Loading...
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
50#include <linux/nfs_fs.h>
51#include <linux/nfs_page.h>
52#include <linux/sunrpc/clnt.h>
53
54#include <asm/system.h>
55#include <asm/uaccess.h>
56#include <linux/atomic.h>
57
58#include "internal.h"
59#include "iostat.h"
60
61#define NFSDBG_FACILITY NFSDBG_VFS
62
63static struct kmem_cache *nfs_direct_cachep;
64
65/*
66 * This represents a set of asynchronous requests that we're waiting on
67 */
68struct nfs_direct_req {
69 struct kref kref; /* release manager */
70
71 /* I/O parameters */
72 struct nfs_open_context *ctx; /* file open context info */
73 struct nfs_lock_context *l_ctx; /* Lock context info */
74 struct kiocb * iocb; /* controlling i/o request */
75 struct inode * inode; /* target file of i/o */
76
77 /* completion state */
78 atomic_t io_count; /* i/os we're waiting for */
79 spinlock_t lock; /* protect completion state */
80 ssize_t count, /* bytes actually processed */
81 error; /* any reported error */
82 struct completion completion; /* wait for i/o completion */
83
84 /* commit state */
85 struct list_head rewrite_list; /* saved nfs_write_data structs */
86 struct nfs_write_data * commit_data; /* special write_data for commits */
87 int flags;
88#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
89#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
90 struct nfs_writeverf verf; /* unstable write verifier */
91};
92
93static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
94static const struct rpc_call_ops nfs_write_direct_ops;
95
96static inline void get_dreq(struct nfs_direct_req *dreq)
97{
98 atomic_inc(&dreq->io_count);
99}
100
101static inline int put_dreq(struct nfs_direct_req *dreq)
102{
103 return atomic_dec_and_test(&dreq->io_count);
104}
105
106/**
107 * nfs_direct_IO - NFS address space operation for direct I/O
108 * @rw: direction (read or write)
109 * @iocb: target I/O control block
110 * @iov: array of vectors that define I/O buffer
111 * @pos: offset in file to begin the operation
112 * @nr_segs: size of iovec array
113 *
114 * The presence of this routine in the address space ops vector means
115 * the NFS client supports direct I/O. However, we shunt off direct
116 * read and write requests before the VFS gets them, so this method
117 * should never be called.
118 */
119ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
120{
121 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
122 iocb->ki_filp->f_path.dentry->d_name.name,
123 (long long) pos, nr_segs);
124
125 return -EINVAL;
126}
127
128static void nfs_direct_dirty_pages(struct page **pages, unsigned int pgbase, size_t count)
129{
130 unsigned int npages;
131 unsigned int i;
132
133 if (count == 0)
134 return;
135 pages += (pgbase >> PAGE_SHIFT);
136 npages = (count + (pgbase & ~PAGE_MASK) + PAGE_SIZE - 1) >> PAGE_SHIFT;
137 for (i = 0; i < npages; i++) {
138 struct page *page = pages[i];
139 if (!PageCompound(page))
140 set_page_dirty(page);
141 }
142}
143
144static 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
151static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
152{
153 struct nfs_direct_req *dreq;
154
155 dreq = kmem_cache_alloc(nfs_direct_cachep, GFP_KERNEL);
156 if (!dreq)
157 return NULL;
158
159 kref_init(&dreq->kref);
160 kref_get(&dreq->kref);
161 init_completion(&dreq->completion);
162 INIT_LIST_HEAD(&dreq->rewrite_list);
163 dreq->iocb = NULL;
164 dreq->ctx = NULL;
165 dreq->l_ctx = NULL;
166 spin_lock_init(&dreq->lock);
167 atomic_set(&dreq->io_count, 0);
168 dreq->count = 0;
169 dreq->error = 0;
170 dreq->flags = 0;
171
172 return dreq;
173}
174
175static void nfs_direct_req_free(struct kref *kref)
176{
177 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
178
179 if (dreq->l_ctx != NULL)
180 nfs_put_lock_context(dreq->l_ctx);
181 if (dreq->ctx != NULL)
182 put_nfs_open_context(dreq->ctx);
183 kmem_cache_free(nfs_direct_cachep, dreq);
184}
185
186static void nfs_direct_req_release(struct nfs_direct_req *dreq)
187{
188 kref_put(&dreq->kref, nfs_direct_req_free);
189}
190
191/*
192 * Collects and returns the final error value/byte-count.
193 */
194static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
195{
196 ssize_t result = -EIOCBQUEUED;
197
198 /* Async requests don't wait here */
199 if (dreq->iocb)
200 goto out;
201
202 result = wait_for_completion_killable(&dreq->completion);
203
204 if (!result)
205 result = dreq->error;
206 if (!result)
207 result = dreq->count;
208
209out:
210 return (ssize_t) result;
211}
212
213/*
214 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
215 * the iocb is still valid here if this is a synchronous request.
216 */
217static void nfs_direct_complete(struct nfs_direct_req *dreq)
218{
219 if (dreq->iocb) {
220 long res = (long) dreq->error;
221 if (!res)
222 res = (long) dreq->count;
223 aio_complete(dreq->iocb, res, 0);
224 }
225 complete_all(&dreq->completion);
226
227 nfs_direct_req_release(dreq);
228}
229
230/*
231 * We must hold a reference to all the pages in this direct read request
232 * until the RPCs complete. This could be long *after* we are woken up in
233 * nfs_direct_wait (for instance, if someone hits ^C on a slow server).
234 */
235static void nfs_direct_read_result(struct rpc_task *task, void *calldata)
236{
237 struct nfs_read_data *data = calldata;
238
239 nfs_readpage_result(task, data);
240}
241
242static void nfs_direct_read_release(void *calldata)
243{
244
245 struct nfs_read_data *data = calldata;
246 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
247 int status = data->task.tk_status;
248
249 spin_lock(&dreq->lock);
250 if (unlikely(status < 0)) {
251 dreq->error = status;
252 spin_unlock(&dreq->lock);
253 } else {
254 dreq->count += data->res.count;
255 spin_unlock(&dreq->lock);
256 nfs_direct_dirty_pages(data->pagevec,
257 data->args.pgbase,
258 data->res.count);
259 }
260 nfs_direct_release_pages(data->pagevec, data->npages);
261
262 if (put_dreq(dreq))
263 nfs_direct_complete(dreq);
264 nfs_readdata_free(data);
265}
266
267static const struct rpc_call_ops nfs_read_direct_ops = {
268#if defined(CONFIG_NFS_V4_1)
269 .rpc_call_prepare = nfs_read_prepare,
270#endif /* CONFIG_NFS_V4_1 */
271 .rpc_call_done = nfs_direct_read_result,
272 .rpc_release = nfs_direct_read_release,
273};
274
275/*
276 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
277 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
278 * bail and stop sending more reads. Read length accounting is
279 * handled automatically by nfs_direct_read_result(). Otherwise, if
280 * no requests have been sent, just return an error.
