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

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

5 files changed, 28 insertions, 9 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 2b3ffa707eae..8fa92a2d9819 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2654,9 +2654,9 @@ int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
  */
 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
 {
+        u64 bytenr;
         int slot;
         int level = 1;
-        u64 bytenr;
         struct extent_buffer *c;
         struct extent_buffer *next = NULL;
 
@@ -2687,11 +2687,14 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
                 level--;
                 c = path->nodes[level];
                 free_extent_buffer(c);
+                slot = btrfs_header_nritems(next);
+                if (slot != 0)
+                        slot--;
                 path->nodes[level] = next;
-                path->slots[level] = 0;
+                path->slots[level] = slot;
                 if (!level)
                         break;
-                next = read_tree_block(root, btrfs_node_blockptr(next, 0),
+                next = read_tree_block(root, btrfs_node_blockptr(next, slot),
                                        btrfs_level_size(root, level - 1));
         }
         return 0;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b83a1bec346f..d6e5c19969b0 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -324,6 +324,7 @@ struct btrfs_fs_info {
         u64 last_trans_committed;
         unsigned long mount_opt;
         u64 max_extent;
+        u64 alloc_start;
         struct btrfs_transaction *running_transaction;
         struct btrfs_super_block super_copy;
         struct extent_buffer *sb_buffer;
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;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3c7bf3bddcad..d6de46961887 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2058,7 +2058,7 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
 
         mutex_lock(&root->fs_info->fs_mutex);
         ret = btrfs_check_free_space(root, PAGE_CACHE_SIZE, 0);
-        mutex_lock(&root->fs_info->fs_mutex);
+        mutex_unlock(&root->fs_info->fs_mutex);
         if (ret)
                 goto out;
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 3bbd7f665694..f1b56eb77b1d 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -63,7 +63,8 @@ static void btrfs_put_super (struct super_block * sb)
 }
 
 enum {
-        Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent, Opt_err,
+        Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
+        Opt_alloc_start, Opt_err,
 };
 
 static match_table_t tokens = {
@@ -71,6 +72,7 @@ static match_table_t tokens = {
         {Opt_nodatasum, "nodatasum"},
         {Opt_nodatacow, "nodatacow"},
         {Opt_max_extent, "max_extent=%s"},
+        {Opt_alloc_start, "alloc_start=%s"},
         {Opt_err, NULL}
 };
 
@@ -162,6 +164,18 @@ static int parse_options (char * options,
                                 }
                         }
                         break;
+                case Opt_alloc_start:
+                        if (info) {
+                                char *num = match_strdup(&args[0]);
+                                if (num) {
+                                        info->alloc_start =
+                                                btrfs_parse_size(num);
+                                        kfree(num);
+                                        printk("btrfs: allocations start at "
+                                               "%Lu\n", info->alloc_start);
+                                }
+                        }
+                        break;
                 default:
                         break;
                 }