From 91d6ac1d62c3dc0f102986318f4027ccfa22c638 Mon Sep 17 00:00:00 2001 From: Sweet Tea Dorminy Date: Wed, 30 Mar 2022 16:11:23 -0400 Subject: [PATCH] btrfs: allocate page arrays using bulk page allocator While calling alloc_page() in a loop is an effective way to populate an array of pages, the MM subsystem provides a method to allocate pages in bulk. alloc_pages_bulk_array() populates the NULL slots in a page array, trying to grab more than one page at a time. Unfortunately, it doesn't guarantee allocating all slots in the array, but it's easy to call it in a loop and return an error if no progress occurs. Reviewed-by: Nikolay Borisov Signed-off-by: Sweet Tea Dorminy Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent_io.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index e472886..cfcbfd5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3146,17 +3146,20 @@ readpage_ok: */ int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array) { - int i; + unsigned int allocated; - for (i = 0; i < nr_pages; i++) { - struct page *page; + for (allocated = 0; allocated < nr_pages;) { + unsigned int last = allocated; - if (page_array[i]) - continue; - page = alloc_page(GFP_NOFS); - if (!page) + allocated = alloc_pages_bulk_array(GFP_NOFS, nr_pages, page_array); + + /* + * During this iteration, no page could be allocated, even + * though alloc_pages_bulk_array() falls back to alloc_page() + * if it could not bulk-allocate. So we must be out of memory. + */ + if (allocated == last) return -ENOMEM; - page_array[i] = page; } return 0; } -- 2.7.4