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[RFT] Support for ~2144 SCSI discs

To: linux-kernel@xxxxxxxxxxxxxxx, linux-scsi@xxxxxxxxxxxxxxx
Subject: [RFT] Support for ~2144 SCSI discs
From: Richard Gooch <rgooch@xxxxxxxxxxxxxxx>
Date: Mon, 30 Jul 2001 20:30:40 -0400
Cc: devfs-announce-list@xxxxxxxxxxxxxxxxxxxxxxx
Sender: owner-devfs@xxxxxxxxxxx
  Hi, all. Below is a patch that adds support for large numbers of
SCSI discs (approximately 2144). I'd like people to try this out. I'm
not doing my normal devfs-patch-v??? thing because this is completely
untested (I'm away from my SCSI boxes), and I don't want to put a
possibly FS-corrupting patch on my ftp archive. The code does compile
and link, though.

There are 3 cases I'd like to have tested:
- people with 1 to 16 SCSI discs
- people with 17 to 128 SCSI discs
- people with >128 SCSI discs

because each of these exercises a slightly different setup path.
Please send success or failure reports to me.

REMINDER: be careful with this patch. It could corrupt your FS.

                                Regards,

                                        Richard....
Permanent: rgooch@xxxxxxxxxxxxx
Current:   rgooch@xxxxxxxxxxxxxxx

diff -urN linux-2.4.7/Documentation/Configure.help 
linux/Documentation/Configure.help
--- linux-2.4.7/Documentation/Configure.help    Thu Jul 19 20:48:15 2001
+++ linux/Documentation/Configure.help  Mon Jul 23 01:19:24 2001
@@ -5410,6 +5410,17 @@
   located on a SCSI disk. In this case, do not compile the driver for
   your SCSI host adapter (below) as a module either.
 
+Many SCSI Discs support
+CONFIG_SD_MANY
+  This allows you to support a very large number of SCSI discs
+  (approximately 2144). You will also need to set CONFIG_DEVFS_FS=y
+  later. This option may consume all unassigned block majors
+  (i.e. those which do not have an allocation in
+  Documentation/devices.txt). Enabling this will consume a few extra
+  kilobytes of kernel memory.
+
+  Unless you have a large storage array, say N.
+
 Extra SCSI Disks
 CONFIG_SD_EXTRA_DEVS
   This controls the amount of additional space allocated in tables for
diff -urN linux-2.4.7/Documentation/filesystems/devfs/ChangeLog 
linux/Documentation/filesystems/devfs/ChangeLog
--- linux-2.4.7/Documentation/filesystems/devfs/ChangeLog       Wed Jul 11 
17:55:41 2001
+++ linux/Documentation/filesystems/devfs/ChangeLog     Mon Jul 30 19:13:00 2001
@@ -1675,3 +1675,13 @@
 - Fixed number leak for /dev/cdroms/cdrom%d
 
 - Fixed number leak for /dev/discs/disc%d
+===============================================================================
+Changes for patch v183
+
+- Fixed bug in <devfs_setup> which could hang boot process
+===============================================================================
+Changes for patch v184
+
+- Support large numbers of SCSI discs (~2144)
+
+- Documentation typo fix for fs/devfs/util.c
diff -urN linux-2.4.7/drivers/scsi/Config.in linux/drivers/scsi/Config.in
--- linux-2.4.7/drivers/scsi/Config.in  Thu Jul  5 14:28:16 2001
+++ linux/drivers/scsi/Config.in        Mon Jul 23 01:19:47 2001
@@ -3,7 +3,8 @@
 dep_tristate '  SCSI disk support' CONFIG_BLK_DEV_SD $CONFIG_SCSI
 
 if [ "$CONFIG_BLK_DEV_SD" != "n" ]; then
-   int  'Maximum number of SCSI disks that can be loaded as modules' 
CONFIG_SD_EXTRA_DEVS 40
+   bool '    Many (~2144) SCSI discs support (requires devfs)' CONFIG_SD_MANY
+   int  '    Maximum number of SCSI disks that can be loaded as modules' 
CONFIG_SD_EXTRA_DEVS 40
 fi
 
 dep_tristate '  SCSI tape support' CONFIG_CHR_DEV_ST $CONFIG_SCSI
diff -urN linux-2.4.7/drivers/scsi/hosts.h linux/drivers/scsi/hosts.h
--- linux-2.4.7/drivers/scsi/hosts.h    Fri Jul 20 15:55:46 2001
+++ linux/drivers/scsi/hosts.h  Mon Jul 30 19:20:27 2001
@@ -506,9 +506,8 @@
     const char * tag;
     struct module * module;      /* Used for loadable modules */
     unsigned char scsi_type;
-    unsigned int major;
-    unsigned int min_major;      /* Minimum major in range. */ 
-    unsigned int max_major;      /* Maximum major in range. */
+    unsigned int *majors;         /* Array of majors used by driver */
+    unsigned int num_majors;      /* Number of majors used by driver */
     unsigned int nr_dev;         /* Number currently attached */
     unsigned int dev_noticed;    /* Number of devices detected. */
     unsigned int dev_max;        /* Current size of arrays */
diff -urN linux-2.4.7/drivers/scsi/osst.c linux/drivers/scsi/osst.c
--- linux-2.4.7/drivers/scsi/osst.c     Fri Jul 20 00:18:15 2001
+++ linux/drivers/scsi/osst.c   Mon Jul 30 17:57:27 2001
@@ -160,7 +160,6 @@
        name:           "OnStream tape",
        tag:            "osst",
        scsi_type:      TYPE_TAPE,
-       major:          OSST_MAJOR,
        detect:         osst_detect,
        init:           osst_init,
        attach:         osst_attach,
diff -urN linux-2.4.7/drivers/scsi/scsi_lib.c linux/drivers/scsi/scsi_lib.c
--- linux-2.4.7/drivers/scsi/scsi_lib.c Thu Jul 19 23:48:04 2001
+++ linux/drivers/scsi/scsi_lib.c       Mon Jul 30 17:52:35 2001
@@ -769,25 +769,10 @@
                 * Search for a block device driver that supports this
                 * major.
                 */
-               if (spnt->blk && spnt->major == major) {
-                       return spnt;
-               }
-               /*
-                * I am still not entirely satisfied with this solution,
-                * but it is good enough for now.  Disks have a number of
-                * major numbers associated with them, the primary
-                * 8, which we test above, and a secondary range of 7
-                * different consecutive major numbers.   If this ever
-                * becomes insufficient, then we could add another function
-                * to the structure, and generalize this completely.
-                */
-               if( spnt->min_major != 0 
-                   && spnt->max_major != 0
-                   && major >= spnt->min_major
-                   && major <= spnt->max_major )
-               {
-                       return spnt;
-               }
+               int i;
+               if (!spnt->blk || !spnt->majors) continue;
+               for (i = 0; i < spnt->num_majors; ++i)
+                       if (spnt->majors[i] == major) return spnt;
        }
        return NULL;
 }
diff -urN linux-2.4.7/drivers/scsi/sd.c linux/drivers/scsi/sd.c
--- linux-2.4.7/drivers/scsi/sd.c       Thu Jul  5 14:28:17 2001
+++ linux/drivers/scsi/sd.c     Mon Jul 30 20:10:58 2001
@@ -28,6 +28,8 @@
  *     
  *      Modified by Alex Davis <letmein@xxxxxxxxx>
  *       Fix problem where removable media could be ejected after sd_open.
+ *
+ *       Modified by Richard Gooch rgooch@xxxxxxxxxxxxx to support >128 discs.
  */
 
 #include <linux/config.h>
@@ -65,7 +67,7 @@
  *  static const char RCSid[] = "$Header:";
  */
 
-#define SD_MAJOR(i) (!(i) ? SCSI_DISK0_MAJOR : SCSI_DISK1_MAJOR-1+(i))
+#define SD_MAJOR(i) sd_template.majors[(i)]
 
 #define SCSI_DISKS_PER_MAJOR   16
 #define SD_MAJOR_NUMBER(i)     SD_MAJOR((i) >> 8)
@@ -108,12 +110,6 @@
        name:"disk",
        tag:"sd",
        scsi_type:TYPE_DISK,
-       major:SCSI_DISK0_MAJOR,
-        /*
-         * Secondary range of majors that this driver handles.
-         */
-       min_major:SCSI_DISK1_MAJOR,
-       max_major:SCSI_DISK7_MAJOR,
        blk:1,
        detect:sd_detect,
        init:sd_init,
@@ -123,6 +119,19 @@
        init_command:sd_init_command,
 };
 
+#ifdef CONFIG_SD_MANY
+static inline int sd_devnum_to_index (int devnum)
+{
+    int i, major = MAJOR (devnum);
+
+    for (i = 0; i < sd_template.num_majors; ++i)
+    {
+        if (sd_template.majors[i] != major) continue;
+        return (i << 4) | (MINOR (i) >> 4);
+    }
+    return -ENODEV;
+}
+#endif
 
 static void rw_intr(Scsi_Cmnd * SCpnt);
 
@@ -1043,6 +1052,41 @@
        return i;
 }
 
+static int sd_alloc_majors (void)
+/*  Allocate as many majors as required
+ */
+{
+       int i, major;
+
+       if ( ( sd_template.majors =
+              kmalloc (sizeof sd_template.majors * N_USED_SD_MAJORS,
+                       GFP_ATOMIC) ) == NULL ) {
+               printk ("sd.c: unable to allocate major array\n");
+               return -ENOMEM;
+       }
+       sd_template.majors[0] = SCSI_DISK0_MAJOR;
+       for (i = 1; (i < N_USED_SD_MAJORS) && (i <N_SD_PREASSIGNED_MAJORS);++i)
+               sd_template.majors[i] = SCSI_DISK1_MAJOR + i - 1;
+       for (; (i >= N_SD_PREASSIGNED_MAJORS) && (i < N_USED_SD_MAJORS); ++i) {
+               if ( ( major = devfs_alloc_major (DEVFS_SPECIAL_BLK) ) < 0 )
+                       break;
+               sd_template.majors[i] = major;
+       }
+       sd_template.dev_max = i * SCSI_DISKS_PER_MAJOR;
+       sd_template.num_majors = i;
+       return 0;
+}      /*  End Function sd_alloc_majors  */
+
+static void sd_dealloc_majors (void)
+/*  Deallocate all the allocated majors
+ */
+{
+       int i;
+
+       for (i = sd_template.num_majors - 1; i >= N_SD_PREASSIGNED_MAJORS; --i)
+               devfs_dealloc_major (DEVFS_SPECIAL_BLK, sd_template.majors[i]);
+}      /*  End Function sd_dealloc_majors  */
+
 /*
  * The sd_init() function looks at all SCSI drives present, determines
  * their size, and reads partition table entries for them.
@@ -1057,16 +1101,16 @@
        if (sd_template.dev_noticed == 0)
                return 0;
 
-       if (!rscsi_disks)
+       if (!rscsi_disks) {
                sd_template.dev_max = sd_template.dev_noticed + SD_EXTRA_DEVS;
-
-       if (sd_template.dev_max > N_SD_MAJORS * SCSI_DISKS_PER_MAJOR)
-               sd_template.dev_max = N_SD_MAJORS * SCSI_DISKS_PER_MAJOR;
+               if ( !sd_alloc_majors() ) return 1;
+       }
 
        if (!sd_registered) {
                for (i = 0; i < N_USED_SD_MAJORS; i++) {
                        if (devfs_register_blkdev(SD_MAJOR(i), "sd", &sd_fops)) 
{
                                printk("Unable to get major %d for SCSI 
disk\n", SD_MAJOR(i));
+                               sd_dealloc_majors();
                                return 1;
                        }
                }
@@ -1166,6 +1210,7 @@
        for (i = 0; i < N_USED_SD_MAJORS; i++) {
                devfs_unregister_blkdev(SD_MAJOR(i), "sd");
        }
+       sd_dealloc_majors();
        sd_registered--;
        return 1;
 }
@@ -1373,6 +1418,7 @@
 
        scsi_unregister_module(MODULE_SCSI_DEV, &sd_template);
 
