4 * Write file data over NFS.
6 * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
9 #include <linux/types.h>
10 #include <linux/slab.h>
12 #include <linux/pagemap.h>
13 #include <linux/file.h>
14 #include <linux/writeback.h>
15 #include <linux/swap.h>
16 #include <linux/migrate.h>
18 #include <linux/sunrpc/clnt.h>
19 #include <linux/nfs_fs.h>
20 #include <linux/nfs_mount.h>
21 #include <linux/nfs_page.h>
22 #include <linux/backing-dev.h>
24 #include <asm/uaccess.h>
26 #include "delegation.h"
32 #define NFSDBG_FACILITY NFSDBG_PAGECACHE
34 #define MIN_POOL_WRITE (32)
35 #define MIN_POOL_COMMIT (4)
38 * Local function declarations
40 static void nfs_pageio_init_write(struct nfs_pageio_descriptor
*desc
,
41 struct inode
*inode
, int ioflags
);
42 static void nfs_redirty_request(struct nfs_page
*req
);
43 static const struct rpc_call_ops nfs_write_partial_ops
;
44 static const struct rpc_call_ops nfs_write_full_ops
;
45 static const struct rpc_call_ops nfs_commit_ops
;
47 static struct kmem_cache
*nfs_wdata_cachep
;
48 static mempool_t
*nfs_wdata_mempool
;
49 static mempool_t
*nfs_commit_mempool
;
51 struct nfs_write_data
*nfs_commitdata_alloc(void)
53 struct nfs_write_data
*p
= mempool_alloc(nfs_commit_mempool
, GFP_NOFS
);
56 memset(p
, 0, sizeof(*p
));
57 INIT_LIST_HEAD(&p
->pages
);
58 p
->res
.seq_res
.sr_slotid
= NFS4_MAX_SLOT_TABLE
;
63 void nfs_commit_free(struct nfs_write_data
*p
)
65 if (p
&& (p
->pagevec
!= &p
->page_array
[0]))
67 mempool_free(p
, nfs_commit_mempool
);
70 struct nfs_write_data
*nfs_writedata_alloc(unsigned int pagecount
)
72 struct nfs_write_data
*p
= mempool_alloc(nfs_wdata_mempool
, GFP_NOFS
);
75 memset(p
, 0, sizeof(*p
));
76 INIT_LIST_HEAD(&p
->pages
);
77 p
->npages
= pagecount
;
78 p
->res
.seq_res
.sr_slotid
= NFS4_MAX_SLOT_TABLE
;
79 if (pagecount
<= ARRAY_SIZE(p
->page_array
))
80 p
->pagevec
= p
->page_array
;
82 p
->pagevec
= kcalloc(pagecount
, sizeof(struct page
*), GFP_NOFS
);
84 mempool_free(p
, nfs_wdata_mempool
);
92 void nfs_writedata_free(struct nfs_write_data
*p
)
94 if (p
&& (p
->pagevec
!= &p
->page_array
[0]))
96 mempool_free(p
, nfs_wdata_mempool
);
99 static void nfs_writedata_release(struct nfs_write_data
*wdata
)
101 put_nfs_open_context(wdata
->args
.context
);
102 nfs_writedata_free(wdata
);
105 static void nfs_context_set_write_error(struct nfs_open_context
*ctx
, int error
)
109 set_bit(NFS_CONTEXT_ERROR_WRITE
, &ctx
->flags
);
112 static struct nfs_page
*nfs_page_find_request_locked(struct page
*page
)
114 struct nfs_page
*req
= NULL
;
116 if (PagePrivate(page
)) {
117 req
= (struct nfs_page
*)page_private(page
);
119 kref_get(&req
->wb_kref
);
124 static struct nfs_page
*nfs_page_find_request(struct page
*page
)
126 struct inode
*inode
= page
->mapping
->host
;
127 struct nfs_page
*req
= NULL
;
129 spin_lock(&inode
->i_lock
);
130 req
= nfs_page_find_request_locked(page
);
131 spin_unlock(&inode
->i_lock
);
135 /* Adjust the file length if we're writing beyond the end */
136 static void nfs_grow_file(struct page
*page
, unsigned int offset
, unsigned int count
)
138 struct inode
*inode
= page
->mapping
->host
;
142 spin_lock(&inode
->i_lock
);
143 i_size
= i_size_read(inode
);
144 end_index
= (i_size
- 1) >> PAGE_CACHE_SHIFT
;
145 if (i_size
> 0 && page
->index
< end_index
)
147 end
= ((loff_t
)page
->index
<< PAGE_CACHE_SHIFT
) + ((loff_t
)offset
+count
);
150 i_size_write(inode
, end
);
151 nfs_inc_stats(inode
, NFSIOS_EXTENDWRITE
);
153 spin_unlock(&inode
->i_lock
);
156 /* A writeback failed: mark the page as bad, and invalidate the page cache */
157 static void nfs_set_pageerror(struct page
*page
)
160 nfs_zap_mapping(page
->mapping
->host
, page
->mapping
);
163 /* We can set the PG_uptodate flag if we see that a write request
164 * covers the full page.
166 static void nfs_mark_uptodate(struct page
*page
, unsigned int base
, unsigned int count
)
168 if (PageUptodate(page
))
172 if (count
!= nfs_page_length(page
))
174 SetPageUptodate(page
);
177 static int wb_priority(struct writeback_control
*wbc
)
179 if (wbc
->for_reclaim
)
180 return FLUSH_HIGHPRI
| FLUSH_STABLE
;
181 if (wbc
->for_kupdate
|| wbc
->for_background
)
187 * NFS congestion control
190 int nfs_congestion_kb
;
192 #define NFS_CONGESTION_ON_THRESH (nfs_congestion_kb >> (PAGE_SHIFT-10))
193 #define NFS_CONGESTION_OFF_THRESH \
194 (NFS_CONGESTION_ON_THRESH - (NFS_CONGESTION_ON_THRESH >> 2))
196 static int nfs_set_page_writeback(struct page
*page
)
198 int ret
= test_set_page_writeback(page
);
201 struct inode
*inode
= page
->mapping
->host
;
202 struct nfs_server
*nfss
= NFS_SERVER(inode
);
204 if (atomic_long_inc_return(&nfss
->writeback
) >
205 NFS_CONGESTION_ON_THRESH
) {
206 set_bdi_congested(&nfss
->backing_dev_info
,
213 static void nfs_end_page_writeback(struct page
*page
)
215 struct inode
*inode
= page
->mapping
->host
;
216 struct nfs_server
*nfss
= NFS_SERVER(inode
);
218 end_page_writeback(page
);
219 if (atomic_long_dec_return(&nfss
->writeback
) < NFS_CONGESTION_OFF_THRESH
)
220 clear_bdi_congested(&nfss
->backing_dev_info
, BLK_RW_ASYNC
);
223 static struct nfs_page
*nfs_find_and_lock_request(struct page
*page
)
225 struct inode
*inode
= page
->mapping
->host
;
226 struct nfs_page
*req
;
229 spin_lock(&inode
->i_lock
);
231 req
= nfs_page_find_request_locked(page
);
234 if (nfs_set_page_tag_locked(req
))
236 /* Note: If we hold the page lock, as is the case in nfs_writepage,
237 * then the call to nfs_set_page_tag_locked() will always
238 * succeed provided that someone hasn't already marked the
239 * request as dirty (in which case we don't care).
241 spin_unlock(&inode
->i_lock
);
242 ret
= nfs_wait_on_request(req
);
243 nfs_release_request(req
);
246 spin_lock(&inode
->i_lock
);
248 spin_unlock(&inode
->i_lock
);
253 * Find an associated nfs write request, and prepare to flush it out
254 * May return an error if the user signalled nfs_wait_on_request().
256 static int nfs_page_async_flush(struct nfs_pageio_descriptor
*pgio
,
259 struct nfs_page
*req
;
262 req
= nfs_find_and_lock_request(page
);
269 ret
= nfs_set_page_writeback(page
);
271 BUG_ON(test_bit(PG_CLEAN
, &req
->wb_flags
));
273 if (!nfs_pageio_add_request(pgio
, req
)) {
274 nfs_redirty_request(req
);
275 ret
= pgio
->pg_error
;
281 static int nfs_do_writepage(struct page
*page
, struct writeback_control
*wbc
, struct nfs_pageio_descriptor
*pgio
)
283 struct inode
*inode
= page
->mapping
->host
;
285 nfs_inc_stats(inode
, NFSIOS_VFSWRITEPAGE
);
286 nfs_add_stats(inode
, NFSIOS_WRITEPAGES
, 1);
288 nfs_pageio_cond_complete(pgio
, page
->index
);
289 return nfs_page_async_flush(pgio
, page
);
293 * Write an mmapped page to the server.
295 static int nfs_writepage_locked(struct page
*page
, struct writeback_control
*wbc
)
297 struct nfs_pageio_descriptor pgio
;
300 nfs_pageio_init_write(&pgio
, page
->mapping
->host
, wb_priority(wbc
));
301 err
= nfs_do_writepage(page
, wbc
, &pgio
);
302 nfs_pageio_complete(&pgio
);
305 if (pgio
.pg_error
< 0)
306 return pgio
.pg_error
;
310 int nfs_writepage(struct page
*page
, struct writeback_control
*wbc
)
314 ret
= nfs_writepage_locked(page
, wbc
);
319 static int nfs_writepages_callback(struct page
*page
, struct writeback_control
*wbc
, void *data
)
323 ret
= nfs_do_writepage(page
, wbc
, data
);
328 int nfs_writepages(struct address_space
*mapping
, struct writeback_control
*wbc
)
330 struct inode
*inode
= mapping
->host
;
331 unsigned long *bitlock
= &NFS_I(inode
)->flags
;
332 struct nfs_pageio_descriptor pgio
;
335 /* Stop dirtying of new pages while we sync */
336 err
= wait_on_bit_lock(bitlock
, NFS_INO_FLUSHING
,
337 nfs_wait_bit_killable
, TASK_KILLABLE
);
341 nfs_inc_stats(inode
, NFSIOS_VFSWRITEPAGES
);
343 nfs_pageio_init_write(&pgio
, inode
, wb_priority(wbc
));
344 err
= write_cache_pages(mapping
, wbc
, nfs_writepages_callback
, &pgio
);
345 nfs_pageio_complete(&pgio
);
347 clear_bit_unlock(NFS_INO_FLUSHING
, bitlock
);
348 smp_mb__after_clear_bit();
349 wake_up_bit(bitlock
, NFS_INO_FLUSHING
);
362 * Insert a write request into an inode
364 static int nfs_inode_add_request(struct inode
*inode
, struct nfs_page
*req
)
366 struct nfs_inode
*nfsi
= NFS_I(inode
);
369 error
= radix_tree_preload(GFP_NOFS
);
373 /* Lock the request! */
374 nfs_lock_request_dontget(req
);
376 spin_lock(&inode
->i_lock
);
377 error
= radix_tree_insert(&nfsi
->nfs_page_tree
, req
->wb_index
, req
);
381 if (nfs_have_delegation(inode
, FMODE_WRITE
))
384 SetPagePrivate(req
->wb_page
);
385 set_page_private(req
->wb_page
, (unsigned long)req
);
387 kref_get(&req
->wb_kref
);
388 radix_tree_tag_set(&nfsi
->nfs_page_tree
, req
->wb_index
,
389 NFS_PAGE_TAG_LOCKED
);
390 spin_unlock(&inode
->i_lock
);
391 radix_tree_preload_end();
397 * Remove a write request from an inode
399 static void nfs_inode_remove_request(struct nfs_page
*req
)
401 struct inode
*inode
= req
->wb_context
->path
.dentry
->d_inode
;
402 struct nfs_inode
*nfsi
= NFS_I(inode
);
404 BUG_ON (!NFS_WBACK_BUSY(req
));
406 spin_lock(&inode
->i_lock
);
407 set_page_private(req
->wb_page
, 0);
408 ClearPagePrivate(req
->wb_page
);
409 radix_tree_delete(&nfsi
->nfs_page_tree
, req
->wb_index
);
412 spin_unlock(&inode
->i_lock
);
415 spin_unlock(&inode
->i_lock
);
416 nfs_clear_request(req
);
417 nfs_release_request(req
);
421 nfs_mark_request_dirty(struct nfs_page
*req
)
423 __set_page_dirty_nobuffers(req
->wb_page
);
426 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
428 * Add a request to the inode's commit list.
431 nfs_mark_request_commit(struct nfs_page
*req
)
433 struct inode
*inode
= req
->wb_context
->path
.dentry
->d_inode
;
434 struct nfs_inode
*nfsi
= NFS_I(inode
);
436 spin_lock(&inode
->i_lock
);
437 set_bit(PG_CLEAN
, &(req
)->wb_flags
);
438 radix_tree_tag_set(&nfsi
->nfs_page_tree
,
440 NFS_PAGE_TAG_COMMIT
);
442 spin_unlock(&inode
->i_lock
);
443 inc_zone_page_state(req
->wb_page
, NR_UNSTABLE_NFS
);
444 inc_bdi_stat(req
->wb_page
->mapping
->backing_dev_info
, BDI_RECLAIMABLE
);
445 __mark_inode_dirty(inode
, I_DIRTY_DATASYNC
);
449 nfs_clear_request_commit(struct nfs_page
*req
)
451 struct page
*page
= req
->wb_page
;
453 if (test_and_clear_bit(PG_CLEAN
, &(req
)->wb_flags
)) {
454 dec_zone_page_state(page
, NR_UNSTABLE_NFS
);
455 dec_bdi_stat(page
->mapping
->backing_dev_info
, BDI_RECLAIMABLE
);
462 int nfs_write_need_commit(struct nfs_write_data
*data
)
464 return data
->verf
.committed
!= NFS_FILE_SYNC
;
468 int nfs_reschedule_unstable_write(struct nfs_page
*req
)
470 if (test_and_clear_bit(PG_NEED_COMMIT
, &req
->wb_flags
)) {
471 nfs_mark_request_commit(req
);
474 if (test_and_clear_bit(PG_NEED_RESCHED
, &req
->wb_flags
)) {
475 nfs_mark_request_dirty(req
);
482 nfs_mark_request_commit(struct nfs_page
*req
)
487 nfs_clear_request_commit(struct nfs_page
*req
)
493 int nfs_write_need_commit(struct nfs_write_data
*data
)
499 int nfs_reschedule_unstable_write(struct nfs_page
*req
)
506 * Wait for a request to complete.
508 * Interruptible by fatal signals only.
510 static int nfs_wait_on_requests_locked(struct inode
*inode
, pgoff_t idx_start
, unsigned int npages
)
512 struct nfs_inode
*nfsi
= NFS_I(inode
);
513 struct nfs_page
*req
;
514 pgoff_t idx_end
, next
;
515 unsigned int res
= 0;
521 idx_end
= idx_start
+ npages
- 1;
524 while (radix_tree_gang_lookup_tag(&nfsi
->nfs_page_tree
, (void **)&req
, next
, 1, NFS_PAGE_TAG_LOCKED
)) {
525 if (req
->wb_index
> idx_end
)
528 next
= req
->wb_index
+ 1;
529 BUG_ON(!NFS_WBACK_BUSY(req
));
531 kref_get(&req
->wb_kref
);
532 spin_unlock(&inode
->i_lock
);
533 error
= nfs_wait_on_request(req
);
534 nfs_release_request(req
);
535 spin_lock(&inode
->i_lock
);
543 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
545 nfs_need_commit(struct nfs_inode
*nfsi
)
547 return radix_tree_tagged(&nfsi
->nfs_page_tree
, NFS_PAGE_TAG_COMMIT
);
551 * nfs_scan_commit - Scan an inode for commit requests
552 * @inode: NFS inode to scan
553 * @dst: destination list
554 * @idx_start: lower bound of page->index to scan.
555 * @npages: idx_start + npages sets the upper bound to scan.
557 * Moves requests from the inode's 'commit' request list.
558 * The requests are *not* checked to ensure that they form a contiguous set.
561 nfs_scan_commit(struct inode
*inode
, struct list_head
*dst
, pgoff_t idx_start
, unsigned int npages
)
563 struct nfs_inode
*nfsi
= NFS_I(inode
);
566 if (!nfs_need_commit(nfsi
))
569 ret
= nfs_scan_list(nfsi
, dst
, idx_start
, npages
, NFS_PAGE_TAG_COMMIT
);
571 nfsi
->ncommit
-= ret
;
572 if (nfs_need_commit(NFS_I(inode
)))
573 __mark_inode_dirty(inode
, I_DIRTY_DATASYNC
);
577 static inline int nfs_need_commit(struct nfs_inode
*nfsi
)
582 static inline int nfs_scan_commit(struct inode
*inode
, struct list_head
*dst
, pgoff_t idx_start
, unsigned int npages
)
589 * Search for an existing write request, and attempt to update
590 * it to reflect a new dirty region on a given page.
592 * If the attempt fails, then the existing request is flushed out
595 static struct nfs_page
*nfs_try_to_update_request(struct inode
*inode
,
600 struct nfs_page
*req
;
605 if (!PagePrivate(page
))
608 end
= offset
+ bytes
;
609 spin_lock(&inode
->i_lock
);
612 req
= nfs_page_find_request_locked(page
);
616 rqend
= req
->wb_offset
+ req
->wb_bytes
;
618 * Tell the caller to flush out the request if
619 * the offsets are non-contiguous.
620 * Note: nfs_flush_incompatible() will already
621 * have flushed out requests having wrong owners.
624 || end
< req
->wb_offset
)
627 if (nfs_set_page_tag_locked(req
))
630 /* The request is locked, so wait and then retry */
631 spin_unlock(&inode
->i_lock
);
632 error
= nfs_wait_on_request(req
);
633 nfs_release_request(req
);
636 spin_lock(&inode
->i_lock
);
639 if (nfs_clear_request_commit(req
) &&
640 radix_tree_tag_clear(&NFS_I(inode
)->nfs_page_tree
,
641 req
->wb_index
, NFS_PAGE_TAG_COMMIT
) != NULL
)
642 NFS_I(inode
)->ncommit
--;
644 /* Okay, the request matches. Update the region */
645 if (offset
< req
->wb_offset
) {
646 req
->wb_offset
= offset
;
647 req
->wb_pgbase
= offset
;
650 req
->wb_bytes
= end
- req
->wb_offset
;
652 req
->wb_bytes
= rqend
- req
->wb_offset
;
654 spin_unlock(&inode
->i_lock
);
657 spin_unlock(&inode
->i_lock
);
658 nfs_release_request(req
);
659 error
= nfs_wb_page(inode
, page
);
661 return ERR_PTR(error
);
665 * Try to update an existing write request, or create one if there is none.
667 * Note: Should always be called with the Page Lock held to prevent races
668 * if we have to add a new request. Also assumes that the caller has
669 * already called nfs_flush_incompatible() if necessary.
