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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/nfs/direct.c
4 *
5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
6 *
7 * High-performance uncached I/O for the Linux NFS client
8 *
9 * There are important applications whose performance or correctness
10 * depends on uncached access to file data. Database clusters
11 * (multiple copies of the same instance running on separate hosts)
12 * implement their own cache coherency protocol that subsumes file
13 * system cache protocols. Applications that process datasets
14 * considerably larger than the client's memory do not always benefit
15 * from a local cache. A streaming video server, for instance, has no
16 * need to cache the contents of a file.
17 *
18 * When an application requests uncached I/O, all read and write requests
19 * are made directly to the server; data stored or fetched via these
20 * requests is not cached in the Linux page cache. The client does not
21 * correct unaligned requests from applications. All requested bytes are
22 * held on permanent storage before a direct write system call returns to
23 * an application.
24 *
25 * Solaris implements an uncached I/O facility called directio() that
26 * is used for backups and sequential I/O to very large files. Solaris
27 * also supports uncaching whole NFS partitions with "-o forcedirectio,"
28 * an undocumented mount option.
29 *
30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
31 * help from Andrew Morton.
32 *
33 * 18 Dec 2001 Initial implementation for 2.4 --cel
34 * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy
35 * 08 Jun 2003 Port to 2.5 APIs --cel
36 * 31 Mar 2004 Handle direct I/O without VFS support --cel
37 * 15 Sep 2004 Parallel async reads --cel
38 * 04 May 2005 support O_DIRECT with aio --cel
39 *
40 */
41
42#include <linux/errno.h>
43#include <linux/sched.h>
44#include <linux/kernel.h>
45#include <linux/file.h>
46#include <linux/pagemap.h>
47#include <linux/kref.h>
48#include <linux/slab.h>
49#include <linux/task_io_accounting_ops.h>
50#include <linux/module.h>
51
52#include <linux/nfs_fs.h>
53#include <linux/nfs_page.h>
54#include <linux/sunrpc/clnt.h>
55
56#include <linux/uaccess.h>
57#include <linux/atomic.h>
58
59#include "delegation.h"
60#include "internal.h"
61#include "iostat.h"
62#include "pnfs.h"
63#include "fscache.h"
64#include "nfstrace.h"
65
66#define NFSDBG_FACILITY NFSDBG_VFS
67
68static struct kmem_cache *nfs_direct_cachep;
69
70static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
71static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
72static void nfs_direct_write_complete(struct nfs_direct_req *dreq);
73static void nfs_direct_write_schedule_work(struct work_struct *work);
74
75static inline void get_dreq(struct nfs_direct_req *dreq)
76{
77 atomic_inc(&dreq->io_count);
78}
79
80static inline int put_dreq(struct nfs_direct_req *dreq)
81{
82 return atomic_dec_and_test(&dreq->io_count);
83}
84
85static void
86nfs_direct_handle_truncated(struct nfs_direct_req *dreq,
87 const struct nfs_pgio_header *hdr,
88 ssize_t dreq_len)
89{
90 if (!(test_bit(NFS_IOHDR_ERROR, &hdr->flags) ||
91 test_bit(NFS_IOHDR_EOF, &hdr->flags)))
92 return;
93 if (dreq->max_count >= dreq_len) {
94 dreq->max_count = dreq_len;
95 if (dreq->count > dreq_len)
96 dreq->count = dreq_len;
97 }
98
99 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && !dreq->error)
100 dreq->error = hdr->error;
101}
102
103static void
104nfs_direct_count_bytes(struct nfs_direct_req *dreq,
105 const struct nfs_pgio_header *hdr)
106{
107 loff_t hdr_end = hdr->io_start + hdr->good_bytes;
108 ssize_t dreq_len = 0;
109
110 if (hdr_end > dreq->io_start)
111 dreq_len = hdr_end - dreq->io_start;
112
113 nfs_direct_handle_truncated(dreq, hdr, dreq_len);
114
115 if (dreq_len > dreq->max_count)
116 dreq_len = dreq->max_count;
117
118 if (dreq->count < dreq_len)
119 dreq->count = dreq_len;
120}
121
122static void nfs_direct_truncate_request(struct nfs_direct_req *dreq,
123 struct nfs_page *req)
124{
125 loff_t offs = req_offset(req);
126 size_t req_start = (size_t)(offs - dreq->io_start);
127
128 if (req_start < dreq->max_count)
129 dreq->max_count = req_start;
130 if (req_start < dreq->count)
131 dreq->count = req_start;
132}
133
134static void nfs_direct_file_adjust_size_locked(struct inode *inode,
135 loff_t offset, size_t count)
136{
137 loff_t newsize = offset + (loff_t)count;
138 loff_t oldsize = i_size_read(inode);
139
140 if (newsize > oldsize) {
141 i_size_write(inode, newsize);
142 NFS_I(inode)->cache_validity &= ~NFS_INO_INVALID_SIZE;
143 trace_nfs_size_grow(inode, newsize);
144 nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
145 }
146}
147
148/**
149 * nfs_swap_rw - NFS address space operation for swap I/O
150 * @iocb: target I/O control block
151 * @iter: I/O buffer
152 *
153 * Perform IO to the swap-file. This is much like direct IO.
154 */
155int nfs_swap_rw(struct kiocb *iocb, struct iov_iter *iter)
156{
157 ssize_t ret;
158
159 if (iov_iter_rw(iter) == READ)
160 ret = nfs_file_direct_read(iocb, iter, true);
161 else
162 ret = nfs_file_direct_write(iocb, iter, true);
163 if (ret < 0)
164 return ret;
165 return 0;
166}
167
168static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
169{
170 unsigned int i;
171 for (i = 0; i < npages; i++)
172 put_page(pages[i]);
173}
174
175void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
176 struct nfs_direct_req *dreq)
177{
178 cinfo->inode = dreq->inode;
179 cinfo->mds = &dreq->mds_cinfo;
180 cinfo->ds = &dreq->ds_cinfo;
181 cinfo->dreq = dreq;
182 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
183}
184
185static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
186{
187 struct nfs_direct_req *dreq;
188
189 dreq = kmem_cache_zalloc(nfs_direct_cachep, GFP_KERNEL);
190 if (!dreq)
191 return NULL;
192
193 kref_init(&dreq->kref);
194 kref_get(&dreq->kref);
195 init_completion(&dreq->completion);
196 INIT_LIST_HEAD(&dreq->mds_cinfo.list);
197 pnfs_init_ds_commit_info(&dreq->ds_cinfo);
198 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
199 spin_lock_init(&dreq->lock);
200
201 return dreq;
202}
203
204static void nfs_direct_req_free(struct kref *kref)
205{
206 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
207
208 pnfs_release_ds_info(&dreq->ds_cinfo, dreq->inode);
209 if (dreq->l_ctx != NULL)
210 nfs_put_lock_context(dreq->l_ctx);
211 if (dreq->ctx != NULL)
212 put_nfs_open_context(dreq->ctx);
213 kmem_cache_free(nfs_direct_cachep, dreq);
214}
215
216static void nfs_direct_req_release(struct nfs_direct_req *dreq)
217{
218 kref_put(&dreq->kref, nfs_direct_req_free);
219}
220
221ssize_t nfs_dreq_bytes_left(struct nfs_direct_req *dreq, loff_t offset)
222{
223 loff_t start = offset - dreq->io_start;
224 return dreq->max_count - start;
225}
226EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left);
227
228/*
229 * Collects and returns the final error value/byte-count.
230 */
231static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
232{
233 ssize_t result = -EIOCBQUEUED;
234
235 /* Async requests don't wait here */
236 if (dreq->iocb)
237 goto out;
238
239 result = wait_for_completion_killable(&dreq->completion);
240
241 if (!result) {
242 result = dreq->count;
243 WARN_ON_ONCE(dreq->count < 0);
244 }
245 if (!result)
246 result = dreq->error;
247
248out:
249 return (ssize_t) result;
250}
251
252/*
253 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
254 * the iocb is still valid here if this is a synchronous request.
255 */
256static void nfs_direct_complete(struct nfs_direct_req *dreq)
257{
258 struct inode *inode = dreq->inode;
259
260 inode_dio_end(inode);
261
262 if (dreq->iocb) {
263 long res = (long) dreq->error;
264 if (dreq->count != 0) {
265 res = (long) dreq->count;
266 WARN_ON_ONCE(dreq->count < 0);
267 }
268 dreq->iocb->ki_complete(dreq->iocb, res);
269 }
270
271 complete(&dreq->completion);
272
273 nfs_direct_req_release(dreq);
274}
275
276static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
277{
278 unsigned long bytes = 0;
279 struct nfs_direct_req *dreq = hdr->dreq;
280
281 spin_lock(&dreq->lock);
282 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
283 spin_unlock(&dreq->lock);
284 goto out_put;
285 }
286
287 nfs_direct_count_bytes(dreq, hdr);
288 spin_unlock(&dreq->lock);
289
290 nfs_update_delegated_atime(dreq->inode);
291
292 while (!list_empty(&hdr->pages)) {
293 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
294 struct page *page = req->wb_page;
295
296 if (!PageCompound(page) && bytes < hdr->good_bytes &&
297 (dreq->flags == NFS_ODIRECT_SHOULD_DIRTY))
298 set_page_dirty(page);
299 bytes += req->wb_bytes;
300 nfs_list_remove_request(req);
301 nfs_release_request(req);
302 }
303out_put:
304 if (put_dreq(dreq))
305 nfs_direct_complete(dreq);
306 hdr->release(hdr);
307}
308
309static void nfs_read_sync_pgio_error(struct list_head *head, int error)
310{
311 struct nfs_page *req;
312
313 while (!list_empty(head)) {
314 req = nfs_list_entry(head->next);
315 nfs_list_remove_request(req);
316 nfs_release_request(req);
317 }
318}
319
320static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
321{
322 get_dreq(hdr->dreq);
323}
324
325static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
326 .error_cleanup = nfs_read_sync_pgio_error,
327 .init_hdr = nfs_direct_pgio_init,
328 .completion = nfs_direct_read_completion,
329};
330
331/*
332 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
333 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
334 * bail and stop sending more reads. Read length accounting is
335 * handled automatically by nfs_direct_read_result(). Otherwise, if
336 * no requests have been sent, just return an error.
337 */
338
339static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
340 struct iov_iter *iter,
341 loff_t pos)
342{
343 struct nfs_pageio_descriptor desc;
344 struct inode *inode = dreq->inode;
345 ssize_t result = -EINVAL;
346 size_t requested_bytes = 0;
347 size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
348
349 nfs_pageio_init_read(&desc, dreq->inode, false,
350 &nfs_direct_read_completion_ops);
351 get_dreq(dreq);
352 desc.pg_dreq = dreq;
353 inode_dio_begin(inode);
354
355 while (iov_iter_count(iter)) {
356 struct page **pagevec;
357 size_t bytes;
358 size_t pgbase;
359 unsigned npages, i;
360
361 result = iov_iter_get_pages_alloc2(iter, &pagevec,
362 rsize, &pgbase);
363 if (result < 0)
364 break;
365
366 bytes = result;
367 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
368 for (i = 0; i < npages; i++) {
369 struct nfs_page *req;
370 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
371 /* XXX do we need to do the eof zeroing found in async_filler? */
372 req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
373 pgbase, pos, req_len);
374 if (IS_ERR(req)) {
375 result = PTR_ERR(req);
376 break;
377 }
378 if (!nfs_pageio_add_request(&desc, req)) {
379 result = desc.pg_error;
380 nfs_release_request(req);
381 break;
382 }
383 pgbase = 0;
384 bytes -= req_len;
385 requested_bytes += req_len;
386 pos += req_len;
387 }
388 nfs_direct_release_pages(pagevec, npages);
389 kvfree(pagevec);
390 if (result < 0)
391 break;
392 }
393
394 nfs_pageio_complete(&desc);
395
396 /*
397 * If no bytes were started, return the error, and let the
398 * generic layer handle the completion.
399 */
400 if (requested_bytes == 0) {
401 inode_dio_end(inode);
402 nfs_direct_req_release(dreq);
403 return result < 0 ? result : -EIO;
404 }
405
406 if (put_dreq(dreq))
407 nfs_direct_complete(dreq);
408 return requested_bytes;
409}
410
411/**
412 * nfs_file_direct_read - file direct read operation for NFS files
413 * @iocb: target I/O control block
414 * @iter: vector of user buffers into which to read data
415 * @swap: flag indicating this is swap IO, not O_DIRECT IO
416 *
417 * We use this function for direct reads instead of calling
418 * generic_file_aio_read() in order to avoid gfar's check to see if
419 * the request starts before the end of the file. For that check
420 * to work, we must generate a GETATTR before each direct read, and
421 * even then there is a window between the GETATTR and the subsequent
422 * READ where the file size could change. Our preference is simply
423 * to do all reads the application wants, and the server will take
424 * care of managing the end of file boundary.
425 *
426 * This function also eliminates unnecessarily updating the file's
427 * atime locally, as the NFS server sets the file's atime, and this
428 * client must read the updated atime from the server back into its
429 * cache.
430 */
431ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
432 bool swap)
433{
434 struct file *file = iocb->ki_filp;
435 struct address_space *mapping = file->f_mapping;
436 struct inode *inode = mapping->host;
437 struct nfs_direct_req *dreq;
438 struct nfs_lock_context *l_ctx;
439 ssize_t result, requested;
440 size_t count = iov_iter_count(iter);
441 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
442
443 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
444 file, count, (long long) iocb->ki_pos);
445
446 result = 0;
447 if (!count)
448 goto out;
449
450 task_io_account_read(count);
451
452 result = -ENOMEM;
453 dreq = nfs_direct_req_alloc();
454 if (dreq == NULL)
455 goto out;
456
457 dreq->inode = inode;
458 dreq->max_count = count;
459 dreq->io_start = iocb->ki_pos;
460 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
461 l_ctx = nfs_get_lock_context(dreq->ctx);
462 if (IS_ERR(l_ctx)) {
463 result = PTR_ERR(l_ctx);
464 nfs_direct_req_release(dreq);
465 goto out_release;
466 }
467 dreq->l_ctx = l_ctx;
468 if (!is_sync_kiocb(iocb))
469 dreq->iocb = iocb;
470
471 if (user_backed_iter(iter))
472 dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
473
474 if (!swap) {
475 result = nfs_start_io_direct(inode);
476 if (result) {
477 /* release the reference that would usually be
478 * consumed by nfs_direct_read_schedule_iovec()
479 */
480 nfs_direct_req_release(dreq);
481 goto out_release;
482 }
483 }
484
485 NFS_I(inode)->read_io += count;
486 requested = nfs_direct_read_schedule_iovec(dreq, iter, iocb->ki_pos);
487
488 if (!swap)
489 nfs_end_io_direct(inode);
490
491 if (requested > 0) {
492 result = nfs_direct_wait(dreq);
493 if (result > 0) {
494 requested -= result;
495 iocb->ki_pos += result;
496 }
497 iov_iter_revert(iter, requested);
498 } else {
499 result = requested;
500 }
501
502out_release:
503 nfs_direct_req_release(dreq);
504out:
505 return result;
506}
507
508static void nfs_direct_add_page_head(struct list_head *list,
509 struct nfs_page *req)
510{
511 struct nfs_page *head = req->wb_head;
512
513 if (!list_empty(&head->wb_list) || !nfs_lock_request(head))
514 return;
515 if (!list_empty(&head->wb_list)) {
516 nfs_unlock_request(head);
517 return;
518 }
519 list_add(&head->wb_list, list);
520 kref_get(&head->wb_kref);
521 kref_get(&head->wb_kref);
522}
523
524static void nfs_direct_join_group(struct list_head *list,
525 struct nfs_commit_info *cinfo,
526 struct inode *inode)
527{
528 struct nfs_page *req, *subreq;
529
530 list_for_each_entry(req, list, wb_list) {
531 if (req->wb_head != req) {
532 nfs_direct_add_page_head(&req->wb_list, req);
533 continue;
534 }
535 subreq = req->wb_this_page;
536 if (subreq == req)
537 continue;
538 do {
539 /*
540 * Remove subrequests from this list before freeing
541 * them in the call to nfs_join_page_group().
542 */
543 if (!list_empty(&subreq->wb_list)) {
544 nfs_list_remove_request(subreq);
545 nfs_release_request(subreq);
546 }
547 } while ((subreq = subreq->wb_this_page) != req);
548 nfs_join_page_group(req, cinfo, inode);
549 }
550}
551
552static void
553nfs_direct_write_scan_commit_list(struct inode *inode,
554 struct list_head *list,
555 struct nfs_commit_info *cinfo)
556{
557 mutex_lock(&NFS_I(cinfo->inode)->commit_mutex);
558 pnfs_recover_commit_reqs(list, cinfo);
559 nfs_scan_commit_list(&cinfo->mds->list, list, cinfo, 0);
560 mutex_unlock(&NFS_I(cinfo->inode)->commit_mutex);
561}
562
563static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
564{
565 struct nfs_pageio_descriptor desc;
566 struct nfs_page *req;
567 LIST_HEAD(reqs);
568 struct nfs_commit_info cinfo;
569
570 nfs_init_cinfo_from_dreq(&cinfo, dreq);
571 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
572
573 nfs_direct_join_group(&reqs, &cinfo, dreq->inode);
574
575 nfs_clear_pnfs_ds_commit_verifiers(&dreq->ds_cinfo);
576 get_dreq(dreq);
577
578 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE, false,
579 &nfs_direct_write_completion_ops);
580 desc.pg_dreq = dreq;
581
582 while (!list_empty(&reqs)) {
583 req = nfs_list_entry(reqs.next);
584 /* Bump the transmission count */
585 req->wb_nio++;
586 if (!nfs_pageio_add_request(&desc, req)) {
587 spin_lock(&dreq->lock);
588 if (dreq->error < 0) {
589 desc.pg_error = dreq->error;
590 } else if (desc.pg_error != -EAGAIN) {
591 dreq->flags = 0;
592 if (!desc.pg_error)
593 desc.pg_error = -EIO;
594 dreq->error = desc.pg_error;
595 } else
596 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
597 spin_unlock(&dreq->lock);
598 break;
599 }
600 nfs_release_request(req);
601 }
602 nfs_pageio_complete(&desc);
603
604 while (!list_empty(&reqs)) {
605 req = nfs_list_entry(reqs.next);
606 nfs_list_remove_request(req);
607 nfs_unlock_and_release_request(req);
608 if (desc.pg_error == -EAGAIN) {
609 nfs_mark_request_commit(req, NULL, &cinfo, 0);
610 } else {
611 spin_lock(&dreq->lock);
612 nfs_direct_truncate_request(dreq, req);
613 spin_unlock(&dreq->lock);
614 nfs_release_request(req);
615 }
616 }
617
618 if (put_dreq(dreq))
619 nfs_direct_write_complete(dreq);
620}
621
622static void nfs_direct_commit_complete(struct nfs_commit_data *data)
623{
624 const struct nfs_writeverf *verf = data->res.verf;
625 struct nfs_direct_req *dreq = data->dreq;
626 struct nfs_commit_info cinfo;
627 struct nfs_page *req;
628 int status = data->task.tk_status;
629
630 trace_nfs_direct_commit_complete(dreq);
631
632 spin_lock(&dreq->lock);
633 if (status < 0) {
634 /* Errors in commit are fatal */
635 dreq->error = status;
636 dreq->flags = NFS_ODIRECT_DONE;
637 } else {
638 status = dreq->error;
639 }
640 spin_unlock(&dreq->lock);
641
642 nfs_init_cinfo_from_dreq(&cinfo, dreq);
643
644 while (!list_empty(&data->pages)) {
645 req = nfs_list_entry(data->pages.next);
646 nfs_list_remove_request(req);
647 if (status < 0) {
648 spin_lock(&dreq->lock);
649 nfs_direct_truncate_request(dreq, req);
650 spin_unlock(&dreq->lock);
651 nfs_release_request(req);
652 } else if (!nfs_write_match_verf(verf, req)) {
653 spin_lock(&dreq->lock);
654 if (dreq->flags == 0)
655 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
656 spin_unlock(&dreq->lock);
657 /*
658 * Despite the reboot, the write was successful,
659 * so reset wb_nio.
660 */
661 req->wb_nio = 0;
662 nfs_mark_request_commit(req, NULL, &cinfo, 0);
663 } else
664 nfs_release_request(req);
665 nfs_unlock_and_release_request(req);
666 }
667
668 if (nfs_commit_end(cinfo.mds))
669 nfs_direct_write_complete(dreq);
670}
671
672static void nfs_direct_resched_write(struct nfs_commit_info *cinfo,
673 struct nfs_page *req)
674{
675 struct nfs_direct_req *dreq = cinfo->dreq;
676
677 trace_nfs_direct_resched_write(dreq);
678
679 spin_lock(&dreq->lock);
680 if (dreq->flags != NFS_ODIRECT_DONE)
681 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
682 spin_unlock(&dreq->lock);
683 nfs_mark_request_commit(req, NULL, cinfo, 0);
684}
685
686static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
687 .completion = nfs_direct_commit_complete,
688 .resched_write = nfs_direct_resched_write,
689};
690
691static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
692{
693 int res;
694 struct nfs_commit_info cinfo;
695 LIST_HEAD(mds_list);
696
697 nfs_init_cinfo_from_dreq(&cinfo, dreq);
698 nfs_commit_begin(cinfo.mds);
699 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
700 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
701 if (res < 0) { /* res == -ENOMEM */
702 spin_lock(&dreq->lock);
703 if (dreq->flags == 0)
704 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
705 spin_unlock(&dreq->lock);
706 }
707 if (nfs_commit_end(cinfo.mds))
708 nfs_direct_write_complete(dreq);
709}
710
711static void nfs_direct_write_clear_reqs(struct nfs_direct_req *dreq)
712{
713 struct nfs_commit_info cinfo;
714 struct nfs_page *req;
715 LIST_HEAD(reqs);
716
717 nfs_init_cinfo_from_dreq(&cinfo, dreq);
718 nfs_direct_write_scan_commit_list(dreq->inode, &reqs, &cinfo);
719
720 while (!list_empty(&reqs)) {
721 req = nfs_list_entry(reqs.next);
722 nfs_list_remove_request(req);
723 nfs_direct_truncate_request(dreq, req);
724 nfs_release_request(req);
725 nfs_unlock_and_release_request(req);
726 }
727}
728
729static void nfs_direct_write_schedule_work(struct work_struct *work)
730{
731 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
732 int flags = dreq->flags;
733
734 dreq->flags = 0;
735 switch (flags) {
736 case NFS_ODIRECT_DO_COMMIT:
737 nfs_direct_commit_schedule(dreq);
738 break;
739 case NFS_ODIRECT_RESCHED_WRITES:
740 nfs_direct_write_reschedule(dreq);
741 break;
742 default:
743 nfs_direct_write_clear_reqs(dreq);
744 nfs_zap_mapping(dreq->inode, dreq->inode->i_mapping);
745 nfs_direct_complete(dreq);
746 }
747}
748
749static void nfs_direct_write_complete(struct nfs_direct_req *dreq)
750{
751 trace_nfs_direct_write_complete(dreq);
752 queue_work(nfsiod_workqueue, &dreq->work); /* Calls nfs_direct_write_schedule_work */
753}
754
755static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
756{
757 struct nfs_direct_req *dreq = hdr->dreq;
758 struct nfs_commit_info cinfo;
759 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
760 struct inode *inode = dreq->inode;
761 int flags = NFS_ODIRECT_DONE;
762
763 trace_nfs_direct_write_completion(dreq);
764
765 nfs_init_cinfo_from_dreq(&cinfo, dreq);
766
767 spin_lock(&dreq->lock);
768 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) {
769 spin_unlock(&dreq->lock);
770 goto out_put;
771 }
772
773 nfs_direct_count_bytes(dreq, hdr);
774 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES, &hdr->flags) &&
775 !test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
776 if (!dreq->flags)
777 dreq->flags = NFS_ODIRECT_DO_COMMIT;
778 flags = dreq->flags;
779 }
780 spin_unlock(&dreq->lock);
781
782 spin_lock(&inode->i_lock);
783 nfs_direct_file_adjust_size_locked(inode, dreq->io_start, dreq->count);
784 nfs_update_delegated_mtime_locked(dreq->inode);
785 spin_unlock(&inode->i_lock);
786
787 while (!list_empty(&hdr->pages)) {
788
789 req = nfs_list_entry(hdr->pages.next);
790 nfs_list_remove_request(req);
791 if (flags == NFS_ODIRECT_DO_COMMIT) {
792 kref_get(&req->wb_kref);
793 memcpy(&req->wb_verf, &hdr->verf.verifier,
794 sizeof(req->wb_verf));
795 nfs_mark_request_commit(req, hdr->lseg, &cinfo,
796 hdr->ds_commit_idx);
797 } else if (flags == NFS_ODIRECT_RESCHED_WRITES) {
798 kref_get(&req->wb_kref);
799 nfs_mark_request_commit(req, NULL, &cinfo, 0);
800 }
801 nfs_unlock_and_release_request(req);
802 }
803
804out_put:
805 if (put_dreq(dreq))
806 nfs_direct_write_complete(dreq);
807 hdr->release(hdr);
808}
809
810static void nfs_write_sync_pgio_error(struct list_head *head, int error)
811{
812 struct nfs_page *req;
813
814 while (!list_empty(head)) {
815 req = nfs_list_entry(head->next);
816 nfs_list_remove_request(req);
817 nfs_unlock_and_release_request(req);
818 }
819}
820
821static void nfs_direct_write_reschedule_io(struct nfs_pgio_header *hdr)
822{
823 struct nfs_direct_req *dreq = hdr->dreq;
824 struct nfs_page *req;
825 struct nfs_commit_info cinfo;
826
827 trace_nfs_direct_write_reschedule_io(dreq);
828
829 nfs_init_cinfo_from_dreq(&cinfo, dreq);
830 spin_lock(&dreq->lock);
831 if (dreq->error == 0)
832 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
833 set_bit(NFS_IOHDR_REDO, &hdr->flags);
834 spin_unlock(&dreq->lock);
835 while (!list_empty(&hdr->pages)) {
836 req = nfs_list_entry(hdr->pages.next);
837 nfs_list_remove_request(req);
838 nfs_unlock_request(req);
839 nfs_mark_request_commit(req, NULL, &cinfo, 0);
840 }
841}
842
843static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
844 .error_cleanup = nfs_write_sync_pgio_error,
845 .init_hdr = nfs_direct_pgio_init,
846 .completion = nfs_direct_write_completion,
847 .reschedule_io = nfs_direct_write_reschedule_io,
848};
849
850
851/*
852 * NB: Return the value of the first error return code. Subsequent
853 * errors after the first one are ignored.
854 */
855/*
856 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
857 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
858 * bail and stop sending more writes. Write length accounting is
859 * handled automatically by nfs_direct_write_result(). Otherwise, if
860 * no requests have been sent, just return an error.
861 */
862static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
863 struct iov_iter *iter,
864 loff_t pos, int ioflags)
865{
866 struct nfs_pageio_descriptor desc;
867 struct inode *inode = dreq->inode;
868 struct nfs_commit_info cinfo;
869 ssize_t result = 0;
870 size_t requested_bytes = 0;
871 size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
872 bool defer = false;
873
874 trace_nfs_direct_write_schedule_iovec(dreq);
875
876 nfs_pageio_init_write(&desc, inode, ioflags, false,
877 &nfs_direct_write_completion_ops);
878 desc.pg_dreq = dreq;
879 get_dreq(dreq);
880 inode_dio_begin(inode);
881
882 NFS_I(inode)->write_io += iov_iter_count(iter);
883 while (iov_iter_count(iter)) {
884 struct page **pagevec;
885 size_t bytes;
886 size_t pgbase;
887 unsigned npages, i;
888
889 result = iov_iter_get_pages_alloc2(iter, &pagevec,
890 wsize, &pgbase);
891 if (result < 0)
892 break;
893
894 bytes = result;
895 npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
896 for (i = 0; i < npages; i++) {
897 struct nfs_page *req;
898 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
899
900 req = nfs_page_create_from_page(dreq->ctx, pagevec[i],
901 pgbase, pos, req_len);
902 if (IS_ERR(req)) {
903 result = PTR_ERR(req);
904 break;
905 }
906
907 if (desc.pg_error < 0) {
908 nfs_free_request(req);
909 result = desc.pg_error;
910 break;
911 }
912
913 pgbase = 0;
914 bytes -= req_len;
915 requested_bytes += req_len;
916 pos += req_len;
917
918 if (defer) {
919 nfs_mark_request_commit(req, NULL, &cinfo, 0);
920 continue;
921 }
922
923 nfs_lock_request(req);
924 if (nfs_pageio_add_request(&desc, req))
925 continue;
926
927 /* Exit on hard errors */
928 if (desc.pg_error < 0 && desc.pg_error != -EAGAIN) {
929 result = desc.pg_error;
930 nfs_unlock_and_release_request(req);
931 break;
932 }
933
934 /* If the error is soft, defer remaining requests */
935 nfs_init_cinfo_from_dreq(&cinfo, dreq);
936 spin_lock(&dreq->lock);
937 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
938 spin_unlock(&dreq->lock);
939 nfs_unlock_request(req);
940 nfs_mark_request_commit(req, NULL, &cinfo, 0);
941 desc.pg_error = 0;
942 defer = true;
943 }
944 nfs_direct_release_pages(pagevec, npages);
945 kvfree(pagevec);
946 if (result < 0)
947 break;
948 }
949 nfs_pageio_complete(&desc);
950
951 /*
952 * If no bytes were started, return the error, and let the
953 * generic layer handle the completion.
954 */
955 if (requested_bytes == 0) {
956 inode_dio_end(inode);
957 nfs_direct_req_release(dreq);
958 return result < 0 ? result : -EIO;
959 }
960
961 if (put_dreq(dreq))
962 nfs_direct_write_complete(dreq);
963 return requested_bytes;
964}
965
966/**
967 * nfs_file_direct_write - file direct write operation for NFS files
968 * @iocb: target I/O control block
969 * @iter: vector of user buffers from which to write data
970 * @swap: flag indicating this is swap IO, not O_DIRECT IO
971 *
972 * We use this function for direct writes instead of calling
973 * generic_file_aio_write() in order to avoid taking the inode
974 * semaphore and updating the i_size. The NFS server will set
975 * the new i_size and this client must read the updated size
976 * back into its cache. We let the server do generic write
977 * parameter checking and report problems.
978 *
979 * We eliminate local atime updates, see direct read above.
980 *
981 * We avoid unnecessary page cache invalidations for normal cached
982 * readers of this file.
983 *
984 * Note that O_APPEND is not supported for NFS direct writes, as there
985 * is no atomic O_APPEND write facility in the NFS protocol.
