blob: 28f320fac4d4261ec8626d0cfe221be83778c20e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/buffer.c
3 *
4 * Copyright (C) 1991, 1992, 2002 Linus Torvalds
5 */
6
7/*
8 * Start bdflush() with kernel_thread not syscall - Paul Gortmaker, 12/95
9 *
10 * Removed a lot of unnecessary code and simplified things now that
11 * the buffer cache isn't our primary cache - Andrew Tridgell 12/96
12 *
13 * Speed up hash, lru, and free list operations. Use gfp() for allocating
14 * hash table, use SLAB cache for buffer heads. SMP threading. -DaveM
15 *
16 * Added 32k buffer block sizes - these are required older ARM systems. - RMK
17 *
18 * async buffer flushing, 1999 Andrea Arcangeli <andrea@suse.de>
19 */
20
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/kernel.h>
22#include <linux/syscalls.h>
23#include <linux/fs.h>
24#include <linux/mm.h>
25#include <linux/percpu.h>
26#include <linux/slab.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080027#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/blkdev.h>
29#include <linux/file.h>
30#include <linux/quotaops.h>
31#include <linux/highmem.h>
32#include <linux/module.h>
33#include <linux/writeback.h>
34#include <linux/hash.h>
35#include <linux/suspend.h>
36#include <linux/buffer_head.h>
Andrew Morton55e829a2006-12-10 02:19:27 -080037#include <linux/task_io_accounting_ops.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038#include <linux/bio.h>
39#include <linux/notifier.h>
40#include <linux/cpu.h>
41#include <linux/bitops.h>
42#include <linux/mpage.h>
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070043#include <linux/bit_spinlock.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044
45static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47#define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
48
49inline void
50init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
51{
52 bh->b_end_io = handler;
53 bh->b_private = private;
54}
55
56static int sync_buffer(void *word)
57{
58 struct block_device *bd;
59 struct buffer_head *bh
60 = container_of(word, struct buffer_head, b_state);
61
62 smp_mb();
63 bd = bh->b_bdev;
64 if (bd)
65 blk_run_address_space(bd->bd_inode->i_mapping);
66 io_schedule();
67 return 0;
68}
69
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080070void __lock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070071{
72 wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer,
73 TASK_UNINTERRUPTIBLE);
74}
75EXPORT_SYMBOL(__lock_buffer);
76
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -080077void unlock_buffer(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -070078{
Nick Piggin51b07fc2008-10-18 20:27:00 -070079 clear_bit_unlock(BH_Lock, &bh->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080 smp_mb__after_clear_bit();
81 wake_up_bit(&bh->b_state, BH_Lock);
82}
83
84/*
85 * Block until a buffer comes unlocked. This doesn't stop it
86 * from becoming locked again - you have to lock it yourself
87 * if you want to preserve its state.
88 */
89void __wait_on_buffer(struct buffer_head * bh)
90{
91 wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE);
92}
93
94static void
95__clear_page_buffers(struct page *page)
96{
97 ClearPagePrivate(page);
Hugh Dickins4c21e2f2005-10-29 18:16:40 -070098 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 page_cache_release(page);
100}
101
Keith Mannthey08bafc02008-11-25 10:24:35 +0100102
103static int quiet_error(struct buffer_head *bh)
104{
105 if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
106 return 0;
107 return 1;
108}
109
110
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111static void buffer_io_error(struct buffer_head *bh)
112{
113 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
115 bdevname(bh->b_bdev, b),
116 (unsigned long long)bh->b_blocknr);
117}
118
119/*
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700120 * End-of-IO handler helper function which does not touch the bh after
121 * unlocking it.
122 * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
123 * a race there is benign: unlock_buffer() only use the bh's address for
124 * hashing after unlocking the buffer, so it doesn't actually touch the bh
125 * itself.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 */
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700127static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128{
129 if (uptodate) {
130 set_buffer_uptodate(bh);
131 } else {
132 /* This happens, due to failed READA attempts. */
133 clear_buffer_uptodate(bh);
134 }
135 unlock_buffer(bh);
Dmitry Monakhov68671f32007-10-16 01:24:47 -0700136}
137
138/*
139 * Default synchronous end-of-IO handler.. Just mark it up-to-date and
140 * unlock the buffer. This is what ll_rw_block uses too.
141 */
142void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
143{
144 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145 put_bh(bh);
146}
147
148void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
149{
150 char b[BDEVNAME_SIZE];
151
152 if (uptodate) {
153 set_buffer_uptodate(bh);
154 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100155 if (!buffer_eopnotsupp(bh) && !quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 buffer_io_error(bh);
157 printk(KERN_WARNING "lost page write due to "
158 "I/O error on %s\n",
159 bdevname(bh->b_bdev, b));
160 }
161 set_buffer_write_io_error(bh);
162 clear_buffer_uptodate(bh);
163 }
164 unlock_buffer(bh);
165 put_bh(bh);
166}
167
168/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 * Various filesystems appear to want __find_get_block to be non-blocking.
170 * But it's the page lock which protects the buffers. To get around this,
171 * we get exclusion from try_to_free_buffers with the blockdev mapping's
172 * private_lock.
173 *
174 * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
175 * may be quite high. This code could TryLock the page, and if that
176 * succeeds, there is no need to take private_lock. (But if
177 * private_lock is contended then so is mapping->tree_lock).
178 */
179static struct buffer_head *
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -0800180__find_get_block_slow(struct block_device *bdev, sector_t block)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181{
182 struct inode *bd_inode = bdev->bd_inode;
183 struct address_space *bd_mapping = bd_inode->i_mapping;
184 struct buffer_head *ret = NULL;
185 pgoff_t index;
186 struct buffer_head *bh;
187 struct buffer_head *head;
188 struct page *page;
189 int all_mapped = 1;
190
191 index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
192 page = find_get_page(bd_mapping, index);
193 if (!page)
194 goto out;
195
196 spin_lock(&bd_mapping->private_lock);
197 if (!page_has_buffers(page))
198 goto out_unlock;
199 head = page_buffers(page);
200 bh = head;
201 do {
Nikanth Karthikesan97f76d32009-04-02 16:56:46 -0700202 if (!buffer_mapped(bh))
203 all_mapped = 0;
204 else if (bh->b_blocknr == block) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 ret = bh;
206 get_bh(bh);
207 goto out_unlock;
208 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 bh = bh->b_this_page;
210 } while (bh != head);
211
212 /* we might be here because some of the buffers on this page are
213 * not mapped. This is due to various races between
214 * file io on the block device and getblk. It gets dealt with
215 * elsewhere, don't buffer_error if we had some unmapped buffers
216 */
217 if (all_mapped) {
218 printk("__find_get_block_slow() failed. "
219 "block=%llu, b_blocknr=%llu\n",
Badari Pulavarty205f87f2006-03-26 01:38:00 -0800220 (unsigned long long)block,
221 (unsigned long long)bh->b_blocknr);
222 printk("b_state=0x%08lx, b_size=%zu\n",
223 bh->b_state, bh->b_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits);
225 }
226out_unlock:
227 spin_unlock(&bd_mapping->private_lock);
228 page_cache_release(page);
229out:
230 return ret;
231}
232
233/* If invalidate_buffers() will trash dirty buffers, it means some kind
234 of fs corruption is going on. Trashing dirty data always imply losing
235 information that was supposed to be just stored on the physical layer
236 by the user.
237
238 Thus invalidate_buffers in general usage is not allwowed to trash
239 dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to
240 be preserved. These buffers are simply skipped.
241
242 We also skip buffers which are still in use. For example this can
243 happen if a userspace program is reading the block device.
244
245 NOTE: In the case where the user removed a removable-media-disk even if
246 there's still dirty data not synced on disk (due a bug in the device driver
247 or due an error of the user), by not destroying the dirty buffers we could
248 generate corruption also on the next media inserted, thus a parameter is
249 necessary to handle this case in the most safe way possible (trying
250 to not corrupt also the new disk inserted with the data belonging to
251 the old now corrupted disk). Also for the ramdisk the natural thing
252 to do in order to release the ramdisk memory is to destroy dirty buffers.
253
254 These are two special cases. Normal usage imply the device driver
255 to issue a sync on the device (without waiting I/O completion) and
256 then an invalidate_buffers call that doesn't trash dirty buffers.
257
258 For handling cache coherency with the blkdev pagecache the 'update' case
259 is been introduced. It is needed to re-read from disk any pinned
260 buffer. NOTE: re-reading from disk is destructive so we can do it only
261 when we assume nobody is changing the buffercache under our I/O and when
262 we think the disk contains more recent information than the buffercache.
263 The update == 1 pass marks the buffers we need to update, the update == 2
264 pass does the actual I/O. */
Peter Zijlstraf98393a2007-05-06 14:49:54 -0700265void invalidate_bdev(struct block_device *bdev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266{
Andrew Morton0e1dfc62006-07-30 03:03:28 -0700267 struct address_space *mapping = bdev->bd_inode->i_mapping;
268
269 if (mapping->nrpages == 0)
270 return;
271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 invalidate_bh_lrus();
Andrew Mortonfc0ecff2007-02-10 01:45:39 -0800273 invalidate_mapping_pages(mapping, 0, -1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274}
275
276/*
277 * Kick pdflush then try to free up some ZONE_NORMAL memory.
278 */
279static void free_more_memory(void)
280{
Mel Gorman19770b32008-04-28 02:12:18 -0700281 struct zone *zone;
Mel Gorman0e884602008-04-28 02:12:14 -0700282 int nid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283
Pekka J Enberg687a21c2005-06-28 20:44:55 -0700284 wakeup_pdflush(1024);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 yield();
286
Mel Gorman0e884602008-04-28 02:12:14 -0700287 for_each_online_node(nid) {
Mel Gorman19770b32008-04-28 02:12:18 -0700288 (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
289 gfp_zone(GFP_NOFS), NULL,
290 &zone);
291 if (zone)
Mel Gorman54a6eb52008-04-28 02:12:16 -0700292 try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
KAMEZAWA Hiroyuki327c0e92009-03-31 15:23:31 -0700293 GFP_NOFS, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 }
295}
296
297/*
298 * I/O completion handler for block_read_full_page() - pages
299 * which come unlocked at the end of I/O.
300 */
301static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
302{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700304 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 struct buffer_head *tmp;
306 struct page *page;
307 int page_uptodate = 1;
308
309 BUG_ON(!buffer_async_read(bh));
310
311 page = bh->b_page;
312 if (uptodate) {
313 set_buffer_uptodate(bh);
314 } else {
315 clear_buffer_uptodate(bh);
Keith Mannthey08bafc02008-11-25 10:24:35 +0100316 if (!quiet_error(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 buffer_io_error(bh);
318 SetPageError(page);
319 }
320
321 /*
322 * Be _very_ careful from here on. Bad things can happen if
323 * two buffer heads end IO at almost the same time and both
324 * decide that the page is now completely done.
325 */
Nick Piggina3972202005-07-07 17:56:56 -0700326 first = page_buffers(page);
327 local_irq_save(flags);
328 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 clear_buffer_async_read(bh);
330 unlock_buffer(bh);
331 tmp = bh;
332 do {
333 if (!buffer_uptodate(tmp))
334 page_uptodate = 0;
335 if (buffer_async_read(tmp)) {
336 BUG_ON(!buffer_locked(tmp));
337 goto still_busy;
338 }
339 tmp = tmp->b_this_page;
340 } while (tmp != bh);
Nick Piggina3972202005-07-07 17:56:56 -0700341 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
342 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343
344 /*
345 * If none of the buffers had errors and they are all
346 * uptodate then we can set the page uptodate.
347 */
348 if (page_uptodate && !PageError(page))
349 SetPageUptodate(page);
350 unlock_page(page);
351 return;
352
353still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700354 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
355 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356 return;
357}
358
359/*
360 * Completion handler for block_write_full_page() - pages which are unlocked
361 * during I/O, and which have PageWriteback cleared upon I/O completion.
362 */
Chris Mason35c80d52009-04-15 13:22:38 -0400363void end_buffer_async_write(struct buffer_head *bh, int uptodate)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364{
365 char b[BDEVNAME_SIZE];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 unsigned long flags;
Nick Piggina3972202005-07-07 17:56:56 -0700367 struct buffer_head *first;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 struct buffer_head *tmp;
369 struct page *page;
370
371 BUG_ON(!buffer_async_write(bh));
372
373 page = bh->b_page;
374 if (uptodate) {
375 set_buffer_uptodate(bh);
376 } else {
Keith Mannthey08bafc02008-11-25 10:24:35 +0100377 if (!quiet_error(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 buffer_io_error(bh);
379 printk(KERN_WARNING "lost page write due to "
380 "I/O error on %s\n",
381 bdevname(bh->b_bdev, b));
382 }
383 set_bit(AS_EIO, &page->mapping->flags);
Jan Kara58ff4072006-10-17 00:10:19 -0700384 set_buffer_write_io_error(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 clear_buffer_uptodate(bh);
386 SetPageError(page);
387 }
388
Nick Piggina3972202005-07-07 17:56:56 -0700389 first = page_buffers(page);
390 local_irq_save(flags);
391 bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
392
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 clear_buffer_async_write(bh);
394 unlock_buffer(bh);
395 tmp = bh->b_this_page;
396 while (tmp != bh) {
397 if (buffer_async_write(tmp)) {
398 BUG_ON(!buffer_locked(tmp));
399 goto still_busy;
400 }
401 tmp = tmp->b_this_page;
402 }
Nick Piggina3972202005-07-07 17:56:56 -0700403 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
404 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 end_page_writeback(page);
406 return;
407
408still_busy:
Nick Piggina3972202005-07-07 17:56:56 -0700409 bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
410 local_irq_restore(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 return;
412}
413
414/*
415 * If a page's buffers are under async readin (end_buffer_async_read
416 * completion) then there is a possibility that another thread of
417 * control could lock one of the buffers after it has completed
418 * but while some of the other buffers have not completed. This
419 * locked buffer would confuse end_buffer_async_read() into not unlocking
420 * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
421 * that this buffer is not under async I/O.
422 *
423 * The page comes unlocked when it has no locked buffer_async buffers
424 * left.
425 *
426 * PageLocked prevents anyone starting new async I/O reads any of
427 * the buffers.
428 *
429 * PageWriteback is used to prevent simultaneous writeout of the same
430 * page.
431 *
432 * PageLocked prevents anyone from starting writeback of a page which is
433 * under read I/O (PageWriteback is only ever set against a locked page).
434 */
435static void mark_buffer_async_read(struct buffer_head *bh)
436{
437 bh->b_end_io = end_buffer_async_read;
438 set_buffer_async_read(bh);
439}
440
Chris Mason35c80d52009-04-15 13:22:38 -0400441void mark_buffer_async_write_endio(struct buffer_head *bh,
442 bh_end_io_t *handler)
443{
444 bh->b_end_io = handler;
445 set_buffer_async_write(bh);
446}
447
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448void mark_buffer_async_write(struct buffer_head *bh)
449{
Chris Mason35c80d52009-04-15 13:22:38 -0400450 mark_buffer_async_write_endio(bh, end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451}
452EXPORT_SYMBOL(mark_buffer_async_write);
453
454
455/*
456 * fs/buffer.c contains helper functions for buffer-backed address space's
457 * fsync functions. A common requirement for buffer-based filesystems is
458 * that certain data from the backing blockdev needs to be written out for
459 * a successful fsync(). For example, ext2 indirect blocks need to be
460 * written back and waited upon before fsync() returns.
461 *
462 * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
463 * inode_has_buffers() and invalidate_inode_buffers() are provided for the
464 * management of a list of dependent buffers at ->i_mapping->private_list.
465 *
466 * Locking is a little subtle: try_to_free_buffers() will remove buffers
467 * from their controlling inode's queue when they are being freed. But
468 * try_to_free_buffers() will be operating against the *blockdev* mapping
469 * at the time, not against the S_ISREG file which depends on those buffers.
