[PATCH] xfs: remove XFS_HSIZE

[PATCH] xfs: remove XFS_HSIZE

[Christoph Hellwig]

XFS_HSIZE is an extremly confusing way to calculate the size of handle_t.
Given that handle_t always only had two sizes, and one of them isn't
even covered by XFS_HSIZE to start with just remove the macro and use
a constant sizeof expression.

Note that XFS_HSIZE isn't used in xfsprogs, xfsdump or xfstests either.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_fs.h | 4 ----
 fs/xfs/xfs_ioctl.c     | 3 +--
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index 095bdf049a3f..a9aa13e66046 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -446,10 +446,6 @@ typedef struct xfs_handle {
 } xfs_handle_t;
 #define ha_fsid ha_u._ha_fsid
 
-#define XFS_HSIZE(handle)	(((char *) &(handle).ha_fid.fid_pad	 \
-				 - (char *) &(handle))			  \
-				 + (handle).ha_fid.fid_len)
-
 /*
  * Structure passed to XFS_IOC_SWAPEXT
  */
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 6190697603c9..f6af76975bc8 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -120,8 +120,7 @@ xfs_find_handle(
 		handle.ha_fid.fid_pad = 0;
 		handle.ha_fid.fid_gen = inode->i_generation;
 		handle.ha_fid.fid_ino = ip->i_ino;
-
-		hsize = XFS_HSIZE(handle);
+		hsize = sizeof(xfs_handle_t);
 	}
 
 	error = -EFAULT;
-- 
2.11.0

Re: [PATCH] xfs: remove XFS_HSIZE

[Darrick J. Wong]

On Tue, May 09, 2017 at 11:00:18AM +0200, Christoph Hellwig wrote:
> XFS_HSIZE is an extremly confusing way to calculate the size of handle_t.
> Given that handle_t always only had two sizes, and one of them isn't
> even covered by XFS_HSIZE to start with just remove the macro and use
> a constant sizeof expression.
> 
> Note that XFS_HSIZE isn't used in xfsprogs, xfsdump or xfstests either.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

> ---
>  fs/xfs/libxfs/xfs_fs.h | 4 ----
>  fs/xfs/xfs_ioctl.c     | 3 +--
>  2 files changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> index 095bdf049a3f..a9aa13e66046 100644
> --- a/fs/xfs/libxfs/xfs_fs.h
> +++ b/fs/xfs/libxfs/xfs_fs.h
> @@ -446,10 +446,6 @@ typedef struct xfs_handle {
>  } xfs_handle_t;
>  #define ha_fsid ha_u._ha_fsid
>  
> -#define XFS_HSIZE(handle)	(((char *) &(handle).ha_fid.fid_pad	 \
> -				 - (char *) &(handle))			  \
> -				 + (handle).ha_fid.fid_len)
> -
>  /*
>   * Structure passed to XFS_IOC_SWAPEXT
>   */
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 6190697603c9..f6af76975bc8 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -120,8 +120,7 @@ xfs_find_handle(
>  		handle.ha_fid.fid_pad = 0;
>  		handle.ha_fid.fid_gen = inode->i_generation;
>  		handle.ha_fid.fid_ino = ip->i_ino;
> -
> -		hsize = XFS_HSIZE(handle);
> +		hsize = sizeof(xfs_handle_t);
>  	}
>  
>  	error = -EFAULT;
> -- 
> 2.11.0
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] xfs: remove XFS_HSIZE

[Darrick J. Wong]

On Tue, May 09, 2017 at 08:40:00AM -0700, Darrick J. Wong wrote:
> On Tue, May 09, 2017 at 11:00:18AM +0200, Christoph Hellwig wrote:
> > XFS_HSIZE is an extremly confusing way to calculate the size of handle_t.
> > Given that handle_t always only had two sizes, and one of them isn't
> > even covered by XFS_HSIZE to start with just remove the macro and use
> > a constant sizeof expression.
> > 
> > Note that XFS_HSIZE isn't used in xfsprogs, xfsdump or xfstests either.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

By the way, do you want me to try to slip this cleanup into 4.12, or
should it wait for 4.13?

