1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/fs/nfs/direct.c
5 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
7 * High-performance uncached I/O for the Linux NFS client
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.
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
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.
30 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
31 * help from Andrew Morton.
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
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>
52 #include <linux/nfs_fs.h>
53 #include <linux/nfs_page.h>
54 #include <linux/sunrpc/clnt.h>
56 #include <linux/uaccess.h>
57 #include <linux/atomic.h>
65 #define NFSDBG_FACILITY NFSDBG_VFS
67 static struct kmem_cache
*nfs_direct_cachep
;
69 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
;
70 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
;
71 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
);
72 static void nfs_direct_write_schedule_work(struct work_struct
*work
);
74 static inline void get_dreq(struct nfs_direct_req
*dreq
)
76 atomic_inc(&dreq
->io_count
);
79 static inline int put_dreq(struct nfs_direct_req
*dreq
)
81 return atomic_dec_and_test(&dreq
->io_count
);
85 nfs_direct_handle_truncated(struct nfs_direct_req
*dreq
,
86 const struct nfs_pgio_header
*hdr
,
89 if (!(test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
) ||
90 test_bit(NFS_IOHDR_EOF
, &hdr
->flags
)))
92 if (dreq
->max_count
>= dreq_len
) {
93 dreq
->max_count
= dreq_len
;
94 if (dreq
->count
> dreq_len
)
95 dreq
->count
= dreq_len
;
97 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
))
98 dreq
->error
= hdr
->error
;
99 else /* Clear outstanding error if this is EOF */
105 nfs_direct_count_bytes(struct nfs_direct_req
*dreq
,
106 const struct nfs_pgio_header
*hdr
)
108 loff_t hdr_end
= hdr
->io_start
+ hdr
->good_bytes
;
109 ssize_t dreq_len
= 0;
111 if (hdr_end
> dreq
->io_start
)
112 dreq_len
= hdr_end
- dreq
->io_start
;
114 nfs_direct_handle_truncated(dreq
, hdr
, dreq_len
);
116 if (dreq_len
> dreq
->max_count
)
117 dreq_len
= dreq
->max_count
;
119 if (dreq
->count
< dreq_len
)
120 dreq
->count
= dreq_len
;
124 * nfs_swap_rw - NFS address space operation for swap I/O
125 * @iocb: target I/O control block
128 * Perform IO to the swap-file. This is much like direct IO.
130 int nfs_swap_rw(struct kiocb
*iocb
, struct iov_iter
*iter
)
134 VM_BUG_ON(iov_iter_count(iter
) != PAGE_SIZE
);
136 if (iov_iter_rw(iter
) == READ
)
137 ret
= nfs_file_direct_read(iocb
, iter
, true);
139 ret
= nfs_file_direct_write(iocb
, iter
, true);
145 static void nfs_direct_release_pages(struct page
**pages
, unsigned int npages
)
148 for (i
= 0; i
< npages
; i
++)
152 void nfs_init_cinfo_from_dreq(struct nfs_commit_info
*cinfo
,
153 struct nfs_direct_req
*dreq
)
155 cinfo
->inode
= dreq
->inode
;
156 cinfo
->mds
= &dreq
->mds_cinfo
;
157 cinfo
->ds
= &dreq
->ds_cinfo
;
159 cinfo
->completion_ops
= &nfs_direct_commit_completion_ops
;
162 static inline struct nfs_direct_req
*nfs_direct_req_alloc(void)
164 struct nfs_direct_req
*dreq
;
166 dreq
= kmem_cache_zalloc(nfs_direct_cachep
, GFP_KERNEL
);
170 kref_init(&dreq
->kref
);
171 kref_get(&dreq
->kref
);
172 init_completion(&dreq
->completion
);
173 INIT_LIST_HEAD(&dreq
->mds_cinfo
.list
);
174 pnfs_init_ds_commit_info(&dreq
->ds_cinfo
);
175 INIT_WORK(&dreq
->work
, nfs_direct_write_schedule_work
);
176 spin_lock_init(&dreq
->lock
);
181 static void nfs_direct_req_free(struct kref
*kref
)
183 struct nfs_direct_req
*dreq
= container_of(kref
, struct nfs_direct_req
, kref
);
185 pnfs_release_ds_info(&dreq
->ds_cinfo
, dreq
->inode
);
186 if (dreq
->l_ctx
!= NULL
)
187 nfs_put_lock_context(dreq
->l_ctx
);
188 if (dreq
->ctx
!= NULL
)
189 put_nfs_open_context(dreq
->ctx
);
190 kmem_cache_free(nfs_direct_cachep
, dreq
);
193 static void nfs_direct_req_release(struct nfs_direct_req
*dreq
)
195 kref_put(&dreq
->kref
, nfs_direct_req_free
);
198 ssize_t
nfs_dreq_bytes_left(struct nfs_direct_req
*dreq
)
200 return dreq
->bytes_left
;
202 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left
);
205 * Collects and returns the final error value/byte-count.
