From: Qu Wenruo wqu@suse.com
commit 1d6a4fc85717677e00fefffd847a50fc5928ce69 upstream.
Previously clear_cache mount option would simply disable free-space-tree feature temporarily then re-enable it to rebuild the whole free space tree.
But this is problematic for block-group-tree feature, as we have an artificial dependency on free-space-tree feature.
If we go the existing method, after clearing the free-space-tree feature, we would flip the filesystem to read-only mode, as we detect a super block write with block-group-tree but no free-space-tree feature.
This patch would change the behavior by properly rebuilding the free space tree without disabling this feature, thus allowing clear_cache mount option to work with block group tree.
Now we can mount a filesystem with block-group-tree feature and clear_mount option:
$ mkfs.btrfs -O block-group-tree /dev/test/scratch1 -f $ sudo mount /dev/test/scratch1 /mnt/btrfs -o clear_cache $ sudo dmesg -t | head -n 5 BTRFS info (device dm-1): force clearing of disk cache BTRFS info (device dm-1): using free space tree BTRFS info (device dm-1): auto enabling async discard BTRFS info (device dm-1): rebuilding free space tree BTRFS info (device dm-1): checking UUID tree
CC: stable@vger.kernel.org # 6.1+ Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/disk-io.c | 25 ++++++++++++++++------ fs/btrfs/free-space-tree.c | 50 ++++++++++++++++++++++++++++++++++++++++++++- fs/btrfs/free-space-tree.h | 3 +- fs/btrfs/super.c | 3 -- 4 files changed, 70 insertions(+), 11 deletions(-)
--- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -3123,23 +3123,34 @@ int btrfs_start_pre_rw_mount(struct btrf { int ret; const bool cache_opt = btrfs_test_opt(fs_info, SPACE_CACHE); - bool clear_free_space_tree = false; + bool rebuild_free_space_tree = false;
if (btrfs_test_opt(fs_info, CLEAR_CACHE) && btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) { - clear_free_space_tree = true; + rebuild_free_space_tree = true; } else if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) && !btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID)) { btrfs_warn(fs_info, "free space tree is invalid"); - clear_free_space_tree = true; + rebuild_free_space_tree = true; }
- if (clear_free_space_tree) { - btrfs_info(fs_info, "clearing free space tree"); - ret = btrfs_clear_free_space_tree(fs_info); + if (rebuild_free_space_tree) { + btrfs_info(fs_info, "rebuilding free space tree"); + ret = btrfs_rebuild_free_space_tree(fs_info); if (ret) { btrfs_warn(fs_info, - "failed to clear free space tree: %d", ret); + "failed to rebuild free space tree: %d", ret); + goto out; + } + } + + if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE) && + !btrfs_test_opt(fs_info, FREE_SPACE_TREE)) { + btrfs_info(fs_info, "disabling free space tree"); + ret = btrfs_delete_free_space_tree(fs_info); + if (ret) { + btrfs_warn(fs_info, + "failed to disable free space tree: %d", ret); goto out; } } --- a/fs/btrfs/free-space-tree.c +++ b/fs/btrfs/free-space-tree.c @@ -1252,7 +1252,7 @@ out: return ret; }
-int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info) +int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info) { struct btrfs_trans_handle *trans; struct btrfs_root *tree_root = fs_info->tree_root; @@ -1295,6 +1295,54 @@ int btrfs_clear_free_space_tree(struct b abort: btrfs_abort_transaction(trans, ret); btrfs_end_transaction(trans); + return ret; +} + +int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info) +{ + struct btrfs_trans_handle *trans; + struct btrfs_key key = { + .objectid = BTRFS_FREE_SPACE_TREE_OBJECTID, + .type = BTRFS_ROOT_ITEM_KEY, + .offset = 0, + }; + struct btrfs_root *free_space_root = btrfs_global_root(fs_info, &key); + struct rb_node *node; + int ret; + + trans = btrfs_start_transaction(free_space_root, 1); + if (IS_ERR(trans)) + return PTR_ERR(trans); + + set_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags); + set_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags); + + ret = clear_free_space_tree(trans, free_space_root); + if (ret) + goto abort; + + node = rb_first_cached(&fs_info->block_group_cache_tree); + while (node) { + struct btrfs_block_group *block_group; + + block_group = rb_entry(node, struct btrfs_block_group, + cache_node); + ret = populate_free_space_tree(trans, block_group); + if (ret) + goto abort; + node = rb_next(node); + } + + btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE); + btrfs_set_fs_compat_ro(fs_info, FREE_SPACE_TREE_VALID); + clear_bit(BTRFS_FS_CREATING_FREE_SPACE_TREE, &fs_info->flags); + + ret = btrfs_commit_transaction(trans); + clear_bit(BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED, &fs_info->flags); + return ret; +abort: + btrfs_abort_transaction(trans, ret); + btrfs_end_transaction(trans); return ret; }
--- a/fs/btrfs/free-space-tree.h +++ b/fs/btrfs/free-space-tree.h @@ -18,7 +18,8 @@ struct btrfs_caching_control;
void set_free_space_tree_thresholds(struct btrfs_block_group *block_group); int btrfs_create_free_space_tree(struct btrfs_fs_info *fs_info); -int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info); +int btrfs_delete_free_space_tree(struct btrfs_fs_info *fs_info); +int btrfs_rebuild_free_space_tree(struct btrfs_fs_info *fs_info); int load_free_space_tree(struct btrfs_caching_control *caching_ctl); int add_block_group_free_space(struct btrfs_trans_handle *trans, struct btrfs_block_group *block_group); --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -828,8 +828,7 @@ out: ret = -EINVAL; } if (btrfs_fs_compat_ro(info, BLOCK_GROUP_TREE) && - (btrfs_test_opt(info, CLEAR_CACHE) || - !btrfs_test_opt(info, FREE_SPACE_TREE))) { + !btrfs_test_opt(info, FREE_SPACE_TREE)) { btrfs_err(info, "cannot disable free space tree with block-group-tree feature"); ret = -EINVAL; }