[PATCH 6/7] block: introduce GENHD_FL_HIDDEN
Christoph Hellwig
hch at lst.de
Thu Nov 2 11:29:53 PDT 2017
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 at lst.de>
---
block/genhd.c | 68 +++++++++++++++++++++++++++++++++++++--------------
include/linux/genhd.h | 1 +
2 files changed, 51 insertions(+), 18 deletions(-)
diff --git a/block/genhd.c b/block/genhd.c
index 1174d24e405e..835e907e6e01 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -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 @@ static void register_disk(struct device *parent, struct gendisk *disk)
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 @@ static void register_disk(struct device *parent, struct gendisk *disk)
*/
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,
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 5c0ed5db33c2..93aae3476f58 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -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 */
--
2.14.2
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