From d11abe4bd5cad39803726ddff1888674e417bda5 Mon Sep 17 00:00:00 2001

From: Coly Li <colyli@suse.de>

Date: Wed, 31 Jul 2019 13:29:29 +0800

Subject: [RHEL7.8 PATCH V2 32/47] mdadm: add --no-devices to avoid component

 devices detail information

When people assemble a md raid device with a large number of

component deivces (e.g. 1500 DASD disks), the raid device detail

information generated by 'mdadm --detail --export $devnode' is very

large. It is because the detail information contains information of

all the component disks (even the missing/failed ones).

In such condition, when udev-md-raid-arrays.rules is triggered and

internally calls "mdadm --detail --no-devices --export $devnode",

user may observe systemd error message ""invalid message length". It

is because the following on-stack raw message buffer in systemd code

is not big enough,

        systemd/src/libudev/libudev-monitor.c

        _public_ struct udev_device *udev_monito ...

                struct ucred *cred;

                union {

                        struct udev_monitor_netlink_header nlh;

                        char raw[8192];

                } buf;

Even change size of raw[] from 8KB to larger size, it may still be not

enough for detail message of a md raid device with much larger number of

component devices.

To fix this problem, an extra option '--no-devices' is added (the

original idea is proposed by Neil Brown). When printing detailed

information of a md raid device, if '--no-devices' is specified, then

all component devices information will not be printed, then the output

message size can be restricted to a small number, even with the systemd

only has 8KB on-disk raw buffer, the md raid array udev rules can work

correctly without failure message.

Signed-off-by: Coly Li <colyli@suse.de>

Reviewed-by: NeilBrown <neilb@suse.com>

Signed-off-by: Jes Sorensen <jsorensen@fb.com>

---

 Detail.c | 24 ++++++++++++++++--------

 ReadMe.c |  1 +

 mdadm.c  |  4 ++++

 mdadm.h  |  2 ++

 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/Detail.c b/Detail.c

index 20ea03a..ad60434 100644

--- a/Detail.c

+++ b/Detail.c

@@ -56,7 +56,7 @@ int Detail(char *dev, struct context *c)

 	 */

 	int fd = open(dev, O_RDONLY);

 	mdu_array_info_t array;

-	mdu_disk_info_t *disks;

+	mdu_disk_info_t *disks = NULL;

 	int next;

 	int d;

 	time_t atime;

@@ -280,7 +280,7 @@ int Detail(char *dev, struct context *c)

 			}

 			map_free(map);

 		}

-		if (sra) {

+		if (!c->no_devices && sra) {

 			struct mdinfo *mdi;

 			for (mdi  = sra->devs; mdi; mdi = mdi->next) {

 				char *path;

@@ -655,12 +655,17 @@ This is pretty boring

 			printf("\n\n");

 		}

-		if (array.raid_disks)

-			printf("    Number   Major   Minor   RaidDevice State\n");

-		else

-			printf("    Number   Major   Minor   RaidDevice\n");

+		if (!c->no_devices) {

+			if (array.raid_disks)

+				printf("    Number   Major   Minor   RaidDevice State\n");

+			else

+				printf("    Number   Major   Minor   RaidDevice\n");

+		}

 	}

-	free(info);

+

+	/* if --no_devices specified, not print component devices info */

+	if (c->no_devices)

+		goto skip_devices_state;

 	for (d = 0; d < max_disks * 2; d++) {

 		char *dv;

@@ -747,6 +752,8 @@ This is pretty boring

 		if (!c->brief)

 			printf("\n");

 	}

+

+skip_devices_state:

 	if (spares && c->brief && array.raid_disks)

 		printf(" spares=%d", spares);

 	if (c->brief && st && st->sb)

@@ -766,8 +773,9 @@ This is pretty boring

 	    !enough(array.level, array.raid_disks, array.layout, 1, avail))

 		rv = 2;

-	free(disks);

 out:

+	free(info);

+	free(disks);

 	close(fd);

 	free(subarray);

 	free(avail);

diff --git a/ReadMe.c b/ReadMe.c

index 12ccf83..eaf1042 100644

--- a/ReadMe.c

+++ b/ReadMe.c

@@ -181,6 +181,7 @@ struct option long_options[] = {

     /* For Detail/Examine */

     {"brief",	  0, 0, Brief},

+    {"no-devices",0, 0, NoDevices},

     {"export",	  0, 0, 'Y'},

     {"sparc2.2",  0, 0, Sparc22},

     {"test",      0, 0, 't'},

diff --git a/mdadm.c b/mdadm.c

index 25a1abd..1fb8086 100644

--- a/mdadm.c

+++ b/mdadm.c

@@ -159,6 +159,10 @@ int main(int argc, char *argv[])

 			c.brief = 1;

 			continue;

+		case NoDevices:

+			c.no_devices = 1;

+			continue;

+

 		case 'Y': c.export++;

 			continue;

diff --git a/mdadm.h b/mdadm.h

index d61a9ca..43b07d5 100644

--- a/mdadm.h

+++ b/mdadm.h

@@ -440,6 +440,7 @@ enum special_options {

 	NoSharing,

 	HelpOptions,

 	Brief,

+	NoDevices,

 	ManageOpt,

 	Add,

 	AddSpare,

@@ -550,6 +551,7 @@ struct context {

 	int	runstop;

 	int	verbose;

 	int	brief;

+	int	no_devices;

 	int	force;

 	char	*homehost;

 	int	require_homehost;

-- 

2.7.5