Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=87df7241bd547da5d4d4a4e5397866dfe422e439
Commit: 87df7241bd547da5d4d4a4e5397866dfe422e439
Parent: 4cbf2aa35e1c189db234190fefc6c83b139ef963
Author: Nick Piggin <[EMAIL PROTECTED]>
AuthorDate: Tue Jan 30 14:36:27 2007 +1100
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon Jan 29 20:20:42 2007 -0800
[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 <[EMAIL PROTECTED]>
Acked-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
fs/buffer.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 460f1c4..1ad674f 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;
-
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