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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 d08b3851da etc)
were merged.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Linus Torvalds 2006-12-19 15:21:59 -08:00
parent 9bfb18392e
commit 46d2277c79
1 changed files with 1 additions and 17 deletions
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18
fs/buffer.c
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@ -2834,7 +2834,7 @@ int try_to_free_buffers(struct page *page)
int ret = 0; int ret = 0;
BUG_ON(!PageLocked(page)); BUG_ON(!PageLocked(page));
if (PageWriteback(page)) if (PageDirty(page) || PageWriteback(page))
return 0; return 0;
if (mapping == NULL) { /* can this still happen? */ if (mapping == NULL) { /* can this still happen? */
@ -2845,22 +2845,6 @@ int try_to_free_buffers(struct page *page)
spin_lock(&mapping->private_lock); spin_lock(&mapping->private_lock);
ret = drop_buffers(page, &buffers_to_free); ret = drop_buffers(page, &buffers_to_free);
spin_unlock(&mapping->private_lock); 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: out:
if (buffers_to_free) { if (buffers_to_free) {
struct buffer_head *bh = buffers_to_free; struct buffer_head *bh = buffers_to_free;