671 static struct nfs_page
* nfs_setup_write_request(struct nfs_open_context
* ctx
,
672 struct page
*page
, unsigned int offset
, unsigned int bytes
)
674 struct inode
*inode
= page
->mapping
->host
;
675 struct nfs_page
*req
;
678 req
= nfs_try_to_update_request(inode
, page
, offset
, bytes
);
681 req
= nfs_create_request(ctx
, inode
, page
, offset
, bytes
);
684 error
= nfs_inode_add_request(inode
, req
);
686 nfs_release_request(req
);
687 req
= ERR_PTR(error
);
693 static int nfs_writepage_setup(struct nfs_open_context
*ctx
, struct page
*page
,
694 unsigned int offset
, unsigned int count
)
696 struct nfs_page
*req
;
698 req
= nfs_setup_write_request(ctx
, page
, offset
, count
);
701 /* Update file length */
702 nfs_grow_file(page
, offset
, count
);
703 nfs_mark_uptodate(page
, req
->wb_pgbase
, req
->wb_bytes
);
704 nfs_clear_page_tag_locked(req
);
708 int nfs_flush_incompatible(struct file
*file
, struct page
*page
)
710 struct nfs_open_context
*ctx
= nfs_file_open_context(file
);
711 struct nfs_page
*req
;
712 int do_flush
, status
;
714 * Look for a request corresponding to this page. If there
715 * is one, and it belongs to another file, we flush it out
716 * before we try to copy anything into the page. Do this
717 * due to the lack of an ACCESS-type call in NFSv2.
718 * Also do the same if we find a request from an existing
722 req
= nfs_page_find_request(page
);
725 do_flush
= req
->wb_page
!= page
|| req
->wb_context
!= ctx
;
726 nfs_release_request(req
);
729 status
= nfs_wb_page(page
->mapping
->host
, page
);
730 } while (status
== 0);
735 * If the page cache is marked as unsafe or invalid, then we can't rely on
736 * the PageUptodate() flag. In this case, we will need to turn off
737 * write optimisations that depend on the page contents being correct.
739 static int nfs_write_pageuptodate(struct page
*page
, struct inode
*inode
)
741 return PageUptodate(page
) &&
742 !(NFS_I(inode
)->cache_validity
& (NFS_INO_REVAL_PAGECACHE
|NFS_INO_INVALID_DATA
));
746 * Update and possibly write a cached page of an NFS file.
748 * XXX: Keep an eye on generic_file_read to make sure it doesn't do bad
749 * things with a page scheduled for an RPC call (e.g. invalidate it).
751 int nfs_updatepage(struct file
*file
, struct page
*page
,
752 unsigned int offset
, unsigned int count
)
754 struct nfs_open_context
*ctx
= nfs_file_open_context(file
);
755 struct inode
*inode
= page
->mapping
->host
;
758 nfs_inc_stats(inode
, NFSIOS_VFSUPDATEPAGE
);
760 dprintk("NFS: nfs_updatepage(%s/%s %d@%lld)\n",
761 file
->f_path
.dentry
->d_parent
->d_name
.name
,
762 file
->f_path
.dentry
->d_name
.name
, count
,
763 (long long)(page_offset(page
) + offset
));
765 /* If we're not using byte range locks, and we know the page
766 * is up to date, it may be more efficient to extend the write
767 * to cover the entire page in order to avoid fragmentation
770 if (nfs_write_pageuptodate(page
, inode
) &&
771 inode
->i_flock
== NULL
&&
772 !(file
->f_flags
& O_DSYNC
)) {
773 count
= max(count
+ offset
, nfs_page_length(page
));
777 status
= nfs_writepage_setup(ctx
, page
, offset
, count
);
779 nfs_set_pageerror(page
);
781 __set_page_dirty_nobuffers(page
);
783 dprintk("NFS: nfs_updatepage returns %d (isize %lld)\n",
784 status
, (long long)i_size_read(inode
));
788 static void nfs_writepage_release(struct nfs_page
*req
)
791 if (PageError(req
->wb_page
) || !nfs_reschedule_unstable_write(req
)) {
792 nfs_end_page_writeback(req
->wb_page
);
793 nfs_inode_remove_request(req
);
795 nfs_end_page_writeback(req
->wb_page
);
796 nfs_clear_page_tag_locked(req
);
799 static int flush_task_priority(int how
)
801 switch (how
& (FLUSH_HIGHPRI
|FLUSH_LOWPRI
)) {
803 return RPC_PRIORITY_HIGH
;
805 return RPC_PRIORITY_LOW
;
807 return RPC_PRIORITY_NORMAL
;
811 * Set up the argument/result storage required for the RPC call.
813 static int nfs_write_rpcsetup(struct nfs_page
*req
,
814 struct nfs_write_data
*data
,
815 const struct rpc_call_ops
*call_ops
,
816 unsigned int count
, unsigned int offset
,
819 struct inode
*inode
= req
->wb_context
->path
.dentry
->d_inode
;
820 int flags
= (how
& FLUSH_SYNC
) ? 0 : RPC_TASK_ASYNC
;
821 int priority
= flush_task_priority(how
);
822 struct rpc_task
*task
;
823 struct rpc_message msg
= {
824 .rpc_argp
= &data
->args
,
825 .rpc_resp
= &data
->res
,
826 .rpc_cred
= req
->wb_context
->cred
,
828 struct rpc_task_setup task_setup_data
= {
829 .rpc_client
= NFS_CLIENT(inode
),
832 .callback_ops
= call_ops
,
833 .callback_data
= data
,
834 .workqueue
= nfsiod_workqueue
,
836 .priority
= priority
,
839 /* Set up the RPC argument and reply structs
840 * NB: take care not to mess about with data->commit et al. */
843 data
->inode
= inode
= req
->wb_context
->path
.dentry
->d_inode
;
844 data
->cred
= msg
.rpc_cred
;
846 data
->args
.fh
= NFS_FH(inode
);
847 data
->args
.offset
= req_offset(req
) + offset
;
848 data
->args
.pgbase
= req
->wb_pgbase
+ offset
;
849 data
->args
.pages
= data
->pagevec
;
850 data
->args
.count
= count
;
851 data
->args
.context
= get_nfs_open_context(req
->wb_context
);
852 data
->args
.stable
= NFS_UNSTABLE
;
853 if (how
& FLUSH_STABLE
) {
854 data
->args
.stable
= NFS_DATA_SYNC
;
855 if (!nfs_need_commit(NFS_I(inode
)))
856 data
->args
.stable
= NFS_FILE_SYNC
;
859 data
->res
.fattr
= &data
->fattr
;
860 data
->res
.count
= count
;
861 data
->res
.verf
= &data
->verf
;
862 nfs_fattr_init(&data
->fattr
);
864 /* Set up the initial task struct. */
865 NFS_PROTO(inode
)->write_setup(data
, &msg
);
867 dprintk("NFS: %5u initiated write call "
868 "(req %s/%lld, %u bytes @ offset %llu)\n",
871 (long long)NFS_FILEID(inode
),
873 (unsigned long long)data
->args
.offset
);
875 task
= rpc_run_task(&task_setup_data
);
877 return PTR_ERR(task
);
882 /* If a nfs_flush_* function fails, it should remove reqs from @head and
883 * call this on each, which will prepare them to be retried on next
884 * writeback using standard nfs.
