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Date: Thu, 15 Jul 2021 14:33:05 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v14 100/138] iomap: Convert readahead and readpage to use
a folio
On Thu, Jul 15, 2021 at 04:36:26AM +0100, Matthew Wilcox (Oracle) wrote:
> Handle folios of arbitrary size instead of working in PAGE_SIZE units.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
--D
> ---
> fs/iomap/buffered-io.c | 61 +++++++++++++++++++++---------------------
> 1 file changed, 30 insertions(+), 31 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 4732298f74e1..7c702d6c2f64 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -188,8 +188,8 @@ static void iomap_read_end_io(struct bio *bio)
> }
>
> struct iomap_readpage_ctx {
> - struct page *cur_page;
> - bool cur_page_in_bio;
> + struct folio *cur_folio;
> + bool cur_folio_in_bio;
> struct bio *bio;
> struct readahead_control *rac;
> };
> @@ -227,8 +227,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_readpage_ctx *ctx = data;
> - struct page *page = ctx->cur_page;
> - struct folio *folio = page_folio(page);
> + struct folio *folio = ctx->cur_folio;
> struct iomap_page *iop = iomap_page_create(inode, folio);
> bool same_page = false, is_contig = false;
> loff_t orig_pos = pos;
> @@ -237,7 +236,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>
> if (iomap->type == IOMAP_INLINE) {
> WARN_ON_ONCE(pos);
> - iomap_read_inline_data(inode, page, iomap);
> + iomap_read_inline_data(inode, &folio->page, iomap);
> return PAGE_SIZE;
> }
>
> @@ -252,7 +251,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> goto done;
> }
>
> - ctx->cur_page_in_bio = true;
> + ctx->cur_folio_in_bio = true;
> if (iop)
> atomic_add(plen, &iop->read_bytes_pending);
>
> @@ -266,7 +265,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> }
>
> if (!is_contig || bio_full(ctx->bio, plen)) {
> - gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
> + gfp_t gfp = mapping_gfp_constraint(folio->mapping, GFP_KERNEL);
> gfp_t orig_gfp = gfp;
> unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
>
> @@ -305,30 +304,31 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
> int
> iomap_readpage(struct page *page, const struct iomap_ops *ops)
> {
> - struct iomap_readpage_ctx ctx = { .cur_page = page };
> - struct inode *inode = page->mapping->host;
> - unsigned poff;
> + struct folio *folio = page_folio(page);
> + struct iomap_readpage_ctx ctx = { .cur_folio = folio };
> + struct inode *inode = folio->mapping->host;
> + size_t poff;
> loff_t ret;
> + size_t len = folio_size(folio);
>
> - trace_iomap_readpage(page->mapping->host, 1);
> + trace_iomap_readpage(inode, 1);
>
> - for (poff = 0; poff < PAGE_SIZE; poff += ret) {
> - ret = iomap_apply(inode, page_offset(page) + poff,
> - PAGE_SIZE - poff, 0, ops, &ctx,
> - iomap_readpage_actor);
> + for (poff = 0; poff < len; poff += ret) {
> + ret = iomap_apply(inode, folio_pos(folio) + poff, len - poff,
> + 0, ops, &ctx, iomap_readpage_actor);
> if (ret <= 0) {
> WARN_ON_ONCE(ret == 0);
> - SetPageError(page);
> + folio_set_error(folio);
> break;
> }
> }
>
> if (ctx.bio) {
> submit_bio(ctx.bio);
> - WARN_ON_ONCE(!ctx.cur_page_in_bio);
> + WARN_ON_ONCE(!ctx.cur_folio_in_bio);
> } else {
> - WARN_ON_ONCE(ctx.cur_page_in_bio);
> - unlock_page(page);
> + WARN_ON_ONCE(ctx.cur_folio_in_bio);
> + folio_unlock(folio);
> }
>
> /*
> @@ -348,15 +348,15 @@ iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length,
> loff_t done, ret;
>
> for (done = 0; done < length; done += ret) {
> - if (ctx->cur_page && offset_in_page(pos + done) == 0) {
> - if (!ctx->cur_page_in_bio)
> - unlock_page(ctx->cur_page);
> - put_page(ctx->cur_page);
> - ctx->cur_page = NULL;
> + if (ctx->cur_folio &&
> + offset_in_folio(ctx->cur_folio, pos + done) == 0) {
> + if (!ctx->cur_folio_in_bio)
> + folio_unlock(ctx->cur_folio);
> + ctx->cur_folio = NULL;
> }
> - if (!ctx->cur_page) {
> - ctx->cur_page = readahead_page(ctx->rac);
> - ctx->cur_page_in_bio = false;
> + if (!ctx->cur_folio) {
> + ctx->cur_folio = readahead_folio(ctx->rac);
> + ctx->cur_folio_in_bio = false;
> }
> ret = iomap_readpage_actor(inode, pos + done, length - done,
> ctx, iomap, srcmap);
> @@ -404,10 +404,9 @@ void iomap_readahead(struct readahead_control *rac, const struct iomap_ops *ops)
>
> if (ctx.bio)
> submit_bio(ctx.bio);
> - if (ctx.cur_page) {
> - if (!ctx.cur_page_in_bio)
> - unlock_page(ctx.cur_page);
> - put_page(ctx.cur_page);
> + if (ctx.cur_folio) {
> + if (!ctx.cur_folio_in_bio)
> + folio_unlock(ctx.cur_folio);
> }
> }
> EXPORT_SYMBOL_GPL(iomap_readahead);
> --
> 2.30.2
>
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