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authorArthur Jones <ajones@riverbed.com>2008-11-07 00:05:17 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2008-11-13 09:55:54 -0800
commita0b8bfb34743b6e6c2bb06ad5a270590d90270f7 (patch)
tree27c637ca1ced6e45dfe07fd79549ce5d170b68cf
parent788a5f3f70e2a9c46020bdd3a195f2a866441c5d (diff)
downloadlwn-a0b8bfb34743b6e6c2bb06ad5a270590d90270f7.tar.gz
lwn-a0b8bfb34743b6e6c2bb06ad5a270590d90270f7.zip
ext3: wait on all pending commits in ext3_sync_fs
commit c87591b719737b4e91eb1a9fa8fd55a4ff1886d6 upstream 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 <sandeen@redhat.com>: #!/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 <ajones@riverbed.com> Cc: Eric Sandeen <sandeen@redhat.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--fs/ext3/super.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index f38a5afc39a1..810bf7c834e8 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2365,13 +2365,12 @@ 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;
}