886 static void nfs_redirty_request(struct nfs_page
*req
)
888 nfs_mark_request_dirty(req
);
889 nfs_end_page_writeback(req
->wb_page
);
890 nfs_clear_page_tag_locked(req
);
894 * Generate multiple small requests to write out a single
895 * contiguous dirty area on one page.
897 static int nfs_flush_multi(struct inode
*inode
, struct list_head
*head
, unsigned int npages
, size_t count
, int how
)
899 struct nfs_page
*req
= nfs_list_entry(head
->next
);
900 struct page
*page
= req
->wb_page
;
901 struct nfs_write_data
*data
;
902 size_t wsize
= NFS_SERVER(inode
)->wsize
, nbytes
;
908 nfs_list_remove_request(req
);
912 size_t len
= min(nbytes
, wsize
);
914 data
= nfs_writedata_alloc(1);
917 list_add(&data
->pages
, &list
);
920 } while (nbytes
!= 0);
921 atomic_set(&req
->wb_complete
, requests
);
923 ClearPageError(page
);
929 data
= list_entry(list
.next
, struct nfs_write_data
, pages
);
930 list_del_init(&data
->pages
);
932 data
->pagevec
[0] = page
;
936 ret2
= nfs_write_rpcsetup(req
, data
, &nfs_write_partial_ops
,
942 } while (nbytes
!= 0);
947 while (!list_empty(&list
)) {
948 data
= list_entry(list
.next
, struct nfs_write_data
, pages
);
949 list_del(&data
->pages
);
950 nfs_writedata_release(data
);
952 nfs_redirty_request(req
);
957 * Create an RPC task for the given write request and kick it.
958 * The page must have been locked by the caller.
960 * It may happen that the page we're passed is not marked dirty.
961 * This is the case if nfs_updatepage detects a conflicting request
962 * that has been written but not committed.
964 static int nfs_flush_one(struct inode
*inode
, struct list_head
*head
, unsigned int npages
, size_t count
, int how
)
966 struct nfs_page
*req
;
968 struct nfs_write_data
*data
;
970 data
= nfs_writedata_alloc(npages
);
974 pages
= data
->pagevec
;
975 while (!list_empty(head
)) {
976 req
= nfs_list_entry(head
->next
);
977 nfs_list_remove_request(req
);
978 nfs_list_add_request(req
, &data
->pages
);
979 ClearPageError(req
->wb_page
);
980 *pages
++ = req
->wb_page
;
982 req
= nfs_list_entry(data
->pages
.next
);
984 /* Set up the argument struct */
985 return nfs_write_rpcsetup(req
, data
, &nfs_write_full_ops
, count
, 0, how
);
987 while (!list_empty(head
)) {
988 req
= nfs_list_entry(head
->next
);
989 nfs_list_remove_request(req
);
990 nfs_redirty_request(req
);
995 static void nfs_pageio_init_write(struct nfs_pageio_descriptor
*pgio
,
996 struct inode
*inode
, int ioflags
)
998 size_t wsize
= NFS_SERVER(inode
)->wsize
;
1000 if (wsize
< PAGE_CACHE_SIZE
)
1001 nfs_pageio_init(pgio
, inode
, nfs_flush_multi
, wsize
, ioflags
);
1003 nfs_pageio_init(pgio
, inode
, nfs_flush_one
, wsize
, ioflags
);
1007 * Handle a write reply that flushed part of a page.
1009 static void nfs_writeback_done_partial(struct rpc_task
*task
, void *calldata
)
1011 struct nfs_write_data
*data
= calldata
;
1013 dprintk("NFS: %5u write(%s/%lld %d@%lld)",
1015 data
->req
->wb_context
->path
.dentry
->d_inode
->i_sb
->s_id
,
1017 NFS_FILEID(data
->req
->wb_context
->path
.dentry
->d_inode
),
1018 data
->req
->wb_bytes
, (long long)req_offset(data
->req
));
1020 nfs_writeback_done(task
, data
);
1023 static void nfs_writeback_release_partial(void *calldata
)
1025 struct nfs_write_data
*data
= calldata
;
1026 struct nfs_page
*req
= data
->req
;
1027 struct page
*page
= req
->wb_page
;
1028 int status
= data
->task
.tk_status
;
1031 nfs_set_pageerror(page
);
1032 nfs_context_set_write_error(req
->wb_context
, status
);
1033 dprintk(", error = %d\n", status
);
1037 if (nfs_write_need_commit(data
)) {
1038 struct inode
*inode
= page
->mapping
->host
;
1040 spin_lock(&inode
->i_lock
);
1041 if (test_bit(PG_NEED_RESCHED
, &req
->wb_flags
)) {
1042 /* Do nothing we need to resend the writes */
1043 } else if (!test_and_set_bit(PG_NEED_COMMIT
, &req
->wb_flags
)) {
1044 memcpy(&req
->wb_verf
, &data
->verf
, sizeof(req
->wb_verf
));
1045 dprintk(" defer commit\n");
1046 } else if (memcmp(&req
->wb_verf
, &data
->verf
, sizeof(req
->wb_verf
))) {
1047 set_bit(PG_NEED_RESCHED
, &req
->wb_flags
);
1048 clear_bit(PG_NEED_COMMIT
, &req
->wb_flags
);
1049 dprintk(" server reboot detected\n");
1051 spin_unlock(&inode
->i_lock
);
1056 if (atomic_dec_and_test(&req
->wb_complete
))
1057 nfs_writepage_release(req
);
1058 nfs_writedata_release(calldata
);
1061 #if defined(CONFIG_NFS_V4_1)
1062 void nfs_write_prepare(struct rpc_task
*task
, void *calldata
)
1064 struct nfs_write_data
*data
= calldata
;
1065 struct nfs_client
*clp
= (NFS_SERVER(data
->inode
))->nfs_client
;
1067 if (nfs4_setup_sequence(clp
, &data
->args
.seq_args
,
1068 &data
->res
.seq_res
, 1, task
))
1070 rpc_call_start(task
);
1072 #endif /* CONFIG_NFS_V4_1 */
1074 static const struct rpc_call_ops nfs_write_partial_ops
= {
1075 #if defined(CONFIG_NFS_V4_1)
1076 .rpc_call_prepare
= nfs_write_prepare
,
1077 #endif /* CONFIG_NFS_V4_1 */
1078 .rpc_call_done
= nfs_writeback_done_partial
,
1079 .rpc_release
= nfs_writeback_release_partial
,
1083 * Handle a write reply that flushes a whole page.
