fs/nfs/direct.c

   1 /*
   2  * linux/fs/nfs/direct.c
   3  *
   4  * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
   5  *
   6  * High-performance uncached I/O for the Linux NFS client
   7  *
   8  * There are important applications whose performance or correctness
   9  * depends on uncached access to file data.  Database clusters
  10  * (multiple copies of the same instance running on separate hosts)
  11  * implement their own cache coherency protocol that subsumes file
  12  * system cache protocols.  Applications that process datasets
  13  * considerably larger than the client's memory do not always benefit
  14  * from a local cache.  A streaming video server, for instance, has no
  15  * need to cache the contents of a file.
  16  *
  17  * When an application requests uncached I/O, all read and write requests
  18  * are made directly to the server; data stored or fetched via these
  19  * requests is not cached in the Linux page cache.  The client does not
  20  * correct unaligned requests from applications.  All requested bytes are
  21  * held on permanent storage before a direct write system call returns to
  22  * an application.
  23  *
  24  * Solaris implements an uncached I/O facility called directio() that
  25  * is used for backups and sequential I/O to very large files.  Solaris
  26  * also supports uncaching whole NFS partitions with "-o forcedirectio,"
  27  * an undocumented mount option.
  28  *
  29  * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
  30  * help from Andrew Morton.
  31  *
  32  * 18 Dec 2001  Initial implementation for 2.4  --cel
  33  * 08 Jul 2002  Version for 2.4.19, with bug fixes --trondmy
  34  * 08 Jun 2003  Port to 2.5 APIs  --cel
  35  * 31 Mar 2004  Handle direct I/O without VFS support  --cel
  36  * 15 Sep 2004  Parallel async reads  --cel
  37  * 04 May 2005  support O_DIRECT with aio  --cel
  38  *
  39  */
  40
  41 #include <linux/errno.h>
  42 #include <linux/sched.h>
  43 #include <linux/kernel.h>
  44 #include <linux/file.h>
  45 #include <linux/pagemap.h>
  46 #include <linux/kref.h>
  47 #include <linux/slab.h>
  48 #include <linux/task_io_accounting_ops.h>
  49 #include <linux/module.h>
  50
  51 #include <linux/nfs_fs.h>
  52 #include <linux/nfs_page.h>
  53 #include <linux/sunrpc/clnt.h>
  54
  55 #include <asm/uaccess.h>
  56 #include <linux/atomic.h>
  57
  58 #include "internal.h"
  59 #include "iostat.h"
  60 #include "pnfs.h"
  61
  62 #define NFSDBG_FACILITY         NFSDBG_VFS
  63
  64 static struct kmem_cache *nfs_direct_cachep;
  65
  66 /*
  67  * This represents a set of asynchronous requests that we're waiting on
  68  */
  69 struct nfs_direct_mirror {
  70         ssize_t count;
  71 };
  72
  73 struct nfs_direct_req {
  74         struct kref             kref;           /* release manager */
  75
  76         /* I/O parameters */
  77         struct nfs_open_context *ctx;           /* file open context info */
  78         struct nfs_lock_context *l_ctx;         /* Lock context info */
  79         struct kiocb *          iocb;           /* controlling i/o request */
  80         struct inode *          inode;          /* target file of i/o */
  81
  82         /* completion state */
  83         atomic_t                io_count;       /* i/os we're waiting for */
  84         spinlock_t              lock;           /* protect completion state */
  85
  86         struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX];
  87         int                     mirror_count;
  88
  89         ssize_t                 count,          /* bytes actually processed */
  90                                 max_count,      /* max expected count */
  91                                 bytes_left,     /* bytes left to be sent */
  92                                 io_start,       /* start of IO */
  93                                 error;          /* any reported error */
  94         struct completion       completion;     /* wait for i/o completion */
  95
  96         /* commit state */
  97         struct nfs_mds_commit_info mds_cinfo;   /* Storage for cinfo */
  98         struct pnfs_ds_commit_info ds_cinfo;    /* Storage for cinfo */
  99         struct work_struct      work;
 100         int                     flags;
 101 #define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
 102 #define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
 103         struct nfs_writeverf    verf;           /* unstable write verifier */
 104 };
 105
 106 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
 107 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
 108 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
 109 static void nfs_direct_write_schedule_work(struct work_struct *work);
 110
 111 static inline void get_dreq(struct nfs_direct_req *dreq)
 112 {
 113         atomic_inc(&dreq->io_count);
 114 }
 115
 116 static inline int put_dreq(struct nfs_direct_req *dreq)
 117 {
 118         return atomic_dec_and_test(&dreq->io_count);
 119 }
 120
 121 static void
 122 nfs_direct_good_bytes(struct nfs_direct_req *dreq, struct nfs_pgio_header *hdr)
 123 {
 124         int i;
 125         ssize_t count;
 126
 127         WARN_ON_ONCE(dreq->count >= dreq->max_count);
 128
 129         if (dreq->mirror_count == 1) {
 130                 dreq->mirrors[hdr->pgio_mirror_idx].count += hdr->good_bytes;
 131                 dreq->count += hdr->good_bytes;
 132         } else {
 133                 /* mirrored writes */
 134                 count = dreq->mirrors[hdr->pgio_mirror_idx].count;
 135                 if (count + dreq->io_start < hdr->io_start + hdr->good_bytes) {
 136                         count = hdr->io_start + hdr->good_bytes - dreq->io_start;
 137                         dreq->mirrors[hdr->pgio_mirror_idx].count = count;
 138                 }
 139                 /* update the dreq->count by finding the minimum agreed count from all
 140                  * mirrors */
 141                 count = dreq->mirrors[0].count;
 142
 143                 for (i = 1; i < dreq->mirror_count; i++)
 144                         count = min(count, dreq->mirrors[i].count);
 145
 146                 dreq->count = count;
 147         }
 148 }
 149
 150 /*
 151  * nfs_direct_select_verf - select the right verifier
 152  * @dreq - direct request possibly spanning multiple servers
 153  * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
 154  * @commit_idx - commit bucket index for the DS
 155  *
 156  * returns the correct verifier to use given the role of the server
 157  */
 158 static struct nfs_writeverf *
 159 nfs_direct_select_verf(struct nfs_direct_req *dreq,
 160                        struct nfs_client *ds_clp,
 161                        int commit_idx)
 162 {
 163         struct nfs_writeverf *verfp = &dreq->verf;
 164
 165 #ifdef CONFIG_NFS_V4_1
 166         /*
 167          * pNFS is in use, use the DS verf except commit_through_mds is set
 168          * for layout segment where nbuckets is zero.
 169          */
 170         if (ds_clp && dreq->ds_cinfo.nbuckets > 0) {
 171                 if (commit_idx >= 0 && commit_idx < dreq->ds_cinfo.nbuckets)
 172                         verfp = &dreq->ds_cinfo.buckets[commit_idx].direct_verf;
 173                 else
 174                         WARN_ON_ONCE(1);
 175         }
 176 #endif
 177         return verfp;
 178 }
 179
 180
 181 /*
 182  * nfs_direct_set_hdr_verf - set the write/commit verifier
 183  * @dreq - direct request possibly spanning multiple servers
 184  * @hdr - pageio header to validate against previously seen verfs
 185  *
 186  * Set the server's (MDS or DS) "seen" verifier
 187  */
 188 static void nfs_direct_set_hdr_verf(struct nfs_direct_req *dreq,
 189                                     struct nfs_pgio_header *hdr)
 190 {
 191         struct nfs_writeverf *verfp;
 192
 193         verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
 194         WARN_ON_ONCE(verfp->committed >= 0);
 195         memcpy(verfp, &hdr->verf, sizeof(struct nfs_writeverf));
 196         WARN_ON_ONCE(verfp->committed < 0);
 197 }
 198
 199 static int nfs_direct_cmp_verf(const struct nfs_writeverf *v1,
 200                 const struct nfs_writeverf *v2)
 201 {
 202         return nfs_write_verifier_cmp(&v1->verifier, &v2->verifier);
 203 }
 204
 205 /*
 206  * nfs_direct_cmp_hdr_verf - compare verifier for pgio header
 207  * @dreq - direct request possibly spanning multiple servers
 208  * @hdr - pageio header to validate against previously seen verf
 209  *
 210  * set the server's "seen" verf if not initialized.
