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

Alex Elder
2011-03-25T20:57:32Z

On Wed, 2011-03-23 at 17:14 +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> 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@sgi.com>

> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> ---
> 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;

. . .