e1d415e97849a882052914509abaf59804d47b43
[linux-2.6.git] / 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
48 #include <linux/nfs_fs.h>
49 #include <linux/nfs_page.h>
50 #include <linux/sunrpc/clnt.h>
51
52 #include <asm/system.h>
53 #include <asm/uaccess.h>
54 #include <asm/atomic.h>
55
56 #include "internal.h"
57 #include "iostat.h"
58
59 #define NFSDBG_FACILITY         NFSDBG_VFS
60
61 static struct kmem_cache *nfs_direct_cachep;
62
63 /*
64  * This represents a set of asynchronous requests that we're waiting on
65  */
66 struct nfs_direct_req {
67         struct kref             kref;           /* release manager */
68
69         /* I/O parameters */
70         struct nfs_open_context *ctx;           /* file open context info */
71         struct kiocb *          iocb;           /* controlling i/o request */
72         struct inode *          inode;          /* target file of i/o */
73
74         /* completion state */
75         atomic_t                io_count;       /* i/os we're waiting for */
76         spinlock_t              lock;           /* protect completion state */
77         ssize_t                 count,          /* bytes actually processed */
78                                 error;          /* any reported error */
79         struct completion       completion;     /* wait for i/o completion */
80
81         /* commit state */
82         struct list_head        rewrite_list;   /* saved nfs_write_data structs */
83         struct nfs_write_data * commit_data;    /* special write_data for commits */
84         int                     flags;
85 #define NFS_ODIRECT_DO_COMMIT           (1)     /* an unstable reply was received */
86 #define NFS_ODIRECT_RESCHED_WRITES      (2)     /* write verification failed */
87         struct nfs_writeverf    verf;           /* unstable write verifier */
88 };
89
90 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
91 static const struct rpc_call_ops nfs_write_direct_ops;
92
93 static inline void get_dreq(struct nfs_direct_req *dreq)
94 {
95         atomic_inc(&dreq->io_count);
96 }
97
98 static inline int put_dreq(struct nfs_direct_req *dreq)
99 {
100         return atomic_dec_and_test(&dreq->io_count);
101 }
102
103 /**
104  * nfs_direct_IO - NFS address space operation for direct I/O
105  * @rw: direction (read or write)
106  * @iocb: target I/O control block
107  * @iov: array of vectors that define I/O buffer
108  * @pos: offset in file to begin the operation
109  * @nr_segs: size of iovec array
110  *
111  * The presence of this routine in the address space ops vector means
112  * the NFS client supports direct I/O.  However, we shunt off direct
113  * read and write requests before the VFS gets them, so this method
114  * should never be called.
115  */
116 ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
117 {
118         dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
119                         iocb->ki_filp->f_path.dentry->d_name.name,
120                         (long long) pos, nr_segs);
121
122         return -EINVAL;
123 }
124
125 static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
126 {
127         unsigned int npages;
128         unsigned int i;
129
130         if (count == 0)
131                 return;
132         pages += (pgbase >> PAGE_SHIFT);
133         npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
134         for (i = 0; i < npages; i++) {
135                 struct page *page = pages[i];
136                 if (!PageCompound(page))
137                         set_page_dirty(page);
138         }
139 }
140
141 static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
142 {
143         unsigned int i;
144         for (i = 0; i < npages; i++)
145                 page_cache_release(pages[i]);
146 }
147
148 static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
149 {
150         struct nfs_direct_req *dreq;
151
152         dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
153         if (!dreq)
154                 return NULL;
155
156         kref_init(&dreq->kref);
157         kref_get(&dreq->kref);
158         init_completion(&dreq->completion);
159         INIT_LIST_HEAD(&dreq->rewrite_list);
160         dreq->iocb = NULL;
161         dreq->ctx = NULL;
162         spin_lock_init(&dreq->lock);
163         atomic_set(&dreq->io_count, 0);
164         dreq->count = 0;
165         dreq->error = 0;
166         dreq->flags = 0;
167
168         return dreq;
169 }
170
171 static void nfs_direct_req_free(struct kref *kref)
172 {
173         struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
174
175         if (dreq->ctx != NULL)
176                 put_nfs_open_context(dreq->ctx);
177         kmem_cache_free(nfs_direct_cachep, dreq);
178 }
179
180 static void nfs_direct_req_release(struct nfs_direct_req *dreq)
181 {
182         kref_put(&dreq->kref, nfs_direct_req_free);
183 }
184
185 /*
186  * Collects and returns the final error value/byte-count.
