Re: [dm-devel] [PATCH 44/45] block: merge struct block_device and struct hd_struct

[Jan Kara <jack@suse.cz>]

On Sat 28-11-20 17:15:09, Christoph Hellwig wrote:
> Instead of having two structures that represent each block device with
> different life time rules, merge them into a single one.  This also
> greatly simplifies the reference counting rules, as we can use the inode
> reference count as the main reference count for the new struct
> block_device, with the device model reference front ending it for device
> model interaction.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  block/blk-cgroup.c        |   9 ++-
>  block/blk.h               |   2 +-
>  block/genhd.c             |  89 +++++++++--------------------
>  block/partitions/core.c   | 116 +++++++++++++++-----------------------
>  fs/block_dev.c            |   9 ---
>  include/linux/blk_types.h |   8 ++-
>  include/linux/blkdev.h    |   1 -
>  include/linux/genhd.h     |  40 +++----------
>  init/do_mounts.c          |  21 ++++---
>  kernel/trace/blktrace.c   |  43 +++-----------
>  10 files changed, 108 insertions(+), 230 deletions(-)
> 
> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> index 5c0a9d588e6312..031114d454a604 100644
> --- a/block/blk-cgroup.c
> +++ b/block/blk-cgroup.c
> @@ -820,9 +820,9 @@ static void blkcg_fill_root_iostats(void)
>  
>  	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
>  	while ((dev = class_dev_iter_next(&iter))) {
> -		struct gendisk *disk = dev_to_disk(dev);
> -		struct hd_struct *part = disk_get_part(disk, 0);
> -		struct blkcg_gq *blkg = blk_queue_root_blkg(disk->queue);
> +		struct block_device *bdev = dev_to_bdev(dev);
> +		struct blkcg_gq *blkg =
> +			blk_queue_root_blkg(bdev->bd_disk->queue);
>  		struct blkg_iostat tmp;
>  		int cpu;
>  
> @@ -830,7 +830,7 @@ static void blkcg_fill_root_iostats(void)
>  		for_each_possible_cpu(cpu) {
>  			struct disk_stats *cpu_dkstats;
>  
> -			cpu_dkstats = per_cpu_ptr(part->bdev->bd_stats, cpu);
> +			cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu);
>  			tmp.ios[BLKG_IOSTAT_READ] +=
>  				cpu_dkstats->ios[STAT_READ];
>  			tmp.ios[BLKG_IOSTAT_WRITE] +=
> @@ -849,7 +849,6 @@ static void blkcg_fill_root_iostats(void)
>  			blkg_iostat_set(&blkg->iostat.cur, &tmp);
>  			u64_stats_update_end(&blkg->iostat.sync);
>  		}
> -		disk_put_part(part);
>  	}
>  }
>  
> diff --git a/block/blk.h b/block/blk.h
> index 9657c6da7c770c..98f0b1ae264120 100644
> --- a/block/blk.h
> +++ b/block/blk.h
> @@ -356,7 +356,7 @@ char *disk_name(struct gendisk *hd, int partno, char *buf);
>  #define ADDPART_FLAG_NONE	0
>  #define ADDPART_FLAG_RAID	1
>  #define ADDPART_FLAG_WHOLEDISK	2
> -void delete_partition(struct hd_struct *part);
> +void delete_partition(struct block_device *part);
>  int bdev_add_partition(struct block_device *bdev, int partno,
>  		sector_t start, sector_t length);
>  int bdev_del_partition(struct block_device *bdev, int partno);
> diff --git a/block/genhd.c b/block/genhd.c
> index e83174818b543a..f6dd02fe614d2c 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -98,13 +98,14 @@ const char *bdevname(struct block_device *bdev, char *buf)
>  }
>  EXPORT_SYMBOL(bdevname);
>  
> -static void part_stat_read_all(struct hd_struct *part, struct disk_stats *stat)
> +static void part_stat_read_all(struct block_device *part,
> +		struct disk_stats *stat)
>  {
>  	int cpu;
>  
>  	memset(stat, 0, sizeof(struct disk_stats));
>  	for_each_possible_cpu(cpu) {
> -		struct disk_stats *ptr = per_cpu_ptr(part->bdev->bd_stats, cpu);
> +		struct disk_stats *ptr = per_cpu_ptr(part->bd_stats, cpu);
>  		int group;
>  
>  		for (group = 0; group < NR_STAT_GROUPS; group++) {
> @@ -159,39 +160,6 @@ struct block_device *__disk_get_part(struct gendisk *disk, int partno)
>  	return rcu_dereference(ptbl->part[partno]);
>  }
>  
> -/**
> - * disk_get_part - get partition
> - * @disk: disk to look partition from
> - * @partno: partition number
> - *
> - * Look for partition @partno from @disk.  If found, increment
> - * reference count and return it.
