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_req {
  70         struct kref             kref;           /* release manager */
  71
  72         /* I/O parameters */
  73         struct nfs_open_context *ctx;           /* file open context info */
  74         struct nfs_lock_context *l_ctx;         /* Lock context info */
  75         struct kiocb *          iocb;           /* controlling i/o request */
  76         struct inode *          inode;          /* target file of i/o */
  77
  78         /* completion state */
  79         atomic_t                io_count;       /* i/os we're waiting for */
  80         spinlock_t              lock;           /* protect completion state */
  81         ssize_t                 count,          /* bytes actually processed */
  82                                 bytes_left,     /* bytes left to be sent */
  83                                 error;          /* any reported error */
  84         struct completion       completion;     /* wait for i/o completion */
  85
  86         /* commit state */
  87         struct nfs_mds_commit_info mds_cinfo;   /* Storage for cinfo */
  88         struct pnfs_ds_commit_info ds_cinfo;    /* Storage for cinfo */
  89         struct work_struct      work;
  90         int                     flags;
  91 #define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
  92 #define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
  93         struct nfs_writeverf    verf;           /* unstable write verifier */
  94 };
  95
  96 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
  97 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
  98 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
  99 static void nfs_direct_write_schedule_work(struct work_struct *work);
 100
 101 static inline void get_dreq(struct nfs_direct_req *dreq)
 102 {
 103         atomic_inc(&dreq->io_count);
 104 }
 105
 106 static inline int put_dreq(struct nfs_direct_req *dreq)
 107 {
 108         return atomic_dec_and_test(&dreq->io_count);
 109 }
 110
 111 /**
 112  * nfs_direct_IO - NFS address space operation for direct I/O
 113  * @rw: direction (read or write)
 114  * @iocb: target I/O control block
 115  * @iov: array of vectors that define I/O buffer
 116  * @pos: offset in file to begin the operation
 117  * @nr_segs: size of iovec array
 118  *
 119  * The presence of this routine in the address space ops vector means
 120  * the NFS client supports direct I/O. However, for most direct IO, we
 121  * shunt off direct read and write requests before the VFS gets them,
 122  * so this method is only ever called for swap.
 123  */
 124 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
 125 {
 126         struct inode *inode = iocb->ki_filp->f_mapping->host;
 127
 128         /* we only support swap file calling nfs_direct_IO */
 129         if (!IS_SWAPFILE(inode))
 130                 return 0;
 131
 132 #ifndef CONFIG_NFS_SWAP
 133         dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
 134                         iocb->ki_filp->f_path.dentry->d_name.name,
 135                         (long long) pos, nr_segs);
 136
 137         return -EINVAL;
 138 #else
 139         VM_BUG_ON(iocb->ki_left != PAGE_SIZE);
 140         VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
 141
 142         if (rw == READ || rw == KERNEL_READ)
 143                 return nfs_file_direct_read(iocb, iov, nr_segs, pos,
 144                                 rw == READ ? true : false);
 145         return nfs_file_direct_write(iocb, iov, nr_segs, pos,
 146                                 rw == WRITE ? true : false);
 147 #endif /* CONFIG_NFS_SWAP */
 148 }
 149
 150 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
 151 {
 152         unsigned int i;
 153         for (i = 0; i < npages; i++)
 154                 page_cache_release(pages[i]);
 155 }
 156
 157 void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
 158                               struct nfs_direct_req *dreq)
 159 {
 160         cinfo->lock = &dreq->lock;
 161         cinfo->mds = &dreq->mds_cinfo;
 162         cinfo->ds = &dreq->ds_cinfo;
 163         cinfo->dreq = dreq;
 164         cinfo->completion_ops = &nfs_direct_commit_completion_ops;
 165 }
 166
 167 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
 168 {
 169         struct nfs_direct_req *dreq;
 170
 171         dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
 172         if (!dreq)
 173                 return NULL;
 174
 175         kref_init(&dreq->kref);
 176         kref_get(&dreq->kref);
 177         init_completion(&dreq->completion);
 178         INIT_LIST_HEAD(&dreq->mds_cinfo.list);
 179         INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
 180         spin_lock_init(&dreq->lock);
 181
 182         return dreq;
 183 }
 184
 185 static void nfs_direct_req_free(struct kref *kref)
 186 {
 187         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
 188
 189         nfs_free_pnfs_ds_cinfo(&dreq->ds_cinfo);
 190         if (dreq->l_ctx != NULL)
 191                 nfs_put_lock_context(dreq->l_ctx);
 192         if (dreq->ctx != NULL)
 193                 put_nfs_open_context(dreq->ctx);
 194         kmem_cache_free(nfs_direct_cachep, dreq);
 195 }
 196
 197 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
 198 {
 199         kref_put(&dreq->kref, nfs_direct_req_free);
 200 }
 201
 202 ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
 203 {
 204         return dreq->bytes_left;
 205 }
 206 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
 207
 208 /*
 209  * Collects and returns the final error value/byte-count.
