rbd: lock_on_read map option

[cascardo/linux.git] / drivers / block / rbd.c

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 35fc1da..cc4c9f4 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -795,6 +795,7 @@ enum {
        /* string args above */
        Opt_read_only,
        Opt_read_write,
+       Opt_lock_on_read,
        Opt_err
 };
 
@@ -806,16 +807,19 @@ static match_table_t rbd_opts_tokens = {
        {Opt_read_only, "ro"},          /* Alternate spelling */
        {Opt_read_write, "read_write"},
        {Opt_read_write, "rw"},         /* Alternate spelling */
+       {Opt_lock_on_read, "lock_on_read"},
        {Opt_err, NULL}
 };
 
 struct rbd_options {
        int     queue_depth;
        bool    read_only;
+       bool    lock_on_read;
 };
 
 #define RBD_QUEUE_DEPTH_DEFAULT        BLKDEV_MAX_RQ
 #define RBD_READ_ONLY_DEFAULT  false
+#define RBD_LOCK_ON_READ_DEFAULT false
 
 static int parse_rbd_opts_token(char *c, void *private)
 {
@@ -851,6 +855,9 @@ static int parse_rbd_opts_token(char *c, void *private)
        case Opt_read_write:
                rbd_opts->read_only = false;
                break;
+       case Opt_lock_on_read:
+               rbd_opts->lock_on_read = true;
+               break;
        default:
                /* libceph prints "bad option" msg */
                return -EINVAL;
@@ -4105,7 +4112,7 @@ static void rbd_queue_workfn(struct work_struct *work)
        u64 length = blk_rq_bytes(rq);
        enum obj_operation_type op_type;
        u64 mapping_size;
-       bool must_be_locked = false;
+       bool must_be_locked;
        int result;
 
        if (rq->cmd_type != REQ_TYPE_FS) {
@@ -4168,6 +4175,9 @@ static void rbd_queue_workfn(struct work_struct *work)
                snapc = rbd_dev->header.snapc;
                ceph_get_snap_context(snapc);
                must_be_locked = rbd_is_lock_supported(rbd_dev);
+       } else {
+               must_be_locked = rbd_dev->opts->lock_on_read &&
+                                       rbd_is_lock_supported(rbd_dev);
        }
        up_read(&rbd_dev->header_rwsem);
 
@@ -5757,6 +5767,7 @@ static int rbd_add_parse_args(const char *buf,
 
        rbd_opts->read_only = RBD_READ_ONLY_DEFAULT;
        rbd_opts->queue_depth = RBD_QUEUE_DEPTH_DEFAULT;
+       rbd_opts->lock_on_read = RBD_LOCK_ON_READ_DEFAULT;
 
        copts = ceph_parse_options(options, mon_addrs,
                                        mon_addrs + mon_addrs_size - 1,