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 : 55318 : bh->b_end_io = handler;
53 : 55318 : 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 : 10867480 : 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 : 41447 : io_schedule();
67 : 41447 : return 0;
68 : : }
69 : :
70 : 0 : void __lock_buffer(struct buffer_head *bh)
71 : : {
72 : 17593 : wait_on_bit_lock(&bh->b_state, BH_Lock, sleep_on_buffer,
73 : : TASK_UNINTERRUPTIBLE);
74 : 0 : }
75 : : EXPORT_SYMBOL(__lock_buffer);
76 : :
77 : 0 : void unlock_buffer(struct buffer_head *bh)
78 : : {
79 : 14389572 : clear_bit_unlock(BH_Lock, &bh->b_state);
80 : 14394799 : smp_mb__after_clear_bit();
81 : 14390937 : wake_up_bit(&bh->b_state, BH_Lock);
82 : 14388812 : }
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 : 51734 : *dirty = false;
95 : 51734 : *writeback = false;
96 : :
97 [ - + ]: 51734 : BUG_ON(!PageLocked(page));
98 : :
99 [ + ]: 51734 : if (!page_has_buffers(page))
100 : 0 : return;
101 : :
102 [ + + ]: 51735 : if (PageWriteback(page))
103 : 1033 : *writeback = true;
104 : :
105 : : head = page_buffers(page);
106 : : bh = head;
107 : : do {
108 [ + + ]: 51735 : if (buffer_locked(bh))
109 : 1033 : *writeback = true;
110 : :
111 [ + + ]: 51735 : if (buffer_dirty(bh))
112 : 6 : *dirty = true;
113 : :
114 : 51735 : bh = bh->b_this_page;
115 [ - + ]: 51735 : } 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 : 39641 : 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 : 1823844 : set_page_private(page, 0);
135 : 1823844 : page_cache_release(page);
136 : 1823796 : }
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 [ + - ]: 7473 : if (uptodate) {
166 : : set_buffer_uptodate(bh);
167 : : } else {
168 : : /* This happens, due to failed READA attempts. */
169 : : clear_buffer_uptodate(bh);
170 : : }
171 : 7473 : unlock_buffer(bh);
172 : 7473 : }
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 : 7473 : __end_buffer_read_notouch(bh, uptodate);
181 : : put_bh(bh);
182 : 7473 : }
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 [ + - ]: 632 : 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 : 632 : unlock_buffer(bh);
202 : : put_bh(bh);
203 : 632 : }
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 : 2864563 : struct inode *bd_inode = bdev->bd_inode;
221 : 2864563 : 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 : 2864563 : index = block >> (PAGE_CACHE_SHIFT - bd_inode->i_blkbits);
230 : 2864563 : page = find_get_page(bd_mapping, index);
231 [ + + ]: 2864154 : if (!page)
232 : : goto out;
233 : :
234 : : spin_lock(&bd_mapping->private_lock);
235 [ + ]: 237965 : if (!page_has_buffers(page))
236 : : goto out_unlock;
237 [ - + ]: 3102525 : head = page_buffers(page);
238 : : bh = head;
239 : : do {
240 [ + - ]: 238205 : if (!buffer_mapped(bh))
241 : : all_mapped = 0;
242 [ + + ]: 238205 : else if (bh->b_blocknr == block) {
243 : : ret = bh;
244 : : get_bh(bh);
245 : : goto out_unlock;
246 : : }
247 : 243 : bh = bh->b_this_page;
248 [ + - ]: 243 : } 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 : 237965 : page_cache_release(page);
270 : : out:
271 : 2864191 : 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 [ - + ]: 2360 : BUG_ON(!buffer_async_read(bh));
308 : :
309 : 2360 : page = bh->b_page;
310 [ + - ]: 2360 : 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 [ - + ]: 2360 : first = page_buffers(page);
325 : : local_irq_save(flags);
326 : 2360 : bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
327 : : clear_buffer_async_read(bh);
328 : 2360 : unlock_buffer(bh);
329 : : tmp = bh;
330 : : do {
331 [ + + ]: 6940 : if (!buffer_uptodate(tmp))
332 : : page_uptodate = 0;
333 [ + + ]: 4580 : if (buffer_async_read(tmp)) {
334 [ - + ]: 1084 : BUG_ON(!buffer_locked(tmp));
335 : : goto still_busy;
336 : : }
337 : 3496 : tmp = tmp->b_this_page;
338 [ + + ]: 3496 : } while (tmp != bh);
339 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
340 [ - + ]: 1276 : 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 [ + - ][ + - ]: 1276 : if (page_uptodate && !PageError(page))
347 : : SetPageUptodate(page);
348 : 1276 : unlock_page(page);
349 : 1276 : return;
350 : :
351 : : still_busy:
352 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
353 [ - + ]: 1084 : 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 [ - + ]: 18071 : BUG_ON(!buffer_async_write(bh));
370 : :
371 : 18071 : page = bh->b_page;
372 [ + - ]: 18071 : 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 [ - + ]: 18071 : first = page_buffers(page);
388 : : local_irq_save(flags);
389 : 18071 : bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
390 : :
391 : : clear_buffer_async_write(bh);
392 : 18071 : unlock_buffer(bh);
393 : 18071 : tmp = bh->b_this_page;
394 [ + + ]: 18206 : while (tmp != bh) {
395 [ + + ]: 162 : if (buffer_async_write(tmp)) {
396 [ - + ]: 27 : BUG_ON(!buffer_locked(tmp));
397 : : goto still_busy;
398 : : }
399 : 135 : tmp = tmp->b_this_page;
400 : : }
401 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
402 [ - + ]: 18044 : local_irq_restore(flags);
403 : 18044 : end_page_writeback(page);
404 : 18044 : return;
405 : :
406 : : still_busy:
407 : : bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
408 [ - + ]: 27 : 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 : 2360 : 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 : 18071 : 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 : 3665625 : 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 : 1 : struct address_space *buffer_mapping = mapping->private_data;
600 : :
601 [ - + ][ # # ]: 1 : 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 : : unsigned long flags;
658 : :
659 : 2072754 : spin_lock_irqsave(&mapping->tree_lock, flags);
660 [ + ]: 2074364 : if (page->mapping) { /* Race with truncate? */
661 [ - + ][ - + ]: 2074731 : WARN_ON_ONCE(warn && !PageUptodate(page));
[ - + ][ # # ]
[ # # ]
662 : 2074731 : account_page_dirtied(page, mapping);
663 : 2073609 : radix_tree_tag_set(&mapping->page_tree,
664 : : page_index(page), PAGECACHE_TAG_DIRTY);
665 : : }
666 : : spin_unlock_irqrestore(&mapping->tree_lock, flags);
667 : 2075517 : __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
668 : 2073420 : }
669 : :
670 : : /*
671 : : * Add a page to the dirty page list.
672 : : *
673 : : * It is a sad fact of life that this function is called from several places
674 : : * deeply under spinlocking. It may not sleep.
675 : : *
676 : : * If the page has buffers, the uptodate buffers are set dirty, to preserve
677 : : * dirty-state coherency between the page and the buffers. It the page does
678 : : * not have buffers then when they are later attached they will all be set
679 : : * dirty.
680 : : *
681 : : * The buffers are dirtied before the page is dirtied. There's a small race
682 : : * window in which a writepage caller may see the page cleanness but not the
683 : : * buffer dirtiness. That's fine. If this code were to set the page dirty
684 : : * before the buffers, a concurrent writepage caller could clear the page dirty
685 : : * bit, see a bunch of clean buffers and we'd end up with dirty buffers/clean
686 : : * page on the dirty page list.
687 : : *
688 : : * We use private_lock to lock against try_to_free_buffers while using the
689 : : * page's buffer list. Also use this to protect against clean buffers being
690 : : * added to the page after it was set dirty.
691 : : *
692 : : * FIXME: may need to call ->reservepage here as well. That's rather up to the
693 : : * address_space though.
694 : : */
695 : 0 : int __set_page_dirty_buffers(struct page *page)
696 : : {
697 : : int newly_dirty;
698 : 616008 : struct address_space *mapping = page_mapping(page);
699 : :
700 [ - + ]: 616513 : if (unlikely(!mapping))
701 : 0 : return !TestSetPageDirty(page);
702 : :
703 : : spin_lock(&mapping->private_lock);
704 [ + - ]: 616797 : if (page_has_buffers(page)) {
705 [ - + ]: 616797 : struct buffer_head *head = page_buffers(page);
706 : : struct buffer_head *bh = head;
707 : :
708 : : do {
709 : : set_buffer_dirty(bh);
710 : 616797 : bh = bh->b_this_page;
711 [ - + ]: 616797 : } while (bh != head);
712 : : }
713 : 616797 : newly_dirty = !TestSetPageDirty(page);
714 : : spin_unlock(&mapping->private_lock);
715 : :
716 [ - + ]: 616797 : if (newly_dirty)
717 : 0 : __set_page_dirty(page, mapping, 1);
718 : 616797 : return newly_dirty;
719 : : }
720 : : EXPORT_SYMBOL(__set_page_dirty_buffers);
721 : :
722 : : /*
723 : : * Write out and wait upon a list of buffers.
724 : : *
725 : : * We have conflicting pressures: we want to make sure that all
726 : : * initially dirty buffers get waited on, but that any subsequently
727 : : * dirtied buffers don't. After all, we don't want fsync to last
728 : : * forever if somebody is actively writing to the file.
729 : : *
730 : : * Do this in two main stages: first we copy dirty buffers to a
731 : : * temporary inode list, queueing the writes as we go. Then we clean
732 : : * up, waiting for those writes to complete.
733 : : *
734 : : * During this second stage, any subsequent updates to the file may end
735 : : * up refiling the buffer on the original inode's dirty list again, so
736 : : * there is a chance we will end up with a buffer queued for write but
737 : : * not yet completed on that list. So, as a final cleanup we go through
738 : : * the osync code to catch these locked, dirty buffers without requeuing
739 : : * any newly dirty buffers for write.
740 : : */
741 : 0 : static int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
742 : : {
743 : : struct buffer_head *bh;
744 : : struct list_head tmp;
745 : : struct address_space *mapping;
746 : : int err = 0, err2;
747 : : struct blk_plug plug;
748 : :
749 : : INIT_LIST_HEAD(&tmp);
750 : 0 : blk_start_plug(&plug);
751 : :
752 : : spin_lock(lock);
753 [ # # ]: 0 : while (!list_empty(list)) {
754 : 0 : bh = BH_ENTRY(list->next);
755 : 0 : mapping = bh->b_assoc_map;
756 : 0 : __remove_assoc_queue(bh);
757 : : /* Avoid race with mark_buffer_dirty_inode() which does
758 : : * a lockless check and we rely on seeing the dirty bit */
759 : 0 : smp_mb();
760 [ # # ][ # # ]: 0 : if (buffer_dirty(bh) || buffer_locked(bh)) {
761 : 0 : list_add(&bh->b_assoc_buffers, &tmp);
762 : 0 : bh->b_assoc_map = mapping;
763 [ # # ]: 0 : if (buffer_dirty(bh)) {
764 : : get_bh(bh);
765 : : spin_unlock(lock);
766 : : /*
767 : : * Ensure any pending I/O completes so that
768 : : * write_dirty_buffer() actually writes the
769 : : * current contents - it is a noop if I/O is
770 : : * still in flight on potentially older
771 : : * contents.
772 : : */
773 : 0 : write_dirty_buffer(bh, WRITE_SYNC);
774 : :
775 : : /*
776 : : * Kick off IO for the previous mapping. Note
777 : : * that we will not run the very last mapping,
778 : : * wait_on_buffer() will do that for us
779 : : * through sync_buffer().
780 : : */
781 : : brelse(bh);
782 : : spin_lock(lock);
783 : : }
784 : : }
785 : : }
786 : :
787 : : spin_unlock(lock);
788 : 0 : blk_finish_plug(&plug);
789 : : spin_lock(lock);
790 : :
791 [ # # ]: 0 : while (!list_empty(&tmp)) {
792 : 0 : bh = BH_ENTRY(tmp.prev);
793 : : get_bh(bh);
794 : 0 : mapping = bh->b_assoc_map;
795 : 0 : __remove_assoc_queue(bh);
796 : : /* Avoid race with mark_buffer_dirty_inode() which does
797 : : * a lockless check and we rely on seeing the dirty bit */
798 : 0 : smp_mb();
799 [ # # ]: 0 : if (buffer_dirty(bh)) {
800 : 0 : list_add(&bh->b_assoc_buffers,
801 : : &mapping->private_list);
802 : 0 : bh->b_assoc_map = mapping;
803 : : }
804 : : spin_unlock(lock);
805 : : wait_on_buffer(bh);
806 [ # # ]: 0 : if (!buffer_uptodate(bh))
807 : : err = -EIO;
808 : : brelse(bh);
809 : : spin_lock(lock);
810 : : }
811 : :
812 : : spin_unlock(lock);
813 : 0 : err2 = osync_buffers_list(lock, list);
814 [ # # ]: 0 : if (err)
815 : : return err;
816 : : else
817 : 0 : return err2;
818 : : }
819 : :
820 : : /*
821 : : * Invalidate any and all dirty buffers on a given inode. We are
822 : : * probably unmounting the fs, but that doesn't mean we have already
823 : : * done a sync(). Just drop the buffers from the inode list.
824 : : *
825 : : * NOTE: we take the inode's blockdev's mapping's private_lock. Which
826 : : * assumes that all the buffers are against the blockdev. Not true
827 : : * for reiserfs.
828 : : */
829 : 0 : void invalidate_inode_buffers(struct inode *inode)
830 : : {
831 [ - + ]: 275073 : if (inode_has_buffers(inode)) {
832 : : struct address_space *mapping = &inode->i_data;
833 : : struct list_head *list = &mapping->private_list;
834 : 0 : struct address_space *buffer_mapping = mapping->private_data;
835 : :
836 : : spin_lock(&buffer_mapping->private_lock);
837 [ # # ]: 0 : while (!list_empty(list))
838 : 0 : __remove_assoc_queue(BH_ENTRY(list->next));
839 : : spin_unlock(&buffer_mapping->private_lock);
840 : : }
841 : 0 : }
842 : : EXPORT_SYMBOL(invalidate_inode_buffers);
843 : :
844 : : /*
845 : : * Remove any clean buffers from the inode's buffer list. This is called
846 : : * when we're trying to free the inode itself. Those buffers can pin it.
847 : : *
848 : : * Returns true if all buffers were removed.
849 : : */
850 : 0 : int remove_inode_buffers(struct inode *inode)
851 : : {
852 : : int ret = 1;
853 : :
854 [ - + ]: 160 : if (inode_has_buffers(inode)) {
855 : : struct address_space *mapping = &inode->i_data;
856 : : struct list_head *list = &mapping->private_list;
857 : 0 : struct address_space *buffer_mapping = mapping->private_data;
858 : :
859 : : spin_lock(&buffer_mapping->private_lock);
860 [ # # ]: 0 : while (!list_empty(list)) {
861 : 0 : struct buffer_head *bh = BH_ENTRY(list->next);
862 [ # # ]: 0 : if (buffer_dirty(bh)) {
863 : : ret = 0;
864 : : break;
865 : : }
866 : 0 : __remove_assoc_queue(bh);
867 : : }
868 : : spin_unlock(&buffer_mapping->private_lock);
869 : : }
870 : 160 : return ret;
871 : : }
872 : :
873 : : /*
874 : : * Create the appropriate buffers when given a page for data area and
875 : : * the size of each buffer.. Use the bh->b_this_page linked list to
876 : : * follow the buffers created. Return NULL if unable to create more
877 : : * buffers.
878 : : *
879 : : * The retry flag is used to differentiate async IO (paging, swapping)
880 : : * which may not fail from ordinary buffer allocations.
