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_IO - NFS address space operation for direct I/O
113 * @rw: direction (read or write)
114 * @iocb: target I/O control block
115 * @iov: array of vectors that define I/O buffer
116 * @pos: offset in file to begin the operation
117 * @nr_segs: size of iovec array
119 * The presence of this routine in the address space ops vector means
120 * the NFS client supports direct I/O. However, for most direct IO, we
121 * shunt off direct read and write requests before the VFS gets them,
122 * so this method is only ever called for swap.
124 ssize_t
nfs_direct_IO(int rw
, struct kiocb
*iocb
, const struct iovec
*iov
, loff_t pos
, unsigned long nr_segs
)
126 struct inode
*inode
= iocb
->ki_filp
->f_mapping
->host
;
128 /* we only support swap file calling nfs_direct_IO */
129 if (!IS_SWAPFILE(inode
))
132 #ifndef CONFIG_NFS_SWAP
133 dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n",
134 iocb
->ki_filp
->f_path
.dentry
->d_name
.name
,
135 (long long) pos
, nr_segs
);
139 VM_BUG_ON(iocb
->ki_left
!= PAGE_SIZE
);
140 VM_BUG_ON(iocb
->ki_nbytes
!= PAGE_SIZE
);
142 if (rw
== READ
|| rw
== KERNEL_READ
)
143 return nfs_file_direct_read(iocb
, iov
, nr_segs
, pos
,
144 rw
== READ
? true : false);
145 return nfs_file_direct_write(iocb
, iov
, nr_segs
, pos
,
146 rw
== WRITE
? true : false);
147 #endif /* CONFIG_NFS_SWAP */
150 static void nfs_direct_release_pages(struct page
**pages
, unsigned int npages
)
153 for (i
= 0; i
< npages
; i
++)
154 page_cache_release(pages
[i
]);
157 void nfs_init_cinfo_from_dreq(struct nfs_commit_info
*cinfo
,
158 struct nfs_direct_req
*dreq
)
160 cinfo
->lock
= &dreq
->lock
;
161 cinfo
->mds
= &dreq
->mds_cinfo
;
162 cinfo
->ds
= &dreq
->ds_cinfo
;
164 cinfo
->completion_ops
= &nfs_direct_commit_completion_ops
;
167 static inline struct nfs_direct_req
*nfs_direct_req_alloc(void)
169 struct nfs_direct_req
*dreq
;
171 dreq
= kmem_cache_zalloc(nfs_direct_cachep
, GFP_KERNEL
);
175 kref_init(&dreq
->kref
);
176 kref_get(&dreq
->kref
);
177 init_completion(&dreq
->completion
);
178 INIT_LIST_HEAD(&dreq
->mds_cinfo
.list
);
179 INIT_WORK(&dreq
->work
, nfs_direct_write_schedule_work
);
180 spin_lock_init(&dreq
->lock
);
185 static void nfs_direct_req_free(struct kref
*kref
)
187 struct nfs_direct_req
*dreq
= container_of(kref
, struct nfs_direct_req
, kref
);
189 nfs_free_pnfs_ds_cinfo(&dreq
->ds_cinfo
);
190 if (dreq
->l_ctx
!= NULL
)
191 nfs_put_lock_context(dreq
->l_ctx
);
192 if (dreq
->ctx
!= NULL
)
193 put_nfs_open_context(dreq
->ctx
);
194 kmem_cache_free(nfs_direct_cachep
, dreq
);
197 static void nfs_direct_req_release(struct nfs_direct_req
*dreq
)
199 kref_put(&dreq
->kref
, nfs_direct_req_free
);
202 ssize_t
nfs_dreq_bytes_left(struct nfs_direct_req
*dreq
)
204 return dreq
->bytes_left
;
206 EXPORT_SYMBOL_GPL(nfs_dreq_bytes_left
);
209 * Collects and returns the final error value/byte-count.
211 static ssize_t
nfs_direct_wait(struct nfs_direct_req
*dreq
)
213 ssize_t result
= -EIOCBQUEUED
;
215 /* Async requests don't wait here */
219 result
= wait_for_completion_killable(&dreq
->completion
);
222 result
= dreq
->error
;
224 result
= dreq
->count
;
227 return (ssize_t
) result
;
231 * Synchronous I/O uses a stack-allocated iocb. Thus we can't trust
232 * the iocb is still valid here if this is a synchronous request.