 211  * returns result of comparison between @hdr->verf and the "seen"
 212  * verf of the server used by @hdr (DS or MDS)
 213  */
 214 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req *dreq,
 215                                           struct nfs_pgio_header *hdr)
 216 {
 217         struct nfs_writeverf *verfp;
 218
 219         verfp = nfs_direct_select_verf(dreq, hdr->ds_clp, hdr->ds_commit_idx);
 220         if (verfp->committed < 0) {
 221                 nfs_direct_set_hdr_verf(dreq, hdr);
 222                 return 0;
 223         }
 224         return nfs_direct_cmp_verf(verfp, &hdr->verf);
 225 }
 226
 227 /*
 228  * nfs_direct_cmp_commit_data_verf - compare verifier for commit data
 229  * @dreq - direct request possibly spanning multiple servers
 230  * @data - commit data to validate against previously seen verf
 231  *
 232  * returns result of comparison between @data->verf and the verf of
 233  * the server used by @data (DS or MDS)
 234  */
 235 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req *dreq,
 236                                            struct nfs_commit_data *data)
 237 {
 238         struct nfs_writeverf *verfp;
 239
 240         verfp = nfs_direct_select_verf(dreq, data->ds_clp,
 241                                          data->ds_commit_index);
 242
 243         /* verifier not set so always fail */
 244         if (verfp->committed < 0)
 245                 return 1;
 246
 247         return nfs_direct_cmp_verf(verfp, &data->verf);
 248 }
 249
 250 /**
 251  * nfs_direct_IO - NFS address space operation for direct I/O
 252  * @iocb: target I/O control block
 253  * @iter: I/O buffer
 254  *
 255  * The presence of this routine in the address space ops vector means
 256  * the NFS client supports direct I/O. However, for most direct IO, we
 257  * shunt off direct read and write requests before the VFS gets them,
 258  * so this method is only ever called for swap.
 259  */
 260 ssize_t nfs_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 261 {
 262         struct inode *inode = iocb->ki_filp->f_mapping->host;
 263
 264         /* we only support swap file calling nfs_direct_IO */
 265         if (!IS_SWAPFILE(inode))
 266                 return 0;
 267
 268         VM_BUG_ON(iov_iter_count(iter) != PAGE_SIZE);
 269
 270         if (iov_iter_rw(iter) == READ)
 271                 return nfs_file_direct_read(iocb, iter);
 272         return nfs_file_direct_write(iocb, iter);
 273 }
 274
 275 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
 276 {
 277         unsigned int i;
 278         for (i = 0; i < npages; i++)
 279                 put_page(pages[i]);
 280 }
 281
 282 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 283                               struct nfs_direct_req *dreq)
 284 {
 285         cinfo->inode = dreq->inode;
 286         cinfo->mds = &dreq->mds_cinfo;
 287         cinfo->ds = &dreq->ds_cinfo;
 288         cinfo->dreq = dreq;
 289         cinfo->completion_ops = &nfs_direct_commit_completion_ops;
 290 }
 291
 292 static inline void nfs_direct_setup_mirroring(struct nfs_direct_req *dreq,
 293                                              struct nfs_pageio_descriptor *pgio,
 294                                              struct nfs_page *req)
 295 {
 296         int mirror_count = 1;
 297
 298         if (pgio->pg_ops->pg_get_mirror_count)
 299                 mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 300
 301         dreq->mirror_count = mirror_count;
 302 }
 303
 304 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 305 {
 306         struct nfs_direct_req *dreq;
 307
 308         dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
 309         if (!dreq)
 310                 return NULL;
 311
 312         kref_init(&dreq->kref);
 313         kref_get(&dreq->kref);
 314         init_completion(&dreq->completion);
 315         INIT_LIST_HEAD(&dreq->mds_cinfo.list);
 316         dreq->verf.committed = NFS_INVALID_STABLE_HOW;  /* not set yet */
 317         INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
 318         dreq->mirror_count = 1;
 319         spin_lock_init(&dreq->lock);
 320
 321         return dreq;
 322 }
 323
 324 static void nfs_direct_req_free(struct kref *kref)
 325 {
 326         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 327
 328         nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
 329         if (dreq->l_ctx != NULL)
 330                 nfs_put_lock_context(dreq->l_ctx);
 331         if (dreq->ctx != NULL)
 332                 put_nfs_open_context(dreq->ctx);
 333         kmem_cache_free(nfs_direct_cachep, dreq);
 334 }
 335
 336 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 337 {
 338         kref_put(&dreq->kref, nfs_direct_req_free);
 339 }
 340
 341 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
 342 {
 343         return dreq->bytes_left;
 344 }
 345 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
 346
 347 /*
 348  * Collects and returns the final error value/byte-count.
 349  */
 350 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
 351 {
 352         ssize_t result = -EIOCBQUEUED;
 353
 354         /* Async requests don't wait here */
 355         if (dreq->iocb)
 356                 goto out;
 357
 358         result = wait_for_completion_killable(&dreq->completion);
 359
 360         if (!result) {
 361                 result = dreq->count;
 362                 WARN_ON_ONCE(dreq->count < 0);
 363         }
 364         if (!result)
 365                 result = dreq->error;
 366
 367 out:
 368         return (ssize_t) result;
 369 }
 370
 371 /*
 372  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 373  * the iocb is still valid here if this is a synchronous request.
 374  */
 375 static void nfs_direct_complete(struct nfs_direct_req *dreq)
 376 {
 377         struct inode *inode = dreq->inode;
 378
 379         inode_dio_end(inode);
 380
 381         if (dreq->iocb) {
 382                 long res = (long) dreq->error;
 383                 if (dreq->count != 0) {
 384                         res = (long) dreq->count;
 385                         WARN_ON_ONCE(dreq->count < 0);
 386                 }
 387                 dreq->iocb->ki_complete(dreq->iocb, res, 0);
 388         }
 389
 390         complete_all(&dreq->completion);
 391
 392         nfs_direct_req_release(dreq);
 393 }
 394
 395 static void nfs_direct_readpage_release(struct nfs_page *req)
 396 {
 397         dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
 398                 req->wb_context->dentry->d_sb->s_id,
 399                 (unsigned long long)NFS_FILEID(d_inode(req->wb_context->dentry)),
 400                 req->wb_bytes,
 401                 (long long)req_offset(req));
 402         nfs_release_request(req);
 403 }
 404
 405 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 406 {
 407         unsigned long bytes = 0;
 408         struct nfs_direct_req *dreq = hdr->dreq;
 409
 410         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 411                 goto out_put;
 412
 413         spin_lock(&dreq->lock);
 414         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
 415                 dreq->error = hdr->error;
 416         else
 417                 nfs_direct_good_bytes(dreq, hdr);
 418
 419         spin_unlock(&dreq->lock);
 420
 421         while (!list_empty(&hdr->pages)) {
 422                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 423                 struct page *page = req->wb_page;
 424
 425                 if (!PageCompound(page) && bytes < hdr->good_bytes)
 426                         set_page_dirty(page);
 427                 bytes += req->wb_bytes;
 428                 nfs_list_remove_request(req);
 429                 nfs_direct_readpage_release(req);
 430         }
 431 out_put:
 432         if (put_dreq(dreq))
 433                 nfs_direct_complete(dreq);
 434         hdr->release(hdr);
 435 }
 436
 437 static void nfs_read_sync_pgio_error(struct list_head *head)
 438 {
 439         struct nfs_page *req;
 440
 441         while (!list_empty(head)) {
 442                 req = nfs_list_entry(head->next);
 443                 nfs_list_remove_request(req);
 444                 nfs_release_request(req);
 445         }
 446 }
 447
 448 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
 449 {
 450         get_dreq(hdr->dreq);
 451 }
 452
 453 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
 454         .error_cleanup = nfs_read_sync_pgio_error,
 455         .init_hdr = nfs_direct_pgio_init,
 456         .completion = nfs_direct_read_completion,
 457 };
 458
 459 /*
 460  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 461  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 462  * bail and stop sending more reads.  Read length accounting is
 463  * handled automatically by nfs_direct_read_result().  Otherwise, if
 464  * no requests have been sent, just return an error.
 465  */
 466
 467 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 468                                               struct iov_iter *iter,
 469                                               loff_t pos)
 470 {
 471         struct nfs_pageio_descriptor desc;
 472         struct inode *inode = dreq->inode;
 473         ssize_t result = -EINVAL;
 474         size_t requested_bytes = 0;
 475         size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
 476
 477         nfs_pageio_init_read(&desc, dreq->inode, false,
 478                              &nfs_direct_read_completion_ops);
 479         get_dreq(dreq);
 480         desc.pg_dreq = dreq;
 481         inode_dio_begin(inode);
 482
 483         while (iov_iter_count(iter)) {
 484                 struct page **pagevec;
 485                 size_t bytes;
 486                 size_t pgbase;
 487                 unsigned npages, i;
 488
 489                 result = iov_iter_get_pages_alloc(iter, &pagevec,
 490                                                   rsize, &pgbase);
 491                 if (result < 0)
 492                         break;
 493
 494                 bytes = result;
 495                 iov_iter_advance(iter, bytes);
 496                 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 497                 for (i = 0; i < npages; i++) {
 498                         struct nfs_page *req;
 499                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 500                         /* XXX do we need to do the eof zeroing found in async_filler? */
 501                         req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
 502                                                  pgbase, req_len);
 503                         if (IS_ERR(req)) {
 504                                 result = PTR_ERR(req);
 505                                 break;
 506                         }
 507                         req->wb_index = pos >> PAGE_SHIFT;
 508                         req->wb_offset = pos & ~PAGE_MASK;
 509                         if (!nfs_pageio_add_request(&desc, req)) {
 510                                 result = desc.pg_error;
 511                                 nfs_release_request(req);
 512                                 break;
 513                         }
 514                         pgbase = 0;
 515                         bytes -= req_len;
 516                         requested_bytes += req_len;
 517                         pos += req_len;
 518                         dreq->bytes_left -= req_len;
 519                 }
 520                 nfs_direct_release_pages(pagevec, npages);
 521                 kvfree(pagevec);
 522                 if (result < 0)
 523                         break;
 524         }
 525
 526         nfs_pageio_complete(&desc);
 527
 528         /*
 529          * If no bytes were started, return the error, and let the
 530          * generic layer handle the completion.
 531          */
 532         if (requested_bytes == 0) {
 533                 inode_dio_end(inode);
 534                 nfs_direct_req_release(dreq);
 535                 return result < 0 ? result : -EIO;
 536         }
 537
 538         if (put_dreq(dreq))
 539                 nfs_direct_complete(dreq);
 540         return 0;
 541 }
 542
 543 /**
 544  * nfs_file_direct_read - file direct read operation for NFS files
 545  * @iocb: target I/O control block
 546  * @iter: vector of user buffers into which to read data
 547  *
 548  * We use this function for direct reads instead of calling
 549  * generic_file_aio_read() in order to avoid gfar's check to see if
 550  * the request starts before the end of the file.  For that check
 551  * to work, we must generate a GETATTR before each direct read, and
 552  * even then there is a window between the GETATTR and the subsequent
 553  * READ where the file size could change.  Our preference is simply
 554  * to do all reads the application wants, and the server will take
 555  * care of managing the end of file boundary.
 556  *
 557  * This function also eliminates unnecessarily updating the file's
 558  * atime locally, as the NFS server sets the file's atime, and this
 559  * client must read the updated atime from the server back into its
 560  * cache.
 561  */
 562 ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter)
 563 {
 564         struct file *file = iocb->ki_filp;
 565         struct address_space *mapping = file->f_mapping;
 566         struct inode *inode = mapping->host;
 567         struct nfs_direct_req *dreq;
 568         struct nfs_lock_context *l_ctx;
 569         ssize_t result = -EINVAL;
 570         size_t count = iov_iter_count(iter);
 571         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 572
 573         dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
 574                 file, count, (long long) iocb->ki_pos);
 575
 576         result = 0;
 577         if (!count)
 578                 goto out;
 579
 580         task_io_account_read(count);
 581
 582         result = -ENOMEM;
 583         dreq = nfs_direct_req_alloc();
 584         if (dreq == NULL)
 585                 goto out;
 586
 587         dreq->inode = inode;
 588         dreq->bytes_left = dreq->max_count = count;
 589         dreq->io_start = iocb->ki_pos;
 590         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 591         l_ctx = nfs_get_lock_context(dreq->ctx);
 592         if (IS_ERR(l_ctx)) {
 593                 result = PTR_ERR(l_ctx);
 594                 goto out_release;
 595         }
 596         dreq->l_ctx = l_ctx;
 597         if (!is_sync_kiocb(iocb))
 598                 dreq->iocb = iocb;
 599
 600         nfs_start_io_direct(inode);
 601
 602         NFS_I(inode)->read_io += count;
 603         result = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
 604
 605         nfs_end_io_direct(inode);
 606
 607         if (!result) {
 608                 result = nfs_direct_wait(dreq);
 609                 if (result > 0)
 610                         iocb->ki_pos += result;
 611         }
 612
 613 out_release:
 614         nfs_direct_req_release(dreq);
 615 out:
 616         return result;
 617 }
 618
 619 static void
 620 nfs_direct_write_scan_commit_list(struct inode *inode,
 621                                   struct list_head *list,
 622                                   struct nfs_commit_info *cinfo)
 623 {
 624         spin_lock(&cinfo->inode->i_lock);
 625 #ifdef CONFIG_NFS_V4_1
 626         if (cinfo->ds != NULL && cinfo->ds->nwritten != 0)
 627                 NFS_SERVER(inode)->pnfs_curr_ld->recover_commit_reqs(list, cinfo);
 628 #endif
 629         nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
 630         spin_unlock(&cinfo->inode->i_lock);
 631 }
 632
 633 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 634 {
 635         struct nfs_pageio_descriptor desc;
 636         struct nfs_page *req, *tmp;
 637         LIST_HEAD(reqs);
 638         struct nfs_commit_info cinfo;
 639         LIST_HEAD(failed);
 640         int i;
 641
 642         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 643         nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
 644
 645         dreq->count = 0;
 646         dreq->verf.committed = NFS_INVALID_STABLE_HOW;
 647         nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
 648         for (i = 0; i < dreq->mirror_count; i++)
 649                 dreq->mirrors[i].count = 0;
 650         get_dreq(dreq);
 651
 652         nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
 653                               &nfs_direct_write_completion_ops);
 654         desc.pg_dreq = dreq;
 655
 656         req = nfs_list_entry(reqs.next);
 657         nfs_direct_setup_mirroring(dreq, &desc, req);
 658         if (desc.pg_error < 0) {
 659                 list_splice_init(&reqs, &failed);
 660                 goto out_failed;
 661         }
 662
 663         list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
 664                 if (!nfs_pageio_add_request(&desc, req)) {
 665                         nfs_list_remove_request(req);
 666                         nfs_list_add_request(req, &failed);
 667                         spin_lock(&cinfo.inode->i_lock);
 668                         dreq->flags = 0;
 669                         if (desc.pg_error < 0)
 670                                 dreq->error = desc.pg_error;
 671                         else
 672                                 dreq->error = -EIO;
 673                         spin_unlock(&cinfo.inode->i_lock);
 674                 }