281 */
282static ssize_t nfs_direct_read_schedule_segment(struct nfs_direct_req *dreq,
283 const struct iovec *iov,
284 loff_t pos)
285{
286 struct nfs_open_context *ctx = dreq->ctx;
287 struct inode *inode = ctx->dentry->d_inode;
288 unsigned long user_addr = (unsigned long)iov->iov_base;
289 size_t count = iov->iov_len;
290 size_t rsize = NFS_SERVER(inode)->rsize;
291 struct rpc_task *task;
292 struct rpc_message msg = {
293 .rpc_cred = ctx->cred,
294 };
295 struct rpc_task_setup task_setup_data = {
296 .rpc_client = NFS_CLIENT(inode),
297 .rpc_message = &msg,
298 .callback_ops = &nfs_read_direct_ops,
299 .workqueue = nfsiod_workqueue,
300 .flags = RPC_TASK_ASYNC,
301 };
302 unsigned int pgbase;
303 int result;
304 ssize_t started = 0;
305
306 do {
307 struct nfs_read_data *data;
308 size_t bytes;
309
310 pgbase = user_addr & ~PAGE_MASK;
311 bytes = min(rsize,count);
312
313 result = -ENOMEM;
314 data = nfs_readdata_alloc(nfs_page_array_len(pgbase, bytes));
315 if (unlikely(!data))
316 break;
317
318 down_read(¤t->mm->mmap_sem);
319 result = get_user_pages(current, current->mm, user_addr,
320 data->npages, 1, 0, data->pagevec, NULL);
321 up_read(¤t->mm->mmap_sem);
322 if (result < 0) {
323 nfs_readdata_free(data);
324 break;
325 }
326 if ((unsigned)result < data->npages) {
327 bytes = result * PAGE_SIZE;
328 if (bytes <= pgbase) {
329 nfs_direct_release_pages(data->pagevec, result);
330 nfs_readdata_free(data);
331 break;
332 }
333 bytes -= pgbase;
334 data->npages = result;
335 }
336
337 get_dreq(dreq);
338
339 data->req = (struct nfs_page *) dreq;
340 data->inode = inode;
341 data->cred = msg.rpc_cred;
342 data->args.fh = NFS_FH(inode);
343 data->args.context = ctx;
344 data->args.lock_context = dreq->l_ctx;
345 data->args.offset = pos;
346 data->args.pgbase = pgbase;
347 data->args.pages = data->pagevec;
348 data->args.count = bytes;
349 data->res.fattr = &data->fattr;
350 data->res.eof = 0;
351 data->res.count = bytes;
352 nfs_fattr_init(&data->fattr);
353 msg.rpc_argp = &data->args;
354 msg.rpc_resp = &data->res;
355
356 task_setup_data.task = &data->task;
357 task_setup_data.callback_data = data;
358 NFS_PROTO(inode)->read_setup(data, &msg);
359
360 task = rpc_run_task(&task_setup_data);
361 if (IS_ERR(task))
362 break;
363 rpc_put_task(task);
364
365 dprintk("NFS: %5u initiated direct read call "
366 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
367 data->task.tk_pid,
368 inode->i_sb->s_id,
369 (long long)NFS_FILEID(inode),
370 bytes,
371 (unsigned long long)data->args.offset);
372
373 started += bytes;
374 user_addr += bytes;
375 pos += bytes;
376 /* FIXME: Remove this unnecessary math from final patch */
377 pgbase += bytes;
378 pgbase &= ~PAGE_MASK;
379 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
380
381 count -= bytes;
382 } while (count != 0);
383
384 if (started)
385 return started;
386 return result < 0 ? (ssize_t) result : -EFAULT;
387}
388
389static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
390 const struct iovec *iov,
391 unsigned long nr_segs,
392 loff_t pos)
393{
394 ssize_t result = -EINVAL;
395 size_t requested_bytes = 0;
396 unsigned long seg;
397
398 get_dreq(dreq);
399
400 for (seg = 0; seg < nr_segs; seg++) {
401 const struct iovec *vec = &iov[seg];
402 result = nfs_direct_read_schedule_segment(dreq, vec, pos);
403 if (result < 0)
404 break;
405 requested_bytes += result;
406 if ((size_t)result < vec->iov_len)
407 break;
408 pos += vec->iov_len;
409 }
410
411 /*
412 * If no bytes were started, return the error, and let the
413 * generic layer handle the completion.
414 */
415 if (requested_bytes == 0) {
416 nfs_direct_req_release(dreq);
417 return result < 0 ? result : -EIO;
418 }
419
420 if (put_dreq(dreq))
421 nfs_direct_complete(dreq);
422 return 0;
423}
424
425static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
426 unsigned long nr_segs, loff_t pos)
427{
428 ssize_t result = -ENOMEM;
429 struct inode *inode = iocb->ki_filp->f_mapping->host;
430 struct nfs_direct_req *dreq;
431
432 dreq = nfs_direct_req_alloc();
433 if (dreq == NULL)
434 goto out;
435
436 dreq->inode = inode;
437 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
438 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
439 if (dreq->l_ctx == NULL)
440 goto out_release;
441 if (!is_sync_kiocb(iocb))
442 dreq->iocb = iocb;
443
444 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
445 if (!result)
446 result = nfs_direct_wait(dreq);
447out_release:
448 nfs_direct_req_release(dreq);
449out:
450 return result;
451}
452
453static void nfs_direct_free_writedata(struct nfs_direct_req *dreq)
454{
455 while (!list_empty(&dreq->rewrite_list)) {
456 struct nfs_write_data *data = list_entry(dreq->rewrite_list.next, struct nfs_write_data, pages);
457 list_del(&data->pages);
458 nfs_direct_release_pages(data->pagevec, data->npages);
459 nfs_writedata_free(data);
460 }
461}
462
463#if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
464static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
465{
466 struct inode *inode = dreq->inode;
467 struct list_head *p;
468 struct nfs_write_data *data;
469 struct rpc_task *task;
470 struct rpc_message msg = {
471 .rpc_cred = dreq->ctx->cred,
472 };
473 struct rpc_task_setup task_setup_data = {
474 .rpc_client = NFS_CLIENT(inode),
475 .rpc_message = &msg,
476 .callback_ops = &nfs_write_direct_ops,
477 .workqueue = nfsiod_workqueue,
478 .flags = RPC_TASK_ASYNC,
479 };
480
481 dreq->count = 0;
482 get_dreq(dreq);
483
484 list_for_each(p, &dreq->rewrite_list) {
485 data = list_entry(p, struct nfs_write_data, pages);
486
487 get_dreq(dreq);
488
489 /* Use stable writes */
490 data->args.stable = NFS_FILE_SYNC;
491
492 /*
493 * Reset data->res.
494 */
495 nfs_fattr_init(&data->fattr);
496 data->res.count = data->args.count;
497 memset(&data->verf, 0, sizeof(data->verf));
498
499 /*
500 * Reuse data->task; data->args should not have changed
501 * since the original request was sent.
502 */
503 task_setup_data.task = &data->task;
504 task_setup_data.callback_data = data;
505 msg.rpc_argp = &data->args;
506 msg.rpc_resp = &data->res;
507 NFS_PROTO(inode)->write_setup(data, &msg);
508
509 /*
510 * We're called via an RPC callback, so BKL is already held.
511 */
512 task = rpc_run_task(&task_setup_data);
513 if (!IS_ERR(task))
514 rpc_put_task(task);
515
516 dprintk("NFS: %5u rescheduled direct write call (req %s/%Ld, %u bytes @ offset %Lu)\n",
517 data->task.tk_pid,
518 inode->i_sb->s_id,
519 (long long)NFS_FILEID(inode),
520 data->args.count,
521 (unsigned long long)data->args.offset);
522 }
523
524 if (put_dreq(dreq))
525 nfs_direct_write_complete(dreq, inode);
526}
527
528static void nfs_direct_commit_result(struct rpc_task *task, void *calldata)
529{
530 struct nfs_write_data *data = calldata;
531
532 /* Call the NFS version-specific code */
533 NFS_PROTO(data->inode)->commit_done(task, data);
534}
535
536static void nfs_direct_commit_release(void *calldata)
537{
538 struct nfs_write_data *data = calldata;
539 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
540 int status = data->task.tk_status;
541
542 if (status < 0) {
543 dprintk("NFS: %5u commit failed with error %d.\n",
544 data->task.tk_pid, status);
545 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
546 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
547 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
548 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
549 }
550
551 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
552 nfs_direct_write_complete(dreq, data->inode);
553 nfs_commit_free(data);
554}
555
556static const struct rpc_call_ops nfs_commit_direct_ops = {
557#if defined(CONFIG_NFS_V4_1)
558 .rpc_call_prepare = nfs_write_prepare,
559#endif /* CONFIG_NFS_V4_1 */
560 .rpc_call_done = nfs_direct_commit_result,
561 .rpc_release = nfs_direct_commit_release,
562};
563
564static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
565{
566 struct nfs_write_data *data = dreq->commit_data;
567 struct rpc_task *task;
568 struct rpc_message msg = {
569 .rpc_argp = &data->args,
570 .rpc_resp = &data->res,
571 .rpc_cred = dreq->ctx->cred,
572 };
573 struct rpc_task_setup task_setup_data = {
574 .task = &data->task,
575 .rpc_client = NFS_CLIENT(dreq->inode),
576 .rpc_message = &msg,
577 .callback_ops = &nfs_commit_direct_ops,
578 .callback_data = data,
579 .workqueue = nfsiod_workqueue,
580 .flags = RPC_TASK_ASYNC,
581 };
582
583 data->inode = dreq->inode;
584 data->cred = msg.rpc_cred;
585
586 data->args.fh = NFS_FH(data->inode);
587 data->args.offset = 0;
588 data->args.count = 0;
589 data->args.context = dreq->ctx;
590 data->args.lock_context = dreq->l_ctx;
591 data->res.count = 0;
592 data->res.fattr = &data->fattr;
593 data->res.verf = &data->verf;
594 nfs_fattr_init(&data->fattr);
595
596 NFS_PROTO(data->inode)->commit_setup(data, &msg);
597
598 /* Note: task.tk_ops->rpc_release will free dreq->commit_data */
599 dreq->commit_data = NULL;
600
601 dprintk("NFS: %5u initiated commit call\n", data->task.tk_pid);
602
603 task = rpc_run_task(&task_setup_data);
604 if (!IS_ERR(task))
605 rpc_put_task(task);
606}
607
608static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
609{
610 int flags = dreq->flags;
611
612 dreq->flags = 0;
613 switch (flags) {
614 case NFS_ODIRECT_DO_COMMIT:
615 nfs_direct_commit_schedule(dreq);
616 break;
617 case NFS_ODIRECT_RESCHED_WRITES:
618 nfs_direct_write_reschedule(dreq);
619 break;
620 default:
621 if (dreq->commit_data != NULL)
622 nfs_commit_free(dreq->commit_data);
623 nfs_direct_free_writedata(dreq);
624 nfs_zap_mapping(inode, inode->i_mapping);
625 nfs_direct_complete(dreq);
626 }
627}
628
629static void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
630{
631 dreq->commit_data = nfs_commitdata_alloc();
632 if (dreq->commit_data != NULL)
633 dreq->commit_data->req = (struct nfs_page *) dreq;
634}
635#else
636static inline void nfs_alloc_commit_data(struct nfs_direct_req *dreq)
637{
638 dreq->commit_data = NULL;
639}
640
641static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
642{
643 nfs_direct_free_writedata(dreq);
644 nfs_zap_mapping(inode, inode->i_mapping);
645 nfs_direct_complete(dreq);
646}
647#endif
648
649static void nfs_direct_write_result(struct rpc_task *task, void *calldata)
650{
651 struct nfs_write_data *data = calldata;
652
653 nfs_writeback_done(task, data);
654}
655
656/*
657 * NB: Return the value of the first error return code. Subsequent
658 * errors after the first one are ignored.
659 */
660static void nfs_direct_write_release(void *calldata)
661{
662 struct nfs_write_data *data = calldata;
663 struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req;
664 int status = data->task.tk_status;
665
666 spin_lock(&dreq->lock);
667
668 if (unlikely(status < 0)) {
669 /* An error has occurred, so we should not commit */
670 dreq->flags = 0;
671 dreq->error = status;
672 }
673 if (unlikely(dreq->error != 0))
674 goto out_unlock;
675
676 dreq->count += data->res.count;
677
678 if (data->res.verf->committed != NFS_FILE_SYNC) {
679 switch (dreq->flags) {
680 case 0:
681 memcpy(&dreq->verf, &data->verf, sizeof(dreq->verf));
682 dreq->flags = NFS_ODIRECT_DO_COMMIT;
683 break;
684 case NFS_ODIRECT_DO_COMMIT:
685 if (memcmp(&dreq->verf, &data->verf, sizeof(dreq->verf))) {
686 dprintk("NFS: %5u write verify failed\n", data->task.tk_pid);
687 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
688 }
689 }
690 }
691out_unlock:
692 spin_unlock(&dreq->lock);
693
694 if (put_dreq(dreq))
695 nfs_direct_write_complete(dreq, data->inode);
696}
697
698static const struct rpc_call_ops nfs_write_direct_ops = {
699#if defined(CONFIG_NFS_V4_1)
700 .rpc_call_prepare = nfs_write_prepare,
701#endif /* CONFIG_NFS_V4_1 */
702 .rpc_call_done = nfs_direct_write_result,
703 .rpc_release = nfs_direct_write_release,
704};
705
706/*
707 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
708 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
709 * bail and stop sending more writes. Write length accounting is
710 * handled automatically by nfs_direct_write_result(). Otherwise, if
711 * no requests have been sent, just return an error.