986 */
987ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
988 bool swap)
989{
990 ssize_t result, requested;
991 size_t count;
992 struct file *file = iocb->ki_filp;
993 struct address_space *mapping = file->f_mapping;
994 struct inode *inode = mapping->host;
995 struct nfs_direct_req *dreq;
996 struct nfs_lock_context *l_ctx;
997 loff_t pos, end;
998
999 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
1000 file, iov_iter_count(iter), (long long) iocb->ki_pos);
1001
1002 if (swap)
1003 /* bypass generic checks */
1004 result = iov_iter_count(iter);
1005 else
1006 result = generic_write_checks(iocb, iter);
1007 if (result <= 0)
1008 return result;
1009 count = result;
1010 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
1011
1012 pos = iocb->ki_pos;
1013 end = (pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT;
1014
1015 task_io_account_write(count);
1016
1017 result = -ENOMEM;
1018 dreq = nfs_direct_req_alloc();
1019 if (!dreq)
1020 goto out;
1021
1022 dreq->inode = inode;
1023 dreq->max_count = count;
1024 dreq->io_start = pos;
1025 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
1026 l_ctx = nfs_get_lock_context(dreq->ctx);
1027 if (IS_ERR(l_ctx)) {
1028 result = PTR_ERR(l_ctx);
1029 nfs_direct_req_release(dreq);
1030 goto out_release;
1031 }
1032 dreq->l_ctx = l_ctx;
1033 if (!is_sync_kiocb(iocb))
1034 dreq->iocb = iocb;
1035 pnfs_init_ds_commit_info_ops(&dreq->ds_cinfo, inode);
1036
1037 if (swap) {
1038 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1039 FLUSH_STABLE);
1040 } else {
1041 result = nfs_start_io_direct(inode);
1042 if (result) {
1043 /* release the reference that would usually be
1044 * consumed by nfs_direct_write_schedule_iovec()
1045 */
1046 nfs_direct_req_release(dreq);
1047 goto out_release;
1048 }
1049
1050 requested = nfs_direct_write_schedule_iovec(dreq, iter, pos,
1051 FLUSH_COND_STABLE);
1052
1053 if (mapping->nrpages) {
1054 invalidate_inode_pages2_range(mapping,
1055 pos >> PAGE_SHIFT, end);
1056 }
1057
1058 nfs_end_io_direct(inode);
1059 }
1060
1061 if (requested > 0) {
1062 result = nfs_direct_wait(dreq);
1063 if (result > 0) {
1064 requested -= result;
1065 iocb->ki_pos = pos + result;
1066 /* XXX: should check the generic_write_sync retval */
1067 generic_write_sync(iocb, result);
1068 }
1069 iov_iter_revert(iter, requested);
1070 } else {
1071 result = requested;
1072 }
1073 nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
1074out_release:
1075 nfs_direct_req_release(dreq);
1076out:
1077 return result;
1078}
1079
1080/**
1081 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1082 *
1083 */
1084int __init nfs_init_directcache(void)
1085{
1086 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
1087 sizeof(struct nfs_direct_req),
1088 0, SLAB_RECLAIM_ACCOUNT,
1089 NULL);
1090 if (nfs_direct_cachep == NULL)
1091 return -ENOMEM;
1092
1093 return 0;
1094}
1095
1096/**
1097 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1098 *
1099 */
1100void nfs_destroy_directcache(void)
1101{
1102 kmem_cache_destroy(nfs_direct_cachep);
1103}
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/uaccess.h>
55#include <linux/atomic.h>
56
57#include "internal.h"
58#include "iostat.h"
59#include "pnfs.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 nfs_mds_commit_info mds_cinfo; /* Storage for cinfo */
86 struct pnfs_ds_commit_info ds_cinfo; /* Storage for cinfo */
87 struct work_struct work;
88 int flags;
89#define NFS_ODIRECT_DO_COMMIT (1) /* an unstable reply was received */
90#define NFS_ODIRECT_RESCHED_WRITES (2) /* write verification failed */
91 struct nfs_writeverf verf; /* unstable write verifier */
92};
93
94static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops;
95static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops;
96static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode);
97static void nfs_direct_write_schedule_work(struct work_struct *work);
98
99static inline void get_dreq(struct nfs_direct_req *dreq)
100{
101 atomic_inc(&dreq->io_count);
102}
103
104static inline int put_dreq(struct nfs_direct_req *dreq)
105{
106 return atomic_dec_and_test(&dreq->io_count);
107}
108
109/**
110 * nfs_direct_IO - NFS address space operation for direct I/O
111 * @rw: direction (read or write)
112 * @iocb: target I/O control block
113 * @iov: array of vectors that define I/O buffer
114 * @pos: offset in file to begin the operation
115 * @nr_segs: size of iovec array
116 *
117 * The presence of this routine in the address space ops vector means
118 * the NFS client supports direct I/O. However, we shunt off direct
119 * read and write requests before the VFS gets them, so this method
120 * should never be called.
121 */
122ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs)
123{
124 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
125 iocb->ki_filp->f_path.dentry->d_name.name,
126 (long long) pos, nr_segs);
127
128 return -EINVAL;
129}
130
131static void nfs_direct_release_pages(struct page **pages, unsigned int npages)
132{
133 unsigned int i;
134 for (i = 0; i < npages; i++)
135 page_cache_release(pages[i]);
136}
137
138void nfs_init_cinfo_from_dreq(struct nfs_commit_info *cinfo,
139 struct nfs_direct_req *dreq)
140{
141 cinfo->lock = &dreq->lock;
142 cinfo->mds = &dreq->mds_cinfo;
143 cinfo->ds = &dreq->ds_cinfo;
144 cinfo->dreq = dreq;
145 cinfo->completion_ops = &nfs_direct_commit_completion_ops;
146}
147
148static inline struct nfs_direct_req *nfs_direct_req_alloc(void)
149{
150 struct nfs_direct_req *dreq;
151
152 dreq = kmem_cache_zalloc(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->mds_cinfo.list);
160 INIT_WORK(&dreq->work, nfs_direct_write_schedule_work);
161 spin_lock_init(&dreq->lock);
162
163 return dreq;
164}
165
166static void nfs_direct_req_free(struct kref *kref)
167{
168 struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref);
169
170 if (dreq->l_ctx != NULL)
171 nfs_put_lock_context(dreq->l_ctx);
172 if (dreq->ctx != NULL)
173 put_nfs_open_context(dreq->ctx);
174 kmem_cache_free(nfs_direct_cachep, dreq);
175}
176
177static void nfs_direct_req_release(struct nfs_direct_req *dreq)
178{
179 kref_put(&dreq->kref, nfs_direct_req_free);
180}
181
182/*
183 * Collects and returns the final error value/byte-count.
184 */
185static ssize_t nfs_direct_wait(struct nfs_direct_req *dreq)
186{
187 ssize_t result = -EIOCBQUEUED;
188
189 /* Async requests don't wait here */
190 if (dreq->iocb)
191 goto out;
192
193 result = wait_for_completion_killable(&dreq->completion);
194
195 if (!result)
196 result = dreq->error;
197 if (!result)
198 result = dreq->count;
199
200out:
201 return (ssize_t) result;
202}
203
204/*
205 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
206 * the iocb is still valid here if this is a synchronous request.
207 */
208static void nfs_direct_complete(struct nfs_direct_req *dreq)
209{
210 if (dreq->iocb) {
211 long res = (long) dreq->error;
212 if (!res)
213 res = (long) dreq->count;
214 aio_complete(dreq->iocb, res, 0);
215 }
216 complete_all(&dreq->completion);
217
218 nfs_direct_req_release(dreq);
219}
220
221static void nfs_direct_readpage_release(struct nfs_page *req)
222{
223 dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
224 req->wb_context->dentry->d_inode->i_sb->s_id,
225 (long long)NFS_FILEID(req->wb_context->dentry->d_inode),
226 req->wb_bytes,
227 (long long)req_offset(req));
228 nfs_release_request(req);
229}
230
231static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
232{
233 unsigned long bytes = 0;
234 struct nfs_direct_req *dreq = hdr->dreq;
235
236 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
237 goto out_put;
238
239 spin_lock(&dreq->lock);
240 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
241 dreq->error = hdr->error;
242 else
243 dreq->count += hdr->good_bytes;
244 spin_unlock(&dreq->lock);
245
246 while (!list_empty(&hdr->pages)) {
247 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
248 struct page *page = req->wb_page;
249
250 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
251 if (bytes > hdr->good_bytes)
252 zero_user(page, 0, PAGE_SIZE);
253 else if (hdr->good_bytes - bytes < PAGE_SIZE)
254 zero_user_segment(page,
255 hdr->good_bytes & ~PAGE_MASK,
256 PAGE_SIZE);
257 }
258 if (!PageCompound(page)) {
259 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
260 if (bytes < hdr->good_bytes)
261 set_page_dirty(page);
262 } else
263 set_page_dirty(page);
264 }
265 bytes += req->wb_bytes;
266 nfs_list_remove_request(req);
267 nfs_direct_readpage_release(req);
268 }
269out_put:
270 if (put_dreq(dreq))
271 nfs_direct_complete(dreq);
272 hdr->release(hdr);
273}
274
275static void nfs_read_sync_pgio_error(struct list_head *head)
276{
277 struct nfs_page *req;
278
279 while (!list_empty(head)) {
280 req = nfs_list_entry(head->next);
281 nfs_list_remove_request(req);
282 nfs_release_request(req);
283 }
284}
285
286static void nfs_direct_pgio_init(struct nfs_pgio_header *hdr)
287{
288 get_dreq(hdr->dreq);
289}
290
291static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
292 .error_cleanup = nfs_read_sync_pgio_error,
293 .init_hdr = nfs_direct_pgio_init,
294 .completion = nfs_direct_read_completion,
295};
296
297/*
298 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
299 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
300 * bail and stop sending more reads. Read length accounting is
301 * handled automatically by nfs_direct_read_result(). Otherwise, if
302 * no requests have been sent, just return an error.
