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  1. 13 Oct, 2008 8 commits
    • Mike Christie's avatar
      [SCSI] scsi: add transport host byte errors (v3) · a4dfaa6f
      Mike Christie authored 
      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: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      a4dfaa6f
    • Mike Christie's avatar
      [SCSI] ibmvfc, qla2xxx, lpfc: remove scsi_target_unblock calls in terminate callbacks · 9cc328f5
      Mike Christie authored 
      The fc class now calls scsi_target_unblock after calling the
terminate callback, so this patch removes the calls from the
drivers.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      9cc328f5
    • Mike Christie's avatar
      [SCSI] fc class: unblock target after calling terminate callback (take 2) · fff9d40c
      Mike Christie authored 
      When we block a rport and the driver implements the terminate
callback we will fail IO that was running quickly. However
IO that was in the scsi_device/block queue sits there until
the dev_loss_tmo fires, and this can make it look like IO is
lost because new IO will get executed but that IO stuck in
the blocked queue sits there for some time longer.

With this patch when the fast io fail tmo fires, we will
fail the blocked IO and any new IO. This patch also allows
all drivers to partially support the fast io fail tmo. If the
terminate io callback is not implemented, we will still fail blocked
IO and any new IO, so multipath can handle that.

This patch also allows the fc and iscsi classes to implement the
same behavior. The timers are just unfornately named differently.

This patch also fixes the problem where drivers were unblocking
the target in their terminate callback, which was needed for
rport removal, but for fast io fail timeout it would cause
IO to bounce arround the scsi/block layer and the LLD queuecommand.
And it for drivers that could have IO stuck but did not have
a terminate callback the unblock calls in the class will fix
them.

v2.
- fix up bit setting style to meet JamesS's pref.
- Broke out new host byte error changes to make it easier to read.
- added JamesS's ack from list.
v1
- initial patch
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarJames Smart <James.Smart@emulex.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      fff9d40c
    • Mike Christie's avatar
      [SCSI] lpfc: use SCSI_MLQUEUE_TARGET_BUSY when catching the rport transition race · a93ce024
      Mike Christie authored 
      We do want to call right back into the queuecommand during the race,
so we can just use SCSI_MLQUEUE_TARGET_BUSY.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarJames Smart <James.Smart@Emulex.Com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      a93ce024
    • Mike Christie's avatar
      [SCSI] libiscsi: Use SCSI_MLQUEUE_TARGET_BUSY · d6d13ee1
      Mike Christie authored 
      For the conditions below we do not want the queuecommand
function to call us right back, so return SCSI_MLQUEUE_TARGET_BUSY.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      d6d13ee1
    • Mike Christie's avatar
      [SCSI] qla2xxx: return SCSI_MLQUEUE_TARGET_BUSY when driver has detected rport error or race · 7b594131
      Mike Christie authored 
      If the fcport is not online then we do not want to block IO to all ports on
the host. We just want to stop IO on port not online, so we should be using
the SCSI_MLQUEUE_TARGET_BUSY return value.

For the case where we race with the rport memset initialization
we do not want the queuecommand to be called again so we can just use
SCSI_MLQUEUE_TARGET_BUSY for this.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarAndrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      7b594131
    • Mike Christie's avatar
      [SCSI] qla4xxx: return SCSI_MLQUEUE_TARGET_BUSY when driver has detected session error · c5e98e91
      Mike Christie authored 
      When qla4xxx begins recovery and the iscsi class is firing up to handle
it, we need to retrn SCSI_MLQUEUE_TARGET_BUSY from the driver instead
of host busy, because the session recovery only affects the one target.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Acked-by: default avatarDavid C Somayajulu <david.somayajulu@qlogic.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      c5e98e91
    • Mike Christie's avatar
      [SCSI] Add helper code so transport classes/driver can control queueing (v3) · f0c0a376
      Mike Christie authored 
      SCSI-ml manages the queueing limits for the device and host, but
does not do so at the target level. However something something similar
can come in userful when a driver is transitioning a transport object to
the the blocked state, becuase at that time we do not want to queue
io and we do not want the queuecommand to be called again.

The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers.
You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit
a transport level queueing issue like the hw cannot allocate some
resource at the iscsi session/connection level, or the target has temporarily
closed or shrunk the queueing window, or if we are transitioning
to the blocked state.

bnx2i, when they rework their firmware according to netdev
developers requests, will also need to be able to limit queueing at this
level. bnx2i will hook into libiscsi, but will allocate a scsi host per
netdevice/hba, so unlike pure software iscsi/iser which is allocating
a host per session, it cannot set the scsi_host->can_queue and return
SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport.

The iscsi class/driver can also set a scsi_target->can_queue value which
reflects the max commands the driver/class can support. For iscsi this
reflects the number of commands we can support for each session due to
session/connection hw limits, driver limits, and to also reflect the
session/targets's queueing window.

Changes:
v1 - initial patch.
v2 - Fix scsi_run_queue handling of multiple blocked targets.
Previously we would break from the main loop if a device was added back on
the starved list. We now run over the list and check if any target is
blocked.
v3 - Rediff for scsi-misc.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      f0c0a376
  3. 12 Oct, 2008 32 commits
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