Btrfs: fix wrong fsid check of scrub

All the metadata in the seed devices has the same fsid as the fsid
of the seed filesystem which is on the seed device, so we should check
them by the current filesystem. Fix it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

fs/btrfs/scrub.c

@@ -1359,6 +1359,16 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
 	return;
 }
 
+static inline int scrub_check_fsid(u8 fsid[],
+				   struct scrub_page *spage)
+{
+	struct btrfs_fs_devices *fs_devices = spage->dev->fs_devices;
+	int ret;
+
+	ret = memcmp(fsid, fs_devices->fsid, BTRFS_UUID_SIZE);
+	return !ret;
+}
+
 static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
 					 struct scrub_block *sblock,
 					 int is_metadata, int have_csum,
@@ -1378,7 +1388,7 @@ static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
 		h = (struct btrfs_header *)mapped_buffer;
 
 		if (sblock->pagev[0]->logical != btrfs_stack_header_bytenr(h) ||
-		    memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE) ||
+		    !scrub_check_fsid(h->fsid, sblock->pagev[0]) ||
 		    memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
 			   BTRFS_UUID_SIZE)) {
 			sblock->header_error = 1;
@@ -1749,7 +1759,7 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
 	if (sblock->pagev[0]->generation != btrfs_stack_header_generation(h))
 		++fail;
 
-	if (memcmp(h->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
+	if (!scrub_check_fsid(h->fsid, sblock->pagev[0]))
 		++fail;
 
 	if (memcmp(h->chunk_tree_uuid, fs_info->chunk_tree_uuid,
@@ -1788,8 +1798,6 @@ static int scrub_checksum_super(struct scrub_block *sblock)
 {
 	struct btrfs_super_block *s;
 	struct scrub_ctx *sctx = sblock->sctx;
-	struct btrfs_root *root = sctx->dev_root;
-	struct btrfs_fs_info *fs_info = root->fs_info;
 	u8 calculated_csum[BTRFS_CSUM_SIZE];
 	u8 on_disk_csum[BTRFS_CSUM_SIZE];
 	struct page *page;
@@ -1814,7 +1822,7 @@ static int scrub_checksum_super(struct scrub_block *sblock)
 	if (sblock->pagev[0]->generation != btrfs_super_generation(s))
 		++fail_gen;
 
-	if (memcmp(s->fsid, fs_info->fsid, BTRFS_UUID_SIZE))
+	if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
 		++fail_cor;
 
 	len = BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE;