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Monitor: don't open md array that doesn't exist. 

Opening a block-special-device for an array that doesn't
exist causes that array to be instantiated (as an empty array).
Races at array shutdown can cause the array to spontaneously
re-appear if some deamon notices a 'change' event and goes
to investigate.

Teach "mdadm --monitor" to avoid this race by checking the
"array_state" before opening the device.

Reported-by: Francis Moreau <francis.moro@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2014-10-29 08:48:02 +11:00
parent 7ae0775871
commit 9a518d81fe
1 changed files with 22 additions and 1 deletions
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23
Monitor.c
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@ -460,7 +460,7 @@ static int check_array(struct state *st, struct mdstat_ent *mdstat,
mdu_array_info_t array;
struct mdstat_ent *mse = NULL, *mse2;
char *dev = st->devname;
int fd;
int fd = -1;
int i;
int remaining_disks;
int last_disk;
@ -468,6 +468,27 @@ static int check_array(struct state *st, struct mdstat_ent *mdstat,
if (test)
alert("TestMessage", dev, NULL, ainfo);
if (st->devnm[0])
fd = open("/sys/block", O_RDONLY|O_DIRECTORY);
if (fd >= 0) {
/* Don't open the device unless it is present and
* active in sysfs.
*/
char buf[10];
close(fd);
fd = sysfs_open(st->devnm, NULL, "array_state");
if (fd < 0 ||
read(fd, buf, 10) < 5 ||
strncmp(buf,"clear",5) == 0 ||
strncmp(buf,"inact",5) == 0) {
if (fd >= 0)
close(fd);
if (!st->err)
alert("DeviceDisappeared", dev, NULL, ainfo);
st->err++;
return 0;
}
}
fd = open(dev, O_RDONLY);
if (fd < 0) {
if (!st->err)