881 : : */
882 : 1827127 : struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
883 : : int retry)
884 : : {
885 : : struct buffer_head *bh, *head;
886 : : long offset;
887 : :
888 : : try_again:
889 : : head = NULL;
890 : : offset = PAGE_SIZE;
891 [ + + ]: 3657244 : while ((offset -= size) >= 0) {
892 : 1828312 : bh = alloc_buffer_head(GFP_NOFS);
893 [ + - ]: 1830817 : if (!bh)
894 : : goto no_grow;
895 : :
896 : 1830817 : bh->b_this_page = head;
897 : 1830817 : bh->b_blocknr = -1;
898 : : head = bh;
899 : :
900 : 1830817 : bh->b_size = size;
901 : :
902 : : /* Link the buffer to its page */
903 : 1830817 : set_bh_page(bh, page, offset);
904 : : }
905 : : return head;
906 : : /*
907 : : * In case anything failed, we just free everything we got.
908 : : */
909 : : no_grow:
910 [ # # ]: 0 : if (head) {
911 : : do {
912 : : bh = head;
913 : 0 : head = head->b_this_page;
914 : 0 : free_buffer_head(bh);
915 [ # # ]: 0 : } while (head);
916 : : }
917 : :
918 : : /*
919 : : * Return failure for non-async IO requests. Async IO requests
920 : : * are not allowed to fail, so we have to wait until buffer heads
921 : : * become available. But we don't want tasks sleeping with
922 : : * partially complete buffers, so all were released above.
923 : : */
924 [ # # ]: 0 : if (!retry)
925 : : return NULL;
926 : :
927 : : /* We're _really_ low on memory. Now we just
928 : : * wait for old buffer heads to become free due to
929 : : * finishing IO. Since this is an async request and
930 : : * the reserve list is empty, we're sure there are
931 : : * async buffer heads in use.
932 : : */
933 : 0 : free_more_memory();
934 : 0 : goto try_again;
935 : : }
936 : : EXPORT_SYMBOL_GPL(alloc_page_buffers);
937 : :
938 : : static inline void
939 : : link_dev_buffers(struct page *page, struct buffer_head *head)
940 : : {
941 : : struct buffer_head *bh, *tail;
942 : :
943 : : bh = head;
944 : : do {
945 : : tail = bh;
946 : 55318 : bh = bh->b_this_page;
947 [ + + ]: 55318 : } while (bh);
948 : 55114 : tail->b_this_page = head;
949 : : attach_page_buffers(page, head);
950 : : }
951 : :
952 : 0 : static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
953 : : {
954 : : sector_t retval = ~((sector_t)0);
955 : 55118 : loff_t sz = i_size_read(bdev->bd_inode);
956 : :
957 [ + ]: 55118 : if (sz) {
958 : : unsigned int sizebits = blksize_bits(size);
959 : 55118 : retval = (sz >> sizebits);
960 : : }
961 : 0 : return retval;
962 : : }
963 : :
964 : : /*
965 : : * Initialise the state of a blockdev page's buffers.
966 : : */
967 : : static sector_t
968 : 0 : init_page_buffers(struct page *page, struct block_device *bdev,
969 : : sector_t block, int size)
970 : : {
971 [ - + ]: 55118 : struct buffer_head *head = page_buffers(page);
972 : : struct buffer_head *bh = head;
973 : : int uptodate = PageUptodate(page);
974 : 55118 : sector_t end_block = blkdev_max_block(I_BDEV(bdev->bd_inode), size);
975 : :
976 : : do {
977 [ + + ]: 110440 : if (!buffer_mapped(bh)) {
978 : : init_buffer(bh, NULL, NULL);
979 : 55318 : bh->b_bdev = bdev;
980 : 55318 : bh->b_blocknr = block;
981 [ - + ]: 55318 : if (uptodate)
982 : : set_buffer_uptodate(bh);
983 [ + - ]: 55318 : if (block < end_block)
984 : : set_buffer_mapped(bh);
985 : : }
986 : 55322 : block++;
987 : 55322 : bh = bh->b_this_page;
988 [ + + ]: 55322 : } while (bh != head);
989 : :
990 : : /*
991 : : * Caller needs to validate requested block against end of device.
992 : : */
993 : 55118 : return end_block;
994 : : }
995 : :
996 : : /*
997 : : * Create the page-cache page that contains the requested block.
998 : : *
999 : : * This is used purely for blockdev mappings.
1000 : : */
1001 : : static int
1002 : 0 : grow_dev_page(struct block_device *bdev, sector_t block,
1003 : : pgoff_t index, int size, int sizebits)
1004 : : {
1005 : 55102 : struct inode *inode = bdev->bd_inode;
1006 : : struct page *page;
1007 : : struct buffer_head *bh;
1008 : : sector_t end_block;
1009 : : int ret = 0; /* Will call free_more_memory() */
1010 : : gfp_t gfp_mask;
1011 : :
1012 : 110204 : gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS;
1013 : : gfp_mask |= __GFP_MOVABLE;
1014 : : /*
1015 : : * XXX: __getblk_slow() can not really deal with failure and
1016 : : * will endlessly loop on improvised global reclaim. Prefer
1017 : : * looping in the allocator rather than here, at least that
1018 : : * code knows what it's doing.
1019 : : */
1020 : 55102 : gfp_mask |= __GFP_NOFAIL;
1021 : :
1022 : 55102 : page = find_or_create_page(inode->i_mapping, index, gfp_mask);
1023 [ + - ]: 55118 : if (!page)
1024 : : return ret;
1025 : :
1026 [ - + ]: 55118 : BUG_ON(!PageLocked(page));
1027 : :
1028 [ + + ]: 55118 : if (page_has_buffers(page)) {
1029 [ - + ]: 4 : bh = page_buffers(page);
1030 [ + - ]: 4 : if (bh->b_size == size) {
1031 : 4 : end_block = init_page_buffers(page, bdev,
1032 : 4 : index << sizebits, size);
1033 : 4 : goto done;
1034 : : }
1035 [ # # ]: 0 : if (!try_to_free_buffers(page))
1036 : : goto failed;
1037 : : }
1038 : :
1039 : : /*
1040 : : * Allocate some buffers for this page
1041 : : */
1042 : 55114 : bh = alloc_page_buffers(page, size, 0);
1043 [ + - ]: 55075 : if (!bh)
1044 : : goto failed;
1045 : :
1046 : : /*
1047 : : * Link the page to the buffers and initialise them. Take the
1048 : : * lock to be atomic wrt __find_get_block(), which does not
1049 : : * run under the page lock.
1050 : : */
1051 : 55075 : spin_lock(&inode->i_mapping->private_lock);
1052 : : link_dev_buffers(page, bh);
1053 : 55114 : end_block = init_page_buffers(page, bdev, index << sizebits, size);
1054 : 55114 : spin_unlock(&inode->i_mapping->private_lock);
1055 : : done:
1056 [ - + ]: 55118 : ret = (block < end_block) ? 1 : -ENXIO;
1057 : : failed:
1058 : 55118 : unlock_page(page);
1059 : 55118 : page_cache_release(page);
1060 : 55118 : return ret;
1061 : : }
1062 : :
1063 : : /*
1064 : : * Create buffers for the specified block device block's page. If
1065 : : * that page was dirty, the buffers are set dirty also.
1066 : : */
1067 : : static int
1068 : 55096 : grow_buffers(struct block_device *bdev, sector_t block, int size)
1069 : : {
1070 : : pgoff_t index;
1071 : : int sizebits;
1072 : :
1073 : : sizebits = -1;
1074 : : do {
1075 : 55232 : sizebits++;
1076 [ + + ]: 55232 : } while ((size << sizebits) < PAGE_SIZE);
1077 : :
1078 : 55096 : index = block >> sizebits;
1079 : :
1080 : : /*
1081 : : * Check for a block which wants to lie outside our maximum possible
1082 : : * pagecache index. (this comparison is done using sector_t types).
1083 : : */
1084 [ - + ]: 55096 : if (unlikely(index != block >> sizebits)) {
1085 : : char b[BDEVNAME_SIZE];
1086 : :
1087 : 0 : printk(KERN_ERR "%s: requested out-of-range block %llu for "
1088 : : "device %s\n",
1089 : : __func__, (unsigned long long)block,
1090 : : bdevname(bdev, b));
1091 : : return -EIO;
1092 : : }
1093 : :
1094 : : /* Create a page with the proper size buffers.. */
1095 : 55096 : return grow_dev_page(bdev, block, index, size, sizebits);
1096 : : }
1097 : :
1098 : : static struct buffer_head *
1099 : 0 : __getblk_slow(struct block_device *bdev, sector_t block, int size)
1100 : : {
1101 : : /* Size must be multiple of hard sectorsize */
1102 [ + ][ + + ]: 55063 : if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
1103 : : (size < 512 || size > PAGE_SIZE))) {
1104 : 58 : printk(KERN_ERR "getblk(): invalid block size %d requested\n",
1105 : : size);
1106 : 0 : printk(KERN_ERR "logical block size: %d\n",
1107 : : bdev_logical_block_size(bdev));
1108 : :
1109 : 55007 : dump_stack();
1110 : 0 : return NULL;
1111 : : }
1112 : :
1113 : : for (;;) {
1114 : : struct buffer_head *bh;
1115 : : int ret;
1116 : :
1117 : 110125 : bh = __find_get_block(bdev, block, size);
1118 [ + + ]: 110223 : if (bh)
1119 : : return bh;
1120 : :
1121 : 55111 : ret = grow_buffers(bdev, block, size);
1122 [ + - ]: 55118 : if (ret < 0)
1123 : : return NULL;
1124 [ + - ]: 55118 : if (ret == 0)
1125 : 0 : free_more_memory();
1126 : : }
1127 : : }
1128 : :
1129 : : /*
1130 : : * The relationship between dirty buffers and dirty pages:
1131 : : *
1132 : : * Whenever a page has any dirty buffers, the page's dirty bit is set, and
1133 : : * the page is tagged dirty in its radix tree.
1134 : : *
1135 : : * At all times, the dirtiness of the buffers represents the dirtiness of
1136 : : * subsections of the page. If the page has buffers, the page dirty bit is
1137 : : * merely a hint about the true dirty state.
1138 : : *
1139 : : * When a page is set dirty in its entirety, all its buffers are marked dirty
1140 : : * (if the page has buffers).
1141 : : *
1142 : : * When a buffer is marked dirty, its page is dirtied, but the page's other
1143 : : * buffers are not.
1144 : : *
1145 : : * Also. When blockdev buffers are explicitly read with bread(), they
1146 : : * individually become uptodate. But their backing page remains not
1147 : : * uptodate - even if all of its buffers are uptodate. A subsequent
1148 : : * block_read_full_page() against that page will discover all the uptodate
1149 : : * buffers, will set the page uptodate and will perform no I/O.
1150 : : */
1151 : :
1152 : : /**
1153 : : * mark_buffer_dirty - mark a buffer_head as needing writeout
1154 : : * @bh: the buffer_head to mark dirty
1155 : : *
1156 : : * mark_buffer_dirty() will set the dirty bit against the buffer, then set its
1157 : : * backing page dirty, then tag the page as dirty in its address_space's radix
1158 : : * tree and then attach the address_space's inode to its superblock's dirty
1159 : : * inode list.
1160 : : *
1161 : : * mark_buffer_dirty() is atomic. It takes bh->b_page->mapping->private_lock,
1162 : : * mapping->tree_lock and mapping->host->i_lock.
1163 : : */
1164 : 0 : void mark_buffer_dirty(struct buffer_head *bh)
1165 : : {
1166 [ - + ][ # # ]: 6671904 : WARN_ON_ONCE(!buffer_uptodate(bh));
[ - + ]
1167 : :
1168 : : trace_block_dirty_buffer(bh);
1169 : :
1170 : : /*
1171 : : * Very *carefully* optimize the it-is-already-dirty case.
1172 : : *
1173 : : * Don't let the final "is it dirty" escape to before we
1174 : : * perhaps modified the buffer.
1175 : : */
1176 [ + + ]: 6673515 : if (buffer_dirty(bh)) {
1177 : 4573482 : smp_mb();
1178 [ - + ]: 4572134 : if (buffer_dirty(bh))
1179 : 6672006 : return;
1180 : : }
1181 : :
1182 [ + + ]: 2100094 : if (!test_set_buffer_dirty(bh)) {
1183 : 2099069 : struct page *page = bh->b_page;
1184 [ + + ]: 2099699 : if (!TestSetPageDirty(page)) {
1185 : 2074314 : struct address_space *mapping = page_mapping(page);
1186 [ + ]: 2073197 : if (mapping)
1187 : 2073536 : __set_page_dirty(page, mapping, 0);
1188 : : }
1189 : : }
1190 : : }
1191 : : EXPORT_SYMBOL(mark_buffer_dirty);
1192 : :
1193 : : /*
1194 : : * Decrement a buffer_head's reference count. If all buffers against a page
1195 : : * have zero reference count, are clean and unlocked, and if the page is clean
1196 : : * and unlocked then try_to_free_buffers() may strip the buffers from the page
1197 : : * in preparation for freeing it (sometimes, rarely, buffers are removed from
1198 : : * a page but it ends up not being freed, and buffers may later be reattached).
1199 : : */
1200 : 0 : void __brelse(struct buffer_head * buf)
1201 : : {
1202 [ + - ]: 11273059 : if (atomic_read(&buf->b_count)) {
1203 : : put_bh(buf);
1204 : 11276305 : return;
1205 : : }
1206 : 0 : WARN(1, KERN_ERR "VFS: brelse: Trying to free free buffer\n");
1207 : : }
1208 : : EXPORT_SYMBOL(__brelse);
1209 : :
1210 : : /*
1211 : : * bforget() is like brelse(), except it discards any
1212 : : * potentially dirty data.
1213 : : */
1214 : 0 : void __bforget(struct buffer_head *bh)
1215 : : {
1216 : : clear_buffer_dirty(bh);
1217 [ - + ]: 34984 : if (bh->b_assoc_map) {
1218 : 0 : struct address_space *buffer_mapping = bh->b_page->mapping;
1219 : :
1220 : : spin_lock(&buffer_mapping->private_lock);
1221 : 0 : list_del_init(&bh->b_assoc_buffers);
1222 : 0 : bh->b_assoc_map = NULL;
1223 : : spin_unlock(&buffer_mapping->private_lock);
1224 : : }
1225 : 34984 : __brelse(bh);
1226 : 34984 : }
1227 : : EXPORT_SYMBOL(__bforget);
1228 : :
1229 : 0 : static struct buffer_head *__bread_slow(struct buffer_head *bh)
1230 : : {
1231 : : lock_buffer(bh);
1232 [ - + ]: 88 : if (buffer_uptodate(bh)) {
1233 : 0 : unlock_buffer(bh);
1234 : 0 : return bh;
1235 : : } else {
1236 : : get_bh(bh);
1237 : 88 : bh->b_end_io = end_buffer_read_sync;
1238 : : submit_bh(READ, bh);
1239 : : wait_on_buffer(bh);
1240 [ - + ]: 88 : if (buffer_uptodate(bh))
1241 : : return bh;
1242 : : }
1243 : : brelse(bh);
1244 : : return NULL;
1245 : : }
1246 : :
1247 : : /*
1248 : : * Per-cpu buffer LRU implementation. To reduce the cost of __find_get_block().
1249 : : * The bhs[] array is sorted - newest buffer is at bhs[0]. Buffers have their
1250 : : * refcount elevated by one when they're in an LRU. A buffer can only appear
1251 : : * once in a particular CPU's LRU. A single buffer can be present in multiple
1252 : : * CPU's LRUs at the same time.
1253 : : *
1254 : : * This is a transparent caching front-end to sb_bread(), sb_getblk() and
1255 : : * sb_find_get_block().
1256 : : *
1257 : : * The LRUs themselves only need locking against invalidate_bh_lrus. We use
1258 : : * a local interrupt disable for that.
1259 : : */
1260 : :
1261 : : #define BH_LRU_SIZE 8
1262 : :
1263 : : struct bh_lru {
1264 : : struct buffer_head *bhs[BH_LRU_SIZE];
1265 : : };
1266 : :
1267 : : static DEFINE_PER_CPU(struct bh_lru, bh_lrus) = {{ NULL }};
1268 : :
1269 : : #ifdef CONFIG_SMP
1270 : : #define bh_lru_lock() local_irq_disable()
1271 : : #define bh_lru_unlock() local_irq_enable()
1272 : : #else
1273 : : #define bh_lru_lock() preempt_disable()
1274 : : #define bh_lru_unlock() preempt_enable()
1275 : : #endif
1276 : :
1277 : : static inline void check_irqs_on(void)
1278 : : {
1279 : : #ifdef irqs_disabled
1280 [ - + ][ - + ]: 11222505 : BUG_ON(irqs_disabled());
1281 : : #endif
1282 : : }
1283 : :
1284 : : /*
1285 : : * The LRU management algorithm is dopey-but-simple. Sorry.