207 static ssize_t
nfs_direct_wait(struct nfs_direct_req
*dreq
)
209 ssize_t result
= -EIOCBQUEUED
;
211 /* Async requests don't wait here */
215 result
= wait_for_completion_killable(&dreq
->completion
);
218 result
= dreq
->count
;
219 WARN_ON_ONCE(dreq
->count
< 0);
222 result
= dreq
->error
;
225 return (ssize_t
) result
;
229 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
230 * the iocb is still valid here if this is a synchronous request.
232 static void nfs_direct_complete(struct nfs_direct_req
*dreq
)
234 struct inode
*inode
= dreq
->inode
;
236 inode_dio_end(inode
);
239 long res
= (long) dreq
->error
;
240 if (dreq
->count
!= 0) {
241 res
= (long) dreq
->count
;
242 WARN_ON_ONCE(dreq
->count
< 0);
244 dreq
->iocb
->ki_complete(dreq
->iocb
, res
);
247 complete(&dreq
->completion
);
249 nfs_direct_req_release(dreq
);
252 static void nfs_direct_read_completion(struct nfs_pgio_header
*hdr
)
254 unsigned long bytes
= 0;
255 struct nfs_direct_req
*dreq
= hdr
->dreq
;
257 spin_lock(&dreq
->lock
);
258 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
)) {
259 spin_unlock(&dreq
->lock
);
263 nfs_direct_count_bytes(dreq
, hdr
);
264 spin_unlock(&dreq
->lock
);
266 while (!list_empty(&hdr
->pages
)) {
267 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
268 struct page
*page
= req
->wb_page
;
270 if (!PageCompound(page
) && bytes
< hdr
->good_bytes
&&
271 (dreq
->flags
== NFS_ODIRECT_SHOULD_DIRTY
))
272 set_page_dirty(page
);
273 bytes
+= req
->wb_bytes
;
274 nfs_list_remove_request(req
);
275 nfs_release_request(req
);
279 nfs_direct_complete(dreq
);
283 static void nfs_read_sync_pgio_error(struct list_head
*head
, int error
)
285 struct nfs_page
*req
;
287 while (!list_empty(head
)) {
288 req
= nfs_list_entry(head
->next
);
289 nfs_list_remove_request(req
);
290 nfs_release_request(req
);
294 static void nfs_direct_pgio_init(struct nfs_pgio_header
*hdr
)
299 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops
= {
300 .error_cleanup
= nfs_read_sync_pgio_error
,
301 .init_hdr
= nfs_direct_pgio_init
,
302 .completion
= nfs_direct_read_completion
,
306 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
307 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
308 * bail and stop sending more reads. Read length accounting is
309 * handled automatically by nfs_direct_read_result(). Otherwise, if
310 * no requests have been sent, just return an error.
