Add a mpath_dev file so that the multipath disk can be looked up from per-path scsi_disk directory.
The following is an example of this usage: $ ls -l /dev/sdc brw-rw---- 1 root disk 8, 32 Feb 24 16:08 /dev/sdc $ cat /sys/class/scsi_mpath_disk/scsi_mpath_disk0/sdc/multipath/sdc:0/mpath_dev 8:32 This can be used by a util like lsscsi, which would find that the gendisk for the per-path scsi_disk is missing. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/sd.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 70 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index f044b2dfaa9fd..0d73b03a3daee 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -4109,6 +4109,73 @@ static int sd_mpath_add_disk(struct scsi_disk *sdkp) return 0; } +static ssize_t sd_mpath_dev_show(struct device *dev, + struct device_attribute *attr, char *page) +{ + struct gendisk *gd = dev_to_disk(dev); + struct scsi_disk *sdkp = gd->private_data; + struct scsi_device *sdev = sdkp->device; + struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; + struct scsi_mpath_head *scsi_mpath_head = + scsi_mpath_dev->scsi_mpath_head; + struct mpath_head *mpath_head = &scsi_mpath_head->mpath_head; + struct sd_mpath_disk *sd_mpath_disk; + struct device *disk_dev; + struct gendisk *disk; + char devt_str[13] = ""; + + /* + * This attr is for the per-path scsi_disk block device. We need to + * handle the scenario that the multipath disk has been deleted and + * the per-path scsi_disk (and its attr files) is still present. + */ + mutex_lock(&sd_mpath_disks_lock); + sd_mpath_disk = sd_mpath_find_disk(scsi_mpath_head); + if (!sd_mpath_disk) + goto out; + if (!sd_mpath_disk->disk_count) + goto out_put_disk; + disk = mpath_head->disk; + disk_dev = disk_to_dev(disk); + format_dev_t(devt_str, disk_dev->devt); +out_put_disk: + sd_mpath_put_disk(sd_mpath_disk); +out: + mutex_unlock(&sd_mpath_disks_lock); + return sysfs_emit(page, "%s\n", devt_str); +} +static DEVICE_ATTR(mpath_dev, 0444, sd_mpath_dev_show, NULL); + +static struct attribute *sd_mpath_dev_attrs[] = { + &dev_attr_mpath_dev.attr, + NULL +}; + +static umode_t sd_mpath_dev_attr_is_visible(struct kobject *kobj, + struct attribute *attr, int i) +{ + struct device *dev = kobj_to_dev(kobj); + struct gendisk *gd = dev_to_disk(dev); + struct scsi_disk *sdkp = gd->private_data; + struct scsi_device *sdev = sdkp->device; + struct scsi_mpath_device *scsi_mpath_device = sdev->scsi_mpath_dev; + + if (!scsi_mpath_device) + return 0; + + return attr->mode; +} + +static const struct attribute_group sd_mpath_dev_attr_group = { + .is_visible = sd_mpath_dev_attr_is_visible, + .attrs = sd_mpath_dev_attrs, +}; + +static const struct attribute_group *sd_mpath_dev_groups[] = { + &sd_mpath_dev_attr_group, + NULL +}; + static ssize_t sd_mpath_device_delayed_removal_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { @@ -4389,6 +4456,8 @@ static int sd_mpath_add_disk(struct scsi_disk *sdkp) { return 0; } + +#define sd_mpath_dev_groups NULL #endif /** @@ -4539,7 +4608,7 @@ static int sd_probe(struct scsi_device *sdp) sdp->host->rpm_autosuspend_delay); } - error = device_add_disk(dev, gd, NULL); + error = device_add_disk(dev, gd, sd_mpath_dev_groups); if (error) { sd_mpath_fail_probe(sdkp); device_unregister(&sdkp->disk_dev); -- 2.43.7
