bcache: add more accurate error messages in read_super()

Previous code only returns "Not a bcache superblock" for both bcache
super block offset and magic error. This patch addss more accurate error
messages,
- for super block unmatched offset:
  "Not a bcache superblock (bad offset)"
- for super block unmatched magic number:
  "Not a bcache superblock (bad magic)"

Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 7becced..623fdaf 100644 (file)
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -92,10 +92,11 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
        pr_debug("read sb version %llu, flags %llu, seq %llu, journal size %u",
                 sb->version, sb->flags, sb->seq, sb->keys);
 
-       err = "Not a bcache superblock";
+       err = "Not a bcache superblock (bad offset)";
        if (sb->offset != SB_SECTOR)
                goto err;
 
+       err = "Not a bcache superblock (bad magic)";
        if (memcmp(sb->magic, bcache_magic, 16))
                goto err;