Btrfs: Metadata reservation for orphan inodes

reserve metadata space for handling orphan inodes

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cb814a71800d..a713f69f0c7a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3626,6 +3626,34 @@ void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
         trans->bytes_reserved = 0;
 }
 
+int btrfs_orphan_reserve_metadata(struct btrfs_trans_handle *trans,
+                                  struct inode *inode)
+{
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct btrfs_block_rsv *src_rsv = get_block_rsv(trans, root);
+        struct btrfs_block_rsv *dst_rsv = root->orphan_block_rsv;
+
+        /*
+         * one for deleting orphan item, one for updating inode and
+         * two for calling btrfs_truncate_inode_items.
+         *
+         * btrfs_truncate_inode_items is a delete operation, it frees
+         * more space than it uses in most cases. So two units of
+         * metadata space should be enough for calling it many times.
+         * If all of the metadata space is used, we can commit
+         * transaction and use space it freed.
+         */
+        u64 num_bytes = calc_trans_metadata_size(root, 4);
+        return block_rsv_migrate_bytes(src_rsv, dst_rsv, num_bytes);
+}
+
+void btrfs_orphan_release_metadata(struct inode *inode)
+{
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        u64 num_bytes = calc_trans_metadata_size(root, 4);
+        btrfs_block_rsv_release(root, root->orphan_block_rsv, num_bytes);
+}
+
 int btrfs_snap_reserve_metadata(struct btrfs_trans_handle *trans,
                                 struct btrfs_pending_snapshot *pending)
 {