[PATCH 0/3] fs: aio: more folio conversion

[PATCH 0/3] fs: aio: more folio conversion

[Kefeng Wang]

Convert to use folio throughout aio.

Kefeng Wang (3):
  fs: aio: use a folio in aio_setup_ring()
  fs: aio: use a folio in aio_free_ring()
  fs: aio: convert to ring_folios and internal_folios

 fs/aio.c | 92 +++++++++++++++++++++++++++++---------------------------
 1 file changed, 48 insertions(+), 44 deletions(-)

-- 
2.27.0

[PATCH 1/3] fs: aio: use a folio in aio_setup_ring()

[Kefeng Wang]

Use a folio throughout aio_setup_ring() to remove calls to compound_head().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 fs/aio.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 9cdaa2faa536..d7f6c8705016 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -527,17 +527,20 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 	}
 
 	for (i = 0; i < nr_pages; i++) {
-		struct page *page;
-		page = find_or_create_page(file->f_mapping,
-					   i, GFP_USER | __GFP_ZERO);
-		if (!page)
+		struct folio *folio;
+
+		folio = __filemap_get_folio(file->f_mapping, i,
+					    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
+					    GFP_USER | __GFP_ZERO);
+		if (!folio)
 			break;
-		pr_debug("pid(%d) page[%d]->count=%d\n",
-			 current->pid, i, page_count(page));
-		SetPageUptodate(page);
-		unlock_page(page);
 
-		ctx->ring_pages[i] = page;
+		pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
+			 folio_ref_count(folio));
+		folio_mark_uptodate(folio);
+		folio_unlock(folio);
+
+		ctx->ring_pages[i] = &folio->page;
 	}
 	ctx->nr_pages = i;
 
-- 
2.27.0

Re: [PATCH 1/3] fs: aio: use a folio in aio_setup_ring()

[Kefeng Wang]

On 2024/3/21 16:27, Kefeng Wang wrote:
> Use a folio throughout aio_setup_ring() to remove calls to compound_head().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>   fs/aio.c | 21 ++++++++++++---------
>   1 file changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/aio.c b/fs/aio.c
> index 9cdaa2faa536..d7f6c8705016 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -527,17 +527,20 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
>   	}
>   
>   	for (i = 0; i < nr_pages; i++) {
> -		struct page *page;
> -		page = find_or_create_page(file->f_mapping,
> -					   i, GFP_USER | __GFP_ZERO);
> -		if (!page)
> +		struct folio *folio;
> +
> +		folio = __filemap_get_folio(file->f_mapping, i,
> +					    FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
> +					    GFP_USER | __GFP_ZERO);
> +		if (!folio)
Oh, this should be  if (IS_ERR(folio)), will update.

>   			break;
> -		pr_debug("pid(%d) page[%d]->count=%d\n",
> -			 current->pid, i, page_count(page));
> -		SetPageUptodate(page);
> -		unlock_page(page);
>   
> -		ctx->ring_pages[i] = page;
> +		pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
> +			 folio_ref_count(folio));
> +		folio_mark_uptodate(folio);
> +		folio_unlock(folio);
> +
> +		ctx->ring_pages[i] = &folio->page;
>   	}
>   	ctx->nr_pages = i;
>   

Re: [PATCH 1/3] fs: aio: use a folio in aio_setup_ring()

[Matthew Wilcox]

On Thu, Mar 21, 2024 at 04:27:31PM +0800, Kefeng Wang wrote:
> +		pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
> +			 folio_ref_count(folio));
> +		folio_mark_uptodate(folio);
> +		folio_unlock(folio);

You can use folio_end_read() here.

[PATCH 2/3] fs: aio: use a folio in aio_free_ring()

[Kefeng Wang]

Use a folio throughout aio_free_ring() to remove calls to compound_head().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 fs/aio.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index d7f6c8705016..2c155be67b9a 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -334,14 +334,15 @@ static void aio_free_ring(struct kioctx *ctx)
 	put_aio_ring_file(ctx);
 
 	for (i = 0; i < ctx->nr_pages; i++) {
-		struct page *page;
-		pr_debug("pid(%d) [%d] page->count=%d\n", current->pid, i,
-				page_count(ctx->ring_pages[i]));
-		page = ctx->ring_pages[i];
-		if (!page)
+		struct folio *folio = page_folio(ctx->ring_pages[i]);
+
+		if (!folio)
 			continue;
+
+		pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
+			 folio_ref_count(folio));
 		ctx->ring_pages[i] = NULL;
-		put_page(page);
+		folio_put(folio);
 	}
 