470 * So the locking for private_list is via the private_lock in the address_space
471 * which backs the buffers. Which is different from the address_space
472 * against which the buffers are listed. So for a particular address_space,
473 * mapping->private_lock does *not* protect mapping->private_list! In fact,
474 * mapping->private_list will always be protected by the backing blockdev's
475 * ->private_lock.
476 *
477 * Which introduces a requirement: all buffers on an address_space's
478 * ->private_list must be from the same address_space: the blockdev's.
479 *
480 * address_spaces which do not place buffers at ->private_list via these
481 * utility functions are free to use private_lock and private_list for
482 * whatever they want. The only requirement is that list_empty(private_list)
483 * be true at clear_inode() time.
484 *
485 * FIXME: clear_inode should not call invalidate_inode_buffers(). The
486 * filesystems should do that. invalidate_inode_buffers() should just go
487 * BUG_ON(!list_empty).
488 *
489 * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
490 * take an address_space, not an inode. And it should be called
491 * mark_buffer_dirty_fsync() to clearly define why those buffers are being
492 * queued up.
493 *
494 * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
495 * list if it is already on a list. Because if the buffer is on a list,
496 * it *must* already be on the right one. If not, the filesystem is being
497 * silly. This will save a ton of locking. But first we have to ensure
498 * that buffers are taken *off* the old inode's list when they are freed
499 * (presumably in truncate). That requires careful auditing of all
500 * filesystems (do it inside bforget()). It could also be done by bringing
501 * b_inode back.
502 */
503
504/*
505 * The buffer's backing address_space's private_lock must be held
506 */
Thomas Petazzonidbacefc2008-07-29 22:33:47 -0700507static void __remove_assoc_queue(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508{
509 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -0700510 WARN_ON(!bh->b_assoc_map);
511 if (buffer_write_io_error(bh))
512 set_bit(AS_EIO, &bh->b_assoc_map->flags);
513 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514}
515
516int inode_has_buffers(struct inode *inode)
517{
518 return !list_empty(&inode->i_data.private_list);
519}
520
521/*
522 * osync is designed to support O_SYNC io. It waits synchronously for
523 * all already-submitted IO to complete, but does not queue any new
524 * writes to the disk.
525 *
526 * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
527 * you dirty the buffers, and then use osync_inode_buffers to wait for
528 * completion. Any other dirty buffers which are not yet queued for
529 * write will not be flushed to disk by the osync.
530 */
531static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
532{
533 struct buffer_head *bh;
534 struct list_head *p;
535 int err = 0;
536
537 spin_lock(lock);
538repeat:
539 list_for_each_prev(p, list) {
540 bh = BH_ENTRY(p);
541 if (buffer_locked(bh)) {
542 get_bh(bh);
543 spin_unlock(lock);
544 wait_on_buffer(bh);
545 if (!buffer_uptodate(bh))
546 err = -EIO;
547 brelse(bh);
548 spin_lock(lock);
549 goto repeat;
550 }
551 }
552 spin_unlock(lock);
553 return err;
554}
555
Jens Axboe053c5252009-04-08 13:44:08 +0200556void do_thaw_all(struct work_struct *work)
Eric Sandeenc2d75432009-03-31 15:23:46 -0700557{
558 struct super_block *sb;
559 char b[BDEVNAME_SIZE];
560
561 spin_lock(&sb_lock);
562restart:
563 list_for_each_entry(sb, &super_blocks, s_list) {
564 sb->s_count++;
565 spin_unlock(&sb_lock);
566 down_read(&sb->s_umount);
567 while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
568 printk(KERN_WARNING "Emergency Thaw on %s\n",
569 bdevname(sb->s_bdev, b));
570 up_read(&sb->s_umount);
571 spin_lock(&sb_lock);
572 if (__put_super_and_need_restart(sb))
573 goto restart;
574 }
575 spin_unlock(&sb_lock);
Jens Axboe053c5252009-04-08 13:44:08 +0200576 kfree(work);
Eric Sandeenc2d75432009-03-31 15:23:46 -0700577 printk(KERN_WARNING "Emergency Thaw complete\n");
578}
579
580/**
581 * emergency_thaw_all -- forcibly thaw every frozen filesystem
582 *
583 * Used for emergency unfreeze of all filesystems via SysRq
584 */
585void emergency_thaw_all(void)
586{
Jens Axboe053c5252009-04-08 13:44:08 +0200587 struct work_struct *work;
588
589 work = kmalloc(sizeof(*work), GFP_ATOMIC);
590 if (work) {
591 INIT_WORK(work, do_thaw_all);
592 schedule_work(work);
593 }
Eric Sandeenc2d75432009-03-31 15:23:46 -0700594}
595
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596/**
Randy Dunlap78a4a502008-02-29 22:02:31 -0800597 * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
Martin Waitz67be2dd2005-05-01 08:59:26 -0700598 * @mapping: the mapping which wants those buffers written
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 *
600 * Starts I/O against the buffers at mapping->private_list, and waits upon
601 * that I/O.
602 *
Martin Waitz67be2dd2005-05-01 08:59:26 -0700603 * Basically, this is a convenience function for fsync().
604 * @mapping is a file or directory which needs those buffers to be written for
605 * a successful fsync().
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 */
607int sync_mapping_buffers(struct address_space *mapping)
608{
609 struct address_space *buffer_mapping = mapping->assoc_mapping;
610
611 if (buffer_mapping == NULL || list_empty(&mapping->private_list))
612 return 0;
613
614 return fsync_buffers_list(&buffer_mapping->private_lock,
615 &mapping->private_list);
616}
617EXPORT_SYMBOL(sync_mapping_buffers);
618
619/*
620 * Called when we've recently written block `bblock', and it is known that
621 * `bblock' was for a buffer_boundary() buffer. This means that the block at
622 * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
623 * dirty, schedule it for IO. So that indirects merge nicely with their data.
624 */
625void write_boundary_block(struct block_device *bdev,
626 sector_t bblock, unsigned blocksize)
627{
628 struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
629 if (bh) {
630 if (buffer_dirty(bh))
631 ll_rw_block(WRITE, 1, &bh);
632 put_bh(bh);
633 }
634}
635
636void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
637{
638 struct address_space *mapping = inode->i_mapping;
639 struct address_space *buffer_mapping = bh->b_page->mapping;
640
641 mark_buffer_dirty(bh);
642 if (!mapping->assoc_mapping) {
643 mapping->assoc_mapping = buffer_mapping;
644 } else {
Eric Sesterhenne827f922006-03-26 18:24:46 +0200645 BUG_ON(mapping->assoc_mapping != buffer_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646 }
Jan Kara535ee2f2008-02-08 04:21:59 -0800647 if (!bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 spin_lock(&buffer_mapping->private_lock);
649 list_move_tail(&bh->b_assoc_buffers,
650 &mapping->private_list);
Jan Kara58ff4072006-10-17 00:10:19 -0700651 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652 spin_unlock(&buffer_mapping->private_lock);
653 }
654}
655EXPORT_SYMBOL(mark_buffer_dirty_inode);
656
657/*
Nick Piggin787d2212007-07-17 04:03:34 -0700658 * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
659 * dirty.
660 *
661 * If warn is true, then emit a warning if the page is not uptodate and has
662 * not been truncated.
663 */
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700664static void __set_page_dirty(struct page *page,
Nick Piggin787d2212007-07-17 04:03:34 -0700665 struct address_space *mapping, int warn)
666{
Nick Piggin19fd6232008-07-25 19:45:32 -0700667 spin_lock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700668 if (page->mapping) { /* Race with truncate? */
669 WARN_ON_ONCE(warn && !PageUptodate(page));
Edward Shishkine3a7cca2009-03-31 15:19:39 -0700670 account_page_dirtied(page, mapping);
Nick Piggin787d2212007-07-17 04:03:34 -0700671 radix_tree_tag_set(&mapping->page_tree,
672 page_index(page), PAGECACHE_TAG_DIRTY);
673 }
Nick Piggin19fd6232008-07-25 19:45:32 -0700674 spin_unlock_irq(&mapping->tree_lock);
Nick Piggin787d2212007-07-17 04:03:34 -0700675 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
Nick Piggin787d2212007-07-17 04:03:34 -0700676}
677
678/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 * Add a page to the dirty page list.
680 *
681 * It is a sad fact of life that this function is called from several places
682 * deeply under spinlocking. It may not sleep.
683 *
684 * If the page has buffers, the uptodate buffers are set dirty, to preserve
685 * dirty-state coherency between the page and the buffers. It the page does
686 * not have buffers then when they are later attached they will all be set
687 * dirty.
688 *
689 * The buffers are dirtied before the page is dirtied. There's a small race
690 * window in which a writepage caller may see the page cleanness but not the
691 * buffer dirtiness. That's fine. If this code were to set the page dirty
692 * before the buffers, a concurrent writepage caller could clear the page dirty
693 * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
694 * page on the dirty page list.
695 *
696 * We use private_lock to lock against try_to_free_buffers while using the
697 * page's buffer list. Also use this to protect against clean buffers being
698 * added to the page after it was set dirty.
699 *
700 * FIXME: may need to call ->reservepage here as well. That's rather up to the
701 * address_space though.
702 */
703int __set_page_dirty_buffers(struct page *page)
704{
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700705 int newly_dirty;
Nick Piggin787d2212007-07-17 04:03:34 -0700706 struct address_space *mapping = page_mapping(page);
Nick Pigginebf7a222006-10-10 04:36:54 +0200707
708 if (unlikely(!mapping))
709 return !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710
711 spin_lock(&mapping->private_lock);
712 if (page_has_buffers(page)) {
713 struct buffer_head *head = page_buffers(page);
714 struct buffer_head *bh = head;
715
716 do {
717 set_buffer_dirty(bh);
718 bh = bh->b_this_page;
719 } while (bh != head);
720 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700721 newly_dirty = !TestSetPageDirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 spin_unlock(&mapping->private_lock);
723
Linus Torvaldsa8e7d492009-03-19 11:32:05 -0700724 if (newly_dirty)
725 __set_page_dirty(page, mapping, 1);
726 return newly_dirty;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727}
728EXPORT_SYMBOL(__set_page_dirty_buffers);
729
730/*
731 * Write out and wait upon a list of buffers.
732 *
733 * We have conflicting pressures: we want to make sure that all
734 * initially dirty buffers get waited on, but that any subsequently
735 * dirtied buffers don't. After all, we don't want fsync to last
736 * forever if somebody is actively writing to the file.
737 *
738 * Do this in two main stages: first we copy dirty buffers to a
739 * temporary inode list, queueing the writes as we go. Then we clean
740 * up, waiting for those writes to complete.
741 *
742 * During this second stage, any subsequent updates to the file may end
743 * up refiling the buffer on the original inode's dirty list again, so
744 * there is a chance we will end up with a buffer queued for write but
745 * not yet completed on that list. So, as a final cleanup we go through
746 * the osync code to catch these locked, dirty buffers without requeuing
747 * any newly dirty buffers for write.
748 */
749static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
750{
751 struct buffer_head *bh;
752 struct list_head tmp;
Jens Axboe9cf6b722009-04-06 14:48:03 +0200753 struct address_space *mapping, *prev_mapping = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 int err = 0, err2;
755
756 INIT_LIST_HEAD(&tmp);
757
758 spin_lock(lock);
759 while (!list_empty(list)) {
760 bh = BH_ENTRY(list->next);
Jan Kara535ee2f2008-02-08 04:21:59 -0800761 mapping = bh->b_assoc_map;
Jan Kara58ff4072006-10-17 00:10:19 -0700762 __remove_assoc_queue(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800763 /* Avoid race with mark_buffer_dirty_inode() which does
764 * a lockless check and we rely on seeing the dirty bit */
765 smp_mb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 if (buffer_dirty(bh) || buffer_locked(bh)) {
767 list_add(&bh->b_assoc_buffers, &tmp);
Jan Kara535ee2f2008-02-08 04:21:59 -0800768 bh->b_assoc_map = mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 if (buffer_dirty(bh)) {
770 get_bh(bh);
771 spin_unlock(lock);
772 /*
773 * Ensure any pending I/O completes so that
774 * ll_rw_block() actually writes the current
775 * contents - it is a noop if I/O is still in
776 * flight on potentially older contents.
777 */
Jens Axboe9cf6b722009-04-06 14:48:03 +0200778 ll_rw_block(SWRITE_SYNC_PLUG, 1, &bh);
779
780 /*
781 * Kick off IO for the previous mapping. Note
782 * that we will not run the very last mapping,
783 * wait_on_buffer() will do that for us
784 * through sync_buffer().
785 */
786 if (prev_mapping && prev_mapping != mapping)
787 blk_run_address_space(prev_mapping);
788 prev_mapping = mapping;
789
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 brelse(bh);
791 spin_lock(lock);
792 }
793 }
794 }
795
796 while (!list_empty(&tmp)) {
797 bh = BH_ENTRY(tmp.prev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 get_bh(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -0800799 mapping = bh->b_assoc_map;
800 __remove_assoc_queue(bh);
801 /* Avoid race with mark_buffer_dirty_inode() which does
802 * a lockless check and we rely on seeing the dirty bit */
803 smp_mb();
804 if (buffer_dirty(bh)) {
805 list_add(&bh->b_assoc_buffers,
Jan Karae3892292008-03-04 14:28:33 -0800806 &mapping->private_list);
Jan Kara535ee2f2008-02-08 04:21:59 -0800807 bh->b_assoc_map = mapping;
808 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 spin_unlock(lock);
810 wait_on_buffer(bh);
811 if (!buffer_uptodate(bh))
812 err = -EIO;
813 brelse(bh);
814 spin_lock(lock);
815 }
816
817 spin_unlock(lock);
818 err2 = osync_buffers_list(lock, list);
819 if (err)
820 return err;
821 else
822 return err2;
823}
824
825/*
826 * Invalidate any and all dirty buffers on a given inode. We are
827 * probably unmounting the fs, but that doesn't mean we have already
828 * done a sync(). Just drop the buffers from the inode list.
829 *
830 * NOTE: we take the inode's blockdev's mapping's private_lock. Which
831 * assumes that all the buffers are against the blockdev. Not true
832 * for reiserfs.
833 */
834void invalidate_inode_buffers(struct inode *inode)
835{
836 if (inode_has_buffers(inode)) {
837 struct address_space *mapping = &inode->i_data;
838 struct list_head *list = &mapping->private_list;
839 struct address_space *buffer_mapping = mapping->assoc_mapping;
840
841 spin_lock(&buffer_mapping->private_lock);
842 while (!list_empty(list))
843 __remove_assoc_queue(BH_ENTRY(list->next));
844 spin_unlock(&buffer_mapping->private_lock);
845 }
846}
Jan Kara52b19ac2008-09-23 18:24:08 +0200847EXPORT_SYMBOL(invalidate_inode_buffers);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848
849/*
850 * Remove any clean buffers from the inode's buffer list. This is called
851 * when we're trying to free the inode itself. Those buffers can pin it.
852 *
853 * Returns true if all buffers were removed.
854 */
855int remove_inode_buffers(struct inode *inode)
856{
857 int ret = 1;
858
859 if (inode_has_buffers(inode)) {
860 struct address_space *mapping = &inode->i_data;
861 struct list_head *list = &mapping->private_list;
862 struct address_space *buffer_mapping = mapping->assoc_mapping;
863
864 spin_lock(&buffer_mapping->private_lock);
865 while (!list_empty(list)) {
866 struct buffer_head *bh = BH_ENTRY(list->next);
867 if (buffer_dirty(bh)) {
868 ret = 0;
869 break;
870 }
871 __remove_assoc_queue(bh);
872 }
873 spin_unlock(&buffer_mapping->private_lock);
874 }
875 return ret;
876}
877
878/*
879 * Create the appropriate buffers when given a page for data area and
880 * the size of each buffer.. Use the bh->b_this_page linked list to
881 * follow the buffers created. Return NULL if unable to create more
882 * buffers.
