[PATCH v4 0/2] s390/dasd: remove ioctl_by_bdev from DASD driver

[PATCH v4 0/2] s390/dasd: remove ioctl_by_bdev from DASD driver

[Stefan Haberland]

Hi Christoph,

here are the patches again. Reviewed and tested internally with DASD as
well as DASD labeled virtblk devices.
So if you agree with the two patches I have no objection against an
inclusion.

v3->v4:
  - merged patches
  - use symbol_get instead of kallsyms_lookup_name
  - add some comments and some cleanup

Christoph Hellwig (1):
  dasd: refactor dasd_ioctl_information

Stefan Haberland (1):
  s390/dasd: remove ioctl_by_bdev calls

 MAINTAINERS                     |  1 +
 block/partitions/ibm.c          | 24 ++++++++---
 drivers/s390/block/dasd_ioctl.c | 76 ++++++++++++++++++++++++---------
 include/linux/dasd_mod.h        |  9 ++++
 4 files changed, 85 insertions(+), 25 deletions(-)
 create mode 100644 include/linux/dasd_mod.h

-- 
2.17.1

[PATCH v4 1/2] dasd: refactor dasd_ioctl_information

[Stefan Haberland]

From: Christoph Hellwig <hch@lst.de>

Prepare for in-kernel callers of this functionality.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[sth@de.ibm.com: remove leftover kfree]
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
---
 drivers/s390/block/dasd_ioctl.c | 42 ++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 9a5f3add325f..9b7782395c37 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -457,10 +457,9 @@ static int dasd_ioctl_read_profile(struct dasd_block *block, void __user *argp)
 /*
  * Return dasd information. Used for BIODASDINFO and BIODASDINFO2.
  */
-static int dasd_ioctl_information(struct dasd_block *block,
-				  unsigned int cmd, void __user *argp)
+static int __dasd_ioctl_information(struct dasd_block *block,
+		struct dasd_information2_t *dasd_info)
 {
-	struct dasd_information2_t *dasd_info;
 	struct subchannel_id sch_id;
 	struct ccw_dev_id dev_id;
 	struct dasd_device *base;
@@ -473,15 +472,9 @@ static int dasd_ioctl_information(struct dasd_block *block,
 	if (!base->discipline || !base->discipline->fill_info)
 		return -EINVAL;
 
-	dasd_info = kzalloc(sizeof(struct dasd_information2_t), GFP_KERNEL);
-	if (dasd_info == NULL)
-		return -ENOMEM;
-
 	rc = base->discipline->fill_info(base, dasd_info);
-	if (rc) {
-		kfree(dasd_info);
+	if (rc)
 		return rc;
-	}
 
 	cdev = base->cdev;
 	ccw_device_get_id(cdev, &dev_id);
@@ -520,15 +513,24 @@ static int dasd_ioctl_information(struct dasd_block *block,
 	list_for_each(l, &base->ccw_queue)
 		dasd_info->chanq_len++;
 	spin_unlock_irqrestore(&block->queue_lock, flags);
+	return 0;
+}
 
-	rc = 0;
-	if (copy_to_user(argp, dasd_info,
-			 ((cmd == (unsigned int) BIODASDINFO2) ?
-			  sizeof(struct dasd_information2_t) :
-			  sizeof(struct dasd_information_t))))
-		rc = -EFAULT;
+static int dasd_ioctl_information(struct dasd_block *block, void __user *argp,
+		size_t copy_size)
+{
+	struct dasd_information2_t *dasd_info;
+	int error;
+
+	dasd_info = kzalloc(sizeof(*dasd_info), GFP_KERNEL);
+	if (!dasd_info)
+		return -ENOMEM;
+
+	error = __dasd_ioctl_information(block, dasd_info);
+	if (!error && copy_to_user(argp, dasd_info, copy_size))
+		error = -EFAULT;
 	kfree(dasd_info);
-	return rc;
+	return error;
 }
 
 /*
@@ -622,10 +624,12 @@ int dasd_ioctl(struct block_device *bdev, fmode_t mode,
 		rc = dasd_ioctl_check_format(bdev, argp);
 		break;
 	case BIODASDINFO:
-		rc = dasd_ioctl_information(block, cmd, argp);
+		rc = dasd_ioctl_information(block, argp,
+				sizeof(struct dasd_information_t));
 		break;
 	case BIODASDINFO2:
-		rc = dasd_ioctl_information(block, cmd, argp);
+		rc = dasd_ioctl_information(block, argp,
+				sizeof(struct dasd_information2_t));
 		break;
 	case BIODASDPRRD:
 		rc = dasd_ioctl_read_profile(block, argp);
-- 
2.17.1

[PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Stefan Haberland]

The IBM partition parser requires device type specific information only
available to the DASD driver to correctly register partitions. The
current approach of using ioctl_by_bdev with a fake user space pointer
is discouraged.

