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Subject[PATCH] SCSI disk minor number cleaning
Date
Hi,
The following patch cleans up a bit usage of parameters related to
number of minors per disk in the SCSI subsystem. This is a preliminary
patch and it seems to not contain any problematic changes. The full version
of the patch (that allows to succesfully change SCSI_MINOR_SHIFT and use
more/less partitions per disk) is available at

ftp://rudy.mif.pg.gda.pl/pub/People/ankry/patches/scsi-minor/

Both are against 2.4.4-ac9, but the "shorter" one can be applied to
2.4.5-pre series as well.

Any comments are welcome.

Andrzej

******************************************************************
diff -uNr linux-2.4.4-ac9/drivers/scsi/sd.c linux-scsi/drivers/scsi/sd.c
--- linux-2.4.4-ac9/drivers/scsi/sd.c Thu May 3 19:29:16 2001
+++ linux-scsi/drivers/scsi/sd.c Tue May 15 22:21:01 2001
@@ -50,6 +50,7 @@
#include <asm/io.h>

#define MAJOR_NR SCSI_DISK0_MAJOR
+#include <linux/scsi_minor.h>
#include <linux/blk.h>
#include <linux/blkpg.h>
#include "scsi.h"
@@ -67,11 +68,12 @@

#define SD_MAJOR(i) (!(i) ? SCSI_DISK0_MAJOR : SCSI_DISK1_MAJOR-1+(i))

-#define SCSI_DISKS_PER_MAJOR 16
+#define SCSI_MINOR_SHIFT 4
+#define SCSI_DISKS_PER_MAJOR (1 << (8 - SCSI_MINOR_SHIFT))
#define SD_MAJOR_NUMBER(i) SD_MAJOR((i) >> 8)
#define SD_MINOR_NUMBER(i) ((i) & 255)
#define MKDEV_SD_PARTITION(i) MKDEV(SD_MAJOR_NUMBER(i), (i) & 255)
-#define MKDEV_SD(index) MKDEV_SD_PARTITION((index) << 4)
+#define MKDEV_SD(index) MKDEV_SD_PARTITION((index) << SCSI_MINOR_SHIFT)
#define N_USED_SCSI_DISKS (sd_template.dev_max + SCSI_DISKS_PER_MAJOR - 1)
#define N_USED_SD_MAJORS (N_USED_SCSI_DISKS / SCSI_DISKS_PER_MAJOR)

@@ -298,7 +300,7 @@
SCSI_LOG_HLQUEUE(1, printk("Doing sd request, dev = %d, block = %d\n", devm, block));

dpnt = &rscsi_disks[dev];
- if (devm >= (sd_template.dev_max << 4) ||
+ if (devm >= (sd_template.dev_max << SCSI_MINOR_SHIFT) ||
!dpnt ||
!dpnt->device->online ||
block + SCpnt->request.nr_sectors > sd[devm].nr_sects) {
@@ -563,8 +565,8 @@
{
SCSI_DISK0_MAJOR, /* Major number */
"sd", /* Major name */
- 4, /* Bits to shift to get real from partition */
- 1 << 4, /* Number of partitions per real */
+ SCSI_MINOR_SHIFT, /* Bits to shift to get real from partition */
+ 1 << SCSI_MINOR_SHIFT, /* Number of partitions per real */
NULL, /* hd struct */
NULL, /* block sizes */
0, /* number */
@@ -951,7 +953,7 @@
* The disk reading code does not allow for reading
* of partial sectors.
*/
- for (m = i << 4; m < ((i + 1) << 4); m++) {
+ for (m = i << SCSI_MINOR_SHIFT; m < ((i + 1) << SCSI_MINOR_SHIFT); m++) {
sd_blocksizes[m] = sector_size;
}
} {
@@ -964,8 +966,11 @@
int hard_sector = sector_size;
int sz = rscsi_disks[i].capacity * (hard_sector/256);

- /* There are 16 minors allocated for each major device */
- for (m = i << 4; m < ((i + 1) << 4); m++) {
+ /*
+ * There are 1<<SCSI_MINOR_SHIFT minors allocated
+ * for each major device
+ */
+ for (m = i << SCSI_MINOR_SHIFT; m < ((i + 1) << SCSI_MINOR_SHIFT); m++) {
sd_hardsizes[m] = hard_sector;
}

@@ -1083,34 +1088,34 @@
memset(rscsi_disks, 0, sd_template.dev_max * sizeof(Scsi_Disk));

/* for every (necessary) major: */
- sd_sizes = kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);
+ sd_sizes = kmalloc((sd_template.dev_max << SCSI_MINOR_SHIFT) * sizeof(int), GFP_ATOMIC);
if (!sd_sizes)
goto cleanup_disks;
- memset(sd_sizes, 0, (sd_template.dev_max << 4) * sizeof(int));
+ memset(sd_sizes, 0, (sd_template.dev_max << SCSI_MINOR_SHIFT) * sizeof(int));