883 *
884 * The retry flag is used to differentiate async IO (paging, swapping)
885 * which may not fail from ordinary buffer allocations.
886 */
887struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
888 int retry)
889{
890 struct buffer_head *bh, *head;
891 long offset;
892
893try_again:
894 head = NULL;
895 offset = PAGE_SIZE;
896 while ((offset -= size) >= 0) {
897 bh = alloc_buffer_head(GFP_NOFS);
898 if (!bh)
899 goto no_grow;
900
901 bh->b_bdev = NULL;
902 bh->b_this_page = head;
903 bh->b_blocknr = -1;
904 head = bh;
905
906 bh->b_state = 0;
907 atomic_set(&bh->b_count, 0);
Chris Masonfc5cd582006-02-01 03:06:48 -0800908 bh->b_private = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700909 bh->b_size = size;
910
911 /* Link the buffer to its page */
912 set_bh_page(bh, page, offset);
913
Nathan Scott01ffe332006-01-17 09:02:07 +1100914 init_buffer(bh, NULL, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 }
916 return head;
917/*
918 * In case anything failed, we just free everything we got.
919 */
920no_grow:
921 if (head) {
922 do {
923 bh = head;
924 head = head->b_this_page;
925 free_buffer_head(bh);
926 } while (head);
927 }
928
929 /*
930 * Return failure for non-async IO requests. Async IO requests
931 * are not allowed to fail, so we have to wait until buffer heads
932 * become available. But we don't want tasks sleeping with
933 * partially complete buffers, so all were released above.
934 */
935 if (!retry)
936 return NULL;
937
938 /* We're _really_ low on memory. Now we just
939 * wait for old buffer heads to become free due to
940 * finishing IO. Since this is an async request and
941 * the reserve list is empty, we're sure there are
942 * async buffer heads in use.
943 */
944 free_more_memory();
945 goto try_again;
946}
947EXPORT_SYMBOL_GPL(alloc_page_buffers);
948
949static inline void
950link_dev_buffers(struct page *page, struct buffer_head *head)
951{
952 struct buffer_head *bh, *tail;
953
954 bh = head;
955 do {
956 tail = bh;
957 bh = bh->b_this_page;
958 } while (bh);
959 tail->b_this_page = head;
960 attach_page_buffers(page, head);
961}
962
963/*
964 * Initialise the state of a blockdev page's buffers.
965 */
966static void
967init_page_buffers(struct page *page, struct block_device *bdev,
968 sector_t block, int size)
969{
970 struct buffer_head *head = page_buffers(page);
971 struct buffer_head *bh = head;
972 int uptodate = PageUptodate(page);
973
974 do {
975 if (!buffer_mapped(bh)) {
976 init_buffer(bh, NULL, NULL);
977 bh->b_bdev = bdev;
978 bh->b_blocknr = block;
979 if (uptodate)
980 set_buffer_uptodate(bh);
981 set_buffer_mapped(bh);
982 }
983 block++;
984 bh = bh->b_this_page;
985 } while (bh != head);
986}
987
988/*
989 * Create the page-cache page that contains the requested block.
990 *
991 * This is user purely for blockdev mappings.
992 */
993static struct page *
994grow_dev_page(struct block_device *bdev, sector_t block,
995 pgoff_t index, int size)
996{
997 struct inode *inode = bdev->bd_inode;
998 struct page *page;
999 struct buffer_head *bh;
1000
Christoph Lameterea125892007-05-16 22:11:21 -07001001 page = find_or_create_page(inode->i_mapping, index,
Mel Gorman769848c2007-07-17 04:03:05 -07001002 (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 if (!page)
1004 return NULL;
1005
Eric Sesterhenne827f922006-03-26 18:24:46 +02001006 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001007
1008 if (page_has_buffers(page)) {
1009 bh = page_buffers(page);
1010 if (bh->b_size == size) {
1011 init_page_buffers(page, bdev, block, size);
1012 return page;
1013 }
1014 if (!try_to_free_buffers(page))
1015 goto failed;
1016 }
1017
1018 /*
1019 * Allocate some buffers for this page
1020 */
1021 bh = alloc_page_buffers(page, size, 0);
1022 if (!bh)
1023 goto failed;
1024
1025 /*
1026 * Link the page to the buffers and initialise them. Take the
1027 * lock to be atomic wrt __find_get_block(), which does not
1028 * run under the page lock.
1029 */
1030 spin_lock(&inode->i_mapping->private_lock);
1031 link_dev_buffers(page, bh);
1032 init_page_buffers(page, bdev, block, size);
1033 spin_unlock(&inode->i_mapping->private_lock);
1034 return page;
1035
1036failed:
1037 BUG();
1038 unlock_page(page);
1039 page_cache_release(page);
1040 return NULL;
1041}
1042
1043/*
1044 * Create buffers for the specified block device block's page. If
1045 * that page was dirty, the buffers are set dirty also.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001047static int
Linus Torvalds1da177e2005-04-16 15:20:36 -07001048grow_buffers(struct block_device *bdev, sector_t block, int size)
1049{
1050 struct page *page;
1051 pgoff_t index;
1052 int sizebits;
1053
1054 sizebits = -1;
1055 do {
1056 sizebits++;
1057 } while ((size << sizebits) < PAGE_SIZE);
1058
1059 index = block >> sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060
Andrew Mortone5657932006-10-11 01:21:46 -07001061 /*
1062 * Check for a block which wants to lie outside our maximum possible
1063 * pagecache index. (this comparison is done using sector_t types).
1064 */
1065 if (unlikely(index != block >> sizebits)) {
1066 char b[BDEVNAME_SIZE];
1067
1068 printk(KERN_ERR "%s: requested out-of-range block %llu for "
1069 "device %s\n",
Harvey Harrison8e24eea2008-04-30 00:55:09 -07001070 __func__, (unsigned long long)block,
Andrew Mortone5657932006-10-11 01:21:46 -07001071 bdevname(bdev, b));
1072 return -EIO;
1073 }
1074 block = index << sizebits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 /* Create a page with the proper size buffers.. */
1076 page = grow_dev_page(bdev, block, index, size);
1077 if (!page)
1078 return 0;
1079 unlock_page(page);
1080 page_cache_release(page);
1081 return 1;
1082}
1083
Adrian Bunk75c96f82005-05-05 16:16:09 -07001084static struct buffer_head *
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085__getblk_slow(struct block_device *bdev, sector_t block, int size)
1086{
1087 /* Size must be multiple of hard sectorsize */
Martin K. Petersene1defc42009-05-22 17:17:49 -04001088 if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 (size < 512 || size > PAGE_SIZE))) {
1090 printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1091 size);
Martin K. Petersene1defc42009-05-22 17:17:49 -04001092 printk(KERN_ERR "logical block size: %d\n",
1093 bdev_logical_block_size(bdev));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094
1095 dump_stack();
1096 return NULL;
1097 }
1098
1099 for (;;) {
1100 struct buffer_head * bh;
Andrew Mortone5657932006-10-11 01:21:46 -07001101 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102
1103 bh = __find_get_block(bdev, block, size);
1104 if (bh)
1105 return bh;
1106
Andrew Mortone5657932006-10-11 01:21:46 -07001107 ret = grow_buffers(bdev, block, size);
1108 if (ret < 0)
1109 return NULL;
1110 if (ret == 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001111 free_more_memory();
1112 }
1113}
1114
1115/*
1116 * The relationship between dirty buffers and dirty pages:
1117 *
1118 * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1119 * the page is tagged dirty in its radix tree.
1120 *
1121 * At all times, the dirtiness of the buffers represents the dirtiness of
1122 * subsections of the page. If the page has buffers, the page dirty bit is
1123 * merely a hint about the true dirty state.
1124 *
1125 * When a page is set dirty in its entirety, all its buffers are marked dirty
1126 * (if the page has buffers).
1127 *
1128 * When a buffer is marked dirty, its page is dirtied, but the page's other
1129 * buffers are not.
1130 *
1131 * Also. When blockdev buffers are explicitly read with bread(), they
1132 * individually become uptodate. But their backing page remains not
1133 * uptodate - even if all of its buffers are uptodate. A subsequent
1134 * block_read_full_page() against that page will discover all the uptodate
1135 * buffers, will set the page uptodate and will perform no I/O.
1136 */
1137
1138/**
1139 * mark_buffer_dirty - mark a buffer_head as needing writeout
Martin Waitz67be2dd2005-05-01 08:59:26 -07001140 * @bh: the buffer_head to mark dirty
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 *
1142 * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1143 * backing page dirty, then tag the page as dirty in its address_space's radix
1144 * tree and then attach the address_space's inode to its superblock's dirty
1145 * inode list.
1146 *
1147 * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1148 * mapping->tree_lock and the global inode_lock.
1149 */
Harvey Harrisonfc9b52c2008-02-08 04:19:52 -08001150void mark_buffer_dirty(struct buffer_head *bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151{
Nick Piggin787d2212007-07-17 04:03:34 -07001152 WARN_ON_ONCE(!buffer_uptodate(bh));
Linus Torvalds1be62dc2008-04-04 14:38:17 -07001153
1154 /*
1155 * Very *carefully* optimize the it-is-already-dirty case.
1156 *
1157 * Don't let the final "is it dirty" escape to before we
1158 * perhaps modified the buffer.
1159 */
1160 if (buffer_dirty(bh)) {
1161 smp_mb();
1162 if (buffer_dirty(bh))
1163 return;
1164 }
1165
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001166 if (!test_set_buffer_dirty(bh)) {
1167 struct page *page = bh->b_page;
Linus Torvalds8e9d78e2009-08-21 17:40:08 -07001168 if (!TestSetPageDirty(page)) {
1169 struct address_space *mapping = page_mapping(page);
1170 if (mapping)
1171 __set_page_dirty(page, mapping, 0);
1172 }
Linus Torvaldsa8e7d492009-03-19 11:32:05 -07001173 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174}
1175
1176/*
1177 * Decrement a buffer_head's reference count. If all buffers against a page
1178 * have zero reference count, are clean and unlocked, and if the page is clean
1179 * and unlocked then try_to_free_buffers() may strip the buffers from the page
1180 * in preparation for freeing it (sometimes, rarely, buffers are removed from
1181 * a page but it ends up not being freed, and buffers may later be reattached).
1182 */
1183void __brelse(struct buffer_head * buf)
1184{
1185 if (atomic_read(&buf->b_count)) {
1186 put_bh(buf);
1187 return;
1188 }
Arjan van de Ven5c752ad2008-07-25 19:45:40 -07001189 WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190}
1191
1192/*
1193 * bforget() is like brelse(), except it discards any
1194 * potentially dirty data.
1195 */
1196void __bforget(struct buffer_head *bh)
1197{
1198 clear_buffer_dirty(bh);
Jan Kara535ee2f2008-02-08 04:21:59 -08001199 if (bh->b_assoc_map) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200 struct address_space *buffer_mapping = bh->b_page->mapping;
1201
1202 spin_lock(&buffer_mapping->private_lock);
1203 list_del_init(&bh->b_assoc_buffers);
Jan Kara58ff4072006-10-17 00:10:19 -07001204 bh->b_assoc_map = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 spin_unlock(&buffer_mapping->private_lock);
1206 }
1207 __brelse(bh);
1208}
1209
1210static struct buffer_head *__bread_slow(struct buffer_head *bh)
1211{
1212 lock_buffer(bh);
1213 if (buffer_uptodate(bh)) {
1214 unlock_buffer(bh);
1215 return bh;
1216 } else {
1217 get_bh(bh);
1218 bh->b_end_io = end_buffer_read_sync;
1219 submit_bh(READ, bh);
1220 wait_on_buffer(bh);
1221 if (buffer_uptodate(bh))
1222 return bh;
1223 }
1224 brelse(bh);
1225 return NULL;
1226}
1227
1228/*
1229 * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1230 * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1231 * refcount elevated by one when they're in an LRU. A buffer can only appear
1232 * once in a particular CPU's LRU. A single buffer can be present in multiple
1233 * CPU's LRUs at the same time.
1234 *
1235 * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1236 * sb_find_get_block().
1237 *
1238 * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1239 * a local interrupt disable for that.
1240 */
1241
1242#define BH_LRU_SIZE 8
1243
1244struct bh_lru {
1245 struct buffer_head *bhs[BH_LRU_SIZE];
1246};
1247
1248static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1249
1250#ifdef CONFIG_SMP
1251#define bh_lru_lock() local_irq_disable()
1252#define bh_lru_unlock() local_irq_enable()
1253#else
1254#define bh_lru_lock() preempt_disable()
1255#define bh_lru_unlock() preempt_enable()
1256#endif
1257
1258static inline void check_irqs_on(void)
1259{
1260#ifdef irqs_disabled
1261 BUG_ON(irqs_disabled());
1262#endif
1263}
1264
1265/*
1266 * The LRU management algorithm is dopey-but-simple. Sorry.
1267 */
1268static void bh_lru_install(struct buffer_head *bh)
1269{
1270 struct buffer_head *evictee = NULL;
1271 struct bh_lru *lru;
1272
1273 check_irqs_on();
1274 bh_lru_lock();
1275 lru = &__get_cpu_var(bh_lrus);
1276 if (lru->bhs[0] != bh) {
1277 struct buffer_head *bhs[BH_LRU_SIZE];
1278 int in;
1279 int out = 0;
1280
1281 get_bh(bh);
1282 bhs[out++] = bh;
1283 for (in = 0; in < BH_LRU_SIZE; in++) {
1284 struct buffer_head *bh2 = lru->bhs[in];
1285
1286 if (bh2 == bh) {
1287 __brelse(bh2);
1288 } else {
1289 if (out >= BH_LRU_SIZE) {
1290 BUG_ON(evictee != NULL);
1291 evictee = bh2;
1292 } else {
1293 bhs[out++] = bh2;
1294 }
1295 }
1296 }
1297 while (out < BH_LRU_SIZE)
1298 bhs[out++] = NULL;
1299 memcpy(lru->bhs, bhs, sizeof(bhs));
1300 }
1301 bh_lru_unlock();
1302
1303 if (evictee)
1304 __brelse(evictee);
1305}
1306
1307/*
1308 * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1309 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001310static struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001311lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312{
1313 struct buffer_head *ret = NULL;
1314 struct bh_lru *lru;
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001315 unsigned int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316
1317 check_irqs_on();
1318 bh_lru_lock();
1319 lru = &__get_cpu_var(bh_lrus);
1320 for (i = 0; i < BH_LRU_SIZE; i++) {
1321 struct buffer_head *bh = lru->bhs[i];
1322
1323 if (bh && bh->b_bdev == bdev &&
1324 bh->b_blocknr == block && bh->b_size == size) {
1325 if (i) {
1326 while (i) {
1327 lru->bhs[i] = lru->bhs[i - 1];
1328 i--;
1329 }
1330 lru->bhs[0] = bh;
1331 }
1332 get_bh(bh);
1333 ret = bh;
1334 break;
1335 }
1336 }
1337 bh_lru_unlock();
1338 return ret;
1339}
1340
1341/*
1342 * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1343 * it in the LRU and mark it as accessed. If it is not present then return
1344 * NULL
1345 */
1346struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001347__find_get_block(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348{
1349 struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1350
1351 if (bh == NULL) {
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001352 bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 if (bh)
1354 bh_lru_install(bh);
1355 }
1356 if (bh)
1357 touch_buffer(bh);
1358 return bh;
1359}
1360EXPORT_SYMBOL(__find_get_block);
1361
1362/*
1363 * __getblk will locate (and, if necessary, create) the buffer_head
1364 * which corresponds to the passed block_device, block and size. The
1365 * returned buffer has its reference count incremented.
