Re: [PATCH 4/9] xfs: honor the O_SYNC flag for aysnchronous direct I/O requests

Jeff Moyer
2012-11-20T19:43:08Z

Dave Chinner <david@fromorbit.com> writes:

> And requeuing work from one workqueue to the next is something that
> we can avoid. We know at IO submission time (i.e.
> xfs_vm_direct_io)) whether an fsync completion is going to be needed
> during Io completion. The ioend->io_needs_fsync flag can be set
> then, and the first pass through xfs_finish_ioend() can queue it to
> the correct workqueue. i.e. it only needs to be queued if it's not
> already an unwritten or append ioend and it needs an fsync.
>
> As it is, all the data completion workqueues run the same completion
> function so all you need to do is handle the fsync case at the end
> of the existing processing - it's not an else case. i.e the end of
> xfs_end_io() becomes:
>
> if (ioend->io_needs_fsync) {
> error = xfs_ioend_fsync(ioend);
> if (error)
> ioend->io_error = -error;
> goto done;
> }
> done:
> xfs_destroy_ioend(ioend);

Works for me, that makes things simpler.

> As it is, this code is going to change before these changes go in -
> there's a nasty regression in the DIO code that I found this
> afternoon that requires reworking this IO completion logic to
> avoid. The patch will appear on the list soon....

I'm not on the xfs list, so if you haven't already sent it, mind Cc-ing
me?

>> --- a/fs/xfs/xfs_mount.h
>> +++ b/fs/xfs/xfs_mount.h
>> @@ -209,6 +209,7 @@ typedef struct xfs_mount {
>> struct workqueue_struct *m_data_workqueue;
>> struct workqueue_struct *m_unwritten_workqueue;
>> struct workqueue_struct *m_cil_workqueue;
>> + struct workqueue_struct *m_aio_blkdev_flush_wq;
>
> struct workqueue_struct *m_aio_fsync_wq;

For the record, m_aio_blkdev_flush_wq is the name you chose previously.
;-)

Thanks for the review!

Cheers,
Jeff