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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
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 | ||
21 | #include <linux/config.h> | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/syscalls.h> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/mm.h> | |
26 | #include <linux/percpu.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/smp_lock.h> | |
16f7e0fe | 29 | #include <linux/capability.h> |
1da177e4 LT |
30 | #include <linux/blkdev.h> |
31 | #include <linux/file.h> | |
32 | #include <linux/quotaops.h> | |
33 | #include <linux/highmem.h> | |
34 | #include <linux/module.h> | |
35 | #include <linux/writeback.h> | |
36 | #include <linux/hash.h> | |
37 | #include <linux/suspend.h> | |
38 | #include <linux/buffer_head.h> | |
39 | #include <linux/bio.h> | |
40 | #include <linux/notifier.h> | |
41 | #include <linux/cpu.h> | |
42 | #include <linux/bitops.h> | |
43 | #include <linux/mpage.h> | |
fb1c8f93 | 44 | #include <linux/bit_spinlock.h> |
1da177e4 LT |
45 | |
46 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list); | |
47 | static void invalidate_bh_lrus(void); | |
48 | ||
49 | #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers) | |
50 | ||
51 | inline void | |
52 | init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private) | |
53 | { | |
54 | bh->b_end_io = handler; | |
55 | bh->b_private = private; | |
56 | } | |
57 | ||
58 | static int sync_buffer(void *word) | |
59 | { | |
60 | struct block_device *bd; | |
61 | struct buffer_head *bh | |
62 | = container_of(word, struct buffer_head, b_state); | |
63 | ||
64 | smp_mb(); | |
65 | bd = bh->b_bdev; | |
66 | if (bd) | |
67 | blk_run_address_space(bd->bd_inode->i_mapping); | |
68 | io_schedule(); | |
69 | return 0; | |
70 | } | |
71 | ||
72 | void fastcall __lock_buffer(struct buffer_head *bh) | |
73 | { | |
74 | wait_on_bit_lock(&bh->b_state, BH_Lock, sync_buffer, | |
75 | TASK_UNINTERRUPTIBLE); | |
76 | } | |
77 | EXPORT_SYMBOL(__lock_buffer); | |
78 | ||
79 | void fastcall unlock_buffer(struct buffer_head *bh) | |
80 | { | |
81 | clear_buffer_locked(bh); | |
82 | smp_mb__after_clear_bit(); | |
83 | wake_up_bit(&bh->b_state, BH_Lock); | |
84 | } | |
85 | ||
86 | /* | |
87 | * Block until a buffer comes unlocked. This doesn't stop it | |
88 | * from becoming locked again - you have to lock it yourself | |
89 | * if you want to preserve its state. | |
90 | */ | |
91 | void __wait_on_buffer(struct buffer_head * bh) | |
92 | { | |
93 | wait_on_bit(&bh->b_state, BH_Lock, sync_buffer, TASK_UNINTERRUPTIBLE); | |
94 | } | |
95 | ||
96 | static void | |
97 | __clear_page_buffers(struct page *page) | |
98 | { | |
99 | ClearPagePrivate(page); | |
4c21e2f2 | 100 | set_page_private(page, 0); |
1da177e4 LT |
101 | page_cache_release(page); |
102 | } | |
103 | ||
104 | static void buffer_io_error(struct buffer_head *bh) | |
105 | { | |
106 | char b[BDEVNAME_SIZE]; | |
107 | ||
108 | printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n", | |
109 | bdevname(bh->b_bdev, b), | |
110 | (unsigned long long)bh->b_blocknr); | |
111 | } | |
112 | ||
113 | /* | |
114 | * Default synchronous end-of-IO handler.. Just mark it up-to-date and | |
115 | * unlock the buffer. This is what ll_rw_block uses too. | |
116 | */ | |
117 | void end_buffer_read_sync(struct buffer_head *bh, int uptodate) | |
118 | { | |
119 | if (uptodate) { | |
120 | set_buffer_uptodate(bh); | |
121 | } else { | |
122 | /* This happens, due to failed READA attempts. */ | |
123 | clear_buffer_uptodate(bh); | |
124 | } | |
125 | unlock_buffer(bh); | |
126 | put_bh(bh); | |
127 | } | |
128 | ||
129 | void end_buffer_write_sync(struct buffer_head *bh, int uptodate) | |
130 | { | |
131 | char b[BDEVNAME_SIZE]; | |
132 | ||
133 | if (uptodate) { | |
134 | set_buffer_uptodate(bh); | |
135 | } else { | |
136 | if (!buffer_eopnotsupp(bh) && printk_ratelimit()) { | |
137 | buffer_io_error(bh); | |
138 | printk(KERN_WARNING "lost page write due to " | |
139 | "I/O error on %s\n", | |
140 | bdevname(bh->b_bdev, b)); | |
141 | } | |
142 | set_buffer_write_io_error(bh); | |
143 | clear_buffer_uptodate(bh); | |
144 | } | |
145 | unlock_buffer(bh); | |
146 | put_bh(bh); | |
147 | } | |
148 | ||
149 | /* | |
150 | * Write out and wait upon all the dirty data associated with a block | |
151 | * device via its mapping. Does not take the superblock lock. | |
152 | */ | |
153 | int sync_blockdev(struct block_device *bdev) | |
154 | { | |
155 | int ret = 0; | |
156 | ||
28fd1298 OH |
157 | if (bdev) |
158 | ret = filemap_write_and_wait(bdev->bd_inode->i_mapping); | |
1da177e4 LT |
159 | return ret; |
160 | } | |
161 | EXPORT_SYMBOL(sync_blockdev); | |
162 | ||
d25b9a1f | 163 | static void __fsync_super(struct super_block *sb) |
1da177e4 LT |
164 | { |
165 | sync_inodes_sb(sb, 0); | |
166 | DQUOT_SYNC(sb); | |
167 | lock_super(sb); | |
168 | if (sb->s_dirt && sb->s_op->write_super) | |
169 | sb->s_op->write_super(sb); | |
170 | unlock_super(sb); | |
171 | if (sb->s_op->sync_fs) | |
172 | sb->s_op->sync_fs(sb, 1); | |
173 | sync_blockdev(sb->s_bdev); | |
174 | sync_inodes_sb(sb, 1); | |
d25b9a1f | 175 | } |
1da177e4 | 176 | |
d25b9a1f OH |
177 | /* |
178 | * Write out and wait upon all dirty data associated with this | |
179 | * superblock. Filesystem data as well as the underlying block | |
180 | * device. Takes the superblock lock. | |
181 | */ | |
182 | int fsync_super(struct super_block *sb) | |
183 | { | |
184 | __fsync_super(sb); | |
1da177e4 LT |
185 | return sync_blockdev(sb->s_bdev); |
186 | } | |
187 | ||
188 | /* | |
189 | * Write out and wait upon all dirty data associated with this | |
190 | * device. Filesystem data as well as the underlying block | |
191 | * device. Takes the superblock lock. | |
192 | */ | |
193 | int fsync_bdev(struct block_device *bdev) | |
194 | { | |
195 | struct super_block *sb = get_super(bdev); | |
196 | if (sb) { | |
197 | int res = fsync_super(sb); | |
198 | drop_super(sb); | |
199 | return res; | |
200 | } | |
201 | return sync_blockdev(bdev); | |
202 | } | |
203 | ||
204 | /** | |
205 | * freeze_bdev -- lock a filesystem and force it into a consistent state | |
206 | * @bdev: blockdevice to lock | |
207 | * | |
c039e313 | 208 | * This takes the block device bd_mount_mutex to make sure no new mounts |
1da177e4 LT |
209 | * happen on bdev until thaw_bdev() is called. |
210 | * If a superblock is found on this device, we take the s_umount semaphore | |
211 | * on it to make sure nobody unmounts until the snapshot creation is done. | |
212 | */ | |
213 | struct super_block *freeze_bdev(struct block_device *bdev) | |
214 | { | |
215 | struct super_block *sb; | |
216 | ||
c039e313 | 217 | mutex_lock(&bdev->bd_mount_mutex); |
1da177e4 LT |
218 | sb = get_super(bdev); |
219 | if (sb && !(sb->s_flags & MS_RDONLY)) { | |
220 | sb->s_frozen = SB_FREEZE_WRITE; | |
d59dd462 | 221 | smp_wmb(); |
1da177e4 | 222 | |
d25b9a1f | 223 | __fsync_super(sb); |
1da177e4 LT |
224 | |
225 | sb->s_frozen = SB_FREEZE_TRANS; | |
d59dd462 | 226 | smp_wmb(); |
1da177e4 LT |
227 | |
228 | sync_blockdev(sb->s_bdev); | |
229 | ||
230 | if (sb->s_op->write_super_lockfs) | |
231 | sb->s_op->write_super_lockfs(sb); | |
232 | } | |
233 | ||
234 | sync_blockdev(bdev); | |
235 | return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */ | |
236 | } | |
237 | EXPORT_SYMBOL(freeze_bdev); | |
238 | ||
239 | /** | |
240 | * thaw_bdev -- unlock filesystem | |
241 | * @bdev: blockdevice to unlock | |
242 | * @sb: associated superblock | |
243 | * | |
244 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). | |
245 | */ | |
246 | void thaw_bdev(struct block_device *bdev, struct super_block *sb) | |
247 | { | |
248 | if (sb) { | |
249 | BUG_ON(sb->s_bdev != bdev); | |
250 | ||
251 | if (sb->s_op->unlockfs) | |
252 | sb->s_op->unlockfs(sb); | |
253 | sb->s_frozen = SB_UNFROZEN; | |
d59dd462 | 254 | smp_wmb(); |
1da177e4 LT |
255 | wake_up(&sb->s_wait_unfrozen); |
256 | drop_super(sb); | |
257 | } | |
258 | ||
c039e313 | 259 | mutex_unlock(&bdev->bd_mount_mutex); |
1da177e4 LT |
260 | } |
261 | EXPORT_SYMBOL(thaw_bdev); | |
262 | ||
263 | /* | |
264 | * sync everything. Start out by waking pdflush, because that writes back | |
265 | * all queues in parallel. | |
266 | */ | |
267 | static void do_sync(unsigned long wait) | |
268 | { | |
687a21ce | 269 | wakeup_pdflush(0); |
1da177e4 LT |
270 | sync_inodes(0); /* All mappings, inodes and their blockdevs */ |
271 | DQUOT_SYNC(NULL); | |
272 | sync_supers(); /* Write the superblocks */ | |
273 | sync_filesystems(0); /* Start syncing the filesystems */ | |
274 | sync_filesystems(wait); /* Waitingly sync the filesystems */ | |
275 | sync_inodes(wait); /* Mappings, inodes and blockdevs, again. */ | |
276 | if (!wait) | |
277 | printk("Emergency Sync complete\n"); | |
278 | if (unlikely(laptop_mode)) | |
279 | laptop_sync_completion(); | |
280 | } | |
281 | ||
282 | asmlinkage long sys_sync(void) | |
283 | { | |
284 | do_sync(1); | |
285 | return 0; | |
286 | } | |
287 | ||
288 | void emergency_sync(void) | |
289 | { | |
290 | pdflush_operation(do_sync, 0); | |
291 | } | |
292 | ||
293 | /* | |
294 | * Generic function to fsync a file. | |
295 | * | |
296 | * filp may be NULL if called via the msync of a vma. | |
297 | */ | |
298 | ||
299 | int file_fsync(struct file *filp, struct dentry *dentry, int datasync) | |
300 | { | |
301 | struct inode * inode = dentry->d_inode; | |
302 | struct super_block * sb; | |
303 | int ret, err; | |
304 | ||
305 | /* sync the inode to buffers */ | |
306 | ret = write_inode_now(inode, 0); | |
307 | ||
308 | /* sync the superblock to buffers */ | |
309 | sb = inode->i_sb; | |
310 | lock_super(sb); | |
311 | if (sb->s_op->write_super) | |
312 | sb->s_op->write_super(sb); | |
313 | unlock_super(sb); | |
314 | ||
315 | /* .. finally sync the buffers to disk */ | |
316 | err = sync_blockdev(sb->s_bdev); | |
317 | if (!ret) | |
318 | ret = err; | |
319 | return ret; | |
320 | } | |
321 | ||
18e79b40 | 322 | long do_fsync(struct file *file, int datasync) |
1da177e4 | 323 | { |
18e79b40 AM |
324 | int ret; |
325 | int err; | |
326 | struct address_space *mapping = file->f_mapping; | |
1da177e4 | 327 | |
1da177e4 LT |
328 | if (!file->f_op || !file->f_op->fsync) { |
329 | /* Why? We can still call filemap_fdatawrite */ | |
18e79b40 AM |
330 | ret = -EINVAL; |
331 | goto out; | |
1da177e4 LT |
332 | } |
333 | ||
334 | current->flags |= PF_SYNCWRITE; | |
335 | ret = filemap_fdatawrite(mapping); | |
336 | ||
337 | /* | |
18e79b40 AM |
338 | * We need to protect against concurrent writers, which could cause |
339 | * livelocks in fsync_buffers_list(). | |
1da177e4 | 340 | */ |
1b1dcc1b | 341 | mutex_lock(&mapping->host->i_mutex); |
dfb388bf | 342 | err = file->f_op->fsync(file, file->f_dentry, datasync); |
1da177e4 LT |
343 | if (!ret) |
344 | ret = err; | |
1b1dcc1b | 345 | mutex_unlock(&mapping->host->i_mutex); |
1da177e4 LT |
346 | err = filemap_fdatawait(mapping); |
347 | if (!ret) | |
348 | ret = err; | |
349 | current->flags &= ~PF_SYNCWRITE; | |
1da177e4 LT |
350 | out: |
351 | return ret; | |
352 | } | |
353 | ||
18e79b40 AM |
354 | static long __do_fsync(unsigned int fd, int datasync) |
355 | { | |
356 | struct file *file; | |
357 | int ret = -EBADF; | |
358 | ||
359 | file = fget(fd); | |
360 | if (file) { | |
361 | ret = do_fsync(file, datasync); | |
362 | fput(file); | |
363 | } | |
364 | return ret; | |
365 | } | |
366 | ||
dfb388bf | 367 | asmlinkage long sys_fsync(unsigned int fd) |
1da177e4 | 368 | { |
18e79b40 | 369 | return __do_fsync(fd, 0); |
dfb388bf | 370 | } |
1da177e4 | 371 | |
dfb388bf ON |
372 | asmlinkage long sys_fdatasync(unsigned int fd) |
373 | { | |
18e79b40 | 374 | return __do_fsync(fd, 1); |
1da177e4 LT |
375 | } |
376 | ||
377 | /* | |
378 | * Various filesystems appear to want __find_get_block to be non-blocking. | |
379 | * But it's the page lock which protects the buffers. To get around this, | |
380 | * we get exclusion from try_to_free_buffers with the blockdev mapping's | |
381 | * private_lock. | |
382 | * | |
383 | * Hack idea: for the blockdev mapping, i_bufferlist_lock contention | |
384 | * may be quite high. This code could TryLock the page, and if that | |
385 | * succeeds, there is no need to take private_lock. (But if | |
386 | * private_lock is contended then so is mapping->tree_lock). | |
387 | */ | |
388 | static struct buffer_head * | |
385fd4c5 | 389 | __find_get_block_slow(struct block_device *bdev, sector_t block) |
1da177e4 LT |
390 | { |
391 | struct inode *bd_inode = bdev->bd_inode; | |
392 | struct address_space *bd_mapping = bd_inode->i_mapping; | |
393 | struct buffer_head *ret = NULL; | |
394 | pgoff_t index; | |
395 | struct buffer_head *bh; | |
396 | struct buffer_head *head; | |
397 | struct page *page; | |
398 | int all_mapped = 1; | |
399 | ||
400 | index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits); | |
401 | page = find_get_page(bd_mapping, index); | |
402 | if (!page) | |
403 | goto out; | |
404 | ||
405 | spin_lock(&bd_mapping->private_lock); | |
406 | if (!page_has_buffers(page)) | |
407 | goto out_unlock; | |
408 | head = page_buffers(page); | |
409 | bh = head; | |
410 | do { | |
411 | if (bh->b_blocknr == block) { | |
412 | ret = bh; | |
413 | get_bh(bh); | |
414 | goto out_unlock; | |
415 | } | |
416 | if (!buffer_mapped(bh)) | |
417 | all_mapped = 0; | |
418 | bh = bh->b_this_page; | |
419 | } while (bh != head); | |
420 | ||
421 | /* we might be here because some of the buffers on this page are | |
422 | * not mapped. This is due to various races between | |
423 | * file io on the block device and getblk. It gets dealt with | |
424 | * elsewhere, don't buffer_error if we had some unmapped buffers | |
425 | */ | |
426 | if (all_mapped) { | |
427 | printk("__find_get_block_slow() failed. " | |
428 | "block=%llu, b_blocknr=%llu\n", | |
205f87f6 BP |
429 | (unsigned long long)block, |
430 | (unsigned long long)bh->b_blocknr); | |
431 | printk("b_state=0x%08lx, b_size=%zu\n", | |
432 | bh->b_state, bh->b_size); | |
1da177e4 LT |
433 | printk("device blocksize: %d\n", 1 << bd_inode->i_blkbits); |
434 | } | |
435 | out_unlock: | |
436 | spin_unlock(&bd_mapping->private_lock); | |
437 | page_cache_release(page); | |
438 | out: | |
439 | return ret; | |
440 | } | |
441 | ||
442 | /* If invalidate_buffers() will trash dirty buffers, it means some kind | |
443 | of fs corruption is going on. Trashing dirty data always imply losing | |
444 | information that was supposed to be just stored on the physical layer | |
445 | by the user. | |
446 | ||
447 | Thus invalidate_buffers in general usage is not allwowed to trash | |
448 | dirty buffers. For example ioctl(FLSBLKBUF) expects dirty data to | |
449 | be preserved. These buffers are simply skipped. | |
450 | ||
451 | We also skip buffers which are still in use. For example this can | |
452 | happen if a userspace program is reading the block device. | |
453 | ||
454 | NOTE: In the case where the user removed a removable-media-disk even if | |
455 | there's still dirty data not synced on disk (due a bug in the device driver | |
456 | or due an error of the user), by not destroying the dirty buffers we could | |
457 | generate corruption also on the next media inserted, thus a parameter is | |
458 | necessary to handle this case in the most safe way possible (trying | |
459 | to not corrupt also the new disk inserted with the data belonging to | |
460 | the old now corrupted disk). Also for the ramdisk the natural thing | |
461 | to do in order to release the ramdisk memory is to destroy dirty buffers. | |
462 | ||
463 | These are two special cases. Normal usage imply the device driver | |
464 | to issue a sync on the device (without waiting I/O completion) and | |
465 | then an invalidate_buffers call that doesn't trash dirty buffers. | |
466 | ||
467 | For handling cache coherency with the blkdev pagecache the 'update' case | |
468 | is been introduced. It is needed to re-read from disk any pinned | |
469 | buffer. NOTE: re-reading from disk is destructive so we can do it only | |
470 | when we assume nobody is changing the buffercache under our I/O and when | |
471 | we think the disk contains more recent information than the buffercache. | |
472 | The update == 1 pass marks the buffers we need to update, the update == 2 | |
473 | pass does the actual I/O. */ | |
474 | void invalidate_bdev(struct block_device *bdev, int destroy_dirty_buffers) | |
475 | { | |
476 | invalidate_bh_lrus(); | |
477 | /* | |
478 | * FIXME: what about destroy_dirty_buffers? | |
479 | * We really want to use invalidate_inode_pages2() for | |
480 | * that, but not until that's cleaned up. | |
481 | */ | |
482 | invalidate_inode_pages(bdev->bd_inode->i_mapping); | |
483 | } | |
484 | ||
485 | /* | |
486 | * Kick pdflush then try to free up some ZONE_NORMAL memory. | |
487 | */ | |
488 | static void free_more_memory(void) | |
489 | { | |
490 | struct zone **zones; | |
491 | pg_data_t *pgdat; | |
492 | ||
687a21ce | 493 | wakeup_pdflush(1024); |
1da177e4 LT |
494 | yield(); |
495 | ||
496 | for_each_pgdat(pgdat) { | |
af4ca457 | 497 | zones = pgdat->node_zonelists[gfp_zone(GFP_NOFS)].zones; |
1da177e4 | 498 | if (*zones) |
1ad539b2 | 499 | try_to_free_pages(zones, GFP_NOFS); |
1da177e4 LT |
500 | } |
501 | } | |
502 | ||
503 | /* | |
504 | * I/O completion handler for block_read_full_page() - pages | |
505 | * which come unlocked at the end of I/O. | |
506 | */ | |
507 | static void end_buffer_async_read(struct buffer_head *bh, int uptodate) | |
508 | { | |
1da177e4 | 509 | unsigned long flags; |
a3972203 | 510 | struct buffer_head *first; |
1da177e4 LT |
511 | struct buffer_head *tmp; |
512 | struct page *page; | |
513 | int page_uptodate = 1; | |
514 | ||
515 | BUG_ON(!buffer_async_read(bh)); | |
516 | ||
517 | page = bh->b_page; | |
518 | if (uptodate) { | |
519 | set_buffer_uptodate(bh); | |
520 | } else { | |
521 | clear_buffer_uptodate(bh); | |
522 | if (printk_ratelimit()) | |
523 | buffer_io_error(bh); | |
524 | SetPageError(page); | |
525 | } | |
526 | ||
527 | /* | |
528 | * Be _very_ careful from here on. Bad things can happen if | |
529 | * two buffer heads end IO at almost the same time and both | |
530 | * decide that the page is now completely done. | |
531 | */ | |
a3972203 NP |
532 | first = page_buffers(page); |
533 | local_irq_save(flags); | |
534 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
1da177e4 LT |
535 | clear_buffer_async_read(bh); |
536 | unlock_buffer(bh); | |
537 | tmp = bh; | |
538 | do { | |
539 | if (!buffer_uptodate(tmp)) | |
540 | page_uptodate = 0; | |
541 | if (buffer_async_read(tmp)) { | |
542 | BUG_ON(!buffer_locked(tmp)); | |
543 | goto still_busy; | |
544 | } | |
545 | tmp = tmp->b_this_page; | |
546 | } while (tmp != bh); | |
a3972203 NP |
547 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
548 | local_irq_restore(flags); | |
1da177e4 LT |
549 | |
550 | /* | |
551 | * If none of the buffers had errors and they are all | |
552 | * uptodate then we can set the page uptodate. | |
553 | */ | |
554 | if (page_uptodate && !PageError(page)) | |
555 | SetPageUptodate(page); | |
556 | unlock_page(page); | |
557 | return; | |
558 | ||
559 | still_busy: | |
a3972203 NP |
560 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
561 | local_irq_restore(flags); | |
1da177e4 LT |
562 | return; |
563 | } | |
564 | ||
565 | /* | |
566 | * Completion handler for block_write_full_page() - pages which are unlocked | |
567 | * during I/O, and which have PageWriteback cleared upon I/O completion. | |
568 | */ | |
569 | void end_buffer_async_write(struct buffer_head *bh, int uptodate) | |
570 | { | |
571 | char b[BDEVNAME_SIZE]; | |
1da177e4 | 572 | unsigned long flags; |
a3972203 | 573 | struct buffer_head *first; |
1da177e4 LT |
574 | struct buffer_head *tmp; |
575 | struct page *page; | |
576 | ||
577 | BUG_ON(!buffer_async_write(bh)); | |
578 | ||
579 | page = bh->b_page; | |
580 | if (uptodate) { | |
581 | set_buffer_uptodate(bh); | |
582 | } else { | |
583 | if (printk_ratelimit()) { | |
584 | buffer_io_error(bh); | |
585 | printk(KERN_WARNING "lost page write due to " | |
586 | "I/O error on %s\n", | |
587 | bdevname(bh->b_bdev, b)); | |
588 | } | |
589 | set_bit(AS_EIO, &page->mapping->flags); | |
590 | clear_buffer_uptodate(bh); | |
591 | SetPageError(page); | |
592 | } | |
593 | ||
a3972203 NP |
594 | first = page_buffers(page); |
595 | local_irq_save(flags); | |
596 | bit_spin_lock(BH_Uptodate_Lock, &first->b_state); | |
597 | ||
1da177e4 LT |
598 | clear_buffer_async_write(bh); |
599 | unlock_buffer(bh); | |
600 | tmp = bh->b_this_page; | |
601 | while (tmp != bh) { | |
602 | if (buffer_async_write(tmp)) { | |
603 | BUG_ON(!buffer_locked(tmp)); | |
604 | goto still_busy; | |
605 | } | |
606 | tmp = tmp->b_this_page; | |
607 | } | |
a3972203 NP |
608 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
609 | local_irq_restore(flags); | |
1da177e4 LT |
610 | end_page_writeback(page); |
611 | return; | |
612 | ||
613 | still_busy: | |
a3972203 NP |
614 | bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); |
615 | local_irq_restore(flags); | |
1da177e4 LT |
616 | return; |
617 | } | |
618 | ||
619 | /* | |
620 | * If a page's buffers are under async readin (end_buffer_async_read | |
621 | * completion) then there is a possibility that another thread of | |
622 | * control could lock one of the buffers after it has completed | |
623 | * but while some of the other buffers have not completed. This | |
624 | * locked buffer would confuse end_buffer_async_read() into not unlocking | |
625 | * the page. So the absence of BH_Async_Read tells end_buffer_async_read() | |
626 | * that this buffer is not under async I/O. | |
627 | * | |
628 | * The page comes unlocked when it has no locked buffer_async buffers | |
629 | * left. | |
630 | * | |
631 | * PageLocked prevents anyone starting new async I/O reads any of | |
632 | * the buffers. | |
633 | * | |
634 | * PageWriteback is used to prevent simultaneous writeout of the same | |
635 | * page. | |
636 | * | |
637 | * PageLocked prevents anyone from starting writeback of a page which is | |
638 | * under read I/O (PageWriteback is only ever set against a locked page). | |
639 | */ | |
640 | static void mark_buffer_async_read(struct buffer_head *bh) | |
641 | { | |
642 | bh->b_end_io = end_buffer_async_read; | |
643 | set_buffer_async_read(bh); | |
644 | } | |
645 | ||
646 | void mark_buffer_async_write(struct buffer_head *bh) | |
647 | { | |
648 | bh->b_end_io = end_buffer_async_write; | |
649 | set_buffer_async_write(bh); | |
650 | } | |
651 | EXPORT_SYMBOL(mark_buffer_async_write); | |
652 | ||
653 | ||
654 | /* | |
655 | * fs/buffer.c contains helper functions for buffer-backed address space's | |
656 | * fsync functions. A common requirement for buffer-based filesystems is | |
657 | * that certain data from the backing blockdev needs to be written out for | |
658 | * a successful fsync(). For example, ext2 indirect blocks need to be | |
659 | * written back and waited upon before fsync() returns. | |
660 | * | |
661 | * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(), | |
662 | * inode_has_buffers() and invalidate_inode_buffers() are provided for the | |
663 | * management of a list of dependent buffers at ->i_mapping->private_list. | |
664 | * | |
665 | * Locking is a little subtle: try_to_free_buffers() will remove buffers | |
666 | * from their controlling inode's queue when they are being freed. But | |
667 | * try_to_free_buffers() will be operating against the *blockdev* mapping | |
668 | * at the time, not against the S_ISREG file which depends on those buffers. | |
669 | * So the locking for private_list is via the private_lock in the address_space | |
670 | * which backs the buffers. Which is different from the address_space | |
671 | * against which the buffers are listed. So for a particular address_space, | |
672 | * mapping->private_lock does *not* protect mapping->private_list! In fact, | |
673 | * mapping->private_list will always be protected by the backing blockdev's | |
674 | * ->private_lock. | |
675 | * | |
676 | * Which introduces a requirement: all buffers on an address_space's | |
677 | * ->private_list must be from the same address_space: the blockdev's. | |
678 | * | |
679 | * address_spaces which do not place buffers at ->private_list via these | |
680 | * utility functions are free to use private_lock and private_list for | |
681 | * whatever they want. The only requirement is that list_empty(private_list) | |
682 | * be true at clear_inode() time. | |
683 | * | |
684 | * FIXME: clear_inode should not call invalidate_inode_buffers(). The | |
685 | * filesystems should do that. invalidate_inode_buffers() should just go | |
686 | * BUG_ON(!list_empty). | |
687 | * | |
688 | * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should | |
689 | * take an address_space, not an inode. And it should be called | |
690 | * mark_buffer_dirty_fsync() to clearly define why those buffers are being | |
691 | * queued up. | |
692 | * | |
693 | * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the | |
694 | * list if it is already on a list. Because if the buffer is on a list, | |
695 | * it *must* already be on the right one. If not, the filesystem is being | |
696 | * silly. This will save a ton of locking. But first we have to ensure | |
697 | * that buffers are taken *off* the old inode's list when they are freed | |
698 | * (presumably in truncate). That requires careful auditing of all | |
699 | * filesystems (do it inside bforget()). It could also be done by bringing | |
700 | * b_inode back. | |
701 | */ | |
702 | ||
703 | /* | |
704 | * The buffer's backing address_space's private_lock must be held | |
705 | */ | |
706 | static inline void __remove_assoc_queue(struct buffer_head *bh) | |
707 | { | |
708 | list_del_init(&bh->b_assoc_buffers); | |
709 | } | |
710 | ||
711 | int inode_has_buffers(struct inode *inode) | |
712 | { | |
713 | return !list_empty(&inode->i_data.private_list); | |
714 | } | |
715 | ||
716 | /* | |
717 | * osync is designed to support O_SYNC io. It waits synchronously for | |
718 | * all already-submitted IO to complete, but does not queue any new | |
719 | * writes to the disk. | |
720 | * | |
721 | * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as | |
722 | * you dirty the buffers, and then use osync_inode_buffers to wait for | |
723 | * completion. Any other dirty buffers which are not yet queued for | |
724 | * write will not be flushed to disk by the osync. | |
725 | */ | |
726 | static int osync_buffers_list(spinlock_t *lock, struct list_head *list) | |
727 | { | |
728 | struct buffer_head *bh; | |
729 | struct list_head *p; | |
730 | int err = 0; | |
731 | ||
732 | spin_lock(lock); | |
733 | repeat: | |
734 | list_for_each_prev(p, list) { | |
735 | bh = BH_ENTRY(p); | |
736 | if (buffer_locked(bh)) { | |
737 | get_bh(bh); | |
738 | spin_unlock(lock); | |
739 | wait_on_buffer(bh); | |
740 | if (!buffer_uptodate(bh)) | |
741 | err = -EIO; | |
742 | brelse(bh); | |
743 | spin_lock(lock); | |
744 | goto repeat; | |
745 | } | |
746 | } | |
747 | spin_unlock(lock); | |
748 | return err; | |
749 | } | |
750 | ||
751 | /** | |
752 | * sync_mapping_buffers - write out and wait upon a mapping's "associated" | |
753 | * buffers | |
67be2dd1 | 754 | * @mapping: the mapping which wants those buffers written |
1da177e4 LT |
755 | * |
756 | * Starts I/O against the buffers at mapping->private_list, and waits upon | |
757 | * that I/O. | |
758 | * | |
67be2dd1 MW |
759 | * Basically, this is a convenience function for fsync(). |
760 | * @mapping is a file or directory which needs those buffers to be written for | |
761 | * a successful fsync(). | |
1da177e4 LT |
762 | */ |
763 | int sync_mapping_buffers(struct address_space *mapping) | |
764 | { | |
765 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
766 | ||
767 | if (buffer_mapping == NULL || list_empty(&mapping->private_list)) | |
768 | return 0; | |
769 | ||
770 | return fsync_buffers_list(&buffer_mapping->private_lock, | |
771 | &mapping->private_list); | |
772 | } | |
773 | EXPORT_SYMBOL(sync_mapping_buffers); | |
774 | ||
775 | /* | |
776 | * Called when we've recently written block `bblock', and it is known that | |
777 | * `bblock' was for a buffer_boundary() buffer. This means that the block at | |
778 | * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's | |
779 | * dirty, schedule it for IO. So that indirects merge nicely with their data. | |
780 | */ | |
781 | void write_boundary_block(struct block_device *bdev, | |
782 | sector_t bblock, unsigned blocksize) | |
783 | { | |
784 | struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize); | |
785 | if (bh) { | |
786 | if (buffer_dirty(bh)) | |
787 | ll_rw_block(WRITE, 1, &bh); | |
