Btrfs: fix the amount of space reserved for unlink

Our unlink reservations were a bit much, we were reserving 10 and I only count 8
possible items we're touching, so comment what we're reserving for and fix the
count value.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 246397d8478f..1f013c5c36aa 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2758,7 +2758,16 @@ static struct btrfs_trans_handle *__unlink_start_trans(struct inode *dir,
         u64 ino = btrfs_ino(inode);
         u64 dir_ino = btrfs_ino(dir);
 
-        trans = btrfs_start_transaction(root, 10);
+        /*
+         * 1 for the possible orphan item
+         * 1 for the dir item
+         * 1 for the dir index
+         * 1 for the inode ref
+         * 1 for the inode ref in the tree log
+         * 2 for the dir entries in the log
+         * 1 for the inode
+         */
+        trans = btrfs_start_transaction(root, 8);
         if (!IS_ERR(trans) || PTR_ERR(trans) != -ENOSPC)
                 return trans;