2 * linux/fs/nfs/direct.c
4 * Copyright (C) 2003 by Chuck Lever <cel@netapp.com>
6 * High-performance uncached I/O for the Linux NFS client
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.
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
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.
29 * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with
30 * help from Andrew Morton.
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
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>
51 #include <linux/nfs_fs.h>
52 #include <linux/nfs_page.h>
53 #include <linux/sunrpc/clnt.h>
55 #include <asm/uaccess.h>
56 #include <linux/atomic.h>
62 #define NFSDBG_FACILITY NFSDBG_VFS
64 static struct kmem_cache
*nfs_direct_cachep
;
67 * This represents a set of asynchronous requests that we're waiting on
69 struct nfs_direct_req
{
70 struct kref kref
; /* release manager */
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 */
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 */
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
;
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 */
96 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
;
97 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
;
98 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
, struct inode
*inode
);
99 static void nfs_direct_write_schedule_work(struct work_struct
*work
);
101 static inline void get_dreq(struct nfs_direct_req
*dreq
)
103 atomic_inc(&dreq
->io_count
);
106 static inline int put_dreq(struct nfs_direct_req
*dreq
)
108 return atomic_dec_and_test(&dreq
->io_count
);
112 * nfs_direct_select_verf - select the right verifier
113 * @dreq - direct request possibly spanning multiple servers
114 * @ds_clp - nfs_client of data server or NULL if MDS / non-pnfs
115 * @ds_idx - index of data server in data server list, only valid if ds_clp set
117 * returns the correct verifier to use given the role of the server
119 static struct nfs_writeverf
*
120 nfs_direct_select_verf(struct nfs_direct_req
*dreq
,
121 struct nfs_client
*ds_clp
,
124 struct nfs_writeverf
*verfp
= &dreq
->verf
;
126 #ifdef CONFIG_NFS_V4_1
128 /* pNFS is in use, use the DS verf */
129 if (ds_idx
>= 0 && ds_idx
< dreq
->ds_cinfo
.nbuckets
)
130 verfp
= &dreq
->ds_cinfo
.buckets
[ds_idx
].direct_verf
;
140 * nfs_direct_set_hdr_verf - set the write/commit verifier
141 * @dreq - direct request possibly spanning multiple servers
142 * @hdr - pageio header to validate against previously seen verfs
144 * Set the server's (MDS or DS) "seen" verifier
146 static void nfs_direct_set_hdr_verf(struct nfs_direct_req
*dreq
,
147 struct nfs_pgio_header
*hdr
)
149 struct nfs_writeverf
*verfp
;
151 verfp
= nfs_direct_select_verf(dreq
, hdr
->ds_clp
,
153 WARN_ON_ONCE(verfp
->committed
>= 0);
154 memcpy(verfp
, &hdr
->verf
, sizeof(struct nfs_writeverf
));
155 WARN_ON_ONCE(verfp
->committed
< 0);
159 * nfs_direct_cmp_hdr_verf - compare verifier for pgio header
160 * @dreq - direct request possibly spanning multiple servers
161 * @hdr - pageio header to validate against previously seen verf
163 * set the server's "seen" verf if not initialized.
