Btrfs: cleanup the similar code of the fs root read

There are several functions whose code is similar, such as
  btrfs_find_last_root()
  btrfs_read_fs_root_no_radix()

Besides that, some functions are invoked twice, it is unnecessary,
for example, we are sure that all roots which is found in
  btrfs_find_orphan_roots()
have their orphan items, so it is unnecessary to check the orphan
item again.

So cleanup it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 53 insertions, 117 deletions

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 5bf1ed57f178..79e683273de5 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -64,52 +64,59 @@ void btrfs_read_root_item(struct extent_buffer *eb, int slot,
 }
 
 /*
- * lookup the root with the highest offset for a given objectid.  The key we do
- * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
- * on error.
+ * btrfs_find_root - lookup the root by the key.
+ * root: the root of the root tree
+ * search_key: the key to search
+ * path: the path we search
+ * root_item: the root item of the tree we look for
+ * root_key: the reak key of the tree we look for
+ *
+ * If ->offset of 'seach_key' is -1ULL, it means we are not sure the offset
+ * of the search key, just lookup the root with the highest offset for a
+ * given objectid.
+ *
+ * If we find something return 0, otherwise > 0, < 0 on error.
  */
-int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
-                        struct btrfs_root_item *item, struct btrfs_key *key)
+int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key,
+                    struct btrfs_path *path, struct btrfs_root_item *root_item,
+                    struct btrfs_key *root_key)
 {
-        struct btrfs_path *path;
-        struct btrfs_key search_key;
         struct btrfs_key found_key;
         struct extent_buffer *l;
         int ret;
         int slot;
 
-        search_key.objectid = objectid;
-        search_key.type = BTRFS_ROOT_ITEM_KEY;
-        search_key.offset = (u64)-1;
-
-        path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
-        ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
+        ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
         if (ret < 0)
-                goto out;
+                return ret;
 
-        BUG_ON(ret == 0);
-        if (path->slots[0] == 0) {
-                ret = 1;
-                goto out;
+        if (search_key->offset != -1ULL) {      /* the search key is exact */
+                if (ret > 0)
+                        goto out;
+        } else {
+                BUG_ON(ret == 0);               /* Logical error */
+                if (path->slots[0] == 0)
+                        goto out;
+                path->slots[0]--;
+                ret = 0;
         }
+
         l = path->nodes[0];
-        slot = path->slots[0] - 1;
+        slot = path->slots[0];
+
         btrfs_item_key_to_cpu(l, &found_key, slot);
-        if (found_key.objectid != objectid ||
+        if (found_key.objectid != search_key->objectid ||
             found_key.type != BTRFS_ROOT_ITEM_KEY) {
                 ret = 1;
                 goto out;
         }
-        if (item)
-                btrfs_read_root_item(l, slot, item);
-        if (key)
-                memcpy(key, &found_key, sizeof(found_key));
 
-        ret = 0;
+        if (root_item)
+                btrfs_read_root_item(l, slot, root_item);
+        if (root_key)
+                memcpy(root_key, &found_key, sizeof(found_key));
 out:
-        btrfs_free_path(path);
+        btrfs_release_path(path);
         return ret;
 }
 
@@ -212,86 +219,6 @@ int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 }
 
-/*
- * at mount time we want to find all the old transaction snapshots that were in
- * the process of being deleted if we crashed.  This is any root item with an
- * offset lower than the latest root.  They need to be queued for deletion to
- * finish what was happening when we crashed.
- */
-int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
-{
-        struct btrfs_root *dead_root;
-        struct btrfs_root_item *ri;
-        struct btrfs_key key;
-        struct btrfs_key found_key;
-        struct btrfs_path *path;
-        int ret;
-        u32 nritems;
-        struct extent_buffer *leaf;
-        int slot;
-
-        key.objectid = objectid;
-        btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
-        key.offset = 0;
-        path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
-
-again:
-        ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-        if (ret < 0)
-                goto err;
-        while (1) {
-                leaf = path->nodes[0];
-                nritems = btrfs_header_nritems(leaf);
-                slot = path->slots[0];
-                if (slot >= nritems) {
-                        ret = btrfs_next_leaf(root, path);
-                        if (ret)
-                                break;
-                        leaf = path->nodes[0];
-                        nritems = btrfs_header_nritems(leaf);
-                        slot = path->slots[0];
-                }
-                btrfs_item_key_to_cpu(leaf, &key, slot);
-                if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
-                        goto next;
-
-                if (key.objectid < objectid)
-                        goto next;
-
-                if (key.objectid > objectid)
-                        break;
-
-                ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
-                if (btrfs_disk_root_refs(leaf, ri) != 0)
-                        goto next;
-
-                memcpy(&found_key, &key, sizeof(key));
-                key.offset++;
-                btrfs_release_path(path);
-                dead_root =
-                        btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
-                                                    &found_key);
-                if (IS_ERR(dead_root)) {
-                        ret = PTR_ERR(dead_root);
-                        goto err;
-                }
-
-                ret = btrfs_add_dead_root(dead_root);
-                if (ret)
-                        goto err;
-                goto again;
-next:
-                slot++;
-                path->slots[0]++;
-        }
-        ret = 0;
-err:
-        btrfs_free_path(path);
-        return ret;
-}
-
 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 {
         struct extent_buffer *leaf;
@@ -340,20 +267,29 @@ int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
                 root_key.objectid = key.offset;
                 key.offset++;
 
-                root = btrfs_read_fs_root_no_name(tree_root->fs_info,
-                                                  &root_key);
-                if (!IS_ERR(root))
+                root = btrfs_read_fs_root(tree_root, &root_key);
+                if (IS_ERR(root)) {
+                        err = PTR_ERR(root);
+                        break;
+                }
+
+                if (btrfs_root_refs(&root->root_item) == 0) {
+                        btrfs_add_dead_root(root);
                         continue;
+                }
 
-                ret = PTR_ERR(root);
-                if (ret != -ENOENT) {
-                        err = ret;
+                err = btrfs_init_fs_root(root);
+                if (err) {
+                        btrfs_free_fs_root(root);
                         break;
                 }
 
-                ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
-                if (ret) {
-                        err = ret;
+                root->orphan_item_inserted = 1;
+
+                err = btrfs_insert_fs_root(root->fs_info, root);
+                if (err) {
+                        BUG_ON(err == -EEXIST);
+                        btrfs_free_fs_root(root);
                         break;
                 }
         }