From: Chris Mason <chris.mason@fusionio.com>
Date: Tue, 7 May 2013 15:00:13 +0000 (-0400)
Subject: Btrfs: allow superblock mismatch from older mkfs
X-Git-Tag: upstream/snapshot3+hdmi~4759^2~88
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=667e7d94a1683661cff5fe9a0fa0d7f8fdd2c007;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

Btrfs: allow superblock mismatch from older mkfs

We've added new checks to make sure the super block crc is correct
during mount.  A fresh filesystem from an older mkfs won't have the
crc set.  This adds a warning when it finds a newly created filesystem
but doesn't fail the mount.

Signed-off-by: Chris Mason <chris.mason@fusionio.com>
---

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index bc423f7..4e9ebe1 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -383,6 +383,11 @@ static int btrfs_check_super_csum(char *raw_disk_sb)
 
 		if (memcmp(raw_disk_sb, result, csum_size))
 			ret = 1;
+
+		if (ret && btrfs_super_generation(disk_sb) < 10) {
+			printk(KERN_WARNING "btrfs: super block crcs don't match, older mkfs detected\n");
+			ret = 0;
+		}
 	}
 
 	if (csum_type >= ARRAY_SIZE(btrfs_csum_sizes)) {