1 files changed, 23 insertions, 41 deletions

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index f749a5447b2a..dd3c040139a2 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -598,6 +598,29 @@ static int btrfs_delayed_inode_reserve_metadata(
         num_bytes = btrfs_calc_trans_metadata_size(root, 1);
 
         /*
+         * If our block_rsv is the delalloc block reserve then check and see if
+         * we have our extra reservation for updating the inode.  If not fall
+         * through and try to reserve space quickly.
+         *
+         * We used to try and steal from the delalloc block rsv or the global
+         * reserve, but we'd steal a full reservation, which isn't kind.  We are
+         * here through delalloc which means we've likely just cowed down close
+         * to the leaf that contains the inode, so we would steal less just
+         * doing the fallback inode update, so if we do end up having to steal
+         * from the global block rsv we hopefully only steal one or two blocks
+         * worth which is less likely to hurt us.
+         */
+        if (src_rsv && src_rsv->type == BTRFS_BLOCK_RSV_DELALLOC) {
+                spin_lock(&BTRFS_I(inode)->lock);
+                if (test_and_clear_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
+                                       &BTRFS_I(inode)->runtime_flags))
+                        release = true;
+                else
+                        src_rsv = NULL;
+                spin_unlock(&BTRFS_I(inode)->lock);
+        }
+
+        /*
          * btrfs_dirty_inode will update the inode under btrfs_join_transaction
          * which doesn't reserve space for speed.  This is a problem since we
          * still need to reserve space for this update, so try to reserve the
@@ -626,51 +649,10 @@ static int btrfs_delayed_inode_reserve_metadata(
                                                       num_bytes, 1);
                 }
                 return ret;
-        } else if (src_rsv->type == BTRFS_BLOCK_RSV_DELALLOC) {
-                spin_lock(&BTRFS_I(inode)->lock);
-                if (test_and_clear_bit(BTRFS_INODE_DELALLOC_META_RESERVED,
-                                       &BTRFS_I(inode)->runtime_flags)) {
-                        spin_unlock(&BTRFS_I(inode)->lock);
-                        release = true;
-                        goto migrate;
-                }
-                spin_unlock(&BTRFS_I(inode)->lock);
-
-                /* Ok we didn't have space pre-reserved.  This shouldn't happen
-                 * too often but it can happen if we do delalloc to an existing
-                 * inode which gets dirtied because of the time update, and then
-                 * isn't touched again until after the transaction commits and
-                 * then we try to write out the data.  First try to be nice and
-                 * reserve something strictly for us.  If not be a pain and try
-                 * to steal from the delalloc block rsv.
-                 */
-                ret = btrfs_block_rsv_add(root, dst_rsv, num_bytes,
-                                          BTRFS_RESERVE_NO_FLUSH);
-                if (!ret)
-                        goto out;
-
-                ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, 1);
-                if (!ret)
-                        goto out;
-
-                if (btrfs_test_opt(root, ENOSPC_DEBUG)) {
-                        btrfs_debug(root->fs_info,
-                                    "block rsv migrate returned %d", ret);
-                        WARN_ON(1);
-                }
-                /*
-                 * Ok this is a problem, let's just steal from the global rsv
-                 * since this really shouldn't happen that often.
-                 */
-                ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
-                                              dst_rsv, num_bytes, 1);
-                goto out;
         }
 
-migrate:
         ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, 1);
 
-out:
         /*
          * Migrate only takes a reservation, it doesn't touch the size of the
          * block_rsv.  This is to simplify people who don't normally have things