[cascardo/linux.git] / net / ceph / osd_client.c

#include <linux/ceph/ceph_debug.h>

#include <linux/module.h>
#include <linux/err.h>
#include <linux/highmem.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#ifdef CONFIG_BLOCK
#include <linux/bio.h>
#endif

#include <linux/ceph/libceph.h>
#include <linux/ceph/osd_client.h>
#include <linux/ceph/messenger.h>
#include <linux/ceph/decode.h>
#include <linux/ceph/auth.h>
#include <linux/ceph/pagelist.h>

#define OSD_OPREPLY_FRONT_LEN   512

static struct kmem_cache        *ceph_osd_request_cache;

static const struct ceph_connection_operations osd_con_ops;

/*
 * Implement client access to distributed object storage cluster.
 *
 * All data objects are stored within a cluster/cloud of OSDs, or
 * "object storage devices."  (Note that Ceph OSDs have _nothing_ to
 * do with the T10 OSD extensions to SCSI.)  Ceph OSDs are simply
 * remote daemons serving up and coordinating consistent and safe
 * access to storage.
 *
 * Cluster membership and the mapping of data objects onto storage devices
 * are described by the osd map.
 *
 * We keep track of pending OSD requests (read, write), resubmit
 * requests to different OSDs when the cluster topology/data layout
 * change, or retry the affected requests when the communications
 * channel with an OSD is reset.
 */

static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req);
static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req);
static void link_linger(struct ceph_osd *osd,
                        struct ceph_osd_linger_request *lreq);
static void unlink_linger(struct ceph_osd *osd,
                          struct ceph_osd_linger_request *lreq);

#if 1
static inline bool rwsem_is_wrlocked(struct rw_semaphore *sem)
{
        bool wrlocked = true;

        if (unlikely(down_read_trylock(sem))) {
                wrlocked = false;
                up_read(sem);
        }

        return wrlocked;
}
static inline void verify_osdc_locked(struct ceph_osd_client *osdc)
{
        WARN_ON(!rwsem_is_locked(&osdc->lock));
}
static inline void verify_osdc_wrlocked(struct ceph_osd_client *osdc)
{
        WARN_ON(!rwsem_is_wrlocked(&osdc->lock));
}
static inline void verify_osd_locked(struct ceph_osd *osd)
{
        struct ceph_osd_client *osdc = osd->o_osdc;

        WARN_ON(!(mutex_is_locked(&osd->lock) &&
                  rwsem_is_locked(&osdc->lock)) &&
                !rwsem_is_wrlocked(&osdc->lock));
}
static inline void verify_lreq_locked(struct ceph_osd_linger_request *lreq)
{
        WARN_ON(!mutex_is_locked(&lreq->lock));
}
#else
static inline void verify_osdc_locked(struct ceph_osd_client *osdc) { }
static inline void verify_osdc_wrlocked(struct ceph_osd_client *osdc) { }
static inline void verify_osd_locked(struct ceph_osd *osd) { }
static inline void verify_lreq_locked(struct ceph_osd_linger_request *lreq) { }
#endif

/*
 * calculate the mapping of a file extent onto an object, and fill out the
 * request accordingly.  shorten extent as necessary if it crosses an
 * object boundary.
 *
 * fill osd op in request message.
 */
static int calc_layout(struct ceph_file_layout *layout, u64 off, u64 *plen,
                        u64 *objnum, u64 *objoff, u64 *objlen)
{
        u64 orig_len = *plen;
        int r;

        /* object extent? */
        r = ceph_calc_file_object_mapping(layout, off, orig_len, objnum,
                                          objoff, objlen);
        if (r < 0)
                return r;
        if (*objlen < orig_len) {
                *plen = *objlen;
                dout(" skipping last %llu, final file extent %llu~%llu\n",
                     orig_len - *plen, off, *plen);
        }

        dout("calc_layout objnum=%llx %llu~%llu\n", *objnum, *objoff, *objlen);

        return 0;
}

static void ceph_osd_data_init(struct ceph_osd_data *osd_data)
{
        memset(osd_data, 0, sizeof (*osd_data));
        osd_data->type = CEPH_OSD_DATA_TYPE_NONE;
}

static void ceph_osd_data_pages_init(struct ceph_osd_data *osd_data,
                        struct page **pages, u64 length, u32 alignment,
                        bool pages_from_pool, bool own_pages)
{
        osd_data->type = CEPH_OSD_DATA_TYPE_PAGES;
        osd_data->pages = pages;
        osd_data->length = length;
        osd_data->alignment = alignment;
        osd_data->pages_from_pool = pages_from_pool;
        osd_data->own_pages = own_pages;
}

static void ceph_osd_data_pagelist_init(struct ceph_osd_data *osd_data,
                        struct ceph_pagelist *pagelist)
{
        osd_data->type = CEPH_OSD_DATA_TYPE_PAGELIST;
        osd_data->pagelist = pagelist;
}

#ifdef CONFIG_BLOCK
static void ceph_osd_data_bio_init(struct ceph_osd_data *osd_data,
                        struct bio *bio, size_t bio_length)
{
        osd_data->type = CEPH_OSD_DATA_TYPE_BIO;
        osd_data->bio = bio;
        osd_data->bio_length = bio_length;
}
#endif /* CONFIG_BLOCK */

#define osd_req_op_data(oreq, whch, typ, fld)                           \
({                                                                      \
        struct ceph_osd_request *__oreq = (oreq);                       \
        unsigned int __whch = (whch);                                   \
        BUG_ON(__whch >= __oreq->r_num_ops);                            \
        &__oreq->r_ops[__whch].typ.fld;                                 \
})

static struct ceph_osd_data *
osd_req_op_raw_data_in(struct ceph_osd_request *osd_req, unsigned int which)
{
        BUG_ON(which >= osd_req->r_num_ops);

        return &osd_req->r_ops[which].raw_data_in;
}

struct ceph_osd_data *
osd_req_op_extent_osd_data(struct ceph_osd_request *osd_req,
                        unsigned int which)
{
        return osd_req_op_data(osd_req, which, extent, osd_data);
}
EXPORT_SYMBOL(osd_req_op_extent_osd_data);

void osd_req_op_raw_data_in_pages(struct ceph_osd_request *osd_req,
                        unsigned int which, struct page **pages,
                        u64 length, u32 alignment,
                        bool pages_from_pool, bool own_pages)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_raw_data_in(osd_req, which);
        ceph_osd_data_pages_init(osd_data, pages, length, alignment,
                                pages_from_pool, own_pages);
}
EXPORT_SYMBOL(osd_req_op_raw_data_in_pages);

void osd_req_op_extent_osd_data_pages(struct ceph_osd_request *osd_req,
                        unsigned int which, struct page **pages,
                        u64 length, u32 alignment,
                        bool pages_from_pool, bool own_pages)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
        ceph_osd_data_pages_init(osd_data, pages, length, alignment,
                                pages_from_pool, own_pages);
}
EXPORT_SYMBOL(osd_req_op_extent_osd_data_pages);

void osd_req_op_extent_osd_data_pagelist(struct ceph_osd_request *osd_req,
                        unsigned int which, struct ceph_pagelist *pagelist)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
        ceph_osd_data_pagelist_init(osd_data, pagelist);
}
EXPORT_SYMBOL(osd_req_op_extent_osd_data_pagelist);

#ifdef CONFIG_BLOCK
void osd_req_op_extent_osd_data_bio(struct ceph_osd_request *osd_req,
                        unsigned int which, struct bio *bio, size_t bio_length)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, extent, osd_data);
        ceph_osd_data_bio_init(osd_data, bio, bio_length);
}
EXPORT_SYMBOL(osd_req_op_extent_osd_data_bio);
#endif /* CONFIG_BLOCK */

static void osd_req_op_cls_request_info_pagelist(
                        struct ceph_osd_request *osd_req,
                        unsigned int which, struct ceph_pagelist *pagelist)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, cls, request_info);
        ceph_osd_data_pagelist_init(osd_data, pagelist);
}

void osd_req_op_cls_request_data_pagelist(
                        struct ceph_osd_request *osd_req,
                        unsigned int which, struct ceph_pagelist *pagelist)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, cls, request_data);
        ceph_osd_data_pagelist_init(osd_data, pagelist);
        osd_req->r_ops[which].cls.indata_len += pagelist->length;
        osd_req->r_ops[which].indata_len += pagelist->length;
}
EXPORT_SYMBOL(osd_req_op_cls_request_data_pagelist);

void osd_req_op_cls_request_data_pages(struct ceph_osd_request *osd_req,
                        unsigned int which, struct page **pages, u64 length,
                        u32 alignment, bool pages_from_pool, bool own_pages)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, cls, request_data);
        ceph_osd_data_pages_init(osd_data, pages, length, alignment,
                                pages_from_pool, own_pages);
        osd_req->r_ops[which].cls.indata_len += length;
        osd_req->r_ops[which].indata_len += length;
}
EXPORT_SYMBOL(osd_req_op_cls_request_data_pages);

void osd_req_op_cls_response_data_pages(struct ceph_osd_request *osd_req,
                        unsigned int which, struct page **pages, u64 length,
                        u32 alignment, bool pages_from_pool, bool own_pages)
{
        struct ceph_osd_data *osd_data;

        osd_data = osd_req_op_data(osd_req, which, cls, response_data);
        ceph_osd_data_pages_init(osd_data, pages, length, alignment,
                                pages_from_pool, own_pages);
}
EXPORT_SYMBOL(osd_req_op_cls_response_data_pages);

static u64 ceph_osd_data_length(struct ceph_osd_data *osd_data)
{
        switch (osd_data->type) {
        case CEPH_OSD_DATA_TYPE_NONE:
                return 0;
        case CEPH_OSD_DATA_TYPE_PAGES:
                return osd_data->length;
        case CEPH_OSD_DATA_TYPE_PAGELIST:
                return (u64)osd_data->pagelist->length;
#ifdef CONFIG_BLOCK
        case CEPH_OSD_DATA_TYPE_BIO:
                return (u64)osd_data->bio_length;
#endif /* CONFIG_BLOCK */
        default:
                WARN(true, "unrecognized data type %d\n", (int)osd_data->type);
                return 0;
        }
}

static void ceph_osd_data_release(struct ceph_osd_data *osd_data)
{
        if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES && osd_data->own_pages) {
                int num_pages;

                num_pages = calc_pages_for((u64)osd_data->alignment,
                                                (u64)osd_data->length);
                ceph_release_page_vector(osd_data->pages, num_pages);
        }
        ceph_osd_data_init(osd_data);
}

static void osd_req_op_data_release(struct ceph_osd_request *osd_req,
                        unsigned int which)
{
        struct ceph_osd_req_op *op;

        BUG_ON(which >= osd_req->r_num_ops);
        op = &osd_req->r_ops[which];

        switch (op->op) {
        case CEPH_OSD_OP_READ:
        case CEPH_OSD_OP_WRITE:
        case CEPH_OSD_OP_WRITEFULL:
                ceph_osd_data_release(&op->extent.osd_data);
                break;
        case CEPH_OSD_OP_CALL:
                ceph_osd_data_release(&op->cls.request_info);
                ceph_osd_data_release(&op->cls.request_data);
                ceph_osd_data_release(&op->cls.response_data);
                break;
        case CEPH_OSD_OP_SETXATTR:
        case CEPH_OSD_OP_CMPXATTR:
                ceph_osd_data_release(&op->xattr.osd_data);
                break;
        case CEPH_OSD_OP_STAT:
                ceph_osd_data_release(&op->raw_data_in);
                break;
        case CEPH_OSD_OP_NOTIFY_ACK:
                ceph_osd_data_release(&op->notify_ack.request_data);
                break;
        case CEPH_OSD_OP_NOTIFY:
                ceph_osd_data_release(&op->notify.request_data);
                ceph_osd_data_release(&op->notify.response_data);
                break;
        default:
                break;
        }
}

/*
 * Assumes @t is zero-initialized.
 */
static void target_init(struct ceph_osd_request_target *t)
{
        ceph_oid_init(&t->base_oid);
        ceph_oloc_init(&t->base_oloc);
        ceph_oid_init(&t->target_oid);
        ceph_oloc_init(&t->target_oloc);

        ceph_osds_init(&t->acting);
        ceph_osds_init(&t->up);
        t->size = -1;
        t->min_size = -1;

        t->osd = CEPH_HOMELESS_OSD;
}

static void target_copy(struct ceph_osd_request_target *dest,
                        const struct ceph_osd_request_target *src)
{
        ceph_oid_copy(&dest->base_oid, &src->base_oid);
        ceph_oloc_copy(&dest->base_oloc, &src->base_oloc);
        ceph_oid_copy(&dest->target_oid, &src->target_oid);
        ceph_oloc_copy(&dest->target_oloc, &src->target_oloc);

        dest->pgid = src->pgid; /* struct */
        dest->pg_num = src->pg_num;
        dest->pg_num_mask = src->pg_num_mask;
        ceph_osds_copy(&dest->acting, &src->acting);
        ceph_osds_copy(&dest->up, &src->up);
        dest->size = src->size;
        dest->min_size = src->min_size;
        dest->sort_bitwise = src->sort_bitwise;

        dest->flags = src->flags;
        dest->paused = src->paused;

        dest->osd = src->osd;
}

static void target_destroy(struct ceph_osd_request_target *t)
{
        ceph_oid_destroy(&t->base_oid);
        ceph_oid_destroy(&t->target_oid);
}

/*
 * requests
 */
static void request_release_checks(struct ceph_osd_request *req)
{
        WARN_ON(!RB_EMPTY_NODE(&req->r_node));
        WARN_ON(!list_empty(&req->r_unsafe_item));
        WARN_ON(req->r_osd);
}

static void ceph_osdc_release_request(struct kref *kref)
{
        struct ceph_osd_request *req = container_of(kref,
                                            struct ceph_osd_request, r_kref);
        unsigned int which;

        dout("%s %p (r_request %p r_reply %p)\n", __func__, req,
             req->r_request, req->r_reply);
        request_release_checks(req);

        if (req->r_request)
                ceph_msg_put(req->r_request);
        if (req->r_reply)
                ceph_msg_put(req->r_reply);

        for (which = 0; which < req->r_num_ops; which++)
                osd_req_op_data_release(req, which);

        target_destroy(&req->r_t);
        ceph_put_snap_context(req->r_snapc);

        if (req->r_mempool)
                mempool_free(req, req->r_osdc->req_mempool);
        else if (req->r_num_ops <= CEPH_OSD_SLAB_OPS)
                kmem_cache_free(ceph_osd_request_cache, req);
        else
                kfree(req);
}

void ceph_osdc_get_request(struct ceph_osd_request *req)
{
        dout("%s %p (was %d)\n", __func__, req,
             atomic_read(&req->r_kref.refcount));
        kref_get(&req->r_kref);
}
EXPORT_SYMBOL(ceph_osdc_get_request);

void ceph_osdc_put_request(struct ceph_osd_request *req)
{
        if (req) {
                dout("%s %p (was %d)\n", __func__, req,
                     atomic_read(&req->r_kref.refcount));
                kref_put(&req->r_kref, ceph_osdc_release_request);
        }
}
EXPORT_SYMBOL(ceph_osdc_put_request);

static void request_init(struct ceph_osd_request *req)
{
        /* req only, each op is zeroed in _osd_req_op_init() */
        memset(req, 0, sizeof(*req));

        kref_init(&req->r_kref);
        init_completion(&req->r_completion);
        init_completion(&req->r_safe_completion);
        RB_CLEAR_NODE(&req->r_node);
        INIT_LIST_HEAD(&req->r_unsafe_item);

        target_init(&req->r_t);
}

/*
 * This is ugly, but it allows us to reuse linger registration and ping
 * requests, keeping the structure of the code around send_linger{_ping}()
 * reasonable.  Setting up a min_nr=2 mempool for each linger request
 * and dealing with copying ops (this blasts req only, watch op remains
 * intact) isn't any better.
 */
static void request_reinit(struct ceph_osd_request *req)
{
        struct ceph_osd_client *osdc = req->r_osdc;
        bool mempool = req->r_mempool;
        unsigned int num_ops = req->r_num_ops;
        u64 snapid = req->r_snapid;
        struct ceph_snap_context *snapc = req->r_snapc;
        bool linger = req->r_linger;
        struct ceph_msg *request_msg = req->r_request;
        struct ceph_msg *reply_msg = req->r_reply;

        dout("%s req %p\n", __func__, req);
        WARN_ON(atomic_read(&req->r_kref.refcount) != 1);
        request_release_checks(req);

