diff options
Diffstat (limited to 'mm/filemap.c')
-rw-r--r-- | mm/filemap.c | 67 |
1 files changed, 6 insertions, 61 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index 83a45d35468b..380776c2a9ac 100644 --- a/mm/filemap.c +++ b/mm/filemap.c | |||
@@ -155,45 +155,15 @@ void remove_from_page_cache(struct page *page) | |||
155 | } | 155 | } |
156 | EXPORT_SYMBOL(remove_from_page_cache); | 156 | EXPORT_SYMBOL(remove_from_page_cache); |
157 | 157 | ||
158 | static int sync_page(void *word) | 158 | static int sleep_on_page(void *word) |
159 | { | 159 | { |
160 | struct address_space *mapping; | ||
161 | struct page *page; | ||
162 | |||
163 | page = container_of((unsigned long *)word, struct page, flags); | ||
164 | |||
165 | /* | ||
166 | * page_mapping() is being called without PG_locked held. | ||
167 | * Some knowledge of the state and use of the page is used to | ||
168 | * reduce the requirements down to a memory barrier. | ||
169 | * The danger here is of a stale page_mapping() return value | ||
170 | * indicating a struct address_space different from the one it's | ||
171 | * associated with when it is associated with one. | ||
172 | * After smp_mb(), it's either the correct page_mapping() for | ||
173 | * the page, or an old page_mapping() and the page's own | ||
174 | * page_mapping() has gone NULL. | ||
175 | * The ->sync_page() address_space operation must tolerate | ||
176 | * page_mapping() going NULL. By an amazing coincidence, | ||
177 | * this comes about because none of the users of the page | ||
178 | * in the ->sync_page() methods make essential use of the | ||
179 | * page_mapping(), merely passing the page down to the backing | ||
180 | * device's unplug functions when it's non-NULL, which in turn | ||
181 | * ignore it for all cases but swap, where only page_private(page) is | ||
182 | * of interest. When page_mapping() does go NULL, the entire | ||
183 | * call stack gracefully ignores the page and returns. | ||
184 | * -- wli | ||
185 | */ | ||
186 | smp_mb(); | ||
187 | mapping = page_mapping(page); | ||
188 | if (mapping && mapping->a_ops && mapping->a_ops->sync_page) | ||
189 | mapping->a_ops->sync_page(page); | ||
190 | io_schedule(); | 160 | io_schedule(); |
191 | return 0; | 161 | return 0; |
192 | } | 162 | } |
193 | 163 | ||
194 | static int sync_page_killable(void *word) | 164 | static int sleep_on_page_killable(void *word) |
195 | { | 165 | { |
196 | sync_page(word); | 166 | sleep_on_page(word); |
197 | return fatal_signal_pending(current) ? -EINTR : 0; | 167 | return fatal_signal_pending(current) ? -EINTR : 0; |
198 | } | 168 | } |
199 | 169 | ||
@@ -479,12 +449,6 @@ struct page *__page_cache_alloc(gfp_t gfp) | |||
479 | EXPORT_SYMBOL(__page_cache_alloc); | 449 | EXPORT_SYMBOL(__page_cache_alloc); |
480 | #endif | 450 | #endif |
481 | 451 | ||
482 | static int __sleep_on_page_lock(void *word) | ||
483 | { | ||
484 | io_schedule(); | ||
485 | return 0; | ||
486 | } | ||
487 | |||
488 | /* | 452 | /* |
489 | * In order to wait for pages to become available there must be | 453 | * In order to wait for pages to become available there must be |
490 | * waitqueues associated with pages. By using a hash table of | 454 | * waitqueues associated with pages. By using a hash table of |
@@ -512,7 +476,7 @@ void wait_on_page_bit(struct page *page, int bit_nr) | |||
512 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); | 476 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr); |
513 | 477 | ||
514 | if (test_bit(bit_nr, &page->flags)) | 478 | if (test_bit(bit_nr, &page->flags)) |
515 | __wait_on_bit(page_waitqueue(page), &wait, sync_page, | 479 | __wait_on_bit(page_waitqueue(page), &wait, sleep_on_page, |
516 | TASK_UNINTERRUPTIBLE); | 480 | TASK_UNINTERRUPTIBLE); |
517 | } | 481 | } |
518 | EXPORT_SYMBOL(wait_on_page_bit); | 482 | EXPORT_SYMBOL(wait_on_page_bit); |
@@ -576,17 +540,12 @@ EXPORT_SYMBOL(end_page_writeback); | |||
576 | /** | 540 | /** |
577 | * __lock_page - get a lock on the page, assuming we need to sleep to get it | 541 | * __lock_page - get a lock on the page, assuming we need to sleep to get it |
578 | * @page: the page to lock | 542 | * @page: the page to lock |
579 | * | ||
580 | * Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some | ||
581 | * random driver's requestfn sets TASK_RUNNING, we could busywait. However | ||
582 | * chances are that on the second loop, the block layer's plug list is empty, | ||
583 | * so sync_page() will then return in state TASK_UNINTERRUPTIBLE. | ||
584 | */ | 543 | */ |
585 | void __lock_page(struct page *page) | 544 | void __lock_page(struct page *page) |
586 | { | 545 | { |
587 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | 546 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
588 | 547 | ||
589 | __wait_on_bit_lock(page_waitqueue(page), &wait, sync_page, | 548 | __wait_on_bit_lock(page_waitqueue(page), &wait, sleep_on_page, |
590 | TASK_UNINTERRUPTIBLE); | 549 | TASK_UNINTERRUPTIBLE); |
591 | } | 550 | } |
592 | EXPORT_SYMBOL(__lock_page); | 551 | EXPORT_SYMBOL(__lock_page); |
@@ -596,24 +555,10 @@ int __lock_page_killable(struct page *page) | |||
596 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | 555 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); |
597 | 556 | ||
598 | return __wait_on_bit_lock(page_waitqueue(page), &wait, | 557 | return __wait_on_bit_lock(page_waitqueue(page), &wait, |
599 | sync_page_killable, TASK_KILLABLE); | 558 | sleep_on_page_killable, TASK_KILLABLE); |
600 | } | 559 | } |
601 | EXPORT_SYMBOL_GPL(__lock_page_killable); | 560 | EXPORT_SYMBOL_GPL(__lock_page_killable); |
602 | 561 | ||
603 | /** | ||
604 | * __lock_page_nosync - get a lock on the page, without calling sync_page() | ||
605 | * @page: the page to lock | ||
606 | * | ||
607 | * Variant of lock_page that does not require the caller to hold a reference | ||
608 | * on the page's mapping. | ||
609 | */ | ||
610 | void __lock_page_nosync(struct page *page) | ||
611 | { | ||
612 | DEFINE_WAIT_BIT(wait, &page->flags, PG_locked); | ||
613 | __wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock, | ||
614 | TASK_UNINTERRUPTIBLE); | ||
615 | } | ||
616 | |||
617 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, | 562 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm, |
618 | unsigned int flags) | 563 | unsigned int flags) |
619 | { | 564 | { |