712 */
713static ssize_t nfs_direct_write_schedule_segment(struct nfs_direct_req *dreq,
714 const struct iovec *iov,
715 loff_t pos, int sync)
716{
717 struct nfs_open_context *ctx = dreq->ctx;
718 struct inode *inode = ctx->dentry->d_inode;
719 unsigned long user_addr = (unsigned long)iov->iov_base;
720 size_t count = iov->iov_len;
721 struct rpc_task *task;
722 struct rpc_message msg = {
723 .rpc_cred = ctx->cred,
724 };
725 struct rpc_task_setup task_setup_data = {
726 .rpc_client = NFS_CLIENT(inode),
727 .rpc_message = &msg,
728 .callback_ops = &nfs_write_direct_ops,
729 .workqueue = nfsiod_workqueue,
730 .flags = RPC_TASK_ASYNC,
731 };
732 size_t wsize = NFS_SERVER(inode)->wsize;
733 unsigned int pgbase;
734 int result;
735 ssize_t started = 0;
736
737 do {
738 struct nfs_write_data *data;
739 size_t bytes;
740
741 pgbase = user_addr & ~PAGE_MASK;
742 bytes = min(wsize,count);
743
744 result = -ENOMEM;
745 data = nfs_writedata_alloc(nfs_page_array_len(pgbase, bytes));
746 if (unlikely(!data))
747 break;
748
749 down_read(¤t->mm->mmap_sem);
750 result = get_user_pages(current, current->mm, user_addr,
751 data->npages, 0, 0, data->pagevec, NULL);
752 up_read(¤t->mm->mmap_sem);
753 if (result < 0) {
754 nfs_writedata_free(data);
755 break;
756 }
757 if ((unsigned)result < data->npages) {
758 bytes = result * PAGE_SIZE;
759 if (bytes <= pgbase) {
760 nfs_direct_release_pages(data->pagevec, result);
761 nfs_writedata_free(data);
762 break;
763 }
764 bytes -= pgbase;
765 data->npages = result;
766 }
767
768 get_dreq(dreq);
769
770 list_move_tail(&data->pages, &dreq->rewrite_list);
771
772 data->req = (struct nfs_page *) dreq;
773 data->inode = inode;
774 data->cred = msg.rpc_cred;
775 data->args.fh = NFS_FH(inode);
776 data->args.context = ctx;
777 data->args.lock_context = dreq->l_ctx;
778 data->args.offset = pos;
779 data->args.pgbase = pgbase;
780 data->args.pages = data->pagevec;
781 data->args.count = bytes;
782 data->args.stable = sync;
783 data->res.fattr = &data->fattr;
784 data->res.count = bytes;
785 data->res.verf = &data->verf;
786 nfs_fattr_init(&data->fattr);
787
788 task_setup_data.task = &data->task;
789 task_setup_data.callback_data = data;
790 msg.rpc_argp = &data->args;
791 msg.rpc_resp = &data->res;
792 NFS_PROTO(inode)->write_setup(data, &msg);
793
794 task = rpc_run_task(&task_setup_data);
795 if (IS_ERR(task))
796 break;
797 rpc_put_task(task);
798
799 dprintk("NFS: %5u initiated direct write call "
800 "(req %s/%Ld, %zu bytes @ offset %Lu)\n",
801 data->task.tk_pid,
802 inode->i_sb->s_id,
803 (long long)NFS_FILEID(inode),
804 bytes,
805 (unsigned long long)data->args.offset);
806
807 started += bytes;
808 user_addr += bytes;
809 pos += bytes;
810
811 /* FIXME: Remove this useless math from the final patch */
812 pgbase += bytes;
813 pgbase &= ~PAGE_MASK;
814 BUG_ON(pgbase != (user_addr & ~PAGE_MASK));
815
816 count -= bytes;
817 } while (count != 0);
818
819 if (started)
820 return started;
821 return result < 0 ? (ssize_t) result : -EFAULT;
822}
823
824static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
825 const struct iovec *iov,
826 unsigned long nr_segs,
827 loff_t pos, int sync)
828{
829 ssize_t result = 0;
830 size_t requested_bytes = 0;
831 unsigned long seg;
832
833 get_dreq(dreq);
834
835 for (seg = 0; seg < nr_segs; seg++) {
836 const struct iovec *vec = &iov[seg];
837 result = nfs_direct_write_schedule_segment(dreq, vec,
838 pos, sync);
839 if (result < 0)
840 break;
841 requested_bytes += result;
842 if ((size_t)result < vec->iov_len)
843 break;
844 pos += vec->iov_len;
845 }
846
847 /*
848 * If no bytes were started, return the error, and let the
849 * generic layer handle the completion.
850 */
851 if (requested_bytes == 0) {
852 nfs_direct_req_release(dreq);
853 return result < 0 ? result : -EIO;
854 }
855
856 if (put_dreq(dreq))
857 nfs_direct_write_complete(dreq, dreq->inode);
858 return 0;
859}
860
861static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
862 unsigned long nr_segs, loff_t pos,
863 size_t count)
864{
865 ssize_t result = -ENOMEM;
866 struct inode *inode = iocb->ki_filp->f_mapping->host;
867 struct nfs_direct_req *dreq;
868 size_t wsize = NFS_SERVER(inode)->wsize;
869 int sync = NFS_UNSTABLE;
870
871 dreq = nfs_direct_req_alloc();
872 if (!dreq)
873 goto out;
874 nfs_alloc_commit_data(dreq);
875
876 if (dreq->commit_data == NULL || count <= wsize)
877 sync = NFS_FILE_SYNC;
878
879 dreq->inode = inode;
880 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
881 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
882 if (dreq->l_ctx == NULL)
883 goto out_release;
884 if (!is_sync_kiocb(iocb))
885 dreq->iocb = iocb;
886
887 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, sync);
888 if (!result)
889 result = nfs_direct_wait(dreq);
890out_release:
891 nfs_direct_req_release(dreq);
892out:
893 return result;
894}
895
896/**
897 * nfs_file_direct_read - file direct read operation for NFS files
898 * @iocb: target I/O control block
899 * @iov: vector of user buffers into which to read data
900 * @nr_segs: size of iov vector
901 * @pos: byte offset in file where reading starts
902 *
903 * We use this function for direct reads instead of calling
904 * generic_file_aio_read() in order to avoid gfar's check to see if
905 * the request starts before the end of the file. For that check
906 * to work, we must generate a GETATTR before each direct read, and
907 * even then there is a window between the GETATTR and the subsequent
908 * READ where the file size could change. Our preference is simply
909 * to do all reads the application wants, and the server will take
910 * care of managing the end of file boundary.
911 *
912 * This function also eliminates unnecessarily updating the file's
913 * atime locally, as the NFS server sets the file's atime, and this
914 * client must read the updated atime from the server back into its
915 * cache.
916 */
917ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
918 unsigned long nr_segs, loff_t pos)
919{
920 ssize_t retval = -EINVAL;
921 struct file *file = iocb->ki_filp;
922 struct address_space *mapping = file->f_mapping;
923 size_t count;
924
925 count = iov_length(iov, nr_segs);
926 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
927
928 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
929 file->f_path.dentry->d_parent->d_name.name,
930 file->f_path.dentry->d_name.name,
931 count, (long long) pos);
932
933 retval = 0;
934 if (!count)
935 goto out;
936
937 retval = nfs_sync_mapping(mapping);
938 if (retval)
939 goto out;
940
941 task_io_account_read(count);
942
943 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
944 if (retval > 0)
945 iocb->ki_pos = pos + retval;
946
947out:
948 return retval;
949}
950
951/**
952 * nfs_file_direct_write - file direct write operation for NFS files
953 * @iocb: target I/O control block
954 * @iov: vector of user buffers from which to write data
955 * @nr_segs: size of iov vector
956 * @pos: byte offset in file where writing starts
957 *
958 * We use this function for direct writes instead of calling
959 * generic_file_aio_write() in order to avoid taking the inode
960 * semaphore and updating the i_size. The NFS server will set
961 * the new i_size and this client must read the updated size
962 * back into its cache. We let the server do generic write
963 * parameter checking and report problems.
964 *
965 * We eliminate local atime updates, see direct read above.
966 *
967 * We avoid unnecessary page cache invalidations for normal cached
968 * readers of this file.
969 *
970 * Note that O_APPEND is not supported for NFS direct writes, as there
971 * is no atomic O_APPEND write facility in the NFS protocol.
