[PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Nikolay Borisov]

We already get the block counts and the calculate the end block at the
beginning of the function. Let's use the local variables for consistency and
readability. No functional changes

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/direct-io.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 08cf27811e5a..987bc17a5f5e 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1139,7 +1139,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	}
 
 	/* watch out for a 0 len io from a tricksy fs */
-	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
+	if (iov_iter_rw(iter) == READ && !count)
 		return 0;
 
 	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
@@ -1248,8 +1248,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 
 	dio->should_dirty = (iter->type == ITER_IOVEC);
 	sdio.iter = iter;
-	sdio.final_block_in_request =
-		(offset + iov_iter_count(iter)) >> blkbits;
+	sdio.final_block_in_request = end >> blkbits;
 
 	/*
 	 * In case of non-aligned buffers, we may need 2 more
-- 
2.7.4

Re: [PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Jeff Moyer]

Nikolay Borisov <nborisov@suse.com> writes:

> We already get the block counts and the calculate the end block at the
> beginning of the function. Let's use the local variables for consistency and
> readability. No functional changes
>
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>

Looks ok to me.

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>

Re: [PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Nikolay Borisov]

On  2.08.2017 10:10, Nikolay Borisov wrote:
> We already get the block counts and the calculate the end block at the
> beginning of the function. Let's use the local variables for consistency and
> readability. No functional changes
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---

ping

>  fs/direct-io.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 08cf27811e5a..987bc17a5f5e 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -1139,7 +1139,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  	}
>  
>  	/* watch out for a 0 len io from a tricksy fs */
> -	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
> +	if (iov_iter_rw(iter) == READ && !count)
>  		return 0;
>  
>  	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
> @@ -1248,8 +1248,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  
>  	dio->should_dirty = (iter->type == ITER_IOVEC);
>  	sdio.iter = iter;
> -	sdio.final_block_in_request =
> -		(offset + iov_iter_count(iter)) >> blkbits;
> +	sdio.final_block_in_request = end >> blkbits;
>  
>  	/*
>  	 * In case of non-aligned buffers, we may need 2 more
> 

Re: [PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Nikolay Borisov]

On  2.08.2017 10:10, Nikolay Borisov wrote:
> We already get the block counts and the calculate the end block at the
> beginning of the function. Let's use the local variables for consistency and
> readability. No functional changes
> 
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/direct-io.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 08cf27811e5a..987bc17a5f5e 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -1139,7 +1139,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  	}
>  
>  	/* watch out for a 0 len io from a tricksy fs */
> -	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
> +	if (iov_iter_rw(iter) == READ && !count)
>  		return 0;
>  
>  	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
> @@ -1248,8 +1248,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  
>  	dio->should_dirty = (iter->type == ITER_IOVEC);
>  	sdio.iter = iter;
> -	sdio.final_block_in_request =
> -		(offset + iov_iter_count(iter)) >> blkbits;
> +	sdio.final_block_in_request = end >> blkbits;
>  
>  	/*
>  	 * In case of non-aligned buffers, we may need 2 more
> 


Ping on that forgotten one :)

[PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Nikolay Borisov]

We already get the block counts and the calculate the end block at the
beginning of the function. Let's use the local variables for consistency and
readability. No functional changes

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
---
Andrew, 

Sending to you since this has been languishing on the mailing for quite some 
time. The patch has been reviewed here:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1460544.html

fs/direct-io.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index a8131087aa1c..a73448a501c2 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1200,7 +1200,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	}
 
 	/* watch out for a 0 len io from a tricksy fs */
-	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
+	if (iov_iter_rw(iter) == READ && !count)
 		return 0;
 
 	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
@@ -1316,8 +1316,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 
 	dio->should_dirty = (iter->type == ITER_IOVEC);
 	sdio.iter = iter;
-	sdio.final_block_in_request =
-		(offset + iov_iter_count(iter)) >> blkbits;
+	sdio.final_block_in_request = end >> blkbits;
 
 	/*
 	 * In case of non-aligned buffers, we may need 2 more
-- 
2.7.4

Re: [PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Andrew Morton]

On Mon, 26 Feb 2018 11:54:30 +0200 Nikolay Borisov <nborisov@suse.com> wrote:

> We already get the block counts and the calculate the end block at the
> beginning of the function. Let's use the local variables for consistency and
> readability. No functional changes
> 

Fair enough.

> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -1200,7 +1200,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  	}
>  
>  	/* watch out for a 0 len io from a tricksy fs */
> -	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
> +	if (iov_iter_rw(iter) == READ && !count)
>  		return 0;
>  
>  	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
> @@ -1316,8 +1316,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>  
>  	dio->should_dirty = (iter->type == ITER_IOVEC);
>  	sdio.iter = iter;
> -	sdio.final_block_in_request =
> -		(offset + iov_iter_count(iter)) >> blkbits;
> +	sdio.final_block_in_request = end >> blkbits;
>  
>  	/*
>  	 * In case of non-aligned buffers, we may need 2 more

It's always scary to see a local being used in this fashion so far away
from where it was initialized.  However, we can get our warm fuzzy
feelings by doing this:

--- a/fs/direct-io.c~direct-io-minor-cleanups-in-do_blockdev_direct_io-fix
+++ a/fs/direct-io.c
@@ -1178,9 +1178,9 @@ do_blockdev_direct_IO(struct kiocb *iocb
 	unsigned blkbits = i_blkbits;
 	unsigned blocksize_mask = (1 << blkbits) - 1;
 	ssize_t retval = -EINVAL;
-	size_t count = iov_iter_count(iter);
+	const size_t count = iov_iter_count(iter);
 	loff_t offset = iocb->ki_pos;
-	loff_t end = offset + count;
+	const loff_t end = offset + count;
 	struct dio *dio;
 	struct dio_submit sdio = { 0, };
 	struct buffer_head map_bh = { 0, };
_

Re: [PATCH] direct-io: Minor cleanups in do_blockdev_direct_IO

[Nikolay Borisov]

On  3.03.2018 02:24, Andrew Morton wrote:
> On Mon, 26 Feb 2018 11:54:30 +0200 Nikolay Borisov <nborisov@suse.com> wrote:
> 
>> We already get the block counts and the calculate the end block at the
>> beginning of the function. Let's use the local variables for consistency and
>> readability. No functional changes
>>
> 
> Fair enough.
> 
>> --- a/fs/direct-io.c
>> +++ b/fs/direct-io.c
>> @@ -1200,7 +1200,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>>  	}
>>  
>>  	/* watch out for a 0 len io from a tricksy fs */
>> -	if (iov_iter_rw(iter) == READ && !iov_iter_count(iter))
>> +	if (iov_iter_rw(iter) == READ && !count)
>>  		return 0;
>>  
>>  	dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
>> @@ -1316,8 +1316,7 @@ do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
>>  
>>  	dio->should_dirty = (iter->type == ITER_IOVEC);
>>  	sdio.iter = iter;
>> -	sdio.final_block_in_request =
>> -		(offset + iov_iter_count(iter)) >> blkbits;
>> +	sdio.final_block_in_request = end >> blkbits;
>>  
>>  	/*
>>  	 * In case of non-aligned buffers, we may need 2 more
> 
> It's always scary to see a local being used in this fashion so far away
> from where it was initialized.  However, we can get our warm fuzzy
> feelings by doing this:
> 

Good point !

> --- a/fs/direct-io.c~direct-io-minor-cleanups-in-do_blockdev_direct_io-fix
> +++ a/fs/direct-io.c
> @@ -1178,9 +1178,9 @@ do_blockdev_direct_IO(struct kiocb *iocb
>  	unsigned blkbits = i_blkbits;
>  	unsigned blocksize_mask = (1 << blkbits) - 1;
>  	ssize_t retval = -EINVAL;
> -	size_t count = iov_iter_count(iter);
> +	const size_t count = iov_iter_count(iter);
>  	loff_t offset = iocb->ki_pos;
> -	loff_t end = offset + count;
> +	const loff_t end = offset + count;
>  	struct dio *dio;
>  	struct dio_submit sdio = { 0, };
>  	struct buffer_head map_bh = { 0, };
> _

I assume you don't want me to resend but will just fold the changes
yourself?

> 
>