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kernel-2.6.18-238.el5.src.rpm

From: Hideo AOKI <haoki@redhat.com>
Date: Thu, 21 Aug 2008 12:55:19 -0400
Subject: [fs] ext3: don't read inode block if buf has write error
Message-id: 48AD9DF7.5080603@redhat.com
O-Subject: [RHEL 5.3 PATCH 2/6] bz#439581: ext3: don't read inode block if the buffer has a write error
Bugzilla: 439581
RH-Acked-by: Josef Bacik <jbacik@redhat.com>
RH-Acked-by: Eric Sandeen <sandeen@redhat.com>

BZ#:
------
https://bugzilla.redhat.com/show_bug.cgi?id=439581

Upstream Status:
----------------
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=95450f5a7e53d5752ce1a0d0b8282e10fe745ae0

Description:
------------
A transient I/O error can corrupt inode data.  Here is the scenario:

(1) update inode_A at the block_B
(2) pdflush writes out new inode_A to the filesystem, but it results
    in write I/O error, at this point, BH_Uptodate flag of the buffer
    for block_B is cleared and BH_Write_EIO is set
(3) create new inode_C which located at block_B, and
    __ext3_get_inode_loc() tries to read on-disk block_B because the
    buffer is not uptodate
(4) if it can read on-disk block_B successfully, inode_A is
    overwritten by old data

This patch makes __ext3_get_inode_loc() not read the inode block if the
buffer has BH_Write_EIO flag.  In this case, the buffer should have the
latest information, so setting the uptodate flag to the buffer (this
avoids WARN_ON_ONCE() in mark_buffer_dirty().)

According to this change, we would need to test BH_Write_EIO flag for the
error checking.  Currently nobody checks write I/O errors on metadata
buffers, but it will be done in other patches I'm working on.

Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: sugita <yumiko.sugita.yf@hitachi.com>
Cc: Satoshi OSHIMA <satoshi.oshima.fk@hitachi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Jan Kara <jack@ucw.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 6cf0542..3d0bc9d 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -2467,6 +2467,16 @@ static int __ext3_get_inode_loc(struct inode *inode,
 	}
 	if (!buffer_uptodate(bh)) {
 		lock_buffer(bh);
+
+		/*
+		 * If the buffer has the write error flag, we have failed
+		 * to write out another inode in the same block.  In this
+		 * case, we don't have to read the block because we may
+		 * read the old inode data successfully.
+		 */
+		if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
+			set_buffer_uptodate(bh);
+
 		if (buffer_uptodate(bh)) {
 			/* someone brought it uptodate while we waited */
 			unlock_buffer(bh);