Currently the loop driver just simulates 512-byte blocks. When
creating bootable images for virtual machines it might be required
to use a different physical blocksize (eg 4k for S/390 DASD), as
the some bootloaders (like lilo or zipl for S/390) need to know
the physical block addresses of the kernel and initrd.
This patchset extends the current LOOP_SET_STATUS64 ioctl to
set the logical and physical blocksize by re-using the existing
'init' fields, which are currently unused.
As usual, comments and reviews are welcome.
Changes to v1:
- Move LO_FLAGS_BLOCKSIZE definition
- Reshuffle patches
Changes to v2:
- Include reviews from Ming Lei
Hannes Reinecke (4):
loop: Remove unused 'bdev' argument from loop_set_capacity
loop: Enable correct physical blocksize
loop: Add 'lo_logical_blocksize'
loop: Pass logical blocksize in 'lo_init[0]' ioctl field
drivers/block/loop.c | 40 +++++++++++++++++++++++++++++++++-------
drivers/block/loop.h | 1 +
include/uapi/linux/loop.h | 1 +
3 files changed, 35 insertions(+), 7 deletions(-)
--
2.6.6
Add a new field 'lo_logical_blocksize' to hold the logical
blocksize of the loop device.
Signed-off-by: Hannes Reinecke <[email protected]>
---
drivers/block/loop.c | 9 +++++++--
drivers/block/loop.h | 1 +
2 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index ff5c874..a863667 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -233,8 +233,11 @@ figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
lo->lo_offset = offset;
if (lo->lo_sizelimit != sizelimit)
lo->lo_sizelimit = sizelimit;
- if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
+ if (lo->lo_flags & LO_FLAGS_BLOCKSIZE) {
blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
+ blk_queue_logical_block_size(lo->lo_queue,
+ lo->lo_logical_blocksize);
+ }
set_capacity(lo->lo_disk, x);
bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
/* let user-space know about the new size */
@@ -816,6 +819,7 @@ static void loop_config_discard(struct loop_device *lo)
struct file *file = lo->lo_backing_file;
struct inode *inode = file->f_mapping->host;
struct request_queue *q = lo->lo_queue;
+ int lo_bits = blksize_bits(lo->lo_logical_blocksize);
/*
* We use punch hole to reclaim the free space used by the
@@ -835,7 +839,7 @@ static void loop_config_discard(struct loop_device *lo)
q->limits.discard_granularity = inode->i_sb->s_blocksize;
q->limits.discard_alignment = 0;
- blk_queue_max_discard_sectors(q, UINT_MAX >> 9);
+ blk_queue_max_discard_sectors(q, UINT_MAX >> lo_bits);
q->limits.discard_zeroes_data = 1;
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
}
@@ -924,6 +928,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
lo->use_dio = false;
lo->lo_blocksize = lo_blocksize;
+ lo->lo_logical_blocksize = 512;
lo->lo_device = bdev;
lo->lo_flags = lo_flags;
lo->lo_backing_file = file;
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index fb2237c..579f2f7 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -49,6 +49,7 @@ struct loop_device {
struct file * lo_backing_file;
struct block_device *lo_device;
unsigned lo_blocksize;
+ unsigned lo_logical_blocksize;
void *key_data;
gfp_t old_gfp_mask;
--
2.6.6
The current LOOP_SET_STATUS64 ioctl has two unused fields
'init[2]', which can be used in conjunction with the
LO_FLAGS_BLOCKSIZE flag to pass in the new logical blocksize.
