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| author | Christoph Hellwig <hch@lst.de> | 2020-11-26 09:23:26 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-12-01 14:53:39 -0700 |
| commit | 22ae8ce8b89241c94ac00c237752c0ffa37ba5ae (patch) | |
| tree | af6d4dfd72e76789c25c64cd1765f037d91f6b72 /include/linux/genhd.h | |
| parent | 4e7b5671c6a883d94b5428e1a9c141bbd56cb2a6 (diff) | |
| download | lwn-22ae8ce8b89241c94ac00c237752c0ffa37ba5ae.tar.gz lwn-22ae8ce8b89241c94ac00c237752c0ffa37ba5ae.zip | |
block: simplify bdev/disk lookup in blkdev_get
To simplify block device lookup and a few other upcoming areas, make sure
that we always have a struct block_device available for each disk and
each partition, and only find existing block devices in bdget. The only
downside of this is that each device and partition uses a little more
memory. The upside will be that a lot of code can be simplified.
With that all we need to look up the block device is to lookup the inode
and do a few sanity checks on the gendisk, instead of the separate lookup
for the gendisk. For blk-cgroup which wants to access a gendisk without
opening it, a new blkdev_{get,put}_no_open low-level interface is added
to replace the previous get_gendisk use.
Note that the change to look up block device directly instead of the two
step lookup using struct gendisk causes a subtile change in behavior:
accessing a non-existing partition on an existing block device can now
cause a call to request_module. That call is harmless, and in practice
no recent system will access these nodes as they aren't created by udev
and static /dev/ setups are unusual.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'include/linux/genhd.h')
| -rw-r--r-- | include/linux/genhd.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/genhd.h b/include/linux/genhd.h index ca5e356084c3..42a51653c730 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -65,6 +65,7 @@ struct hd_struct { struct disk_stats __percpu *dkstats; struct percpu_ref ref; + struct block_device *bdev; struct device __dev; struct kobject *holder_dir; int policy, partno; @@ -193,7 +194,6 @@ struct gendisk { int flags; unsigned long state; #define GD_NEED_PART_SCAN 0 - struct rw_semaphore lookup_sem; struct kobject *slave_dir; struct timer_rand_state *random; @@ -300,7 +300,6 @@ static inline void add_disk_no_queue_reg(struct gendisk *disk) } extern void del_gendisk(struct gendisk *gp); -extern struct gendisk *get_gendisk(dev_t dev, int *partno); extern struct block_device *bdget_disk(struct gendisk *disk, int partno); extern void set_disk_ro(struct gendisk *disk, int flag); @@ -338,7 +337,6 @@ int blk_drop_partitions(struct block_device *bdev); extern struct gendisk *__alloc_disk_node(int minors, int node_id); extern void put_disk(struct gendisk *disk); -extern void put_disk_and_module(struct gendisk *disk); #define alloc_disk_node(minors, node_id) \ ({ \ @@ -388,7 +386,10 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev, } #endif /* CONFIG_SYSFS */ +extern struct rw_semaphore bdev_lookup_sem; + dev_t blk_lookup_devt(const char *name, int partno); +void blk_request_module(dev_t devt); #ifdef CONFIG_BLOCK void printk_all_partitions(void); #else /* CONFIG_BLOCK */ |