[PATCHv2 0/4] loop: enable different physical blocksizes

[PATCHv2 0/4] loop: enable different physical blocksizes

[Hannes Reinecke]

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

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      | 35 ++++++++++++++++++++++++++++++-----
 drivers/block/loop.h      |  1 +
 include/uapi/linux/loop.h |  1 +
 3 files changed, 32 insertions(+), 5 deletions(-)

-- 
1.8.4.5

[PATCH 1/4] loop: Remove unused 'bdev' argument from loop_set_capacity

[Hannes Reinecke]

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 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 f7a4c9d..b9e12a0 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1130,7 +1130,7 @@ 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;
@@ -1179,7 +1179,7 @@ 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;
 	default:
 		err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
-- 
1.8.4.5

[PATCH 2/4] loop: Enable correct physical blocksize

[Hannes Reinecke]

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 ioctl.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 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 b9e12a0..fce13bd 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -177,6 +177,8 @@ 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 */
@@ -758,7 +760,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 
 	lo->lo_blocksize = lo_blocksize;
 	lo->lo_device = bdev;
-	lo->lo_flags = lo_flags;
+	lo->lo_flags |= lo_flags;
 	lo->lo_backing_file = file;
 	lo->transfer = NULL;
 	lo->ioctl = NULL;
@@ -769,6 +771,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
 		blk_queue_flush(lo->lo_queue, REQ_FLUSH);
 
+	if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
+		blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
 	set_capacity(lo->lo_disk, size);
 	bd_set_size(bdev, size << 9);
 	loop_sysfs_init(lo);
@@ -951,6 +955,9 @@ 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)
 		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h
index e0cecd2..caec9d3 100644
--- a/include/uapi/linux/loop.h
+++ b/include/uapi/linux/loop.h
@@ -21,6 +21,7 @@ enum {
 	LO_FLAGS_READ_ONLY	= 1,
 	LO_FLAGS_AUTOCLEAR	= 4,
 	LO_FLAGS_PARTSCAN	= 8,
+	LO_FLAGS_BLOCKSIZE	= 16,
 };
 
 #include <asm/posix_types.h>	/* for __kernel_old_dev_t */
-- 
1.8.4.5

Re: [PATCH 2/4] loop: Enable correct physical blocksize

[Ming Lei]

On Fri, Aug 7, 2015 at 4:54 AM, Hannes Reinecke <hare@suse.de> wrote:
> 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 ioctl.
>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  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 b9e12a0..fce13bd 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -177,6 +177,8 @@ 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 */
> @@ -758,7 +760,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
>
>         lo->lo_blocksize = lo_blocksize;
>         lo->lo_device = bdev;
> -       lo->lo_flags = lo_flags;
> +       lo->lo_flags |= lo_flags;

lo->lo_flags is cleared in loop_clr_fd(), and set_status() can only
be done when loop's state is bound, so why do you want to
keep previous zero flag?

>         lo->lo_backing_file = file;
>         lo->transfer = NULL;
>         lo->ioctl = NULL;
> @@ -769,6 +771,8 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
>         if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
>                 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
>
> +       if (lo->lo_flags & LO_FLAGS_BLOCKSIZE)
> +               blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize);
>         set_capacity(lo->lo_disk, size);
>         bd_set_size(bdev, size << 9);
>         loop_sysfs_init(lo);
> @@ -951,6 +955,9 @@ 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)
>                 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
> diff --git a/include/uapi/linux/loop.h b/include/uapi/linux/loop.h
> index e0cecd2..caec9d3 100644
> --- a/include/uapi/linux/loop.h
> +++ b/include/uapi/linux/loop.h
> @@ -21,6 +21,7 @@ enum {
>         LO_FLAGS_READ_ONLY      = 1,
>         LO_FLAGS_AUTOCLEAR      = 4,
>         LO_FLAGS_PARTSCAN       = 8,
> +       LO_FLAGS_BLOCKSIZE      = 16,
>  };
>
>  #include <asm/posix_types.h>   /* for __kernel_old_dev_t */
> --
> 1.8.4.5
>



-- 
Ming Lei

[PATCH 3/4] loop: Add 'lo_logical_blocksize'

[Hannes Reinecke]

Add a new field 'lo_logical_blocksize' to hold the logical
blocksize of the loop device.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/block/loop.c | 14 +++++++++++---
 drivers/block/loop.h |  1 +
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index fce13bd..321f296 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -177,8 +177,11 @@ 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 */
@@ -666,6 +669,7 @@ 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
@@ -685,7 +689,7 @@ static void loop_config_discard(struct loop_device *lo)
 
 	q->limits.discard_granularity = inode->i_sb->s_blocksize;
 	q->limits.discard_alignment = 0;
-	q->limits.max_discard_sectors = UINT_MAX >> 9;
+	q->limits.max_discard_sectors = UINT_MAX >> lo_bits;
 	q->limits.discard_zeroes_data = 1;
 	queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 }
@@ -759,6 +763,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
 
 	lo->lo_blocksize = lo_blocksize;
+	lo->lo_logical_blocksize = 512;
 	lo->lo_device = bdev;
 	lo->lo_flags |= lo_flags;
 	lo->lo_backing_file = file;
@@ -771,8 +776,11 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
 		blk_queue_flush(lo->lo_queue, REQ_FLUSH);
 
-	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, size);
 	bd_set_size(bdev, size << 9);
 	loop_sysfs_init(lo);
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 25e8997..93af885 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;
-- 
1.8.4.5

[PATCH 4/4] loop: Pass logical blocksize in 'lo_init[0]' ioctl field

[Hannes Reinecke]

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 <hare@suse.de>
---
 drivers/block/loop.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 321f296..3d2ee0f 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -963,11 +963,21 @@ 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;
+		lo->lo_logical_blocksize = info->lo_init[0];
+	}
 
 	if (lo->lo_offset != info->lo_offset ||
-	    lo->lo_sizelimit != info->lo_sizelimit)
+	    lo->lo_sizelimit != info->lo_sizelimit ||
+	    lo->lo_flags & LO_FLAGS_BLOCKSIZE)
 		if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
 			return -EFBIG;
 
-- 
1.8.4.5

[PATCHv3 0/4] loop: enable different physical blocksizes

[Hannes Reinecke]

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

[PATCH 1/4] loop: Remove unused 'bdev' argument from loop_set_capacity

[Hannes Reinecke]

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 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

Re: [PATCH 1/4] loop: Remove unused 'bdev' argument from loop_set_capacity

[Ming Lei]

On Tue, Nov 1, 2016 at 3:37 AM, Hannes Reinecke <hare@suse.de> wrote:
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
>  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 <tom.leiming@gmail.com>


thanks,
Ming Lei