1366 *
1367 * __getblk() cannot fail - it just keeps trying. If you pass it an
1368 * illegal block number, __getblk() will happily return a buffer_head
1369 * which represents the non-existent block. Very weird.
1370 *
1371 * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1372 * attempt is failing. FIXME, perhaps?
1373 */
1374struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001375__getblk(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376{
1377 struct buffer_head *bh = __find_get_block(bdev, block, size);
1378
1379 might_sleep();
1380 if (bh == NULL)
1381 bh = __getblk_slow(bdev, block, size);
1382 return bh;
1383}
1384EXPORT_SYMBOL(__getblk);
1385
1386/*
1387 * Do async read-ahead on a buffer..
1388 */
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001389void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001390{
1391 struct buffer_head *bh = __getblk(bdev, block, size);
Andrew Mortona3e713b2005-10-30 15:03:15 -08001392 if (likely(bh)) {
1393 ll_rw_block(READA, 1, &bh);
1394 brelse(bh);
1395 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396}
1397EXPORT_SYMBOL(__breadahead);
1398
1399/**
1400 * __bread() - reads a specified block and returns the bh
Martin Waitz67be2dd2005-05-01 08:59:26 -07001401 * @bdev: the block_device to read from
Linus Torvalds1da177e2005-04-16 15:20:36 -07001402 * @block: number of block
1403 * @size: size (in bytes) to read
1404 *
1405 * Reads a specified block, and returns buffer head that contains it.
1406 * It returns NULL if the block was unreadable.
1407 */
1408struct buffer_head *
Tomasz Kvarsin3991d3b2007-02-12 00:52:14 -08001409__bread(struct block_device *bdev, sector_t block, unsigned size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410{
1411 struct buffer_head *bh = __getblk(bdev, block, size);
1412
Andrew Mortona3e713b2005-10-30 15:03:15 -08001413 if (likely(bh) && !buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 bh = __bread_slow(bh);
1415 return bh;
1416}
1417EXPORT_SYMBOL(__bread);
1418
1419/*
1420 * invalidate_bh_lrus() is called rarely - but not only at unmount.
1421 * This doesn't race because it runs in each cpu either in irq
1422 * or with preempt disabled.
1423 */
1424static void invalidate_bh_lru(void *arg)
1425{
1426 struct bh_lru *b = &get_cpu_var(bh_lrus);
1427 int i;
1428
1429 for (i = 0; i < BH_LRU_SIZE; i++) {
1430 brelse(b->bhs[i]);
1431 b->bhs[i] = NULL;
1432 }
1433 put_cpu_var(bh_lrus);
1434}
1435
Peter Zijlstraf9a14392007-05-06 14:49:55 -07001436void invalidate_bh_lrus(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437{
Jens Axboe15c8b6c2008-05-09 09:39:44 +02001438 on_each_cpu(invalidate_bh_lru, NULL, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001439}
Nick Piggin9db55792008-02-08 04:19:49 -08001440EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001441
1442void set_bh_page(struct buffer_head *bh,
1443 struct page *page, unsigned long offset)
1444{
1445 bh->b_page = page;
Eric Sesterhenne827f922006-03-26 18:24:46 +02001446 BUG_ON(offset >= PAGE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 if (PageHighMem(page))
1448 /*
1449 * This catches illegal uses and preserves the offset:
1450 */
1451 bh->b_data = (char *)(0 + offset);
1452 else
1453 bh->b_data = page_address(page) + offset;
1454}
1455EXPORT_SYMBOL(set_bh_page);
1456
1457/*
1458 * Called when truncating a buffer on a page completely.
1459 */
Arjan van de Ven858119e2006-01-14 13:20:43 -08001460static void discard_buffer(struct buffer_head * bh)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461{
1462 lock_buffer(bh);
1463 clear_buffer_dirty(bh);
1464 bh->b_bdev = NULL;
1465 clear_buffer_mapped(bh);
1466 clear_buffer_req(bh);
1467 clear_buffer_new(bh);
1468 clear_buffer_delay(bh);
David Chinner33a266d2007-02-12 00:51:41 -08001469 clear_buffer_unwritten(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 unlock_buffer(bh);
1471}
1472
1473/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001474 * block_invalidatepage - invalidate part of all of a buffer-backed page
1475 *
1476 * @page: the page which is affected
1477 * @offset: the index of the truncation point
1478 *
1479 * block_invalidatepage() is called when all or part of the page has become
1480 * invalidatedby a truncate operation.
1481 *
1482 * block_invalidatepage() does not have to release all buffers, but it must
1483 * ensure that no dirty buffer is left outside @offset and that no I/O
1484 * is underway against any of the blocks which are outside the truncation
1485 * point. Because the caller is about to free (and possibly reuse) those
1486 * blocks on-disk.
1487 */
NeilBrown2ff28e22006-03-26 01:37:18 -08001488void block_invalidatepage(struct page *page, unsigned long offset)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001489{
1490 struct buffer_head *head, *bh, *next;
1491 unsigned int curr_off = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492
1493 BUG_ON(!PageLocked(page));
1494 if (!page_has_buffers(page))
1495 goto out;
1496
1497 head = page_buffers(page);
1498 bh = head;
1499 do {
1500 unsigned int next_off = curr_off + bh->b_size;
1501 next = bh->b_this_page;
1502
1503 /*
1504 * is this block fully invalidated?
1505 */
1506 if (offset <= curr_off)
1507 discard_buffer(bh);
1508 curr_off = next_off;
1509 bh = next;
1510 } while (bh != head);
1511
1512 /*
1513 * We release buffers only if the entire page is being invalidated.
1514 * The get_block cached value has been unconditionally invalidated,
1515 * so real IO is not possible anymore.
1516 */
1517 if (offset == 0)
NeilBrown2ff28e22006-03-26 01:37:18 -08001518 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519out:
NeilBrown2ff28e22006-03-26 01:37:18 -08001520 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521}
1522EXPORT_SYMBOL(block_invalidatepage);
1523
1524/*
1525 * We attach and possibly dirty the buffers atomically wrt
1526 * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1527 * is already excluded via the page lock.
1528 */
1529void create_empty_buffers(struct page *page,
1530 unsigned long blocksize, unsigned long b_state)
1531{
1532 struct buffer_head *bh, *head, *tail;
1533
1534 head = alloc_page_buffers(page, blocksize, 1);
1535 bh = head;
1536 do {
1537 bh->b_state |= b_state;
1538 tail = bh;
1539 bh = bh->b_this_page;
1540 } while (bh);
1541 tail->b_this_page = head;
1542
1543 spin_lock(&page->mapping->private_lock);
1544 if (PageUptodate(page) || PageDirty(page)) {
1545 bh = head;
1546 do {
1547 if (PageDirty(page))
1548 set_buffer_dirty(bh);
1549 if (PageUptodate(page))
1550 set_buffer_uptodate(bh);
1551 bh = bh->b_this_page;
1552 } while (bh != head);
1553 }
1554 attach_page_buffers(page, head);
1555 spin_unlock(&page->mapping->private_lock);
1556}
1557EXPORT_SYMBOL(create_empty_buffers);
1558
1559/*
1560 * We are taking a block for data and we don't want any output from any
1561 * buffer-cache aliases starting from return from that function and
1562 * until the moment when something will explicitly mark the buffer
1563 * dirty (hopefully that will not happen until we will free that block ;-)
1564 * We don't even need to mark it not-uptodate - nobody can expect
1565 * anything from a newly allocated buffer anyway. We used to used
1566 * unmap_buffer() for such invalidation, but that was wrong. We definitely
1567 * don't want to mark the alias unmapped, for example - it would confuse
1568 * anyone who might pick it with bread() afterwards...
1569 *
1570 * Also.. Note that bforget() doesn't lock the buffer. So there can
1571 * be writeout I/O going on against recently-freed buffers. We don't
1572 * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1573 * only if we really need to. That happens here.
1574 */
1575void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1576{
1577 struct buffer_head *old_bh;
1578
1579 might_sleep();
1580
Coywolf Qi Hunt385fd4c2005-11-07 00:59:39 -08001581 old_bh = __find_get_block_slow(bdev, block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582 if (old_bh) {
1583 clear_buffer_dirty(old_bh);
1584 wait_on_buffer(old_bh);
1585 clear_buffer_req(old_bh);
1586 __brelse(old_bh);
1587 }
1588}
1589EXPORT_SYMBOL(unmap_underlying_metadata);
1590
1591/*
1592 * NOTE! All mapped/uptodate combinations are valid:
1593 *
1594 * Mapped Uptodate Meaning
1595 *
1596 * No No "unknown" - must do get_block()
1597 * No Yes "hole" - zero-filled
1598 * Yes No "allocated" - allocated on disk, not read in
1599 * Yes Yes "valid" - allocated and up-to-date in memory.
1600 *
1601 * "Dirty" is valid only with the last case (mapped+uptodate).
1602 */
1603
1604/*
1605 * While block_write_full_page is writing back the dirty buffers under
1606 * the page lock, whoever dirtied the buffers may decide to clean them
1607 * again at any time. We handle that by only looking at the buffer
1608 * state inside lock_buffer().
1609 *
1610 * If block_write_full_page() is called for regular writeback
1611 * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1612 * locked buffer. This only can happen if someone has written the buffer
1613 * directly, with submit_bh(). At the address_space level PageWriteback
1614 * prevents this contention from occurring.
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001615 *
1616 * If block_write_full_page() is called with wbc->sync_mode ==
1617 * WB_SYNC_ALL, the writes are posted using WRITE_SYNC_PLUG; this
1618 * causes the writes to be flagged as synchronous writes, but the
1619 * block device queue will NOT be unplugged, since usually many pages
1620 * will be pushed to the out before the higher-level caller actually
1621 * waits for the writes to be completed. The various wait functions,
1622 * such as wait_on_writeback_range() will ultimately call sync_page()
1623 * which will ultimately call blk_run_backing_dev(), which will end up
1624 * unplugging the device queue.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625 */
1626static int __block_write_full_page(struct inode *inode, struct page *page,
Chris Mason35c80d52009-04-15 13:22:38 -04001627 get_block_t *get_block, struct writeback_control *wbc,
1628 bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629{
1630 int err;
1631 sector_t block;
1632 sector_t last_block;
Andrew Mortonf0fbd5f2005-05-05 16:15:48 -07001633 struct buffer_head *bh, *head;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001634 const unsigned blocksize = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 int nr_underway = 0;
Theodore Ts'o6e34eed2009-04-07 18:12:43 -04001636 int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
1637 WRITE_SYNC_PLUG : WRITE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638
1639 BUG_ON(!PageLocked(page));
1640
1641 last_block = (i_size_read(inode) - 1) >> inode->i_blkbits;
1642
1643 if (!page_has_buffers(page)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001644 create_empty_buffers(page, blocksize,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 (1 << BH_Dirty)|(1 << BH_Uptodate));
1646 }
1647
1648 /*
1649 * Be very careful. We have no exclusion from __set_page_dirty_buffers
1650 * here, and the (potentially unmapped) buffers may become dirty at
1651 * any time. If a buffer becomes dirty here after we've inspected it
1652 * then we just miss that fact, and the page stays dirty.
1653 *
1654 * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1655 * handle that here by just cleaning them.
1656 */
1657
Andrew Morton54b21a72006-01-08 01:03:05 -08001658 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 head = page_buffers(page);
1660 bh = head;
1661
1662 /*
1663 * Get all the dirty buffers mapped to disk addresses and
1664 * handle any aliases from the underlying blockdev's mapping.
1665 */
1666 do {
1667 if (block > last_block) {
1668 /*
1669 * mapped buffers outside i_size will occur, because
1670 * this page can be outside i_size when there is a
1671 * truncate in progress.
1672 */
1673 /*
1674 * The buffer was zeroed by block_write_full_page()
1675 */
1676 clear_buffer_dirty(bh);
1677 set_buffer_uptodate(bh);
Alex Tomas29a814d2008-07-11 19:27:31 -04001678 } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
1679 buffer_dirty(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001680 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 err = get_block(inode, block, bh, 1);
1682 if (err)
1683 goto recover;
Alex Tomas29a814d2008-07-11 19:27:31 -04001684 clear_buffer_delay(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685 if (buffer_new(bh)) {
1686 /* blockdev mappings never come here */
1687 clear_buffer_new(bh);
1688 unmap_underlying_metadata(bh->b_bdev,
1689 bh->b_blocknr);
1690 }
1691 }
1692 bh = bh->b_this_page;
1693 block++;
1694 } while (bh != head);
1695
1696 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 if (!buffer_mapped(bh))
1698 continue;
1699 /*
1700 * If it's a fully non-blocking write attempt and we cannot
1701 * lock the buffer then redirty the page. Note that this can
1702 * potentially cause a busy-wait loop from pdflush and kswapd
1703 * activity, but those code paths have their own higher-level
1704 * throttling.
1705 */
1706 if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) {
1707 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02001708 } else if (!trylock_buffer(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709 redirty_page_for_writepage(wbc, page);
1710 continue;
1711 }
1712 if (test_clear_buffer_dirty(bh)) {
Chris Mason35c80d52009-04-15 13:22:38 -04001713 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001714 } else {
1715 unlock_buffer(bh);
1716 }
1717 } while ((bh = bh->b_this_page) != head);
1718
1719 /*
1720 * The page and its buffers are protected by PageWriteback(), so we can
1721 * drop the bh refcounts early.
1722 */
1723 BUG_ON(PageWriteback(page));
1724 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725
1726 do {
1727 struct buffer_head *next = bh->b_this_page;
1728 if (buffer_async_write(bh)) {
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001729 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 nr_underway++;
1731 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001732 bh = next;
1733 } while (bh != head);
Andrew Morton05937ba2005-05-05 16:15:47 -07001734 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001735
1736 err = 0;
1737done:
1738 if (nr_underway == 0) {
1739 /*
1740 * The page was marked dirty, but the buffers were
1741 * clean. Someone wrote them back by hand with
1742 * ll_rw_block/submit_bh. A rare case.
1743 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001744 end_page_writeback(page);
Nick Piggin3d67f2d2007-05-06 14:49:05 -07001745
Linus Torvalds1da177e2005-04-16 15:20:36 -07001746 /*
1747 * The page and buffer_heads can be released at any time from
1748 * here on.
1749 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 }
1751 return err;
1752
1753recover:
1754 /*
1755 * ENOSPC, or some other error. We may already have added some
1756 * blocks to the file, so we need to write these out to avoid
1757 * exposing stale data.
1758 * The page is currently locked and not marked for writeback
1759 */
1760 bh = head;
1761 /* Recovery: lock and submit the mapped buffers */
1762 do {
Alex Tomas29a814d2008-07-11 19:27:31 -04001763 if (buffer_mapped(bh) && buffer_dirty(bh) &&
1764 !buffer_delay(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 lock_buffer(bh);
Chris Mason35c80d52009-04-15 13:22:38 -04001766 mark_buffer_async_write_endio(bh, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001767 } else {
1768 /*
1769 * The buffer may have been set dirty during
1770 * attachment to a dirty page.
1771 */
1772 clear_buffer_dirty(bh);
1773 }
1774 } while ((bh = bh->b_this_page) != head);
1775 SetPageError(page);
1776 BUG_ON(PageWriteback(page));
Andrew Morton7e4c3692007-05-08 00:23:27 -07001777 mapping_set_error(page->mapping, err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778 set_page_writeback(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001779 do {
1780 struct buffer_head *next = bh->b_this_page;
1781 if (buffer_async_write(bh)) {
1782 clear_buffer_dirty(bh);
Theodore Ts'oa64c8612009-03-27 22:14:10 -04001783 submit_bh(write_op, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 nr_underway++;
1785 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001786 bh = next;
1787 } while (bh != head);
Nick Pigginffda9d32007-02-20 13:57:54 -08001788 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789 goto done;
1790}
1791
Nick Pigginafddba42007-10-16 01:25:01 -07001792/*
1793 * If a page has any new buffers, zero them out here, and mark them uptodate
1794 * and dirty so they'll be written out (in order to prevent uninitialised
1795 * block data from leaking). And clear the new bit.