788 | put_bh(bh); | |
789 | } | |
790 | } | |
791 | ||
792 | void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode) | |
793 | { | |
794 | struct address_space *mapping = inode->i_mapping; | |
795 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
796 | ||
797 | mark_buffer_dirty(bh); | |
798 | if (!mapping->assoc_mapping) { | |
799 | mapping->assoc_mapping = buffer_mapping; | |
800 | } else { | |
801 | if (mapping->assoc_mapping != buffer_mapping) | |
802 | BUG(); | |
803 | } | |
804 | if (list_empty(&bh->b_assoc_buffers)) { | |
805 | spin_lock(&buffer_mapping->private_lock); | |
806 | list_move_tail(&bh->b_assoc_buffers, | |
807 | &mapping->private_list); | |
808 | spin_unlock(&buffer_mapping->private_lock); | |
809 | } | |
810 | } | |
811 | EXPORT_SYMBOL(mark_buffer_dirty_inode); | |
812 | ||
813 | /* | |
814 | * Add a page to the dirty page list. | |
815 | * | |
816 | * It is a sad fact of life that this function is called from several places | |
817 | * deeply under spinlocking. It may not sleep. | |
818 | * | |
819 | * If the page has buffers, the uptodate buffers are set dirty, to preserve | |
820 | * dirty-state coherency between the page and the buffers. It the page does | |
821 | * not have buffers then when they are later attached they will all be set | |
822 | * dirty. | |
823 | * | |
824 | * The buffers are dirtied before the page is dirtied. There's a small race | |
825 | * window in which a writepage caller may see the page cleanness but not the | |
826 | * buffer dirtiness. That's fine. If this code were to set the page dirty | |
827 | * before the buffers, a concurrent writepage caller could clear the page dirty | |
828 | * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean | |
829 | * page on the dirty page list. | |
830 | * | |
831 | * We use private_lock to lock against try_to_free_buffers while using the | |
832 | * page's buffer list. Also use this to protect against clean buffers being | |
833 | * added to the page after it was set dirty. | |
834 | * | |
835 | * FIXME: may need to call ->reservepage here as well. That's rather up to the | |
836 | * address_space though. | |
837 | */ | |
838 | int __set_page_dirty_buffers(struct page *page) | |
839 | { | |
840 | struct address_space * const mapping = page->mapping; | |
841 | ||
842 | spin_lock(&mapping->private_lock); | |
843 | if (page_has_buffers(page)) { | |
844 | struct buffer_head *head = page_buffers(page); | |
845 | struct buffer_head *bh = head; | |
846 | ||
847 | do { | |
848 | set_buffer_dirty(bh); | |
849 | bh = bh->b_this_page; | |
850 | } while (bh != head); | |
851 | } | |
852 | spin_unlock(&mapping->private_lock); | |
853 | ||
854 | if (!TestSetPageDirty(page)) { | |
855 | write_lock_irq(&mapping->tree_lock); | |
856 | if (page->mapping) { /* Race with truncate? */ | |
857 | if (mapping_cap_account_dirty(mapping)) | |
858 | inc_page_state(nr_dirty); | |
859 | radix_tree_tag_set(&mapping->page_tree, | |
860 | page_index(page), | |
861 | PAGECACHE_TAG_DIRTY); | |
862 | } | |
863 | write_unlock_irq(&mapping->tree_lock); | |
864 | __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); | |
4741c9fd | 865 | return 1; |
1da177e4 | 866 | } |
1da177e4 LT |
867 | return 0; |
868 | } | |
869 | EXPORT_SYMBOL(__set_page_dirty_buffers); | |
870 | ||
871 | /* | |
872 | * Write out and wait upon a list of buffers. | |
873 | * | |
874 | * We have conflicting pressures: we want to make sure that all | |
875 | * initially dirty buffers get waited on, but that any subsequently | |
876 | * dirtied buffers don't. After all, we don't want fsync to last | |
877 | * forever if somebody is actively writing to the file. | |
878 | * | |
879 | * Do this in two main stages: first we copy dirty buffers to a | |
880 | * temporary inode list, queueing the writes as we go. Then we clean | |
881 | * up, waiting for those writes to complete. | |
882 | * | |
883 | * During this second stage, any subsequent updates to the file may end | |
884 | * up refiling the buffer on the original inode's dirty list again, so | |
885 | * there is a chance we will end up with a buffer queued for write but | |
886 | * not yet completed on that list. So, as a final cleanup we go through | |
887 | * the osync code to catch these locked, dirty buffers without requeuing | |
888 | * any newly dirty buffers for write. | |
889 | */ | |
890 | static int fsync_buffers_list(spinlock_t *lock, struct list_head *list) | |
891 | { | |
892 | struct buffer_head *bh; | |
893 | struct list_head tmp; | |
894 | int err = 0, err2; | |
895 | ||
896 | INIT_LIST_HEAD(&tmp); | |
897 | ||
898 | spin_lock(lock); | |
899 | while (!list_empty(list)) { | |
900 | bh = BH_ENTRY(list->next); | |
901 | list_del_init(&bh->b_assoc_buffers); | |
902 | if (buffer_dirty(bh) || buffer_locked(bh)) { | |
903 | list_add(&bh->b_assoc_buffers, &tmp); | |
904 | if (buffer_dirty(bh)) { | |
905 | get_bh(bh); | |
906 | spin_unlock(lock); | |
907 | /* | |
908 | * Ensure any pending I/O completes so that | |
909 | * ll_rw_block() actually writes the current | |
910 | * contents - it is a noop if I/O is still in | |
911 | * flight on potentially older contents. | |
912 | */ | |
a7662236 | 913 | ll_rw_block(SWRITE, 1, &bh); |
1da177e4 LT |
914 | brelse(bh); |
915 | spin_lock(lock); | |
916 | } | |
917 | } | |
918 | } | |
919 | ||
920 | while (!list_empty(&tmp)) { | |
921 | bh = BH_ENTRY(tmp.prev); | |
922 | __remove_assoc_queue(bh); | |
923 | get_bh(bh); | |
924 | spin_unlock(lock); | |
925 | wait_on_buffer(bh); | |
926 | if (!buffer_uptodate(bh)) | |
927 | err = -EIO; | |
928 | brelse(bh); | |
929 | spin_lock(lock); | |
930 | } | |
931 | ||
932 | spin_unlock(lock); | |
933 | err2 = osync_buffers_list(lock, list); | |
934 | if (err) | |
935 | return err; | |
936 | else | |
937 | return err2; | |
938 | } | |
939 | ||
940 | /* | |
941 | * Invalidate any and all dirty buffers on a given inode. We are | |
942 | * probably unmounting the fs, but that doesn't mean we have already | |
943 | * done a sync(). Just drop the buffers from the inode list. | |
944 | * | |
945 | * NOTE: we take the inode's blockdev's mapping's private_lock. Which | |
946 | * assumes that all the buffers are against the blockdev. Not true | |
947 | * for reiserfs. | |
948 | */ | |
949 | void invalidate_inode_buffers(struct inode *inode) | |
950 | { | |
951 | if (inode_has_buffers(inode)) { | |
952 | struct address_space *mapping = &inode->i_data; | |
953 | struct list_head *list = &mapping->private_list; | |
954 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
955 | ||
956 | spin_lock(&buffer_mapping->private_lock); | |
957 | while (!list_empty(list)) | |
958 | __remove_assoc_queue(BH_ENTRY(list->next)); | |
959 | spin_unlock(&buffer_mapping->private_lock); | |
960 | } | |
961 | } | |
962 | ||
963 | /* | |
964 | * Remove any clean buffers from the inode's buffer list. This is called | |
965 | * when we're trying to free the inode itself. Those buffers can pin it. | |
966 | * | |
967 | * Returns true if all buffers were removed. | |
968 | */ | |
969 | int remove_inode_buffers(struct inode *inode) | |
970 | { | |
971 | int ret = 1; | |
972 | ||
973 | if (inode_has_buffers(inode)) { | |
974 | struct address_space *mapping = &inode->i_data; | |
975 | struct list_head *list = &mapping->private_list; | |
976 | struct address_space *buffer_mapping = mapping->assoc_mapping; | |
977 | ||
978 | spin_lock(&buffer_mapping->private_lock); | |
979 | while (!list_empty(list)) { | |
980 | struct buffer_head *bh = BH_ENTRY(list->next); | |
981 | if (buffer_dirty(bh)) { | |
982 | ret = 0; | |
983 | break; | |
984 | } | |
985 | __remove_assoc_queue(bh); | |
986 | } | |
987 | spin_unlock(&buffer_mapping->private_lock); | |
988 | } | |
989 | return ret; | |
990 | } | |
991 | ||
992 | /* | |
993 | * Create the appropriate buffers when given a page for data area and | |
994 | * the size of each buffer.. Use the bh->b_this_page linked list to | |
995 | * follow the buffers created. Return NULL if unable to create more | |
996 | * buffers. | |
997 | * | |
998 | * The retry flag is used to differentiate async IO (paging, swapping) | |
999 | * which may not fail from ordinary buffer allocations. | |
1000 | */ | |
1001 | struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size, | |
1002 | int retry) | |
1003 | { | |
1004 | struct buffer_head *bh, *head; | |
1005 | long offset; | |
1006 | ||
1007 | try_again: | |
1008 | head = NULL; | |
1009 | offset = PAGE_SIZE; | |
1010 | while ((offset -= size) >= 0) { | |
1011 | bh = alloc_buffer_head(GFP_NOFS); | |
1012 | if (!bh) | |
1013 | goto no_grow; | |
1014 | ||
1015 | bh->b_bdev = NULL; | |
1016 | bh->b_this_page = head; | |
1017 | bh->b_blocknr = -1; | |
1018 | head = bh; | |
1019 | ||
1020 | bh->b_state = 0; | |
1021 | atomic_set(&bh->b_count, 0); | |
fc5cd582 | 1022 | bh->b_private = NULL; |
1da177e4 LT |
1023 | bh->b_size = size; |
1024 | ||
1025 | /* Link the buffer to its page */ | |
1026 | set_bh_page(bh, page, offset); | |
1027 | ||
01ffe339 | 1028 | init_buffer(bh, NULL, NULL); |
1da177e4 LT |
1029 | } |
1030 | return head; | |
1031 | /* | |
1032 | * In case anything failed, we just free everything we got. | |
1033 | */ | |
1034 | no_grow: | |
1035 | if (head) { | |
1036 | do { | |
1037 | bh = head; | |
1038 | head = head->b_this_page; | |
1039 | free_buffer_head(bh); | |
1040 | } while (head); | |
1041 | } | |
1042 | ||
1043 | /* | |
1044 | * Return failure for non-async IO requests. Async IO requests | |
1045 | * are not allowed to fail, so we have to wait until buffer heads | |
1046 | * become available. But we don't want tasks sleeping with | |
1047 | * partially complete buffers, so all were released above. | |
1048 | */ | |
1049 | if (!retry) | |
1050 | return NULL; | |
1051 | ||
1052 | /* We're _really_ low on memory. Now we just | |
1053 | * wait for old buffer heads to become free due to | |
1054 | * finishing IO. Since this is an async request and | |
1055 | * the reserve list is empty, we're sure there are | |
1056 | * async buffer heads in use. | |
1057 | */ | |
1058 | free_more_memory(); | |
1059 | goto try_again; | |
1060 | } | |
1061 | EXPORT_SYMBOL_GPL(alloc_page_buffers); | |
1062 | ||
1063 | static inline void | |
1064 | link_dev_buffers(struct page *page, struct buffer_head *head) | |
1065 | { | |
1066 | struct buffer_head *bh, *tail; | |
1067 | ||
1068 | bh = head; | |
1069 | do { | |
1070 | tail = bh; | |
1071 | bh = bh->b_this_page; | |
1072 | } while (bh); | |
1073 | tail->b_this_page = head; | |
1074 | attach_page_buffers(page, head); | |
1075 | } | |
1076 | ||
1077 | /* | |
1078 | * Initialise the state of a blockdev page's buffers. | |
1079 | */ | |
1080 | static void | |
1081 | init_page_buffers(struct page *page, struct block_device *bdev, | |
1082 | sector_t block, int size) | |
1083 | { | |
1084 | struct buffer_head *head = page_buffers(page); | |
1085 | struct buffer_head *bh = head; | |
1086 | int uptodate = PageUptodate(page); | |
1087 | ||
1088 | do { | |
1089 | if (!buffer_mapped(bh)) { | |
1090 | init_buffer(bh, NULL, NULL); | |
1091 | bh->b_bdev = bdev; | |
1092 | bh->b_blocknr = block; | |
1093 | if (uptodate) | |
1094 | set_buffer_uptodate(bh); | |
1095 | set_buffer_mapped(bh); | |
1096 | } | |
1097 | block++; | |
1098 | bh = bh->b_this_page; | |
1099 | } while (bh != head); | |
1100 | } | |
1101 | ||
1102 | /* | |
1103 | * Create the page-cache page that contains the requested block. | |
1104 | * | |
1105 | * This is user purely for blockdev mappings. | |
1106 | */ | |
1107 | static struct page * | |
1108 | grow_dev_page(struct block_device *bdev, sector_t block, | |
1109 | pgoff_t index, int size) | |
1110 | { | |
1111 | struct inode *inode = bdev->bd_inode; | |
1112 | struct page *page; | |
1113 | struct buffer_head *bh; | |
1114 | ||
1115 | page = find_or_create_page(inode->i_mapping, index, GFP_NOFS); | |
1116 | if (!page) | |
1117 | return NULL; | |
1118 | ||
1119 | if (!PageLocked(page)) | |
1120 | BUG(); | |
1121 | ||
1122 | if (page_has_buffers(page)) { | |
1123 | bh = page_buffers(page); | |
1124 | if (bh->b_size == size) { | |
1125 | init_page_buffers(page, bdev, block, size); | |
1126 | return page; | |
1127 | } | |
1128 | if (!try_to_free_buffers(page)) | |
1129 | goto failed; | |
1130 | } | |
1131 | ||
1132 | /* | |
1133 | * Allocate some buffers for this page | |
1134 | */ | |
1135 | bh = alloc_page_buffers(page, size, 0); | |
1136 | if (!bh) | |
1137 | goto failed; | |
1138 | ||
1139 | /* | |
1140 | * Link the page to the buffers and initialise them. Take the | |
1141 | * lock to be atomic wrt __find_get_block(), which does not | |
1142 | * run under the page lock. | |
1143 | */ | |
1144 | spin_lock(&inode->i_mapping->private_lock); | |
1145 | link_dev_buffers(page, bh); | |
1146 | init_page_buffers(page, bdev, block, size); | |
1147 | spin_unlock(&inode->i_mapping->private_lock); | |
1148 | return page; | |
1149 | ||
1150 | failed: | |
1151 | BUG(); | |
1152 | unlock_page(page); | |
1153 | page_cache_release(page); | |
1154 | return NULL; | |
1155 | } | |
1156 | ||
1157 | /* | |
1158 | * Create buffers for the specified block device block's page. If | |
1159 | * that page was dirty, the buffers are set dirty also. | |
1160 | * | |
1161 | * Except that's a bug. Attaching dirty buffers to a dirty | |
1162 | * blockdev's page can result in filesystem corruption, because | |
1163 | * some of those buffers may be aliases of filesystem data. | |
1164 | * grow_dev_page() will go BUG() if this happens. | |
1165 | */ | |
858119e1 | 1166 | static int |
1da177e4 LT |
1167 | grow_buffers(struct block_device *bdev, sector_t block, int size) |
1168 | { | |
1169 | struct page *page; | |
1170 | pgoff_t index; | |
1171 | int sizebits; | |
1172 | ||
1173 | sizebits = -1; | |
1174 | do { | |
1175 | sizebits++; | |
1176 | } while ((size << sizebits) < PAGE_SIZE); | |
1177 | ||
1178 | index = block >> sizebits; | |
1179 | block = index << sizebits; | |
1180 | ||
1181 | /* Create a page with the proper size buffers.. */ | |
1182 | page = grow_dev_page(bdev, block, index, size); | |
1183 | if (!page) | |
1184 | return 0; | |
1185 | unlock_page(page); | |
1186 | page_cache_release(page); | |
1187 | return 1; | |
1188 | } | |
1189 | ||
75c96f85 | 1190 | static struct buffer_head * |
1da177e4 LT |
1191 | __getblk_slow(struct block_device *bdev, sector_t block, int size) |
1192 | { | |
1193 | /* Size must be multiple of hard sectorsize */ | |
