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Jan Kara authored
commit 646caa9c upstream. Commit 06bd3c36 (ext4: fix data exposure after a crash) uncovered a deadlock in ext4_writepages() which was previously much harder to hit. After this commit xfstest generic/130 reproduces the deadlock on small filesystems. The problem happens when ext4_do_update_inode() sets LARGE_FILE feature and marks current inode handle as synchronous. That subsequently results in ext4_journal_stop() called from ext4_writepages() to block waiting for transaction commit while still holding page locks, reference to io_end, and some prepared bio in mpd structure each of which can possibly block transaction commit from completing and thus results in deadlock. Fix the problem by releasing page locks, io_end reference, and submitting prepared bio before calling ext4_journal_stop(). [ Changed to defer the call to ext4_journal_stop() only if the handle is synchronous. --tytso ] Reported-and-tested-by:
Eryu Guan <eguan@redhat.com> Signed-off-by:
Theodore Ts'o <tytso@mit.edu> Signed-off-by:
Jan Kara <jack@suse.cz> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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