 210  */
 211 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
 212 {
 213         ssize_t result = -EIOCBQUEUED;
 214
 215         /* Async requests don't wait here */
 216         if (dreq->iocb)
 217                 goto out;
 218
 219         result = wait_for_completion_killable(&dreq->completion);
 220
 221         if (!result)
 222                 result = dreq->error;
 223         if (!result)
 224                 result = dreq->count;
 225
 226 out:
 227         return (ssize_t) result;
 228 }
 229
 230 /*
 231  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
 232  * the iocb is still valid here if this is a synchronous request.
 233  */
 234 static void nfs_direct_complete(struct nfs_direct_req *dreq)
 235 {
 236         if (dreq->iocb) {
 237                 long res = (long) dreq->error;
 238                 if (!res)
 239                         res = (long) dreq->count;
 240                 aio_complete(dreq->iocb, res, 0);
 241         }
 242         complete_all(&dreq->completion);
 243
 244         nfs_direct_req_release(dreq);
 245 }
 246
 247 static void nfs_direct_readpage_release(struct nfs_page *req)
 248 {
 249         dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
 250                 req->wb_context->dentry->d_inode->i_sb->s_id,
 251                 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
 252                 req->wb_bytes,
 253                 (long long)req_offset(req));
 254         nfs_release_request(req);
 255 }
 256
 257 static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
 258 {
 259         unsigned long bytes = 0;
 260         struct nfs_direct_req *dreq = hdr->dreq;
 261
 262         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 263                 goto out_put;
 264
 265         spin_lock(&dreq->lock);
 266         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
 267                 dreq->error = hdr->error;
 268         else
 269                 dreq->count += hdr->good_bytes;
 270         spin_unlock(&dreq->lock);
 271
 272         while (!list_empty(&hdr->pages)) {
 273                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 274                 struct page *page = req->wb_page;
 275
 276                 if (!PageCompound(page) && bytes < hdr->good_bytes)
 277                         set_page_dirty(page);
 278                 bytes += req->wb_bytes;
 279                 nfs_list_remove_request(req);
 280                 nfs_direct_readpage_release(req);
 281         }
 282 out_put:
 283         if (put_dreq(dreq))
 284                 nfs_direct_complete(dreq);
 285         hdr->release(hdr);
 286 }
 287
 288 static void nfs_read_sync_pgio_error(struct list_head *head)
 289 {
 290         struct nfs_page *req;
 291
 292         while (!list_empty(head)) {
 293                 req = nfs_list_entry(head->next);
 294                 nfs_list_remove_request(req);
 295                 nfs_release_request(req);
 296         }
 297 }
 298
 299 static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
 300 {
 301         get_dreq(hdr->dreq);
 302 }
 303
 304 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
 305         .error_cleanup = nfs_read_sync_pgio_error,
 306         .init_hdr = nfs_direct_pgio_init,
 307         .completion = nfs_direct_read_completion,
 308 };
 309
 310 /*
 311  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
 312  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
 313  * bail and stop sending more reads.  Read length accounting is
 314  * handled automatically by nfs_direct_read_result().  Otherwise, if
 315  * no requests have been sent, just return an error.
 316  */
 317 static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
 318                                                 const struct iovec *iov,
 319                                                 loff_t pos, bool uio)
 320 {
 321         struct nfs_direct_req *dreq = desc->pg_dreq;
 322         struct nfs_open_context *ctx = dreq->ctx;
 323         struct inode *inode = ctx->dentry->d_inode;
 324         unsigned long user_addr = (unsigned long)iov->iov_base;
 325         size_t count = iov->iov_len;
 326         size_t rsize = NFS_SERVER(inode)->rsize;
 327         unsigned int pgbase;
 328         int result;
 329         ssize_t started = 0;
 330         struct page **pagevec = NULL;
 331         unsigned int npages;
 332
 333         do {
 334                 size_t bytes;
 335                 int i;
 336
 337                 pgbase = user_addr & ~PAGE_MASK;
 338                 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
 339
 340                 result = -ENOMEM;
 341                 npages = nfs_page_array_len(pgbase, bytes);
 342                 if (!pagevec)
 343                         pagevec = kmalloc(npages * sizeof(struct page *),
 344                                           GFP_KERNEL);
 345                 if (!pagevec)
 346                         break;
 347                 if (uio) {
 348                         down_read(&current->mm->mmap_sem);
 349                         result = get_user_pages(current, current->mm, user_addr,
 350                                         npages, 1, 0, pagevec, NULL);
 351                         up_read(&current->mm->mmap_sem);
 352                         if (result < 0)
 353                                 break;
 354                 } else {
 355                         WARN_ON(npages != 1);
 356                         result = get_kernel_page(user_addr, 1, pagevec);
 357                         if (WARN_ON(result != 1))
 358                                 break;
 359                 }
 360
 361                 if ((unsigned)result < npages) {
 362                         bytes = result * PAGE_SIZE;
 363                         if (bytes <= pgbase) {
 364                                 nfs_direct_release_pages(pagevec, result);
 365                                 break;
 366                         }
 367                         bytes -= pgbase;
 368                         npages = result;
 369                 }
 370
 371                 for (i = 0; i < npages; i++) {
 372                         struct nfs_page *req;
 373                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 374                         /* XXX do we need to do the eof zeroing found in async_filler? */
 375                         req = nfs_create_request(dreq->ctx, dreq->inode,
 376                                                  pagevec[i],
 377                                                  pgbase, req_len);
 378                         if (IS_ERR(req)) {
 379                                 result = PTR_ERR(req);
 380                                 break;
 381                         }
 382                         req->wb_index = pos >> PAGE_SHIFT;
 383                         req->wb_offset = pos & ~PAGE_MASK;
 384                         if (!nfs_pageio_add_request(desc, req)) {
 385                                 result = desc->pg_error;
 386                                 nfs_release_request(req);
 387                                 break;
 388                         }
 389                         pgbase = 0;
 390                         bytes -= req_len;
 391                         started += req_len;
 392                         user_addr += req_len;
 393                         pos += req_len;
 394                         count -= req_len;
 395                         dreq->bytes_left -= req_len;
 396                 }
 397                 /* The nfs_page now hold references to these pages */
 398                 nfs_direct_release_pages(pagevec, npages);
 399         } while (count != 0 && result >= 0);
 400
 401         kfree(pagevec);
 402
 403         if (started)
 404                 return started;
 405         return result < 0 ? (ssize_t) result : -EFAULT;
 406 }
 407
 408 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
 409                                               const struct iovec *iov,
 410                                               unsigned long nr_segs,
 411                                               loff_t pos, bool uio)
 412 {
 413         struct nfs_pageio_descriptor desc;
 414         ssize_t result = -EINVAL;
 415         size_t requested_bytes = 0;
 416         unsigned long seg;
 417
 418         NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
 419                              &nfs_direct_read_completion_ops);
 420         get_dreq(dreq);
 421         desc.pg_dreq = dreq;
 422
 423         for (seg = 0; seg < nr_segs; seg++) {
 424                 const struct iovec *vec = &iov[seg];
 425                 result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
 426                 if (result < 0)
 427                         break;
 428                 requested_bytes += result;
 429                 if ((size_t)result < vec->iov_len)
 430                         break;
 431                 pos += vec->iov_len;
 432         }
 433
 434         nfs_pageio_complete(&desc);
 435
 436         /*
 437          * If no bytes were started, return the error, and let the
 438          * generic layer handle the completion.
