Btrfs: optimize the error handle of use_block_rsv()

cc: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 162a66bfbffd39986a4c0506c459a3b76872616a..5e2c0bf84075d2248135e04a7be4447e7f55aba1 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6656,48 +6656,39 @@ use_block_rsv(struct btrfs_trans_handle *trans,
 
        block_rsv = get_block_rsv(trans, root);
 
-       if (block_rsv->size == 0) {
-               ret = reserve_metadata_bytes(root, block_rsv, blocksize,
-                                            BTRFS_RESERVE_NO_FLUSH);
-               /*
-                * If we couldn't reserve metadata bytes try and use some from
-                * the global reserve.
-                */
-               if (ret && block_rsv != global_rsv) {
-                       ret = block_rsv_use_bytes(global_rsv, blocksize);
-                       if (!ret)
-                               return global_rsv;
-                       return ERR_PTR(ret);
-               } else if (ret) {
-                       return ERR_PTR(ret);
-               }
-               return block_rsv;
-       }
+       if (unlikely(block_rsv->size == 0))
+               goto try_reserve;
 
        ret = block_rsv_use_bytes(block_rsv, blocksize);
        if (!ret)
                return block_rsv;
-       if (ret && !block_rsv->failfast) {
-               if (btrfs_test_opt(root, ENOSPC_DEBUG)) {
-                       static DEFINE_RATELIMIT_STATE(_rs,
-                                       DEFAULT_RATELIMIT_INTERVAL * 10,
-                                       /*DEFAULT_RATELIMIT_BURST*/ 1);
-                       if (__ratelimit(&_rs))
-                               WARN(1, KERN_DEBUG
-                                       "btrfs: block rsv returned %d\n", ret);
-               }
-               ret = reserve_metadata_bytes(root, block_rsv, blocksize,
-                                            BTRFS_RESERVE_NO_FLUSH);
-               if (!ret) {
-                       return block_rsv;
-               } else if (ret && block_rsv != global_rsv) {
-                       ret = block_rsv_use_bytes(global_rsv, blocksize);
-                       if (!ret)
-                               return global_rsv;
-               }
-       }
 
-       return ERR_PTR(-ENOSPC);
+       if (block_rsv->failfast)
+               return ERR_PTR(ret);
+
+       if (btrfs_test_opt(root, ENOSPC_DEBUG)) {
+               static DEFINE_RATELIMIT_STATE(_rs,
+                               DEFAULT_RATELIMIT_INTERVAL * 10,
+                               /*DEFAULT_RATELIMIT_BURST*/ 1);
+               if (__ratelimit(&_rs))
+                       WARN(1, KERN_DEBUG
+                               "btrfs: block rsv returned %d\n", ret);
+       }
+try_reserve:
+       ret = reserve_metadata_bytes(root, block_rsv, blocksize,
+                                    BTRFS_RESERVE_NO_FLUSH);
+       if (!ret)
+               return block_rsv;
+       /*
+        * If we couldn't reserve metadata bytes try and use some from
+        * the global reserve.
+        */
+       if (block_rsv->type != BTRFS_BLOCK_RSV_GLOBAL) {
+               ret = block_rsv_use_bytes(global_rsv, blocksize);
+               if (!ret)
+                       return global_rsv;
+       }
+       return ERR_PTR(ret);
 }
 
 static void unuse_block_rsv(struct btrfs_fs_info *fs_info,