On Sun, Jul 25 2021 at 1:54P -0400,
Christoph Hellwig <hch@xxxxxx> wrote:
> Move the block holder code into a separate file as it is not in any way
> related to the other block_dev.c code, and add a new selectable config
> option for it so that we don't have to build it without any remapped
> drivers selected.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> block/Kconfig | 4 ++
> block/Makefile | 1 +
> block/holder.c | 139 ++++++++++++++++++++++++++++++++++++
> drivers/md/Kconfig | 2 +
> drivers/md/bcache/Kconfig | 1 +
> fs/block_dev.c | 144 +-------------------------------------
> include/linux/blk_types.h | 2 +-
> include/linux/genhd.h | 4 +-
> 8 files changed, 151 insertions(+), 146 deletions(-)
> create mode 100644 block/holder.c
>
> diff --git a/block/Kconfig b/block/Kconfig
> index fd732aede922..a24d7263d1fc 100644
> --- a/block/Kconfig
> +++ b/block/Kconfig
> @@ -251,4 +251,8 @@ config BLK_MQ_RDMA
> config BLK_PM
> def_bool BLOCK && PM
>
> +# do not use in new code
> +config BLOCK_HOLDER_DEPRECATED
> + bool
> +
What is it that new code that does IO remapping and device stacking
_should_ be using!? Seems the whole "do not use" and "DEPRECATED" is
a misnomer.
But those nits aside, code looks fine mechnically:
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> source "block/Kconfig.iosched"
> diff --git a/block/Makefile b/block/Makefile
> index bfbe4e13ca1e..6fc6216634ed 100644
> --- a/block/Makefile
> +++ b/block/Makefile
> @@ -42,3 +42,4 @@ obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o
> obj-$(CONFIG_BLK_PM) += blk-pm.o
> obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += keyslot-manager.o blk-crypto.o
> obj-$(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) += blk-crypto-fallback.o
> +obj-$(CONFIG_BLOCK_HOLDER_DEPRECATED) += holder.o
> diff --git a/block/holder.c b/block/holder.c
> new file mode 100644
> index 000000000000..904a1dcd5c12
> --- /dev/null
> +++ b/block/holder.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/genhd.h>
> +
> +struct bd_holder_disk {
> + struct list_head list;
> + struct gendisk *disk;
> + int refcnt;
> +};
> +
> +static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
> + struct gendisk *disk)
> +{
> + struct bd_holder_disk *holder;
> +
> + list_for_each_entry(holder, &bdev->bd_holder_disks, list)
> + if (holder->disk == disk)
> + return holder;
> + return NULL;
> +}
> +
> +static int add_symlink(struct kobject *from, struct kobject *to)
> +{
> + return sysfs_create_link(from, to, kobject_name(to));
> +}
> +
> +static void del_symlink(struct kobject *from, struct kobject *to)
> +{
> + sysfs_remove_link(from, kobject_name(to));
> +}
> +
> +/**
> + * bd_link_disk_holder - create symlinks between holding disk and slave bdev
> + * @bdev: the claimed slave bdev
> + * @disk: the holding disk
> + *
> + * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
> + *
> + * This functions creates the following sysfs symlinks.
> + *
> + * - from "slaves" directory of the holder @disk to the claimed @bdev
> + * - from "holders" directory of the @bdev to the holder @disk
> + *
> + * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
> + * passed to bd_link_disk_holder(), then:
> + *
> + * /sys/block/dm-0/slaves/sda --> /sys/block/sda
> + * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
> + *
> + * The caller must have claimed @bdev before calling this function and
> + * ensure that both @bdev and @disk are valid during the creation and
> + * lifetime of these symlinks.
> + *
> + * CONTEXT:
> + * Might sleep.
> + *
> + * RETURNS:
> + * 0 on success, -errno on failure.
> + */
> +int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
> +{
> + struct bd_holder_disk *holder;
> + int ret = 0;
> +
> + mutex_lock(&bdev->bd_disk->open_mutex);
> +
> + WARN_ON_ONCE(!bdev->bd_holder);
> +
> + /* FIXME: remove the following once add_disk() handles errors */
> + if (WARN_ON(!disk->slave_dir || !bdev->bd_holder_dir))
> + goto out_unlock;
> +
> + holder = bd_find_holder_disk(bdev, disk);
> + if (holder) {
> + holder->refcnt++;
> + goto out_unlock;
> + }
> +
> + holder = kzalloc(sizeof(*holder), GFP_KERNEL);
> + if (!holder) {
> + ret = -ENOMEM;
> + goto out_unlock;
> + }
> +
> + INIT_LIST_HEAD(&holder->list);
> + holder->disk = disk;
> + holder->refcnt = 1;
> +
> + ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
> + if (ret)
> + goto out_free;
> +
> + ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
> + if (ret)
> + goto out_del;
> + /*
> + * bdev could be deleted beneath us which would implicitly destroy
> + * the holder directory. Hold on to it.
