linux.git/drivers/scsi/scsi_error.c, branch v3.14

[SCSI] Set the minimum valid value of 'eh_deadline' as 0

2013-12-19T15:39:02+00:00

The former minimum valid value of 'eh_deadline' is 1s, which means
the earliest occasion to shorten EH is 1 second later since a
command is failed or timed out. But if we want to skip EH steps
ASAP, we have to wait until the first EH step is finished. If the
duration of the first EH step is long, this waiting time is
excruciating. So, it is necessary to accept 0 as the minimum valid
value for 'eh_deadline'.

According to my test, with Hannes' patchset 'New EH command timeout
handler' as well, the minimum IO time is improved from 73s
(eh_deadline = 1) to 43s(eh_deadline = 0) when commands are timed
out by disabling RSCN and target port.

Signed-off-by: Ren Mingxin 
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Unlock accesses to eh_deadline

2013-12-19T15:39:02+00:00

32bit accesses are guaranteed to be atomic, so we can remove
the spinlock when checking for eh_deadline. We only need to
make sure to catch any updates which might happened during
the call to time_before(); if so we just recheck with the
correct value.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] improved eh timeout handler

2013-12-19T15:39:02+00:00

When a command runs into a timeout we need to send an 'ABORT TASK'
TMF. This is typically done by the 'eh_abort_handler' LLDD callback.

Conceptually, however, this function is a normal SCSI command, so
there is no need to enter the error handler.

This patch implements a new scsi_abort_command() function which
invokes an asynchronous function scsi_eh_abort_handler() to
abort the commands via the usual 'eh_abort_handler'.

If abort succeeds the command is either retried or terminated,
depending on the number of allowed retries. However, 'eh_eflags'
records the abort, so if the retry would fail again the
command is pushed onto the error handler without trying to
abort it (again); it'll be cleared up from SCSI EH.

[hare: smatch detected stray switch fixed]
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Fix erratic device offline during EH

2013-12-19T15:39:02+00:00

Commit 18a4d0a22ed6c54b67af7718c305cd010f09ddf8
(Handle disk devices which can not process medium access commands)
was introduced to offline any device which cannot process medium
access commands.
However, commit 3eef6257de48ff84a5d98ca533685df8a3beaeb8
(Reduce error recovery time by reducing use of TURs) reduced
the number of TURs by sending it only on the first failing
command, which might or might not be a medium access command.
So in combination this results in an erratic device offlining
during EH; if the command where the TUR was sent upon happens
to be a medium access command the device will be set offline,
if not everything proceeds as normal.

This patch moves the check to the final test, eliminating
this problem.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] scsi_error: Escalate to LUN reset if abort fails

2013-10-25T11:18:30+00:00

If a command abort fails there is a fair chance that all other
aborts will be failing, too.
So we should be calling LUN reset directly after the first failed
abort and skip aborting the remaining commands.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Add 'eh_deadline' to limit SCSI EH runtime

2013-10-25T11:17:59+00:00

This patchs adds an 'eh_deadline' sysfs attribute to the scsi
host which limits the overall runtime of the SCSI EH.
The 'eh_deadline' value is stored in the now obsolete field
'resetting'.
When a command is failed the start time of the EH is stored
in 'last_reset'. If the overall runtime of the SCSI EH is longer
than last_reset + eh_deadline, the EH is short-circuited and
falls through to issue a host reset only.

[jejb: add comments in Scsi_Host about new fields]
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Generate uevents on certain unit attention codes

2013-08-26T14:52:27+00:00

Generate a uevent when the following Unit Attention ASC/ASCQ
codes are received:

    2A/01  MODE PARAMETERS CHANGED
    2A/09  CAPACITY DATA HAS CHANGED
    38/07  THIN PROVISIONING SOFT THRESHOLD REACHED
    3F/03  INQUIRY DATA HAS CHANGED
    3F/0E  REPORTED LUNS DATA HAS CHANGED

Log kernel messages when the following Unit Attention ASC/ASCQ
codes are received that are not as specific as those above:

    2A/xx  PARAMETERS CHANGED
    3F/xx  TARGET OPERATING CONDITIONS HAVE CHANGED

Added logic to set expecting_lun_change for other LUNs on the target
after REPORTED LUNS DATA HAS CHANGED is received, so that duplicate
uevents are not generated, and clear expecting_lun_change when a
REPORT LUNS command completes, in accordance with the SPC-3
specification regarding reporting of the 3F 0E ASC/ASCQ UA.

[jejb: remove SPC3 test in scsi_report_lun_change and some docbook fixes and
       unused variable fix, both reported by Fengguang Wu]
Signed-off-by: Ewan D. Milne 
Signed-off-by: James Bottomley

[SCSI] Return ENODATA on medium error

2013-08-23T16:54:53+00:00

When a medium error is detected the SCSI stack should return
ENODATA to the upper layers.

[jejb: fix whitespace error]
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] return ENOSPC on thin provisioning failure

2013-08-23T16:43:54+00:00

When the thin provisioning hard threshold is reached we
should return ENOSPC to inform upper layers about this fact.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] Set hostbyte status in scsi_check_sense()

2013-08-23T16:34:56+00:00

We should be modifying the host_byte status in scsi_check_sense()
directly; this saves us to introduce a special return code for
each and every condition.

Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley