btrfs: create free space tree on ro->rw remount (5011139a) · Commits · 戴 / test

When a user attempts to remount a btrfs filesystem with 'mount -o remount,space_cache=v2', that operation silently succeeds. Unfortunately, this is misleading, because the remount does not create the free space tree. /proc/mounts will incorrectly show space_cache=v2, but on the next mount, the file system will revert to the old space_cache. For now, we handle only the easier case, where the existing mount is read-only and the new mount is read-write. In that case, we can create the free space tree without contending with the block groups changing as we go. Reviewed-by:

Josef Bacik <josef@toxicpanda.com> Signed-off-by:

Boris Burkov <boris@bur.io> Reviewed-by:

David Sterba <dsterba@suse.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

+11 −12

Original line number	Diff line number	Diff line
		@@ -2898,6 +2898,17 @@ int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info)
		goto out;
		}

		if (btrfs_test_opt(fs_info, FREE_SPACE_TREE) &&
		!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
		btrfs_info(fs_info, "creating free space tree");
		ret = btrfs_create_free_space_tree(fs_info);
		if (ret) {
		btrfs_warn(fs_info,
		"failed to create free space tree: %d", ret);
		goto out;
		}
		}

		ret = btrfs_resume_balance_async(fs_info);
		if (ret)
		goto out;
		@@ -3370,18 +3381,6 @@ int __cold open_ctree(struct super_block sb, struct btrfs_fs_devices fs_device
		}
		}

		if (btrfs_test_opt(fs_info, FREE_SPACE_TREE) &&
		!btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE)) {
		btrfs_info(fs_info, "creating free space tree");
		ret = btrfs_create_free_space_tree(fs_info);
		if (ret) {
		btrfs_warn(fs_info,
		"failed to create free space tree: %d", ret);
		close_ctree(fs_info);
		return ret;
		}
		}

		ret = btrfs_start_pre_rw_mount(fs_info);
		if (ret) {
		close_ctree(fs_info);

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