[PATCH] fs: ext4: skip journal state if fs has metadata_csum

[Arnaud Ferraris]

As u-boot doesn't support the metadata_csum feature, writing to a
filesystem with this feature enabled will fail, as expected. However,
during the process, a journal state check is performed, which could
result in:
  - a fs recovery if the fs wasn't umounted properly
  - the fs being marked dirty

Both these cases result in a superblock change, leading to a mismatch
between the superblock checksum and its contents. Therefore, Linux will
consider the filesystem heavily corrupted and will require e2fsck to be
run manually to boot.

By bypassing the journal state check, this patch ensures the superblock
won't be corrupted if the filesystem has metadata_csum feature enabled.

Signed-off-by: Arnaud Ferraris <arnaud.ferraris at collabora.com>
---

 fs/ext4/ext4_journal.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/ext4_journal.c b/fs/ext4/ext4_journal.c
index 3559daf11d..f8524e5a99 100644
--- a/fs/ext4/ext4_journal.c
+++ b/fs/ext4/ext4_journal.c
@@ -409,6 +409,9 @@ int ext4fs_check_journal_state(int recovery_flag)
 	char *temp_buff1 = NULL;
 	struct ext_filesystem *fs = get_fs();
 
+	if (le32_to_cpu(fs->sb->feature_ro_compat) & EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)
+		return 0;
+
 	temp_buff = zalloc(fs->blksz);
 	if (!temp_buff)
 		return -ENOMEM;
-- 
2.26.1