On Tue, Mar 10, 2026 at 11:49:21AM +0000, John Garry wrote: > Add a dedicated ALUA driver which can be used for native SCSI multipath > and also DH-based ALUA support. > > Only core functions to submit a RTPG, STPG, tur, and also helper functions > are added. > > The code from scsi_dh_alua.c to maintain the port groups is not added, > because it is quite intertwined with the DH code. However the port group > management code would be quite useful. > > Hannes Reinecke originally authored this code. > > Signed-off-by: John Garry <[email protected]> > diff --git a/drivers/scsi/scsi_alua.c b/drivers/scsi/scsi_alua.c > new file mode 100644 > index 0000000000000..2e4102192dcb9 > --- /dev/null > +++ b/drivers/scsi/scsi_alua.c > @@ -0,0 +1,204 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Generic SCSI-3 ALUA SCSI driver > + * > + * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH. > + * All rights reserved. > + */ > + > +#include <scsi/scsi.h> > +#include <scsi/scsi_proto.h> > +#include <scsi/scsi_dbg.h> > +#include <scsi/scsi_eh.h> > +#include <scsi/scsi_alua.h> > + > +#define DRV_NAME "alua" > + > +#define ALUA_FAILOVER_RETRIES 5 > + > +/* > + * alua_check_tpgs - Evaluate TPGS setting > + * @sdev: device to be checked > + * > + * Examine the TPGS setting of the sdev to find out if ALUA > + * is supported. > + */ > +int alua_check_tpgs(struct scsi_device *sdev) > +{ > + int tpgs = TPGS_MODE_NONE; > + > + /* > + * ALUA support for non-disk devices is fraught with > + * difficulties, so disable it for now. > + */ > + if (sdev->type != TYPE_DISK) { > + sdev_printk(KERN_INFO, sdev, > + "%s: disable for non-disk devices\n", > + DRV_NAME); > + return tpgs; > + } > + > + tpgs = scsi_device_tpgs(sdev); > + switch (tpgs) { > + case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT: > + sdev_printk(KERN_INFO, sdev, > + "%s: supports implicit and explicit TPGS\n", > + DRV_NAME); > + break; > + case TPGS_MODE_EXPLICIT: > + sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n", > + DRV_NAME); > + break; > + case TPGS_MODE_IMPLICIT: > + sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n", > + DRV_NAME); > + break; > + case TPGS_MODE_NONE: > + sdev_printk(KERN_INFO, sdev, "%s: not supported\n", > + DRV_NAME); > + break; > + default: > + sdev_printk(KERN_INFO, sdev, > + "%s: unsupported TPGS setting %d\n", > + DRV_NAME, tpgs); > + tpgs = TPGS_MODE_NONE; > + break; > + } > + > + return tpgs; > +} > +EXPORT_SYMBOL_GPL(alua_check_tpgs); > + > +/* > + * alua_tur - Send a TEST UNIT READY > + * @sdev: device to which the TEST UNIT READY command should be send > + * > + * Send a TEST UNIT READY to @sdev to figure out the device state > + * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, > + * 0 if no error occurred, and SCSI_DH_IO otherwise.
Nitpick: The comment here still references SCSI_DH_ values -Ben > + */ > +int alua_tur(struct scsi_device *sdev)