 439          */
 440         if (requested_bytes == 0) {
 441                 nfs_direct_req_release(dreq);
 442                 return result < 0 ? result : -EIO;
 443         }
 444
 445         if (put_dreq(dreq))
 446                 nfs_direct_complete(dreq);
 447         return 0;
 448 }
 449
 450 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
 451                                unsigned long nr_segs, loff_t pos, bool uio)
 452 {
 453         ssize_t result = -ENOMEM;
 454         struct inode *inode = iocb->ki_filp->f_mapping->host;
 455         struct nfs_direct_req *dreq;
 456         struct nfs_lock_context *l_ctx;
 457
 458         dreq = nfs_direct_req_alloc();
 459         if (dreq == NULL)
 460                 goto out;
 461
 462         dreq->inode = inode;
 463         dreq->bytes_left = iov_length(iov, nr_segs);
 464         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 465         l_ctx = nfs_get_lock_context(dreq->ctx);
 466         if (IS_ERR(l_ctx)) {
 467                 result = PTR_ERR(l_ctx);
 468                 goto out_release;
 469         }
 470         dreq->l_ctx = l_ctx;
 471         if (!is_sync_kiocb(iocb))
 472                 dreq->iocb = iocb;
 473
 474         NFS_I(inode)->read_io += iov_length(iov, nr_segs);
 475         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
 476         if (!result)
 477                 result = nfs_direct_wait(dreq);
 478 out_release:
 479         nfs_direct_req_release(dreq);
 480 out:
 481         return result;
 482 }
 483
 484 static void nfs_inode_dio_write_done(struct inode *inode)
 485 {
 486         nfs_zap_mapping(inode, inode->i_mapping);
 487         inode_dio_done(inode);
 488 }
 489
 490 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
 491 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 492 {
 493         struct nfs_pageio_descriptor desc;
 494         struct nfs_page *req, *tmp;
 495         LIST_HEAD(reqs);
 496         struct nfs_commit_info cinfo;
 497         LIST_HEAD(failed);
 498
 499         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 500         pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
 501         spin_lock(cinfo.lock);
 502         nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
 503         spin_unlock(cinfo.lock);
 504
 505         dreq->count = 0;
 506         get_dreq(dreq);
 507
 508         NFS_PROTO(dreq->inode)->write_pageio_init(&desc, dreq->inode, FLUSH_STABLE,
 509                               &nfs_direct_write_completion_ops);
 510         desc.pg_dreq = dreq;
 511
 512         list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
 513                 if (!nfs_pageio_add_request(&desc, req)) {
 514                         nfs_list_remove_request(req);
 515                         nfs_list_add_request(req, &failed);
 516                         spin_lock(cinfo.lock);
 517                         dreq->flags = 0;
 518                         dreq->error = -EIO;
 519                         spin_unlock(cinfo.lock);
 520                 }
 521                 nfs_release_request(req);
 522         }
 523         nfs_pageio_complete(&desc);
 524
 525         while (!list_empty(&failed)) {
 526                 req = nfs_list_entry(failed.next);
 527                 nfs_list_remove_request(req);
 528                 nfs_unlock_and_release_request(req);
 529         }
 530
 531         if (put_dreq(dreq))
 532                 nfs_direct_write_complete(dreq, dreq->inode);
 533 }
 534
 535 static void nfs_direct_commit_complete(struct nfs_commit_data *data)
 536 {
 537         struct nfs_direct_req *dreq = data->dreq;
 538         struct nfs_commit_info cinfo;
 539         struct nfs_page *req;
 540         int status = data->task.tk_status;
 541
 542         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 543         if (status < 0) {
 544                 dprintk("NFS: %5u commit failed with error %d.\n",
 545                         data->task.tk_pid, status);
 546                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 547         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
 548                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
 549                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 550         }
 551
 552         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
 553         while (!list_empty(&data->pages)) {
 554                 req = nfs_list_entry(data->pages.next);
 555                 nfs_list_remove_request(req);
 556                 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
 557                         /* Note the rewrite will go through mds */
 558                         nfs_mark_request_commit(req, NULL, &cinfo);
 559                 } else