313 static ssize_t
nfs_direct_read_schedule_iovec(struct nfs_direct_req
*dreq
,
314 struct iov_iter
*iter
,
317 struct nfs_pageio_descriptor desc
;
318 struct inode
*inode
= dreq
->inode
;
319 ssize_t result
= -EINVAL
;
320 size_t requested_bytes
= 0;
321 size_t rsize
= max_t(size_t, NFS_SERVER(inode
)->rsize
, PAGE_SIZE
);
323 nfs_pageio_init_read(&desc
, dreq
->inode
, false,
324 &nfs_direct_read_completion_ops
);
327 inode_dio_begin(inode
);
329 while (iov_iter_count(iter
)) {
330 struct page
**pagevec
;
335 result
= iov_iter_get_pages_alloc2(iter
, &pagevec
,
341 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
342 for (i
= 0; i
< npages
; i
++) {
343 struct nfs_page
*req
;
344 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
345 /* XXX do we need to do the eof zeroing found in async_filler? */
346 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
],
349 result
= PTR_ERR(req
);
352 req
->wb_index
= pos
>> PAGE_SHIFT
;
353 req
->wb_offset
= pos
& ~PAGE_MASK
;
354 if (!nfs_pageio_add_request(&desc
, req
)) {
355 result
= desc
.pg_error
;
356 nfs_release_request(req
);
361 requested_bytes
+= req_len
;
363 dreq
->bytes_left
-= req_len
;
365 nfs_direct_release_pages(pagevec
, npages
);
371 nfs_pageio_complete(&desc
);
374 * If no bytes were started, return the error, and let the
375 * generic layer handle the completion.
377 if (requested_bytes
== 0) {
378 inode_dio_end(inode
);
379 nfs_direct_req_release(dreq
);
380 return result
< 0 ? result
: -EIO
;
384 nfs_direct_complete(dreq
);
385 return requested_bytes
;
389 * nfs_file_direct_read - file direct read operation for NFS files
390 * @iocb: target I/O control block
391 * @iter: vector of user buffers into which to read data
392 * @swap: flag indicating this is swap IO, not O_DIRECT IO
394 * We use this function for direct reads instead of calling
395 * generic_file_aio_read() in order to avoid gfar's check to see if
396 * the request starts before the end of the file. For that check
397 * to work, we must generate a GETATTR before each direct read, and
398 * even then there is a window between the GETATTR and the subsequent
399 * READ where the file size could change. Our preference is simply
400 * to do all reads the application wants, and the server will take
401 * care of managing the end of file boundary.
403 * This function also eliminates unnecessarily updating the file's
404 * atime locally, as the NFS server sets the file's atime, and this
405 * client must read the updated atime from the server back into its
408 ssize_t
nfs_file_direct_read(struct kiocb
*iocb
, struct iov_iter
*iter
,
411 struct file
*file
= iocb
->ki_filp
;
412 struct address_space
*mapping
= file
->f_mapping
;
413 struct inode
*inode
= mapping
->host
;
414 struct nfs_direct_req
*dreq
;
415 struct nfs_lock_context
*l_ctx
;
416 ssize_t result
, requested
;
417 size_t count
= iov_iter_count(iter
);
418 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTREADBYTES
, count
);
420 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
421 file
, count
, (long long) iocb
->ki_pos
);
427 task_io_account_read(count
);
430 dreq
= nfs_direct_req_alloc();
435 dreq
->bytes_left
= dreq
->max_count
= count
;
436 dreq
->io_start
= iocb
->ki_pos
;
437 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
438 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
440 result
= PTR_ERR(l_ctx
);
441 nfs_direct_req_release(dreq
);
445 if (!is_sync_kiocb(iocb
))
448 if (user_backed_iter(iter
))
449 dreq
->flags
= NFS_ODIRECT_SHOULD_DIRTY
;
452 nfs_start_io_direct(inode
);
454 NFS_I(inode
)->read_io
+= count
;
455 requested
= nfs_direct_read_schedule_iovec(dreq
, iter
, iocb
->ki_pos
);
458 nfs_end_io_direct(inode
);
461 result
= nfs_direct_wait(dreq
);
464 iocb
->ki_pos
+= result
;
466 iov_iter_revert(iter
, requested
);
472 nfs_direct_req_release(dreq
);
478 nfs_direct_join_group(struct list_head
*list
, struct inode
*inode
)
480 struct nfs_page
*req
, *next
;
482 list_for_each_entry(req
, list
, wb_list
) {
483 if (req
->wb_head
!= req
|| req
->wb_this_page
== req
)
485 for (next
= req
->wb_this_page
;
486 next
!= req
->wb_head
;
487 next
= next
->wb_this_page
) {
488 nfs_list_remove_request(next
);
489 nfs_release_request(next
);
491 nfs_join_page_group(req
, inode
);
496 nfs_direct_write_scan_commit_list(struct inode
*inode
,
497 struct list_head
*list
,
498 struct nfs_commit_info
*cinfo
)
500 mutex_lock(&NFS_I(cinfo
->inode
)->commit_mutex
);
501 pnfs_recover_commit_reqs(list
, cinfo
);
502 nfs_scan_commit_list(&cinfo
->mds
->list
, list
, cinfo
, 0);
503 mutex_unlock(&NFS_I(cinfo
->inode
)->commit_mutex
);
506 static void nfs_direct_write_reschedule(struct nfs_direct_req
*dreq
)
508 struct nfs_pageio_descriptor desc
;
509 struct nfs_page
*req
, *tmp
;
511 struct nfs_commit_info cinfo
;
514 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
515 nfs_direct_write_scan_commit_list(dreq
->inode
, &reqs
, &cinfo
);
517 nfs_direct_join_group(&reqs
, dreq
->inode
);
521 list_for_each_entry(req
, &reqs
, wb_list
)
522 dreq
->max_count
+= req
->wb_bytes
;
523 nfs_clear_pnfs_ds_commit_verifiers(&dreq
->ds_cinfo
);
526 nfs_pageio_init_write(&desc
, dreq
->inode
, FLUSH_STABLE
, false,
527 &nfs_direct_write_completion_ops
);
530 list_for_each_entry_safe(req
, tmp
, &reqs
, wb_list
) {
531 /* Bump the transmission count */
533 if (!nfs_pageio_add_request(&desc
, req
)) {
534 nfs_list_move_request(req
, &failed
);
535 spin_lock(&cinfo
.inode
->i_lock
);
537 if (desc
.pg_error
< 0)
538 dreq
->error
= desc
.pg_error
;
541 spin_unlock(&cinfo
.inode
->i_lock
);
543 nfs_release_request(req
);
545 nfs_pageio_complete(&desc
);
547 while (!list_empty(&failed
)) {
548 req
= nfs_list_entry(failed
.next
);
549 nfs_list_remove_request(req
);
550 nfs_unlock_and_release_request(req
);
554 nfs_direct_write_complete(dreq
);
557 static void nfs_direct_commit_complete(struct nfs_commit_data
*data
)
559 const struct nfs_writeverf
*verf
= data
->res
.verf
;
560 struct nfs_direct_req
*dreq
= data
->dreq
;
561 struct nfs_commit_info cinfo
;
562 struct nfs_page
*req
;
563 int status
= data
->task
.tk_status
;
565 trace_nfs_direct_commit_complete(dreq
);
568 /* Errors in commit are fatal */
569 dreq
->error
= status
;
572 dreq
->flags
= NFS_ODIRECT_DONE
;
574 status
= dreq
->error
;
577 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
579 while (!list_empty(&data
->pages
)) {
580 req
= nfs_list_entry(data
->pages
.next
);
581 nfs_list_remove_request(req
);
582 if (status
>= 0 && !nfs_write_match_verf(verf
, req
)) {
