From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4459C433FE for ; Sat, 30 Apr 2022 21:40:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245573AbiD3VoC (ORCPT ); Sat, 30 Apr 2022 17:44:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245651AbiD3VoA (ORCPT ); Sat, 30 Apr 2022 17:44:00 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3ACEB1C6; Sat, 30 Apr 2022 14:40:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=m+46ifgzSQGKmNYd/J0pGOxSj2CQrYuL8G0ttBaB3sA=; b=hHKdxRVOWwmh/tNS3AohcfRwcB fqcVNHNb3HCS+FaPM+EmZBWYz9evSvJ4cRcxziAGMqH8RLQ/B1fxHp2LFwYbpw5jFH+1beRucyFaC idz6Q7VmLsrht8jY3P/HnimISfwlXfg7/XO/E8G95UwjrDf2R9Sq+iRZmNnCwT5utGOVitbb3VliA nfGi6Psqfhkp4OHYnDCp41+h+nz8Wgvm5k8hM61VfILmIJZS7SwDi6ljF52KmJ9pp1g33IiLeA3Zo iJ0zcF0IAOqKKtOXTkCkXHoKMVQq9Dtnk6NlAb9MD10+lcFNvJmRb2VSHFmZGD5JXi4FPj7iFU1sF cAVF30Qw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nkupL-00Dbva-Lo; Sat, 30 Apr 2022 21:40:31 +0000 Date: Sat, 30 Apr 2022 22:40:31 +0100 From: Matthew Wilcox To: Brian Foster Cc: "Darrick J. Wong" , xfs , fstests , linux-fsdevel Subject: Re: generic/068 crash on 5.18-rc2? Message-ID: References: <20220413033425.GM16799@magnolia> <20220418174747.GF17025@magnolia> <20220422215943.GC17025@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sat, Apr 30, 2022 at 04:44:07AM +0100, Matthew Wilcox wrote: > (I do not love this, have not even compiled it; it's late. We may be > better off just storing next_folio inside the folio_iter). Does anyone have a preference for fixing this between Option A: diff --git a/include/linux/bio.h b/include/linux/bio.h index 49eff01fb829..55e2499beff6 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -269,6 +269,7 @@ struct folio_iter { size_t offset; size_t length; /* private: for use by the iterator */ + struct folio *_next; size_t _seg_count; int _i; }; @@ -280,19 +281,23 @@ static inline void bio_first_folio(struct folio_iter *fi, struct bio *bio, fi->folio = page_folio(bvec->bv_page); fi->offset = bvec->bv_offset + - PAGE_SIZE * (bvec->bv_page - &fi->folio->page); + PAGE_SIZE * folio_page_idx(fi->folio, bvec->bv_page); fi->_seg_count = bvec->bv_len; fi->length = min(folio_size(fi->folio) - fi->offset, fi->_seg_count); fi->_i = i; + if (fi->_seg_count > fi->length) + fi->_next = folio_next(fi->folio); } static inline void bio_next_folio(struct folio_iter *fi, struct bio *bio) { fi->_seg_count -= fi->length; if (fi->_seg_count) { - fi->folio = folio_next(fi->folio); + fi->folio = fi->_next; fi->offset = 0; fi->length = min(folio_size(fi->folio), fi->_seg_count); + if (fi->_seg_count > fi->length) + fi->_next = folio_next(fi->folio); } else if (fi->_i + 1 < bio->bi_vcnt) { bio_first_folio(fi, bio, fi->_i + 1); } else { and Option B: diff --git a/include/linux/bio.h b/include/linux/bio.h index 49eff01fb829..554f5fce060c 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -290,7 +290,8 @@ static inline void bio_next_folio(struct folio_iter *fi, struct bio *bio) { fi->_seg_count -= fi->length; if (fi->_seg_count) { - fi->folio = folio_next(fi->folio); + fi->folio = __folio_next(fi->folio, + (fi->offset + fi->length) / PAGE_SIZE); fi->offset = 0; fi->length = min(folio_size(fi->folio), fi->_seg_count); } else if (fi->_i + 1 < bio->bi_vcnt) { diff --git a/include/linux/mm.h b/include/linux/mm.h index de32c0383387..9c5547af8d0e 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1642,6 +1642,12 @@ static inline long folio_nr_pages(struct folio *folio) return compound_nr(&folio->page); } +static inline struct folio *__folio_next(struct folio *folio, + unsigned long nr_pages) +{ + return (struct folio *)folio_page(folio, nr_pages); +} + /** * folio_next - Move to the next physical folio. * @folio: The folio we're currently operating on. @@ -1658,7 +1664,7 @@ static inline long folio_nr_pages(struct folio *folio) */ static inline struct folio *folio_next(struct folio *folio) { - return (struct folio *)folio_page(folio, folio_nr_pages(folio)); + return __folio_next(folio, folio_nr_pages(folio)); } /** Currently running Option A through its paces.