The ability to modify the SCSI device state was introduced by commit
638127e579a4 ("[PATCH] Fix error handler offline behaviour"; v2.6.12). That
same commit introduced the following device states:
{ SDEV_CREATED, "created" },
{ SDEV_RUNNING, "running" },
{ SDEV_CANCEL, "cancel" },
{ SDEV_DEL, "deleted" },
{ SDEV_QUIESCE, "quiesce" },
{ SDEV_OFFLINE, "offline" },
The SDEV_BLOCK state was introduced later to avoid that an FC cable pull
would immediately result in an I/O error (commit 1094e682310e; "[PATCH]
suspending I/Os to a device"; v2.6.12). That same patch introduced the
ability to set the SDEV_BLOCK state from user space. I'm not sure whether
that ability was introduced on purpose or accidentally.
This patch makes sure that SDEV_BLOCK is only used for its original
purpose, namely to allow transport drivers and LLDs to block further
.queuecommand() calls while transport layer or adapter recovery is in
progress.
Notes:
- While SDEV_BLOCK blocks all SCSI commands, in the SDEV_QUIESCE
state only those block layer requests are blocked for which RQF_PREEMPT
has not been set. RQF_PREEMPT is not set for I/O requests submitted by
e.g. a filesystem but is set for all requests pass-through requests.
See also __scsi_execute().
- By doing a web search for ("blocked" OR "quiesce") AND
"/sys/class/scsi_device" AND "device/state" I found several storage
configuration guides. The instructions I found in these guides
tell users to write the value "running" or "offline" in the SCSI
device state sysfs attribute and no other values.
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: James Smart <james.smart@xxxxxxxxxxxx>
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
drivers/scsi/scsi_sysfs.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ff0aea7ac87f..a49ee113b3c4 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -769,6 +769,13 @@ store_state_field(struct device *dev, struct device_attribute *attr,
}
if (!state)
return -EINVAL;
+ /*
+ * The state SDEV_BLOCK should not be set from userspace. Translate
+ * SDEV_BLOCK into SDEV_QUIESCE in case the SDEV_BLOCK state transition
+ * is requested from user space.
+ */
+ if (state == SDEV_BLOCK)
+ state = SDEV_QUIESCE;
mutex_lock(&sdev->state_mutex);
ret = scsi_device_set_state(sdev, state);
--
2.22.0.rc3
