btrfs: make clear_cache mount option to rebuild FST without disabling it
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>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 59ea049..fbf9006 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3121,23 +3121,34 @@ int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info)
{
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;
}
}