1194 | if (unlikely(size & (bdev_hardsect_size(bdev)-1) || | |
1195 | (size < 512 || size > PAGE_SIZE))) { | |
1196 | printk(KERN_ERR "getblk(): invalid block size %d requested\n", | |
1197 | size); | |
1198 | printk(KERN_ERR "hardsect size: %d\n", | |
1199 | bdev_hardsect_size(bdev)); | |
1200 | ||
1201 | dump_stack(); | |
1202 | return NULL; | |
1203 | } | |
1204 | ||
1205 | for (;;) { | |
1206 | struct buffer_head * bh; | |
1207 | ||
1208 | bh = __find_get_block(bdev, block, size); | |
1209 | if (bh) | |
1210 | return bh; | |
1211 | ||
1212 | if (!grow_buffers(bdev, block, size)) | |
1213 | free_more_memory(); | |
1214 | } | |
1215 | } | |
1216 | ||
1217 | /* | |
1218 | * The relationship between dirty buffers and dirty pages: | |
1219 | * | |
1220 | * Whenever a page has any dirty buffers, the page's dirty bit is set, and | |
1221 | * the page is tagged dirty in its radix tree. | |
1222 | * | |
1223 | * At all times, the dirtiness of the buffers represents the dirtiness of | |
1224 | * subsections of the page. If the page has buffers, the page dirty bit is | |
1225 | * merely a hint about the true dirty state. | |
1226 | * | |
1227 | * When a page is set dirty in its entirety, all its buffers are marked dirty | |
1228 | * (if the page has buffers). | |
1229 | * | |
1230 | * When a buffer is marked dirty, its page is dirtied, but the page's other | |
1231 | * buffers are not. | |
1232 | * | |
1233 | * Also. When blockdev buffers are explicitly read with bread(), they | |
1234 | * individually become uptodate. But their backing page remains not | |
1235 | * uptodate - even if all of its buffers are uptodate. A subsequent | |
1236 | * block_read_full_page() against that page will discover all the uptodate | |
1237 | * buffers, will set the page uptodate and will perform no I/O. | |
1238 | */ | |
1239 | ||
1240 | /** | |
1241 | * mark_buffer_dirty - mark a buffer_head as needing writeout | |
67be2dd1 | 1242 | * @bh: the buffer_head to mark dirty |
1da177e4 LT |
1243 | * |
1244 | * mark_buffer_dirty() will set the dirty bit against the buffer, then set its | |
1245 | * backing page dirty, then tag the page as dirty in its address_space's radix | |
1246 | * tree and then attach the address_space's inode to its superblock's dirty | |
1247 | * inode list. | |
1248 | * | |
1249 | * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock, | |
1250 | * mapping->tree_lock and the global inode_lock. | |
1251 | */ | |
1252 | void fastcall mark_buffer_dirty(struct buffer_head *bh) | |
1253 | { | |
1254 | if (!buffer_dirty(bh) && !test_set_buffer_dirty(bh)) | |
1255 | __set_page_dirty_nobuffers(bh->b_page); | |
1256 | } | |
1257 | ||
1258 | /* | |
1259 | * Decrement a buffer_head's reference count. If all buffers against a page | |
1260 | * have zero reference count, are clean and unlocked, and if the page is clean | |
1261 | * and unlocked then try_to_free_buffers() may strip the buffers from the page | |
1262 | * in preparation for freeing it (sometimes, rarely, buffers are removed from | |
1263 | * a page but it ends up not being freed, and buffers may later be reattached). | |
1264 | */ | |
1265 | void __brelse(struct buffer_head * buf) | |
1266 | { | |
1267 | if (atomic_read(&buf->b_count)) { | |
1268 | put_bh(buf); | |
1269 | return; | |
1270 | } | |
1271 | printk(KERN_ERR "VFS: brelse: Trying to free free buffer\n"); | |
1272 | WARN_ON(1); | |
1273 | } | |
1274 | ||
1275 | /* | |
1276 | * bforget() is like brelse(), except it discards any | |
1277 | * potentially dirty data. | |
1278 | */ | |
1279 | void __bforget(struct buffer_head *bh) | |
1280 | { | |
1281 | clear_buffer_dirty(bh); | |
1282 | if (!list_empty(&bh->b_assoc_buffers)) { | |
1283 | struct address_space *buffer_mapping = bh->b_page->mapping; | |
1284 | ||
1285 | spin_lock(&buffer_mapping->private_lock); | |
1286 | list_del_init(&bh->b_assoc_buffers); | |
1287 | spin_unlock(&buffer_mapping->private_lock); | |
1288 | } | |
1289 | __brelse(bh); | |
1290 | } | |
1291 | ||
1292 | static struct buffer_head *__bread_slow(struct buffer_head *bh) | |
1293 | { | |
1294 | lock_buffer(bh); | |
1295 | if (buffer_uptodate(bh)) { | |
1296 | unlock_buffer(bh); | |
1297 | return bh; | |
1298 | } else { | |
1299 | get_bh(bh); | |
1300 | bh->b_end_io = end_buffer_read_sync; | |
1301 | submit_bh(READ, bh); | |
1302 | wait_on_buffer(bh); | |
1303 | if (buffer_uptodate(bh)) | |
1304 | return bh; | |
1305 | } | |
1306 | brelse(bh); | |
1307 | return NULL; | |
1308 | } | |
1309 | ||
1310 | /* | |
1311 | * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block(). | |
1312 | * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their | |
1313 | * refcount elevated by one when they're in an LRU. A buffer can only appear | |
1314 | * once in a particular CPU's LRU. A single buffer can be present in multiple | |
1315 | * CPU's LRUs at the same time. | |
1316 | * | |
1317 | * This is a transparent caching front-end to sb_bread(), sb_getblk() and | |
1318 | * sb_find_get_block(). | |
1319 | * | |
1320 | * The LRUs themselves only need locking against invalidate_bh_lrus. We use | |
1321 | * a local interrupt disable for that. | |
1322 | */ | |
1323 | ||
1324 | #define BH_LRU_SIZE 8 | |
1325 | ||
1326 | struct bh_lru { | |
1327 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1328 | }; | |
1329 | ||
1330 | static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }}; | |
1331 | ||
1332 | #ifdef CONFIG_SMP | |
1333 | #define bh_lru_lock() local_irq_disable() | |
1334 | #define bh_lru_unlock() local_irq_enable() | |
1335 | #else | |
1336 | #define bh_lru_lock() preempt_disable() | |
1337 | #define bh_lru_unlock() preempt_enable() | |
1338 | #endif | |
1339 | ||
1340 | static inline void check_irqs_on(void) | |
1341 | { | |
1342 | #ifdef irqs_disabled | |
1343 | BUG_ON(irqs_disabled()); | |
1344 | #endif | |
1345 | } | |
1346 | ||
1347 | /* | |
1348 | * The LRU management algorithm is dopey-but-simple. Sorry. | |
1349 | */ | |
1350 | static void bh_lru_install(struct buffer_head *bh) | |
1351 | { | |
1352 | struct buffer_head *evictee = NULL; | |
1353 | struct bh_lru *lru; | |
1354 | ||
1355 | check_irqs_on(); | |
1356 | bh_lru_lock(); | |
1357 | lru = &__get_cpu_var(bh_lrus); | |
1358 | if (lru->bhs[0] != bh) { | |
1359 | struct buffer_head *bhs[BH_LRU_SIZE]; | |
1360 | int in; | |
1361 | int out = 0; | |
1362 | ||
1363 | get_bh(bh); | |
1364 | bhs[out++] = bh; | |
1365 | for (in = 0; in < BH_LRU_SIZE; in++) { | |
1366 | struct buffer_head *bh2 = lru->bhs[in]; | |
1367 | ||
1368 | if (bh2 == bh) { | |
1369 | __brelse(bh2); | |
1370 | } else { | |
1371 | if (out >= BH_LRU_SIZE) { | |
1372 | BUG_ON(evictee != NULL); | |
1373 | evictee = bh2; | |
1374 | } else { | |
1375 | bhs[out++] = bh2; | |
1376 | } | |
1377 | } | |
1378 | } | |
1379 | while (out < BH_LRU_SIZE) | |
1380 | bhs[out++] = NULL; | |
1381 | memcpy(lru->bhs, bhs, sizeof(bhs)); | |
1382 | } | |
1383 | bh_lru_unlock(); | |
1384 | ||
1385 | if (evictee) | |
1386 | __brelse(evictee); | |
1387 | } | |
1388 | ||
1389 | /* | |
1390 | * Look up the bh in this cpu's LRU. If it's there, move it to the head. | |
1391 | */ | |
858119e1 | 1392 | static struct buffer_head * |
1da177e4 LT |
1393 | lookup_bh_lru(struct block_device *bdev, sector_t block, int size) |
1394 | { | |
1395 | struct buffer_head *ret = NULL; | |
1396 | struct bh_lru *lru; | |
1397 | int i; | |
1398 | ||
1399 | check_irqs_on(); | |
1400 | bh_lru_lock(); | |
1401 | lru = &__get_cpu_var(bh_lrus); | |
1402 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1403 | struct buffer_head *bh = lru->bhs[i]; | |
1404 | ||
1405 | if (bh && bh->b_bdev == bdev && | |
1406 | bh->b_blocknr == block && bh->b_size == size) { | |
1407 | if (i) { | |
1408 | while (i) { | |
1409 | lru->bhs[i] = lru->bhs[i - 1]; | |
1410 | i--; | |
1411 | } | |
1412 | lru->bhs[0] = bh; | |
1413 | } | |
1414 | get_bh(bh); | |
1415 | ret = bh; | |
1416 | break; | |
1417 | } | |
1418 | } | |
1419 | bh_lru_unlock(); | |
1420 | return ret; | |
1421 | } | |
1422 | ||
1423 | /* | |
1424 | * Perform a pagecache lookup for the matching buffer. If it's there, refresh | |
1425 | * it in the LRU and mark it as accessed. If it is not present then return | |
1426 | * NULL | |
1427 | */ | |
1428 | struct buffer_head * | |
1429 | __find_get_block(struct block_device *bdev, sector_t block, int size) | |
1430 | { | |
1431 | struct buffer_head *bh = lookup_bh_lru(bdev, block, size); | |
1432 | ||
1433 | if (bh == NULL) { | |
385fd4c5 | 1434 | bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1435 | if (bh) |
1436 | bh_lru_install(bh); | |
1437 | } | |
1438 | if (bh) | |
1439 | touch_buffer(bh); | |
1440 | return bh; | |
1441 | } | |
1442 | EXPORT_SYMBOL(__find_get_block); | |
1443 | ||
1444 | /* | |
1445 | * __getblk will locate (and, if necessary, create) the buffer_head | |
1446 | * which corresponds to the passed block_device, block and size. The | |
1447 | * returned buffer has its reference count incremented. | |
1448 | * | |
1449 | * __getblk() cannot fail - it just keeps trying. If you pass it an | |
1450 | * illegal block number, __getblk() will happily return a buffer_head | |
1451 | * which represents the non-existent block. Very weird. | |
1452 | * | |
1453 | * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers() | |
1454 | * attempt is failing. FIXME, perhaps? | |
1455 | */ | |
1456 | struct buffer_head * | |
1457 | __getblk(struct block_device *bdev, sector_t block, int size) | |
1458 | { | |
1459 | struct buffer_head *bh = __find_get_block(bdev, block, size); | |
1460 | ||
1461 | might_sleep(); | |
1462 | if (bh == NULL) | |
1463 | bh = __getblk_slow(bdev, block, size); | |
1464 | return bh; | |
1465 | } | |
1466 | EXPORT_SYMBOL(__getblk); | |
1467 | ||
1468 | /* | |
1469 | * Do async read-ahead on a buffer.. | |
1470 | */ | |
1471 | void __breadahead(struct block_device *bdev, sector_t block, int size) | |
1472 | { | |
1473 | struct buffer_head *bh = __getblk(bdev, block, size); | |
a3e713b5 AM |
1474 | if (likely(bh)) { |
1475 | ll_rw_block(READA, 1, &bh); | |
1476 | brelse(bh); | |
1477 | } | |
1da177e4 LT |
1478 | } |
1479 | EXPORT_SYMBOL(__breadahead); | |
1480 | ||
1481 | /** | |
1482 | * __bread() - reads a specified block and returns the bh | |
67be2dd1 | 1483 | * @bdev: the block_device to read from |
1da177e4 LT |
1484 | * @block: number of block |
1485 | * @size: size (in bytes) to read | |
1486 | * | |
1487 | * Reads a specified block, and returns buffer head that contains it. | |
1488 | * It returns NULL if the block was unreadable. | |
1489 | */ | |
1490 | struct buffer_head * | |
1491 | __bread(struct block_device *bdev, sector_t block, int size) | |
1492 | { | |
1493 | struct buffer_head *bh = __getblk(bdev, block, size); | |
1494 | ||
a3e713b5 | 1495 | if (likely(bh) && !buffer_uptodate(bh)) |
1da177e4 LT |
1496 | bh = __bread_slow(bh); |
1497 | return bh; | |
1498 | } | |
1499 | EXPORT_SYMBOL(__bread); | |
1500 | ||
1501 | /* | |
1502 | * invalidate_bh_lrus() is called rarely - but not only at unmount. | |
1503 | * This doesn't race because it runs in each cpu either in irq | |
1504 | * or with preempt disabled. | |
1505 | */ | |
1506 | static void invalidate_bh_lru(void *arg) | |
1507 | { | |
1508 | struct bh_lru *b = &get_cpu_var(bh_lrus); | |
1509 | int i; | |
1510 | ||
1511 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
1512 | brelse(b->bhs[i]); | |
1513 | b->bhs[i] = NULL; | |
1514 | } | |
1515 | put_cpu_var(bh_lrus); | |
1516 | } | |
1517 | ||
1518 | static void invalidate_bh_lrus(void) | |
1519 | { | |
1520 | on_each_cpu(invalidate_bh_lru, NULL, 1, 1); | |
1521 | } | |
1522 | ||
1523 | void set_bh_page(struct buffer_head *bh, | |
1524 | struct page *page, unsigned long offset) | |
1525 | { | |
1526 | bh->b_page = page; | |
1527 | if (offset >= PAGE_SIZE) | |
1528 | BUG(); | |
1529 | if (PageHighMem(page)) | |
1530 | /* | |
1531 | * This catches illegal uses and preserves the offset: | |
1532 | */ | |
1533 | bh->b_data = (char *)(0 + offset); | |
1534 | else | |
1535 | bh->b_data = page_address(page) + offset; | |
1536 | } | |
1537 | EXPORT_SYMBOL(set_bh_page); | |
1538 | ||
1539 | /* | |
1540 | * Called when truncating a buffer on a page completely. | |
1541 | */ | |
858119e1 | 1542 | static void discard_buffer(struct buffer_head * bh) |
1da177e4 LT |
1543 | { |
1544 | lock_buffer(bh); | |
1545 | clear_buffer_dirty(bh); | |
1546 | bh->b_bdev = NULL; | |
1547 | clear_buffer_mapped(bh); | |
1548 | clear_buffer_req(bh); | |
1549 | clear_buffer_new(bh); | |
1550 | clear_buffer_delay(bh); | |
1551 | unlock_buffer(bh); | |
1552 | } | |
1553 | ||
1554 | /** | |
1555 | * try_to_release_page() - release old fs-specific metadata on a page | |
1556 | * | |
1557 | * @page: the page which the kernel is trying to free | |
1558 | * @gfp_mask: memory allocation flags (and I/O mode) | |
1559 | * | |
1560 | * The address_space is to try to release any data against the page | |
1561 | * (presumably at page->private). If the release was successful, return `1'. | |
1562 | * Otherwise return zero. | |
1563 | * | |
1564 | * The @gfp_mask argument specifies whether I/O may be performed to release | |
1565 | * this page (__GFP_IO), and whether the call may block (__GFP_WAIT). | |
1566 | * | |
1567 | * NOTE: @gfp_mask may go away, and this function may become non-blocking. | |
1568 | */ | |
27496a8c | 1569 | int try_to_release_page(struct page *page, gfp_t gfp_mask) |
1da177e4 LT |
1570 | { |
1571 | struct address_space * const mapping = page->mapping; | |
1572 | ||
1573 | BUG_ON(!PageLocked(page)); | |
1574 | if (PageWriteback(page)) | |
1575 | return 0; | |
1576 | ||
1577 | if (mapping && mapping->a_ops->releasepage) | |
1578 | return mapping->a_ops->releasepage(page, gfp_mask); | |
1579 | return try_to_free_buffers(page); | |
1580 | } | |
1581 | EXPORT_SYMBOL(try_to_release_page); | |
1582 | ||
1583 | /** | |
1584 | * block_invalidatepage - invalidate part of all of a buffer-backed page | |
1585 | * | |
1586 | * @page: the page which is affected | |
1587 | * @offset: the index of the truncation point | |
1588 | * | |
1589 | * block_invalidatepage() is called when all or part of the page has become | |
1590 | * invalidatedby a truncate operation. | |
1591 | * | |
1592 | * block_invalidatepage() does not have to release all buffers, but it must | |
1593 | * ensure that no dirty buffer is left outside @offset and that no I/O | |
1594 | * is underway against any of the blocks which are outside the truncation | |