1286 : : */
1287 : 0 : static void bh_lru_install(struct buffer_head *bh)
1288 : : {
1289 : : struct buffer_head *evictee = NULL;
1290 : :
1291 : : check_irqs_on();
1292 : : bh_lru_lock();
1293 [ + + ]: 236781 : if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
1294 : : struct buffer_head *bhs[BH_LRU_SIZE];
1295 : : int in;
1296 : : int out = 0;
1297 : :
1298 : : get_bh(bh);
1299 : 473526 : bhs[out++] = bh;
1300 [ + + ]: 2367204 : for (in = 0; in < BH_LRU_SIZE; in++) {
1301 : : struct buffer_head *bh2 =
1302 : 3787360 : __this_cpu_read(bh_lrus.bhs[in]);
1303 : :
1304 [ + ]: 1893680 : if (bh2 == bh) {
1305 : 0 : __brelse(bh2);
1306 : : } else {
1307 [ + + ]: 1893826 : if (out >= BH_LRU_SIZE) {
1308 [ - + ]: 236773 : BUG_ON(evictee != NULL);
1309 : : evictee = bh2;
1310 : : } else {
1311 : 1657053 : bhs[out++] = bh2;
1312 : : }
1313 : : }
1314 : : }
1315 [ - + ]: 236755 : while (out < BH_LRU_SIZE)
1316 : 0 : bhs[out++] = NULL;
1317 : 236755 : memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
1318 : : }
1319 : : bh_lru_unlock();
1320 : :
1321 [ + + ]: 236759 : if (evictee)
1322 : 235543 : __brelse(evictee);
1323 : 236733 : }
1324 : :
1325 : : /*
1326 : : * Look up the bh in this cpu's LRU. If it's there, move it to the head.
1327 : : */
1328 : : static struct buffer_head *
1329 : 0 : lookup_bh_lru(struct block_device *bdev, sector_t block, unsigned size)
1330 : : {
1331 : : struct buffer_head *ret = NULL;
1332 : : unsigned int i;
1333 : :
1334 : : check_irqs_on();
1335 : : bh_lru_lock();
1336 [ + + ]: 21725768 : for (i = 0; i < BH_LRU_SIZE; i++) {
1337 : 42703868 : struct buffer_head *bh = __this_cpu_read(bh_lrus.bhs[i]);
1338 : :
1339 [ + ][ + ]: 21351934 : if (bh && bh->b_bdev == bdev &&
[ + + ]
1340 [ + + ]: 10634021 : bh->b_blocknr == block && bh->b_size == size) {
1341 [ + + ]: 10608490 : if (i) {
1342 [ + + ]: 11756682 : while (i) {
1343 : 7938796 : __this_cpu_write(bh_lrus.bhs[i],
1344 : : __this_cpu_read(bh_lrus.bhs[i - 1]));
1345 : : i--;
1346 : : }
1347 : 3817886 : __this_cpu_write(bh_lrus.bhs[0], bh);
1348 : : }
1349 : : get_bh(bh);
1350 : : ret = bh;
1351 : 10633806 : break;
1352 : : }
1353 : : }
1354 : : bh_lru_unlock();
1355 : 10985106 : return ret;
1356 : : }
1357 : :
1358 : : /*
1359 : : * Perform a pagecache lookup for the matching buffer. If it's there, refresh
1360 : : * it in the LRU and mark it as accessed. If it is not present then return
1361 : : * NULL
1362 : : */
1363 : : struct buffer_head *
1364 : 0 : __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
1365 : : {
1366 : 10977181 : struct buffer_head *bh = lookup_bh_lru(bdev, block, size);
1367 : :
1368 [ + + ]: 10986289 : if (bh == NULL) {
1369 : 351850 : bh = __find_get_block_slow(bdev, block);
1370 [ + + ]: 351844 : if (bh)
1371 : 236771 : bh_lru_install(bh);
1372 : : }
1373 [ + + ]: 10982540 : if (bh)
1374 : : touch_buffer(bh);
1375 : 10983041 : return bh;
1376 : : }
1377 : : EXPORT_SYMBOL(__find_get_block);
1378 : :
1379 : : /*
1380 : : * __getblk will locate (and, if necessary, create) the buffer_head
1381 : : * which corresponds to the passed block_device, block and size. The
1382 : : * returned buffer has its reference count incremented.
1383 : : *
1384 : : * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
1385 : : * attempt is failing. FIXME, perhaps?
1386 : : */
1387 : : struct buffer_head *
1388 : 0 : __getblk(struct block_device *bdev, sector_t block, unsigned size)
1389 : : {
1390 : 10768395 : struct buffer_head *bh = __find_get_block(bdev, block, size);
1391 : :
1392 : : might_sleep();
1393 [ + + ]: 10774516 : if (bh == NULL)
1394 : 55054 : bh = __getblk_slow(bdev, block, size);
1395 : 6164 : return bh;
1396 : : }
1397 : : EXPORT_SYMBOL(__getblk);
1398 : :
1399 : : /*
1400 : : * Do async read-ahead on a buffer..
1401 : : */
1402 : 0 : void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
1403 : : {
1404 : 6488 : struct buffer_head *bh = __getblk(bdev, block, size);
1405 [ + - ]: 6488 : if (likely(bh)) {
1406 : 6488 : ll_rw_block(READA, 1, &bh);
1407 : 6488 : brelse(bh);
1408 : : }
1409 : 0 : }
1410 : : EXPORT_SYMBOL(__breadahead);
1411 : :
1412 : : /**
1413 : : * __bread() - reads a specified block and returns the bh
1414 : : * @bdev: the block_device to read from
1415 : : * @block: number of block
1416 : : * @size: size (in bytes) to read
1417 : : *
1418 : : * Reads a specified block, and returns buffer head that contains it.
1419 : : * It returns NULL if the block was unreadable.
1420 : : */
1421 : : struct buffer_head *
1422 : 0 : __bread(struct block_device *bdev, sector_t block, unsigned size)
1423 : : {
1424 : 120 : struct buffer_head *bh = __getblk(bdev, block, size);
1425 : :
1426 [ + - ][ + + ]: 120 : if (likely(bh) && !buffer_uptodate(bh))
1427 : 88 : bh = __bread_slow(bh);
1428 : 0 : return bh;
1429 : : }
1430 : : EXPORT_SYMBOL(__bread);
1431 : :
1432 : : /*
1433 : : * invalidate_bh_lrus() is called rarely - but not only at unmount.
1434 : : * This doesn't race because it runs in each cpu either in irq
1435 : : * or with preempt disabled.
1436 : : */
1437 : 0 : static void invalidate_bh_lru(void *arg)
1438 : : {
1439 : 181 : struct bh_lru *b = &get_cpu_var(bh_lrus);
1440 : : int i;
1441 : :
1442 [ + + ]: 1803 : for (i = 0; i < BH_LRU_SIZE; i++) {
1443 : 1442 : brelse(b->bhs[i]);
1444 : 1441 : b->bhs[i] = NULL;
1445 : : }
1446 : 180 : put_cpu_var(bh_lrus);
1447 : 180 : }
1448 : :
1449 : 0 : static bool has_bh_in_lru(int cpu, void *dummy)
1450 : : {
1451 : 290 : struct bh_lru *b = per_cpu_ptr(&bh_lrus, cpu);
1452 : : int i;
1453 : :
1454 [ + + ]: 1146 : for (i = 0; i < BH_LRU_SIZE; i++) {
1455 [ + + ]: 1039 : if (b->bhs[i])
1456 : : return 1;
1457 : : }
1458 : :
1459 : : return 0;
1460 : : }
1461 : :
1462 : 0 : void invalidate_bh_lrus(void)
1463 : : {
1464 : 58 : on_each_cpu_cond(has_bh_in_lru, invalidate_bh_lru, NULL, 1, GFP_KERNEL);
1465 : 58 : }
1466 : : EXPORT_SYMBOL_GPL(invalidate_bh_lrus);
1467 : :
1468 : 0 : void set_bh_page(struct buffer_head *bh,
1469 : : struct page *page, unsigned long offset)
1470 : : {
1471 : 1881700 : bh->b_page = page;
1472 [ - + ]: 1881700 : BUG_ON(offset >= PAGE_SIZE);
1473 [ + + ]: 1881700 : if (PageHighMem(page))
1474 : : /*
1475 : : * This catches illegal uses and preserves the offset:
1476 : : */
1477 : 1215561 : bh->b_data = (char *)(0 + offset);
1478 : : else
1479 : 666139 : bh->b_data = page_address(page) + offset;
1480 : 1881735 : }
1481 : : EXPORT_SYMBOL(set_bh_page);
1482 : :
1483 : : /*
1484 : : * Called when truncating a buffer on a page completely.
1485 : : */
1486 : 0 : static void discard_buffer(struct buffer_head * bh)
1487 : : {
1488 : : lock_buffer(bh);
1489 : : clear_buffer_dirty(bh);
1490 : 1716552 : bh->b_bdev = NULL;
1491 : : clear_buffer_mapped(bh);
1492 : : clear_buffer_req(bh);
1493 : : clear_buffer_new(bh);
1494 : : clear_buffer_delay(bh);
1495 : : clear_buffer_unwritten(bh);
1496 : 1716544 : unlock_buffer(bh);
1497 : 1716435 : }
1498 : :
1499 : : /**
1500 : : * block_invalidatepage - invalidate part or all of a buffer-backed page
1501 : : *
1502 : : * @page: the page which is affected
1503 : : * @offset: start of the range to invalidate
1504 : : * @length: length of the range to invalidate
1505 : : *
1506 : : * block_invalidatepage() is called when all or part of the page has become
1507 : : * invalidated by a truncate operation.
1508 : : *
1509 : : * block_invalidatepage() does not have to release all buffers, but it must
1510 : : * ensure that no dirty buffer is left outside @offset and that no I/O
1511 : : * is underway against any of the blocks which are outside the truncation
1512 : : * point. Because the caller is about to free (and possibly reuse) those
1513 : : * blocks on-disk.
1514 : : */
1515 : 0 : void block_invalidatepage(struct page *page, unsigned int offset,
1516 : : unsigned int length)
1517 : : {
1518 : : struct buffer_head *head, *bh, *next;
1519 : : unsigned int curr_off = 0;
1520 : 1730770 : unsigned int stop = length + offset;
1521 : :
1522 [ - + ]: 1730770 : BUG_ON(!PageLocked(page));
1523 [ + ]: 1730770 : if (!page_has_buffers(page))
1524 : : goto out;
1525 : :
1526 : : /*
1527 : : * Check for overflow
1528 : : */
1529 [ - + ]: 3461540 : BUG_ON(stop > PAGE_CACHE_SIZE || stop < length);
1530 : :
1531 [ - + ]: 1730770 : head = page_buffers(page);
1532 : : bh = head;
1533 : : do {
1534 : 1732045 : unsigned int next_off = curr_off + bh->b_size;
1535 : 1732045 : next = bh->b_this_page;
1536 : :
1537 : : /*
1538 : : * Are we still fully in range ?
1539 : : */
1540 [ + ]: 1732045 : if (next_off > stop)
1541 : : goto out;
1542 : :
1543 : : /*
1544 : : * is this block fully invalidated?
1545 : : */
1546 [ + + ]: 1732065 : if (offset <= curr_off)
1547 : 1716592 : discard_buffer(bh);
1548 : : curr_off = next_off;
1549 : : bh = next;
1550 [ + + ]: 1731951 : } while (bh != head);
1551 : :
1552 : : /*
1553 : : * We release buffers only if the entire page is being invalidated.
1554 : : * The get_block cached value has been unconditionally invalidated,
1555 : : * so real IO is not possible anymore.
1556 : : */
1557 [ + + ]: 1730676 : if (offset == 0)
1558 : 1715226 : try_to_release_page(page, 0);
1559 : : out:
1560 : 0 : return;
1561 : : }
1562 : : EXPORT_SYMBOL(block_invalidatepage);
1563 : :
1564 : :
1565 : : /*
1566 : : * We attach and possibly dirty the buffers atomically wrt
1567 : : * __set_page_dirty_buffers() via private_lock. try_to_free_buffers
1568 : : * is already excluded via the page lock.
1569 : : */
1570 : 0 : void create_empty_buffers(struct page *page,
1571 : : unsigned long blocksize, unsigned long b_state)
1572 : : {
1573 : : struct buffer_head *bh, *head, *tail;
1574 : :
1575 : 1772285 : head = alloc_page_buffers(page, blocksize, 1);
1576 : : bh = head;
1577 : : do {
1578 : 1775207 : bh->b_state |= b_state;
1579 : : tail = bh;
1580 : 1775207 : bh = bh->b_this_page;
1581 [ + + ]: 1775207 : } while (bh);
1582 : 1774082 : tail->b_this_page = head;
1583 : :
1584 : 1774082 : spin_lock(&page->mapping->private_lock);
1585 [ + + ][ + + ]: 1770641 : if (PageUptodate(page) || PageDirty(page)) {
1586 : : bh = head;
1587 : : do {
1588 [ - + ]: 132029 : if (PageDirty(page))
1589 : : set_buffer_dirty(bh);
1590 [ + ]: 131969 : if (PageUptodate(page))
1591 : : set_buffer_uptodate(bh);
1592 : 132038 : bh = bh->b_this_page;
1593 [ + + ]: 132038 : } while (bh != head);
1594 : : }
1595 : : attach_page_buffers(page, head);
1596 : 1772246 : spin_unlock(&page->mapping->private_lock);
1597 : 1774269 : }
1598 : : EXPORT_SYMBOL(create_empty_buffers);
1599 : :
1600 : : /*
1601 : : * We are taking a block for data and we don't want any output from any
1602 : : * buffer-cache aliases starting from return from that function and
1603 : : * until the moment when something will explicitly mark the buffer
1604 : : * dirty (hopefully that will not happen until we will free that block ;-)
1605 : : * We don't even need to mark it not-uptodate - nobody can expect
1606 : : * anything from a newly allocated buffer anyway. We used to used
1607 : : * unmap_buffer() for such invalidation, but that was wrong. We definitely
1608 : : * don't want to mark the alias unmapped, for example - it would confuse
1609 : : * anyone who might pick it with bread() afterwards...
1610 : : *
1611 : : * Also.. Note that bforget() doesn't lock the buffer. So there can
1612 : : * be writeout I/O going on against recently-freed buffers. We don't
1613 : : * wait on that I/O in bforget() - it's more efficient to wait on the I/O
1614 : : * only if we really need to. That happens here.
1615 : : */
1616 : 0 : void unmap_underlying_metadata(struct block_device *bdev, sector_t block)
1617 : : {
1618 : : struct buffer_head *old_bh;
1619 : :
1620 : : might_sleep();
1621 : :
1622 : 2513356 : old_bh = __find_get_block_slow(bdev, block);
1623 [ + + ]: 2513619 : if (old_bh) {
1624 : : clear_buffer_dirty(old_bh);
1625 : : wait_on_buffer(old_bh);
1626 : : clear_buffer_req(old_bh);
1627 : 1180 : __brelse(old_bh);
1628 : : }
1629 : 2513619 : }
1630 : : EXPORT_SYMBOL(unmap_underlying_metadata);
1631 : :
1632 : : /*
1633 : : * Size is a power-of-two in the range 512..PAGE_SIZE,
1634 : : * and the case we care about most is PAGE_SIZE.
