Re: [PATCH 55/78] block: change the hash used for looking up block devices

Hannes Reinecke
2020-11-20T07:26:33Z

On 11/16/20 3:57 PM, Christoph Hellwig wrote:
> Adding the minor to the major creates tons of pointless conflicts. Just
> use the dev_t itself, which is 32-bits and thus is guaranteed to fit
> into ino_t.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/block_dev.c | 26 ++------------------------
> 1 file changed, 2 insertions(+), 24 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index d8664f5c1ff669..29db12c3bb501c 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -870,35 +870,12 @@ void __init bdev_cache_init(void)
> blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
> }
>
> -/*
> - * Most likely _very_ bad one - but then it's hardly critical for small
> - * /dev and can be fixed when somebody will need really large one.
> - * Keep in mind that it will be fed through icache hash function too.
> - */
> -static inline unsigned long hash(dev_t dev)
> -{
> - return MAJOR(dev)+MINOR(dev);
> -}
> -
> -static int bdev_test(struct inode *inode, void *data)
> -{
> - return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
> -}
> -
> -static int bdev_set(struct inode *inode, void *data)
> -{
> - BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
> - return 0;
> -}
> -
> static struct block_device *bdget(dev_t dev)
> {
> struct block_device *bdev;
> struct inode *inode;
>
> - inode = iget5_locked(blockdev_superblock, hash(dev),
> - bdev_test, bdev_set, &dev);
> -
> + inode = iget_locked(blockdev_superblock, dev);
> if (!inode)
> return NULL;
>
> @@ -910,6 +887,7 @@ static struct block_device *bdget(dev_t dev)
> bdev->bd_super = NULL;
> bdev->bd_inode = inode;
> bdev->bd_part_count = 0;
> + bdev->bd_dev = dev;
> inode->i_mode = S_IFBLK;
> inode->i_rdev = dev;
> inode->i_bdev = bdev;
>
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer