[PATCH AUTOSEL 4.19 12/40] ext4: do not commit super on read-only bdev

From: Sasha Levin
Date: Wed Apr 15 2020 - 08:17:05 EST


From: Eric Sandeen <sandeen@xxxxxxxxxx>

[ Upstream commit c96e2b8564adfb8ac14469ebc51ddc1bfecb3ae2 ]

Under some circumstances we may encounter a filesystem error on a
read-only block device, and if we try to save the error info to the
superblock and commit it, we'll wind up with a noisy error and
backtrace, i.e.:

[ 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
...

To avoid this, commit the error info in the superblock only if the
block device is writable.

Reported-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
Link: https://lore.kernel.org/r/4b6e774d-cc00-3469-7abb-108eb151071a@xxxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 d44fc3f579e13..6e7f055af828c 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -388,7 +388,8 @@ static void save_error_info(struct super_block *sb, const char *func,
unsigned int line)
{
__save_error_info(sb, func, line);
- ext4_commit_super(sb, 1);
+ if (!bdev_read_only(sb->s_bdev))
+ ext4_commit_super(sb, 1);
}

/*
--
2.20.1