Btrfs: Integrate metadata reservation with start_transaction

Besides simplify the code, this change makes sure all metadata
reservation for normal metadata operations are released after
committing transaction.

Changes since V1:

Add code that check if unlink and rmdir will free space.

Add ENOSPC handling for clone ioctl.

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

1 files changed, 8 insertions, 5 deletions

diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 56e728d70e39..14b3841b75d5 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -57,8 +57,11 @@ struct btrfs_trans_handle {
 struct btrfs_pending_snapshot {
         struct dentry *dentry;
         struct btrfs_root *root;
-        char *name;
-        struct btrfs_key root_key;
+        struct btrfs_root *snap;
+        /* block reservation for the operation */
+        struct btrfs_block_rsv block_rsv;
+        /* extra metadata reseration for relocation */
+        int error;
         struct list_head list;
 };
 
@@ -85,11 +88,11 @@ static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
                           struct btrfs_root *root);
 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
-                                                   int num_blocks);
+                                                   int num_items);
 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
-                                                   int num_blocks);
+                                                  int num_blocks);
 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
-                                                   int num_blocks);
+                                                         int num_blocks);
 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
                                      struct btrfs_root *root);
 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,