/proc/partitions for LVM

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>).

Are their any plans for something like this to be added
or is their a reason it was taken out?

BTW, 2.4.0-test11 is the first "perfect" kernel for me. It
finally has everything I use working correctly. (well, with a small raid5 patch, anyway).

Brian Kress
[email protected]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
Please read the FAQ at http://www.tux.org/lkml/

Quoted 6 lines · Brian Kress

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.

Quoted 10 lines

Are their any plans for something like this to be added
or is their a reason it was taken out?

BTW, 2.4.0-test11 is the first "perfect" kernel for me. It
finally has everything I use working correctly. (well, with a small raid5 patch, anyway).

Quoted 6 lines

Brian Kress
[email protected]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
Please read the FAQ at http://www.tux.org/lkml/

--

Regards,
Heinz -- The LVM guy --

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Bartningstr. 12

                                                  64289 Darmstadt
                                                  Germany
[email protected]                           +49 6151 7103 86
                                                       FAX 7103 96

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Quoted 9 lines · Heinz J. Mauelshagen

Quoted 6 lines · Brian Kress

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>).

Quoted 6 lines

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.

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.

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.

Brian Kress
[email protected]

Quoted 31 lines

Quoted 10 lines

Are their any plans for something like this to be added
or is their a reason it was taken out?

BTW, 2.4.0-test11 is the first "perfect" kernel for me. It
finally has everything I use working correctly. (well, with a small raid5 patch, anyway).

Quoted 6 lines

Brian Kress
[email protected]
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
Please read the FAQ at http://www.tux.org/lkml/

--

Regards,
Heinz -- The LVM guy --

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Bartningstr. 12

                                                  64289 Darmstadt
                                                  Germany
[email protected]                           +49 6151 7103 86
                                                       FAX 7103 96

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Quoted 17 lines · Brian Kress

Quoted 9 lines · Heinz J. Mauelshagen

Quoted 6 lines · Brian Kress

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>).

Quoted 6 lines

Yes.
It actually was <vgname>/<lvname>.

Linus didn't accept it though.

The code is still available in case he changes his mind.

Quoted 7 lines

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.

Quoted 3 lines

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.

Quoted 8 lines

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.

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)

Quoted 44 lines · Heinz J. Mauelshagen

Quoted 17 lines · Brian Kress

Quoted 9 lines · Heinz J. Mauelshagen

Quoted 6 lines · Brian Kress

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>).

Quoted 6 lines

Yes.
It actually was <vgname>/<lvname>.

Linus didn't accept it though.

The code is still available in case he changes his mind.

Quoted 7 lines

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.

Quoted 3 lines

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.

Quoted 8 lines

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.

Quoted 2 lines

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
[email protected]
diff -u --recursive linux-2.4.0-test11/drivers/block/DAC960.c linux-2.4.0-test11-ppfix/drivers/block/DAC960.c

drivers/block/DAC960.c +16 -0

@@ -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

drivers/block/cciss.c +15 -0

@@ -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

drivers/block/cpqarray.c +15 -0

@@ -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

drivers/ide/ide-probe.c +35 -0

@@ -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

drivers/md/lvm.c +6 -21

@@ -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

drivers/md/md.c +11 -0

@@ -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

drivers/scsi/sd.c +25 -0

@@ -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

fs/partitions/check.c +3 -73

@@ -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