> - *
> - * CONTEXT:
> - * Don't care.
> - *
> - * RETURNS:
> - * Pointer to the found partition on success, NULL if not found.
> - */
> -struct hd_struct *disk_get_part(struct gendisk *disk, int partno)
> -{
> -	struct block_device *bdev;
> -	struct hd_struct *part;
> -
> -	rcu_read_lock();
> -	bdev = __disk_get_part(disk, partno);
> -	if (!bdev)
> -		goto fail;
> -	part = bdev->bd_part;
> -	if (!kobject_get_unless_zero(&part_to_dev(part)->kobj))
> -		goto fail;
> -	rcu_read_unlock();
> -	return part;
> -fail:
> -	rcu_read_unlock();
> -	return NULL;
> -}
> -
>  /**
>   * disk_part_iter_init - initialize partition iterator
>   * @piter: iterator to initialize
> @@ -851,7 +819,7 @@ void del_gendisk(struct gendisk *disk)
>  			     DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE);
>  	while ((part = disk_part_iter_next(&piter))) {
>  		invalidate_partition(part);
> -		delete_partition(part->bd_part);
> +		delete_partition(part);
>  	}
>  	disk_part_iter_exit(&piter);
>  
> @@ -944,13 +912,13 @@ void blk_request_module(dev_t devt)
>   */
>  struct block_device *bdget_disk(struct gendisk *disk, int partno)
>  {
> -	struct hd_struct *part;
>  	struct block_device *bdev = NULL;
>  
> -	part = disk_get_part(disk, partno);
> -	if (part)
> -		bdev = bdget_part(part);
> -	disk_put_part(part);
> +	rcu_read_lock();
> +	bdev = __disk_get_part(disk, partno);
> +	if (bdev && !bdgrab(bdev))
> +		bdev = NULL;
> +	rcu_read_unlock();
>  
>  	return bdev;
>  }
> @@ -1167,24 +1135,22 @@ static ssize_t disk_ro_show(struct device *dev,
>  ssize_t part_size_show(struct device *dev,
>  		       struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -
> -	return sprintf(buf, "%llu\n", bdev_nr_sectors(p->bdev));
> +	return sprintf(buf, "%llu\n", bdev_nr_sectors(dev_to_bdev(dev)));
>  }
>  
>  ssize_t part_stat_show(struct device *dev,
>  		       struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -	struct request_queue *q = part_to_disk(p)->queue;
> +	struct block_device *bdev = dev_to_bdev(dev);
> +	struct request_queue *q = bdev->bd_disk->queue;
>  	struct disk_stats stat;
>  	unsigned int inflight;
>  
> -	part_stat_read_all(p, &stat);
> +	part_stat_read_all(bdev, &stat);
>  	if (queue_is_mq(q))
> -		inflight = blk_mq_in_flight(q, p->bdev);
> +		inflight = blk_mq_in_flight(q, bdev);
>  	else
> -		inflight = part_in_flight(p->bdev);
> +		inflight = part_in_flight(bdev);
>  
>  	return sprintf(buf,
>  		"%8lu %8lu %8llu %8u "
> @@ -1219,14 +1185,14 @@ ssize_t part_stat_show(struct device *dev,
>  ssize_t part_inflight_show(struct device *dev, struct device_attribute *attr,
>  			   char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -	struct request_queue *q = part_to_disk(p)->queue;
> +	struct block_device *bdev = dev_to_bdev(dev);
> +	struct request_queue *q = bdev->bd_disk->queue;
>  	unsigned int inflight[2];
>  
>  	if (queue_is_mq(q))
> -		blk_mq_in_flight_rw(q, p->bdev, inflight);
> +		blk_mq_in_flight_rw(q, bdev, inflight);
>  	else
> -		part_in_flight_rw(p->bdev, inflight);
> +		part_in_flight_rw(bdev, inflight);
