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>

1 files changed, 28 insertions, 37 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 162a66bfbffd..5e2c0bf84075 100644
--- 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,