Re: [PATCH v2] blkdev: Replace blksize_bits() with ilog2()

From: Christoph Hellwig <hch@lst.de>
To: Kaitao Cheng <pilgrimtao@gmail.com>
Cc: axboe@kernel.dk, hch@lst.de, sth@linux.ibm.com,
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	ming.lei@redhat.com, martin.petersen@oracle.com,
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	houtao1@huawei.com, asml.silence@gmail.com, ajay.joshi@wdc.com,
	linux-kernel@vger.kernel.org, songmuchun@bytedance.com,
	hoeppner@linux.ibm.com, heiko.carstens@de.ibm.com,
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Subject: Re: [PATCH v2] blkdev: Replace blksize_bits() with ilog2()
Date: Fri, 29 May 2020 16:15:55 +0200	[thread overview]
Message-ID: <20200529141555.GA3249@lst.de> (raw)
In-Reply-To: <20200529141100.37519-1-pilgrimtao@gmail.com>

>  	ns->size = i_size_read(ns->bdev->bd_inode);
> -	ns->blksize_shift = blksize_bits(bdev_logical_block_size(ns->bdev));
> +	ns->blksize_shift = ilog2(bdev_logical_block_size(ns->bdev));

This should just be:

	ns->blksize_shift = ns->bdev->bd_inode->i_blkbits;

> diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c
> index 777734d1b4e5..55adb134451b 100644
> --- a/drivers/s390/block/dasd_ioctl.c
> +++ b/drivers/s390/block/dasd_ioctl.c
> @@ -228,7 +228,7 @@ dasd_format(struct dasd_block *block, struct format_data_t *fdata)
>  	 */
>  	if (fdata->start_unit == 0) {
>  		struct block_device *bdev = bdget_disk(block->gdp, 0);
> -		bdev->bd_inode->i_blkbits = blksize_bits(fdata->blksize);
> +		bdev->bd_inode->i_blkbits = ilog2(fdata->blksize);

This also needs to set bdev->bd_block_size, so this probably warrants
a separate fix that be backported.  It might be nice to split out
a helper that sets bd_block_size and bd_inode->i_blkbits together
so that such a use is more obvious.

>  	} else if (inode->i_bdev) {
>  		blksize = bdev_logical_block_size(inode->i_bdev);
> -		blkbits = blksize_bits(blksize);
> +		blkbits = ilog2(blksize);

This can just use inode->i_bdev->bd_inode->i_blkbits.

> diff --git a/fs/buffer.c b/fs/buffer.c
> index fc8831c392d7..fa92e0afe349 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -907,7 +907,7 @@ static sector_t blkdev_max_block(struct block_device *bdev, unsigned int size)
>  	loff_t sz = i_size_read(bdev->bd_inode);
>  
>  	if (sz) {
> -		unsigned int sizebits = blksize_bits(size);
> +		unsigned int sizebits = ilog2(size);

bdev->bd_inode->i_blkbits.

> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 1543b5af400e..7ea2cd3effcc 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -1148,7 +1148,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  
>  	if (align & blocksize_mask) {
>  		if (bdev)
> -			blkbits = blksize_bits(bdev_logical_block_size(bdev));
> +			blkbits = ilog2(bdev_logical_block_size(bdev));

bdev->bd_inode->i_blkbits.

> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index cb05f71cf850..b896da27942a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -3458,7 +3458,7 @@ static int check_direct_IO(struct inode *inode, struct iov_iter *iter,
>  
>  	if (align & blocksize_mask) {
>  		if (bdev)
> -			blkbits = blksize_bits(bdev_logical_block_size(bdev));
> +			blkbits = ilog2(bdev_logical_block_size(bdev));

bdev->bd_inode->i_blkbits.

>  		blocksize_mask = (1 << blkbits) - 1;
>  		if (align & blocksize_mask)
>  			return -EINVAL;
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index ec7b78e6feca..2a807657d544 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -203,7 +203,7 @@ static loff_t
>  iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
>  		struct iomap_dio *dio, struct iomap *iomap)
>  {
> -	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
> +	unsigned int blkbits = ilog2(bdev_logical_block_size(iomap->bdev));

iomap->bdev->bd_inode->i_blkbits.