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| author | Nick Piggin <npiggin@suse.de> | 2006-09-25 23:31:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-26 08:48:48 -0700 |
| commit | db37648cd6ce9b828abd6d49aa3d269926ee7b7d (patch) | |
| tree | a0155c7897f4706386d10c8718f98687bc357c82 /include | |
| parent | 28e4d965e6131ace1e813e93aebca89ac6b82dc1 (diff) | |
| download | op-kernel-dev-db37648cd6ce9b828abd6d49aa3d269926ee7b7d.zip op-kernel-dev-db37648cd6ce9b828abd6d49aa3d269926ee7b7d.tar.gz | |
[PATCH] mm: non syncing lock_page()
lock_page needs the caller to have a reference on the page->mapping inode
due to sync_page, ergo set_page_dirty_lock is obviously buggy according to
its comments.
Solve it by introducing a new lock_page_nosync which does not do a sync_page.
akpm: unpleasant solution to an unpleasant problem. If it goes wrong it could
cause great slowdowns while the lock_page() caller waits for kblockd to
perform the unplug. And if a filesystem has special sync_page() requirements
(none presently do), permanent hangs are possible.
otoh, set_page_dirty_lock() is usually (always?) called against userspace
pages. They are always up-to-date, so there shouldn't be any pending read I/O
against these pages.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/pagemap.h | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0a2f5d2..64f9509 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -130,14 +130,29 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma, } extern void FASTCALL(__lock_page(struct page *page)); +extern void FASTCALL(__lock_page_nosync(struct page *page)); extern void FASTCALL(unlock_page(struct page *page)); +/* + * lock_page may only be called if we have the page's inode pinned. + */ static inline void lock_page(struct page *page) { might_sleep(); if (TestSetPageLocked(page)) __lock_page(page); } + +/* + * lock_page_nosync should only be used if we can't pin the page's inode. + * Doesn't play quite so well with block device plugging. + */ +static inline void lock_page_nosync(struct page *page) +{ + might_sleep(); + if (TestSetPageLocked(page)) + __lock_page_nosync(page); +} /* * This is exported only for wait_on_page_locked/wait_on_page_writeback. |
