Branch data Line data Source code
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/kernel.h>
22 : : #include <linux/syscalls.h>
23 : : #include <linux/fs.h>
24 : : #include <linux/mm.h>
25 : : #include <linux/percpu.h>
26 : : #include <linux/slab.h>
27 : : #include <linux/capability.h>
28 : : #include <linux/blkdev.h>
29 : : #include <linux/file.h>
30 : : #include <linux/quotaops.h>
31 : : #include <linux/highmem.h>
32 : : #include <linux/export.h>
33 : : #include <linux/writeback.h>
34 : : #include <linux/hash.h>
35 : : #include <linux/suspend.h>
36 : : #include <linux/buffer_head.h>
37 : : #include <linux/task_io_accounting_ops.h>
38 : : #include <linux/bio.h>
39 : : #include <linux/notifier.h>
40 : : #include <linux/cpu.h>
41 : : #include <linux/bitops.h>
42 : : #include <linux/mpage.h>
43 : : #include <linux/bit_spinlock.h>
44 : : #include <trace/events/block.h>
45 : :
46 : : static int fsync_buffers_list(spinlock_t *lock, struct list_head *list);
47 : :
48 : : #define BH_ENTRY(list) list_entry((list), struct buffer_head, b_assoc_buffers)
49 : :
50 : 0 : void init_buffer(struct buffer_head *bh, bh_end_io_t *handler, void *private)
51 : : {
52 : 59594 : bh->b_end_io = handler;
53 : 59594 : bh->b_private = private;
54 : 0 : }
55 : : EXPORT_SYMBOL(init_buffer);
56 : :
57 : 0 : inline void touch_buffer(struct buffer_head *bh)
58 : : {
59 : : trace_block_touch_buffer(bh);
60 : 14354989 : mark_page_accessed(bh->b_page);
61 : 0 : }
62 : : EXPORT_SYMBOL(touch_buffer);
63 : :
64 : 0 : static int sleep_on_buffer(void *word)
65 : : {
66 : 43784 : io_schedule();
67 : 43784 : return 0;
68 : : }
69 : :
70 : 0 : void __lock_buffer(struct buffer_head *bh)
71 : : {
72 : 4990 : wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
73 : : TASK_UNINTERRUPTIBLE);
74 : 1 : }
75 : : EXPORT_SYMBOL(__lock_buffer);
76 : :
77 : 0 : void unlock_buffer(struct buffer_head *bh)
78 : : {
79 : 19032298 : clear_bit_unlock(BH_Lock, &bh->b_state);
80 : 19032982 : smp_mb__after_clear_bit();
81 : 19032671 : wake_up_bit(&bh->b_state, BH_Lock);
82 : 19032215 : }
83 : : EXPORT_SYMBOL(unlock_buffer);
84 : :
85 : : /*
86 : : * Returns if the page has dirty or writeback buffers. If all the buffers
87 : : * are unlocked and clean then the PageDirty information is stale. If
88 : : * any of the pages are locked, it is assumed they are locked for IO.
89 : : */
90 : 0 : void buffer_check_dirty_writeback(struct page *page,
91 : : bool *dirty, bool *writeback)
92 : : {
93 : : struct buffer_head *head, *bh;
94 : 52196 : *dirty = false;
95 : 52196 : *writeback = false;
96 : :
97 [ - + ]: 52196 : BUG_ON(!PageLocked(page));
98 : :
99 [ + ]: 52196 : if (!page_has_buffers(page))
100 : 0 : return;
101 : :
102 [ + + ]: 52215 : if (PageWriteback(page))
103 : 104 : *writeback = true;
104 : :
105 : : head = page_buffers(page);
106 : : bh = head;
107 : : do {
108 [ + + ]: 52215 : if (buffer_locked(bh))
109 : 105 : *writeback = true;
110 : :
111 [ + + ]: 52215 : if (buffer_dirty(bh))
112 : 37 : *dirty = true;
113 : :
114 : 52215 : bh = bh->b_this_page;
115 [ - + ]: 52215 : } while (bh != head);
116 : : }
117 : : EXPORT_SYMBOL(buffer_check_dirty_writeback);
118 : :
119 : : /*
120 : : * Block until a buffer comes unlocked. This doesn't stop it
121 : : * from becoming locked again - you have to lock it yourself
122 : : * if you want to preserve its state.
123 : : */
124 : 0 : void __wait_on_buffer(struct buffer_head * bh)
125 : : {
126 : 42037 : wait_on_bit(&bh->b_state, BH_Lock, sleep_on_buffer, TASK_UNINTERRUPTIBLE);
127 : 0 : }
128 : : EXPORT_SYMBOL(__wait_on_buffer);
129 : :
130 : : static void
131 : 0 : __clear_page_buffers(struct page *page)
132 : : {
133 : : ClearPagePrivate(page);
134 : 1913330 : set_page_private(page, 0);
135 : 1913330 : page_cache_release(page);
136 : 1913326 : }
137 : :
138 : :
139 : 0 : static int quiet_error(struct buffer_head *bh)
140 : : {
141 [ # # ][ # # ]: 0 : if (!test_bit(BH_Quiet, &bh->b_state) && printk_ratelimit())
142 : : return 0;
143 : : return 1;
144 : : }
145 : :
146 : :
147 : 0 : static void buffer_io_error(struct buffer_head *bh)
148 : : {
149 : : char b[BDEVNAME_SIZE];
150 : 0 : printk(KERN_ERR "Buffer I/O error on device %s, logical block %Lu\n",
151 : : bdevname(bh->b_bdev, b),
152 : : (unsigned long long)bh->b_blocknr);
153 : 0 : }
154 : :
155 : : /*
156 : : * End-of-IO handler helper function which does not touch the bh after
157 : : * unlocking it.
158 : : * Note: unlock_buffer() sort-of does touch the bh after unlocking it, but
159 : : * a race there is benign: unlock_buffer() only use the bh's address for
160 : : * hashing after unlocking the buffer, so it doesn't actually touch the bh
161 : : * itself.
162 : : */
163 : 0 : static void __end_buffer_read_notouch(struct buffer_head *bh, int uptodate)
164 : : {
165 [ + - ]: 5255 : if (uptodate) {
166 : : set_buffer_uptodate(bh);
167 : : } else {
168 : : /* This happens, due to failed READA attempts. */
169 : : clear_buffer_uptodate(bh);
170 : : }
171 : 5255 : unlock_buffer(bh);
172 : 5255 : }
173 : :
174 : : /*
175 : : * Default synchronous end-of-IO handler.. Just mark it up-to-date and
176 : : * unlock the buffer. This is what ll_rw_block uses too.
177 : : */
178 : 0 : void end_buffer_read_sync(struct buffer_head *bh, int uptodate)
179 : : {
180 : 5255 : __end_buffer_read_notouch(bh, uptodate);
181 : : put_bh(bh);
182 : 5255 : }
183 : : EXPORT_SYMBOL(end_buffer_read_sync);
184 : :
185 : 0 : void end_buffer_write_sync(struct buffer_head *bh, int uptodate)
186 : : {
187 : : char b[BDEVNAME_SIZE];
188 : :
189 [ + - ]: 623 : if (uptodate) {
190 : : set_buffer_uptodate(bh);
191 : : } else {
192 [ # # ]: 0 : if (!quiet_error(bh)) {
193 : 0 : buffer_io_error(bh);
194 : 0 : printk(KERN_WARNING "lost page write due to "
195 : : "I/O error on %s\n",
196 : : bdevname(bh->b_bdev, b));
197 : : }
198 : : set_buffer_write_io_error(bh);
199 : : clear_buffer_uptodate(bh);
200 : : }
201 : 623 : unlock_buffer(bh);
202 : : put_bh(bh);
203 : 623 : }
204 : : EXPORT_SYMBOL(end_buffer_write_sync);
205 : :
206 : : /*
207 : : * Various filesystems appear to want __find_get_block to be non-blocking.
208 : : * But it's the page lock which protects the buffers. To get around this,
209 : : * we get exclusion from try_to_free_buffers with the blockdev mapping's
210 : : * private_lock.
211 : : *
212 : : * Hack idea: for the blockdev mapping, i_bufferlist_lock contention
213 : : * may be quite high. This code could TryLock the page, and if that
214 : : * succeeds, there is no need to take private_lock. (But if
215 : : * private_lock is contended then so is mapping->tree_lock).
216 : : */
217 : : static struct buffer_head *
218 : 0 : __find_get_block_slow(struct block_device *bdev, sector_t block)
219 : : {
220 : 3058301 : struct inode *bd_inode = bdev->bd_inode;
221 : 3058301 : struct address_space *bd_mapping = bd_inode->i_mapping;
222 : : struct buffer_head *ret = NULL;
223 : : pgoff_t index;
224 : : struct buffer_head *bh;
225 : : struct buffer_head *head;
226 : : struct page *page;
227 : : int all_mapped = 1;
228 : :
229 : 3058301 : index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
230 : 3058301 : page = find_get_page(bd_mapping, index);
231 [ + + ]: 3058354 : if (!page)
232 : : goto out;
233 : :
234 : : spin_lock(&bd_mapping->private_lock);
235 [ + ]: 306084 : if (!page_has_buffers(page))
236 : : goto out_unlock;
237 [ - + ]: 3364382 : head = page_buffers(page);
238 : : bh = head;
239 : : do {
240 [ + - ]: 306081 : if (!buffer_mapped(bh))
241 : : all_mapped = 0;
242 [ + - ]: 306081 : else if (bh->b_blocknr == block) {
243 : : ret = bh;
244 : : get_bh(bh);
245 : : goto out_unlock;
246 : : }
247 : 0 : bh = bh->b_this_page;
248 [ # # ]: 0 : } while (bh != head);
249 : :
250 : : /* we might be here because some of the buffers on this page are
251 : : * not mapped. This is due to various races between
252 : : * file io on the block device and getblk. It gets dealt with
253 : : * elsewhere, don't buffer_error if we had some unmapped buffers
254 : : */
255 [ # # ]: 0 : if (all_mapped) {
256 : : char b[BDEVNAME_SIZE];
257 : :
258 : 0 : printk("__find_get_block_slow() failed. "
259 : : "block=%llu, b_blocknr=%llu\n",
260 : : (unsigned long long)block,
261 : : (unsigned long long)bh->b_blocknr);
262 : 0 : printk("b_state=0x%08lx, b_size=%zu\n",
263 : : bh->b_state, bh->b_size);
264 : 0 : printk("device %s blocksize: %d\n", bdevname(bdev, b),
265 : 0 : 1 << bd_inode->i_blkbits);
266 : : }
267 : : out_unlock:
268 : : spin_unlock(&bd_mapping->private_lock);
269 : 306084 : page_cache_release(page);
270 : : out:
271 : 3058360 : return ret;
272 : : }
273 : :
274 : : /*
275 : : * Kick the writeback threads then try to free up some ZONE_NORMAL memory.
276 : : */
277 : 0 : static void free_more_memory(void)
278 : : {
279 : : struct zone *zone;
280 : : int nid;
281 : :
282 : 0 : wakeup_flusher_threads(1024, WB_REASON_FREE_MORE_MEM);
283 : 0 : yield();
284 : :
285 [ # # ]: 0 : for_each_online_node(nid) {
286 : : (void)first_zones_zonelist(node_zonelist(nid, GFP_NOFS),
287 : : gfp_zone(GFP_NOFS), NULL,
288 : : &zone);
289 [ # # ]: 0 : if (zone)
290 : 0 : try_to_free_pages(node_zonelist(nid, GFP_NOFS), 0,
291 : : GFP_NOFS, NULL);
292 : : }
293 : 0 : }
294 : :
295 : : /*
296 : : * I/O completion handler for block_read_full_page() - pages
297 : : * which come unlocked at the end of I/O.
298 : : */
299 : 0 : static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
300 : : {
301 : : unsigned long flags;
302 : : struct buffer_head *first;
303 : : struct buffer_head *tmp;
304 : : struct page *page;
305 : : int page_uptodate = 1;
306 : :
307 [ - + ]: 668 : BUG_ON(!buffer_async_read(bh));
308 : :
309 : 668 : page = bh->b_page;
310 [ + - ]: 668 : if (uptodate) {
311 : : set_buffer_uptodate(bh);
312 : : } else {
313 : : clear_buffer_uptodate(bh);
314 [ # # ]: 0 : if (!quiet_error(bh))
315 : 0 : buffer_io_error(bh);
316 : : SetPageError(page);
317 : : }
318 : :
319 : : /*
320 : : * Be _very_ careful from here on. Bad things can happen if
321 : : * two buffer heads end IO at almost the same time and both
322 : : * decide that the page is now completely done.
323 : : */
324 [ - + ]: 668 : first = page_buffers(page);
325 : : local_irq_save(flags);
326 : 668 : bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
327 : : clear_buffer_async_read(bh);
328 : 668 : unlock_buffer(bh);
329 : : tmp = bh;
330 : : do {
331 [ - + ]: 1336 : if (!buffer_uptodate(tmp))
332 : : page_uptodate = 0;
333 [ - + ]: 668 : if (buffer_async_read(tmp)) {
334 [ # # ]: 0 : BUG_ON(!buffer_locked(tmp));
335 : : goto still_busy;
336 : : }
337 : 668 : tmp = tmp->b_this_page;
338 [ - + ]: 668 : } while (tmp != bh);
339 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
340 [ - + ]: 668 : local_irq_restore(flags);
341 : :
342 : : /*
343 : : * If none of the buffers had errors and they are all
344 : : * uptodate then we can set the page uptodate.
345 : : */
346 [ + - ][ + - ]: 668 : if (page_uptodate && !PageError(page))
347 : : SetPageUptodate(page);
348 : 668 : unlock_page(page);
349 : 668 : return;
350 : :
351 : : still_busy:
352 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
353 [ # # ]: 0 : local_irq_restore(flags);
354 : : return;
355 : : }
356 : :
357 : : /*
358 : : * Completion handler for block_write_full_page() - pages which are unlocked
359 : : * during I/O, and which have PageWriteback cleared upon I/O completion.
360 : : */
361 : 0 : void end_buffer_async_write(struct buffer_head *bh, int uptodate)
362 : : {
363 : : char b[BDEVNAME_SIZE];
364 : : unsigned long flags;
365 : : struct buffer_head *first;
366 : : struct buffer_head *tmp;
367 : : struct page *page;
368 : :
369 [ - + ]: 19852 : BUG_ON(!buffer_async_write(bh));
370 : :
371 : 19852 : page = bh->b_page;
372 [ + - ]: 19852 : if (uptodate) {
373 : : set_buffer_uptodate(bh);
374 : : } else {
375 [ # # ]: 0 : if (!quiet_error(bh)) {
376 : 0 : buffer_io_error(bh);
377 : 0 : printk(KERN_WARNING "lost page write due to "
378 : : "I/O error on %s\n",
379 : : bdevname(bh->b_bdev, b));
380 : : }
381 : 0 : set_bit(AS_EIO, &page->mapping->flags);
382 : : set_buffer_write_io_error(bh);
383 : : clear_buffer_uptodate(bh);
384 : : SetPageError(page);
385 : : }
386 : :
387 [ - + ]: 19852 : first = page_buffers(page);
388 : : local_irq_save(flags);
389 : 19852 : bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
390 : :
391 : : clear_buffer_async_write(bh);
392 : 19852 : unlock_buffer(bh);
393 : 19852 : tmp = bh->b_this_page;
394 [ - + ]: 19852 : while (tmp != bh) {
395 [ # # ]: 0 : if (buffer_async_write(tmp)) {
396 [ # # ]: 0 : BUG_ON(!buffer_locked(tmp));
397 : : goto still_busy;
398 : : }
399 : 0 : tmp = tmp->b_this_page;
400 : : }
401 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
402 [ - + ]: 19852 : local_irq_restore(flags);
403 : 19852 : end_page_writeback(page);
404 : 19852 : return;
405 : :
406 : : still_busy:
407 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
408 [ # # ]: 0 : local_irq_restore(flags);
409 : : return;
410 : : }
411 : : EXPORT_SYMBOL(end_buffer_async_write);
412 : :
413 : : /*
414 : : * If a page's buffers are under async readin (end_buffer_async_read
415 : : * completion) then there is a possibility that another thread of
416 : : * control could lock one of the buffers after it has completed
417 : : * but while some of the other buffers have not completed. This
418 : : * locked buffer would confuse end_buffer_async_read() into not unlocking
419 : : * the page. So the absence of BH_Async_Read tells end_buffer_async_read()
420 : : * that this buffer is not under async I/O.
421 : : *
422 : : * The page comes unlocked when it has no locked buffer_async buffers
423 : : * left.
424 : : *
425 : : * PageLocked prevents anyone starting new async I/O reads any of
426 : : * the buffers.
427 : : *
428 : : * PageWriteback is used to prevent simultaneous writeout of the same
429 : : * page.
430 : : *
431 : : * PageLocked prevents anyone from starting writeback of a page which is
432 : : * under read I/O (PageWriteback is only ever set against a locked page).
433 : : */
434 : : static void mark_buffer_async_read(struct buffer_head *bh)
435 : : {
436 : 668 : bh->b_end_io = end_buffer_async_read;
437 : : set_buffer_async_read(bh);
438 : : }
439 : :
440 : : static void mark_buffer_async_write_endio(struct buffer_head *bh,
441 : : bh_end_io_t *handler)
442 : : {
443 : 19852 : bh->b_end_io = handler;
444 : : set_buffer_async_write(bh);
445 : : }
446 : :
447 : 0 : void mark_buffer_async_write(struct buffer_head *bh)
448 : : {
449 : : mark_buffer_async_write_endio(bh, end_buffer_async_write);
450 : 0 : }
451 : : EXPORT_SYMBOL(mark_buffer_async_write);
452 : :
453 : :
454 : : /*
455 : : * fs/buffer.c contains helper functions for buffer-backed address space's
456 : : * fsync functions. A common requirement for buffer-based filesystems is
457 : : * that certain data from the backing blockdev needs to be written out for
458 : : * a successful fsync(). For example, ext2 indirect blocks need to be
459 : : * written back and waited upon before fsync() returns.
