1 /* handling of writes to regular files and writing back to the server
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
11 #include <linux/backing-dev.h>
12 #include <linux/slab.h>
14 #include <linux/pagemap.h>
15 #include <linux/writeback.h>
16 #include <linux/pagevec.h>
19 static int afs_write_back_from_locked_page(struct afs_writeback
*wb
,
23 * mark a page as having been made dirty and thus needing writeback
25 int afs_set_page_dirty(struct page
*page
)
28 return __set_page_dirty_nobuffers(page
);
32 * unlink a writeback record because its usage has reached zero
33 * - must be called with the wb->vnode->writeback_lock held
35 static void afs_unlink_writeback(struct afs_writeback
*wb
)
37 struct afs_writeback
*front
;
38 struct afs_vnode
*vnode
= wb
->vnode
;
40 list_del_init(&wb
->link
);
41 if (!list_empty(&vnode
->writebacks
)) {
42 /* if an fsync rises to the front of the queue then wake it
44 front
= list_entry(vnode
->writebacks
.next
,
45 struct afs_writeback
, link
);
46 if (front
->state
== AFS_WBACK_SYNCING
) {
47 _debug("wake up sync");
48 front
->state
= AFS_WBACK_COMPLETE
;
49 wake_up(&front
->waitq
);
55 * free a writeback record
57 static void afs_free_writeback(struct afs_writeback
*wb
)
65 * dispose of a reference to a writeback record
67 void afs_put_writeback(struct afs_writeback
*wb
)
69 struct afs_vnode
*vnode
= wb
->vnode
;
71 _enter("{%d}", wb
->usage
);
73 spin_lock(&vnode
->writeback_lock
);
75 afs_unlink_writeback(wb
);
78 spin_unlock(&vnode
->writeback_lock
);
80 afs_free_writeback(wb
);
84 * partly or wholly fill a page that's under preparation for writing
86 static int afs_fill_page(struct afs_vnode
*vnode
, struct key
*key
,
87 loff_t pos
, unsigned int len
, struct page
*page
)
92 _enter(",,%llu", (unsigned long long)pos
);
94 req
= kzalloc(sizeof(struct afs_read
) + sizeof(struct page
*),
99 atomic_set(&req
->usage
, 1);
103 req
->pages
[0] = page
;
106 ret
= afs_vnode_fetch_data(vnode
, key
, req
);
109 if (ret
== -ENOENT
) {
110 _debug("got NOENT from server"
111 " - marking file deleted and stale");
112 set_bit(AFS_VNODE_DELETED
, &vnode
->flags
);
117 _leave(" = %d", ret
);
122 * prepare to perform part of a write to a page
124 int afs_write_begin(struct file
*file
, struct address_space
*mapping
,
125 loff_t pos
, unsigned len
, unsigned flags
,
126 struct page
**pagep
, void **fsdata
)
128 struct afs_writeback
*candidate
, *wb
;
129 struct afs_vnode
*vnode
= AFS_FS_I(file_inode(file
));
131 struct key
*key
= file
->private_data
;
132 unsigned from
= pos
& (PAGE_SIZE
- 1);
133 unsigned to
= from
+ len
;
134 pgoff_t index
= pos
>> PAGE_SHIFT
;
137 _enter("{%x:%u},{%lx},%u,%u",
138 vnode
->fid
.vid
, vnode
->fid
.vnode
, index
, from
, to
);
140 candidate
= kzalloc(sizeof(*candidate
), GFP_KERNEL
);
143 candidate
->vnode
= vnode
;
144 candidate
->first
= candidate
->last
= index
;
145 candidate
->offset_first
= from
;
146 candidate
->to_last
= to
;
147 INIT_LIST_HEAD(&candidate
->link
);
148 candidate
->usage
= 1;
149 candidate
->state
= AFS_WBACK_PENDING
;
150 init_waitqueue_head(&candidate
->waitq
);
152 page
= grab_cache_page_write_begin(mapping
, index
, flags
);
158 if (!PageUptodate(page
) && len
!= PAGE_SIZE
) {
159 ret
= afs_fill_page(vnode
, key
, pos
& PAGE_MASK
, PAGE_SIZE
, page
);
164 _leave(" = %d [prep]", ret
);
167 SetPageUptodate(page
);
170 /* page won't leak in error case: it eventually gets cleaned off LRU */
174 spin_lock(&vnode
->writeback_lock
);
176 /* see if this page is already pending a writeback under a suitable key
177 * - if so we can just join onto that one */
178 wb
= (struct afs_writeback
*) page_private(page
);
180 if (wb
->key
== key
&& wb
->state
== AFS_WBACK_PENDING
)
181 goto subsume_in_current_wb
;
182 goto flush_conflicting_wb
;
186 /* see if we can find an already pending writeback that we can
187 * append this page to */
188 list_for_each_entry(wb
, &vnode
->writebacks
, link
) {
189 if (wb
->last
== index
- 1 && wb
->key
== key
&&
190 wb
->state
== AFS_WBACK_PENDING
)
191 goto append_to_previous_wb
;
195 list_add_tail(&candidate
->link
, &vnode
->writebacks
);
196 candidate
->key
= key_get(key
);
197 spin_unlock(&vnode
->writeback_lock
);
198 SetPagePrivate(page
);
199 set_page_private(page
, (unsigned long) candidate
);
200 _leave(" = 0 [new]");
203 subsume_in_current_wb
:
205 ASSERTRANGE(wb
->first
, <=, index
, <=, wb
->last
);
206 if (index
== wb
->first
&& from
< wb
->offset_first
)
207 wb
->offset_first
= from
;
208 if (index
== wb
->last
&& to
> wb
->to_last
)
210 spin_unlock(&vnode
->writeback_lock
);
212 _leave(" = 0 [sub]");
215 append_to_previous_wb
:
216 _debug("append into %lx-%lx", wb
->first
, wb
->last
);
220 spin_unlock(&vnode
->writeback_lock
);
221 SetPagePrivate(page
);
222 set_page_private(page
, (unsigned long) wb
);
224 _leave(" = 0 [app]");
227 /* the page is currently bound to another context, so if it's dirty we
228 * need to flush it before we can use the new context */
229 flush_conflicting_wb
:
230 _debug("flush conflict");
231 if (wb
->state
== AFS_WBACK_PENDING
)
232 wb
->state
= AFS_WBACK_CONFLICTING
;
233 spin_unlock(&vnode
->writeback_lock
);
234 if (clear_page_dirty_for_io(page
)) {
235 ret
= afs_write_back_from_locked_page(wb
, page
);
237 afs_put_writeback(candidate
);
238 _leave(" = %d", ret
);
243 /* the page holds a ref on the writeback record */
244 afs_put_writeback(wb
);
245 set_page_private(page
, 0);
246 ClearPagePrivate(page
);
251 * finalise part of a write to a page
253 int afs_write_end(struct file
*file
, struct address_space
*mapping
,
254 loff_t pos
, unsigned len
, unsigned copied
,
255 struct page
*page
, void *fsdata
)
257 struct afs_vnode
*vnode
= AFS_FS_I(file_inode(file
));
258 struct key
*key
= file
->private_data
;
259 loff_t i_size
, maybe_i_size
;
262 _enter("{%x:%u},{%lx}",
263 vnode
->fid
.vid
, vnode
->fid
.vnode
, page
->index
);
265 maybe_i_size
= pos
+ copied
;
267 i_size
= i_size_read(&vnode
->vfs_inode
);
268 if (maybe_i_size
> i_size
) {
269 spin_lock(&vnode
->writeback_lock
);
270 i_size
= i_size_read(&vnode
->vfs_inode
);
271 if (maybe_i_size
> i_size
)
272 i_size_write(&vnode
->vfs_inode
, maybe_i_size
);
273 spin_unlock(&vnode
->writeback_lock
);
276 if (!PageUptodate(page
)) {
278 /* Try and load any missing data from the server. The
279 * unmarshalling routine will take care of clearing any
280 * bits that are beyond the EOF.
282 ret
= afs_fill_page(vnode
, key
, pos
+ copied
,
287 SetPageUptodate(page
);
290 set_page_dirty(page
);
300 * kill all the pages in the given range
302 static void afs_kill_pages(struct afs_vnode
*vnode
, bool error
,
303 pgoff_t first
, pgoff_t last
)
306 unsigned count
, loop
;
308 _enter("{%x:%u},%lx-%lx",
309 vnode
->fid
.vid
, vnode
->fid
.vnode
, first
, last
);
311 pagevec_init(&pv
, 0);
314 _debug("kill %lx-%lx", first
, last
);
316 count
= last
- first
+ 1;
317 if (count
> PAGEVEC_SIZE
)
318 count
= PAGEVEC_SIZE
;
319 pv
.nr
= find_get_pages_contig(vnode
->vfs_inode
.i_mapping
,
320 first
, count
, pv
.pages
);
321 ASSERTCMP(pv
.nr
, ==, count
);
323 for (loop
= 0; loop
< count
; loop
++) {
324 struct page
*page
= pv
.pages
[loop
];
325 ClearPageUptodate(page
);
328 if (PageWriteback(page
))
329 end_page_writeback(page
);
330 if (page
->index
>= first
)
331 first
= page
->index
+ 1;
334 __pagevec_release(&pv
);
335 } while (first
< last
);
341 * synchronously write back the locked page and any subsequent non-locked dirty
342 * pages also covered by the same writeback record
344 static int afs_write_back_from_locked_page(struct afs_writeback
*wb
,
345 struct page
*primary_page
)
347 struct page
*pages
[8], *page
;
349 unsigned n
, offset
, to
;
350 pgoff_t start
, first
, last
;
353 _enter(",%lx", primary_page
->index
);
356 if (test_set_page_writeback(primary_page
))
359 /* find all consecutive lockable dirty pages, stopping when we find a
360 * page that is not immediately lockable, is not dirty or is missing,
361 * or we reach the end of the range */
362 start
= primary_page
->index
;
363 if (start
>= wb
->last
)
367 _debug("more %lx [%lx]", start
, count
);
368 n
= wb
->last
- start
+ 1;
369 if (n
> ARRAY_SIZE(pages
))
370 n
= ARRAY_SIZE(pages
);
371 n
= find_get_pages_contig(wb
->vnode
->vfs_inode
.i_mapping
,
373 _debug("fgpc %u", n
);
376 if (pages
[0]->index
!= start
) {
378 put_page(pages
[--n
]);
383 for (loop
= 0; loop
< n
; loop
++) {
385 if (page
->index
> wb
->last
)
387 if (!trylock_page(page
))
389 if (!PageDirty(page
) ||
390 page_private(page
) != (unsigned long) wb
) {
394 if (!clear_page_dirty_for_io(page
))
396 if (test_set_page_writeback(page
))
403 for (; loop
< n
; loop
++)
404 put_page(pages
[loop
]);
409 } while (start
<= wb
->last
&& count
< 65536);
412 /* we now have a contiguous set of dirty pages, each with writeback set
413 * and the dirty mark cleared; the first page is locked and must remain
414 * so, all the rest are unlocked */
415 first
= primary_page
->index
;
416 last
= first
+ count
- 1;
418 offset
= (first
== wb
->first
) ? wb
->offset_first
: 0;
419 to
= (last
== wb
->last
) ? wb
->to_last
: PAGE_SIZE
;
421 _debug("write back %lx[%u..] to %lx[..%u]", first
, offset
, last
, to
);
423 ret
= afs_vnode_store_data(wb
, first
, last
, offset
, to
);
428 mapping_set_error(wb
->vnode
->vfs_inode
.i_mapping
, -ENOSPC
);
437 afs_kill_pages(wb
->vnode
, true, first
, last
);
438 mapping_set_error(wb
->vnode
->vfs_inode
.i_mapping
, -EIO
);
446 afs_kill_pages(wb
->vnode
, false, first
, last
);
455 _leave(" = %d", ret
);
460 * write a page back to the server
461 * - the caller locked the page for us
463 int afs_writepage(struct page
*page
, struct writeback_control
*wbc
)
465 struct afs_writeback
*wb
;
468 _enter("{%lx},", page
->index
);
470 wb
= (struct afs_writeback
*) page_private(page
);
473 ret
= afs_write_back_from_locked_page(wb
, page
);
476 _leave(" = %d", ret
);
480 wbc
->nr_to_write
-= ret
;
487 * write a region of pages back to the server
489 static int afs_writepages_region(struct address_space
*mapping
,
490 struct writeback_control
*wbc
,
491 pgoff_t index
, pgoff_t end
, pgoff_t
*_next
)
493 struct afs_writeback
*wb
;
497 _enter(",,%lx,%lx,", index
, end
);
500 n
= find_get_pages_tag(mapping
, &index
, PAGECACHE_TAG_DIRTY
,
505 _debug("wback %lx", page
->index
);
507 if (page
->index
> end
) {
510 _leave(" = 0 [%lx]", *_next
);
514 /* at this point we hold neither mapping->tree_lock nor lock on
515 * the page itself: the page may be truncated or invalidated
516 * (changing page->mapping to NULL), or even swizzled back from
517 * swapper_space to tmpfs file mapping
521 if (page
->mapping
!= mapping
|| !PageDirty(page
)) {
527 if (PageWriteback(page
)) {
529 if (wbc
->sync_mode
!= WB_SYNC_NONE
)
530 wait_on_page_writeback(page
);
535 wb
= (struct afs_writeback
*) page_private(page
);
538 spin_lock(&wb
->vnode
->writeback_lock
);
539 wb
->state
= AFS_WBACK_WRITING
;
540 spin_unlock(&wb
->vnode
->writeback_lock
);
542 if (!clear_page_dirty_for_io(page
))
544 ret
= afs_write_back_from_locked_page(wb
, page
);
548 _leave(" = %d", ret
);
552 wbc
->nr_to_write
-= ret
;
555 } while (index
< end
&& wbc
->nr_to_write
> 0);
558 _leave(" = 0 [%lx]", *_next
);
563 * write some of the pending data back to the server
565 int afs_writepages(struct address_space
*mapping
,
566 struct writeback_control
*wbc
)
568 pgoff_t start
, end
, next
;
573 if (wbc
->range_cyclic
) {
574 start
= mapping
->writeback_index
;
576 ret
= afs_writepages_region(mapping
, wbc
, start
, end
, &next
);
577 if (start
> 0 && wbc
->nr_to_write
> 0 && ret
== 0)
578 ret
= afs_writepages_region(mapping
, wbc
, 0, start
,
580 mapping
->writeback_index
= next
;
581 } else if (wbc
->range_start
== 0 && wbc
->range_end
== LLONG_MAX
) {
582 end
= (pgoff_t
)(LLONG_MAX
>> PAGE_SHIFT
);
583 ret
= afs_writepages_region(mapping
, wbc
, 0, end
, &next
);
584 if (wbc
->nr_to_write
> 0)
585 mapping
->writeback_index
= next
;
587 start
= wbc
->range_start
>> PAGE_SHIFT
;
588 end
= wbc
->range_end
>> PAGE_SHIFT
;
589 ret
= afs_writepages_region(mapping
, wbc
, start
, end
, &next
);
592 _leave(" = %d", ret
);
597 * completion of write to server
599 void afs_pages_written_back(struct afs_vnode
*vnode
, struct afs_call
*call
)
601 struct afs_writeback
*wb
= call
->wb
;
603 unsigned count
, loop
;
604 pgoff_t first
= call
->first
, last
= call
->last
;
607 _enter("{%x:%u},{%lx-%lx}",
608 vnode
->fid
.vid
, vnode
->fid
.vnode
, first
, last
);
612 pagevec_init(&pv
, 0);
615 _debug("done %lx-%lx", first
, last
);
617 count
= last
- first
+ 1;
618 if (count
> PAGEVEC_SIZE
)
619 count
= PAGEVEC_SIZE
;
620 pv
.nr
= find_get_pages_contig(call
->mapping
, first
, count
,
622 ASSERTCMP(pv
.nr
, ==, count
);
624 spin_lock(&vnode
->writeback_lock
);
625 for (loop
= 0; loop
< count
; loop
++) {
626 struct page
*page
= pv
.pages
[loop
];
627 end_page_writeback(page
);
628 if (page_private(page
) == (unsigned long) wb
) {
629 set_page_private(page
, 0);
630 ClearPagePrivate(page
);
635 if (wb
->usage
== 0) {
636 afs_unlink_writeback(wb
);
639 spin_unlock(&vnode
->writeback_lock