234 static void nfs_direct_complete(struct nfs_direct_req
*dreq
)
237 long res
= (long) dreq
->error
;
239 res
= (long) dreq
->count
;
240 aio_complete(dreq
->iocb
, res
, 0);
242 complete_all(&dreq
->completion
);
244 nfs_direct_req_release(dreq
);
247 static void nfs_direct_readpage_release(struct nfs_page
*req
)
249 dprintk("NFS: direct read done (%s/%lld %d@%lld)\n",
250 req
->wb_context
->dentry
->d_inode
->i_sb
->s_id
,
251 (long long)NFS_FILEID(req
->wb_context
->dentry
->d_inode
),
253 (long long)req_offset(req
));
254 nfs_release_request(req
);
257 static void nfs_direct_read_completion(struct nfs_pgio_header
*hdr
)
259 unsigned long bytes
= 0;
260 struct nfs_direct_req
*dreq
= hdr
->dreq
;
262 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
265 spin_lock(&dreq
->lock
);
266 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
) && (hdr
->good_bytes
== 0))
267 dreq
->error
= hdr
->error
;
269 dreq
->count
+= hdr
->good_bytes
;
270 spin_unlock(&dreq
->lock
);
272 while (!list_empty(&hdr
->pages
)) {
273 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
274 struct page
*page
= req
->wb_page
;
276 if (!PageCompound(page
) && bytes
< hdr
->good_bytes
)
277 set_page_dirty(page
);
278 bytes
+= req
->wb_bytes
;
279 nfs_list_remove_request(req
);
280 nfs_direct_readpage_release(req
);
284 nfs_direct_complete(dreq
);
288 static void nfs_read_sync_pgio_error(struct list_head
*head
)
290 struct nfs_page
*req
;
292 while (!list_empty(head
)) {
293 req
= nfs_list_entry(head
->next
);
294 nfs_list_remove_request(req
);
295 nfs_release_request(req
);
299 static void nfs_direct_pgio_init(struct nfs_pgio_header
*hdr
)
304 static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops
= {
305 .error_cleanup
= nfs_read_sync_pgio_error
,
306 .init_hdr
= nfs_direct_pgio_init
,
307 .completion
= nfs_direct_read_completion
,
311 * For each rsize'd chunk of the user's buffer, dispatch an NFS READ
312 * operation. If nfs_readdata_alloc() or get_user_pages() fails,
313 * bail and stop sending more reads. Read length accounting is
314 * handled automatically by nfs_direct_read_result(). Otherwise, if
315 * no requests have been sent, just return an error.
317 static ssize_t
nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor
*desc
,
318 const struct iovec
*iov
,
319 loff_t pos
, bool uio
)
321 struct nfs_direct_req
*dreq
= desc
->pg_dreq
;
322 struct nfs_open_context
*ctx
= dreq
->ctx
;
323 struct inode
*inode
= ctx
->dentry
->d_inode
;
324 unsigned long user_addr
= (unsigned long)iov
->iov_base
;
325 size_t count
= iov
->iov_len
;
326 size_t rsize
= NFS_SERVER(inode
)->rsize
;
330 struct page
**pagevec
= NULL
;
337 pgbase
= user_addr
& ~PAGE_MASK
;
338 bytes
= min(max_t(size_t, rsize
, PAGE_SIZE
), count
);
341 npages
= nfs_page_array_len(pgbase
, bytes
);
343 pagevec
= kmalloc(npages
* sizeof(struct page
*),
348 down_read(¤t
->mm
->mmap_sem
);
349 result
= get_user_pages(current
, current
->mm
, user_addr
,
350 npages
, 1, 0, pagevec
, NULL
);
351 up_read(¤t
->mm
->mmap_sem
);
355 WARN_ON(npages
!= 1);
356 result
= get_kernel_page(user_addr
, 1, pagevec
);
357 if (WARN_ON(result
!= 1))
361 if ((unsigned)result
< npages
) {
362 bytes
= result
* PAGE_SIZE
;
363 if (bytes
<= pgbase
) {
364 nfs_direct_release_pages(pagevec
, result
);
371 for (i
= 0; i
< npages
; i
++) {
372 struct nfs_page
*req