303 */
304static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
305 const struct iovec *iov,
306 loff_t pos)
307{
308 struct nfs_direct_req *dreq = desc->pg_dreq;
309 struct nfs_open_context *ctx = dreq->ctx;
310 struct inode *inode = ctx->dentry->d_inode;
311 unsigned long user_addr = (unsigned long)iov->iov_base;
312 size_t count = iov->iov_len;
313 size_t rsize = NFS_SERVER(inode)->rsize;
314 unsigned int pgbase;
315 int result;
316 ssize_t started = 0;
317 struct page **pagevec = NULL;
318 unsigned int npages;
319
320 do {
321 size_t bytes;
322 int i;
323
324 pgbase = user_addr & ~PAGE_MASK;
325 bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
326
327 result = -ENOMEM;
328 npages = nfs_page_array_len(pgbase, bytes);
329 if (!pagevec)
330 pagevec = kmalloc(npages * sizeof(struct page *),
331 GFP_KERNEL);
332 if (!pagevec)
333 break;
334 down_read(¤t->mm->mmap_sem);
335 result = get_user_pages(current, current->mm, user_addr,
336 npages, 1, 0, pagevec, NULL);
337 up_read(¤t->mm->mmap_sem);
338 if (result < 0)
339 break;
340 if ((unsigned)result < npages) {
341 bytes = result * PAGE_SIZE;
342 if (bytes <= pgbase) {
343 nfs_direct_release_pages(pagevec, result);
344 break;
345 }
346 bytes -= pgbase;
347 npages = result;
348 }
349
350 for (i = 0; i < npages; i++) {
351 struct nfs_page *req;
352 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
353 /* XXX do we need to do the eof zeroing found in async_filler? */
354 req = nfs_create_request(dreq->ctx, dreq->inode,
355 pagevec[i],
356 pgbase, req_len);
357 if (IS_ERR(req)) {
358 result = PTR_ERR(req);
359 break;
360 }
361 req->wb_index = pos >> PAGE_SHIFT;
362 req->wb_offset = pos & ~PAGE_MASK;
363 if (!nfs_pageio_add_request(desc, req)) {
364 result = desc->pg_error;
365 nfs_release_request(req);
366 break;
367 }
368 pgbase = 0;
369 bytes -= req_len;
370 started += req_len;
371 user_addr += req_len;
372 pos += req_len;
373 count -= req_len;
374 }
375 /* The nfs_page now hold references to these pages */
376 nfs_direct_release_pages(pagevec, npages);
377 } while (count != 0 && result >= 0);
378
379 kfree(pagevec);
380
381 if (started)
382 return started;
383 return result < 0 ? (ssize_t) result : -EFAULT;
384}
385
386static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
387 const struct iovec *iov,
388 unsigned long nr_segs,
389 loff_t pos)
390{
391 struct nfs_pageio_descriptor desc;
392 ssize_t result = -EINVAL;
393 size_t requested_bytes = 0;
394 unsigned long seg;
395
396 nfs_pageio_init_read(&desc, dreq->inode,
397 &nfs_direct_read_completion_ops);
398 get_dreq(dreq);
399 desc.pg_dreq = dreq;
400
401 for (seg = 0; seg < nr_segs; seg++) {
402 const struct iovec *vec = &iov[seg];
403 result = nfs_direct_read_schedule_segment(&desc, vec, pos);
404 if (result < 0)
405 break;
406 requested_bytes += result;
407 if ((size_t)result < vec->iov_len)
408 break;
409 pos += vec->iov_len;
410 }
411
412 nfs_pageio_complete(&desc);
413
414 /*
415 * If no bytes were started, return the error, and let the
416 * generic layer handle the completion.
417 */
418 if (requested_bytes == 0) {
419 nfs_direct_req_release(dreq);
420 return result < 0 ? result : -EIO;
421 }
422
423 if (put_dreq(dreq))
424 nfs_direct_complete(dreq);
425 return 0;
426}
427
428static ssize_t nfs_direct_read(struct kiocb *iocb, const struct iovec *iov,
429 unsigned long nr_segs, loff_t pos)
430{
431 ssize_t result = -ENOMEM;
432 struct inode *inode = iocb->ki_filp->f_mapping->host;
433 struct nfs_direct_req *dreq;
434
435 dreq = nfs_direct_req_alloc();
436 if (dreq == NULL)
437 goto out;
438
439 dreq->inode = inode;
440 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
441 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
442 if (dreq->l_ctx == NULL)
443 goto out_release;
444 if (!is_sync_kiocb(iocb))
445 dreq->iocb = iocb;
446
447 result = nfs_direct_read_schedule_iovec(dreq, iov, nr_segs, pos);
448 if (!result)
449 result = nfs_direct_wait(dreq);
450 NFS_I(inode)->read_io += result;
451out_release:
452 nfs_direct_req_release(dreq);
453out:
454 return result;
455}
456
457static void nfs_inode_dio_write_done(struct inode *inode)
458{
459 nfs_zap_mapping(inode, inode->i_mapping);
460 inode_dio_done(inode);
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 nfs_pageio_descriptor desc;
467 struct nfs_page *req, *tmp;
468 LIST_HEAD(reqs);
469 struct nfs_commit_info cinfo;
470 LIST_HEAD(failed);
471
472 nfs_init_cinfo_from_dreq(&cinfo, dreq);
473 pnfs_recover_commit_reqs(dreq->inode, &reqs, &cinfo);
474 spin_lock(cinfo.lock);
475 nfs_scan_commit_list(&cinfo.mds->list, &reqs, &cinfo, 0);
476 spin_unlock(cinfo.lock);
477
478 dreq->count = 0;
479 get_dreq(dreq);
480
481 nfs_pageio_init_write(&desc, dreq->inode, FLUSH_STABLE,
482 &nfs_direct_write_completion_ops);
483 desc.pg_dreq = dreq;
484
485 list_for_each_entry_safe(req, tmp, &reqs, wb_list) {
486 if (!nfs_pageio_add_request(&desc, req)) {
487 nfs_list_remove_request(req);
488 nfs_list_add_request(req, &failed);
489 spin_lock(cinfo.lock);
490 dreq->flags = 0;
491 dreq->error = -EIO;
492 spin_unlock(cinfo.lock);
493 }
494 nfs_release_request(req);
495 }
496 nfs_pageio_complete(&desc);
497
498 while (!list_empty(&failed)) {
499 req = nfs_list_entry(failed.next);
500 nfs_list_remove_request(req);
501 nfs_unlock_and_release_request(req);
502 }
503
504 if (put_dreq(dreq))
505 nfs_direct_write_complete(dreq, dreq->inode);
506}
507
508static void nfs_direct_commit_complete(struct nfs_commit_data *data)
509{
510 struct nfs_direct_req *dreq = data->dreq;
511 struct nfs_commit_info cinfo;
512 struct nfs_page *req;
513 int status = data->task.tk_status;
514
515 nfs_init_cinfo_from_dreq(&cinfo, dreq);
516 if (status < 0) {
517 dprintk("NFS: %5u commit failed with error %d.\n",
518 data->task.tk_pid, status);
519 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
520 } else if (memcmp(&dreq->verf, &data->verf, sizeof(data->verf))) {
521 dprintk("NFS: %5u commit verify failed\n", data->task.tk_pid);
522 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
523 }
524
525 dprintk("NFS: %5u commit returned %d\n", data->task.tk_pid, status);
526 while (!list_empty(&data->pages)) {
527 req = nfs_list_entry(data->pages.next);
528 nfs_list_remove_request(req);
529 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES) {
530 /* Note the rewrite will go through mds */
531 nfs_mark_request_commit(req, NULL, &cinfo);
532 } else
533 nfs_release_request(req);
534 nfs_unlock_and_release_request(req);
535 }
536
537 if (atomic_dec_and_test(&cinfo.mds->rpcs_out))
538 nfs_direct_write_complete(dreq, data->inode);
539}
540
541static void nfs_direct_error_cleanup(struct nfs_inode *nfsi)
542{
543 /* There is no lock to clear */
544}
545
546static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops = {
547 .completion = nfs_direct_commit_complete,
548 .error_cleanup = nfs_direct_error_cleanup,
549};
550
551static void nfs_direct_commit_schedule(struct nfs_direct_req *dreq)
552{
553 int res;
554 struct nfs_commit_info cinfo;
555 LIST_HEAD(mds_list);
556