Fix this by replacing IOCTL calls with direct in-kernel function calls.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
---
 MAINTAINERS                     |  1 +
 block/partitions/ibm.c          | 24 +++++++++++++++++------
 drivers/s390/block/dasd_ioctl.c | 34 +++++++++++++++++++++++++++++++++
 include/linux/dasd_mod.h        |  9 +++++++++
 4 files changed, 62 insertions(+), 6 deletions(-)
 create mode 100644 include/linux/dasd_mod.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 1608ef8ce8d3..37f700187d74 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14625,6 +14625,7 @@ S:	Supported
 W:	http://www.ibm.com/developerworks/linux/linux390/
 F:	block/partitions/ibm.c
 F:	drivers/s390/block/dasd*
+F:	include/linux/dasd_mod.h
 
 S390 IOMMU (PCI)
 M:	Gerald Schaefer <gerald.schaefer@de.ibm.com>
diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
index 073faa6a69b8..d6e18df9c53c 100644
--- a/block/partitions/ibm.c
+++ b/block/partitions/ibm.c
@@ -13,10 +13,11 @@
 #include <asm/ebcdic.h>
 #include <linux/uaccess.h>
 #include <asm/vtoc.h>
+#include <linux/module.h>
+#include <linux/dasd_mod.h>
 
 #include "check.h"
 
-
 union label_t {
 	struct vtoc_volume_label_cdl vol;
 	struct vtoc_volume_label_ldl lnx;
@@ -288,7 +289,9 @@ static int find_cms1_partitions(struct parsed_partitions *state,
  */
 int ibm_partition(struct parsed_partitions *state)
 {
+	int (*fn)(struct gendisk *disk, dasd_information2_t *info);
 	struct block_device *bdev = state->bdev;
+	struct gendisk *disk = bdev->bd_disk;
 	int blocksize, res;
 	loff_t i_size, offset, size;
 	dasd_information2_t *info;
@@ -299,24 +302,31 @@ int ibm_partition(struct parsed_partitions *state)
 	union label_t *label;
 
 	res = 0;
+	if (!disk->fops->getgeo)
+		goto out_exit;
+	fn = symbol_get(dasd_biodasdinfo);
+	if (!fn)
+		goto out_exit;
 	blocksize = bdev_logical_block_size(bdev);
 	if (blocksize <= 0)
-		goto out_exit;
+		goto out_symbol;
 	i_size = i_size_read(bdev->bd_inode);
 	if (i_size == 0)
-		goto out_exit;
+		goto out_symbol;
 	info = kmalloc(sizeof(dasd_information2_t), GFP_KERNEL);
 	if (info == NULL)
-		goto out_exit;
+		goto out_symbol;
 	geo = kmalloc(sizeof(struct hd_geometry), GFP_KERNEL);
 	if (geo == NULL)
 		goto out_nogeo;
 	label = kmalloc(sizeof(union label_t), GFP_KERNEL);
 	if (label == NULL)
 		goto out_nolab;
-	if (ioctl_by_bdev(bdev, HDIO_GETGEO, (unsigned long)geo) != 0)
+	/* set start if not filled by getgeo function e.g. virtblk */
+	geo->start = get_start_sect(bdev);
+	if (disk->fops->getgeo(bdev, geo))
 		goto out_freeall;
-	if (ioctl_by_bdev(bdev, BIODASDINFO2, (unsigned long)info) != 0) {
+	if (fn(disk, info)) {
 		kfree(info);
 		info = NULL;
 	}
@@ -359,6 +369,8 @@ int ibm_partition(struct parsed_partitions *state)
 	kfree(geo);
 out_nogeo:
 	kfree(info);
+out_symbol:
+	symbol_put(dasd_biodasdinfo);
 out_exit:
 	return res;
 }
diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
index 9b7782395c37..777734d1b4e5 100644
--- a/drivers/s390/block/dasd_ioctl.c
+++ b/drivers/s390/block/dasd_ioctl.c
@@ -22,6 +22,7 @@
 #include <asm/schid.h>
 #include <asm/cmb.h>
 #include <linux/uaccess.h>
+#include <linux/dasd_mod.h>
 