Signed-off-by: Hannes Reinecke <[email protected]>
---
drivers/block/loop.c | 24 +++++++++++++++++++-----
1 file changed, 19 insertions(+), 5 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index a863667..9ad56bf 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -221,7 +221,8 @@ static void __loop_update_dio(struct loop_device *lo, bool dio)
}
static int
-figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
+figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit,
+ loff_t logical_blocksize)
{
loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
sector_t x = (sector_t)size;
@@ -234,6 +235,7 @@ figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
if (lo->lo_sizelimit != sizelimit)
lo->lo_sizelimit = sizelimit;
if (lo->lo_flags & LO_FLAGS_BLOCKSIZE) {
+ lo->lo_logical_blocksize = logical_blocksize;
blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
blk_queue_logical_block_size(lo->lo_queue,
lo->lo_logical_blocksize);
@@ -1124,13 +1126,24 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
if (err)
return err;
- if (info->lo_flags & LO_FLAGS_BLOCKSIZE)
+ if (info->lo_flags & LO_FLAGS_BLOCKSIZE) {
lo->lo_flags |= LO_FLAGS_BLOCKSIZE;
+ if ((info->lo_init[0] != 512) &&
+ (info->lo_init[0] != 1024) &&
+ (info->lo_init[0] != 2048) &&
+ (info->lo_init[0] != 4096))
+ return -EINVAL;
+ if (info->lo_init[0] > lo->lo_blocksize)
+ return -EINVAL;
+ }
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit ||
- lo->lo_flags != lo_flags)
- if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
+ lo->lo_flags != lo_flags ||
+ ((lo->lo_flags & LO_FLAGS_BLOCKSIZE) &&
+ (lo->lo_logical_blocksize != info->lo_init[0])))
+ if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit,
+ info->lo_init[0]))
return -EFBIG;
loop_config_discard(lo);
@@ -1315,7 +1328,8 @@ static int loop_set_capacity(struct loop_device *lo)
if (unlikely(lo->lo_state != Lo_bound))
return -ENXIO;
- return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
+ return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit,
+ lo->lo_logical_blocksize);
}
static int loop_set_dio(struct loop_device *lo, unsigned long arg)
--
2.6.6
When running on files the physical blocksize is actually 4k,
so we should be announcing it as such. This is enabled with
a new LO_FLAGS_BLOCKSIZE flag value to the existing
loop_set_status ioctl.
Signed-off-by: Hannes Reinecke <[email protected]>
---
drivers/block/loop.c | 9 ++++++++-
include/uapi/linux/loop.h | 1 +
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 3008dec..ff5c874 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -233,6 +233,8 @@ figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
lo->lo_offset = offset;
if (lo->lo_sizelimit != sizelimit)
lo->lo_sizelimit = sizelimit;
+ if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
+ blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
set_capacity(lo->lo_disk, x);
bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
/* let user-space know about the new size */
@@ -1087,6 +1089,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
int err;
struct loop_func_table *xfer;
kuid_t uid = current_uid();
+ int lo_flags = lo->lo_flags;
if (lo->lo_encrypt_key_size &&
!uid_eq(lo->lo_key_owner, uid) &&
@@ -1116,8 +1119,12 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
if (err)
return err;
+ if (info->lo_flags & LO_FLAGS_BLOCKSIZE)
+ lo->lo_flags |= LO_FLAGS_BLOCKSIZE;
+
if (lo->lo_offset != info->lo_offset ||
- lo->lo_sizelimit != info->lo_sizelimit)
+ lo->lo_sizelimit != info->lo_sizelimit ||
+ lo->lo_flags != lo_flags)
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
return -EFBIG;
diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h
index c8125ec..2691c1c 100644
--- a/include/uapi/linux/loop.h
+++ b/include/uapi/linux/loop.h
@@ -22,6 +22,7 @@ enum {
LO_FLAGS_AUTOCLEAR = 4,
LO_FLAGS_PARTSCAN = 8,
LO_FLAGS_DIRECT_IO = 16,
+ LO_FLAGS_BLOCKSIZE = 32,
};
#include <asm/posix_types.h> /* for __kernel_old_dev_t */
--
2.6.6
Signed-off-by: Hannes Reinecke <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
---
drivers/block/loop.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index fa1b7a9..3008dec 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1298,7 +1298,7 @@ loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
return err;
}
-static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
+static int loop_set_capacity(struct loop_device *lo)
{
if (unlikely(lo->lo_state != Lo_bound))
return -ENXIO;
@@ -1361,7 +1361,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
case LOOP_SET_CAPACITY:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
- err = loop_set_capacity(lo, bdev);
+ err = loop_set_capacity(lo);
break;
case LOOP_SET_DIRECT_IO:
err = -EPERM;
--
2.6.6
On Tue, Nov 1, 2016 at 3:37 AM, Hannes Reinecke <[email protected]> wrote:
> Signed-off-by: Hannes Reinecke <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>
> ---
> drivers/block/loop.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index fa1b7a9..3008dec 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1298,7 +1298,7 @@ loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
> return err;
> }
>
> -static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
> +static int loop_set_capacity(struct loop_device *lo)
> {
> if (unlikely(lo->lo_state != Lo_bound))
> return -ENXIO;
> @@ -1361,7 +1361,7 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode,
> case LOOP_SET_CAPACITY:
> err = -EPERM;
> if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
> - err = loop_set_capacity(lo, bdev);
> + err = loop_set_capacity(lo);
> break;
> case LOOP_SET_DIRECT_IO:
> err = -EPERM;
Reviewed-by: Ming Lei <[email protected]>
thanks,
Ming Lei
On Mon, Oct 31, 2016 at 08:37:17PM +0100, Hannes Reinecke wrote:
> When running on files the physical blocksize is actually 4k,
Is it? Independent of that sentence the patch looks fine:
Reviewed-by: Christoph Hellwig <[email protected]>
On Mon, Oct 31, 2016 at 08:37:18PM +0100, Hannes Reinecke wrote:
> Add a new field 'lo_logical_blocksize' to hold the logical
> blocksize of the loop device.