460 : : *
461 : : * The functions mark_buffer_inode_dirty(), fsync_inode_buffers(),
462 : : * inode_has_buffers() and invalidate_inode_buffers() are provided for the
463 : : * management of a list of dependent buffers at ->i_mapping->private_list.
464 : : *
465 : : * Locking is a little subtle: try_to_free_buffers() will remove buffers
466 : : * from their controlling inode's queue when they are being freed. But
467 : : * try_to_free_buffers() will be operating against the *blockdev* mapping
468 : : * at the time, not against the S_ISREG file which depends on those buffers.
469 : : * So the locking for private_list is via the private_lock in the address_space
470 : : * which backs the buffers. Which is different from the address_space
471 : : * against which the buffers are listed. So for a particular address_space,
472 : : * mapping->private_lock does *not* protect mapping->private_list! In fact,
473 : : * mapping->private_list will always be protected by the backing blockdev's
474 : : * ->private_lock.
475 : : *
476 : : * Which introduces a requirement: all buffers on an address_space's
477 : : * ->private_list must be from the same address_space: the blockdev's.
478 : : *
479 : : * address_spaces which do not place buffers at ->private_list via these
480 : : * utility functions are free to use private_lock and private_list for
481 : : * whatever they want. The only requirement is that list_empty(private_list)
482 : : * be true at clear_inode() time.
483 : : *
484 : : * FIXME: clear_inode should not call invalidate_inode_buffers(). The
485 : : * filesystems should do that. invalidate_inode_buffers() should just go
486 : : * BUG_ON(!list_empty).
487 : : *
488 : : * FIXME: mark_buffer_dirty_inode() is a data-plane operation. It should
489 : : * take an address_space, not an inode. And it should be called
490 : : * mark_buffer_dirty_fsync() to clearly define why those buffers are being
491 : : * queued up.
492 : : *
493 : : * FIXME: mark_buffer_dirty_inode() doesn't need to add the buffer to the
494 : : * list if it is already on a list. Because if the buffer is on a list,
495 : : * it *must* already be on the right one. If not, the filesystem is being
496 : : * silly. This will save a ton of locking. But first we have to ensure
497 : : * that buffers are taken *off* the old inode's list when they are freed
498 : : * (presumably in truncate). That requires careful auditing of all
499 : : * filesystems (do it inside bforget()). It could also be done by bringing
500 : : * b_inode back.
501 : : */
502 : :
503 : : /*
504 : : * The buffer's backing address_space's private_lock must be held
505 : : */
506 : 0 : static void __remove_assoc_queue(struct buffer_head *bh)
507 : : {
508 : 0 : list_del_init(&bh->b_assoc_buffers);
509 [ # # ]: 0 : WARN_ON(!bh->b_assoc_map);
510 [ # # ]: 0 : if (buffer_write_io_error(bh))
511 : 0 : set_bit(AS_EIO, &bh->b_assoc_map->flags);
512 : 0 : bh->b_assoc_map = NULL;
513 : 0 : }
514 : :
515 : 0 : int inode_has_buffers(struct inode *inode)
516 : : {
517 : 4478956 : return !list_empty(&inode->i_data.private_list);
518 : : }
519 : :
520 : : /*
521 : : * osync is designed to support O_SYNC io. It waits synchronously for
522 : : * all already-submitted IO to complete, but does not queue any new
523 : : * writes to the disk.
524 : : *
525 : : * To do O_SYNC writes, just queue the buffer writes with ll_rw_block as
526 : : * you dirty the buffers, and then use osync_inode_buffers to wait for
527 : : * completion. Any other dirty buffers which are not yet queued for
528 : : * write will not be flushed to disk by the osync.
529 : : */
530 : 0 : static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
531 : : {
532 : : struct buffer_head *bh;
533 : : struct list_head *p;
534 : : int err = 0;
535 : :
536 : : spin_lock(lock);
537 : : repeat:
538 [ # # ]: 0 : list_for_each_prev(p, list) {
539 : 0 : bh = BH_ENTRY(p);
540 [ # # ]: 0 : if (buffer_locked(bh)) {
541 : : get_bh(bh);
542 : : spin_unlock(lock);
543 : : wait_on_buffer(bh);
544 [ # # ]: 0 : if (!buffer_uptodate(bh))
545 : : err = -EIO;
546 : : brelse(bh);
547 : : spin_lock(lock);
548 : : goto repeat;
549 : : }
550 : : }
551 : : spin_unlock(lock);
552 : 0 : return err;
553 : : }
554 : :
555 : 0 : static void do_thaw_one(struct super_block *sb, void *unused)
556 : : {
557 : : char b[BDEVNAME_SIZE];
558 [ # # ][ # # ]: 0 : while (sb->s_bdev && !thaw_bdev(sb->s_bdev, sb))
559 : 0 : printk(KERN_WARNING "Emergency Thaw on %s\n",
560 : : bdevname(sb->s_bdev, b));
561 : 0 : }
562 : :
563 : 0 : static void do_thaw_all(struct work_struct *work)
564 : : {
565 : 0 : iterate_supers(do_thaw_one, NULL);
566 : 0 : kfree(work);
567 : 0 : printk(KERN_WARNING "Emergency Thaw complete\n");
568 : 0 : }
569 : :
570 : : /**
571 : : * emergency_thaw_all -- forcibly thaw every frozen filesystem
572 : : *
573 : : * Used for emergency unfreeze of all filesystems via SysRq
574 : : */
575 : 0 : void emergency_thaw_all(void)
576 : : {
577 : : struct work_struct *work;
578 : :
579 : : work = kmalloc(sizeof(*work), GFP_ATOMIC);
580 [ # # ]: 0 : if (work) {
581 : 0 : INIT_WORK(work, do_thaw_all);
582 : : schedule_work(work);
583 : : }
584 : 0 : }
585 : :
586 : : /**
587 : : * sync_mapping_buffers - write out & wait upon a mapping's "associated" buffers
588 : : * @mapping: the mapping which wants those buffers written
589 : : *
590 : : * Starts I/O against the buffers at mapping->private_list, and waits upon
591 : : * that I/O.
592 : : *
593 : : * Basically, this is a convenience function for fsync().
594 : : * @mapping is a file or directory which needs those buffers to be written for
595 : : * a successful fsync().
596 : : */
597 : 0 : int sync_mapping_buffers(struct address_space *mapping)
598 : : {
599 : 0 : struct address_space *buffer_mapping = mapping->private_data;
600 : :
601 [ # # ][ # # ]: 0 : if (buffer_mapping == NULL || list_empty(&mapping->private_list))
602 : : return 0;
603 : :
604 : 0 : return fsync_buffers_list(&buffer_mapping->private_lock,
605 : : &mapping->private_list);
606 : : }
607 : : EXPORT_SYMBOL(sync_mapping_buffers);
608 : :
609 : : /*
610 : : * Called when we've recently written block `bblock', and it is known that
611 : : * `bblock' was for a buffer_boundary() buffer. This means that the block at
612 : : * `bblock + 1' is probably a dirty indirect block. Hunt it down and, if it's
613 : : * dirty, schedule it for IO. So that indirects merge nicely with their data.
614 : : */
615 : 0 : void write_boundary_block(struct block_device *bdev,
616 : : sector_t bblock, unsigned blocksize)
617 : : {
618 : 0 : struct buffer_head *bh = __find_get_block(bdev, bblock + 1, blocksize);
619 [ # # ]: 0 : if (bh) {
620 [ # # ]: 0 : if (buffer_dirty(bh))
621 : 0 : ll_rw_block(WRITE, 1, &bh);
622 : 0 : put_bh(bh);
623 : : }
624 : 0 : }
625 : :
626 : 0 : void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
627 : : {
628 : 0 : struct address_space *mapping = inode->i_mapping;
629 : 0 : struct address_space *buffer_mapping = bh->b_page->mapping;
630 : :
631 : 0 : mark_buffer_dirty(bh);
632 [ # # ]: 0 : if (!mapping->private_data) {
633 : 0 : mapping->private_data = buffer_mapping;
634 : : } else {
635 [ # # ]: 0 : BUG_ON(mapping->private_data != buffer_mapping);
636 : : }
637 [ # # ]: 0 : if (!bh->b_assoc_map) {
638 : : spin_lock(&buffer_mapping->private_lock);
639 : 0 : list_move_tail(&bh->b_assoc_buffers,
640 : : &mapping->private_list);
641 : 0 : bh->b_assoc_map = mapping;
642 : : spin_unlock(&buffer_mapping->private_lock);
643 : : }
644 : 0 : }
645 : : EXPORT_SYMBOL(mark_buffer_dirty_inode);
646 : :
647 : : /*
648 : : * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
649 : : * dirty.
650 : : *
651 : : * If warn is true, then emit a warning if the page is not uptodate and has
652 : : * not been truncated.
653 : : */
654 : 0 : static void __set_page_dirty(struct page *page,
655 : : struct address_space *mapping, int warn)
656 : : {
657 : : spin_lock_irq(&mapping->tree_lock);
658 [ + + ]: 2139281 : if (page->mapping) { /* Race with truncate? */
659 [ - + - ]: 2139268 : WARN_ON_ONCE(warn && !PageUptodate(page));
[ - + ][ # # ]
[ # # ]
660 : 2139268 : account_page_dirtied(page, mapping);
661 : 2139278 : radix_tree_tag_set(&mapping->page_tree,
662 : : page_index(page), PAGECACHE_TAG_DIRTY);
663 : : }
664 : : spin_unlock_irq(&mapping->tree_lock);
665 : 2139302 : __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
666 : 2139245 : }
667 : :
668 : : /*
669 : : * Add a page to the dirty page list.
670 : : *
671 : : * It is a sad fact of life that this function is called from several places
672 : : * deeply under spinlocking. It may not sleep.
673 : : *
674 : : * If the page has buffers, the uptodate buffers are set dirty, to preserve
675 : : * dirty-state coherency between the page and the buffers. It the page does
676 : : * not have buffers then when they are later attached they will all be set
677 : : * dirty.
678 : : *
679 : : * The buffers are dirtied before the page is dirtied. There's a small race
680 : : * window in which a writepage caller may see the page cleanness but not the
681 : : * buffer dirtiness. That's fine. If this code were to set the page dirty
682 : : * before the buffers, a concurrent writepage caller could clear the page dirty
683 : : * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
684 : : * page on the dirty page list.
685 : : *
686 : : * We use private_lock to lock against try_to_free_buffers while using the
687 : : * page's buffer list. Also use this to protect against clean buffers being
688 : : * added to the page after it was set dirty.
689 : : *
690 : : * FIXME: may need to call ->reservepage here as well. That's rather up to the
691 : : * address_space though.
692 : : */
693 : 0 : int __set_page_dirty_buffers(struct page *page)
694 : : {
695 : : int newly_dirty;
696 : 792976 : struct address_space *mapping = page_mapping(page);
697 : :
698 [ - + ]: 793047 : if (unlikely(!mapping))
699 : 0 : return !TestSetPageDirty(page);
700 : :
701 : : spin_lock(&mapping->private_lock);
702 [ + - ]: 793082 : if (page_has_buffers(page)) {
703 [ - + ]: 793082 : struct buffer_head *head = page_buffers(page);
704 : : struct buffer_head *bh = head;
705 : :
706 : : do {
707 : : set_buffer_dirty(bh);
708 : 793082 : bh = bh->b_this_page;
709 [ - + ]: 793082 : } while (bh != head);
710 : : }
711 : 793082 : newly_dirty = !TestSetPageDirty(page);
712 : : spin_unlock(&mapping->private_lock);
713 : :
714 [ - + ]: 793082 : if (newly_dirty)
715 : 0 : __set_page_dirty(page, mapping, 1);
716 : 793082 : return newly_dirty;
717 : : }
718 : : EXPORT_SYMBOL(__set_page_dirty_buffers);
719 : :
720 : : /*
721 : : * Write out and wait upon a list of buffers.
722 : : *
723 : : * We have conflicting pressures: we want to make sure that all
724 : : * initially dirty buffers get waited on, but that any subsequently
725 : : * dirtied buffers don't. After all, we don't want fsync to last
726 : : * forever if somebody is actively writing to the file.
727 : : *
728 : : * Do this in two main stages: first we copy dirty buffers to a
729 : : * temporary inode list, queueing the writes as we go. Then we clean
730 : : * up, waiting for those writes to complete.
731 : : *
732 : : * During this second stage, any subsequent updates to the file may end
733 : : * up refiling the buffer on the original inode's dirty list again, so
734 : : * there is a chance we will end up with a buffer queued for write but
735 : : * not yet completed on that list. So, as a final cleanup we go through
736 : : * the osync code to catch these locked, dirty buffers without requeuing
737 : : * any newly dirty buffers for write.
738 : : */
739 : 0 : static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
740 : : {
741 : : struct buffer_head *bh;
742 : : struct list_head tmp;
743 : : struct address_space *mapping;
744 : : int err = 0, err2;
745 : : struct blk_plug plug;
746 : :
747 : : INIT_LIST_HEAD(&tmp);
748 : 0 : blk_start_plug(&plug);
749 : :
750 : : spin_lock(lock);
751 [ # # ]: 0 : while (!list_empty(list)) {
752 : 0 : bh = BH_ENTRY(list->next);
753 : 0 : mapping = bh->b_assoc_map;
754 : 0 : __remove_assoc_queue(bh);
755 : : /* Avoid race with mark_buffer_dirty_inode() which does
756 : : * a lockless check and we rely on seeing the dirty bit */
757 : 0 : smp_mb();
758 [ # # ][ # # ]: 0 : if (buffer_dirty(bh) || buffer_locked(bh)) {
759 : 0 : list_add(&bh->b_assoc_buffers, &tmp);
760 : 0 : bh->b_assoc_map = mapping;
761 [ # # ]: 0 : if (buffer_dirty(bh)) {
762 : : get_bh(bh);
763 : : spin_unlock(lock);
764 : : /*
765 : : * Ensure any pending I/O completes so that
766 : : * write_dirty_buffer() actually writes the
767 : : * current contents - it is a noop if I/O is
768 : : * still in flight on potentially older
769 : : * contents.
770 : : */
771 : 0 : write_dirty_buffer(bh, WRITE_SYNC);
772 : :
773 : : /*
774 : : * Kick off IO for the previous mapping. Note
775 : : * that we will not run the very last mapping,
776 : : * wait_on_buffer() will do that for us
777 : : * through sync_buffer().
778 : : */
779 : : brelse(bh);
780 : : spin_lock(lock);
781 : : }
782 : : }
783 : : }
784 : :
785 : : spin_unlock(lock);
786 : 0 : blk_finish_plug(&plug);
787 : : spin_lock(lock);
788 : :
789 [ # # ]: 0 : while (!list_empty(&tmp)) {
790 : 0 : bh = BH_ENTRY(tmp.prev);
791 : : get_bh(bh);
792 : 0 : mapping = bh->b_assoc_map;
793 : 0 : __remove_assoc_queue(bh);
794 : : /* Avoid race with mark_buffer_dirty_inode() which does
795 : : * a lockless check and we rely on seeing the dirty bit */
796 : 0 : smp_mb();
797 [ # # ]: 0 : if (buffer_dirty(bh)) {
798 : 0 : list_add(&bh->b_assoc_buffers,
799 : : &mapping->private_list);
800 : 0 : bh->b_assoc_map = mapping;
801 : : }
802 : : spin_unlock(lock);
803 : : wait_on_buffer(bh);
804 [ # # ]: 0 : if (!buffer_uptodate(bh))
805 : : err = -EIO;
806 : : brelse(bh);
807 : : spin_lock(lock);
808 : : }
809 : :
810 : : spin_unlock(lock);
811 : 0 : err2 = osync_buffers_list(lock, list);
812 [ # # ]: 0 : if (err)
813 : : return err;
814 : : else
815 : 0 : return err2;
816 : : }
817 : :
818 : : /*
819 : : * Invalidate any and all dirty buffers on a given inode. We are
820 : : * probably unmounting the fs, but that doesn't mean we have already
821 : : * done a sync(). Just drop the buffers from the inode list.
822 : : *
823 : : * NOTE: we take the inode's blockdev's mapping's private_lock. Which
824 : : * assumes that all the buffers are against the blockdev. Not true
825 : : * for reiserfs.
826 : : */
827 : 0 : void invalidate_inode_buffers(struct inode *inode)
828 : : {
829 [ - + ]: 476186 : if (inode_has_buffers(inode)) {
830 : : struct address_space *mapping = &inode->i_data;
831 : : struct list_head *list = &mapping->private_list;
832 : 0 : struct address_space *buffer_mapping = mapping->private_data;
833 : :
834 : : spin_lock(&buffer_mapping->private_lock);
835 [ # # ]: 0 : while (!list_empty(list))
836 : 0 : __remove_assoc_queue(BH_ENTRY(list->next));
837 : : spin_unlock(&buffer_mapping->private_lock);
838 : : }
839 : 0 : }
840 : : EXPORT_SYMBOL(invalidate_inode_buffers);
841 : :
842 : : /*
843 : : * Remove any clean buffers from the inode's buffer list. This is called
844 : : * when we're trying to free the inode itself. Those buffers can pin it.
845 : : *
846 : : * Returns true if all buffers were removed.
847 : : */
848 : 0 : int remove_inode_buffers(struct inode *inode)
849 : : {
850 : : int ret = 1;
851 : :
852 [ - + ]: 36 : if (inode_has_buffers(inode)) {
853 : : struct address_space *mapping = &inode->i_data;
854 : : struct list_head *list = &mapping->private_list;
855 : 0 : struct address_space *buffer_mapping = mapping->private_data;
856 : :
857 : : spin_lock(&buffer_mapping->private_lock);
858 [ # # ]: 0 : while (!list_empty(list)) {
859 : 0 : struct buffer_head *bh = BH_ENTRY(list->next);
860 [ # # ]: 0 : if (buffer_dirty(bh)) {
861 : : ret = 0;
862 : : break;
863 : : }
864 : 0 : __remove_assoc_queue(bh);
865 : : }
866 : : spin_unlock(&buffer_mapping->private_lock);
867 : : }
868 : 36 : return ret;
869 : : }
870 : :
871 : : /*
872 : : * Create the appropriate buffers when given a page for data area and
873 : : * the size of each buffer.. Use the bh->b_this_page linked list to
874 : : * follow the buffers created. Return NULL if unable to create more
875 : : * buffers.
