From: Menny Hamburger <Menny_Hamburger@xxxxxxxx> Currently, when scsi_dh_activate() returns with an error (e.g. SCSI_DH_NOSYS) the activate_complete callback is not called and the error is not propagated to DM mpath. When a SCSI device attached to a device handler is deleted, userland processes currently performing I/O on the device will have their I/O hang forever. - Set SCSI_DH_NOSYS error when the handler is in the process of being deleted (e.g. the SCSI device is in a SDEV_CANCEL or SDEV_DEL state). - Set SCSI_DH_DEV_OFFLINED error when device is in SDEV_OFFLINE state. - Call the activate_complete callback function directly from scsi_dh_activate if an error has been set (when either the scsi_dh internal data has already been deleted or is in the process of being deleted). The patch was tested in an iSCSI environment, RDAC H/W handler and multipath. In the following reproduction process, dd will I/O hang forever and the only way to release it will be to reboot the machine: 1) Perform I/O on a multipath device: dd if=/dev/dm-0 of=/dev/zero bs=8k count=1000000 & 2) Delete all slave SCSI devices contained in the mpath device: I) In an iSCSI environment, the easiest way to do this is by stopping iSCSI: /etc/init.d/iscsi stop II) Another way to delete the devices is by applying the following bash scriptlet: dm_devs=$(ls /sys/block/ | grep dm- | xargs) for dm_dev in $dm_devs; do devices=$(ls /sys/block/$dm_dev/slaves) for device in $devices; do echo 1 > /sys/block/$device/device/delete done done NOTE: when DM mpath's fail_path uses blk_abort_queue this scsi_dh change isn't strictly required. However, DM mpath's call to blk_abort_queue will soon be reverted because it has proven to be unsafe due to a race (between blk_abort_queue and scsi_request_fn) that can lead to list corruption. Therefore we cannot rely on blk_abort_queue via fail_path, but even if we could this scsi_dh change is still preferrable. Signed-off-by: Menny Hamburger <Menny_Hamburger@xxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- drivers/scsi/device_handler/scsi_dh.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) v1 and v2 were posted/discussed on dm-devel v3: just tweaked the patch header a bit diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index 6fae3d2..b0c56f6 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -442,12 +442,19 @@ int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data) sdev = q->queuedata; if (sdev && sdev->scsi_dh_data) scsi_dh = sdev->scsi_dh_data->scsi_dh; - if (!scsi_dh || !get_device(&sdev->sdev_gendev)) + if (!scsi_dh || !get_device(&sdev->sdev_gendev) || + sdev->sdev_state == SDEV_CANCEL || + sdev->sdev_state == SDEV_DEL) err = SCSI_DH_NOSYS; + if (sdev->sdev_state == SDEV_OFFLINE) + err = SCSI_DH_DEV_OFFLINED; spin_unlock_irqrestore(q->queue_lock, flags); - if (err) + if (err) { + if (fn) + fn(data, err); return err; + } if (scsi_dh->activate) err = scsi_dh->activate(sdev, fn, data); -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel