Re: RFC: Modularize /proc/partitons (was Re: /proc/partitions for LVM)

[Brian Kress <kressb@fsc-usa.com>]

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"Heinz J. Mauelshagen" wrote:
> 
> On Wed, Nov 22, 2000 at 04:27:51PM -0500, Brian Kress wrote:
> > "Heinz J. Mauelshagen" wrote:
> > >
> > > On Wed, Nov 22, 2000 at 04:05:39PM -0500, Brian Kress wrote:
> > > >       Question about /proc/partitions and LVM.  LVM devices in
> > > > /proc/partitions currently show up as lvma, lvmb, etc, depending on
> > > > their device number.  This breaks things like mount by filesystem
> > > > name.  Back when LVM existed as a patch, I believe there was some
> > > > support in fs/partitions/check.c for showing the proper name for
> > > > the device (something like <vgname>/<lvname>).
> > >
> > > Yes.
> > > It actually was <vgname>/<lvname>.
> > >
> > > Linus didn't accept it though.
> > >
> > > The code is still available in case he changes his mind.
> >
> >       Yes, I can see that now looking through lvm.c.  (LVM_HD_NAME)
> > I'm guessing why he didn't take it is the minor hack of adding a
> > function pointer to genhd.c as a special case just for LVM.
> >       A general solution to this problem would be nice.  The
> > big switch statement in disk_name in fs/paritions/check.c is kind
> > of ugly as it has generic code have to know things about specific
> > drivers.
> 
> Yep.
> 
> >       How's this for an idea to generalize this.  Put a function
> > pointer in the gendisk structure for a specific function to call
> > for disk_name for disks for that gendisk.
> 
> Sounds resonable to me.
> 
> > That way, LVM gets its
> > <vgname>/<lvname>, IDE gets its two disks per major (special cased
> > right now), all the other special cases get what they need and future
> > drivers can call their devices whatever they like without touching
> > this file.  Makes the whole thing more modular.  Make a NULL for
> > this function default to the old <name>a, <name>b, etc.
> >       What to people think about this?  If this sounds reasonable
> > I can come up with a patch.
> 
> Very good. I'ld appreciate it.
> 


OK, here's the patch.  It has three sets of changes:

1)  Add a function pointer to struct gendisk called hd_name.

2)  Make disk_name in fs/partitions/check.c use that function
    pointer if its non-null.

3)  Change the following drivers to use this method. (adding the
    driver specific method and removing the old code in check.c)

drivers/md/lvm.c
drivers/md/md.c
drivers/ide/ide-probe.c
drivers/scsi/sd.c
drivers/block/cpqarray.c
drivers/block/cciss.c
drivers/block/DAC960.c


	Let me know what you think.  Think there's any chance we
can get this in the main kernel tree?


Brian Kress
kressb@fsc-usa.com

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diff -u --recursive linux-2.4.0-test11/drivers/block/DAC960.c linux-2.4.0-test11-ppfix/drivers/block/DAC960.c
--- linux-2.4.0-test11/drivers/block/DAC960.c	Mon Nov 20 15:17:25 2000
+++ linux-2.4.0-test11-ppfix/drivers/block/DAC960.c	Thu Nov 23 14:29:37 2000
@@ -1885,6 +1885,21 @@
 }
 
 
+char *DAC960_disk_name(struct gendisk *hd, int minor, char *buf)
+
+{
+	int ctlr = hd->major - DAC960_MAJOR;
+	int disk = minor >> hd->minor_shift;
+	int part = minor & ((1 << hd->minor_shift) - 1);
+
+	if (part)
+		sprintf(buf, "%s/c%dd%dp%d", hd->major_name, ctlr, disk, part);
+	else
+		sprintf(buf, "%s/c%dd%d", hd->major_name, ctlr, disk);
+	return buf;
+}
+
+
 /*
   DAC960_RegisterBlockDevice registers the Block Device structures
   associated with Controller.
@@ -1945,6 +1960,7 @@
   Controller->GenericDiskInfo.nr_real = Controller->LogicalDriveCount;
   Controller->GenericDiskInfo.next = NULL;
   Controller->GenericDiskInfo.fops = &DAC960_BlockDeviceOperations;
+  Controller->GenericDiskInfo.hd_name = DAC960_disk_name;
   /*
     Install the Generic Disk Information structure at the end of the list.
   */
diff -u --recursive linux-2.4.0-test11/drivers/block/cciss.c linux-2.4.0-test11-ppfix/drivers/block/cciss.c
--- linux-2.4.0-test11/drivers/block/cciss.c	Mon Nov 20 15:17:25 2000
+++ linux-2.4.0-test11-ppfix/drivers/block/cciss.c	Thu Nov 23 14:22:55 2000
@@ -1749,6 +1749,20 @@
 	kfree(size_buff);
 }	
 
+char *cciss_disk_name(struct gendisk *hd, int minor, char *buf)
+
+{
+	int ctlr = hd->major - COMPAQ_CISS_MAJOR;
+	int disk = minor >> hd->minor_shift;
+	int part = minor & ((1 << hd->minor_shift) - 1);
+
+	if (part)
+		sprintf(buf, "%s/c%dd%dp%d", hd->major_name, ctlr, disk, part);
+	else
+		sprintf(buf, "%s/c%dd%d", hd->major_name, ctlr, disk);
+	return buf;
+}
+
 /*
  *  This is it.  Find all the controllers and register them.  I really hate
  *  stealing all these major device numbers.
@@ -1851,6 +1865,7 @@
 		hba[i]->gendisk.part = hba[i]->hd;
 		hba[i]->gendisk.sizes = hba[i]->sizes;
 		hba[i]->gendisk.nr_real = hba[i]->num_luns;
+		hba[i]->gendisk.hd_name = cciss_disk_name;
 
 		/* Get on the disk list */ 
 		hba[i]->gendisk.next = gendisk_head;
diff -u --recursive linux-2.4.0-test11/drivers/block/cpqarray.c linux-2.4.0-test11-ppfix/drivers/block/cpqarray.c
--- linux-2.4.0-test11/drivers/block/cpqarray.c	Mon Nov 20 15:20:29 2000
+++ linux-2.4.0-test11-ppfix/drivers/block/cpqarray.c	Thu Nov 23 14:14:03 2000
@@ -362,6 +362,20 @@
 }
 #endif /* MODULE */
 
+char *ida_disk_name(struct gendisk *hd, int minor, char *buf)
+
+{
+	int ctlr = hd->major - COMPAQ_SMART2_MAJOR;
+	int disk = minor >> hd->minor_shift;
+	int part = minor & ((1 << hd->minor_shift) - 1);
+
+	if (part)
+		sprintf(buf, "%s/c%dd%dp%d", hd->major_name, ctlr, disk, part);
+	else
+		sprintf(buf, "%s/c%dd%d", hd->major_name, ctlr, disk);
+	return buf;                                                   
+}
+
 /*
  *  This is it.  Find all the controllers and register them.  I really hate
  *  stealing all these major device numbers.
@@ -512,6 +526,7 @@
 		ida_gendisk[i].part = ida + (i*256);
 		ida_gendisk[i].sizes = ida_sizes + (i*256);
 		ida_gendisk[i].nr_real = 0; 
+		ida_gendisk[i].hd_name = ida_disk_name;
 	
 		/* Get on the disk list */
 		ida_gendisk[i].next = gendisk_head;
diff -u --recursive linux-2.4.0-test11/drivers/ide/ide-probe.c linux-2.4.0-test11-ppfix/drivers/ide/ide-probe.c
--- linux-2.4.0-test11/drivers/ide/ide-probe.c	Thu Aug  3 19:29:49 2000
+++ linux-2.4.0-test11-ppfix/drivers/ide/ide-probe.c	Thu Nov 23 12:32:16 2000
@@ -726,6 +726,40 @@
 	return 0;
 }
 
