Re: [RFT] Support for ~2144 SCSI discs

Re: [RFT] Support for ~2144 SCSI discs

[Alan Cox]

> In previous experiments trying to connect up to 512 devices we switched to
> vmalloc because the static nature of sd.c's allocation exceeds 128k which
> I assumed was the max for kmalloc YMMV.

vmalloc is fine, but for large sets of disks sd should be disk object
pointers instead, and a 32bit dev_t migration will be needed anyway

[RFT] Support for ~2144 SCSI discs

[Richard Gooch]

  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@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

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@erols.com>
  *       Fix problem where removable media could be ejected after sd_open.
+ *
+ *       Modified by Richard Gooch rgooch@atnf.csiro.au 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@atnf.csiro.au>
+	       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@atnf.csiro.au>
                Created <devfs_*alloc_unique_number>.
+    20010730   Richard Gooch <rgooch@atnf.csiro.au>
+               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)

Re: [RFT] Support for ~2144 SCSI discs

[Jeremy Higdon]

With the sard patch and a 64 bit system, you start having
trouble at around 103 configured disks, because of the following
line in sd_init() (sd.c), because kmalloc doesn't like allocating
large chunks of memory:

        sd = kmalloc((sd_template.dev_max << 4) *
                                          sizeof(struct hd_struct),
                                          GFP_ATOMIC);

Without sard, you'd have problems past 512 disks.


With the sard patch, the hd_struct looks like the following:

struct hd_struct {
        long start_sect;
        long nr_sects;
        devfs_handle_t de;              /* primary (master) devfs entry  */

        int number;                     /* stupid old code wastes space  */

        /* Performance stats: */
        unsigned int ios_in_flight;
        unsigned int io_ticks;
        unsigned int last_idle_time;
        unsigned int last_queue_change;
        unsigned int aveq;

        unsigned int rd_ios;
        unsigned int rd_merges;
        unsigned int rd_ticks;
        unsigned int rd_sectors;
        unsigned int wr_ios;
        unsigned int wr_merges;
        unsigned int wr_ticks;
        unsigned int wr_sectors;
};


The caveat is that I'm looking at a patch that is a few months old (I
couldn't find where the latest version of the kernel patch is).

jeremy

Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Jeremy Higdon writes:
> With the sard patch and a 64 bit system, you start having
> trouble at around 103 configured disks, because of the following

So even without my patch, sard doesn't support the previous limit of
128 devices.

> line in sd_init() (sd.c), because kmalloc doesn't like allocating
> large chunks of memory:
> 
>         sd = kmalloc((sd_template.dev_max << 4) *
>                                           sizeof(struct hd_struct),
>                                           GFP_ATOMIC);
> 
> Without sard, you'd have problems past 512 disks.

Yes, when I was coding up the patch I noticed the use of GFP_ATOMIC in
the allocation calls. I have two questions:
- can we use GFP_KERNEL instead (why use GFP_ATOMIC)
- can we switch to vmalloc() instead of kmalloc()?

> With the sard patch, the hd_struct looks like the following:
> 
> struct hd_struct {
>         long start_sect;
>         long nr_sects;
>         devfs_handle_t de;              /* primary (master) devfs entry  */
> 
>         int number;                     /* stupid old code wastes space  */
> 
>         /* Performance stats: */
>         unsigned int ios_in_flight;
>         unsigned int io_ticks;
>         unsigned int last_idle_time;
>         unsigned int last_queue_change;
>         unsigned int aveq;
> 
>         unsigned int rd_ios;
>         unsigned int rd_merges;
>         unsigned int rd_ticks;
>         unsigned int rd_sectors;
>         unsigned int wr_ios;
>         unsigned int wr_merges;
>         unsigned int wr_ticks;
>         unsigned int wr_sectors;
> };
> 
> The caveat is that I'm looking at a patch that is a few months old (I
> couldn't find where the latest version of the kernel patch is).

Do the stats have to be kept on a per-partition basic? What about
per-device instead?

