Re: [PATCH v8 02/11] btrfs: read raid-stripe-tree from disk

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2023/9/11 22:22, Johannes Thumshirn wrote:
> If we find a raid-stripe-tree on mount, read it from disk.
>
> Reviewed-by: Josef Bacik <josef@toxicpanda.com>
> Reviewed-by: Anand Jain <anand.jain@oracle.com>
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
> ---
>   fs/btrfs/block-rsv.c       |  6 ++++++
>   fs/btrfs/disk-io.c         | 18 ++++++++++++++++++
>   fs/btrfs/disk-io.h         |  5 +++++
>   fs/btrfs/fs.h              |  1 +
>   include/uapi/linux/btrfs.h |  1 +
>   5 files changed, 31 insertions(+)
>
> diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
> index 77684c5e0c8b..4e55e5f30f7f 100644
> --- a/fs/btrfs/block-rsv.c
> +++ b/fs/btrfs/block-rsv.c
> @@ -354,6 +354,11 @@ 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
> @@ -405,6 +410,7 @@ 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:
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 4c5d71065ea8..1ecebcfc1c17 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/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",
> diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
> index 02b645744a82..8b7f01a01c44 100644
> --- a/fs/btrfs/disk-io.h
> +++ b/fs/btrfs/disk-io.h
> @@ -103,6 +103,11 @@ static inline struct btrfs_root *btrfs_grab_root(struct btrfs_root *root)
>   	return NULL;
>   }
>
> +static inline struct btrfs_root *btrfs_stripe_tree_root(struct btrfs_fs_info *fs_info)
> +{
> +	return fs_info->stripe_root;
> +}
> +

Do we really need this? IIRC we never have a wrapper or fs_info->fs_root.

Thanks,
Qu
>   void btrfs_put_root(struct btrfs_root *root);
>   void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
>   int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
> diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h
> index d84a390336fc..5c7778e8b5ed 100644
> --- a/fs/btrfs/fs.h
> +++ b/fs/btrfs/fs.h
> @@ -367,6 +367,7 @@ 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;
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
> index dbb8b96da50d..b9a1d9af8ae8 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/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;
>