 /* This is ugly... */
 #define PRINTK_HEADER "dasd_ioctl:"
@@ -664,3 +665,36 @@ int dasd_ioctl(struct block_device *bdev, fmode_t mode,
 	dasd_put_device(base);
 	return rc;
 }
+
+
+/**
+ * dasd_biodasdinfo() - fill out the dasd information structure
+ * @disk [in]: pointer to gendisk structure that references a DASD
+ * @info [out]: pointer to the dasd_information2_t structure
+ *
+ * Provide access to DASD specific information.
+ * The gendisk structure is checked if it belongs to the DASD driver by
+ * comparing the gendisk->fops pointer.
+ * If it does not belong to the DASD driver -EINVAL is returned.
+ * Otherwise the provided dasd_information2_t structure is filled out.
+ *
+ * Returns:
+ *   %0 on success and a negative error value on failure.
+ */
+int dasd_biodasdinfo(struct gendisk *disk, struct dasd_information2_t *info)
+{
+	struct dasd_device *base;
+	int error;
+
+	if (disk->fops != &dasd_device_operations)
+		return -EINVAL;
+
+	base = dasd_device_from_gendisk(disk);
+	if (!base)
+		return -ENODEV;
+	error = __dasd_ioctl_information(base->block, info);
+	dasd_put_device(base);
+	return error;
+}
+/* export that symbol_get in partition detection is possible */
+EXPORT_SYMBOL_GPL(dasd_biodasdinfo);
diff --git a/include/linux/dasd_mod.h b/include/linux/dasd_mod.h
new file mode 100644
index 000000000000..d39abad2ff6e
--- /dev/null
+++ b/include/linux/dasd_mod.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef DASD_MOD_H
+#define DASD_MOD_H
+
+#include <asm/dasd.h>
+
+extern int dasd_biodasdinfo(struct gendisk *disk, dasd_information2_t *info);
+
+#endif
-- 
2.17.1

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCH 3/2] block: remove ioctl_by_bdev

[Christoph Hellwig]

No callers left.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/block_dev.c     | 12 ------------
 include/linux/fs.h |  1 -
 2 files changed, 13 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index ebd1507789d29..2eb92456a22e7 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -2166,18 +2166,6 @@ const struct file_operations def_blk_fops = {
 	.fallocate	= blkdev_fallocate,
 };
 
-int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
-{
-	int res;
-	mm_segment_t old_fs = get_fs();
-	set_fs(KERNEL_DS);
-	res = blkdev_ioctl(bdev, 0, cmd, arg);
-	set_fs(old_fs);
-	return res;
-}
-
-EXPORT_SYMBOL(ioctl_by_bdev);
-
 /**
  * lookup_bdev  - lookup a struct block_device by name
  * @pathname:	special file representing the block device
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1a95e51588113..861ca61d728bc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2636,7 +2636,6 @@ extern int sync_filesystem(struct super_block *);
 extern const struct file_operations def_blk_fops;
 extern const struct file_operations def_chr_fops;
 #ifdef CONFIG_BLOCK
-extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
 extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
 extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
 extern int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder);
-- 
2.26.2

Re: [PATCH 3/2] block: remove ioctl_by_bdev

[Al Viro]

On Tue, May 19, 2020 at 04:33:21PM +0200, Christoph Hellwig wrote:
> No callers left.

No callers left after...?  IOW, where are the patches?  There'd been
several patchsets posted, each with more than one revision...

I realize that some of that went into -mm, but could you repost
the final variant of the entire pile and/or tell which set of
git branches to look at?

Re: [PATCH 3/2] block: remove ioctl_by_bdev

[Christoph Hellwig]

On Tue, May 19, 2020 at 08:03:33PM +0100, Al Viro wrote:
> On Tue, May 19, 2020 at 04:33:21PM +0200, Christoph Hellwig wrote:
> > No callers left.
> 
> No callers left after...?  IOW, where are the patches?  There'd been
> several patchsets posted, each with more than one revision...

In Jens' for-5.8/block tree, which has all the patches to remove them
merged.

Link: https://git.kernel.dk/cgit/linux-block/log/?h=for-5.8/block

Re: [PATCH v4 0/2] s390/dasd: remove ioctl_by_bdev from DASD driver

[Jens Axboe]

On 5/19/20 8:22 AM, Stefan Haberland wrote:
> Hi Christoph,
> 
> here are the patches again. Reviewed and tested internally with DASD as
> well as DASD labeled virtblk devices.
> So if you agree with the two patches I have no objection against an
> inclusion.

