This fixes a bug in recent kernels which results in failure to boot
on systems that have multipath SCSI disks. I observed this failure
on a POWER8 server where all the disks are multipath SCSI disks.
The symptoms are several messages like this on the console:
[ 3.018700] device-mapper: table: 253:0: multipath: error attaching hardware handler
[ 3.018828] device-mapper: ioctl: error adding target to table
and the system does not find its disks, and therefore fails to boot.
Bisection revealed that the bug was introduced in commit 566079c849cf,
"dm-mpath, scsi_dh: request scsi_dh modules in scsi_dh, not dm-mpath".
The specific reason for the failure is that where we previously loaded
the "scsi_dh_alua" module, we are now trying to load the "alua" module,
which doesn't exist.
To fix this, we change the request_module call in scsi_dh_lookup()
to prepend "scsi_dh_" to the name, just like the old code in
drivers/md/dm-mpath.c:parse_hw_handler() used to do.
Fixes: 566079c849cf
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
---
drivers/scsi/scsi_dh.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index edb044a..0a2168e 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -111,7 +111,7 @@ static struct scsi_device_handler *scsi_dh_lookup(const char *name)
dh = __scsi_dh_lookup(name);
if (!dh) {
- request_module(name);
+ request_module("scsi_dh_%s", name);
dh = __scsi_dh_lookup(name);
}
--
2.1.4
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