Commit e6436921 authored Mar 20, 2013 by Jan Kara

ext3: fix data=journal fast mount/umount hang



In data=journal mode, if we unmount the file system before a
transaction has a chance to complete, when the journal inode is being
evicted, we can end up calling into log_wait_commit() for the
last transaction, after the journalling machinery has been shut down.
That triggers the WARN_ONCE in __log_start_commit().

Arguably we should adjust ext3_should_journal_data() to return FALSE
for the journal inode, but the only place it matters is
ext3_evict_inode(), and so it's to save a bit of CPU time, and to make
the patch much more obviously correct by inspection(tm), we'll fix it
by explicitly not trying to waiting for a journal commit when we are
evicting the journal inode, since it's guaranteed to never succeed in
this case.

This can be easily replicated via:

     mount -t ext3 -o data=journal /dev/vdb /vdb ; umount /vdb

This is a port of ext4 fix from Ted Ts'o.

Signed-off-by: Jan Kara <jack@suse.cz>

parent c288d296

fs/ext3/inode.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -218,7 +218,8 @@ void ext3_evict_inode (struct inode *inode)
		*/
		if (inode->i_nlink && ext3_should_journal_data(inode) &&
		EXT3_SB(inode->i_sb)->s_journal &&
		(S_ISLNK(inode->i_mode) \|\| S_ISREG(inode->i_mode))) {
		(S_ISLNK(inode->i_mode) \|\| S_ISREG(inode->i_mode)) &&
		inode->i_ino != EXT3_JOURNAL_INO) {
		tid_t commit_tid = atomic_read(&ei->i_datasync_tid);
		journal_t *journal = EXT3_SB(inode->i_sb)->s_journal;