Applied for 5.8, with Christoph's removal patch as well.

-- 
Jens Axboe

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christian Borntraeger]

On 19.05.20 16:22, Stefan Haberland wrote:
> The IBM partition parser requires device type specific information only
> available to the DASD driver to correctly register partitions. The
> current approach of using ioctl_by_bdev with a fake user space pointer
> is discouraged.
> 
> Fix this by replacing IOCTL calls with direct in-kernel function calls.
> 
> Suggested-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
> Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>

FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.

> ---
>  MAINTAINERS                     |  1 +
>  block/partitions/ibm.c          | 24 +++++++++++++++++------
>  drivers/s390/block/dasd_ioctl.c | 34 +++++++++++++++++++++++++++++++++
>  include/linux/dasd_mod.h        |  9 +++++++++
>  4 files changed, 62 insertions(+), 6 deletions(-)
>  create mode 100644 include/linux/dasd_mod.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 1608ef8ce8d3..37f700187d74 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -14625,6 +14625,7 @@ S:	Supported
>  W:	http://www.ibm.com/developerworks/linux/linux390/
>  F:	block/partitions/ibm.c
>  F:	drivers/s390/block/dasd*
> +F:	include/linux/dasd_mod.h
>  
>  S390 IOMMU (PCI)
>  M:	Gerald Schaefer <gerald.schaefer@de.ibm.com>
> diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
> index 073faa6a69b8..d6e18df9c53c 100644
> --- a/block/partitions/ibm.c
> +++ b/block/partitions/ibm.c
> @@ -13,10 +13,11 @@
>  #include <asm/ebcdic.h>
>  #include <linux/uaccess.h>
>  #include <asm/vtoc.h>
> +#include <linux/module.h>
> +#include <linux/dasd_mod.h>
>  
>  #include "check.h"
>  
> -
>  union label_t {
>  	struct vtoc_volume_label_cdl vol;
>  	struct vtoc_volume_label_ldl lnx;
> @@ -288,7 +289,9 @@ static int find_cms1_partitions(struct parsed_partitions *state,
>   */
>  int ibm_partition(struct parsed_partitions *state)
>  {
> +	int (*fn)(struct gendisk *disk, dasd_information2_t *info);
>  	struct block_device *bdev = state->bdev;
> +	struct gendisk *disk = bdev->bd_disk;
>  	int blocksize, res;
>  	loff_t i_size, offset, size;
>  	dasd_information2_t *info;
> @@ -299,24 +302,31 @@ int ibm_partition(struct parsed_partitions *state)
>  	union label_t *label;
>  
>  	res = 0;
> +	if (!disk->fops->getgeo)
> +		goto out_exit;
> +	fn = symbol_get(dasd_biodasdinfo);
> +	if (!fn)
> +		goto out_exit;
>  	blocksize = bdev_logical_block_size(bdev);
>  	if (blocksize <= 0)
> -		goto out_exit;
> +		goto out_symbol;
>  	i_size = i_size_read(bdev->bd_inode);
>  	if (i_size == 0)
> -		goto out_exit;
> +		goto out_symbol;
>  	info = kmalloc(sizeof(dasd_information2_t), GFP_KERNEL);
>  	if (info == NULL)
> -		goto out_exit;
> +		goto out_symbol;
>  	geo = kmalloc(sizeof(struct hd_geometry), GFP_KERNEL);
>  	if (geo == NULL)
>  		goto out_nogeo;
>  	label = kmalloc(sizeof(union label_t), GFP_KERNEL);
>  	if (label == NULL)
>  		goto out_nolab;
> -	if (ioctl_by_bdev(bdev, HDIO_GETGEO, (unsigned long)geo) != 0)
> +	/* set start if not filled by getgeo function e.g. virtblk */
> +	geo->start = get_start_sect(bdev);
> +	if (disk->fops->getgeo(bdev, geo))
>  		goto out_freeall;
> -	if (ioctl_by_bdev(bdev, BIODASDINFO2, (unsigned long)info) != 0) {
> +	if (fn(disk, info)) {
>  		kfree(info);
>  		info = NULL;
>  	}
> @@ -359,6 +369,8 @@ int ibm_partition(struct parsed_partitions *state)
>  	kfree(geo);
>  out_nogeo:
>  	kfree(info);
> +out_symbol:
> +	symbol_put(dasd_biodasdinfo);
>  out_exit:
>  	return res;
>  }
> diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
> index 9b7782395c37..777734d1b4e5 100644
> --- a/drivers/s390/block/dasd_ioctl.c
> +++ b/drivers/s390/block/dasd_ioctl.c
> @@ -22,6 +22,7 @@
>  #include <asm/schid.h>
>  #include <asm/cmb.h>
>  #include <linux/uaccess.h>
> +#include <linux/dasd_mod.h>
>  
>  /* This is ugly... */
>  #define PRINTK_HEADER "dasd_ioctl:"
> @@ -664,3 +665,36 @@ int dasd_ioctl(struct block_device *bdev, fmode_t mode,
>  	dasd_put_device(base);
>  	return rc;
>  }
> +
> +
> +/**
> + * dasd_biodasdinfo() - fill out the dasd information structure
> + * @disk [in]: pointer to gendisk structure that references a DASD
> + * @info [out]: pointer to the dasd_information2_t structure
> + *
> + * Provide access to DASD specific information.
> + * The gendisk structure is checked if it belongs to the DASD driver by
> + * comparing the gendisk->fops pointer.
> + * If it does not belong to the DASD driver -EINVAL is returned.
> + * Otherwise the provided dasd_information2_t structure is filled out.
> + *
> + * Returns:
> + *   %0 on success and a negative error value on failure.
> + */
> +int dasd_biodasdinfo(struct gendisk *disk, struct dasd_information2_t *info)
> +{
> +	struct dasd_device *base;
> +	int error;
> +
> +	if (disk->fops != &dasd_device_operations)
> +		return -EINVAL;
> +
> +	base = dasd_device_from_gendisk(disk);
> +	if (!base)
> +		return -ENODEV;
> +	error = __dasd_ioctl_information(base->block, info);
> +	dasd_put_device(base);
> +	return error;
> +}
> +/* export that symbol_get in partition detection is possible */
> +EXPORT_SYMBOL_GPL(dasd_biodasdinfo);
> diff --git a/include/linux/dasd_mod.h b/include/linux/dasd_mod.h
> new file mode 100644
> index 000000000000..d39abad2ff6e
> --- /dev/null
> +++ b/include/linux/dasd_mod.h
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef DASD_MOD_H
> +#define DASD_MOD_H
> +
> +#include <asm/dasd.h>
> +
> +extern int dasd_biodasdinfo(struct gendisk *disk, dasd_information2_t *info);
> +
> +#endif
> 

