[PATCH] scsi_debug: Runtime-configurable sector size

["Martin K. Petersen" <martin.petersen@oracle.com>]

Make scsi_debug sector size configurable at load time instead of being
a #define.  Handy for testing 4KB sectors.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

---

diff -r b1f69dded4b8 drivers/scsi/scsi_debug.c
--- a/drivers/scsi/scsi_debug.c	Wed Apr 30 15:41:26 2008 -0400
+++ b/drivers/scsi/scsi_debug.c	Wed Apr 30 16:08:12 2008 -0400
@@ -94,6 +94,7 @@
 #define DEF_VIRTUAL_GB   0
 #define DEF_FAKE_RW	0
 #define DEF_VPD_USE_HOSTNO 1
+#define DEF_SECTOR_SIZE 512
 
 /* bit mask values for scsi_debug_opts */
 #define SCSI_DEBUG_OPT_NOISE   1
@@ -142,6 +143,7 @@
 static int scsi_debug_virtual_gb = DEF_VIRTUAL_GB;
 static int scsi_debug_fake_rw = DEF_FAKE_RW;
 static int scsi_debug_vpd_use_hostno = DEF_VPD_USE_HOSTNO;
+static int scsi_debug_sector_size = DEF_SECTOR_SIZE;
 
 static int scsi_debug_cmnd_count = 0;
 
@@ -156,11 +158,6 @@
 static int sdebug_heads;		/* heads per disk */
 static int sdebug_cylinders_per;	/* cylinders per surface */
 static int sdebug_sectors_per;		/* sectors per cylinder */
-
-/* default sector size is 512 bytes, 2**9 bytes */
-#define POW2_SECT_SIZE 9
-#define SECT_SIZE (1 << POW2_SECT_SIZE)
-#define SECT_SIZE_PER(TGT) SECT_SIZE
 
 #define SDEBUG_MAX_PARTS 4
 
@@ -878,8 +875,8 @@
 		arr[2] = 0xff;
 		arr[3] = 0xff;
 	}
-	arr[6] = (SECT_SIZE_PER(target) >> 8) & 0xff;
-	arr[7] = SECT_SIZE_PER(target) & 0xff;
+	arr[6] = (scsi_debug_sector_size >> 8) & 0xff;
+	arr[7] = scsi_debug_sector_size & 0xff;
 	return fill_from_dev_buffer(scp, arr, SDEBUG_READCAP_ARR_SZ);
 }
 
@@ -902,10 +899,10 @@
 	capac = sdebug_capacity - 1;
 	for (k = 0; k < 8; ++k, capac >>= 8)
 		arr[7 - k] = capac & 0xff;
-	arr[8] = (SECT_SIZE_PER(target) >> 24) & 0xff;
-	arr[9] = (SECT_SIZE_PER(target) >> 16) & 0xff;
-	arr[10] = (SECT_SIZE_PER(target) >> 8) & 0xff;
-	arr[11] = SECT_SIZE_PER(target) & 0xff;
+	arr[8] = (scsi_debug_sector_size >> 24) & 0xff;
+	arr[9] = (scsi_debug_sector_size >> 16) & 0xff;
+	arr[10] = (scsi_debug_sector_size >> 8) & 0xff;
+	arr[11] = scsi_debug_sector_size & 0xff;
 	return fill_from_dev_buffer(scp, arr,
 				    min(alloc_len, SDEBUG_READCAP16_ARR_SZ));
 }
@@ -1026,8 +1023,8 @@
         memcpy(p, format_pg, sizeof(format_pg));
         p[10] = (sdebug_sectors_per >> 8) & 0xff;
         p[11] = sdebug_sectors_per & 0xff;
-        p[12] = (SECT_SIZE >> 8) & 0xff;
-        p[13] = SECT_SIZE & 0xff;
+        p[12] = (scsi_debug_sector_size >> 8) & 0xff;
+        p[13] = scsi_debug_sector_size & 0xff;
         if (DEV_REMOVEABLE(target))
                 p[20] |= 0x20; /* should agree with INQUIRY */
         if (1 == pcontrol)
@@ -1206,8 +1203,8 @@
 			ap[2] = (sdebug_capacity >> 8) & 0xff;
 			ap[3] = sdebug_capacity & 0xff;
 		}
-        	ap[6] = (SECT_SIZE_PER(target) >> 8) & 0xff;
-        	ap[7] = SECT_SIZE_PER(target) & 0xff;
+        	ap[6] = (scsi_debug_sector_size >> 8) & 0xff;
+        	ap[7] = scsi_debug_sector_size & 0xff;
 		offset += bd_len;
 		ap = arr + offset;
 	} else if (16 == bd_len) {
@@ -1215,10 +1212,10 @@
 
         	for (k = 0; k < 8; ++k, capac >>= 8)
                 	ap[7 - k] = capac & 0xff;
-        	ap[12] = (SECT_SIZE_PER(target) >> 24) & 0xff;
-        	ap[13] = (SECT_SIZE_PER(target) >> 16) & 0xff;
-        	ap[14] = (SECT_SIZE_PER(target) >> 8) & 0xff;
-        	ap[15] = SECT_SIZE_PER(target) & 0xff;
+        	ap[12] = (scsi_debug_sector_size >> 24) & 0xff;
+        	ap[13] = (scsi_debug_sector_size >> 16) & 0xff;
+        	ap[14] = (scsi_debug_sector_size >> 8) & 0xff;
+        	ap[15] = scsi_debug_sector_size & 0xff;
 		offset += bd_len;
 		ap = arr + offset;
 	}
@@ -1519,10 +1516,10 @@
 	if (block + num > sdebug_store_sectors)
 		rest = block + num - sdebug_store_sectors;
 
