• Arthur Jones's avatar
    ext3: wait on all pending commits in ext3_sync_fs · c87591b7
    Arthur Jones authored
    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: default avatarArthur Jones <ajones@riverbed.com>
    Cc: Eric Sandeen <sandeen@redhat.com>
    Cc: Theodore Ts'o <tytso@mit.edu>
    Cc: <linux-ext4@vger.kernel.org>
    Cc: <stable@kernel.org>		[2.6.everything]
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    c87591b7
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