[PATCH 3.2 010/152] ext4: don't call ext4_should_journal_data() on the journal inode

From: Ben Hutchings
Date: Sun Nov 13 2016 - 22:03:17 EST


3.2.84-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Vegard Nossum <vegard.nossum@xxxxxxxxxx>

commit 6a7fd522a7c94cdef0a3b08acf8e6702056e635c upstream.

If ext4_fill_super() fails early, it's possible for ext4_evict_inode()
to call ext4_should_journal_data() before superblock options and flags
are fully set up. In that case, the iput() on the journal inode can
end up causing a BUG().

Work around this problem by reordering the tests so we only call
ext4_should_journal_data() after we know it's not the journal inode.

Fixes: 2d859db3e4 ("ext4: fix data corruption in inodes with journalled data")
Fixes: 2b405bfa84 ("ext4: fix data=journal fast mount/umount hang")
Cc: Jan Kara <jack@xxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/ext4/inode.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -142,9 +142,9 @@ void ext4_evict_inode(struct inode *inod
* Note that directories do not have this problem because they
* don't use page cache.
*/
- if (ext4_should_journal_data(inode) &&
- (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode)) &&
- inode->i_ino != EXT4_JOURNAL_INO) {
+ if (inode->i_ino != EXT4_JOURNAL_INO &&
+ ext4_should_journal_data(inode) &&
+ (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode))) {
journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;