        WARN_ON(atomic_read(&request_msg->kref.refcount) != 1);
        WARN_ON(atomic_read(&reply_msg->kref.refcount) != 1);
        target_destroy(&req->r_t);

        request_init(req);
        req->r_osdc = osdc;
        req->r_mempool = mempool;
        req->r_num_ops = num_ops;
        req->r_snapid = snapid;
        req->r_snapc = snapc;
        req->r_linger = linger;
        req->r_request = request_msg;
        req->r_reply = reply_msg;
}

struct ceph_osd_request *ceph_osdc_alloc_request(struct ceph_osd_client *osdc,
                                               struct ceph_snap_context *snapc,
                                               unsigned int num_ops,
                                               bool use_mempool,
                                               gfp_t gfp_flags)
{
        struct ceph_osd_request *req;

        if (use_mempool) {
                BUG_ON(num_ops > CEPH_OSD_SLAB_OPS);
                req = mempool_alloc(osdc->req_mempool, gfp_flags);
        } else if (num_ops <= CEPH_OSD_SLAB_OPS) {
                req = kmem_cache_alloc(ceph_osd_request_cache, gfp_flags);
        } else {
                BUG_ON(num_ops > CEPH_OSD_MAX_OPS);
                req = kmalloc(sizeof(*req) + num_ops * sizeof(req->r_ops[0]),
                              gfp_flags);
        }
        if (unlikely(!req))
                return NULL;

        request_init(req);
        req->r_osdc = osdc;
        req->r_mempool = use_mempool;
        req->r_num_ops = num_ops;
        req->r_snapid = CEPH_NOSNAP;
        req->r_snapc = ceph_get_snap_context(snapc);

        dout("%s req %p\n", __func__, req);
        return req;
}
EXPORT_SYMBOL(ceph_osdc_alloc_request);

int ceph_osdc_alloc_messages(struct ceph_osd_request *req, gfp_t gfp)
{
        struct ceph_osd_client *osdc = req->r_osdc;
        struct ceph_msg *msg;
        int msg_size;

        WARN_ON(ceph_oid_empty(&req->r_base_oid));

        /* create request message */
        msg_size = 4 + 4 + 4; /* client_inc, osdmap_epoch, flags */
        msg_size += 4 + 4 + 4 + 8; /* mtime, reassert_version */
        msg_size += 2 + 4 + 8 + 4 + 4; /* oloc */
        msg_size += 1 + 8 + 4 + 4; /* pgid */
        msg_size += 4 + req->r_base_oid.name_len; /* oid */
        msg_size += 2 + req->r_num_ops * sizeof(struct ceph_osd_op);
        msg_size += 8; /* snapid */
        msg_size += 8; /* snap_seq */
        msg_size += 4 + 8 * (req->r_snapc ? req->r_snapc->num_snaps : 0);
        msg_size += 4; /* retry_attempt */

        if (req->r_mempool)
                msg = ceph_msgpool_get(&osdc->msgpool_op, 0);
        else
                msg = ceph_msg_new(CEPH_MSG_OSD_OP, msg_size, gfp, true);
        if (!msg)
                return -ENOMEM;

        memset(msg->front.iov_base, 0, msg->front.iov_len);
        req->r_request = msg;

        /* create reply message */
        msg_size = OSD_OPREPLY_FRONT_LEN;
        msg_size += req->r_base_oid.name_len;
        msg_size += req->r_num_ops * sizeof(struct ceph_osd_op);

        if (req->r_mempool)
                msg = ceph_msgpool_get(&osdc->msgpool_op_reply, 0);
        else
                msg = ceph_msg_new(CEPH_MSG_OSD_OPREPLY, msg_size, gfp, true);
        if (!msg)
                return -ENOMEM;

        req->r_reply = msg;

        return 0;
}
EXPORT_SYMBOL(ceph_osdc_alloc_messages);

static bool osd_req_opcode_valid(u16 opcode)
{
        switch (opcode) {
#define GENERATE_CASE(op, opcode, str)  case CEPH_OSD_OP_##op: return true;
__CEPH_FORALL_OSD_OPS(GENERATE_CASE)
#undef GENERATE_CASE
        default:
                return false;
        }
}

/*
 * This is an osd op init function for opcodes that have no data or
 * other information associated with them.  It also serves as a
 * common init routine for all the other init functions, below.
 */
static struct ceph_osd_req_op *
_osd_req_op_init(struct ceph_osd_request *osd_req, unsigned int which,
                 u16 opcode, u32 flags)
{
        struct ceph_osd_req_op *op;

        BUG_ON(which >= osd_req->r_num_ops);
        BUG_ON(!osd_req_opcode_valid(opcode));

        op = &osd_req->r_ops[which];
        memset(op, 0, sizeof (*op));
        op->op = opcode;
        op->flags = flags;

        return op;
}

void osd_req_op_init(struct ceph_osd_request *osd_req,
                     unsigned int which, u16 opcode, u32 flags)
{
        (void)_osd_req_op_init(osd_req, which, opcode, flags);
}
EXPORT_SYMBOL(osd_req_op_init);

void osd_req_op_extent_init(struct ceph_osd_request *osd_req,
                                unsigned int which, u16 opcode,
                                u64 offset, u64 length,
                                u64 truncate_size, u32 truncate_seq)
{
        struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which,
                                                      opcode, 0);
        size_t payload_len = 0;

        BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
               opcode != CEPH_OSD_OP_WRITEFULL && opcode != CEPH_OSD_OP_ZERO &&
               opcode != CEPH_OSD_OP_TRUNCATE);

        op->extent.offset = offset;
        op->extent.length = length;
        op->extent.truncate_size = truncate_size;
        op->extent.truncate_seq = truncate_seq;
        if (opcode == CEPH_OSD_OP_WRITE || opcode == CEPH_OSD_OP_WRITEFULL)
                payload_len += length;

        op->indata_len = payload_len;
}
EXPORT_SYMBOL(osd_req_op_extent_init);

void osd_req_op_extent_update(struct ceph_osd_request *osd_req,
                                unsigned int which, u64 length)
{
        struct ceph_osd_req_op *op;
        u64 previous;

        BUG_ON(which >= osd_req->r_num_ops);
        op = &osd_req->r_ops[which];
        previous = op->extent.length;

        if (length == previous)
                return;         /* Nothing to do */
        BUG_ON(length > previous);

        op->extent.length = length;
        op->indata_len -= previous - length;
}
EXPORT_SYMBOL(osd_req_op_extent_update);

void osd_req_op_extent_dup_last(struct ceph_osd_request *osd_req,
                                unsigned int which, u64 offset_inc)
{
        struct ceph_osd_req_op *op, *prev_op;

        BUG_ON(which + 1 >= osd_req->r_num_ops);

        prev_op = &osd_req->r_ops[which];
        op = _osd_req_op_init(osd_req, which + 1, prev_op->op, prev_op->flags);
        /* dup previous one */
        op->indata_len = prev_op->indata_len;
        op->outdata_len = prev_op->outdata_len;
        op->extent = prev_op->extent;
        /* adjust offset */
        op->extent.offset += offset_inc;
        op->extent.length -= offset_inc;

        if (op->op == CEPH_OSD_OP_WRITE || op->op == CEPH_OSD_OP_WRITEFULL)
                op->indata_len -= offset_inc;
}
EXPORT_SYMBOL(osd_req_op_extent_dup_last);

void osd_req_op_cls_init(struct ceph_osd_request *osd_req, unsigned int which,
                        u16 opcode, const char *class, const char *method)
{
        struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which,
                                                      opcode, 0);
        struct ceph_pagelist *pagelist;
        size_t payload_len = 0;
        size_t size;

        BUG_ON(opcode != CEPH_OSD_OP_CALL);

        pagelist = kmalloc(sizeof (*pagelist), GFP_NOFS);
        BUG_ON(!pagelist);
        ceph_pagelist_init(pagelist);

        op->cls.class_name = class;
        size = strlen(class);
        BUG_ON(size > (size_t) U8_MAX);
        op->cls.class_len = size;
        ceph_pagelist_append(pagelist, class, size);
        payload_len += size;

        op->cls.method_name = method;
        size = strlen(method);
        BUG_ON(size > (size_t) U8_MAX);
        op->cls.method_len = size;
        ceph_pagelist_append(pagelist, method, size);
        payload_len += size;

        osd_req_op_cls_request_info_pagelist(osd_req, which, pagelist);

        op->indata_len = payload_len;
}
EXPORT_SYMBOL(osd_req_op_cls_init);

int osd_req_op_xattr_init(struct ceph_osd_request *osd_req, unsigned int which,
                          u16 opcode, const char *name, const void *value,
                          size_t size, u8 cmp_op, u8 cmp_mode)
{
        struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which,
                                                      opcode, 0);
        struct ceph_pagelist *pagelist;
        size_t payload_len;

        BUG_ON(opcode != CEPH_OSD_OP_SETXATTR && opcode != CEPH_OSD_OP_CMPXATTR);

        pagelist = kmalloc(sizeof(*pagelist), GFP_NOFS);
        if (!pagelist)
                return -ENOMEM;

        ceph_pagelist_init(pagelist);

        payload_len = strlen(name);
        op->xattr.name_len = payload_len;
        ceph_pagelist_append(pagelist, name, payload_len);

        op->xattr.value_len = size;
        ceph_pagelist_append(pagelist, value, size);
        payload_len += size;

        op->xattr.cmp_op = cmp_op;
        op->xattr.cmp_mode = cmp_mode;

        ceph_osd_data_pagelist_init(&op->xattr.osd_data, pagelist);
        op->indata_len = payload_len;
        return 0;
}
EXPORT_SYMBOL(osd_req_op_xattr_init);

/*
 * @watch_opcode: CEPH_OSD_WATCH_OP_*
 */
static void osd_req_op_watch_init(struct ceph_osd_request *req, int which,
                                  u64 cookie, u8 watch_opcode)
{
        struct ceph_osd_req_op *op;

        op = _osd_req_op_init(req, which, CEPH_OSD_OP_WATCH, 0);
        op->watch.cookie = cookie;
        op->watch.op = watch_opcode;
        op->watch.gen = 0;
}

void osd_req_op_alloc_hint_init(struct ceph_osd_request *osd_req,
                                unsigned int which,
                                u64 expected_object_size,
                                u64 expected_write_size)
{
        struct ceph_osd_req_op *op = _osd_req_op_init(osd_req, which,
                                                      CEPH_OSD_OP_SETALLOCHINT,
                                                      0);

        op->alloc_hint.expected_object_size = expected_object_size;
        op->alloc_hint.expected_write_size = expected_write_size;

        /*
         * CEPH_OSD_OP_SETALLOCHINT op is advisory and therefore deemed
         * not worth a feature bit.  Set FAILOK per-op flag to make
         * sure older osds don't trip over an unsupported opcode.
         */
        op->flags |= CEPH_OSD_OP_FLAG_FAILOK;
}
EXPORT_SYMBOL(osd_req_op_alloc_hint_init);

static void ceph_osdc_msg_data_add(struct ceph_msg *msg,
                                struct ceph_osd_data *osd_data)
{
        u64 length = ceph_osd_data_length(osd_data);

        if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGES) {
                BUG_ON(length > (u64) SIZE_MAX);
                if (length)
                        ceph_msg_data_add_pages(msg, osd_data->pages,
                                        length, osd_data->alignment);
        } else if (osd_data->type == CEPH_OSD_DATA_TYPE_PAGELIST) {
                BUG_ON(!length);
                ceph_msg_data_add_pagelist(msg, osd_data->pagelist);
#ifdef CONFIG_BLOCK
        } else if (osd_data->type == CEPH_OSD_DATA_TYPE_BIO) {
                ceph_msg_data_add_bio(msg, osd_data->bio, length);
#endif
        } else {
                BUG_ON(osd_data->type != CEPH_OSD_DATA_TYPE_NONE);
        }
}

static u32 osd_req_encode_op(struct ceph_osd_op *dst,
                             const struct ceph_osd_req_op *src)
{
        if (WARN_ON(!osd_req_opcode_valid(src->op))) {
                pr_err("unrecognized osd opcode %d\n", src->op);

                return 0;
        }

        switch (src->op) {
        case CEPH_OSD_OP_STAT:
                break;
        case CEPH_OSD_OP_READ:
        case CEPH_OSD_OP_WRITE:
        case CEPH_OSD_OP_WRITEFULL:
        case CEPH_OSD_OP_ZERO:
        case CEPH_OSD_OP_TRUNCATE:
                dst->extent.offset = cpu_to_le64(src->extent.offset);
                dst->extent.length = cpu_to_le64(src->extent.length);
                dst->extent.truncate_size =
                        cpu_to_le64(src->extent.truncate_size);
                dst->extent.truncate_seq =
                        cpu_to_le32(src->extent.truncate_seq);
                break;
        case CEPH_OSD_OP_CALL:
                dst->cls.class_len = src->cls.class_len;
                dst->cls.method_len = src->cls.method_len;
                dst->cls.indata_len = cpu_to_le32(src->cls.indata_len);
                break;
        case CEPH_OSD_OP_STARTSYNC:
                break;
        case CEPH_OSD_OP_WATCH:
                dst->watch.cookie = cpu_to_le64(src->watch.cookie);
                dst->watch.ver = cpu_to_le64(0);
                dst->watch.op = src->watch.op;
                dst->watch.gen = cpu_to_le32(src->watch.gen);
                break;
        case CEPH_OSD_OP_NOTIFY_ACK:
                break;
        case CEPH_OSD_OP_NOTIFY:
                dst->notify.cookie = cpu_to_le64(src->notify.cookie);
                break;
        case CEPH_OSD_OP_SETALLOCHINT:
                dst->alloc_hint.expected_object_size =
                    cpu_to_le64(src->alloc_hint.expected_object_size);
                dst->alloc_hint.expected_write_size =
                    cpu_to_le64(src->alloc_hint.expected_write_size);
                break;
        case CEPH_OSD_OP_SETXATTR:
        case CEPH_OSD_OP_CMPXATTR:
                dst->xattr.name_len = cpu_to_le32(src->xattr.name_len);
                dst->xattr.value_len = cpu_to_le32(src->xattr.value_len);
                dst->xattr.cmp_op = src->xattr.cmp_op;
                dst->xattr.cmp_mode = src->xattr.cmp_mode;
                break;
        case CEPH_OSD_OP_CREATE:
        case CEPH_OSD_OP_DELETE:
                break;
        default:
                pr_err("unsupported osd opcode %s\n",
                        ceph_osd_op_name(src->op));
                WARN_ON(1);

                return 0;
        }

        dst->op = cpu_to_le16(src->op);
        dst->flags = cpu_to_le32(src->flags);
        dst->payload_len = cpu_to_le32(src->indata_len);

        return src->indata_len;
}

/*
 * build new request AND message, calculate layout, and adjust file
 * extent as needed.
 *
 * if the file was recently truncated, we include information about its
 * old and new size so that the object can be updated appropriately.  (we
 * avoid synchronously deleting truncated objects because it's slow.)
 *
 * if @do_sync, include a 'startsync' command so that the osd will flush
 * data quickly.
 */
struct ceph_osd_request *ceph_osdc_new_request(struct ceph_osd_client *osdc,
                                               struct ceph_file_layout *layout,
                                               struct ceph_vino vino,
                                               u64 off, u64 *plen,
                                               unsigned int which, int num_ops,
                                               int opcode, int flags,
                                               struct ceph_snap_context *snapc,
                                               u32 truncate_seq,
                                               u64 truncate_size,
                                               bool use_mempool)
{
        struct ceph_osd_request *req;
        u64 objnum = 0;
        u64 objoff = 0;
        u64 objlen = 0;
        int r;

        BUG_ON(opcode != CEPH_OSD_OP_READ && opcode != CEPH_OSD_OP_WRITE &&
               opcode != CEPH_OSD_OP_ZERO && opcode != CEPH_OSD_OP_TRUNCATE &&
               opcode != CEPH_OSD_OP_CREATE && opcode != CEPH_OSD_OP_DELETE);

        req = ceph_osdc_alloc_request(osdc, snapc, num_ops, use_mempool,
                                        GFP_NOFS);
        if (!req) {
                r = -ENOMEM;
                goto fail;
        }

        /* calculate max write size */
        r = calc_layout(layout, off, plen, &objnum, &objoff, &objlen);
        if (r)
                goto fail;

        if (opcode == CEPH_OSD_OP_CREATE || opcode == CEPH_OSD_OP_DELETE) {
                osd_req_op_init(req, which, opcode, 0);
        } else {
                u32 object_size = le32_to_cpu(layout->fl_object_size);
                u32 object_base = off - objoff;
                if (!(truncate_seq == 1 && truncate_size == -1ULL)) {
                        if (truncate_size <= object_base) {
                                truncate_size = 0;
                        } else {
                                truncate_size -= object_base;
                                if (truncate_size > object_size)
                                        truncate_size = object_size;
                        }
                }
                osd_req_op_extent_init(req, which, opcode, objoff, objlen,
                                       truncate_size, truncate_seq);
        }

        req->r_flags = flags;
        req->r_base_oloc.pool = ceph_file_layout_pg_pool(*layout);
        ceph_oid_printf(&req->r_base_oid, "%llx.%08llx", vino.ino, objnum);

        req->r_snapid = vino.snap;
        if (flags & CEPH_OSD_FLAG_WRITE)
                req->r_data_offset = off;

        r = ceph_osdc_alloc_messages(req, GFP_NOFS);
        if (r)
                goto fail;

        return req;

fail:
        ceph_osdc_put_request(req);
        return ERR_PTR(r);
}
EXPORT_SYMBOL(ceph_osdc_new_request);