>  
>  	return sprintf(buf, "%8u %8u\n", inflight[0], inflight[1]);
>  }
> @@ -1274,16 +1240,14 @@ static DEVICE_ATTR(badblocks, 0644, disk_badblocks_show, disk_badblocks_store);
>  ssize_t part_fail_show(struct device *dev,
>  		       struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -
> -	return sprintf(buf, "%d\n", p->bdev->bd_make_it_fail);
> +	return sprintf(buf, "%d\n", dev_to_bdev(dev)->make_it_fail);
>  }
>  
>  ssize_t part_fail_store(struct device *dev,
>  			struct device_attribute *attr,
>  			const char *buf, size_t count)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> +	struct block_device *p = dev_to_bdev(dev);
>  	int i;
>  
>  	if (count > 0 && sscanf(buf, "%d", &i) > 0)
> @@ -1497,7 +1461,7 @@ static int diskstats_show(struct seq_file *seqf, void *v)
>  
>  	disk_part_iter_init(&piter, gp, DISK_PITER_INCL_EMPTY_PART0);
>  	while ((hd = disk_part_iter_next(&piter))) {
> -		part_stat_read_all(hd->bd_part, &stat);
> +		part_stat_read_all(hd, &stat);
>  		if (queue_is_mq(gp->queue))
>  			inflight = blk_mq_in_flight(gp->queue, hd);
>  		else
> @@ -1569,7 +1533,7 @@ dev_t blk_lookup_devt(const char *name, int partno)
>  	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
>  	while ((dev = class_dev_iter_next(&iter))) {
>  		struct gendisk *disk = dev_to_disk(dev);
> -		struct hd_struct *part;
> +		struct block_device *part;
>  
>  		if (strcmp(dev_name(dev), name))
>  			continue;
> @@ -1582,13 +1546,12 @@ dev_t blk_lookup_devt(const char *name, int partno)
>  				     MINOR(dev->devt) + partno);
>  			break;
>  		}
> -		part = disk_get_part(disk, partno);
> +		part = bdget_disk(disk, partno);
>  		if (part) {
> -			devt = part_devt(part);
> -			disk_put_part(part);
> +			devt = part->bd_dev;
> +			bdput(part);
>  			break;
>  		}
> -		disk_put_part(part);
>  	}
>  	class_dev_iter_exit(&iter);
>  	return devt;
> diff --git a/block/partitions/core.c b/block/partitions/core.c
> index 4cb6df175f9077..deca253583bd3f 100644
> --- a/block/partitions/core.c
> +++ b/block/partitions/core.c
> @@ -182,44 +182,39 @@ static struct parsed_partitions *check_partition(struct gendisk *hd,
>  static ssize_t part_partition_show(struct device *dev,
>  				   struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -
> -	return sprintf(buf, "%d\n", p->bdev->bd_partno);
> +	return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_partno);
>  }
>  
>  static ssize_t part_start_show(struct device *dev,
>  			       struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -
> -	return sprintf(buf, "%llu\n", p->bdev->bd_start_sect);
> +	return sprintf(buf, "%llu\n", dev_to_bdev(dev)->bd_start_sect);
>  }
>  
>  static ssize_t part_ro_show(struct device *dev,
>  			    struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -	return sprintf(buf, "%d\n", p->bdev->bd_read_only);
> +	return sprintf(buf, "%d\n", dev_to_bdev(dev)->bd_read_only);
>  }
>  
>  static ssize_t part_alignment_offset_show(struct device *dev,
>  					  struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> +	struct block_device *bdev = dev_to_bdev(dev);
