udev: remove node only if major/minor matches

udev: remove node only if major/minor matches

[Kay Sievers]

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Hi Hannes,
here we remove the device node only if the major/minor number matches
the one in our database. Will this solve the possible issue with the multipath
setup, where a device remove event may delete a node which belongs to a
different path?

Thanks,
Kay

[-- Attachment #2: udev-check-removal-01.patch --]
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===== udev_db.c 1.41 vs edited =====
--- 1.41/udev_db.c	2005-02-04 18:38:55 +01:00
+++ edited/udev_db.c	2005-02-17 02:24:49 +01:00
@@ -79,6 +79,7 @@ int udev_db_add_device(struct udevice *u
 	fprintf(f, "P:%s\n", udev->devpath);
 	fprintf(f, "N:%s\n", udev->name);
 	fprintf(f, "S:%s\n", udev->symlink);
+	fprintf(f, "M:%u:%u\n", udev->major, udev->minor);
 	fprintf(f, "A:%u\n", udev->partitions);
 	fprintf(f, "R:%u\n", udev->ignore_remove);
 
@@ -90,6 +91,7 @@ int udev_db_add_device(struct udevice *u
 static int parse_db_file(struct udevice *udev, const char *filename)
 {
 	char line[NAME_SIZE];
+	char temp[NAME_SIZE];
 	char *bufline;
 	char *buf;
 	size_t bufsize;
@@ -119,6 +121,13 @@ static int parse_db_file(struct udevice 
 				count = NAME_SIZE-1;
 			strncpy(udev->name, &bufline[2], count-2);
 			udev->name[count-2] = '\0';
+			break;
+		case 'M':
+			if (count > NAME_SIZE)
+				count = NAME_SIZE-1;
+			strncpy(temp, &bufline[2], count-2);
+			temp[count-2] = '\0';
+			sscanf(temp, "%u:%u", &udev->major, &udev->minor);
 			break;
 		case 'S':
 			if (count > NAME_SIZE)
===== udev_remove.c 1.45 vs edited =====
--- 1.45/udev_remove.c	2005-02-09 00:43:18 +01:00
+++ edited/udev_remove.c	2005-02-17 02:55:21 +01:00
@@ -71,6 +71,7 @@ static int delete_node(struct udevice *u
 {
 	char filename[NAME_SIZE];
 	char partitionname[NAME_SIZE];
+	struct stat stats;
 	int retval;
 	int i;
 	char *pos;
@@ -79,6 +80,15 @@ static int delete_node(struct udevice *u
 
 	snprintf(filename, NAME_SIZE, "%s/%s", udev_root, udev->name);
 	filename[NAME_SIZE-1] = '\0';
+
+	dbg("checking major/minor of device node '%s'", filename);
+	if (stat(filename, &stats) != 0)
+		return -1;
+
+	if (udev->major && stats.st_rdev != makedev(udev->major, udev->minor)) {
+		info("device node '%s' points to a different device, skip removal", filename);
+		return -1;
+	}
 