 	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
-- 
2.27.0

[PATCH 3/3] fs: aio: convert to ring_folios and internal_folios

[Kefeng Wang]

Since aio use folios in most functions, convert ring/internal_pages
to ring/internal_folios, let's directly use folio instead of page
throughout aio to remove hidden calls to compound_head(), eg,
flush_dcache_page().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 fs/aio.c | 62 ++++++++++++++++++++++++++++----------------------------
 1 file changed, 31 insertions(+), 31 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 2c155be67b9a..9c15ffbec432 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -122,7 +122,7 @@ struct kioctx {
 	unsigned long		mmap_base;
 	unsigned long		mmap_size;
 
-	struct page		**ring_pages;
+	struct folio		**ring_folios;
 	long			nr_pages;
 
 	struct rcu_work		free_rwork;	/* see free_ioctx() */
@@ -160,7 +160,7 @@ struct kioctx {
 		spinlock_t	completion_lock;
 	} ____cacheline_aligned_in_smp;
 
-	struct page		*internal_pages[AIO_RING_PAGES];
+	struct folio		*internal_folios[AIO_RING_PAGES];
 	struct file		*aio_ring_file;
 
 	unsigned		id;
@@ -334,20 +334,20 @@ static void aio_free_ring(struct kioctx *ctx)
 	put_aio_ring_file(ctx);
 
 	for (i = 0; i < ctx->nr_pages; i++) {
-		struct folio *folio = page_folio(ctx->ring_pages[i]);
+		struct folio *folio = ctx->ring_folios[i];
 
 		if (!folio)
 			continue;
 
 		pr_debug("pid(%d) [%d] folio->count=%d\n", current->pid, i,
 			 folio_ref_count(folio));
-		ctx->ring_pages[i] = NULL;
+		ctx->ring_folios[i] = NULL;
 		folio_put(folio);
 	}
 
-	if (ctx->ring_pages && ctx->ring_pages != ctx->internal_pages) {
-		kfree(ctx->ring_pages);
-		ctx->ring_pages = NULL;
+	if (ctx->ring_folios && ctx->ring_folios != ctx->internal_folios) {
+		kfree(ctx->ring_folios);
+		ctx->ring_folios = NULL;
 	}
 }
 
@@ -442,7 +442,7 @@ static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 	idx = src->index;
 	if (idx < (pgoff_t)ctx->nr_pages) {
 		/* Make sure the old folio hasn't already been changed */
-		if (ctx->ring_pages[idx] != &src->page)
+		if (ctx->ring_folios[idx] != src)
 			rc = -EAGAIN;
 	} else
 		rc = -EINVAL;
@@ -466,8 +466,8 @@ static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 	 */
 	spin_lock_irqsave(&ctx->completion_lock, flags);
 	folio_migrate_copy(dst, src);
-	BUG_ON(ctx->ring_pages[idx] != &src->page);
-	ctx->ring_pages[idx] = &dst->page;
+	BUG_ON(ctx->ring_folios[idx] != src);
+	ctx->ring_folios[idx] = dst;
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
 	/* The old folio is no longer accessible. */
@@ -517,11 +517,11 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 	nr_events = (PAGE_SIZE * nr_pages - sizeof(struct aio_ring))
 			/ sizeof(struct io_event);
 
-	ctx->ring_pages = ctx->internal_pages;
+	ctx->ring_folios = ctx->internal_folios;
 	if (nr_pages > AIO_RING_PAGES) {
-		ctx->ring_pages = kcalloc(nr_pages, sizeof(struct page *),
-					  GFP_KERNEL);
-		if (!ctx->ring_pages) {
+		ctx->ring_folios = kcalloc(nr_pages, sizeof(struct folio *),
+					   GFP_KERNEL);
+		if (!ctx->ring_folios) {
 			put_aio_ring_file(ctx);
 			return -ENOMEM;
 		}
@@ -541,7 +541,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 		folio_mark_uptodate(folio);
 		folio_unlock(folio);
 
-		ctx->ring_pages[i] = &folio->page;
+		ctx->ring_folios[i] = folio;
 	}
 	ctx->nr_pages = i;
 
@@ -574,7 +574,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 	ctx->user_id = ctx->mmap_base;
 	ctx->nr_events = nr_events; /* trusted copy */
 
-	ring = page_address(ctx->ring_pages[0]);
+	ring = folio_address(ctx->ring_folios[0]);
 	ring->nr = nr_events;	/* user copy */
 	ring->id = ~0U;
 	ring->head = ring->tail = 0;
@@ -582,7 +582,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 	ring->compat_features = AIO_RING_COMPAT_FEATURES;
 	ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
 	ring->header_length = sizeof(struct aio_ring);
-	flush_dcache_page(ctx->ring_pages[0]);
+	flush_dcache_folio(ctx->ring_folios[0]);
 
 	return 0;
 }
@@ -693,9 +693,9 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
 
