btrfs: read raid stripe tree from disk

If we find the raid-stripe-tree on mount, read it from disk. This is
a backward incompatible feature. The rescue=ignorebadroots mount option
will skip this tree.
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-rsv.c

@@ -356,6 +356,11 @@ void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
 		min_items++;
 	}
 
+	if (btrfs_fs_incompat(fs_info, RAID_STRIPE_TREE)) {
+		num_bytes += btrfs_root_used(&fs_info->stripe_root->root_item);
+		min_items++;
+	}
+
 	/*
 	 * But we also want to reserve enough space so we can do the fallback
 	 * global reserve for an unlink, which is an additional
@@ -407,6 +412,7 @@ void btrfs_init_root_block_rsv(struct btrfs_root *root)
 	case BTRFS_EXTENT_TREE_OBJECTID:
 	case BTRFS_FREE_SPACE_TREE_OBJECTID:
 	case BTRFS_BLOCK_GROUP_TREE_OBJECTID:
+	case BTRFS_RAID_STRIPE_TREE_OBJECTID:
 		root->block_rsv = &fs_info->delayed_refs_rsv;
 		break;
 	case BTRFS_ROOT_TREE_OBJECTID:

fs/btrfs/disk-io.c

@@ -1179,6 +1179,8 @@ static struct btrfs_root *btrfs_get_global_root(struct btrfs_fs_info *fs_info,
 		return btrfs_grab_root(fs_info->block_group_root);
 	case BTRFS_FREE_SPACE_TREE_OBJECTID:
 		return btrfs_grab_root(btrfs_global_root(fs_info, &key));
+	case BTRFS_RAID_STRIPE_TREE_OBJECTID:
+		return btrfs_grab_root(fs_info->stripe_root);
 	default:
 		return NULL;
 	}
@@ -1259,6 +1261,7 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
 	btrfs_put_root(fs_info->fs_root);
 	btrfs_put_root(fs_info->data_reloc_root);
 	btrfs_put_root(fs_info->block_group_root);
+	btrfs_put_root(fs_info->stripe_root);
 	btrfs_check_leaked_roots(fs_info);
 	btrfs_extent_buffer_leak_debug_check(fs_info);
 	kfree(fs_info->super_copy);
@@ -1804,6 +1807,7 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
 	free_root_extent_buffers(info->fs_root);
 	free_root_extent_buffers(info->data_reloc_root);
 	free_root_extent_buffers(info->block_group_root);
+	free_root_extent_buffers(info->stripe_root);
 	if (free_chunk_root)
 		free_root_extent_buffers(info->chunk_root);
 }
@@ -2280,6 +2284,20 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
 		fs_info->uuid_root = root;
 	}
 
+	if (btrfs_fs_incompat(fs_info, RAID_STRIPE_TREE)) {
+		location.objectid = BTRFS_RAID_STRIPE_TREE_OBJECTID;
+		root = btrfs_read_tree_root(tree_root, &location);
+		if (IS_ERR(root)) {
+			if (!btrfs_test_opt(fs_info, IGNOREBADROOTS)) {
+				ret = PTR_ERR(root);
+				goto out;
+			}
+		} else {
+			set_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state);
+			fs_info->stripe_root = root;
+		}
+	}
+
 	return 0;
 out:
 	btrfs_warn(fs_info, "failed to read root (objectid=%llu): %d",

fs/btrfs/fs.h

@@ -373,6 +373,7 @@ struct btrfs_fs_info {
 	struct btrfs_root *uuid_root;
 	struct btrfs_root *data_reloc_root;
 	struct btrfs_root *block_group_root;
+	struct btrfs_root *stripe_root;
 
 	/* The log root tree is a directory of all the other log roots */
 	struct btrfs_root *log_root_tree;

include/uapi/linux/btrfs.h

@@ -333,6 +333,7 @@ struct btrfs_ioctl_fs_info_args {
 #define BTRFS_FEATURE_INCOMPAT_RAID1C34		(1ULL << 11)
 #define BTRFS_FEATURE_INCOMPAT_ZONED		(1ULL << 12)
 #define BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2	(1ULL << 13)
+#define BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE	(1ULL << 14)
 
 struct btrfs_ioctl_feature_flags {
 	__u64 compat_flags;