 	info("removing device node '%s'", filename);
 	retval = unlink_secure(filename);
===== test/udev-test.pl 1.82 vs edited =====
--- 1.82/test/udev-test.pl	2005-02-13 22:03:06 +01:00
+++ edited/test/udev-test.pl	2005-02-17 03:28:45 +01:00
@@ -758,23 +758,13 @@ BUS="scsi", KERNEL="sda", NAME="link", S
 EOF
 	},
 	{
-		desc		=> "symlink name empty",
-		subsys		=> "block",
-		devpath		=> "/block/sda",
-		exp_name	=> "",
-		exp_target	=> "link",
-		exp_error	=> "yes",
-		conf		=> <<EOF
-BUS="scsi", KERNEL="sda", NAME="link", SYMLINK=""
-EOF
-	},
-	{
 		desc		=> "symlink name '.'",
 		subsys		=> "block",
 		devpath		=> "/block/sda",
 		exp_name	=> ".",
 		exp_target	=> "link",
-		exp_error	=> "yes",
+		exp_add_error	=> "yes",
+		exp_rem_error	=> "yes",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="link", SYMLINK="."
 EOF
@@ -785,7 +775,7 @@ EOF
 		devpath		=> "/block/sda",
 		exp_name	=> "symlink",
 		exp_target	=> "",
-		exp_error	=> "yes",
+		exp_add_error	=> "yes",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="", SYMLINK="symlink"
 EOF
@@ -796,7 +786,8 @@ EOF
 		devpath		=> "/block/sda",
 		exp_name	=> "",
 		exp_target	=> "",
-		exp_error	=> "yes",
+		exp_add_error	=> "yes",
+		exp_rem_error	=> "yes",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="", SYMLINK=""
 EOF
@@ -807,6 +798,8 @@ EOF
 		devpath		=> "/class/tty/tty0",
 		exp_name	=> "link",
 		exp_target	=> "link",
+		exp_rem_error	=> "yes",
+		option		=> "clear",
 		conf		=> <<EOF
 KERNEL="tty0", NAME="link", SYMLINK="link"
 EOF
@@ -1025,7 +1018,7 @@ EOF
 		subsys		=> "block",
 		devpath		=> "/block/sda",
 		exp_name	=> "node",
-		exp_error	=> "yes",
+		exp_add_error	=> "yes",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="node", OPTIONS="ignore"
 EOF
@@ -1045,7 +1038,7 @@ EOF
 		subsys		=> "block",
 		devpath		=> "/block/sda/sda1",
 		exp_name	=> "node6",
-		exp_error	=> "yes",
+		exp_add_error	=> "yes",
 		conf		=> <<EOF
 SUBSYSTEM="block", OPTIONS="all_partitions"
 BUS="scsi", KERNEL="sda", NAME="node"
@@ -1056,7 +1049,7 @@ EOF
 		subsys		=> "block",
 		devpath		=> "/block/sda",
 		exp_name	=> "node",
-		exp_error	=> "yes",
+		exp_rem_error	=> "yes",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="node", OPTIONS="ignore_remove"
 EOF
@@ -1066,7 +1059,7 @@ EOF
 		subsys		=> "block",
 		devpath		=> "/block/sda",
 		exp_name	=> "node14",
-		exp_error	=> "yes",
+		exp_rem_error	=> "yes",
 		option		=> "clear",
 		conf		=> <<EOF
 BUS="scsi", KERNEL="sda", NAME="node", OPTIONS="ignore_remove, all_partitions"
@@ -1225,7 +1218,7 @@ sub symlink_test {
 		} else {
 			print "expected symlink from: \'$config->{exp_name}\' to \'$config->{exp_target}\'\n";
 			print "created symlink from: \'$config->{exp_name}\' to \'$2\'\n";
-			if ($config->{exp_error}) {
+			if ($config->{exp_add_error}) {
 				print "as expected    ";
 			} else {
 				$error++;
@@ -1234,7 +1227,7 @@ sub symlink_test {
 	} else {
 		print "expected symlink from: \'$config->{exp_name}\' to \'$config->{exp_target}\'\n";
 		print "symlink: not created ";
-		if ($config->{exp_error}) {
+		if ($config->{exp_add_error}) {
 			print "as expected    ";
 		} else {
 			$error++;
@@ -1273,7 +1266,7 @@ sub run_test {
 		print "add: ok    ";
 	} else {
 		print "add: error ";
-		if ($config->{exp_error}) {
+		if ($config->{exp_add_error}) {
 			print "as expected    ";
 		} else {
 			print "\n\n";
@@ -1292,7 +1285,7 @@ sub run_test {
 	if ((-e "$PWD/$udev_root$config->{exp_name}") ||
 	    (-l "$PWD/$udev_root$config->{exp_name}")) {
 		print "remove: error ";
-		if ($config->{exp_error}) {
+		if ($config->{exp_rem_error}) {
 			print "as expected\n\n";
 		} else {
 			print "\n\n";

Re: udev: remove node only if major/minor matches

[Greg KH]

On Thu, Feb 17, 2005 at 04:13:13AM +0100, Kay Sievers wrote:
> Hi Hannes,
> here we remove the device node only if the major/minor number matches
> the one in our database. Will this solve the possible issue with the multipath
> setup, where a device remove event may delete a node which belongs to a
> different path?

Patch looks good to me.  Bah, I hate multipath...

thanks,

greg k-h


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Re: udev: remove node only if major/minor matches

[Hannes Reinecke]

Kay Sievers wrote:
> Hi Hannes,
> here we remove the device node only if the major/minor number matches
> the one in our database. Will this solve the possible issue with the multipath
> setup, where a device remove event may delete a node which belongs to a
> different path?
> 
Could be. Having the Major/Minor numbers in udev is a Good Thing (tm), 
regardless. I'll check the iSCSI thing.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke			hare@suse.de
SUSE Linux Products GmbH		S390 & zSeries
Maxfeldstraße 5				+49 911 74053 688
90409 Nürnberg				http://www.suse.de


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Re: udev: remove node only if major/minor matches

[Patrick Mansfield]

On Thu, Feb 17, 2005 at 04:13:13AM +0100, Kay Sievers wrote:
> Hi Hannes,
> here we remove the device node only if the major/minor number matches
> the one in our database. Will this solve the possible issue with the multipath
> setup, where a device remove event may delete a node which belongs to a
> different path?

If device nodes are being overwritten, how does not removing an
overwritten /dev help?

Don't the multipath tools already require a separate sd /dev for proper usage
(i.e. path checker)?

It would be much better to never overwrite a correct /dev entry. Paths (i.e.
sd's) should really be named based on their sysfs or physical path, or
just the default name; the dm device should be named based on disk or
device specific attributes (scsi_id, volume_id, etc.). There is no good
way to know if dm is going to use an sd in a dm multipath.

If "%e" would always work, that might help.

-- Patrick Mansfield


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