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