;
373 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
374 /* XXX do we need to do the eof zeroing found in async_filler? */
375 req
= nfs_create_request(dreq
->ctx
, dreq
->inode
,
379 result
= PTR_ERR(req
);
382 req
->wb_index
= pos
>> PAGE_SHIFT
;
383 req
->wb_offset
= pos
& ~PAGE_MASK
;
384 if (!nfs_pageio_add_request(desc
, req
)) {
385 result
= desc
->pg_error
;
386 nfs_release_request(req
);
392 user_addr
+= req_len
;
395 dreq
->bytes_left
-= req_len
;
397 /* The nfs_page now hold references to these pages */
398 nfs_direct_release_pages(pagevec
, npages
);
399 } while (count
!= 0 && result
>= 0);
405 return result
< 0 ? (ssize_t
) result
: -EFAULT
;
408 static ssize_t
nfs_direct_read_schedule_iovec(struct nfs_direct_req
*dreq
,
409 const struct iovec
*iov
,
410 unsigned long nr_segs
,
411 loff_t pos
, bool uio
)
413 struct nfs_pageio_descriptor desc
;
414 ssize_t result
= -EINVAL
;
415 size_t requested_bytes
= 0;
418 NFS_PROTO(dreq
->inode
)->read_pageio_init(&desc
, dreq
->inode
,
419 &nfs_direct_read_completion_ops
);
423 for (seg
= 0; seg
< nr_segs
; seg
++) {
424 const struct iovec
*vec
= &iov
[seg
];
425 result
= nfs_direct_read_schedule_segment(&desc
, vec
, pos
, uio
);
428 requested_bytes
+= result
;
429 if ((size_t)result
< vec
->iov_len
)
434 nfs_pageio_complete(&desc
);
437 * If no bytes were started, return the error, and let the
438 * generic layer handle the completion.
440 if (requested_bytes
== 0) {
441 nfs_direct_req_release(dreq
);
442 return result
< 0 ? result
: -EIO
;
446 nfs_direct_complete(dreq
);
450 static ssize_t
nfs_direct_read(struct kiocb
*iocb
, const struct iovec
*iov
,
451 unsigned long nr_segs
, loff_t pos
, bool uio
)
453 ssize_t result
= -ENOMEM
;
454 struct inode
*inode
= iocb
->ki_filp
->f_mapping
->host
;
455 struct nfs_direct_req
*dreq
;
456 struct nfs_lock_context
*l_ctx
;
458 dreq
= nfs_direct_req_alloc();
463 dreq
->bytes_left
= iov_length(iov
, nr_segs
);
464 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
465 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
467 result
= PTR_ERR(l_ctx
);
471 if (!is_sync_kiocb(iocb
))
474 NFS_I(inode
)->read_io
+= iov_length(iov
, nr_segs
);
475 result
= nfs_direct_read_schedule_iovec(dreq
, iov
, nr_segs
, pos
, uio
);
477 result
= nfs_direct_wait(dreq
);
479 nfs_direct_req_release(dreq
);
484 static void nfs_inode_dio_write_done(struct inode
*inode
)
486 nfs_zap_mapping(inode
, inode
->i_mapping
);
487 inode_dio_done(inode
);
490 #if IS_ENABLED(CONFIG_NFS_V3) || IS_ENABLED(CONFIG_NFS_V4)
491 static void nfs_direct_write_reschedule(struct nfs_direct_req
*dreq
)
493 struct nfs_pageio_descriptor desc
;
494 struct nfs_page
*req
, *tmp
;
496 struct nfs_commit_info cinfo
;
499 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
500 pnfs_recover_commit_reqs(dreq
->inode
, &reqs
, &cinfo
);
501 spin_lock(cinfo
.lock
);
502 nfs_scan_commit_list(&cinfo
.mds
->list
, &reqs
, &cinfo
, 0);
503 spin_unlock(cinfo
.lock
);
508 NFS_PROTO(dreq
->inode
)->write_pageio_init(&desc
, dreq
->inode
, FLUSH_STABLE
,
509 &nfs_direct_write_completion_ops
);
512 list_for_each_entry_safe(req
, tmp
, &reqs
, wb_list
) {
513 if (!nfs_pageio_add_request(&desc
, req
)) {
514 nfs_list_remove_request(req
);
515 nfs_list_add_request(req
, &failed
);
516 spin_lock(cinfo
.lock
);
519 spin_unlock(cinfo
.lock
);