1085 * FIXME: There is an inherent race with invalidate_inode_pages and
1086 * writebacks since the page->count is kept > 1 for as long
1087 * as the page has a write request pending.
1089 static void nfs_writeback_done_full(struct rpc_task
*task
, void *calldata
)
1091 struct nfs_write_data
*data
= calldata
;
1093 nfs_writeback_done(task
, data
);
1096 static void nfs_writeback_release_full(void *calldata
)
1098 struct nfs_write_data
*data
= calldata
;
1099 int status
= data
->task
.tk_status
;
1101 /* Update attributes as result of writeback. */
1102 while (!list_empty(&data
->pages
)) {
1103 struct nfs_page
*req
= nfs_list_entry(data
->pages
.next
);
1104 struct page
*page
= req
->wb_page
;
1106 nfs_list_remove_request(req
);
1108 dprintk("NFS: %5u write (%s/%lld %d@%lld)",
1110 req
->wb_context
->path
.dentry
->d_inode
->i_sb
->s_id
,
1111 (long long)NFS_FILEID(req
->wb_context
->path
.dentry
->d_inode
),
1113 (long long)req_offset(req
));
1116 nfs_set_pageerror(page
);
1117 nfs_context_set_write_error(req
->wb_context
, status
);
1118 dprintk(", error = %d\n", status
);
1119 goto remove_request
;
1122 if (nfs_write_need_commit(data
)) {
1123 memcpy(&req
->wb_verf
, &data
->verf
, sizeof(req
->wb_verf
));
1124 nfs_mark_request_commit(req
);
1125 nfs_end_page_writeback(page
);
1126 dprintk(" marked for commit\n");
1131 nfs_end_page_writeback(page
);
1132 nfs_inode_remove_request(req
);
1134 nfs_clear_page_tag_locked(req
);
1136 nfs_writedata_release(calldata
);
1139 static const struct rpc_call_ops nfs_write_full_ops
= {
1140 #if defined(CONFIG_NFS_V4_1)
1141 .rpc_call_prepare
= nfs_write_prepare
,
1142 #endif /* CONFIG_NFS_V4_1 */
1143 .rpc_call_done
= nfs_writeback_done_full
,
1144 .rpc_release
= nfs_writeback_release_full
,
1149 * This function is called when the WRITE call is complete.
1151 int nfs_writeback_done(struct rpc_task
*task
, struct nfs_write_data
*data
)
1153 struct nfs_writeargs
*argp
= &data
->args
;
1154 struct nfs_writeres
*resp
= &data
->res
;
1155 struct nfs_server
*server
= NFS_SERVER(data
->inode
);
1158 dprintk("NFS: %5u nfs_writeback_done (status %d)\n",
1159 task
->tk_pid
, task
->tk_status
);
1162 * ->write_done will attempt to use post-op attributes to detect
1163 * conflicting writes by other clients. A strict interpretation
1164 * of close-to-open would allow us to continue caching even if
1165 * another writer had changed the file, but some applications
1166 * depend on tighter cache coherency when writing.
1168 status
= NFS_PROTO(data
->inode
)->write_done(task
, data
);
1171 nfs_add_stats(data
->inode
, NFSIOS_SERVERWRITTENBYTES
, resp
->count
);
1173 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1174 if (resp
->verf
->committed
< argp
->stable
&& task
->tk_status
>= 0) {
1175 /* We tried a write call, but the server did not
1176 * commit data to stable storage even though we
1178 * Note: There is a known bug in Tru64 < 5.0 in which
1179 * the server reports NFS_DATA_SYNC, but performs
1180 * NFS_FILE_SYNC. We therefore implement this checking
1181 * as a dprintk() in order to avoid filling syslog.
1183 static unsigned long complain
;
1185 if (time_before(complain
, jiffies
)) {
1186 dprintk("NFS: faulty NFS server %s:"
1187 " (committed = %d) != (stable = %d)\n",
1188 server
->nfs_client
->cl_hostname
,
1189 resp
->verf
->committed
, argp
->stable
);
1190 complain
= jiffies
+ 300 * HZ
;
1194 /* Is this a short write? */
1195 if (task
->tk_status
>= 0 && resp
->count
< argp
->count
) {
1196 static unsigned long complain
;
1198 nfs_inc_stats(data
->inode
, NFSIOS_SHORTWRITE
);
1200 /* Has the server at least made some progress? */
1201 if (resp
->count
!= 0) {
1202 /* Was this an NFSv2 write or an NFSv3 stable write? */
1203 if (resp
->verf
->committed
!= NFS_UNSTABLE
) {
1204 /* Resend from where the server left off */
1205 argp
->offset
+= resp
->count
;
1206 argp
->pgbase
+= resp
->count
;
1207 argp
->count
-= resp
->count
;
1209 /* Resend as a stable write in order to avoid
1210 * headaches in the case of a server crash.
1212 argp
->stable
= NFS_FILE_SYNC
;
1214 nfs_restart_rpc(task
, server
->nfs_client
);
1217 if (time_before(complain
, jiffies
)) {
1219 "NFS: Server wrote zero bytes, expected %u.\n",
1221 complain
= jiffies
+ 300 * HZ
;
1223 /* Can't do anything about it except throw an error. */
1224 task
->tk_status
= -EIO
;
1230 #if defined(CONFIG_NFS_V3) || defined(CONFIG_NFS_V4)
1231 static void nfs_commitdata_release(void *data
)
1233 struct nfs_write_data
*wdata
= data
;
1235 put_nfs_open_context(wdata
->args
.context
);
1236 nfs_commit_free(wdata
);
1240 * Set up the argument/result storage required for the RPC call.