>  
>  	return sprintf(buf, "%u\n",
> -		queue_limit_alignment_offset(&part_to_disk(p)->queue->limits,
> -				p->bdev->bd_start_sect));
> +		queue_limit_alignment_offset(&bdev->bd_disk->queue->limits,
> +				bdev->bd_start_sect));
>  }
>  
>  static ssize_t part_discard_alignment_show(struct device *dev,
>  					   struct device_attribute *attr, char *buf)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> +	struct block_device *bdev = dev_to_bdev(dev);
>  
>  	return sprintf(buf, "%u\n",
> -		queue_limit_discard_alignment(&part_to_disk(p)->queue->limits,
> -				p->bdev->bd_start_sect));
> +		queue_limit_discard_alignment(&bdev->bd_disk->queue->limits,
> +				bdev->bd_start_sect));
>  }
>  
>  static DEVICE_ATTR(partition, 0444, part_partition_show, NULL);
> @@ -264,20 +259,17 @@ static const struct attribute_group *part_attr_groups[] = {
>  
>  static void part_release(struct device *dev)
>  {
> -	struct hd_struct *p = dev_to_part(dev);
> -
>  	blk_free_devt(dev->devt);
> -	bdput(p->bdev);
> +	bdput(dev_to_bdev(dev));
>  }
>  
>  static int part_uevent(struct device *dev, struct kobj_uevent_env *env)
>  {
> -	struct hd_struct *part = dev_to_part(dev);
> +	struct block_device *part = dev_to_bdev(dev);
>  
> -	add_uevent_var(env, "PARTN=%u", part->bdev->bd_partno);
> -	if (part->bdev->bd_meta_info && part->bdev->bd_meta_info->volname[0])
> -		add_uevent_var(env, "PARTNAME=%s",
> -			       part->bdev->bd_meta_info->volname);
> +	add_uevent_var(env, "PARTN=%u", part->bd_partno);
> +	if (part->bd_meta_info && part->bd_meta_info->volname[0])
> +		add_uevent_var(env, "PARTNAME=%s", part->bd_meta_info->volname);
>  	return 0;
>  }
>  
> @@ -292,25 +284,25 @@ struct device_type part_type = {
>   * Must be called either with bd_mutex held, before a disk can be opened or
>   * after all disk users are gone.
>   */
> -void delete_partition(struct hd_struct *part)
> +void delete_partition(struct block_device *part)
>  {
> -	struct gendisk *disk = part_to_disk(part);
> +	struct gendisk *disk = part->bd_disk;
>  	struct disk_part_tbl *ptbl =
>  		rcu_dereference_protected(disk->part_tbl, 1);
>  
> -	rcu_assign_pointer(ptbl->part[part->bdev->bd_partno], NULL);
> +	rcu_assign_pointer(ptbl->part[part->bd_partno], NULL);
>  	rcu_assign_pointer(ptbl->last_lookup, NULL);
>  
> -	kobject_put(part->bdev->bd_holder_dir);
> -	device_del(part_to_dev(part));
> +	kobject_put(part->bd_holder_dir);
> +	device_del(&part->bd_device);
>  
>  	/*
>  	 * Remove the block device from the inode hash, so that it cannot be
>  	 * looked up any more even when openers still hold references.
>  	 */
> -	remove_inode_hash(part->bdev->bd_inode);
> +	remove_inode_hash(part->bd_inode);
>  
> -	put_device(part_to_dev(part));
> +	put_device(&part->bd_device);
>  }
>  
>  static ssize_t whole_disk_show(struct device *dev,
> @@ -324,11 +316,10 @@ static DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
>   * Must be called either with bd_mutex held, before a disk can be opened or
>   * after all disk users are gone.
>   */
> -static struct hd_struct *add_partition(struct gendisk *disk, int partno,
> +static struct block_device *add_partition(struct gendisk *disk, int partno,
>  				sector_t start, sector_t len, int flags,
>  				struct partition_meta_info *info)
>  {
> -	struct hd_struct *p;
>  	dev_t devt = MKDEV(0, 0);
>  	struct device *ddev = disk_to_dev(disk);
>  	struct device *pdev;
> @@ -367,9 +358,6 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	if (!bdev)
>  		return ERR_PTR(-ENOMEM);
>  
> -	p = bdev->bd_part;
> -	pdev = part_to_dev(p);
> -
>  	bdev->bd_start_sect = start;
>  	bdev_set_nr_sectors(bdev, len);
>  	bdev->bd_read_only = get_disk_ro(disk);
> @@ -381,6 +369,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  			goto out_bdput;
>  	}
>  
> +	pdev = &bdev->bd_device;
>  	dname = dev_name(ddev);
>  	if (isdigit(dname[strlen(dname) - 1]))
>  		dev_set_name(pdev, "%sp%d", dname, partno);
> @@ -422,7 +411,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno,
>  	/* suppress uevent if the disk suppresses it */
>  	if (!dev_get_uevent_suppress(ddev))
>  		kobject_uevent(&pdev->kobj, KOBJ_ADD);
> -	return p;
> +	return bdev;
>  
>  out_bdput:
>  	bdput(bdev);
> @@ -459,7 +448,7 @@ static bool partition_overlaps(struct gendisk *disk, sector_t start,
>  int bdev_add_partition(struct block_device *bdev, int partno,
>  		sector_t start, sector_t length)
>  {
> -	struct hd_struct *part;
> +	struct block_device *part;
>  
>  	mutex_lock(&bdev->bd_mutex);
>  	if (partition_overlaps(bdev->bd_disk, start, length, -1)) {
> @@ -475,76 +464,59 @@ int bdev_add_partition(struct block_device *bdev, int partno,
>  
>  int bdev_del_partition(struct block_device *bdev, int partno)
>  {
> -	struct block_device *bdevp;
> -	struct hd_struct *part = NULL;
> +	struct block_device *part;
>  	int ret;
>  
> -	bdevp = bdget_disk(bdev->bd_disk, partno);
> -	if (!bdevp)
> +	part = bdget_disk(bdev->bd_disk, partno);
> +	if (!part)
>  		return -ENXIO;
>  
> -	mutex_lock(&bdevp->bd_mutex);
> +	mutex_lock(&part->bd_mutex);
>  	mutex_lock_nested(&bdev->bd_mutex, 1);
>  
> -	ret = -ENXIO;
> -	part = disk_get_part(bdev->bd_disk, partno);
> -	if (!part)
> -		goto out_unlock;
> -
>  	ret = -EBUSY;
> -	if (bdevp->bd_openers)
> +	if (part->bd_openers)
>  		goto out_unlock;
>  
> -	sync_blockdev(bdevp);
> -	invalidate_bdev(bdevp);
> +	sync_blockdev(part);
> +	invalidate_bdev(part);
>  
>  	delete_partition(part);
>  	ret = 0;
>  out_unlock:
>  	mutex_unlock(&bdev->bd_mutex);
> -	mutex_unlock(&bdevp->bd_mutex);
> -	bdput(bdevp);
> -	if (part)
> -		disk_put_part(part);
> +	mutex_unlock(&part->bd_mutex);
> +	bdput(part);
>  	return ret;
>  }
>  
>  int bdev_resize_partition(struct block_device *bdev, int partno,
>  		sector_t start, sector_t length)
>  {
> -	struct block_device *bdevp;
> -	struct hd_struct *part;
> +	struct block_device *part;
>  	int ret = 0;
>  
> -	part = disk_get_part(bdev->bd_disk, partno);
> +	part = bdget_disk(bdev->bd_disk, partno);
>  	if (!part)
>  		return -ENXIO;
>  
> -	ret = -ENOMEM;
> -	bdevp = bdget_part(part);
> -	if (!bdevp)
> -		goto out_put_part;
> -
> -	mutex_lock(&bdevp->bd_mutex);
> +	mutex_lock(&part->bd_mutex);
>  	mutex_lock_nested(&bdev->bd_mutex, 1);
> -
>  	ret = -EINVAL;
> -	if (start != part->bdev->bd_start_sect)
> +	if (start != part->bd_start_sect)
>  		goto out_unlock;