972 */
973ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
974 unsigned long nr_segs, loff_t pos)
975{
976 ssize_t retval = -EINVAL;
977 struct file *file = iocb->ki_filp;
978 struct address_space *mapping = file->f_mapping;
979 size_t count;
980
981 count = iov_length(iov, nr_segs);
982 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
983
984 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
985 file->f_path.dentry->d_parent->d_name.name,
986 file->f_path.dentry->d_name.name,
987 count, (long long) pos);
988
989 retval = generic_write_checks(file, &pos, &count, 0);
990 if (retval)
991 goto out;
992
993 retval = -EINVAL;
994 if ((ssize_t) count < 0)
995 goto out;
996 retval = 0;
997 if (!count)
998 goto out;
999
1000 retval = nfs_sync_mapping(mapping);
1001 if (retval)
1002 goto out;
1003
1004 task_io_account_write(count);
1005
1006 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
1007
1008 if (retval > 0)
1009 iocb->ki_pos = pos + retval;
1010
1011out:
1012 return retval;
1013}
1014
1015/**
1016 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1017 *
1018 */
1019int __init nfs_init_directcache(void)
1020{
1021 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1022 sizeof(struct nfs_direct_req),
1023 0, (SLAB_RECLAIM_ACCOUNT|
1024 SLAB_MEM_SPREAD),
1025 NULL);
1026 if (nfs_direct_cachep == NULL)
1027 return -ENOMEM;
1028
1029 return 0;
1030}
1031
1032/**
1033 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1034 *
1035 */
1036void nfs_destroy_directcache(void)
1037{
1038 kmem_cache_destroy(nfs_direct_cachep);
1039}
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
64static struct kmem_cache *nfs_direct_cachep;
65
66/*
67 * This represents a set of asynchronous requests that we're waiting on
68 */
69struct 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
96static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
97static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
98static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
99static void nfs_direct_write_schedule_work(struct work_struct *work);
100
101static inline void get_dreq(struct nfs_direct_req *dreq)
102{
103 atomic_inc(&dreq->io_count);
104}
105
106static 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 */
124ssize_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 (%pD) off/no(%Ld/%lu) EINVAL\n",
128 iocb->ki_filp, (long long) pos, nr_segs);
129
130 return -EINVAL;
131#else
132 VM_BUG_ON(iocb->ki_nbytes != PAGE_SIZE);
133
134 if (rw == READ || rw == KERNEL_READ)
135 return nfs_file_direct_read(iocb, iov, nr_segs, pos,
136 rw == READ ? true : false);
137 return nfs_file_direct_write(iocb, iov, nr_segs, pos,
138 rw == WRITE ? true : false);
139#endif /* CONFIG_NFS_SWAP */
140}
141
142static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
143{
144 unsigned int i;
145 for (i = 0; i < npages; i++)
146 page_cache_release(pages[i]);
147}
148
149void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
150 struct nfs_direct_req *dreq)
151{
152 cinfo->lock = &dreq->lock;
153 cinfo->mds = &dreq->mds_cinfo;
154 cinfo->ds = &dreq->ds_cinfo;
155 cinfo->dreq = dreq;
156 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
157}
158
159static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
160{
161 struct nfs_direct_req *dreq;
162
163 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
164 if (!dreq)
165 return NULL;
166
167 kref_init(&dreq->kref);
168 kref_get(&dreq->kref);
169 init_completion(&dreq->completion);
170 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
171 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
172 spin_lock_init(&dreq->lock);
173
174 return dreq;
175}
176
177static void nfs_direct_req_free(struct kref *kref)
178{
179 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
180
181 if (dreq->l_ctx != NULL)
182 nfs_put_lock_context(dreq->l_ctx);
183 if (dreq->ctx != NULL)
184 put_nfs_open_context(dreq->ctx);
185 kmem_cache_free(nfs_direct_cachep, dreq);
186}
187
188static void nfs_direct_req_release(struct nfs_direct_req *dreq)
189{
190 kref_put(&dreq->kref, nfs_direct_req_free);
191}
192
193ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq)
194{
195 return dreq->bytes_left;
196}
197EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
198
199/*
200 * Collects and returns the final error value/byte-count.
201 */
202static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
203{
204 ssize_t result = -EIOCBQUEUED;
205
206 /* Async requests don't wait here */
207 if (dreq->iocb)
208 goto out;
209
210 result = wait_for_completion_killable(&dreq->completion);
211
212 if (!result)
213 result = dreq->error;
214 if (!result)
215 result = dreq->count;
216
217out:
218 return (ssize_t) result;
219}
220
221/*
222 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
223 * the iocb is still valid here if this is a synchronous request.
224 */
225static void nfs_direct_complete(struct nfs_direct_req *dreq, bool write)
226{
227 struct inode *inode = dreq->inode;
228
229 if (dreq->iocb && write) {
230 loff_t pos = dreq->iocb->ki_pos + dreq->count;
231
232 spin_lock(&inode->i_lock);
233 if (i_size_read(inode) < pos)
234 i_size_write(inode, pos);
235 spin_unlock(&inode->i_lock);
236 }
237
238 if (write)
239 nfs_zap_mapping(inode, inode->i_mapping);
240
241 inode_dio_done(inode);
242
243 if (dreq->iocb) {
244 long res = (long) dreq->error;
245 if (!res)
246 res = (long) dreq->count;
247 aio_complete(dreq->iocb, res, 0);
248 }
249
250 complete_all(&dreq->completion);
251
252 nfs_direct_req_release(dreq);
253}
254
255static void nfs_direct_readpage_release(struct nfs_page *req)
256{
257 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
258 req->wb_context->dentry->d_inode->i_sb->s_id,
259 (unsigned long long)NFS_FILEID(req->wb_context->dentry->d_inode),
260 req->wb_bytes,
261 (long long)req_offset(req));
262 nfs_release_request(req);
263}
264
265static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
266{
267 unsigned long bytes = 0;
268 struct nfs_direct_req *dreq = hdr->dreq;
269
270 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
271 goto out_put;
272
273 spin_lock(&dreq->lock);
274 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
275 dreq->error = hdr->error;
276 else
277 dreq->count += hdr->good_bytes;
278 spin_unlock(&dreq->lock);
279
280 while (!list_empty(&hdr->pages)) {
281 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
282 struct page *page = req->wb_page;
283
284 if (!PageCompound(page) && bytes < hdr->good_bytes)
285 set_page_dirty(page);
286 bytes += req->wb_bytes;
287 nfs_list_remove_request(req);
288 nfs_direct_readpage_release(req);
289 }
290out_put:
291 if (put_dreq(dreq))
292 nfs_direct_complete(dreq, false);
293 hdr->release(hdr);
294}
295
296static void nfs_read_sync_pgio_error(struct list_head *head)
297{
298 struct nfs_page *req;
299
300 while (!list_empty(head)) {
301 req = nfs_list_entry(head->next);
302 nfs_list_remove_request(req);
303 nfs_release_request(req);
304 }
305}
306
307static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
308{
309 get_dreq(hdr->dreq);
310}
311
312static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
313 .error_cleanup = nfs_read_sync_pgio_error,
314 .init_hdr = nfs_direct_pgio_init,
315 .completion = nfs_direct_read_completion,
316};
317
318/*
319 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
320 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
321 * bail and stop sending more reads. Read length accounting is
322 * handled automatically by nfs_direct_read_result(). Otherwise, if
323 * no requests have been sent, just return an error.