187  */
188 static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
189 {
190         ssize_t result = -EIOCBQUEUED;
191
192         /* Async requests don't wait here */
193         if (dreq->iocb)
194                 goto out;
195
196         result = wait_for_completion_killable(&dreq->completion);
197
198         if (!result)
199                 result = dreq->error;
200         if (!result)
201                 result = dreq->count;
202
203 out:
204         return (ssize_t) result;
205 }
206
207 /*
208  * Synchronous I/O uses a stack-allocated iocb.  Thus we can't trust
209  * the iocb is still valid here if this is a synchronous request.
210  */
211 static void nfs_direct_complete(struct nfs_direct_req *dreq)
212 {
213         if (dreq->iocb) {
214                 long res = (long) dreq->error;
215                 if (!res)
216                         res = (long) dreq->count;
217                 aio_complete(dreq->iocb, res, 0);
218         }
219         complete_all(&dreq->completion);
220
221         nfs_direct_req_release(dreq);
222 }
223
224 /*
225  * We must hold a reference to all the pages in this direct read request
226  * until the RPCs complete.  This could be long *after* we are woken up in
227  * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
228  */
229 static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
230 {
231         struct nfs_read_data *data = calldata;
232
233         nfs_readpage_result(task, data);
234 }
235
236 static void nfs_direct_read_release(void *calldata)
237 {
238
239         struct nfs_read_data *data = calldata;
240         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
241         int status = data->task.tk_status;
242
243         spin_lock(&dreq->lock);
244         if (unlikely(status < 0)) {
245                 dreq->error = status;
246                 spin_unlock(&dreq->lock);
247         } else {
248                 dreq->count += data->res.count;
249                 spin_unlock(&dreq->lock);
250                 nfs_direct_dirty_pages(data->pagevec,
251                                 data->args.pgbase,
252                                 data->res.count);
253         }
254         nfs_direct_release_pages(data->pagevec, data->npages);
255
256         if (put_dreq(dreq))
257                 nfs_direct_complete(dreq);
258         nfs_readdata_free(data);
259 }
260
261 static const struct rpc_call_ops nfs_read_direct_ops = {
262 #if defined(CONFIG_NFS_V4_1)
263         .rpc_call_prepare = nfs_read_prepare,
264 #endif /* CONFIG_NFS_V4_1 */
265         .rpc_call_done = nfs_direct_read_result,
266         .rpc_release = nfs_direct_read_release,
267 };
268
269 /*
270  * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
271  * operation.  If nfs_readdata_alloc() or get_user_pages() fails,
272  * bail and stop sending more reads.  Read length accounting is
273  * handled automatically by nfs_direct_read_result().  Otherwise, if
274  * no requests have been sent, just return an error.
275  */
276 static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
277                                                 const struct iovec *iov,
278                                                 loff_t pos)
279 {
280         struct nfs_open_context *ctx = dreq->ctx;
281         struct inode *inode = ctx->path.dentry->d_inode;
282         unsigned long user_addr = (unsigned long)iov->iov_base;
283         size_t count = iov->iov_len;
284         size_t rsize = NFS_SERVER(inode)->rsize;
285         struct rpc_task *task;
286         struct rpc_message msg = {
287                 .rpc_cred = ctx->cred,
288         };
289         struct rpc_task_setup task_setup_data = {
290                 .rpc_client = NFS_CLIENT(inode),
291                 .rpc_message = &msg,
292                 .callback_ops = &nfs_read_direct_ops,
293                 .workqueue = nfsiod_workqueue,
294                 .flags = RPC_TASK_ASYNC,
295         };
296         unsigned int pgbase;
297         int result;
298         ssize_t started = 0;
299
300         do {
301                 struct nfs_read_data *data;
302                 size_t bytes;
303
304                 pgbase = user_addr & ~PAGE_MASK;
305                 bytes = min(rsize,count);
306
307                 result = -ENOMEM;
308                 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
309                 if (unlikely(!data))
310                         break;
311
312                 down_read(&current->mm->mmap_sem);
313                 result = get_user_pages(current, current->mm, user_addr,
314                                         data->npages, 1, 0, data->pagevec, NULL);
315                 up_read(&current->mm->mmap_sem);
316                 if (result < 0) {
317                         nfs_readdata_free(data);
318                         break;
319                 }
320                 if ((unsigned)result < data->npages) {
321                         bytes = result * PAGE_SIZE;
322                         if (bytes <= pgbase) {
323                                 nfs_direct_release_pages(data->pagevec, result);
324                                 nfs_readdata_free(data);
325                                 break;
326                         }
327                         bytes -= pgbase;
328                         data->npages = result;
329                 }
330
331                 get_dreq(dreq);
332
333                 data->req = (struct nfs_page *) dreq;
334                 data->inode = inode;
335                 data->cred = msg.rpc_cred;
336                 data->args.fh = NFS_FH(inode);
337                 data->args.context = ctx;
338                 data->args.offset = pos;
339                 data->args.pgbase = pgbase;
340                 data->args.pages = data->pagevec;
341                 data->args.count = bytes;
342                 data->res.fattr = &data->fattr;
343                 data->res.eof = 0;
344                 data->res.count = bytes;
345                 msg.rpc_argp = &data->args;
346                 msg.rpc_resp = &data->res;
347
348                 task_setup_data.task = &data->task;
349                 task_setup_data.callback_data = data;
350                 NFS_PROTO(inode)->read_setup(data, &msg);
351
352                 task = rpc_run_task(&task_setup_data);
353                 if (IS_ERR(task))
354                         break;
355                 rpc_put_task(task);
356
357                 dprintk("NFS: %5u initiated direct read call "
358                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
359                                 data->task.tk_pid,
360                                 inode->i_sb->s_id,
361                                 (long long)NFS_FILEID(inode),
362                                 bytes,
363                                 (unsigned long long)data->args.offset);
364
365                 started += bytes;
366                 user_addr += bytes;
367                 pos += bytes;
368                 /* FIXME: Remove this unnecessary math from final patch */
369                 pgbase += bytes;
370                 pgbase &= ~PAGE_MASK;
371                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
372
373                 count -= bytes;
374         } while (count != 0);
375
376         if (started)
377                 return started;
378         return result < 0 ? (ssize_t) result : -EFAULT;
379 }
380
381 static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
382                                               const struct iovec *iov,
383                                               unsigned long nr_segs,
384                                               loff_t pos)
385 {
386         ssize_t result = -EINVAL;
387         size_t requested_bytes = 0;
388         unsigned long seg;
389
390         get_dreq(dreq);
391
392         for (seg = 0; seg < nr_segs; seg++) {
393                 const struct iovec *vec = &iov[seg];
394                 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
395                 if (result < 0)
396                         break;
397                 requested_bytes += result;
398                 if ((size_t)result < vec->iov_len)
399                         break;
400                 pos += vec->iov_len;
401         }
402
403         if (put_dreq(dreq))
404                 nfs_direct_complete(dreq);
405
406         if (requested_bytes != 0)
407                 return 0;
408
409         if (result < 0)
410                 return result;
411         return -EIO;
412 }
413
414 static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
415                                unsigned long nr_segs, loff_t pos)
416 {
417         ssize_t result = 0;
418         struct inode *inode = iocb->ki_filp->f_mapping->host;
419         struct nfs_direct_req *dreq;
420
421         dreq = nfs_direct_req_alloc();
422         if (!dreq)
423                 return -ENOMEM;
424
425         dreq->inode = inode;
426         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
427         if (!is_sync_kiocb(iocb))
428                 dreq->iocb = iocb;
429
430         result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
431         if (!result)
432                 result = nfs_direct_wait(dreq);
433         nfs_direct_req_release(dreq);
434
435         return result;
436 }
437
438 static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
439 {
440         while (!list_empty(&dreq->rewrite_list)) {
441                 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
442                 list_del(&data->pages);
443                 nfs_direct_release_pages(data->pagevec, data->npages);
444                 nfs_writedata_free(data);
445         }
446 }
447
448 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
449 static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
450 {
451         struct inode *inode = dreq->inode;
452         struct list_head *p;
453         struct nfs_write_data *data;
454         struct rpc_task *task;
455         struct rpc_message msg = {
456                 .rpc_cred = dreq->ctx->cred,
457         };
458         struct rpc_task_setup task_setup_data = {
459                 .rpc_client = NFS_CLIENT(inode),
460                 .rpc_message = &msg,
461                 .callback_ops = &nfs_write_direct_ops,
462                 .workqueue = nfsiod_workqueue,
463                 .flags = RPC_TASK_ASYNC,
464         };
465
466         dreq->count = 0;
467         get_dreq(dreq);
468
469         list_for_each(p, &dreq->rewrite_list) {
470                 data = list_entry(p, struct nfs_write_data, pages);
471
472                 get_dreq(dreq);
473
474                 /* Use stable writes */
475                 data->args.stable = NFS_FILE_SYNC;
476
477                 /*
478                  * Reset data->res.
