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authorHannes Reinecke <hare@suse.de>2009-12-15 09:26:06 +0100
committerJames Bottomley <James.Bottomley@suse.de>2010-01-18 10:48:09 -0600
commitf2818663c82b7297ff4aa38cbddb870dc02f7104 (patch)
treeff088e90961a99d664a8923e48ef69d6289d48e2
parente47c11c7a402a054a85cb917a6ed020f6b5fae04 (diff)
[SCSI] scsi_transport_fc: Remove capping from dev_loss_tmo
Currently dev_loss_tmo is capped by SCSI_DEVICE_BLOCK_MAX_TIMEOUT. This causes problem with multipathing when the 'no_path_retry' setting exceeds the dev_loss_tmo setting, as then the system might run into a deadlock when all paths have been removed temporarily for longer than dev_loss_tmo. The principal reasons for the capping has been that we should not allow a remote port to remain in status 'blocked' indefinitely, so the capping is there to ensure that the port status is being reset eventually. However, the fast_io_fail_tmo will also move the remote port out of the 'blocked' state, so for any HBA driver implementing both the capping should really be on the fast_io_fail_tmo, and not on the dev_loss_tmo. This patch implements just that, ie the fast_io_fail_tmo is capped to SCSI_DEVICE_BLOCK_TIMEOUT and the capping is removed from dev_loss_tmo when fast_io_fail_tmo is set. This allows us to synchronize the dev_loss_tmo setting to the 'no_path_retry' setting from multipathing thus avoiding the deadlock. Signed-off-by: Hannes Reinecke <hare@suse.de> Acked-by: James Smart <james.smart@emulex.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
-rw-r--r--drivers/scsi/scsi_transport_fc.c26
1 files changed, 21 insertions, 5 deletions
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 653f22a8deb..79660ee3e21 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -475,7 +475,8 @@ MODULE_PARM_DESC(dev_loss_tmo,
"Maximum number of seconds that the FC transport should"
" insulate the loss of a remote port. Once this value is"
" exceeded, the scsi target is removed. Value should be"
- " between 1 and SCSI_DEVICE_BLOCK_MAX_TIMEOUT.");
+ " between 1 and SCSI_DEVICE_BLOCK_MAX_TIMEOUT if"
+ " fast_io_fail_tmo is not set.");
/*
* Netlink Infrastructure
@@ -842,9 +843,17 @@ store_fc_rport_dev_loss_tmo(struct device *dev, struct device_attribute *attr,
(rport->port_state == FC_PORTSTATE_NOTPRESENT))
return -EBUSY;
val = simple_strtoul(buf, &cp, 0);
- if ((*cp && (*cp != '\n')) ||
- (val < 0) || (val > SCSI_DEVICE_BLOCK_MAX_TIMEOUT))
+ if ((*cp && (*cp != '\n')) || (val < 0))
return -EINVAL;
+
+ /*
+ * If fast_io_fail is off we have to cap
+ * dev_loss_tmo at SCSI_DEVICE_BLOCK_MAX_TIMEOUT
+ */
+ if (rport->fast_io_fail_tmo == -1 &&
+ val > SCSI_DEVICE_BLOCK_MAX_TIMEOUT)
+ return -EINVAL;
+
i->f->set_rport_dev_loss_tmo(rport, val);
return count;
}
@@ -925,9 +934,16 @@ store_fc_rport_fast_io_fail_tmo(struct device *dev,
rport->fast_io_fail_tmo = -1;
else {
val = simple_strtoul(buf, &cp, 0);
- if ((*cp && (*cp != '\n')) ||
- (val < 0) || (val >= rport->dev_loss_tmo))
+ if ((*cp && (*cp != '\n')) || (val < 0))
return -EINVAL;
+ /*
+ * Cap fast_io_fail by dev_loss_tmo or
+ * SCSI_DEVICE_BLOCK_MAX_TIMEOUT.
+ */
+ if ((val >= rport->dev_loss_tmo) ||
+ (val > SCSI_DEVICE_BLOCK_MAX_TIMEOUT))
+ return -EINVAL;
+
rport->fast_io_fail_tmo = val;
}
return count;