583 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
585 * Despite the reboot, the write was successful,
589 nfs_mark_request_commit(req
, NULL
, &cinfo
, 0);
590 } else /* Error or match */
591 nfs_release_request(req
);
592 nfs_unlock_and_release_request(req
);
595 if (nfs_commit_end(cinfo
.mds
))
596 nfs_direct_write_complete(dreq
);
599 static void nfs_direct_resched_write(struct nfs_commit_info
*cinfo
,
600 struct nfs_page
*req
)
602 struct nfs_direct_req
*dreq
= cinfo
->dreq
;
604 trace_nfs_direct_resched_write(dreq
);
606 spin_lock(&dreq
->lock
);
607 if (dreq
->flags
!= NFS_ODIRECT_DONE
)
608 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
609 spin_unlock(&dreq
->lock
);
610 nfs_mark_request_commit(req
, NULL
, cinfo
, 0);
613 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
= {
614 .completion
= nfs_direct_commit_complete
,
615 .resched_write
= nfs_direct_resched_write
,
618 static void nfs_direct_commit_schedule(struct nfs_direct_req
*dreq
)
621 struct nfs_commit_info cinfo
;
624 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
625 nfs_scan_commit(dreq
->inode
, &mds_list
, &cinfo
);
626 res
= nfs_generic_commit_list(dreq
->inode
, &mds_list
, 0, &cinfo
);
627 if (res
< 0) /* res == -ENOMEM */
628 nfs_direct_write_reschedule(dreq
);
631 static void nfs_direct_write_clear_reqs(struct nfs_direct_req
*dreq
)
633 struct nfs_commit_info cinfo
;
634 struct nfs_page
*req
;
637 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
638 nfs_direct_write_scan_commit_list(dreq
->inode
, &reqs
, &cinfo
);
640 while (!list_empty(&reqs
)) {
641 req
= nfs_list_entry(reqs
.next
);
642 nfs_list_remove_request(req
);
643 nfs_release_request(req
);
644 nfs_unlock_and_release_request(req
);
648 static void nfs_direct_write_schedule_work(struct work_struct
*work
)
650 struct nfs_direct_req
*dreq
= container_of(work
, struct nfs_direct_req
, work
);
651 int flags
= dreq
->flags
;
655 case NFS_ODIRECT_DO_COMMIT
:
656 nfs_direct_commit_schedule(dreq
);
658 case NFS_ODIRECT_RESCHED_WRITES
:
659 nfs_direct_write_reschedule(dreq
);
662 nfs_direct_write_clear_reqs(dreq
);
663 nfs_zap_mapping(dreq
->inode
, dreq
->inode
->i_mapping
);
664 nfs_direct_complete(dreq
);
668 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
)
670 trace_nfs_direct_write_complete(dreq
);
671 queue_work(nfsiod_workqueue
, &dreq
->work
); /* Calls nfs_direct_write_schedule_work */
674 static void nfs_direct_write_completion(struct nfs_pgio_header
*hdr
)
676 struct nfs_direct_req
*dreq
= hdr
->dreq
;
677 struct nfs_commit_info cinfo
;
678 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
679 int flags
= NFS_ODIRECT_DONE
;
681 trace_nfs_direct_write_completion(dreq
);
683 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
685 spin_lock(&dreq
->lock
);
686 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
)) {
687 spin_unlock(&dreq
->lock
);
691 nfs_direct_count_bytes(dreq
, hdr
);
692 if (test_bit(NFS_IOHDR_UNSTABLE_WRITES
, &hdr
->flags
)) {
694 dreq
->flags
= NFS_ODIRECT_DO_COMMIT
;
697 spin_unlock(&dreq
->lock
);
699 while (!list_empty(&hdr
->pages
)) {
701 req
= nfs_list_entry(hdr
->pages
.next
);
702 nfs_list_remove_request(req
);
703 if (flags
== NFS_ODIRECT_DO_COMMIT
) {
704 kref_get(&req
->wb_kref
);
705 memcpy(&req
->wb_verf
, &hdr
