|
Menny, Yes, I agree there is a
problem. Wouldn’t it be simpler if you could handle everything scsi_dh.c..
See my response below.. Thanks Babu From:
dm-devel-bounces@xxxxxxxxxx [mailto:dm-devel-bounces@xxxxxxxxxx] On Behalf Of Menny_Hamburger@xxxxxxxx When scsi_dh_activate
returns SCSI_DH_NOSYS the H/W handler callback is not called, pg_init_done is
not called in the multipath layer and
pending I/O is requeued forever; this situation causes all userland processes
currently performing I/O on the device to I/O hang. A
similar situation occurs when the device has transitioned to
SDEV_CANCEL/SDEV_DEL and the device handler data had not yet
been deleted. The easiest way to reproduce
this is in an ISCSI environment: dd if=/dev/dm-0
of=/dev/zero bs=8k count=1000000 & /etc/init.d/iscsi
stop In this example, dd will I/O
hang forever and the only way to release it will be to reboot the machine This patch calls pg_init_done
directly from the mpath code when the scsi_dh_activate returns a non SCSI_DH_OK
error. Note: The patch is over RHEL5.5. When running an upstream
kernel, the above scenario may not occur because the request queue is aborted
in dm-mpath.c:fail_path. This patch makes sure the
problem does not occur at all, rather than handling it when it does. In
addition, it seems too risky to apply request queue abort
functionality on RHEL5 at this stage. diff -r -U 2
a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c ---
a/drivers/md/dm-mpath.c 2010-12-13 09:16:31.358858000 +0200 +++
b/drivers/md/dm-mpath.c 2010-12-13 09:16:31.796998000 +0200 @@ -1190,4 +1190,5 @@
case SCSI_DH_OK:
break; +
case SCSI_DH_DEV_OFFLINED: If you
are not doing anything special then I would let default take care of it.
No need of this change..
case SCSI_DH_NOSYS:
if (!m->hw_handler_name) { @@ -1252,7 +1253,15 @@ {
struct pgpath *pgpath = (struct pgpath *) data; +
int err; -
scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev), +
err = scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev),
pg_init_done, &pgpath->path); + + /* + *
If error is not SCSI_DH_OK, we have not entered the scsi_dh H/W handler and did
not call pg_init_done - + *
need to call pg_init_done directly. + */ + if
(err) +
pg_init_done(&pgpath->path, err); } You can move this to scsi_dh.c diff -r -U 2
a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c ---
a/drivers/scsi/device_handler/scsi_dh.c 2010-12-13
09:16:31.616554000 +0200 +++ b/drivers/scsi/device_handler/scsi_dh.c
2010-12-13 09:16:31.878170000 +0200 @@ -443,4 +443,9 @@
spin_unlock_irqrestore(q->queue_lock, flags); + if
(sdev->sdev_state == SDEV_CANCEL || +
sdev->sdev_state == SDEV_DEL || +
sdev->sdev_state == SDEV_OFFLINE) +
err = SCSI_DH_DEV_OFFLINED; + You can
change it something like below..
if (err) {
if(fn) fn(data, err);
return err; } |
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