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christoph Hellwig]

On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
> 
> On 19.05.20 16:22, Stefan Haberland wrote:
> > The IBM partition parser requires device type specific information only
> > available to the DASD driver to correctly register partitions. The
> > current approach of using ioctl_by_bdev with a fake user space pointer
> > is discouraged.
> > 
> > Fix this by replacing IOCTL calls with direct in-kernel function calls.
> > 
> > Suggested-by: Christoph Hellwig <hch@lst.de>
> > Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
> > Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
> > Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
> 
> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.

What are the symptoms?

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christian Borntraeger]

On 07.10.20 12:39, Christoph Hellwig wrote:
> On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
>>
>> On 19.05.20 16:22, Stefan Haberland wrote:
>>> The IBM partition parser requires device type specific information only
>>> available to the DASD driver to correctly register partitions. The
>>> current approach of using ioctl_by_bdev with a fake user space pointer
>>> is discouraged.
>>>
>>> Fix this by replacing IOCTL calls with direct in-kernel function calls.
>>>
>>> Suggested-by: Christoph Hellwig <hch@lst.de>
>>> Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
>>> Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
>>> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
>>
>> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.
> 
> What are the symptoms?

During boot I normally have
 
[    0.930231] virtio_blk virtio1: [vda] 5409180 4096-byte logical blocks (22.2 GB/20.6 GiB)
[    0.930233] vda: detected capacity change from 0 to 22156001280
[    0.932806]  vda:VOL1/  0X3333: vda1 vda2 vda3

With this change, the last line is no longer there (if CONFIG_DASD=m) and this also 
reflects itself in /proc/partitions. The partitions are no longer detected.

