On 06/02/2014 04:36 AM, NeilBrown wrote:
> On Fri, 30 May 2014 15:18:33 +0200 Artur Paszkiewicz
> <artur.paszkiewicz@xxxxxxxxx> wrote:
>
>> If the checksum verification fails in mdadm and mdmon is running, retry
>> the load to get a consistent snapshot of the mpb.
>>
>> Based on db575f3b
>>
>> Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
>> Reviewed-by: Pawel Baldysiak <pawel.baldysiak@xxxxxxxxx>
>> ---
>> super-intel.c | 17 +++++++++++++++++
>> 1 file changed, 17 insertions(+)
>>
>> diff --git a/super-intel.c b/super-intel.c
>> index f0a7ab5..037c018 100644
>> --- a/super-intel.c
>> +++ b/super-intel.c
>> @@ -4422,6 +4422,7 @@ static int load_super_imsm(struct supertype *st, int fd, char *devname)
>> {
>> struct intel_super *super;
>> int rv;
>> + int retry;
>>
>> if (test_partition(fd))
>> /* IMSM not allowed on partitions */
>> @@ -4444,6 +4445,22 @@ static int load_super_imsm(struct supertype *st, int fd, char *devname)
>> }
>> rv = load_and_parse_mpb(fd, super, devname, 0);
>>
>> + /* retry the load if we might have raced against mdmon */
>> + if (rv == 3) {
>> + struct mdstat_ent *mdstat = mdstat_by_component(fd2devnm(fd));
>> +
>> + if (mdmon_running(mdstat->devnm) && getpid() != mdmon_pid(mdstat->devnm)) {
>> + for (retry = 0; retry < 3; retry++) {
>> + usleep(3000);
>> + rv = load_and_parse_mpb(fd, super, devname, 0);
>> + if (rv != 3)
>> + break;
>> + }
>> + }
>
> The only thing you use from mdstat is devnm, and that is the thing you passed
> to mdstat_by_component to get mdstat....
>
> Can you just do
> char *devnm = fd2devnm(fd);
> if (mdmon_running(devnm) && ......)
>
> ??
>
I can't do that because mdmon_running and mdmon_pid need a devnm of a
container device, and the only thing we have here is the file descriptor
of a component device. So I used mdstat_by_component to get the
container devnm. Do you have an idea how to get that reliably without
reading mdstat?
I have overlooked that mdstat_by_component can return NULL here. I've
added a check for this in the patch below.
Thanks,
Artur
>From dfb12870a482654b405ec1d4d9d3a8ba69a6290c Mon Sep 17 00:00:00 2001
From: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
Date: Tue, 27 May 2014 15:30:54 +0200
Subject: [PATCH] imsm: retry load_and_parse_mpb if we suspect mdmon has made
modifications
If the checksum verification fails in mdadm and mdmon is running, retry
the load to get a consistent snapshot of the mpb.
Based on db575f3b
Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
---
super-intel.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/super-intel.c b/super-intel.c
index f0a7ab5..9dd807a 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -4422,6 +4422,7 @@ static int load_super_imsm(struct supertype *st, int fd, char *devname)
{
struct intel_super *super;
int rv;
+ int retry;
if (test_partition(fd))
/* IMSM not allowed on partitions */
@@ -4444,6 +4445,22 @@ static int load_super_imsm(struct supertype *st, int fd, char *devname)
}
rv = load_and_parse_mpb(fd, super, devname, 0);
+ /* retry the load if we might have raced against mdmon */
+ if (rv == 3) {
+ struct mdstat_ent *mdstat = mdstat_by_component(fd2devnm(fd));
+
+ if (mdstat && mdmon_running(mdstat->devnm) && getpid() != mdmon_pid(mdstat->devnm)) {
+ for (retry = 0; retry < 3; retry++) {
+ usleep(3000);
+ rv = load_and_parse_mpb(fd, super, devname, 0);
+ if (rv != 3)
+ break;
+ }
+ }
+
+ free_mdstat(mdstat);
+ }
+
if (rv) {
if (devname)
pr_err("Failed to load all information "
--
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