 560                         nfs_release_request(req);
 561                 nfs_unlock_and_release_request(req);
 562         }
 563
 564         if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
 565                 nfs_direct_write_complete(dreq, data->inode);
 566 }
 567
 568 static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
 569 {
 570         /* There is no lock to clear */
 571 }
 572
 573 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
 574         .completion = nfs_direct_commit_complete,
 575         .error_cleanup = nfs_direct_error_cleanup,
 576 };
 577
 578 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
 579 {
 580         int res;
 581         struct nfs_commit_info cinfo;
 582         LIST_HEAD(mds_list);
 583
 584         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 585         nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
 586         res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
 587         if (res < 0) /* res == -ENOMEM */
 588                 nfs_direct_write_reschedule(dreq);
 589 }
 590
 591 static void nfs_direct_write_schedule_work(struct work_struct *work)
 592 {
 593         struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
 594         int flags = dreq->flags;
 595
 596         dreq->flags = 0;
 597         switch (flags) {
 598                 case NFS_ODIRECT_DO_COMMIT:
 599                         nfs_direct_commit_schedule(dreq);
 600                         break;
 601                 case NFS_ODIRECT_RESCHED_WRITES:
 602                         nfs_direct_write_reschedule(dreq);
 603                         break;
 604                 default:
 605                         nfs_inode_dio_write_done(dreq->inode);
 606                         nfs_direct_complete(dreq);
 607         }
 608 }
 609
 610 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 611 {
 612         schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
 613 }
 614
 615 #else
 616 static void nfs_direct_write_schedule_work(struct work_struct *work)
 617 {
 618 }
 619
 620 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
 621 {
 622         nfs_inode_dio_write_done(inode);
 623         nfs_direct_complete(dreq);
 624 }
 625 #endif
 626
 627 /*
 628  * NB: Return the value of the first error return code.  Subsequent
 629  *     errors after the first one are ignored.
 630  */
 631 /*
 632  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
 633  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
 634  * bail and stop sending more writes.  Write length accounting is
 635  * handled automatically by nfs_direct_write_result().  Otherwise, if
 636  * no requests have been sent, just return an error.
 637  */
 638 static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
 639                                                  const struct iovec *iov,
 640                                                  loff_t pos, bool uio)
 641 {
 642         struct nfs_direct_req *dreq = desc->pg_dreq;
 643         struct nfs_open_context *ctx = dreq->ctx;
 644         struct inode *inode = ctx->dentry->d_inode;
 645         unsigned long user_addr = (unsigned long)iov->iov_base;
 646         size_t count = iov->iov_len;
 647         size_t wsize = NFS_SERVER(inode)->wsize;
 648         unsigned int pgbase;
 649         int result;
 650         ssize_t started = 0;
 651         struct page **pagevec = NULL;
 652         unsigned int npages;
 653
 654         do {
 655                 size_t bytes;
 656                 int i;
 657
 658                 pgbase = user_addr & ~PAGE_MASK;
 659                 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
 660
 661                 result = -ENOMEM;
 662                 npages = nfs_page_array_len(pgbase, bytes);
 663                 if (!pagevec)
 664                         pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
 665                 if (!pagevec)
 666                         break;
 667
 668                 if (uio) {
 669                         down_read(&current->mm->mmap_sem);
 670                         result = get_user_pages(current, current->mm, user_addr,
 671                                                 npages, 0, 0, pagevec, NULL);
 672                         up_read(&current->mm->mmap_sem);
 673                         if (result < 0)
 674                                 break;
 675                 } else {
 676                         WARN_ON(npages != 1);
 677                         result = get_kernel_page(user_addr, 0, pagevec);
 678                         if (WARN_ON(result != 1))
 679                                 break;
 680                 }
 681
 682                 if ((unsigned)result < npages) {
 683                         bytes = result * PAGE_SIZE;