1595 | * point. Because the caller is about to free (and possibly reuse) those | |
1596 | * blocks on-disk. | |
1597 | */ | |
2ff28e22 | 1598 | void block_invalidatepage(struct page *page, unsigned long offset) |
1da177e4 LT |
1599 | { |
1600 | struct buffer_head *head, *bh, *next; | |
1601 | unsigned int curr_off = 0; | |
1da177e4 LT |
1602 | |
1603 | BUG_ON(!PageLocked(page)); | |
1604 | if (!page_has_buffers(page)) | |
1605 | goto out; | |
1606 | ||
1607 | head = page_buffers(page); | |
1608 | bh = head; | |
1609 | do { | |
1610 | unsigned int next_off = curr_off + bh->b_size; | |
1611 | next = bh->b_this_page; | |
1612 | ||
1613 | /* | |
1614 | * is this block fully invalidated? | |
1615 | */ | |
1616 | if (offset <= curr_off) | |
1617 | discard_buffer(bh); | |
1618 | curr_off = next_off; | |
1619 | bh = next; | |
1620 | } while (bh != head); | |
1621 | ||
1622 | /* | |
1623 | * We release buffers only if the entire page is being invalidated. | |
1624 | * The get_block cached value has been unconditionally invalidated, | |
1625 | * so real IO is not possible anymore. | |
1626 | */ | |
1627 | if (offset == 0) | |
2ff28e22 | 1628 | try_to_release_page(page, 0); |
1da177e4 | 1629 | out: |
2ff28e22 | 1630 | return; |
1da177e4 LT |
1631 | } |
1632 | EXPORT_SYMBOL(block_invalidatepage); | |
1633 | ||
2ff28e22 | 1634 | void do_invalidatepage(struct page *page, unsigned long offset) |
aaa4059b | 1635 | { |
2ff28e22 N |
1636 | void (*invalidatepage)(struct page *, unsigned long); |
1637 | invalidatepage = page->mapping->a_ops->invalidatepage ? : | |
1638 | block_invalidatepage; | |
1639 | (*invalidatepage)(page, offset); | |
aaa4059b JK |
1640 | } |
1641 | ||
1da177e4 LT |
1642 | /* |
1643 | * We attach and possibly dirty the buffers atomically wrt | |
1644 | * __set_page_dirty_buffers() via private_lock. try_to_free_buffers | |
1645 | * is already excluded via the page lock. | |
1646 | */ | |
1647 | void create_empty_buffers(struct page *page, | |
1648 | unsigned long blocksize, unsigned long b_state) | |
1649 | { | |
1650 | struct buffer_head *bh, *head, *tail; | |
1651 | ||
1652 | head = alloc_page_buffers(page, blocksize, 1); | |
1653 | bh = head; | |
1654 | do { | |
1655 | bh->b_state |= b_state; | |
1656 | tail = bh; | |
1657 | bh = bh->b_this_page; | |
1658 | } while (bh); | |
1659 | tail->b_this_page = head; | |
1660 | ||
1661 | spin_lock(&page->mapping->private_lock); | |
1662 | if (PageUptodate(page) || PageDirty(page)) { | |
1663 | bh = head; | |
1664 | do { | |
1665 | if (PageDirty(page)) | |
1666 | set_buffer_dirty(bh); | |
1667 | if (PageUptodate(page)) | |
1668 | set_buffer_uptodate(bh); | |
1669 | bh = bh->b_this_page; | |
1670 | } while (bh != head); | |
1671 | } | |
1672 | attach_page_buffers(page, head); | |
1673 | spin_unlock(&page->mapping->private_lock); | |
1674 | } | |
1675 | EXPORT_SYMBOL(create_empty_buffers); | |
1676 | ||
1677 | /* | |
1678 | * We are taking a block for data and we don't want any output from any | |
1679 | * buffer-cache aliases starting from return from that function and | |
1680 | * until the moment when something will explicitly mark the buffer | |
1681 | * dirty (hopefully that will not happen until we will free that block ;-) | |
1682 | * We don't even need to mark it not-uptodate - nobody can expect | |
1683 | * anything from a newly allocated buffer anyway. We used to used | |
1684 | * unmap_buffer() for such invalidation, but that was wrong. We definitely | |
1685 | * don't want to mark the alias unmapped, for example - it would confuse | |
1686 | * anyone who might pick it with bread() afterwards... | |
1687 | * | |
1688 | * Also.. Note that bforget() doesn't lock the buffer. So there can | |
1689 | * be writeout I/O going on against recently-freed buffers. We don't | |
1690 | * wait on that I/O in bforget() - it's more efficient to wait on the I/O | |
1691 | * only if we really need to. That happens here. | |
1692 | */ | |
1693 | void unmap_underlying_metadata(struct block_device *bdev, sector_t block) | |
1694 | { | |
1695 | struct buffer_head *old_bh; | |
1696 | ||
1697 | might_sleep(); | |
1698 | ||
385fd4c5 | 1699 | old_bh = __find_get_block_slow(bdev, block); |
1da177e4 LT |
1700 | if (old_bh) { |
1701 | clear_buffer_dirty(old_bh); | |
1702 | wait_on_buffer(old_bh); | |
1703 | clear_buffer_req(old_bh); | |
1704 | __brelse(old_bh); | |
1705 | } | |
1706 | } | |
1707 | EXPORT_SYMBOL(unmap_underlying_metadata); | |
1708 | ||
1709 | /* | |
1710 | * NOTE! All mapped/uptodate combinations are valid: | |
1711 | * | |
1712 | * Mapped Uptodate Meaning | |
1713 | * | |
1714 | * No No "unknown" - must do get_block() | |
1715 | * No Yes "hole" - zero-filled | |
1716 | * Yes No "allocated" - allocated on disk, not read in | |
1717 | * Yes Yes "valid" - allocated and up-to-date in memory. | |
1718 | * | |
1719 | * "Dirty" is valid only with the last case (mapped+uptodate). | |
1720 | */ | |
1721 | ||
1722 | /* | |
1723 | * While block_write_full_page is writing back the dirty buffers under | |
1724 | * the page lock, whoever dirtied the buffers may decide to clean them | |
1725 | * again at any time. We handle that by only looking at the buffer | |
1726 | * state inside lock_buffer(). | |
1727 | * | |
1728 | * If block_write_full_page() is called for regular writeback | |
1729 | * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a | |
1730 | * locked buffer. This only can happen if someone has written the buffer | |
1731 | * directly, with submit_bh(). At the address_space level PageWriteback | |
1732 | * prevents this contention from occurring. | |
1733 | */ | |
1734 | static int __block_write_full_page(struct inode *inode, struct page *page, | |
1735 | get_block_t *get_block, struct writeback_control *wbc) | |
1736 | { | |
1737 | int err; | |
1738 | sector_t block; | |
1739 | sector_t last_block; | |
f0fbd5fc | 1740 | struct buffer_head *bh, *head; |
b0cf2321 | 1741 | const unsigned blocksize = 1 << inode->i_blkbits; |
1da177e4 LT |
1742 | int nr_underway = 0; |
1743 | ||
1744 | BUG_ON(!PageLocked(page)); | |
1745 | ||
1746 | last_block = (i_size_read(inode) - 1) >> inode->i_blkbits; | |
1747 | ||
1748 | if (!page_has_buffers(page)) { | |
b0cf2321 | 1749 | create_empty_buffers(page, blocksize, |
1da177e4 LT |
1750 | (1 << BH_Dirty)|(1 << BH_Uptodate)); |
1751 | } | |
1752 | ||
1753 | /* | |
1754 | * Be very careful. We have no exclusion from __set_page_dirty_buffers | |
1755 | * here, and the (potentially unmapped) buffers may become dirty at | |
1756 | * any time. If a buffer becomes dirty here after we've inspected it | |
1757 | * then we just miss that fact, and the page stays dirty. | |
1758 | * | |
1759 | * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; | |
1760 | * handle that here by just cleaning them. | |
1761 | */ | |
1762 | ||
54b21a79 | 1763 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
1764 | head = page_buffers(page); |
1765 | bh = head; | |
1766 | ||
1767 | /* | |
1768 | * Get all the dirty buffers mapped to disk addresses and | |
1769 | * handle any aliases from the underlying blockdev's mapping. | |
1770 | */ | |
1771 | do { | |
1772 | if (block > last_block) { | |
1773 | /* | |
1774 | * mapped buffers outside i_size will occur, because | |
1775 | * this page can be outside i_size when there is a | |
1776 | * truncate in progress. | |
1777 | */ | |
1778 | /* | |
1779 | * The buffer was zeroed by block_write_full_page() | |
1780 | */ | |
1781 | clear_buffer_dirty(bh); | |
1782 | set_buffer_uptodate(bh); | |
1783 | } else if (!buffer_mapped(bh) && buffer_dirty(bh)) { | |
b0cf2321 | 1784 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1785 | err = get_block(inode, block, bh, 1); |
1786 | if (err) | |
1787 | goto recover; | |
1788 | if (buffer_new(bh)) { | |
1789 | /* blockdev mappings never come here */ | |
1790 | clear_buffer_new(bh); | |
1791 | unmap_underlying_metadata(bh->b_bdev, | |
1792 | bh->b_blocknr); | |
1793 | } | |
1794 | } | |
1795 | bh = bh->b_this_page; | |
1796 | block++; | |
1797 | } while (bh != head); | |
1798 | ||
1799 | do { | |
1da177e4 LT |
1800 | if (!buffer_mapped(bh)) |
1801 | continue; | |
1802 | /* | |
1803 | * If it's a fully non-blocking write attempt and we cannot | |
1804 | * lock the buffer then redirty the page. Note that this can | |
1805 | * potentially cause a busy-wait loop from pdflush and kswapd | |
1806 | * activity, but those code paths have their own higher-level | |
1807 | * throttling. | |
1808 | */ | |
1809 | if (wbc->sync_mode != WB_SYNC_NONE || !wbc->nonblocking) { | |
1810 | lock_buffer(bh); | |
1811 | } else if (test_set_buffer_locked(bh)) { | |
1812 | redirty_page_for_writepage(wbc, page); | |
1813 | continue; | |
1814 | } | |
1815 | if (test_clear_buffer_dirty(bh)) { | |
1816 | mark_buffer_async_write(bh); | |
1817 | } else { | |
1818 | unlock_buffer(bh); | |
1819 | } | |
1820 | } while ((bh = bh->b_this_page) != head); | |
1821 | ||
1822 | /* | |
1823 | * The page and its buffers are protected by PageWriteback(), so we can | |
1824 | * drop the bh refcounts early. | |
1825 | */ | |
1826 | BUG_ON(PageWriteback(page)); | |
1827 | set_page_writeback(page); | |
1da177e4 LT |
1828 | |
1829 | do { | |
1830 | struct buffer_head *next = bh->b_this_page; | |
1831 | if (buffer_async_write(bh)) { | |
1832 | submit_bh(WRITE, bh); | |
1833 | nr_underway++; | |
1834 | } | |
1da177e4 LT |
1835 | bh = next; |
1836 | } while (bh != head); | |
05937baa | 1837 | unlock_page(page); |
1da177e4 LT |
1838 | |
1839 | err = 0; | |
1840 | done: | |
1841 | if (nr_underway == 0) { | |
1842 | /* | |
1843 | * The page was marked dirty, but the buffers were | |
1844 | * clean. Someone wrote them back by hand with | |
1845 | * ll_rw_block/submit_bh. A rare case. | |
1846 | */ | |
1847 | int uptodate = 1; | |
1848 | do { | |
1849 | if (!buffer_uptodate(bh)) { | |
1850 | uptodate = 0; | |
1851 | break; | |
1852 | } | |
1853 | bh = bh->b_this_page; | |
1854 | } while (bh != head); | |
1855 | if (uptodate) | |
1856 | SetPageUptodate(page); | |
1857 | end_page_writeback(page); | |
1858 | /* | |
1859 | * The page and buffer_heads can be released at any time from | |
1860 | * here on. | |
1861 | */ | |
1862 | wbc->pages_skipped++; /* We didn't write this page */ | |
1863 | } | |
1864 | return err; | |
1865 | ||
1866 | recover: | |
1867 | /* | |
1868 | * ENOSPC, or some other error. We may already have added some | |
1869 | * blocks to the file, so we need to write these out to avoid | |
1870 | * exposing stale data. | |
1871 | * The page is currently locked and not marked for writeback | |
1872 | */ | |
1873 | bh = head; | |
1874 | /* Recovery: lock and submit the mapped buffers */ | |
1875 | do { | |
1da177e4 LT |
1876 | if (buffer_mapped(bh) && buffer_dirty(bh)) { |
1877 | lock_buffer(bh); | |
1878 | mark_buffer_async_write(bh); | |
1879 | } else { | |
1880 | /* | |
1881 | * The buffer may have been set dirty during | |
1882 | * attachment to a dirty page. | |
1883 | */ | |
1884 | clear_buffer_dirty(bh); | |
1885 | } | |
1886 | } while ((bh = bh->b_this_page) != head); | |
1887 | SetPageError(page); | |
1888 | BUG_ON(PageWriteback(page)); | |
1889 | set_page_writeback(page); | |
1890 | unlock_page(page); | |
1891 | do { | |
1892 | struct buffer_head *next = bh->b_this_page; | |
1893 | if (buffer_async_write(bh)) { | |
1894 | clear_buffer_dirty(bh); | |
1895 | submit_bh(WRITE, bh); | |
1896 | nr_underway++; | |
1897 | } | |
1da177e4 LT |
1898 | bh = next; |
1899 | } while (bh != head); | |
1900 | goto done; | |
1901 | } | |
1902 | ||
1903 | static int __block_prepare_write(struct inode *inode, struct page *page, | |
1904 | unsigned from, unsigned to, get_block_t *get_block) | |
1905 | { | |
1906 | unsigned block_start, block_end; | |
1907 | sector_t block; | |
1908 | int err = 0; | |
1909 | unsigned blocksize, bbits; | |
1910 | struct buffer_head *bh, *head, *wait[2], **wait_bh=wait; | |
1911 | ||
1912 | BUG_ON(!PageLocked(page)); | |
1913 | BUG_ON(from > PAGE_CACHE_SIZE); | |
1914 | BUG_ON(to > PAGE_CACHE_SIZE); | |
1915 | BUG_ON(from > to); | |
1916 | ||
1917 | blocksize = 1 << inode->i_blkbits; | |
1918 | if (!page_has_buffers(page)) | |
1919 | create_empty_buffers(page, blocksize, 0); | |
1920 | head = page_buffers(page); | |
1921 | ||
1922 | bbits = inode->i_blkbits; | |
1923 | block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits); | |
1924 | ||
1925 | for(bh = head, block_start = 0; bh != head || !block_start; | |
1926 | block++, 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 (PageUptodate(page)) { | |
1930 | if (!buffer_uptodate(bh)) | |
1931 | set_buffer_uptodate(bh); | |
1932 | } | |
1933 | continue; | |
1934 | } | |
1935 | if (buffer_new(bh)) | |
1936 | clear_buffer_new(bh); | |
1937 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 1938 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
1939 | err = get_block(inode, block, bh, 1); |
1940 | if (err) | |
f3ddbdc6 | 1941 | break; |
1da177e4 | 1942 | if (buffer_new(bh)) { |
1da177e4 LT |
1943 | unmap_underlying_metadata(bh->b_bdev, |
1944 | bh->b_blocknr); | |
1945 | if (PageUptodate(page)) { | |
1946 | set_buffer_uptodate(bh); | |
1947 | continue; | |
1948 | } | |
1949 | if (block_end > to || block_start < from) { | |
1950 | void *kaddr; | |
1951 | ||
1952 | kaddr = kmap_atomic(page, KM_USER0); | |
1953 | if (block_end > to) | |
1954 | memset(kaddr+to, 0, | |
1955 | block_end-to); | |
1956 | if (block_start < from) | |
1957 | memset(kaddr+block_start, | |
1958 | 0, from-block_start); | |
1959 | flush_dcache_page(page); | |
1960 | kunmap_atomic(kaddr, KM_USER0); | |
1961 | } | |
1962 | continue; | |
1963 | } | |
1964 | } | |
1965 | if (PageUptodate(page)) { | |
1966 | if (!buffer_uptodate(bh)) | |
1967 | set_buffer_uptodate(bh); | |
1968 | continue; | |
1969 | } | |
1970 | if (!buffer_uptodate(bh) && !buffer_delay(bh) && | |
1971 | (block_start < from || block_end > to)) { | |
1972 | ll_rw_block(READ, 1, &bh); | |
1973 | *wait_bh++=bh; | |
1974 | } | |
1975 | } | |
1976 | /* | |
1977 | * If we issued read requests - let them complete. | |
1978 | */ | |
1979 | while(wait_bh > wait) { | |
1980 | wait_on_buffer(*--wait_bh); | |
1981 | if (!buffer_uptodate(*wait_bh)) | |
f3ddbdc6 | 1982 | err = -EIO; |
1da177e4 | 1983 | } |
152becd2 AA |
1984 | if (!err) { |
1985 | bh = head; | |
1986 | do { | |
1987 | if (buffer_new(bh)) | |
1988 | clear_buffer_new(bh); | |
1989 | } while ((bh = bh->b_this_page) != head); | |
