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

Stefan Haberland
2020-05-19T14:22:59Z

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