>  
>  	ret = -EBUSY;
>  	if (partition_overlaps(bdev->bd_disk, start, length, partno))
>  		goto out_unlock;
>  
> -	bdev_set_nr_sectors(bdevp, length);
> +	bdev_set_nr_sectors(part, length);
>  
>  	ret = 0;
>  out_unlock:
> -	mutex_unlock(&bdevp->bd_mutex);
> +	mutex_unlock(&part->bd_mutex);
>  	mutex_unlock(&bdev->bd_mutex);
> -	bdput(bdevp);
> -out_put_part:
> -	disk_put_part(part);
> +	bdput(part);
>  	return ret;
>  }
>  
> @@ -577,7 +549,7 @@ int blk_drop_partitions(struct block_device *bdev)
>  
>  	disk_part_iter_init(&piter, bdev->bd_disk, DISK_PITER_INCL_EMPTY);
>  	while ((part = disk_part_iter_next(&piter)))
> -		delete_partition(part->bd_part);
> +		delete_partition(part);
>  	disk_part_iter_exit(&piter);
>  
>  	return 0;
> @@ -592,7 +564,7 @@ static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,
>  {
>  	sector_t size = state->parts[p].size;
>  	sector_t from = state->parts[p].from;
> -	struct hd_struct *part;
> +	struct block_device *part;
>  
>  	if (!size)
>  		return true;
> @@ -632,7 +604,7 @@ static bool blk_add_partition(struct gendisk *disk, struct block_device *bdev,
>  
>  	if (IS_BUILTIN(CONFIG_BLK_DEV_MD) &&
>  	    (state->parts[p].flags & ADDPART_FLAG_RAID))
> -		md_autodetect_dev(part_to_dev(part)->devt);
> +		md_autodetect_dev(part->bd_dev);
>  
>  	return true;
>  }
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 61cf33b6284feb..a9905d8fd02b23 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -39,7 +39,6 @@
>  
>  struct bdev_inode {
>  	struct block_device bdev;
> -	struct hd_struct hd;
>  	struct inode vfs_inode;
>  };
>  
> @@ -887,9 +886,6 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
>  		iput(inode);
>  		return NULL;
>  	}
> -	bdev->bd_part = &BDEV_I(inode)->hd;
> -	memset(bdev->bd_part, 0, sizeof(*bdev->bd_part));
> -	bdev->bd_part->bdev = bdev;
>  	return bdev;
>  }
>  
> @@ -926,11 +922,6 @@ struct block_device *bdgrab(struct block_device *bdev)
>  }
>  EXPORT_SYMBOL(bdgrab);
>  
> -struct block_device *bdget_part(struct hd_struct *part)
> -{
> -	return bdget(part_devt(part));
> -}
> -
>  long nr_blockdev_pages(void)
>  {
>  	struct inode *inode;
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 6edea5c1625909..866f74261b3ba8 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -8,6 +8,7 @@
>  
>  #include <linux/types.h>
>  #include <linux/bvec.h>
> +#include <linux/device.h>
>  #include <linux/ktime.h>
>  
>  struct bio_set;
> @@ -30,6 +31,7 @@ struct block_device {
>  	struct super_block *	bd_super;
>  	struct mutex		bd_mutex;	/* open/close mutex */
>  	void *			bd_claiming;
> +	struct device		bd_device;
>  	void *			bd_holder;
>  	int			bd_holders;
>  	bool			bd_write_holder;
> @@ -38,7 +40,6 @@ struct block_device {
>  #endif
>  	struct kobject		*bd_holder_dir;
>  	u8			bd_partno;
> -	struct hd_struct *	bd_part;
>  	/* number of times partitions within this device have been opened. */
>  	unsigned		bd_part_count;
>  
> @@ -61,8 +62,11 @@ struct block_device {
>  #define bdev_whole(_bdev) \
>  	((_bdev)->bd_disk->part0)
>  
> +#define dev_to_bdev(device) \
> +	container_of((device), struct block_device, bd_device)
> +
>  #define bdev_kobj(_bdev) \
> -	(&part_to_dev((_bdev)->bd_part)->kobj)
> +	(&((_bdev)->bd_device.kobj))
>  
>  /*
>   * Block error status values.  See block/blk-core:blk_errors for the details.