> + */
> + kobject_get(bdev->bd_holder_dir);
> +
> + list_add(&holder->list, &bdev->bd_holder_disks);
> + goto out_unlock;
> +
> +out_del:
> + del_symlink(disk->slave_dir, bdev_kobj(bdev));
> +out_free:
> + kfree(holder);
> +out_unlock:
> + mutex_unlock(&bdev->bd_disk->open_mutex);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(bd_link_disk_holder);
> +
> +/**
> + * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
> + * @bdev: the calimed slave bdev
> + * @disk: the holding disk
> + *
> + * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
> + *
> + * CONTEXT:
> + * Might sleep.
> + */
> +void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
> +{
> + struct bd_holder_disk *holder;
> +
> + mutex_lock(&bdev->bd_disk->open_mutex);
> + holder = bd_find_holder_disk(bdev, disk);
> + if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
> + del_symlink(disk->slave_dir, bdev_kobj(bdev));
> + del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
> + kobject_put(bdev->bd_holder_dir);
> + list_del_init(&holder->list);
> + kfree(holder);
> + }
> + mutex_unlock(&bdev->bd_disk->open_mutex);
> +}
> +EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
> index 0602e82a9516..f821dae101a9 100644
> --- a/drivers/md/Kconfig
> +++ b/drivers/md/Kconfig
> @@ -15,6 +15,7 @@ if MD
>
> config BLK_DEV_MD
> tristate "RAID support"
> + select BLOCK_HOLDER_DEPRECATED if SYSFS
> help
> This driver lets you combine several hard disk partitions into one
> logical block device. This can be used to simply append one
> @@ -201,6 +202,7 @@ config BLK_DEV_DM_BUILTIN
>
> config BLK_DEV_DM
> tristate "Device mapper support"
> + select BLOCK_HOLDER_DEPRECATED if SYSFS
> select BLK_DEV_DM_BUILTIN
> depends on DAX || DAX=n
> help
> diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig
> index d1ca4d059c20..cf3e8096942a 100644
> --- a/drivers/md/bcache/Kconfig
> +++ b/drivers/md/bcache/Kconfig
> @@ -2,6 +2,7 @@
>
> config BCACHE
> tristate "Block device as cache"
> + select BLOCK_HOLDER_DEPRECATED if SYSFS
> select CRC64
> help
> Allows a block device to be used as cache for other devices; uses
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 0c424a0cadaa..7825d152634e 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -900,7 +900,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
> bdev->bd_disk = disk;
> bdev->bd_partno = partno;
> bdev->bd_inode = inode;
> -#ifdef CONFIG_SYSFS
> +#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
> INIT_LIST_HEAD(&bdev->bd_holder_disks);
> #endif
> bdev->bd_stats = alloc_percpu(struct disk_stats);
> @@ -1092,148 +1092,6 @@ void bd_abort_claiming(struct block_device *bdev, void *holder)
> }
> EXPORT_SYMBOL(bd_abort_claiming);
>
> -#ifdef CONFIG_SYSFS
> -struct bd_holder_disk {
> - struct list_head list;
> - struct gendisk *disk;
> - int refcnt;
> -};
> -
> -static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
> - struct gendisk *disk)
> -{
> - struct bd_holder_disk *holder;
> -
> - list_for_each_entry(holder, &bdev->bd_holder_disks, list)
> - if (holder->disk == disk)
> - return holder;
> - return NULL;
> -}
> -
> -static int add_symlink(struct kobject *from, struct kobject *to)
> -{
> - return sysfs_create_link(from, to, kobject_name(to));
> -}
> -
> -static void del_symlink(struct kobject *from, struct kobject *to)
> -{
> - sysfs_remove_link(from, kobject_name(to));
> -}
> -
> -/**
> - * bd_link_disk_holder - create symlinks between holding disk and slave bdev
> - * @bdev: the claimed slave bdev
> - * @disk: the holding disk
> - *
> - * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
> - *
> - * This functions creates the following sysfs symlinks.
