block: introduce GENHD_FL_HIDDEN
With this flag a driver can create a gendisk that can be used for I/O submission inside the kernel, but which is not registered as user facing block device. This will be useful for the NVMe multipath implementation. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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@ -585,6 +585,11 @@ static void register_disk(struct device *parent, struct gendisk *disk)
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*/
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pm_runtime_set_memalloc_noio(ddev, true);
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if (disk->flags & GENHD_FL_HIDDEN) {
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dev_set_uevent_suppress(ddev, 0);
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return;
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}
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disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
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disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
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@ -616,6 +621,11 @@ exit:
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while ((part = disk_part_iter_next(&piter)))
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kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
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disk_part_iter_exit(&piter);
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err = sysfs_create_link(&ddev->kobj,
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&disk->queue->backing_dev_info->dev->kobj,
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"bdi");
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WARN_ON(err);
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}
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/**
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@ -630,7 +640,6 @@ exit:
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*/
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void device_add_disk(struct device *parent, struct gendisk *disk)
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{
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struct backing_dev_info *bdi;
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dev_t devt;
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int retval;
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@ -639,7 +648,8 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
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* parameters make sense.
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*/
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WARN_ON(disk->minors && !(disk->major || disk->first_minor));
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WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
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WARN_ON(!disk->minors &&
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!(disk->flags & (GENHD_FL_EXT_DEVT | GENHD_FL_HIDDEN)));
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disk->flags |= GENHD_FL_UP;
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@ -648,18 +658,26 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
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WARN_ON(1);
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return;
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}
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disk_to_dev(disk)->devt = devt;
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disk->major = MAJOR(devt);
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disk->first_minor = MINOR(devt);
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disk_alloc_events(disk);
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/* Register BDI before referencing it from bdev */
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bdi = disk->queue->backing_dev_info;
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bdi_register_owner(bdi, disk_to_dev(disk));
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blk_register_region(disk_devt(disk), disk->minors, NULL,
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exact_match, exact_lock, disk);
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if (disk->flags & GENHD_FL_HIDDEN) {
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/*
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* Don't let hidden disks show up in /proc/partitions,
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* and don't bother scanning for partitions either.
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*/
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disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
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disk->flags |= GENHD_FL_NO_PART_SCAN;
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} else {
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/* Register BDI before referencing it from bdev */
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disk_to_dev(disk)->devt = devt;
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bdi_register_owner(disk->queue->backing_dev_info,
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disk_to_dev(disk));
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blk_register_region(disk_devt(disk), disk->minors, NULL,
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exact_match, exact_lock, disk);
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}
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register_disk(parent, disk);
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blk_register_queue(disk);
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@ -669,10 +687,6 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
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*/
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WARN_ON_ONCE(!blk_get_queue(disk->queue));
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retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
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"bdi");
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WARN_ON(retval);
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disk_add_events(disk);
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blk_integrity_add(disk);
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}
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@ -701,7 +715,8 @@ void del_gendisk(struct gendisk *disk)
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set_capacity(disk, 0);
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disk->flags &= ~GENHD_FL_UP;
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sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
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if (!(disk->flags & GENHD_FL_HIDDEN))
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sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
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if (disk->queue) {
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/*
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* Unregister bdi before releasing device numbers (as they can
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@ -712,13 +727,15 @@ void del_gendisk(struct gendisk *disk)
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} else {
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WARN_ON(1);
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}
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blk_unregister_region(disk_devt(disk), disk->minors);
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if (!(disk->flags & GENHD_FL_HIDDEN)) {
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blk_unregister_region(disk_devt(disk), disk->minors);
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kobject_put(disk->part0.holder_dir);
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kobject_put(disk->slave_dir);
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}
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part_stat_set_all(&disk->part0, 0);
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disk->part0.stamp = 0;
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kobject_put(disk->part0.holder_dir);
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kobject_put(disk->slave_dir);
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if (!sysfs_deprecated)
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sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
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pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
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@ -781,6 +798,10 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
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spin_unlock_bh(&ext_devt_lock);
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}
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if (unlikely(disk->flags & GENHD_FL_HIDDEN)) {
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put_disk(disk);
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disk = NULL;
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}
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return disk;
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}
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EXPORT_SYMBOL(get_gendisk);
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@ -1024,6 +1045,15 @@ static ssize_t disk_removable_show(struct device *dev,
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(disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
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}
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static ssize_t disk_hidden_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct gendisk *disk = dev_to_disk(dev);
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return sprintf(buf, "%d\n",
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(disk->flags & GENHD_FL_HIDDEN ? 1 : 0));
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}
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static ssize_t disk_ro_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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@ -1061,6 +1091,7 @@ static ssize_t disk_discard_alignment_show(struct device *dev,
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static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
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static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
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static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
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static DEVICE_ATTR(hidden, S_IRUGO, disk_hidden_show, NULL);
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static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
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static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
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static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
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@ -1085,6 +1116,7 @@ static struct attribute *disk_attrs[] = {
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&dev_attr_range.attr,
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&dev_attr_ext_range.attr,
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&dev_attr_removable.attr,
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&dev_attr_hidden.attr,
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&dev_attr_ro.attr,
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&dev_attr_size.attr,
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&dev_attr_alignment_offset.attr,
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@ -140,6 +140,7 @@ struct hd_struct {
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#define GENHD_FL_NATIVE_CAPACITY 128
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#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE 256
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#define GENHD_FL_NO_PART_SCAN 512
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#define GENHD_FL_HIDDEN 1024
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enum {
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DISK_EVENT_MEDIA_CHANGE = 1 << 0, /* media changed */
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