479                  */
480                 nfs_fattr_init(&data->fattr);
481                 data->res.count = data->args.count;
482                 memset(&data->verf, 0, sizeof(data->verf));
483
484                 /*
485                  * Reuse data->task; data->args should not have changed
486                  * since the original request was sent.
487                  */
488                 task_setup_data.task = &data->task;
489                 task_setup_data.callback_data = data;
490                 msg.rpc_argp = &data->args;
491                 msg.rpc_resp = &data->res;
492                 NFS_PROTO(inode)->write_setup(data, &msg);
493
494                 /*
495                  * We're called via an RPC callback, so BKL is already held.
496                  */
497                 task = rpc_run_task(&task_setup_data);
498                 if (!IS_ERR(task))
499                         rpc_put_task(task);
500
501                 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
502                                 data->task.tk_pid,
503                                 inode->i_sb->s_id,
504                                 (long long)NFS_FILEID(inode),
505                                 data->args.count,
506                                 (unsigned long long)data->args.offset);
507         }
508
509         if (put_dreq(dreq))
510                 nfs_direct_write_complete(dreq, inode);
511 }
512
513 static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
514 {
515         struct nfs_write_data *data = calldata;
516
517         /* Call the NFS version-specific code */
518         NFS_PROTO(data->inode)->commit_done(task, data);
519 }
520
521 static void nfs_direct_commit_release(void *calldata)
522 {
523         struct nfs_write_data *data = calldata;
524         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
525         int status = data->task.tk_status;
526
527         if (status < 0) {
528                 dprintk("NFS: %5u commit failed with error %d.\n",
529                                 data->task.tk_pid, status);
530                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
531         } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
532                 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
533                 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
534         }
535
536         dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
537         nfs_direct_write_complete(dreq, data->inode);
538         nfs_commit_free(data);
539 }
540
541 static const struct rpc_call_ops nfs_commit_direct_ops = {
542 #if defined(CONFIG_NFS_V4_1)
543         .rpc_call_prepare = nfs_write_prepare,
544 #endif /* CONFIG_NFS_V4_1 */
545         .rpc_call_done = nfs_direct_commit_result,
546         .rpc_release = nfs_direct_commit_release,
547 };
548
549 static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
550 {
551         struct nfs_write_data *data = dreq->commit_data;
552         struct rpc_task *task;
553         struct rpc_message msg = {
554                 .rpc_argp = &data->args,
555                 .rpc_resp = &data->res,
556                 .rpc_cred = dreq->ctx->cred,
557         };
558         struct rpc_task_setup task_setup_data = {
559                 .task = &data->task,
560                 .rpc_client = NFS_CLIENT(dreq->inode),
561                 .rpc_message = &msg,
562                 .callback_ops = &nfs_commit_direct_ops,
563                 .callback_data = data,
564                 .workqueue = nfsiod_workqueue,
565                 .flags = RPC_TASK_ASYNC,
566         };
567
568         data->inode = dreq->inode;
569         data->cred = msg.rpc_cred;
570
571         data->args.fh = NFS_FH(data->inode);
572         data->args.offset = 0;
573         data->args.count = 0;
574         data->args.context = dreq->ctx;
575         data->res.count = 0;
576         data->res.fattr = &data->fattr;
577         data->res.verf = &data->verf;
578
579         NFS_PROTO(data->inode)->commit_setup(data, &msg);
580
581         /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
582         dreq->commit_data = NULL;
583
584         dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
585
586         task = rpc_run_task(&task_setup_data);
587         if (!IS_ERR(task))
588                 rpc_put_task(task);
589 }
590
591 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
592 {
593         int flags = dreq->flags;
594
595         dreq->flags = 0;
596         switch (flags) {
597                 case NFS_ODIRECT_DO_COMMIT:
598                         nfs_direct_commit_schedule(dreq);
599                         break;
600                 case NFS_ODIRECT_RESCHED_WRITES:
601                         nfs_direct_write_reschedule(dreq);
602                         break;
603                 default:
604                         if (dreq->commit_data != NULL)
605                                 nfs_commit_free(dreq->commit_data);
606                         nfs_direct_free_writedata(dreq);
607                         nfs_zap_mapping(inode, inode->i_mapping);
608                         nfs_direct_complete(dreq);
609         }
610 }
611
612 static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
613 {
614         dreq->commit_data = nfs_commitdata_alloc();
