1
linux/include/scsi
Mike Christie a4dfaa6f2e [SCSI] scsi: add transport host byte errors (v3)
Currently, if there is a transport problem the iscsi drivers will return
outstanding commands (commands being exeucted by the driver/fw/hw) with
DID_BUS_BUSY and block the session so no new commands can be queued.
Commands that are caught between the failure handling and blocking are
failed with DID_IMM_RETRY or one of the scsi ml queuecommand return values.
When the recovery_timeout fires, the iscsi drivers then fail IO with
DID_NO_CONNECT.

For fcp, some drivers will fail some outstanding IO (disk but possibly not
tape) with DID_BUS_BUSY or DID_ERROR or some other value that causes a retry
and hits the scsi_error.c failfast check, block the rport, and commands
caught in the race are failed with DID_IMM_RETRY. Other drivers, may
hold onto all IO and wait for the terminate_rport_io or dev_loss_tmo_callbk
to be called.

The following patches attempt to unify what upper layers will see drivers
like multipath can make a good guess. This relies on drivers being
hooked into their transport class.

This first patch just defines two new host byte errors so drivers can
return the same value for when a rport/session is blocked and for
when the fast_io_fail_tmo fires.

The idea is that if the LLD/class detects a problem and is going to block
a rport/session, then if the LLD wants or must return the command to scsi-ml,
then it can return it with DID_TRANSPORT_DISRUPTED. This will requeue
the IO into the same scsi queue it came from, until the fast io fail timer
fires and the class decides what to do.

When using multipath and the fast_io_fail_tmo fires then the class
can fail commands with DID_TRANSPORT_FAILFAST or drivers can use
DID_TRANSPORT_FAILFAST in their terminate_rport_io callbacks or
the equivlent in iscsi if we ever implement more advanced recovery methods.
A LLD, like lpfc, could continue to return DID_ERROR and then it will hit
the normal failfast path, so drivers do not have fully be ported to
work better. The point of the patches is that upper layers will
not see a failure that could be recovered from while the rport/session is
blocked until fast_io_fail_tmo/recovery_timeout fires.

V3
Remove some comments.
V2
Fixed patch/diff errors and renamed DID_TRANSPORT_BLOCKED to
DID_TRANSPORT_DISRUPTED.
V1
initial patch.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-10-13 09:28:48 -04:00
..
iscsi_if.h [SCSI] iscsi class: Add session initiatorname and ifacename sysfs attrs. 2008-07-12 08:22:21 -05:00
iscsi_proto.h [SCSI] iscsi_tcp: Enable any size command 2008-07-12 08:22:23 -05:00
libiscsi.h [SCSI] libiscsi, iser, tcp: remove recv_lock 2008-07-12 08:22:22 -05:00
libsas.h include: Remove unnecessary inclusions of asm/semaphore.h 2008-04-18 22:16:54 -04:00
libsrp.h [SCSI] tgt: convert libsrp and ibmvstgt to use srp_transport 2007-10-12 14:37:57 -04:00
sas_ata.h [SCSI] libsas: fix missing inlines in header file 2008-04-07 12:19:10 -05:00
sas.h [SCSI] libsas: Convert sas_proto users to sas_protocol 2008-01-11 18:22:41 -06:00
scsi_cmnd.h block: unify request timeout handling 2008-10-09 08:56:13 +02:00
scsi_dbg.h [SCSI] Fix device not ready printk 2007-10-12 14:51:56 -04:00
scsi_device.h [SCSI] Add helper code so transport classes/driver can control queueing (v3) 2008-10-13 09:28:46 -04:00
scsi_devinfo.h
scsi_dh.h [SCSI] scsi_dh: attach to hardware handler from dm-mpath 2008-07-26 15:14:53 -04:00
scsi_driver.h Revert "scsi: revert "[SCSI] Get rid of scsi_cmnd->done"" 2008-01-06 10:17:12 -08:00
scsi_eh.h [SCSI] scsi_eh_prep_cmnd should save scmd->underflow 2008-07-26 15:14:56 -04:00
scsi_host.h block: unify request timeout handling 2008-10-09 08:56:13 +02:00
scsi_ioctl.h
scsi_netlink_fc.h
scsi_netlink.h [SCSI] scsi_netlink: Add transport and LLD recieve and event support 2008-10-03 11:46:13 -05:00
scsi_tcq.h
scsi_tgt_if.h [SCSI] tgt: add I_T nexus support 2007-10-12 14:37:50 -04:00
scsi_tgt.h [SCSI] tgt: add I_T nexus support 2007-10-12 14:37:50 -04:00
scsi_transport_fc.h [SCSI] fc class: unblock target after calling terminate callback (take 2) 2008-10-13 09:28:47 -04:00
scsi_transport_iscsi.h driver core: remove KOBJ_NAME_LEN define 2008-07-21 21:54:52 -07:00
scsi_transport_sas.h SCSI: convert struct class_device to struct device 2008-04-19 19:10:33 -07:00
scsi_transport_spi.h
scsi_transport_srp.h [SCSI] tgt: move tsk_mgmt_response callback to transport class 2007-10-12 14:38:01 -04:00
scsi_transport.h block: unify request timeout handling 2008-10-09 08:56:13 +02:00
scsi.h [SCSI] scsi: add transport host byte errors (v3) 2008-10-13 09:28:48 -04:00
scsicam.h
sg.h [SCSI] sg: Add target reset support 2008-07-12 08:22:32 -05:00
srp.h