--D

> 
> > ---
> >  fs/xfs/libxfs/xfs_fs.h | 4 ----
> >  fs/xfs/xfs_ioctl.c     | 3 +--
> >  2 files changed, 1 insertion(+), 6 deletions(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> > index 095bdf049a3f..a9aa13e66046 100644
> > --- a/fs/xfs/libxfs/xfs_fs.h
> > +++ b/fs/xfs/libxfs/xfs_fs.h
> > @@ -446,10 +446,6 @@ typedef struct xfs_handle {
> >  } xfs_handle_t;
> >  #define ha_fsid ha_u._ha_fsid
> >  
> > -#define XFS_HSIZE(handle)	(((char *) &(handle).ha_fid.fid_pad	 \
> > -				 - (char *) &(handle))			  \
> > -				 + (handle).ha_fid.fid_len)
> > -
> >  /*
> >   * Structure passed to XFS_IOC_SWAPEXT
> >   */
> > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > index 6190697603c9..f6af76975bc8 100644
> > --- a/fs/xfs/xfs_ioctl.c
> > +++ b/fs/xfs/xfs_ioctl.c
> > @@ -120,8 +120,7 @@ xfs_find_handle(
> >  		handle.ha_fid.fid_pad = 0;
> >  		handle.ha_fid.fid_gen = inode->i_generation;
> >  		handle.ha_fid.fid_ino = ip->i_ino;
> > -
> > -		hsize = XFS_HSIZE(handle);
> > +		hsize = sizeof(xfs_handle_t);
> >  	}
> >  
> >  	error = -EFAULT;
> > -- 
> > 2.11.0
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH] xfs: remove XFS_HSIZE

[Christoph Hellwig]

No need to expedite a simple cleanup.

Re: [PATCH] xfs: remove XFS_HSIZE

[Eric Sandeen]

On 5/9/17 4:00 AM, Christoph Hellwig wrote:
> XFS_HSIZE is an extremly confusing way to calculate the size of handle_t.
> Given that handle_t always only had two sizes, and one of them isn't
> even covered by XFS_HSIZE to start with just remove the macro and use
> a constant sizeof expression.
> 
> Note that XFS_HSIZE isn't used in xfsprogs, xfsdump or xfstests either.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Ok, so with this assignment a few lines before:

handle.ha_fid.fid_len = sizeof(xfs_fid_t) - sizeof(handle.ha_fid.fid_len);

(so: fid_len == size of (fid_pad + fid_gen + fid_ino))

and:

(((char *) &(handle).ha_fid.fid_pad - (char *) &(handle)) + (handle).ha_fid.fid_len)
|< --        size of ha_u + sizeof fid_len         -->  |  |<-sizeof(pad+gen+ino)->|

this does indeed seem to come out to sizeof(xfs_handle_t).

Looks winning, minor comment below

> ---
>  fs/xfs/libxfs/xfs_fs.h | 4 ----
>  fs/xfs/xfs_ioctl.c     | 3 +--
>  2 files changed, 1 insertion(+), 6 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
> index 095bdf049a3f..a9aa13e66046 100644
> --- a/fs/xfs/libxfs/xfs_fs.h
> +++ b/fs/xfs/libxfs/xfs_fs.h
> @@ -446,10 +446,6 @@ typedef struct xfs_handle {
>  } xfs_handle_t;
>  #define ha_fsid ha_u._ha_fsid
>  
> -#define XFS_HSIZE(handle)	(((char *) &(handle).ha_fid.fid_pad	 \
> -				 - (char *) &(handle))			  \
> -				 + (handle).ha_fid.fid_len)
> -
>  /*
>   * Structure passed to XFS_IOC_SWAPEXT
>   */
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 6190697603c9..f6af76975bc8 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -120,8 +120,7 @@ xfs_find_handle(
>  		handle.ha_fid.fid_pad = 0;
>  		handle.ha_fid.fid_gen = inode->i_generation;
>  		handle.ha_fid.fid_ino = ip->i_ino;
> -
> -		hsize = XFS_HSIZE(handle);
> +		hsize = sizeof(xfs_handle_t);

at this point, no need to have the hsize assignment in if { } as well as else { }, right?

-Eric

>  	}
>  
>  	error = -EFAULT;
> 

Re: [PATCH] xfs: remove XFS_HSIZE

[Christoph Hellwig]

On Tue, May 09, 2017 at 10:40:31AM -0500, Eric Sandeen wrote:
> > -
> > -		hsize = XFS_HSIZE(handle);
> > +		hsize = sizeof(xfs_handle_t);
> 
> at this point, no need to have the hsize assignment in if { } as well as else { }, right?
> 

In the other branch hsize is smaller, it only covers the fsid.

Re: [PATCH] xfs: remove XFS_HSIZE

[Eric Sandeen]

> On May 9, 2017, at 4:18 PM, Christoph Hellwig <hch@lst.de> wrote:
> 
> On Tue, May 09, 2017 at 10:40:31AM -0500, Eric Sandeen wrote:
>>> -
>>> -        hsize = XFS_HSIZE(handle);
>>> +        hsize = sizeof(xfs_handle_t);
>> 
>> at this point, no need to have the hsize assignment in if { } as well as else { }, right?
>> 
> 
> In the other branch hsize is smaller, it only covers the fsid.

Ugh I misread, sorry.

Reviewed-by: Eric Sandeen <sandeen@sandeen.net>
>