From c87591b719737b4e91eb1a9fa8fd55a4ff1886d6 Mon Sep 17 00:00:00 2001 From: Arthur Jones Date: Thu, 6 Nov 2008 12:53:35 -0800 Subject: [PATCH] ext3: wait on all pending commits in ext3_sync_fs In ext3_sync_fs, we only wait for a commit to finish if we started it, but there may be one already in progress which will not be synced. In the case of a data=ordered umount with pending long symlinks which are delayed due to a long list of other I/O on the backing block device, this causes the buffer associated with the long symlinks to not be moved to the inode dirty list in the second phase of fsync_super. Then, before they can be dirtied again, kjournald exits, seeing the UMOUNT flag and the dirty pages are never written to the backing block device, causing long symlink corruption and exposing new or previously freed block data to userspace. This can be reproduced with a script created by Eric Sandeen : #!/bin/bash umount /mnt/test2 mount /dev/sdb4 /mnt/test2 rm -f /mnt/test2/* dd if=/dev/zero of=/mnt/test2/bigfile bs=1M count=512 touch /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename ln -s /mnt/test2/thisisveryveryveryveryveryveryveryveryveryveryveryveryveryveryveryverylongfilename /mnt/test2/link umount /mnt/test2 mount /dev/sdb4 /mnt/test2 ls /mnt/test2/ umount /mnt/test2 To ensure all commits are synced, we flush all journal commits now when sync_fs'ing ext3. Signed-off-by: Arthur Jones Cc: Eric Sandeen Cc: Theodore Ts'o Cc: Cc: [2.6.everything] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext3/super.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/fs/ext3/super.c b/fs/ext3/super.c index e5717a4fae6..5dec6d1356c 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -2390,13 +2390,12 @@ static void ext3_write_super (struct super_block * sb) static int ext3_sync_fs(struct super_block *sb, int wait) { - tid_t target; - sb->s_dirt = 0; - if (journal_start_commit(EXT3_SB(sb)->s_journal, &target)) { - if (wait) - log_wait_commit(EXT3_SB(sb)->s_journal, target); - } + if (wait) + ext3_force_commit(sb); + else + journal_start_commit(EXT3_SB(sb)->s_journal, NULL); + return 0; } -- 2.20.1