On Tue, Mar 17, 2026 at 12:07:03PM +0000, John Garry wrote:
> For when no device handler is used, add ALUA support.
>
> This will be equivalent to when native SCSI multipathing is used.
>
> Essentially all the same handling is available as DH alua driver for
> rescan, request prep, sense handling.
>
> Signed-off-by: John Garry <[email protected]>
> ---
> drivers/scsi/scsi_alua.c | 93 +++++++++++++++++++++++++++++++++++++++
> drivers/scsi/scsi_error.c | 7 +++
> drivers/scsi/scsi_lib.c | 7 +++
> drivers/scsi/scsi_scan.c | 2 +
> drivers/scsi/scsi_sysfs.c | 4 +-
> include/scsi/scsi_alua.h | 14 ++++++
> 6 files changed, 126 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_alua.c b/drivers/scsi/scsi_alua.c
> index d3fcd887e5018..ee0229b1a9d12 100644
> --- a/drivers/scsi/scsi_alua.c
> +++ b/drivers/scsi/scsi_alua.c
> @@ -562,6 +562,90 @@ int scsi_alua_stpg_run(struct scsi_device *sdev, bool
> optimize)
> }
> EXPORT_SYMBOL_GPL(scsi_alua_stpg_run);
>
> +enum scsi_disposition scsi_alua_check_sense(struct scsi_device *sdev,
> + struct scsi_sense_hdr *sense_hdr)
This seems like it should be shareable with scsi_dh_alua as well. In
might need to take a function to call for rescanning and have
alua_check_sense() be a wrapper around it, but since the force argument
to alua_check() is now always set to true in scsi_dh_alua, it's
unnecessary, so both it and scsi_device_alua_rescan() can have the
same arguments.
> +{
> + switch (sense_hdr->sense_key) {
> + case NOT_READY:
> + if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
> + /*
> + * LUN Not Accessible - ALUA state transition
> + */
> + scsi_alua_handle_state_transition(sdev);
> + return NEEDS_RETRY;
> + }
> + break;
> + case UNIT_ATTENTION:
> + if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) {
> + /*
> + * LUN Not Accessible - ALUA state transition
> + */
> + scsi_alua_handle_state_transition(sdev);
> + return NEEDS_RETRY;
> + }
> + if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) {
> + /*
> + * Power On, Reset, or Bus Device Reset.
> + * Might have obscured a state transition,
> + * so schedule a recheck.
> + */
> + scsi_device_alua_rescan(sdev);
> + return ADD_TO_MLQUEUE;
> + }
> + if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04)
> + /*
> + * Device internal reset
> + */
> + return ADD_TO_MLQUEUE;
> + if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01)
> + /*
> + * Mode Parameters Changed
> + */
> + return ADD_TO_MLQUEUE;
> + if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) {
> + /*
> + * ALUA state changed
> + */
> + scsi_device_alua_rescan(sdev);
> + return ADD_TO_MLQUEUE;
> + }
> + if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) {
> + /*
> + * Implicit ALUA state transition failed
> + */
> + scsi_device_alua_rescan(sdev);
> + return ADD_TO_MLQUEUE;
> + }
> + if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03)
> + /*
> + * Inquiry data has changed
> + */
> + return ADD_TO_MLQUEUE;
> + if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e)
> + /*
> + * REPORTED_LUNS_DATA_HAS_CHANGED is reported
> + * when switching controllers on targets like
> + * Intel Multi-Flex. We can just retry.
> + */
> + return ADD_TO_MLQUEUE;
> + break;
> + }
> +
> + return SCSI_RETURN_NOT_HANDLED;
> +}
> +
> +static void alua_rtpg_work(struct work_struct *work)
> +{
> + struct alua_data *alua =
> + container_of(work, struct alua_data, work.work);
> + int ret;
> +
> + ret = scsi_alua_rtpg_run(alua->sdev);
> +
> + if (ret == -EAGAIN)
> + queue_delayed_work(kalua_wq, &alua->work, alua->interval * HZ);
> +}
> +
> int scsi_alua_sdev_init(struct scsi_device *sdev)
> {
> int rel_port, ret, tpgs;
> @@ -591,6 +675,7 @@ int scsi_alua_sdev_init(struct scsi_device *sdev)
> goto out_free_data;
> }
>
> + INIT_DELAYED_WORK(&sdev->alua->work, alua_rtpg_work);
> sdev->alua->sdev = sdev;
> sdev->alua->tpgs = tpgs;
> spin_lock_init(&sdev->alua->lock);
> @@ -638,6 +723,14 @@ bool scsi_device_alua_implicit(struct scsi_device *sdev)
> return sdev->alua->tpgs & TPGS_MODE_IMPLICIT;
> }
>
> +void scsi_device_alua_rescan(struct scsi_device *sdev)
> +{
> + struct alua_data *alua = sdev->alua;
> +
> + queue_delayed_work(kalua_wq, &alua->work,
> + msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS));
This code doesn't support triggering a new rtpg while the current one is
running. I'll leave it to people with more scsi expertise to say how
important that is, but the scsi_dh_alua code now will always trigger a
new rtpg in this case (or at least it would, with the issues from patch
12 fixed).
-Ben
> +}
> +
> int scsi_alua_init(void)
> {
> kalua_wq = alloc_workqueue("kalua", WQ_MEM_RECLAIM | WQ_PERCPU, 0);
> diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
> index 147127fb4db9c..a542e7a85a24d 100644
> --- a/drivers/scsi/scsi_error.c
> +++ b/drivers/scsi/scsi_error.c
> @@ -29,6 +29,7 @@
> #include <linux/jiffies.h>
>
> #include <scsi/scsi.h>
> +#include <scsi/scsi_alua.h>
> #include <scsi/scsi_cmnd.h>
> #include <scsi/scsi_dbg.h>
> #include <scsi/scsi_device.h>
> @@ -578,6 +579,12 @@ enum scsi_disposition scsi_check_sense(struct scsi_cmnd
> *scmd)
> if (rc != SCSI_RETURN_NOT_HANDLED)
> return rc;
> /* handler does not care. Drop down to default handling */
> + } else if (scsi_device_alua_implicit(sdev)) {
> + enum scsi_disposition rc;
> +
> + rc = scsi_alua_check_sense(sdev, &sshdr);
> + if (rc != SCSI_RETURN_NOT_HANDLED)
> + return rc;
> }
>
> if (scmd->cmnd[0] == TEST_UNIT_READY &&
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index d3a8cd4166f92..e5bcee555ea10 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -26,6 +26,7 @@
> #include <linux/unaligned.h>
>
> #include <scsi/scsi.h>
> +#include <scsi/scsi_alua.h>
> #include <scsi/scsi_cmnd.h>
> #include <scsi/scsi_dbg.h>
> #include <scsi/scsi_device.h>
> @@ -1719,6 +1720,12 @@ static blk_status_t scsi_prepare_cmd(struct request
> *req)
> if (sdev->handler && sdev->handler->prep_fn) {
> blk_status_t ret = sdev->handler->prep_fn(sdev, req);
>
> + if (ret != BLK_STS_OK)
> + return ret;
> + } else if (scsi_device_alua_implicit(sdev)) {
> + /* We should be able to make this common for ALUA DH as well */
> + blk_status_t ret = scsi_alua_prep_fn(sdev, req);
> +
> if (ret != BLK_STS_OK)
> return ret;
> }
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 3af64d1231445..73caf83bd1097 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -1744,6 +1744,8 @@ int scsi_rescan_device(struct scsi_device *sdev)
>
> if (sdev->handler && sdev->handler->rescan)
> sdev->handler->rescan(sdev);
> + else if (scsi_device_alua_implicit(sdev))
> + scsi_device_alua_rescan(sdev);
>
> if (dev->driver && try_module_get(dev->driver->owner)) {
> struct scsi_driver *drv = to_scsi_driver(dev->driver);
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 6c4c3c22f6acf..71a9613898cfc 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -1152,7 +1152,7 @@ sdev_show_access_state(struct device *dev,
> unsigned char access_state;
> const char *access_state_name;
>
> - if (!sdev->handler)
> + if (!sdev->handler && !scsi_device_alua_implicit(sdev))
> return -EINVAL;
>
> access_state = (sdev->access_state & SCSI_ACCESS_STATE_MASK);
> @@ -1409,6 +1409,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
> scsi_autopm_get_device(sdev);
>
> scsi_dh_add_device(sdev);
> + if (!sdev->handler && scsi_device_alua_implicit(sdev))
> + scsi_device_alua_rescan(sdev);
>
> error = device_add(&sdev->sdev_gendev);
> if (error) {
> diff --git a/include/scsi/scsi_alua.h b/include/scsi/scsi_alua.h
> index 2d5db944f75b7..8e506d1d66cce 100644
> --- a/include/scsi/scsi_alua.h
> +++ b/include/scsi/scsi_alua.h
> @@ -24,6 +24,7 @@ struct alua_data {
> unsigned char transition_tmo;
> unsigned long expiry;
> unsigned long interval;
> + struct delayed_work work;
> struct scsi_device *sdev;
> spinlock_t lock;
> };
> @@ -35,11 +36,15 @@ void scsi_alua_handle_state_transition(struct scsi_device
> *sdev);
>
> int scsi_alua_check_tpgs(struct scsi_device *sdev);
>
> +enum scsi_disposition scsi_alua_check_sense(struct scsi_device *sdev,
> + struct scsi_sense_hdr *sense_hdr);
> +
> int scsi_alua_rtpg_run(struct scsi_device *sdev);
> int scsi_alua_stpg_run(struct scsi_device *sdev, bool optimize);
>
> blk_status_t scsi_alua_prep_fn(struct scsi_device *sdev, struct request
> *req);
>
> +void scsi_device_alua_rescan(struct scsi_device *sdev);
> bool scsi_device_alua_implicit(struct scsi_device *sdev);
>
> int scsi_alua_init(void);
> @@ -53,6 +58,12 @@ static inline int scsi_alua_check_tpgs(struct scsi_device
> *sdev)
> {
> return 0;
> }
> +static inline
> +enum scsi_disposition scsi_alua_check_sense(struct scsi_device *sdev,
> + struct scsi_sense_hdr *sense_hdr)
> +{
> + return SCSI_RETURN_NOT_HANDLED;
> +}
> static inline int scsi_alua_rtpg_run(struct scsi_device *sdev)
> {
> return 0;
> @@ -66,6 +77,9 @@ blk_status_t scsi_alua_prep_fn(struct scsi_device *sdev,
> struct request *req)
> {
> return BLK_STS_OK;
> }
> +static inline void scsi_device_alua_rescan(struct scsi_device *sdev)
> +{
> +}
> static inline bool scsi_device_alua_implicit(struct scsi_device *sdev)
> {
> return false;
> --
> 2.43.5
