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block: make the block holder code optional 

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.

The Kconfig symbol contains a _DEPRECATED suffix to match the comments
added in commit 49731baa41
("block: restore multiple bd_link_disk_holder() support").

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20210804094147.459763-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-08-04 11:41:40 +02:00 committed by Jens Axboe
parent 2112f5c133
commit c66fd01971
8 changed files with 151 additions and 146 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
block/Kconfig
View File

@ -241,4 +241,8 @@ config BLK_MQ_RDMA
config BLK_PM
def_bool BLOCK && PM
# do not use in new code
config BLOCK_HOLDER_DEPRECATED
bool
source "block/Kconfig.iosched"

1
block/Makefile
View File

@ -41,3 +41,4 @@ 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

139
block/holder.c Normal file
View File

@ -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);

2
drivers/md/Kconfig
View File

@ -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

1
drivers/md/bcache/Kconfig
View File

@ -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

144
fs/block_dev.c
View File

@ -902,7 +902,7 @@ 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);
@ -1063,148 +1063,6 @@ 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);

2
include/linux/blk_types.h
View File

@ -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;

4
include/linux/genhd.h
View File

@ -318,7 +318,7 @@ 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
@ -331,7 +331,7 @@ 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);
void inc_diskseq(struct gendisk *disk);