521 nfs_release_request(req
);
523 nfs_pageio_complete(&desc
);
525 while (!list_empty(&failed
)) {
526 req
= nfs_list_entry(failed
.next
);
527 nfs_list_remove_request(req
);
528 nfs_unlock_and_release_request(req
);
532 nfs_direct_write_complete(dreq
, dreq
->inode
);
535 static void nfs_direct_commit_complete(struct nfs_commit_data
*data
)
537 struct nfs_direct_req
*dreq
= data
->dreq
;
538 struct nfs_commit_info cinfo
;
539 struct nfs_page
*req
;
540 int status
= data
->task
.tk_status
;
542 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
544 dprintk("NFS: %5u commit failed with error %d.\n",
545 data
->task
.tk_pid
, status
);
546 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
547 } else if (memcmp(&dreq
->verf
, &data
->verf
, sizeof(data
->verf
))) {
548 dprintk("NFS: %5u commit verify failed\n", data
->task
.tk_pid
);
549 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
552 dprintk("NFS: %5u commit returned %d\n", data
->task
.tk_pid
, status
);
553 while (!list_empty(&data
->pages
)) {
554 req
= nfs_list_entry(data
->pages
.next
);
555 nfs_list_remove_request(req
);
556 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
) {
557 /* Note the rewrite will go through mds */
558 nfs_mark_request_commit(req
, NULL
, &cinfo
);
560 nfs_release_request(req
);
561 nfs_unlock_and_release_request(req
);
564 if (atomic_dec_and_test(&cinfo
.mds
->rpcs_out
))
565 nfs_direct_write_complete(dreq
, data
->inode
);
568 static void nfs_direct_error_cleanup(struct nfs_inode
*nfsi
)
570 /* There is no lock to clear */
573 static const struct nfs_commit_completion_ops nfs_direct_commit_completion_ops
= {
574 .completion
= nfs_direct_commit_complete
,
575 .error_cleanup
= nfs_direct_error_cleanup
,
578 static void nfs_direct_commit_schedule(struct nfs_direct_req
*dreq
)
581 struct nfs_commit_info cinfo
;
584 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
585 nfs_scan_commit(dreq
->inode
, &mds_list
, &cinfo
);
586 res
= nfs_generic_commit_list(dreq
->inode
, &mds_list
, 0, &cinfo
);
587 if (res
< 0) /* res == -ENOMEM */
588 nfs_direct_write_reschedule(dreq
);
591 static void nfs_direct_write_schedule_work(struct work_struct
*work
)
593 struct nfs_direct_req
*dreq
= container_of(work
, struct nfs_direct_req
, work
);
594 int flags
= dreq
->flags
;
598 case NFS_ODIRECT_DO_COMMIT
:
599 nfs_direct_commit_schedule(dreq
);
601 case NFS_ODIRECT_RESCHED_WRITES
:
602 nfs_direct_write_reschedule(dreq
);
605 nfs_inode_dio_write_done(dreq
->inode
);
606 nfs_direct_complete(dreq
);
610 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
, struct inode
*inode
)
612 schedule_work(&dreq
->work
); /* Calls nfs_direct_write_schedule_work */
616 static void nfs_direct_write_schedule_work(struct work_struct
*work
)
620 static void nfs_direct_write_complete(struct nfs_direct_req
*dreq
, struct inode
*inode
)
622 nfs_inode_dio_write_done(inode
);
623 nfs_direct_complete(dreq
);
628 * NB: Return the value of the first error return code. Subsequent
629 * errors after the first one are ignored.
632 * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
633 * operation. If nfs_writedata_alloc() or get_user_pages() fails,
634 * bail and stop sending more writes. Write length accounting is
635 * handled automatically by nfs_direct_write_result(). Otherwise, if
636 * no requests have been sent, just return an error.