);
642 afs_free_writeback(wb
);
646 __pagevec_release(&pv
);
647 } while (first
<= last
);
653 * write to an AFS file
655 ssize_t
afs_file_write(struct kiocb
*iocb
, struct iov_iter
*from
)
657 struct afs_vnode
*vnode
= AFS_FS_I(file_inode(iocb
->ki_filp
));
659 size_t count
= iov_iter_count(from
);
661 _enter("{%x.%u},{%zu},",
662 vnode
->fid
.vid
, vnode
->fid
.vnode
, count
);
664 if (IS_SWAPFILE(&vnode
->vfs_inode
)) {
666 "AFS: Attempt to write to active swap file!\n");
673 result
= generic_file_write_iter(iocb
, from
);
675 _leave(" = %zd", result
);
680 * flush the vnode to the fileserver
682 int afs_writeback_all(struct afs_vnode
*vnode
)
684 struct address_space
*mapping
= vnode
->vfs_inode
.i_mapping
;
685 struct writeback_control wbc
= {
686 .sync_mode
= WB_SYNC_ALL
,
687 .nr_to_write
= LONG_MAX
,
694 ret
= mapping
->a_ops
->writepages(mapping
, &wbc
);
695 __mark_inode_dirty(mapping
->host
, I_DIRTY_PAGES
);
697 _leave(" = %d", ret
);
702 * flush any dirty pages for this process, and check for write errors.
703 * - the return status from this call provides a reliable indication of
704 * whether any write errors occurred for this process.
706 int afs_fsync(struct file
*file
, loff_t start
, loff_t end
, int datasync
)
708 struct inode
*inode
= file_inode(file
);
709 struct afs_writeback
*wb
, *xwb
;
710 struct afs_vnode
*vnode
= AFS_FS_I(inode
);
713 _enter("{%x:%u},{n=%pD},%d",
714 vnode
->fid
.vid
, vnode
->fid
.vnode
, file
,
717 ret
= filemap_write_and_wait_range(inode
->i_mapping
, start
, end
);
722 /* use a writeback record as a marker in the queue - when this reaches
723 * the front of the queue, all the outstanding writes are either
724 * completed or rejected */
725 wb
= kzalloc(sizeof(*wb
), GFP_KERNEL
);
733 wb
->offset_first
= 0;
734 wb
->to_last
= PAGE_SIZE
;
736 wb
->state
= AFS_WBACK_SYNCING
;
737 init_waitqueue_head(&wb
->waitq
);
739 spin_lock(&vnode
->writeback_lock
);
740 list_for_each_entry(xwb
, &vnode
->writebacks
, link
) {
741 if (xwb
->state
== AFS_WBACK_PENDING
)
742 xwb
->state
= AFS_WBACK_CONFLICTING
;
744 list_add_tail(&wb
->link
, &vnode
->writebacks
);
745 spin_unlock(&vnode
->writeback_lock
);
747 /* push all the outstanding writebacks to the server */
748 ret
= afs_writeback_all(vnode
);
750 afs_put_writeback(wb
);
751 _leave(" = %d [wb]", ret
);
755 /* wait for the preceding writes to actually complete */
756 ret
= wait_event_interruptible(wb
->waitq
,
757 wb
->state
== AFS_WBACK_COMPLETE
||
758 vnode
->writebacks
.next
== &wb
->link
);
759 afs_put_writeback(wb
);
760 _leave(" = %d", ret
);
767 * Flush out all outstanding writes on a file opened for writing when it is
770 int afs_flush(struct file
*file
, fl_owner_t id
)
774 if ((file
->f_mode
& FMODE_WRITE
) == 0)
777 return vfs_fsync(file
, 0);
781 * notification that a previously read-only page is about to become writable
782 * - if it returns an error, the caller will deliver a bus error signal
784 int afs_page_mkwrite(struct vm_area_struct
*vma
, struct page
*page
)
786 struct afs_vnode
*vnode
= AFS_FS_I(vma
->vm_file
->f_mapping
->host
);
788 _enter("{{%x:%u}},{%lx}",
789 vnode
->fid
.vid
, vnode
->fid
.vnode
, page
->index
);
791 /* wait for the page to be written to the cache before we allow it to
793 #ifdef CONFIG_AFS_FSCACHE
794 fscache_wait_on_page_write(vnode
->cache
, page
);