324 */
325static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
326 const struct iovec *iov,
327 loff_t pos, bool uio)
328{
329 struct nfs_direct_req *dreq = desc->pg_dreq;
330 struct nfs_open_context *ctx = dreq->ctx;
331 struct inode *inode = ctx->dentry->d_inode;
332 unsigned long user_addr = (unsigned long)iov->iov_base;
333 size_t count = iov->iov_len;
334 size_t rsize = NFS_SERVER(inode)->rsize;
335 unsigned int pgbase;
336 int result;
337 ssize_t started = 0;
338 struct page **pagevec = NULL;
339 unsigned int npages;
340
341 do {
342 size_t bytes;
343 int i;
344
345 pgbase = user_addr & ~PAGE_MASK;
346 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
347
348 result = -ENOMEM;
349 npages = nfs_page_array_len(pgbase, bytes);
350 if (!pagevec)
351 pagevec = kmalloc(npages * sizeof(struct page *),
352 GFP_KERNEL);
353 if (!pagevec)
354 break;
355 if (uio) {
356 down_read(¤t->mm->mmap_sem);
357 result = get_user_pages(current, current->mm, user_addr,
358 npages, 1, 0, pagevec, NULL);
359 up_read(¤t->mm->mmap_sem);
360 if (result < 0)
361 break;
362 } else {
363 WARN_ON(npages != 1);
364 result = get_kernel_page(user_addr, 1, pagevec);
365 if (WARN_ON(result != 1))
366 break;
367 }
368
369 if ((unsigned)result < npages) {
370 bytes = result * PAGE_SIZE;
371 if (bytes <= pgbase) {
372 nfs_direct_release_pages(pagevec, result);
373 break;
374 }
375 bytes -= pgbase;
376 npages = result;
377 }
378
379 for (i = 0; i < npages; i++) {
380 struct nfs_page *req;
381 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
382 /* XXX do we need to do the eof zeroing found in async_filler? */
383 req = nfs_create_request(dreq->ctx, dreq->inode,
384 pagevec[i],
385 pgbase, req_len);
386 if (IS_ERR(req)) {
387 result = PTR_ERR(req);
388 break;
389 }
390 req->wb_index = pos >> PAGE_SHIFT;
391 req->wb_offset = pos & ~PAGE_MASK;
392 if (!nfs_pageio_add_request(desc, req)) {
393 result = desc->pg_error;
394 nfs_release_request(req);
395 break;
396 }
397 pgbase = 0;
398 bytes -= req_len;
399 started += req_len;
400 user_addr += req_len;
401 pos += req_len;
402 count -= req_len;
403 dreq->bytes_left -= req_len;
404 }
405 /* The nfs_page now hold references to these pages */
406 nfs_direct_release_pages(pagevec, npages);
407 } while (count != 0 && result >= 0);
408
409 kfree(pagevec);
410
411 if (started)
412 return started;
413 return result < 0 ? (ssize_t) result : -EFAULT;
414}
415
416static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
417 const struct iovec *iov,
418 unsigned long nr_segs,
419 loff_t pos, bool uio)
420{
421 struct nfs_pageio_descriptor desc;
422 struct inode *inode = dreq->inode;
423 ssize_t result = -EINVAL;
424 size_t requested_bytes = 0;
425 unsigned long seg;
426
427 NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
428 &nfs_direct_read_completion_ops);
429 get_dreq(dreq);
430 desc.pg_dreq = dreq;
431 atomic_inc(&inode->i_dio_count);
432
433 for (seg = 0; seg < nr_segs; seg++) {
434 const struct iovec *vec = &iov[seg];
435 result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
436 if (result < 0)
437 break;
438 requested_bytes += result;
439 if ((size_t)result < vec->iov_len)
440 break;
441 pos += vec->iov_len;
442 }
443
444 nfs_pageio_complete(&desc);
445
446 /*
447 * If no bytes were started, return the error, and let the
448 * generic layer handle the completion.
449 */
450 if (requested_bytes == 0) {
451 inode_dio_done(inode);
452 nfs_direct_req_release(dreq);
453 return result < 0 ? result : -EIO;
454 }
455
456 if (put_dreq(dreq))
457 nfs_direct_complete(dreq, false);
458 return 0;
459}
460
461/**
462 * nfs_file_direct_read - file direct read operation for NFS files
463 * @iocb: target I/O control block
464 * @iov: vector of user buffers into which to read data
465 * @nr_segs: size of iov vector
466 * @pos: byte offset in file where reading starts
467 *
468 * We use this function for direct reads instead of calling
469 * generic_file_aio_read() in order to avoid gfar's check to see if
470 * the request starts before the end of the file. For that check
471 * to work, we must generate a GETATTR before each direct read, and
472 * even then there is a window between the GETATTR and the subsequent
473 * READ where the file size could change. Our preference is simply
474 * to do all reads the application wants, and the server will take
475 * care of managing the end of file boundary.
476 *
477 * This function also eliminates unnecessarily updating the file's
478 * atime locally, as the NFS server sets the file's atime, and this
479 * client must read the updated atime from the server back into its
480 * cache.
481 */
482ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
483 unsigned long nr_segs, loff_t pos, bool uio)
484{
485 struct file *file = iocb->ki_filp;
486 struct address_space *mapping = file->f_mapping;
487 struct inode *inode = mapping->host;
488 struct nfs_direct_req *dreq;
489 struct nfs_lock_context *l_ctx;
490 ssize_t result = -EINVAL;
491 size_t count;
492
493 count = iov_length(iov, nr_segs);
494 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
495
496 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
497 file, count, (long long) pos);
498
499 result = 0;
500 if (!count)
501 goto out;
502
503 mutex_lock(&inode->i_mutex);
504 result = nfs_sync_mapping(mapping);
505 if (result)
506 goto out_unlock;
507
508 task_io_account_read(count);
509
510 result = -ENOMEM;
511 dreq = nfs_direct_req_alloc();
512 if (dreq == NULL)
513 goto out_unlock;
514
515 dreq->inode = inode;
516 dreq->bytes_left = iov_length(iov, nr_segs);
517 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
518 l_ctx = nfs_get_lock_context(dreq->ctx);
519 if (IS_ERR(l_ctx)) {
520 result = PTR_ERR(l_ctx);
521 goto out_release;
522 }
523 dreq->l_ctx = l_ctx;
524 if (!is_sync_kiocb(iocb))
525 dreq->iocb = iocb;
526
527 NFS_I(inode)->read_io += iov_length(iov, nr_segs);
528 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos, uio);
529
530 mutex_unlock(&inode->i_mutex);
531
532 if (!result) {
533 result = nfs_direct_wait(dreq);
534 if (result > 0)
535 iocb->ki_pos = pos + result;
536 }
537
538 nfs_direct_req_release(dreq);
539 return result;
540
541out_release:
542 nfs_direct_req_release(dreq);
543out_unlock:
544 mutex_unlock(&inode->i_mutex);
545out:
546 return result;
547}
548
549#if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
550static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
551{
552 struct nfs_pageio_descriptor desc;
553 struct nfs_page *req, *tmp;
554 LIST_HEAD(reqs);
555 struct nfs_commit_info cinfo;
556 LIST_HEAD(failed);
557
558 nfs_init_cinfo_from_dreq(&cinfo, dreq);
559 pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
560 spin_lock(cinfo.lock);
561 nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
562 spin_unlock(cinfo.lock);
563
564 dreq->count = 0;
565 get_dreq(dreq);
566
567 NFS_PROTO(dreq->inode)->write_pageio_init(&desc, dreq->inode, FLUSH_STABLE,
568 &nfs_direct_write_completion_ops);
569 desc.pg_dreq = dreq;
570
571 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
572 if (!nfs_pageio_add_request(&desc, req)) {
573 nfs_list_remove_request(req);
574 nfs_list_add_request(req, &failed);
575 spin_lock(cinfo.lock);
576 dreq->flags = 0;
577 dreq->error = -EIO;
578 spin_unlock(cinfo.lock);
579 }
580 nfs_release_request(req);
581 }
582 nfs_pageio_complete(&desc);
583
584 while (!list_empty(&failed)) {
585 req = nfs_list_entry(failed.next);
586 nfs_list_remove_request(req);
587 nfs_unlock_and_release_request(req);
588 }
589
590 if (put_dreq(dreq))
591 nfs_direct_write_complete(dreq, dreq->inode);
592}
593
594static void nfs_direct_commit_complete(struct nfs_commit_data *data)
595{
596 struct nfs_direct_req *dreq = data->dreq;
597 struct nfs_commit_info cinfo;
598 struct nfs_page *req;
599 int status = data->task.tk_status;
600
601 nfs_init_cinfo_from_dreq(&cinfo, dreq);
602 if (status < 0) {
603 dprintk("NFS: %5u commit failed with error %d.\n",
604 data->task.tk_pid, status);
605 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
606 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
607 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
608 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
609 }
610
611 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
612 while (!list_empty(&data->pages)) {
613 req = nfs_list_entry(data->pages.next);
614 nfs_list_remove_request(req);
615 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
616 /* Note the rewrite will go through mds */
617 nfs_mark_request_commit(req, NULL, &cinfo);
618 } else
619 nfs_release_request(req);
620 nfs_unlock_and_release_request(req);
621 }
622
623 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
624 nfs_direct_write_complete(dreq, data->inode);
625}
626
627static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
628{
629 /* There is no lock to clear */
630}
631
632static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
633 .completion = nfs_direct_commit_complete,
634 .error_cleanup = nfs_direct_error_cleanup,
635};
636
637static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
638{
639 int res;
640 struct nfs_commit_info cinfo;
641 LIST_HEAD(mds_list);
642
643 nfs_init_cinfo_from_dreq(&cinfo, dreq);
644 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
645 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
646 if (res < 0) /* res == -ENOMEM */
647 nfs_direct_write_reschedule(dreq);
648}
649
650static void nfs_direct_write_schedule_work(struct work_struct *work)
651{
652 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
653 int flags = dreq->flags;
654
655 dreq->flags = 0;
656 switch (flags) {
657 case NFS_ODIRECT_DO_COMMIT:
658 nfs_direct_commit_schedule(dreq);
659 break;
660 case NFS_ODIRECT_RESCHED_WRITES:
661 nfs_direct_write_reschedule(dreq);
662 break;
663 default:
664 nfs_direct_complete(dreq, true);
665 }
666}
667
668static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
669{
670 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
671}
672
673#else
674static void nfs_direct_write_schedule_work(struct work_struct *work)
675{
676}
677
678static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
679{
680 nfs_direct_complete(dreq, true);
681}
682#endif
683
684/*
685 * NB: Return the value of the first error return code. Subsequent
686 * errors after the first one are ignored.
687 */
688/*
689 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
690 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
691 * bail and stop sending more writes. Write length accounting is
692 * handled automatically by nfs_direct_write_result(). Otherwise, if
693 * no requests have been sent, just return an error.
694 */
695static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
696 const struct iovec *iov,
697 loff_t pos, bool uio)
698{
699 struct nfs_direct_req *dreq = desc->pg_dreq;
700 struct nfs_open_context *ctx = dreq->ctx;
701 struct inode *inode = ctx->dentry->d_inode;
702 unsigned long user_addr = (unsigned long)iov->iov_base;
703 size_t count = iov->iov_len;
704 size_t wsize = NFS_SERVER(inode)->wsize;
705 unsigned int pgbase;
706 int result;
707 ssize_t started = 0;
708 struct page **pagevec = NULL;
709 unsigned int npages;
710
711 do {
712 size_t bytes;
713 int i;
714
715 pgbase = user_addr & ~PAGE_MASK;
716 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
717
718 result = -ENOMEM;
719 npages = nfs_page_array_len(pgbase, bytes);
720 if (!pagevec)
721 pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
722 if (!pagevec)
723 break;
724
725 if (uio) {
726 down_read(¤t->mm->mmap_sem);
727 result = get_user_pages(current, current->mm, user_addr,
728 npages, 0, 0, pagevec, NULL);
729 up_read(¤t->mm->mmap_sem);
730 if (result < 0)
731 break;
732 } else {
733 WARN_ON(npages != 1);
734 result = get_kernel_page(user_addr, 0, pagevec);
735 if (WARN_ON(result != 1))
736 break;
737 }
738
739 if ((unsigned)result < npages) {
740 bytes = result * PAGE_SIZE;
741 if (bytes <= pgbase) {
742 nfs_direct_release_pages(pagevec, result);
743 break;
744 }
745 bytes -= pgbase;
746 npages = result;
747 }
748
749 for (i = 0; i < npages; i++) {
750 struct nfs_page *req;
751 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
752
753 req = nfs_create_request(dreq->ctx, dreq->inode,
754 pagevec[i],
755 pgbase, req_len);
756 if (IS_ERR(req)) {
757 result = PTR_ERR(req);
758 break;
759 }
760 nfs_lock_request(req);
761 req->wb_index = pos >> PAGE_SHIFT;
762 req->wb_offset = pos & ~PAGE_MASK;
763 if (!nfs_pageio_add_request(desc, req)) {
