Re: [PATCH v14 128/138] iomap: Support multi-page folios in invalidatepage

Darrick J. Wong
2021-07-15T22:10:21Z

On Thu, Jul 15, 2021 at 04:36:54AM +0100, Matthew Wilcox (Oracle) wrote:
> If we're punching a hole in a multi-page folio, we need to remove the
> per-page iomap data as the folio is about to be split and each page will
> need its own. This means that writepage can now come across a page with
> no iop allocated, so remove the assertion that there is already one,
> and just create one (with the uptodate bits set) if there isn't one.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Lol, Andreas already did the bottom half of the change for you.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
> fs/iomap/buffered-io.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 48de198c5603..7f78256fc0ba 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -474,13 +474,17 @@ iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
> trace_iomap_invalidatepage(folio->mapping->host, offset, len);
>
> /*
> - * If we are invalidating the entire page, clear the dirty state from it
> - * and release it to avoid unnecessary buildup of the LRU.
> + * If we are invalidating the entire folio, clear the dirty state
> + * from it and release it to avoid unnecessary buildup of the LRU.
> */
> if (offset == 0 && len == folio_size(folio)) {
> WARN_ON_ONCE(folio_test_writeback(folio));
> folio_cancel_dirty(folio);
> iomap_page_release(folio);
> + } else if (folio_multi(folio)) {
> + /* Must release the iop so the page can be split */
> + WARN_ON_ONCE(!folio_test_uptodate(folio) && folio_test_dirty(folio));
> + iomap_page_release(folio);
> }
> }
> EXPORT_SYMBOL_GPL(iomap_invalidatepage);
> @@ -1300,7 +1304,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> struct writeback_control *wbc, struct inode *inode,
> struct folio *folio, loff_t end_pos)
> {
> - struct iomap_page *iop = to_iomap_page(folio);
> + struct iomap_page *iop = iomap_page_create(inode, folio);
> struct iomap_ioend *ioend, *next;
> unsigned len = i_blocksize(inode);
> unsigned nblocks = i_blocks_per_folio(inode, folio);
> @@ -1308,7 +1312,6 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
> int error = 0, count = 0, i;
> LIST_HEAD(submit_list);
>
> - WARN_ON_ONCE(nblocks > 1 && !iop);
> WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
>
> /*
> --
> 2.30.2
>