On Thu, Jan 11, 2018 at 10:15:02PM +0100, Andreas Gruenbacher wrote:
> Add a callback to iomap_file_buffered_write that's called whenever
> writing to a page has completed. This is needed for implementing data
> journaling: in the data journaling case, pages are written into the
> journal before being written back to their proper on-disk locations.
>
> (So far, the only user of iomap_file_buffered_write is xfs, which
> doesn't do data journaling.)
>
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> ---
> fs/iomap.c | 21 +++++++++++++++++++--
> include/linux/iomap.h | 9 +++++++++
> 2 files changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/fs/iomap.c b/fs/iomap.c
> index 47d29ccffaef..98903be66c35 100644
> --- a/fs/iomap.c
> +++ b/fs/iomap.c
> @@ -149,11 +149,21 @@ iomap_write_end(struct inode *inode, loff_t pos, unsigned len,
> return ret;
> }
>
> +struct iomap_write_data {
> + struct iov_iter *iter;
> + const struct iomap_ops *ops;
> +};
> +
> static loff_t
> iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> struct iomap *iomap)
> {
> - struct iov_iter *i = data;
> + struct iomap_write_data *d = data;
> + struct iov_iter *i = d->iter;
> + void (*iomap_written)(struct inode *inode, struct page *page,
> + unsigned int offset, unsigned int length,
> + unsigned int written) =
> + d->ops->iomap_written;
> long status = 0;
> ssize_t written = 0;
> unsigned int flags = AOP_FLAG_NOFS;
> @@ -198,6 +208,9 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>
> flush_dcache_page(page);
>
> + if (iomap_written)
> + iomap_written(inode, page, offset, bytes, copied);
> +
> status = iomap_write_end(inode, pos, bytes, copied, page);
> if (unlikely(status < 0))
> break;
This looks like it should replace iomap_write_end() as it has
pretty much the same parameters are passed to it.
i.e. it seems to me like a better solution would be to add
->write_begin/->write_end ops to the struct iomap_ops and have
existing implementations set them up as iomap_write_begin()/
iomap_write_end(). Then gfs2 can do it's special little extra bit
and then call iomap_write_end() in the one call...
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
