btrfs: fix ASSERT em->len condition in btrfs_get_extent

The em->len value is supposed to be verified in the assertion condition
though we expect it to be same as the sectorsize.

Fixes: a196a894 ("btrfs: do not reset extent map members for inline extents read")
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NTanmay Bhushan <007047221b@gmail.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -7092,7 +7092,7 @@ struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
 		 * Other members are not utilized for inline extents.
 		 */
 		ASSERT(em->block_start == EXTENT_MAP_INLINE);
-		ASSERT(em->len = fs_info->sectorsize);
+		ASSERT(em->len == fs_info->sectorsize);
 
 		ret = read_inline_extent(inode, path, page);
 		if (ret < 0)