638 static ssize_t
nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor
*desc
,
639 const struct iovec
*iov
,
640 loff_t pos
, bool uio
)
642 struct nfs_direct_req
*dreq
= desc
->pg_dreq
;
643 struct nfs_open_context
*ctx
= dreq
->ctx
;
644 struct inode
*inode
= ctx
->dentry
->d_inode
;
645 unsigned long user_addr
= (unsigned long)iov
->iov_base
;
646 size_t count
= iov
->iov_len
;
647 size_t wsize
= NFS_SERVER(inode
)->wsize
;
651 struct page
**pagevec
= NULL
;
658 pgbase
= user_addr
& ~PAGE_MASK
;
659 bytes
= min(max_t(size_t, wsize
, PAGE_SIZE
), count
);
662 npages
= nfs_page_array_len(pgbase
, bytes
);
664 pagevec
= kmalloc(npages
* sizeof(struct page
*), GFP_KERNEL
);
669 down_read(¤t
->mm
->mmap_sem
);
670 result
= get_user_pages(current
, current
->mm
, user_addr
,
671 npages
, 0, 0, pagevec
, NULL
);
672 up_read(¤t
->mm
->mmap_sem
);
676 WARN_ON(npages
!= 1);
677 result
= get_kernel_page(user_addr
, 0, pagevec
);
678 if (WARN_ON(result
!= 1))
682 if ((unsigned)result
< npages
) {
683 bytes
= result
* PAGE_SIZE
;
684 if (bytes
<= pgbase
) {
685 nfs_direct_release_pages(pagevec
, result
);
692 for (i
= 0; i
< npages
; i
++) {
693 struct nfs_page
*req
;
694 unsigned int req_len
= min_t(size_t, bytes
, PAGE_SIZE
- pgbase
);
696 req
= nfs_create_request(dreq
->ctx
, dreq
->inode
,
700 result
= PTR_ERR(req
);
703 nfs_lock_request(req
);
704 req
->wb_index
= pos
>> PAGE_SHIFT
;
705 req
->wb_offset
= pos
& ~PAGE_MASK
;
706 if (!nfs_pageio_add_request(desc
, req
)) {
707 result
= desc
->pg_error
;
708 nfs_unlock_and_release_request(req
);
714 user_addr
+= req_len
;
717 dreq
->bytes_left
-= req_len
;
719 /* The nfs_page now hold references to these pages */
720 nfs_direct_release_pages(pagevec
, npages
);
721 } while (count
!= 0 && result
>= 0);
727 return result
< 0 ? (ssize_t
) result
: -EFAULT
;
730 static void nfs_direct_write_completion(struct nfs_pgio_header
*hdr
)
732 struct nfs_direct_req
*dreq
= hdr
->dreq
;
733 struct nfs_commit_info cinfo
;
735 struct nfs_page
*req
= nfs_list_entry(hdr
->pages
.next
);
737 if (test_bit(NFS_IOHDR_REDO
, &hdr
->flags
))
740 nfs_init_cinfo_from_dreq(&cinfo
, dreq
);
742 spin_lock(&dreq
->lock
);
744 if (test_bit(NFS_IOHDR_ERROR
, &hdr
->flags
)) {
746 dreq
->error
= hdr
->error
;
748 if (dreq
->error
!= 0)
749 bit
= NFS_IOHDR_ERROR
;
751 dreq
->count
+= hdr
->good_bytes
;
752 if (test_bit(NFS_IOHDR_NEED_RESCHED
, &hdr
->flags
)) {
753 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
754 bit
= NFS_IOHDR_NEED_RESCHED
;
755 } else if (test_bit(NFS_IOHDR_NEED_COMMIT
, &hdr
->flags
)) {
756 if (dreq
->flags
== NFS_ODIRECT_RESCHED_WRITES
)
757 bit
= NFS_IOHDR_NEED_RESCHED
;
758 else if (dreq
->flags
== 0) {
759 memcpy(&dreq
->verf
, hdr
->verf
,
761 bit
= NFS_IOHDR_NEED_COMMIT
;
762 dreq
->flags
= NFS_ODIRECT_DO_COMMIT
;
763 } else if (dreq
->flags
== NFS_ODIRECT_DO_COMMIT
) {
764 if (memcmp(&dreq
->verf
, hdr
->verf
, sizeof(dreq
->verf
))) {
765 dreq
->flags
= NFS_ODIRECT_RESCHED_WRITES
;
766 bit
= NFS_IOHDR_NEED_RESCHED
;
768 bit
= NFS_IOHDR_NEED_COMMIT
;
772 spin_unlock(&dreq
->lock
);
774 while (!list_empty(&hdr
->pages
)) {
775 req
= nfs_list_entry(hdr
->pages
.next
);