1242 static int nfs_commit_rpcsetup(struct list_head
*head
,
1243 struct nfs_write_data
*data
,
1246 struct nfs_page
*first
= nfs_list_entry(head
->next
);
1247 struct inode
*inode
= first
->wb_context
->path
.dentry
->d_inode
;
1248 int flags
= (how
& FLUSH_SYNC
) ? 0 : RPC_TASK_ASYNC
;
1249 int priority
= flush_task_priority(how
);
1250 struct rpc_task
*task
;
1251 struct rpc_message msg
= {
1252 .rpc_argp
= &data
->args
,
1253 .rpc_resp
= &data
->res
,
1254 .rpc_cred
= first
->wb_context
->cred
,
1256 struct rpc_task_setup task_setup_data
= {
1257 .task
= &data
->task
,
1258 .rpc_client
= NFS_CLIENT(inode
),
1259 .rpc_message
= &msg
,
1260 .callback_ops
= &nfs_commit_ops
,
1261 .callback_data
= data
,
1262 .workqueue
= nfsiod_workqueue
,
1264 .priority
= priority
,
1267 /* Set up the RPC argument and reply structs
1268 * NB: take care not to mess about with data->commit et al. */
1270 list_splice_init(head
, &data
->pages
);
1272 data
->inode
= inode
;
1273 data
->cred
= msg
.rpc_cred
;
1275 data
->args
.fh
= NFS_FH(data
->inode
);
1276 /* Note: we always request a commit of the entire inode */
1277 data
->args
.offset
= 0;
1278 data
->args
.count
= 0;
1279 data
->args
.context
= get_nfs_open_context(first
->wb_context
);
1280 data
->res
.count
= 0;
1281 data
->res
.fattr
= &data
->fattr
;
1282 data
->res
.verf
= &data
->verf
;
1283 nfs_fattr_init(&data
->fattr
);
1285 /* Set up the initial task struct. */
1286 NFS_PROTO(inode
)->commit_setup(data
, &msg
);
1288 dprintk("NFS: %5u initiated commit call\n", data
->task
.tk_pid
);
1290 task
= rpc_run_task(&task_setup_data
);
1292 return PTR_ERR(task
);
1298 * Commit dirty pages
1301 nfs_commit_list(struct inode
*inode
, struct list_head
*head
, int how
)
1303 struct nfs_write_data
*data
;
1304 struct nfs_page
*req
;
1306 data
= nfs_commitdata_alloc();
1311 /* Set up the argument struct */
1312 return nfs_commit_rpcsetup(head
, data
, how
);
1314 while (!list_empty(head
)) {
1315 req
= nfs_list_entry(head
->next
);
1316 nfs_list_remove_request(req
);
1317 nfs_mark_request_commit(req
);
1318 dec_zone_page_state(req
->wb_page
, NR_UNSTABLE_NFS
);
1319 dec_bdi_stat(req
->wb_page
->mapping
->backing_dev_info
,
1321 nfs_clear_page_tag_locked(req
);
1327 * COMMIT call returned
1329 static void nfs_commit_done(struct rpc_task
*task
, void *calldata
)
1331 struct nfs_write_data
*data
= calldata
;
1333 dprintk("NFS: %5u nfs_commit_done (status %d)\n",
1334 task
->tk_pid
, task
->tk_status
);
1336 /* Call the NFS version-specific code */
1337 if (NFS_PROTO(data
->inode
)->commit_done(task
, data
) != 0)
1341 static void nfs_commit_release(void *calldata
)
1343 struct nfs_write_data
*data
= calldata
;
1344 struct nfs_page
*req
;
1345 int status
= data
->task
.tk_status
;
1347 while (!list_empty(&data
->pages
)) {
1348 req
= nfs_list_entry(data
->pages
.next
);
1349 nfs_list_remove_request(req
);
1350 nfs_clear_request_commit(req
);
1352 dprintk("NFS: commit (%s/%lld %d@%lld)",
1353 req
->wb_context
->path
.dentry
->d_inode
->i_sb
->s_id
,
1354 (long long)NFS_FILEID(req
->wb_context
->path
.dentry
->d_inode
),
1356 (long long)req_offset(req
));
1358 nfs_context_set_write_error(req
->wb_context
, status
);
1359 nfs_inode_remove_request(req
);
1360 dprintk(", error = %d\n", status
);
1364 /* Okay, COMMIT succeeded, apparently. Check the verifier
1365 * returned by the server against all stored verfs. */
1366 if (!memcmp(req
->wb_verf
.verifier
, data
->verf
.verifier
, sizeof(data
->verf
.verifier
))) {
1367 /* We have a match */
1368 nfs_inode_remove_request(req
);
1372 /* We have a mismatch. Write the page again */
1373 dprintk(" mismatch\n");
1374 nfs_mark_request_dirty(req
);
1376 nfs_clear_page_tag_locked(req
);
1378 nfs_commitdata_release(calldata
);
1381 static const struct rpc_call_ops nfs_commit_ops
= {
1382 #if defined(CONFIG_NFS_V4_1)
1383 .rpc_call_prepare
= nfs_write_prepare
,
1384 #endif /* CONFIG_NFS_V4_1 */
1385 .rpc_call_done
= nfs_commit_done
,
1386 .rpc_release
= nfs_commit_release
,
1389 static int nfs_commit_inode(struct inode
*inode
, int how
)
1394 spin_lock(&inode
->i_lock
);
1395 res
= nfs_scan_commit(inode
, &head
, 0, 0);
1396 spin_unlock(&inode
->i_lock
);
1398 int error
= nfs_commit_list(inode
, &head
, how
);
1405 static int nfs_commit_unstable_pages(struct inode
*inode
, struct writeback_control
*wbc
)
1407 struct nfs_inode
*nfsi
= NFS_I(inode
);
1408 int flags
= FLUSH_SYNC
;
1411 /* Don't commit yet if this is a non-blocking flush and there are
1412 * lots of outstanding writes for this mapping.
1414 if (wbc
->sync_mode
== WB_SYNC_NONE
&&
1415 nfsi
->ncommit
<= (nfsi
->npages
>> 1))
1416 goto out_mark_dirty
;
1418 if (wbc
->nonblocking
|| wbc
->for_background
)
1420 ret
= nfs_commit_inode(inode
, flags
);
1422 if (wbc
->sync_mode
== WB_SYNC_NONE
) {
1423 if (ret
< wbc
->nr_to_write
)
1424 wbc
->nr_to_write
-= ret
;
1426 wbc
->nr_to_write
= 0;
1431 __mark_inode_dirty(inode
, I_DIRTY_DATASYNC
);
1435 static inline int nfs_commit_list(struct inode
*inode
, struct list_head
*head
, int how
)
1440 static int nfs_commit_unstable_pages(struct inode
*inode
, struct writeback_control
*wbc
)
1446 int nfs_write_inode(struct inode
*inode
, struct writeback_control
*wbc
)
1448 return nfs_commit_unstable_pages(inode
, wbc
);
1451 long nfs_sync_mapping_wait(struct address_space
*mapping
, struct writeback_control
*wbc
, int how
)
1453 struct inode
*inode
= mapping
->host
;
1454 pgoff_t idx_start
, idx_end
;
1455 unsigned int npages
= 0;
1460 if (wbc
->range_cyclic
)
1463 idx_start
= wbc
->range_start
>> PAGE_CACHE_SHIFT
;
1464 idx_end
= wbc
->range_end
>> PAGE_CACHE_SHIFT
;
1465 if (idx_end
> idx_start
) {
1466 pgoff_t l_npages
= 1 + idx_end
- idx_start
;
1468 if (sizeof(npages
) != sizeof(l_npages
) &&
1469 (pgoff_t
)npages
!= l_npages
)
1473 spin_lock(&inode
->i_lock
);
1475 ret
= nfs_wait_on_requests_locked(inode
, idx_start
, npages
);
1478 pages
= nfs_scan_commit(inode
, &head
, idx_start
, npages
);
1481 pages
+= nfs_scan_commit(inode
, &head
, 0, 0);
1482 spin_unlock(&inode
->i_lock
);
1483 ret
= nfs_commit_list(inode
, &head
, how
);
1484 spin_lock(&inode
->i_lock
);
1487 spin_unlock(&inode
->i_lock
);
1492 * flush the inode to disk.
1494 int nfs_wb_all(struct inode
*inode
)
1496 struct writeback_control wbc
= {
1497 .sync_mode
= WB_SYNC_ALL
,
1498 .nr_to_write
= LONG_MAX
,
1500 .range_end
= LLONG_MAX
,
1503 return sync_inode(inode
, &wbc
);
1506 int nfs_wb_page_cancel(struct inode
*inode
, struct page
*page
)
1508 struct nfs_page
*req
;
1511 BUG_ON(!PageLocked(page
));
1513 req
= nfs_page_find_request(page
);
1516 if (nfs_lock_request_dontget(req
)) {
1517 nfs_inode_remove_request(req
);
1519 * In case nfs_inode_remove_request has marked the
1520 * page as being dirty
1522 cancel_dirty_page(page
, PAGE_CACHE_SIZE
);
1523 nfs_unlock_request(req
);
1526 ret
= nfs_wait_on_request(req
);
1527 nfs_release_request(req
);
1534 static int nfs_wb_page_priority(struct inode
*inode
, struct page
*page
,
1537 loff_t range_start
= page_offset(page
);
1538 loff_t range_end
= range_start
+ (loff_t
)(PAGE_CACHE_SIZE
- 1);
1539 struct writeback_control wbc
= {
1540 .bdi
= page
->mapping
->backing_dev_info
,
1541 .sync_mode
= WB_SYNC_ALL
,
1542 .nr_to_write
= LONG_MAX
,
1543 .range_start
= range_start
,
1544 .range_end
= range_end
,
1549 if (clear_page_dirty_for_io(page
)) {
1550 ret
= nfs_writepage_locked(page
, &wbc
);
1553 } else if (!PagePrivate(page
))
1555 ret
= nfs_sync_mapping_wait(page
->mapping
, &wbc
, how
);
1558 } while (PagePrivate(page
));
1561 __mark_inode_dirty(inode
, I_DIRTY_PAGES
);
1566 * Write back all requests on one page - we do this before reading it.
1568 int nfs_wb_page(struct inode
*inode
, struct page
* page
)
1570 return nfs_wb_page_priority(inode
, page
, FLUSH_STABLE
);
1573 #ifdef CONFIG_MIGRATION
1574 int nfs_migrate_page(struct address_space
*mapping
, struct page
*newpage
,
1577 struct nfs_page
*req
;
1580 nfs_fscache_release_page(page
, GFP_KERNEL
);
1582 req
= nfs_find_and_lock_request(page
);
1587 ret
= migrate_page(mapping
, newpage
, page
);
1592 page_cache_get(newpage
);
1593 spin_lock(&mapping
->host
->i_lock
);
1594 req
->wb_page
= newpage
;
1595 SetPagePrivate(newpage
);
1596 set_page_private(newpage
, (unsigned long)req
);
1597 ClearPagePrivate(page
);
1598 set_page_private(page
, 0);
1599 spin_unlock(&mapping
->host
->i_lock
);
1600 page_cache_release(page
);
1602 nfs_clear_page_tag_locked(req
);
1608 int __init
nfs_init_writepagecache(void)
1610 nfs_wdata_cachep
= kmem_cache_create("nfs_write_data",
1611 sizeof(struct nfs_write_data
),
1612 0, SLAB_HWCACHE_ALIGN
,
1614 if (nfs_wdata_cachep
== NULL
)
1617 nfs_wdata_mempool
= mempool_create_slab_pool(MIN_POOL_WRITE
,
1619 if (nfs_wdata_mempool
== NULL
)
1622 nfs_commit_mempool
= mempool_create_slab_pool(MIN_POOL_COMMIT
,
1624 if (nfs_commit_mempool
== NULL
)
1628 * NFS congestion size, scale with available memory.
1640 * This allows larger machines to have larger/more transfers.
1641 * Limit the default to 256M
1643 nfs_congestion_kb
= (16*int_sqrt(totalram_pages
)) << (PAGE_SHIFT
-10);
1644 if (nfs_congestion_kb
> 256*1024)
1645 nfs_congestion_kb
= 256*1024;
1650 void nfs_destroy_writepagecache(void)
1652 mempool_destroy(nfs_commit_mempool
);
1653 mempool_destroy(nfs_wdata_mempool
);
1654 kmem_cache_destroy(nfs_wdata_cachep
);