764 result = desc->pg_error;
765 nfs_unlock_and_release_request(req);
766 break;
767 }
768 pgbase = 0;
769 bytes -= req_len;
770 started += req_len;
771 user_addr += req_len;
772 pos += req_len;
773 count -= req_len;
774 dreq->bytes_left -= req_len;
775 }
776 /* The nfs_page now hold references to these pages */
777 nfs_direct_release_pages(pagevec, npages);
778 } while (count != 0 && result >= 0);
779
780 kfree(pagevec);
781
782 if (started)
783 return started;
784 return result < 0 ? (ssize_t) result : -EFAULT;
785}
786
787static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
788{
789 struct nfs_direct_req *dreq = hdr->dreq;
790 struct nfs_commit_info cinfo;
791 int bit = -1;
792 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
793
794 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
795 goto out_put;
796
797 nfs_init_cinfo_from_dreq(&cinfo, dreq);
798
799 spin_lock(&dreq->lock);
800
801 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
802 dreq->flags = 0;
803 dreq->error = hdr->error;
804 }
805 if (dreq->error != 0)
806 bit = NFS_IOHDR_ERROR;
807 else {
808 dreq->count += hdr->good_bytes;
809 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
810 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
811 bit = NFS_IOHDR_NEED_RESCHED;
812 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
813 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
814 bit = NFS_IOHDR_NEED_RESCHED;
815 else if (dreq->flags == 0) {
816 memcpy(&dreq->verf, hdr->verf,
817 sizeof(dreq->verf));
818 bit = NFS_IOHDR_NEED_COMMIT;
819 dreq->flags = NFS_ODIRECT_DO_COMMIT;
820 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
821 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
822 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
823 bit = NFS_IOHDR_NEED_RESCHED;
824 } else
825 bit = NFS_IOHDR_NEED_COMMIT;
826 }
827 }
828 }
829 spin_unlock(&dreq->lock);
830
831 while (!list_empty(&hdr->pages)) {
832 req = nfs_list_entry(hdr->pages.next);
833 nfs_list_remove_request(req);
834 switch (bit) {
835 case NFS_IOHDR_NEED_RESCHED:
836 case NFS_IOHDR_NEED_COMMIT:
837 kref_get(&req->wb_kref);
838 nfs_mark_request_commit(req, hdr->lseg, &cinfo);
839 }
840 nfs_unlock_and_release_request(req);
841 }
842
843out_put:
844 if (put_dreq(dreq))
845 nfs_direct_write_complete(dreq, hdr->inode);
846 hdr->release(hdr);
847}
848
849static void nfs_write_sync_pgio_error(struct list_head *head)
850{
851 struct nfs_page *req;
852
853 while (!list_empty(head)) {
854 req = nfs_list_entry(head->next);
855 nfs_list_remove_request(req);
856 nfs_unlock_and_release_request(req);
857 }
858}
859
860static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
861 .error_cleanup = nfs_write_sync_pgio_error,
862 .init_hdr = nfs_direct_pgio_init,
863 .completion = nfs_direct_write_completion,
864};
865
866static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
867 const struct iovec *iov,
868 unsigned long nr_segs,
869 loff_t pos, bool uio)
870{
871 struct nfs_pageio_descriptor desc;
872 struct inode *inode = dreq->inode;
873 ssize_t result = 0;
874 size_t requested_bytes = 0;
875 unsigned long seg;
876
877 NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
878 &nfs_direct_write_completion_ops);
879 desc.pg_dreq = dreq;
880 get_dreq(dreq);
881 atomic_inc(&inode->i_dio_count);
882
883 NFS_I(dreq->inode)->write_io += iov_length(iov, nr_segs);
884 for (seg = 0; seg < nr_segs; seg++) {
885 const struct iovec *vec = &iov[seg];
886 result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
887 if (result < 0)
888 break;
889 requested_bytes += result;
890 if ((size_t)result < vec->iov_len)
891 break;
892 pos += vec->iov_len;
893 }
894 nfs_pageio_complete(&desc);
895
896 /*
897 * If no bytes were started, return the error, and let the
898 * generic layer handle the completion.
899 */
900 if (requested_bytes == 0) {
901 inode_dio_done(inode);
902 nfs_direct_req_release(dreq);
903 return result < 0 ? result : -EIO;
904 }
905
906 if (put_dreq(dreq))
907 nfs_direct_write_complete(dreq, dreq->inode);
908 return 0;
909}
910
911/**
912 * nfs_file_direct_write - file direct write operation for NFS files
913 * @iocb: target I/O control block
914 * @iov: vector of user buffers from which to write data
915 * @nr_segs: size of iov vector
916 * @pos: byte offset in file where writing starts
917 *
918 * We use this function for direct writes instead of calling
919 * generic_file_aio_write() in order to avoid taking the inode
920 * semaphore and updating the i_size. The NFS server will set
921 * the new i_size and this client must read the updated size
922 * back into its cache. We let the server do generic write
923 * parameter checking and report problems.
924 *
925 * We eliminate local atime updates, see direct read above.
926 *
927 * We avoid unnecessary page cache invalidations for normal cached
928 * readers of this file.
929 *
930 * Note that O_APPEND is not supported for NFS direct writes, as there
931 * is no atomic O_APPEND write facility in the NFS protocol.
932 */
933ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
934 unsigned long nr_segs, loff_t pos, bool uio)
935{
936 ssize_t result = -EINVAL;
937 struct file *file = iocb->ki_filp;
938 struct address_space *mapping = file->f_mapping;
939 struct inode *inode = mapping->host;
940 struct nfs_direct_req *dreq;
941 struct nfs_lock_context *l_ctx;
942 loff_t end;
943 size_t count;
944
945 count = iov_length(iov, nr_segs);
946 end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
947
948 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
949
950 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
951 file, count, (long long) pos);
952
953 result = generic_write_checks(file, &pos, &count, 0);
954 if (result)
955 goto out;
956
957 result = -EINVAL;
958 if ((ssize_t) count < 0)
959 goto out;
960 result = 0;
961 if (!count)
962 goto out;
963
964 mutex_lock(&inode->i_mutex);
965
966 result = nfs_sync_mapping(mapping);
967 if (result)
968 goto out_unlock;
969
970 if (mapping->nrpages) {
971 result = invalidate_inode_pages2_range(mapping,
972 pos >> PAGE_CACHE_SHIFT, end);
973 if (result)
974 goto out_unlock;
975 }
976
977 task_io_account_write(count);
978
979 result = -ENOMEM;
980 dreq = nfs_direct_req_alloc();
981 if (!dreq)
982 goto out_unlock;
983
984 dreq->inode = inode;
985 dreq->bytes_left = count;
986 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
987 l_ctx = nfs_get_lock_context(dreq->ctx);
988 if (IS_ERR(l_ctx)) {
989 result = PTR_ERR(l_ctx);
990 goto out_release;
991 }
992 dreq->l_ctx = l_ctx;
993 if (!is_sync_kiocb(iocb))
994 dreq->iocb = iocb;
995
996 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos, uio);
997
998 if (mapping->nrpages) {
999 invalidate_inode_pages2_range(mapping,
1000 pos >> PAGE_CACHE_SHIFT, end);
1001 }
1002
1003 mutex_unlock(&inode->i_mutex);
1004
1005 if (!result) {
1006 result = nfs_direct_wait(dreq);
1007 if (result > 0) {
1008 struct inode *inode = mapping->host;
1009
1010 iocb->ki_pos = pos + result;
1011 spin_lock(&inode->i_lock);
1012 if (i_size_read(inode) < iocb->ki_pos)
1013 i_size_write(inode, iocb->ki_pos);
1014 spin_unlock(&inode->i_lock);
1015 }
1016 }
1017 nfs_direct_req_release(dreq);
1018 return result;
1019
1020out_release:
1021 nfs_direct_req_release(dreq);
1022out_unlock:
1023 mutex_unlock(&inode->i_mutex);
1024out:
1025 return result;
1026}
1027
1028/**
1029 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1030 *
1031 */
1032int __init nfs_init_directcache(void)
1033{
1034 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1035 sizeof(struct nfs_direct_req),
1036 0, (SLAB_RECLAIM_ACCOUNT|
1037 SLAB_MEM_SPREAD),
1038 NULL);
1039 if (nfs_direct_cachep == NULL)
1040 return -ENOMEM;
1041
1042 return 0;
1043}
1044
1045/**
1046 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1047 *
1048 */
1049void nfs_destroy_directcache(void)
1050{
1051 kmem_cache_destroy(nfs_direct_cachep);
1052}