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Re: [PATCH] xfs: lseek SEEK_DATA/SEEK_HOLE consolidation

To: Jeff Liu <jeff.liu@xxxxxxxxxx>
Subject: Re: [PATCH] xfs: lseek SEEK_DATA/SEEK_HOLE consolidation
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 24 Jun 2013 09:13:20 +1000
Cc: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <51C454DE.2010008@xxxxxxxxxx>
References: <51C454DE.2010008@xxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Fri, Jun 21, 2013 at 09:27:58PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@xxxxxxxxxx>
> 
> Consolidate lseek(2) SEEK_DATA/SEEK_HOLE according to the
> implementation of VFS lseek_execute():
> - if end up with a negative offset, return EINVAL if file
>   is not huge.
> - if end up with an offset larger than s_maxbytes, return
>   EINVAL as well.
> - reset file version to 0 if end up with an offset that is
>   not equal to the current file offset.
> 
> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>
> 
> ---
>  fs/xfs/xfs_file.c |   26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index a5f2042..dc42751 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1270,8 +1270,19 @@ xfs_seek_data(
>       }
>  
>  out:
> -     if (offset != file->f_pos)
> +     if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
> +             error = EINVAL;
> +             goto out_unlock;
> +     }
> +     if (offset > inode->i_sb->s_maxbytes) {
> +             error = EINVAL;
> +             goto out_unlock;
> +     }
> +
> +     if (offset != file->f_pos) {
>               file->f_pos = offset;
> +             file->f_version = 0;
> +     }

Hi Jeff, why are you copy-n-pasting this code from lseek_execute()
rather than making lseek_execute() an exported function and calling
that directly? 

>  
>  out_unlock:
>       xfs_iunlock_map_shared(ip, lock);
> @@ -1372,6 +1383,15 @@ xfs_seek_hole(
>       }
>  
>  out:
> +     if (offset < 0 && !(file->f_mode & FMODE_UNSIGNED_OFFSET)) {
> +             error = EINVAL;
> +             goto out_unlock;
> +     }
> +     if (offset > inode->i_sb->s_maxbytes) {
> +             error = EINVAL;
> +             goto out_unlock;
> +     }

These checks belong after we truncated offset to isize, don't they?
And that would make both of these functions simply require a call to
lseek_execute(), yes?

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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