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 1d4be1fc6007c5..17cedf0dc83db0 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1999,7 +1999,6 @@ void blkdev_put_no_open(struct block_device *bdev);
>  struct block_device *bdev_alloc(struct gendisk *disk, u8 partno);
>  void bdev_add(struct block_device *bdev, dev_t dev);
>  struct block_device *I_BDEV(struct inode *inode);
> -struct block_device *bdget_part(struct hd_struct *part);
>  struct block_device *bdgrab(struct block_device *bdev);
>  void bdput(struct block_device *);
>  
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index cd23c80265b2b2..809aaa32d53cba 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -19,12 +19,6 @@
>  #include <linux/blk_types.h>
>  #include <asm/local.h>
>  
> -#define dev_to_part(device)	container_of((device), struct hd_struct, __dev)
> -#define part_to_dev(part)	(&((part)->__dev))
> -
> -#define dev_to_disk(device)	(dev_to_part(device)->bdev->bd_disk)
> -#define disk_to_dev(disk)	(part_to_dev((disk)->part0->bd_part))
> -
>  extern const struct device_type disk_type;
>  extern struct device_type part_type;
>  extern struct class block_class;
> @@ -51,11 +45,6 @@ struct partition_meta_info {
>  	u8 volname[PARTITION_META_INFO_VOLNAMELTH];
>  };
>  
> -struct hd_struct {
> -	struct block_device *bdev;
> -	struct device __dev;
> -};
> -
>  /**
>   * DOC: genhd capability flags
>   *
> @@ -190,19 +179,21 @@ struct gendisk {
>  	struct lockdep_map lockdep_map;
>  };
>  
> +/*
> + * The gendisk is refcounted by the part0 block_device, and the bd_device
> + * therein is also used for device model presentation in sysfs.
> + */
> +#define dev_to_disk(device) \
> +	(dev_to_bdev(device)->bd_disk)
> +#define disk_to_dev(disk) \
> +	(&((disk)->part0->bd_device))
> +
>  #if IS_REACHABLE(CONFIG_CDROM)
>  #define disk_to_cdi(disk)	((disk)->cdi)
>  #else
>  #define disk_to_cdi(disk)	NULL
>  #endif
>  
> -static inline struct gendisk *part_to_disk(struct hd_struct *part)
> -{
> -	if (unlikely(!part))
> -		return NULL;
> -	return part->bdev->bd_disk;
> -}
> -
>  static inline int disk_max_parts(struct gendisk *disk)
>  {
>  	if (disk->flags & GENHD_FL_EXT_DEVT)
> @@ -221,19 +212,6 @@ static inline dev_t disk_devt(struct gendisk *disk)
>  	return MKDEV(disk->major, disk->first_minor);
>  }
>  
> -static inline dev_t part_devt(struct hd_struct *part)
> -{
> -	return part_to_dev(part)->devt;
> -}
> -
> -extern struct hd_struct *disk_get_part(struct gendisk *disk, int partno);
> -
> -static inline void disk_put_part(struct hd_struct *part)
> -{
> -	if (likely(part))
> -		put_device(part_to_dev(part));
> -}
> -
>  /*
>   * Smarter partition iterator without context limits.
>   */
> diff --git a/init/do_mounts.c b/init/do_mounts.c
> index 86bef93e72ebd6..a78e44ee6adb8d 100644
> --- a/init/do_mounts.c
> +++ b/init/do_mounts.c
> @@ -76,11 +76,11 @@ struct uuidcmp {
>   */
>  static int match_dev_by_uuid(struct device *dev, const void *data)
>  {
> +	struct block_device *bdev = dev_to_bdev(dev);
>  	const struct uuidcmp *cmp = data;
> -	struct hd_struct *part = dev_to_part(dev);
>  
> -	if (!part->bdev->bd_meta_info ||
> -	    strncasecmp(cmp->uuid, part->bdev->bd_meta_info->uuid, cmp->len))
> +	if (!bdev->bd_meta_info ||
> +	    strncasecmp(cmp->uuid, bdev->bd_meta_info->uuid, cmp->len))
>  		return 0;
>  	return 1;
>  }
> @@ -133,13 +133,13 @@ static dev_t devt_from_partuuid(const char *uuid_str)
>  		 * Attempt to find the requested partition by adding an offset
>  		 * to the partition number found by UUID.