1796 */
1797void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1798{
1799 unsigned int block_start, block_end;
1800 struct buffer_head *head, *bh;
1801
1802 BUG_ON(!PageLocked(page));
1803 if (!page_has_buffers(page))
1804 return;
1805
1806 bh = head = page_buffers(page);
1807 block_start = 0;
1808 do {
1809 block_end = block_start + bh->b_size;
1810
1811 if (buffer_new(bh)) {
1812 if (block_end > from && block_start < to) {
1813 if (!PageUptodate(page)) {
1814 unsigned start, size;
1815
1816 start = max(from, block_start);
1817 size = min(to, block_end) - start;
1818
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001819 zero_user(page, start, size);
Nick Pigginafddba42007-10-16 01:25:01 -07001820 set_buffer_uptodate(bh);
1821 }
1822
1823 clear_buffer_new(bh);
1824 mark_buffer_dirty(bh);
1825 }
1826 }
1827
1828 block_start = block_end;
1829 bh = bh->b_this_page;
1830 } while (bh != head);
1831}
1832EXPORT_SYMBOL(page_zero_new_buffers);
1833
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834static int __block_prepare_write(struct inode *inode, struct page *page,
1835 unsigned from, unsigned to, get_block_t *get_block)
1836{
1837 unsigned block_start, block_end;
1838 sector_t block;
1839 int err = 0;
1840 unsigned blocksize, bbits;
1841 struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1842
1843 BUG_ON(!PageLocked(page));
1844 BUG_ON(from > PAGE_CACHE_SIZE);
1845 BUG_ON(to > PAGE_CACHE_SIZE);
1846 BUG_ON(from > to);
1847
1848 blocksize = 1 << inode->i_blkbits;
1849 if (!page_has_buffers(page))
1850 create_empty_buffers(page, blocksize, 0);
1851 head = page_buffers(page);
1852
1853 bbits = inode->i_blkbits;
1854 block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1855
1856 for(bh = head, block_start = 0; bh != head || !block_start;
1857 block++, block_start=block_end, bh = bh->b_this_page) {
1858 block_end = block_start + blocksize;
1859 if (block_end <= from || block_start >= to) {
1860 if (PageUptodate(page)) {
1861 if (!buffer_uptodate(bh))
1862 set_buffer_uptodate(bh);
1863 }
1864 continue;
1865 }
1866 if (buffer_new(bh))
1867 clear_buffer_new(bh);
1868 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08001869 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870 err = get_block(inode, block, bh, 1);
1871 if (err)
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001872 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873 if (buffer_new(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001874 unmap_underlying_metadata(bh->b_bdev,
1875 bh->b_blocknr);
1876 if (PageUptodate(page)) {
Nick Piggin637aff42007-10-16 01:25:00 -07001877 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 set_buffer_uptodate(bh);
Nick Piggin637aff42007-10-16 01:25:00 -07001879 mark_buffer_dirty(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 continue;
1881 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08001882 if (block_end > to || block_start < from)
1883 zero_user_segments(page,
1884 to, block_end,
1885 block_start, from);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 continue;
1887 }
1888 }
1889 if (PageUptodate(page)) {
1890 if (!buffer_uptodate(bh))
1891 set_buffer_uptodate(bh);
1892 continue;
1893 }
1894 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
David Chinner33a266d2007-02-12 00:51:41 -08001895 !buffer_unwritten(bh) &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001896 (block_start < from || block_end > to)) {
1897 ll_rw_block(READ, 1, &bh);
1898 *wait_bh++=bh;
1899 }
1900 }
1901 /*
1902 * If we issued read requests - let them complete.
1903 */
1904 while(wait_bh > wait) {
1905 wait_on_buffer(*--wait_bh);
1906 if (!buffer_uptodate(*wait_bh))
Nick Pigginf3ddbdc2005-05-05 16:15:45 -07001907 err = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001908 }
Nick Pigginafddba42007-10-16 01:25:01 -07001909 if (unlikely(err))
1910 page_zero_new_buffers(page, from, to);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911 return err;
1912}
1913
1914static int __block_commit_write(struct inode *inode, struct page *page,
1915 unsigned from, unsigned to)
1916{
1917 unsigned block_start, block_end;
1918 int partial = 0;
1919 unsigned blocksize;
1920 struct buffer_head *bh, *head;
1921
1922 blocksize = 1 << inode->i_blkbits;
1923
1924 for(bh = head = page_buffers(page), block_start = 0;
1925 bh != head || !block_start;
1926 block_start=block_end, bh = bh->b_this_page) {
1927 block_end = block_start + blocksize;
1928 if (block_end <= from || block_start >= to) {
1929 if (!buffer_uptodate(bh))
1930 partial = 1;
1931 } else {
1932 set_buffer_uptodate(bh);
1933 mark_buffer_dirty(bh);
1934 }
Nick Pigginafddba42007-10-16 01:25:01 -07001935 clear_buffer_new(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936 }
1937
1938 /*
1939 * If this is a partial write which happened to make all buffers
1940 * uptodate then we can optimize away a bogus readpage() for
1941 * the next read(). Here we 'discover' whether the page went
1942 * uptodate as a result of this (potentially partial) write.
1943 */
1944 if (!partial)
1945 SetPageUptodate(page);
1946 return 0;
1947}
1948
1949/*
Nick Pigginafddba42007-10-16 01:25:01 -07001950 * block_write_begin takes care of the basic task of block allocation and
1951 * bringing partial write blocks uptodate first.
1952 *
1953 * If *pagep is not NULL, then block_write_begin uses the locked page
1954 * at *pagep rather than allocating its own. In this case, the page will
1955 * not be unlocked or deallocated on failure.
1956 */
1957int block_write_begin(struct file *file, struct address_space *mapping,
1958 loff_t pos, unsigned len, unsigned flags,
1959 struct page **pagep, void **fsdata,
1960 get_block_t *get_block)
1961{
1962 struct inode *inode = mapping->host;
1963 int status = 0;
1964 struct page *page;
1965 pgoff_t index;
1966 unsigned start, end;
1967 int ownpage = 0;
1968
1969 index = pos >> PAGE_CACHE_SHIFT;
1970 start = pos & (PAGE_CACHE_SIZE - 1);
1971 end = start + len;
1972
1973 page = *pagep;
1974 if (page == NULL) {
1975 ownpage = 1;
Nick Piggin54566b22009-01-04 12:00:53 -08001976 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Pigginafddba42007-10-16 01:25:01 -07001977 if (!page) {
1978 status = -ENOMEM;
1979 goto out;
1980 }
1981 *pagep = page;
1982 } else
1983 BUG_ON(!PageLocked(page));
1984
1985 status = __block_prepare_write(inode, page, start, end, get_block);
1986 if (unlikely(status)) {
1987 ClearPageUptodate(page);
1988
1989 if (ownpage) {
1990 unlock_page(page);
1991 page_cache_release(page);
1992 *pagep = NULL;
1993
1994 /*
1995 * prepare_write() may have instantiated a few blocks
1996 * outside i_size. Trim these off again. Don't need
1997 * i_size_read because we hold i_mutex.
1998 */
1999 if (pos + len > inode->i_size)
2000 vmtruncate(inode, inode->i_size);
2001 }
Nick Pigginafddba42007-10-16 01:25:01 -07002002 }
2003
2004out:
2005 return status;
2006}
2007EXPORT_SYMBOL(block_write_begin);
2008
2009int block_write_end(struct file *file, struct address_space *mapping,
2010 loff_t pos, unsigned len, unsigned copied,
2011 struct page *page, void *fsdata)
2012{
2013 struct inode *inode = mapping->host;
2014 unsigned start;
2015
2016 start = pos & (PAGE_CACHE_SIZE - 1);
2017
2018 if (unlikely(copied < len)) {
2019 /*
2020 * The buffers that were written will now be uptodate, so we
2021 * don't have to worry about a readpage reading them and
2022 * overwriting a partial write. However if we have encountered
2023 * a short write and only partially written into a buffer, it
2024 * will not be marked uptodate, so a readpage might come in and
2025 * destroy our partial write.
2026 *
2027 * Do the simplest thing, and just treat any short write to a
2028 * non uptodate page as a zero-length write, and force the
2029 * caller to redo the whole thing.
2030 */
2031 if (!PageUptodate(page))
2032 copied = 0;
2033
2034 page_zero_new_buffers(page, start+copied, start+len);
2035 }
2036 flush_dcache_page(page);
2037
2038 /* This could be a short (even 0-length) commit */
2039 __block_commit_write(inode, page, start, start+copied);
2040
2041 return copied;
2042}
2043EXPORT_SYMBOL(block_write_end);
2044
2045int generic_write_end(struct file *file, struct address_space *mapping,
2046 loff_t pos, unsigned len, unsigned copied,
2047 struct page *page, void *fsdata)
2048{
2049 struct inode *inode = mapping->host;
Jan Karac7d206b2008-07-11 19:27:31 -04002050 int i_size_changed = 0;
Nick Pigginafddba42007-10-16 01:25:01 -07002051
2052 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2053
2054 /*
2055 * No need to use i_size_read() here, the i_size
2056 * cannot change under us because we hold i_mutex.
2057 *
2058 * But it's important to update i_size while still holding page lock:
2059 * page writeout could otherwise come in and zero beyond i_size.
2060 */
2061 if (pos+copied > inode->i_size) {
2062 i_size_write(inode, pos+copied);
Jan Karac7d206b2008-07-11 19:27:31 -04002063 i_size_changed = 1;
Nick Pigginafddba42007-10-16 01:25:01 -07002064 }
2065
2066 unlock_page(page);
2067 page_cache_release(page);
2068
Jan Karac7d206b2008-07-11 19:27:31 -04002069 /*
2070 * Don't mark the inode dirty under page lock. First, it unnecessarily
2071 * makes the holding time of page lock longer. Second, it forces lock
2072 * ordering of page lock and transaction start for journaling
2073 * filesystems.
2074 */
2075 if (i_size_changed)
2076 mark_inode_dirty(inode);
2077
Nick Pigginafddba42007-10-16 01:25:01 -07002078 return copied;
2079}
2080EXPORT_SYMBOL(generic_write_end);
2081
2082/*
Hisashi Hifumi8ab22b92008-07-28 15:46:36 -07002083 * block_is_partially_uptodate checks whether buffers within a page are
2084 * uptodate or not.
2085 *
2086 * Returns true if all buffers which correspond to a file portion
2087 * we want to read are uptodate.
2088 */
2089int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2090 unsigned long from)
2091{
2092 struct inode *inode = page->mapping->host;
2093 unsigned block_start, block_end, blocksize;
2094 unsigned to;
2095 struct buffer_head *bh, *head;
2096 int ret = 1;
2097
2098 if (!page_has_buffers(page))
2099 return 0;
2100
2101 blocksize = 1 << inode->i_blkbits;
2102 to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2103 to = from + to;
2104 if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2105 return 0;
2106
2107 head = page_buffers(page);
2108 bh = head;
2109 block_start = 0;
2110 do {
2111 block_end = block_start + blocksize;
2112 if (block_end > from && block_start < to) {
2113 if (!buffer_uptodate(bh)) {
2114 ret = 0;
2115 break;
2116 }
2117 if (block_end >= to)
2118 break;
2119 }
2120 block_start = block_end;
2121 bh = bh->b_this_page;
2122 } while (bh != head);
2123
2124 return ret;
2125}
2126EXPORT_SYMBOL(block_is_partially_uptodate);
2127
2128/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002129 * Generic "read page" function for block devices that have the normal
2130 * get_block functionality. This is most of the block device filesystems.
2131 * Reads the page asynchronously --- the unlock_buffer() and
2132 * set/clear_buffer_uptodate() functions propagate buffer state into the
2133 * page struct once IO has completed.
2134 */
2135int block_read_full_page(struct page *page, get_block_t *get_block)
2136{
2137 struct inode *inode = page->mapping->host;
2138 sector_t iblock, lblock;
2139 struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2140 unsigned int blocksize;
2141 int nr, i;
2142 int fully_mapped = 1;
2143
Matt Mackallcd7619d2005-05-01 08:59:01 -07002144 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 blocksize = 1 << inode->i_blkbits;
2146 if (!page_has_buffers(page))
2147 create_empty_buffers(page, blocksize, 0);
2148 head = page_buffers(page);
2149
2150 iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2151 lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits;
2152 bh = head;
2153 nr = 0;
2154 i = 0;
2155
2156 do {
2157 if (buffer_uptodate(bh))
2158 continue;
2159
2160 if (!buffer_mapped(bh)) {
Andrew Mortonc64610b2005-05-16 21:53:49 -07002161 int err = 0;
2162
Linus Torvalds1da177e2005-04-16 15:20:36 -07002163 fully_mapped = 0;
2164 if (iblock < lblock) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002165 WARN_ON(bh->b_size != blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002166 err = get_block(inode, iblock, bh, 0);
2167 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002168 SetPageError(page);
2169 }
2170 if (!buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002171 zero_user(page, i * blocksize, blocksize);
Andrew Mortonc64610b2005-05-16 21:53:49 -07002172 if (!err)
2173 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002174 continue;
2175 }
2176 /*
2177 * get_block() might have updated the buffer
2178 * synchronously
2179 */
2180 if (buffer_uptodate(bh))
2181 continue;
2182 }
2183 arr[nr++] = bh;
2184 } while (i++, iblock++, (bh = bh->b_this_page) != head);
2185
2186 if (fully_mapped)
2187 SetPageMappedToDisk(page);
2188
2189 if (!nr) {
2190 /*
2191 * All buffers are uptodate - we can set the page uptodate
2192 * as well. But not if get_block() returned an error.
2193 */
2194 if (!PageError(page))
2195 SetPageUptodate(page);
2196 unlock_page(page);
2197 return 0;
2198 }
2199
2200 /* Stage two: lock the buffers */
2201 for (i = 0; i < nr; i++) {
2202 bh = arr[i];
2203 lock_buffer(bh);
2204 mark_buffer_async_read(bh);
2205 }
2206
2207 /*
2208 * Stage 3: start the IO. Check for uptodateness
2209 * inside the buffer lock in case another process reading
2210 * the underlying blockdev brought it uptodate (the sct fix).
2211 */
2212 for (i = 0; i < nr; i++) {
2213 bh = arr[i];
2214 if (buffer_uptodate(bh))
2215 end_buffer_async_read(bh, 1);
2216 else
2217 submit_bh(READ, bh);
2218 }
2219 return 0;
2220}
2221
2222/* utility function for filesystems that need to do work on expanding
Nick Piggin89e10782007-10-16 01:25:07 -07002223 * truncates. Uses filesystem pagecache writes to allow the filesystem to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 * deal with the hole.
