From: Ben Slusky We need to set the hardsect_size of the loop device to that of the real device. The loop device advertises a block size of 1024 even when configured over a cdrom. When burning a ext2 on a cd, and mounting it directly, I get: blocksize=2048; when I losetup /dev/loop0 /dev/cdrom, and then try to mount, I get: blocksize=1024; and then misaligned transfer; this results in not being able to read the superblock. The loop device should be changed to export the same blocksize of the underlying device --- 25-akpm/drivers/block/loop.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff -puN drivers/block/loop.c~loop-fix-hardsect drivers/block/loop.c --- 25/drivers/block/loop.c~loop-fix-hardsect Wed Jan 14 14:04:29 2004 +++ 25-akpm/drivers/block/loop.c Wed Jan 14 14:42:52 2004 @@ -732,8 +732,6 @@ static int loop_set_fd(struct loop_devic mapping_set_gfp_mask(inode->i_mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); - set_blocksize(bdev, lo_blocksize); - lo->lo_bio = lo->lo_biotail = NULL; /* @@ -752,11 +750,14 @@ static int loop_set_fd(struct loop_devic blk_queue_max_sectors(lo->lo_queue, q->max_sectors); blk_queue_max_phys_segments(lo->lo_queue,q->max_phys_segments); blk_queue_max_hw_segments(lo->lo_queue, q->max_hw_segments); + blk_queue_hardsect_size(lo->lo_queue, queue_hardsect_size(q)); blk_queue_max_segment_size(lo->lo_queue, q->max_segment_size); blk_queue_segment_boundary(lo->lo_queue, q->seg_boundary_mask); blk_queue_merge_bvec(lo->lo_queue, q->merge_bvec_fn); } + set_blocksize(bdev, lo_blocksize); + kernel_thread(loop_thread, lo, CLONE_KERNEL); down(&lo->lo_sem); _