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, 7 insertions, 10 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8db7b14bbae..d6e3af8be95 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1097,7 +1097,7 @@ static int btrfs_rm_dev_item(struct btrfs_root *root,
         if (!path)
                 return -ENOMEM;
 
-        trans = btrfs_start_transaction(root, 1);
+        trans = btrfs_start_transaction(root, 0);
         key.objectid = BTRFS_DEV_ITEMS_OBJECTID;
         key.type = BTRFS_DEV_ITEM_KEY;
         key.offset = device->devid;
@@ -1486,7 +1486,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
                 goto error;
         }
 
-        trans = btrfs_start_transaction(root, 1);
+        trans = btrfs_start_transaction(root, 0);
         lock_chunks(root);
 
         device->barriers = 1;
@@ -1751,9 +1751,10 @@ static int btrfs_relocate_chunk(struct btrfs_root *root,
 
         /* step one, relocate all the extents inside this chunk */
         ret = btrfs_relocate_block_group(extent_root, chunk_offset);
-        BUG_ON(ret);
+        if (ret)
+                return ret;
 
-        trans = btrfs_start_transaction(root, 1);
+        trans = btrfs_start_transaction(root, 0);
         BUG_ON(!trans);
 
         lock_chunks(root);
@@ -1925,7 +1926,7 @@ int btrfs_balance(struct btrfs_root *dev_root)
                         break;
                 BUG_ON(ret);
 
-                trans = btrfs_start_transaction(dev_root, 1);
+                trans = btrfs_start_transaction(dev_root, 0);
                 BUG_ON(!trans);
 
                 ret = btrfs_grow_device(trans, device, old_size);
@@ -2094,11 +2095,7 @@ again:
         }
 
         /* Shrinking succeeded, else we would be at "done". */
-        trans = btrfs_start_transaction(root, 1);
-        if (!trans) {
-                ret = -ENOMEM;
-                goto done;
-        }
+        trans = btrfs_start_transaction(root, 0);
         lock_chunks(root);
 
         device->disk_total_bytes = new_size;