Why do we use the same flag for both block sizes? If there is a good
reason for that it should be documented and both should be in the same
patch.
On Mon, Oct 31, 2016 at 08:37:19PM +0100, Hannes Reinecke wrote:
> The current LOOP_SET_STATUS64 ioctl has two unused fields
> 'init[2]', which can be used in conjunction with the
> LO_FLAGS_BLOCKSIZE flag to pass in the new logical blocksize.
Can we give them sane field names while at it? Also I see now reason
not to merge this with the previous two patches.
On 11/01/2016 03:01 PM, Christoph Hellwig wrote:
> On Mon, Oct 31, 2016 at 08:37:18PM +0100, Hannes Reinecke wrote:
>> Add a new field 'lo_logical_blocksize' to hold the logical
>> blocksize of the loop device.
>
> Why do we use the same flag for both block sizes? If there is a good
> reason for that it should be documented and both should be in the same
> patch.
>
_Actually_ the flag enables you to set the logical blocksize.
However, if you want to set the logical blocksize you also have to set a
matching physical blocksize.
And the physical blocksize itself isn't settable, rather taken from the
underlying device/filesystem/whatever.
So the flag itself does not have a dual purpose, it's just out of
necessity that you have to set the physical blocksize if you want to
change the logical blocksize.
And I got pushback when I proposed to set the physical blocksize always,
so I made it dependent on the LO_BLOCKSIZE flag, too.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: J. Hawn, J. Guild, F. Imend?rffer, HRB 16746 (AG N?rnberg)
On 11/01/2016 03:02 PM, Christoph Hellwig wrote:
> On Mon, Oct 31, 2016 at 08:37:19PM +0100, Hannes Reinecke wrote:
>> The current LOOP_SET_STATUS64 ioctl has two unused fields
>> 'init[2]', which can be used in conjunction with the
>> LO_FLAGS_BLOCKSIZE flag to pass in the new logical blocksize.
>
> Can we give them sane field names while at it? Also I see now reason
> not to merge this with the previous two patches.
>
Sure I can rename it.
As for merging, I don't really care.
So for the next round I'll be merging them all together.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: J. Hawn, J. Guild, F. Imend?rffer, HRB 16746 (AG N?rnberg)
On 11/01/2016 03:02 PM, Christoph Hellwig wrote:
> On Mon, Oct 31, 2016 at 08:37:19PM +0100, Hannes Reinecke wrote:
>> The current LOOP_SET_STATUS64 ioctl has two unused fields
>> 'init[2]', which can be used in conjunction with the
>> LO_FLAGS_BLOCKSIZE flag to pass in the new logical blocksize.
>
> Can we give them sane field names while at it? Also I see now reason
> not to merge this with the previous two patches.
>
I'd rather not change the name; it's part of the exported ioctl
interface, and changing would mean to change the ioctl interface.
Which would make quite some user-space programs barf.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
[email protected] +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N?rnberg
GF: J. Hawn, J. Guild, F. Imend?rffer, HRB 16746 (AG N?rnberg)