Re: [PATCH 1/3] direct-io: always call ->end_io if non-NULL

Darrick J. Wong
2016-02-03T00:05:25Z

On Tue, Feb 02, 2016 at 09:17:35PM +0100, Christoph Hellwig wrote:
> See http://www.infradead.org/rpr.html

Ick. ^^^

> This way we can pass back errors to the file system, and allow for
> cleanup required for all direct I/O invocations.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> fs/dax.c | 2 +-
> fs/direct-io.c | 4 ++--
> fs/ext4/inode.c | 3 +++
> fs/ocfs2/aops.c | 3 +++
> fs/xfs/xfs_aops.c | 3 +++
> 5 files changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 4fd6b0c..e47d1ba 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -267,7 +267,7 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
> if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ)
> inode_unlock(inode);
>
> - if ((retval > 0) && end_io)
> + if (end_io)
> end_io(iocb, pos, retval, bh.b_private);
>
> if (!(flags & DIO_SKIP_DIO_COUNT))
> diff --git a/fs/direct-io.c b/fs/direct-io.c
> index 1b2f7ff..ead7ac1 100644
> --- a/fs/direct-io.c
> +++ b/fs/direct-io.c
> @@ -253,8 +253,8 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret,
> if (ret == 0)
> ret = transferred;
>
> - if (dio->end_io && dio->result)
> - dio->end_io(dio->iocb, offset, transferred, dio->private);
> + if (dio->end_io)
> + dio->end_io(dio->iocb, offset, ret, dio->private);

Could we make end_io return an int so that errors during completion can be
stuffed into ret to be picked up by whatever's calling directio? Something
like this:

if (dio->end_io) {
int ret2;

ret2 = dio->end_io(dio->iocb, offset, ret, dio->private);
if (ret2 && !ret)
ret = ret2;
}

That way I can capture IO errors during the CoW remapping step and pass them to
userland either via dio_complete()'s return value or through ki_complete.

(If ret itself is an error code then obviously we don't bother with the
post-CoW remap.)

--D

>
> if (!(dio->flags & DIO_SKIP_DIO_COUNT))
> inode_dio_end(dio->inode);
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 83bc8bf..d04555b 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3166,6 +3166,9 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
> {
> ext4_io_end_t *io_end = iocb->private;
>
> + if (size <= 0)
> + return;
> +
> /* if not async direct IO just return */
> if (!io_end)
> return;
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index 794fd15..1eeb804 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -628,6 +628,9 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
> struct inode *inode = file_inode(iocb->ki_filp);
> int level;
>
> + if (bytes <= 0)
> + return;
> +
> /* this io's submitter should not have unlocked this before we could */
> BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
>
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 379c089..c318e9f 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -1655,6 +1655,9 @@ xfs_end_io_direct_write(
> struct inode *inode = file_inode(iocb->ki_filp);
> struct xfs_ioend *ioend = private;
>
> + if (size <= 0)
> + return;
> +
> trace_xfs_gbmap_direct_endio(XFS_I(inode), offset, size,
> ioend ? ioend->io_type : 0, NULL);
>
> --
> 2.1.4
>
> --
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