ext4: don't manipulate recovery flag when freezing no-journal fs

At some point along this sequence of changes:

f6e63f90 ext4: fold ext4_nojournal_sops into ext4_sops
bb044576 ext4: support freezing ext2 (nojournal) file systems
9ca92389 ext4: Use separate super_operations structure for no_journal filesystems

ext4 started setting needs_recovery on filesystems without journals
when they are unfrozen.  This makes no sense, and in fact confuses
blkid to the point where it doesn't recognize the filesystem at all.

(freeze ext2; unfreeze ext2; run blkid; see no output; run dumpe2fs,
see needs_recovery set on fs w/ no journal).

To fix this, don't manipulate the INCOMPAT_RECOVER feature on
filesystems without journals.
Reported-by: NStu Mark <smark@datto.com>
Reviewed-by: NJan Kara <jack@suse.com>
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org

fs/ext4/super.c

@@ -4836,10 +4836,11 @@ static int ext4_freeze(struct super_block *sb)
 		error = jbd2_journal_flush(journal);
 		if (error < 0)
 			goto out;
+
+		/* Journal blocked and flushed, clear needs_recovery flag. */
+		EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
 	}
 
-	/* Journal blocked and flushed, clear needs_recovery flag. */
-	EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
 	error = ext4_commit_super(sb, 1);
 out:
 	if (journal)
@@ -4857,8 +4858,11 @@ static int ext4_unfreeze(struct super_block *sb)
 	if (sb->s_flags & MS_RDONLY)
 		return 0;
 
-	/* Reset the needs_recovery flag before the fs is unlocked. */
-	EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+	if (EXT4_SB(sb)->s_journal) {
+		/* Reset the needs_recovery flag before the fs is unlocked. */
+		EXT4_SET_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
+	}
+
 	ext4_commit_super(sb, 1);
 	return 0;
 }