For a scsi_device to support multipath, introduce structure scsi_mpath_device to hold multipath-specific details.
Like nvme_ns structure for NVME, scsi_mpath_device holds the mpath_device structure to device management and path selection. A module param are introduced to enable multipath - the following modes are available: - on - off - always SCSI multipath will only be available until the following conditions: - scsi_multipath enabled and ALUA supported and unique ID available in VPD page 83. - scsi_multipath always mode and unique ID available in VPD page 83 The scsi_device structure contains a pointer to scsi_mpath_device; having this pointer set or unset indicates whether multipath is enabled or disabled for the scsi_device. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/Kconfig | 10 +++ drivers/scsi/Makefile | 1 + drivers/scsi/scsi.c | 8 +- drivers/scsi/scsi_multipath.c | 146 ++++++++++++++++++++++++++++++++++ drivers/scsi/scsi_scan.c | 4 + drivers/scsi/scsi_sysfs.c | 2 + include/scsi/scsi_device.h | 2 + include/scsi/scsi_multipath.h | 55 +++++++++++++ 8 files changed, 227 insertions(+), 1 deletion(-) create mode 100644 drivers/scsi/scsi_multipath.c create mode 100644 include/scsi/scsi_multipath.h diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig index 19d0884479a24..2375971db2052 100644 --- a/drivers/scsi/Kconfig +++ b/drivers/scsi/Kconfig @@ -76,6 +76,16 @@ config SCSI_LIB_KUNIT_TEST If unsure say N. +config SCSI_MULTIPATH + bool "SCSI multipath support (EXPERIMENTAL)" + depends on SCSI_MOD + select LIBMULTIPATH + help + This option enables support for native SCSI multipath support for + SCSI host. + + If unsure say N. + comment "SCSI support type (disk, tape, CD-ROM)" depends on SCSI diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile index 16de3e41f94c4..64b7a82828b81 100644 --- a/drivers/scsi/Makefile +++ b/drivers/scsi/Makefile @@ -168,6 +168,7 @@ scsi_mod-y += scsi_trace.o scsi_logging.o scsi_mod-$(CONFIG_PM) += scsi_pm.o scsi_mod-$(CONFIG_SCSI_DH) += scsi_dh.o scsi_mod-$(CONFIG_BLK_DEV_BSG) += scsi_bsg.o +scsi_mod-$(CONFIG_SCSI_MULTIPATH) += scsi_multipath.o hv_storvsc-y := storvsc_drv.o diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c index 76cdad063f7bc..70aa1dbeacebf 100644 --- a/drivers/scsi/scsi.c +++ b/drivers/scsi/scsi.c @@ -64,6 +64,7 @@ #include <scsi/scsi_driver.h> #include <scsi/scsi_eh.h> #include <scsi/scsi_host.h> +#include <scsi/scsi_multipath.h> #include <scsi/scsi_tcq.h> #include "scsi_priv.h" @@ -1042,12 +1043,16 @@ static int __init init_scsi(void) error = scsi_sysfs_register(); if (error) goto cleanup_sysctl; + error = scsi_multipath_init(); + if (error) + goto cleanup_sysfs; scsi_netlink_init(); printk(KERN_NOTICE "SCSI subsystem initialized\n"); return 0; - +cleanup_sysfs: + scsi_sysfs_unregister(); cleanup_sysctl: scsi_exit_sysctl(); cleanup_hosts: @@ -1066,6 +1071,7 @@ static int __init init_scsi(void) static void __exit exit_scsi(void) { scsi_netlink_exit(); + scsi_multipath_exit(); scsi_sysfs_unregister(); scsi_exit_sysctl(); scsi_exit_hosts(); diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c new file mode 100644 index 0000000000000..ff37cfdf2f9d1 --- /dev/null +++ b/drivers/scsi/scsi_multipath.c @@ -0,0 +1,146 @@ +// SPDX-License-Indentifier: GPL-2.0 +/* + * Copyright (c) 2026 Oracle Corp + * + */ + +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_driver.h> +#include <scsi/scsi_proto.h> +#include <scsi/scsi_host.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi_multipath.h> + +#include "scsi_priv.h" + +enum { + SCSI_MULTIPATH_OFF, + SCSI_MULTIPATH_ON, + SCSI_MULTIPATH_ALWAYS, +}; + +static const char *scsi_multipath_modes[] = { + [SCSI_MULTIPATH_OFF] = "off", + [SCSI_MULTIPATH_ON] = "on", + [SCSI_MULTIPATH_ALWAYS] = "always", +}; + +static int scsi_multipath = SCSI_MULTIPATH_OFF; + +static int scsi_multipath_param_set(const char *val, const struct kernel_param *kp) +{ + if (!val) + return -EINVAL; + if (!strncmp(val, "on", 2)) + scsi_multipath = SCSI_MULTIPATH_ON; + else if (!strncmp(val, "always", 6)) + scsi_multipath = SCSI_MULTIPATH_ALWAYS; + else if (!strncmp(val, "off", 3)) + scsi_multipath = SCSI_MULTIPATH_OFF; + else + return -EINVAL; + + return 0; +} + +static int scsi_multipath_param_get(char *buf, const struct kernel_param *kp) +{ + return sprintf(buf, "%s\n", scsi_multipath_modes[scsi_multipath]); +} + +static const struct kernel_param_ops multipath_param_ops = { + .set = scsi_multipath_param_set, + .get = scsi_multipath_param_get, +}; + +module_param_cb(multipath, &multipath_param_ops, &scsi_multipath, 0444); +MODULE_PARM_DESC(multipath, "turn on native multipath support, options: on, off, always"); + +static int scsi_mpath_unique_lun_id(struct scsi_device *sdev) +{ + struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; + int ret; + + ret = scsi_vpd_lun_id(sdev, scsi_mpath_dev->device_id_str, + SCSI_MPATH_DEVICE_ID_LEN); + if (ret < 0) + return ret; + + return 0; +} + +static int scsi_multipath_sdev_init(struct scsi_device *sdev) +{ + struct Scsi_Host *shost = sdev->host; + struct scsi_mpath_device *scsi_mpath_dev; + struct mpath_device *mpath_device; + + scsi_mpath_dev = kzalloc(sizeof(*scsi_mpath_dev), GFP_KERNEL); + if (!scsi_mpath_dev) + return -ENOMEM; + scsi_mpath_dev->sdev = sdev; + sdev->scsi_mpath_dev = scsi_mpath_dev; + + mpath_device = &scsi_mpath_dev->mpath_device; + mpath_device->numa_node = dev_to_node(shost->dma_dev); + mpath_device->access_state = MPATH_STATE_OPTIMIZED; + + return 0; +} + +static void scsi_multipath_sdev_uninit(struct scsi_device *sdev) +{ + kfree(sdev->scsi_mpath_dev); + sdev->scsi_mpath_dev = NULL; +} + +int scsi_mpath_dev_alloc(struct scsi_device *sdev) +{ + int ret; + + if (scsi_multipath == SCSI_MULTIPATH_OFF) + return 0; + + if (!scsi_device_tpgs(sdev) && (scsi_multipath != SCSI_MULTIPATH_ALWAYS)) { + sdev_printk(KERN_DEBUG, sdev, "IMPLICIT TPGS are required for multipath support\n"); + return 0; + } + + ret = scsi_multipath_sdev_init(sdev); + if (ret) + return ret; + + ret = scsi_mpath_unique_lun_id(sdev); + if (ret < 0) { + ret = 0; + goto out_uninit; + } + + return 0; + +out_uninit: + scsi_multipath_sdev_uninit(sdev); + return ret; +} + +void scsi_mpath_dev_release(struct scsi_device *sdev) +{ + struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; + + if (!scsi_mpath_dev) + return; + + scsi_multipath_sdev_uninit(sdev); +} + +int __init scsi_multipath_init(void) +{ + return 0; +} + +void __exit scsi_multipath_exit(void) +{ +} + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("scsi_multipath"); diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c index 2cfcf1f5d6a46..842dad8cc6a2f 100644 --- a/drivers/scsi/scsi_scan.c +++ b/drivers/scsi/scsi_scan.c @@ -46,6 +46,7 @@ #include <scsi/scsi_transport.h> #include <scsi/scsi_dh.h> #include <scsi/scsi_eh.h> +#include <scsi/scsi_multipath.h> #include "scsi_priv.h" #include "scsi_logging.h" @@ -1123,6 +1124,9 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result, sdev->max_queue_depth = sdev->queue_depth; WARN_ON_ONCE(sdev->max_queue_depth > sdev->budget_map.depth); + if (scsi_mpath_dev_alloc(sdev)) + return SCSI_SCAN_NO_RESPONSE; + /* * Ok, the device is now all set up, we can * register it and tell the rest of the kernel diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 6b8c5c05f2944..47534d9f2cf9b 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -23,6 +23,7 @@ #include <scsi/scsi_transport.h> #include <scsi/scsi_driver.h> #include <scsi/scsi_devinfo.h> +#include <scsi/scsi_multipath.h> #include "scsi_priv.h" #include "scsi_logging.h" @@ -455,6 +456,7 @@ static void scsi_device_dev_release(struct device *dev) might_sleep(); scsi_dh_release_device(sdev); + scsi_mpath_dev_release(sdev); parent = sdev->sdev_gendev.parent; diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index d32f5841f4f85..52974dba0a724 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -279,6 +279,8 @@ struct scsi_device { struct device sdev_gendev, sdev_dev; + struct scsi_mpath_device *scsi_mpath_dev; + struct work_struct requeue_work; struct scsi_device_handler *handler; diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h new file mode 100644 index 0000000000000..d3d410dafd17a --- /dev/null +++ b/include/scsi/scsi_multipath.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _SCSI_SCSI_MULTIPATH_H +#define _SCSI_SCSI_MULTIPATH_H + +#include <linux/list.h> +#include <linux/types.h> +#include <linux/rcupdate.h> +#include <linux/workqueue.h> +#include <linux/mutex.h> +#include <linux/blk-mq.h> +#include <linux/multipath.h> +#include <scsi/scsi.h> +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_dbg.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi_devinfo.h> +#include <scsi/scsi_driver.h> + +#ifdef CONFIG_SCSI_MULTIPATH +#define SCSI_MPATH_DEVICE_ID_LEN 256 + +struct scsi_mpath_device { + struct mpath_device mpath_device; + struct scsi_device *sdev; + + char device_id_str[SCSI_MPATH_DEVICE_ID_LEN]; +}; +#define to_scsi_mpath_device(d) \ + container_of(d, struct scsi_mpath_device, mpath_device) + +int scsi_mpath_dev_alloc(struct scsi_device *sdev); +void scsi_mpath_dev_release(struct scsi_device *sdev); +int scsi_multipath_init(void); +void scsi_multipath_exit(void); +#else /* CONFIG_SCSI_MULTIPATH */ + +struct scsi_mpath_device { +}; + +static inline int scsi_mpath_dev_alloc(struct scsi_device *sdev) +{ + return 0; +} +static inline void scsi_mpath_dev_release(struct scsi_device *sdev) +{ +} +static inline int scsi_multipath_init(void) +{ + return 0; +} +static inline void scsi_multipath_exit(void) +{ +} +#endif /* CONFIG_SCSI_MULTIPATH */ +#endif /* _SCSI_SCSI_MULTIPATH_H */ -- 2.43.5
