Clean up and make try_to_free_buffers() not race with dirty pages
This is preparatory work in our continuing saga on some hard-to-trigger
file corruption with shared writable mmap() after the dirty page
tracking changes (commit d08b3851da41d0ee60851f2c75b118e1f7a5fc89 etc)
were merged.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/buffer.c b/fs/buffer.c
index d1f1b54..263f88e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2834,7 +2834,7 @@
int ret = 0;
BUG_ON(!PageLocked(page));
- if (PageWriteback(page))
+ if (PageDirty(page) || PageWriteback(page))
return 0;
if (mapping == NULL) { /* can this still happen? */
@@ -2845,22 +2845,6 @@
spin_lock(&mapping->private_lock);
ret = drop_buffers(page, &buffers_to_free);
spin_unlock(&mapping->private_lock);
- if (ret) {
- /*
- * If the filesystem writes its buffers by hand (eg ext3)
- * then we can have clean buffers against a dirty page. We
- * clean the page here; otherwise later reattachment of buffers
- * could encounter a non-uptodate page, which is unresolvable.
- * This only applies in the rare case where try_to_free_buffers
- * succeeds but the page is not freed.
- *
- * Also, during truncate, discard_buffer will have marked all
- * the page's buffers clean. We discover that here and clean
- * the page also.
- */
- if (test_clear_page_dirty(page))
- task_io_account_cancelled_write(PAGE_CACHE_SIZE);
- }
out:
if (buffers_to_free) {
struct buffer_head *bh = buffers_to_free;