Introduce a scsi_device head structure - scsi_mpath_head - to manage multipathing for a scsi_device. This is similar to nvme_ns_head structure.
There is no reference in scsi_mpath_head to any disk, as this would be mananged by the scsi_disk driver. A list of scsi_mpath_head structures is managed to lookup for matching multipathed scsi_device's. Matching is done through the scsi_device unique id. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/scsi_multipath.c | 147 ++++++++++++++++++++++++++++++++++ drivers/scsi/scsi_sysfs.c | 3 + include/scsi/scsi_multipath.h | 29 +++++++ 3 files changed, 179 insertions(+) diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c index 04e0bad3d9204..49316269fad8e 100644 --- a/drivers/scsi/scsi_multipath.c +++ b/drivers/scsi/scsi_multipath.c @@ -16,6 +16,10 @@ bool scsi_multipath; static bool scsi_multipath_always; +static LIST_HEAD(scsi_mpath_heads_list); +static DEFINE_MUTEX(scsi_mpath_heads_lock); +static DEFINE_IDA(scsi_multipath_dev_ida); + static int multipath_param_set(const char *val, const struct kernel_param *kp) { int ret; @@ -99,6 +103,73 @@ static int scsi_multipath_sdev_init(struct scsi_device *sdev) return 0; } +struct mpath_head_template smpdt_pr = { +}; + +static struct scsi_mpath_head *scsi_mpath_alloc_head(void) +{ + struct scsi_mpath_head *scsi_mpath_head; + int ret; + + scsi_mpath_head = kzalloc(sizeof(*scsi_mpath_head), GFP_KERNEL); + if (!scsi_mpath_head) + return NULL; + + ida_init(&scsi_mpath_head->ida); + mutex_init(&scsi_mpath_head->lock); + + scsi_mpath_head->mpath_head = mpath_alloc_head(); + if (IS_ERR(scsi_mpath_head->mpath_head)) + goto out_free; + scsi_mpath_head->mpath_head->mpdt = &smpdt_pr; + scsi_mpath_head->mpath_head->drvdata = scsi_mpath_head; + + scsi_mpath_head->index = ida_alloc(&scsi_multipath_dev_ida, GFP_KERNEL); + if (scsi_mpath_head->index < 0) + goto out_put_head; + + device_initialize(&scsi_mpath_head->dev); + ret = dev_set_name(&scsi_mpath_head->dev, "%d", scsi_mpath_head->index); + if (ret) { + put_device(&scsi_mpath_head->dev); + goto out_free_ida; + } + + return scsi_mpath_head; + +out_free_ida: + ida_free(&scsi_multipath_dev_ida, scsi_mpath_head->index); +out_put_head: + mpath_put_head(scsi_mpath_head->mpath_head); +out_free: + kfree(scsi_mpath_head); + return NULL; +} + +static struct scsi_mpath_head *scsi_mpath_find_head( + struct scsi_mpath_device *scsi_mpath_dev) +{ + struct scsi_mpath_head *scsi_mpath_head; + int ret; + + mutex_lock(&scsi_mpath_heads_lock); + list_for_each_entry(scsi_mpath_head, &scsi_mpath_heads_list, entry) { + ret = scsi_mpath_get_head(scsi_mpath_head); + if (ret) + continue; + if (strncmp(scsi_mpath_head->wwid, + scsi_mpath_dev->device_id_str, + SCSI_MPATH_DEVICE_ID_LEN) == 0) { + + mutex_unlock(&scsi_mpath_heads_lock); + return scsi_mpath_head; + } + scsi_mpath_put_head(scsi_mpath_head); + } + + return NULL; +} + static void scsi_multipath_sdev_uninit(struct scsi_device *sdev) { kfree(sdev->scsi_mpath_dev); @@ -107,6 +178,7 @@ static void scsi_multipath_sdev_uninit(struct scsi_device *sdev) int scsi_mpath_dev_alloc(struct scsi_device *sdev) { + struct scsi_mpath_head *scsi_mpath_head; int ret; if (!scsi_multipath) @@ -127,13 +199,75 @@ int scsi_mpath_dev_alloc(struct scsi_device *sdev) goto out_uninit; } + scsi_mpath_head = scsi_mpath_find_head(sdev->scsi_mpath_dev); + if (scsi_mpath_head) + goto found; + /* scsi_mpath_disks_list lock held */ + scsi_mpath_head = scsi_mpath_alloc_head(); + if (!scsi_mpath_head) + goto out_uninit; + + strcpy(scsi_mpath_head->wwid, sdev->scsi_mpath_dev->device_id_str); + + ret = device_add(&scsi_mpath_head->dev); + if (ret) + goto out_put_head; + + list_add_tail(&scsi_mpath_head->entry, &scsi_mpath_heads_list); + + mutex_unlock(&scsi_mpath_heads_lock); + sdev->scsi_mpath_dev->scsi_mpath_head = scsi_mpath_head; + +found: + sdev->scsi_mpath_dev->index = ida_alloc(&scsi_mpath_head->ida, GFP_KERNEL); + if (sdev->scsi_mpath_dev->index < 0) { + ret = sdev->scsi_mpath_dev->index; + goto out_put_head; + } + + mutex_lock(&scsi_mpath_head->lock); + scsi_mpath_head->dev_count++; + mutex_unlock(&scsi_mpath_head->lock); + + sdev->scsi_mpath_dev->scsi_mpath_head = scsi_mpath_head; return 0; +out_put_head: + scsi_mpath_put_head(scsi_mpath_head); out_uninit: + mutex_unlock(&scsi_mpath_heads_lock); scsi_multipath_sdev_uninit(sdev); return ret; } +static void scsi_mpath_remove_head(struct scsi_mpath_device *scsi_mpath_dev) +{ + struct scsi_mpath_head *scsi_mpath_head = + scsi_mpath_dev->scsi_mpath_head; + bool last_path = false; + + mutex_lock(&scsi_mpath_head->lock); + scsi_mpath_head->dev_count--; + if (scsi_mpath_head->dev_count == 0) + last_path = true; + mutex_unlock(&scsi_mpath_head->lock); + + if (last_path) + device_del(&scsi_mpath_head->dev); + + scsi_mpath_dev->scsi_mpath_head = NULL; + scsi_mpath_put_head(scsi_mpath_head); +} + +void scsi_mpath_remove_device(struct scsi_mpath_device *scsi_mpath_dev) +{ + struct scsi_mpath_head *scsi_mpath_head = scsi_mpath_dev->scsi_mpath_head; + + ida_free(&scsi_mpath_head->ida, scsi_mpath_dev->index); + + scsi_mpath_remove_head(scsi_mpath_dev); +} + void scsi_mpath_dev_release(struct scsi_device *sdev) { struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; @@ -142,8 +276,21 @@ void scsi_mpath_dev_release(struct scsi_device *sdev) return; scsi_multipath_sdev_uninit(sdev); +} + +int scsi_mpath_get_head(struct scsi_mpath_head *scsi_mpath_head) +{ + if (!get_device(&scsi_mpath_head->dev)) + return -ENXIO; + return 0; +} +EXPORT_SYMBOL_GPL(scsi_mpath_get_head); +void scsi_mpath_put_head(struct scsi_mpath_head *scsi_mpath_head) +{ + put_device(&scsi_mpath_head->dev); } +EXPORT_SYMBOL_GPL(scsi_mpath_put_head); int __init scsi_multipath_init(void) { diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c index 0d69e27600a7a..287a683e89ae5 100644 --- a/drivers/scsi/scsi_sysfs.c +++ b/drivers/scsi/scsi_sysfs.c @@ -1447,6 +1447,9 @@ void __scsi_remove_device(struct scsi_device *sdev) } else put_device(&sdev->sdev_dev); + if (sdev->scsi_mpath_dev) + scsi_mpath_remove_device(sdev->scsi_mpath_dev); + /* * Stop accepting new requests and wait until all queuecommand() and * scsi_run_queue() invocations have finished before tearing down the diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h index ca00ea10cd5db..38953b05a44dc 100644 --- a/include/scsi/scsi_multipath.h +++ b/include/scsi/scsi_multipath.h @@ -19,9 +19,22 @@ #ifdef CONFIG_SCSI_MULTIPATH #define SCSI_MPATH_DEVICE_ID_LEN 40 +struct scsi_mpath_head { + char wwid[SCSI_MPATH_DEVICE_ID_LEN]; + struct list_head entry; + int dev_count; + struct ida ida; + struct mutex lock; + struct mpath_head *mpath_head; + struct device dev; + int index; +}; + struct scsi_mpath_device { struct mpath_device mpath_device; struct scsi_device *sdev; + int index; + struct scsi_mpath_head *scsi_mpath_head; char device_id_str[SCSI_MPATH_DEVICE_ID_LEN]; }; @@ -32,8 +45,13 @@ 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); +void scsi_mpath_remove_device(struct scsi_mpath_device *scsi_mpath_dev); +int scsi_mpath_get_head(struct scsi_mpath_head *); +void scsi_mpath_put_head(struct scsi_mpath_head *); #else /* CONFIG_SCSI_MULTIPATH */ +struct scsi_mpath_head { +}; struct scsi_mpath_device { }; @@ -51,5 +69,16 @@ static inline int scsi_multipath_init(void) static inline void scsi_multipath_exit(void) { } +static inline void scsi_mpath_remove_device(struct scsi_mpath_device + *scsi_mpath_dev) +{ +} +static inline int scsi_mpath_get_head(struct scsi_mpath_head *) +{ + return 0; +} +static inline void scsi_mpath_put_head(struct scsi_mpath_head *) +{ +} #endif /* CONFIG_SCSI_MULTIPATH */ #endif /* _SCSI_SCSI_MULTIPATH_H */ -- 2.43.5