->verf
.verifier
,
706 sizeof(req
->wb_verf
));
707 nfs_mark_request_commit(req
, hdr
->lseg
, &cinfo
,
709 } else if (flags
== NFS_ODIRECT_RESCHED_WRITES
) {
710 kref_get(&req
->wb_kref
);
711 nfs_mark_request_commit(req
, NULL
, &cinfo
, 0);
713 nfs_unlock_and_release_request(req
);
718 nfs_direct_write_complete(dreq
);
722 static void nfs_write_sync_pgio_error(struct list_head
*head
, int error
)
724 struct nfs_page
*req
;
726 while (!list_empty(head
)) {
727 req
= nfs_list_entry(head
->next
);
728 nfs_list_remove_request(req
);
729 nfs_unlock_and_release_request(req
);
733 static void nfs_direct_write_reschedule_io(struct nfs_pgio_header
*hdr
)
735 struct nfs_direct_req
*dreq
= hdr
->dreq
;
737 trace_nfs_direct_write_reschedule_io(dreq
);
739 spin_lock(&dreq
->lock
);
740 if (dreq
->error
== 0) {
741 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
742 /* fake unstable write to let common nfs resend pages */
743 hdr
->verf
.committed
= NFS_UNSTABLE
;
744 hdr
->good_bytes
= hdr
->args
.offset
+ hdr
->args
.count
-
747 spin_unlock(&dreq
->lock
);
750 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
= {
751 .error_cleanup
= nfs_write_sync_pgio_error
,
752 .init_hdr
= nfs_direct_pgio_init
,
753 .completion
= nfs_direct_write_completion
,
754 .reschedule_io
= nfs_direct_write_reschedule_io
,
759 * NB: Return the value of the first error return code. Subsequent
760 * errors after the first one are ignored.
763 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
764 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
765 * bail and stop sending more writes. Write length accounting is
766 * handled automatically by nfs_direct_write_result(). Otherwise, if
767 * no requests have been sent, just return an error.
769 static ssize_t
nfs_direct_write_schedule_iovec(struct nfs_direct_req
*dreq
,
770 struct iov_iter
*iter
,
771 loff_t pos
, int ioflags
)
773 struct nfs_pageio_descriptor desc
;
774 struct inode
*inode
= dreq
->inode
;
776 size_t requested_bytes
= 0;
777 size_t wsize
= max_t(size_t, NFS_SERVER(inode
)->wsize
, PAGE_SIZE
);
779 trace_nfs_direct_write_schedule_iovec(dreq
);
781 nfs_pageio_init_write(&desc
, inode
, ioflags
, false,
782 &nfs_direct_write_completion_ops
);
785 inode_dio_begin(inode
);
787 NFS_I(inode
)->write_io
+= iov_iter_count(iter
);
788 while (iov_iter_count(iter
)) {
789 struct page
**pagevec
;
794 result
= iov_iter_get_pages_alloc2(iter
, &pagevec
,
800 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
801 for (i
= 0; i
< npages
; i
++) {
802 struct nfs_page
*req
;
803 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
805 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
],
808 result
= PTR_ERR(req
);
812 if (desc
.pg_error
< 0) {
813 nfs_free_request(req
);
814 result
= desc
.pg_error
;
818 nfs_lock_request(req
);
819 req
->wb_index
= pos
>> PAGE_SHIFT
;
820 req
->wb_offset
= pos
& ~PAGE_MASK
;
821 if (!nfs_pageio_add_request(&desc
, req
)) {
822 result
= desc
.pg_error
;
823 nfs_unlock_and_release_request(req
);
828 requested_bytes
+= req_len
;
830 dreq
->bytes_left
-= req_len
;
832 nfs_direct_release_pages(pagevec
, npages
);
837 nfs_pageio_complete(&desc
);
840 * If no bytes were started, return the error, and let the
841 * generic layer handle the completion.
