xfs
[Top] [All Lists]

Re: [PATCH 2/6] xfs: use i_mmaplock on read faults

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH 2/6] xfs: use i_mmaplock on read faults
From: Brian Foster <bfoster@xxxxxxxxxx>
Date: Mon, 9 Feb 2015 15:31:21 -0500
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <1423083859-28439-3-git-send-email-david@xxxxxxxxxxxxx>
References: <1423083859-28439-1-git-send-email-david@xxxxxxxxxxxxx> <1423083859-28439-3-git-send-email-david@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.23 (2014-03-12)
On Thu, Feb 05, 2015 at 08:04:15AM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
> 
> Take the i_mmaplock over read page faults. These come through the
> ->fault callout, so we need to wrap the generic implementation
> with the i_mmaplock. While there, add tracepoints for the read
> fault as it passes through XFS.
> 
> This gives us a lock order of mmap_sem -> i_mmaplock -> page_lock
> -> i_lock.
> 
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---

Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>

>  fs/xfs/xfs_file.c  | 28 +++++++++++++++++++++++++++-
>  fs/xfs/xfs_trace.h |  2 ++
>  2 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 712d312..6cc1b7d 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -1369,6 +1369,32 @@ xfs_file_llseek(
>       }
>  }
>  
> +/*
> + * Locking for serialisation of IO during page faults. This results in a lock
> + * ordering of:
> + *
> + * mmap_sem (MM)
> + *   i_mmap_lock (XFS - truncate serialisation)
> + *     page_lock (MM)
> + *       i_lock (XFS - extent map serialisation)
> + */
> +STATIC int
> +xfs_filemap_fault(
> +     struct vm_area_struct   *vma,
> +     struct vm_fault         *vmf)
> +{
> +     struct xfs_inode        *ip = XFS_I(vma->vm_file->f_mapping->host);
> +     int                     error;
> +
> +     trace_xfs_filemap_fault(ip);
> +
> +     xfs_ilock(ip, XFS_MMAPLOCK_SHARED);
> +     error = filemap_fault(vma, vmf);
> +     xfs_iunlock(ip, XFS_MMAPLOCK_SHARED);
> +
> +     return error;
> +}
> +
>  const struct file_operations xfs_file_operations = {
>       .llseek         = xfs_file_llseek,
>       .read           = new_sync_read,
> @@ -1401,7 +1427,7 @@ const struct file_operations xfs_dir_file_operations = {
>  };
>  
>  static const struct vm_operations_struct xfs_file_vm_ops = {
> -     .fault          = filemap_fault,
> +     .fault          = xfs_filemap_fault,
>       .map_pages      = filemap_map_pages,
>       .page_mkwrite   = xfs_vm_page_mkwrite,
>       .remap_pages    = generic_file_remap_pages,
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 51372e3..c496153 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -685,6 +685,8 @@ DEFINE_INODE_EVENT(xfs_inode_set_eofblocks_tag);
>  DEFINE_INODE_EVENT(xfs_inode_clear_eofblocks_tag);
>  DEFINE_INODE_EVENT(xfs_inode_free_eofblocks_invalid);
>  
> +DEFINE_INODE_EVENT(xfs_filemap_fault);
> +
>  DECLARE_EVENT_CLASS(xfs_iref_class,
>       TP_PROTO(struct xfs_inode *ip, unsigned long caller_ip),
>       TP_ARGS(ip, caller_ip),
> -- 
> 2.0.0
> 
> _______________________________________________
> xfs mailing list
> xfs@xxxxxxxxxxx
> http://oss.sgi.com/mailman/listinfo/xfs

<Prev in Thread] Current Thread [Next in Thread>