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Stefan Haberland]

Am 07.10.20 um 12:44 schrieb Christian Borntraeger:
>
> On 07.10.20 12:39, Christoph Hellwig wrote:
>> On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
>>> On 19.05.20 16:22, Stefan Haberland wrote:
>>>> The IBM partition parser requires device type specific information only
>>>> available to the DASD driver to correctly register partitions. The
>>>> current approach of using ioctl_by_bdev with a fake user space pointer
>>>> is discouraged.
>>>>
>>>> Fix this by replacing IOCTL calls with direct in-kernel function calls.
>>>>
>>>> Suggested-by: Christoph Hellwig <hch@lst.de>
>>>> Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
>>>> Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
>>>> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
>>> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.
>> What are the symptoms?
> During boot I normally have
>  
> [    0.930231] virtio_blk virtio1: [vda] 5409180 4096-byte logical blocks (22.2 GB/20.6 GiB)
> [    0.930233] vda: detected capacity change from 0 to 22156001280
> [    0.932806]  vda:VOL1/  0X3333: vda1 vda2 vda3
>
> With this change, the last line is no longer there (if CONFIG_DASD=m) and this also 
> reflects itself in /proc/partitions. The partitions are no longer detected.

OK, looks like the module is not loaded and with

        fn = symbol_get(dasd_biodasdinfo);
        if (!fn)
                goto out_exit;

the ibm.c partition detection aborts.

Solution could be not to exit in this case but jump to the probing
process. I will have a closer look at this.

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christoph Hellwig]

On Wed, Oct 07, 2020 at 12:44:55PM +0200, Christian Borntraeger wrote:
> 
> 
> On 07.10.20 12:39, Christoph Hellwig wrote:
> > On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
> >>
> >> On 19.05.20 16:22, Stefan Haberland wrote:
> >>> The IBM partition parser requires device type specific information only
> >>> available to the DASD driver to correctly register partitions. The
> >>> current approach of using ioctl_by_bdev with a fake user space pointer
> >>> is discouraged.
> >>>
> >>> Fix this by replacing IOCTL calls with direct in-kernel function calls.
> >>>
> >>> Suggested-by: Christoph Hellwig <hch@lst.de>
> >>> Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
> >>> Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
> >>> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
> >>
> >> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.
> > 
> > What are the symptoms?
> 
> During boot I normally have

> [    0.930231] virtio_blk virtio1: [vda] 5409180 4096-byte logical blocks (22.2 GB/20.6 GiB)
> [    0.930233] vda: detected capacity change from 0 to 22156001280
> [    0.932806]  vda:VOL1/  0X3333: vda1 vda2 vda3
> 
> With this change, the last line is no longer there (if CONFIG_DASD=m) and this also 
> reflects itself in /proc/partitions. The partitions are no longer detected.

Can you try this patch?

diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
index d6e18df9c53c6d..d91cee558ce67a 100644
--- a/block/partitions/ibm.c
+++ b/block/partitions/ibm.c
@@ -305,8 +305,6 @@ int ibm_partition(struct parsed_partitions *state)
 	if (!disk->fops->getgeo)
 		goto out_exit;
 	fn = symbol_get(dasd_biodasdinfo);
-	if (!fn)
-		goto out_exit;
 	blocksize = bdev_logical_block_size(bdev);
 	if (blocksize <= 0)
 		goto out_symbol;
@@ -326,7 +324,7 @@ int ibm_partition(struct parsed_partitions *state)
 	geo->start = get_start_sect(bdev);
 	if (disk->fops->getgeo(bdev, geo))
 		goto out_freeall;
-	if (fn(disk, info)) {
+	if (!fn || fn(disk, info)) {
 		kfree(info);
 		info = NULL;
 	}

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christian Borntraeger]

On 07.10.20 14:00, Christoph Hellwig wrote:
> On Wed, Oct 07, 2020 at 12:44:55PM +0200, Christian Borntraeger wrote:
>>
>>
>> On 07.10.20 12:39, Christoph Hellwig wrote:
>>> On Wed, Oct 07, 2020 at 11:34:17AM +0200, Christian Borntraeger wrote:
>>>>
>>>> On 19.05.20 16:22, Stefan Haberland wrote:
>>>>> The IBM partition parser requires device type specific information only
>>>>> available to the DASD driver to correctly register partitions. The
>>>>> current approach of using ioctl_by_bdev with a fake user space pointer
>>>>> is discouraged.
>>>>>
>>>>> Fix this by replacing IOCTL calls with direct in-kernel function calls.
>>>>>
>>>>> Suggested-by: Christoph Hellwig <hch@lst.de>
>>>>> Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
>>>>> Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
>>>>> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
>>>>
>>>> FWIW, this broken the ibm-partition code for virtio-blk, when CONFIG_DASD=m.
>>>
>>> What are the symptoms?
>>
>> During boot I normally have
> 
>> [    0.930231] virtio_blk virtio1: [vda] 5409180 4096-byte logical blocks (22.2 GB/20.6 GiB)
>> [    0.930233] vda: detected capacity change from 0 to 22156001280
>> [    0.932806]  vda:VOL1/  0X3333: vda1 vda2 vda3
>>
>> With this change, the last line is no longer there (if CONFIG_DASD=m) and this also 
>> reflects itself in /proc/partitions. The partitions are no longer detected.
> 
> Can you try this patch?


