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s390/dasd: Move device name formatting into separate function

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The device name formatting can be generalized and made more readable
compared to the current state. SCSI already provides a generalized way
to format many devices in the same naming scheme as DASD does, which was
introduced with commit 3e1a7ff8a0 ("block: allow disk to have extended
device number").

Use this much cleaner code from drivers/scsi/sd.c to handle the legacy
naming scheme in DASD as a replacement for the current implementation.

For easier error handling for the new function, move the gendisk free
portion of dasd_gendisk_free() out into a new function dasd_gd_free().

Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jan Höppner 2025-11-26 17:06:33 +01:00 committed by Jens Axboe
parent 764def9e8e
commit 43198756ee
1 changed files with 54 additions and 26 deletions
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80
drivers/s390/block/dasd_genhd.c
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@ -22,6 +22,7 @@
static unsigned int queue_depth = 32;
static unsigned int nr_hw_queues = 4;
static void dasd_gd_free(struct gendisk *gdp);
module_param(queue_depth, uint, 0444);
MODULE_PARM_DESC(queue_depth, "Default queue depth for new DASD devices");
@ -29,6 +30,37 @@ MODULE_PARM_DESC(queue_depth, "Default queue depth for new DASD devices");
module_param(nr_hw_queues, uint, 0444);
MODULE_PARM_DESC(nr_hw_queues, "Default number of hardware queues for new DASD devices");
/*
* Set device name.
* dasda - dasdz : 26 devices
* dasdaa - dasdzz : 676 devices, added up = 702
* dasdaaa - dasdzzz : 17576 devices, added up = 18278
* dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
*/
static int dasd_name_format(char *prefix, int index, char *buf, int buflen)
{
const int base = 'z' - 'a' + 1;
char *begin = buf + strlen(prefix);
char *end = buf + buflen;
char *p;
int unit;
p = end - 1;
*p = '\0';
unit = base;
do {
if (p == begin)
return -EINVAL;
*--p = 'a' + (index % unit);
index = (index / unit) - 1;
} while (index >= 0);
memmove(begin, p, end - p);
memcpy(buf, prefix, strlen(prefix));
return 0;
}
/*
* Allocate and register gendisk structure for device.
*/
@ -45,11 +77,13 @@ int dasd_gendisk_alloc(struct dasd_block *block)
};
struct gendisk *gdp;
struct dasd_device *base;
int len, rc;
unsigned int devindex;
int rc;
/* Make sure the minor for this device exists. */
base = block->base;
if (base->devindex >= DASD_PER_MAJOR)
devindex = base->devindex;
if (devindex >= DASD_PER_MAJOR)
return -EBUSY;
block->tag_set.ops = &dasd_mq_ops;
@ -69,31 +103,17 @@ int dasd_gendisk_alloc(struct dasd_block *block)
/* Initialize gendisk structure. */
gdp->major = DASD_MAJOR;
gdp->first_minor = base->devindex << DASD_PARTN_BITS;
gdp->first_minor = devindex << DASD_PARTN_BITS;
gdp->minors = 1 << DASD_PARTN_BITS;
gdp->fops = &dasd_device_operations;
/*
* Set device name.
* dasda - dasdz : 26 devices
* dasdaa - dasdzz : 676 devices, added up = 702
* dasdaaa - dasdzzz : 17576 devices, added up = 18278
* dasdaaaa - dasdzzzz : 456976 devices, added up = 475252
*/
len = sprintf(gdp->disk_name, "dasd");
if (base->devindex > 25) {
if (base->devindex > 701) {
if (base->devindex > 18277)
len += sprintf(gdp->disk_name + len, "%c",
'a'+(((base->devindex-18278)
/17576)%26));
len += sprintf(gdp->disk_name + len, "%c",
'a'+(((base->devindex-702)/676)%26));
}
len += sprintf(gdp->disk_name + len, "%c",
'a'+(((base->devindex-26)/26)%26));
rc = dasd_name_format("dasd", devindex, gdp->disk_name, sizeof(gdp->disk_name));
if (rc) {
DBF_DEV_EVENT(DBF_ERR, block->base,
"setting disk name failed, rc %d", rc);
dasd_gd_free(gdp);
return rc;
}
len += sprintf(gdp->disk_name + len, "%c", 'a'+(base->devindex%26));
if (base->features & DASD_FEATURE_READONLY ||
test_bit(DASD_FLAG_DEVICE_RO, &base->flags))
@ -111,15 +131,23 @@ int dasd_gendisk_alloc(struct dasd_block *block)
return 0;
}
/*
* Free gendisk structure
*/
static void dasd_gd_free(struct gendisk *gd)
{
del_gendisk(gd);
gd->private_data = NULL;
put_disk(gd);
}
/*
* Unregister and free gendisk structure for device.
*/
void dasd_gendisk_free(struct dasd_block *block)
{
if (block->gdp) {
del_gendisk(block->gdp);
block->gdp->private_data = NULL;
put_disk(block->gdp);
dasd_gd_free(block->gdp);
block->gdp = NULL;
blk_mq_free_tag_set(&block->tag_set);
}