876 : : *
877 : : * The retry flag is used to differentiate async IO (paging, swapping)
878 : : * which may not fail from ordinary buffer allocations.
879 : : */
880 : 1898705 : struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
881 : : int retry)
882 : : {
883 : : struct buffer_head *bh, *head;
884 : : long offset;
885 : :
886 : : try_again:
887 : : head = NULL;
888 : : offset = PAGE_SIZE;
889 [ + + ]: 3797504 : while ((offset -= size) >= 0) {
890 : 1898800 : bh = alloc_buffer_head(GFP_NOFS);
891 [ + - ]: 1898704 : if (!bh)
892 : : goto no_grow;
893 : :
894 : 1898704 : bh->b_this_page = head;
895 : 1898704 : bh->b_blocknr = -1;
896 : : head = bh;
897 : :
898 : 1898704 : bh->b_size = size;
899 : :
900 : : /* Link the buffer to its page */
901 : 1898704 : set_bh_page(bh, page, offset);
902 : : }
903 : : return head;
904 : : /*
905 : : * In case anything failed, we just free everything we got.
906 : : */
907 : : no_grow:
908 [ # # ]: 0 : if (head) {
909 : : do {
910 : : bh = head;
911 : 0 : head = head->b_this_page;
912 : 0 : free_buffer_head(bh);
913 [ # # ]: 0 : } while (head);
914 : : }
915 : :
916 : : /*
917 : : * Return failure for non-async IO requests. Async IO requests
918 : : * are not allowed to fail, so we have to wait until buffer heads
919 : : * become available. But we don't want tasks sleeping with
920 : : * partially complete buffers, so all were released above.
921 : : */
922 [ # # ]: 0 : if (!retry)
923 : : return NULL;
924 : :
925 : : /* We're _really_ low on memory. Now we just
926 : : * wait for old buffer heads to become free due to
927 : : * finishing IO. Since this is an async request and
928 : : * the reserve list is empty, we're sure there are
929 : : * async buffer heads in use.
930 : : */
931 : 0 : free_more_memory();
932 : 0 : goto try_again;
933 : : }
934 : : EXPORT_SYMBOL_GPL(alloc_page_buffers);
935 : :
936 : : static inline void
937 : : link_dev_buffers(struct page *page, struct buffer_head *head)
938 : : {
939 : : struct buffer_head *bh, *tail;
940 : :
941 : : bh = head;
942 : : do {
943 : : tail = bh;
944 : 59594 : bh = bh->b_this_page;
945 [ - + ]: 59594 : } while (bh);
946 : 59594 : tail->b_this_page = head;
947 : : attach_page_buffers(page, head);
948 : : }
949 : :
950 : 0 : static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
951 : : {
952 : : sector_t retval = ~((sector_t)0);
953 : 59596 : loff_t sz = i_size_read(bdev->bd_inode);
954 : :
955 [ + ]: 59596 : if (sz) {
956 : : unsigned int sizebits = blksize_bits(size);
957 : 59596 : retval = (sz >> sizebits);
958 : : }
959 : 0 : return retval;
960 : : }
961 : :
962 : : /*
963 : : * Initialise the state of a blockdev page's buffers.
964 : : */
965 : : static sector_t
966 : 0 : init_page_buffers(struct page *page, struct block_device *bdev,
967 : : sector_t block, int size)
968 : : {
969 [ - + ]: 59596 : struct buffer_head *head = page_buffers(page);
970 : : struct buffer_head *bh = head;
971 : : int uptodate = PageUptodate(page);
972 : 59596 : sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size);
973 : :
974 : : do {
975 [ + + ]: 119192 : if (!buffer_mapped(bh)) {
976 : : init_buffer(bh, NULL, NULL);
977 : 59594 : bh->b_bdev = bdev;
978 : 59594 : bh->b_blocknr = block;
979 [ - + ]: 59594 : if (uptodate)
980 : : set_buffer_uptodate(bh);
981 [ + - ]: 59594 : if (block < end_block)
982 : : set_buffer_mapped(bh);
983 : : }
984 : 59596 : block++;
985 : 59596 : bh = bh->b_this_page;
986 [ - + ]: 59596 : } while (bh != head);
987 : :
988 : : /*
989 : : * Caller needs to validate requested block against end of device.
990 : : */
991 : 59596 : return end_block;
992 : : }
993 : :
994 : : /*
995 : : * Create the page-cache page that contains the requested block.
996 : : *
997 : : * This is used purely for blockdev mappings.
998 : : */
999 : : static int
1000 : 0 : grow_dev_page(struct block_device *bdev, sector_t block,
1001 : : pgoff_t index, int size, int sizebits)
1002 : : {
1003 : 59596 : struct inode *inode = bdev->bd_inode;
1004 : : struct page *page;
1005 : : struct buffer_head *bh;
1006 : : sector_t end_block;
1007 : : int ret = 0; /* Will call free_more_memory() */
1008 : : gfp_t gfp_mask;
1009 : :
1010 : 119192 : gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS;
1011 : : gfp_mask |= __GFP_MOVABLE;
1012 : : /*
1013 : : * XXX: __getblk_slow() can not really deal with failure and
1014 : : * will endlessly loop on improvised global reclaim. Prefer
1015 : : * looping in the allocator rather than here, at least that
1016 : : * code knows what it's doing.
1017 : : */
1018 : 59596 : gfp_mask |= __GFP_NOFAIL;
1019 : :
1020 : 59596 : page = find_or_create_page(inode->i_mapping, index, gfp_mask);
1021 [ + - ]: 59596 : if (!page)
1022 : : return ret;
1023 : :
1024 [ - + ]: 59596 : BUG_ON(!PageLocked(page));
1025 : :
1026 [ + + ]: 59596 : if (page_has_buffers(page)) {
1027 [ - + ]: 2 : bh = page_buffers(page);
1028 [ + - ]: 2 : if (bh->b_size == size) {
1029 : 2 : end_block = init_page_buffers(page, bdev,
1030 : 2 : index << sizebits, size);
1031 : 2 : goto done;
1032 : : }
1033 [ # # ]: 0 : if (!try_to_free_buffers(page))
1034 : : goto failed;
1035 : : }
1036 : :
1037 : : /*
1038 : : * Allocate some buffers for this page
1039 : : */
1040 : 59594 : bh = alloc_page_buffers(page, size, 0);
1041 [ + ]: 59593 : if (!bh)
1042 : : goto failed;
1043 : :
1044 : : /*
1045 : : * Link the page to the buffers and initialise them. Take the
1046 : : * lock to be atomic wrt __find_get_block(), which does not
1047 : : * run under the page lock.
1048 : : */
1049 : 59594 : spin_lock(&inode->i_mapping->private_lock);
1050 : : link_dev_buffers(page, bh);
1051 : 59594 : end_block = init_page_buffers(page, bdev, index << sizebits, size);
1052 : 59594 : spin_unlock(&inode->i_mapping->private_lock);
1053 : : done:
1054 [ - + ]: 59596 : ret = (block < end_block) ? 1 : -ENXIO;
1055 : : failed:
1056 : 59595 : unlock_page(page);
1057 : 59596 : page_cache_release(page);
1058 : 59596 : return ret;
1059 : : }
1060 : :
1061 : : /*
1062 : : * Create buffers for the specified block device block's page. If
1063 : : * that page was dirty, the buffers are set dirty also.
1064 : : */
1065 : : static int
1066 : 59596 : grow_buffers(struct block_device *bdev, sector_t block, int size)
1067 : : {
1068 : : pgoff_t index;
1069 : : int sizebits;
1070 : :
1071 : : sizebits = -1;
1072 : : do {
1073 : 59596 : sizebits++;
1074 [ - + ]: 59596 : } while ((size << sizebits) < PAGE_SIZE);
1075 : :
1076 : 59596 : index = block >> sizebits;
1077 : :
1078 : : /*
1079 : : * Check for a block which wants to lie outside our maximum possible
1080 : : * pagecache index. (this comparison is done using sector_t types).
1081 : : */
1082 [ - + ]: 59596 : if (unlikely(index != block >> sizebits)) {
1083 : : char b[BDEVNAME_SIZE];
1084 : :
1085 : 0 : printk(KERN_ERR "%s: requested out-of-range block %llu for "
1086 : : "device %s\n",
1087 : : __func__, (unsigned long long)block,
1088 : : bdevname(bdev, b));
1089 : : return -EIO;
1090 : : }
1091 : :
1092 : : /* Create a page with the proper size buffers.. */
1093 : 59596 : return grow_dev_page(bdev, block, index, size, sizebits);
1094 : : }
1095 : :
1096 : : static struct buffer_head *
1097 : 0 : __getblk_slow(struct block_device *bdev, sector_t block, int size)
1098 : : {
1099 : : /* Size must be multiple of hard sectorsize */
1100 [ + - ][ + - ]: 59600 : if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
1101 : : (size < 512 || size > PAGE_SIZE))) {
1102 : 0 : printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1103 : : size);
1104 : 0 : printk(KERN_ERR "logical block size: %d\n",
1105 : : bdev_logical_block_size(bdev));
1106 : :
1107 : 59600 : dump_stack();
1108 : 0 : return NULL;
1109 : : }
1110 : :
1111 : : for (;;) {
1112 : : struct buffer_head *bh;
1113 : : int ret;
1114 : :
1115 : 119196 : bh = __find_get_block(bdev, block, size);
1116 [ + + ]: 119193 : if (bh)
1117 : : return bh;
1118 : :
1119 : 59596 : ret = grow_buffers(bdev, block, size);
1120 [ + - ]: 59596 : if (ret < 0)
1121 : : return NULL;
1122 [ + - ]: 59596 : if (ret == 0)
1123 : 0 : free_more_memory();
1124 : : }
1125 : : }
1126 : :
1127 : : /*
1128 : : * The relationship between dirty buffers and dirty pages:
1129 : : *
1130 : : * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1131 : : * the page is tagged dirty in its radix tree.
1132 : : *
1133 : : * At all times, the dirtiness of the buffers represents the dirtiness of
1134 : : * subsections of the page. If the page has buffers, the page dirty bit is
1135 : : * merely a hint about the true dirty state.
1136 : : *
1137 : : * When a page is set dirty in its entirety, all its buffers are marked dirty
1138 : : * (if the page has buffers).
1139 : : *
1140 : : * When a buffer is marked dirty, its page is dirtied, but the page's other
1141 : : * buffers are not.
1142 : : *
1143 : : * Also. When blockdev buffers are explicitly read with bread(), they
1144 : : * individually become uptodate. But their backing page remains not
1145 : : * uptodate - even if all of its buffers are uptodate. A subsequent
1146 : : * block_read_full_page() against that page will discover all the uptodate
1147 : : * buffers, will set the page uptodate and will perform no I/O.
1148 : : */
1149 : :
1150 : : /**
1151 : : * mark_buffer_dirty - mark a buffer_head as needing writeout
1152 : : * @bh: the buffer_head to mark dirty
1153 : : *
1154 : : * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1155 : : * backing page dirty, then tag the page as dirty in its address_space's radix
1156 : : * tree and then attach the address_space's inode to its superblock's dirty
1157 : : * inode list.
1158 : : *
1159 : : * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1160 : : * mapping->tree_lock and mapping->host->i_lock.
1161 : : */
1162 : 0 : void mark_buffer_dirty(struct buffer_head *bh)
1163 : : {
1164 [ - + ][ # # ]: 7417513 : WARN_ON_ONCE(!buffer_uptodate(bh));
[ - ]
1165 : :
1166 : : trace_block_dirty_buffer(bh);
1167 : :
1168 : : /*
1169 : : * Very *carefully* optimize the it-is-already-dirty case.
1170 : : *
1171 : : * Don't let the final "is it dirty" escape to before we
1172 : : * perhaps modified the buffer.
1173 : : */
1174 [ + + ]: 7417484 : if (buffer_dirty(bh)) {
1175 : 5243819 : smp_mb();
1176 [ - + ]: 5243925 : if (buffer_dirty(bh))
1177 : 7417631 : return;
1178 : : }
1179 : :
1180 [ + ]: 2173631 : if (!test_set_buffer_dirty(bh)) {
1181 : 2173666 : struct page *page = bh->b_page;
1182 [ + + ]: 2173725 : if (!TestSetPageDirty(page)) {
1183 : 2139194 : struct address_space *mapping = page_mapping(page);
1184 [ + ]: 2139182 : if (mapping)
1185 : 2139237 : __set_page_dirty(page, mapping, 0);
1186 : : }
1187 : : }
1188 : : }
1189 : : EXPORT_SYMBOL(mark_buffer_dirty);
1190 : :
1191 : : /*
1192 : : * Decrement a buffer_head's reference count. If all buffers against a page
1193 : : * have zero reference count, are clean and unlocked, and if the page is clean
1194 : : * and unlocked then try_to_free_buffers() may strip the buffers from the page
1195 : : * in preparation for freeing it (sometimes, rarely, buffers are removed from
1196 : : * a page but it ends up not being freed, and buffers may later be reattached).
1197 : : */
1198 : 0 : void __brelse(struct buffer_head * buf)
1199 : : {
1200 [ + - ]: 14908091 : if (atomic_read(&buf->b_count)) {
1201 : : put_bh(buf);
1202 : 14909217 : return;
1203 : : }
1204 : 0 : WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
1205 : : }
1206 : : EXPORT_SYMBOL(__brelse);
1207 : :
1208 : : /*
1209 : : * bforget() is like brelse(), except it discards any
1210 : : * potentially dirty data.
1211 : : */
1212 : 0 : void __bforget(struct buffer_head *bh)
1213 : : {
1214 : : clear_buffer_dirty(bh);
1215 [ - + ]: 38767 : if (bh->b_assoc_map) {
1216 : 0 : struct address_space *buffer_mapping = bh->b_page->mapping;
1217 : :
1218 : : spin_lock(&buffer_mapping->private_lock);
1219 : 0 : list_del_init(&bh->b_assoc_buffers);
1220 : 0 : bh->b_assoc_map = NULL;
1221 : : spin_unlock(&buffer_mapping->private_lock);
1222 : : }
1223 : 38767 : __brelse(bh);
1224 : 38767 : }
1225 : : EXPORT_SYMBOL(__bforget);
1226 : :
1227 : 0 : static struct buffer_head *__bread_slow(struct buffer_head *bh)
1228 : : {
1229 : : lock_buffer(bh);
1230 [ # # ]: 0 : if (buffer_uptodate(bh)) {
1231 : 0 : unlock_buffer(bh);
1232 : 0 : return bh;
1233 : : } else {
1234 : : get_bh(bh);
1235 : 0 : bh->b_end_io = end_buffer_read_sync;
1236 : : submit_bh(READ, bh);
1237 : : wait_on_buffer(bh);
1238 [ # # ]: 0 : if (buffer_uptodate(bh))
1239 : : return bh;
1240 : : }
1241 : : brelse(bh);
1242 : : return NULL;
1243 : : }
1244 : :
1245 : : /*
1246 : : * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1247 : : * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1248 : : * refcount elevated by one when they're in an LRU. A buffer can only appear
1249 : : * once in a particular CPU's LRU. A single buffer can be present in multiple
1250 : : * CPU's LRUs at the same time.
1251 : : *
1252 : : * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1253 : : * sb_find_get_block().
1254 : : *
1255 : : * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1256 : : * a local interrupt disable for that.
1257 : : */
1258 : :
1259 : : #define BH_LRU_SIZE 8
1260 : :
1261 : : struct bh_lru {
1262 : : struct buffer_head *bhs[BH_LRU_SIZE];
1263 : : };
1264 : :
1265 : : static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1266 : :
1267 : : #ifdef CONFIG_SMP
1268 : : #define bh_lru_lock() local_irq_disable()
1269 : : #define bh_lru_unlock() local_irq_enable()
1270 : : #else
1271 : : #define bh_lru_lock() preempt_disable()
1272 : : #define bh_lru_unlock() preempt_enable()
1273 : : #endif
1274 : :
1275 : : static inline void check_irqs_on(void)
1276 : : {
1277 : : #ifdef irqs_disabled
1278 [ - + ][ - + ]: 14791397 : BUG_ON(irqs_disabled());
1279 : : #endif
1280 : : }
1281 : :
1282 : : /*
1283 : : * The LRU management algorithm is dopey-but-simple. Sorry.
