On Fri, 2024-12-13 at 14:18 -0800, Joanne Koong wrote:
> Add support for folios larger than one page size for writethrough
> writes.
>
> Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
> ---
> fs/fuse/file.c | 19 ++++++++++++-------
> 1 file changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> index c041bb328203..84e39426862a 100644
> --- a/fs/fuse/file.c
> +++ b/fs/fuse/file.c
> @@ -1135,6 +1135,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
> struct iov_iter *ii, loff_t pos,
> unsigned int max_pages)
> {
> + size_t max_folio_size = mapping_max_folio_size(mapping);
> struct fuse_args_pages *ap = &ia->ap;
> struct fuse_conn *fc = get_fuse_conn(mapping->host);
> unsigned offset = pos & (PAGE_SIZE - 1);
> @@ -1146,17 +1147,17 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
> num = min(num, max_pages << PAGE_SHIFT);
>
> ap->args.in_pages = true;
> - ap->descs[0].offset = offset;
>
> while (num) {
> size_t tmp;
> struct folio *folio;
> pgoff_t index = pos >> PAGE_SHIFT;
> - unsigned int bytes = min(PAGE_SIZE - offset, num);
> + unsigned int bytes;
> + unsigned int folio_offset;
>
> again:
> err = -EFAULT;
> - if (fault_in_iov_iter_readable(ii, bytes))
> + if (fault_in_iov_iter_readable(ii, max_folio_size) == max_folio_size)
> break;
>
> folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
> @@ -1169,7 +1170,10 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
> if (mapping_writably_mapped(mapping))
> flush_dcache_folio(folio);
>
> - tmp = copy_folio_from_iter_atomic(folio, offset, bytes, ii);
> + folio_offset = ((index - folio->index) << PAGE_SHIFT) + offset;
> + bytes = min(folio_size(folio) - folio_offset, num);
> +
> + tmp = copy_folio_from_iter_atomic(folio, folio_offset, bytes, ii);
Just to save someone else going down the same rabbit hole:
copy_folio_from_iter_atomic() is defined as:
static inline size_t copy_folio_from_iter_atomic(struct folio *folio,
size_t offset, size_t bytes, struct iov_iter *i)
{
return copy_page_from_iter_atomic(&folio->page, offset, bytes, i);
}
...which _looks_ sort of like it's not fully baked yet and can't handle
a large folio, but it turns out that copy_page_from_iter_atomic() can
handle compound pages, so I think this is actually OK. Whew!
> flush_dcache_folio(folio);
>
> if (!tmp) {
> @@ -1180,6 +1184,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
>
> err = 0;
> ap->folios[ap->num_folios] = folio;
> + ap->descs[ap->num_folios].offset = folio_offset;
> ap->descs[ap->num_folios].length = tmp;
> ap->num_folios++;
>
> @@ -1187,11 +1192,11 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
> pos += tmp;
> num -= tmp;
> offset += tmp;
> - if (offset == PAGE_SIZE)
> + if (offset == folio_size(folio))
> offset = 0;
>
> - /* If we copied full page, mark it uptodate */
> - if (tmp == PAGE_SIZE)
> + /* If we copied full folio, mark it uptodate */
> + if (tmp == folio_size(folio))
> folio_mark_uptodate(folio);
>
> if (folio_test_uptodate(folio)) {
--
Jeff Layton <jlayton@xxxxxxxxxx>