1635 : : *
1636 : : * So this *could* possibly be written with those
1637 : : * constraints in mind (relevant mostly if some
1638 : : * architecture has a slow bit-scan instruction)
1639 : : */
1640 : : static inline int block_size_bits(unsigned int blocksize)
1641 : : {
1642 [ - + ][ # # ]: 13006657 : return ilog2(blocksize);
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ + - ]
[ - ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ - + ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
[ # # ][ # # ]
1643 : : }
1644 : :
1645 : 0 : static struct buffer_head *create_page_buffers(struct page *page, struct inode *inode, unsigned int b_state)
1646 : : {
1647 [ - + ]: 6502933 : BUG_ON(!PageLocked(page));
1648 : :
1649 [ + + ]: 6502933 : if (!page_has_buffers(page))
1650 : 1767865 : create_empty_buffers(page, 1 << ACCESS_ONCE(inode->i_blkbits), b_state);
1651 [ - + ]: 6506356 : return page_buffers(page);
1652 : : }
1653 : :
1654 : : /*
1655 : : * NOTE! All mapped/uptodate combinations are valid:
1656 : : *
1657 : : * Mapped Uptodate Meaning
1658 : : *
1659 : : * No No "unknown" - must do get_block()
1660 : : * No Yes "hole" - zero-filled
1661 : : * Yes No "allocated" - allocated on disk, not read in
1662 : : * Yes Yes "valid" - allocated and up-to-date in memory.
1663 : : *
1664 : : * "Dirty" is valid only with the last case (mapped+uptodate).
1665 : : */
1666 : :
1667 : : /*
1668 : : * While block_write_full_page is writing back the dirty buffers under
1669 : : * the page lock, whoever dirtied the buffers may decide to clean them
1670 : : * again at any time. We handle that by only looking at the buffer
1671 : : * state inside lock_buffer().
1672 : : *
1673 : : * If block_write_full_page() is called for regular writeback
1674 : : * (wbc->sync_mode == WB_SYNC_NONE) then it will redirty a page which has a
1675 : : * locked buffer. This only can happen if someone has written the buffer
1676 : : * directly, with submit_bh(). At the address_space level PageWriteback
1677 : : * prevents this contention from occurring.
1678 : : *
1679 : : * If block_write_full_page() is called with wbc->sync_mode ==
1680 : : * WB_SYNC_ALL, the writes are posted using WRITE_SYNC; this
1681 : : * causes the writes to be flagged as synchronous writes.
1682 : : */
1683 : 0 : static int __block_write_full_page(struct inode *inode, struct page *page,
1684 : : get_block_t *get_block, struct writeback_control *wbc,
1685 : : bh_end_io_t *handler)
1686 : : {
1687 : : int err;
1688 : : sector_t block;
1689 : : sector_t last_block;
1690 : : struct buffer_head *bh, *head;
1691 : : unsigned int blocksize, bbits;
1692 : : int nr_underway = 0;
1693 [ + + ]: 23984 : int write_op = (wbc->sync_mode == WB_SYNC_ALL ?
1694 : : WRITE_SYNC : WRITE);
1695 : :
1696 : 23984 : head = create_page_buffers(page, inode,
1697 : : (1 << BH_Dirty)|(1 << BH_Uptodate));
1698 : :
1699 : : /*
1700 : : * Be very careful. We have no exclusion from __set_page_dirty_buffers
1701 : : * here, and the (potentially unmapped) buffers may become dirty at
1702 : : * any time. If a buffer becomes dirty here after we've inspected it
1703 : : * then we just miss that fact, and the page stays dirty.
1704 : : *
1705 : : * Buffers outside i_size may be dirtied by __set_page_dirty_buffers;
1706 : : * handle that here by just cleaning them.
1707 : : */
1708 : :
1709 : : bh = head;
1710 : 47968 : blocksize = bh->b_size;
1711 : 23984 : bbits = block_size_bits(blocksize);
1712 : :
1713 : 23984 : block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1714 : 23984 : last_block = (i_size_read(inode) - 1) >> bbits;
1715 : :
1716 : : /*
1717 : : * Get all the dirty buffers mapped to disk addresses and
1718 : : * handle any aliases from the underlying blockdev's mapping.
1719 : : */
1720 : : do {
1721 [ + + ]: 24230 : if (block > last_block) {
1722 : : /*
1723 : : * mapped buffers outside i_size will occur, because
1724 : : * this page can be outside i_size when there is a
1725 : : * truncate in progress.
1726 : : */
1727 : : /*
1728 : : * The buffer was zeroed by block_write_full_page()
1729 : : */
1730 : : clear_buffer_dirty(bh);
1731 : : set_buffer_uptodate(bh);
1732 [ + - ][ - + ]: 24227 : } else if ((!buffer_mapped(bh) || buffer_delay(bh)) &&
[ # # ]
1733 : : buffer_dirty(bh)) {
1734 [ # # ]: 0 : WARN_ON(bh->b_size != blocksize);
1735 : 0 : err = get_block(inode, block, bh, 1);
1736 [ # # ]: 0 : if (err)
1737 : : goto recover;
1738 : : clear_buffer_delay(bh);
1739 [ # # ]: 0 : if (buffer_new(bh)) {
1740 : : /* blockdev mappings never come here */
1741 : : clear_buffer_new(bh);
1742 : 0 : unmap_underlying_metadata(bh->b_bdev,
1743 : : bh->b_blocknr);
1744 : : }
1745 : : }
1746 : 24230 : bh = bh->b_this_page;
1747 : 24230 : block++;
1748 [ + + ]: 24230 : } while (bh != head);
1749 : :
1750 : : do {
1751 [ + + ]: 24230 : if (!buffer_mapped(bh))
1752 : 3 : continue;
1753 : : /*
1754 : : * If it's a fully non-blocking write attempt and we cannot
1755 : : * lock the buffer then redirty the page. Note that this can
1756 : : * potentially cause a busy-wait loop from writeback threads
1757 : : * and kswapd activity, but those code paths have their own
1758 : : * higher-level throttling.
1759 : : */
1760 [ + + ]: 24227 : if (wbc->sync_mode != WB_SYNC_NONE) {
1761 : : lock_buffer(bh);
1762 [ + + ]: 15261 : } else if (!trylock_buffer(bh)) {
1763 : 23 : redirty_page_for_writepage(wbc, page);
1764 : 23 : continue;
1765 : : }
1766 [ + + ]: 24204 : if (test_clear_buffer_dirty(bh)) {
1767 : : mark_buffer_async_write_endio(bh, handler);
1768 : : } else {
1769 : 6133 : unlock_buffer(bh);
1770 : : }
1771 [ + + ]: 24230 : } while ((bh = bh->b_this_page) != head);
1772 : :
1773 : : /*
1774 : : * The page and its buffers are protected by PageWriteback(), so we can
1775 : : * drop the bh refcounts early.
1776 : : */
1777 [ - + ]: 23984 : BUG_ON(PageWriteback(page));
1778 : : set_page_writeback(page);
1779 : :
1780 : : do {
1781 : 24230 : struct buffer_head *next = bh->b_this_page;
1782 [ + + ]: 24230 : if (buffer_async_write(bh)) {
1783 : : submit_bh(write_op, bh);
1784 : 18070 : nr_underway++;
1785 : : }
1786 : : bh = next;
1787 [ + + ]: 24229 : } while (bh != head);
1788 : 23983 : unlock_page(page);
1789 : :
1790 : : err = 0;
1791 : : done:
1792 [ + + ]: 23984 : if (nr_underway == 0) {
1793 : : /*
1794 : : * The page was marked dirty, but the buffers were
1795 : : * clean. Someone wrote them back by hand with
1796 : : * ll_rw_block/submit_bh. A rare case.
1797 : : */
1798 : 5940 : end_page_writeback(page);
1799 : :
1800 : : /*
1801 : : * The page and buffer_heads can be released at any time from
1802 : : * here on.
1803 : : */
1804 : : }
1805 : 23984 : return err;
1806 : :
1807 : : recover:
1808 : : /*
1809 : : * ENOSPC, or some other error. We may already have added some
1810 : : * blocks to the file, so we need to write these out to avoid
1811 : : * exposing stale data.
1812 : : * The page is currently locked and not marked for writeback
1813 : : */
1814 : : bh = head;
1815 : : /* Recovery: lock and submit the mapped buffers */
1816 : : do {
1817 [ # # ][ # # ]: 0 : if (buffer_mapped(bh) && buffer_dirty(bh) &&
[ # # ]
1818 : : !buffer_delay(bh)) {
1819 : : lock_buffer(bh);
1820 : : mark_buffer_async_write_endio(bh, handler);
1821 : : } else {
1822 : : /*
1823 : : * The buffer may have been set dirty during
1824 : : * attachment to a dirty page.
1825 : : */
1826 : : clear_buffer_dirty(bh);
1827 : : }
1828 [ # # ]: 0 : } while ((bh = bh->b_this_page) != head);
1829 : : SetPageError(page);
1830 [ # # ]: 0 : BUG_ON(PageWriteback(page));
1831 : 0 : mapping_set_error(page->mapping, err);
1832 : : set_page_writeback(page);
1833 : : do {
1834 : 0 : struct buffer_head *next = bh->b_this_page;
1835 [ # # ]: 0 : if (buffer_async_write(bh)) {
1836 : : clear_buffer_dirty(bh);
1837 : : submit_bh(write_op, bh);
1838 : 0 : nr_underway++;
1839 : : }
1840 : : bh = next;
1841 [ # # ]: 0 : } while (bh != head);
1842 : 0 : unlock_page(page);
1843 : 0 : goto done;
1844 : : }
1845 : :
1846 : : /*
1847 : : * If a page has any new buffers, zero them out here, and mark them uptodate
1848 : : * and dirty so they'll be written out (in order to prevent uninitialised
1849 : : * block data from leaking). And clear the new bit.
1850 : : */
1851 : 0 : void page_zero_new_buffers(struct page *page, unsigned from, unsigned to)
1852 : : {
1853 : : unsigned int block_start, block_end;
1854 : : struct buffer_head *head, *bh;
1855 : :
1856 [ - + ]: 8 : BUG_ON(!PageLocked(page));
1857 [ + - ]: 8 : if (!page_has_buffers(page))
1858 : 0 : return;
1859 : :
1860 [ - + ]: 8 : bh = head = page_buffers(page);
1861 : : block_start = 0;
1862 : : do {
1863 : 8 : block_end = block_start + bh->b_size;
1864 : :
1865 [ + + ]: 8 : if (buffer_new(bh)) {
1866 [ + - ]: 2 : if (block_end > from && block_start < to) {
1867 [ + - ]: 2 : if (!PageUptodate(page)) {
1868 : : unsigned start, size;
1869 : :
1870 : 2 : start = max(from, block_start);
1871 : 2 : size = min(to, block_end) - start;
1872 : :
1873 : : zero_user(page, start, size);
1874 : : set_buffer_uptodate(bh);
1875 : : }
1876 : :
1877 : : clear_buffer_new(bh);
1878 : 2 : mark_buffer_dirty(bh);
1879 : : }
1880 : : }
1881 : :
1882 : : block_start = block_end;
1883 : 8 : bh = bh->b_this_page;
1884 [ - + ]: 8 : } while (bh != head);
1885 : : }
1886 : : EXPORT_SYMBOL(page_zero_new_buffers);
1887 : :
1888 : 0 : int __block_write_begin(struct page *page, loff_t pos, unsigned len,
1889 : : get_block_t *get_block)
1890 : : {
1891 : 6477114 : unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1892 : 6477114 : unsigned to = from + len;
1893 : 6477114 : struct inode *inode = page->mapping->host;
1894 : : unsigned block_start, block_end;
1895 : : sector_t block;
1896 : : int err = 0;
1897 : : unsigned blocksize, bbits;
1898 : : struct buffer_head *bh, *head, *wait[2], **wait_bh=wait;
1899 : :
1900 [ - + ]: 6477114 : BUG_ON(!PageLocked(page));
1901 : : BUG_ON(from > PAGE_CACHE_SIZE);
1902 [ - + ]: 6477114 : BUG_ON(to > PAGE_CACHE_SIZE);
1903 [ - + ]: 6477114 : BUG_ON(from > to);
1904 : :
1905 : 6477114 : head = create_page_buffers(page, inode, 0);
1906 : 12953979 : blocksize = head->b_size;
1907 : 6476865 : bbits = block_size_bits(blocksize);
1908 : :
1909 : 6476865 : block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
1910 : :
1911 [ + + ]: 12952086 : for(bh = head, block_start = 0; bh != head || !block_start;
1912 : 6475221 : block++, block_start=block_end, bh = bh->b_this_page) {
1913 : 6477399 : block_end = block_start + blocksize;
1914 [ + + ]: 6477399 : if (block_end <= from || block_start >= to) {
1915 [ + ]: 0 : if (PageUptodate(page)) {
1916 [ - + ]: 33 : if (!buffer_uptodate(bh))
1917 : : set_buffer_uptodate(bh);
1918 : : }
1919 : 0 : continue;
1920 : : }
1921 [ - + ]: 6477068 : if (buffer_new(bh))
1922 : : clear_buffer_new(bh);
1923 [ + + ]: 6480746 : if (!buffer_mapped(bh)) {
1924 [ - + ]: 1771121 : WARN_ON(bh->b_size != blocksize);
1925 : 1771121 : err = get_block(inode, block, bh, 1);
1926 [ + ]: 8243572 : if (err)
1927 : : break;
1928 [ + + ]: 1768902 : if (buffer_new(bh)) {
1929 : 1766665 : unmap_underlying_metadata(bh->b_bdev,
1930 : : bh->b_blocknr);
1931 [ + + ]: 1766388 : if (PageUptodate(page)) {
1932 : 132648 : clear_buffer_new(bh);
1933 : 132665 : set_buffer_uptodate(bh);
1934 : 132676 : mark_buffer_dirty(bh);
1935 : 132716 : continue;
1936 : : }
1937 [ + + ]: 1633740 : if (block_end > to || block_start < from)
1938 : : zero_user_segments(page,
1939 : : to, block_end,
1940 : : block_start, from);
1941 : 1631851 : continue;
1942 : : }
1943 : : }
1944 [ + + ]: 4709268 : if (PageUptodate(page)) {
1945 [ - + ]: 4705553 : if (!buffer_uptodate(bh))
1946 : : set_buffer_uptodate(bh);
1947 : 4707427 : continue;
1948 : : }
1949 [ + - ][ + - ]: 3715 : if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
[ + - ]
1950 [ + + ]: 3715 : !buffer_unwritten(bh) &&
1951 : 3715 : (block_start < from || block_end > to)) {
1952 : 540 : ll_rw_block(READ, 1, &bh);
1953 : 540 : *wait_bh++=bh;
1954 : : }
1955 : : }
1956 : : /*
1957 : : * If we issued read requests - let them complete.
1958 : : */
1959 [ + + ]: 6475210 : while(wait_bh > wait) {
1960 : 540 : wait_on_buffer(*--wait_bh);
1961 [ - + ]: 540 : if (!buffer_uptodate(*wait_bh))
1962 : : err = -EIO;
1963 : : }
1964 [ - + ]: 6474670 : if (unlikely(err))
1965 : 0 : page_zero_new_buffers(page, from, to);
1966 : 6474670 : return err;
1967 : : }
1968 : : EXPORT_SYMBOL(__block_write_begin);
1969 : :
1970 : 0 : static int __block_commit_write(struct inode *inode, struct page *page,
1971 : : unsigned from, unsigned to)
1972 : : {
1973 : : unsigned block_start, block_end;
1974 : : int partial = 0;
1975 : : unsigned blocksize;
1976 : : struct buffer_head *bh, *head;
1977 : :
1978 [ - + ]: 6477211 : bh = head = page_buffers(page);
1979 : 6477211 : blocksize = bh->b_size;
1980 : :
1981 : : block_start = 0;
1982 : : do {
1983 : 6476570 : block_end = block_start + blocksize;
1984 [ + + ]: 6476570 : if (block_end <= from || block_start >= to) {
1985 [ + + ]: 65 : if (!buffer_uptodate(bh))
1986 : : partial = 1;
1987 : : } else {
1988 : : set_buffer_uptodate(bh);
1989 : 6475941 : mark_buffer_dirty(bh);
1990 : : }
1991 : : clear_buffer_new(bh);
1992 : :
1993 : : block_start = block_end;
1994 : 6476716 : bh = bh->b_this_page;
1995 [ + ]: 6476716 : } while (bh != head);
1996 : :
1997 : : /*
1998 : : * If this is a partial write which happened to make all buffers
1999 : : * uptodate then we can optimize away a bogus readpage() for
2000 : : * the next read(). Here we 'discover' whether the page went
2001 : : * uptodate as a result of this (potentially partial) write.
2002 : : */
2003 [ + + ]: 6477357 : if (!partial)
2004 : : SetPageUptodate(page);
2005 : 6475672 : return 0;
2006 : : }
2007 : :
2008 : : /*
2009 : : * block_write_begin takes care of the basic task of block allocation and
2010 : : * bringing partial write blocks uptodate first.
2011 : : *
2012 : : * The filesystem needs to handle block truncation upon failure.
2013 : : */
2014 : 0 : int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
2015 : : unsigned flags, struct page **pagep, get_block_t *get_block)
2016 : : {
2017 : 5271 : pgoff_t index = pos >> PAGE_CACHE_SHIFT;
2018 : : struct page *page;
2019 : : int status;
2020 : :
2021 : 5271 : page = grab_cache_page_write_begin(mapping, index, flags);
2022 [ + - ]: 5271 : if (!page)
2023 : : return -ENOMEM;
2024 : :
2025 : 5271 : status = __block_write_begin(page, pos, len, get_block);
2026 [ - + ]: 5271 : if (unlikely(status)) {
2027 : 0 : unlock_page(page);
2028 : 0 : page_cache_release(page);
2029 : : page = NULL;
2030 : : }
2031 : :
2032 : 5271 : *pagep = page;
2033 : 5271 : return status;
2034 : : }
2035 : : EXPORT_SYMBOL(block_write_begin);
2036 : :
2037 : 0 : int block_write_end(struct file *file, struct address_space *mapping,
2038 : : loff_t pos, unsigned len, unsigned copied,
2039 : : struct page *page, void *fsdata)
2040 : : {
2041 : : struct inode *inode = mapping->host;
2042 : : unsigned start;
2043 : :
2044 : 6270043 : start = pos & (PAGE_CACHE_SIZE - 1);
2045 : :
2046 [ + + ]: 6270043 : if (unlikely(copied < len)) {
2047 : : /*
2048 : : * The buffers that were written will now be uptodate, so we
2049 : : * don't have to worry about a readpage reading them and
2050 : : * overwriting a partial write. However if we have encountered
2051 : : * a short write and only partially written into a buffer, it
2052 : : * will not be marked uptodate, so a readpage might come in and
2053 : : * destroy our partial write.
2054 : : *
2055 : : * Do the simplest thing, and just treat any short write to a
2056 : : * non uptodate page as a zero-length write, and force the
2057 : : * caller to redo the whole thing.
2058 : : */
2059 [ + + ]: 6270051 : if (!PageUptodate(page))
2060 : : copied = 0;
2061 : :
2062 : 8 : page_zero_new_buffers(page, start+copied, start+len);
2063 : : }
2064 : 6270043 : flush_dcache_page(page);
2065 : :
2066 : : /* This could be a short (even 0-length) commit */
2067 : 6272154 : __block_commit_write(inode, page, start, start+copied);
2068 : :
2069 : 6269739 : return copied;
2070 : : }
2071 : : EXPORT_SYMBOL(block_write_end);
2072 : :
2073 : 0 : int generic_write_end(struct file *file, struct address_space *mapping,
2074 : : loff_t pos, unsigned len, unsigned copied,
2075 : : struct page *page, void *fsdata)
2076 : : {
2077 : 6265384 : struct inode *inode = mapping->host;
2078 : : int i_size_changed = 0;
2079 : :
2080 : 6265384 : copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
2081 : :
2082 : : /*
2083 : : * No need to use i_size_read() here, the i_size
2084 : : * cannot change under us because we hold i_mutex.
2085 : : *
2086 : : * But it's important to update i_size while still holding page lock:
2087 : : * page writeout could otherwise come in and zero beyond i_size.
2088 : : */
2089 [ + + ]: 6264242 : if (pos+copied > inode->i_size) {
2090 : : i_size_write(inode, pos+copied);
2091 : : i_size_changed = 1;
2092 : : }
2093 : :
2094 : 6260560 : unlock_page(page);
2095 : 6263288 : page_cache_release(page);
2096 : :
2097 : : /*
2098 : : * Don't mark the inode dirty under page lock. First, it unnecessarily
2099 : : * makes the holding time of page lock longer. Second, it forces lock
2100 : : * ordering of page lock and transaction start for journaling
2101 : : * filesystems.
2102 : : */
2103 [ + + ]: 6258187 : if (i_size_changed)
2104 : : mark_inode_dirty(inode);
2105 : :
2106 : 6258445 : return copied;
2107 : : }
2108 : : EXPORT_SYMBOL(generic_write_end);
2109 : :
2110 : : /*
2111 : : * block_is_partially_uptodate checks whether buffers within a page are
2112 : : * uptodate or not.
2113 : : *
2114 : : * Returns true if all buffers which correspond to a file portion
2115 : : * we want to read are uptodate.
2116 : : */
2117 : 0 : int block_is_partially_uptodate(struct page *page, read_descriptor_t *desc,
2118 : : unsigned long from)
2119 : : {
2120 : : unsigned block_start, block_end, blocksize;
2121 : : unsigned to;
2122 : : struct buffer_head *bh, *head;
2123 : : int ret = 1;
2124 : :
2125 [ + - ]: 4 : if (!page_has_buffers(page))
2126 : : return 0;
2127 : :
2128 [ - + ]: 4 : head = page_buffers(page);
2129 : 4 : blocksize = head->b_size;
2130 : 4 : to = min_t(unsigned, PAGE_CACHE_SIZE - from, desc->count);
2131 : 4 : to = from + to;
2132 [ + - ][ + ]: 4 : if (from < blocksize && to > PAGE_CACHE_SIZE - blocksize)
2133 : : return 0;
2134 : :
2135 : : bh = head;
2136 : : block_start = 0;
2137 : : do {
2138 : 3 : block_end = block_start + blocksize;
2139 [ + - ]: 3 : if (block_end > from && block_start < to) {
2140 [ + - ]: 3 : if (!buffer_uptodate(bh)) {
2141 : : ret = 0;
2142 : : break;
2143 : : }
2144 [ - + ]: 3 : if (block_end >= to)
2145 : : break;
2146 : : }
2147 : : block_start = block_end;
2148 : 0 : bh = bh->b_this_page;
2149 [ # # ]: 0 : } while (bh != head);
2150 : :
2151 : 3 : return ret;
2152 : : }
2153 : : EXPORT_SYMBOL(block_is_partially_uptodate);
2154 : :
2155 : : /*
2156 : : * Generic "read page" function for block devices that have the normal
2157 : : * get_block functionality. This is most of the block device filesystems.
2158 : : * Reads the page asynchronously --- the unlock_buffer() and
2159 : : * set/clear_buffer_uptodate() functions propagate buffer state into the
2160 : : * page struct once IO has completed.
2161 : : */
2162 : 0 : int block_read_full_page(struct page *page, get_block_t *get_block)
2163 : : {
2164 : 2355 : struct inode *inode = page->mapping->host;
2165 : : sector_t iblock, lblock;
2166 : : struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
2167 : : unsigned int blocksize, bbits;
2168 : : int nr, i;
2169 : : int fully_mapped = 1;
2170 : :
2171 : 2355 : head = create_page_buffers(page, inode, 0);
2172 : 4710 : blocksize = head->b_size;
2173 : 2355 : bbits = block_size_bits(blocksize);
2174 : :
2175 : 2355 : iblock = (sector_t)page->index << (PAGE_CACHE_SHIFT - bbits);
2176 : 2355 : lblock = (i_size_read(inode)+blocksize-1) >> bbits;
2177 : : bh = head;
2178 : : nr = 0;
2179 : : i = 0;
2180 : :
2181 : : do {
2182 [ + + ]: 3468 : if (buffer_uptodate(bh))
2183 : 29 : continue;
2184 : :
2185 [ + + ]: 3439 : if (!buffer_mapped(bh)) {
2186 : : int err = 0;
2187 : :
2188 : : fully_mapped = 0;
2189 [ + + ]: 3413 : if (iblock < lblock) {
2190 [ - + ]: 3410 : WARN_ON(bh->b_size != blocksize);
2191 : 3410 : err = get_block(inode, iblock, bh, 0);
2192 [ - + ]: 3410 : if (err)
2193 : : SetPageError(page);
2194 : : }
2195 [ + + ]: 3413 : if (!buffer_mapped(bh)) {
2196 : 1079 : zero_user(page, i * blocksize, blocksize);
2197 [ + - ]: 1079 : if (!err)
2198 : : set_buffer_uptodate(bh);
2199 : 1079 : continue;
2200 : : }
2201 : : /*
2202 : : * get_block() might have updated the buffer
2203 : : * synchronously
2204 : : */
2205 [ - + ]: 2334 : if (buffer_uptodate(bh))
2206 : 0 : continue;
2207 : : }
2208 : 2360 : arr[nr++] = bh;
2209 [ + + ]: 3468 : } while (i++, iblock++, (bh = bh->b_this_page) != head);
2210 : :
2211 [ + + ]: 2355 : if (fully_mapped)
2212 : : SetPageMappedToDisk(page);
2213 : :
2214 [ + + ]: 2355 : if (!nr) {
2215 : : /*
2216 : : * All buffers are uptodate - we can set the page uptodate
2217 : : * as well. But not if get_block() returned an error.
2218 : : */
2219 [ + - ]: 1079 : if (!PageError(page))
2220 : : SetPageUptodate(page);
2221 : 1079 : unlock_page(page);
2222 : 1079 : return 0;
2223 : : }
2224 : :
2225 : : /* Stage two: lock the buffers */
2226 [ + + ]: 3636 : for (i = 0; i < nr; i++) {
2227 : 2360 : bh = arr[i];
2228 : : lock_buffer(bh);
2229 : : mark_buffer_async_read(bh);
2230 : : }
2231 : :
2232 : : /*
2233 : : * Stage 3: start the IO. Check for uptodateness
2234 : : * inside the buffer lock in case another process reading
2235 : : * the underlying blockdev brought it uptodate (the sct fix).
2236 : : */
2237 [ + + ]: 3636 : for (i = 0; i < nr; i++) {
2238 : 2360 : bh = arr[i];
2239 [ - + ]: 2360 : if (buffer_uptodate(bh))
2240 : 0 : end_buffer_async_read(bh, 1);
2241 : : else
2242 : : submit_bh(READ, bh);
2243 : : }
2244 : : return 0;
2245 : : }
2246 : : EXPORT_SYMBOL(block_read_full_page);
2247 : :
2248 : : /* utility function for filesystems that need to do work on expanding
2249 : : * truncates. Uses filesystem pagecache writes to allow the filesystem to
2250 : : * deal with the hole.
2251 : : */
2252 : 0 : int generic_cont_expand_simple(struct inode *inode, loff_t size)
2253 : : {
2254 : 0 : struct address_space *mapping = inode->i_mapping;
2255 : : struct page *page;
2256 : : void *fsdata;
2257 : : int err;
2258 : :
2259 : 0 : err = inode_newsize_ok(inode, size);
2260 [ # # ]: 0 : if (err)
2261 : : goto out;
2262 : :
2263 : 0 : err = pagecache_write_begin(NULL, mapping, size, 0,
2264 : : AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
2265 : : &page, &fsdata);
2266 [ # # ]: 0 : if (err)
2267 : : goto out;
2268 : :
2269 : 0 : err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
2270 [ # # ]: 0 : BUG_ON(err > 0);
2271 : :
2272 : : out:
2273 : 0 : return err;
2274 : : }
2275 : : EXPORT_SYMBOL(generic_cont_expand_simple);
2276 : :
2277 : 0 : static int cont_expand_zero(struct file *file, struct address_space *mapping,
2278 : : loff_t pos, loff_t *bytes)
2279 : : {
2280 : 0 : struct inode *inode = mapping->host;
2281 : 0 : unsigned blocksize = 1 << inode->i_blkbits;
2282 : : struct page *page;
2283 : : void *fsdata;
2284 : : pgoff_t index, curidx;
2285 : : loff_t curpos;
2286 : : unsigned zerofrom, offset, len;
2287 : : int err = 0;
2288 : :
2289 : 0 : index = pos >> PAGE_CACHE_SHIFT;
2290 : 0 : offset = pos & ~PAGE_CACHE_MASK;
2291 : :
2292 [ # # ]: 0 : while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
2293 : 0 : zerofrom = curpos & ~PAGE_CACHE_MASK;
2294 [ # # ]: 0 : if (zerofrom & (blocksize-1)) {
2295 : 0 : *bytes |= (blocksize-1);
2296 : 0 : (*bytes)++;
2297 : : }
2298 : 0 : len = PAGE_CACHE_SIZE - zerofrom;
2299 : :
2300 : 0 : err = pagecache_write_begin(file, mapping, curpos, len,
2301 : : AOP_FLAG_UNINTERRUPTIBLE,
2302 : : &page, &fsdata);
2303 [ # # ]: 0 : if (err)
2304 : : goto out;
2305 : 0 : zero_user(page, zerofrom, len);
2306 : 0 : err = pagecache_write_end(file, mapping, curpos, len, len,
2307 : : page, fsdata);
2308 [ # # ]: 0 : if (err < 0)
2309 : : goto out;
2310 [ # # ]: 0 : BUG_ON(err != len);
2311 : : err = 0;
2312 : :
2313 : 0 : balance_dirty_pages_ratelimited(mapping);
2314 : : }
2315 : :
2316 : : /* page covers the boundary, find the boundary offset */
2317 [ # # ]: 0 : if (index == curidx) {
2318 : 0 : zerofrom = curpos & ~PAGE_CACHE_MASK;
2319 : : /* if we will expand the thing last block will be filled */
2320 [ # # ]: 0 : if (offset <= zerofrom) {
2321 : : goto out;
2322 : : }
2323 [ # # ]: 0 : if (zerofrom & (blocksize-1)) {
2324 : 0 : *bytes |= (blocksize-1);
2325 : 0 : (*bytes)++;
2326 : : }
2327 : 0 : len = offset - zerofrom;
2328 : :
2329 : 0 : err = pagecache_write_begin(file, mapping, curpos, len,
2330 : : AOP_FLAG_UNINTERRUPTIBLE,
2331 : : &page, &fsdata);
2332 [ # # ]: 0 : if (err)
2333 : : goto out;
2334 : 0 : zero_user(page, zerofrom, len);
2335 : 0 : err = pagecache_write_end(file, mapping, curpos, len, len,
2336 : : page, fsdata);
2337 [ # # ]: 0 : if (err < 0)
2338 : : goto out;
2339 [ # # ]: 0 : BUG_ON(err != len);
2340 : : err = 0;
2341 : : }
2342 : : out:
2343 : 0 : return err;
2344 : : }
2345 : :
2346 : : /*
2347 : : * For moronic filesystems that do not allow holes in file.
2348 : : * We may have to extend the file.
2349 : : */
2350 : 0 : int cont_write_begin(struct file *file, struct address_space *mapping,
2351 : : loff_t pos, unsigned len, unsigned flags,
2352 : : struct page **pagep, void **fsdata,
2353 : : get_block_t *get_block, loff_t *bytes)
2354 : : {
2355 : 0 : struct inode *inode = mapping->host;
2356 : 0 : unsigned blocksize = 1 << inode->i_blkbits;
2357 : : unsigned zerofrom;
2358 : : int err;
2359 : :
2360 : 0 : err = cont_expand_zero(file, mapping, pos, bytes);
2361 [ # # ]: 0 : if (err)
2362 : : return err;
2363 : :
2364 : 0 : zerofrom = *bytes & ~PAGE_CACHE_MASK;
2365 [ # # ][ # # ]: 0 : if (pos+len > *bytes && zerofrom & (blocksize-1)) {
2366 : 0 : *bytes |= (blocksize-1);
2367 : 0 : (*bytes)++;
2368 : : }
2369 : :
2370 : 0 : return block_write_begin(mapping, pos, len, flags, pagep, get_block);
2371 : : }
2372 : : EXPORT_SYMBOL(cont_write_begin);
2373 : :
2374 : 0 : int block_commit_write(struct page *page, unsigned from, unsigned to)
2375 : : {
2376 : : struct inode *inode = page->mapping->host;
2377 : 205271 : __block_commit_write(inode,page,from,to);
2378 : 0 : return 0;
2379 : : }
2380 : : EXPORT_SYMBOL(block_commit_write);
2381 : :
2382 : : /*
2383 : : * block_page_mkwrite() is not allowed to change the file size as it gets
2384 : : * called from a page fault handler when a page is first dirtied. Hence we must
2385 : : * be careful to check for EOF conditions here. We set the page up correctly
2386 : : * for a written page which means we get ENOSPC checking when writing into
2387 : : * holes and correct delalloc and unwritten extent mapping on filesystems that
2388 : : * support these features.
