diff options
| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2007-01-30 14:36:27 +1100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-01-29 20:20:42 -0800 |
| commit | 87df7241bd547da5d4d4a4e5397866dfe422e439 (patch) | |
| tree | ffe1e90a761aa358ef95e351e0718cb3c377ad37 | |
| parent | 4cbf2aa35e1c189db234190fefc6c83b139ef963 (diff) | |
[PATCH] Fix try_to_free_buffer() locking
Fix commit ecdfc9787fe527491baefc22dce8b2dbd5b2908d
Not to put too fine a point on it, but in a nutshell...
__set_page_dirty_buffers() | try_to_free_buffers()
---------------------------+---------------------------
| spin_lock(private_lock);
| drop_bufers()
| spin_unlock(private_lock);
spin_lock(private_lock) |
!page_has_buffers() |
spin_unlock(private_lock) |
SetPageDirty() |
| cancel_dirty_page()
oops!
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | fs/buffer.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 460f1c43238e..1ad674fd348c 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2844,7 +2844,6 @@ int try_to_free_buffers(struct page *page) spin_lock(&mapping->private_lock); ret = drop_buffers(page, &buffers_to_free); - spin_unlock(&mapping->private_lock); /* * If the filesystem writes its buffers by hand (eg ext3) @@ -2855,9 +2854,14 @@ int try_to_free_buffers(struct page *page) * Also, during truncate, discard_buffer will have marked all * the page's buffers clean. We discover that here and clean * the page also. + * + * private_lock must be held over this entire operation in order + * to synchronise against __set_page_dirty_buffers and prevent the + * dirty bit from being lost. */ if (ret) cancel_dirty_page(page, PAGE_CACHE_SIZE); + spin_unlock(&mapping->private_lock); out: if (buffers_to_free) { struct buffer_head *bh = buffers_to_free; |