Commit 5c075c5b authored by Fabio M. De Francesco's avatar Fabio M. De Francesco Committed by Christian Brauner
Browse files

fs/aio: Stop allocating aio rings from HIGHMEM 



There is no need to allocate aio rings from HIGHMEM because of very
little memory needed here.

Therefore, use GFP_USER flag in find_or_create_page() and get rid of
kmap*() mappings.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Ira Weiny <ira.weiny@intel.com>
Suggested-by: default avatarMatthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarFabio M. De Francesco <fmdefrancesco@gmail.com>
Reviewed-by: default avatarIra Weiny <ira.weiny@intel.com>
Message-Id: <20230609145937.17610-1-fmdefrancesco@gmail.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent b6334e2c

fs/aio.c

+9 −17
Original line number Diff line number Diff line
@@ -530,7 +530,7 @@ 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_HIGHUSER | __GFP_ZERO);

					   i, GFP_USER | __GFP_ZERO);

		if (!page)

			break;

		pr_debug("pid(%d) page[%d]->count=%d\n",
@@ -571,7 +571,7 @@ 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 = kmap_atomic(ctx->ring_pages[0]);

	ring = page_address(ctx->ring_pages[0]);

	ring->nr = nr_events;	/* user copy */

	ring->id = ~0U;

	ring->head = ring->tail = 0;
@@ -579,7 +579,6 @@ 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);

	kunmap_atomic(ring);

	flush_dcache_page(ctx->ring_pages[0]);



	return 0;
@@ -682,9 +681,8 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm) 
					 * we are protected from page migration

					 * changes ring_pages by ->ring_lock.

					 */

					ring = kmap_atomic(ctx->ring_pages[0]);

					ring = page_address(ctx->ring_pages[0]);

					ring->id = ctx->id;

					kunmap_atomic(ring);

					return 0;

				}
@@ -1025,9 +1023,8 @@ static void user_refill_reqs_available(struct kioctx *ctx) 
		 * against ctx->completed_events below will make sure we do the

		 * safe/right thing.

		 */

		ring = kmap_atomic(ctx->ring_pages[0]);

		ring = page_address(ctx->ring_pages[0]);

		head = ring->head;

		kunmap_atomic(ring);



		refill_reqs_available(ctx, head, ctx->tail);

	}
@@ -1133,12 +1130,11 @@ static void aio_complete(struct aio_kiocb *iocb) 
	if (++tail >= ctx->nr_events)

		tail = 0;



	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);

	ev_page = page_address(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);

	event = ev_page + pos % AIO_EVENTS_PER_PAGE;



	*event = iocb->ki_res;



	kunmap_atomic(ev_page);

	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);



	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n", ctx, tail, iocb,
@@ -1152,10 +1148,9 @@ static void aio_complete(struct aio_kiocb *iocb) 


	ctx->tail = tail;



	ring = kmap_atomic(ctx->ring_pages[0]);

	ring = page_address(ctx->ring_pages[0]);

	head = ring->head;

	ring->tail = tail;

	kunmap_atomic(ring);

	flush_dcache_page(ctx->ring_pages[0]);



	ctx->completed_events++;
@@ -1215,10 +1210,9 @@ static long aio_read_events_ring(struct kioctx *ctx, 
	mutex_lock(&ctx->ring_lock);



	/* Access to ->ring_pages here is protected by ctx->ring_lock. */

	ring = kmap_atomic(ctx->ring_pages[0]);

	ring = page_address(ctx->ring_pages[0]);

	head = ring->head;

	tail = ring->tail;

	kunmap_atomic(ring);



	/*

	 * Ensure that once we've read the current tail pointer, that
@@ -1250,10 +1244,9 @@ static long aio_read_events_ring(struct kioctx *ctx, 
		avail = min(avail, nr - ret);

		avail = min_t(long, avail, AIO_EVENTS_PER_PAGE - pos);



		ev = kmap(page);

		ev = page_address(page);

		copy_ret = copy_to_user(event + ret, ev + pos,

					sizeof(*ev) * avail);

		kunmap(page);



		if (unlikely(copy_ret)) {

			ret = -EFAULT;
@@ -1265,9 +1258,8 @@ static long aio_read_events_ring(struct kioctx *ctx, 
		head %= ctx->nr_events;

	}



	ring = kmap_atomic(ctx->ring_pages[0]);

	ring = page_address(ctx->ring_pages[0]);

	ring->head = head;

	kunmap_atomic(ring);

	flush_dcache_page(ctx->ring_pages[0]);



	pr_debug("%li  h%u t%u\n", ret, head, tail);