 675                 nfs_release_request(req);
 676         }
 677         nfs_pageio_complete(&desc);
 678
 679 out_failed:
 680         while (!list_empty(&failed)) {
 681                 req = nfs_list_entry(failed.next);
 682                 nfs_list_remove_request(req);
 683                 nfs_unlock_and_release_request(req);
 684         }
 685
 686         if (put_dreq(dreq))
 687                 nfs_direct_write_complete(dreq, dreq->inode);
 688 }
 689
 690 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
 691 {
 692         struct nfs_direct_req *dreq = data->dreq;
 693         struct nfs_commit_info cinfo;
 694         struct nfs_page *req;
 695         int status = data->task.tk_status;
 696
 697         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 698         if (status < 0) {
 699                 dprintk("NFS: %5u commit failed with error %d.\n",
 700                         data->task.tk_pid, status);
 701                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 702         } else if (nfs_direct_cmp_commit_data_verf(dreq, data)) {
 703                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
 704                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 705         }
 706
 707         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
 708         while (!list_empty(&data->pages)) {
 709                 req = nfs_list_entry(data->pages.next);
 710                 nfs_list_remove_request(req);
 711                 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
 712                         /* Note the rewrite will go through mds */
 713                         nfs_mark_request_commit(req, NULL, &cinfo, 0);
 714                 } else
 715                         nfs_release_request(req);
 716                 nfs_unlock_and_release_request(req);
 717         }
 718
 719         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
 720                 nfs_direct_write_complete(dreq, data->inode);
 721 }
 722
 723 static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
 724                 struct nfs_page *req)
 725 {
 726         struct nfs_direct_req *dreq = cinfo->dreq;
 727
 728         spin_lock(&dreq->lock);
 729         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 730         spin_unlock(&dreq->lock);
 731         nfs_mark_request_commit(req, NULL, cinfo, 0);
 732 }
 733
 734 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
 735         .completion = nfs_direct_commit_complete,
 736         .resched_write = nfs_direct_resched_write,
 737 };
 738
 739 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 740 {
 741         int res;
 742         struct nfs_commit_info cinfo;
 743         LIST_HEAD(mds_list);
 744
 745         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 746         nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
 747         res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
 748         if (res < 0) /* res == -ENOMEM */
 749                 nfs_direct_write_reschedule(dreq);
 750 }
 751
 752 static void nfs_direct_write_schedule_work(struct work_struct *work)
 753 {
 754         struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
 755         int flags = dreq->flags;
 756
 757         dreq->flags = 0;
 758         switch (flags) {
 759                 case NFS_ODIRECT_DO_COMMIT:
 760                         nfs_direct_commit_schedule(dreq);
 761                         break;
 762                 case NFS_ODIRECT_RESCHED_WRITES:
 763                         nfs_direct_write_reschedule(dreq);
 764                         break;
 765                 default:
 766                         nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
 767                         nfs_direct_complete(dreq);
 768         }
 769 }
 770
 771 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 772 {
 773         schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
 774 }
 775
 776 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 777 {
 778         struct nfs_direct_req *dreq = hdr->dreq;
 779         struct nfs_commit_info cinfo;
 780         bool request_commit = false;
 781         struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 782
 783         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 784                 goto out_put;
 785
 786         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 787
 788         spin_lock(&dreq->lock);
 789
 790         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 791                 dreq->flags = 0;
 792                 dreq->error = hdr->error;
 793         }
 794         if (dreq->error == 0) {
 795                 nfs_direct_good_bytes(dreq, hdr);
 796                 if (nfs_write_need_commit(hdr)) {
 797                         if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
 798                                 request_commit = true;
 799                         else if (dreq->flags == 0) {
 800                                 nfs_direct_set_hdr_verf(dreq, hdr);
 801                                 request_commit = true;
 802                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
 803                         } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
 804                                 request_commit = true;
 805                                 if (nfs_direct_set_or_cmp_hdr_verf(dreq, hdr))
 806                                         dreq->flags =
 807                                                 NFS_ODIRECT_RESCHED_WRITES;
 808                         }
 809                 }
 810         }
 811         spin_unlock(&dreq->lock);
 812
 813         while (!list_empty(&hdr->pages)) {
 814
 815                 req = nfs_list_entry(hdr->pages.next);
 816                 nfs_list_remove_request(req);
 817                 if (request_commit) {
 818                         kref_get(&req->wb_kref);
 819                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
 820                                 hdr->ds_commit_idx);
 821                 }
 822                 nfs_unlock_and_release_request(req);
 823         }
 824
 825 out_put:
 826         if (put_dreq(dreq))
 827                 nfs_direct_write_complete(dreq, hdr->inode);
 828         hdr->release(hdr);
 829 }
 830
 831 static void nfs_write_sync_pgio_error(struct list_head *head)
 832 {
 833         struct nfs_page *req;
 834
 835         while (!list_empty(head)) {
 836                 req = nfs_list_entry(head->next);
 837                 nfs_list_remove_request(req);
 838                 nfs_unlock_and_release_request(req);
 839         }
 840 }
 841
 842 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
 843 {
 844         struct nfs_direct_req *dreq = hdr->dreq;
 845
 846         spin_lock(&dreq->lock);
 847         if (dreq->error == 0) {
 848                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 849                 /* fake unstable write to let common nfs resend pages */
 850                 hdr->verf.committed = NFS_UNSTABLE;
 851                 hdr->good_bytes = hdr->args.count;
 852         }
 853         spin_unlock(&dreq->lock);
 854 }
 855
 856 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
 857         .error_cleanup = nfs_write_sync_pgio_error,
 858         .init_hdr = nfs_direct_pgio_init,
 859         .completion = nfs_direct_write_completion,
 860         .reschedule_io = nfs_direct_write_reschedule_io,
 861 };
 862
 863
 864 /*
 865  * NB: Return the value of the first error return code.  Subsequent
 866  *     errors after the first one are ignored.
 867  */
 868 /*
 869  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 870  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 871  * bail and stop sending more writes.  Write length accounting is
 872  * handled automatically by nfs_direct_write_result().  Otherwise, if
 873  * no requests have been sent, just return an error.
 874  */
 875 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 876                                                struct iov_iter *iter,
 877                                                loff_t pos)
 878 {
 879         struct nfs_pageio_descriptor desc;
 880         struct inode *inode = dreq->inode;
 881         ssize_t result = 0;
 882         size_t requested_bytes = 0;
 883         size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
 884
 885         nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE, false,
 886                               &nfs_direct_write_completion_ops);
 887         desc.pg_dreq = dreq;
 888         get_dreq(dreq);
 889         inode_dio_begin(inode);
 890
 891         NFS_I(inode)->write_io += iov_iter_count(iter);
 892         while (iov_iter_count(iter)) {
 893                 struct page **pagevec;
 894                 size_t bytes;
 895                 size_t pgbase;
 896                 unsigned npages, i;
 897
 898                 result = iov_iter_get_pages_alloc(iter, &pagevec,
 899                                                   wsize, &pgbase);
 900                 if (result < 0)
 901                         break;
 902
 903                 bytes = result;
 904                 iov_iter_advance(iter, bytes);
 905                 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
 906                 for (i = 0; i < npages; i++) {
 907                         struct nfs_page *req;
 908                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 909
 910                         req = nfs_create_request(dreq->ctx, pagevec[i], NULL,
 911                                                  pgbase, req_len);
 912                         if (IS_ERR(req)) {
 913                                 result = PTR_ERR(req);
 914                                 break;
 915                         }
 916
 917                         nfs_direct_setup_mirroring(dreq, &desc, req);
 918                         if (desc.pg_error < 0) {
 919                                 nfs_free_request(req);
 920                                 result = desc.pg_error;
 921                                 break;
 922                         }
 923
 924                         nfs_lock_request(req);
 925                         req->wb_index = pos >> PAGE_SHIFT;
 926                         req->wb_offset = pos & ~PAGE_MASK;
 927                         if (!nfs_pageio_add_request(&desc, req)) {
 928                                 result = desc.pg_error;
 929                                 nfs_unlock_and_release_request(req);
 930                                 break;
 931                         }
 932                         pgbase = 0;
 933                         bytes -= req_len;
 934                         requested_bytes += req_len;
 935                         pos += req_len;
 936                         dreq->bytes_left -= req_len;
 937                 }
 938                 nfs_direct_release_pages(pagevec, npages);
 939                 kvfree(pagevec);
 940                 if (result < 0)
 941                         break;
 942         }
 943         nfs_pageio_complete(&desc);
 944
 945         /*
 946          * If no bytes were started, return the error, and let the
 947          * generic layer handle the completion.