557 nfs_init_cinfo_from_dreq(&cinfo, dreq);
558 nfs_scan_commit(dreq->inode, &mds_list, &cinfo);
559 res = nfs_generic_commit_list(dreq->inode, &mds_list, 0, &cinfo);
560 if (res < 0) /* res == -ENOMEM */
561 nfs_direct_write_reschedule(dreq);
562}
563
564static void nfs_direct_write_schedule_work(struct work_struct *work)
565{
566 struct nfs_direct_req *dreq = container_of(work, struct nfs_direct_req, work);
567 int flags = dreq->flags;
568
569 dreq->flags = 0;
570 switch (flags) {
571 case NFS_ODIRECT_DO_COMMIT:
572 nfs_direct_commit_schedule(dreq);
573 break;
574 case NFS_ODIRECT_RESCHED_WRITES:
575 nfs_direct_write_reschedule(dreq);
576 break;
577 default:
578 nfs_inode_dio_write_done(dreq->inode);
579 nfs_direct_complete(dreq);
580 }
581}
582
583static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
584{
585 schedule_work(&dreq->work); /* Calls nfs_direct_write_schedule_work */
586}
587
588#else
589static void nfs_direct_write_schedule_work(struct work_struct *work)
590{
591}
592
593static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode *inode)
594{
595 nfs_inode_dio_write_done(inode);
596 nfs_direct_complete(dreq);
597}
598#endif
599
600/*
601 * NB: Return the value of the first error return code. Subsequent
602 * errors after the first one are ignored.
603 */
604/*
605 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
606 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
607 * bail and stop sending more writes. Write length accounting is
608 * handled automatically by nfs_direct_write_result(). Otherwise, if
609 * no requests have been sent, just return an error.
610 */
611static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
612 const struct iovec *iov,
613 loff_t pos)
614{
615 struct nfs_direct_req *dreq = desc->pg_dreq;
616 struct nfs_open_context *ctx = dreq->ctx;
617 struct inode *inode = ctx->dentry->d_inode;
618 unsigned long user_addr = (unsigned long)iov->iov_base;
619 size_t count = iov->iov_len;
620 size_t wsize = NFS_SERVER(inode)->wsize;
621 unsigned int pgbase;
622 int result;
623 ssize_t started = 0;
624 struct page **pagevec = NULL;
625 unsigned int npages;
626
627 do {
628 size_t bytes;
629 int i;
630
631 pgbase = user_addr & ~PAGE_MASK;
632 bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
633
634 result = -ENOMEM;
635 npages = nfs_page_array_len(pgbase, bytes);
636 if (!pagevec)
637 pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
638 if (!pagevec)
639 break;
640
641 down_read(¤t->mm->mmap_sem);
642 result = get_user_pages(current, current->mm, user_addr,
643 npages, 0, 0, pagevec, NULL);
644 up_read(¤t->mm->mmap_sem);
645 if (result < 0)
646 break;
647
648 if ((unsigned)result < npages) {
649 bytes = result * PAGE_SIZE;
650 if (bytes <= pgbase) {
651 nfs_direct_release_pages(pagevec, result);
652 break;
653 }
654 bytes -= pgbase;
655 npages = result;
656 }
657
658 for (i = 0; i < npages; i++) {
659 struct nfs_page *req;
660 unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
661
662 req = nfs_create_request(dreq->ctx, dreq->inode,
663 pagevec[i],
664 pgbase, req_len);
665 if (IS_ERR(req)) {
666 result = PTR_ERR(req);
667 break;
668 }
669 nfs_lock_request(req);
670 req->wb_index = pos >> PAGE_SHIFT;
671 req->wb_offset = pos & ~PAGE_MASK;
672 if (!nfs_pageio_add_request(desc, req)) {
673 result = desc->pg_error;
674 nfs_unlock_and_release_request(req);
675 break;
676 }
677 pgbase = 0;
678 bytes -= req_len;
679 started += req_len;
680 user_addr += req_len;
681 pos += req_len;
682 count -= req_len;
683 }
684 /* The nfs_page now hold references to these pages */
685 nfs_direct_release_pages(pagevec, npages);
686 } while (count != 0 && result >= 0);
687
688 kfree(pagevec);
689
690 if (started)
691 return started;
692 return result < 0 ? (ssize_t) result : -EFAULT;
693}
694
695static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
696{
697 struct nfs_direct_req *dreq = hdr->dreq;
698 struct nfs_commit_info cinfo;
699 int bit = -1;
700 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
701
702 if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
703 goto out_put;
704
705 nfs_init_cinfo_from_dreq(&cinfo, dreq);
706
707 spin_lock(&dreq->lock);
708
709 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
710 dreq->flags = 0;
711 dreq->error = hdr->error;
712 }
713 if (dreq->error != 0)
714 bit = NFS_IOHDR_ERROR;
715 else {
716 dreq->count += hdr->good_bytes;
717 if (test_bit(NFS_IOHDR_NEED_RESCHED, &hdr->flags)) {
718 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
719 bit = NFS_IOHDR_NEED_RESCHED;
720 } else if (test_bit(NFS_IOHDR_NEED_COMMIT, &hdr->flags)) {
721 if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
722 bit = NFS_IOHDR_NEED_RESCHED;
723 else if (dreq->flags == 0) {
724 memcpy(&dreq->verf, hdr->verf,
725 sizeof(dreq->verf));
726 bit = NFS_IOHDR_NEED_COMMIT;
727 dreq->flags = NFS_ODIRECT_DO_COMMIT;
728 } else if (dreq->flags == NFS_ODIRECT_DO_COMMIT) {
729 if (memcmp(&dreq->verf, hdr->verf, sizeof(dreq->verf))) {
730 dreq->flags = NFS_ODIRECT_RESCHED_WRITES;
731 bit = NFS_IOHDR_NEED_RESCHED;
732 } else
733 bit = NFS_IOHDR_NEED_COMMIT;
734 }
735 }
736 }
737 spin_unlock(&dreq->lock);
738
739 while (!list_empty(&hdr->pages)) {
740 req = nfs_list_entry(hdr->pages.next);
741 nfs_list_remove_request(req);
742 switch (bit) {
743 case NFS_IOHDR_NEED_RESCHED:
744 case NFS_IOHDR_NEED_COMMIT:
745 kref_get(&req->wb_kref);
746 nfs_mark_request_commit(req, hdr->lseg, &cinfo);
747 }
748 nfs_unlock_and_release_request(req);
749 }
750
751out_put:
752 if (put_dreq(dreq))
753 nfs_direct_write_complete(dreq, hdr->inode);
754 hdr->release(hdr);
755}
756
757static void nfs_write_sync_pgio_error(struct list_head *head)
758{
759 struct nfs_page *req;
760
761 while (!list_empty(head)) {
762 req = nfs_list_entry(head->next);
763 nfs_list_remove_request(req);
764 nfs_unlock_and_release_request(req);
765 }
766}
767
768static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
769 .error_cleanup = nfs_write_sync_pgio_error,
770 .init_hdr = nfs_direct_pgio_init,
771 .completion = nfs_direct_write_completion,
772};
773
774static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
775 const struct iovec *iov,
776 unsigned long nr_segs,
777 loff_t pos)
778{
779 struct nfs_pageio_descriptor desc;
780 struct inode *inode = dreq->inode;
781 ssize_t result = 0;
782 size_t requested_bytes = 0;
783 unsigned long seg;
784
785 nfs_pageio_init_write(&desc, inode, FLUSH_COND_STABLE,
786 &nfs_direct_write_completion_ops);
787 desc.pg_dreq = dreq;
788 get_dreq(dreq);
789 atomic_inc(&inode->i_dio_count);
790
791 for (seg = 0; seg < nr_segs; seg++) {
792 const struct iovec *vec = &iov[seg];
793 result = nfs_direct_write_schedule_segment(&desc, vec, pos);
794 if (result < 0)
795 break;
796 requested_bytes += result;
797 if ((size_t)result < vec->iov_len)
798 break;
799 pos += vec->iov_len;
800 }
801 nfs_pageio_complete(&desc);
802 NFS_I(dreq->inode)->write_io += desc.pg_bytes_written;
803
804 /*
805 * If no bytes were started, return the error, and let the
806 * generic layer handle the completion.