776 nfs_list_remove_request(req
);
778 case NFS_IOHDR_NEED_RESCHED
:
779 case NFS_IOHDR_NEED_COMMIT
:
780 kref_get(&req
->wb_kref
);
781 nfs_mark_request_commit(req
, hdr
->lseg
, &cinfo
);
783 nfs_unlock_and_release_request(req
);
788 nfs_direct_write_complete(dreq
, hdr
->inode
);
792 static void nfs_write_sync_pgio_error(struct list_head
*head
)
794 struct nfs_page
*req
;
796 while (!list_empty(head
)) {
797 req
= nfs_list_entry(head
->next
);
798 nfs_list_remove_request(req
);
799 nfs_unlock_and_release_request(req
);
803 static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops
= {
804 .error_cleanup
= nfs_write_sync_pgio_error
,
805 .init_hdr
= nfs_direct_pgio_init
,
806 .completion
= nfs_direct_write_completion
,
809 static ssize_t
nfs_direct_write_schedule_iovec(struct nfs_direct_req
*dreq
,
810 const struct iovec
*iov
,
811 unsigned long nr_segs
,
812 loff_t pos
, bool uio
)
814 struct nfs_pageio_descriptor desc
;
815 struct inode
*inode
= dreq
->inode
;
817 size_t requested_bytes
= 0;
820 NFS_PROTO(inode
)->write_pageio_init(&desc
, inode
, FLUSH_COND_STABLE
,
821 &nfs_direct_write_completion_ops
);
824 atomic_inc(&inode
->i_dio_count
);
826 NFS_I(dreq
->inode
)->write_io
+= iov_length(iov
, nr_segs
);
827 for (seg
= 0; seg
< nr_segs
; seg
++) {
828 const struct iovec
*vec
= &iov
[seg
];
829 result
= nfs_direct_write_schedule_segment(&desc
, vec
, pos
, uio
);
832 requested_bytes
+= result
;
833 if ((size_t)result
< vec
->iov_len
)
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_done(inode
);
845 nfs_direct_req_release(dreq
);
846 return result
< 0 ? result
: -EIO
;
850 nfs_direct_write_complete(dreq
, dreq
->inode
);
854 static ssize_t
nfs_direct_write(struct kiocb
*iocb
, const struct iovec
*iov
,
855 unsigned long nr_segs
, loff_t pos
,
856 size_t count
, bool uio
)
858 ssize_t result
= -ENOMEM
;
859 struct inode
*inode
= iocb
->ki_filp
->f_mapping
->host
;
860 struct nfs_direct_req
*dreq
;
861 struct nfs_lock_context
*l_ctx
;
863 dreq
= nfs_direct_req_alloc();
868 dreq
->bytes_left
= count
;
869 dreq
->ctx
= get_nfs_open_context(nfs_file_open_context(iocb
->ki_filp
));
870 l_ctx
= nfs_get_lock_context(dreq
->ctx
);
872 result
= PTR_ERR(l_ctx
);
876 if (!is_sync_kiocb(iocb
))
879 result
= nfs_direct_write_schedule_iovec(dreq
, iov
, nr_segs
, pos
, uio
);
881 result
= nfs_direct_wait(dreq
);
883 nfs_direct_req_release(dreq
);
889 * nfs_file_direct_read - file direct read operation for NFS files
890 * @iocb: target I/O control block
891 * @iov: vector of user buffers into which to read data
892 * @nr_segs: size of iov vector
893 * @pos: byte offset in file where reading starts
895 * We use this function for direct reads instead of calling
896 * generic_file_aio_read() in order to avoid gfar's check to see if
897 * the request starts before the end of the file. For that check
898 * to work, we must generate a GETATTR before each direct read, and
899 * even then there is a window between the GETATTR and the subsequent
900 * READ where the file size could change. Our preference is simply
901 * to do all reads the application wants, and the server will take
902 * care of managing the end of file boundary.