> - *
> - * - from "slaves" directory of the holder @disk to the claimed @bdev
> - * - from "holders" directory of the @bdev to the holder @disk
> - *
> - * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
> - * passed to bd_link_disk_holder(), then:
> - *
> - * /sys/block/dm-0/slaves/sda --> /sys/block/sda
> - * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
> - *
> - * The caller must have claimed @bdev before calling this function and
> - * ensure that both @bdev and @disk are valid during the creation and
> - * lifetime of these symlinks.
> - *
> - * CONTEXT:
> - * Might sleep.
> - *
> - * RETURNS:
> - * 0 on success, -errno on failure.
> - */
> -int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
> -{
> - struct bd_holder_disk *holder;
> - int ret = 0;
> -
> - mutex_lock(&bdev->bd_disk->open_mutex);
> -
> - WARN_ON_ONCE(!bdev->bd_holder);
> -
> - /* FIXME: remove the following once add_disk() handles errors */
> - if (WARN_ON(!disk->slave_dir || !bdev->bd_holder_dir))
> - goto out_unlock;
> -
> - holder = bd_find_holder_disk(bdev, disk);
> - if (holder) {
> - holder->refcnt++;
> - goto out_unlock;
> - }
> -
> - holder = kzalloc(sizeof(*holder), GFP_KERNEL);
> - if (!holder) {
> - ret = -ENOMEM;
> - goto out_unlock;
> - }
> -
> - INIT_LIST_HEAD(&holder->list);
> - holder->disk = disk;
> - holder->refcnt = 1;
> -
> - ret = add_symlink(disk->slave_dir, bdev_kobj(bdev));
> - if (ret)
> - goto out_free;
> -
> - ret = add_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
> - if (ret)
> - goto out_del;
> - /*
> - * bdev could be deleted beneath us which would implicitly destroy
> - * the holder directory. Hold on to it.
> - */
> - kobject_get(bdev->bd_holder_dir);
> -
> - list_add(&holder->list, &bdev->bd_holder_disks);
> - goto out_unlock;
> -
> -out_del:
> - del_symlink(disk->slave_dir, bdev_kobj(bdev));
> -out_free:
> - kfree(holder);
> -out_unlock:
> - mutex_unlock(&bdev->bd_disk->open_mutex);
> - return ret;
> -}
> -EXPORT_SYMBOL_GPL(bd_link_disk_holder);
> -
> -/**
> - * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
> - * @bdev: the calimed slave bdev
> - * @disk: the holding disk
> - *
> - * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
> - *
> - * CONTEXT:
> - * Might sleep.
> - */
> -void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
> -{
> - struct bd_holder_disk *holder;
> -
> - mutex_lock(&bdev->bd_disk->open_mutex);
> -
> - holder = bd_find_holder_disk(bdev, disk);
> -
> - if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
> - del_symlink(disk->slave_dir, bdev_kobj(bdev));
> - del_symlink(bdev->bd_holder_dir, &disk_to_dev(disk)->kobj);
> - kobject_put(bdev->bd_holder_dir);
> - list_del_init(&holder->list);
> - kfree(holder);
> - }
> -
> - mutex_unlock(&bdev->bd_disk->open_mutex);
> -}
> -EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
> -#endif
> -
> static void blkdev_flush_mapping(struct block_device *bdev)
> {
> WARN_ON_ONCE(bdev->bd_holders);
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 290f9061b29a..7a4e139d24ef 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -34,7 +34,7 @@ struct block_device {
> void * bd_holder;
> int bd_holders;
> bool bd_write_holder;
> -#ifdef CONFIG_SYSFS
> +#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
> struct list_head bd_holder_disks;
> #endif
> struct kobject *bd_holder_dir;
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index 13b34177cc85..6831d74f2002 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -316,7 +316,7 @@ void set_capacity(struct gendisk *disk, sector_t size);
> int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
> long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
>
> -#ifdef CONFIG_SYSFS
> +#ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
> int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
> void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk);
> #else
> @@ -329,7 +329,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev,
> struct gendisk *disk)
> {
> }
> -#endif /* CONFIG_SYSFS */
> +#endif /* CONFIG_BLOCK_HOLDER_DEPRECATED */
>
> dev_t part_devt(struct gendisk *disk, u8 partno);
> dev_t blk_lookup_devt(const char *name, int partno);
> --
> 2.30.2
>
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