807 */
808 if (requested_bytes == 0) {
809 inode_dio_done(inode);
810 nfs_direct_req_release(dreq);
811 return result < 0 ? result : -EIO;
812 }
813
814 if (put_dreq(dreq))
815 nfs_direct_write_complete(dreq, dreq->inode);
816 return 0;
817}
818
819static ssize_t nfs_direct_write(struct kiocb *iocb, const struct iovec *iov,
820 unsigned long nr_segs, loff_t pos,
821 size_t count)
822{
823 ssize_t result = -ENOMEM;
824 struct inode *inode = iocb->ki_filp->f_mapping->host;
825 struct nfs_direct_req *dreq;
826
827 dreq = nfs_direct_req_alloc();
828 if (!dreq)
829 goto out;
830
831 dreq->inode = inode;
832 dreq->ctx = get_nfs_open_context(nfs_file_open_context(iocb->ki_filp));
833 dreq->l_ctx = nfs_get_lock_context(dreq->ctx);
834 if (dreq->l_ctx == NULL)
835 goto out_release;
836 if (!is_sync_kiocb(iocb))
837 dreq->iocb = iocb;
838
839 result = nfs_direct_write_schedule_iovec(dreq, iov, nr_segs, pos);
840 if (!result)
841 result = nfs_direct_wait(dreq);
842out_release:
843 nfs_direct_req_release(dreq);
844out:
845 return result;
846}
847
848/**
849 * nfs_file_direct_read - file direct read operation for NFS files
850 * @iocb: target I/O control block
851 * @iov: vector of user buffers into which to read data
852 * @nr_segs: size of iov vector
853 * @pos: byte offset in file where reading starts
854 *
855 * We use this function for direct reads instead of calling
856 * generic_file_aio_read() in order to avoid gfar's check to see if
857 * the request starts before the end of the file. For that check
858 * to work, we must generate a GETATTR before each direct read, and
859 * even then there is a window between the GETATTR and the subsequent
860 * READ where the file size could change. Our preference is simply
861 * to do all reads the application wants, and the server will take
862 * care of managing the end of file boundary.
863 *
864 * This function also eliminates unnecessarily updating the file's
865 * atime locally, as the NFS server sets the file's atime, and this
866 * client must read the updated atime from the server back into its
867 * cache.
868 */
869ssize_t nfs_file_direct_read(struct kiocb *iocb, const struct iovec *iov,
870 unsigned long nr_segs, loff_t pos)
871{
872 ssize_t retval = -EINVAL;
873 struct file *file = iocb->ki_filp;
874 struct address_space *mapping = file->f_mapping;
875 size_t count;
876
877 count = iov_length(iov, nr_segs);
878 nfs_add_stats(mapping->host, NFSIOS_DIRECTREADBYTES, count);
879
880 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
881 file->f_path.dentry->d_parent->d_name.name,
882 file->f_path.dentry->d_name.name,
883 count, (long long) pos);
884
885 retval = 0;
886 if (!count)
887 goto out;
888
889 retval = nfs_sync_mapping(mapping);
890 if (retval)
891 goto out;
892
893 task_io_account_read(count);
894
895 retval = nfs_direct_read(iocb, iov, nr_segs, pos);
896 if (retval > 0)
897 iocb->ki_pos = pos + retval;
898
899out:
900 return retval;
901}
902
903/**
904 * nfs_file_direct_write - file direct write operation for NFS files
905 * @iocb: target I/O control block
906 * @iov: vector of user buffers from which to write data
907 * @nr_segs: size of iov vector
908 * @pos: byte offset in file where writing starts
909 *
910 * We use this function for direct writes instead of calling
911 * generic_file_aio_write() in order to avoid taking the inode
912 * semaphore and updating the i_size. The NFS server will set
913 * the new i_size and this client must read the updated size
914 * back into its cache. We let the server do generic write
915 * parameter checking and report problems.
916 *
917 * We eliminate local atime updates, see direct read above.
918 *
919 * We avoid unnecessary page cache invalidations for normal cached
920 * readers of this file.
921 *
922 * Note that O_APPEND is not supported for NFS direct writes, as there
923 * is no atomic O_APPEND write facility in the NFS protocol.
924 */
925ssize_t nfs_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
926 unsigned long nr_segs, loff_t pos)
927{
928 ssize_t retval = -EINVAL;
929 struct file *file = iocb->ki_filp;
930 struct address_space *mapping = file->f_mapping;
931 size_t count;
932
933 count = iov_length(iov, nr_segs);
934 nfs_add_stats(mapping->host, NFSIOS_DIRECTWRITTENBYTES, count);
935
936 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
937 file->f_path.dentry->d_parent->d_name.name,
938 file->f_path.dentry->d_name.name,
939 count, (long long) pos);
940
941 retval = generic_write_checks(file, &pos, &count, 0);
942 if (retval)
943 goto out;
944
945 retval = -EINVAL;
946 if ((ssize_t) count < 0)
947 goto out;
948 retval = 0;
949 if (!count)
950 goto out;
951
952 retval = nfs_sync_mapping(mapping);
953 if (retval)
954 goto out;
955
956 task_io_account_write(count);
957
958 retval = nfs_direct_write(iocb, iov, nr_segs, pos, count);
959 if (retval > 0) {
960 struct inode *inode = mapping->host;
961
962 iocb->ki_pos = pos + retval;
963 spin_lock(&inode->i_lock);
964 if (i_size_read(inode) < iocb->ki_pos)
965 i_size_write(inode, iocb->ki_pos);
966 spin_unlock(&inode->i_lock);
967 }
968out:
969 return retval;
970}
971
972/**
973 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
974 *
975 */
976int __init nfs_init_directcache(void)
977{
978 nfs_direct_cachep = kmem_cache_create("nfs_direct_cache",
979 sizeof(struct nfs_direct_req),
980 0, (SLAB_RECLAIM_ACCOUNT|
981 SLAB_MEM_SPREAD),
982 NULL);
983 if (nfs_direct_cachep == NULL)
984 return -ENOMEM;
985
986 return 0;
987}
988
989/**
990 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
991 *
992 */
993void nfs_destroy_directcache(void)
994{
995 kmem_cache_destroy(nfs_direct_cachep);
996}