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Eric Youngdale]

    FYI - At some point in the 2.5 series I would like to do some serious
surgery on the sd datastructures - this will mainly remove load order
dependencies and eliminate the need for CONFIG_SD_EXTRA.  I believe that
some of the work that Jens has already started on the blk device layer will
make support for very large numbers of disks much easier.

-Eric

----- Original Message -----
From: "Richard Gooch" <rgooch@ras.ucalgary.ca>
To: <linux-kernel@vger.kernel.org>; <linux-scsi@vger.kernel.org>
Cc: <devfs-announce-list@mobilix.ras.ucalgary.ca>
Sent: Monday, July 30, 2001 8:30 PM
Subject: [RFT] Support for ~2144 SCSI discs


>   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@atnf.csiro.au
> Current:   rgooch@ras.ucalgary.ca
>
> 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@erols.com>
>   *       Fix problem where removable media could be ejected after
sd_open.
> + *
> + *       Modified by Richard Gooch rgooch@atnf.csiro.au 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@atnf.csiro.au>
> +        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@atnf.csiro.au>
>                 Created <devfs_*alloc_unique_number>.
> +    20010730   Richard Gooch <rgooch@atnf.csiro.au>
> +               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)
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org
>

Re: [RFT] Support for ~2144 SCSI discs

[Mike Anderson]

Richard Gooch [rgooch@ras.ucalgary.ca] wrote:
> Jeremy Higdon writes:
> > With the sard patch and a 64 bit system, you start having
> > trouble at around 103 configured disks, because of the following
> 
> So even without my patch, sard doesn't support the previous limit of
> 128 devices.
> 
> > line in sd_init() (sd.c), because kmalloc doesn't like allocating
> > large chunks of memory:
> > 
> >         sd = kmalloc((sd_template.dev_max << 4) *
> >                                           sizeof(struct hd_struct),
> >                                           GFP_ATOMIC);
> > 
> > Without sard, you'd have problems past 512 disks.
> 
> Yes, when I was coding up the patch I noticed the use of GFP_ATOMIC in
> the allocation calls. I have two questions:
> - can we use GFP_KERNEL instead (why use GFP_ATOMIC)
> - can we switch to vmalloc() instead of kmalloc()?

In previous experiments trying to connect up to 512 devices we switched to
vmalloc because the static nature of sd.c's allocation exceeds 128k which
I assumed was the max for kmalloc YMMV.

> 				Regards,
> 
> 					Richard....
> Permanent: rgooch@atnf.csiro.au
> Current:   rgooch@ras.ucalgary.ca
> -
> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> the body of a message to majordomo@vger.kernel.org

-Mike
-- 
Michael Anderson
mike.anderson@us.ibm.com

Re: [RFT] Support for ~2144 SCSI discs

[Mike Panetta]

Any maybe target mode?  That would be nice to
have :) Or is it already here?

Mike

On Tue, Jul 31, 2001 at 10:10:59AM -0400, Eric Youngdale wrote:
> 
>     FYI - At some point in the 2.5 series I would like to do some serious
> surgery on the sd datastructures - this will mainly remove load order
> dependencies and eliminate the need for CONFIG_SD_EXTRA.  I believe that
> some of the work that Jens has already started on the blk device layer will
> make support for very large numbers of disks much easier.
> 
> -Eric
> 
> ----- Original Message -----
> From: "Richard Gooch" <rgooch@ras.ucalgary.ca>
> To: <linux-kernel@vger.kernel.org>; <linux-scsi@vger.kernel.org>
> Cc: <devfs-announce-list@mobilix.ras.ucalgary.ca>
> Sent: Monday, July 30, 2001 8:30 PM
> Subject: [RFT] Support for ~2144 SCSI discs
> 
> 
> >   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@atnf.csiro.au
> > Current:   rgooch@ras.ucalgary.ca
> >
> > 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@erols.com>
> >   *       Fix problem where removable media could be ejected after
> sd_open.
> > + *
> > + *       Modified by Richard Gooch rgooch@atnf.csiro.au 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@atnf.csiro.au>
> > +        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@atnf.csiro.au>
> >                 Created <devfs_*alloc_unique_number>.
> > +    20010730   Richard Gooch <rgooch@atnf.csiro.au>
> > +               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)
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
> > the body of a message to majordomo@vger.kernel.org
> >
> 
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

-- 

Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Mike Panetta writes:
> Any maybe target mode?  That would be nice to
> have :) Or is it already here?

Well, I haven't done that. I haven't looked for it myself. I don't
have any plans for that.

> > > diff -urN linux-2.4.7/Documentation/Configure.help

BTW: next time please don't quote the patch. No need to chew extra
bandwidth.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Mike Anderson writes:
> In previous experiments trying to connect up to 512 devices we
> switched to vmalloc because the static nature of sd.c's allocation
> exceeds 128k which I assumed was the max for kmalloc YMMV.

Yes, I figure on switching to vmalloc() and putting in an
in_interrupt() test in sd_init() to make sure the vmalloc() is safe.

Eric: do you happen to know why there are these GFP_ATOMIC flags?
To my knowledge, nothing calls sd_init() outside of process context.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Douglas Gilbert]

Richard Gooch wrote:
> 
> Mike Anderson writes:
> > In previous experiments trying to connect up to 512 devices we
> > switched to vmalloc because the static nature of sd.c's allocation
> > exceeds 128k which I assumed was the max for kmalloc YMMV.
> 
> Yes, I figure on switching to vmalloc() and putting in an
> in_interrupt() test in sd_init() to make sure the vmalloc() is safe.
> 
> Eric: do you happen to know why there are these GFP_ATOMIC flags?
> To my knowledge, nothing calls sd_init() outside of process context.

Richard,
I've seen GFP_KERNEL take 10 minutes in lk 2.4.6 . The 
mm gets tweaked pretty often so it is difficult to know 
exactly how it will react when memory is tight. A time 
bound would be useful on GFP_KERNEL.

<opinion> It is best to find out quickly there is 
not enough memory and have some alternate strategy 
to cope with that problem. GFP_KERNEL in its current 
form should be taken out and shot. </opinion>

Doug Gilbert

Re: [RFT] Support for ~2144 SCSI discs

[Eric Youngdale]

    Potentially yes, although that doesn't have so much to do with the disk
driver proper.  The first goal is to rid ourselves of some baggage that make
it harder to move forward.

-Eric

----- Original Message -----
From: "Mike Panetta" <mpanetta@applianceware.com>
To: "Eric Youngdale" <eric@andante.org>
Cc: "Richard Gooch" <rgooch@ras.ucalgary.ca>;
<linux-kernel@vger.kernel.org>; <linux-scsi@vger.kernel.org>;
<devfs-announce-list@mobilix.ras.ucalgary.ca>
Sent: Tuesday, July 31, 2001 6:38 PM
Subject: Re: [RFT] Support for ~2144 SCSI discs


> Any maybe target mode?  That would be nice to
> have :) Or is it already here?
>
> Mike
>
> On Tue, Jul 31, 2001 at 10:10:59AM -0400, Eric Youngdale wrote:
> >
> >     FYI - At some point in the 2.5 series I would like to do some
serious
> > surgery on the sd datastructures - this will mainly remove load order
> > dependencies and eliminate the need for CONFIG_SD_EXTRA.  I believe that
> > some of the work that Jens has already started on the blk device layer
will
> > make support for very large numbers of disks much easier.
> >
> > -Eric
> >
> > ----- Original Message -----
> > From: "Richard Gooch" <rgooch@ras.ucalgary.ca>
> > To: <linux-kernel@vger.kernel.org>; <linux-scsi@vger.kernel.org>
> > Cc: <devfs-announce-list@mobilix.ras.ucalgary.ca>
> > Sent: Monday, July 30, 2001 8:30 PM
> > Subject: [RFT] Support for ~2144 SCSI discs
> >
> >
> > >   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@atnf.csiro.au
> > > Current:   rgooch@ras.ucalgary.ca
> > >
> > > 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@erols.com>
> > >   *       Fix problem where removable media could be ejected after
> > sd_open.
> > > + *
> > > + *       Modified by Richard Gooch rgooch@atnf.csiro.au 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@atnf.csiro.au>
> > > +        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@atnf.csiro.au>
> > >                 Created <devfs_*alloc_unique_number>.
> > > +    20010730   Richard Gooch <rgooch@atnf.csiro.au>
> > > +               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)
> > > -
> > > To unsubscribe from this list: send the line "unsubscribe linux-scsi"
in
> > > the body of a message to majordomo@vger.kernel.org
> > >
> >
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel"
in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at  http://www.tux.org/lkml/
>
> --
>

Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Douglas Gilbert writes:
> Richard Gooch wrote:
> > 
> > Mike Anderson writes:
> > > In previous experiments trying to connect up to 512 devices we
> > > switched to vmalloc because the static nature of sd.c's allocation
> > > exceeds 128k which I assumed was the max for kmalloc YMMV.
> > 
> > Yes, I figure on switching to vmalloc() and putting in an
> > in_interrupt() test in sd_init() to make sure the vmalloc() is safe.
> > 
> > Eric: do you happen to know why there are these GFP_ATOMIC flags?
> > To my knowledge, nothing calls sd_init() outside of process context.
> 
> I've seen GFP_KERNEL take 10 minutes in lk 2.4.6 . The 
> mm gets tweaked pretty often so it is difficult to know 
> exactly how it will react when memory is tight. A time 
> bound would be useful on GFP_KERNEL.
> 
> <opinion> It is best to find out quickly there is 
> not enough memory and have some alternate strategy 
> to cope with that problem. GFP_KERNEL in its current 
> form should be taken out and shot. </opinion>

Perhaps. But I don't think we should use GFP_ATOMIC just because
GFP_KERNEL might be slow! That's just sweeping the problem under the
carpet. If there are MM problems, then waiting 10 minutes for the SCSI
driver to load might provide encouragement for people to fix the
bloody thing.

In any case, using GFP_ATOMIC just means that it will fail, which is
probably worse than trying hard. Not being able to use my SCSI drive
is pretty disastrous on some of my machines. Also, sd_init() is
usually called very early on in the boot process. If memory is tight
at that point, we have more to worry about.

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Karcaw]

I am pleased to see this, I recently expanded the majors number range
on my system from 8 majors to 32 by just pushing the secondary range
from 65-71 to 65-95, This solution Stomped on other majors, COMPAQ
SMART array and IDE6-9, etc. I did not think this was a viable solution
to the mainstream kernel so I have only been using it here.  I am glad
someone with more experience is fixing this one.  I am currently
working with linux on a the HP VA7100 that can support up to 1024 LUNS
(limited by fibre Channel HBAs to 256 or 128) on a single device, so I
am using up disks very quickly with only 128 availible. 

One questions I have on the patch:
-in drivers/char/sysrq.c:is_local_disk(...) references the SCSI major
numbers, should it change for this patch?

I wrote a patch for the Scsi Generic Driver that uses devfs to extend
the numbers of genric devices beyond the 256 minor limit.  It will use
as many major/minor numbers that it can get from devfs for generic scsi
drivers.  it can be found on the official sg web site at:
http://gear.torque.net/sg/ as an experimental driver(sg3120df).

Evan Felix


--- Richard Gooch <rgooch@ras.ucalgary.ca> wrote:
>   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@atnf.csiro.au
> Current:   rgooch@ras.ucalgary.ca




=====
---------
Evan Felix
Karcaw@rocketmail.com
---------

__________________________________________________
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Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Karcaw@rocketmail.com writes:
> I am pleased to see this, I recently expanded the majors number
> range on my system from 8 majors to 32 by just pushing the secondary
> range from 65-71 to 65-95, This solution Stomped on other majors,
> COMPAQ SMART array and IDE6-9, etc. I did not think this was a
> viable solution to the mainstream kernel so I have only been using
> it here.  I am glad someone with more experience is fixing this one.
> I am currently working with linux on a the HP VA7100 that can
> support up to 1024 LUNS (limited by fibre Channel HBAs to 256 or
> 128) on a single device, so I am using up disks very quickly with
> only 128 availible.