164 * returns result of comparison between @hdr->verf and the "seen"
165 * verf of the server used by @hdr (DS or MDS)
167 static int nfs_direct_set_or_cmp_hdr_verf(struct nfs_direct_req
*dreq
,
168 struct nfs_pgio_header
*hdr
)
170 struct nfs_writeverf
*verfp
;
172 verfp
= nfs_direct_select_verf(dreq
, hdr
->ds_clp
,
174 if (verfp
->committed
< 0) {
175 nfs_direct_set_hdr_verf(dreq
, hdr
);
178 return memcmp(verfp
, &hdr
->verf
, sizeof(struct nfs_writeverf
));
182 * nfs_direct_cmp_commit_data_verf - compare verifier for commit data
183 * @dreq - direct request possibly spanning multiple servers
184 * @data - commit data to validate against previously seen verf
186 * returns result of comparison between @data->verf and the verf of
187 * the server used by @data (DS or MDS)
189 static int nfs_direct_cmp_commit_data_verf(struct nfs_direct_req
*dreq
,
190 struct nfs_commit_data
*data
)
192 struct nfs_writeverf
*verfp
;
194 verfp
= nfs_direct_select_verf(dreq
, data
->ds_clp
,
195 data
->ds_commit_index
);
196 WARN_ON_ONCE(verfp
->committed
< 0);
197 return memcmp(verfp
, &data
->verf
, sizeof(struct nfs_writeverf
));
201 * nfs_direct_IO - NFS address space operation for direct I/O
202 * @rw: direction (read or write)
203 * @iocb: target I/O control block
204 * @iov: array of vectors that define I/O buffer
205 * @pos: offset in file to begin the operation
206 * @nr_segs: size of iovec array
208 * The presence of this routine in the address space ops vector means
209 * the NFS client supports direct I/O. However, for most direct IO, we
210 * shunt off direct read and write requests before the VFS gets them,
211 * so this method is only ever called for swap.
213 ssize_t
nfs_direct_IO(int rw
, struct kiocb
*iocb
, struct iov_iter
*iter
, loff_t pos
)
215 #ifndef CONFIG_NFS_SWAP
216 dprintk("NFS: nfs_direct_IO (%pD) off/no(%Ld/%lu) EINVAL\n",
217 iocb
->ki_filp
, (long long) pos
, iter
->nr_segs
);
221 VM_BUG_ON(iocb
->ki_nbytes
!= PAGE_SIZE
);
224 return nfs_file_direct_read(iocb
, iter
, pos
);
225 return nfs_file_direct_write(iocb
, iter
, pos
);
226 #endif /* CONFIG_NFS_SWAP */
229 static void nfs_direct_release_pages(struct page
**pages
, unsigned int npages
)
232 for (i
= 0; i
< npages
; i
++)
233 page_cache_release(pages
[i
]);
236 void nfs_init_cinfo_from_dreq(struct nfs_commit_info
*cinfo
,
237 struct nfs_direct_req
*dreq
)
239 cinfo
->lock
= &dreq
->lock
;
240 cinfo
->mds
= &dreq
->mds_cinfo
;
241 cinfo
->ds
= &dreq
->ds_cinfo
;
243 cinfo
->completion_ops
= &nfs_direct_commit_completion_ops
;
246 static inline struct nfs_direct_req
*nfs_direct_req_alloc(void)
248 struct nfs_direct_req
*dreq
;
250 dreq
= kmem_cache_zalloc(nfs_direct_cachep
, GFP_KERNEL
);
254 kref_init(&dreq
->kref
);
255 kref_get(&dreq
->kref
);
256 init_completion(&dreq
->completion
);
257 INIT_LIST_HEAD(&dreq
->mds_cinfo
.list
);
258 dreq
->verf
.committed
= NFS_INVALID_STABLE_HOW
; /* not set yet */
259 INIT_WORK(&dreq
->work
, nfs_direct_write_schedule_work
);
260 spin_lock_init(&dreq
->lock
);
265 static void nfs_direct_req_free(struct kref
*kref
)
267 struct nfs_direct_req
*dreq
= container_of(kref
, struct nfs_direct_req
, kref
);
269 nfs_free_pnfs_ds_cinfo(&dreq
->ds_cinfo
);
270 if (dreq
->l_ctx
!= NULL
)
271 nfs_put_lock_context(dreq
->l_ctx
);
272 if (dreq
->ctx
!= NULL
)
273 put_nfs_open_context(dreq
->ctx
);
274 kmem_cache_free(nfs_direct_cachep
, dreq
);
277 static void nfs_direct_req_release(struct nfs_direct_req
*dreq
)
279 kref_put(&dreq
->kref
, nfs_direct_req_free
);
282 ssize_t
nfs_dreq_bytes_left(struct nfs_direct_req
*dreq
)
284 return dreq
->bytes_left
;
286 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left
);
289 * Collects and returns the final error value/byte-count.
