From f2f6ed3d54648ec19dcdeec30f66843cf7a38487 Mon Sep 17 00:00:00 2001 From: Wang Shilong Date: Sun, 7 Apr 2013 10:50:16 +0000 Subject: [PATCH] Btrfs: introduce a mutex lock for btrfs quota operations The original code has one spin_lock 'qgroup_lock' to protect quota configurations in memory. If we want to add a BTRFS_QGROUP_INFO_KEY, it will be added to Btree firstly, and then update configurations in memory,however, a race condition may happen between these operations. For example: ->add_qgroup_info_item() ->add_qgroup_rb() For the above case, del_qgroup_info_item() may happen just before add_qgroup_rb(). What's worse, when we want to add a qgroup relation: ->add_qgroup_relation_item() ->add_qgroup_relations() We don't have any checks whether 'src' and 'dst' exist before add_qgroup_relation_item(), a race condition can also happen for the above case. To avoid race condition and have all the necessary checks, we introduce a mutex lock 'qgroup_ioctl_lock', and we make all the user change operations protected by the mutex lock. Signed-off-by: Wang Shilong Reviewed-by: Miao Xie Signed-off-by: Josef Bacik --- fs/btrfs/ctree.h | 3 ++ fs/btrfs/disk-io.c | 1 + fs/btrfs/qgroup.c | 82 +++++++++++++++++++++++++++++++++++++----------------- 3 files changed, 61 insertions(+), 25 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 075a8a0..1a85040 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -1583,6 +1583,9 @@ struct btrfs_fs_info { struct rb_root qgroup_tree; spinlock_t qgroup_lock; + /* protect user change for quota operations */ + struct mutex qgroup_ioctl_lock; + /* list of dirty qgroups to be written at next commit */ struct list_head dirty_qgroups; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 70e6b0c..9f83e5b 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2213,6 +2213,7 @@ int open_ctree(struct super_block *sb, mutex_init(&fs_info->dev_replace.lock); spin_lock_init(&fs_info->qgroup_lock); + mutex_init(&fs_info->qgroup_ioctl_lock); fs_info->qgroup_tree = RB_ROOT; INIT_LIST_HEAD(&fs_info->dirty_qgroups); fs_info->qgroup_seq = 1; diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 5be5a39..0a1f686 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -791,6 +791,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans, int ret = 0; int slot; + mutex_lock(&fs_info->qgroup_ioctl_lock); spin_lock(&fs_info->qgroup_lock); if (fs_info->quota_root) { fs_info->pending_quota_state = 1; @@ -900,6 +901,7 @@ out_free_root: kfree(quota_root); } out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -910,10 +912,11 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, struct btrfs_root *quota_root; int ret = 0; + mutex_lock(&fs_info->qgroup_ioctl_lock); spin_lock(&fs_info->qgroup_lock); if (!fs_info->quota_root) { spin_unlock(&fs_info->qgroup_lock); - return 0; + goto out; } fs_info->quota_enabled = 0; fs_info->pending_quota_state = 0; @@ -922,8 +925,10 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, btrfs_free_qgroup_config(fs_info); spin_unlock(&fs_info->qgroup_lock); - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } ret = btrfs_clean_quota_tree(trans, quota_root); if (ret) @@ -944,6 +949,7 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans, free_extent_buffer(quota_root->commit_root); kfree(quota_root); out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -959,24 +965,28 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, struct btrfs_root *quota_root; int ret = 0; + mutex_lock(&fs_info->qgroup_ioctl_lock); quota_root = fs_info->quota_root; - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } ret = add_qgroup_relation_item(trans, quota_root, src, dst); if (ret) - return ret; + goto out; ret = add_qgroup_relation_item(trans, quota_root, dst, src); if (ret) { del_qgroup_relation_item(trans, quota_root, src, dst); - return ret; + goto out; } spin_lock(&fs_info->qgroup_lock); ret = add_relation_rb(quota_root->fs_info, src, dst); spin_unlock(&fs_info->qgroup_lock); - +out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -987,9 +997,12 @@ int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, int ret = 0; int err; + mutex_lock(&fs_info->qgroup_ioctl_lock); quota_root = fs_info->quota_root; - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } ret = del_qgroup_relation_item(trans, quota_root, src, dst); err = del_qgroup_relation_item(trans, quota_root, dst, src); @@ -1000,7 +1013,8 @@ int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, del_relation_rb(fs_info, src, dst); spin_unlock(&fs_info->qgroup_lock); - +out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -1011,9 +1025,12 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, struct btrfs_qgroup *qgroup; int ret = 0; + mutex_lock(&fs_info->qgroup_ioctl_lock); quota_root = fs_info->quota_root; - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } ret = add_qgroup_item(trans, quota_root, qgroupid); @@ -1023,7 +1040,8 @@ int btrfs_create_qgroup(struct btrfs_trans_handle *trans, if (IS_ERR(qgroup)) ret = PTR_ERR(qgroup); - +out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -1034,9 +1052,12 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, struct btrfs_qgroup *qgroup; int ret = 0; + mutex_lock(&fs_info->qgroup_ioctl_lock); quota_root = fs_info->quota_root; - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } /* check if there are no relations to this qgroup */ spin_lock(&fs_info->qgroup_lock); @@ -1044,7 +1065,8 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, if (qgroup) { if (!list_empty(&qgroup->groups) || !list_empty(&qgroup->members)) { spin_unlock(&fs_info->qgroup_lock); - return -EBUSY; + ret = -EBUSY; + goto out; } } spin_unlock(&fs_info->qgroup_lock); @@ -1054,7 +1076,8 @@ int btrfs_remove_qgroup(struct btrfs_trans_handle *trans, spin_lock(&fs_info->qgroup_lock); del_qgroup_rb(quota_root->fs_info, qgroupid); spin_unlock(&fs_info->qgroup_lock); - +out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -1062,12 +1085,16 @@ int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, u64 qgroupid, struct btrfs_qgroup_limit *limit) { - struct btrfs_root *quota_root = fs_info->quota_root; + struct btrfs_root *quota_root; struct btrfs_qgroup *qgroup; int ret = 0; - if (!quota_root) - return -EINVAL; + mutex_lock(&fs_info->qgroup_ioctl_lock); + quota_root = fs_info->quota_root; + if (!quota_root) { + ret = -EINVAL; + goto out; + } ret = update_qgroup_limit_item(trans, quota_root, qgroupid, limit->flags, limit->max_rfer, @@ -1094,7 +1121,8 @@ int btrfs_limit_qgroup(struct btrfs_trans_handle *trans, unlock: spin_unlock(&fs_info->qgroup_lock); - +out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } @@ -1392,11 +1420,14 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, struct btrfs_qgroup *dstgroup; u32 level_size = 0; + mutex_lock(&fs_info->qgroup_ioctl_lock); if (!fs_info->quota_enabled) - return 0; + goto out; - if (!quota_root) - return -EINVAL; + if (!quota_root) { + ret = -EINVAL; + goto out; + } /* * create a tracking group for the subvol itself @@ -1523,6 +1554,7 @@ int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, unlock: spin_unlock(&fs_info->qgroup_lock); out: + mutex_unlock(&fs_info->qgroup_ioctl_lock); return ret; } -- 2.7.4