2225 */
Nick Piggin89e10782007-10-16 01:25:07 -07002226int generic_cont_expand_simple(struct inode *inode, loff_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227{
2228 struct address_space *mapping = inode->i_mapping;
2229 struct page *page;
Nick Piggin89e10782007-10-16 01:25:07 -07002230 void *fsdata;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002231 unsigned long limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002232 int err;
2233
2234 err = -EFBIG;
2235 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
2236 if (limit != RLIM_INFINITY && size > (loff_t)limit) {
2237 send_sig(SIGXFSZ, current, 0);
2238 goto out;
2239 }
2240 if (size > inode->i_sb->s_maxbytes)
2241 goto out;
2242
Nick Piggin89e10782007-10-16 01:25:07 -07002243 err = pagecache_write_begin(NULL, mapping, size, 0,
2244 AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2245 &page, &fsdata);
2246 if (err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 goto out;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002248
Nick Piggin89e10782007-10-16 01:25:07 -07002249 err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2250 BUG_ON(err > 0);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002251
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252out:
2253 return err;
2254}
2255
Adrian Bunkf1e3af72008-04-29 00:59:01 -07002256static int cont_expand_zero(struct file *file, struct address_space *mapping,
2257 loff_t pos, loff_t *bytes)
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002258{
Nick Piggin89e10782007-10-16 01:25:07 -07002259 struct inode *inode = mapping->host;
2260 unsigned blocksize = 1 << inode->i_blkbits;
2261 struct page *page;
2262 void *fsdata;
2263 pgoff_t index, curidx;
2264 loff_t curpos;
2265 unsigned zerofrom, offset, len;
2266 int err = 0;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002267
Nick Piggin89e10782007-10-16 01:25:07 -07002268 index = pos >> PAGE_CACHE_SHIFT;
2269 offset = pos & ~PAGE_CACHE_MASK;
2270
2271 while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2272 zerofrom = curpos & ~PAGE_CACHE_MASK;
2273 if (zerofrom & (blocksize-1)) {
2274 *bytes |= (blocksize-1);
2275 (*bytes)++;
2276 }
2277 len = PAGE_CACHE_SIZE - zerofrom;
2278
2279 err = pagecache_write_begin(file, mapping, curpos, len,
2280 AOP_FLAG_UNINTERRUPTIBLE,
2281 &page, &fsdata);
2282 if (err)
2283 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002284 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002285 err = pagecache_write_end(file, mapping, curpos, len, len,
2286 page, fsdata);
2287 if (err < 0)
2288 goto out;
2289 BUG_ON(err != len);
2290 err = 0;
OGAWA Hirofumi061e9742008-04-28 02:16:28 -07002291
2292 balance_dirty_pages_ratelimited(mapping);
Nick Piggin89e10782007-10-16 01:25:07 -07002293 }
2294
2295 /* page covers the boundary, find the boundary offset */
2296 if (index == curidx) {
2297 zerofrom = curpos & ~PAGE_CACHE_MASK;
2298 /* if we will expand the thing last block will be filled */
2299 if (offset <= zerofrom) {
2300 goto out;
2301 }
2302 if (zerofrom & (blocksize-1)) {
2303 *bytes |= (blocksize-1);
2304 (*bytes)++;
2305 }
2306 len = offset - zerofrom;
2307
2308 err = pagecache_write_begin(file, mapping, curpos, len,
2309 AOP_FLAG_UNINTERRUPTIBLE,
2310 &page, &fsdata);
2311 if (err)
2312 goto out;
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002313 zero_user(page, zerofrom, len);
Nick Piggin89e10782007-10-16 01:25:07 -07002314 err = pagecache_write_end(file, mapping, curpos, len, len,
2315 page, fsdata);
2316 if (err < 0)
2317 goto out;
2318 BUG_ON(err != len);
2319 err = 0;
2320 }
2321out:
2322 return err;
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08002323}
2324
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325/*
2326 * For moronic filesystems that do not allow holes in file.
2327 * We may have to extend the file.
2328 */
Nick Piggin89e10782007-10-16 01:25:07 -07002329int cont_write_begin(struct file *file, struct address_space *mapping,
2330 loff_t pos, unsigned len, unsigned flags,
2331 struct page **pagep, void **fsdata,
2332 get_block_t *get_block, loff_t *bytes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002335 unsigned blocksize = 1 << inode->i_blkbits;
Nick Piggin89e10782007-10-16 01:25:07 -07002336 unsigned zerofrom;
2337 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338
Nick Piggin89e10782007-10-16 01:25:07 -07002339 err = cont_expand_zero(file, mapping, pos, bytes);
2340 if (err)
2341 goto out;
2342
2343 zerofrom = *bytes & ~PAGE_CACHE_MASK;
2344 if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2345 *bytes |= (blocksize-1);
2346 (*bytes)++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347 }
2348
Nick Piggin89e10782007-10-16 01:25:07 -07002349 *pagep = NULL;
2350 err = block_write_begin(file, mapping, pos, len,
2351 flags, pagep, fsdata, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002352out:
Nick Piggin89e10782007-10-16 01:25:07 -07002353 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354}
2355
2356int block_prepare_write(struct page *page, unsigned from, unsigned to,
2357 get_block_t *get_block)
2358{
2359 struct inode *inode = page->mapping->host;
2360 int err = __block_prepare_write(inode, page, from, to, get_block);
2361 if (err)
2362 ClearPageUptodate(page);
2363 return err;
2364}
2365
2366int block_commit_write(struct page *page, unsigned from, unsigned to)
2367{
2368 struct inode *inode = page->mapping->host;
2369 __block_commit_write(inode,page,from,to);
2370 return 0;
2371}
2372
David Chinner54171692007-07-19 17:39:55 +10002373/*
2374 * block_page_mkwrite() is not allowed to change the file size as it gets
2375 * called from a page fault handler when a page is first dirtied. Hence we must
2376 * be careful to check for EOF conditions here. We set the page up correctly
2377 * for a written page which means we get ENOSPC checking when writing into
2378 * holes and correct delalloc and unwritten extent mapping on filesystems that
2379 * support these features.
2380 *
2381 * We are not allowed to take the i_mutex here so we have to play games to
2382 * protect against truncate races as the page could now be beyond EOF. Because
2383 * vmtruncate() writes the inode size before removing pages, once we have the
2384 * page lock we can determine safely if the page is beyond EOF. If it is not
2385 * beyond EOF, then the page is guaranteed safe against truncation until we
2386 * unlock the page.
2387 */
2388int
Nick Pigginc2ec1752009-03-31 15:23:21 -07002389block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
David Chinner54171692007-07-19 17:39:55 +10002390 get_block_t get_block)
2391{
Nick Pigginc2ec1752009-03-31 15:23:21 -07002392 struct page *page = vmf->page;
David Chinner54171692007-07-19 17:39:55 +10002393 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
2394 unsigned long end;
2395 loff_t size;
Nick Piggin56a76f82009-03-31 15:23:23 -07002396 int ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
David Chinner54171692007-07-19 17:39:55 +10002397
2398 lock_page(page);
2399 size = i_size_read(inode);
2400 if ((page->mapping != inode->i_mapping) ||
Nick Piggin18336332007-07-20 00:31:45 -07002401 (page_offset(page) > size)) {
David Chinner54171692007-07-19 17:39:55 +10002402 /* page got truncated out from underneath us */
Nick Pigginb827e492009-04-30 15:08:16 -07002403 unlock_page(page);
2404 goto out;
David Chinner54171692007-07-19 17:39:55 +10002405 }
2406
2407 /* page is wholly or partially inside EOF */
2408 if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2409 end = size & ~PAGE_CACHE_MASK;
2410 else
2411 end = PAGE_CACHE_SIZE;
2412
2413 ret = block_prepare_write(page, 0, end, get_block);
2414 if (!ret)
2415 ret = block_commit_write(page, 0, end);
2416
Nick Piggin56a76f82009-03-31 15:23:23 -07002417 if (unlikely(ret)) {
Nick Pigginb827e492009-04-30 15:08:16 -07002418 unlock_page(page);
Nick Piggin56a76f82009-03-31 15:23:23 -07002419 if (ret == -ENOMEM)
2420 ret = VM_FAULT_OOM;
2421 else /* -ENOSPC, -EIO, etc */
2422 ret = VM_FAULT_SIGBUS;
Nick Pigginb827e492009-04-30 15:08:16 -07002423 } else
2424 ret = VM_FAULT_LOCKED;
Nick Pigginc2ec1752009-03-31 15:23:21 -07002425
Nick Pigginb827e492009-04-30 15:08:16 -07002426out:
David Chinner54171692007-07-19 17:39:55 +10002427 return ret;
2428}
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429
2430/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002431 * nobh_write_begin()'s prereads are special: the buffer_heads are freed
Linus Torvalds1da177e2005-04-16 15:20:36 -07002432 * immediately, while under the page lock. So it needs a special end_io
2433 * handler which does not touch the bh after unlocking it.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 */
2435static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2436{
Dmitry Monakhov68671f32007-10-16 01:24:47 -07002437 __end_buffer_read_notouch(bh, uptodate);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002438}
2439
2440/*
Nick Piggin03158cd2007-10-16 01:25:25 -07002441 * Attach the singly-linked list of buffers created by nobh_write_begin, to
2442 * the page (converting it to circular linked list and taking care of page
2443 * dirty races).
2444 */
2445static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2446{
2447 struct buffer_head *bh;
2448
2449 BUG_ON(!PageLocked(page));
2450
2451 spin_lock(&page->mapping->private_lock);
2452 bh = head;
2453 do {
2454 if (PageDirty(page))
2455 set_buffer_dirty(bh);
2456 if (!bh->b_this_page)
2457 bh->b_this_page = head;
2458 bh = bh->b_this_page;
2459 } while (bh != head);
2460 attach_page_buffers(page, head);
2461 spin_unlock(&page->mapping->private_lock);
2462}
2463
2464/*
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465 * On entry, the page is fully not uptodate.
2466 * On exit the page is fully uptodate in the areas outside (from,to)
2467 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002468int nobh_write_begin(struct file *file, struct address_space *mapping,
2469 loff_t pos, unsigned len, unsigned flags,
2470 struct page **pagep, void **fsdata,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002471 get_block_t *get_block)
2472{
Nick Piggin03158cd2007-10-16 01:25:25 -07002473 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 const unsigned blkbits = inode->i_blkbits;
2475 const unsigned blocksize = 1 << blkbits;
Nick Piggina4b06722007-10-16 01:24:48 -07002476 struct buffer_head *head, *bh;
Nick Piggin03158cd2007-10-16 01:25:25 -07002477 struct page *page;
2478 pgoff_t index;
2479 unsigned from, to;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002480 unsigned block_in_page;
Nick Piggina4b06722007-10-16 01:24:48 -07002481 unsigned block_start, block_end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482 sector_t block_in_file;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002483 int nr_reads = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484 int ret = 0;
2485 int is_mapped_to_disk = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486
Nick Piggin03158cd2007-10-16 01:25:25 -07002487 index = pos >> PAGE_CACHE_SHIFT;
2488 from = pos & (PAGE_CACHE_SIZE - 1);
2489 to = from + len;
2490
Nick Piggin54566b22009-01-04 12:00:53 -08002491 page = grab_cache_page_write_begin(mapping, index, flags);
Nick Piggin03158cd2007-10-16 01:25:25 -07002492 if (!page)
2493 return -ENOMEM;
2494 *pagep = page;
2495 *fsdata = NULL;
2496
2497 if (page_has_buffers(page)) {
2498 unlock_page(page);
2499 page_cache_release(page);
2500 *pagep = NULL;
2501 return block_write_begin(file, mapping, pos, len, flags, pagep,
2502 fsdata, get_block);
2503 }
Nick Piggina4b06722007-10-16 01:24:48 -07002504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505 if (PageMappedToDisk(page))
2506 return 0;
2507
Nick Piggina4b06722007-10-16 01:24:48 -07002508 /*
2509 * Allocate buffers so that we can keep track of state, and potentially
2510 * attach them to the page if an error occurs. In the common case of
2511 * no error, they will just be freed again without ever being attached
2512 * to the page (which is all OK, because we're under the page lock).
2513 *
2514 * Be careful: the buffer linked list is a NULL terminated one, rather
2515 * than the circular one we're used to.
2516 */
2517 head = alloc_page_buffers(page, blocksize, 0);
Nick Piggin03158cd2007-10-16 01:25:25 -07002518 if (!head) {
2519 ret = -ENOMEM;
2520 goto out_release;
2521 }
Nick Piggina4b06722007-10-16 01:24:48 -07002522
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524
2525 /*
2526 * We loop across all blocks in the page, whether or not they are
2527 * part of the affected region. This is so we can discover if the
2528 * page is fully mapped-to-disk.
2529 */
Nick Piggina4b06722007-10-16 01:24:48 -07002530 for (block_start = 0, block_in_page = 0, bh = head;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002531 block_start < PAGE_CACHE_SIZE;
Nick Piggina4b06722007-10-16 01:24:48 -07002532 block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002533 int create;
2534
Nick Piggina4b06722007-10-16 01:24:48 -07002535 block_end = block_start + blocksize;
2536 bh->b_state = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002537 create = 1;
2538 if (block_start >= to)
2539 create = 0;
2540 ret = get_block(inode, block_in_file + block_in_page,
Nick Piggina4b06722007-10-16 01:24:48 -07002541 bh, create);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002542 if (ret)
2543 goto failed;
Nick Piggina4b06722007-10-16 01:24:48 -07002544 if (!buffer_mapped(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002545 is_mapped_to_disk = 0;
Nick Piggina4b06722007-10-16 01:24:48 -07002546 if (buffer_new(bh))
2547 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2548 if (PageUptodate(page)) {
2549 set_buffer_uptodate(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002550 continue;
Nick Piggina4b06722007-10-16 01:24:48 -07002551 }
2552 if (buffer_new(bh) || !buffer_mapped(bh)) {
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002553 zero_user_segments(page, block_start, from,
2554 to, block_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555 continue;
2556 }
Nick Piggina4b06722007-10-16 01:24:48 -07002557 if (buffer_uptodate(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002558 continue; /* reiserfs does this */
2559 if (block_start < from || block_end > to) {
Nick Piggina4b06722007-10-16 01:24:48 -07002560 lock_buffer(bh);
2561 bh->b_end_io = end_buffer_read_nobh;
2562 submit_bh(READ, bh);
2563 nr_reads++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002564 }
2565 }
2566
2567 if (nr_reads) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 /*
2569 * The page is locked, so these buffers are protected from
2570 * any VM or truncate activity. Hence we don't need to care
2571 * for the buffer_head refcounts.
2572 */
Nick Piggina4b06722007-10-16 01:24:48 -07002573 for (bh = head; bh; bh = bh->b_this_page) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574 wait_on_buffer(bh);
2575 if (!buffer_uptodate(bh))
2576 ret = -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002577 }
2578 if (ret)
2579 goto failed;
2580 }
2581
2582 if (is_mapped_to_disk)
2583 SetPageMappedToDisk(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002584
Nick Piggin03158cd2007-10-16 01:25:25 -07002585 *fsdata = head; /* to be released by nobh_write_end */
Nick Piggina4b06722007-10-16 01:24:48 -07002586
Linus Torvalds1da177e2005-04-16 15:20:36 -07002587 return 0;
2588
2589failed:
Nick Piggin03158cd2007-10-16 01:25:25 -07002590 BUG_ON(!ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002591 /*
Nick Piggina4b06722007-10-16 01:24:48 -07002592 * Error recovery is a bit difficult. We need to zero out blocks that
2593 * were newly allocated, and dirty them to ensure they get written out.