2389 : : *
2390 : : * We are not allowed to take the i_mutex here so we have to play games to
2391 : : * protect against truncate races as the page could now be beyond EOF. Because
2392 : : * truncate writes the inode size before removing pages, once we have the
2393 : : * page lock we can determine safely if the page is beyond EOF. If it is not
2394 : : * beyond EOF, then the page is guaranteed safe against truncation until we
2395 : : * unlock the page.
2396 : : *
2397 : : * Direct callers of this function should protect against filesystem freezing
2398 : : * using sb_start_write() - sb_end_write() functions.
2399 : : */
2400 : 0 : int __block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2401 : : get_block_t get_block)
2402 : : {
2403 : 410636 : struct page *page = vmf->page;
2404 : 205086 : struct inode *inode = file_inode(vma->vm_file);
2405 : : unsigned long end;
2406 : : loff_t size;
2407 : : int ret;
2408 : :
2409 : : lock_page(page);
2410 : : size = i_size_read(inode);
2411 [ + ][ + ]: 205440 : if ((page->mapping != inode->i_mapping) ||
2412 : : (page_offset(page) > size)) {
2413 : : /* We overload EFAULT to mean page got truncated */
2414 : : ret = -EFAULT;
2415 : : goto out_unlock;
2416 : : }
2417 : :
2418 : : /* page is wholly or partially inside EOF */
2419 [ + + ]: 205555 : if (((page->index + 1) << PAGE_CACHE_SHIFT) > size)
2420 : 54478 : end = size & ~PAGE_CACHE_MASK;
2421 : : else
2422 : : end = PAGE_CACHE_SIZE;
2423 : :
2424 : 205555 : ret = __block_write_begin(page, 0, end, get_block);
2425 [ + ]: 205198 : if (!ret)
2426 : : ret = block_commit_write(page, 0, end);
2427 : :
2428 [ + - ]: 205147 : if (unlikely(ret < 0))
2429 : : goto out_unlock;
2430 : 205147 : set_page_dirty(page);
2431 : 205601 : wait_for_stable_page(page);
2432 : 205598 : return 0;
2433 : : out_unlock:
2434 : 0 : unlock_page(page);
2435 : 0 : return ret;
2436 : : }
2437 : : EXPORT_SYMBOL(__block_page_mkwrite);
2438 : :
2439 : 0 : int block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
2440 : : get_block_t get_block)
2441 : : {
2442 : : int ret;
2443 : 0 : struct super_block *sb = file_inode(vma->vm_file)->i_sb;
2444 : :
2445 : : sb_start_pagefault(sb);
2446 : :
2447 : : /*
2448 : : * Update file times before taking page lock. We may end up failing the
2449 : : * fault so this update may be superfluous but who really cares...
2450 : : */
2451 : 0 : file_update_time(vma->vm_file);
2452 : :
2453 : 0 : ret = __block_page_mkwrite(vma, vmf, get_block);
2454 : : sb_end_pagefault(sb);
2455 : 0 : return block_page_mkwrite_return(ret);
2456 : : }
2457 : : EXPORT_SYMBOL(block_page_mkwrite);
2458 : :
2459 : : /*
2460 : : * nobh_write_begin()'s prereads are special: the buffer_heads are freed
2461 : : * immediately, while under the page lock. So it needs a special end_io
2462 : : * handler which does not touch the bh after unlocking it.
2463 : : */
2464 : 0 : static void end_buffer_read_nobh(struct buffer_head *bh, int uptodate)
2465 : : {
2466 : 0 : __end_buffer_read_notouch(bh, uptodate);
2467 : 0 : }
2468 : :
2469 : : /*
2470 : : * Attach the singly-linked list of buffers created by nobh_write_begin, to
2471 : : * the page (converting it to circular linked list and taking care of page
2472 : : * dirty races).
2473 : : */
2474 : 0 : static void attach_nobh_buffers(struct page *page, struct buffer_head *head)
2475 : : {
2476 : : struct buffer_head *bh;
2477 : :
2478 [ # # ]: 0 : BUG_ON(!PageLocked(page));
2479 : :
2480 : 0 : spin_lock(&page->mapping->private_lock);
2481 : : bh = head;
2482 : : do {
2483 [ # # ]: 0 : if (PageDirty(page))
2484 : : set_buffer_dirty(bh);
2485 [ # # ]: 0 : if (!bh->b_this_page)
2486 : 0 : bh->b_this_page = head;
2487 : 0 : bh = bh->b_this_page;
2488 [ # # ]: 0 : } while (bh != head);
2489 : : attach_page_buffers(page, head);
2490 : 0 : spin_unlock(&page->mapping->private_lock);
2491 : 0 : }
2492 : :
2493 : : /*
2494 : : * On entry, the page is fully not uptodate.
2495 : : * On exit the page is fully uptodate in the areas outside (from,to)
2496 : : * The filesystem needs to handle block truncation upon failure.
2497 : : */
2498 : 0 : int nobh_write_begin(struct address_space *mapping,
2499 : : loff_t pos, unsigned len, unsigned flags,
2500 : : struct page **pagep, void **fsdata,
2501 : : get_block_t *get_block)
2502 : : {
2503 : 0 : struct inode *inode = mapping->host;
2504 : 0 : const unsigned blkbits = inode->i_blkbits;
2505 : 0 : const unsigned blocksize = 1 << blkbits;
2506 : : struct buffer_head *head, *bh;
2507 : : struct page *page;
2508 : : pgoff_t index;
2509 : : unsigned from, to;
2510 : : unsigned block_in_page;
2511 : : unsigned block_start, block_end;
2512 : : sector_t block_in_file;
2513 : : int nr_reads = 0;
2514 : : int ret = 0;
2515 : : int is_mapped_to_disk = 1;
2516 : :
2517 : 0 : index = pos >> PAGE_CACHE_SHIFT;
2518 : 0 : from = pos & (PAGE_CACHE_SIZE - 1);
2519 : 0 : to = from + len;
2520 : :
2521 : 0 : page = grab_cache_page_write_begin(mapping, index, flags);
2522 [ # # ]: 0 : if (!page)
2523 : : return -ENOMEM;
2524 : 0 : *pagep = page;
2525 : 0 : *fsdata = NULL;
2526 : :
2527 [ # # ]: 0 : if (page_has_buffers(page)) {
2528 : 0 : ret = __block_write_begin(page, pos, len, get_block);
2529 [ # # ]: 0 : if (unlikely(ret))
2530 : : goto out_release;
2531 : : return ret;
2532 : : }
2533 : :
2534 [ # # ]: 0 : if (PageMappedToDisk(page))
2535 : : return 0;
2536 : :
2537 : : /*
2538 : : * Allocate buffers so that we can keep track of state, and potentially
2539 : : * attach them to the page if an error occurs. In the common case of
2540 : : * no error, they will just be freed again without ever being attached
2541 : : * to the page (which is all OK, because we're under the page lock).
2542 : : *
2543 : : * Be careful: the buffer linked list is a NULL terminated one, rather
2544 : : * than the circular one we're used to.
2545 : : */
2546 : 0 : head = alloc_page_buffers(page, blocksize, 0);
2547 [ # # ]: 0 : if (!head) {
2548 : : ret = -ENOMEM;
2549 : : goto out_release;
2550 : : }
2551 : :
2552 : 0 : block_in_file = (sector_t)page->index << (PAGE_CACHE_SHIFT - blkbits);
2553 : :
2554 : : /*
2555 : : * We loop across all blocks in the page, whether or not they are
2556 : : * part of the affected region. This is so we can discover if the
2557 : : * page is fully mapped-to-disk.
2558 : : */
2559 [ # # ]: 0 : for (block_start = 0, block_in_page = 0, bh = head;
2560 : : block_start < PAGE_CACHE_SIZE;
2561 : 0 : block_in_page++, block_start += blocksize, bh = bh->b_this_page) {
2562 : : int create;
2563 : :
2564 : 0 : block_end = block_start + blocksize;
2565 : 0 : bh->b_state = 0;
2566 : : create = 1;
2567 [ # # ]: 0 : if (block_start >= to)
2568 : : create = 0;
2569 : 0 : ret = get_block(inode, block_in_file + block_in_page,
2570 : : bh, create);
2571 [ # # ]: 0 : if (ret)
2572 : : goto failed;
2573 [ # # ]: 0 : if (!buffer_mapped(bh))
2574 : : is_mapped_to_disk = 0;
2575 [ # # ]: 0 : if (buffer_new(bh))
2576 : 0 : unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
2577 [ # # ]: 0 : if (PageUptodate(page)) {
2578 : : set_buffer_uptodate(bh);
2579 : 0 : continue;
2580 : : }
2581 [ # # ][ # # ]: 0 : if (buffer_new(bh) || !buffer_mapped(bh)) {
2582 : : zero_user_segments(page, block_start, from,
2583 : : to, block_end);
2584 : 0 : continue;
2585 : : }
2586 [ # # ]: 0 : if (buffer_uptodate(bh))
2587 : 0 : continue; /* reiserfs does this */
2588 [ # # ]: 0 : if (block_start < from || block_end > to) {
2589 : : lock_buffer(bh);
2590 : 0 : bh->b_end_io = end_buffer_read_nobh;
2591 : : submit_bh(READ, bh);
2592 : 0 : nr_reads++;
2593 : : }
2594 : : }
2595 : :
2596 [ # # ]: 0 : if (nr_reads) {
2597 : : /*
2598 : : * The page is locked, so these buffers are protected from
2599 : : * any VM or truncate activity. Hence we don't need to care
2600 : : * for the buffer_head refcounts.
2601 : : */
2602 [ # # ]: 0 : for (bh = head; bh; bh = bh->b_this_page) {
2603 : : wait_on_buffer(bh);
2604 [ # # ]: 0 : if (!buffer_uptodate(bh))
2605 : : ret = -EIO;
2606 : : }
2607 [ # # ]: 0 : if (ret)
2608 : : goto failed;
2609 : : }
2610 : :
2611 [ # # ]: 0 : if (is_mapped_to_disk)
2612 : : SetPageMappedToDisk(page);
2613 : :
2614 : 0 : *fsdata = head; /* to be released by nobh_write_end */
2615 : :
2616 : 0 : return 0;
2617 : :
2618 : : failed:
2619 [ # # ]: 0 : BUG_ON(!ret);
2620 : : /*
2621 : : * Error recovery is a bit difficult. We need to zero out blocks that
2622 : : * were newly allocated, and dirty them to ensure they get written out.
2623 : : * Buffers need to be attached to the page at this point, otherwise
2624 : : * the handling of potential IO errors during writeout would be hard
2625 : : * (could try doing synchronous writeout, but what if that fails too?)
2626 : : */
2627 : 0 : attach_nobh_buffers(page, head);
2628 : 0 : page_zero_new_buffers(page, from, to);
2629 : :
2630 : : out_release:
2631 : 0 : unlock_page(page);
2632 : 0 : page_cache_release(page);
2633 : 0 : *pagep = NULL;
2634 : :
2635 : 0 : return ret;
2636 : : }
2637 : : EXPORT_SYMBOL(nobh_write_begin);
2638 : :
2639 : 0 : int nobh_write_end(struct file *file, struct address_space *mapping,
2640 : : loff_t pos, unsigned len, unsigned copied,
2641 : : struct page *page, void *fsdata)
2642 : : {
2643 : 0 : struct inode *inode = page->mapping->host;
2644 : : struct buffer_head *head = fsdata;
2645 : : struct buffer_head *bh;
2646 [ # # ][ # # ]: 0 : BUG_ON(fsdata != NULL && page_has_buffers(page));
2647 : :
2648 [ # # ][ # # ]: 0 : if (unlikely(copied < len) && head)
2649 : 0 : attach_nobh_buffers(page, head);
2650 [ # # ]: 0 : if (page_has_buffers(page))
2651 : 0 : return generic_write_end(file, mapping, pos, len,
2652 : : copied, page, fsdata);
2653 : :
2654 : : SetPageUptodate(page);
2655 : 0 : set_page_dirty(page);
2656 [ # # ]: 0 : if (pos+copied > inode->i_size) {
2657 : : i_size_write(inode, pos+copied);
2658 : : mark_inode_dirty(inode);
2659 : : }
2660 : :
2661 : 0 : unlock_page(page);
2662 : 0 : page_cache_release(page);
2663 : :
2664 [ # # ]: 0 : while (head) {
2665 : : bh = head;
2666 : 0 : head = head->b_this_page;
2667 : 0 : free_buffer_head(bh);
2668 : : }
2669 : :
2670 : 0 : return copied;
2671 : : }
2672 : : EXPORT_SYMBOL(nobh_write_end);
2673 : :
2674 : : /*
2675 : : * nobh_writepage() - based on block_full_write_page() except
2676 : : * that it tries to operate without attaching bufferheads to
2677 : : * the page.
2678 : : */
2679 : 0 : int nobh_writepage(struct page *page, get_block_t *get_block,
2680 : : struct writeback_control *wbc)
2681 : : {
2682 : 0 : struct inode * const inode = page->mapping->host;
2683 : : loff_t i_size = i_size_read(inode);
2684 : 0 : const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2685 : : unsigned offset;
2686 : : int ret;
2687 : :
2688 : : /* Is the page fully inside i_size? */
2689 [ # # ]: 0 : if (page->index < end_index)
2690 : : goto out;
2691 : :
2692 : : /* Is the page fully outside i_size? (truncate in progress) */
2693 : 0 : offset = i_size & (PAGE_CACHE_SIZE-1);
2694 [ # # ][ # # ]: 0 : if (page->index >= end_index+1 || !offset) {
2695 : : /*
2696 : : * The page may have dirty, unmapped buffers. For example,
2697 : : * they may have been added in ext3_writepage(). Make them
2698 : : * freeable here, so the page does not leak.
2699 : : */
2700 : : #if 0
2701 : : /* Not really sure about this - do we need this ? */
2702 : : if (page->mapping->a_ops->invalidatepage)
2703 : : page->mapping->a_ops->invalidatepage(page, offset);
2704 : : #endif
2705 : 0 : unlock_page(page);
2706 : 0 : return 0; /* don't care */
2707 : : }
2708 : :
2709 : : /*
2710 : : * The page straddles i_size. It must be zeroed out on each and every
2711 : : * writepage invocation because it may be mmapped. "A file is mapped
2712 : : * in multiples of the page size. For a file that is not a multiple of
2713 : : * the page size, the remaining memory is zeroed when mapped, and
2714 : : * writes to that region are not written out to the file."
