Btrfs: Update find free objectid function for orphan cleanup code

Orphan items use BTRFS_ORPHAN_OBJECTID (-5UUL) as key objectid. This
affects the find free objectid functions, inode objectid can easily
overflow after orphan file cleanup.

---

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

2 files changed, 10 insertions, 8 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 754c738ec2e8..2ed6918f32e5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -82,9 +82,10 @@ struct btrfs_ordered_sum;
 #define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL
 
 /*
- * All files have objectids higher than this.
+ * All files have objectids in this range.
  */
 #define BTRFS_FIRST_FREE_OBJECTID 256ULL
+#define BTRFS_LAST_FREE_OBJECTID -256ULL
 #define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL
 
 
diff --git a/fs/btrfs/inode-map.c b/fs/btrfs/inode-map.c
index 298346ae1481..cd6171c2da42 100644
--- a/fs/btrfs/inode-map.c
+++ b/fs/btrfs/inode-map.c
@@ -32,7 +32,8 @@ int btrfs_find_highest_inode(struct btrfs_root *root, u64 *objectid)
         path = btrfs_alloc_path();
         BUG_ON(!path);
 
-        search_key.objectid = (u64)-1;
+        search_key.objectid = BTRFS_LAST_FREE_OBJECTID;
+        search_key.type = -1;
         search_key.offset = (u64)-1;
         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
         if (ret < 0)
@@ -70,16 +71,17 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
         u64 search_start = dirid;
 
         mutex_lock(&root->objectid_mutex);
-        if (root->last_inode_alloc) {
+        if (root->last_inode_alloc >= BTRFS_FIRST_FREE_OBJECTID &&
+            root->last_inode_alloc < BTRFS_LAST_FREE_OBJECTID) {
                 *objectid = ++root->last_inode_alloc;
                 mutex_unlock(&root->objectid_mutex);
                 return 0;
         }
         path = btrfs_alloc_path();
         BUG_ON(!path);
-        search_start = root->last_inode_alloc;
         search_start = max(search_start, BTRFS_FIRST_FREE_OBJECTID);
         search_key.objectid = search_start;
+        search_key.type = 0;
         search_key.offset = 0;
 
         btrfs_init_path(path);
@@ -88,9 +90,6 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
         if (ret < 0)
                 goto error;
 
-        if (path->slots[0] > 0)
-                path->slots[0]--;
-
         while (1) {
                 l = path->nodes[0];
                 slot = path->slots[0];
@@ -120,13 +119,15 @@ int btrfs_find_free_objectid(struct btrfs_trans_handle *trans,
                                 }
                         }
                 }
+                if (key.objectid >= BTRFS_LAST_FREE_OBJECTID)
+                        break;
                 start_found = 1;
                 last_ino = key.objectid + 1;
                 path->slots[0]++;
         }
         // FIXME -ENOSPC
+        BUG_ON(1);
 found:
-        root->last_inode_alloc = *objectid;
         btrfs_release_path(root, path);
         btrfs_free_path(path);
         BUG_ON(*objectid < search_start);