From: Nick Piggin <npiggin@suse.de>
Date: Tue, 16 Oct 2007 08:25:00 +0000 (-0700)
Subject: fs: fix data-loss on error
X-Git-Tag: v2.6.24-rc1~1200
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=637aff46f94a754207c80c8c64bf1b74f24b967d;p=linux-2.6

fs: fix data-loss on error

New buffers against uptodate pages are simply be marked uptodate, while the
buffer_new bit remains set.  This causes error-case code to zero out parts of
those buffers because it thinks they contain stale data: wrong, they are
actually uptodate so this is a data loss situation.

Fix this by actually clearning buffer_new and marking the buffer dirty.  It
makes sense to always clear buffer_new before setting a buffer uptodate.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/buffer.c b/fs/buffer.c
index 09bb80c479..9ece6c2086 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1813,7 +1813,9 @@ static int __block_prepare_write(struct inode *inode, struct page *page,
 				unmap_underlying_metadata(bh->b_bdev,
 							bh->b_blocknr);
 				if (PageUptodate(page)) {
+					clear_buffer_new(bh);
 					set_buffer_uptodate(bh);
+					mark_buffer_dirty(bh);
 					continue;
 				}
 				if (block_end > to || block_start < from) {