From e09fe2d2119800e6060f9b8ba71e072a0eb0fa4d Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Fri, 27 Feb 2015 16:24:23 +0800 Subject: [PATCH] btrfs: Don't allow subvolid >= (1 << BTRFS_QGROUP_LEVEL_SHIFT) to be created Btrfs will create qgroup on subvolume creation if quota is enabled, but qgroup uses the high bits(currently 16 bits) as level, to build the inheritance. However it is fully possible a subvolume can be created with a subvolumeid larger than 1 << BTRFS_QGROUP_LEVEL_SHIFT, so it will be considered as level 1 and can't be assigned to other qgroup in level 1. This patch will prevent such things so qgroup inheritance will not be screwed up. The downside is very clear, btrfs subvolume number limit will decrease from (u64 max - 256(fisrt free objectid) - 256(last free objectid)) to (u48 max -256(first free objectid)). But we still have near u48(that's 15 digits in dec), so that should not be a huge problem. Signed-off-by: Qu Wenruo Reviewed-by: Josef Bacik Signed-off-by: Chris Mason --- fs/btrfs/ctree.h | 3 ++- fs/btrfs/ioctl.c | 7 +++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8b851ac7c3fa..6f364e1d8d3d 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -4219,7 +4219,8 @@ int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb, static inline int is_fstree(u64 rootid) { if (rootid == BTRFS_FS_TREE_OBJECTID || - (s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID) + ((s64)rootid >= (s64)BTRFS_FIRST_FREE_OBJECTID && + !btrfs_qgroup_level(rootid))) return 1; return 0; } diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 2e66d8e76f32..e38b645c5015 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -456,6 +456,13 @@ static noinline int create_subvol(struct inode *dir, if (ret) return ret; + /* + * Don't create subvolume whose level is not zero. Or qgroup will be + * screwed up since it assume subvolme qgroup's level to be 0. + */ + if (btrfs_qgroup_level(objectid)) + return -ENOSPC; + btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP); /* * The same as the snapshot creation, please see the comment -- 2.20.1