+       sd_dealloc_majors();
        for (i = 0; i < N_USED_SD_MAJORS; i++)
                devfs_unregister_blkdev(SD_MAJOR(i), "sd");
 
diff -urN linux-2.4.7/drivers/scsi/sd.h linux/drivers/scsi/sd.h
--- linux-2.4.7/drivers/scsi/sd.h       Fri Jul 20 15:55:46 2001
+++ linux/drivers/scsi/sd.h     Mon Jul 30 20:09:12 2001
@@ -42,10 +42,14 @@
  */
 extern kdev_t sd_find_target(void *host, int tgt);
 
-#define N_SD_MAJORS    8
+#define N_SD_PREASSIGNED_MAJORS        8
 
+#ifdef CONFIG_SD_MANY
+#define SD_PARTITION(i)                ((sd_devnum_to_index((i)) << 4) | 
((i)&0x0f))
+#else
 #define SD_MAJOR_MASK  (N_SD_MAJORS - 1)
 #define SD_PARTITION(i)                (((MAJOR(i) & SD_MAJOR_MASK) << 8) | 
(MINOR(i) & 255))
+#endif
 
 #endif
 
diff -urN linux-2.4.7/drivers/scsi/sg.c linux/drivers/scsi/sg.c
--- linux-2.4.7/drivers/scsi/sg.c       Wed Jul  4 18:39:28 2001
+++ linux/drivers/scsi/sg.c     Mon Jul 30 17:57:52 2001
@@ -123,7 +123,6 @@
 {
       tag:"sg",
       scsi_type:0xff,
-      major:SCSI_GENERIC_MAJOR,
       detect:sg_detect,
       init:sg_init,
       finish:sg_finish,
diff -urN linux-2.4.7/drivers/scsi/sr.c linux/drivers/scsi/sr.c
--- linux-2.4.7/drivers/scsi/sr.c       Thu Jul  5 14:28:17 2001
+++ linux/drivers/scsi/sr.c     Mon Jul 30 17:59:33 2001
@@ -69,12 +69,15 @@
 
 static int sr_init_command(Scsi_Cmnd *);
 
+static unsigned int sr_major = SCSI_CDROM_MAJOR;
+
 static struct Scsi_Device_Template sr_template =
 {
        name:"cdrom",
        tag:"sr",
        scsi_type:TYPE_ROM,
-       major:SCSI_CDROM_MAJOR,
+       majors:&sr_major,
+       num_majors:1,
        blk:1,
        detect:sr_detect,
        init:sr_init,
diff -urN linux-2.4.7/drivers/scsi/st.c linux/drivers/scsi/st.c
--- linux-2.4.7/drivers/scsi/st.c       Fri Jul 20 00:16:32 2001
+++ linux/drivers/scsi/st.c     Mon Jul 30 17:58:22 2001
@@ -160,7 +160,6 @@
        name:"tape", 
        tag:"st", 
        scsi_type:TYPE_TAPE,
-       major:SCSI_TAPE_MAJOR, 
        detect:st_detect, 
        init:st_init,
        attach:st_attach, 
diff -urN linux-2.4.7/fs/devfs/base.c linux/fs/devfs/base.c
--- linux-2.4.7/fs/devfs/base.c Wed Jul 11 17:55:41 2001
+++ linux/fs/devfs/base.c       Mon Jul 30 19:10:41 2001
@@ -511,6 +511,9 @@
               Removed broken devnum allocation and use <devfs_alloc_devnum>.
               Fixed old devnum leak by calling new <devfs_dealloc_devnum>.
   v0.107
+    20010712   Richard Gooch <rgooch@xxxxxxxxxxxxx>
+              Fixed bug in <devfs_setup> which could hang boot process.
+  v0.108
 */
 #include <linux/types.h>
 #include <linux/errno.h>
@@ -543,7 +546,7 @@
 #include <asm/bitops.h>
 #include <asm/atomic.h>
 
-#define DEVFS_VERSION            "0.107 (20010709)"
+#define DEVFS_VERSION            "0.108 (20010712)"
 
 #define DEVFS_NAME "devfs"
 
@@ -1342,12 +1345,12 @@
            return NULL;
        }
     }
-    de->u.fcb.autogen = 0;
+    de->u.fcb.autogen = FALSE;
     if ( S_ISCHR (mode) || S_ISBLK (mode) )
     {
        de->u.fcb.u.device.major = major;
        de->u.fcb.u.device.minor = minor;
-       de->u.fcb.autogen = (devnum == NODEV) ? 0 : 1;
+       de->u.fcb.autogen = (devnum == NODEV) ? FALSE : TRUE;
     }
     else if ( S_ISREG (mode) ) de->u.fcb.u.file.size = 0;
     else
@@ -1418,7 +1421,7 @@
                                   MKDEV (de->u.fcb.u.device.major,
                                          de->u.fcb.u.device.minor) );
        }
-       de->u.fcb.autogen = 0;
+       de->u.fcb.autogen = FALSE;
        return;
     }
     if (S_ISLNK (de->mode) && de->registered)
@@ -2063,6 +2066,7 @@
        {"show",      OPTION_SHOW,        &boot_options},
        {"only",      OPTION_ONLY,        &boot_options},
        {"mount",     OPTION_MOUNT,       &boot_options},
+       {NULL,        0,                  NULL}
     };
 
     while ( (*str != '\0') && !isspace (*str) )
@@ -2074,7 +2078,7 @@
            invert = 1;
            str += 2;
        }
-       for (i = 0; i < sizeof (devfs_options_tab); i++)
+       for (i = 0; devfs_options_tab[i].name != NULL; i++)
        {
            int len = strlen (devfs_options_tab[i].name);
 
diff -urN linux-2.4.7/fs/devfs/util.c linux/fs/devfs/util.c
--- linux-2.4.7/fs/devfs/util.c Wed Jul 11 17:55:41 2001
+++ linux/fs/devfs/util.c       Mon Jul 30 18:28:12 2001
@@ -39,6 +39,8 @@
                Created <devfs_*alloc_major> and <devfs_*alloc_devnum>.
     20010710   Richard Gooch <rgooch@xxxxxxxxxxxxx>
                Created <devfs_*alloc_unique_number>.
+    20010730   Richard Gooch <rgooch@xxxxxxxxxxxxx>
+               Documentation typo fix.
 */
 #include <linux/module.h>
 #include <linux/init.h>
@@ -214,7 +216,7 @@
 
 /**
  *     devfs_alloc_major - Allocate a major number.
- *     @type: The type of the major (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLOCK)
+ *     @type: The type of the major (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLK)
 
  *     Returns the allocated major, else -1 if none are available.
  *     This routine is thread safe and does not block.
@@ -238,7 +240,7 @@
 
 /**
  *     devfs_dealloc_major - Deallocate a major number.
- *     @type: The type of the major (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLOCK)
+ *     @type: The type of the major (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLK)
  *     @major: The major number.
  *     This routine is thread safe and does not block.
  */
@@ -282,7 +284,7 @@
 
 /**
  *     devfs_alloc_devnum - Allocate a device number.
- *     @type: The type (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLOCK).
+ *     @type: The type (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLK).
  *
  *     Returns the allocated device number, else NODEV if none are available.
  *     This routine is thread safe and may block.
@@ -347,7 +349,7 @@
 
 /**
  *     devfs_dealloc_devnum - Dellocate a device number.
- *     @type: The type (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLOCK).
+ *     @type: The type (DEVFS_SPECIAL_CHR or DEVFS_SPECIAL_BLK).
  *     @devnum: The device number.
  *
  *     This routine is thread safe and does not block.
diff -urN linux-2.4.7/include/linux/blk.h linux/include/linux/blk.h
--- linux-2.4.7/include/linux/blk.h     Mon Jul 30 19:20:01 2001
+++ linux/include/linux/blk.h   Mon Jul 30 20:05:18 2001
@@ -144,7 +144,11 @@
 
 #define DEVICE_NAME "scsidisk"
 #define TIMEOUT_VALUE (2*HZ)
+#ifdef CONFIG_SD_MANY
+#define DEVICE_NR(device) sd_devnum_to_index((device))
+#else
 #define DEVICE_NR(device) (((MAJOR(device) & SD_MAJOR_MASK) << (8 - 4)) + 
(MINOR(device) >> 4))
+#endif
 
 /* Kludge to use the same number for both char and block major numbers */
 #elif  (MAJOR_NR == MD_MAJOR) && defined(MD_DRIVER)

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