1284 : : */
1285 : 0 : static void bh_lru_install(struct buffer_head *bh)
1286 : : {
1287 : : struct buffer_head *evictee = NULL;
1288 : :
1289 : : check_irqs_on();
1290 : : bh_lru_lock();
1291 [ + - ]: 304124 : if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
1292 : : struct buffer_head *bhs[BH_LRU_SIZE];
1293 : : int in;
1294 : : int out = 0;
1295 : :
1296 : : get_bh(bh);
1297 : 608228 : bhs[out++] = bh;
1298 [ + + ]: 3041139 : for (in = 0; in < BH_LRU_SIZE; in++) {
1299 : : struct buffer_head *bh2 =
1300 : 4865784 : __this_cpu_read(bh_lrus.bhs[in]);
1301 : :
1302 [ + ]: 2432892 : if (bh2 == bh) {
1303 : 0 : __brelse(bh2);
1304 : : } else {
1305 [ + + ]: 2432929 : if (out >= BH_LRU_SIZE) {
1306 [ - + ]: 304120 : BUG_ON(evictee != NULL);
1307 : : evictee = bh2;
1308 : : } else {
1309 : 2128809 : bhs[out++] = bh2;
1310 : : }
1311 : : }
1312 : : }
1313 [ - + ]: 304123 : while (out < BH_LRU_SIZE)
1314 : 0 : bhs[out++] = NULL;
1315 : 304123 : memcpy(__this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
1316 : : }
1317 : : bh_lru_unlock();
1318 : :
1319 [ + + ]: 304122 : if (evictee)
1320 : 304121 : __brelse(evictee);
1321 : 304121 : }
1322 : :
1323 : : /*
1324 : : * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1325 : : */
1326 : : static struct buffer_head *
1327 : 0 : lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
1328 : : {
1329 : : struct buffer_head *ret = NULL;
1330 : : unsigned int i;
1331 : :
1332 : : check_irqs_on();
1333 : : bh_lru_lock();
1334 [ + + ]: 28177880 : for (i = 0; i < BH_LRU_SIZE; i++) {
1335 : 55476052 : struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
1336 : :
1337 [ + ][ + ]: 27738026 : if (bh && bh->b_bdev == bdev &&
[ + + ]
1338 [ + + ]: 14050890 : bh->b_blocknr == block && bh->b_size == size) {
1339 [ + + ]: 14046824 : if (i) {
1340 [ + + ]: 15268232 : while (i) {
1341 : 10199095 : __this_cpu_write(bh_lrus.bhs[i],
1342 : : __this_cpu_read(bh_lrus.bhs[i - 1]));
1343 : : i--;
1344 : : }
1345 : 5069137 : __this_cpu_write(bh_lrus.bhs[0], bh);
1346 : : }
1347 : : get_bh(bh);
1348 : : ret = bh;
1349 : 14050886 : break;
1350 : : }
1351 : : }
1352 : : bh_lru_unlock();
1353 : 14487202 : return ret;
1354 : : }
1355 : :
1356 : : /*
1357 : : * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1358 : : * it in the LRU and mark it as accessed. If it is not present then return
1359 : : * NULL
1360 : : */
1361 : : struct buffer_head *
1362 : 0 : __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
1363 : : {
1364 : 14486755 : struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1365 : :
1366 [ + + ]: 14487457 : if (bh == NULL) {
1367 : 436667 : bh = __find_get_block_slow(bdev, block);
1368 [ + + ]: 436672 : if (bh)
1369 : 304124 : bh_lru_install(bh);
1370 : : }
1371 [ + + ]: 14487546 : if (bh)
1372 : : touch_buffer(bh);
1373 : 14487315 : return bh;
1374 : : }
1375 : : EXPORT_SYMBOL(__find_get_block);
1376 : :
1377 : : /*
1378 : : * __getblk will locate (and, if necessary, create) the buffer_head
1379 : : * which corresponds to the passed block_device, block and size. The
1380 : : * returned buffer has its reference count incremented.
1381 : : *
1382 : : * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1383 : : * attempt is failing. FIXME, perhaps?
1384 : : */
1385 : : struct buffer_head *
1386 : 0 : __getblk(struct block_device *bdev, sector_t block, unsigned size)
1387 : : {
1388 : 14243303 : struct buffer_head *bh = __find_get_block(bdev, block, size);
1389 : :
1390 : : might_sleep();
1391 [ + + ]: 14243949 : if (bh == NULL)
1392 : 59600 : bh = __getblk_slow(bdev, block, size);
1393 : 646 : return bh;
1394 : : }
1395 : : EXPORT_SYMBOL(__getblk);
1396 : :
1397 : : /*
1398 : : * Do async read-ahead on a buffer..
1399 : : */
1400 : 0 : void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
1401 : : {
1402 : 5128 : struct buffer_head *bh = __getblk(bdev, block, size);
1403 [ + - ]: 5129 : if (likely(bh)) {
1404 : 5129 : ll_rw_block(READA, 1, &bh);
1405 : 5128 : brelse(bh);
1406 : : }
1407 : 1 : }
1408 : : EXPORT_SYMBOL(__breadahead);
1409 : :
1410 : : /**
1411 : : * __bread() - reads a specified block and returns the bh
1412 : : * @bdev: the block_device to read from
1413 : : * @block: number of block
1414 : : * @size: size (in bytes) to read
1415 : : *
1416 : : * Reads a specified block, and returns buffer head that contains it.
1417 : : * It returns NULL if the block was unreadable.
1418 : : */
1419 : : struct buffer_head *
1420 : 0 : __bread(struct block_device *bdev, sector_t block, unsigned size)
1421 : : {
1422 : 0 : struct buffer_head *bh = __getblk(bdev, block, size);
1423 : :
1424 [ # # ][ # # ]: 0 : if (likely(bh) && !buffer_uptodate(bh))
1425 : 0 : bh = __bread_slow(bh);
1426 : 0 : return bh;
1427 : : }
1428 : : EXPORT_SYMBOL(__bread);
1429 : :
1430 : : /*
1431 : : * invalidate_bh_lrus() is called rarely - but not only at unmount.
1432 : : * This doesn't race because it runs in each cpu either in irq
1433 : : * or with preempt disabled.
1434 : : */
1435 : 0 : static void invalidate_bh_lru(void *arg)
1436 : : {
1437 : 0 : struct bh_lru *b = &get_cpu_var(bh_lrus);
1438 : : int i;
1439 : :
1440 [ # # ]: 0 : for (i = 0; i < BH_LRU_SIZE; i++) {
1441 : 0 : brelse(b->bhs[i]);
1442 : 0 : b->bhs[i] = NULL;
1443 : : }
1444 : 0 : put_cpu_var(bh_lrus);
1445 : 0 : }
1446 : :
1447 : 0 : static bool has_bh_in_lru(int cpu, void *dummy)
1448 : : {
1449 : 0 : struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1450 : : int i;
1451 : :
1452 [ # # ]: 0 : for (i = 0; i < BH_LRU_SIZE; i++) {
1453 [ # # ]: 0 : if (b->bhs[i])
1454 : : return 1;
1455 : : }
1456 : :
1457 : : return 0;
1458 : : }
1459 : :
1460 : 0 : void invalidate_bh_lrus(void)
1461 : : {
1462 : 0 : on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
1463 : 0 : }
1464 : : EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
1465 : :
1466 : 0 : void set_bh_page(struct buffer_head *bh,
1467 : : struct page *page, unsigned long offset)
1468 : : {
1469 : 1969148 : bh->b_page = page;
1470 [ - + ]: 1969148 : BUG_ON(offset >= PAGE_SIZE);
1471 [ + + ]: 1969148 : if (PageHighMem(page))
1472 : : /*
1473 : : * This catches illegal uses and preserves the offset:
1474 : : */
1475 : 1262652 : bh->b_data = (char *)(0 + offset);
1476 : : else
1477 : 706496 : bh->b_data = page_address(page) + offset;
1478 : 1969164 : }
1479 : : EXPORT_SYMBOL(set_bh_page);
1480 : :
1481 : : /*
1482 : : * Called when truncating a buffer on a page completely.
1483 : : */
1484 : 0 : static void discard_buffer(struct buffer_head * bh)
1485 : : {
1486 : : lock_buffer(bh);
1487 : : clear_buffer_dirty(bh);
1488 : 1698953 : bh->b_bdev = NULL;
1489 : : clear_buffer_mapped(bh);
1490 : : clear_buffer_req(bh);
1491 : : clear_buffer_new(bh);
1492 : : clear_buffer_delay(bh);
1493 : : clear_buffer_unwritten(bh);
1494 : 1698952 : unlock_buffer(bh);
1495 : 1698946 : }
1496 : :
1497 : : /**
1498 : : * block_invalidatepage - invalidate part or all of a buffer-backed page
1499 : : *
1500 : : * @page: the page which is affected
1501 : : * @offset: start of the range to invalidate
1502 : : * @length: length of the range to invalidate
1503 : : *
1504 : : * block_invalidatepage() is called when all or part of the page has become
1505 : : * invalidated by a truncate operation.
1506 : : *
1507 : : * block_invalidatepage() does not have to release all buffers, but it must
1508 : : * ensure that no dirty buffer is left outside @offset and that no I/O
1509 : : * is underway against any of the blocks which are outside the truncation
1510 : : * point. Because the caller is about to free (and possibly reuse) those
1511 : : * blocks on-disk.
1512 : : */
1513 : 0 : void block_invalidatepage(struct page *page, unsigned int offset,
1514 : : unsigned int length)
1515 : : {
1516 : : struct buffer_head *head, *bh, *next;
1517 : : unsigned int curr_off = 0;
1518 : 1713931 : unsigned int stop = length + offset;
1519 : :
1520 [ - + ]: 1713931 : BUG_ON(!PageLocked(page));
1521 [ + ]: 1713931 : if (!page_has_buffers(page))
1522 : : goto out;
1523 : :
1524 : : /*
1525 : : * Check for overflow
1526 : : */
1527 [ - + ]: 3427875 : BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
1528 : :
1529 [ - + ]: 1713944 : head = page_buffers(page);
1530 : : bh = head;
1531 : : do {
1532 : 1713944 : unsigned int next_off = curr_off + bh->b_size;
1533 : 1713944 : next = bh->b_this_page;
1534 : :
1535 : : /*
1536 : : * Are we still fully in range ?
1537 : : */
1538 [ + ]: 1713944 : if (next_off > stop)
1539 : : goto out;
1540 : :
1541 : : /*
1542 : : * is this block fully invalidated?
1543 : : */
1544 [ + + ]: 1713946 : if (offset <= curr_off)
1545 : 1698946 : discard_buffer(bh);
1546 : : curr_off = next_off;
1547 : : bh = next;
1548 [ - + ]: 1713947 : } while (bh != head);
1549 : :
1550 : : /*
1551 : : * We release buffers only if the entire page is being invalidated.
1552 : : * The get_block cached value has been unconditionally invalidated,
1553 : : * so real IO is not possible anymore.
1554 : : */
1555 [ + + ]: 1713947 : if (offset == 0)
1556 : 1698950 : try_to_release_page(page, 0);
1557 : : out:
1558 : 0 : return;
1559 : : }
1560 : : EXPORT_SYMBOL(block_invalidatepage);
1561 : :
1562 : :
1563 : : /*
1564 : : * We attach and possibly dirty the buffers atomically wrt
1565 : : * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1566 : : * is already excluded via the page lock.
1567 : : */
1568 : 0 : void create_empty_buffers(struct page *page,
1569 : : unsigned long blocksize, unsigned long b_state)
1570 : : {
1571 : : struct buffer_head *bh, *head, *tail;
1572 : :
1573 : 1839210 : head = alloc_page_buffers(page, blocksize, 1);
1574 : : bh = head;
1575 : : do {
1576 : 1839196 : bh->b_state |= b_state;
1577 : : tail = bh;
1578 : 1839196 : bh = bh->b_this_page;
1579 [ - + ]: 1839196 : } while (bh);
1580 : 1839196 : tail->b_this_page = head;
1581 : :
1582 : 1839196 : spin_lock(&page->mapping->private_lock);
1583 [ + + ][ + + ]: 1839191 : if (PageUptodate(page) || PageDirty(page)) {
1584 : : bh = head;
1585 : : do {
1586 [ - + ]: 157225 : if (PageDirty(page))
1587 : : set_buffer_dirty(bh);
1588 [ + + ]: 157233 : if (PageUptodate(page))
1589 : : set_buffer_uptodate(bh);
1590 : 157177 : bh = bh->b_this_page;
1591 [ - + ]: 157177 : } while (bh != head);
1592 : : }
1593 : : attach_page_buffers(page, head);
1594 : 1839165 : spin_unlock(&page->mapping->private_lock);
1595 : 1839203 : }
1596 : : EXPORT_SYMBOL(create_empty_buffers);
1597 : :
1598 : : /*
1599 : : * We are taking a block for data and we don't want any output from any
1600 : : * buffer-cache aliases starting from return from that function and
1601 : : * until the moment when something will explicitly mark the buffer
1602 : : * dirty (hopefully that will not happen until we will free that block ;-)
1603 : : * We don't even need to mark it not-uptodate - nobody can expect
1604 : : * anything from a newly allocated buffer anyway. We used to used
1605 : : * unmap_buffer() for such invalidation, but that was wrong. We definitely
1606 : : * don't want to mark the alias unmapped, for example - it would confuse
1607 : : * anyone who might pick it with bread() afterwards...
1608 : : *
1609 : : * Also.. Note that bforget() doesn't lock the buffer. So there can
1610 : : * be writeout I/O going on against recently-freed buffers. We don't
1611 : : * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1612 : : * only if we really need to. That happens here.
1613 : : */
1614 : 0 : void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1615 : : {
1616 : : struct buffer_head *old_bh;
1617 : :
1618 : : might_sleep();
1619 : :
1620 : 2621665 : old_bh = __find_get_block_slow(bdev, block);
1621 [ + + ]: 2621671 : if (old_bh) {
1622 : : clear_buffer_dirty(old_bh);
1623 : : wait_on_buffer(old_bh);
1624 : : clear_buffer_req(old_bh);
1625 : 1957 : __brelse(old_bh);
1626 : : }
1627 : 2621671 : }
1628 : : EXPORT_SYMBOL(unmap_underlying_metadata);
1629 : :
1630 : : /*
1631 : : * Size is a power-of-two in the range 512..PAGE_SIZE,
1632 : : * and the case we care about most is PAGE_SIZE.
1633 : : *
1634 : : * So this *could* possibly be written with those
1635 : : * constraints in mind (relevant mostly if some
1636 : : * architecture has a slow bit-scan instruction)
1637 : : */
1638 : : static inline int block_size_bits(unsigned int blocksize)
1639 : : {
1640 [ - + ][ # # ]: 14423524 : return ilog2(blocksize);
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1641 : : }
1642 : :
1643 : 0 : static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
1644 : : {
1645 [ - + ]: 7212009 : BUG_ON(!PageLocked(page));
1646 : :
1647 [ + + ]: 7212009 : if (!page_has_buffers(page))
1648 : 1833648 : create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
1649 [ - + ]: 7211973 : return page_buffers(page);
1650 : : }
1651 : :
1652 : : /*
1653 : : * NOTE! All mapped/uptodate combinations are valid:
1654 : : *
1655 : : * Mapped Uptodate Meaning
1656 : : *
1657 : : * No No "unknown" - must do get_block()
1658 : : * No Yes "hole" - zero-filled
1659 : : * Yes No "allocated" - allocated on disk, not read in
1660 : : * Yes Yes "valid" - allocated and up-to-date in memory.
1661 : : *
1662 : : * "Dirty" is valid only with the last case (mapped+uptodate).
1663 : : */
1664 : :
1665 : : /*
1666 : : * While block_write_full_page is writing back the dirty buffers under
1667 : : * the page lock, whoever dirtied the buffers may decide to clean them
1668 : : * again at any time. We handle that by only looking at the buffer
1669 : : * state inside lock_buffer().
1670 : : *
1671 : : * If block_write_full_page() is called for regular writeback
1672 : : * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1673 : : * locked buffer. This only can happen if someone has written the buffer
1674 : : * directly, with submit_bh(). At the address_space level PageWriteback
1675 : : * prevents this contention from occurring.
1676 : : *
1677 : : * If block_write_full_page() is called with wbc->sync_mode ==
1678 : : * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1679 : : * causes the writes to be flagged as synchronous writes.
1680 : : */
1681 : 0 : static int __block_write_full_page(struct inode *inode, struct page *page,
1682 : : get_block_t *get_block, struct writeback_control *wbc,
1683 : : bh_end_io_t *handler)
1684 : : {
1685 : : int err;
1686 : : sector_t block;
1687 : : sector_t last_block;
1688 : : struct buffer_head *bh, *head;
1689 : : unsigned int blocksize, bbits;
1690 : : int nr_underway = 0;
1691 [ + + ]: 26055 : int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
1692 : : WRITE_SYNC : WRITE);
1693 : :
1694 : 26055 : head = create_page_buffers(page, inode,
1695 : : (1 << BH_Dirty)|(1 << BH_Uptodate));
1696 : :
1697 : : /*
1698 : : * Be very careful. We have no exclusion from __set_page_dirty_buffers
1699 : : * here, and the (potentially unmapped) buffers may become dirty at
1700 : : * any time. If a buffer becomes dirty here after we've inspected it
1701 : : * then we just miss that fact, and the page stays dirty.
1702 : : *
1703 : : * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1704 : : * handle that here by just cleaning them.
1705 : : */
1706 : :
1707 : : bh = head;
1708 : 52110 : blocksize = bh->b_size;
1709 : 26055 : bbits = block_size_bits(blocksize);
1710 : :
1711 : 26055 : block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1712 : 26055 : last_block = (i_size_read(inode) - 1) >> bbits;
1713 : :
1714 : : /*
1715 : : * Get all the dirty buffers mapped to disk addresses and
1716 : : * handle any aliases from the underlying blockdev's mapping.
1717 : : */
1718 : : do {
1719 [ - + ]: 26055 : if (block > last_block) {
1720 : : /*
1721 : : * mapped buffers outside i_size will occur, because
1722 : : * this page can be outside i_size when there is a
1723 : : * truncate in progress.
1724 : : */
1725 : : /*
1726 : : * The buffer was zeroed by block_write_full_page()
1727 : : */
1728 : : clear_buffer_dirty(bh);
1729 : : set_buffer_uptodate(bh);
1730 [ + - ][ - + ]: 26055 : } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
[ # # ]
1731 : : buffer_dirty(bh)) {
1732 [ # # ]: 0 : WARN_ON(bh->b_size != blocksize);
1733 : 0 : err = get_block(inode, block, bh, 1);
1734 [ # # ]: 0 : if (err)
1735 : : goto recover;
1736 : : clear_buffer_delay(bh);
1737 [ # # ]: 0 : if (buffer_new(bh)) {
1738 : : /* blockdev mappings never come here */
1739 : : clear_buffer_new(bh);
1740 : 0 : unmap_underlying_metadata(bh->b_bdev,
1741 : : bh->b_blocknr);
1742 : : }
1743 : : }
1744 : 26055 : bh = bh->b_this_page;
1745 : 26055 : block++;
1746 [ - + ]: 26055 : } while (bh != head);
1747 : :
1748 : : do {
1749 [ - + ]: 26055 : if (!buffer_mapped(bh))
1750 : 0 : continue;
1751 : : /*
1752 : : * If it's a fully non-blocking write attempt and we cannot
1753 : : * lock the buffer then redirty the page. Note that this can
1754 : : * potentially cause a busy-wait loop from writeback threads
1755 : : * and kswapd activity, but those code paths have their own
1756 : : * higher-level throttling.
1757 : : */
1758 [ + + ]: 26055 : if (wbc->sync_mode != WB_SYNC_NONE) {
1759 : : lock_buffer(bh);
1760 [ + + ]: 20510 : } else if (!trylock_buffer(bh)) {
1761 : 4 : redirty_page_for_writepage(wbc, page);
1762 : 4 : continue;
1763 : : }
1764 [ + + ]: 26051 : if (test_clear_buffer_dirty(bh)) {
1765 : : mark_buffer_async_write_endio(bh, handler);
1766 : : } else {
1767 : 6199 : unlock_buffer(bh);
1768 : : }
1769 [ - + ]: 26055 : } while ((bh = bh->b_this_page) != head);
1770 : :
1771 : : /*
1772 : : * The page and its buffers are protected by PageWriteback(), so we can
1773 : : * drop the bh refcounts early.
1774 : : */
1775 [ - + ]: 26055 : BUG_ON(PageWriteback(page));
1776 : : set_page_writeback(page);
1777 : :
1778 : : do {
1779 : 26056 : struct buffer_head *next = bh->b_this_page;
1780 [ + + ]: 26056 : if (buffer_async_write(bh)) {
1781 : : submit_bh(write_op, bh);
1782 : 19851 : nr_underway++;
1783 : : }
1784 : : bh = next;
1785 [ - + ]: 26055 : } while (bh != head);
1786 : 26055 : unlock_page(page);
1787 : :
1788 : : err = 0;
1789 : : done:
1790 [ + + ]: 26055 : if (nr_underway == 0) {
1791 : : /*
1792 : : * The page was marked dirty, but the buffers were
1793 : : * clean. Someone wrote them back by hand with
1794 : : * ll_rw_block/submit_bh. A rare case.
1795 : : */
1796 : 6203 : end_page_writeback(page);
1797 : :
1798 : : /*
1799 : : * The page and buffer_heads can be released at any time from
1800 : : * here on.
1801 : : */
1802 : : }
1803 : 26055 : return err;
1804 : :
1805 : : recover:
1806 : : /*
1807 : : * ENOSPC, or some other error. We may already have added some
1808 : : * blocks to the file, so we need to write these out to avoid
1809 : : * exposing stale data.
1810 : : * The page is currently locked and not marked for writeback
1811 : : */
1812 : : bh = head;
1813 : : /* Recovery: lock and submit the mapped buffers */
1814 : : do {
1815 [ # # ][ # # ]: 0 : if (buffer_mapped(bh) && buffer_dirty(bh) &&
[ # # ]
1816 : : !buffer_delay(bh)) {
1817 : : lock_buffer(bh);
1818 : : mark_buffer_async_write_endio(bh, handler);
1819 : : } else {
1820 : : /*
1821 : : * The buffer may have been set dirty during
1822 : : * attachment to a dirty page.
1823 : : */
1824 : : clear_buffer_dirty(bh);
1825 : : }
1826 [ # # ]: 0 : } while ((bh = bh->b_this_page) != head);
1827 : : SetPageError(page);
1828 [ # # ]: 0 : BUG_ON(PageWriteback(page));
1829 : 0 : mapping_set_error(page->mapping, err);
1830 : : set_page_writeback(page);
1831 : : do {
1832 : 0 : struct buffer_head *next = bh->b_this_page;
1833 [ # # ]: 0 : if (buffer_async_write(bh)) {
1834 : : clear_buffer_dirty(bh);
1835 : : submit_bh(write_op, bh);
1836 : 0 : nr_underway++;
1837 : : }
1838 : : bh = next;
1839 [ # # ]: 0 : } while (bh != head);
1840 : 0 : unlock_page(page);
1841 : 0 : goto done;
1842 : : }
1843 : :
1844 : : /*
1845 : : * If a page has any new buffers, zero them out here, and mark them uptodate
1846 : : * and dirty so they'll be written out (in order to prevent uninitialised
1847 : : * block data from leaking). And clear the new bit.
1848 : : */
1849 : 0 : void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1850 : : {
1851 : : unsigned int block_start, block_end;
1852 : : struct buffer_head *head, *bh;
1853 : :
1854 [ - + ]: 8 : BUG_ON(!PageLocked(page));
1855 [ + - ]: 8 : if (!page_has_buffers(page))
1856 : 0 : return;
1857 : :
1858 [ - + ]: 8 : bh = head = page_buffers(page);
1859 : : block_start = 0;
1860 : : do {
1861 : 8 : block_end = block_start + bh->b_size;
1862 : :
1863 [ + + ]: 8 : if (buffer_new(bh)) {
1864 [ + - ]: 2 : if (block_end > from && block_start < to) {
1865 [ + - ]: 2 : if (!PageUptodate(page)) {
1866 : : unsigned start, size;
1867 : :
1868 : 2 : start = max(from, block_start);
1869 : 2 : size = min(to, block_end) - start;
1870 : :
1871 : : zero_user(page, start, size);
1872 : : set_buffer_uptodate(bh);
1873 : : }
1874 : :
1875 : : clear_buffer_new(bh);
1876 : 2 : mark_buffer_dirty(bh);
1877 : : }
1878 : : }
1879 : :
1880 : : block_start = block_end;
1881 : 8 : bh = bh->b_this_page;
1882 [ - + ]: 8 : } while (bh != head);
1883 : : }
1884 : : EXPORT_SYMBOL(page_zero_new_buffers);
1885 : :
1886 : 0 : int __block_write_begin(struct page *page, loff_t pos, unsigned len,
1887 : : get_block_t *get_block)
1888 : : {
1889 : 7184195 : unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1890 : 7184195 : unsigned to = from + len;
1891 : 7184195 : struct inode *inode = page->mapping->host;
1892 : : unsigned block_start, block_end;
1893 : : sector_t block;
1894 : : int err = 0;
1895 : : unsigned blocksize, bbits;
1896 : : struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1897 : :
1898 [ - + ]: 7184195 : BUG_ON(!PageLocked(page));
1899 : : BUG_ON(from > PAGE_CACHE_SIZE);
1900 [ - + ]: 7184195 : BUG_ON(to > PAGE_CACHE_SIZE);
1901 [ - + ]: 7184195 : BUG_ON(from > to);
1902 : :
1903 : 7184195 : head = create_page_buffers(page, inode, 0);
1904 : 14367910 : blocksize = head->b_size;
1905 : 7183715 : bbits = block_size_bits(blocksize);
1906 : :
1907 : 7183715 : block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1908 : :
1909 [ + + ]: 14367747 : for(bh = head, block_start = 0; bh != head || !block_start;
1910 : 7184032 : block++, block_start=block_end, bh = bh->b_this_page) {
1911 : 7183947 : block_end = block_start + blocksize;
1912 [ + ]: 7183947 : if (block_end <= from || block_start >= to) {
1913 [ - ]: 0 : if (PageUptodate(page)) {
1914 [ # # ]: 0 : if (!buffer_uptodate(bh))
1915 : : set_buffer_uptodate(bh);
1916 : : }
1917 : 0 : continue;
1918 : : }
1919 [ - + ]: 7184009 : if (buffer_new(bh))
1920 : : clear_buffer_new(bh);
1921 [ + + ]: 7184375 : if (!buffer_mapped(bh)) {
1922 [ - + ]: 1836013 : WARN_ON(bh->b_size != blocksize);
1923 : 1836013 : err = get_block(inode, block, bh, 1);
1924 [ + + ]: 9019809 : if (err)
1925 : : break;
1926 [ + ]: 1835904 : if (buffer_new(bh)) {
1927 : 1835907 : unmap_underlying_metadata(bh->b_bdev,
1928 : : bh->b_blocknr);
1929 [ + + ]: 1835959 : if (PageUptodate(page)) {
1930 : 157883 : clear_buffer_new(bh);
1931 : 157842 : set_buffer_uptodate(bh);
1932 : 157901 : mark_buffer_dirty(bh);
1933 : 157909 : continue;
1934 : : }
1935 [ + + ]: 1678076 : if (block_end > to || block_start < from)
1936 : : zero_user_segments(page,
1937 : : to, block_end,
1938 : : block_start, from);
1939 : 1678081 : continue;
1940 : : }
1941 : : }
1942 [ + + ]: 5348189 : if (PageUptodate(page)) {
1943 [ - + ]: 5348171 : if (!buffer_uptodate(bh))
1944 : : set_buffer_uptodate(bh);
1945 : 5348163 : continue;
1946 : : }
1947 [ + - ][ + - ]: 18 : if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
[ + - ]
1948 [ + - ]: 18 : !buffer_unwritten(bh) &&
1949 : 18 : (block_start < from || block_end > to)) {
1950 : 18 : ll_rw_block(READ, 1, &bh);
1951 : 18 : *wait_bh++=bh;
1952 : : }
1953 : : }
1954 : : /*
1955 : : * If we issued read requests - let them complete.
1956 : : */
1957 [ + + ]: 7183923 : while(wait_bh > wait) {
1958 : 18 : wait_on_buffer(*--wait_bh);
1959 [ - + ]: 18 : if (!buffer_uptodate(*wait_bh))
1960 : : err = -EIO;
1961 : : }
1962 [ - + ]: 7183905 : if (unlikely(err))
1963 : 0 : page_zero_new_buffers(page, from, to);
1964 : 7183905 : return err;
1965 : : }
1966 : : EXPORT_SYMBOL(__block_write_begin);
1967 : :
1968 : 0 : static int __block_commit_write(struct inode *inode, struct page *page,
1969 : : unsigned from, unsigned to)
1970 : : {
1971 : : unsigned block_start, block_end;
1972 : : int partial = 0;
1973 : : unsigned blocksize;
1974 : : struct buffer_head *bh, *head;
1975 : :
1976 [ - + ]: 7176667 : bh = head = page_buffers(page);
1977 : 7176667 : blocksize = bh->b_size;
1978 : :
1979 : : block_start = 0;
1980 : : do {
1981 : 7176681 : block_end = block_start + blocksize;
1982 [ + + ]: 7176681 : if (block_end <= from || block_start >= to) {
1983 [ - + ]: 2 : if (!buffer_uptodate(bh))
1984 : : partial = 1;
1985 : : } else {
1986 : : set_buffer_uptodate(bh);
1987 : 7176718 : mark_buffer_dirty(bh);
1988 : : }
1989 : : clear_buffer_new(bh);
1990 : :
1991 : : block_start = block_end;
1992 : 7176766 : bh = bh->b_this_page;
1993 [ + + ]: 7176766 : } while (bh != head);
1994 : :
1995 : : /*
1996 : : * If this is a partial write which happened to make all buffers
1997 : : * uptodate then we can optimize away a bogus readpage() for
1998 : : * the next read(). Here we 'discover' whether the page went
1999 : : * uptodate as a result of this (potentially partial) write.
2000 : : */
2001 [ + + ]: 7176752 : if (!partial)
2002 : : SetPageUptodate(page);
2003 : 7176689 : return 0;
2004 : : }
2005 : :
2006 : : /*
2007 : : * block_write_begin takes care of the basic task of block allocation and
2008 : : * bringing partial write blocks uptodate first.
2009 : : *
2010 : : * The filesystem needs to handle block truncation upon failure.
2011 : : */
2012 : 0 : int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
2013 : : unsigned flags, struct page **pagep, get_block_t *get_block)
2014 : : {
2015 : 0 : pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2016 : : struct page *page;
2017 : : int status;
2018 : :
2019 : 0 : page = grab_cache_page_write_begin(mapping, index, flags);
2020 [ # # ]: 0 : if (!page)
2021 : : return -ENOMEM;
2022 : :
2023 : 0 : status = __block_write_begin(page, pos, len, get_block);
2024 [ # # ]: 0 : if (unlikely(status)) {
2025 : 0 : unlock_page(page);
2026 : 0 : page_cache_release(page);
2027 : : page = NULL;
2028 : : }
2029 : :
2030 : 0 : *pagep = page;
2031 : 0 : return status;
2032 : : }
2033 : : EXPORT_SYMBOL(block_write_begin);
2034 : :
2035 : 0 : int block_write_end(struct file *file, struct address_space *mapping,
2036 : : loff_t pos, unsigned len, unsigned copied,
2037 : : struct page *page, void *fsdata)
2038 : : {
2039 : : struct inode *inode = mapping->host;
2040 : : unsigned start;
2041 : :
2042 : 6912239 : start = pos & (PAGE_CACHE_SIZE - 1);
2043 : :
2044 [ + + ]: 6912239 : if (unlikely(copied < len)) {
2045 : : /*
2046 : : * The buffers that were written will now be uptodate, so we
2047 : : * don't have to worry about a readpage reading them and
2048 : : * overwriting a partial write. However if we have encountered
2049 : : * a short write and only partially written into a buffer, it
2050 : : * will not be marked uptodate, so a readpage might come in and
2051 : : * destroy our partial write.
2052 : : *
2053 : : * Do the simplest thing, and just treat any short write to a
2054 : : * non uptodate page as a zero-length write, and force the
2055 : : * caller to redo the whole thing.
2056 : : */
2057 [ + + ]: 6912247 : if (!PageUptodate(page))
2058 : : copied = 0;
2059 : :
2060 : 8 : page_zero_new_buffers(page, start+copied, start+len);
2061 : : }
2062 : 6912239 : flush_dcache_page(page);
2063 : :
2064 : : /* This could be a short (even 0-length) commit */
2065 : 6912171 : __block_commit_write(inode, page, start, start+copied);
2066 : :
2067 : 6912257 : return copied;
2068 : : }
2069 : : EXPORT_SYMBOL(block_write_end);
2070 : :
2071 : 0 : int generic_write_end(struct file *file, struct address_space *mapping,
2072 : : loff_t pos, unsigned len, unsigned copied,
2073 : : struct page *page, void *fsdata)
2074 : : {
2075 : 6912344 : struct inode *inode = mapping->host;
2076 : : int i_size_changed = 0;
2077 : :
2078 : 6912344 : copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2079 : :
2080 : : /*
2081 : : * No need to use i_size_read() here, the i_size
2082 : : * cannot change under us because we hold i_mutex.
2083 : : *
2084 : : * But it's important to update i_size while still holding page lock:
2085 : : * page writeout could otherwise come in and zero beyond i_size.
2086 : : */
2087 [ + + ]: 6912288 : if (pos+copied > inode->i_size) {
2088 : : i_size_write(inode, pos+copied);
2089 : : i_size_changed = 1;
2090 : : }
2091 : :
2092 : 6912289 : unlock_page(page);
2093 : 6912360 : page_cache_release(page);
2094 : :
2095 : : /*
2096 : : * Don't mark the inode dirty under page lock. First, it unnecessarily
2097 : : * makes the holding time of page lock longer. Second, it forces lock
2098 : : * ordering of page lock and transaction start for journaling
2099 : : * filesystems.
2100 : : */
2101 [ + + ]: 6912372 : if (i_size_changed)
2102 : : mark_inode_dirty(inode);
2103 : :
2104 : 6912363 : return copied;
2105 : : }
2106 : : EXPORT_SYMBOL(generic_write_end);
2107 : :
2108 : : /*
2109 : : * block_is_partially_uptodate checks whether buffers within a page are
2110 : : * uptodate or not.
2111 : : *
2112 : : * Returns true if all buffers which correspond to a file portion
2113 : : * we want to read are uptodate.
2114 : : */
2115 : 0 : int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2116 : : unsigned long from)
2117 : : {
2118 : : unsigned block_start, block_end, blocksize;
2119 : : unsigned to;
2120 : : struct buffer_head *bh, *head;
2121 : : int ret = 1;
2122 : :
2123 [ # # ]: 0 : if (!page_has_buffers(page))
2124 : : return 0;
2125 : :
2126 [ # # ]: 0 : head = page_buffers(page);
2127 : 0 : blocksize = head->b_size;
2128 : 0 : to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2129 : 0 : to = from + to;
2130 [ # # ][ # # ]: 0 : if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2131 : : return 0;
2132 : :
2133 : : bh = head;
2134 : : block_start = 0;
2135 : : do {
2136 : 0 : block_end = block_start + blocksize;
2137 [ # # ]: 0 : if (block_end > from && block_start < to) {
2138 [ # # ]: 0 : if (!buffer_uptodate(bh)) {
2139 : : ret = 0;
2140 : : break;
2141 : : }
2142 [ # # ]: 0 : if (block_end >= to)
2143 : : break;
2144 : : }
2145 : : block_start = block_end;
2146 : 0 : bh = bh->b_this_page;
2147 [ # # ]: 0 : } while (bh != head);
2148 : :
2149 : 0 : return ret;
2150 : : }
2151 : : EXPORT_SYMBOL(block_is_partially_uptodate);
2152 : :
2153 : : /*
2154 : : * Generic "read page" function for block devices that have the normal
2155 : : * get_block functionality. This is most of the block device filesystems.
2156 : : * Reads the page asynchronously --- the unlock_buffer() and
2157 : : * set/clear_buffer_uptodate() functions propagate buffer state into the
2158 : : * page struct once IO has completed.