291 static ssize_t
nfs_direct_wait(struct nfs_direct_req
*dreq
)
293 ssize_t result
= -EIOCBQUEUED
;
295 /* Async requests don't wait here */
299 result
= wait_for_completion_killable(&dreq
->completion
);
302 result
= dreq
->error
;
304 result
= dreq
->count
;
307 return (ssize_t
) result
;
311 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
312 * the iocb is still valid here if this is a synchronous request.
314 static void nfs_direct_complete(struct nfs_direct_req
*dreq
, bool write
)
316 struct inode
*inode
= dreq
->inode
;
318 if (dreq
->iocb
&& write
) {
319 loff_t pos
= dreq
->iocb
->ki_pos
+ dreq
->count
;
321 spin_lock(&inode
->i_lock
);
322 if (i_size_read(inode
) < pos
)
323 i_size_write(inode
, pos
);
324 spin_unlock(&inode
->i_lock
);
328 nfs_zap_mapping(inode
, inode
->i_mapping
);
330 inode_dio_done(inode
);
333 long res
= (long) dreq
->error
;
335 res
= (long) dreq
->count
;
336 aio_complete(dreq
->iocb
, res
, 0);
339 complete_all(&dreq
->completion
);
341 nfs_direct_req_release(dreq
);
344 static void nfs_direct_readpage_release(struct nfs_page
*req
)
346 dprintk("NFS: direct read done (%s/%llu %d@%lld)\n",
347 req
->wb_context
->dentry
->d_inode
->i_sb
->s_id
,
348 (unsigned long long)NFS_FILEID(req
->wb_context
->dentry
->d_inode
),
350 (long long)req_offset(req
));
351 nfs_release_request(req
);
354 static void nfs_direct_read_completion(struct nfs_pgio_header
*hdr
)
356 unsigned long bytes
= 0;
357 struct nfs_direct_req
*dreq
= hdr
->dreq
;
359 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
362 spin_lock(&dreq
->lock
);
363 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
) && (hdr
->good_bytes
== 0))
364 dreq
->error
= hdr
->error
;
366 dreq
->count
+= hdr
->good_bytes
;
367 spin_unlock(&dreq
->lock
);
369 while (!list_empty(&hdr
->pages
)) {
370 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
371 struct page
*page
= req
->wb_page
;
373 if (!PageCompound(page
) && bytes
< hdr
->good_bytes
)
374 set_page_dirty(page
);
375 bytes
+= req
->wb_bytes
;
376 nfs_list_remove_request(req
);
377 nfs_direct_readpage_release(req
);
381 nfs_direct_complete(dreq
, false);
385 static void nfs_read_sync_pgio_error(struct list_head
*head
)
387 struct nfs_page
*req
;
389 while (!list_empty(head
)) {
390 req
= nfs_list_entry(head
->next
);
391 nfs_list_remove_request(req
);
392 nfs_release_request(req
);
396 static void nfs_direct_pgio_init(struct nfs_pgio_header
*hdr
)
401 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops
= {
402 .error_cleanup
= nfs_read_sync_pgio_error
,
403 .init_hdr
= nfs_direct_pgio_init
,
404 .completion
= nfs_direct_read_completion
,
408 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
409 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
410 * bail and stop sending more reads. Read length accounting is
411 * handled automatically by nfs_direct_read_result(). Otherwise, if
412 * no requests have been sent, just return an error.
