btrfs: heed alloc_start

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
index a9f1fc2..45c592a 100644 (file)
--- 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;