1990 | return 0; | |
1991 | } | |
f3ddbdc6 | 1992 | /* Error case: */ |
1da177e4 LT |
1993 | /* |
1994 | * Zero out any newly allocated blocks to avoid exposing stale | |
1995 | * data. If BH_New is set, we know that the block was newly | |
1996 | * allocated in the above loop. | |
1997 | */ | |
1998 | bh = head; | |
1999 | block_start = 0; | |
2000 | do { | |
2001 | block_end = block_start+blocksize; | |
2002 | if (block_end <= from) | |
2003 | goto next_bh; | |
2004 | if (block_start >= to) | |
2005 | break; | |
2006 | if (buffer_new(bh)) { | |
2007 | void *kaddr; | |
2008 | ||
2009 | clear_buffer_new(bh); | |
2010 | kaddr = kmap_atomic(page, KM_USER0); | |
2011 | memset(kaddr+block_start, 0, bh->b_size); | |
2012 | kunmap_atomic(kaddr, KM_USER0); | |
2013 | set_buffer_uptodate(bh); | |
2014 | mark_buffer_dirty(bh); | |
2015 | } | |
2016 | next_bh: | |
2017 | block_start = block_end; | |
2018 | bh = bh->b_this_page; | |
2019 | } while (bh != head); | |
2020 | return err; | |
2021 | } | |
2022 | ||
2023 | static int __block_commit_write(struct inode *inode, struct page *page, | |
2024 | unsigned from, unsigned to) | |
2025 | { | |
2026 | unsigned block_start, block_end; | |
2027 | int partial = 0; | |
2028 | unsigned blocksize; | |
2029 | struct buffer_head *bh, *head; | |
2030 | ||
2031 | blocksize = 1 << inode->i_blkbits; | |
2032 | ||
2033 | for(bh = head = page_buffers(page), block_start = 0; | |
2034 | bh != head || !block_start; | |
2035 | block_start=block_end, bh = bh->b_this_page) { | |
2036 | block_end = block_start + blocksize; | |
2037 | if (block_end <= from || block_start >= to) { | |
2038 | if (!buffer_uptodate(bh)) | |
2039 | partial = 1; | |
2040 | } else { | |
2041 | set_buffer_uptodate(bh); | |
2042 | mark_buffer_dirty(bh); | |
2043 | } | |
2044 | } | |
2045 | ||
2046 | /* | |
2047 | * If this is a partial write which happened to make all buffers | |
2048 | * uptodate then we can optimize away a bogus readpage() for | |
2049 | * the next read(). Here we 'discover' whether the page went | |
2050 | * uptodate as a result of this (potentially partial) write. | |
2051 | */ | |
2052 | if (!partial) | |
2053 | SetPageUptodate(page); | |
2054 | return 0; | |
2055 | } | |
2056 | ||
2057 | /* | |
2058 | * Generic "read page" function for block devices that have the normal | |
2059 | * get_block functionality. This is most of the block device filesystems. | |
2060 | * Reads the page asynchronously --- the unlock_buffer() and | |
2061 | * set/clear_buffer_uptodate() functions propagate buffer state into the | |
2062 | * page struct once IO has completed. | |
2063 | */ | |
2064 | int block_read_full_page(struct page *page, get_block_t *get_block) | |
2065 | { | |
2066 | struct inode *inode = page->mapping->host; | |
2067 | sector_t iblock, lblock; | |
2068 | struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; | |
2069 | unsigned int blocksize; | |
2070 | int nr, i; | |
2071 | int fully_mapped = 1; | |
2072 | ||
cd7619d6 | 2073 | BUG_ON(!PageLocked(page)); |
1da177e4 LT |
2074 | blocksize = 1 << inode->i_blkbits; |
2075 | if (!page_has_buffers(page)) | |
2076 | create_empty_buffers(page, blocksize, 0); | |
2077 | head = page_buffers(page); | |
2078 | ||
2079 | iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits); | |
2080 | lblock = (i_size_read(inode)+blocksize-1) >> inode->i_blkbits; | |
2081 | bh = head; | |
2082 | nr = 0; | |
2083 | i = 0; | |
2084 | ||
2085 | do { | |
2086 | if (buffer_uptodate(bh)) | |
2087 | continue; | |
2088 | ||
2089 | if (!buffer_mapped(bh)) { | |
c64610ba AM |
2090 | int err = 0; |
2091 | ||
1da177e4 LT |
2092 | fully_mapped = 0; |
2093 | if (iblock < lblock) { | |
b0cf2321 | 2094 | WARN_ON(bh->b_size != blocksize); |
c64610ba AM |
2095 | err = get_block(inode, iblock, bh, 0); |
2096 | if (err) | |
1da177e4 LT |
2097 | SetPageError(page); |
2098 | } | |
2099 | if (!buffer_mapped(bh)) { | |
2100 | void *kaddr = kmap_atomic(page, KM_USER0); | |
2101 | memset(kaddr + i * blocksize, 0, blocksize); | |
2102 | flush_dcache_page(page); | |
2103 | kunmap_atomic(kaddr, KM_USER0); | |
c64610ba AM |
2104 | if (!err) |
2105 | set_buffer_uptodate(bh); | |
1da177e4 LT |
2106 | continue; |
2107 | } | |
2108 | /* | |
2109 | * get_block() might have updated the buffer | |
2110 | * synchronously | |
2111 | */ | |
2112 | if (buffer_uptodate(bh)) | |
2113 | continue; | |
2114 | } | |
2115 | arr[nr++] = bh; | |
2116 | } while (i++, iblock++, (bh = bh->b_this_page) != head); | |
2117 | ||
2118 | if (fully_mapped) | |
2119 | SetPageMappedToDisk(page); | |
2120 | ||
2121 | if (!nr) { | |
2122 | /* | |
2123 | * All buffers are uptodate - we can set the page uptodate | |
2124 | * as well. But not if get_block() returned an error. | |
2125 | */ | |
2126 | if (!PageError(page)) | |
2127 | SetPageUptodate(page); | |
2128 | unlock_page(page); | |
2129 | return 0; | |
2130 | } | |
2131 | ||
2132 | /* Stage two: lock the buffers */ | |
2133 | for (i = 0; i < nr; i++) { | |
2134 | bh = arr[i]; | |
2135 | lock_buffer(bh); | |
2136 | mark_buffer_async_read(bh); | |
2137 | } | |
2138 | ||
2139 | /* | |
2140 | * Stage 3: start the IO. Check for uptodateness | |
2141 | * inside the buffer lock in case another process reading | |
2142 | * the underlying blockdev brought it uptodate (the sct fix). | |
2143 | */ | |
2144 | for (i = 0; i < nr; i++) { | |
2145 | bh = arr[i]; | |
2146 | if (buffer_uptodate(bh)) | |
2147 | end_buffer_async_read(bh, 1); | |
2148 | else | |
2149 | submit_bh(READ, bh); | |
2150 | } | |
2151 | return 0; | |
2152 | } | |
2153 | ||
2154 | /* utility function for filesystems that need to do work on expanding | |
2155 | * truncates. Uses prepare/commit_write to allow the filesystem to | |
2156 | * deal with the hole. | |
2157 | */ | |
05eb0b51 OH |
2158 | static int __generic_cont_expand(struct inode *inode, loff_t size, |
2159 | pgoff_t index, unsigned int offset) | |
1da177e4 LT |
2160 | { |
2161 | struct address_space *mapping = inode->i_mapping; | |
2162 | struct page *page; | |
05eb0b51 | 2163 | unsigned long limit; |
1da177e4 LT |
2164 | int err; |
2165 | ||
2166 | err = -EFBIG; | |
2167 | limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; | |
2168 | if (limit != RLIM_INFINITY && size > (loff_t)limit) { | |
2169 | send_sig(SIGXFSZ, current, 0); | |
2170 | goto out; | |
2171 | } | |
2172 | if (size > inode->i_sb->s_maxbytes) | |
2173 | goto out; | |
2174 | ||
1da177e4 LT |
2175 | err = -ENOMEM; |
2176 | page = grab_cache_page(mapping, index); | |
2177 | if (!page) | |
2178 | goto out; | |
2179 | err = mapping->a_ops->prepare_write(NULL, page, offset, offset); | |
05eb0b51 OH |
2180 | if (err) { |
2181 | /* | |
2182 | * ->prepare_write() may have instantiated a few blocks | |
2183 | * outside i_size. Trim these off again. | |
2184 | */ | |
2185 | unlock_page(page); | |
2186 | page_cache_release(page); | |
2187 | vmtruncate(inode, inode->i_size); | |
2188 | goto out; | |
1da177e4 | 2189 | } |
05eb0b51 OH |
2190 | |
2191 | err = mapping->a_ops->commit_write(NULL, page, offset, offset); | |
2192 | ||
1da177e4 LT |
2193 | unlock_page(page); |
2194 | page_cache_release(page); | |
2195 | if (err > 0) | |
2196 | err = 0; | |
2197 | out: | |
2198 | return err; | |
2199 | } | |
2200 | ||
05eb0b51 OH |
2201 | int generic_cont_expand(struct inode *inode, loff_t size) |
2202 | { | |
2203 | pgoff_t index; | |
2204 | unsigned int offset; | |
2205 | ||
2206 | offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */ | |
2207 | ||
2208 | /* ugh. in prepare/commit_write, if from==to==start of block, we | |
2209 | ** skip the prepare. make sure we never send an offset for the start | |
2210 | ** of a block | |
2211 | */ | |
2212 | if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) { | |
2213 | /* caller must handle this extra byte. */ | |
2214 | offset++; | |
2215 | } | |
2216 | index = size >> PAGE_CACHE_SHIFT; | |
2217 | ||
2218 | return __generic_cont_expand(inode, size, index, offset); | |
2219 | } | |
2220 | ||
2221 | int generic_cont_expand_simple(struct inode *inode, loff_t size) | |
2222 | { | |
2223 | loff_t pos = size - 1; | |
2224 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
2225 | unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1; | |
2226 | ||
2227 | /* prepare/commit_write can handle even if from==to==start of block. */ | |
2228 | return __generic_cont_expand(inode, size, index, offset); | |
2229 | } | |
2230 | ||
1da177e4 LT |
2231 | /* |
2232 | * For moronic filesystems that do not allow holes in file. | |
2233 | * We may have to extend the file. | |
2234 | */ | |
2235 | ||
2236 | int cont_prepare_write(struct page *page, unsigned offset, | |
2237 | unsigned to, get_block_t *get_block, loff_t *bytes) | |
2238 | { | |
2239 | struct address_space *mapping = page->mapping; | |
2240 | struct inode *inode = mapping->host; | |
2241 | struct page *new_page; | |
2242 | pgoff_t pgpos; | |
2243 | long status; | |
2244 | unsigned zerofrom; | |
2245 | unsigned blocksize = 1 << inode->i_blkbits; | |
2246 | void *kaddr; | |
2247 | ||
2248 | while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) { | |
2249 | status = -ENOMEM; | |
2250 | new_page = grab_cache_page(mapping, pgpos); | |
2251 | if (!new_page) | |
2252 | goto out; | |
2253 | /* we might sleep */ | |
2254 | if (*bytes>>PAGE_CACHE_SHIFT != pgpos) { | |
2255 | unlock_page(new_page); | |
2256 | page_cache_release(new_page); | |
2257 | continue; | |
2258 | } | |
2259 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2260 | if (zerofrom & (blocksize-1)) { | |
2261 | *bytes |= (blocksize-1); | |
2262 | (*bytes)++; | |
2263 | } | |
2264 | status = __block_prepare_write(inode, new_page, zerofrom, | |
2265 | PAGE_CACHE_SIZE, get_block); | |
2266 | if (status) | |
2267 | goto out_unmap; | |
2268 | kaddr = kmap_atomic(new_page, KM_USER0); | |
2269 | memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom); | |
2270 | flush_dcache_page(new_page); | |
2271 | kunmap_atomic(kaddr, KM_USER0); | |
2272 | generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE); | |
2273 | unlock_page(new_page); | |
2274 | page_cache_release(new_page); | |
2275 | } | |
2276 | ||
2277 | if (page->index < pgpos) { | |
2278 | /* completely inside the area */ | |
2279 | zerofrom = offset; | |
2280 | } else { | |
2281 | /* page covers the boundary, find the boundary offset */ | |
2282 | zerofrom = *bytes & ~PAGE_CACHE_MASK; | |
2283 | ||
2284 | /* if we will expand the thing last block will be filled */ | |
2285 | if (to > zerofrom && (zerofrom & (blocksize-1))) { | |
2286 | *bytes |= (blocksize-1); | |
2287 | (*bytes)++; | |
2288 | } | |
2289 | ||
2290 | /* starting below the boundary? Nothing to zero out */ | |
2291 | if (offset <= zerofrom) | |
2292 | zerofrom = offset; | |
2293 | } | |
2294 | status = __block_prepare_write(inode, page, zerofrom, to, get_block); | |
2295 | if (status) | |
2296 | goto out1; | |
2297 | if (zerofrom < offset) { | |
2298 | kaddr = kmap_atomic(page, KM_USER0); | |
2299 | memset(kaddr+zerofrom, 0, offset-zerofrom); | |
2300 | flush_dcache_page(page); | |
2301 | kunmap_atomic(kaddr, KM_USER0); | |
2302 | __block_commit_write(inode, page, zerofrom, offset); | |
2303 | } | |
2304 | return 0; | |
2305 | out1: | |
2306 | ClearPageUptodate(page); | |
2307 | return status; | |
2308 | ||
2309 | out_unmap: | |
2310 | ClearPageUptodate(new_page); | |
2311 | unlock_page(new_page); | |
2312 | page_cache_release(new_page); | |
2313 | out: | |
2314 | return status; | |
2315 | } | |
2316 | ||
2317 | int block_prepare_write(struct page *page, unsigned from, unsigned to, | |
2318 | get_block_t *get_block) | |
2319 | { | |
2320 | struct inode *inode = page->mapping->host; | |
2321 | int err = __block_prepare_write(inode, page, from, to, get_block); | |
2322 | if (err) | |
2323 | ClearPageUptodate(page); | |
2324 | return err; | |
2325 | } | |
2326 | ||
2327 | int block_commit_write(struct page *page, unsigned from, unsigned to) | |
2328 | { | |
2329 | struct inode *inode = page->mapping->host; | |
2330 | __block_commit_write(inode,page,from,to); | |
2331 | return 0; | |
2332 | } | |
2333 | ||
2334 | int generic_commit_write(struct file *file, struct page *page, | |
2335 | unsigned from, unsigned to) | |
2336 | { | |
2337 | struct inode *inode = page->mapping->host; | |
2338 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2339 | __block_commit_write(inode,page,from,to); | |
2340 | /* | |
2341 | * No need to use i_size_read() here, the i_size | |
1b1dcc1b | 2342 | * cannot change under us because we hold i_mutex. |
1da177e4 LT |
2343 | */ |
2344 | if (pos > inode->i_size) { | |
2345 | i_size_write(inode, pos); | |
2346 | mark_inode_dirty(inode); | |
2347 | } | |
2348 | return 0; | |
2349 | } | |
2350 | ||
2351 | ||
2352 | /* | |
2353 | * nobh_prepare_write()'s prereads are special: the buffer_heads are freed | |
2354 | * immediately, while under the page lock. So it needs a special end_io | |
2355 | * handler which does not touch the bh after unlocking it. | |
2356 | * | |
2357 | * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but | |
2358 | * a race there is benign: unlock_buffer() only use the bh's address for | |
2359 | * hashing after unlocking the buffer, so it doesn't actually touch the bh | |
2360 | * itself. | |
2361 | */ | |
2362 | static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate) | |
2363 | { | |
2364 | if (uptodate) { | |
2365 | set_buffer_uptodate(bh); | |
2366 | } else { | |
2367 | /* This happens, due to failed READA attempts. */ | |
2368 | clear_buffer_uptodate(bh); | |
2369 | } | |
2370 | unlock_buffer(bh); | |
2371 | } | |
2372 | ||
2373 | /* | |
2374 | * On entry, the page is fully not uptodate. | |
2375 | * On exit the page is fully uptodate in the areas outside (from,to) | |
2376 | */ | |
2377 | int nobh_prepare_write(struct page *page, unsigned from, unsigned to, | |
2378 | get_block_t *get_block) | |
2379 | { | |
2380 | struct inode *inode = page->mapping->host; | |
2381 | const unsigned blkbits = inode->i_blkbits; | |
2382 | const unsigned blocksize = 1 << blkbits; | |
2383 | struct buffer_head map_bh; | |
2384 | struct buffer_head *read_bh[MAX_BUF_PER_PAGE]; | |
2385 | unsigned block_in_page; | |
2386 | unsigned block_start; | |
2387 | sector_t block_in_file; | |
2388 | char *kaddr; | |
2389 | int nr_reads = 0; | |
2390 | int i; | |
2391 | int ret = 0; | |
2392 | int is_mapped_to_disk = 1; | |
2393 | int dirtied_it = 0; | |
2394 | ||
2395 | if (PageMappedToDisk(page)) | |
2396 | return 0; | |
2397 | ||
2398 | block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits); | |
2399 | map_bh.b_page = page; | |
2400 | ||
2401 | /* | |
2402 | * We loop across all blocks in the page, whether or not they are | |
2403 | * part of the affected region. This is so we can discover if the | |
2404 | * page is fully mapped-to-disk. | |
2405 | */ | |
2406 | for (block_start = 0, block_in_page = 0; | |
2407 | block_start < PAGE_CACHE_SIZE; | |
2408 | block_in_page++, block_start += blocksize) { | |
2409 | unsigned block_end = block_start + blocksize; | |
2410 | int create; | |
2411 | ||
2412 | map_bh.b_state = 0; | |
2413 | create = 1; | |
2414 | if (block_start >= to) | |
2415 | create = 0; | |
b0cf2321 | 2416 | map_bh.b_size = blocksize; |
1da177e4 LT |
2417 | ret = get_block(inode, block_in_file + block_in_page, |
2418 | &map_bh, create); | |
2419 | if (ret) | |
2420 | goto failed; | |
2421 | if (!buffer_mapped(&map_bh)) | |
2422 | is_mapped_to_disk = 0; | |
2423 | if (buffer_new(&map_bh)) | |
2424 | unmap_underlying_metadata(map_bh.b_bdev, | |
2425 | map_bh.b_blocknr); | |
2426 | if (PageUptodate(page)) | |
2427 | continue; | |
2428 | if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) { | |
2429 | kaddr = kmap_atomic(page, KM_USER0); | |
2430 | if (block_start < from) { | |
2431 | memset(kaddr+block_start, 0, from-block_start); | |
2432 | dirtied_it = 1; | |
2433 | } | |
2434 | if (block_end > to) { | |
2435 | memset(kaddr + to, 0, block_end - to); | |
2436 | dirtied_it = 1; | |
2437 | } | |
2438 | flush_dcache_page(page); | |
2439 | kunmap_atomic(kaddr, KM_USER0); | |
2440 | continue; | |
2441 | } | |
2442 | if (buffer_uptodate(&map_bh)) | |
2443 | continue; /* reiserfs does this */ | |
2444 | if (block_start < from || block_end > to) { | |
2445 | struct buffer_head *bh = alloc_buffer_head(GFP_NOFS); | |
2446 | ||
2447 | if (!bh) { | |
2448 | ret = -ENOMEM; | |
2449 | goto failed; | |
2450 | } | |
2451 | bh->b_state = map_bh.b_state; | |
2452 | atomic_set(&bh->b_count, 0); | |
2453 | bh->b_this_page = NULL; | |
2454 | bh->b_page = page; | |
2455 | bh->b_blocknr = map_bh.b_blocknr; | |
2456 | bh->b_size = blocksize; | |
2457 | bh->b_data = (char *)(long)block_start; | |
2458 | bh->b_bdev = map_bh.b_bdev; | |
2459 | bh->b_private = NULL; | |
2460 | read_bh[nr_reads++] = bh; | |
2461 | } | |
2462 | } | |
2463 | ||
2464 | if (nr_reads) { | |
2465 | struct buffer_head *bh; | |
2466 | ||
2467 | /* | |
2468 | * The page is locked, so these buffers are protected from | |
2469 | * any VM or truncate activity. Hence we don't need to care | |
2470 | * for the buffer_head refcounts. | |
2471 | */ | |
2472 | for (i = 0; i < nr_reads; i++) { | |
2473 | bh = read_bh[i]; | |
2474 | lock_buffer(bh); | |
2475 | bh->b_end_io = end_buffer_read_nobh; | |
2476 | submit_bh(READ, bh); | |
2477 | } | |
2478 | for (i = 0; i < nr_reads; i++) { | |
2479 | bh = read_bh[i]; | |
2480 | wait_on_buffer(bh); | |
2481 | if (!buffer_uptodate(bh)) | |
2482 | ret = -EIO; | |
2483 | free_buffer_head(bh); | |
2484 | read_bh[i] = NULL; | |
2485 | } | |
2486 | if (ret) | |
2487 | goto failed; | |
2488 | } | |
2489 | ||
2490 | if (is_mapped_to_disk) | |
2491 | SetPageMappedToDisk(page); | |
2492 | SetPageUptodate(page); | |
2493 | ||
2494 | /* | |
2495 | * Setting the page dirty here isn't necessary for the prepare_write | |
2496 | * function - commit_write will do that. But if/when this function is | |
2497 | * used within the pagefault handler to ensure that all mmapped pages | |
2498 | * have backing space in the filesystem, we will need to dirty the page | |
2499 | * if its contents were altered. | |
2500 | */ | |
2501 | if (dirtied_it) | |
2502 | set_page_dirty(page); | |
2503 | ||
2504 | return 0; | |
2505 | ||
2506 | failed: | |
2507 | for (i = 0; i < nr_reads; i++) { | |
2508 | if (read_bh[i]) | |
2509 | free_buffer_head(read_bh[i]); | |
2510 | } | |
2511 | ||
2512 | /* | |
2513 | * Error recovery is pretty slack. Clear the page and mark it dirty | |
2514 | * so we'll later zero out any blocks which _were_ allocated. | |
2515 | */ | |
2516 | kaddr = kmap_atomic(page, KM_USER0); | |
2517 | memset(kaddr, 0, PAGE_CACHE_SIZE); | |
2518 | kunmap_atomic(kaddr, KM_USER0); | |
2519 | SetPageUptodate(page); | |
2520 | set_page_dirty(page); | |
2521 | return ret; | |
2522 | } | |
2523 | EXPORT_SYMBOL(nobh_prepare_write); | |
2524 | ||
2525 | int nobh_commit_write(struct file *file, struct page *page, | |
2526 | unsigned from, unsigned to) | |
2527 | { | |
2528 | struct inode *inode = page->mapping->host; | |
2529 | loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; | |
2530 | ||
2531 | set_page_dirty(page); | |
2532 | if (pos > inode->i_size) { | |
2533 | i_size_write(inode, pos); | |
2534 | mark_inode_dirty(inode); | |
2535 | } | |
2536 | return 0; | |
2537 | } | |
2538 | EXPORT_SYMBOL(nobh_commit_write); | |
2539 | ||
2540 | /* | |
2541 | * nobh_writepage() - based on block_full_write_page() except | |
2542 | * that it tries to operate without attaching bufferheads to | |
2543 | * the page. | |
2544 | */ | |
2545 | int nobh_writepage(struct page *page, get_block_t *get_block, | |
2546 | struct writeback_control *wbc) | |
2547 | { | |
2548 | struct inode * const inode = page->mapping->host; | |
2549 | loff_t i_size = i_size_read(inode); | |
2550 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2551 | unsigned offset; | |
2552 | void *kaddr; | |
2553 | int ret; | |
2554 | ||
2555 | /* Is the page fully inside i_size? */ | |
2556 | if (page->index < end_index) | |
2557 | goto out; | |
2558 | ||
2559 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2560 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2561 | if (page->index >= end_index+1 || !offset) { | |
2562 | /* | |
2563 | * The page may have dirty, unmapped buffers. For example, | |
2564 | * they may have been added in ext3_writepage(). Make them | |
2565 | * freeable here, so the page does not leak. | |
2566 | */ | |
2567 | #if 0 | |
2568 | /* Not really sure about this - do we need this ? */ | |
2569 | if (page->mapping->a_ops->invalidatepage) | |
2570 | page->mapping->a_ops->invalidatepage(page, offset); | |
2571 | #endif | |
2572 | unlock_page(page); | |
2573 | return 0; /* don't care */ | |
2574 | } | |
2575 | ||
2576 | /* | |
2577 | * The page straddles i_size. It must be zeroed out on each and every | |
2578 | * writepage invocation because it may be mmapped. "A file is mapped | |
2579 | * in multiples of the page size. For a file that is not a multiple of | |
2580 | * the page size, the remaining memory is zeroed when mapped, and | |
2581 | * writes to that region are not written out to the file." | |
2582 | */ | |
2583 | kaddr = kmap_atomic(page, KM_USER0); | |
2584 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2585 | flush_dcache_page(page); | |
2586 | kunmap_atomic(kaddr, KM_USER0); | |
2587 | out: | |
2588 | ret = mpage_writepage(page, get_block, wbc); | |
2589 | if (ret == -EAGAIN) | |
2590 | ret = __block_write_full_page(inode, page, get_block, wbc); | |
2591 | return ret; | |
2592 | } | |
2593 | EXPORT_SYMBOL(nobh_writepage); | |
2594 | ||
2595 | /* | |
2596 | * This function assumes that ->prepare_write() uses nobh_prepare_write(). | |
2597 | */ | |
2598 | int nobh_truncate_page(struct address_space *mapping, loff_t from) | |
2599 | { | |
2600 | struct inode *inode = mapping->host; | |
2601 | unsigned blocksize = 1 << inode->i_blkbits; | |
2602 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2603 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2604 | unsigned to; | |
2605 | struct page *page; | |
2606 | struct address_space_operations *a_ops = mapping->a_ops; | |
2607 | char *kaddr; | |
2608 | int ret = 0; | |
2609 | ||
2610 | if ((offset & (blocksize - 1)) == 0) | |
2611 | goto out; | |
2612 | ||
2613 | ret = -ENOMEM; | |
2614 | page = grab_cache_page(mapping, index); | |
2615 | if (!page) | |
2616 | goto out; | |
2617 | ||
2618 | to = (offset + blocksize) & ~(blocksize - 1); | |
2619 | ret = a_ops->prepare_write(NULL, page, offset, to); | |
2620 | if (ret == 0) { | |
2621 | kaddr = kmap_atomic(page, KM_USER0); | |
2622 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2623 | flush_dcache_page(page); | |
2624 | kunmap_atomic(kaddr, KM_USER0); | |
2625 | set_page_dirty(page); | |
2626 | } | |
2627 | unlock_page(page); | |
2628 | page_cache_release(page); | |
2629 | out: | |
2630 | return ret; | |
2631 | } | |
2632 | EXPORT_SYMBOL(nobh_truncate_page); | |
2633 | ||
2634 | int block_truncate_page(struct address_space *mapping, | |
2635 | loff_t from, get_block_t *get_block) | |
2636 | { | |
2637 | pgoff_t index = from >> PAGE_CACHE_SHIFT; | |
2638 | unsigned offset = from & (PAGE_CACHE_SIZE-1); | |
2639 | unsigned blocksize; | |
54b21a79 | 2640 | sector_t iblock; |
1da177e4 LT |
2641 | unsigned length, pos; |
2642 | struct inode *inode = mapping->host; | |
2643 | struct page *page; | |
2644 | struct buffer_head *bh; | |
2645 | void *kaddr; | |
2646 | int err; | |
2647 | ||
2648 | blocksize = 1 << inode->i_blkbits; | |
2649 | length = offset & (blocksize - 1); | |
2650 | ||
2651 | /* Block boundary? Nothing to do */ | |
2652 | if (!length) | |
2653 | return 0; | |
2654 | ||
2655 | length = blocksize - length; | |
54b21a79 | 2656 | iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits); |
1da177e4 LT |
2657 | |
2658 | page = grab_cache_page(mapping, index); | |
2659 | err = -ENOMEM; | |
2660 | if (!page) | |
2661 | goto out; | |
2662 | ||
2663 | if (!page_has_buffers(page)) | |
2664 | create_empty_buffers(page, blocksize, 0); | |
2665 | ||
2666 | /* Find the buffer that contains "offset" */ | |
2667 | bh = page_buffers(page); | |
2668 | pos = blocksize; | |
2669 | while (offset >= pos) { | |
2670 | bh = bh->b_this_page; | |
2671 | iblock++; | |
2672 | pos += blocksize; | |
2673 | } | |
2674 | ||
2675 | err = 0; | |
2676 | if (!buffer_mapped(bh)) { | |
b0cf2321 | 2677 | WARN_ON(bh->b_size != blocksize); |
1da177e4 LT |
2678 | err = get_block(inode, iblock, bh, 0); |
2679 | if (err) | |
2680 | goto unlock; | |
2681 | /* unmapped? It's a hole - nothing to do */ | |
2682 | if (!buffer_mapped(bh)) | |
2683 | goto unlock; | |
2684 | } | |
2685 | ||
2686 | /* Ok, it's mapped. Make sure it's up-to-date */ | |
2687 | if (PageUptodate(page)) | |
2688 | set_buffer_uptodate(bh); | |
2689 | ||
2690 | if (!buffer_uptodate(bh) && !buffer_delay(bh)) { | |
2691 | err = -EIO; | |
2692 | ll_rw_block(READ, 1, &bh); | |
2693 | wait_on_buffer(bh); | |
2694 | /* Uhhuh. Read error. Complain and punt. */ | |
2695 | if (!buffer_uptodate(bh)) | |
2696 | goto unlock; | |
2697 | } | |
2698 | ||
2699 | kaddr = kmap_atomic(page, KM_USER0); | |
2700 | memset(kaddr + offset, 0, length); | |
2701 | flush_dcache_page(page); | |
2702 | kunmap_atomic(kaddr, KM_USER0); | |
2703 | ||
2704 | mark_buffer_dirty(bh); | |
2705 | err = 0; | |
2706 | ||
2707 | unlock: | |
2708 | unlock_page(page); | |
2709 | page_cache_release(page); | |
2710 | out: | |
2711 | return err; | |
2712 | } | |
2713 | ||
2714 | /* | |
2715 | * The generic ->writepage function for buffer-backed address_spaces | |
2716 | */ | |
2717 | int block_write_full_page(struct page *page, get_block_t *get_block, | |
2718 | struct writeback_control *wbc) | |
2719 | { | |
2720 | struct inode * const inode = page->mapping->host; | |
2721 | loff_t i_size = i_size_read(inode); | |
2722 | const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT; | |
2723 | unsigned offset; | |
2724 | void *kaddr; | |
2725 | ||
2726 | /* Is the page fully inside i_size? */ | |
2727 | if (page->index < end_index) | |
2728 | return __block_write_full_page(inode, page, get_block, wbc); | |
2729 | ||
2730 | /* Is the page fully outside i_size? (truncate in progress) */ | |
2731 | offset = i_size & (PAGE_CACHE_SIZE-1); | |
2732 | if (page->index >= end_index+1 || !offset) { | |
2733 | /* | |
2734 | * The page may have dirty, unmapped buffers. For example, | |
2735 | * they may have been added in ext3_writepage(). Make them | |
2736 | * freeable here, so the page does not leak. | |
2737 | */ | |
aaa4059b | 2738 | do_invalidatepage(page, 0); |
1da177e4 LT |
2739 | unlock_page(page); |
2740 | return 0; /* don't care */ | |
2741 | } | |
2742 | ||
2743 | /* | |
2744 | * The page straddles i_size. It must be zeroed out on each and every | |
2745 | * writepage invokation because it may be mmapped. "A file is mapped | |
2746 | * in multiples of the page size. For a file that is not a multiple of | |
2747 | * the page size, the remaining memory is zeroed when mapped, and | |
2748 | * writes to that region are not written out to the file." | |
2749 | */ | |
2750 | kaddr = kmap_atomic(page, KM_USER0); | |
2751 | memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); | |
2752 | flush_dcache_page(page); | |
2753 | kunmap_atomic(kaddr, KM_USER0); | |
2754 | return __block_write_full_page(inode, page, get_block, wbc); | |
2755 | } | |
2756 | ||
2757 | sector_t generic_block_bmap(struct address_space *mapping, sector_t block, | |
2758 | get_block_t *get_block) | |
2759 | { | |
2760 | struct buffer_head tmp; | |
2761 | struct inode *inode = mapping->host; | |
2762 | tmp.b_state = 0; | |
2763 | tmp.b_blocknr = 0; | |
b0cf2321 | 2764 | tmp.b_size = 1 << inode->i_blkbits; |
1da177e4 LT |
2765 | get_block(inode, block, &tmp, 0); |
2766 | return tmp.b_blocknr; | |
2767 | } | |
2768 | ||
2769 | static int end_bio_bh_io_sync(struct bio *bio, unsigned int bytes_done, int err) | |
2770 | { | |
2771 | struct buffer_head *bh = bio->bi_private; | |
2772 | ||
2773 | if (bio->bi_size) | |
2774 | return 1; | |
2775 | ||
2776 | if (err == -EOPNOTSUPP) { | |
2777 | set_bit(BIO_EOPNOTSUPP, &bio->bi_flags); | |
2778 | set_bit(BH_Eopnotsupp, &bh->b_state); | |
2779 | } | |
2780 | ||
2781 | bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags)); | |
2782 | bio_put(bio); | |
2783 | return 0; | |
2784 | } | |
2785 | ||
2786 | int submit_bh(int rw, struct buffer_head * bh) | |
2787 | { | |
2788 | struct bio *bio; | |
2789 | int ret = 0; | |
2790 | ||
2791 | BUG_ON(!buffer_locked(bh)); | |
2792 | BUG_ON(!buffer_mapped(bh)); | |
2793 | BUG_ON(!bh->b_end_io); | |
2794 | ||
2795 | if (buffer_ordered(bh) && (rw == WRITE)) | |
2796 | rw = WRITE_BARRIER; | |
2797 | ||
2798 | /* | |
2799 | * Only clear out a write error when rewriting, should this | |
2800 | * include WRITE_SYNC as well? | |
2801 | */ | |