904 * This function also eliminates unnecessarily updating the file's
905 * atime locally, as the NFS server sets the file's atime, and this
906 * client must read the updated atime from the server back into its
909 ssize_t
nfs_file_direct_read(struct kiocb
*iocb
, const struct iovec
*iov
,
910 unsigned long nr_segs
, loff_t pos
, bool uio
)
912 ssize_t retval
= -EINVAL
;
913 struct file
*file
= iocb
->ki_filp
;
914 struct address_space
*mapping
= file
->f_mapping
;
917 count
= iov_length(iov
, nr_segs
);
918 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTREADBYTES
, count
);
920 dfprintk(FILE, "NFS: direct read(%s/%s, %zd@%Ld)\n",
921 file
->f_path
.dentry
->d_parent
->d_name
.name
,
922 file
->f_path
.dentry
->d_name
.name
,
923 count
, (long long) pos
);
929 retval
= nfs_sync_mapping(mapping
);
933 task_io_account_read(count
);
935 retval
= nfs_direct_read(iocb
, iov
, nr_segs
, pos
, uio
);
937 iocb
->ki_pos
= pos
+ retval
;
944 * nfs_file_direct_write - file direct write operation for NFS files
945 * @iocb: target I/O control block
946 * @iov: vector of user buffers from which to write data
947 * @nr_segs: size of iov vector
948 * @pos: byte offset in file where writing starts
950 * We use this function for direct writes instead of calling
951 * generic_file_aio_write() in order to avoid taking the inode
952 * semaphore and updating the i_size. The NFS server will set
953 * the new i_size and this client must read the updated size
954 * back into its cache. We let the server do generic write
955 * parameter checking and report problems.
957 * We eliminate local atime updates, see direct read above.
959 * We avoid unnecessary page cache invalidations for normal cached
960 * readers of this file.
962 * Note that O_APPEND is not supported for NFS direct writes, as there
963 * is no atomic O_APPEND write facility in the NFS protocol.
965 ssize_t
nfs_file_direct_write(struct kiocb
*iocb
, const struct iovec
*iov
,
966 unsigned long nr_segs
, loff_t pos
, bool uio
)
968 ssize_t retval
= -EINVAL
;
969 struct file
*file
= iocb
->ki_filp
;
970 struct address_space
*mapping
= file
->f_mapping
;
973 count
= iov_length(iov
, nr_segs
);
974 nfs_add_stats(mapping
->host
, NFSIOS_DIRECTWRITTENBYTES
, count
);
976 dfprintk(FILE, "NFS: direct write(%s/%s, %zd@%Ld)\n",
977 file
->f_path
.dentry
->d_parent
->d_name
.name
,
978 file
->f_path
.dentry
->d_name
.name
,
979 count
, (long long) pos
);
981 retval
= generic_write_checks(file
, &pos
, &count
, 0);
986 if ((ssize_t
) count
< 0)
992 retval
= nfs_sync_mapping(mapping
);
996 task_io_account_write(count
);
998 retval
= nfs_direct_write(iocb
, iov
, nr_segs
, pos
, count
, uio
);
1000 struct inode
*inode
= mapping
->host
;
1002 iocb
->ki_pos
= pos
+ retval
;
1003 spin_lock(&inode
->i_lock
);
1004 if (i_size_read(inode
) < iocb
->ki_pos
)
1005 i_size_write(inode
, iocb
->ki_pos
);
1006 spin_unlock(&inode
->i_lock
);
1013 * nfs_init_directcache - create a slab cache for nfs_direct_req structures
1016 int __init
nfs_init_directcache(void)
1018 nfs_direct_cachep
= kmem_cache_create("nfs_direct_cache",
1019 sizeof(struct nfs_direct_req
),
1020 0, (SLAB_RECLAIM_ACCOUNT
|
1023 if (nfs_direct_cachep
== NULL
)
1030 * nfs_destroy_directcache - destroy the slab cache for nfs_direct_req structures
1033 void nfs_destroy_directcache(void)
1035 kmem_cache_destroy(nfs_direct_cachep
);