[2/7] Btrfs: add a necessary check before updating qgroup limit

Commit Message

Wang Shilong March 26, 2013, 11:55 a.m. UTC

From: Wang Shilong <[e-mail]>

Add a necessary check before updating qgroup limit,
if the relative qgroup dosen't exsit, do not join transaction.

Signed-off-by: Wang Shilong <[e-mail]>
Reviewed-by: Miao Xie <[e-mail]>
---
 fs/btrfs/ioctl.c |   43 ++++++++++++++++++++++++++++++++++++-------
 1 files changed, 36 insertions(+), 7 deletions(-)

Patch

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0b8ab81..3c4fde0 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3837,6 +3837,33 @@  drop_write:
 	return ret;
 }
 
+static int may_qgroup_limit(struct btrfs_root *root, u64 qgroupid)
+{
+	int ret = 0;
+	struct btrfs_key key;
+	struct btrfs_path *path;
+
+	if (!root->fs_info->quota_root)
+		return -EINVAL;
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		return ret;
+	}
+
+	key.objectid = 0;
+	key.type = BTRFS_QGROUP_INFO_KEY;
+	key.offset = qgroupid;
+
+	ret = btrfs_search_slot(NULL, root->fs_info->quota_root,
+				&key, path, 0, 0);
+	if (ret > 0)
+		ret = -ENOENT;
+	btrfs_free_path(path);
+	return ret;
+}
+
 static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
 {
 	struct btrfs_root *root = BTRFS_I(file_inode(file))->root;
@@ -3859,19 +3886,21 @@  static long btrfs_ioctl_qgroup_limit(struct file *file, void __user *arg)
 		goto drop_write;
 	}
 	mutex_lock(&root->fs_info->quota_lock);
-	trans = btrfs_join_transaction(root);
-	if (IS_ERR(trans)) {
-		ret = PTR_ERR(trans);
-		goto out;
-	}
-
 	qgroupid = sa->qgroupid;
 	if (!qgroupid) {
 		/* take the current subvol as qgroup */
 		qgroupid = root->root_key.objectid;
 	}
+	ret = may_qgroup_limit(root, qgroupid);
+	if (ret)
+		goto out;
+
+	trans = btrfs_join_transaction(root);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		goto out;
+	}
 
-	/* FIXME: check if the IDs really exist */
 	ret = btrfs_limit_qgroup(trans, root->fs_info, qgroupid, &sa->lim);
 
 	err = btrfs_end_transaction(trans, root);