Commit 5011139a authored by Boris Burkov's avatar Boris Burkov Committed by David Sterba
Browse files

btrfs: create free space tree on ro->rw remount 



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: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarBoris Burkov <boris@bur.io>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 997e3e2e

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);