2594 * Buffers need to be attached to the page at this point, otherwise
2595 * the handling of potential IO errors during writeout would be hard
2596 * (could try doing synchronous writeout, but what if that fails too?)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002597 */
Nick Piggin03158cd2007-10-16 01:25:25 -07002598 attach_nobh_buffers(page, head);
2599 page_zero_new_buffers(page, from, to);
Nick Piggina4b06722007-10-16 01:24:48 -07002600
Nick Piggin03158cd2007-10-16 01:25:25 -07002601out_release:
2602 unlock_page(page);
2603 page_cache_release(page);
2604 *pagep = NULL;
Nick Piggina4b06722007-10-16 01:24:48 -07002605
Nick Piggin03158cd2007-10-16 01:25:25 -07002606 if (pos + len > inode->i_size)
2607 vmtruncate(inode, inode->i_size);
Nick Piggina4b06722007-10-16 01:24:48 -07002608
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 return ret;
2610}
Nick Piggin03158cd2007-10-16 01:25:25 -07002611EXPORT_SYMBOL(nobh_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002612
Nick Piggin03158cd2007-10-16 01:25:25 -07002613int nobh_write_end(struct file *file, struct address_space *mapping,
2614 loff_t pos, unsigned len, unsigned copied,
2615 struct page *page, void *fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616{
2617 struct inode *inode = page->mapping->host;
Nick Pigginefdc3132007-10-21 06:57:41 +02002618 struct buffer_head *head = fsdata;
Nick Piggin03158cd2007-10-16 01:25:25 -07002619 struct buffer_head *bh;
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002620 BUG_ON(fsdata != NULL && page_has_buffers(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621
Dave Kleikampd4cf1092009-02-06 14:59:26 -06002622 if (unlikely(copied < len) && head)
Dmitri Monakhov5b41e742008-03-28 14:15:52 -07002623 attach_nobh_buffers(page, head);
2624 if (page_has_buffers(page))
2625 return generic_write_end(file, mapping, pos, len,
2626 copied, page, fsdata);
Nick Piggina4b06722007-10-16 01:24:48 -07002627
Nick Piggin22c8ca72007-02-20 13:58:09 -08002628 SetPageUptodate(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629 set_page_dirty(page);
Nick Piggin03158cd2007-10-16 01:25:25 -07002630 if (pos+copied > inode->i_size) {
2631 i_size_write(inode, pos+copied);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002632 mark_inode_dirty(inode);
2633 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002634
2635 unlock_page(page);
2636 page_cache_release(page);
2637
Nick Piggin03158cd2007-10-16 01:25:25 -07002638 while (head) {
2639 bh = head;
2640 head = head->b_this_page;
2641 free_buffer_head(bh);
2642 }
2643
2644 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002645}
Nick Piggin03158cd2007-10-16 01:25:25 -07002646EXPORT_SYMBOL(nobh_write_end);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647
2648/*
2649 * nobh_writepage() - based on block_full_write_page() except
2650 * that it tries to operate without attaching bufferheads to
2651 * the page.
2652 */
2653int nobh_writepage(struct page *page, get_block_t *get_block,
2654 struct writeback_control *wbc)
2655{
2656 struct inode * const inode = page->mapping->host;
2657 loff_t i_size = i_size_read(inode);
2658 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2659 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002660 int ret;
2661
2662 /* Is the page fully inside i_size? */
2663 if (page->index < end_index)
2664 goto out;
2665
2666 /* Is the page fully outside i_size? (truncate in progress) */
2667 offset = i_size & (PAGE_CACHE_SIZE-1);
2668 if (page->index >= end_index+1 || !offset) {
2669 /*
2670 * The page may have dirty, unmapped buffers. For example,
2671 * they may have been added in ext3_writepage(). Make them
2672 * freeable here, so the page does not leak.
2673 */
2674#if 0
2675 /* Not really sure about this - do we need this ? */
2676 if (page->mapping->a_ops->invalidatepage)
2677 page->mapping->a_ops->invalidatepage(page, offset);
2678#endif
2679 unlock_page(page);
2680 return 0; /* don't care */
2681 }
2682
2683 /*
2684 * The page straddles i_size. It must be zeroed out on each and every
2685 * writepage invocation because it may be mmapped. "A file is mapped
2686 * in multiples of the page size. For a file that is not a multiple of
2687 * the page size, the remaining memory is zeroed when mapped, and
2688 * writes to that region are not written out to the file."
2689 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002690 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002691out:
2692 ret = mpage_writepage(page, get_block, wbc);
2693 if (ret == -EAGAIN)
Chris Mason35c80d52009-04-15 13:22:38 -04002694 ret = __block_write_full_page(inode, page, get_block, wbc,
2695 end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002696 return ret;
2697}
2698EXPORT_SYMBOL(nobh_writepage);
2699
Nick Piggin03158cd2007-10-16 01:25:25 -07002700int nobh_truncate_page(struct address_space *mapping,
2701 loff_t from, get_block_t *get_block)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002702{
Linus Torvalds1da177e2005-04-16 15:20:36 -07002703 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2704 unsigned offset = from & (PAGE_CACHE_SIZE-1);
Nick Piggin03158cd2007-10-16 01:25:25 -07002705 unsigned blocksize;
2706 sector_t iblock;
2707 unsigned length, pos;
2708 struct inode *inode = mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002709 struct page *page;
Nick Piggin03158cd2007-10-16 01:25:25 -07002710 struct buffer_head map_bh;
2711 int err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002712
Nick Piggin03158cd2007-10-16 01:25:25 -07002713 blocksize = 1 << inode->i_blkbits;
2714 length = offset & (blocksize - 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002715
Nick Piggin03158cd2007-10-16 01:25:25 -07002716 /* Block boundary? Nothing to do */
2717 if (!length)
2718 return 0;
2719
2720 length = blocksize - length;
2721 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2722
Linus Torvalds1da177e2005-04-16 15:20:36 -07002723 page = grab_cache_page(mapping, index);
Nick Piggin03158cd2007-10-16 01:25:25 -07002724 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002725 if (!page)
2726 goto out;
2727
Nick Piggin03158cd2007-10-16 01:25:25 -07002728 if (page_has_buffers(page)) {
2729has_buffers:
2730 unlock_page(page);
2731 page_cache_release(page);
2732 return block_truncate_page(mapping, from, get_block);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002733 }
Nick Piggin03158cd2007-10-16 01:25:25 -07002734
2735 /* Find the buffer that contains "offset" */
2736 pos = blocksize;
2737 while (offset >= pos) {
2738 iblock++;
2739 pos += blocksize;
2740 }
2741
Theodore Ts'o460bcf52009-05-12 07:37:56 -04002742 map_bh.b_size = blocksize;
2743 map_bh.b_state = 0;
Nick Piggin03158cd2007-10-16 01:25:25 -07002744 err = get_block(inode, iblock, &map_bh, 0);
2745 if (err)
2746 goto unlock;
2747 /* unmapped? It's a hole - nothing to do */
2748 if (!buffer_mapped(&map_bh))
2749 goto unlock;
2750
2751 /* Ok, it's mapped. Make sure it's up-to-date */
2752 if (!PageUptodate(page)) {
2753 err = mapping->a_ops->readpage(NULL, page);
2754 if (err) {
2755 page_cache_release(page);
2756 goto out;
2757 }
2758 lock_page(page);
2759 if (!PageUptodate(page)) {
2760 err = -EIO;
2761 goto unlock;
2762 }
2763 if (page_has_buffers(page))
2764 goto has_buffers;
2765 }
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002766 zero_user(page, offset, length);
Nick Piggin03158cd2007-10-16 01:25:25 -07002767 set_page_dirty(page);
2768 err = 0;
2769
2770unlock:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002771 unlock_page(page);
2772 page_cache_release(page);
2773out:
Nick Piggin03158cd2007-10-16 01:25:25 -07002774 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775}
2776EXPORT_SYMBOL(nobh_truncate_page);
2777
2778int block_truncate_page(struct address_space *mapping,
2779 loff_t from, get_block_t *get_block)
2780{
2781 pgoff_t index = from >> PAGE_CACHE_SHIFT;
2782 unsigned offset = from & (PAGE_CACHE_SIZE-1);
2783 unsigned blocksize;
Andrew Morton54b21a72006-01-08 01:03:05 -08002784 sector_t iblock;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002785 unsigned length, pos;
2786 struct inode *inode = mapping->host;
2787 struct page *page;
2788 struct buffer_head *bh;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002789 int err;
2790
2791 blocksize = 1 << inode->i_blkbits;
2792 length = offset & (blocksize - 1);
2793
2794 /* Block boundary? Nothing to do */
2795 if (!length)
2796 return 0;
2797
2798 length = blocksize - length;
Andrew Morton54b21a72006-01-08 01:03:05 -08002799 iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800
2801 page = grab_cache_page(mapping, index);
2802 err = -ENOMEM;
2803 if (!page)
2804 goto out;
2805
2806 if (!page_has_buffers(page))
2807 create_empty_buffers(page, blocksize, 0);
2808
2809 /* Find the buffer that contains "offset" */
2810 bh = page_buffers(page);
2811 pos = blocksize;
2812 while (offset >= pos) {
2813 bh = bh->b_this_page;
2814 iblock++;
2815 pos += blocksize;
2816 }
2817
2818 err = 0;
2819 if (!buffer_mapped(bh)) {
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002820 WARN_ON(bh->b_size != blocksize);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821 err = get_block(inode, iblock, bh, 0);
2822 if (err)
2823 goto unlock;
2824 /* unmapped? It's a hole - nothing to do */
2825 if (!buffer_mapped(bh))
2826 goto unlock;
2827 }
2828
2829 /* Ok, it's mapped. Make sure it's up-to-date */
2830 if (PageUptodate(page))
2831 set_buffer_uptodate(bh);
2832
David Chinner33a266d2007-02-12 00:51:41 -08002833 if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002834 err = -EIO;
2835 ll_rw_block(READ, 1, &bh);
2836 wait_on_buffer(bh);
2837 /* Uhhuh. Read error. Complain and punt. */
2838 if (!buffer_uptodate(bh))
2839 goto unlock;
2840 }
2841
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002842 zero_user(page, offset, length);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002843 mark_buffer_dirty(bh);
2844 err = 0;
2845
2846unlock:
2847 unlock_page(page);
2848 page_cache_release(page);
2849out:
2850 return err;
2851}
2852
2853/*
2854 * The generic ->writepage function for buffer-backed address_spaces
Chris Mason35c80d52009-04-15 13:22:38 -04002855 * this form passes in the end_io handler used to finish the IO.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002856 */
Chris Mason35c80d52009-04-15 13:22:38 -04002857int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2858 struct writeback_control *wbc, bh_end_io_t *handler)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002859{
2860 struct inode * const inode = page->mapping->host;
2861 loff_t i_size = i_size_read(inode);
2862 const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2863 unsigned offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002864
2865 /* Is the page fully inside i_size? */
2866 if (page->index < end_index)
Chris Mason35c80d52009-04-15 13:22:38 -04002867 return __block_write_full_page(inode, page, get_block, wbc,
2868 handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002869
2870 /* Is the page fully outside i_size? (truncate in progress) */
2871 offset = i_size & (PAGE_CACHE_SIZE-1);
2872 if (page->index >= end_index+1 || !offset) {
2873 /*
2874 * The page may have dirty, unmapped buffers. For example,
2875 * they may have been added in ext3_writepage(). Make them
2876 * freeable here, so the page does not leak.
2877 */
Jan Karaaaa40592005-10-30 15:00:16 -08002878 do_invalidatepage(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002879 unlock_page(page);
2880 return 0; /* don't care */
2881 }
2882
2883 /*
2884 * The page straddles i_size. It must be zeroed out on each and every
2885 * writepage invokation because it may be mmapped. "A file is mapped
2886 * in multiples of the page size. For a file that is not a multiple of
2887 * the page size, the remaining memory is zeroed when mapped, and
2888 * writes to that region are not written out to the file."
2889 */
Christoph Lametereebd2aa2008-02-04 22:28:29 -08002890 zero_user_segment(page, offset, PAGE_CACHE_SIZE);
Chris Mason35c80d52009-04-15 13:22:38 -04002891 return __block_write_full_page(inode, page, get_block, wbc, handler);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002892}
2893
Chris Mason35c80d52009-04-15 13:22:38 -04002894/*
2895 * The generic ->writepage function for buffer-backed address_spaces
2896 */
2897int block_write_full_page(struct page *page, get_block_t *get_block,
2898 struct writeback_control *wbc)
2899{
2900 return block_write_full_page_endio(page, get_block, wbc,
2901 end_buffer_async_write);
2902}
2903
2904
Linus Torvalds1da177e2005-04-16 15:20:36 -07002905sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2906 get_block_t *get_block)
2907{
2908 struct buffer_head tmp;
2909 struct inode *inode = mapping->host;
2910 tmp.b_state = 0;
2911 tmp.b_blocknr = 0;
Badari Pulavartyb0cf2322006-03-26 01:38:00 -08002912 tmp.b_size = 1 << inode->i_blkbits;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002913 get_block(inode, block, &tmp, 0);
2914 return tmp.b_blocknr;
2915}
2916
NeilBrown6712ecf2007-09-27 12:47:43 +02002917static void end_bio_bh_io_sync(struct bio *bio, int err)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002918{
2919 struct buffer_head *bh = bio->bi_private;
2920
Linus Torvalds1da177e2005-04-16 15:20:36 -07002921 if (err == -EOPNOTSUPP) {
2922 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2923 set_bit(BH_Eopnotsupp, &bh->b_state);
2924 }
2925
Keith Mannthey08bafc02008-11-25 10:24:35 +01002926 if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2927 set_bit(BH_Quiet, &bh->b_state);
2928
Linus Torvalds1da177e2005-04-16 15:20:36 -07002929 bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2930 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002931}
2932
2933int submit_bh(int rw, struct buffer_head * bh)
2934{
2935 struct bio *bio;
2936 int ret = 0;
2937
2938 BUG_ON(!buffer_locked(bh));
2939 BUG_ON(!buffer_mapped(bh));
2940 BUG_ON(!bh->b_end_io);
Aneesh Kumar K.V8fb0e342009-05-12 16:22:37 -04002941 BUG_ON(buffer_delay(bh));
2942 BUG_ON(buffer_unwritten(bh));
Linus Torvalds1da177e2005-04-16 15:20:36 -07002943
Jens Axboe48fd4f92008-08-22 10:00:36 +02002944 /*
2945 * Mask in barrier bit for a write (could be either a WRITE or a
2946 * WRITE_SYNC
2947 */
2948 if (buffer_ordered(bh) && (rw & WRITE))
2949 rw |= WRITE_BARRIER;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002950
2951 /*
Jens Axboe48fd4f92008-08-22 10:00:36 +02002952 * Only clear out a write error when rewriting
Linus Torvalds1da177e2005-04-16 15:20:36 -07002953 */
Jens Axboe48fd4f92008-08-22 10:00:36 +02002954 if (test_set_buffer_req(bh) && (rw & WRITE))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002955 clear_buffer_write_io_error(bh);
2956
2957 /*
2958 * from here on down, it's all bio -- do the initial mapping,
2959 * submit_bio -> generic_make_request may further map this bio around
2960 */
2961 bio = bio_alloc(GFP_NOIO, 1);
2962
2963 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
2964 bio->bi_bdev = bh->b_bdev;
2965 bio->bi_io_vec[0].bv_page = bh->b_page;
2966 bio->bi_io_vec[0].bv_len = bh->b_size;
2967 bio->bi_io_vec[0].bv_offset = bh_offset(bh);
2968
2969 bio->bi_vcnt = 1;
2970 bio->bi_idx = 0;
2971 bio->bi_size = bh->b_size;
2972
2973 bio->bi_end_io = end_bio_bh_io_sync;
2974 bio->bi_private = bh;
2975
2976 bio_get(bio);
2977 submit_bio(rw, bio);
2978
2979 if (bio_flagged(bio, BIO_EOPNOTSUPP))
2980 ret = -EOPNOTSUPP;
2981
2982 bio_put(bio);
2983 return ret;
2984}
2985
2986/**
2987 * ll_rw_block: low-level access to block devices (DEPRECATED)
Jan Karaa7662232005-09-06 15:19:10 -07002988 * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002989 * @nr: number of &struct buffer_heads in the array
2990 * @bhs: array of pointers to &struct buffer_head
2991 *
Jan Karaa7662232005-09-06 15:19:10 -07002992 * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
2993 * requests an I/O operation on them, either a %READ or a %WRITE. The third
2994 * %SWRITE is like %WRITE only we make sure that the *current* data in buffers
2995 * are sent to disk. The fourth %READA option is described in the documentation
2996 * for generic_make_request() which ll_rw_block() calls.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002997 *
2998 * This function drops any buffer that it cannot get a lock on (with the
Jan Karaa7662232005-09-06 15:19:10 -07002999 * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be
3000 * clean when doing a write request, and any buffer that appears to be
3001 * up-to-date when doing read request. Further it marks as clean buffers that
3002 * are processed for writing (the buffer cache won't assume that they are
3003 * actually clean until the buffer gets unlocked).