843 if (requested_bytes
== 0) {
844 inode_dio_end(inode
);
845 nfs_direct_req_release(dreq
);
846 return result
< 0 ? result
: -EIO
;
850 nfs_direct_write_complete(dreq
);
851 return requested_bytes
;
855 * nfs_file_direct_write - file direct write operation for NFS files
856 * @iocb: target I/O control block
857 * @iter: vector of user buffers from which to write data
858 * @swap: flag indicating this is swap IO, not O_DIRECT IO
860 * We use this function for direct writes instead of calling
861 * generic_file_aio_write() in order to avoid taking the inode
862 * semaphore and updating the i_size. The NFS server will set
863 * the new i_size and this client must read the updated size
864 * back into its cache. We let the server do generic write
865 * parameter checking and report problems.
867 * We eliminate local atime updates, see direct read above.
869 * We avoid unnecessary page cache invalidations for normal cached
870 * readers of this file.
872 * Note that O_APPEND is not supported for NFS direct writes, as there
873 * is no atomic O_APPEND write facility in the NFS protocol.
875 ssize_t
nfs_file_direct_write(struct kiocb
*iocb
, struct iov_iter
*iter
,
878 ssize_t result
, requested
;
880 struct file
*file
= iocb
->ki_filp
;
881 struct address_space
*mapping
= file
->f_mapping
;
882 struct inode
*inode
= mapping
->host
;
883 struct nfs_direct_req
*dreq
;
884 struct nfs_lock_context
*l_ctx
;
887 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
888 file
, iov_iter_count(iter
), (long long) iocb
->ki_pos
);
891 /* bypass generic checks */
892 result
= iov_iter_count(iter
);
894 result
= generic_write_checks(iocb
, iter
);
898 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTWRITTENBYTES
, count
);
901 end
= (pos
+ iov_iter_count(iter
) - 1) >> PAGE_SHIFT
;
903 task_io_account_write(count
);
906 dreq
= nfs_direct_req_alloc();
911 dreq
->bytes_left
= dreq
->max_count
= count
;
912 dreq
->io_start
= pos
;
913 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
914 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
916 result
= PTR_ERR(l_ctx
);
917 nfs_direct_req_release(dreq
);
921 if (!is_sync_kiocb(iocb
))
923 pnfs_init_ds_commit_info_ops(&dreq
->ds_cinfo
, inode
);
926 requested
= nfs_direct_write_schedule_iovec(dreq
, iter
, pos
,
929 nfs_start_io_direct(inode
);
931 requested
= nfs_direct_write_schedule_iovec(dreq
, iter
, pos
,
934 if (mapping
->nrpages
) {
935 invalidate_inode_pages2_range(mapping
,
936 pos
>> PAGE_SHIFT
, end
);
939 nfs_end_io_direct(inode
);
943 result
= nfs_direct_wait(dreq
);
946 iocb
->ki_pos
= pos
+ result
;
947 /* XXX: should check the generic_write_sync retval */
948 generic_write_sync(iocb
, result
);
950 iov_iter_revert(iter
, requested
);
954 nfs_fscache_invalidate(inode
, FSCACHE_INVAL_DIO_WRITE
);
956 nfs_direct_req_release(dreq
);
962 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
965 int __init
nfs_init_directcache(void)
967 nfs_direct_cachep
= kmem_cache_create("nfs_direct_cache",
968 sizeof(struct nfs_direct_req
),
969 0, (SLAB_RECLAIM_ACCOUNT
|
972 if (nfs_direct_cachep
== NULL
)
979 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
982 void nfs_destroy_directcache(void)
984 kmem_cache_destroy(nfs_direct_cachep
);