> 
> diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
> index d6e18df9c53c6d..d91cee558ce67a 100644
> --- a/block/partitions/ibm.c
> +++ b/block/partitions/ibm.c
> @@ -305,8 +305,6 @@ int ibm_partition(struct parsed_partitions *state)
>  	if (!disk->fops->getgeo)
>  		goto out_exit;
>  	fn = symbol_get(dasd_biodasdinfo);
> -	if (!fn)
> -		goto out_exit;
>  	blocksize = bdev_logical_block_size(bdev);
>  	if (blocksize <= 0)
>  		goto out_symbol;
> @@ -326,7 +324,7 @@ int ibm_partition(struct parsed_partitions *state)
>  	geo->start = get_start_sect(bdev);
>  	if (disk->fops->getgeo(bdev, geo))
>  		goto out_freeall;
> -	if (fn(disk, info)) {
> +	if (!fn || fn(disk, info)) {
>  		kfree(info);
>  		info = NULL;
>  	}
> 

Unfortunately not. On insmodding virtio_blk I do get:
[    3.331256] vda: detected capacity change from 0 to 22156001280
[    3.332381] ------------[ cut here ]------------
[    3.332382] kernel BUG at kernel/module.c:1081!
[    3.332420] monitor event: 0040 ilc:2 [#1] SMP 
[    3.332422] Modules linked in: virtio_blk(+) kvm
[    3.332425] CPU: 0 PID: 136 Comm: insmod Not tainted 5.8.13+ #54
[    3.332425] Hardware name: IBM 3906 M04 704 (KVM/Linux)
[    3.332426] Krnl PSW : 0704c00180000000 0000000016cf4fc6 (__symbol_put+0x56/0x58)
[    3.332434]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
[    3.332435] Krnl GPRS: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
[    3.332436]            0000000000000000 0000000000000018 0000000000000000 0000000000000098
[    3.332437]            0000000000000000 0000000000000001 0000000000000000 0000000004fd9180
[    3.332438]            000000001f70c000 0000000004fd9360 0000000016cf4fa2 000003e0000f7648
[    3.332445] Krnl Code: 0000000016cf4fb8: f0a8000407fe	srp	4(11,%r0),2046,8
[    3.332445]            0000000016cf4fbe: 47000700		bc	0,1792
[    3.332445]           #0000000016cf4fc2: af000000		mc	0,0
[    3.332445]           >0000000016cf4fc6: 0707		bcr	0,%r7
[    3.332445]            0000000016cf4fc8: c00400000000	brcl	0,0000000016cf4fc8
[    3.332445]            0000000016cf4fce: eb6ff0480024	stmg	%r6,%r15,72(%r15)
[    3.332445]            0000000016cf4fd4: b90400ef		lgr	%r14,%r15
[    3.332445]            0000000016cf4fd8: b90400b4		lgr	%r11,%r4
[    3.332454] Call Trace:
[    3.332456]  [<0000000016cf4fc6>] __symbol_put+0x56/0x58 
[    3.332458] ([<0000000016cf4fa2>] __symbol_put+0x32/0x58)
[    3.332462]  [<00000000171be268>] ibm_partition+0xa0/0xa28 
[    3.332464]  [<00000000171b952c>] blk_add_partitions+0x184/0x5b8 
[    3.332467]  [<0000000016f07e94>] bdev_disk_changed+0x8c/0x120 
[    3.332468]  [<0000000016f09872>] __blkdev_get+0x3fa/0x598 
[    3.332469]  [<0000000016f09a42>] blkdev_get+0x32/0x1c8 
[    3.332471]  [<00000000171b5ee4>] __device_add_disk+0x32c/0x510 
[    3.332473]  [<000003ff80068de0>] virtblk_probe+0x5f0/0xc30 [virtio_blk] 
[    3.332477]  [<00000000172cc110>] virtio_dev_probe+0x178/0x2a0 
[    3.332480]  [<000000001731cecc>] really_probe+0xf4/0x498 
[    3.332481]  [<000000001731da1a>] device_driver_attach+0xd2/0xd8 
[    3.332482]  [<000000001731dad8>] __driver_attach+0xb8/0x180 
[    3.332483]  [<000000001731a1e2>] bus_for_each_dev+0x82/0xb8 
[    3.332484]  [<000000001731bf66>] bus_add_driver+0x1fe/0x248 
[    3.332486]  [<000000001731e340>] driver_register+0xa0/0x168 
[    3.332487]  [<000003ff8006e068>] init+0x68/0x1000 [virtio_blk] 
[    3.332489]  [<0000000016bfc884>] do_one_initcall+0x3c/0x1f8 
[    3.332490]  [<0000000016cf6c98>] do_init_module+0x68/0x290 
[    3.332491]  [<0000000016cf9eec>] __do_sys_finit_module+0xa4/0xe8 
[    3.332494]  [<000000001766c760>] system_call+0xdc/0x2b0 
[    3.332495] Last Breaking-Event-Address:
[    3.332496]  [<0000000016cf4fa6>] __symbol_put+0x36/0x58
[    3.332498] ---[ end trace 4a4a7a5643aab422 ]---