Yeah, you're not the only one. I've fielded questions from various
people along the lines of "why does Linux only see the first 128
SDs?".

> One questions I have on the patch:
> -in drivers/char/sysrq.c:is_local_disk(...) references the SCSI major
> numbers, should it change for this patch?

It's not essential. The is_local_disk() function is used to first sync
standard local discs and then "experimental" block devices. So the
extra SDs will get synced regardless. I also note that is_local_disk()
doesn't yet know about extra IDE discs either. Oh, well.

> I wrote a patch for the Scsi Generic Driver that uses devfs to
> extend the numbers of genric devices beyond the 256 minor limit.  It
> will use as many major/minor numbers that it can get from devfs for
> generic scsi drivers.  it can be found on the official sg web site
> at: http://gear.torque.net/sg/ as an experimental driver(sg3120df).

Yes, Doug talked to me about it at OLS. Unfortunately you've added
another search loop in a BH handler. Not your fault, really, since the
SCSI midlayer doesn't have a pointer from the SCSI request structure
to the upper-level driver instance structure. I urged Doug to send in
a patch to Linus that does this.

BTW: if you're going to use my patch, use the second draft I sent out
last night. The first one didn't quite work :-)

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Douglas Gilbert]

Alan Cox wrote:
> 
> > > kmalloc with GFP_KERNEL has a 128K limit which avoids the bizarre
> > > behaviour you get when you abuse get_free_pages.
> >
> > Last I heard, get_free_pages() also has a 128 kiB limit. So what's the
> > difference?
> 
> get_free_pages doesnt have such a limit. Thats why sg had the problem it did

Alan,
That is incorrect.

The failure I got with the sg driver with cdrdao
and cdda2wav was with 32 KB buffers, lots of them.
cdda2wav in RH 7.1 was trying to get 100 MB of them!

If you look at the sg driver you will find that it never
attempts a get_free_pages greater than SG_SCATTER_SZ (32 KB).
So that unkillable lockup on those apps demonstrates
rather well that GFP_KERNEL is dangerous.

Doug Gilbert

Re: [RFT] Support for ~2144 SCSI discs

[Alan Cox]

> > kmalloc with GFP_KERNEL has a 128K limit which avoids the bizarre
> > behaviour you get when you abuse get_free_pages.
> 
> Last I heard, get_free_pages() also has a 128 kiB limit. So what's the
> difference?

get_free_pages doesnt have such a limit. Thats why sg had the problem it did

Re: [RFT] Support for ~2144 SCSI discs

[Richard Gooch]

Alan Cox writes:
> > I've seen GFP_KERNEL take 10 minutes in lk 2.4.6 . The 
> > mm gets tweaked pretty often so it is difficult to know 
> > exactly how it will react when memory is tight. A time 
> > bound would be useful on GFP_KERNEL.
> 
> kmalloc with GFP_KERNEL has a 128K limit which avoids the bizarre
> behaviour you get when you abuse get_free_pages.

Last I heard, get_free_pages() also has a 128 kiB limit. So what's the
difference?

				Regards,

					Richard....
Permanent: rgooch@atnf.csiro.au
Current:   rgooch@ras.ucalgary.ca

Re: [RFT] Support for ~2144 SCSI discs

[Alan Cox]

> I've seen GFP_KERNEL take 10 minutes in lk 2.4.6 . The 
> mm gets tweaked pretty often so it is difficult to know 
> exactly how it will react when memory is tight. A time 
> bound would be useful on GFP_KERNEL.

kmalloc with GFP_KERNEL has a 128K limit which avoids the bizarre behaviour
you get when you abuse get_free_pages.