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block: introduce GENHD_FL_HIDDEN

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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>
This commit is contained in:
Christoph Hellwig 2017-11-02 21:29:53 +03:00 committed by Jens Axboe
parent 517bf3c306
commit 8ddcd65325
2 changed files with 51 additions and 18 deletions
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68
block/genhd.c
View File

@ -585,6 +585,11 @@ static void register_disk(struct device *parent, struct gendisk *disk)
*/
pm_runtime_set_memalloc_noio(ddev, true);
if (disk->flags & GENHD_FL_HIDDEN) {
dev_set_uevent_suppress(ddev, 0);
return;
}
disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj);
disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj);
@ -616,6 +621,11 @@ exit:
while ((part = disk_part_iter_next(&piter)))
kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD);
disk_part_iter_exit(&piter);
err = sysfs_create_link(&ddev->kobj,
&disk->queue->backing_dev_info->dev->kobj,
"bdi");
WARN_ON(err);
}
/**
@ -630,7 +640,6 @@ exit:
*/
void device_add_disk(struct device *parent, struct gendisk *disk)
{
struct backing_dev_info *bdi;
dev_t devt;
int retval;
@ -639,7 +648,8 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
* parameters make sense.
*/
WARN_ON(disk->minors && !(disk->major || disk->first_minor));
WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT));
WARN_ON(!disk->minors &&
!(disk->flags & (GENHD_FL_EXT_DEVT | GENHD_FL_HIDDEN)));
disk->flags |= GENHD_FL_UP;
@ -648,18 +658,26 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
WARN_ON(1);
return;
}
disk_to_dev(disk)->devt = devt;
disk->major = MAJOR(devt);
disk->first_minor = MINOR(devt);
disk_alloc_events(disk);
/* Register BDI before referencing it from bdev */
bdi = disk->queue->backing_dev_info;
bdi_register_owner(bdi, disk_to_dev(disk));
blk_register_region(disk_devt(disk), disk->minors, NULL,
exact_match, exact_lock, disk);
if (disk->flags & GENHD_FL_HIDDEN) {
/*
* Don't let hidden disks show up in /proc/partitions,
* and don't bother scanning for partitions either.
*/
disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO;
disk->flags |= GENHD_FL_NO_PART_SCAN;
} else {
/* Register BDI before referencing it from bdev */
disk_to_dev(disk)->devt = devt;
bdi_register_owner(disk->queue->backing_dev_info,
disk_to_dev(disk));
blk_register_region(disk_devt(disk), disk->minors, NULL,
exact_match, exact_lock, disk);
}
register_disk(parent, disk);
blk_register_queue(disk);
@ -669,10 +687,6 @@ void device_add_disk(struct device *parent, struct gendisk *disk)
*/
WARN_ON_ONCE(!blk_get_queue(disk->queue));
retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
"bdi");
WARN_ON(retval);
disk_add_events(disk);
blk_integrity_add(disk);
}
@ -701,7 +715,8 @@ void del_gendisk(struct gendisk *disk)
set_capacity(disk, 0);
disk->flags &= ~GENHD_FL_UP;
sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
if (!(disk->flags & GENHD_FL_HIDDEN))
sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi");
if (disk->queue) {
/*
* Unregister bdi before releasing device numbers (as they can
@ -712,13 +727,15 @@ void del_gendisk(struct gendisk *disk)
} else {
WARN_ON(1);
}
blk_unregister_region(disk_devt(disk), disk->minors);
if (!(disk->flags & GENHD_FL_HIDDEN)) {
blk_unregister_region(disk_devt(disk), disk->minors);
kobject_put(disk->part0.holder_dir);
kobject_put(disk->slave_dir);
}
part_stat_set_all(&disk->part0, 0);
disk->part0.stamp = 0;
kobject_put(disk->part0.holder_dir);
kobject_put(disk->slave_dir);
if (!sysfs_deprecated)
sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk)));
pm_runtime_set_memalloc_noio(disk_to_dev(disk), false);
@ -781,6 +798,10 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
spin_unlock_bh(&ext_devt_lock);
}
if (unlikely(disk->flags & GENHD_FL_HIDDEN)) {
put_disk(disk);
disk = NULL;
}
return disk;
}
EXPORT_SYMBOL(get_gendisk);
@ -1024,6 +1045,15 @@ static ssize_t disk_removable_show(struct device *dev,
(disk->flags & GENHD_FL_REMOVABLE ? 1 : 0));
}
static ssize_t disk_hidden_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
return sprintf(buf, "%d\n",
(disk->flags & GENHD_FL_HIDDEN ? 1 : 0));
}
static ssize_t disk_ro_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@ -1061,6 +1091,7 @@ static ssize_t disk_discard_alignment_show(struct device *dev,
static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL);
static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL);
static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL);
static DEVICE_ATTR(hidden, S_IRUGO, disk_hidden_show, NULL);
static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL);
static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL);
static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL);
@ -1085,6 +1116,7 @@ static struct attribute *disk_attrs[] = {
&dev_attr_range.attr,
&dev_attr_ext_range.attr,
&dev_attr_removable.attr,
&dev_attr_hidden.attr,
&dev_attr_ro.attr,
&dev_attr_size.attr,
&dev_attr_alignment_offset.attr,

1
include/linux/genhd.h
View File

@ -140,6 +140,7 @@ struct hd_struct {
#define GENHD_FL_NATIVE_CAPACITY 128
#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE 256
#define GENHD_FL_NO_PART_SCAN 512
#define GENHD_FL_HIDDEN 1024
enum {
DISK_EVENT_MEDIA_CHANGE = 1 << 0, /* media changed */