On Mon, Jul 19, 2021 at 12:35:10PM +0200, Christoph Hellwig wrote:
> Rewrite iomap_seek_hole to use iomap_iter.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/iomap/seek.c | 46 +++++++++++++++++++++++-----------------------
> 1 file changed, 23 insertions(+), 23 deletions(-)
>
> diff --git a/fs/iomap/seek.c b/fs/iomap/seek.c
> index ce6fb810854fec..7d6ed9af925e96 100644
> --- a/fs/iomap/seek.c
> +++ b/fs/iomap/seek.c
> @@ -1,7 +1,7 @@
> // SPDX-License-Identifier: GPL-2.0
> /*
> * Copyright (C) 2017 Red Hat, Inc.
> - * Copyright (c) 2018 Christoph Hellwig.
> + * Copyright (c) 2018-2021 Christoph Hellwig.
> */
> #include <linux/module.h>
> #include <linux/compiler.h>
> @@ -10,21 +10,19 @@
> #include <linux/pagemap.h>
> #include <linux/pagevec.h>
>
> -static loff_t
> -iomap_seek_hole_actor(struct inode *inode, loff_t start, loff_t length,
> - void *data, struct iomap *iomap, struct iomap *srcmap)
> +static loff_t iomap_seek_hole_iter(const struct iomap_iter *iter, loff_t *pos)
/me wonders if @pos should be named hole_pos (here and in the caller) to
make it a little easier to read...
> {
> - loff_t offset = start;
> + loff_t length = iomap_length(iter);
>
> - switch (iomap->type) {
> + switch (iter->iomap.type) {
> case IOMAP_UNWRITTEN:
> - offset = mapping_seek_hole_data(inode->i_mapping, start,
> - start + length, SEEK_HOLE);
> - if (offset == start + length)
> + *pos = mapping_seek_hole_data(iter->inode->i_mapping,
> + iter->pos, iter->pos + length, SEEK_HOLE);
> + if (*pos == iter->pos + length)
> return length;
> - fallthrough;
> + return 0;
> case IOMAP_HOLE:
> - *(loff_t *)data = offset;
> + *pos = iter->pos;
> return 0;
> default:
> return length;
> @@ -35,23 +33,25 @@ loff_t
> iomap_seek_hole(struct inode *inode, loff_t offset, const struct iomap_ops *ops)
> {
> loff_t size = i_size_read(inode);
> - loff_t ret;
> + struct iomap_iter iter = {
> + .inode = inode,
> + .pos = offset,
> + .flags = IOMAP_REPORT,
> + };
> + int ret;
>
> /* Nothing to be found before or beyond the end of the file. */
> if (offset < 0 || offset >= size)
> return -ENXIO;
>
> - while (offset < size) {
> - ret = iomap_apply(inode, offset, size - offset, IOMAP_REPORT,
> - ops, &offset, iomap_seek_hole_actor);
> - if (ret < 0)
> - return ret;
> - if (ret == 0)
> - break;
> - offset += ret;
> - }
> -
> - return offset;
> + iter.len = size - offset;
> + while ((ret = iomap_iter(&iter, ops)) > 0)
> + iter.processed = iomap_seek_hole_iter(&iter, &offset);
> + if (ret < 0)
> + return ret;
> + if (iter.len)
> + return offset;
...because what we're really saying here is that if seek_hole_iter found
a hole (and returned zero, thereby terminating the loop before iter.len
could reach zero), we want to return the position of the hole.
> + return size;
Not sure why we return size here...? Oh, because there's an implicit
hole at EOF, so we return i_size. Uh, does this do the right thing if
->iomap_begin returns posteof mappings? I don't see anything in
iomap_iter_advance that would stop iteration at EOF.
--D
> }
> EXPORT_SYMBOL_GPL(iomap_seek_hole);
>
> --
> 2.30.2
>