2159 : : */
2160 : 0 : int block_read_full_page(struct page *page, get_block_t *get_block)
2161 : : {
2162 : 1752 : struct inode *inode = page->mapping->host;
2163 : : sector_t iblock, lblock;
2164 : : struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2165 : : unsigned int blocksize, bbits;
2166 : : int nr, i;
2167 : : int fully_mapped = 1;
2168 : :
2169 : 1752 : head = create_page_buffers(page, inode, 0);
2170 : 3504 : blocksize = head->b_size;
2171 : 1752 : bbits = block_size_bits(blocksize);
2172 : :
2173 : 1752 : iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
2174 : 1752 : lblock = (i_size_read(inode)+blocksize-1) >> bbits;
2175 : : bh = head;
2176 : : nr = 0;
2177 : : i = 0;
2178 : :
2179 : : do {
2180 [ - + ]: 1752 : if (buffer_uptodate(bh))
2181 : 0 : continue;
2182 : :
2183 [ + - ]: 1752 : if (!buffer_mapped(bh)) {
2184 : : int err = 0;
2185 : :
2186 : : fully_mapped = 0;
2187 [ + - ]: 1752 : if (iblock < lblock) {
2188 [ - + ]: 1752 : WARN_ON(bh->b_size != blocksize);
2189 : 1752 : err = get_block(inode, iblock, bh, 0);
2190 [ - + ]: 1752 : if (err)
2191 : : SetPageError(page);
2192 : : }
2193 [ + + ]: 1752 : if (!buffer_mapped(bh)) {
2194 : 1084 : zero_user(page, i * blocksize, blocksize);
2195 [ + - ]: 1084 : if (!err)
2196 : : set_buffer_uptodate(bh);
2197 : 1084 : continue;
2198 : : }
2199 : : /*
2200 : : * get_block() might have updated the buffer
2201 : : * synchronously
2202 : : */
2203 [ - + ]: 668 : if (buffer_uptodate(bh))
2204 : 0 : continue;
2205 : : }
2206 : 668 : arr[nr++] = bh;
2207 [ - + ]: 1752 : } while (i++, iblock++, (bh = bh->b_this_page) != head);
2208 : :
2209 [ - + ]: 1752 : if (fully_mapped)
2210 : : SetPageMappedToDisk(page);
2211 : :
2212 [ + + ]: 1752 : if (!nr) {
2213 : : /*
2214 : : * All buffers are uptodate - we can set the page uptodate
2215 : : * as well. But not if get_block() returned an error.
2216 : : */
2217 [ + - ]: 1084 : if (!PageError(page))
2218 : : SetPageUptodate(page);
2219 : 1084 : unlock_page(page);
2220 : 1084 : return 0;
2221 : : }
2222 : :
2223 : : /* Stage two: lock the buffers */
2224 [ + + ]: 1336 : for (i = 0; i < nr; i++) {
2225 : 668 : bh = arr[i];
2226 : : lock_buffer(bh);
2227 : : mark_buffer_async_read(bh);
2228 : : }
2229 : :
2230 : : /*
2231 : : * Stage 3: start the IO. Check for uptodateness
2232 : : * inside the buffer lock in case another process reading
2233 : : * the underlying blockdev brought it uptodate (the sct fix).
2234 : : */
2235 [ + + ]: 1336 : for (i = 0; i < nr; i++) {
2236 : 668 : bh = arr[i];
2237 [ - + ]: 668 : if (buffer_uptodate(bh))
2238 : 0 : end_buffer_async_read(bh, 1);
2239 : : else
2240 : : submit_bh(READ, bh);
2241 : : }
2242 : : return 0;
2243 : : }
2244 : : EXPORT_SYMBOL(block_read_full_page);
2245 : :
2246 : : /* utility function for filesystems that need to do work on expanding
2247 : : * truncates. Uses filesystem pagecache writes to allow the filesystem to
2248 : : * deal with the hole.
2249 : : */
2250 : 0 : int generic_cont_expand_simple(struct inode *inode, loff_t size)
2251 : : {
2252 : 0 : struct address_space *mapping = inode->i_mapping;
2253 : : struct page *page;
2254 : : void *fsdata;
2255 : : int err;
2256 : :
2257 : 0 : err = inode_newsize_ok(inode, size);
2258 [ # # ]: 0 : if (err)
2259 : : goto out;
2260 : :
2261 : 0 : err = pagecache_write_begin(NULL, mapping, size, 0,
2262 : : AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2263 : : &page, &fsdata);
2264 [ # # ]: 0 : if (err)
2265 : : goto out;
2266 : :
2267 : 0 : err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2268 [ # # ]: 0 : BUG_ON(err > 0);
2269 : :
2270 : : out:
2271 : 0 : return err;
2272 : : }
2273 : : EXPORT_SYMBOL(generic_cont_expand_simple);
2274 : :
2275 : 0 : static int cont_expand_zero(struct file *file, struct address_space *mapping,
2276 : : loff_t pos, loff_t *bytes)
2277 : : {
2278 : 0 : struct inode *inode = mapping->host;
2279 : 0 : unsigned blocksize = 1 << inode->i_blkbits;
2280 : : struct page *page;
2281 : : void *fsdata;
2282 : : pgoff_t index, curidx;
2283 : : loff_t curpos;
2284 : : unsigned zerofrom, offset, len;
2285 : : int err = 0;
2286 : :
2287 : 0 : index = pos >> PAGE_CACHE_SHIFT;
2288 : 0 : offset = pos & ~PAGE_CACHE_MASK;
2289 : :
2290 [ # # ]: 0 : while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2291 : 0 : zerofrom = curpos & ~PAGE_CACHE_MASK;
2292 [ # # ]: 0 : if (zerofrom & (blocksize-1)) {
2293 : 0 : *bytes |= (blocksize-1);
2294 : 0 : (*bytes)++;
2295 : : }
2296 : 0 : len = PAGE_CACHE_SIZE - zerofrom;
2297 : :
2298 : 0 : err = pagecache_write_begin(file, mapping, curpos, len,
2299 : : AOP_FLAG_UNINTERRUPTIBLE,
2300 : : &page, &fsdata);
2301 [ # # ]: 0 : if (err)
2302 : : goto out;
2303 : 0 : zero_user(page, zerofrom, len);
2304 : 0 : err = pagecache_write_end(file, mapping, curpos, len, len,
2305 : : page, fsdata);
2306 [ # # ]: 0 : if (err < 0)
2307 : : goto out;
2308 [ # # ]: 0 : BUG_ON(err != len);
2309 : : err = 0;
2310 : :
2311 : 0 : balance_dirty_pages_ratelimited(mapping);
2312 : : }
2313 : :
2314 : : /* page covers the boundary, find the boundary offset */
2315 [ # # ]: 0 : if (index == curidx) {
2316 : 0 : zerofrom = curpos & ~PAGE_CACHE_MASK;
2317 : : /* if we will expand the thing last block will be filled */
2318 [ # # ]: 0 : if (offset <= zerofrom) {
2319 : : goto out;
2320 : : }
2321 [ # # ]: 0 : if (zerofrom & (blocksize-1)) {
2322 : 0 : *bytes |= (blocksize-1);
2323 : 0 : (*bytes)++;
2324 : : }
2325 : 0 : len = offset - zerofrom;
2326 : :
2327 : 0 : err = pagecache_write_begin(file, mapping, curpos, len,
2328 : : AOP_FLAG_UNINTERRUPTIBLE,
2329 : : &page, &fsdata);
2330 [ # # ]: 0 : if (err)
2331 : : goto out;
2332 : 0 : zero_user(page, zerofrom, len);
2333 : 0 : err = pagecache_write_end(file, mapping, curpos, len, len,
2334 : : page, fsdata);
2335 [ # # ]: 0 : if (err < 0)
2336 : : goto out;
2337 [ # # ]: 0 : BUG_ON(err != len);
2338 : : err = 0;
2339 : : }
2340 : : out:
2341 : 0 : return err;
2342 : : }
2343 : :
2344 : : /*
2345 : : * For moronic filesystems that do not allow holes in file.
2346 : : * We may have to extend the file.
2347 : : */
2348 : 0 : int cont_write_begin(struct file *file, struct address_space *mapping,
2349 : : loff_t pos, unsigned len, unsigned flags,
2350 : : struct page **pagep, void **fsdata,
2351 : : get_block_t *get_block, loff_t *bytes)
2352 : : {
2353 : 0 : struct inode *inode = mapping->host;
2354 : 0 : unsigned blocksize = 1 << inode->i_blkbits;
2355 : : unsigned zerofrom;
2356 : : int err;
2357 : :
2358 : 0 : err = cont_expand_zero(file, mapping, pos, bytes);
2359 [ # # ]: 0 : if (err)
2360 : : return err;
2361 : :
2362 : 0 : zerofrom = *bytes & ~PAGE_CACHE_MASK;
2363 [ # # ][ # # ]: 0 : if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2364 : 0 : *bytes |= (blocksize-1);
2365 : 0 : (*bytes)++;
2366 : : }
2367 : :
2368 : 0 : return block_write_begin(mapping, pos, len, flags, pagep, get_block);
2369 : : }
2370 : : EXPORT_SYMBOL(cont_write_begin);
2371 : :
2372 : 0 : int block_commit_write(struct page *page, unsigned from, unsigned to)
2373 : : {
2374 : : struct inode *inode = page->mapping->host;
2375 : 264357 : __block_commit_write(inode,page,from,to);
2376 : 0 : return 0;
2377 : : }
2378 : : EXPORT_SYMBOL(block_commit_write);
2379 : :
2380 : : /*
2381 : : * block_page_mkwrite() is not allowed to change the file size as it gets
2382 : : * called from a page fault handler when a page is first dirtied. Hence we must
2383 : : * be careful to check for EOF conditions here. We set the page up correctly
2384 : : * for a written page which means we get ENOSPC checking when writing into
2385 : : * holes and correct delalloc and unwritten extent mapping on filesystems that
2386 : : * support these features.
2387 : : *
2388 : : * We are not allowed to take the i_mutex here so we have to play games to
2389 : : * protect against truncate races as the page could now be beyond EOF. Because
2390 : : * truncate writes the inode size before removing pages, once we have the
2391 : : * page lock we can determine safely if the page is beyond EOF. If it is not
2392 : : * beyond EOF, then the page is guaranteed safe against truncation until we
2393 : : * unlock the page.
2394 : : *
2395 : : * Direct callers of this function should protect against filesystem freezing
2396 : : * using sb_start_write() - sb_end_write() functions.
2397 : : */
2398 : 0 : int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2399 : : get_block_t get_block)
2400 : : {
2401 : 528750 : struct page *page = vmf->page;
2402 : 264373 : struct inode *inode = file_inode(vma->vm_file);
2403 : : unsigned long end;
2404 : : loff_t size;
2405 : : int ret;
2406 : :
2407 : : lock_page(page);
2408 : : size = i_size_read(inode);
2409 [ + ][ + - ]: 264373 : if ((page->mapping != inode->i_mapping) ||
2410 : : (page_offset(page) > size)) {
2411 : : /* We overload EFAULT to mean page got truncated */
2412 : : ret = -EFAULT;
2413 : : goto out_unlock;
2414 : : }
2415 : :
2416 : : /* page is wholly or partially inside EOF */
2417 [ + + ]: 264377 : if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2418 : 92283 : end = size & ~PAGE_CACHE_MASK;
2419 : : else
2420 : : end = PAGE_CACHE_SIZE;
2421 : :
2422 : 264377 : ret = __block_write_begin(page, 0, end, get_block);
2423 [ + + ]: 264359 : if (!ret)
2424 : : ret = block_commit_write(page, 0, end);
2425 : :
2426 [ + - ]: 264382 : if (unlikely(ret < 0))
2427 : : goto out_unlock;
2428 : 264382 : set_page_dirty(page);
2429 : 264384 : wait_for_stable_page(page);
2430 : 264371 : return 0;
2431 : : out_unlock:
2432 : 0 : unlock_page(page);
2433 : 0 : return ret;
2434 : : }
2435 : : EXPORT_SYMBOL(__block_page_mkwrite);
2436 : :
2437 : 0 : int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2438 : : get_block_t get_block)
2439 : : {
2440 : : int ret;
2441 : 0 : struct super_block *sb = file_inode(vma->vm_file)->i_sb;
2442 : :
2443 : : sb_start_pagefault(sb);
2444 : :
2445 : : /*
2446 : : * Update file times before taking page lock. We may end up failing the
2447 : : * fault so this update may be superfluous but who really cares...
2448 : : */
2449 : 0 : file_update_time(vma->vm_file);
2450 : :
2451 : 0 : ret = __block_page_mkwrite(vma, vmf, get_block);
2452 : : sb_end_pagefault(sb);
2453 : 0 : return block_page_mkwrite_return(ret);
2454 : : }
2455 : : EXPORT_SYMBOL(block_page_mkwrite);
2456 : :
2457 : : /*
2458 : : * nobh_write_begin()'s prereads are special: the buffer_heads are freed
2459 : : * immediately, while under the page lock. So it needs a special end_io
2460 : : * handler which does not touch the bh after unlocking it.
2461 : : */
2462 : 0 : static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2463 : : {
2464 : 0 : __end_buffer_read_notouch(bh, uptodate);
2465 : 0 : }
2466 : :
2467 : : /*
2468 : : * Attach the singly-linked list of buffers created by nobh_write_begin, to
2469 : : * the page (converting it to circular linked list and taking care of page
2470 : : * dirty races).
2471 : : */
2472 : 0 : static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2473 : : {
2474 : : struct buffer_head *bh;
2475 : :
2476 [ # # ]: 0 : BUG_ON(!PageLocked(page));
2477 : :
2478 : 0 : spin_lock(&page->mapping->private_lock);
2479 : : bh = head;
2480 : : do {
2481 [ # # ]: 0 : if (PageDirty(page))
2482 : : set_buffer_dirty(bh);
2483 [ # # ]: 0 : if (!bh->b_this_page)
2484 : 0 : bh->b_this_page = head;
2485 : 0 : bh = bh->b_this_page;
2486 [ # # ]: 0 : } while (bh != head);
2487 : : attach_page_buffers(page, head);
2488 : 0 : spin_unlock(&page->mapping->private_lock);
2489 : 0 : }
2490 : :
2491 : : /*
2492 : : * On entry, the page is fully not uptodate.
2493 : : * On exit the page is fully uptodate in the areas outside (from,to)
2494 : : * The filesystem needs to handle block truncation upon failure.
2495 : : */
2496 : 0 : int nobh_write_begin(struct address_space *mapping,
2497 : : loff_t pos, unsigned len, unsigned flags,
2498 : : struct page **pagep, void **fsdata,
2499 : : get_block_t *get_block)
2500 : : {
2501 : 0 : struct inode *inode = mapping->host;
2502 : 0 : const unsigned blkbits = inode->i_blkbits;
2503 : 0 : const unsigned blocksize = 1 << blkbits;
2504 : : struct buffer_head *head, *bh;
2505 : : struct page *page;
2506 : : pgoff_t index;
2507 : : unsigned from, to;
2508 : : unsigned block_in_page;
2509 : : unsigned block_start, block_end;
2510 : : sector_t block_in_file;
2511 : : int nr_reads = 0;
2512 : : int ret = 0;
2513 : : int is_mapped_to_disk = 1;
2514 : :
2515 : 0 : index = pos >> PAGE_CACHE_SHIFT;
2516 : 0 : from = pos & (PAGE_CACHE_SIZE - 1);
2517 : 0 : to = from + len;
2518 : :
2519 : 0 : page = grab_cache_page_write_begin(mapping, index, flags);
2520 [ # # ]: 0 : if (!page)
2521 : : return -ENOMEM;
2522 : 0 : *pagep = page;
2523 : 0 : *fsdata = NULL;
2524 : :
2525 [ # # ]: 0 : if (page_has_buffers(page)) {
2526 : 0 : ret = __block_write_begin(page, pos, len, get_block);
2527 [ # # ]: 0 : if (unlikely(ret))
2528 : : goto out_release;
2529 : : return ret;
2530 : : }
2531 : :
2532 [ # # ]: 0 : if (PageMappedToDisk(page))
2533 : : return 0;
2534 : :
2535 : : /*
2536 : : * Allocate buffers so that we can keep track of state, and potentially
2537 : : * attach them to the page if an error occurs. In the common case of
2538 : : * no error, they will just be freed again without ever being attached
2539 : : * to the page (which is all OK, because we're under the page lock).
2540 : : *
2541 : : * Be careful: the buffer linked list is a NULL terminated one, rather
2542 : : * than the circular one we're used to.
2543 : : */
2544 : 0 : head = alloc_page_buffers(page, blocksize, 0);
2545 [ # # ]: 0 : if (!head) {
2546 : : ret = -ENOMEM;
2547 : : goto out_release;
2548 : : }
2549 : :
2550 : 0 : block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
2551 : :
2552 : : /*
2553 : : * We loop across all blocks in the page, whether or not they are
2554 : : * part of the affected region. This is so we can discover if the
2555 : : * page is fully mapped-to-disk.
2556 : : */
2557 [ # # ]: 0 : for (block_start = 0, block_in_page = 0, bh = head;
2558 : : block_start < PAGE_CACHE_SIZE;
2559 : 0 : block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
2560 : : int create;
2561 : :
2562 : 0 : block_end = block_start + blocksize;
2563 : 0 : bh->b_state = 0;
2564 : : create = 1;
2565 [ # # ]: 0 : if (block_start >= to)
2566 : : create = 0;
2567 : 0 : ret = get_block(inode, block_in_file + block_in_page,
2568 : : bh, create);
2569 [ # # ]: 0 : if (ret)
2570 : : goto failed;
2571 [ # # ]: 0 : if (!buffer_mapped(bh))
2572 : : is_mapped_to_disk = 0;
2573 [ # # ]: 0 : if (buffer_new(bh))
2574 : 0 : unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2575 [ # # ]: 0 : if (PageUptodate(page)) {
2576 : : set_buffer_uptodate(bh);
2577 : 0 : continue;
2578 : : }
2579 [ # # ][ # # ]: 0 : if (buffer_new(bh) || !buffer_mapped(bh)) {
2580 : : zero_user_segments(page, block_start, from,
2581 : : to, block_end);
2582 : 0 : continue;
2583 : : }
2584 [ # # ]: 0 : if (buffer_uptodate(bh))
2585 : 0 : continue; /* reiserfs does this */
2586 [ # # ]: 0 : if (block_start < from || block_end > to) {
2587 : : lock_buffer(bh);
2588 : 0 : bh->b_end_io = end_buffer_read_nobh;
2589 : : submit_bh(READ, bh);
2590 : 0 : nr_reads++;
2591 : : }
2592 : : }
2593 : :
2594 [ # # ]: 0 : if (nr_reads) {
2595 : : /*
2596 : : * The page is locked, so these buffers are protected from
2597 : : * any VM or truncate activity. Hence we don't need to care
2598 : : * for the buffer_head refcounts.