/*
 * We keep osd requests in an rbtree, sorted by ->r_tid.
 */
DEFINE_RB_FUNCS(request, struct ceph_osd_request, r_tid, r_node)

static bool osd_homeless(struct ceph_osd *osd)
{
        return osd->o_osd == CEPH_HOMELESS_OSD;
}

static bool osd_registered(struct ceph_osd *osd)
{
        verify_osdc_locked(osd->o_osdc);

        return !RB_EMPTY_NODE(&osd->o_node);
}

/*
 * Assumes @osd is zero-initialized.
 */
static void osd_init(struct ceph_osd *osd)
{
        atomic_set(&osd->o_ref, 1);
        RB_CLEAR_NODE(&osd->o_node);
        osd->o_requests = RB_ROOT;
        osd->o_linger_requests = RB_ROOT;
        INIT_LIST_HEAD(&osd->o_osd_lru);
        INIT_LIST_HEAD(&osd->o_keepalive_item);
        osd->o_incarnation = 1;
        mutex_init(&osd->lock);
}

static void osd_cleanup(struct ceph_osd *osd)
{
        WARN_ON(!RB_EMPTY_NODE(&osd->o_node));
        WARN_ON(!RB_EMPTY_ROOT(&osd->o_requests));
        WARN_ON(!RB_EMPTY_ROOT(&osd->o_linger_requests));
        WARN_ON(!list_empty(&osd->o_osd_lru));
        WARN_ON(!list_empty(&osd->o_keepalive_item));

        if (osd->o_auth.authorizer) {
                WARN_ON(osd_homeless(osd));
                ceph_auth_destroy_authorizer(osd->o_auth.authorizer);
        }
}

/*
 * Track open sessions with osds.
 */
static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
{
        struct ceph_osd *osd;

        WARN_ON(onum == CEPH_HOMELESS_OSD);

        osd = kzalloc(sizeof(*osd), GFP_NOIO | __GFP_NOFAIL);
        osd_init(osd);
        osd->o_osdc = osdc;
        osd->o_osd = onum;

        ceph_con_init(&osd->o_con, osd, &osd_con_ops, &osdc->client->msgr);

        return osd;
}

static struct ceph_osd *get_osd(struct ceph_osd *osd)
{
        if (atomic_inc_not_zero(&osd->o_ref)) {
                dout("get_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref)-1,
                     atomic_read(&osd->o_ref));
                return osd;
        } else {
                dout("get_osd %p FAIL\n", osd);
                return NULL;
        }
}

static void put_osd(struct ceph_osd *osd)
{
        dout("put_osd %p %d -> %d\n", osd, atomic_read(&osd->o_ref),
             atomic_read(&osd->o_ref) - 1);
        if (atomic_dec_and_test(&osd->o_ref)) {
                osd_cleanup(osd);
                kfree(osd);
        }
}

DEFINE_RB_FUNCS(osd, struct ceph_osd, o_osd, o_node)

static void __move_osd_to_lru(struct ceph_osd *osd)
{
        struct ceph_osd_client *osdc = osd->o_osdc;

        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);
        BUG_ON(!list_empty(&osd->o_osd_lru));

        spin_lock(&osdc->osd_lru_lock);
        list_add_tail(&osd->o_osd_lru, &osdc->osd_lru);
        spin_unlock(&osdc->osd_lru_lock);

        osd->lru_ttl = jiffies + osdc->client->options->osd_idle_ttl;
}

static void maybe_move_osd_to_lru(struct ceph_osd *osd)
{
        if (RB_EMPTY_ROOT(&osd->o_requests) &&
            RB_EMPTY_ROOT(&osd->o_linger_requests))
                __move_osd_to_lru(osd);
}

static void __remove_osd_from_lru(struct ceph_osd *osd)
{
        struct ceph_osd_client *osdc = osd->o_osdc;

        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);

        spin_lock(&osdc->osd_lru_lock);
        if (!list_empty(&osd->o_osd_lru))
                list_del_init(&osd->o_osd_lru);
        spin_unlock(&osdc->osd_lru_lock);
}

/*
 * Close the connection and assign any leftover requests to the
 * homeless session.
 */
static void close_osd(struct ceph_osd *osd)
{
        struct ceph_osd_client *osdc = osd->o_osdc;
        struct rb_node *n;

        verify_osdc_wrlocked(osdc);
        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);

        ceph_con_close(&osd->o_con);

        for (n = rb_first(&osd->o_requests); n; ) {
                struct ceph_osd_request *req =
                    rb_entry(n, struct ceph_osd_request, r_node);

                n = rb_next(n); /* unlink_request() */

                dout(" reassigning req %p tid %llu\n", req, req->r_tid);
                unlink_request(osd, req);
                link_request(&osdc->homeless_osd, req);
        }
        for (n = rb_first(&osd->o_linger_requests); n; ) {
                struct ceph_osd_linger_request *lreq =
                    rb_entry(n, struct ceph_osd_linger_request, node);

                n = rb_next(n); /* unlink_linger() */

                dout(" reassigning lreq %p linger_id %llu\n", lreq,
                     lreq->linger_id);
                unlink_linger(osd, lreq);
                link_linger(&osdc->homeless_osd, lreq);
        }

        __remove_osd_from_lru(osd);
        erase_osd(&osdc->osds, osd);
        put_osd(osd);
}

/*
 * reset osd connect
 */
static int reopen_osd(struct ceph_osd *osd)
{
        struct ceph_entity_addr *peer_addr;

        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);

        if (RB_EMPTY_ROOT(&osd->o_requests) &&
            RB_EMPTY_ROOT(&osd->o_linger_requests)) {
                close_osd(osd);
                return -ENODEV;
        }

        peer_addr = &osd->o_osdc->osdmap->osd_addr[osd->o_osd];
        if (!memcmp(peer_addr, &osd->o_con.peer_addr, sizeof (*peer_addr)) &&
                        !ceph_con_opened(&osd->o_con)) {
                struct rb_node *n;

                dout("osd addr hasn't changed and connection never opened, "
                     "letting msgr retry\n");
                /* touch each r_stamp for handle_timeout()'s benfit */
                for (n = rb_first(&osd->o_requests); n; n = rb_next(n)) {
                        struct ceph_osd_request *req =
                            rb_entry(n, struct ceph_osd_request, r_node);
                        req->r_stamp = jiffies;
                }

                return -EAGAIN;
        }

        ceph_con_close(&osd->o_con);
        ceph_con_open(&osd->o_con, CEPH_ENTITY_TYPE_OSD, osd->o_osd, peer_addr);
        osd->o_incarnation++;

        return 0;
}

static struct ceph_osd *lookup_create_osd(struct ceph_osd_client *osdc, int o,
                                          bool wrlocked)
{
        struct ceph_osd *osd;

        if (wrlocked)
                verify_osdc_wrlocked(osdc);
        else
                verify_osdc_locked(osdc);

        if (o != CEPH_HOMELESS_OSD)
                osd = lookup_osd(&osdc->osds, o);
        else
                osd = &osdc->homeless_osd;
        if (!osd) {
                if (!wrlocked)
                        return ERR_PTR(-EAGAIN);

                osd = create_osd(osdc, o);
                insert_osd(&osdc->osds, osd);
                ceph_con_open(&osd->o_con, CEPH_ENTITY_TYPE_OSD, osd->o_osd,
                              &osdc->osdmap->osd_addr[osd->o_osd]);
        }

        dout("%s osdc %p osd%d -> osd %p\n", __func__, osdc, o, osd);
        return osd;
}

/*
 * Create request <-> OSD session relation.
 *
 * @req has to be assigned a tid, @osd may be homeless.
 */
static void link_request(struct ceph_osd *osd, struct ceph_osd_request *req)
{
        verify_osd_locked(osd);
        WARN_ON(!req->r_tid || req->r_osd);
        dout("%s osd %p osd%d req %p tid %llu\n", __func__, osd, osd->o_osd,
             req, req->r_tid);

        if (!osd_homeless(osd))
                __remove_osd_from_lru(osd);
        else
                atomic_inc(&osd->o_osdc->num_homeless);

        get_osd(osd);
        insert_request(&osd->o_requests, req);
        req->r_osd = osd;
}

static void unlink_request(struct ceph_osd *osd, struct ceph_osd_request *req)
{
        verify_osd_locked(osd);
        WARN_ON(req->r_osd != osd);
        dout("%s osd %p osd%d req %p tid %llu\n", __func__, osd, osd->o_osd,
             req, req->r_tid);

        req->r_osd = NULL;
        erase_request(&osd->o_requests, req);
        put_osd(osd);

        if (!osd_homeless(osd))
                maybe_move_osd_to_lru(osd);
        else
                atomic_dec(&osd->o_osdc->num_homeless);
}

static bool __pool_full(struct ceph_pg_pool_info *pi)
{
        return pi->flags & CEPH_POOL_FLAG_FULL;
}

static bool have_pool_full(struct ceph_osd_client *osdc)
{
        struct rb_node *n;

        for (n = rb_first(&osdc->osdmap->pg_pools); n; n = rb_next(n)) {
                struct ceph_pg_pool_info *pi =
                    rb_entry(n, struct ceph_pg_pool_info, node);

                if (__pool_full(pi))
                        return true;
        }

        return false;
}

static bool pool_full(struct ceph_osd_client *osdc, s64 pool_id)
{
        struct ceph_pg_pool_info *pi;

        pi = ceph_pg_pool_by_id(osdc->osdmap, pool_id);
        if (!pi)
                return false;

        return __pool_full(pi);
}

/*
 * Returns whether a request should be blocked from being sent
 * based on the current osdmap and osd_client settings.
 */
static bool target_should_be_paused(struct ceph_osd_client *osdc,
                                    const struct ceph_osd_request_target *t,
                                    struct ceph_pg_pool_info *pi)
{
        bool pauserd = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD);
        bool pausewr = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR) ||
                       ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) ||
                       __pool_full(pi);

        WARN_ON(pi->id != t->base_oloc.pool);
        return (t->flags & CEPH_OSD_FLAG_READ && pauserd) ||
               (t->flags & CEPH_OSD_FLAG_WRITE && pausewr);
}

enum calc_target_result {
        CALC_TARGET_NO_ACTION = 0,
        CALC_TARGET_NEED_RESEND,
        CALC_TARGET_POOL_DNE,
};

static enum calc_target_result calc_target(struct ceph_osd_client *osdc,
                                           struct ceph_osd_request_target *t,
                                           u32 *last_force_resend,
                                           bool any_change)
{
        struct ceph_pg_pool_info *pi;
        struct ceph_pg pgid, last_pgid;
        struct ceph_osds up, acting;
        bool force_resend = false;
        bool need_check_tiering = false;
        bool need_resend = false;
        bool sort_bitwise = ceph_osdmap_flag(osdc->osdmap,
                                             CEPH_OSDMAP_SORTBITWISE);
        enum calc_target_result ct_res;
        int ret;

        pi = ceph_pg_pool_by_id(osdc->osdmap, t->base_oloc.pool);
        if (!pi) {
                t->osd = CEPH_HOMELESS_OSD;
                ct_res = CALC_TARGET_POOL_DNE;
                goto out;
        }

        if (osdc->osdmap->epoch == pi->last_force_request_resend) {
                if (last_force_resend &&
                    *last_force_resend < pi->last_force_request_resend) {
                        *last_force_resend = pi->last_force_request_resend;
                        force_resend = true;
                } else if (!last_force_resend) {
                        force_resend = true;
                }
        }
        if (ceph_oid_empty(&t->target_oid) || force_resend) {
                ceph_oid_copy(&t->target_oid, &t->base_oid);
                need_check_tiering = true;
        }
        if (ceph_oloc_empty(&t->target_oloc) || force_resend) {
                ceph_oloc_copy(&t->target_oloc, &t->base_oloc);
                need_check_tiering = true;
        }

        if (need_check_tiering &&
            (t->flags & CEPH_OSD_FLAG_IGNORE_OVERLAY) == 0) {
                if (t->flags & CEPH_OSD_FLAG_READ && pi->read_tier >= 0)
                        t->target_oloc.pool = pi->read_tier;
                if (t->flags & CEPH_OSD_FLAG_WRITE && pi->write_tier >= 0)
                        t->target_oloc.pool = pi->write_tier;
        }

        ret = ceph_object_locator_to_pg(osdc->osdmap, &t->target_oid,
                                        &t->target_oloc, &pgid);
        if (ret) {
                WARN_ON(ret != -ENOENT);
                t->osd = CEPH_HOMELESS_OSD;
                ct_res = CALC_TARGET_POOL_DNE;
                goto out;
        }
        last_pgid.pool = pgid.pool;
        last_pgid.seed = ceph_stable_mod(pgid.seed, t->pg_num, t->pg_num_mask);

        ceph_pg_to_up_acting_osds(osdc->osdmap, &pgid, &up, &acting);
        if (any_change &&
            ceph_is_new_interval(&t->acting,
                                 &acting,
                                 &t->up,
                                 &up,
                                 t->size,
                                 pi->size,
                                 t->min_size,
                                 pi->min_size,
                                 t->pg_num,
                                 pi->pg_num,
                                 t->sort_bitwise,
                                 sort_bitwise,
                                 &last_pgid))
                force_resend = true;

        if (t->paused && !target_should_be_paused(osdc, t, pi)) {
                t->paused = false;
                need_resend = true;
        }

        if (ceph_pg_compare(&t->pgid, &pgid) ||
            ceph_osds_changed(&t->acting, &acting, any_change) ||
            force_resend) {
                t->pgid = pgid; /* struct */
                ceph_osds_copy(&t->acting, &acting);
                ceph_osds_copy(&t->up, &up);
                t->size = pi->size;
                t->min_size = pi->min_size;
                t->pg_num = pi->pg_num;
                t->pg_num_mask = pi->pg_num_mask;
                t->sort_bitwise = sort_bitwise;

                t->osd = acting.primary;
                need_resend = true;
        }

        ct_res = need_resend ? CALC_TARGET_NEED_RESEND : CALC_TARGET_NO_ACTION;
out:
        dout("%s t %p -> ct_res %d osd %d\n", __func__, t, ct_res, t->osd);
        return ct_res;
}

static void setup_request_data(struct ceph_osd_request *req,
                               struct ceph_msg *msg)
{
        u32 data_len = 0;
        int i;

        if (!list_empty(&msg->data))
                return;

        WARN_ON(msg->data_length);
        for (i = 0; i < req->r_num_ops; i++) {
                struct ceph_osd_req_op *op = &req->r_ops[i];

                switch (op->op) {
                /* request */
                case CEPH_OSD_OP_WRITE:
                case CEPH_OSD_OP_WRITEFULL:
                        WARN_ON(op->indata_len != op->extent.length);
                        ceph_osdc_msg_data_add(msg, &op->extent.osd_data);
                        break;
                case CEPH_OSD_OP_SETXATTR:
                case CEPH_OSD_OP_CMPXATTR:
                        WARN_ON(op->indata_len != op->xattr.name_len +
                                                  op->xattr.value_len);
                        ceph_osdc_msg_data_add(msg, &op->xattr.osd_data);
                        break;
                case CEPH_OSD_OP_NOTIFY_ACK:
                        ceph_osdc_msg_data_add(msg,
                                               &op->notify_ack.request_data);
                        break;

                /* reply */
                case CEPH_OSD_OP_STAT:
                        ceph_osdc_msg_data_add(req->r_reply,
                                               &op->raw_data_in);
                        break;
                case CEPH_OSD_OP_READ:
                        ceph_osdc_msg_data_add(req->r_reply,
                                               &op->extent.osd_data);
                        break;

                /* both */
                case CEPH_OSD_OP_CALL:
                        WARN_ON(op->indata_len != op->cls.class_len +
                                                  op->cls.method_len +
                                                  op->cls.indata_len);
                        ceph_osdc_msg_data_add(msg, &op->cls.request_info);
                        /* optional, can be NONE */
                        ceph_osdc_msg_data_add(msg, &op->cls.request_data);
                        /* optional, can be NONE */
                        ceph_osdc_msg_data_add(req->r_reply,
                                               &op->cls.response_data);
                        break;
                case CEPH_OSD_OP_NOTIFY:
                        ceph_osdc_msg_data_add(msg,
                                               &op->notify.request_data);
                        ceph_osdc_msg_data_add(req->r_reply,
                                               &op->notify.response_data);
                        break;
                }

                data_len += op->indata_len;
        }

        WARN_ON(data_len != msg->data_length);
}

static void encode_request(struct ceph_osd_request *req, struct ceph_msg *msg)
{
        void *p = msg->front.iov_base;
        void *const end = p + msg->front_alloc_len;
        u32 data_len = 0;
        int i;

        if (req->r_flags & CEPH_OSD_FLAG_WRITE) {
                /* snapshots aren't writeable */
                WARN_ON(req->r_snapid != CEPH_NOSNAP);
        } else {
                WARN_ON(req->r_mtime.tv_sec || req->r_mtime.tv_nsec ||
                        req->r_data_offset || req->r_snapc);
        }

        setup_request_data(req, msg);

        ceph_encode_32(&p, 1); /* client_inc, always 1 */
        ceph_encode_32(&p, req->r_osdc->osdmap->epoch);
        ceph_encode_32(&p, req->r_flags);
        ceph_encode_timespec(p, &req->r_mtime);
        p += sizeof(struct ceph_timespec);
        /* aka reassert_version */
        memcpy(p, &req->r_replay_version, sizeof(req->r_replay_version));
        p += sizeof(req->r_replay_version);

        /* oloc */
        ceph_encode_8(&p, 4);
        ceph_encode_8(&p, 4);
        ceph_encode_32(&p, 8 + 4 + 4);
        ceph_encode_64(&p, req->r_t.target_oloc.pool);
        ceph_encode_32(&p, -1); /* preferred */
        ceph_encode_32(&p, 0); /* key len */

        /* pgid */
        ceph_encode_8(&p, 1);
        ceph_encode_64(&p, req->r_t.pgid.pool);
        ceph_encode_32(&p, req->r_t.pgid.seed);
        ceph_encode_32(&p, -1); /* preferred */

        /* oid */
        ceph_encode_32(&p, req->r_t.target_oid.name_len);
        memcpy(p, req->r_t.target_oid.name, req->r_t.target_oid.name_len);
        p += req->r_t.target_oid.name_len;

        /* ops, can imply data */
        ceph_encode_16(&p, req->r_num_ops);
        for (i = 0; i < req->r_num_ops; i++) {
                data_len += osd_req_encode_op(p, &req->r_ops[i]);
                p += sizeof(struct ceph_osd_op);
        }

        ceph_encode_64(&p, req->r_snapid); /* snapid */
        if (req->r_snapc) {
                ceph_encode_64(&p, req->r_snapc->seq);
                ceph_encode_32(&p, req->r_snapc->num_snaps);
                for (i = 0; i < req->r_snapc->num_snaps; i++)
                        ceph_encode_64(&p, req->r_snapc->snaps[i]);
        } else {
                ceph_encode_64(&p, 0); /* snap_seq */
                ceph_encode_32(&p, 0); /* snaps len */
        }

        ceph_encode_32(&p, req->r_attempts); /* retry_attempt */

        BUG_ON(p > end);
        msg->front.iov_len = p - msg->front.iov_base;
        msg->hdr.version = cpu_to_le16(4); /* MOSDOp v4 */
        msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
        msg->hdr.data_len = cpu_to_le32(data_len);
        /*
         * The header "data_off" is a hint to the receiver allowing it
         * to align received data into its buffers such that there's no
         * need to re-copy it before writing it to disk (direct I/O).
         */
        msg->hdr.data_off = cpu_to_le16(req->r_data_offset);

        dout("%s req %p oid %*pE oid_len %d front %zu data %u\n", __func__,
             req, req->r_t.target_oid.name_len, req->r_t.target_oid.name,
             req->r_t.target_oid.name_len, msg->front.iov_len, data_len);
}

/*
 * @req has to be assigned a tid and registered.
 */
static void send_request(struct ceph_osd_request *req)
{
        struct ceph_osd *osd = req->r_osd;

        verify_osd_locked(osd);
        WARN_ON(osd->o_osd != req->r_t.osd);

        /*
         * We may have a previously queued request message hanging
         * around.  Cancel it to avoid corrupting the msgr.
         */
        if (req->r_sent)
                ceph_msg_revoke(req->r_request);

        req->r_flags |= CEPH_OSD_FLAG_KNOWN_REDIR;
        if (req->r_attempts)
                req->r_flags |= CEPH_OSD_FLAG_RETRY;
        else
                WARN_ON(req->r_flags & CEPH_OSD_FLAG_RETRY);

        encode_request(req, req->r_request);

        dout("%s req %p tid %llu to pg %llu.%x osd%d flags 0x%x attempt %d\n",
             __func__, req, req->r_tid, req->r_t.pgid.pool, req->r_t.pgid.seed,
             req->r_t.osd, req->r_flags, req->r_attempts);

        req->r_t.paused = false;
        req->r_stamp = jiffies;
        req->r_attempts++;

        req->r_sent = osd->o_incarnation;
        req->r_request->hdr.tid = cpu_to_le64(req->r_tid);
        ceph_con_send(&osd->o_con, ceph_msg_get(req->r_request));
}

static void maybe_request_map(struct ceph_osd_client *osdc)
{
        bool continuous = false;

        verify_osdc_locked(osdc);
        WARN_ON(!osdc->osdmap->epoch);

        if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) ||
            ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD) ||
            ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR)) {
                dout("%s osdc %p continuous\n", __func__, osdc);
                continuous = true;
        } else {
                dout("%s osdc %p onetime\n", __func__, osdc);
        }

        if (ceph_monc_want_map(&osdc->client->monc, CEPH_SUB_OSDMAP,
                               osdc->osdmap->epoch + 1, continuous))
                ceph_monc_renew_subs(&osdc->client->monc);
}

static void __submit_request(struct ceph_osd_request *req, bool wrlocked)
{
        struct ceph_osd_client *osdc = req->r_osdc;
        struct ceph_osd *osd;
        bool need_send = false;
        bool promoted = false;

        WARN_ON(req->r_tid || req->r_got_reply);
        dout("%s req %p wrlocked %d\n", __func__, req, wrlocked);

again:
        calc_target(osdc, &req->r_t, &req->r_last_force_resend, false);
        osd = lookup_create_osd(osdc, req->r_t.osd, wrlocked);
        if (IS_ERR(osd)) {
                WARN_ON(PTR_ERR(osd) != -EAGAIN || wrlocked);
                goto promote;
        }

        if ((req->r_flags & CEPH_OSD_FLAG_WRITE) &&
            ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR)) {
                dout("req %p pausewr\n", req);
                req->r_t.paused = true;
                maybe_request_map(osdc);
        } else if ((req->r_flags & CEPH_OSD_FLAG_READ) &&
                   ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD)) {
                dout("req %p pauserd\n", req);
                req->r_t.paused = true;
                maybe_request_map(osdc);
        } else if ((req->r_flags & CEPH_OSD_FLAG_WRITE) &&
                   !(req->r_flags & (CEPH_OSD_FLAG_FULL_TRY |
                                     CEPH_OSD_FLAG_FULL_FORCE)) &&
                   (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) ||
                    pool_full(osdc, req->r_t.base_oloc.pool))) {
                dout("req %p full/pool_full\n", req);
                pr_warn_ratelimited("FULL or reached pool quota\n");
                req->r_t.paused = true;
                maybe_request_map(osdc);
        } else if (!osd_homeless(osd)) {
                need_send = true;
        } else {
                maybe_request_map(osdc);
        }

        mutex_lock(&osd->lock);
        /*
         * Assign the tid atomically with send_request() to protect
         * multiple writes to the same object from racing with each
         * other, resulting in out of order ops on the OSDs.
         */
        req->r_tid = atomic64_inc_return(&osdc->last_tid);
        link_request(osd, req);
        if (need_send)
                send_request(req);
        mutex_unlock(&osd->lock);

        if (promoted)
                downgrade_write(&osdc->lock);
        return;

promote:
        up_read(&osdc->lock);
        down_write(&osdc->lock);
        wrlocked = true;
        promoted = true;
        goto again;
}

static void account_request(struct ceph_osd_request *req)
{
        unsigned int mask = CEPH_OSD_FLAG_ACK | CEPH_OSD_FLAG_ONDISK;

        if (req->r_flags & CEPH_OSD_FLAG_READ) {
                WARN_ON(req->r_flags & mask);
                req->r_flags |= CEPH_OSD_FLAG_ACK;
        } else if (req->r_flags & CEPH_OSD_FLAG_WRITE)
                WARN_ON(!(req->r_flags & mask));
        else
                WARN_ON(1);

        WARN_ON(req->r_unsafe_callback && (req->r_flags & mask) != mask);
        atomic_inc(&req->r_osdc->num_requests);
}

static void submit_request(struct ceph_osd_request *req, bool wrlocked)
{
        ceph_osdc_get_request(req);
        account_request(req);
        __submit_request(req, wrlocked);
}

static void __finish_request(struct ceph_osd_request *req)
{
        struct ceph_osd_client *osdc = req->r_osdc;
        struct ceph_osd *osd = req->r_osd;

        verify_osd_locked(osd);
        dout("%s req %p tid %llu\n", __func__, req, req->r_tid);

        unlink_request(osd, req);
        atomic_dec(&osdc->num_requests);

        /*
         * If an OSD has failed or returned and a request has been sent
         * twice, it's possible to get a reply and end up here while the
         * request message is queued for delivery.  We will ignore the
         * reply, so not a big deal, but better to try and catch it.
         */
        ceph_msg_revoke(req->r_request);
        ceph_msg_revoke_incoming(req->r_reply);
}

static void finish_request(struct ceph_osd_request *req)
{
        __finish_request(req);
        ceph_osdc_put_request(req);
}

static void __complete_request(struct ceph_osd_request *req)
{
        if (req->r_callback)
                req->r_callback(req);
        else
                complete_all(&req->r_completion);
}

static void cancel_request(struct ceph_osd_request *req)
{
        dout("%s req %p tid %llu\n", __func__, req, req->r_tid);

        finish_request(req);
}

/*
 * lingering requests, watch/notify v2 infrastructure
 */
static void linger_release(struct kref *kref)
{
        struct ceph_osd_linger_request *lreq =
            container_of(kref, struct ceph_osd_linger_request, kref);

        dout("%s lreq %p reg_req %p ping_req %p\n", __func__, lreq,
             lreq->reg_req, lreq->ping_req);
        WARN_ON(!RB_EMPTY_NODE(&lreq->node));
        WARN_ON(!RB_EMPTY_NODE(&lreq->osdc_node));
        WARN_ON(!list_empty(&lreq->scan_item));
        WARN_ON(lreq->osd);

        if (lreq->reg_req)
                ceph_osdc_put_request(lreq->reg_req);
        if (lreq->ping_req)
                ceph_osdc_put_request(lreq->ping_req);
        target_destroy(&lreq->t);
        kfree(lreq);
}

static void linger_put(struct ceph_osd_linger_request *lreq)
{
        if (lreq)
                kref_put(&lreq->kref, linger_release);
}

static struct ceph_osd_linger_request *
linger_get(struct ceph_osd_linger_request *lreq)
{
        kref_get(&lreq->kref);
        return lreq;
}

static struct ceph_osd_linger_request *
linger_alloc(struct ceph_osd_client *osdc)
{
        struct ceph_osd_linger_request *lreq;

        lreq = kzalloc(sizeof(*lreq), GFP_NOIO);
        if (!lreq)
                return NULL;

        kref_init(&lreq->kref);
        mutex_init(&lreq->lock);
        RB_CLEAR_NODE(&lreq->node);
        RB_CLEAR_NODE(&lreq->osdc_node);
        INIT_LIST_HEAD(&lreq->scan_item);
        init_completion(&lreq->reg_commit_wait);
        init_completion(&lreq->notify_finish_wait);

        lreq->osdc = osdc;
        target_init(&lreq->t);

        dout("%s lreq %p\n", __func__, lreq);
        return lreq;
}

DEFINE_RB_INSDEL_FUNCS(linger, struct ceph_osd_linger_request, linger_id, node)
DEFINE_RB_FUNCS(linger_osdc, struct ceph_osd_linger_request, linger_id, osdc_node)

/*
 * Create linger request <-> OSD session relation.
 *
 * @lreq has to be registered, @osd may be homeless.
 */
static void link_linger(struct ceph_osd *osd,
                        struct ceph_osd_linger_request *lreq)
{
        verify_osd_locked(osd);
        WARN_ON(!lreq->linger_id || lreq->osd);
        dout("%s osd %p osd%d lreq %p linger_id %llu\n", __func__, osd,
             osd->o_osd, lreq, lreq->linger_id);

        if (!osd_homeless(osd))
                __remove_osd_from_lru(osd);
        else
                atomic_inc(&osd->o_osdc->num_homeless);

        get_osd(osd);
        insert_linger(&osd->o_linger_requests, lreq);
        lreq->osd = osd;
}

static void unlink_linger(struct ceph_osd *osd,
                          struct ceph_osd_linger_request *lreq)
{
        verify_osd_locked(osd);
        WARN_ON(lreq->osd != osd);
        dout("%s osd %p osd%d lreq %p linger_id %llu\n", __func__, osd,
             osd->o_osd, lreq, lreq->linger_id);

        lreq->osd = NULL;
        erase_linger(&osd->o_linger_requests, lreq);
        put_osd(osd);

        if (!osd_homeless(osd))
                maybe_move_osd_to_lru(osd);
        else
                atomic_dec(&osd->o_osdc->num_homeless);
}

static bool __linger_registered(struct ceph_osd_linger_request *lreq)
{
        verify_osdc_locked(lreq->osdc);

        return !RB_EMPTY_NODE(&lreq->osdc_node);
}

static bool linger_registered(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;
        bool registered;

        down_read(&osdc->lock);
        registered = __linger_registered(lreq);
        up_read(&osdc->lock);

        return registered;
}

static void linger_register(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;

        verify_osdc_wrlocked(osdc);
        WARN_ON(lreq->linger_id);

        linger_get(lreq);
        lreq->linger_id = ++osdc->last_linger_id;
        insert_linger_osdc(&osdc->linger_requests, lreq);
}

static void linger_unregister(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;

        verify_osdc_wrlocked(osdc);

        erase_linger_osdc(&osdc->linger_requests, lreq);
        linger_put(lreq);
}

static void cancel_linger_request(struct ceph_osd_request *req)
{
        struct ceph_osd_linger_request *lreq = req->r_priv;

        WARN_ON(!req->r_linger);
        cancel_request(req);
        linger_put(lreq);
}

struct linger_work {
        struct work_struct work;
        struct ceph_osd_linger_request *lreq;

        union {
                struct {
                        u64 notify_id;
                        u64 notifier_id;
                        void *payload; /* points into @msg front */
                        size_t payload_len;

                        struct ceph_msg *msg; /* for ceph_msg_put() */
                } notify;
                struct {
                        int err;
                } error;
        };
};

static struct linger_work *lwork_alloc(struct ceph_osd_linger_request *lreq,
                                       work_func_t workfn)
{
        struct linger_work *lwork;

        lwork = kzalloc(sizeof(*lwork), GFP_NOIO);
        if (!lwork)
                return NULL;

        INIT_WORK(&lwork->work, workfn);
        lwork->lreq = linger_get(lreq);

        return lwork;
}

static void lwork_free(struct linger_work *lwork)
{
        struct ceph_osd_linger_request *lreq = lwork->lreq;

        linger_put(lreq);
        kfree(lwork);
}

static void lwork_queue(struct linger_work *lwork)
{
        struct ceph_osd_linger_request *lreq = lwork->lreq;
        struct ceph_osd_client *osdc = lreq->osdc;

        verify_lreq_locked(lreq);
        queue_work(osdc->notify_wq, &lwork->work);
}

static void do_watch_notify(struct work_struct *w)
{
        struct linger_work *lwork = container_of(w, struct linger_work, work);
        struct ceph_osd_linger_request *lreq = lwork->lreq;

        if (!linger_registered(lreq)) {
                dout("%s lreq %p not registered\n", __func__, lreq);
                goto out;
        }

