[SCSI] scsi_transport_fc: Remove capping from dev_loss_tmo
authorHannes Reinecke <hare@suse.de>
Tue, 15 Dec 2009 08:26:06 +0000 (09:26 +0100)
committerJames Bottomley <James.Bottomley@suse.de>
Mon, 18 Jan 2010 16:48:09 +0000 (10:48 -0600)
commitf2818663c82b7297ff4aa38cbddb870dc02f7104
treeff088e90961a99d664a8923e48ef69d6289d48e2
parente47c11c7a402a054a85cb917a6ed020f6b5fae04
[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>
drivers/scsi/scsi_transport_fc.c