[PATCH AUTOSEL 5.5 116/121] ext4: check for non-zero journal inum in ext4_calculate_overhead

Sasha Levin
2020-04-11T23:33:58Z

From: Ritesh Harjani <riteshh@linux.ibm.com>

[ Upstream commit f1eec3b0d0a849996ebee733b053efa71803dad5 ]

While calculating overhead for internal journal, also check
that j_inum shouldn't be 0. Otherwise we get below error with
xfstests generic/050 with external journal (XXX_LOGDEV config) enabled.

It could be simply reproduced with loop device with an external journal
and marking blockdev as RO before mounting.

[ 3337.146838] EXT4-fs error (device pmem1p2): ext4_get_journal_inode:4634: comm mount: inode #0: comm mount: iget: illegal inode #
------------[ cut here ]------------
generic_make_request: Trying to write to read-only block-device pmem1p2 (partno 2)
WARNING: CPU: 107 PID: 115347 at block/blk-core.c:788 generic_make_request_checks+0x6b4/0x7d0
CPU: 107 PID: 115347 Comm: mount Tainted: G L --------- -t - 4.18.0-167.el8.ppc64le #1
NIP: c0000000006f6d44 LR: c0000000006f6d40 CTR: 0000000030041dd4
<...>
NIP [c0000000006f6d44] generic_make_request_checks+0x6b4/0x7d0
LR [c0000000006f6d40] generic_make_request_checks+0x6b0/0x7d0
<...>
Call Trace:
generic_make_request_checks+0x6b0/0x7d0 (unreliable)
generic_make_request+0x3c/0x420
submit_bio+0xd8/0x200
submit_bh_wbc+0x1e8/0x250
__sync_dirty_buffer+0xd0/0x210
ext4_commit_super+0x310/0x420 [ext4]
__ext4_error+0xa4/0x1e0 [ext4]
__ext4_iget+0x388/0xe10 [ext4]
ext4_get_journal_inode+0x40/0x150 [ext4]
ext4_calculate_overhead+0x5a8/0x610 [ext4]
ext4_fill_super+0x3188/0x3260 [ext4]
mount_bdev+0x778/0x8f0
ext4_mount+0x28/0x50 [ext4]
mount_fs+0x74/0x230
vfs_kern_mount.part.6+0x6c/0x250
do_mount+0x2fc/0x1280
sys_mount+0x158/0x180
system_call+0x5c/0x70
EXT4-fs (pmem1p2): no journal found
EXT4-fs (pmem1p2): can't get journal size
EXT4-fs (pmem1p2): mounted filesystem without journal. Opts: dax,norecovery

Fixes: 3c816ded78bb ("ext4: use journal inode to determine journal overhead")
Reported-by: Harish Sriram <harish@linux.ibm.com>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200316093038.25485-1-riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/super.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 71e2b80ff4aae..1fa00a5ec6178 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3564,7 +3564,8 @@ int ext4_calculate_overhead(struct super_block *sb)
*/
if (sbi->s_journal && !sbi->journal_bdev)
overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen);
- else if (ext4_has_feature_journal(sb) && !sbi->s_journal) {
+ else if (ext4_has_feature_journal(sb) && !sbi->s_journal && j_inum) {
+ /* j_inum for internal journal is non-zero */
j_inode = ext4_get_journal_inode(sb, j_inum);
if (j_inode) {
j_blocks = j_inode->i_size >> sb->s_blocksize_bits;
--
2.20.1