bcache: add read_super_common() to read major part of super block

Later patches will introduce feature set bits to on-disk super block and
increase super block version. Current code in read_super() which reads
common part of super block for version BCACHE_SB_VERSION_CDEV and version
BCACHE_SB_VERSION_CDEV_WITH_UUID will be shared with the new version.

Therefore this patch moves the reusable part into read_super_common(),
this preparation patch will make later patches more simplier and only
focus on new feature set bits.

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 0f90616..a234c4c 100644 (file)
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -59,6 +59,67 @@ struct workqueue_struct *bch_journal_wq;
 
 /* Superblock */
 
+static const char *read_super_common(struct cache_sb *sb,  struct block_device *bdev,
+                                    struct cache_sb_disk *s)
+{
+       const char *err;
+       unsigned int i;
+
+       sb->nbuckets    = le64_to_cpu(s->nbuckets);
+       sb->bucket_size = le16_to_cpu(s->bucket_size);
+
+       sb->nr_in_set   = le16_to_cpu(s->nr_in_set);
+       sb->nr_this_dev = le16_to_cpu(s->nr_this_dev);
+
+       err = "Too many buckets";
+       if (sb->nbuckets > LONG_MAX)
+               goto err;
+
+       err = "Not enough buckets";
+       if (sb->nbuckets < 1 << 7)
+               goto err;
+
+       err = "Bad block/bucket size";
+       if (!is_power_of_2(sb->block_size) ||
+           sb->block_size > PAGE_SECTORS ||
+           !is_power_of_2(sb->bucket_size) ||
+           sb->bucket_size < PAGE_SECTORS)
+               goto err;
+
+       err = "Invalid superblock: device too small";
+       if (get_capacity(bdev->bd_disk) <
+           sb->bucket_size * sb->nbuckets)
+               goto err;
+
+       err = "Bad UUID";
+       if (bch_is_zero(sb->set_uuid, 16))
+               goto err;
+
+       err = "Bad cache device number in set";
+       if (!sb->nr_in_set ||
+           sb->nr_in_set <= sb->nr_this_dev ||
+           sb->nr_in_set > MAX_CACHES_PER_SET)
+               goto err;
+
+       err = "Journal buckets not sequential";
+       for (i = 0; i < sb->keys; i++)
+               if (sb->d[i] != sb->first_bucket + i)
+                       goto err;
+
+       err = "Too many journal buckets";
+       if (sb->first_bucket + sb->keys > sb->nbuckets)
+               goto err;
+
+       err = "Invalid superblock: first bucket comes before end of super";
+       if (sb->first_bucket * sb->bucket_size < 16)
+               goto err;
+
+       err = NULL;
+err:
+       return err;
+}
+
+
 static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
                              struct cache_sb_disk **res)
 {
@@ -133,55 +194,9 @@ static const char *read_super(struct cache_sb *sb, struct block_device *bdev,
                break;
        case BCACHE_SB_VERSION_CDEV:
        case BCACHE_SB_VERSION_CDEV_WITH_UUID:
-               sb->nbuckets    = le64_to_cpu(s->nbuckets);
-               sb->bucket_size = le16_to_cpu(s->bucket_size);
-
-               sb->nr_in_set   = le16_to_cpu(s->nr_in_set);
-               sb->nr_this_dev = le16_to_cpu(s->nr_this_dev);
-
-               err = "Too many buckets";
-               if (sb->nbuckets > LONG_MAX)
-                       goto err;
-
-               err = "Not enough buckets";
-               if (sb->nbuckets < 1 << 7)
-                       goto err;
-
-               err = "Bad block/bucket size";
-               if (!is_power_of_2(sb->block_size) ||
-                   sb->block_size > PAGE_SECTORS ||
-                   !is_power_of_2(sb->bucket_size) ||
-                   sb->bucket_size < PAGE_SECTORS)
-                       goto err;
-
-               err = "Invalid superblock: device too small";
-               if (get_capacity(bdev->bd_disk) <
-                   sb->bucket_size * sb->nbuckets)
-                       goto err;
-
-               err = "Bad UUID";
-               if (bch_is_zero(sb->set_uuid, 16))
-                       goto err;
-
-               err = "Bad cache device number in set";
-               if (!sb->nr_in_set ||
-                   sb->nr_in_set <= sb->nr_this_dev ||
-                   sb->nr_in_set > MAX_CACHES_PER_SET)
-                       goto err;
-
-               err = "Journal buckets not sequential";
-               for (i = 0; i < sb->keys; i++)
-                       if (sb->d[i] != sb->first_bucket + i)
-                               goto err;
-
-               err = "Too many journal buckets";
-               if (sb->first_bucket + sb->keys > sb->nbuckets)
-                       goto err;
-
-               err = "Invalid superblock: first bucket comes before end of super";
-               if (sb->first_bucket * sb->bucket_size < 16)
+               err = read_super_common(sb, bdev, s);
+               if (err)
                        goto err;
-
                break;
        default:
                err = "Unsupported superblock version";