 684                         if (bytes <= pgbase) {
 685                                 nfs_direct_release_pages(pagevec, result);
 686                                 break;
 687                         }
 688                         bytes -= pgbase;
 689                         npages = result;
 690                 }
 691
 692                 for (i = 0; i < npages; i++) {
 693                         struct nfs_page *req;
 694                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
 695
 696                         req = nfs_create_request(dreq->ctx, dreq->inode,
 697                                                  pagevec[i],
 698                                                  pgbase, req_len);
 699                         if (IS_ERR(req)) {
 700                                 result = PTR_ERR(req);
 701                                 break;
 702                         }
 703                         nfs_lock_request(req);
 704                         req->wb_index = pos >> PAGE_SHIFT;
 705                         req->wb_offset = pos & ~PAGE_MASK;
 706                         if (!nfs_pageio_add_request(desc, req)) {
 707                                 result = desc->pg_error;
 708                                 nfs_unlock_and_release_request(req);
 709                                 break;
 710                         }
 711                         pgbase = 0;
 712                         bytes -= req_len;
 713                         started += req_len;
 714                         user_addr += req_len;
 715                         pos += req_len;
 716                         count -= req_len;
 717                         dreq->bytes_left -= req_len;
 718                 }
 719                 /* The nfs_page now hold references to these pages */
 720                 nfs_direct_release_pages(pagevec, npages);
 721         } while (count != 0 && result >= 0);
 722
 723         kfree(pagevec);
 724
 725         if (started)
 726                 return started;
 727         return result < 0 ? (ssize_t) result : -EFAULT;
 728 }
 729
 730 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 731 {
 732         struct nfs_direct_req *dreq = hdr->dreq;
 733         struct nfs_commit_info cinfo;
 734         int bit = -1;
 735         struct nfs_page *req = nfs_list_entry(hdr->pages.next);
 736
 737         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
 738                 goto out_put;
 739
 740         nfs_init_cinfo_from_dreq(&cinfo, dreq);
 741
 742         spin_lock(&dreq->lock);
 743
 744         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
 745                 dreq->flags = 0;
 746                 dreq->error = hdr->error;
 747         }
 748         if (dreq->error != 0)
 749                 bit = NFS_IOHDR_ERROR;
 750         else {
 751                 dreq->count += hdr->good_bytes;
 752                 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
 753                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 754                         bit = NFS_IOHDR_NEED_RESCHED;
 755                 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
 756                         if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
 757                                 bit = NFS_IOHDR_NEED_RESCHED;
 758                         else if (dreq->flags == 0) {
 759                                 memcpy(&dreq->verf, hdr->verf,
 760                                        sizeof(dreq->verf));
 761                                 bit = NFS_IOHDR_NEED_COMMIT;
 762                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
 763                         } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
 764                                 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
 765                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
 766                                         bit = NFS_IOHDR_NEED_RESCHED;
 767                                 } else
 768                                         bit = NFS_IOHDR_NEED_COMMIT;
 769                         }
 770                 }
 771         }
 772         spin_unlock(&dreq->lock);
 773
 774         while (!list_empty(&hdr->pages)) {
 775                 req = nfs_list_entry(hdr->pages.next);
 776                 nfs_list_remove_request(req);
 777                 switch (bit) {
 778                 case NFS_IOHDR_NEED_RESCHED:
 779                 case NFS_IOHDR_NEED_COMMIT:
 780                         kref_get(&req->wb_kref);
 781                         nfs_mark_request_commit(req, hdr->lseg, &cinfo);
 782                 }
 783                 nfs_unlock_and_release_request(req);
 784         }
 785
 786 out_put:
 787         if (put_dreq(dreq))
 788                 nfs_direct_write_complete(dreq, hdr->inode);
 789         hdr->release(hdr);
 790 }
 791
 792 static void nfs_write_sync_pgio_error(struct list_head *head)
 793 {
 794         struct nfs_page *req;
 795
 796         while (!list_empty(head)) {
 797                 req = nfs_list_entry(head->next);
 798                 nfs_list_remove_request(req);
 799                 nfs_unlock_and_release_request(req);
 800         }
 801 }
 802
 803 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
 804         .error_cleanup = nfs_write_sync_pgio_error,
 805         .init_hdr = nfs_direct_pgio_init,
 806         .completion = nfs_direct_write_completion,
 807 };
 808
 809 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
 810                                                const struct iovec *iov,
 811                                                unsigned long nr_segs,
 812                                                loff_t pos, bool uio)
 813 {
 814         struct nfs_pageio_descriptor desc;
 815         struct inode *inode = dreq->inode;
 816         ssize_t result = 0;
 817         size_t requested_bytes = 0;
 818         unsigned long seg;
 819
 820         NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
 821                               &nfs_direct_write_completion_ops);
 822         desc.pg_dreq = dreq;
 823         get_dreq(dreq);
 824         atomic_inc(&inode->i_dio_count);
 825
 826         NFS_I(dreq->inode)->write_io += iov_length(iov, nr_segs);
 827         for (seg = 0; seg < nr_segs; seg++) {
 828                 const struct iovec *vec = &iov[seg];
 829                 result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
 830                 if (result < 0)
 831                         break;
 832                 requested_bytes += result;
 833                 if ((size_t)result < vec->iov_len)
 834                         break;
 835                 pos += vec->iov_len;
 836         }
 837         nfs_pageio_complete(&desc);
 838
 839         /*
 840          * If no bytes were started, return the error, and let the
 841          * generic layer handle the completion.
 842          */
 843         if (requested_bytes == 0) {
 844                 inode_dio_done(inode);
 845                 nfs_direct_req_release(dreq);
 846                 return result < 0 ? result : -EIO;
 847         }
 848
 849         if (put_dreq(dreq))
 850                 nfs_direct_write_complete(dreq, dreq->inode);
 851         return 0;
 852 }
 853
 854 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
 855                                 unsigned long nr_segs, loff_t pos,
 856                                 size_t count, bool uio)
 857 {
 858         ssize_t result = -ENOMEM;
 859         struct inode *inode = iocb->ki_filp->f_mapping->host;
 860         struct nfs_direct_req *dreq;
 861         struct nfs_lock_context *l_ctx;
 862
 863         dreq = nfs_direct_req_alloc();
 864         if (!dreq)
 865                 goto out;
 866
 867         dreq->inode = inode;
 868         dreq->bytes_left = count;
 869         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
 870         l_ctx = nfs_get_lock_context(dreq->ctx);
 871         if (IS_ERR(l_ctx)) {
 872                 result = PTR_ERR(l_ctx);
 873                 goto out_release;
 874         }
 875         dreq->l_ctx = l_ctx;
 876         if (!is_sync_kiocb(iocb))
 877                 dreq->iocb = iocb;
 878
 879         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
 880         if (!result)
 881                 result = nfs_direct_wait(dreq);
 882 out_release:
 883         nfs_direct_req_release(dreq);
 884 out:
 885         return result;
 886 }
 887
 888 /**
 889  * nfs_file_direct_read - file direct read operation for NFS files
 890  * @iocb: target I/O control block
 891  * @iov: vector of user buffers into which to read data
 892  * @nr_segs: size of iov vector
 893  * @pos: byte offset in file where reading starts
 894  *
 895  * We use this function for direct reads instead of calling
 896  * generic_file_aio_read() in order to avoid gfar's check to see if
 897  * the request starts before the end of the file.  For that check
 898  * to work, we must generate a GETATTR before each direct read, and
 899  * even then there is a window between the GETATTR and the subsequent
 900  * READ where the file size could change.  Our preference is simply
 901  * to do all reads the application wants, and the server will take
 902  * care of managing the end of file boundary.
 903  *
 904  * This function also eliminates unnecessarily updating the file's
 905  * atime locally, as the NFS server sets the file's atime, and this
 906  * client must read the updated atime from the server back into its
 907  * cache.
 908  */
 909 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
 910                                 unsigned long nr_segs, loff_t pos, bool uio)
 911 {
 912         ssize_t retval = -EINVAL;
 913         struct file *file = iocb->ki_filp;
 914         struct address_space *mapping = file->f_mapping;
 915         size_t count;
 916
 917         count = iov_length(iov, nr_segs);
 918         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
 919
 920         dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
 921                 file->f_path.dentry->d_parent->d_name.name,
 922                 file->f_path.dentry->d_name.name,
 923                 count, (long long) pos);
 924
 925         retval = 0;
 926         if (!count)
 927                 goto out;
 928
 929         retval = nfs_sync_mapping(mapping);
 930         if (retval)
 931                 goto out;
 932
 933         task_io_account_read(count);
 934
 935         retval = nfs_direct_read(iocb, iov, nr_segs, pos, uio);
 936         if (retval > 0)
 937                 iocb->ki_pos = pos + retval;
 938
 939 out:
 940         return retval;
 941 }
 942
 943 /**
 944  * nfs_file_direct_write - file direct write operation for NFS files
 945  * @iocb: target I/O control block
 946  * @iov: vector of user buffers from which to write data
 947  * @nr_segs: size of iov vector
 948  * @pos: byte offset in file where writing starts
 949  *
 950  * We use this function for direct writes instead of calling
 951  * generic_file_aio_write() in order to avoid taking the inode
 952  * semaphore and updating the i_size.  The NFS server will set
 953  * the new i_size and this client must read the updated size
 954  * back into its cache.  We let the server do generic write
 955  * parameter checking and report problems.
 956  *
 957  * We eliminate local atime updates, see direct read above.
 958  *
 959  * We avoid unnecessary page cache invalidations for normal cached
 960  * readers of this file.
 961  *
 962  * Note that O_APPEND is not supported for NFS direct writes, as there
 963  * is no atomic O_APPEND write facility in the NFS protocol.
 964  */
 965 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 966                                 unsigned long nr_segs, loff_t pos, bool uio)
 967 {
 968         ssize_t retval = -EINVAL;
 969         struct file *file = iocb->ki_filp;
 970         struct address_space *mapping = file->f_mapping;
 971         size_t count;
 972
 973         count = iov_length(iov, nr_segs);
 974         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
 975
 976         dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
 977                 file->f_path.dentry->d_parent->d_name.name,
 978                 file->f_path.dentry->d_name.name,
 979                 count, (long long) pos);
 980
 981         retval = generic_write_checks(file, &pos, &count, 0);
 982         if (retval)
 983                 goto out;
 984
 985         retval = -EINVAL;
 986         if ((ssize_t) count < 0)
 987                 goto out;
 988         retval = 0;
 989         if (!count)
 990                 goto out;
 991
 992         retval = nfs_sync_mapping(mapping);
 993         if (retval)
 994                 goto out;
 995
 996         task_io_account_write(count);
 997
 998         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count, uio);
 999         if (retval > 0) {
1000                 struct inode *inode = mapping->host;
1001
1002                 iocb->ki_pos = pos + retval;
1003                 spin_lock(&inode->i_lock);
1004                 if (i_size_read(inode) < iocb->ki_pos)
1005                         i_size_write(inode, iocb->ki_pos);
1006                 spin_unlock(&inode->i_lock);
1007         }
1008 out:
1009         return retval;
1010 }
1011
1012 /**
1013  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1014  *
1015  */
1016 int __init nfs_init_directcache(void)
1017 {
1018         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1019                                                 sizeof(struct nfs_direct_req),
1020                                                 0, (SLAB_RECLAIM_ACCOUNT|
1021                                                         SLAB_MEM_SPREAD),
1022                                                 NULL);
1023         if (nfs_direct_cachep == NULL)
1024                 return -ENOMEM;
1025
1026         return 0;
1027 }
1028
1029 /**
1030  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1031  *
1032  */
1033 void nfs_destroy_directcache(void)
1034 {
1035         kmem_cache_destroy(nfs_direct_cachep);
1036 }