From: Ben Slusky <sluskyb@paranoiacs.org>
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
---
drivers/block/loop.c | 16 +++++++---------
1 files changed, 7 insertions(+), 9 deletions(-)
diff -puN drivers/block/loop.c~loop-fix-hardsect drivers/block/loop.c
--- 25/drivers/block/loop.c~loop-fix-hardsect 2004-01-07 21:18:52.000000000 -0800
+++ 25-akpm/drivers/block/loop.c 2004-01-07 21:20:52.000000000 -0800
@@ -676,7 +676,6 @@ static int loop_set_fd(struct loop_devic
if (!file)
goto out;
- error = -EINVAL;
inode = file->f_dentry->d_inode;
if (!(file->f_mode & FMODE_WRITE))
@@ -686,7 +685,7 @@ static int loop_set_fd(struct loop_devic
lo_device = inode->i_bdev;
if (lo_device == bdev) {
error = -EBUSY;
- goto out;
+ goto out_putf;
}
lo_blocksize = block_size(lo_device);
if (bdev_read_only(lo_device))
@@ -697,6 +696,7 @@ static int loop_set_fd(struct loop_devic
* If we can't read - sorry. If we only can't write - well,
* it's going to be read-only.
*/
+ error = -EINVAL;
if (!inode->i_fop->sendfile)
goto out_putf;
@@ -709,8 +709,6 @@ static int loop_set_fd(struct loop_devic
} else
goto out_putf;
- get_file(file);
-
if (!(lo_file->f_mode & FMODE_WRITE))
lo_flags |= LO_FLAGS_READ_ONLY;
@@ -725,15 +723,12 @@ static int loop_set_fd(struct loop_devic
lo->lo_sizelimit = 0;
if (figure_loop_size(lo)) {
error = -EFBIG;
- fput(file);
goto out_putf;
}
lo->old_gfp_mask = mapping_gfp_mask(inode->i_mapping);
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;
/*
@@ -752,15 +747,18 @@ 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);
}
+ error = set_blocksize(bdev, lo_blocksize);
+ if (error)
+ goto out_putf;
+
kernel_thread(loop_thread, lo, CLONE_KERNEL);
down(&lo->lo_sem);
-
- fput(file);
return 0;
out_putf:
_