On Wed 18-04-18 14:08:26, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Currently iomap_dio_rw() only handles (data)sync write completions
> for AIO. This means we can't optimised non-AIO IO to minimise device
> flushes as we can't tell the caller whether a flush is required or
> not.
>
> To solve this problem and enable further optimisations, make
> iomap_dio_rw responsible for data sync behaviour for all IO, not
> just AIO.
>
> In doing so, the sync operation is now accounted as part of the DIO
> IO by inode_dio_end(), hence post-IO data stability updates will no
> long race against operations that serialise via inode_dio_wait()
> such as truncate or hole punch.
>
> Signed-Off-By: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Looks good to me. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/iomap.c | 22 +++++++++++++++-------
> fs/xfs/xfs_file.c | 5 -----
> 2 files changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index afd163586aa0..1f59c2d9ade6 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -685,6 +685,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_data);
> * Private flags for iomap_dio, must not overlap with the public ones in
> * iomap.h:
> */
> +#define IOMAP_DIO_NEED_SYNC (1 << 29)
> #define IOMAP_DIO_WRITE (1 << 30)
> #define IOMAP_DIO_DIRTY (1 << 31)
>
> @@ -759,6 +760,13 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
> dio_warn_stale_pagecache(iocb->ki_filp);
> }
>
> + /*
> + * If this is a DSYNC write, make sure we push it to stable storage now
> + * that we've written data.
> + */
> + if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
> + ret = generic_write_sync(iocb, ret);
> +
> inode_dio_end(file_inode(iocb->ki_filp));
> kfree(dio);
>
> @@ -768,14 +776,8 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
> static void iomap_dio_complete_work(struct work_struct *work)
> {
> struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
> - struct kiocb *iocb = dio->iocb;
> - bool is_write = (dio->flags & IOMAP_DIO_WRITE);
> - ssize_t ret;
>
> - ret = iomap_dio_complete(dio);
> - if (is_write && ret > 0)
> - ret = generic_write_sync(iocb, ret);
> - iocb->ki_complete(iocb, ret, 0);
> + dio->iocb->ki_complete(dio->iocb, iomap_dio_complete(dio), 0);
> }
>
> /*
> @@ -961,6 +963,10 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
> return copied;
> }
>
> +/*
> + * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
> + * is being issued as AIO or not.
> + */
> ssize_t
> iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
> @@ -1006,6 +1012,8 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> dio->flags |= IOMAP_DIO_DIRTY;
> } else {
> dio->flags |= IOMAP_DIO_WRITE;
> + if (iocb->ki_flags & IOCB_DSYNC)
> + dio->flags |= IOMAP_DIO_NEED_SYNC;
> flags |= IOMAP_WRITE;
> }
>
> diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> index 6f15027661b6..0c4b8313d544 100644
> --- a/fs/xfs/xfs_file.c
> +++ b/fs/xfs/xfs_file.c
> @@ -570,11 +570,6 @@ xfs_file_dio_aio_write(
> * complete fully or fail.
> */
> ASSERT(ret < 0 || ret == count);
> -
> - if (ret > 0) {
> - /* Handle various SYNC-type writes */
> - ret = generic_write_sync(iocb, ret);
> - }
> return ret;
> }
>
> --
> 2.16.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