 					/* While kioctx setup is in progress,
 					 * we are protected from page migration
-					 * changes ring_pages by ->ring_lock.
+					 * changes ring_folios by ->ring_lock.
 					 */
-					ring = page_address(ctx->ring_pages[0]);
+					ring = folio_address(ctx->ring_folios[0]);
 					ring->id = ctx->id;
 					return 0;
 				}
@@ -1037,7 +1037,7 @@ static void user_refill_reqs_available(struct kioctx *ctx)
 		 * against ctx->completed_events below will make sure we do the
 		 * safe/right thing.
 		 */
-		ring = page_address(ctx->ring_pages[0]);
+		ring = folio_address(ctx->ring_folios[0]);
 		head = ring->head;
 
 		refill_reqs_available(ctx, head, ctx->tail);
@@ -1149,12 +1149,12 @@ static void aio_complete(struct aio_kiocb *iocb)
 	if (++tail >= ctx->nr_events)
 		tail = 0;
 
-	ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+	ev_page = folio_address(ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE]);
 	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
 
 	*event = iocb->ki_res;
 
-	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
+	flush_dcache_folio(ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE]);
 
 	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
 		 (void __user *)(unsigned long)iocb->ki_res.obj,
@@ -1167,10 +1167,10 @@ static void aio_complete(struct aio_kiocb *iocb)
 
 	ctx->tail = tail;
 
-	ring = page_address(ctx->ring_pages[0]);
+	ring = folio_address(ctx->ring_folios[0]);
 	head = ring->head;
 	ring->tail = tail;
-	flush_dcache_page(ctx->ring_pages[0]);
+	flush_dcache_folio(ctx->ring_folios[0]);
 
 	ctx->completed_events++;
 	if (ctx->completed_events > 1)
@@ -1242,8 +1242,8 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	sched_annotate_sleep();
 	mutex_lock(&ctx->ring_lock);
 
-	/* Access to ->ring_pages here is protected by ctx->ring_lock. */
-	ring = page_address(ctx->ring_pages[0]);
+	/* Access to ->ring_folios here is protected by ctx->ring_lock. */
+	ring = folio_address(ctx->ring_folios[0]);
 	head = ring->head;
 	tail = ring->tail;
 
@@ -1264,20 +1264,20 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	while (ret < nr) {
 		long avail;
 		struct io_event *ev;
-		struct page *page;
+		struct folio *folio;
 
 		avail = (head <= tail ?  tail : ctx->nr_events) - head;
 		if (head == tail)
 			break;
 
 		pos = head + AIO_EVENTS_OFFSET;
-		page = ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE];
+		folio = ctx->ring_folios[pos / AIO_EVENTS_PER_PAGE];
 		pos %= AIO_EVENTS_PER_PAGE;
 
 		avail = min(avail, nr - ret);
 		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);
 
-		ev = page_address(page);
+		ev = folio_address(folio);
 		copy_ret = copy_to_user(event + ret, ev + pos,
 					sizeof(*ev) * avail);
 
@@ -1291,9 +1291,9 @@ static long aio_read_events_ring(struct kioctx *ctx,
 		head %= ctx->nr_events;
 	}
 
-	ring = page_address(ctx->ring_pages[0]);
+	ring = folio_address(ctx->ring_folios[0]);
 	ring->head = head;
-	flush_dcache_page(ctx->ring_pages[0]);
+	flush_dcache_folio(ctx->ring_folios[0]);
 
 	pr_debug("%li  h%u t%u\n", ret, head, tail);
 out:
-- 
2.27.0

Re: [PATCH 0/3] fs: aio: more folio conversion

[Matthew Wilcox]

On Thu, Mar 21, 2024 at 04:27:30PM +0800, Kefeng Wang wrote:
> Convert to use folio throughout aio.

I see no problems here other than the one you mentioned and the minor
optimisation I pointed out.  Thanks.

Re: [PATCH 0/3] fs: aio: more folio conversion

[Kefeng Wang]

On 2024/3/21 20:26, Matthew Wilcox wrote:
> On Thu, Mar 21, 2024 at 04:27:30PM +0800, Kefeng Wang wrote:
>> Convert to use folio throughout aio.
> 
> I see no problems here other than the one you mentioned and the minor
> optimisation I pointed out.  Thanks.

I send v2 to fix the folio check and use the helper, thanks for you review.