2802 | if (test_set_buffer_req(bh) && (rw == WRITE || rw == WRITE_BARRIER)) | |
2803 | clear_buffer_write_io_error(bh); | |
2804 | ||
2805 | /* | |
2806 | * from here on down, it's all bio -- do the initial mapping, | |
2807 | * submit_bio -> generic_make_request may further map this bio around | |
2808 | */ | |
2809 | bio = bio_alloc(GFP_NOIO, 1); | |
2810 | ||
2811 | bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); | |
2812 | bio->bi_bdev = bh->b_bdev; | |
2813 | bio->bi_io_vec[0].bv_page = bh->b_page; | |
2814 | bio->bi_io_vec[0].bv_len = bh->b_size; | |
2815 | bio->bi_io_vec[0].bv_offset = bh_offset(bh); | |
2816 | ||
2817 | bio->bi_vcnt = 1; | |
2818 | bio->bi_idx = 0; | |
2819 | bio->bi_size = bh->b_size; | |
2820 | ||
2821 | bio->bi_end_io = end_bio_bh_io_sync; | |
2822 | bio->bi_private = bh; | |
2823 | ||
2824 | bio_get(bio); | |
2825 | submit_bio(rw, bio); | |
2826 | ||
2827 | if (bio_flagged(bio, BIO_EOPNOTSUPP)) | |
2828 | ret = -EOPNOTSUPP; | |
2829 | ||
2830 | bio_put(bio); | |
2831 | return ret; | |
2832 | } | |
2833 | ||
2834 | /** | |
2835 | * ll_rw_block: low-level access to block devices (DEPRECATED) | |
a7662236 | 2836 | * @rw: whether to %READ or %WRITE or %SWRITE or maybe %READA (readahead) |
1da177e4 LT |
2837 | * @nr: number of &struct buffer_heads in the array |
2838 | * @bhs: array of pointers to &struct buffer_head | |
2839 | * | |
a7662236 JK |
2840 | * ll_rw_block() takes an array of pointers to &struct buffer_heads, and |
2841 | * requests an I/O operation on them, either a %READ or a %WRITE. The third | |
2842 | * %SWRITE is like %WRITE only we make sure that the *current* data in buffers | |
2843 | * are sent to disk. The fourth %READA option is described in the documentation | |
2844 | * for generic_make_request() which ll_rw_block() calls. | |
1da177e4 LT |
2845 | * |
2846 | * This function drops any buffer that it cannot get a lock on (with the | |
a7662236 JK |
2847 | * BH_Lock state bit) unless SWRITE is required, any buffer that appears to be |
2848 | * clean when doing a write request, and any buffer that appears to be | |
2849 | * up-to-date when doing read request. Further it marks as clean buffers that | |
2850 | * are processed for writing (the buffer cache won't assume that they are | |
2851 | * actually clean until the buffer gets unlocked). | |
1da177e4 LT |
2852 | * |
2853 | * ll_rw_block sets b_end_io to simple completion handler that marks | |
2854 | * the buffer up-to-date (if approriate), unlocks the buffer and wakes | |
2855 | * any waiters. | |
2856 | * | |
2857 | * All of the buffers must be for the same device, and must also be a | |
2858 | * multiple of the current approved size for the device. | |
2859 | */ | |
2860 | void ll_rw_block(int rw, int nr, struct buffer_head *bhs[]) | |
2861 | { | |
2862 | int i; | |
2863 | ||
2864 | for (i = 0; i < nr; i++) { | |
2865 | struct buffer_head *bh = bhs[i]; | |
2866 | ||
a7662236 JK |
2867 | if (rw == SWRITE) |
2868 | lock_buffer(bh); | |
2869 | else if (test_set_buffer_locked(bh)) | |
1da177e4 LT |
2870 | continue; |
2871 | ||
a7662236 | 2872 | if (rw == WRITE || rw == SWRITE) { |
1da177e4 | 2873 | if (test_clear_buffer_dirty(bh)) { |
76c3073a | 2874 | bh->b_end_io = end_buffer_write_sync; |
e60e5c50 | 2875 | get_bh(bh); |
1da177e4 LT |
2876 | submit_bh(WRITE, bh); |
2877 | continue; | |
2878 | } | |
2879 | } else { | |
1da177e4 | 2880 | if (!buffer_uptodate(bh)) { |
76c3073a | 2881 | bh->b_end_io = end_buffer_read_sync; |
e60e5c50 | 2882 | get_bh(bh); |
1da177e4 LT |
2883 | submit_bh(rw, bh); |
2884 | continue; | |
2885 | } | |
2886 | } | |
2887 | unlock_buffer(bh); | |
1da177e4 LT |
2888 | } |
2889 | } | |
2890 | ||
2891 | /* | |
2892 | * For a data-integrity writeout, we need to wait upon any in-progress I/O | |
2893 | * and then start new I/O and then wait upon it. The caller must have a ref on | |
2894 | * the buffer_head. | |
2895 | */ | |
2896 | int sync_dirty_buffer(struct buffer_head *bh) | |
2897 | { | |
2898 | int ret = 0; | |
2899 | ||
2900 | WARN_ON(atomic_read(&bh->b_count) < 1); | |
2901 | lock_buffer(bh); | |
2902 | if (test_clear_buffer_dirty(bh)) { | |
2903 | get_bh(bh); | |
2904 | bh->b_end_io = end_buffer_write_sync; | |
2905 | ret = submit_bh(WRITE, bh); | |
2906 | wait_on_buffer(bh); | |
2907 | if (buffer_eopnotsupp(bh)) { | |
2908 | clear_buffer_eopnotsupp(bh); | |
2909 | ret = -EOPNOTSUPP; | |
2910 | } | |
2911 | if (!ret && !buffer_uptodate(bh)) | |
2912 | ret = -EIO; | |
2913 | } else { | |
2914 | unlock_buffer(bh); | |
2915 | } | |
2916 | return ret; | |
2917 | } | |
2918 | ||
2919 | /* | |
2920 | * try_to_free_buffers() checks if all the buffers on this particular page | |
2921 | * are unused, and releases them if so. | |
2922 | * | |
2923 | * Exclusion against try_to_free_buffers may be obtained by either | |
2924 | * locking the page or by holding its mapping's private_lock. | |
2925 | * | |
2926 | * If the page is dirty but all the buffers are clean then we need to | |
2927 | * be sure to mark the page clean as well. This is because the page | |
2928 | * may be against a block device, and a later reattachment of buffers | |
2929 | * to a dirty page will set *all* buffers dirty. Which would corrupt | |
2930 | * filesystem data on the same device. | |
2931 | * | |
2932 | * The same applies to regular filesystem pages: if all the buffers are | |
2933 | * clean then we set the page clean and proceed. To do that, we require | |
2934 | * total exclusion from __set_page_dirty_buffers(). That is obtained with | |
2935 | * private_lock. | |
2936 | * | |
2937 | * try_to_free_buffers() is non-blocking. | |
2938 | */ | |
2939 | static inline int buffer_busy(struct buffer_head *bh) | |
2940 | { | |
2941 | return atomic_read(&bh->b_count) | | |
2942 | (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock))); | |
2943 | } | |
2944 | ||
2945 | static int | |
2946 | drop_buffers(struct page *page, struct buffer_head **buffers_to_free) | |
2947 | { | |
2948 | struct buffer_head *head = page_buffers(page); | |
2949 | struct buffer_head *bh; | |
2950 | ||
2951 | bh = head; | |
2952 | do { | |
de7d5a3b | 2953 | if (buffer_write_io_error(bh) && page->mapping) |
1da177e4 LT |
2954 | set_bit(AS_EIO, &page->mapping->flags); |
2955 | if (buffer_busy(bh)) | |
2956 | goto failed; | |
2957 | bh = bh->b_this_page; | |
2958 | } while (bh != head); | |
2959 | ||
2960 | do { | |
2961 | struct buffer_head *next = bh->b_this_page; | |
2962 | ||
2963 | if (!list_empty(&bh->b_assoc_buffers)) | |
2964 | __remove_assoc_queue(bh); | |
2965 | bh = next; | |
2966 | } while (bh != head); | |
2967 | *buffers_to_free = head; | |
2968 | __clear_page_buffers(page); | |
2969 | return 1; | |
2970 | failed: | |
2971 | return 0; | |
2972 | } | |
2973 | ||
2974 | int try_to_free_buffers(struct page *page) | |
2975 | { | |
2976 | struct address_space * const mapping = page->mapping; | |
2977 | struct buffer_head *buffers_to_free = NULL; | |
2978 | int ret = 0; | |
2979 | ||
2980 | BUG_ON(!PageLocked(page)); | |
2981 | if (PageWriteback(page)) | |
2982 | return 0; | |
2983 | ||
2984 | if (mapping == NULL) { /* can this still happen? */ | |
2985 | ret = drop_buffers(page, &buffers_to_free); | |
2986 | goto out; | |
2987 | } | |
2988 | ||
2989 | spin_lock(&mapping->private_lock); | |
2990 | ret = drop_buffers(page, &buffers_to_free); | |
2991 | if (ret) { | |
2992 | /* | |
2993 | * If the filesystem writes its buffers by hand (eg ext3) | |
2994 | * then we can have clean buffers against a dirty page. We | |
2995 | * clean the page here; otherwise later reattachment of buffers | |
2996 | * could encounter a non-uptodate page, which is unresolvable. | |
2997 | * This only applies in the rare case where try_to_free_buffers | |
2998 | * succeeds but the page is not freed. | |
2999 | */ | |
3000 | clear_page_dirty(page); | |
3001 | } | |
3002 | spin_unlock(&mapping->private_lock); | |
3003 | out: | |
3004 | if (buffers_to_free) { | |
3005 | struct buffer_head *bh = buffers_to_free; | |
3006 | ||
3007 | do { | |
3008 | struct buffer_head *next = bh->b_this_page; | |
3009 | free_buffer_head(bh); | |
3010 | bh = next; | |
3011 | } while (bh != buffers_to_free); | |
3012 | } | |
3013 | return ret; | |
3014 | } | |
3015 | EXPORT_SYMBOL(try_to_free_buffers); | |
3016 | ||
3978d717 | 3017 | void block_sync_page(struct page *page) |
1da177e4 LT |
3018 | { |
3019 | struct address_space *mapping; | |
3020 | ||
3021 | smp_mb(); | |
3022 | mapping = page_mapping(page); | |
3023 | if (mapping) | |
3024 | blk_run_backing_dev(mapping->backing_dev_info, page); | |
1da177e4 LT |
3025 | } |
3026 | ||
3027 | /* | |
3028 | * There are no bdflush tunables left. But distributions are | |
3029 | * still running obsolete flush daemons, so we terminate them here. | |
3030 | * | |
3031 | * Use of bdflush() is deprecated and will be removed in a future kernel. | |
3032 | * The `pdflush' kernel threads fully replace bdflush daemons and this call. | |
3033 | */ | |
3034 | asmlinkage long sys_bdflush(int func, long data) | |
3035 | { | |
3036 | static int msg_count; | |
3037 | ||
3038 | if (!capable(CAP_SYS_ADMIN)) | |
3039 | return -EPERM; | |
3040 | ||
3041 | if (msg_count < 5) { | |
3042 | msg_count++; | |
3043 | printk(KERN_INFO | |
3044 | "warning: process `%s' used the obsolete bdflush" | |
3045 | " system call\n", current->comm); | |
3046 | printk(KERN_INFO "Fix your initscripts?\n"); | |
3047 | } | |
3048 | ||
3049 | if (func == 1) | |
3050 | do_exit(0); | |
3051 | return 0; | |
3052 | } | |
3053 | ||
3054 | /* | |
3055 | * Buffer-head allocation | |
3056 | */ | |
3057 | static kmem_cache_t *bh_cachep; | |
3058 | ||
3059 | /* | |
3060 | * Once the number of bh's in the machine exceeds this level, we start | |
3061 | * stripping them in writeback. | |
3062 | */ | |
3063 | static int max_buffer_heads; | |
3064 | ||
3065 | int buffer_heads_over_limit; | |
3066 | ||
3067 | struct bh_accounting { | |
3068 | int nr; /* Number of live bh's */ | |
3069 | int ratelimit; /* Limit cacheline bouncing */ | |
3070 | }; | |
3071 | ||
3072 | static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0}; | |
3073 | ||
3074 | static void recalc_bh_state(void) | |
3075 | { | |
3076 | int i; | |
3077 | int tot = 0; | |
3078 | ||
3079 | if (__get_cpu_var(bh_accounting).ratelimit++ < 4096) | |
3080 | return; | |
3081 | __get_cpu_var(bh_accounting).ratelimit = 0; | |
8a143426 | 3082 | for_each_online_cpu(i) |
1da177e4 LT |
3083 | tot += per_cpu(bh_accounting, i).nr; |
3084 | buffer_heads_over_limit = (tot > max_buffer_heads); | |
3085 | } | |
3086 | ||
dd0fc66f | 3087 | struct buffer_head *alloc_buffer_head(gfp_t gfp_flags) |
1da177e4 LT |
3088 | { |
3089 | struct buffer_head *ret = kmem_cache_alloc(bh_cachep, gfp_flags); | |
3090 | if (ret) { | |
736c7b80 | 3091 | get_cpu_var(bh_accounting).nr++; |
1da177e4 | 3092 | recalc_bh_state(); |
736c7b80 | 3093 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3094 | } |
3095 | return ret; | |
3096 | } | |
3097 | EXPORT_SYMBOL(alloc_buffer_head); | |
3098 | ||
3099 | void free_buffer_head(struct buffer_head *bh) | |
3100 | { | |
3101 | BUG_ON(!list_empty(&bh->b_assoc_buffers)); | |
3102 | kmem_cache_free(bh_cachep, bh); | |
736c7b80 | 3103 | get_cpu_var(bh_accounting).nr--; |
1da177e4 | 3104 | recalc_bh_state(); |
736c7b80 | 3105 | put_cpu_var(bh_accounting); |
1da177e4 LT |
3106 | } |
3107 | EXPORT_SYMBOL(free_buffer_head); | |
3108 | ||
3109 | static void | |
3110 | init_buffer_head(void *data, kmem_cache_t *cachep, unsigned long flags) | |
3111 | { | |
3112 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == | |
3113 | SLAB_CTOR_CONSTRUCTOR) { | |
3114 | struct buffer_head * bh = (struct buffer_head *)data; | |
3115 | ||
3116 | memset(bh, 0, sizeof(*bh)); | |
3117 | INIT_LIST_HEAD(&bh->b_assoc_buffers); | |
3118 | } | |
3119 | } | |
3120 | ||
3121 | #ifdef CONFIG_HOTPLUG_CPU | |
3122 | static void buffer_exit_cpu(int cpu) | |
3123 | { | |
3124 | int i; | |
3125 | struct bh_lru *b = &per_cpu(bh_lrus, cpu); | |
3126 | ||
3127 | for (i = 0; i < BH_LRU_SIZE; i++) { | |
3128 | brelse(b->bhs[i]); | |
3129 | b->bhs[i] = NULL; | |
3130 | } | |
8a143426 ED |
3131 | get_cpu_var(bh_accounting).nr += per_cpu(bh_accounting, cpu).nr; |
3132 | per_cpu(bh_accounting, cpu).nr = 0; | |
3133 | put_cpu_var(bh_accounting); | |
1da177e4 LT |
3134 | } |
3135 | ||
3136 | static int buffer_cpu_notify(struct notifier_block *self, | |
3137 | unsigned long action, void *hcpu) | |
3138 | { | |
3139 | if (action == CPU_DEAD) | |
3140 | buffer_exit_cpu((unsigned long)hcpu); | |
3141 | return NOTIFY_OK; | |
3142 | } | |
3143 | #endif /* CONFIG_HOTPLUG_CPU */ | |
3144 | ||
3145 | void __init buffer_init(void) | |
3146 | { | |
3147 | int nrpages; | |
3148 | ||
3149 | bh_cachep = kmem_cache_create("buffer_head", | |
b0196009 PJ |
3150 | sizeof(struct buffer_head), 0, |
3151 | (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| | |
3152 | SLAB_MEM_SPREAD), | |
3153 | init_buffer_head, | |
3154 | NULL); | |
1da177e4 LT |
3155 | |
3156 | /* | |
3157 | * Limit the bh occupancy to 10% of ZONE_NORMAL | |
3158 | */ | |
3159 | nrpages = (nr_free_buffer_pages() * 10) / 100; | |
3160 | max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head)); | |
3161 | hotcpu_notifier(buffer_cpu_notify, 0); | |
3162 | } | |
3163 | ||
3164 | EXPORT_SYMBOL(__bforget); | |
3165 | EXPORT_SYMBOL(__brelse); | |
3166 | EXPORT_SYMBOL(__wait_on_buffer); | |
3167 | EXPORT_SYMBOL(block_commit_write); | |
3168 | EXPORT_SYMBOL(block_prepare_write); | |
3169 | EXPORT_SYMBOL(block_read_full_page); | |
3170 | EXPORT_SYMBOL(block_sync_page); | |
3171 | EXPORT_SYMBOL(block_truncate_page); | |
3172 | EXPORT_SYMBOL(block_write_full_page); | |
3173 | EXPORT_SYMBOL(cont_prepare_write); | |
3174 | EXPORT_SYMBOL(end_buffer_async_write); | |
3175 | EXPORT_SYMBOL(end_buffer_read_sync); | |
3176 | EXPORT_SYMBOL(end_buffer_write_sync); | |
3177 | EXPORT_SYMBOL(file_fsync); | |
3178 | EXPORT_SYMBOL(fsync_bdev); | |
3179 | EXPORT_SYMBOL(generic_block_bmap); | |
3180 | EXPORT_SYMBOL(generic_commit_write); | |
3181 | EXPORT_SYMBOL(generic_cont_expand); | |
05eb0b51 | 3182 | EXPORT_SYMBOL(generic_cont_expand_simple); |
1da177e4 LT |
3183 | EXPORT_SYMBOL(init_buffer); |
3184 | EXPORT_SYMBOL(invalidate_bdev); | |
3185 | EXPORT_SYMBOL(ll_rw_block); | |
3186 | EXPORT_SYMBOL(mark_buffer_dirty); | |
3187 | EXPORT_SYMBOL(submit_bh); | |
3188 | EXPORT_SYMBOL(sync_dirty_buffer); | |
3189 | EXPORT_SYMBOL(unlock_buffer); |