 948          */
 949         if (requested_bytes == 0) {
 950                 inode_dio_end(inode);
 951                 nfs_direct_req_release(dreq);
 952                 return result < 0 ? result : -EIO;
 953         }
 954
 955         if (put_dreq(dreq))
 956                 nfs_direct_write_complete(dreq, dreq->inode);
 957         return 0;
 958 }
 959
 960 /**
 961  * nfs_file_direct_write - file direct write operation for NFS files
 962  * @iocb: target I/O control block
 963  * @iter: vector of user buffers from which to write data
 964  *
 965  * We use this function for direct writes instead of calling
 966  * generic_file_aio_write() in order to avoid taking the inode
 967  * semaphore and updating the i_size.  The NFS server will set
 968  * the new i_size and this client must read the updated size
 969  * back into its cache.  We let the server do generic write
 970  * parameter checking and report problems.
 971  *
 972  * We eliminate local atime updates, see direct read above.
 973  *
 974  * We avoid unnecessary page cache invalidations for normal cached
 975  * readers of this file.
 976  *
 977  * Note that O_APPEND is not supported for NFS direct writes, as there
 978  * is no atomic O_APPEND write facility in the NFS protocol.
 979  */
 980 ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter)
 981 {
 982         ssize_t result = -EINVAL;
 983         size_t count;
 984         struct file *file = iocb->ki_filp;
 985         struct address_space *mapping = file->f_mapping;
 986         struct inode *inode = mapping->host;
 987         struct nfs_direct_req *dreq;
 988         struct nfs_lock_context *l_ctx;
 989         loff_t pos, end;
 990
 991         dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
 992                 file, iov_iter_count(iter), (long long) iocb->ki_pos);
 993
 994         result = generic_write_checks(iocb, iter);
 995         if (result <= 0)
 996                 return result;
 997         count = result;
 998         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 999
1000         pos = iocb->ki_pos;
1001         end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
1002
1003         task_io_account_write(count);
1004
1005         result = -ENOMEM;
1006         dreq = nfs_direct_req_alloc();
1007         if (!dreq)
1008                 goto out;
1009
1010         dreq->inode = inode;
1011         dreq->bytes_left = dreq->max_count = count;
1012         dreq->io_start = pos;
1013         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
1014         l_ctx = nfs_get_lock_context(dreq->ctx);
1015         if (IS_ERR(l_ctx)) {
1016                 result = PTR_ERR(l_ctx);
1017                 goto out_release;
1018         }
1019         dreq->l_ctx = l_ctx;
1020         if (!is_sync_kiocb(iocb))
1021                 dreq->iocb = iocb;
1022
1023         nfs_start_io_direct(inode);
1024
1025         result = nfs_direct_write_schedule_iovec(dreq, iter, pos);
1026
1027         if (mapping->nrpages) {
1028                 invalidate_inode_pages2_range(mapping,
1029                                               pos >> PAGE_SHIFT, end);
1030         }
1031
1032         nfs_end_io_direct(inode);
1033
1034         if (!result) {
1035                 result = nfs_direct_wait(dreq);
1036                 if (result > 0) {
1037                         iocb->ki_pos = pos + result;
1038                         /* XXX: should check the generic_write_sync retval */
1039                         generic_write_sync(iocb, result);
1040                 }
1041         }
1042 out_release:
1043         nfs_direct_req_release(dreq);
1044 out:
1045         return result;
1046 }
1047
1048 /**
1049  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1050  *
1051  */
1052 int __init nfs_init_directcache(void)
1053 {
1054         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1055                                                 sizeof(struct nfs_direct_req),
1056                                                 0, (SLAB_RECLAIM_ACCOUNT|
1057                                                         SLAB_MEM_SPREAD),
1058                                                 NULL);
1059         if (nfs_direct_cachep == NULL)
1060                 return -ENOMEM;
1061
1062         return 0;
1063 }
1064
1065 /**
1066  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1067  *
1068  */
1069 void nfs_destroy_directcache(void)
1070 {
1071         kmem_cache_destroy(nfs_direct_cachep);
1072 }