415 static ssize_t
nfs_direct_read_schedule_iovec(struct nfs_direct_req
*dreq
,
416 struct iov_iter
*iter
,
419 struct nfs_pageio_descriptor desc
;
420 struct inode
*inode
= dreq
->inode
;
421 ssize_t result
= -EINVAL
;
422 size_t requested_bytes
= 0;
423 size_t rsize
= max_t(size_t, NFS_SERVER(inode
)->rsize
, PAGE_SIZE
);
425 nfs_pageio_init_read(&desc
, dreq
->inode
, false,
426 &nfs_direct_read_completion_ops
);
429 atomic_inc(&inode
->i_dio_count
);
431 while (iov_iter_count(iter
)) {
432 struct page
**pagevec
;
437 result
= iov_iter_get_pages_alloc(iter
, &pagevec
,
443 iov_iter_advance(iter
, bytes
);
444 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
445 for (i
= 0; i
< npages
; i
++) {
446 struct nfs_page
*req
;
447 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
448 /* XXX do we need to do the eof zeroing found in async_filler? */
449 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
], NULL
,
452 result
= PTR_ERR(req
);
455 req
->wb_index
= pos
>> PAGE_SHIFT
;
456 req
->wb_offset
= pos
& ~PAGE_MASK
;
457 if (!nfs_pageio_add_request(&desc
, req
)) {
458 result
= desc
.pg_error
;
459 nfs_release_request(req
);
464 requested_bytes
+= req_len
;
466 dreq
->bytes_left
-= req_len
;
468 nfs_direct_release_pages(pagevec
, npages
);
474 nfs_pageio_complete(&desc
);
477 * If no bytes were started, return the error, and let the
478 * generic layer handle the completion.
480 if (requested_bytes
== 0) {
481 inode_dio_done(inode
);
482 nfs_direct_req_release(dreq
);
483 return result
< 0 ? result
: -EIO
;
487 nfs_direct_complete(dreq
, false);
492 * nfs_file_direct_read - file direct read operation for NFS files
493 * @iocb: target I/O control block
494 * @iter: vector of user buffers into which to read data
495 * @pos: byte offset in file where reading starts
497 * We use this function for direct reads instead of calling
498 * generic_file_aio_read() in order to avoid gfar's check to see if
499 * the request starts before the end of the file. For that check
500 * to work, we must generate a GETATTR before each direct read, and
501 * even then there is a window between the GETATTR and the subsequent
502 * READ where the file size could change. Our preference is simply
503 * to do all reads the application wants, and the server will take
504 * care of managing the end of file boundary.
506 * This function also eliminates unnecessarily updating the file's
507 * atime locally, as the NFS server sets the file's atime, and this
508 * client must read the updated atime from the server back into its
511 ssize_t
nfs_file_direct_read(struct kiocb
*iocb
, struct iov_iter
*iter
,
514 struct file
*file
= iocb
->ki_filp
;
515 struct address_space
*mapping
= file
->f_mapping
;
516 struct inode
*inode
= mapping
->host
;
517 struct nfs_direct_req
*dreq
;
518 struct nfs_lock_context
*l_ctx
;
519 ssize_t result
= -EINVAL
;
520 size_t count
= iov_iter_count(iter
);
521 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTREADBYTES
, count
);
523 dfprintk(FILE, "NFS: direct read(%pD2, %zd@%Ld)\n",
524 file
, count
, (long long) pos
);
530 mutex_lock(&inode
->i_mutex
);
531 result
= nfs_sync_mapping(mapping
);
535 task_io_account_read(count
);
538 dreq
= nfs_direct_req_alloc();
543 dreq
->bytes_left
= count
;
544 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
545 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
547 result
= PTR_ERR(l_ctx
);
551 if (!is_sync_kiocb(iocb
))
554 NFS_I(inode
)->read_io
+= count
;
555 result
= nfs_direct_read_schedule_iovec(dreq
, iter
, pos
);
557 mutex_unlock(&inode
->i_mutex
);
560 result