>  		 */
> -		struct hd_struct *part;
> +		struct block_device *part;
>  
> -		part = disk_get_part(dev_to_disk(dev),
> -				     dev_to_part(dev)->bdev->bd_partno + offset);
> +		part = bdget_disk(dev_to_disk(dev),
> +				  dev_to_bdev(dev)->bd_partno + offset);
>  		if (part) {
> -			devt = part_devt(part);
> -			put_device(part_to_dev(part));
> +			devt = part->bd_dev;
> +			bdput(part);
>  		}
>  	} else {
>  		devt = dev->devt;
> @@ -166,11 +166,10 @@ static dev_t devt_from_partuuid(const char *uuid_str)
>   */
>  static int match_dev_by_label(struct device *dev, const void *data)
>  {
> +	struct block_device *bdev = dev_to_bdev(dev);
>  	const char *label = data;
> -	struct hd_struct *part = dev_to_part(dev);
>  
> -	if (!part->bdev->bd_meta_info ||
> -	    strcmp(label, part->bdev->bd_meta_info->volname))
> +	if (!bdev->bd_meta_info || strcmp(label, bdev->bd_meta_info->volname))
>  		return 0;
>  	return 1;
>  }
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index 8a723a91ec5a06..a482a37848bff7 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -1810,30 +1810,15 @@ static ssize_t blk_trace_mask2str(char *buf, int mask)
>  	return p - buf;
>  }
>  
> -static struct request_queue *blk_trace_get_queue(struct block_device *bdev)
> -{
> -	if (bdev->bd_disk == NULL)
> -		return NULL;
> -
> -	return bdev_get_queue(bdev);
> -}
> -
>  static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
>  					 struct device_attribute *attr,
>  					 char *buf)
>  {
> -	struct block_device *bdev = bdget_part(dev_to_part(dev));
> -	struct request_queue *q;
> +	struct block_device *bdev = dev_to_bdev(dev);
> +	struct request_queue *q = bdev_get_queue(bdev);
>  	struct blk_trace *bt;
>  	ssize_t ret = -ENXIO;
>  
> -	if (bdev == NULL)
> -		goto out;
> -
> -	q = blk_trace_get_queue(bdev);
> -	if (q == NULL)
> -		goto out_bdput;
> -
>  	mutex_lock(&q->debugfs_mutex);
>  
>  	bt = rcu_dereference_protected(q->blk_trace,
> @@ -1856,9 +1841,6 @@ static ssize_t sysfs_blk_trace_attr_show(struct device *dev,
>  
>  out_unlock_bdev:
>  	mutex_unlock(&q->debugfs_mutex);
> -out_bdput:
> -	bdput(bdev);
> -out:
>  	return ret;
>  }
>  
> @@ -1866,8 +1848,8 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
>  					  struct device_attribute *attr,
>  					  const char *buf, size_t count)
>  {
> -	struct block_device *bdev;
> -	struct request_queue *q;
> +	struct block_device *bdev = dev_to_bdev(dev);
> +	struct request_queue *q = bdev_get_queue(bdev);
>  	struct blk_trace *bt;
>  	u64 value;
>  	ssize_t ret = -EINVAL;
> @@ -1883,17 +1865,10 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
>  				goto out;
>  			value = ret;
>  		}
> -	} else if (kstrtoull(buf, 0, &value))
> -		goto out;
> -
> -	ret = -ENXIO;
> -	bdev = bdget_part(dev_to_part(dev));
> -	if (bdev == NULL)
> -		goto out;
> -
> -	q = blk_trace_get_queue(bdev);
> -	if (q == NULL)
> -		goto out_bdput;
> +	} else {
> +		if (kstrtoull(buf, 0, &value))
> +			goto out;
> +	}
>  
>  	mutex_lock(&q->debugfs_mutex);
>  
> @@ -1931,8 +1906,6 @@ static ssize_t sysfs_blk_trace_attr_store(struct device *dev,
>  
>  out_unlock_bdev:
>  	mutex_unlock(&q->debugfs_mutex);
> -out_bdput:
> -	bdput(bdev);
>  out:
>  	return ret ? ret : count;
>  }
> -- 
> 2.29.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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