2715 : : */
2716 : : zero_user_segment(page, offset, PAGE_CACHE_SIZE);
2717 : : out:
2718 : 0 : ret = mpage_writepage(page, get_block, wbc);
2719 [ # # ]: 0 : if (ret == -EAGAIN)
2720 : 0 : ret = __block_write_full_page(inode, page, get_block, wbc,
2721 : : end_buffer_async_write);
2722 : 0 : return ret;
2723 : : }
2724 : : EXPORT_SYMBOL(nobh_writepage);
2725 : :
2726 : 0 : int nobh_truncate_page(struct address_space *mapping,
2727 : : loff_t from, get_block_t *get_block)
2728 : : {
2729 : 0 : pgoff_t index = from >> PAGE_CACHE_SHIFT;
2730 : 0 : unsigned offset = from & (PAGE_CACHE_SIZE-1);
2731 : : unsigned blocksize;
2732 : : sector_t iblock;
2733 : : unsigned length, pos;
2734 : 0 : struct inode *inode = mapping->host;
2735 : : struct page *page;
2736 : : struct buffer_head map_bh;
2737 : : int err;
2738 : :
2739 : 0 : blocksize = 1 << inode->i_blkbits;
2740 : 0 : length = offset & (blocksize - 1);
2741 : :
2742 : : /* Block boundary? Nothing to do */
2743 [ # # ]: 0 : if (!length)
2744 : : return 0;
2745 : :
2746 : 0 : length = blocksize - length;
2747 : 0 : iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2748 : :
2749 : : page = grab_cache_page(mapping, index);
2750 : : err = -ENOMEM;
2751 [ # # ]: 0 : if (!page)
2752 : : goto out;
2753 : :
2754 [ # # ]: 0 : if (page_has_buffers(page)) {
2755 : : has_buffers:
2756 : 0 : unlock_page(page);
2757 : 0 : page_cache_release(page);
2758 : 0 : return block_truncate_page(mapping, from, get_block);
2759 : : }
2760 : :
2761 : : /* Find the buffer that contains "offset" */
2762 : : pos = blocksize;
2763 [ # # ]: 0 : while (offset >= pos) {
2764 : 0 : iblock++;
2765 : 0 : pos += blocksize;
2766 : : }
2767 : :
2768 : 0 : map_bh.b_size = blocksize;
2769 : 0 : map_bh.b_state = 0;
2770 : 0 : err = get_block(inode, iblock, &map_bh, 0);
2771 [ # # ]: 0 : if (err)
2772 : : goto unlock;
2773 : : /* unmapped? It's a hole - nothing to do */
2774 [ # # ]: 0 : if (!buffer_mapped(&map_bh))
2775 : : goto unlock;
2776 : :
2777 : : /* Ok, it's mapped. Make sure it's up-to-date */
2778 [ # # ]: 0 : if (!PageUptodate(page)) {
2779 : 0 : err = mapping->a_ops->readpage(NULL, page);
2780 [ # # ]: 0 : if (err) {
2781 : 0 : page_cache_release(page);
2782 : 0 : goto out;
2783 : : }
2784 : : lock_page(page);
2785 [ # # ]: 0 : if (!PageUptodate(page)) {
2786 : : err = -EIO;
2787 : : goto unlock;
2788 : : }
2789 [ # # ]: 0 : if (page_has_buffers(page))
2790 : : goto has_buffers;
2791 : : }
2792 : : zero_user(page, offset, length);
2793 : 0 : set_page_dirty(page);
2794 : : err = 0;
2795 : :
2796 : : unlock:
2797 : 0 : unlock_page(page);
2798 : 0 : page_cache_release(page);
2799 : : out:
2800 : 0 : return err;
2801 : : }
2802 : : EXPORT_SYMBOL(nobh_truncate_page);
2803 : :
2804 : 0 : int block_truncate_page(struct address_space *mapping,
2805 : : loff_t from, get_block_t *get_block)
2806 : : {
2807 : 0 : pgoff_t index = from >> PAGE_CACHE_SHIFT;
2808 : 0 : unsigned offset = from & (PAGE_CACHE_SIZE-1);
2809 : : unsigned blocksize;
2810 : : sector_t iblock;
2811 : : unsigned length, pos;
2812 : 0 : struct inode *inode = mapping->host;
2813 : : struct page *page;
2814 : : struct buffer_head *bh;
2815 : : int err;
2816 : :
2817 : 0 : blocksize = 1 << inode->i_blkbits;
2818 : 0 : length = offset & (blocksize - 1);
2819 : :
2820 : : /* Block boundary? Nothing to do */
2821 [ # # ]: 0 : if (!length)
2822 : : return 0;
2823 : :
2824 : 0 : length = blocksize - length;
2825 : 0 : iblock = (sector_t)index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
2826 : :
2827 : : page = grab_cache_page(mapping, index);
2828 : : err = -ENOMEM;
2829 [ # # ]: 0 : if (!page)
2830 : : goto out;
2831 : :
2832 [ # # ]: 0 : if (!page_has_buffers(page))
2833 : 0 : create_empty_buffers(page, blocksize, 0);
2834 : :
2835 : : /* Find the buffer that contains "offset" */
2836 [ # # ]: 0 : bh = page_buffers(page);
2837 : : pos = blocksize;
2838 [ # # ]: 0 : while (offset >= pos) {
2839 : 0 : bh = bh->b_this_page;
2840 : 0 : iblock++;
2841 : 0 : pos += blocksize;
2842 : : }
2843 : :
2844 : : err = 0;
2845 [ # # ]: 0 : if (!buffer_mapped(bh)) {
2846 [ # # ]: 0 : WARN_ON(bh->b_size != blocksize);
2847 : 0 : err = get_block(inode, iblock, bh, 0);
2848 [ # # ]: 0 : if (err)
2849 : : goto unlock;
2850 : : /* unmapped? It's a hole - nothing to do */
2851 [ # # ]: 0 : if (!buffer_mapped(bh))
2852 : : goto unlock;
2853 : : }
2854 : :
2855 : : /* Ok, it's mapped. Make sure it's up-to-date */
2856 [ # # ]: 0 : if (PageUptodate(page))
2857 : 0 : set_buffer_uptodate(bh);
2858 : :
2859 [ # # ][ # # ]: 0 : if (!buffer_uptodate(bh) && !buffer_delay(bh) && !buffer_unwritten(bh)) {
[ # # ]
2860 : : err = -EIO;
2861 : 0 : ll_rw_block(READ, 1, &bh);
2862 : 0 : wait_on_buffer(bh);
2863 : : /* Uhhuh. Read error. Complain and punt. */
2864 [ # # ]: 0 : if (!buffer_uptodate(bh))
2865 : : goto unlock;
2866 : : }
2867 : :
2868 : : zero_user(page, offset, length);
2869 : 0 : mark_buffer_dirty(bh);
2870 : : err = 0;
2871 : :
2872 : : unlock:
2873 : 0 : unlock_page(page);
2874 : 0 : page_cache_release(page);
2875 : : out:
2876 : 0 : return err;
2877 : : }
2878 : : EXPORT_SYMBOL(block_truncate_page);
2879 : :
2880 : : /*
2881 : : * The generic ->writepage function for buffer-backed address_spaces
2882 : : * this form passes in the end_io handler used to finish the IO.
2883 : : */
2884 : 0 : int block_write_full_page_endio(struct page *page, get_block_t *get_block,
2885 : : struct writeback_control *wbc, bh_end_io_t *handler)
2886 : : {
2887 : 23984 : struct inode * const inode = page->mapping->host;
2888 : : loff_t i_size = i_size_read(inode);
2889 : 23984 : const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
2890 : : unsigned offset;
2891 : :
2892 : : /* Is the page fully inside i_size? */
2893 [ + + ]: 23984 : if (page->index < end_index)
2894 : 23983 : return __block_write_full_page(inode, page, get_block, wbc,
2895 : : handler);
2896 : :
2897 : : /* Is the page fully outside i_size? (truncate in progress) */
2898 : 1 : offset = i_size & (PAGE_CACHE_SIZE-1);
2899 [ + - ][ - + ]: 1 : if (page->index >= end_index+1 || !offset) {
2900 : : /*
2901 : : * The page may have dirty, unmapped buffers. For example,
2902 : : * they may have been added in ext3_writepage(). Make them
2903 : : * freeable here, so the page does not leak.
2904 : : */
2905 : 0 : do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
2906 : 0 : unlock_page(page);
2907 : 0 : return 0; /* don't care */
2908 : : }
2909 : :
2910 : : /*
2911 : : * The page straddles i_size. It must be zeroed out on each and every
2912 : : * writepage invocation because it may be mmapped. "A file is mapped
2913 : : * in multiples of the page size. For a file that is not a multiple of
2914 : : * the page size, the remaining memory is zeroed when mapped, and
2915 : : * writes to that region are not written out to the file."
2916 : : */
2917 : : zero_user_segment(page, offset, PAGE_CACHE_SIZE);
2918 : 1 : return __block_write_full_page(inode, page, get_block, wbc, handler);
2919 : : }
2920 : : EXPORT_SYMBOL(block_write_full_page_endio);
2921 : :
2922 : : /*
2923 : : * The generic ->writepage function for buffer-backed address_spaces
2924 : : */
2925 : 0 : int block_write_full_page(struct page *page, get_block_t *get_block,
2926 : : struct writeback_control *wbc)
2927 : : {
2928 : 23984 : return block_write_full_page_endio(page, get_block, wbc,
2929 : : end_buffer_async_write);
2930 : : }
2931 : : EXPORT_SYMBOL(block_write_full_page);
2932 : :
2933 : 0 : sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
2934 : : get_block_t *get_block)
2935 : : {
2936 : : struct buffer_head tmp;
2937 : 123440 : struct inode *inode = mapping->host;
2938 : 123440 : tmp.b_state = 0;
2939 : 123440 : tmp.b_blocknr = 0;
2940 : 123440 : tmp.b_size = 1 << inode->i_blkbits;
2941 : 123440 : get_block(inode, block, &tmp, 0);
2942 : 123440 : return tmp.b_blocknr;
2943 : : }
2944 : : EXPORT_SYMBOL(generic_block_bmap);
2945 : :
2946 : 0 : static void end_bio_bh_io_sync(struct bio *bio, int err)
2947 : : {
2948 : 118497 : struct buffer_head *bh = bio->bi_private;
2949 : :
2950 [ - + ]: 118497 : if (err == -EOPNOTSUPP) {
2951 : 0 : set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
2952 : : }
2953 : :
2954 [ - + ]: 118497 : if (unlikely (test_bit(BIO_QUIET,&bio->bi_flags)))
2955 : 0 : set_bit(BH_Quiet, &bh->b_state);
2956 : :
2957 : 118497 : bh->b_end_io(bh, test_bit(BIO_UPTODATE, &bio->bi_flags));
2958 : 118497 : bio_put(bio);
2959 : 118497 : }
2960 : :
2961 : : /*
2962 : : * This allows us to do IO even on the odd last sectors
2963 : : * of a device, even if the bh block size is some multiple
2964 : : * of the physical sector size.
2965 : : *
2966 : : * We'll just truncate the bio to the size of the device,
2967 : : * and clear the end of the buffer head manually.
2968 : : *
2969 : : * Truly out-of-range accesses will turn into actual IO
2970 : : * errors, this only handles the "we need to be able to
2971 : : * do IO at the final sector" case.
2972 : : */
2973 : 0 : static void guard_bh_eod(int rw, struct bio *bio, struct buffer_head *bh)
2974 : : {
2975 : : sector_t maxsector;
2976 : : unsigned bytes;
2977 : :
2978 : 118498 : maxsector = i_size_read(bio->bi_bdev->bd_inode) >> 9;
2979 [ + - ]: 118498 : if (!maxsector)
2980 : : return;
2981 : :
2982 : : /*
2983 : : * If the *whole* IO is past the end of the device,
2984 : : * let it through, and the IO layer will turn it into
2985 : : * an EIO.
2986 : : */
2987 [ + - ]: 118498 : if (unlikely(bio->bi_iter.bi_sector >= maxsector))
2988 : : return;
2989 : :
2990 : 118498 : maxsector -= bio->bi_iter.bi_sector;
2991 : 118498 : bytes = bio->bi_iter.bi_size;
2992 [ - + ]: 118498 : if (likely((bytes >> 9) <= maxsector))
2993 : : return;
2994 : :
2995 : : /* Uhhuh. We've got a bh that straddles the device size! */
2996 : 0 : bytes = maxsector << 9;
2997 : :
2998 : : /* Truncate the bio.. */
2999 : 0 : bio->bi_iter.bi_size = bytes;
3000 : 0 : bio->bi_io_vec[0].bv_len = bytes;
3001 : :
3002 : : /* ..and clear the end of the buffer for reads */
3003 [ # # ]: 0 : if ((rw & RW_MASK) == READ) {
3004 : 0 : void *kaddr = kmap_atomic(bh->b_page);
3005 [ # # ]: 0 : memset(kaddr + bh_offset(bh) + bytes, 0, bh->b_size - bytes);
3006 : 0 : kunmap_atomic(kaddr);
3007 : 0 : flush_dcache_page(bh->b_page);
3008 : : }
3009 : : }
3010 : :
3011 : 0 : int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
3012 : : {
3013 : : struct bio *bio;
3014 : : int ret = 0;
3015 : :
3016 [ - + ]: 118498 : BUG_ON(!buffer_locked(bh));
3017 [ - + ]: 118498 : BUG_ON(!buffer_mapped(bh));
3018 [ - + ]: 118498 : BUG_ON(!bh->b_end_io);
3019 [ - + ]: 118498 : BUG_ON(buffer_delay(bh));
3020 [ - + ]: 118498 : BUG_ON(buffer_unwritten(bh));
3021 : :
3022 : : /*
3023 : : * Only clear out a write error when rewriting
3024 : : */
3025 [ + + ][ + - ]: 118498 : if (test_set_buffer_req(bh) && (rw & WRITE))
3026 : : clear_buffer_write_io_error(bh);
3027 : :
3028 : : /*
3029 : : * from here on down, it's all bio -- do the initial mapping,
3030 : : * submit_bio -> generic_make_request may further map this bio around
3031 : : */
3032 : : bio = bio_alloc(GFP_NOIO, 1);
3033 : :
3034 : 118498 : bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
3035 : 118498 : bio->bi_bdev = bh->b_bdev;
3036 : 118498 : bio->bi_io_vec[0].bv_page = bh->b_page;
3037 : 118498 : bio->bi_io_vec[0].bv_len = bh->b_size;
3038 : 118498 : bio->bi_io_vec[0].bv_offset = bh_offset(bh);
3039 : :
3040 : 118498 : bio->bi_vcnt = 1;
3041 : 118498 : bio->bi_iter.bi_size = bh->b_size;
3042 : :
3043 : 118498 : bio->bi_end_io = end_bio_bh_io_sync;
3044 : 118498 : bio->bi_private = bh;
3045 : 118498 : bio->bi_flags |= bio_flags;
3046 : :
3047 : : /* Take care of bh's that straddle the end of the device */
3048 : 118498 : guard_bh_eod(rw, bio, bh);
3049 : :
3050 [ + + ]: 118498 : if (buffer_meta(bh))
3051 : 13595 : rw |= REQ_META;
3052 [ + + ]: 118498 : if (buffer_prio(bh))
3053 : 13595 : rw |= REQ_PRIO;
3054 : :
3055 : 0 : bio_get(bio);
3056 : 118498 : submit_bio(rw, bio);
3057 : :
3058 [ - + ]: 118497 : if (bio_flagged(bio, BIO_EOPNOTSUPP))
3059 : : ret = -EOPNOTSUPP;
3060 : :
3061 : 118497 : bio_put(bio);
3062 : 118498 : return ret;
3063 : : }
3064 : : EXPORT_SYMBOL_GPL(_submit_bh);
3065 : :
3066 : 0 : int submit_bh(int rw, struct buffer_head *bh)
3067 : : {
3068 : 118488 : return _submit_bh(rw, bh, 0);
3069 : : }
3070 : : EXPORT_SYMBOL(submit_bh);
3071 : :
3072 : : /**
3073 : : * ll_rw_block: low-level access to block devices (DEPRECATED)
3074 : : * @rw: whether to %READ or %WRITE or maybe %READA (readahead)
3075 : : * @nr: number of &struct buffer_heads in the array
3076 : : * @bhs: array of pointers to &struct buffer_head
3077 : : *
3078 : : * ll_rw_block() takes an array of pointers to &struct buffer_heads, and
3079 : : * requests an I/O operation on them, either a %READ or a %WRITE. The third
3080 : : * %READA option is described in the documentation for generic_make_request()
3081 : : * which ll_rw_block() calls.
3082 : : *
3083 : : * This function drops any buffer that it cannot get a lock on (with the
3084 : : * BH_Lock state bit), any buffer that appears to be clean when doing a write
3085 : : * request, and any buffer that appears to be up-to-date when doing read
3086 : : * request. Further it marks as clean buffers that are processed for
3087 : : * writing (the buffer cache won't assume that they are actually clean
3088 : : * until the buffer gets unlocked).
3089 : : *
3090 : : * ll_rw_block sets b_end_io to simple completion handler that marks
3091 : : * the buffer up-to-date (if approriate), unlocks the buffer and wakes
3092 : : * any waiters.
3093 : : *
3094 : : * All of the buffers must be for the same device, and must also be a
3095 : : * multiple of the current approved size for the device.
3096 : : */
3097 : 0 : void ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
3098 : : {
3099 : : int i;
3100 : :
3101 [ + + ]: 1251637 : for (i = 0; i < nr; i++) {
3102 : 625862 : struct buffer_head *bh = bhs[i];
3103 : :
3104 [ + + ]: 625626 : if (!trylock_buffer(bh))
3105 : 207 : continue;
3106 [ - + ]: 625419 : if (rw == WRITE) {
3107 [ # # ]: 0 : if (test_clear_buffer_dirty(bh)) {
3108 : 0 : bh->b_end_io = end_buffer_write_sync;
3109 : : get_bh(bh);
3110 : : submit_bh(WRITE, bh);
3111 : 0 : continue;
3112 : : }
3113 : : } else {
3114 [ + + ]: 625419 : if (!buffer_uptodate(bh)) {
3115 : 7163 : bh->b_end_io = end_buffer_read_sync;
3116 : : get_bh(bh);
3117 : : submit_bh(rw, bh);
3118 : 7163 : continue;
3119 : : }
3120 : : }
3121 : 618256 : unlock_buffer(bh);
3122 : : }
3123 : 625775 : }
3124 : : EXPORT_SYMBOL(ll_rw_block);
3125 : :
3126 : 0 : void write_dirty_buffer(struct buffer_head *bh, int rw)
3127 : : {
3128 : : lock_buffer(bh);
3129 [ - + ]: 560 : if (!test_clear_buffer_dirty(bh)) {
3130 : 0 : unlock_buffer(bh);
3131 : 0 : return;
3132 : : }
3133 : 560 : bh->b_end_io = end_buffer_write_sync;
3134 : : get_bh(bh);
3135 : : submit_bh(rw, bh);
3136 : : }
3137 : : EXPORT_SYMBOL(write_dirty_buffer);
3138 : :
3139 : : /*
3140 : : * For a data-integrity writeout, we need to wait upon any in-progress I/O
3141 : : * and then start new I/O and then wait upon it. The caller must have a ref on
3142 : : * the buffer_head.
3143 : : */
3144 : 0 : int __sync_dirty_buffer(struct buffer_head *bh, int rw)
3145 : : {
3146 : : int ret = 0;
3147 : :
3148 [ - + ]: 59 : WARN_ON(atomic_read(&bh->b_count) < 1);
3149 : : lock_buffer(bh);
3150 [ + - ]: 59 : if (test_clear_buffer_dirty(bh)) {
3151 : : get_bh(bh);
3152 : 59 : bh->b_end_io = end_buffer_write_sync;
3153 : : ret = submit_bh(rw, bh);
3154 : : wait_on_buffer(bh);
3155 [ + - ][ - + ]: 59 : if (!ret && !buffer_uptodate(bh))
3156 : : ret = -EIO;
3157 : : } else {
3158 : 0 : unlock_buffer(bh);
3159 : : }
3160 : 59 : return ret;
3161 : : }
3162 : : EXPORT_SYMBOL(__sync_dirty_buffer);
3163 : :
3164 : 0 : int sync_dirty_buffer(struct buffer_head *bh)
3165 : : {
3166 : 58 : return __sync_dirty_buffer(bh, WRITE_SYNC);
3167 : : }
3168 : : EXPORT_SYMBOL(sync_dirty_buffer);
3169 : :
3170 : : /*
3171 : : * try_to_free_buffers() checks if all the buffers on this particular page
3172 : : * are unused, and releases them if so.
3173 : : *
3174 : : * Exclusion against try_to_free_buffers may be obtained by either
3175 : : * locking the page or by holding its mapping's private_lock.
3176 : : *
3177 : : * If the page is dirty but all the buffers are clean then we need to
3178 : : * be sure to mark the page clean as well. This is because the page
3179 : : * may be against a block device, and a later reattachment of buffers
3180 : : * to a dirty page will set *all* buffers dirty. Which would corrupt
3181 : : * filesystem data on the same device.
3182 : : *
3183 : : * The same applies to regular filesystem pages: if all the buffers are
3184 : : * clean then we set the page clean and proceed. To do that, we require
3185 : : * total exclusion from __set_page_dirty_buffers(). That is obtained with
3186 : : * private_lock.
3187 : : *
3188 : : * try_to_free_buffers() is non-blocking.
3189 : : */
3190 : : static inline int buffer_busy(struct buffer_head *bh)
3191 : : {
3192 : 3683554 : return atomic_read(&bh->b_count) |
3193 : 1841777 : (bh->b_state & ((1 << BH_Dirty) | (1 << BH_Lock)));
3194 : : }
3195 : :
3196 : : static int
3197 : 0 : drop_buffers(struct page *page, struct buffer_head **buffers_to_free)
3198 : : {
3199 [ - + ]: 1840448 : struct buffer_head *head = page_buffers(page);
3200 : : struct buffer_head *bh;
3201 : :
3202 : : bh = head;
3203 : : do {
3204 [ - + ][ # # ]: 1841749 : if (buffer_write_io_error(bh) && page->mapping)
3205 : 0 : set_bit(AS_EIO, &page->mapping->flags);
3206 [ + + ]: 1841777 : if (buffer_busy(bh))
3207 : : goto failed;
3208 : 1825094 : bh = bh->b_this_page;
3209 [ + + ]: 1825094 : } while (bh != head);
3210 : :
3211 : : do {
3212 : 1825125 : struct buffer_head *next = bh->b_this_page;
3213 : :
3214 [ - + ]: 1825125 : if (bh->b_assoc_map)
3215 : 0 : __remove_assoc_queue(bh);
3216 : : bh = next;
3217 [ + + ]: 1825196 : } while (bh != head);
3218 : 1823864 : *buffers_to_free = head;
3219 : 1823864 : __clear_page_buffers(page);
3220 : 1823793 : return 1;
3221 : : failed:
3222 : : return 0;
3223 : : }
3224 : :
3225 : 0 : int try_to_free_buffers(struct page *page)
3226 : : {
3227 : 1840496 : struct address_space * const mapping = page->mapping;
3228 : 1840496 : struct buffer_head *buffers_to_free = NULL;
3229 : : int ret = 0;
3230 : :
3231 [ - + ]: 1840496 : BUG_ON(!PageLocked(page));
3232 [ + ]: 1840496 : if (PageWriteback(page))
3233 : : return 0;
3234 : :
3235 [ + + ]: 1840526 : if (mapping == NULL) { /* can this still happen? */
3236 : 48 : ret = drop_buffers(page, &buffers_to_free);
3237 : 48 : goto out;
3238 : : }
3239 : :
3240 : : spin_lock(&mapping->private_lock);
3241 : 1840452 : ret = drop_buffers(page, &buffers_to_free);
3242 : :
3243 : : /*
3244 : : * If the filesystem writes its buffers by hand (eg ext3)
3245 : : * then we can have clean buffers against a dirty page. We
3246 : : * clean the page here; otherwise the VM will never notice
3247 : : * that the filesystem did any IO at all.
3248 : : *
3249 : : * Also, during truncate, discard_buffer will have marked all
3250 : : * the page's buffers clean. We discover that here and clean
3251 : : * the page also.
3252 : : *
3253 : : * private_lock must be held over this entire operation in order
3254 : : * to synchronise against __set_page_dirty_buffers and prevent the
3255 : : * dirty bit from being lost.
3256 : : */
3257 [ + + ]: 1840432 : if (ret)
3258 : 1823751 : cancel_dirty_page(page, PAGE_CACHE_SIZE);
3259 : : spin_unlock(&mapping->private_lock);
3260 : : out:
3261 [ + + ]: 3681121 : if (buffers_to_free) {
3262 : : struct buffer_head *bh = buffers_to_free;
3263 : :
3264 : : do {
3265 : 1825250 : struct buffer_head *next = bh->b_this_page;
3266 : 1825250 : free_buffer_head(bh);
3267 : : bh = next;
3268 [ + + ]: 1825184 : } while (bh != buffers_to_free);
3269 : : }
3270 : 1840559 : return ret;
3271 : : }
3272 : : EXPORT_SYMBOL(try_to_free_buffers);
3273 : :
3274 : : /*
3275 : : * There are no bdflush tunables left. But distributions are
3276 : : * still running obsolete flush daemons, so we terminate them here.
3277 : : *
3278 : : * Use of bdflush() is deprecated and will be removed in a future kernel.
3279 : : * The `flush-X' kernel threads fully replace bdflush daemons and this call.
3280 : : */
3281 : 0 : SYSCALL_DEFINE2(bdflush, int, func, long, data)
3282 : : {
3283 : : static int msg_count;
3284 : :
3285 [ + - ]: 1 : if (!capable(CAP_SYS_ADMIN))
3286 : : return -EPERM;
3287 : :
3288 [ + - ]: 1 : if (msg_count < 5) {
3289 : 1 : msg_count++;
3290 : 1 : printk(KERN_INFO
3291 : : "warning: process `%s' used the obsolete bdflush"
3292 : 1 : " system call\n", current->comm);
3293 : 1 : printk(KERN_INFO "Fix your initscripts?\n");
3294 : : }
3295 : :
3296 [ - + ]: 1 : if (func == 1)
3297 : 0 : do_exit(0);
3298 : : return 0;
3299 : : }
3300 : :
3301 : : /*
3302 : : * Buffer-head allocation
3303 : : */
3304 : : static struct kmem_cache *bh_cachep __read_mostly;
3305 : :
3306 : : /*
3307 : : * Once the number of bh's in the machine exceeds this level, we start
3308 : : * stripping them in writeback.
3309 : : */
3310 : : static unsigned long max_buffer_heads;
3311 : :
3312 : : int buffer_heads_over_limit;
3313 : :
3314 : : struct bh_accounting {
3315 : : int nr; /* Number of live bh's */
3316 : : int ratelimit; /* Limit cacheline bouncing */
3317 : : };
3318 : :
3319 : : static DEFINE_PER_CPU(struct bh_accounting, bh_accounting) = {0, 0};
3320 : :
3321 : 0 : static void recalc_bh_state(void)
3322 : : {
3323 : : int i;
3324 : : int tot = 0;
3325 : :
3326 [ + + ]: 3759148 : if (__this_cpu_inc_return(bh_accounting.ratelimit) - 1 < 4096)
3327 : 3759148 : return;
3328 : 1834 : __this_cpu_write(bh_accounting.ratelimit, 0);
3329 [ + + ]: 3765567 : for_each_online_cpu(i)
3330 : 4585 : tot += per_cpu(bh_accounting, i).nr;
3331 : 917 : buffer_heads_over_limit = (tot > max_buffer_heads);
3332 : : }
3333 : :
3334 : 0 : struct buffer_head *alloc_buffer_head(gfp_t gfp_flags)
3335 : : {
3336 : 1880290 : struct buffer_head *ret = kmem_cache_zalloc(bh_cachep, gfp_flags);
3337 [ + ]: 1882967 : if (ret) {
3338 : 1882978 : INIT_LIST_HEAD(&ret->b_assoc_buffers);
3339 : 1882978 : preempt_disable();
3340 : 3765910 : __this_cpu_inc(bh_accounting.nr);
3341 : 1882955 : recalc_bh_state();
3342 : 1882497 : preempt_enable();
3343 : : }
3344 : 2240 : return ret;
3345 : : }
3346 : : EXPORT_SYMBOL(alloc_buffer_head);
3347 : :
3348 : 0 : void free_buffer_head(struct buffer_head *bh)
3349 : : {
3350 [ - + ]: 1876938 : BUG_ON(!list_empty(&bh->b_assoc_buffers));
3351 : 1876938 : kmem_cache_free(bh_cachep, bh);
3352 : 1876966 : preempt_disable();
3353 : 3753940 : __this_cpu_dec(bh_accounting.nr);
3354 : 1876970 : recalc_bh_state();
3355 : 1876919 : preempt_enable();
3356 : 1876924 : }
3357 : : EXPORT_SYMBOL(free_buffer_head);
3358 : :
3359 : 0 : static void buffer_exit_cpu(int cpu)
3360 : : {
3361 : : int i;
3362 : 78 : struct bh_lru *b = &per_cpu(bh_lrus, cpu);
3363 : :
3364 [ + + ]: 702 : for (i = 0; i < BH_LRU_SIZE; i++) {
3365 : 624 : brelse(b->bhs[i]);
3366 : 624 : b->bhs[i] = NULL;
3367 : : }
3368 : 156 : this_cpu_add(bh_accounting.nr, per_cpu(bh_accounting, cpu).nr);
3369 : 78 : per_cpu(bh_accounting, cpu).nr = 0;
3370 : 78 : }
3371 : :
3372 : 0 : static int buffer_cpu_notify(struct notifier_block *self,
3373 : : unsigned long action, void *hcpu)
3374 : : {
3375 [ + + ]: 555 : if (action == CPU_DEAD || action == CPU_DEAD_FROZEN)
3376 : 78 : buffer_exit_cpu((unsigned long)hcpu);
3377 : 0 : return NOTIFY_OK;
3378 : : }
3379 : :
3380 : : /**
3381 : : * bh_uptodate_or_lock - Test whether the buffer is uptodate
3382 : : * @bh: struct buffer_head
3383 : : *
3384 : : * Return true if the buffer is up-to-date and false,
3385 : : * with the buffer locked, if not.
3386 : : */
3387 : 0 : int bh_uptodate_or_lock(struct buffer_head *bh)
3388 : : {
3389 [ + + ]: 417905 : if (!buffer_uptodate(bh)) {
3390 : : lock_buffer(bh);
3391 [ - + ]: 18 : if (!buffer_uptodate(bh))
3392 : : return 0;
3393 : 0 : unlock_buffer(bh);
3394 : : }
3395 : : return 1;
3396 : : }
3397 : : EXPORT_SYMBOL(bh_uptodate_or_lock);
3398 : :
3399 : : /**
3400 : : * bh_submit_read - Submit a locked buffer for reading
3401 : : * @bh: struct buffer_head
3402 : : *
3403 : : * Returns zero on success and -EIO on error.
3404 : : */
3405 : 0 : int bh_submit_read(struct buffer_head *bh)
3406 : : {
3407 [ - + ]: 17 : BUG_ON(!buffer_locked(bh));
3408 : :
3409 [ - + ]: 17 : if (buffer_uptodate(bh)) {
3410 : 0 : unlock_buffer(bh);
3411 : 0 : return 0;
3412 : : }
3413 : :
3414 : : get_bh(bh);
3415 : 17 : bh->b_end_io = end_buffer_read_sync;
3416 : : submit_bh(READ, bh);
3417 : : wait_on_buffer(bh);
3418 [ - + ]: 34 : if (buffer_uptodate(bh))
3419 : : return 0;
3420 : 0 : return -EIO;
3421 : : }
3422 : : EXPORT_SYMBOL(bh_submit_read);
3423 : :
3424 : 0 : void __init buffer_init(void)
3425 : : {
3426 : : unsigned long nrpages;
3427 : :
3428 : 0 : bh_cachep = kmem_cache_create("buffer_head",
3429 : : sizeof(struct buffer_head), 0,
3430 : : (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC|
3431 : : SLAB_MEM_SPREAD),
3432 : : NULL);
3433 : :
3434 : : /*
3435 : : * Limit the bh occupancy to 10% of ZONE_NORMAL
3436 : : */
3437 : 0 : nrpages = (nr_free_buffer_pages() * 10) / 100;
3438 : 0 : max_buffer_heads = nrpages * (PAGE_SIZE / sizeof(struct buffer_head));
3439 : 0 : hotcpu_notifier(buffer_cpu_notify, 0);
3440 : 0 : }
|