= nfs_direct_wait(dreq
);
562 iocb
->ki_pos
= pos
+ result
;
565 nfs_direct_req_release(dreq
);
569 nfs_direct_req_release(dreq
);
571 mutex_unlock(&inode
->i_mutex
);
576 static void nfs_direct_write_reschedule(struct nfs_direct_req
*dreq
)
578 struct nfs_pageio_descriptor desc
;
579 struct nfs_page
*req
, *tmp
;
581 struct nfs_commit_info cinfo
;
584 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
585 pnfs_recover_commit_reqs(dreq
->inode
, &reqs
, &cinfo
);
586 spin_lock(cinfo
.lock
);
587 nfs_scan_commit_list(&cinfo
.mds
->list
, &reqs
, &cinfo
, 0);
588 spin_unlock(cinfo
.lock
);
593 nfs_pageio_init_write(&desc
, dreq
->inode
, FLUSH_STABLE
, false,
594 &nfs_direct_write_completion_ops
);
597 list_for_each_entry_safe(req
, tmp
, &reqs
, wb_list
) {
598 if (!nfs_pageio_add_request(&desc
, req
)) {
599 nfs_list_remove_request(req
);
600 nfs_list_add_request(req
, &failed
);
601 spin_lock(cinfo
.lock
);
604 spin_unlock(cinfo
.lock
);
606 nfs_release_request(req
);
608 nfs_pageio_complete(&desc
);
610 while (!list_empty(&failed
)) {
611 req
= nfs_list_entry(failed
.next
);
612 nfs_list_remove_request(req
);
613 nfs_unlock_and_release_request(req
);
617 nfs_direct_write_complete(dreq
, dreq
->inode
);
620 static void nfs_direct_commit_complete(struct nfs_commit_data
*data
)
622 struct nfs_direct_req
*dreq
= data
->dreq
;
623 struct nfs_commit_info cinfo
;
624 struct nfs_page
*req
;
625 int status
= data
->task
.tk_status
;
627 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
629 dprintk("NFS: %5u commit failed with error %d.\n",
630 data
->task
.tk_pid
, status
);
631 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
632 } else if (nfs_direct_cmp_commit_data_verf(dreq
, data
)) {
633 dprintk("NFS: %5u commit verify failed\n", data
->task
.tk_pid
);
634 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
637 dprintk("NFS: %5u commit returned %d\n", data
->task
.tk_pid
, status
);
638 while (!list_empty(&data
->pages
)) {
639 req
= nfs_list_entry(data
->pages
.next
);
640 nfs_list_remove_request(req
);
641 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
) {
642 /* Note the rewrite will go through mds */
643 nfs_mark_request_commit(req
, NULL
, &cinfo
);
645 nfs_release_request(req
);
646 nfs_unlock_and_release_request(req
);
649 if (atomic_dec_and_test(&cinfo
.mds
->rpcs_out
))
650 nfs_direct_write_complete(dreq
, data
->inode
);
653 static void nfs_direct_error_cleanup(struct nfs_inode
*nfsi
)
655 /* There is no lock to clear */
658 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
= {
659 .completion
= nfs_direct_commit_complete
,
660 .error_cleanup
= nfs_direct_error_cleanup
,
663 static void nfs_direct_commit_schedule(struct nfs_direct_req
*dreq
)
666 struct nfs_commit_info cinfo
;
669 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
670 nfs_scan_commit(dreq
->inode
, &mds_list
, &cinfo
);
671 res
= nfs_generic_commit_list(dreq
->inode
, &mds_list
, 0, &cinfo
);
672 if (res
< 0) /* res == -ENOMEM */
673 nfs_direct_write_reschedule(dreq
);
676 static void nfs_direct_write_schedule_work(struct work_struct
*work
)
678 struct nfs_direct_req
*dreq
= container_of(work
, struct nfs_direct_req
, work
);
679 int flags
= dreq
->flags
;
683 case NFS_ODIRECT_DO_COMMIT
:
684 nfs_direct_commit_schedule(dreq
);
686 case NFS_ODIRECT_RESCHED_WRITES
:
687 nfs_direct_write_reschedule(dreq
);
690 nfs_direct_complete(dreq
, true);
694 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
, struct inode
*inode
)
696 schedule_work(&dreq
->work
); /* Calls nfs_direct_write_schedule_work */
699 static void nfs_direct_write_completion(struct nfs_pgio_header
*hdr
)
701 struct nfs_direct_req
*dreq
= hdr
->dreq
;
702 struct nfs_commit_info cinfo
;
703 bool request_commit
= false;
704 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
706 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
709 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
711 spin_lock(&dreq
->lock
);
713 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
)) {
715 dreq
->error
= hdr
->error
;
717 if (dreq
->error
== 0) {
718 dreq
->count
+= hdr
->good_bytes
;
719 if (nfs_write_need_commit(hdr
)) {
720 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
)
721 request_commit
= true;
722 else if (dreq
->flags
== 0) {
723 nfs_direct_set_hdr_verf(dreq
, hdr
);
724 request_commit
= true;
725 dreq
->flags
= NFS_ODIRECT_DO_COMMIT
;
726 } else if (dreq
->flags
== NFS_ODIRECT_DO_COMMIT
) {
727 request_commit
= true;
728 if (nfs_direct_set_or_cmp_hdr_verf(dreq
, hdr
))
730 NFS_ODIRECT_RESCHED_WRITES
;
734 spin_unlock(&dreq
->lock
);
736 while (!list_empty(&hdr
->pages
)) {
738 req
= nfs_list_entry(hdr
->pages
.next
);
739 nfs_list_remove_request(req
);
740 if (request_commit
) {
741 kref_get(&req
->wb_kref
);
742 nfs_mark_request_commit(req
, hdr
->lseg
, &cinfo
);
744 nfs_unlock_and_release_request(req
);
749 nfs_direct_write_complete(dreq
, hdr
->inode
);
753 static void nfs_write_sync_pgio_error(struct list_head
*head
)
755 struct nfs_page
*req
;
757 while (!list_empty(head
)) {
758 req
= nfs_list_entry(head
->next
);
759 nfs_list_remove_request(req
);
760 nfs_unlock_and_release_request(req
);
764 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
= {
765 .error_cleanup
= nfs_write_sync_pgio_error
,
766 .init_hdr
= nfs_direct_pgio_init
,
767 .completion
= nfs_direct_write_completion
,
772 * NB: Return the value of the first error return code. Subsequent
773 * errors after the first one are ignored.
776 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
777 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
778 * bail and stop sending more writes. Write length accounting is
779 * handled automatically by nfs_direct_write_result(). Otherwise, if
780 * no requests have been sent, just return an error.
782 static ssize_t
nfs_direct_write_schedule_iovec(struct nfs_direct_req
*dreq
,
783 struct iov_iter
*iter
,
786 struct nfs_pageio_descriptor desc
;
787 struct inode
*inode
= dreq
->inode
;
789 size_t requested_bytes
= 0;
790 size_t wsize
= max_t(size_t, NFS_SERVER(inode
)->wsize
, PAGE_SIZE
);
792 nfs_pageio_init_write(&desc
, inode
, FLUSH_COND_STABLE
, false,
793 &nfs_direct_write_completion_ops
);
796 atomic_inc(&inode
->i_dio_count
);
798 NFS_I(inode
)->write_io
+= iov_iter_count(iter
);
799 while (iov_iter_count(iter
)) {
800 struct page
**pagevec
;
805 result
= iov_iter_get_pages_alloc(iter
, &pagevec
,
811 iov_iter_advance(iter
, bytes
);
812 npages
= (result
+ pgbase
+ PAGE_SIZE
- 1) / PAGE_SIZE
;
813 for (i
= 0; i
< npages
; i
++) {
814 struct nfs_page
*req
;
815 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
817 req
= nfs_create_request(dreq
->ctx
, pagevec
[i
], NULL
,
820 result
= PTR_ERR(req
);
823 nfs_lock_request(req
);
824 req
->wb_index
= pos
>> PAGE_SHIFT
;
825 req
->wb_offset
= pos
& ~PAGE_MASK
;
826 if (!nfs_pageio_add_request(&desc
, req
)) {
827 result
= desc
.pg_error
;
828 nfs_unlock_and_release_request(req
);
833 requested_bytes
+= req_len
;
835 dreq
->bytes_left
-= req_len
;
837 nfs_direct_release_pages(pagevec
, npages
);
842 nfs_pageio_complete(&desc
);
845 * If no bytes were started, return the error, and let the
846 * generic layer handle the completion.
848 if (requested_bytes
== 0) {
849 inode_dio_done(inode
);
850 nfs_direct_req_release(dreq
);
851 return result
< 0 ? result
: -EIO
;
855 nfs_direct_write_complete(dreq
, dreq
->inode
);
860 * nfs_file_direct_write - file direct write operation for NFS files
861 * @iocb: target I/O control block
862 * @iter: vector of user buffers from which to write data
863 * @pos: byte offset in file where writing starts
865 * We use this function for direct writes instead of calling
866 * generic_file_aio_write() in order to avoid taking the inode
867 * semaphore and updating the i_size. The NFS server will set
868 * the new i_size and this client must read the updated size
869 * back into its cache. We let the server do generic write
870 * parameter checking and report problems.
872 * We eliminate local atime updates, see direct read above.
874 * We avoid unnecessary page cache invalidations for normal cached
875 * readers of this file.
877 * Note that O_APPEND is not supported for NFS direct writes, as there
878 * is no atomic O_APPEND write facility in the NFS protocol.
880 ssize_t
nfs_file_direct_write(struct kiocb
*iocb
, struct iov_iter
*iter
,
883 ssize_t result
= -EINVAL
;
884 struct file
*file
= iocb
->ki_filp
;
885 struct address_space
*mapping
= file
->f_mapping
;
886 struct inode
*inode
= mapping
->host
;
887 struct nfs_direct_req
*dreq
;
888 struct nfs_lock_context
*l_ctx
;
890 size_t count
= iov_iter_count(iter
);
891 end
= (pos
+ count
- 1) >> PAGE_CACHE_SHIFT
;
893 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTWRITTENBYTES
, count
);
895 dfprintk(FILE, "NFS: direct write(%pD2, %zd@%Ld)\n",
896 file
, count
, (long long) pos
);
898 result
= generic_write_checks(file
, &pos
, &count
, 0);
903 if ((ssize_t
) count
< 0)
909 mutex_lock(&inode
->i_mutex
);
911 result
= nfs_sync_mapping(mapping
);
915 if (mapping
->nrpages
) {
916 result
= invalidate_inode_pages2_range(mapping
,
917 pos
>> PAGE_CACHE_SHIFT
, end
);
922 task_io_account_write(count
);
925 dreq
= nfs_direct_req_alloc();
930 dreq
->bytes_left
= count
;
931 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
932 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
934 result
= PTR_ERR(l_ctx
);
938 if (!is_sync_kiocb(iocb
))
941 result
= nfs_direct_write_schedule_iovec(dreq
, iter
, pos
);
943 if (mapping
->nrpages
) {
944 invalidate_inode_pages2_range(mapping
,
945 pos
>> PAGE_CACHE_SHIFT
, end
);
948 mutex_unlock(&inode
->i_mutex
);
951 result
= nfs_direct_wait(dreq
);
953 struct inode
*inode
= mapping
->host
;
955 iocb
->ki_pos
= pos
+ result
;
956 spin_lock(&inode
->i_lock
);
957 if (i_size_read(inode
) < iocb
->ki_pos
)
958 i_size_write(inode
, iocb
->ki_pos
);
959 spin_unlock(&inode
->i_lock
);
962 nfs_direct_req_release(dreq
);
966 nfs_direct_req_release(dreq
);
968 mutex_unlock(&inode
->i_mutex
);
974 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
977 int __init
nfs_init_directcache(void)
979 nfs_direct_cachep
= kmem_cache_create("nfs_direct_cache",
980 sizeof(struct nfs_direct_req
),
981 0, (SLAB_RECLAIM_ACCOUNT
|
984 if (nfs_direct_cachep
== NULL
)
991 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
994 void nfs_destroy_directcache(void)
996 kmem_cache_destroy(nfs_direct_cachep
);