s390/dasd: Move device name formatting into separate function

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 3e1a7ff8a0a7 ("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>

diff --git a/drivers/s390/block/dasd_genhd.c b/drivers/s390/block/dasd_genhd.c
index 28e92fad0ca1f9bf53533f0e0da7a41c7a42586d..6ee3d952412e629c890d370b53d897bd27f4cc52 100644 (file)
--- a/drivers/s390/block/dasd_genhd.c
+++ b/drivers/s390/block/dasd_genhd.c
@@ -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);
        }