Linus Torvalds1da177e2005-04-16 15:20:36 -07003004 *
3005 * ll_rw_block sets b_end_io to simple completion handler that marks
3006 * the buffer up-to-date (if approriate), unlocks the buffer and wakes
3007 * any waiters.
3008 *
3009 * All of the buffers must be for the same device, and must also be a
3010 * multiple of the current approved size for the device.
3011 */
3012void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3013{
3014 int i;
3015
3016 for (i = 0; i < nr; i++) {
3017 struct buffer_head *bh = bhs[i];
3018
Jens Axboe9cf6b722009-04-06 14:48:03 +02003019 if (rw == SWRITE || rw == SWRITE_SYNC || rw == SWRITE_SYNC_PLUG)
Jan Karaa7662232005-09-06 15:19:10 -07003020 lock_buffer(bh);
Nick Pigginca5de402008-08-02 12:02:13 +02003021 else if (!trylock_buffer(bh))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003022 continue;
3023
Jens Axboe9cf6b722009-04-06 14:48:03 +02003024 if (rw == WRITE || rw == SWRITE || rw == SWRITE_SYNC ||
3025 rw == SWRITE_SYNC_PLUG) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003026 if (test_clear_buffer_dirty(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003027 bh->b_end_io = end_buffer_write_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003028 get_bh(bh);
Jens Axboe18ce3752008-07-01 09:07:34 +02003029 if (rw == SWRITE_SYNC)
3030 submit_bh(WRITE_SYNC, bh);
3031 else
3032 submit_bh(WRITE, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003033 continue;
3034 }
3035 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07003036 if (!buffer_uptodate(bh)) {
akpm@osdl.org76c30732005-04-16 15:24:07 -07003037 bh->b_end_io = end_buffer_read_sync;
OGAWA Hirofumie60e5c52006-02-03 03:04:43 -08003038 get_bh(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003039 submit_bh(rw, bh);
3040 continue;
3041 }
3042 }
3043 unlock_buffer(bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003044 }
3045}
3046
3047/*
3048 * For a data-integrity writeout, we need to wait upon any in-progress I/O
3049 * and then start new I/O and then wait upon it. The caller must have a ref on
3050 * the buffer_head.
3051 */
3052int sync_dirty_buffer(struct buffer_head *bh)
3053{
3054 int ret = 0;
3055
3056 WARN_ON(atomic_read(&bh->b_count) < 1);
3057 lock_buffer(bh);
3058 if (test_clear_buffer_dirty(bh)) {
3059 get_bh(bh);
3060 bh->b_end_io = end_buffer_write_sync;
Jens Axboe1aa2a7c2009-04-06 14:48:08 +02003061 ret = submit_bh(WRITE_SYNC, bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003062 wait_on_buffer(bh);
3063 if (buffer_eopnotsupp(bh)) {
3064 clear_buffer_eopnotsupp(bh);
3065 ret = -EOPNOTSUPP;
3066 }
3067 if (!ret && !buffer_uptodate(bh))
3068 ret = -EIO;
3069 } else {
3070 unlock_buffer(bh);
3071 }
3072 return ret;
3073}
3074
3075/*
3076 * try_to_free_buffers() checks if all the buffers on this particular page
3077 * are unused, and releases them if so.
3078 *
3079 * Exclusion against try_to_free_buffers may be obtained by either
3080 * locking the page or by holding its mapping's private_lock.
3081 *
3082 * If the page is dirty but all the buffers are clean then we need to
3083 * be sure to mark the page clean as well. This is because the page
3084 * may be against a block device, and a later reattachment of buffers
3085 * to a dirty page will set *all* buffers dirty. Which would corrupt
3086 * filesystem data on the same device.
3087 *
3088 * The same applies to regular filesystem pages: if all the buffers are
3089 * clean then we set the page clean and proceed. To do that, we require
3090 * total exclusion from __set_page_dirty_buffers(). That is obtained with
3091 * private_lock.
3092 *
3093 * try_to_free_buffers() is non-blocking.
3094 */
3095static inline int buffer_busy(struct buffer_head *bh)
3096{
3097 return atomic_read(&bh->b_count) |
3098 (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3099}
3100
3101static int
3102drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3103{
3104 struct buffer_head *head = page_buffers(page);
3105 struct buffer_head *bh;
3106
3107 bh = head;
3108 do {
akpm@osdl.orgde7d5a32005-05-01 08:58:39 -07003109 if (buffer_write_io_error(bh) && page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003110 set_bit(AS_EIO, &page->mapping->flags);
3111 if (buffer_busy(bh))
3112 goto failed;
3113 bh = bh->b_this_page;
3114 } while (bh != head);
3115
3116 do {
3117 struct buffer_head *next = bh->b_this_page;
3118
Jan Kara535ee2f2008-02-08 04:21:59 -08003119 if (bh->b_assoc_map)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003120 __remove_assoc_queue(bh);
3121 bh = next;
3122 } while (bh != head);
3123 *buffers_to_free = head;
3124 __clear_page_buffers(page);
3125 return 1;
3126failed:
3127 return 0;
3128}
3129
3130int try_to_free_buffers(struct page *page)
3131{
3132 struct address_space * const mapping = page->mapping;
3133 struct buffer_head *buffers_to_free = NULL;
3134 int ret = 0;
3135
3136 BUG_ON(!PageLocked(page));
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003137 if (PageWriteback(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003138 return 0;
3139
3140 if (mapping == NULL) { /* can this still happen? */
3141 ret = drop_buffers(page, &buffers_to_free);
3142 goto out;
3143 }
3144
3145 spin_lock(&mapping->private_lock);
3146 ret = drop_buffers(page, &buffers_to_free);
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003147
3148 /*
3149 * If the filesystem writes its buffers by hand (eg ext3)
3150 * then we can have clean buffers against a dirty page. We
3151 * clean the page here; otherwise the VM will never notice
3152 * that the filesystem did any IO at all.
3153 *
3154 * Also, during truncate, discard_buffer will have marked all
3155 * the page's buffers clean. We discover that here and clean
3156 * the page also.
Nick Piggin87df7242007-01-30 14:36:27 +11003157 *
3158 * private_lock must be held over this entire operation in order
3159 * to synchronise against __set_page_dirty_buffers and prevent the
3160 * dirty bit from being lost.
Linus Torvaldsecdfc972007-01-26 12:47:06 -08003161 */
3162 if (ret)
3163 cancel_dirty_page(page, PAGE_CACHE_SIZE);
Nick Piggin87df7242007-01-30 14:36:27 +11003164 spin_unlock(&mapping->private_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003165out:
3166 if (buffers_to_free) {
3167 struct buffer_head *bh = buffers_to_free;
3168
3169 do {
3170 struct buffer_head *next = bh->b_this_page;
3171 free_buffer_head(bh);
3172 bh = next;
3173 } while (bh != buffers_to_free);
3174 }
3175 return ret;
3176}
3177EXPORT_SYMBOL(try_to_free_buffers);
3178
NeilBrown3978d712006-03-26 01:37:17 -08003179void block_sync_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003180{
3181 struct address_space *mapping;
3182
3183 smp_mb();
3184 mapping = page_mapping(page);
3185 if (mapping)
3186 blk_run_backing_dev(mapping->backing_dev_info, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003187}
3188
3189/*
3190 * There are no bdflush tunables left. But distributions are
3191 * still running obsolete flush daemons, so we terminate them here.
3192 *
3193 * Use of bdflush() is deprecated and will be removed in a future kernel.
3194 * The `pdflush' kernel threads fully replace bdflush daemons and this call.
3195 */
Heiko Carstensbdc480e2009-01-14 14:14:12 +01003196SYSCALL_DEFINE2(bdflush, int, func, long, data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003197{
3198 static int msg_count;
3199
3200 if (!capable(CAP_SYS_ADMIN))
3201 return -EPERM;
3202
3203 if (msg_count < 5) {
3204 msg_count++;
3205 printk(KERN_INFO
3206 "warning: process `%s' used the obsolete bdflush"
3207 " system call\n", current->comm);
3208 printk(KERN_INFO "Fix your initscripts?\n");
3209 }
3210
3211 if (func == 1)
3212 do_exit(0);
3213 return 0;
3214}
3215
3216/*
3217 * Buffer-head allocation
3218 */
Christoph Lametere18b8902006-12-06 20:33:20 -08003219static struct kmem_cache *bh_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003220
3221/*
3222 * Once the number of bh's in the machine exceeds this level, we start
3223 * stripping them in writeback.
3224 */
3225static int max_buffer_heads;
3226
3227int buffer_heads_over_limit;
3228
3229struct bh_accounting {
3230 int nr; /* Number of live bh's */
3231 int ratelimit; /* Limit cacheline bouncing */
3232};
3233
3234static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3235
3236static void recalc_bh_state(void)
3237{
3238 int i;
3239 int tot = 0;
3240
3241 if (__get_cpu_var(bh_accounting).ratelimit++ < 4096)
3242 return;
3243 __get_cpu_var(bh_accounting).ratelimit = 0;
Eric Dumazet8a143422006-03-24 03:18:10 -08003244 for_each_online_cpu(i)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003245 tot += per_cpu(bh_accounting, i).nr;
3246 buffer_heads_over_limit = (tot > max_buffer_heads);
3247}
3248
Al Virodd0fc662005-10-07 07:46:04 +01003249struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003250{
Christoph Lameter488514d2008-04-28 02:12:05 -07003251 struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003252 if (ret) {
Christoph Lametera35afb82007-05-16 22:10:57 -07003253 INIT_LIST_HEAD(&ret->b_assoc_buffers);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003254 get_cpu_var(bh_accounting).nr++;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003255 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003256 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003257 }
3258 return ret;
3259}
3260EXPORT_SYMBOL(alloc_buffer_head);
3261
3262void free_buffer_head(struct buffer_head *bh)
3263{
3264 BUG_ON(!list_empty(&bh->b_assoc_buffers));
3265 kmem_cache_free(bh_cachep, bh);
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003266 get_cpu_var(bh_accounting).nr--;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003267 recalc_bh_state();
Coywolf Qi Hunt736c7b82005-09-06 15:18:17 -07003268 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003269}
3270EXPORT_SYMBOL(free_buffer_head);
3271
Linus Torvalds1da177e2005-04-16 15:20:36 -07003272static void buffer_exit_cpu(int cpu)
3273{
3274 int i;
3275 struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3276
3277 for (i = 0; i < BH_LRU_SIZE; i++) {
3278 brelse(b->bhs[i]);
3279 b->bhs[i] = NULL;
3280 }
Eric Dumazet8a143422006-03-24 03:18:10 -08003281 get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr;
3282 per_cpu(bh_accounting, cpu).nr = 0;
3283 put_cpu_var(bh_accounting);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003284}
3285
3286static int buffer_cpu_notify(struct notifier_block *self,
3287 unsigned long action, void *hcpu)
3288{
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -07003289 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003290 buffer_exit_cpu((unsigned long)hcpu);
3291 return NOTIFY_OK;
3292}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003293
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003294/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003295 * bh_uptodate_or_lock - Test whether the buffer is uptodate
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003296 * @bh: struct buffer_head
3297 *
3298 * Return true if the buffer is up-to-date and false,
3299 * with the buffer locked, if not.
3300 */
3301int bh_uptodate_or_lock(struct buffer_head *bh)
3302{
3303 if (!buffer_uptodate(bh)) {
3304 lock_buffer(bh);
3305 if (!buffer_uptodate(bh))
3306 return 0;
3307 unlock_buffer(bh);
3308 }
3309 return 1;
3310}
3311EXPORT_SYMBOL(bh_uptodate_or_lock);
3312
3313/**
Randy Dunlapa6b91912008-03-19 17:01:00 -07003314 * bh_submit_read - Submit a locked buffer for reading
Aneesh Kumar K.V389d1b02008-01-28 23:58:26 -05003315 * @bh: struct buffer_head
3316 *
3317 * Returns zero on success and -EIO on error.
3318 */
3319int bh_submit_read(struct buffer_head *bh)
3320{
3321 BUG_ON(!buffer_locked(bh));
3322
3323 if (buffer_uptodate(bh)) {
3324 unlock_buffer(bh);
3325 return 0;
3326 }
3327
3328 get_bh(bh);
3329 bh->b_end_io = end_buffer_read_sync;
3330 submit_bh(READ, bh);
3331 wait_on_buffer(bh);
3332 if (buffer_uptodate(bh))
3333 return 0;
3334 return -EIO;
3335}
3336EXPORT_SYMBOL(bh_submit_read);
3337
Christoph Lameterb98938c2008-02-04 22:28:36 -08003338static void
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07003339init_buffer_head(void *data)
Christoph Lameterb98938c2008-02-04 22:28:36 -08003340{
3341 struct buffer_head *bh = data;
3342
3343 memset(bh, 0, sizeof(*bh));
3344 INIT_LIST_HEAD(&bh->b_assoc_buffers);
3345}
3346
Linus Torvalds1da177e2005-04-16 15:20:36 -07003347void __init buffer_init(void)
3348{
3349 int nrpages;
3350
Christoph Lameterb98938c2008-02-04 22:28:36 -08003351 bh_cachep = kmem_cache_create("buffer_head",
3352 sizeof(struct buffer_head), 0,
3353 (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3354 SLAB_MEM_SPREAD),
3355 init_buffer_head);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003356
3357 /*
3358 * Limit the bh occupancy to 10% of ZONE_NORMAL
3359 */
3360 nrpages = (nr_free_buffer_pages() * 10) / 100;
3361 max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3362 hotcpu_notifier(buffer_cpu_notify, 0);
3363}
3364
3365EXPORT_SYMBOL(__bforget);
3366EXPORT_SYMBOL(__brelse);
3367EXPORT_SYMBOL(__wait_on_buffer);
3368EXPORT_SYMBOL(block_commit_write);
3369EXPORT_SYMBOL(block_prepare_write);
David Chinner54171692007-07-19 17:39:55 +10003370EXPORT_SYMBOL(block_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003371EXPORT_SYMBOL(block_read_full_page);
3372EXPORT_SYMBOL(block_sync_page);
3373EXPORT_SYMBOL(block_truncate_page);
3374EXPORT_SYMBOL(block_write_full_page);
Chris Mason35c80d52009-04-15 13:22:38 -04003375EXPORT_SYMBOL(block_write_full_page_endio);
Nick Piggin89e10782007-10-16 01:25:07 -07003376EXPORT_SYMBOL(cont_write_begin);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003377EXPORT_SYMBOL(end_buffer_read_sync);
3378EXPORT_SYMBOL(end_buffer_write_sync);
Chris Mason35c80d52009-04-15 13:22:38 -04003379EXPORT_SYMBOL(end_buffer_async_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003380EXPORT_SYMBOL(file_fsync);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003381EXPORT_SYMBOL(generic_block_bmap);
OGAWA Hirofumi05eb0b52006-01-08 01:02:13 -08003382EXPORT_SYMBOL(generic_cont_expand_simple);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003383EXPORT_SYMBOL(init_buffer);
3384EXPORT_SYMBOL(invalidate_bdev);
3385EXPORT_SYMBOL(ll_rw_block);
3386EXPORT_SYMBOL(mark_buffer_dirty);
3387EXPORT_SYMBOL(submit_bh);
3388EXPORT_SYMBOL(sync_dirty_buffer);
3389EXPORT_SYMBOL(unlock_buffer);