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Commit 46d2277c authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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 d08b3851 etc)
were merged.

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9bfb1839

fs/buffer.c

+1 −17
Original line number Diff line number Diff line
@@ -2834,7 +2834,7 @@ int try_to_free_buffers(struct page *page) 
	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 @@ 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 (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;