xfs
[Top] [All Lists]

Re: [PATCH 1/5] [XFS] Use xfs_sync_inodes() for device flushing

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 1/5] [XFS] Use xfs_sync_inodes() for device flushing
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 16 Mar 2009 21:45:37 +1100
Cc: xfs@xxxxxxxxxxx, mpatocka@xxxxxxxxxx
In-reply-to: <20090316090847.GA2636@xxxxxxxxxxxxx>
Mail-followup-to: Christoph Hellwig <hch@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx, mpatocka@xxxxxxxxxx
References: <1237116707-25793-1-git-send-email-david@xxxxxxxxxxxxx> <1237116707-25793-2-git-send-email-david@xxxxxxxxxxxxx> <20090316090847.GA2636@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.18 (2008-05-17)
On Mon, Mar 16, 2009 at 05:08:47AM -0400, Christoph Hellwig wrote:
> On Sun, Mar 15, 2009 at 10:31:43PM +1100, Dave Chinner wrote:
> > index 5aeb777..08be36d 100644
> > --- a/fs/xfs/linux-2.6/xfs_fs_subr.c
> > +++ b/fs/xfs/linux-2.6/xfs_fs_subr.c
> > @@ -74,14 +74,14 @@ xfs_flush_pages(
> >  
> >     if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
> >             xfs_iflags_clear(ip, XFS_ITRUNCATED);
> > -           ret = filemap_fdatawrite(mapping);
> > -           if (flags & XFS_B_ASYNC)
> > -                   return -ret;
> > -           ret2 = filemap_fdatawait(mapping);
> > -           if (!ret)
> > -                   ret = ret2;
> > +           ret = -filemap_fdatawrite(mapping);
> >     }
> > -   return -ret;
> > +   if (flags & XFS_B_ASYNC)
> > +           return ret;
> > +   ret2 = xfs_wait_on_pages(ip, first, last);
> > +   if (!ret)
> > +           ret = ret2;
> > +   return ret;
> >  }
> 
> How does this belong into this patch series?

So xfs_flush_pages waits on writeback pages which aren't caught by
mapping_tagged(mapping, PAGECACHE_TAG_DIRTY). If we are waiting for
a flush to complete, we should be waiting for all pages under IO to
complete regardless of whether there are dirty pages or not. That
matters if we are doing 2 passes to flush everything and then wait;
the wait won't see dirty mappings, but there might still be pages
under IO....

> Also I think the sync code should just use filemap_fdatawait and
> filemap_fdatawait directly.  It's at a high enough level that we don't
> need all these obsfucations.

OK. I'll rework it so that:

> > +           if (flags & SYNC_DELWRI) {
> > +                   if (VN_DIRTY(inode)) {
> > +                           if (flags & SYNC_TRYLOCK) {
> > +                                   if (xfs_ilock_nowait(ip, 
> > XFS_IOLOCK_SHARED))
> > +                                           lock_flags |= XFS_IOLOCK_SHARED;
> > +                           } else {
> > +                                   xfs_ilock(ip, XFS_IOLOCK_SHARED);
> > +                                   lock_flags |= XFS_IOLOCK_SHARED;
> > +                           }
> 
> > +                           if (lock_flags & XFS_IOLOCK_SHARED) {
> 
> Too long line and pretty ugly use of the lock_flags variable, but given
> that it gets sorted out in the sync series I think we can leave it that way.

This gets done early and the later patches become simpler.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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