btrfs: qgroup: Introduce new functions to reserve/free metadata

Introduce new functions btrfs_qgroup_reserve/free_meta() to reserve/free
metadata reserved space.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 75d8e584c3e5..897a49d71638 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -2594,3 +2594,43 @@ int btrfs_qgroup_release_data(struct inode *inode, u64 start, u64 len)
 {
         return __btrfs_qgroup_release_data(inode, start, len, 0);
 }
+
+int btrfs_qgroup_reserve_meta(struct btrfs_root *root, int num_bytes)
+{
+        int ret;
+
+        if (!root->fs_info->quota_enabled || !is_fstree(root->objectid) ||
+            num_bytes == 0)
+                return 0;
+
+        BUG_ON(num_bytes != round_down(num_bytes, root->nodesize));
+        ret = btrfs_qgroup_reserve(root, num_bytes);
+        if (ret < 0)
+                return ret;
+        atomic_add(num_bytes, &root->qgroup_meta_rsv);
+        return ret;
+}
+
+void btrfs_qgroup_free_meta_all(struct btrfs_root *root)
+{
+        int reserved;
+
+        if (!root->fs_info->quota_enabled || !is_fstree(root->objectid))
+                return;
+
+        reserved = atomic_xchg(&root->qgroup_meta_rsv, 0);
+        if (reserved == 0)
+                return;
+        btrfs_qgroup_free(root, reserved);
+}
+
+void btrfs_qgroup_free_meta(struct btrfs_root *root, int num_bytes)
+{
+        if (!root->fs_info->quota_enabled || !is_fstree(root->objectid))
+                return;
+
+        BUG_ON(num_bytes != round_down(num_bytes, root->nodesize));
+        WARN_ON(atomic_read(&root->qgroup_meta_rsv) < num_bytes);
+        atomic_sub(num_bytes, &root->qgroup_meta_rsv);
+        btrfs_qgroup_free(root, num_bytes);
+}