2599 : : */
2600 [ # # ]: 0 : for (bh = head; bh; bh = bh->b_this_page) {
2601 : : wait_on_buffer(bh);
2602 [ # # ]: 0 : if (!buffer_uptodate(bh))
2603 : : ret = -EIO;
2604 : : }
2605 [ # # ]: 0 : if (ret)
2606 : : goto failed;
2607 : : }
2608 : :
2609 [ # # ]: 0 : if (is_mapped_to_disk)
2610 : : SetPageMappedToDisk(page);
2611 : :
2612 : 0 : *fsdata = head; /* to be released by nobh_write_end */
2613 : :
2614 : 0 : return 0;
2615 : :
2616 : : failed:
2617 [ # # ]: 0 : BUG_ON(!ret);
2618 : : /*
2619 : : * Error recovery is a bit difficult. We need to zero out blocks that
2620 : : * were newly allocated, and dirty them to ensure they get written out.
2621 : : * Buffers need to be attached to the page at this point, otherwise
2622 : : * the handling of potential IO errors during writeout would be hard
2623 : : * (could try doing synchronous writeout, but what if that fails too?)
2624 : : */
2625 : 0 : attach_nobh_buffers(page, head);
2626 : 0 : page_zero_new_buffers(page, from, to);
2627 : :
2628 : : out_release:
2629 : 0 : unlock_page(page);
2630 : 0 : page_cache_release(page);
2631 : 0 : *pagep = NULL;
2632 : :
2633 : 0 : return ret;
2634 : : }
2635 : : EXPORT_SYMBOL(nobh_write_begin);
2636 : :
2637 : 0 : int nobh_write_end(struct file *file, struct address_space *mapping,
2638 : : loff_t pos, unsigned len, unsigned copied,
2639 : : struct page *page, void *fsdata)
2640 : : {
2641 : 0 : struct inode *inode = page->mapping->host;
2642 : : struct buffer_head *head = fsdata;
2643 : : struct buffer_head *bh;
2644 [ # # ][ # # ]: 0 : BUG_ON(fsdata != NULL && page_has_buffers(page));
2645 : :
2646 [ # # ][ # # ]: 0 : if (unlikely(copied < len) && head)
2647 : 0 : attach_nobh_buffers(page, head);
2648 [ # # ]: 0 : if (page_has_buffers(page))
2649 : 0 : return generic_write_end(file, mapping, pos, len,
2650 : : copied, page, fsdata);
2651 : :
2652 : : SetPageUptodate(page);
2653 : 0 : set_page_dirty(page);
2654 [ # # ]: 0 : if (pos+copied > inode->i_size) {
2655 : : i_size_write(inode, pos+copied);
2656 : : mark_inode_dirty(inode);
2657 : : }
2658 : :
2659 : 0 : unlock_page(page);
2660 : 0 : page_cache_release(page);
2661 : :
2662 [ # # ]: 0 : while (head) {
2663 : : bh = head;
2664 : 0 : head = head->b_this_page;
2665 : 0 : free_buffer_head(bh);
2666 : : }
2667 : :
2668 : 0 : return copied;
2669 : : }
2670 : : EXPORT_SYMBOL(nobh_write_end);
2671 : :
2672 : : /*
2673 : : * nobh_writepage() - based on block_full_write_page() except
2674 : : * that it tries to operate without attaching bufferheads to
2675 : : * the page.
2676 : : */
2677 : 0 : int nobh_writepage(struct page *page, get_block_t *get_block,
2678 : : struct writeback_control *wbc)
2679 : : {
2680 : 0 : struct inode * const inode = page->mapping->host;
2681 : : loff_t i_size = i_size_read(inode);
2682 : 0 : const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2683 : : unsigned offset;
2684 : : int ret;
2685 : :
2686 : : /* Is the page fully inside i_size? */
2687 [ # # ]: 0 : if (page->index < end_index)
2688 : : goto out;
2689 : :
2690 : : /* Is the page fully outside i_size? (truncate in progress) */
2691 : 0 : offset = i_size & (PAGE_CACHE_SIZE-1);
2692 [ # # ][ # # ]: 0 : if (page->index >= end_index+1 || !offset) {
2693 : : /*
2694 : : * The page may have dirty, unmapped buffers. For example,
2695 : : * they may have been added in ext3_writepage(). Make them
2696 : : * freeable here, so the page does not leak.
2697 : : */
2698 : : #if 0
2699 : : /* Not really sure about this - do we need this ? */
2700 : : if (page->mapping->a_ops->invalidatepage)
2701 : : page->mapping->a_ops->invalidatepage(page, offset);
2702 : : #endif
2703 : 0 : unlock_page(page);
2704 : 0 : return 0; /* don't care */
2705 : : }
2706 : :
2707 : : /*
2708 : : * The page straddles i_size. It must be zeroed out on each and every
2709 : : * writepage invocation because it may be mmapped. "A file is mapped
2710 : : * in multiples of the page size. For a file that is not a multiple of
2711 : : * the page size, the remaining memory is zeroed when mapped, and
2712 : : * writes to that region are not written out to the file."
2713 : : */
2714 : : zero_user_segment(page, offset, PAGE_CACHE_SIZE);
2715 : : out:
2716 : 0 : ret = mpage_writepage(page, get_block, wbc);
2717 [ # # ]: 0 : if (ret == -EAGAIN)
2718 : 0 : ret = __block_write_full_page(inode, page, get_block, wbc,
2719 : : end_buffer_async_write);
2720 : 0 : return ret;
2721 : : }
2722 : : EXPORT_SYMBOL(nobh_writepage);
2723 : :
2724 : 0 : int nobh_truncate_page(struct address_space *mapping,
2725 : : loff_t from, get_block_t *get_block)
2726 : : {
2727 : 0 : pgoff_t index = from >> PAGE_CACHE_SHIFT;
2728 : 0 : unsigned offset = from & (PAGE_CACHE_SIZE-1);
2729 : : unsigned blocksize;
2730 : : sector_t iblock;
2731 : : unsigned length, pos;
2732 : 0 : struct inode *inode = mapping->host;
2733 : : struct page *page;
2734 : : struct buffer_head map_bh;
2735 : : int err;
2736 : :
2737 : 0 : blocksize = 1 << inode->i_blkbits;
2738 : 0 : length = offset & (blocksize - 1);
2739 : :
2740 : : /* Block boundary? Nothing to do */
2741 [ # # ]: 0 : if (!length)
2742 : : return 0;
2743 : :
2744 : 0 : length = blocksize - length;
2745 : 0 : iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2746 : :
2747 : : page = grab_cache_page(mapping, index);
2748 : : err = -ENOMEM;
2749 [ # # ]: 0 : if (!page)
2750 : : goto out;
2751 : :
2752 [ # # ]: 0 : if (page_has_buffers(page)) {
2753 : : has_buffers:
2754 : 0 : unlock_page(page);
2755 : 0 : page_cache_release(page);
2756 : 0 : return block_truncate_page(mapping, from, get_block);
2757 : : }
2758 : :
2759 : : /* Find the buffer that contains "offset" */
2760 : : pos = blocksize;
2761 [ # # ]: 0 : while (offset >= pos) {
2762 : 0 : iblock++;
2763 : 0 : pos += blocksize;
2764 : : }
2765 : :
2766 : 0 : map_bh.b_size = blocksize;
2767 : 0 : map_bh.b_state = 0;
2768 : 0 : err = get_block(inode, iblock, &map_bh, 0);
2769 [ # # ]: 0 : if (err)
2770 : : goto unlock;
2771 : : /* unmapped? It's a hole - nothing to do */
2772 [ # # ]: 0 : if (!buffer_mapped(&map_bh))
2773 : : goto unlock;
2774 : :
2775 : : /* Ok, it's mapped. Make sure it's up-to-date */
2776 [ # # ]: 0 : if (!PageUptodate(page)) {
2777 : 0 : err = mapping->a_ops->readpage(NULL, page);
2778 [ # # ]: 0 : if (err) {
2779 : 0 : page_cache_release(page);
2780 : 0 : goto out;
2781 : : }
2782 : : lock_page(page);
2783 [ # # ]: 0 : if (!PageUptodate(page)) {
2784 : : err = -EIO;
2785 : : goto unlock;
2786 : : }
2787 [ # # ]: 0 : if (page_has_buffers(page))
2788 : : goto has_buffers;
2789 : : }
2790 : : zero_user(page, offset, length);
2791 : 0 : set_page_dirty(page);
2792 : : err = 0;
2793 : :
2794 : : unlock:
2795 : 0 : unlock_page(page);
2796 : 0 : page_cache_release(page);
2797 : : out:
2798 : 0 : return err;
2799 : : }
2800 : : EXPORT_SYMBOL(nobh_truncate_page);
2801 : :
2802 : 0 : int block_truncate_page(struct address_space *mapping,
2803 : : loff_t from, get_block_t *get_block)
2804 : : {
2805 : 0 : pgoff_t index = from >> PAGE_CACHE_SHIFT;
2806 : 0 : unsigned offset = from & (PAGE_CACHE_SIZE-1);
2807 : : unsigned blocksize;
2808 : : sector_t iblock;
2809 : : unsigned length, pos;
2810 : 0 : struct inode *inode = mapping->host;
2811 : : struct page *page;
2812 : : struct buffer_head *bh;
2813 : : int err;
2814 : :
2815 : 0 : blocksize = 1 << inode->i_blkbits;
2816 : 0 : length = offset & (blocksize - 1);
2817 : :
2818 : : /* Block boundary? Nothing to do */
2819 [ # # ]: 0 : if (!length)
2820 : : return 0;
2821 : :
2822 : 0 : length = blocksize - length;
2823 : 0 : iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2824 : :
2825 : : page = grab_cache_page(mapping, index);
2826 : : err = -ENOMEM;
2827 [ # # ]: 0 : if (!page)
2828 : : goto out;
2829 : :
2830 [ # # ]: 0 : if (!page_has_buffers(page))
2831 : 0 : create_empty_buffers(page, blocksize, 0);
2832 : :
2833 : : /* Find the buffer that contains "offset" */
2834 [ # # ]: 0 : bh = page_buffers(page);
2835 : : pos = blocksize;
2836 [ # # ]: 0 : while (offset >= pos) {
2837 : 0 : bh = bh->b_this_page;
2838 : 0 : iblock++;
2839 : 0 : pos += blocksize;
2840 : : }
2841 : :
2842 : : err = 0;
2843 [ # # ]: 0 : if (!buffer_mapped(bh)) {
2844 [ # # ]: 0 : WARN_ON(bh->b_size != blocksize);
2845 : 0 : err = get_block(inode, iblock, bh, 0);
2846 [ # # ]: 0 : if (err)
2847 : : goto unlock;
2848 : : /* unmapped? It's a hole - nothing to do */
2849 [ # # ]: 0 : if (!buffer_mapped(bh))
2850 : : goto unlock;
2851 : : }
2852 : :
2853 : : /* Ok, it's mapped. Make sure it's up-to-date */
2854 [ # # ]: 0 : if (PageUptodate(page))
2855 : 0 : set_buffer_uptodate(bh);
2856 : :
2857 [ # # ][ # # ]: 0 : if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
[ # # ]
2858 : : err = -EIO;
2859 : 0 : ll_rw_block(READ, 1, &bh);
2860 : 0 : wait_on_buffer(bh);
2861 : : /* Uhhuh. Read error. Complain and punt. */
2862 [ # # ]: 0 : if (!buffer_uptodate(bh))
2863 : : goto unlock;
2864 : : }
2865 : :
2866 : : zero_user(page, offset, length);
2867 : 0 : mark_buffer_dirty(bh);
2868 : : err = 0;
2869 : :
2870 : : unlock:
2871 : 0 : unlock_page(page);
2872 : 0 : page_cache_release(page);
2873 : : out:
2874 : 0 : return err;
2875 : : }
2876 : : EXPORT_SYMBOL(block_truncate_page);
2877 : :
2878 : : /*
2879 : : * The generic ->writepage function for buffer-backed address_spaces
2880 : : * this form passes in the end_io handler used to finish the IO.
2881 : : */
2882 : 0 : int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2883 : : struct writeback_control *wbc, bh_end_io_t *handler)
2884 : : {
2885 : 26055 : struct inode * const inode = page->mapping->host;
2886 : : loff_t i_size = i_size_read(inode);
2887 : 26055 : const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2888 : : unsigned offset;
2889 : :
2890 : : /* Is the page fully inside i_size? */
2891 [ + - ]: 26055 : if (page->index < end_index)
2892 : 26055 : return __block_write_full_page(inode, page, get_block, wbc,
2893 : : handler);
2894 : :
2895 : : /* Is the page fully outside i_size? (truncate in progress) */
2896 : 0 : offset = i_size & (PAGE_CACHE_SIZE-1);
2897 [ # # ][ # # ]: 0 : if (page->index >= end_index+1 || !offset) {
2898 : : /*
2899 : : * The page may have dirty, unmapped buffers. For example,
2900 : : * they may have been added in ext3_writepage(). Make them
2901 : : * freeable here, so the page does not leak.
2902 : : */
2903 : 0 : do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
2904 : 0 : unlock_page(page);
2905 : 0 : return 0; /* don't care */
2906 : : }
2907 : :
2908 : : /*
2909 : : * The page straddles i_size. It must be zeroed out on each and every
2910 : : * writepage invocation because it may be mmapped. "A file is mapped
2911 : : * in multiples of the page size. For a file that is not a multiple of
2912 : : * the page size, the remaining memory is zeroed when mapped, and
2913 : : * writes to that region are not written out to the file."
2914 : : */
2915 : : zero_user_segment(page, offset, PAGE_CACHE_SIZE);
2916 : 0 : return __block_write_full_page(inode, page, get_block, wbc, handler);
2917 : : }
2918 : : EXPORT_SYMBOL(block_write_full_page_endio);
2919 : :
2920 : : /*
2921 : : * The generic ->writepage function for buffer-backed address_spaces
2922 : : */
2923 : 0 : int block_write_full_page(struct page *page, get_block_t *get_block,
2924 : : struct writeback_control *wbc)
2925 : : {
2926 : 26055 : return block_write_full_page_endio(page, get_block, wbc,
2927 : : end_buffer_async_write);
2928 : : }
2929 : : EXPORT_SYMBOL(block_write_full_page);
2930 : :
2931 : 0 : sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2932 : : get_block_t *get_block)
2933 : : {
2934 : : struct buffer_head tmp;
2935 : 145402 : struct inode *inode = mapping->host;
2936 : 145402 : tmp.b_state = 0;
2937 : 145402 : tmp.b_blocknr = 0;
2938 : 145402 : tmp.b_size = 1 << inode->i_blkbits;
2939 : 145402 : get_block(inode, block, &tmp, 0);
2940 : 145402 : return tmp.b_blocknr;
2941 : : }
2942 : : EXPORT_SYMBOL(generic_block_bmap);
2943 : :
2944 : 0 : static void end_bio_bh_io_sync(struct bio *bio, int err)
2945 : : {
2946 : 138168 : struct buffer_head *bh = bio->bi_private;
2947 : :
2948 [ - + ]: 138168 : if (err == -EOPNOTSUPP) {
2949 : 0 : set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2950 : : }
2951 : :
2952 [ - + ]: 138168 : if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2953 : 0 : set_bit(BH_Quiet, &bh->b_state);
2954 : :
2955 : 138168 : bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2956 : 138168 : bio_put(bio);
2957 : 138168 : }
2958 : :
2959 : : /*
2960 : : * This allows us to do IO even on the odd last sectors
2961 : : * of a device, even if the bh block size is some multiple
2962 : : * of the physical sector size.
2963 : : *
2964 : : * We'll just truncate the bio to the size of the device,
2965 : : * and clear the end of the buffer head manually.
2966 : : *
2967 : : * Truly out-of-range accesses will turn into actual IO
2968 : : * errors, this only handles the "we need to be able to
2969 : : * do IO at the final sector" case.
2970 : : */
2971 : 0 : static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh)
2972 : : {
2973 : : sector_t maxsector;
2974 : : unsigned bytes;
2975 : :
2976 : 138168 : maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
2977 [ + - ]: 138167 : if (!maxsector)
2978 : : return;
2979 : :
2980 : : /*
2981 : : * If the *whole* IO is past the end of the device,
2982 : : * let it through, and the IO layer will turn it into
2983 : : * an EIO.