- sd_blocksizes = kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);
+ sd_blocksizes = kmalloc((sd_template.dev_max << SCSI_MINOR_SHIFT) * sizeof(int), GFP_ATOMIC);
if (!sd_blocksizes)
goto cleanup_sizes;

- sd_hardsizes = kmalloc((sd_template.dev_max << 4) * sizeof(int), GFP_ATOMIC);
+ sd_hardsizes = kmalloc((sd_template.dev_max << SCSI_MINOR_SHIFT) * sizeof(int), GFP_ATOMIC);
if (!sd_hardsizes)
goto cleanup_blocksizes;

- for (i = 0; i < sd_template.dev_max << 4; i++) {
+ for (i = 0; i < sd_template.dev_max << SCSI_MINOR_SHIFT; i++) {
sd_blocksizes[i] = 1024;
sd_hardsizes[i] = 512;
}

for (i = 0; i < N_USED_SD_MAJORS; i++) {
- blksize_size[SD_MAJOR(i)] = sd_blocksizes + i * (SCSI_DISKS_PER_MAJOR << 4);
- hardsect_size[SD_MAJOR(i)] = sd_hardsizes + i * (SCSI_DISKS_PER_MAJOR << 4);
+ blksize_size[SD_MAJOR(i)] = sd_blocksizes + i * (SCSI_DISKS_PER_MAJOR << SCSI_MINOR_SHIFT);
+ hardsect_size[SD_MAJOR(i)] = sd_hardsizes + i * (SCSI_DISKS_PER_MAJOR << SCSI_MINOR_SHIFT);
}
- sd = kmalloc((sd_template.dev_max << 4) *
+ sd = kmalloc((sd_template.dev_max << SCSI_MINOR_SHIFT) *
sizeof(struct hd_struct),
GFP_ATOMIC);
if (!sd)
goto cleanup_sd;
- memset(sd, 0, (sd_template.dev_max << 4) * sizeof(struct hd_struct));
+ memset(sd, 0, (sd_template.dev_max << SCSI_MINOR_SHIFT) * sizeof(struct hd_struct));

if (N_USED_SD_MAJORS > 1)
sd_gendisks = kmalloc(N_USED_SD_MAJORS * sizeof(struct gendisk), GFP_ATOMIC);
@@ -1132,10 +1137,10 @@
SCSI_DISKS_PER_MAJOR * sizeof *sd_gendisks[i].flags);
sd_gendisks[i].major = SD_MAJOR(i);
sd_gendisks[i].major_name = "sd";
- sd_gendisks[i].minor_shift = 4;
- sd_gendisks[i].max_p = 1 << 4;
- sd_gendisks[i].part = sd + (i * SCSI_DISKS_PER_MAJOR << 4);
- sd_gendisks[i].sizes = sd_sizes + (i * SCSI_DISKS_PER_MAJOR << 4);
+ sd_gendisks[i].minor_shift = SCSI_MINOR_SHIFT;
+ sd_gendisks[i].max_p = 1 << SCSI_MINOR_SHIFT;
+ sd_gendisks[i].part = sd + (i * SCSI_DISKS_PER_MAJOR << SCSI_MINOR_SHIFT);
+ sd_gendisks[i].sizes = sd_sizes + (i * SCSI_DISKS_PER_MAJOR << SCSI_MINOR_SHIFT);
sd_gendisks[i].nr_real = 0;
sd_gendisks[i].next = sd_gendisks + i + 1;
sd_gendisks[i].real_devices =
@@ -1191,9 +1196,9 @@
if (!rscsi_disks[i].capacity && rscsi_disks[i].device) {
sd_init_onedisk(i);
if (!rscsi_disks[i].has_part_table) {
- sd_sizes[i << 4] = rscsi_disks[i].capacity;
+ sd_sizes[i << SCSI_MINOR_SHIFT] = rscsi_disks[i].capacity;
register_disk(&SD_GENDISK(i), MKDEV_SD(i),
- 1<<4, &sd_fops,
+ 1 << SCSI_MINOR_SHIFT, &sd_fops,
rscsi_disks[i].capacity);
rscsi_disks[i].has_part_table = 1;
}
@@ -1312,7 +1317,7 @@
#endif

grok_partitions(&SD_GENDISK(target), target % SCSI_DISKS_PER_MAJOR,
- 1<<4, CAPACITY);
+ 1 << SCSI_MINOR_SHIFT, CAPACITY);

DEVICE_BUSY = 0;
return 0;

--
=======================================================================
Andrzej M. Krzysztofowicz ankry@mif.pg.gda.pl
phone (48)(58) 347 14 61
Faculty of Applied Phys. & Math., Technical University of Gdansk
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