[SCSI] Handle disk devices which can not process medium access commands
We have experienced several devices which fail in a fashion we do not
currently handle gracefully in SCSI. After a failure these devices will
respond to the SCSI primary command set (INQUIRY, TEST UNIT READY, etc.)
but any command accessing the storage medium will time out.
The following patch adds an callback that can be used by upper level
drivers to inspect the results of an error handling command. This in
turn has been used to implement additional checking in the SCSI disk
driver.
If a medium access command fails twice but TEST UNIT READY succeeds both
times in the subsequent error handling we will offline the device. The
maximum number of failed commands required to take a device offline can
be tweaked in sysfs.
Also add a new error flag to scsi_debug which allows this scenario to be
easily reproduced.
[jejb: fix up integer parsing to use kstrtouint]
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index d2fd0ef..8917154 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -126,6 +126,7 @@
#define SCSI_DEBUG_OPT_TRANSPORT_ERR 16
#define SCSI_DEBUG_OPT_DIF_ERR 32
#define SCSI_DEBUG_OPT_DIX_ERR 64
+#define SCSI_DEBUG_OPT_MAC_TIMEOUT 128
/* When "every_nth" > 0 then modulo "every_nth" commands:
* - a no response is simulated if SCSI_DEBUG_OPT_TIMEOUT is set
* - a RECOVERED_ERROR is simulated on successful read and write
@@ -3615,6 +3616,9 @@
scsi_debug_every_nth = -1;
if (SCSI_DEBUG_OPT_TIMEOUT & scsi_debug_opts)
return 0; /* ignore command causing timeout */
+ else if (SCSI_DEBUG_OPT_MAC_TIMEOUT & scsi_debug_opts &&
+ scsi_medium_access_command(SCpnt))
+ return 0; /* time out reads and writes */
else if (SCSI_DEBUG_OPT_RECOVERED_ERR & scsi_debug_opts)
inj_recovered = 1; /* to reads and writes below */
else if (SCSI_DEBUG_OPT_TRANSPORT_ERR & scsi_debug_opts)