[PATCH] iomap: directly use logical block size

[PATCH] iomap: directly use logical block size

[Keith Busch]

From: Keith Busch <kbusch@kernel.org>

Don't transform the logical block size to a bit shift only to shift it
back to the original block size. Just use the size.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 fs/iomap/direct-io.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 4eb559a16c9e..503b97e5a115 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -240,7 +240,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
 {
 	const struct iomap *iomap = &iter->iomap;
 	struct inode *inode = iter->inode;
-	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
+	unsigned int blksz = bdev_logical_block_size(iomap->bdev);
 	unsigned int fs_block_size = i_blocksize(inode), pad;
 	loff_t length = iomap_length(iter);
 	loff_t pos = iter->pos;
@@ -252,7 +252,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
 	size_t copied = 0;
 	size_t orig_count;
 
-	if ((pos | length) & ((1 << blkbits) - 1) ||
+	if ((pos | length) & (blksz - 1) ||
 	    !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
 		return -EINVAL;
 
-- 
2.30.2

Re: [PATCH] iomap: directly use logical block size

[Chaitanya Kulkarni]

On 10/26/2022 9:51 AM, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Don't transform the logical block size to a bit shift only to shift it
> back to the original block size. Just use the size.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---

we should also change any other callers like this.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

Re: [PATCH] iomap: directly use logical block size

[Darrick J. Wong]

On Wed, Oct 26, 2022 at 09:51:33AM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Don't transform the logical block size to a bit shift only to shift it
> back to the original block size. Just use the size.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>  fs/iomap/direct-io.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 4eb559a16c9e..503b97e5a115 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -240,7 +240,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>  {
>  	const struct iomap *iomap = &iter->iomap;
>  	struct inode *inode = iter->inode;
> -	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
> +	unsigned int blksz = bdev_logical_block_size(iomap->bdev);

/me looks at what blksize_bits does (assumes block size > 256) and rolls
his eyes.

Regardless, this looks correct to me, so

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D


>  	unsigned int fs_block_size = i_blocksize(inode), pad;
>  	loff_t length = iomap_length(iter);
>  	loff_t pos = iter->pos;
> @@ -252,7 +252,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>  	size_t copied = 0;
>  	size_t orig_count;
>  
> -	if ((pos | length) & ((1 << blkbits) - 1) ||
> +	if ((pos | length) & (blksz - 1) ||
>  	    !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
>  		return -EINVAL;
>  
> -- 
> 2.30.2
> 

Re: [PATCH] iomap: directly use logical block size

[Bart Van Assche]

On 10/26/22 09:51, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Don't transform the logical block size to a bit shift only to shift it
> back to the original block size. Just use the size.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>   fs/iomap/direct-io.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 4eb559a16c9e..503b97e5a115 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -240,7 +240,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>   {
>   	const struct iomap *iomap = &iter->iomap;
>   	struct inode *inode = iter->inode;
> -	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
> +	unsigned int blksz = bdev_logical_block_size(iomap->bdev);
>   	unsigned int fs_block_size = i_blocksize(inode), pad;
>   	loff_t length = iomap_length(iter);
>   	loff_t pos = iter->pos;
> @@ -252,7 +252,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
>   	size_t copied = 0;
>   	size_t orig_count;
>   
> -	if ((pos | length) & ((1 << blkbits) - 1) ||
> +	if ((pos | length) & (blksz - 1) ||
>   	    !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
>   		return -EINVAL;

Reviewed-by: Bart Van Assche <bvanassche@acm.org>

Re: [PATCH] iomap: directly use logical block size

[Christoph Hellwig]

On Wed, Oct 26, 2022 at 09:51:33AM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> Don't transform the logical block size to a bit shift only to shift it
> back to the original block size. Just use the size.

This looks reasonable.  But given that the blksz variable is only used
once, why not open code the bdev_logical_block_size in the conditional?