615         if (dreq->commit_data != NULL)
616                 dreq->commit_data->req = (struct nfs_page *) dreq;
617 }
618 #else
619 static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
620 {
621         dreq->commit_data = NULL;
622 }
623
624 static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
625 {
626         nfs_direct_free_writedata(dreq);
627         nfs_zap_mapping(inode, inode->i_mapping);
628         nfs_direct_complete(dreq);
629 }
630 #endif
631
632 static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
633 {
634         struct nfs_write_data *data = calldata;
635
636         if (nfs_writeback_done(task, data) != 0)
637                 return;
638 }
639
640 /*
641  * NB: Return the value of the first error return code.  Subsequent
642  *     errors after the first one are ignored.
643  */
644 static void nfs_direct_write_release(void *calldata)
645 {
646         struct nfs_write_data *data = calldata;
647         struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
648         int status = data->task.tk_status;
649
650         spin_lock(&dreq->lock);
651
652         if (unlikely(status < 0)) {
653                 /* An error has occurred, so we should not commit */
654                 dreq->flags = 0;
655                 dreq->error = status;
656         }
657         if (unlikely(dreq->error != 0))
658                 goto out_unlock;
659
660         dreq->count += data->res.count;
661
662         if (data->res.verf->committed != NFS_FILE_SYNC) {
663                 switch (dreq->flags) {
664                         case 0:
665                                 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
666                                 dreq->flags = NFS_ODIRECT_DO_COMMIT;
667                                 break;
668                         case NFS_ODIRECT_DO_COMMIT:
669                                 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
670                                         dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
671                                         dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
672                                 }
673                 }
674         }
675 out_unlock:
676         spin_unlock(&dreq->lock);
677
678         if (put_dreq(dreq))
679                 nfs_direct_write_complete(dreq, data->inode);
680 }
681
682 static const struct rpc_call_ops nfs_write_direct_ops = {
683 #if defined(CONFIG_NFS_V4_1)
684         .rpc_call_prepare = nfs_write_prepare,
685 #endif /* CONFIG_NFS_V4_1 */
686         .rpc_call_done = nfs_direct_write_result,
687         .rpc_release = nfs_direct_write_release,
688 };
689
690 /*
691  * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
692  * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
693  * bail and stop sending more writes.  Write length accounting is
694  * handled automatically by nfs_direct_write_result().  Otherwise, if
695  * no requests have been sent, just return an error.
696  */
697 static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
698                                                  const struct iovec *iov,
699                                                  loff_t pos, int sync)
700 {
701         struct nfs_open_context *ctx = dreq->ctx;
702         struct inode *inode = ctx->path.dentry->d_inode;
703         unsigned long user_addr = (unsigned long)iov->iov_base;
704         size_t count = iov->iov_len;
705         struct rpc_task *task;
706         struct rpc_message msg = {
707                 .rpc_cred = ctx->cred,
708         };
709         struct rpc_task_setup task_setup_data = {
710                 .rpc_client = NFS_CLIENT(inode),
711                 .rpc_message = &msg,
712                 .callback_ops = &nfs_write_direct_ops,
713                 .workqueue = nfsiod_workqueue,
714                 .flags = RPC_TASK_ASYNC,
715         };
716         size_t wsize = NFS_SERVER(inode)->wsize;
717         unsigned int pgbase;
718         int result;
719         ssize_t started = 0;
720
721         do {
722                 struct nfs_write_data *data;
723                 size_t bytes;
724
725                 pgbase = user_addr & ~PAGE_MASK;
726                 bytes = min(wsize,count);
727
728                 result = -ENOMEM;
729                 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
730                 if (unlikely(!data))
731                         break;
732
733                 down_read(&current->mm->mmap_sem);
734                 result = get_user_pages(current, current->mm, user_addr,
735                                         data->npages, 0, 0, data->pagevec, NULL);
736                 up_read(&current->mm->mmap_sem);
737                 if (result < 0) {
738                         nfs_writedata_free(data);
739                         break;
740                 }
741                 if ((unsigned)result < data->npages) {
742                         bytes = result * PAGE_SIZE;
743                         if (bytes <= pgbase) {
744                                 nfs_direct_release_pages(data->pagevec, result);
745                                 nfs_writedata_free(data);
746                                 break;
747                         }
748                         bytes -= pgbase;
749                         data->npages = result;
750                 }
751
752                 get_dreq(dreq);
753
754                 list_move_tail(&data->pages, &dreq->rewrite_list);
755
756                 data->req = (struct nfs_page *) dreq;
757                 data->inode = inode;
758                 data->cred = msg.rpc_cred;
759                 data->args.fh = NFS_FH(inode);
760                 data->args.context = ctx;
761                 data->args.offset = pos;
762                 data->args.pgbase = pgbase;
763                 data->args.pages = data->pagevec;
764                 data->args.count = bytes;
765                 data->args.stable = sync;
766                 data->res.fattr = &data->fattr;
767                 data->res.count = bytes;
768                 data->res.verf = &data->verf;
769
770                 task_setup_data.task = &data->task;
771                 task_setup_data.callback_data = data;
772                 msg.rpc_argp = &data->args;
773                 msg.rpc_resp = &data->res;
774                 NFS_PROTO(inode)->write_setup(data, &msg);
775
776                 task = rpc_run_task(&task_setup_data);
777                 if (IS_ERR(task))
778                         break;
779                 rpc_put_task(task);
780
781                 dprintk("NFS: %5u initiated direct write call "
782                         "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
783                                 data->task.tk_pid,
784                                 inode->i_sb->s_id,
785                                 (long long)NFS_FILEID(inode),
786                                 bytes,
787                                 (unsigned long long)data->args.offset);
788
789                 started += bytes;
790                 user_addr += bytes;
791                 pos += bytes;
792
793                 /* FIXME: Remove this useless math from the final patch */
794                 pgbase += bytes;
795                 pgbase &= ~PAGE_MASK;
796                 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
797
798                 count -= bytes;
799         } while (count != 0);
800
801         if (started)
802                 return started;
803         return result < 0 ? (ssize_t) result : -EFAULT;
804 }
805
806 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
807                                                const struct iovec *iov,
808                                                unsigned long nr_segs,
809                                                loff_t pos, int sync)
810 {
811         ssize_t result = 0;
812         size_t requested_bytes = 0;
813         unsigned long seg;
814
815         get_dreq(dreq);
816
817         for (seg = 0; seg < nr_segs; seg++) {
818                 const struct iovec *vec = &iov[seg];
819                 result = nfs_direct_write_schedule_segment(dreq, vec,
820                                                            pos, sync);
821                 if (result < 0)
822                         break;
823                 requested_bytes += result;
824                 if ((size_t)result < vec->iov_len)
825                         break;
826                 pos += vec->iov_len;
827         }
828
829         if (put_dreq(dreq))
830                 nfs_direct_write_complete(dreq, dreq->inode);
831
832         if (requested_bytes != 0)
833                 return 0;
834
835         if (result < 0)
836                 return result;
837         return -EIO;
838 }
839
840 static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
841                                 unsigned long nr_segs, loff_t pos,
842                                 size_t count)
843 {
844         ssize_t result = 0;
845         struct inode *inode = iocb->ki_filp->f_mapping->host;
846         struct nfs_direct_req *dreq;
847         size_t wsize = NFS_SERVER(inode)->wsize;
848         int sync = NFS_UNSTABLE;
849
850         dreq = nfs_direct_req_alloc();
851         if (!dreq)
852                 return -ENOMEM;
853         nfs_alloc_commit_data(dreq);
854
855         if (dreq->commit_data == NULL || count < wsize)
856                 sync = NFS_FILE_SYNC;
857
858         dreq->inode = inode;
859         dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
860         if (!is_sync_kiocb(iocb))
861                 dreq->iocb = iocb;
862
863         result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
864         if (!result)
865                 result = nfs_direct_wait(dreq);
866         nfs_direct_req_release(dreq);
867
868         return result;
869 }
870
871 /**
872  * nfs_file_direct_read - file direct read operation for NFS files
873  * @iocb: target I/O control block
874  * @iov: vector of user buffers into which to read data
875  * @nr_segs: size of iov vector
876  * @pos: byte offset in file where reading starts
877  *
878  * We use this function for direct reads instead of calling
879  * generic_file_aio_read() in order to avoid gfar's check to see if
880  * the request starts before the end of the file.  For that check
881  * to work, we must generate a GETATTR before each direct read, and
882  * even then there is a window between the GETATTR and the subsequent
883  * READ where the file size could change.  Our preference is simply
884  * to do all reads the application wants, and the server will take
885  * care of managing the end of file boundary.