+char* ide_disk_name(struct gendisk *hd, int minor, char *buf)
+
+{
+	int unit = (minor >> hd->minor_shift) + 'a';                         
+	unsigned int part = minor & ((1 << hd->minor_shift) - 1);
+
+	switch (hd->major) {
+		case IDE9_MAJOR:
+			unit += 2;
+		case IDE8_MAJOR:
+			unit += 2;
+		case IDE7_MAJOR:
+			unit += 2;
+		case IDE6_MAJOR:
+			unit += 2;
+		case IDE5_MAJOR:
+			unit += 2;
+		case IDE4_MAJOR:
+			unit += 2;
+		case IDE3_MAJOR:
+			unit += 2;
+		case IDE2_MAJOR:
+			unit += 2;
+		case IDE1_MAJOR:
+			unit += 2;
+		case IDE0_MAJOR:
+	}
+	if (part)
+		sprintf(buf, "hd%c%d", unit, part);
+	else
+		sprintf(buf, "hd%c", unit);
+	return buf;                                                          
+}
+
 /*
  * init_gendisk() (as opposed to ide_geninit) is called for each major device,
  * after probing for drives, to allocate partition tables and other data
@@ -781,6 +815,7 @@
 	gd->fops        = ide_fops;             /* file operations */
 	gd->de_arr	= kmalloc (sizeof *gd->de_arr * units, GFP_KERNEL);
 	gd->flags	= kmalloc (sizeof *gd->flags * units, GFP_KERNEL);
+	gd->hd_name	= ide_disk_name;
 	if (gd->de_arr)
 		memset (gd->de_arr, 0, sizeof *gd->de_arr * units);
 	if (gd->flags)
diff -u --recursive linux-2.4.0-test11/drivers/md/lvm.c linux-2.4.0-test11-ppfix/drivers/md/lvm.c
--- linux-2.4.0-test11/drivers/md/lvm.c	Mon Nov 20 15:20:30 2000
+++ linux-2.4.0-test11-ppfix/drivers/md/lvm.c	Thu Nov 23 07:47:20 2000
@@ -213,9 +213,7 @@
 &lvm_proc_get_info;
 #endif
 
-#ifdef LVM_HD_NAME
-void lvm_hd_name(char *, int);
-#endif
+char *lvm_hd_name(struct gendisk *, int, char *);
 /* End external function prototypes */
 
 
@@ -230,9 +228,6 @@
 int lvm_snapshot_alloc(lv_t *);
 void lvm_snapshot_release(lv_t *); 
 
-#ifdef LVM_HD_NAME
-extern void (*lvm_hd_name_ptr) (char *, int);
-#endif
 static int lvm_map(struct buffer_head *, int);
 static int lvm_do_lock_lvm(void);
 static int lvm_do_le_remap(vg_t *, void *);
@@ -397,11 +392,6 @@
 		lvm_gendisk.next = NULL;
 	}
 
-#ifdef LVM_HD_NAME
-	/* reference from drivers/block/genhd.c */
-	lvm_hd_name_ptr = lvm_hd_name;
-#endif
-
 	blk_init_queue(BLK_DEFAULT_QUEUE(MAJOR_NR), DEVICE_REQUEST);
 	blk_queue_make_request(BLK_DEFAULT_QUEUE(MAJOR_NR), lvm_make_request_fn);
 	blk_queue_pluggable(BLK_DEFAULT_QUEUE(MAJOR_NR), lvm_plug_device_noop);
@@ -460,11 +450,6 @@
 	remove_proc_entry(LVM_NAME, &proc_root);
 #endif
 
-#ifdef LVM_HD_NAME
-	/* reference from linux/drivers/block/genhd.c */
-	lvm_hd_name_ptr = NULL;
-#endif
-
 	printk(KERN_INFO "%s -- Module successfully deactivated\n", lvm_name);
 
 	return;
@@ -1448,24 +1433,22 @@
  * internal support functions
  */
 
-#ifdef LVM_HD_NAME
 /*
  * generate "hard disk" name
  */
-void lvm_hd_name(char *buf, int minor)
+char *lvm_hd_name(struct gendisk *hd, int minor, char *buf)
 {
 	int len = 0;
 	lv_t *lv_ptr;
 
 	if (vg[VG_BLK(minor)] == NULL ||
 	    (lv_ptr = vg[VG_BLK(minor)]->lv[LV_BLK(minor)]) == NULL)
-		return;
+		return buf;
 	len = strlen(lv_ptr->lv_name) - 5;
 	memcpy(buf, &lv_ptr->lv_name[5], len);
 	buf[len] = 0;
-	return;
+	return buf;
 }
-#endif
 