-	ret = func(scmd, fake_storep + (block * SECT_SIZE),
-		   (num - rest) * SECT_SIZE);
+	ret = func(scmd, fake_storep + (block * scsi_debug_sector_size),
+		   (num - rest) * scsi_debug_sector_size);
 	if (!ret && rest)
-		ret = func(scmd, fake_storep, rest * SECT_SIZE);
+		ret = func(scmd, fake_storep, rest * scsi_debug_sector_size);
 
 	return ret;
 }
@@ -1575,10 +1572,10 @@
 	write_unlock_irqrestore(&atomic_rw, iflags);
 	if (-1 == ret)
 		return (DID_ERROR << 16);
-	else if ((ret < (num * SECT_SIZE)) &&
+	else if ((ret < (num * scsi_debug_sector_size)) &&
 		 (SCSI_DEBUG_OPT_NOISE & scsi_debug_opts))
 		printk(KERN_INFO "scsi_debug: write: cdb indicated=%u, "
-		       " IO sent=%d bytes\n", num * SECT_SIZE, ret);
+		       " IO sent=%d bytes\n", num * scsi_debug_sector_size, ret);
 	return 0;
 }
 
@@ -2085,6 +2082,7 @@
 module_param_named(virtual_gb, scsi_debug_virtual_gb, int, S_IRUGO | S_IWUSR);
 module_param_named(vpd_use_hostno, scsi_debug_vpd_use_hostno, int,
 		   S_IRUGO | S_IWUSR);
+module_param_named(sector_size, scsi_debug_sector_size, int, S_IRUGO);
 
 MODULE_AUTHOR("Eric Youngdale + Douglas Gilbert");
 MODULE_DESCRIPTION("SCSI debug adapter driver");
@@ -2106,6 +2104,7 @@
 MODULE_PARM_DESC(scsi_level, "SCSI level to simulate(def=5[SPC-3])");
 MODULE_PARM_DESC(virtual_gb, "virtual gigabyte size (def=0 -> use dev_size_mb)");
 MODULE_PARM_DESC(vpd_use_hostno, "0 -> dev ids ignore hostno (def=1 -> unique dev ids)");
+MODULE_PARM_DESC(sector_size, "hardware sector size in bytes (def=512)");
 
 
 static char sdebug_info[256];
@@ -2158,8 +2157,9 @@
 	    scsi_debug_dev_size_mb, scsi_debug_opts, scsi_debug_every_nth,
 	    scsi_debug_cmnd_count, scsi_debug_delay,
 	    scsi_debug_max_luns, scsi_debug_scsi_level,
-	    SECT_SIZE, sdebug_cylinders_per, sdebug_heads, sdebug_sectors_per,
-	    num_aborts, num_dev_resets, num_bus_resets, num_host_resets);
+	    scsi_debug_sector_size, sdebug_cylinders_per, sdebug_heads,
+	    sdebug_sectors_per, num_aborts, num_dev_resets, num_bus_resets,
+	    num_host_resets);
 	if (pos < offset) {
 		len = 0;
 		begin = pos;
@@ -2434,6 +2434,12 @@
 DRIVER_ATTR(vpd_use_hostno, S_IRUGO | S_IWUSR, sdebug_vpd_use_hostno_show,
 	    sdebug_vpd_use_hostno_store);
 
+static ssize_t sdebug_sector_size_show(struct device_driver * ddp, char * buf)
+{
+	return scnprintf(buf, PAGE_SIZE, "%u\n", scsi_debug_sector_size);
+}
+DRIVER_ATTR(sector_size, S_IRUGO, sdebug_sector_size_show, NULL);
+
 /* Note: The following function creates attribute files in the
    /sys/bus/pseudo/drivers/scsi_debug directory. The advantage of these
    files (over those found in the /sys/module/scsi_debug/parameters
@@ -2459,11 +2465,13 @@
 	ret |= driver_create_file(&sdebug_driverfs_driver, &driver_attr_scsi_level);
 	ret |= driver_create_file(&sdebug_driverfs_driver, &driver_attr_virtual_gb);
 	ret |= driver_create_file(&sdebug_driverfs_driver, &driver_attr_vpd_use_hostno);
+	ret |= driver_create_file(&sdebug_driverfs_driver, &driver_attr_sector_size);
 	return ret;
 }
 
 static void do_remove_driverfs_files(void)
 {
+	driver_remove_file(&sdebug_driverfs_driver, &driver_attr_sector_size);
 	driver_remove_file(&sdebug_driverfs_driver, &driver_attr_vpd_use_hostno);
 	driver_remove_file(&sdebug_driverfs_driver, &driver_attr_virtual_gb);
 	driver_remove_file(&sdebug_driverfs_driver, &driver_attr_scsi_level);
@@ -2499,10 +2507,22 @@
 	int k;
 	int ret;
 
+	switch (scsi_debug_sector_size) {
+	case  512:
+	case 1024:
+	case 2048:
+	case 4096:
+		break;
+	default:
+		printk(KERN_ERR "scsi_debug_init: invalid sector_size %u\n",
+		       scsi_debug_sector_size);
+		return -EINVAL;
+	}
+
 	if (scsi_debug_dev_size_mb < 1)
 		scsi_debug_dev_size_mb = 1;  /* force minimum 1 MB ramdisk */
 	sz = (unsigned long)scsi_debug_dev_size_mb * 1048576;
-	sdebug_store_sectors = sz / SECT_SIZE;
+	sdebug_store_sectors = sz / scsi_debug_sector_size;
 	sdebug_capacity = get_sdebug_capacity();
 
 	/* play around with geometry, don't waste too much on track 0 */