btrfs: heed alloc_start

Arne Jansen · Arne Jansen · commit a9c9bf68276c · 2011-05-13T15:36:12.000+02:00
currently alloc_start is disregarded if the requested
chunk size is bigger than (device size - alloc_start),
but smaller than the device size.
The only situation where I see this could have made sense
was when a chunk equal the size of the device has been
requested. This was possible as the allocator failed to
take alloc_start into account when calculating the request
chunk size. As this gets fixed by this patch, the workaround
is not necessary anymore.
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
@@ -849,10 +849,7 @@ int find_free_dev_extent(struct btrfs_trans_handle *trans,
 	/* we don't want to overwrite the superblock on the drive,
 	 * so we make sure to start at an offset of at least 1MB
 	 */
-	search_start = 1024 * 1024;
-
-	if (root->fs_info->alloc_start + num_bytes <= search_end)
-		search_start = max(root->fs_info->alloc_start, search_start);
+	search_start = max(root->fs_info->alloc_start, 1024ull * 1024);
 
 	max_hole_start = search_start;
 	max_hole_size = 0;
