ext3: fix data=journal fast mount/umount hang

PATCH In review Benjamin LaHaise 2 participants 2 messages Jul 3, 2013 – Jul 8, 2013

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Benjamin LaHaise

author

2013-07-03 21:34 UTC #0 lore raw

PATCH 1/1 ext3: fix data=journal fast mount/umount hang

This patch appears to have been missed for ext3, while the ext4 version was merged back in March -- see [email protected]. A customer of mine has been running into this bug on their production servers on 3.4-stable. It applies cleanly to the 3.3 through 3.8 trees.

-ben

commit e643692138cfa33528f054b071ba2583509bb217

Author: Jan Kara <[email protected]>
Date:   Wed Mar 20 14:39:05 2013 +0100

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 <[email protected]>

Signed-off-by Benjamin LaHaise <[email protected]>

fs/ext3/inode.c +2 -1

index d512c4b..d706dbf 100644
@@ -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;

Luis Henriques

2013-07-08 12:01 UTC #1 lore raw

Quoted 6 lines · Benjamin LaHaise

This patch appears to have been missed for ext3, while the ext4 version was merged back in March -- see [email protected]. A customer of mine has been running into this bug on their production servers on 3.4-stable. It applies cleanly to the 3.3 through 3.8 trees.
-ben

Thanks Ben, I'm queuing it for the 3.5 kernel.

Cheers,

Signature · 1 line

Luis

Quoted 48 lines

commit e643692138cfa33528f054b071ba2583509bb217
Author: Jan Kara <[email protected]>
Date:   Wed Mar 20 14:39:05 2013 +0100
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 <[email protected]>
Signed-off-by Benjamin LaHaise <[email protected]>
fs/ext3/inode.c +2 -2
index d512c4b..d706dbf 100644
@@ -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;
 
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