        WARN_ON(!lreq->is_watch);
        dout("%s lreq %p notify_id %llu notifier_id %llu payload_len %zu\n",
             __func__, lreq, lwork->notify.notify_id, lwork->notify.notifier_id,
             lwork->notify.payload_len);
        lreq->wcb(lreq->data, lwork->notify.notify_id, lreq->linger_id,
                  lwork->notify.notifier_id, lwork->notify.payload,
                  lwork->notify.payload_len);

out:
        ceph_msg_put(lwork->notify.msg);
        lwork_free(lwork);
}

static void do_watch_error(struct work_struct *w)
{
        struct linger_work *lwork = container_of(w, struct linger_work, work);
        struct ceph_osd_linger_request *lreq = lwork->lreq;

        if (!linger_registered(lreq)) {
                dout("%s lreq %p not registered\n", __func__, lreq);
                goto out;
        }

        dout("%s lreq %p err %d\n", __func__, lreq, lwork->error.err);
        lreq->errcb(lreq->data, lreq->linger_id, lwork->error.err);

out:
        lwork_free(lwork);
}

static void queue_watch_error(struct ceph_osd_linger_request *lreq)
{
        struct linger_work *lwork;

        lwork = lwork_alloc(lreq, do_watch_error);
        if (!lwork) {
                pr_err("failed to allocate error-lwork\n");
                return;
        }

        lwork->error.err = lreq->last_error;
        lwork_queue(lwork);
}

static void linger_reg_commit_complete(struct ceph_osd_linger_request *lreq,
                                       int result)
{
        if (!completion_done(&lreq->reg_commit_wait)) {
                lreq->reg_commit_error = (result <= 0 ? result : 0);
                complete_all(&lreq->reg_commit_wait);
        }
}

static void linger_commit_cb(struct ceph_osd_request *req)
{
        struct ceph_osd_linger_request *lreq = req->r_priv;

        mutex_lock(&lreq->lock);
        dout("%s lreq %p linger_id %llu result %d\n", __func__, lreq,
             lreq->linger_id, req->r_result);
        WARN_ON(!__linger_registered(lreq));
        linger_reg_commit_complete(lreq, req->r_result);
        lreq->committed = true;

        if (!lreq->is_watch) {
                struct ceph_osd_data *osd_data =
                    osd_req_op_data(req, 0, notify, response_data);
                void *p = page_address(osd_data->pages[0]);

                WARN_ON(req->r_ops[0].op != CEPH_OSD_OP_NOTIFY ||
                        osd_data->type != CEPH_OSD_DATA_TYPE_PAGES);

                /* make note of the notify_id */
                if (req->r_ops[0].outdata_len >= sizeof(u64)) {
                        lreq->notify_id = ceph_decode_64(&p);
                        dout("lreq %p notify_id %llu\n", lreq,
                             lreq->notify_id);
                } else {
                        dout("lreq %p no notify_id\n", lreq);
                }
        }

        mutex_unlock(&lreq->lock);
        linger_put(lreq);
}

static int normalize_watch_error(int err)
{
        /*
         * Translate ENOENT -> ENOTCONN so that a delete->disconnection
         * notification and a failure to reconnect because we raced with
         * the delete appear the same to the user.
         */
        if (err == -ENOENT)
                err = -ENOTCONN;

        return err;
}

static void linger_reconnect_cb(struct ceph_osd_request *req)
{
        struct ceph_osd_linger_request *lreq = req->r_priv;

        mutex_lock(&lreq->lock);
        dout("%s lreq %p linger_id %llu result %d last_error %d\n", __func__,
             lreq, lreq->linger_id, req->r_result, lreq->last_error);
        if (req->r_result < 0) {
                if (!lreq->last_error) {
                        lreq->last_error = normalize_watch_error(req->r_result);
                        queue_watch_error(lreq);
                }
        }

        mutex_unlock(&lreq->lock);
        linger_put(lreq);
}

static void send_linger(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_request *req = lreq->reg_req;
        struct ceph_osd_req_op *op = &req->r_ops[0];

        verify_osdc_wrlocked(req->r_osdc);
        dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);

        if (req->r_osd)
                cancel_linger_request(req);

        request_reinit(req);
        ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
        ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
        req->r_flags = lreq->t.flags;
        req->r_mtime = lreq->mtime;

        mutex_lock(&lreq->lock);
        if (lreq->is_watch && lreq->committed) {
                WARN_ON(op->op != CEPH_OSD_OP_WATCH ||
                        op->watch.cookie != lreq->linger_id);
                op->watch.op = CEPH_OSD_WATCH_OP_RECONNECT;
                op->watch.gen = ++lreq->register_gen;
                dout("lreq %p reconnect register_gen %u\n", lreq,
                     op->watch.gen);
                req->r_callback = linger_reconnect_cb;
        } else {
                if (!lreq->is_watch)
                        lreq->notify_id = 0;
                else
                        WARN_ON(op->watch.op != CEPH_OSD_WATCH_OP_WATCH);
                dout("lreq %p register\n", lreq);
                req->r_callback = linger_commit_cb;
        }
        mutex_unlock(&lreq->lock);

        req->r_priv = linger_get(lreq);
        req->r_linger = true;

        submit_request(req, true);
}

static void linger_ping_cb(struct ceph_osd_request *req)
{
        struct ceph_osd_linger_request *lreq = req->r_priv;

        mutex_lock(&lreq->lock);
        dout("%s lreq %p linger_id %llu result %d ping_sent %lu last_error %d\n",
             __func__, lreq, lreq->linger_id, req->r_result, lreq->ping_sent,
             lreq->last_error);
        if (lreq->register_gen == req->r_ops[0].watch.gen) {
                if (req->r_result && !lreq->last_error) {
                        lreq->last_error = normalize_watch_error(req->r_result);
                        queue_watch_error(lreq);
                }
        } else {
                dout("lreq %p register_gen %u ignoring old pong %u\n", lreq,
                     lreq->register_gen, req->r_ops[0].watch.gen);
        }

        mutex_unlock(&lreq->lock);
        linger_put(lreq);
}

static void send_linger_ping(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;
        struct ceph_osd_request *req = lreq->ping_req;
        struct ceph_osd_req_op *op = &req->r_ops[0];

        if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD)) {
                dout("%s PAUSERD\n", __func__);
                return;
        }

        lreq->ping_sent = jiffies;
        dout("%s lreq %p linger_id %llu ping_sent %lu register_gen %u\n",
             __func__, lreq, lreq->linger_id, lreq->ping_sent,
             lreq->register_gen);

        if (req->r_osd)
                cancel_linger_request(req);

        request_reinit(req);
        target_copy(&req->r_t, &lreq->t);

        WARN_ON(op->op != CEPH_OSD_OP_WATCH ||
                op->watch.cookie != lreq->linger_id ||
                op->watch.op != CEPH_OSD_WATCH_OP_PING);
        op->watch.gen = lreq->register_gen;
        req->r_callback = linger_ping_cb;
        req->r_priv = linger_get(lreq);
        req->r_linger = true;

        ceph_osdc_get_request(req);
        account_request(req);
        req->r_tid = atomic64_inc_return(&osdc->last_tid);
        link_request(lreq->osd, req);
        send_request(req);
}

static void linger_submit(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;
        struct ceph_osd *osd;

        calc_target(osdc, &lreq->t, &lreq->last_force_resend, false);
        osd = lookup_create_osd(osdc, lreq->t.osd, true);
        link_linger(osd, lreq);

        send_linger(lreq);
}

/*
 * @lreq has to be both registered and linked.
 */
static void __linger_cancel(struct ceph_osd_linger_request *lreq)
{
        if (lreq->is_watch && lreq->ping_req->r_osd)
                cancel_linger_request(lreq->ping_req);
        if (lreq->reg_req->r_osd)
                cancel_linger_request(lreq->reg_req);
        unlink_linger(lreq->osd, lreq);
        linger_unregister(lreq);
}

static void linger_cancel(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;

        down_write(&osdc->lock);
        if (__linger_registered(lreq))
                __linger_cancel(lreq);
        up_write(&osdc->lock);
}

static int linger_reg_commit_wait(struct ceph_osd_linger_request *lreq)
{
        int ret;

        dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
        ret = wait_for_completion_interruptible(&lreq->reg_commit_wait);
        return ret ?: lreq->reg_commit_error;
}

static int linger_notify_finish_wait(struct ceph_osd_linger_request *lreq)
{
        int ret;

        dout("%s lreq %p linger_id %llu\n", __func__, lreq, lreq->linger_id);
        ret = wait_for_completion_interruptible(&lreq->notify_finish_wait);
        return ret ?: lreq->notify_finish_error;
}

/*
 * Timeout callback, called every N seconds.  When 1 or more OSD
 * requests has been active for more than N seconds, we send a keepalive
 * (tag + timestamp) to its OSD to ensure any communications channel
 * reset is detected.
 */
static void handle_timeout(struct work_struct *work)
{
        struct ceph_osd_client *osdc =
                container_of(work, struct ceph_osd_client, timeout_work.work);
        struct ceph_options *opts = osdc->client->options;
        unsigned long cutoff = jiffies - opts->osd_keepalive_timeout;
        LIST_HEAD(slow_osds);
        struct rb_node *n, *p;

        dout("%s osdc %p\n", __func__, osdc);
        down_write(&osdc->lock);

        /*
         * ping osds that are a bit slow.  this ensures that if there
         * is a break in the TCP connection we will notice, and reopen
         * a connection with that osd (from the fault callback).
         */
        for (n = rb_first(&osdc->osds); n; n = rb_next(n)) {
                struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);
                bool found = false;

                for (p = rb_first(&osd->o_requests); p; p = rb_next(p)) {
                        struct ceph_osd_request *req =
                            rb_entry(p, struct ceph_osd_request, r_node);

                        if (time_before(req->r_stamp, cutoff)) {
                                dout(" req %p tid %llu on osd%d is laggy\n",
                                     req, req->r_tid, osd->o_osd);
                                found = true;
                        }
                }
                for (p = rb_first(&osd->o_linger_requests); p; p = rb_next(p)) {
                        struct ceph_osd_linger_request *lreq =
                            rb_entry(p, struct ceph_osd_linger_request, node);

                        dout(" lreq %p linger_id %llu is served by osd%d\n",
                             lreq, lreq->linger_id, osd->o_osd);
                        found = true;

                        mutex_lock(&lreq->lock);
                        if (lreq->is_watch && lreq->committed && !lreq->last_error)
                                send_linger_ping(lreq);
                        mutex_unlock(&lreq->lock);
                }

                if (found)
                        list_move_tail(&osd->o_keepalive_item, &slow_osds);
        }

        if (atomic_read(&osdc->num_homeless) || !list_empty(&slow_osds))
                maybe_request_map(osdc);

        while (!list_empty(&slow_osds)) {
                struct ceph_osd *osd = list_first_entry(&slow_osds,
                                                        struct ceph_osd,
                                                        o_keepalive_item);
                list_del_init(&osd->o_keepalive_item);
                ceph_con_keepalive(&osd->o_con);
        }

        up_write(&osdc->lock);
        schedule_delayed_work(&osdc->timeout_work,
                              osdc->client->options->osd_keepalive_timeout);
}

static void handle_osds_timeout(struct work_struct *work)
{
        struct ceph_osd_client *osdc =
                container_of(work, struct ceph_osd_client,
                             osds_timeout_work.work);
        unsigned long delay = osdc->client->options->osd_idle_ttl / 4;
        struct ceph_osd *osd, *nosd;

        dout("%s osdc %p\n", __func__, osdc);
        down_write(&osdc->lock);
        list_for_each_entry_safe(osd, nosd, &osdc->osd_lru, o_osd_lru) {
                if (time_before(jiffies, osd->lru_ttl))
                        break;

                WARN_ON(!RB_EMPTY_ROOT(&osd->o_requests));
                WARN_ON(!RB_EMPTY_ROOT(&osd->o_linger_requests));
                close_osd(osd);
        }

        up_write(&osdc->lock);
        schedule_delayed_work(&osdc->osds_timeout_work,
                              round_jiffies_relative(delay));
}

static int ceph_oloc_decode(void **p, void *end,
                            struct ceph_object_locator *oloc)
{
        u8 struct_v, struct_cv;
        u32 len;
        void *struct_end;
        int ret = 0;

        ceph_decode_need(p, end, 1 + 1 + 4, e_inval);
        struct_v = ceph_decode_8(p);
        struct_cv = ceph_decode_8(p);
        if (struct_v < 3) {
                pr_warn("got v %d < 3 cv %d of ceph_object_locator\n",
                        struct_v, struct_cv);
                goto e_inval;
        }
        if (struct_cv > 6) {
                pr_warn("got v %d cv %d > 6 of ceph_object_locator\n",
                        struct_v, struct_cv);
                goto e_inval;
        }
        len = ceph_decode_32(p);
        ceph_decode_need(p, end, len, e_inval);
        struct_end = *p + len;

        oloc->pool = ceph_decode_64(p);
        *p += 4; /* skip preferred */

        len = ceph_decode_32(p);
        if (len > 0) {
                pr_warn("ceph_object_locator::key is set\n");
                goto e_inval;
        }

        if (struct_v >= 5) {
                len = ceph_decode_32(p);
                if (len > 0) {
                        pr_warn("ceph_object_locator::nspace is set\n");
                        goto e_inval;
                }
        }

        if (struct_v >= 6) {
                s64 hash = ceph_decode_64(p);
                if (hash != -1) {
                        pr_warn("ceph_object_locator::hash is set\n");
                        goto e_inval;
                }
        }

        /* skip the rest */
        *p = struct_end;
out:
        return ret;

e_inval:
        ret = -EINVAL;
        goto out;
}

static int ceph_redirect_decode(void **p, void *end,
                                struct ceph_request_redirect *redir)
{
        u8 struct_v, struct_cv;
        u32 len;
        void *struct_end;
        int ret;

        ceph_decode_need(p, end, 1 + 1 + 4, e_inval);
        struct_v = ceph_decode_8(p);
        struct_cv = ceph_decode_8(p);
        if (struct_cv > 1) {
                pr_warn("got v %d cv %d > 1 of ceph_request_redirect\n",
                        struct_v, struct_cv);
                goto e_inval;
        }
        len = ceph_decode_32(p);
        ceph_decode_need(p, end, len, e_inval);
        struct_end = *p + len;

        ret = ceph_oloc_decode(p, end, &redir->oloc);
        if (ret)
                goto out;

        len = ceph_decode_32(p);
        if (len > 0) {
                pr_warn("ceph_request_redirect::object_name is set\n");
                goto e_inval;
        }

        len = ceph_decode_32(p);
        *p += len; /* skip osd_instructions */

        /* skip the rest */
        *p = struct_end;
out:
        return ret;

e_inval:
        ret = -EINVAL;
        goto out;
}

struct MOSDOpReply {
        struct ceph_pg pgid;
        u64 flags;
        int result;
        u32 epoch;
        int num_ops;
        u32 outdata_len[CEPH_OSD_MAX_OPS];
        s32 rval[CEPH_OSD_MAX_OPS];
        int retry_attempt;
        struct ceph_eversion replay_version;
        u64 user_version;
        struct ceph_request_redirect redirect;
};

static int decode_MOSDOpReply(const struct ceph_msg *msg, struct MOSDOpReply *m)
{
        void *p = msg->front.iov_base;
        void *const end = p + msg->front.iov_len;
        u16 version = le16_to_cpu(msg->hdr.version);
        struct ceph_eversion bad_replay_version;
        u8 decode_redir;
        u32 len;
        int ret;
        int i;

        ceph_decode_32_safe(&p, end, len, e_inval);
        ceph_decode_need(&p, end, len, e_inval);
        p += len; /* skip oid */

        ret = ceph_decode_pgid(&p, end, &m->pgid);
        if (ret)
                return ret;

        ceph_decode_64_safe(&p, end, m->flags, e_inval);
        ceph_decode_32_safe(&p, end, m->result, e_inval);
        ceph_decode_need(&p, end, sizeof(bad_replay_version), e_inval);
        memcpy(&bad_replay_version, p, sizeof(bad_replay_version));
        p += sizeof(bad_replay_version);
        ceph_decode_32_safe(&p, end, m->epoch, e_inval);

        ceph_decode_32_safe(&p, end, m->num_ops, e_inval);
        if (m->num_ops > ARRAY_SIZE(m->outdata_len))
                goto e_inval;

        ceph_decode_need(&p, end, m->num_ops * sizeof(struct ceph_osd_op),
                         e_inval);
        for (i = 0; i < m->num_ops; i++) {
                struct ceph_osd_op *op = p;

                m->outdata_len[i] = le32_to_cpu(op->payload_len);
                p += sizeof(*op);
        }

        ceph_decode_32_safe(&p, end, m->retry_attempt, e_inval);
        for (i = 0; i < m->num_ops; i++)
                ceph_decode_32_safe(&p, end, m->rval[i], e_inval);

        if (version >= 5) {
                ceph_decode_need(&p, end, sizeof(m->replay_version), e_inval);
                memcpy(&m->replay_version, p, sizeof(m->replay_version));
                p += sizeof(m->replay_version);
                ceph_decode_64_safe(&p, end, m->user_version, e_inval);
        } else {
                m->replay_version = bad_replay_version; /* struct */
                m->user_version = le64_to_cpu(m->replay_version.version);
        }

        if (version >= 6) {
                if (version >= 7)
                        ceph_decode_8_safe(&p, end, decode_redir, e_inval);
                else
                        decode_redir = 1;
        } else {
                decode_redir = 0;
        }

        if (decode_redir) {
                ret = ceph_redirect_decode(&p, end, &m->redirect);
                if (ret)
                        return ret;
        } else {
                ceph_oloc_init(&m->redirect.oloc);
        }

        return 0;

e_inval:
        return -EINVAL;
}

/*
 * We are done with @req if
 *   - @m is a safe reply, or
 *   - @m is an unsafe reply and we didn't want a safe one
 */
static bool done_request(const struct ceph_osd_request *req,
                         const struct MOSDOpReply *m)
{
        return (m->result < 0 ||
                (m->flags & CEPH_OSD_FLAG_ONDISK) ||
                !(req->r_flags & CEPH_OSD_FLAG_ONDISK));
}

