[PATCH 66/78] block: keep a block_device reference for each hd_struct

[Hannes Reinecke]

On 11/16/20 3:57 PM, Christoph Hellwig wrote:
> To simplify block device lookup and a few other upcomdin areas, make sure
> that we always have a struct block_device available for each disk and
> each partition.  The only downside of this is that each device and
> partition uses a little more memories.  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.
> 
> As part of the change switch bdget() to only find existing block devices,
> given that we know that the block_device structure must be allocated at
> probe / partition scan time.
> 
> blk-cgroup needed a bit of a special treatment as the only place that
> wanted to lookup a gendisk outside of the normal blkdev_get path.  It is
> switched to lookup using the block device hash now that this is the
> primary lookup path.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   block/blk-cgroup.c         |  42 ++++-----
>   block/blk-iocost.c         |  36 +++----
>   block/blk.h                |   1 -
>   block/genhd.c              | 188 +++----------------------------------
>   block/partitions/core.c    |  28 +++---
>   fs/block_dev.c             | 133 +++++++++++++++-----------
>   include/linux/blk-cgroup.h |   4 +-
>   include/linux/blkdev.h     |   3 +
>   include/linux/genhd.h      |   4 +-
>   9 files changed, 153 insertions(+), 286 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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