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