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@xxxxxxx>
Cc: Neil Brown <neilb@xxxxxxxx>
---
Detail.c | 17 +++++++++++++----
ReadMe.c | 1 +
mdadm.c | 4 ++++
mdadm.h | 2 ++
4 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/Detail.c b/Detail.c
index 20ea03a..879ca3b 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 +280,8 @@ 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;
@@ -654,18 +655,23 @@ This is pretty boring
closedir(dir);
printf("\n\n");
}
+ }
+ if (!c->no_devices && !c->brief) {
if (array.raid_disks)
printf(" Number Major Minor RaidDevice State\n");
else
printf(" Number Major Minor RaidDevice\n");
}
- free(info);
for (d = 0; d < max_disks * 2; d++) {
char *dv;
mdu_disk_info_t disk = disks[d];
+ /* if --no_devices specified, quit devices iteration loop */
+ if (c->no_devices)
+ break;
+
if (d >= array.raid_disks * 2 &&
disk.major == 0 && disk.minor == 0)
continue;
@@ -766,8 +772,11 @@ This is pretty boring
!enough(array.level, array.raid_disks, array.layout, 1, avail))
rv = 2;
- free(disks);
out:
+ if (disks)
+ free(disks);
+ if (info)
+ free(info);
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 c36d7fd..e96f271 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -442,6 +442,7 @@ enum special_options {
NoSharing,
HelpOptions,
Brief,
+ NoDevices,
ManageOpt,
Add,
AddSpare,
@@ -552,6 +553,7 @@ struct context {
int runstop;
int verbose;
int brief;
+ int no_devices;
int force;
char *homehost;
int require_homehost;
--
2.16.4
