From f2818663c82b7297ff4aa38cbddb870dc02f7104 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Tue, 15 Dec 2009 09:26:06 +0100 Subject: [PATCH] [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 Acked-by: James Smart Signed-off-by: James Bottomley --- drivers/scsi/scsi_transport_fc.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c index 653f22a8deb9..79660ee3e211 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;