/*
 * handle osd op reply.  either call the callback if it is specified,
 * or do the completion to wake up the waiting thread.
 *
 * ->r_unsafe_callback is set?  yes                     no
 *
 * first reply is OK (needed    r_cb/r_completion,      r_cb/r_completion,
 * any or needed/got safe)      r_safe_completion       r_safe_completion
 *
 * first reply is unsafe        r_unsafe_cb(true)       (nothing)
 *
 * when we get the safe reply   r_unsafe_cb(false),     r_cb/r_completion,
 *                              r_safe_completion       r_safe_completion
 */
static void handle_reply(struct ceph_osd *osd, struct ceph_msg *msg)
{
        struct ceph_osd_client *osdc = osd->o_osdc;
        struct ceph_osd_request *req;
        struct MOSDOpReply m;
        u64 tid = le64_to_cpu(msg->hdr.tid);
        u32 data_len = 0;
        bool already_acked;
        int ret;
        int i;

        dout("%s msg %p tid %llu\n", __func__, msg, tid);

        down_read(&osdc->lock);
        if (!osd_registered(osd)) {
                dout("%s osd%d unknown\n", __func__, osd->o_osd);
                goto out_unlock_osdc;
        }
        WARN_ON(osd->o_osd != le64_to_cpu(msg->hdr.src.num));

        mutex_lock(&osd->lock);
        req = lookup_request(&osd->o_requests, tid);
        if (!req) {
                dout("%s osd%d tid %llu unknown\n", __func__, osd->o_osd, tid);
                goto out_unlock_session;
        }

        ret = decode_MOSDOpReply(msg, &m);
        if (ret) {
                pr_err("failed to decode MOSDOpReply for tid %llu: %d\n",
                       req->r_tid, ret);
                ceph_msg_dump(msg);
                goto fail_request;
        }
        dout("%s req %p tid %llu flags 0x%llx pgid %llu.%x epoch %u attempt %d v %u'%llu uv %llu\n",
             __func__, req, req->r_tid, m.flags, m.pgid.pool, m.pgid.seed,
             m.epoch, m.retry_attempt, le32_to_cpu(m.replay_version.epoch),
             le64_to_cpu(m.replay_version.version), m.user_version);

        if (m.retry_attempt >= 0) {
                if (m.retry_attempt != req->r_attempts - 1) {
                        dout("req %p tid %llu retry_attempt %d != %d, ignoring\n",
                             req, req->r_tid, m.retry_attempt,
                             req->r_attempts - 1);
                        goto out_unlock_session;
                }
        } else {
                WARN_ON(1); /* MOSDOpReply v4 is assumed */
        }

        if (!ceph_oloc_empty(&m.redirect.oloc)) {
                dout("req %p tid %llu redirect pool %lld\n", req, req->r_tid,
                     m.redirect.oloc.pool);
                unlink_request(osd, req);
                mutex_unlock(&osd->lock);

                ceph_oloc_copy(&req->r_t.target_oloc, &m.redirect.oloc);
                req->r_flags |= CEPH_OSD_FLAG_REDIRECTED;
                req->r_tid = 0;
                __submit_request(req, false);
                goto out_unlock_osdc;
        }

        if (m.num_ops != req->r_num_ops) {
                pr_err("num_ops %d != %d for tid %llu\n", m.num_ops,
                       req->r_num_ops, req->r_tid);
                goto fail_request;
        }
        for (i = 0; i < req->r_num_ops; i++) {
                dout(" req %p tid %llu op %d rval %d len %u\n", req,
                     req->r_tid, i, m.rval[i], m.outdata_len[i]);
                req->r_ops[i].rval = m.rval[i];
                req->r_ops[i].outdata_len = m.outdata_len[i];
                data_len += m.outdata_len[i];
        }
        if (data_len != le32_to_cpu(msg->hdr.data_len)) {
                pr_err("sum of lens %u != %u for tid %llu\n", data_len,
                       le32_to_cpu(msg->hdr.data_len), req->r_tid);
                goto fail_request;
        }
        dout("%s req %p tid %llu acked %d result %d data_len %u\n", __func__,
             req, req->r_tid, req->r_got_reply, m.result, data_len);

        already_acked = req->r_got_reply;
        if (!already_acked) {
                req->r_result = m.result ?: data_len;
                req->r_replay_version = m.replay_version; /* struct */
                req->r_got_reply = true;
        } else if (!(m.flags & CEPH_OSD_FLAG_ONDISK)) {
                dout("req %p tid %llu dup ack\n", req, req->r_tid);
                goto out_unlock_session;
        }

        if (done_request(req, &m)) {
                __finish_request(req);
                if (req->r_linger) {
                        WARN_ON(req->r_unsafe_callback);
                        dout("req %p tid %llu cb (locked)\n", req, req->r_tid);
                        __complete_request(req);
                }
        }

        mutex_unlock(&osd->lock);
        up_read(&osdc->lock);

        if (done_request(req, &m)) {
                if (already_acked && req->r_unsafe_callback) {
                        dout("req %p tid %llu safe-cb\n", req, req->r_tid);
                        req->r_unsafe_callback(req, false);
                } else if (!req->r_linger) {
                        dout("req %p tid %llu cb\n", req, req->r_tid);
                        __complete_request(req);
                }
        } else {
                if (req->r_unsafe_callback) {
                        dout("req %p tid %llu unsafe-cb\n", req, req->r_tid);
                        req->r_unsafe_callback(req, true);
                } else {
                        WARN_ON(1);
                }
        }
        if (m.flags & CEPH_OSD_FLAG_ONDISK)
                complete_all(&req->r_safe_completion);

        ceph_osdc_put_request(req);
        return;

fail_request:
        req->r_result = -EIO;
        __finish_request(req);
        __complete_request(req);
        complete_all(&req->r_safe_completion);
out_unlock_session:
        mutex_unlock(&osd->lock);
out_unlock_osdc:
        up_read(&osdc->lock);
}

static void set_pool_was_full(struct ceph_osd_client *osdc)
{
        struct rb_node *n;

        for (n = rb_first(&osdc->osdmap->pg_pools); n; n = rb_next(n)) {
                struct ceph_pg_pool_info *pi =
                    rb_entry(n, struct ceph_pg_pool_info, node);

                pi->was_full = __pool_full(pi);
        }
}

static bool pool_cleared_full(struct ceph_osd_client *osdc, s64 pool_id)
{
        struct ceph_pg_pool_info *pi;

        pi = ceph_pg_pool_by_id(osdc->osdmap, pool_id);
        if (!pi)
                return false;

        return pi->was_full && !__pool_full(pi);
}

static enum calc_target_result
recalc_linger_target(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_client *osdc = lreq->osdc;
        enum calc_target_result ct_res;

        ct_res = calc_target(osdc, &lreq->t, &lreq->last_force_resend, true);
        if (ct_res == CALC_TARGET_NEED_RESEND) {
                struct ceph_osd *osd;

                osd = lookup_create_osd(osdc, lreq->t.osd, true);
                if (osd != lreq->osd) {
                        unlink_linger(lreq->osd, lreq);
                        link_linger(osd, lreq);
                }
        }

        return ct_res;
}

/*
 * Requeue requests whose mapping to an OSD has changed.
 */
static void scan_requests(struct ceph_osd *osd,
                          bool force_resend,
                          bool cleared_full,
                          bool check_pool_cleared_full,
                          struct rb_root *need_resend,
                          struct list_head *need_resend_linger)
{
        struct ceph_osd_client *osdc = osd->o_osdc;
        struct rb_node *n;
        bool force_resend_writes;

        for (n = rb_first(&osd->o_linger_requests); n; ) {
                struct ceph_osd_linger_request *lreq =
                    rb_entry(n, struct ceph_osd_linger_request, node);
                enum calc_target_result ct_res;

                n = rb_next(n); /* recalc_linger_target() */

                dout("%s lreq %p linger_id %llu\n", __func__, lreq,
                     lreq->linger_id);
                ct_res = recalc_linger_target(lreq);
                switch (ct_res) {
                case CALC_TARGET_NO_ACTION:
                        force_resend_writes = cleared_full ||
                            (check_pool_cleared_full &&
                             pool_cleared_full(osdc, lreq->t.base_oloc.pool));
                        if (!force_resend && !force_resend_writes)
                                break;

                        /* fall through */
                case CALC_TARGET_NEED_RESEND:
                        /*
                         * scan_requests() for the previous epoch(s)
                         * may have already added it to the list, since
                         * it's not unlinked here.
                         */
                        if (list_empty(&lreq->scan_item))
                                list_add_tail(&lreq->scan_item, need_resend_linger);
                        break;
                case CALC_TARGET_POOL_DNE:
                        break;
                }
        }

        for (n = rb_first(&osd->o_requests); n; ) {
                struct ceph_osd_request *req =
                    rb_entry(n, struct ceph_osd_request, r_node);
                enum calc_target_result ct_res;

                n = rb_next(n); /* unlink_request() */

                dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
                ct_res = calc_target(osdc, &req->r_t,
                                     &req->r_last_force_resend, false);
                switch (ct_res) {
                case CALC_TARGET_NO_ACTION:
                        force_resend_writes = cleared_full ||
                            (check_pool_cleared_full &&
                             pool_cleared_full(osdc, req->r_t.base_oloc.pool));
                        if (!force_resend &&
                            (!(req->r_flags & CEPH_OSD_FLAG_WRITE) ||
                             !force_resend_writes))
                                break;

                        /* fall through */
                case CALC_TARGET_NEED_RESEND:
                        unlink_request(osd, req);
                        insert_request(need_resend, req);
                        break;
                case CALC_TARGET_POOL_DNE:
                        break;
                }
        }
}

static int handle_one_map(struct ceph_osd_client *osdc,
                          void *p, void *end, bool incremental,
                          struct rb_root *need_resend,
                          struct list_head *need_resend_linger)
{
        struct ceph_osdmap *newmap;
        struct rb_node *n;
        bool skipped_map = false;
        bool was_full;

        was_full = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL);
        set_pool_was_full(osdc);

        if (incremental)
                newmap = osdmap_apply_incremental(&p, end, osdc->osdmap);
        else
                newmap = ceph_osdmap_decode(&p, end);
        if (IS_ERR(newmap))
                return PTR_ERR(newmap);

        if (newmap != osdc->osdmap) {
                /*
                 * Preserve ->was_full before destroying the old map.
                 * For pools that weren't in the old map, ->was_full
                 * should be false.
                 */
                for (n = rb_first(&newmap->pg_pools); n; n = rb_next(n)) {
                        struct ceph_pg_pool_info *pi =
                            rb_entry(n, struct ceph_pg_pool_info, node);
                        struct ceph_pg_pool_info *old_pi;

                        old_pi = ceph_pg_pool_by_id(osdc->osdmap, pi->id);
                        if (old_pi)
                                pi->was_full = old_pi->was_full;
                        else
                                WARN_ON(pi->was_full);
                }

                if (osdc->osdmap->epoch &&
                    osdc->osdmap->epoch + 1 < newmap->epoch) {
                        WARN_ON(incremental);
                        skipped_map = true;
                }

                ceph_osdmap_destroy(osdc->osdmap);
                osdc->osdmap = newmap;
        }

        was_full &= !ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL);
        scan_requests(&osdc->homeless_osd, skipped_map, was_full, true,
                      need_resend, need_resend_linger);

        for (n = rb_first(&osdc->osds); n; ) {
                struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);

                n = rb_next(n); /* close_osd() */

                scan_requests(osd, skipped_map, was_full, true, need_resend,
                              need_resend_linger);
                if (!ceph_osd_is_up(osdc->osdmap, osd->o_osd) ||
                    memcmp(&osd->o_con.peer_addr,
                           ceph_osd_addr(osdc->osdmap, osd->o_osd),
                           sizeof(struct ceph_entity_addr)))
                        close_osd(osd);
        }

        return 0;
}

static void kick_requests(struct ceph_osd_client *osdc,
                          struct rb_root *need_resend,
                          struct list_head *need_resend_linger)
{
        struct ceph_osd_linger_request *lreq, *nlreq;
        struct rb_node *n;

        for (n = rb_first(need_resend); n; ) {
                struct ceph_osd_request *req =
                    rb_entry(n, struct ceph_osd_request, r_node);
                struct ceph_osd *osd;

                n = rb_next(n);
                erase_request(need_resend, req); /* before link_request() */

                WARN_ON(req->r_osd);
                calc_target(osdc, &req->r_t, NULL, false);
                osd = lookup_create_osd(osdc, req->r_t.osd, true);
                link_request(osd, req);
                if (!req->r_linger) {
                        if (!osd_homeless(osd) && !req->r_t.paused)
                                send_request(req);
                } else {
                        cancel_linger_request(req);
                }
        }

        list_for_each_entry_safe(lreq, nlreq, need_resend_linger, scan_item) {
                if (!osd_homeless(lreq->osd))
                        send_linger(lreq);

                list_del_init(&lreq->scan_item);
        }
}

/*
 * Process updated osd map.
 *
 * The message contains any number of incremental and full maps, normally
 * indicating some sort of topology change in the cluster.  Kick requests
 * off to different OSDs as needed.
 */
void ceph_osdc_handle_map(struct ceph_osd_client *osdc, struct ceph_msg *msg)
{
        void *p = msg->front.iov_base;
        void *const end = p + msg->front.iov_len;
        u32 nr_maps, maplen;
        u32 epoch;
        struct ceph_fsid fsid;
        struct rb_root need_resend = RB_ROOT;
        LIST_HEAD(need_resend_linger);
        bool handled_incremental = false;
        bool was_pauserd, was_pausewr;
        bool pauserd, pausewr;
        int err;

        dout("%s have %u\n", __func__, osdc->osdmap->epoch);
        down_write(&osdc->lock);

        /* verify fsid */
        ceph_decode_need(&p, end, sizeof(fsid), bad);
        ceph_decode_copy(&p, &fsid, sizeof(fsid));
        if (ceph_check_fsid(osdc->client, &fsid) < 0)
                goto bad;

        was_pauserd = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD);
        was_pausewr = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR) ||
                      ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) ||
                      have_pool_full(osdc);

        /* incremental maps */
        ceph_decode_32_safe(&p, end, nr_maps, bad);
        dout(" %d inc maps\n", nr_maps);
        while (nr_maps > 0) {
                ceph_decode_need(&p, end, 2*sizeof(u32), bad);
                epoch = ceph_decode_32(&p);
                maplen = ceph_decode_32(&p);
                ceph_decode_need(&p, end, maplen, bad);
                if (osdc->osdmap->epoch &&
                    osdc->osdmap->epoch + 1 == epoch) {
                        dout("applying incremental map %u len %d\n",
                             epoch, maplen);
                        err = handle_one_map(osdc, p, p + maplen, true,
                                             &need_resend, &need_resend_linger);
                        if (err)
                                goto bad;
                        handled_incremental = true;
                } else {
                        dout("ignoring incremental map %u len %d\n",
                             epoch, maplen);
                }
                p += maplen;
                nr_maps--;
        }
        if (handled_incremental)
                goto done;

        /* full maps */
        ceph_decode_32_safe(&p, end, nr_maps, bad);
        dout(" %d full maps\n", nr_maps);
        while (nr_maps) {
                ceph_decode_need(&p, end, 2*sizeof(u32), bad);
                epoch = ceph_decode_32(&p);
                maplen = ceph_decode_32(&p);
                ceph_decode_need(&p, end, maplen, bad);
                if (nr_maps > 1) {
                        dout("skipping non-latest full map %u len %d\n",
                             epoch, maplen);
                } else if (osdc->osdmap->epoch >= epoch) {
                        dout("skipping full map %u len %d, "
                             "older than our %u\n", epoch, maplen,
                             osdc->osdmap->epoch);
                } else {
                        dout("taking full map %u len %d\n", epoch, maplen);
                        err = handle_one_map(osdc, p, p + maplen, false,
                                             &need_resend, &need_resend_linger);
                        if (err)
                                goto bad;
                }
                p += maplen;
                nr_maps--;
        }

done:
        /*
         * subscribe to subsequent osdmap updates if full to ensure
         * we find out when we are no longer full and stop returning
         * ENOSPC.
         */
        pauserd = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSERD);
        pausewr = ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_PAUSEWR) ||
                  ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL) ||
                  have_pool_full(osdc);
        if (was_pauserd || was_pausewr || pauserd || pausewr)
                maybe_request_map(osdc);

        kick_requests(osdc, &need_resend, &need_resend_linger);

        ceph_monc_got_map(&osdc->client->monc, CEPH_SUB_OSDMAP,
                          osdc->osdmap->epoch);
        up_write(&osdc->lock);
        wake_up_all(&osdc->client->auth_wq);
        return;

bad:
        pr_err("osdc handle_map corrupt msg\n");
        ceph_msg_dump(msg);
        up_write(&osdc->lock);
}

