tree b1c9dfc1936579e4fd2a48f77f702effc39029e2
parent c7d206b3379f7d6462e778b74f475c470ee3dcaf
author Jan Kara <jack@suse.cz> 1215818851 -0400
committer Theodore Ts'o <tytso@mit.edu> 1215818851 -0400

ext4: Invert the locking order of page_lock and transaction start

This changes are needed to support data=ordered mode handling via
inodes.  This enables us to get rid of the journal heads and buffer
heads for data buffers in the ordered mode.  With the changes, during
tranasaction commit we writeout the inode pages using the
writepages()/writepage(). That implies we take page lock during
transaction commit. This can cause a deadlock with the locking order
page_lock -> jbd2_journal_start, since the jbd2_journal_start can wait
for the journal_commit to happen and the journal_commit now needs to
take the page lock. To avoid this dead lock reverse the locking order.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>