Btrfs: Add readahead to the online shrinker, and a mount -o alloc_start= for testing

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a421069e998b..d6243c2afc73 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1630,11 +1630,11 @@ int btrfs_alloc_extent(struct btrfs_trans_handle *trans,
         struct btrfs_path *path;
 
         btrfs_set_stack_extent_refs(&extent_item, 1);
-#if 0
-        new_hint = max(hint_byte, 16ULL * 1024 * 1024 * 1024);
+
+        new_hint = max(hint_byte, root->fs_info->alloc_start);
         if (new_hint < btrfs_super_total_bytes(&info->super_copy))
                 hint_byte = new_hint;
-#endif
+
         WARN_ON(num_bytes < root->sectorsize);
         ret = find_free_extent(trans, root, num_bytes, empty_size,
                                search_start, search_end, hint_byte, ins,
@@ -2239,7 +2239,7 @@ static int relocate_one_reference(struct btrfs_root *extent_root,
                 free_extent_buffer(eb);
 
                 path->lowest_level = level;
-                path->reada = 0;
+                path->reada = 2;
                 ret = btrfs_search_slot(trans, found_root, &found_key, path,
                                         0, 1);
                 path->lowest_level = 0;
@@ -2372,6 +2372,7 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
         block_group_cache = &info->block_group_cache;
         path = btrfs_alloc_path();
         root = root->fs_info->extent_root;
+        path->reada = 2;
 
 again:
         total_found = 0;