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christoph Hellwig]

On Wed, Oct 07, 2020 at 02:09:18PM +0200, Christian Borntraeger wrote:
> Unfortunately not. On insmodding virtio_blk I do get:

Yeah, the symbol_put needs to be conditional as well.  New version below:

diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
index d6e18df9c53c6d..4b044e620d3534 100644
--- a/block/partitions/ibm.c
+++ b/block/partitions/ibm.c
@@ -305,8 +305,6 @@ int ibm_partition(struct parsed_partitions *state)
 	if (!disk->fops->getgeo)
 		goto out_exit;
 	fn = symbol_get(dasd_biodasdinfo);
-	if (!fn)
-		goto out_exit;
 	blocksize = bdev_logical_block_size(bdev);
 	if (blocksize <= 0)
 		goto out_symbol;
@@ -326,7 +324,7 @@ int ibm_partition(struct parsed_partitions *state)
 	geo->start = get_start_sect(bdev);
 	if (disk->fops->getgeo(bdev, geo))
 		goto out_freeall;
-	if (fn(disk, info)) {
+	if (!fn || fn(disk, info)) {
 		kfree(info);
 		info = NULL;
 	}
@@ -370,7 +368,8 @@ int ibm_partition(struct parsed_partitions *state)
 out_nogeo:
 	kfree(info);
 out_symbol:
-	symbol_put(dasd_biodasdinfo);
+	if (fn)
+		symbol_put(dasd_biodasdinfo);
 out_exit:
 	return res;
 }

Re: [PATCH v4 2/2] s390/dasd: remove ioctl_by_bdev calls

[Christian Borntraeger]

On 07.10.20 14:14, Christoph Hellwig wrote:
> On Wed, Oct 07, 2020 at 02:09:18PM +0200, Christian Borntraeger wrote:
>> Unfortunately not. On insmodding virtio_blk I do get:
> 
> Yeah, the symbol_put needs to be conditional as well.  New version below:

Yes, this works.
> 
> diff --git a/block/partitions/ibm.c b/block/partitions/ibm.c
> index d6e18df9c53c6d..4b044e620d3534 100644
> --- a/block/partitions/ibm.c
> +++ b/block/partitions/ibm.c
> @@ -305,8 +305,6 @@ int ibm_partition(struct parsed_partitions *state)
>  	if (!disk->fops->getgeo)
>  		goto out_exit;
>  	fn = symbol_get(dasd_biodasdinfo);
> -	if (!fn)
> -		goto out_exit;
>  	blocksize = bdev_logical_block_size(bdev);
>  	if (blocksize <= 0)
>  		goto out_symbol;
> @@ -326,7 +324,7 @@ int ibm_partition(struct parsed_partitions *state)
>  	geo->start = get_start_sect(bdev);
>  	if (disk->fops->getgeo(bdev, geo))
>  		goto out_freeall;
> -	if (fn(disk, info)) {
> +	if (!fn || fn(disk, info)) {
>  		kfree(info);
>  		info = NULL;
>  	}
> @@ -370,7 +368,8 @@ int ibm_partition(struct parsed_partitions *state)
>  out_nogeo:
>  	kfree(info);
>  out_symbol:
> -	symbol_put(dasd_biodasdinfo);
> +	if (fn)
> +		symbol_put(dasd_biodasdinfo);
>  out_exit:
>  	return res;
>  }
>