 
 /*
@@ -2515,6 +2498,8 @@
 
 	blksize_size[MAJOR_NR] = lvm_blocksizes;
 	blk_size[MAJOR_NR] = lvm_size;
+
+	lvm_gendisk.hd_name=lvm_hd_name;
 
 	return;
 } /* lvm_gen_init() */
diff -u --recursive linux-2.4.0-test11/drivers/md/md.c linux-2.4.0-test11-ppfix/drivers/md/md.c
--- linux-2.4.0-test11/drivers/md/md.c	Mon Nov 20 15:20:30 2000
+++ linux-2.4.0-test11-ppfix/drivers/md/md.c	Thu Nov 23 07:56:06 2000
@@ -113,6 +113,8 @@
 extern struct block_device_operations md_fops;
 static devfs_handle_t devfs_handle;
 
+char *md_disk_name(struct gendisk*, int, char *);
+
 static struct gendisk md_gendisk=
 {
 	major: MD_MAJOR,
@@ -125,6 +127,7 @@
 	real_devices: NULL,
 	next: NULL,
 	fops: &md_fops,
+	hd_name: md_disk_name,
 };
 
 /*
@@ -215,6 +218,14 @@
 	MOD_INC_USE_COUNT;
 
 	return mddev;
+}
+
+char * md_disk_name(struct gendisk *hd, int minor, char* buf)
+
+{
+	int unit = (minor >> hd->minor_shift) + '0';
+	sprintf(buf, "%s%c", hd->major_name, unit);
+        return buf;
 }
 
 struct gendisk * find_gendisk (kdev_t dev)
diff -u --recursive linux-2.4.0-test11/drivers/scsi/sd.c linux-2.4.0-test11-ppfix/drivers/scsi/sd.c
--- linux-2.4.0-test11/drivers/scsi/sd.c	Mon Nov 20 15:17:18 2000
+++ linux-2.4.0-test11-ppfix/drivers/scsi/sd.c	Thu Nov 23 09:53:01 2000
@@ -1013,6 +1013,30 @@
 	return i;
 }
 
+char *scsi_disk_name(struct gendisk *hd, int minor, char *buf)
+
+{
+	int unit = (minor >> hd->minor_shift) + 'a';
+	unsigned int part = minor & ((1 << hd->minor_shift) - 1);
+
+	if (hd->major >= SCSI_DISK1_MAJOR && hd->major <= SCSI_DISK7_MAJOR) {
+		unit = unit + (hd->major - SCSI_DISK1_MAJOR + 1) * 16;
+		if (unit > 'z') {
+			unit -= 'z' + 1;
+			sprintf(buf, "sd%c%c", 'a' + unit / 26, 'a' + unit % 26);
+			if (part)
+				sprintf(buf + 4, "%d", part);
+			return buf;
+		}
+	}
+
+	if (part)
+		sprintf(buf, "sd%c%d", unit, part);
+	else
+		sprintf(buf, "sd%c", unit);
+	return buf;
+}
+
 /*
  * The sd_init() function looks at all SCSI drives present, determines
  * their size, and reads partition table entries for them.
@@ -1109,6 +1133,7 @@
 		sd_gendisks[i].next = sd_gendisks + i + 1;
 		sd_gendisks[i].real_devices =
 		    (void *) (rscsi_disks + i * SCSI_DISKS_PER_MAJOR);
+		sd_gendisks[i].hd_name=scsi_disk_name;
 	}
 
 	LAST_SD_GENDISK.next = NULL;
diff -u --recursive linux-2.4.0-test11/fs/partitions/check.c linux-2.4.0-test11-ppfix/fs/partitions/check.c
--- linux-2.4.0-test11/fs/partitions/check.c	Mon Nov 20 15:17:27 2000
+++ linux-2.4.0-test11-ppfix/fs/partitions/check.c	Thu Nov 23 14:30:45 2000
@@ -83,11 +83,10 @@
  */
 char *disk_name (struct gendisk *hd, int minor, char *buf)
 {
-	unsigned int part;
 	const char *maj = hd->major_name;
 	int unit = (minor >> hd->minor_shift) + 'a';
+	unsigned int part = minor & ((1 << hd->minor_shift) - 1);
 
-	part = minor & ((1 << hd->minor_shift) - 1);
 	if (hd->part[minor].de) {
 		int pos;
 
