Re: [PATCH 2/2] jbd2: fix descriptor block size handling errors with journal_csum

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Fri, Sep 05, 2014 at 09:01:54PM -0700, Darrick J. Wong wrote:
> On Tue, Sep 02, 2014 at 03:28:33PM -0400, TR Reardon wrote:
> > There may still be problems with this patch.  After applying to 3.16.1, I am now getting "can't enable checksumming v2 and v3 at the same time" errors on mount.  Initial mount/dismount work fine, but once fs is touched--forcing superblock update--it cannot be mounted anew.
> > 
> > Note results from dumpe2fs  (without recent patches)
> > 
> > Journal backup:           inode blocks
> > Checksum type:            crc32c
> > Checksum:                 0x39141b69
> > Journal features:         journal_incompat_revoke journal_64bit journal_async_commit journal_checksum_v2 FEATURE_I4
> > Journal size:             128M
> > Journal length:           32768
> > Journal sequence:         0x00012aa4
> > Journal start:            0
> > Journal checksum type:    crc32c
> > Journal checksum:         0x3952b695
> > 
> > Seems that the old v2 flag is not cleared on dismount?
> 
> Yep.  Thanks for catching this.

Also, would you mind testing this patch?  I think it'll suffice to clear all
the journal flags before enabling whichever one we want.

--D

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 0b28b36..aff945d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3190,6 +3190,10 @@ static int set_journal_csum_feature_set(struct super_block *sb)
 		incompat = 0;
 	}
 
+	jbd2_journal_clear_features(sbi->s_journal,
+			JBD2_FEATURE_COMPAT_CHECKSUM, 0,
+			JBD2_FEATURE_INCOMPAT_CSUM_V3 |
+			JBD2_FEATURE_INCOMPAT_CSUM_V2);
 	if (test_opt(sb, JOURNAL_ASYNC_COMMIT)) {
 		ret = jbd2_journal_set_features(sbi->s_journal,
 				compat, 0,
@@ -3202,11 +3206,8 @@ static int set_journal_csum_feature_set(struct super_block *sb)
 		jbd2_journal_clear_features(sbi->s_journal, 0, 0,
 				JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
 	} else {
-		jbd2_journal_clear_features(sbi->s_journal,
-				JBD2_FEATURE_COMPAT_CHECKSUM, 0,
-				JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT |
-				JBD2_FEATURE_INCOMPAT_CSUM_V3 |
-				JBD2_FEATURE_INCOMPAT_CSUM_V2);
+		jbd2_journal_clear_features(sbi->s_journal, 0, 0,
+				JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
 	}
 
 	return ret;