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Re: [PATCH 1/6] xfs: preallocation transactions do not need to be synchr

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 1/6] xfs: preallocation transactions do not need to be synchronous
From: Alex Elder <aelder@xxxxxxx>
Date: Fri, 25 Mar 2011 16:00:36 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <1300860870-15471-2-git-send-email-david@xxxxxxxxxxxxx>
References: <1300860870-15471-1-git-send-email-david@xxxxxxxxxxxxx> <1300860870-15471-2-git-send-email-david@xxxxxxxxxxxxx>
Reply-to: aelder@xxxxxxx
On Wed, 2011-03-23 at 17:14 +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Preallocation and hole punch transactions are currently synchronous
> and this is causing performance problems in some cases. The
> transactions don't need to be synchronous as we don't need to
> guarantee the preallocation is persistent on disk until a
> fdatasync, fsync, sync operation occurs. If the file is opened
> O_SYNC or O_DATASYNC, only then should the transaction be issued
> synchronously.

There's a minor (but important) bug in this.  Other than that
this looks good.

Reviewed-by: Alex Elder <aelder@xxxxxxx>

> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> ---
>  fs/xfs/linux-2.6/xfs_file.c  |    4 ++++
>  fs/xfs/linux-2.6/xfs_ioctl.c |    4 ++++
>  fs/xfs/xfs_vnodeops.c        |    3 ++-
>  fs/xfs/xfs_vnodeops.h        |    1 +
>  4 files changed, 11 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
> index ae59865..baa2cb3 100644
> --- a/fs/xfs/linux-2.6/xfs_file.c
> +++ b/fs/xfs/linux-2.6/xfs_file.c
> @@ -896,6 +896,7 @@ xfs_file_fallocate(
>       xfs_flock64_t   bf;
>       xfs_inode_t     *ip = XFS_I(inode);
>       int             cmd = XFS_IOC_RESVSP;
> +     int             attr_flags = XFS_ATTR_NOLOCK;
>  
>       if (mode & ~(FALLOC_FL_KEEP_SIZE |
>                    FALLOC_FL_PUNCH_HOLE |
> @@ -922,6 +923,9 @@ xfs_file_fallocate(
>                       goto out_unlock;
>       }
>  
> +     if (file->f_flags & O_DSYNC)
> +             attr_flags |= XFS_ATTR_SYNC;
> +
>       error = -xfs_change_file_space(ip, cmd, &bf, 0, XFS_ATTR_NOLOCK);

You need to pass attr_flags as the last argument here.

>       if (error)
>               goto out_unlock;

. . .

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