@@ -95,77 +94,8 @@
 		if (pos >= 0)
 			return buf + pos;
 	}
-	/*
-	 * IDE devices use multiple major numbers, but the drives
-	 * are named as:  {hda,hdb}, {hdc,hdd}, {hde,hdf}, {hdg,hdh}..
-	 * This requires special handling here.
-	 */
-	switch (hd->major) {
-		case IDE9_MAJOR:
-			unit += 2;
-		case IDE8_MAJOR:
-			unit += 2;
-		case IDE7_MAJOR:
-			unit += 2;
-		case IDE6_MAJOR:
-			unit += 2;
-		case IDE5_MAJOR:
-			unit += 2;
-		case IDE4_MAJOR:
-			unit += 2;
-		case IDE3_MAJOR:
-			unit += 2;
-		case IDE2_MAJOR:
-			unit += 2;
-		case IDE1_MAJOR:
-			unit += 2;
-		case IDE0_MAJOR:
-			maj = "hd";
-			break;
-		case MD_MAJOR:
-			unit -= 'a'-'0';
-			break;
-	}
-	if (hd->major >= SCSI_DISK1_MAJOR && hd->major <= SCSI_DISK7_MAJOR) {
-		unit = unit + (hd->major - SCSI_DISK1_MAJOR + 1) * 16;
-		if (unit > 'z') {
-			unit -= 'z' + 1;
-			sprintf(buf, "sd%c%c", 'a' + unit / 26, 'a' + unit % 26);
-			if (part)
-				sprintf(buf + 4, "%d", part);
-			return buf;
-		}
-	}
-	if (hd->major >= COMPAQ_SMART2_MAJOR && hd->major <= COMPAQ_SMART2_MAJOR+7) {
-		int ctlr = hd->major - COMPAQ_SMART2_MAJOR;
- 		int disk = minor >> hd->minor_shift;
- 		int part = minor & (( 1 << hd->minor_shift) - 1);
- 		if (part == 0)
- 			sprintf(buf, "%s/c%dd%d", maj, ctlr, disk);
- 		else
- 			sprintf(buf, "%s/c%dd%dp%d", maj, ctlr, disk, part);
- 		return buf;
- 	}
-	if (hd->major >= COMPAQ_CISS_MAJOR && hd->major <= COMPAQ_CISS_MAJOR+7) {
-                int ctlr = hd->major - COMPAQ_CISS_MAJOR;
-                int disk = minor >> hd->minor_shift;
-                int part = minor & (( 1 << hd->minor_shift) - 1);
-                if (part == 0)
-                        sprintf(buf, "%s/c%dd%d", maj, ctlr, disk);
-                else
-                        sprintf(buf, "%s/c%dd%dp%d", maj, ctlr, disk, part);
-                return buf;
-	}
-	if (hd->major >= DAC960_MAJOR && hd->major <= DAC960_MAJOR+7) {
-		int ctlr = hd->major - DAC960_MAJOR;
- 		int disk = minor >> hd->minor_shift;
- 		int part = minor & (( 1 << hd->minor_shift) - 1);
- 		if (part == 0)
- 			sprintf(buf, "%s/c%dd%d", maj, ctlr, disk);
- 		else
- 			sprintf(buf, "%s/c%dd%dp%d", maj, ctlr, disk, part);
- 		return buf;
- 	}
+	if (hd->hd_name) return hd->hd_name(hd, minor, buf);
+
 	if (part)
 		sprintf(buf, "%s%c%d", maj, unit, part);
 	else
diff -u --recursive linux-2.4.0-test11/include/linux/genhd.h linux-2.4.0-test11-ppfix/include/linux/genhd.h
--- linux-2.4.0-test11/include/linux/genhd.h	Mon Nov 20 15:31:01 2000
+++ linux-2.4.0-test11-ppfix/include/linux/genhd.h	Thu Nov 23 07:44:35 2000
@@ -72,6 +72,8 @@
 
 	devfs_handle_t *de_arr;         /* one per physical disc */
 	char *flags;                    /* one per physical disc */
+
+	char *(*hd_name) (struct gendisk *, int, char *);
 };
 #endif  /*  __KERNEL__  */