886  *
887  * This function also eliminates unnecessarily updating the file's
888  * atime locally, as the NFS server sets the file's atime, and this
889  * client must read the updated atime from the server back into its
890  * cache.
891  */
892 ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
893                                 unsigned long nr_segs, loff_t pos)
894 {
895         ssize_t retval = -EINVAL;
896         struct file *file = iocb->ki_filp;
897         struct address_space *mapping = file->f_mapping;
898         size_t count;
899
900         count = iov_length(iov, nr_segs);
901         nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
902
903         dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
904                 file->f_path.dentry->d_parent->d_name.name,
905                 file->f_path.dentry->d_name.name,
906                 count, (long long) pos);
907
908         retval = 0;
909         if (!count)
910                 goto out;
911
912         retval = nfs_sync_mapping(mapping);
913         if (retval)
914                 goto out;
915
916         retval = nfs_direct_read(iocb, iov, nr_segs, pos);
917         if (retval > 0)
918                 iocb->ki_pos = pos + retval;
919
920 out:
921         return retval;
922 }
923
924 /**
925  * nfs_file_direct_write - file direct write operation for NFS files
926  * @iocb: target I/O control block
927  * @iov: vector of user buffers from which to write data
928  * @nr_segs: size of iov vector
929  * @pos: byte offset in file where writing starts
930  *
931  * We use this function for direct writes instead of calling
932  * generic_file_aio_write() in order to avoid taking the inode
933  * semaphore and updating the i_size.  The NFS server will set
934  * the new i_size and this client must read the updated size
935  * back into its cache.  We let the server do generic write
936  * parameter checking and report problems.
937  *
938  * We eliminate local atime updates, see direct read above.
939  *
940  * We avoid unnecessary page cache invalidations for normal cached
941  * readers of this file.
942  *
943  * Note that O_APPEND is not supported for NFS direct writes, as there
944  * is no atomic O_APPEND write facility in the NFS protocol.
945  */
946 ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
947                                 unsigned long nr_segs, loff_t pos)
948 {
949         ssize_t retval = -EINVAL;
950         struct file *file = iocb->ki_filp;
951         struct address_space *mapping = file->f_mapping;
952         size_t count;
953
954         count = iov_length(iov, nr_segs);
955         nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
956
957         dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
958                 file->f_path.dentry->d_parent->d_name.name,
959                 file->f_path.dentry->d_name.name,
960                 count, (long long) pos);
961
962         retval = generic_write_checks(file, &pos, &count, 0);
963         if (retval)
964                 goto out;
965
966         retval = -EINVAL;
967         if ((ssize_t) count < 0)
968                 goto out;
969         retval = 0;
970         if (!count)
971                 goto out;
972
973         retval = nfs_sync_mapping(mapping);
974         if (retval)
975                 goto out;
976
977         retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
978
979         if (retval > 0)
980                 iocb->ki_pos = pos + retval;
981
982 out:
983         return retval;
984 }
985
986 /**
987  * nfs_init_directcache - create a slab cache for nfs_direct_req structures
988  *
989  */
990 int __init nfs_init_directcache(void)
991 {
992         nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
993                                                 sizeof(struct nfs_direct_req),
994                                                 0, (SLAB_RECLAIM_ACCOUNT|
995                                                         SLAB_MEM_SPREAD),
996                                                 NULL);
997         if (nfs_direct_cachep == NULL)
998                 return -ENOMEM;
999
1000         return 0;
1001 }
1002
1003 /**
1004  * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1005  *
1006  */
1007 void nfs_destroy_directcache(void)
1008 {
1009         kmem_cache_destroy(nfs_direct_cachep);
1010 }