Re: [PATCH 5/6] writeback: try more writeback as long as something was written

Christoph Hellwig
2011-04-21T08:01:16Z

On Thu, Apr 21, 2011 at 05:52:58PM +1000, Dave Chinner wrote:
> > We shouldn't have I_DIRTY_PAGES set for that case, as we only redirty
> > metadata. But we're actually doing a xfs_mark_inode_dirty, which
> > dirties all of I_DIRTY, which includes I_DIRTY_PAGES. I guess it
> > should change to
> >
> > __mark_inode_dirty(inode, I_DIRTY_SYNC | I_DIRTY_DATASYNC);
>
> Probably should. Using xfs_mark_inode_dirty_sync() might be the best
> thing to do.

That's not correct either - we need to set I_DIRTY_DATASYNC so that it
gets caught by fsync and not just fdatasync.

But thinking about it I'm actually not sure we need it at all. We already
wait for the i_iocount to go to zero both in fsync and ->sync_fs, which will
catch pending I/O completions even without any VFS dirty state. So just
marking the inode dirty (as I_DIRTY_SYNC | I_DIRTY_DATASYNC) on I/O
completion should be enough these days.