/*
 * Resubmit requests pending on the given osd.
 */
static void kick_osd_requests(struct ceph_osd *osd)
{
        struct rb_node *n;

        for (n = rb_first(&osd->o_requests); n; ) {
                struct ceph_osd_request *req =
                    rb_entry(n, struct ceph_osd_request, r_node);

                n = rb_next(n); /* cancel_linger_request() */

                if (!req->r_linger) {
                        if (!req->r_t.paused)
                                send_request(req);
                } else {
                        cancel_linger_request(req);
                }
        }
        for (n = rb_first(&osd->o_linger_requests); n; n = rb_next(n)) {
                struct ceph_osd_linger_request *lreq =
                    rb_entry(n, struct ceph_osd_linger_request, node);

                send_linger(lreq);
        }
}

/*
 * If the osd connection drops, we need to resubmit all requests.
 */
static void osd_fault(struct ceph_connection *con)
{
        struct ceph_osd *osd = con->private;
        struct ceph_osd_client *osdc = osd->o_osdc;

        dout("%s osd %p osd%d\n", __func__, osd, osd->o_osd);

        down_write(&osdc->lock);
        if (!osd_registered(osd)) {
                dout("%s osd%d unknown\n", __func__, osd->o_osd);
                goto out_unlock;
        }

        if (!reopen_osd(osd))
                kick_osd_requests(osd);
        maybe_request_map(osdc);

out_unlock:
        up_write(&osdc->lock);
}

/*
 * Process osd watch notifications
 */
static void handle_watch_notify(struct ceph_osd_client *osdc,
                                struct ceph_msg *msg)
{
        void *p = msg->front.iov_base;
        void *const end = p + msg->front.iov_len;
        struct ceph_osd_linger_request *lreq;
        struct linger_work *lwork;
        u8 proto_ver, opcode;
        u64 cookie, notify_id;
        u64 notifier_id = 0;
        s32 return_code = 0;
        void *payload = NULL;
        u32 payload_len = 0;

        ceph_decode_8_safe(&p, end, proto_ver, bad);
        ceph_decode_8_safe(&p, end, opcode, bad);
        ceph_decode_64_safe(&p, end, cookie, bad);
        p += 8; /* skip ver */
        ceph_decode_64_safe(&p, end, notify_id, bad);

        if (proto_ver >= 1) {
                ceph_decode_32_safe(&p, end, payload_len, bad);
                ceph_decode_need(&p, end, payload_len, bad);
                payload = p;
                p += payload_len;
        }

        if (le16_to_cpu(msg->hdr.version) >= 2)
                ceph_decode_32_safe(&p, end, return_code, bad);

        if (le16_to_cpu(msg->hdr.version) >= 3)
                ceph_decode_64_safe(&p, end, notifier_id, bad);

        down_read(&osdc->lock);
        lreq = lookup_linger_osdc(&osdc->linger_requests, cookie);
        if (!lreq) {
                dout("%s opcode %d cookie %llu dne\n", __func__, opcode,
                     cookie);
                goto out_unlock_osdc;
        }

        mutex_lock(&lreq->lock);
        dout("%s opcode %d cookie %llu lreq %p is_watch %d\n", __func__,
             opcode, cookie, lreq, lreq->is_watch);
        if (opcode == CEPH_WATCH_EVENT_DISCONNECT) {
                if (!lreq->last_error) {
                        lreq->last_error = -ENOTCONN;
                        queue_watch_error(lreq);
                }
        } else if (!lreq->is_watch) {
                /* CEPH_WATCH_EVENT_NOTIFY_COMPLETE */
                if (lreq->notify_id && lreq->notify_id != notify_id) {
                        dout("lreq %p notify_id %llu != %llu, ignoring\n", lreq,
                             lreq->notify_id, notify_id);
                } else if (!completion_done(&lreq->notify_finish_wait)) {
                        struct ceph_msg_data *data =
                            list_first_entry_or_null(&msg->data,
                                                     struct ceph_msg_data,
                                                     links);

                        if (data) {
                                if (lreq->preply_pages) {
                                        WARN_ON(data->type !=
                                                        CEPH_MSG_DATA_PAGES);
                                        *lreq->preply_pages = data->pages;
                                        *lreq->preply_len = data->length;
                                } else {
                                        ceph_release_page_vector(data->pages,
                                               calc_pages_for(0, data->length));
                                }
                        }
                        lreq->notify_finish_error = return_code;
                        complete_all(&lreq->notify_finish_wait);
                }
        } else {
                /* CEPH_WATCH_EVENT_NOTIFY */
                lwork = lwork_alloc(lreq, do_watch_notify);
                if (!lwork) {
                        pr_err("failed to allocate notify-lwork\n");
                        goto out_unlock_lreq;
                }

                lwork->notify.notify_id = notify_id;
                lwork->notify.notifier_id = notifier_id;
                lwork->notify.payload = payload;
                lwork->notify.payload_len = payload_len;
                lwork->notify.msg = ceph_msg_get(msg);
                lwork_queue(lwork);
        }

out_unlock_lreq:
        mutex_unlock(&lreq->lock);
out_unlock_osdc:
        up_read(&osdc->lock);
        return;

bad:
        pr_err("osdc handle_watch_notify corrupt msg\n");
}

/*
 * Register request, send initial attempt.
 */
int ceph_osdc_start_request(struct ceph_osd_client *osdc,
                            struct ceph_osd_request *req,
                            bool nofail)
{
        down_read(&osdc->lock);
        submit_request(req, false);
        up_read(&osdc->lock);

        return 0;
}
EXPORT_SYMBOL(ceph_osdc_start_request);

/*
 * Unregister a registered request.  The request is not completed (i.e.
 * no callbacks or wakeups) - higher layers are supposed to know what
 * they are canceling.
 */
void ceph_osdc_cancel_request(struct ceph_osd_request *req)
{
        struct ceph_osd_client *osdc = req->r_osdc;

        down_write(&osdc->lock);
        if (req->r_osd)
                cancel_request(req);
        up_write(&osdc->lock);
}
EXPORT_SYMBOL(ceph_osdc_cancel_request);

/*
 * @timeout: in jiffies, 0 means "wait forever"
 */
static int wait_request_timeout(struct ceph_osd_request *req,
                                unsigned long timeout)
{
        long left;

        dout("%s req %p tid %llu\n", __func__, req, req->r_tid);
        left = wait_for_completion_interruptible_timeout(&req->r_completion,
                                                ceph_timeout_jiffies(timeout));
        if (left <= 0) {
                left = left ?: -ETIMEDOUT;
                ceph_osdc_cancel_request(req);

                /* kludge - need to to wake ceph_osdc_sync() */
                complete_all(&req->r_safe_completion);
        } else {
                left = req->r_result; /* completed */
        }

        return left;
}

/*
 * wait for a request to complete
 */
int ceph_osdc_wait_request(struct ceph_osd_client *osdc,
                           struct ceph_osd_request *req)
{
        return wait_request_timeout(req, 0);
}
EXPORT_SYMBOL(ceph_osdc_wait_request);

/*
 * sync - wait for all in-flight requests to flush.  avoid starvation.
 */
void ceph_osdc_sync(struct ceph_osd_client *osdc)
{
        struct rb_node *n, *p;
        u64 last_tid = atomic64_read(&osdc->last_tid);

again:
        down_read(&osdc->lock);
        for (n = rb_first(&osdc->osds); n; n = rb_next(n)) {
                struct ceph_osd *osd = rb_entry(n, struct ceph_osd, o_node);

                mutex_lock(&osd->lock);
                for (p = rb_first(&osd->o_requests); p; p = rb_next(p)) {
                        struct ceph_osd_request *req =
                            rb_entry(p, struct ceph_osd_request, r_node);

                        if (req->r_tid > last_tid)
                                break;

                        if (!(req->r_flags & CEPH_OSD_FLAG_WRITE))
                                continue;

                        ceph_osdc_get_request(req);
                        mutex_unlock(&osd->lock);
                        up_read(&osdc->lock);
                        dout("%s waiting on req %p tid %llu last_tid %llu\n",
                             __func__, req, req->r_tid, last_tid);
                        wait_for_completion(&req->r_safe_completion);
                        ceph_osdc_put_request(req);
                        goto again;
                }

                mutex_unlock(&osd->lock);
        }

        up_read(&osdc->lock);
        dout("%s done last_tid %llu\n", __func__, last_tid);
}
EXPORT_SYMBOL(ceph_osdc_sync);

static struct ceph_osd_request *
alloc_linger_request(struct ceph_osd_linger_request *lreq)
{
        struct ceph_osd_request *req;

        req = ceph_osdc_alloc_request(lreq->osdc, NULL, 1, false, GFP_NOIO);
        if (!req)
                return NULL;

        ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
        ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);

        if (ceph_osdc_alloc_messages(req, GFP_NOIO)) {
                ceph_osdc_put_request(req);
                return NULL;
        }

        return req;
}

/*
 * Returns a handle, caller owns a ref.
 */
struct ceph_osd_linger_request *
ceph_osdc_watch(struct ceph_osd_client *osdc,
                struct ceph_object_id *oid,
                struct ceph_object_locator *oloc,
                rados_watchcb2_t wcb,
                rados_watcherrcb_t errcb,
                void *data)
{
        struct ceph_osd_linger_request *lreq;
        int ret;

        lreq = linger_alloc(osdc);
        if (!lreq)
                return ERR_PTR(-ENOMEM);

        lreq->is_watch = true;
        lreq->wcb = wcb;
        lreq->errcb = errcb;
        lreq->data = data;

        ceph_oid_copy(&lreq->t.base_oid, oid);
        ceph_oloc_copy(&lreq->t.base_oloc, oloc);
        lreq->t.flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK;
        lreq->mtime = CURRENT_TIME;

        lreq->reg_req = alloc_linger_request(lreq);
        if (!lreq->reg_req) {
                ret = -ENOMEM;
                goto err_put_lreq;
        }

        lreq->ping_req = alloc_linger_request(lreq);
        if (!lreq->ping_req) {
                ret = -ENOMEM;
                goto err_put_lreq;
        }

        down_write(&osdc->lock);
        linger_register(lreq); /* before osd_req_op_* */
        osd_req_op_watch_init(lreq->reg_req, 0, lreq->linger_id,
                              CEPH_OSD_WATCH_OP_WATCH);
        osd_req_op_watch_init(lreq->ping_req, 0, lreq->linger_id,
                              CEPH_OSD_WATCH_OP_PING);
        linger_submit(lreq);
        up_write(&osdc->lock);

        ret = linger_reg_commit_wait(lreq);
        if (ret) {
                linger_cancel(lreq);
                goto err_put_lreq;
        }

        return lreq;

err_put_lreq:
        linger_put(lreq);
        return ERR_PTR(ret);
}
EXPORT_SYMBOL(ceph_osdc_watch);

/*
 * Releases a ref.
 *
 * Times out after mount_timeout to preserve rbd unmap behaviour
 * introduced in 2894e1d76974 ("rbd: timeout watch teardown on unmap
 * with mount_timeout").
 */
int ceph_osdc_unwatch(struct ceph_osd_client *osdc,
                      struct ceph_osd_linger_request *lreq)
{
        struct ceph_options *opts = osdc->client->options;
        struct ceph_osd_request *req;
        int ret;

        req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
        if (!req)
                return -ENOMEM;

        ceph_oid_copy(&req->r_base_oid, &lreq->t.base_oid);
        ceph_oloc_copy(&req->r_base_oloc, &lreq->t.base_oloc);
        req->r_flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK;
        req->r_mtime = CURRENT_TIME;
        osd_req_op_watch_init(req, 0, lreq->linger_id,
                              CEPH_OSD_WATCH_OP_UNWATCH);

        ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
        if (ret)
                goto out_put_req;

        ceph_osdc_start_request(osdc, req, false);
        linger_cancel(lreq);
        linger_put(lreq);
        ret = wait_request_timeout(req, opts->mount_timeout);

out_put_req:
        ceph_osdc_put_request(req);
        return ret;
}
EXPORT_SYMBOL(ceph_osdc_unwatch);

static int osd_req_op_notify_ack_init(struct ceph_osd_request *req, int which,
                                      u64 notify_id, u64 cookie, void *payload,
                                      size_t payload_len)
{
        struct ceph_osd_req_op *op;
        struct ceph_pagelist *pl;
        int ret;

        op = _osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY_ACK, 0);

        pl = kmalloc(sizeof(*pl), GFP_NOIO);
        if (!pl)
                return -ENOMEM;

        ceph_pagelist_init(pl);
        ret = ceph_pagelist_encode_64(pl, notify_id);
        ret |= ceph_pagelist_encode_64(pl, cookie);
        if (payload) {
                ret |= ceph_pagelist_encode_32(pl, payload_len);
                ret |= ceph_pagelist_append(pl, payload, payload_len);
        } else {
                ret |= ceph_pagelist_encode_32(pl, 0);
        }
        if (ret) {
                ceph_pagelist_release(pl);
                return -ENOMEM;
        }

        ceph_osd_data_pagelist_init(&op->notify_ack.request_data, pl);
        op->indata_len = pl->length;
        return 0;
}

int ceph_osdc_notify_ack(struct ceph_osd_client *osdc,
                         struct ceph_object_id *oid,
                         struct ceph_object_locator *oloc,
                         u64 notify_id,
                         u64 cookie,
                         void *payload,
                         size_t payload_len)
{
        struct ceph_osd_request *req;
        int ret;

        req = ceph_osdc_alloc_request(osdc, NULL, 1, false, GFP_NOIO);
        if (!req)
                return -ENOMEM;

        ceph_oid_copy(&req->r_base_oid, oid);
        ceph_oloc_copy(&req->r_base_oloc, oloc);
        req->r_flags = CEPH_OSD_FLAG_READ;

        ret = ceph_osdc_alloc_messages(req, GFP_NOIO);
        if (ret)
                goto out_put_req;

        ret = osd_req_op_notify_ack_init(req, 0, notify_id, cookie, payload,
                                         payload_len);
        if (ret)
                goto out_put_req;

        ceph_osdc_start_request(osdc, req, false);
        ret = ceph_osdc_wait_request(osdc, req);

out_put_req:
        ceph_osdc_put_request(req);
        return ret;
}
EXPORT_SYMBOL(ceph_osdc_notify_ack);

static int osd_req_op_notify_init(struct ceph_osd_request *req, int which,
                                  u64 cookie, u32 prot_ver, u32 timeout,
                                  void *payload, size_t payload_len)
{
        struct ceph_osd_req_op *op;
        struct ceph_pagelist *pl;
        int ret;

        op = _osd_req_op_init(req, which, CEPH_OSD_OP_NOTIFY, 0);
        op->notify.cookie = cookie;

        pl = kmalloc(sizeof(*pl), GFP_NOIO);
        if (!pl)
                return -ENOMEM;

        ceph_pagelist_init(pl);
        ret = ceph_pagelist_encode_32(pl, 1); /* prot_ver */
        ret |= ceph_pagelist_encode_32(pl, timeout);
        ret |= ceph_pagelist_encode_32(pl, payload_len);
        ret |= ceph_pagelist_append(pl, payload, payload_len);
        if (ret) {
                ceph_pagelist_release(pl);
                return -ENOMEM;
        }

        ceph_osd_data_pagelist_init(&op->notify.request_data, pl);
        op->indata_len = pl->length;
        return 0;
}

/*
 * @timeout: in seconds
 *
 * @preply_{pages,len} are initialized both on success and error.
 * The caller is responsible for:
 *
 *     ceph_release_page_vector(reply_pages, calc_pages_for(0, reply_len))
 */
int ceph_osdc_notify(struct ceph_osd_client *osdc,
                     struct ceph_object_id *oid,
                     struct ceph_object_locator *oloc,
                     void *payload,
                     size_t payload_len,
                     u32 timeout,
                     struct page ***preply_pages,
                     size_t *preply_len)
{
        struct ceph_osd_linger_request *lreq;
        struct page **pages;
        int ret;

        WARN_ON(!timeout);
        if (preply_pages) {
                *preply_pages = NULL;
                *preply_len = 0;
        }

        lreq = linger_alloc(osdc);
        if (!lreq)
                return -ENOMEM;

        lreq->preply_pages = preply_pages;
        lreq->preply_len = preply_len;

        ceph_oid_copy(&lreq->t.base_oid, oid);
        ceph_oloc_copy(&lreq->t.base_oloc, oloc);
        lreq->t.flags = CEPH_OSD_FLAG_READ;

        lreq->reg_req = alloc_linger_request(lreq);
        if (!lreq->reg_req) {
                ret = -ENOMEM;
                goto out_put_lreq;
        }

        /* for notify_id */
        pages = ceph_alloc_page_vector(1, GFP_NOIO);
        if (IS_ERR(pages)) {
                ret = PTR_ERR(pages);
                goto out_put_lreq;
        }

        down_write(&osdc->lock);
        linger_register(lreq); /* before osd_req_op_* */
        ret = osd_req_op_notify_init(lreq->reg_req, 0, lreq->linger_id, 1,
                                     timeout, payload, payload_len);
        if (ret) {
                linger_unregister(lreq);
                up_write(&osdc->lock);
                ceph_release_page_vector(pages, 1);
                goto out_put_lreq;
        }
        ceph_osd_data_pages_init(osd_req_op_data(lreq->reg_req, 0, notify,
                                                 response_data),
                                 pages, PAGE_SIZE, 0, false, true);
        linger_submit(lreq);
        up_write(&osdc->lock);

        ret = linger_reg_commit_wait(lreq);
        if (!ret)
                ret = linger_notify_finish_wait(lreq);
        else
                dout("lreq %p failed to initiate notify %d\n", lreq, ret);

        linger_cancel(lreq);
out_put_lreq:
        linger_put(lreq);
        return ret;
}
EXPORT_SYMBOL(ceph_osdc_notify);

/*
 * Call all pending notify callbacks - for use after a watch is
 * unregistered, to make sure no more callbacks for it will be invoked
 */
void ceph_osdc_flush_notifies(struct ceph_osd_client *osdc)
{
        flush_workqueue(osdc->notify_wq);
}
EXPORT_SYMBOL(ceph_osdc_flush_notifies);


/*
 * init, shutdown
 */
int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
{
        int err;

        dout("init\n");
        osdc->client = client;
        init_rwsem(&osdc->lock);
        osdc->osds = RB_ROOT;
        INIT_LIST_HEAD(&osdc->osd_lru);
        spin_lock_init(&osdc->osd_lru_lock);
        osd_init(&osdc->homeless_osd);
        osdc->homeless_osd.o_osdc = osdc;
        osdc->homeless_osd.o_osd = CEPH_HOMELESS_OSD;
        osdc->linger_requests = RB_ROOT;
        INIT_DELAYED_WORK(&osdc->timeout_work, handle_timeout);
        INIT_DELAYED_WORK(&osdc->osds_timeout_work, handle_osds_timeout);

        err = -ENOMEM;
        osdc->osdmap = ceph_osdmap_alloc();
        if (!osdc->osdmap)
                goto out;

        osdc->req_mempool = mempool_create_slab_pool(10,
                                                     ceph_osd_request_cache);
        if (!osdc->req_mempool)
                goto out_map;

        err = ceph_msgpool_init(&osdc->msgpool_op, CEPH_MSG_OSD_OP,
                                PAGE_SIZE, 10, true, "osd_op");
        if (err < 0)
                goto out_mempool;
        err = ceph_msgpool_init(&osdc->msgpool_op_reply, CEPH_MSG_OSD_OPREPLY,
                                PAGE_SIZE, 10, true, "osd_op_reply");
        if (err < 0)
                goto out_msgpool;

        err = -ENOMEM;
        osdc->notify_wq = create_singlethread_workqueue("ceph-watch-notify");
        if (!osdc->notify_wq)
                goto out_msgpool_reply;

        schedule_delayed_work(&osdc->timeout_work,
                              osdc->client->options->osd_keepalive_timeout);
        schedule_delayed_work(&osdc->osds_timeout_work,
            round_jiffies_relative(osdc->client->options->osd_idle_ttl));

        return 0;

out_msgpool_reply:
        ceph_msgpool_destroy(&osdc->msgpool_op_reply);
out_msgpool:
        ceph_msgpool_destroy(&osdc->msgpool_op);
out_mempool:
        mempool_destroy(osdc->req_mempool);
out_map:
        ceph_osdmap_destroy(osdc->osdmap);
out:
        return err;
}

void ceph_osdc_stop(struct ceph_osd_client *osdc)
{
        flush_workqueue(osdc->notify_wq);
        destroy_workqueue(osdc->notify_wq);
        cancel_delayed_work_sync(&osdc->timeout_work);
        cancel_delayed_work_sync(&osdc->osds_timeout_work);

        down_write(&osdc->lock);
        while (!RB_EMPTY_ROOT(&osdc->osds)) {
                struct ceph_osd *osd = rb_entry(rb_first(&osdc->osds),
                                                struct ceph_osd, o_node);
                close_osd(osd);
        }
        up_write(&osdc->lock);
        WARN_ON(atomic_read(&osdc->homeless_osd.o_ref) != 1);
        osd_cleanup(&osdc->homeless_osd);

        WARN_ON(!list_empty(&osdc->osd_lru));
        WARN_ON(!RB_EMPTY_ROOT(&osdc->linger_requests));
        WARN_ON(atomic_read(&osdc->num_requests));
        WARN_ON(atomic_read(&osdc->num_homeless));

        ceph_osdmap_destroy(osdc->osdmap);
        mempool_destroy(osdc->req_mempool);
        ceph_msgpool_destroy(&osdc->msgpool_op);
        ceph_msgpool_destroy(&osdc->msgpool_op_reply);
}

/*
 * Read some contiguous pages.  If we cross a stripe boundary, shorten
 * *plen.  Return number of bytes read, or error.
 */
int ceph_osdc_readpages(struct ceph_osd_client *osdc,
                        struct ceph_vino vino, struct ceph_file_layout *layout,
                        u64 off, u64 *plen,
                        u32 truncate_seq, u64 truncate_size,
                        struct page **pages, int num_pages, int page_align)
{
        struct ceph_osd_request *req;
        int rc = 0;

        dout("readpages on ino %llx.%llx on %llu~%llu\n", vino.ino,
             vino.snap, off, *plen);
        req = ceph_osdc_new_request(osdc, layout, vino, off, plen, 0, 1,
                                    CEPH_OSD_OP_READ, CEPH_OSD_FLAG_READ,
                                    NULL, truncate_seq, truncate_size,
                                    false);
        if (IS_ERR(req))
                return PTR_ERR(req);

        /* it may be a short read due to an object boundary */
        osd_req_op_extent_osd_data_pages(req, 0,
                                pages, *plen, page_align, false, false);

        dout("readpages  final extent is %llu~%llu (%llu bytes align %d)\n",
             off, *plen, *plen, page_align);

        rc = ceph_osdc_start_request(osdc, req, false);
        if (!rc)
                rc = ceph_osdc_wait_request(osdc, req);

        ceph_osdc_put_request(req);
        dout("readpages result %d\n", rc);
        return rc;
}
EXPORT_SYMBOL(ceph_osdc_readpages);

/*
 * do a synchronous write on N pages
 */
int ceph_osdc_writepages(struct ceph_osd_client *osdc, struct ceph_vino vino,
                         struct ceph_file_layout *layout,
                         struct ceph_snap_context *snapc,
                         u64 off, u64 len,
                         u32 truncate_seq, u64 truncate_size,
                         struct timespec *mtime,
                         struct page **pages, int num_pages)
{
        struct ceph_osd_request *req;
        int rc = 0;
        int page_align = off & ~PAGE_MASK;

        req = ceph_osdc_new_request(osdc, layout, vino, off, &len, 0, 1,
                                    CEPH_OSD_OP_WRITE,
                                    CEPH_OSD_FLAG_ONDISK | CEPH_OSD_FLAG_WRITE,
                                    snapc, truncate_seq, truncate_size,
                                    true);
        if (IS_ERR(req))
                return PTR_ERR(req);

        /* it may be a short write due to an object boundary */
        osd_req_op_extent_osd_data_pages(req, 0, pages, len, page_align,
                                false, false);
        dout("writepages %llu~%llu (%llu bytes)\n", off, len, len);

        req->r_mtime = *mtime;
        rc = ceph_osdc_start_request(osdc, req, true);
        if (!rc)
                rc = ceph_osdc_wait_request(osdc, req);

        ceph_osdc_put_request(req);
        if (rc == 0)
                rc = len;
        dout("writepages result %d\n", rc);
        return rc;
}
EXPORT_SYMBOL(ceph_osdc_writepages);

int ceph_osdc_setup(void)
{
        size_t size = sizeof(struct ceph_osd_request) +
            CEPH_OSD_SLAB_OPS * sizeof(struct ceph_osd_req_op);

        BUG_ON(ceph_osd_request_cache);
        ceph_osd_request_cache = kmem_cache_create("ceph_osd_request", size,
                                                   0, 0, NULL);

        return ceph_osd_request_cache ? 0 : -ENOMEM;
}
EXPORT_SYMBOL(ceph_osdc_setup);

void ceph_osdc_cleanup(void)
{
        BUG_ON(!ceph_osd_request_cache);
        kmem_cache_destroy(ceph_osd_request_cache);
        ceph_osd_request_cache = NULL;
}
EXPORT_SYMBOL(ceph_osdc_cleanup);

/*
 * handle incoming message
 */
static void dispatch(struct ceph_connection *con, struct ceph_msg *msg)
{
        struct ceph_osd *osd = con->private;
        struct ceph_osd_client *osdc = osd->o_osdc;
        int type = le16_to_cpu(msg->hdr.type);

        switch (type) {
        case CEPH_MSG_OSD_MAP:
                ceph_osdc_handle_map(osdc, msg);
                break;
        case CEPH_MSG_OSD_OPREPLY:
                handle_reply(osd, msg);
                break;
        case CEPH_MSG_WATCH_NOTIFY:
                handle_watch_notify(osdc, msg);
                break;

        default:
                pr_err("received unknown message type %d %s\n", type,
                       ceph_msg_type_name(type));
        }

        ceph_msg_put(msg);
}

/*
 * Lookup and return message for incoming reply.  Don't try to do
 * anything about a larger than preallocated data portion of the
 * message at the moment - for now, just skip the message.
 */
static struct ceph_msg *get_reply(struct ceph_connection *con,
                                  struct ceph_msg_header *hdr,
                                  int *skip)
{
        struct ceph_osd *osd = con->private;
        struct ceph_osd_client *osdc = osd->o_osdc;
        struct ceph_msg *m = NULL;
        struct ceph_osd_request *req;
        int front_len = le32_to_cpu(hdr->front_len);
        int data_len = le32_to_cpu(hdr->data_len);
        u64 tid = le64_to_cpu(hdr->tid);

        down_read(&osdc->lock);
        if (!osd_registered(osd)) {
                dout("%s osd%d unknown, skipping\n", __func__, osd->o_osd);
                *skip = 1;
                goto out_unlock_osdc;
        }
        WARN_ON(osd->o_osd != le64_to_cpu(hdr->src.num));

        mutex_lock(&osd->lock);
        req = lookup_request(&osd->o_requests, tid);
        if (!req) {
                dout("%s osd%d tid %llu unknown, skipping\n", __func__,
                     osd->o_osd, tid);
                *skip = 1;
                goto out_unlock_session;
        }

        ceph_msg_revoke_incoming(req->r_reply);

        if (front_len > req->r_reply->front_alloc_len) {
                pr_warn("%s osd%d tid %llu front %d > preallocated %d\n",
                        __func__, osd->o_osd, req->r_tid, front_len,
                        req->r_reply->front_alloc_len);
                m = ceph_msg_new(CEPH_MSG_OSD_OPREPLY, front_len, GFP_NOFS,
                                 false);
                if (!m)
                        goto out_unlock_session;
                ceph_msg_put(req->r_reply);
                req->r_reply = m;
        }

        if (data_len > req->r_reply->data_length) {
                pr_warn("%s osd%d tid %llu data %d > preallocated %zu, skipping\n",
                        __func__, osd->o_osd, req->r_tid, data_len,
                        req->r_reply->data_length);
                m = NULL;
                *skip = 1;
                goto out_unlock_session;
        }

        m = ceph_msg_get(req->r_reply);
        dout("get_reply tid %lld %p\n", tid, m);

out_unlock_session:
        mutex_unlock(&osd->lock);
out_unlock_osdc:
        up_read(&osdc->lock);
        return m;
}

/*
 * TODO: switch to a msg-owned pagelist
 */
static struct ceph_msg *alloc_msg_with_page_vector(struct ceph_msg_header *hdr)
{
        struct ceph_msg *m;
        int type = le16_to_cpu(hdr->type);
        u32 front_len = le32_to_cpu(hdr->front_len);
        u32 data_len = le32_to_cpu(hdr->data_len);

        m = ceph_msg_new(type, front_len, GFP_NOIO, false);
        if (!m)
                return NULL;

        if (data_len) {
                struct page **pages;
                struct ceph_osd_data osd_data;

                pages = ceph_alloc_page_vector(calc_pages_for(0, data_len),
                                               GFP_NOIO);
                if (!pages) {
                        ceph_msg_put(m);
                        return NULL;
                }

                ceph_osd_data_pages_init(&osd_data, pages, data_len, 0, false,
                                         false);
                ceph_osdc_msg_data_add(m, &osd_data);
        }

        return m;
}

static struct ceph_msg *alloc_msg(struct ceph_connection *con,
                                  struct ceph_msg_header *hdr,
                                  int *skip)
{
        struct ceph_osd *osd = con->private;
        int type = le16_to_cpu(hdr->type);

        *skip = 0;
        switch (type) {
        case CEPH_MSG_OSD_MAP:
        case CEPH_MSG_WATCH_NOTIFY:
                return alloc_msg_with_page_vector(hdr);
        case CEPH_MSG_OSD_OPREPLY:
                return get_reply(con, hdr, skip);
        default:
                pr_warn("%s osd%d unknown msg type %d, skipping\n", __func__,
                        osd->o_osd, type);
                *skip = 1;
                return NULL;
        }
}

/*
 * Wrappers to refcount containing ceph_osd struct
 */
static struct ceph_connection *get_osd_con(struct ceph_connection *con)
{
        struct ceph_osd *osd = con->private;
        if (get_osd(osd))
                return con;
        return NULL;
}

static void put_osd_con(struct ceph_connection *con)
{
        struct ceph_osd *osd = con->private;
        put_osd(osd);
}

/*
 * authentication
 */
/*
 * Note: returned pointer is the address of a structure that's
 * managed separately.  Caller must *not* attempt to free it.
 */
static struct ceph_auth_handshake *get_authorizer(struct ceph_connection *con,
                                        int *proto, int force_new)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;
        struct ceph_auth_handshake *auth = &o->o_auth;

        if (force_new && auth->authorizer) {
                ceph_auth_destroy_authorizer(auth->authorizer);
                auth->authorizer = NULL;
        }
        if (!auth->authorizer) {
                int ret = ceph_auth_create_authorizer(ac, CEPH_ENTITY_TYPE_OSD,
                                                      auth);
                if (ret)
                        return ERR_PTR(ret);
        } else {
                int ret = ceph_auth_update_authorizer(ac, CEPH_ENTITY_TYPE_OSD,
                                                     auth);
                if (ret)
                        return ERR_PTR(ret);
        }
        *proto = ac->protocol;

        return auth;
}


static int verify_authorizer_reply(struct ceph_connection *con, int len)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;

        return ceph_auth_verify_authorizer_reply(ac, o->o_auth.authorizer, len);
}

static int invalidate_authorizer(struct ceph_connection *con)
{
        struct ceph_osd *o = con->private;
        struct ceph_osd_client *osdc = o->o_osdc;
        struct ceph_auth_client *ac = osdc->client->monc.auth;

        ceph_auth_invalidate_authorizer(ac, CEPH_ENTITY_TYPE_OSD);
        return ceph_monc_validate_auth(&osdc->client->monc);
}

static int osd_sign_message(struct ceph_msg *msg)
{
        struct ceph_osd *o = msg->con->private;
        struct ceph_auth_handshake *auth = &o->o_auth;

        return ceph_auth_sign_message(auth, msg);
}

static int osd_check_message_signature(struct ceph_msg *msg)
{
        struct ceph_osd *o = msg->con->private;
        struct ceph_auth_handshake *auth = &o->o_auth;

        return ceph_auth_check_message_signature(auth, msg);
}

static const struct ceph_connection_operations osd_con_ops = {
        .get = get_osd_con,
        .put = put_osd_con,
        .dispatch = dispatch,
        .get_authorizer = get_authorizer,
        .verify_authorizer_reply = verify_authorizer_reply,
        .invalidate_authorizer = invalidate_authorizer,
        .alloc_msg = alloc_msg,
        .sign_message = osd_sign_message,
        .check_message_signature = osd_check_message_signature,
        .fault = osd_fault,
};