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jbd: Fix lock ordering bug in journal_unmap_buffer()

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commit 25389bb207 upstream.

Commit 09e05d48 introduced a wait for transaction commit into
journal_unmap_buffer() in the case we are truncating a buffer undergoing commit
in the page stradding i_size on a filesystem with blocksize < pagesize. Sadly
we forgot to drop buffer lock before waiting for transaction commit and thus
deadlock is possible when kjournald wants to lock the buffer.

Fix the problem by dropping the buffer lock before waiting for transaction
commit. Since we are still holding page lock (and that is OK), buffer cannot
disappear under us.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara 2012-11-23 14:03:04 +01:00 committed by Greg Kroah-Hartman
parent c9fa3f41a9
commit acaf0ed4bd
1 changed files with 2 additions and 0 deletions
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2
fs/jbd/transaction.c
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@ -1963,7 +1963,9 @@ retry:
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&journal->j_state_lock);
unlock_buffer(bh);
log_wait_commit(journal, tid);
lock_buffer(bh);
goto retry;
}
/*