2984 : : */
2985 [ + - ]: 138167 : if (unlikely(bio->bi_sector >= maxsector))
2986 : : return;
2987 : :
2988 : 138167 : maxsector -= bio->bi_sector;
2989 : 138167 : bytes = bio->bi_size;
2990 [ - + ]: 138167 : if (likely((bytes >> 9) <= maxsector))
2991 : : return;
2992 : :
2993 : : /* Uhhuh. We've got a bh that straddles the device size! */
2994 : 0 : bytes = maxsector << 9;
2995 : :
2996 : : /* Truncate the bio.. */
2997 : 0 : bio->bi_size = bytes;
2998 : 0 : bio->bi_io_vec[0].bv_len = bytes;
2999 : :
3000 : : /* ..and clear the end of the buffer for reads */
3001 [ # # ]: 0 : if ((rw & RW_MASK) == READ) {
3002 : 0 : void *kaddr = kmap_atomic(bh->b_page);
3003 [ # # ]: 0 : memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes);
3004 : 0 : kunmap_atomic(kaddr);
3005 : 0 : flush_dcache_page(bh->b_page);
3006 : : }
3007 : : }
3008 : :
3009 : 0 : int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
3010 : : {
3011 : : struct bio *bio;
3012 : : int ret = 0;
3013 : :
3014 [ - + ]: 138168 : BUG_ON(!buffer_locked(bh));
3015 [ - + ]: 138168 : BUG_ON(!buffer_mapped(bh));
3016 [ - + ]: 138168 : BUG_ON(!bh->b_end_io);
3017 [ - + ]: 138168 : BUG_ON(buffer_delay(bh));
3018 [ - + ]: 138168 : BUG_ON(buffer_unwritten(bh));
3019 : :
3020 : : /*
3021 : : * Only clear out a write error when rewriting
3022 : : */
3023 [ + + ][ + - ]: 138168 : if (test_set_buffer_req(bh) && (rw & WRITE))
3024 : : clear_buffer_write_io_error(bh);
3025 : :
3026 : : /*
3027 : : * from here on down, it's all bio -- do the initial mapping,
3028 : : * submit_bio -> generic_make_request may further map this bio around
3029 : : */
3030 : : bio = bio_alloc(GFP_NOIO, 1);
3031 : :
3032 : 138167 : bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
3033 : 138167 : bio->bi_bdev = bh->b_bdev;
3034 : 138167 : bio->bi_io_vec[0].bv_page = bh->b_page;
3035 : 138167 : bio->bi_io_vec[0].bv_len = bh->b_size;
3036 : 138167 : bio->bi_io_vec[0].bv_offset = bh_offset(bh);
3037 : :
3038 : 138167 : bio->bi_vcnt = 1;
3039 : 138167 : bio->bi_size = bh->b_size;
3040 : :
3041 : 138167 : bio->bi_end_io = end_bio_bh_io_sync;
3042 : 138167 : bio->bi_private = bh;
3043 : 138167 : bio->bi_flags |= bio_flags;
3044 : :
3045 : : /* Take care of bh's that straddle the end of the device */
3046 : 138167 : guard_bh_eod(rw, bio, bh);
3047 : :
3048 [ + + ]: 138167 : if (buffer_meta(bh))
3049 : 19174 : rw |= REQ_META;
3050 [ + + ]: 138167 : if (buffer_prio(bh))
3051 : 19174 : rw |= REQ_PRIO;
3052 : :
3053 : 0 : bio_get(bio);
3054 : 138167 : submit_bio(rw, bio);
3055 : :
3056 [ - + ]: 138165 : if (bio_flagged(bio, BIO_EOPNOTSUPP))
3057 : : ret = -EOPNOTSUPP;
3058 : :
3059 : 138165 : bio_put(bio);
3060 : 138165 : return ret;
3061 : : }
3062 : : EXPORT_SYMBOL_GPL(_submit_bh);
3063 : :
3064 : 0 : int submit_bh(int rw, struct buffer_head *bh)
3065 : : {
3066 : 138168 : return _submit_bh(rw, bh, 0);
3067 : : }
3068 : : EXPORT_SYMBOL(submit_bh);
3069 : :
3070 : : /**
3071 : : * ll_rw_block: low-level access to block devices (DEPRECATED)
3072 : : * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
3073 : : * @nr: number of &struct buffer_heads in the array
3074 : : * @bhs: array of pointers to &struct buffer_head
3075 : : *
3076 : : * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
3077 : : * requests an I/O operation on them, either a %READ or a %WRITE. The third
3078 : : * %READA option is described in the documentation for generic_make_request()
3079 : : * which ll_rw_block() calls.
3080 : : *
3081 : : * This function drops any buffer that it cannot get a lock on (with the
3082 : : * BH_Lock state bit), any buffer that appears to be clean when doing a write
3083 : : * request, and any buffer that appears to be up-to-date when doing read
3084 : : * request. Further it marks as clean buffers that are processed for
3085 : : * writing (the buffer cache won't assume that they are actually clean
3086 : : * until the buffer gets unlocked).
3087 : : *
3088 : : * ll_rw_block sets b_end_io to simple completion handler that marks
3089 : : * the buffer up-to-date (if approriate), unlocks the buffer and wakes
3090 : : * any waiters.
3091 : : *
3092 : : * All of the buffers must be for the same device, and must also be a
3093 : : * multiple of the current approved size for the device.
3094 : : */
3095 : 0 : void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3096 : : {
3097 : : int i;
3098 : :
3099 [ + + ]: 2159402 : for (i = 0; i < nr; i++) {
3100 : 1079704 : struct buffer_head *bh = bhs[i];
3101 : :
3102 [ + + ]: 1079707 : if (!trylock_buffer(bh))
3103 : 208 : continue;
3104 [ - + ]: 1079499 : if (rw == WRITE) {
3105 [ # # ]: 0 : if (test_clear_buffer_dirty(bh)) {
3106 : 0 : bh->b_end_io = end_buffer_write_sync;
3107 : : get_bh(bh);
3108 : : submit_bh(WRITE, bh);
3109 : 0 : continue;
3110 : : }
3111 : : } else {
3112 [ + + ]: 1079499 : if (!buffer_uptodate(bh)) {
3113 : 5076 : bh->b_end_io = end_buffer_read_sync;
3114 : : get_bh(bh);
3115 : : submit_bh(rw, bh);
3116 : 5076 : continue;
3117 : : }
3118 : : }
3119 : 1074423 : unlock_buffer(bh);
3120 : : }
3121 : 1079698 : }
3122 : : EXPORT_SYMBOL(ll_rw_block);
3123 : :
3124 : 0 : void write_dirty_buffer(struct buffer_head *bh, int rw)
3125 : : {
3126 : : lock_buffer(bh);
3127 [ - + ]: 610 : if (!test_clear_buffer_dirty(bh)) {
3128 : 0 : unlock_buffer(bh);
3129 : 0 : return;
3130 : : }
3131 : 610 : bh->b_end_io = end_buffer_write_sync;
3132 : : get_bh(bh);
3133 : : submit_bh(rw, bh);
3134 : : }
3135 : : EXPORT_SYMBOL(write_dirty_buffer);
3136 : :
3137 : : /*
3138 : : * For a data-integrity writeout, we need to wait upon any in-progress I/O
3139 : : * and then start new I/O and then wait upon it. The caller must have a ref on
3140 : : * the buffer_head.
3141 : : */
3142 : 0 : int __sync_dirty_buffer(struct buffer_head *bh, int rw)
3143 : : {
3144 : : int ret = 0;
3145 : :
3146 [ # # ]: 0 : WARN_ON(atomic_read(&bh->b_count) < 1);
3147 : : lock_buffer(bh);
3148 [ # # ]: 0 : if (test_clear_buffer_dirty(bh)) {
3149 : : get_bh(bh);
3150 : 0 : bh->b_end_io = end_buffer_write_sync;
3151 : : ret = submit_bh(rw, bh);
3152 : : wait_on_buffer(bh);
3153 [ # # ][ # # ]: 0 : if (!ret && !buffer_uptodate(bh))
3154 : : ret = -EIO;
3155 : : } else {
3156 : 0 : unlock_buffer(bh);
3157 : : }
3158 : 0 : return ret;
3159 : : }
3160 : : EXPORT_SYMBOL(__sync_dirty_buffer);
3161 : :
3162 : 0 : int sync_dirty_buffer(struct buffer_head *bh)
3163 : : {
3164 : 0 : return __sync_dirty_buffer(bh, WRITE_SYNC);
3165 : : }
3166 : : EXPORT_SYMBOL(sync_dirty_buffer);
3167 : :
3168 : : /*
3169 : : * try_to_free_buffers() checks if all the buffers on this particular page
3170 : : * are unused, and releases them if so.
3171 : : *
3172 : : * Exclusion against try_to_free_buffers may be obtained by either
3173 : : * locking the page or by holding its mapping's private_lock.
3174 : : *
3175 : : * If the page is dirty but all the buffers are clean then we need to
3176 : : * be sure to mark the page clean as well. This is because the page
3177 : : * may be against a block device, and a later reattachment of buffers
3178 : : * to a dirty page will set *all* buffers dirty. Which would corrupt
3179 : : * filesystem data on the same device.
3180 : : *
3181 : : * The same applies to regular filesystem pages: if all the buffers are
3182 : : * clean then we set the page clean and proceed. To do that, we require
3183 : : * total exclusion from __set_page_dirty_buffers(). That is obtained with
3184 : : * private_lock.
3185 : : *
3186 : : * try_to_free_buffers() is non-blocking.
3187 : : */
3188 : : static inline int buffer_busy(struct buffer_head *bh)
3189 : : {
3190 : 3858036 : return atomic_read(&bh->b_count) |
3191 : 1929018 : (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3192 : : }
3193 : :
3194 : : static int
3195 : 0 : drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3196 : : {
3197 [ - + ]: 1929030 : struct buffer_head *head = page_buffers(page);
3198 : : struct buffer_head *bh;
3199 : :
3200 : : bh = head;
3201 : : do {
3202 [ - + ][ # # ]: 1929031 : if (buffer_write_io_error(bh) && page->mapping)
3203 : 0 : set_bit(AS_EIO, &page->mapping->flags);
3204 [ + + ]: 1929018 : if (buffer_busy(bh))
3205 : : goto failed;
3206 : 1913315 : bh = bh->b_this_page;
3207 [ + + ]: 1913315 : } while (bh != head);
3208 : :
3209 : : do {
3210 : 1913317 : struct buffer_head *next = bh->b_this_page;
3211 : :
3212 [ - + ]: 1913317 : if (bh->b_assoc_map)
3213 : 0 : __remove_assoc_queue(bh);
3214 : : bh = next;
3215 [ + + ]: 1913321 : } while (bh != head);
3216 : 1913318 : *buffers_to_free = head;
3217 : 1913318 : __clear_page_buffers(page);
3218 : 1913325 : return 1;
3219 : : failed:
3220 : : return 0;
3221 : : }
3222 : :
3223 : 0 : int try_to_free_buffers(struct page *page)
3224 : : {
3225 : 1928973 : struct address_space * const mapping = page->mapping;
3226 : 1928973 : struct buffer_head *buffers_to_free = NULL;
3227 : : int ret = 0;
3228 : :
3229 [ - + ]: 1928973 : BUG_ON(!PageLocked(page));
3230 [ + ]: 1928973 : if (PageWriteback(page))
3231 : : return 0;
3232 : :
3233 [ + + ]: 1928996 : if (mapping == NULL) { /* can this still happen? */
3234 : 79 : ret = drop_buffers(page, &buffers_to_free);
3235 : 79 : goto out;
3236 : : }
3237 : :
3238 : : spin_lock(&mapping->private_lock);
3239 : 1928961 : ret = drop_buffers(page, &buffers_to_free);
3240 : :
3241 : : /*
3242 : : * If the filesystem writes its buffers by hand (eg ext3)
3243 : : * then we can have clean buffers against a dirty page. We
3244 : : * clean the page here; otherwise the VM will never notice
3245 : : * that the filesystem did any IO at all.
3246 : : *
3247 : : * Also, during truncate, discard_buffer will have marked all
3248 : : * the page's buffers clean. We discover that here and clean
3249 : : * the page also.
3250 : : *
3251 : : * private_lock must be held over this entire operation in order
3252 : : * to synchronise against __set_page_dirty_buffers and prevent the
3253 : : * dirty bit from being lost.
3254 : : */
3255 [ + + ]: 1928933 : if (ret)
3256 : 1913230 : cancel_dirty_page(page, PAGE_CACHE_SIZE);
3257 : : spin_unlock(&mapping->private_lock);
3258 : : out:
3259 [ + + ]: 3858012 : if (buffers_to_free) {
3260 : : struct buffer_head *bh = buffers_to_free;
3261 : :
3262 : : do {
3263 : 1913338 : struct buffer_head *next = bh->b_this_page;
3264 : 1913338 : free_buffer_head(bh);
3265 : : bh = next;
3266 [ + + ]: 1913332 : } while (bh != buffers_to_free);
3267 : : }
3268 : 1929033 : return ret;
3269 : : }
3270 : : EXPORT_SYMBOL(try_to_free_buffers);
3271 : :
3272 : : /*
3273 : : * There are no bdflush tunables left. But distributions are
3274 : : * still running obsolete flush daemons, so we terminate them here.
3275 : : *
3276 : : * Use of bdflush() is deprecated and will be removed in a future kernel.
3277 : : * The `flush-X' kernel threads fully replace bdflush daemons and this call.
3278 : : */
3279 : 0 : SYSCALL_DEFINE2(bdflush, int, func, long, data)
3280 : : {
3281 : : static int msg_count;
3282 : :
3283 [ + - ]: 1 : if (!capable(CAP_SYS_ADMIN))
3284 : : return -EPERM;
3285 : :
3286 [ + - ]: 1 : if (msg_count < 5) {
3287 : 1 : msg_count++;
3288 : 1 : printk(KERN_INFO
3289 : : "warning: process `%s' used the obsolete bdflush"
3290 : 1 : " system call\n", current->comm);
3291 : 1 : printk(KERN_INFO "Fix your initscripts?\n");
3292 : : }
3293 : :
3294 [ - + ]: 1 : if (func == 1)
3295 : 0 : do_exit(0);
3296 : : return 0;
3297 : : }
3298 : :
3299 : : /*
3300 : : * Buffer-head allocation
3301 : : */
3302 : : static struct kmem_cache *bh_cachep __read_mostly;
3303 : :
3304 : : /*
3305 : : * Once the number of bh's in the machine exceeds this level, we start
3306 : : * stripping them in writeback.
3307 : : */
3308 : : static unsigned long max_buffer_heads;
3309 : :
3310 : : int buffer_heads_over_limit;
3311 : :
3312 : : struct bh_accounting {
3313 : : int nr; /* Number of live bh's */
3314 : : int ratelimit; /* Limit cacheline bouncing */
3315 : : };
3316 : :
3317 : : static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3318 : :
3319 : 0 : static void recalc_bh_state(void)
3320 : : {
3321 : : int i;
3322 : : int tot = 0;
3323 : :
3324 [ + + ]: 3952835 : if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
3325 : 3952835 : return;
3326 : 1930 : __this_cpu_write(bh_accounting.ratelimit, 0);
3327 [ + + ]: 3956695 : for_each_online_cpu(i)
3328 : 1930 : tot += per_cpu(bh_accounting, i).nr;
3329 : 965 : buffer_heads_over_limit = (tot > max_buffer_heads);
3330 : : }
3331 : :
3332 : 0 : struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
3333 : : {
3334 : 1968873 : struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
3335 [ + + ]: 1969165 : if (ret) {
3336 : 1969047 : INIT_LIST_HEAD(&ret->b_assoc_buffers);
3337 : 1969047 : preempt_disable();
3338 : 3937996 : __this_cpu_inc(bh_accounting.nr);
3339 : 1968998 : recalc_bh_state();
3340 : 1969099 : preempt_enable();
3341 : : }
3342 : 399 : return ret;
3343 : : }
3344 : : EXPORT_SYMBOL(alloc_buffer_head);
3345 : :
3346 : 0 : void free_buffer_head(struct buffer_head *bh)
3347 : : {
3348 [ - + ]: 1983743 : BUG_ON(!list_empty(&bh->b_assoc_buffers));
3349 : 1983743 : kmem_cache_free(bh_cachep, bh);
3350 : 1983738 : preempt_disable();
3351 : 3967478 : __this_cpu_dec(bh_accounting.nr);
3352 : 1983739 : recalc_bh_state();
3353 : 1983738 : preempt_enable();
3354 : 1983736 : }
3355 : : EXPORT_SYMBOL(free_buffer_head);
3356 : :
3357 : 0 : static void buffer_exit_cpu(int cpu)
3358 : : {
3359 : : int i;
3360 : 0 : struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3361 : :
3362 [ # # ]: 0 : for (i = 0; i < BH_LRU_SIZE; i++) {
3363 : 0 : brelse(b->bhs[i]);
3364 : 0 : b->bhs[i] = NULL;
3365 : : }
3366 : 0 : this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
3367 : 0 : per_cpu(bh_accounting, cpu).nr = 0;
3368 : 0 : }
3369 : :
3370 : 0 : static int buffer_cpu_notify(struct notifier_block *self,
3371 : : unsigned long action, void *hcpu)
3372 : : {
3373 [ # # ]: 0 : if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
3374 : 0 : buffer_exit_cpu((unsigned long)hcpu);
3375 : 0 : return NOTIFY_OK;
3376 : : }
3377 : :
3378 : : /**
3379 : : * bh_uptodate_or_lock - Test whether the buffer is uptodate
3380 : : * @bh: struct buffer_head
3381 : : *
3382 : : * Return true if the buffer is up-to-date and false,
3383 : : * with the buffer locked, if not.
3384 : : */
3385 : 0 : int bh_uptodate_or_lock(struct buffer_head *bh)
3386 : : {
3387 [ + + ]: 347271 : if (!buffer_uptodate(bh)) {
3388 : : lock_buffer(bh);
3389 [ - + ]: 8 : if (!buffer_uptodate(bh))
3390 : : return 0;
3391 : 0 : unlock_buffer(bh);
3392 : : }
3393 : : return 1;
3394 : : }
3395 : : EXPORT_SYMBOL(bh_uptodate_or_lock);
3396 : :
3397 : : /**
3398 : : * bh_submit_read - Submit a locked buffer for reading
3399 : : * @bh: struct buffer_head
3400 : : *
3401 : : * Returns zero on success and -EIO on error.
3402 : : */
3403 : 0 : int bh_submit_read(struct buffer_head *bh)
3404 : : {
3405 [ - + ]: 8 : BUG_ON(!buffer_locked(bh));
3406 : :
3407 [ - + ]: 8 : if (buffer_uptodate(bh)) {
3408 : 0 : unlock_buffer(bh);
3409 : 0 : return 0;
3410 : : }
3411 : :
3412 : : get_bh(bh);
3413 : 8 : bh->b_end_io = end_buffer_read_sync;
3414 : : submit_bh(READ, bh);
3415 : : wait_on_buffer(bh);
3416 [ - + ]: 16 : if (buffer_uptodate(bh))
3417 : : return 0;
3418 : 0 : return -EIO;
3419 : : }
3420 : : EXPORT_SYMBOL(bh_submit_read);
3421 : :
3422 : 0 : void __init buffer_init(void)
3423 : : {
3424 : : unsigned long nrpages;
3425 : :
3426 : 0 : bh_cachep = kmem_cache_create("buffer_head",
3427 : : sizeof(struct buffer_head), 0,
3428 : : (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3429 : : SLAB_MEM_SPREAD),
3430 : : NULL);
3431 : :
3432 : : /*
3433 : : * Limit the bh occupancy to 10% of ZONE_NORMAL
3434 : : */
3435 : 0 : nrpages = (nr_free_buffer_pages() * 10) / 100;
3436 : 0 : max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3437 : 0 : hotcpu_notifier(buffer_cpu_notify, 0);
3438 : 0 : }
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