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 814B4C001DD for ; Thu, 13 Jul 2023 04:42:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233845AbjGMEmL (ORCPT ); Thu, 13 Jul 2023 00:42:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233659AbjGMEmK (ORCPT ); Thu, 13 Jul 2023 00:42:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56A6019B9; Wed, 12 Jul 2023 21:42:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E9A0E619B0; Thu, 13 Jul 2023 04:42:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4C57AC433C8; Thu, 13 Jul 2023 04:42:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689223328; bh=eykB0apE7Xtvo5kC4MX3hePLLE/Wk4V+dfp++PZB/LM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rTCMvPQzs1N43zu/PfsS27WZpGjCTw4Z1vl2ea4LIrVbOcXoJkenx3UTNchJFW2z3 WdP3fnxixTNpB+GvUDRU1uOXt6T6DduX5qnWPbvf31WD265RfqmP07PwPhhGuO1yCh lrhMyyKhM2RSgsfNGebrf3xlr4Z688Qp3MY4GHrwS4UzyQ8JD1JJdRH4XJ8XGSGQOe zbFfyTdDIA2iNROJyNXFb0VedorSmQzyKww7+CBCnr1MqR3ZuDj45GIckazW1qQ7kl /giYHYk2by6rFDEB54/JBbB9gyw3bv1JkHLEnPXCphsZQF0+Y/1w6Z9SDhOPcI/meY 4jHtD7Cp/Bu+w== Date: Wed, 12 Jul 2023 21:42:07 -0700 From: "Darrick J. Wong" To: "Matthew Wilcox (Oracle)" Cc: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, Wang Yugui , Dave Chinner , Christoph Hellwig , Kent Overstreet Subject: Re: [PATCH v4 1/9] iov_iter: Handle compound highmem pages in copy_page_from_iter_atomic() Message-ID: <20230713044207.GH108251@frogsfrogsfrogs> References: <20230710130253.3484695-1-willy@infradead.org> <20230710130253.3484695-2-willy@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230710130253.3484695-2-willy@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, Jul 10, 2023 at 02:02:45PM +0100, Matthew Wilcox (Oracle) wrote: > copy_page_from_iter_atomic() already handles !highmem compound > pages correctly, but if we are passed a highmem compound page, > each base page needs to be mapped & unmapped individually. > > Signed-off-by: Matthew Wilcox (Oracle) Yikes. Does this want a fixes tag? Reviewed-by: Darrick J. Wong --D > --- > lib/iov_iter.c | 43 ++++++++++++++++++++++++++++--------------- > 1 file changed, 28 insertions(+), 15 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index b667b1e2f688..c728b6e4fb18 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -566,24 +566,37 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i) > } > EXPORT_SYMBOL(iov_iter_zero); > > -size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t bytes, > - struct iov_iter *i) > +size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, > + size_t bytes, struct iov_iter *i) > { > - char *kaddr = kmap_atomic(page), *p = kaddr + offset; > - if (!page_copy_sane(page, offset, bytes)) { > - kunmap_atomic(kaddr); > + size_t n, copied = 0; > + > + if (!page_copy_sane(page, offset, bytes)) > return 0; > - } > - if (WARN_ON_ONCE(!i->data_source)) { > - kunmap_atomic(kaddr); > + if (WARN_ON_ONCE(!i->data_source)) > return 0; > - } > - iterate_and_advance(i, bytes, base, len, off, > - copyin(p + off, base, len), > - memcpy_from_iter(i, p + off, base, len) > - ) > - kunmap_atomic(kaddr); > - return bytes; > + > + do { > + char *p; > + > + n = bytes - copied; > + if (PageHighMem(page)) { > + page += offset / PAGE_SIZE; > + offset %= PAGE_SIZE; > + n = min_t(size_t, n, PAGE_SIZE - offset); > + } > + > + p = kmap_atomic(page) + offset; > + iterate_and_advance(i, n, base, len, off, > + copyin(p + off, base, len), > + memcpy_from_iter(i, p + off, base, len) > + ) > + kunmap_atomic(p); > + copied += n; > + offset += n; > + } while (PageHighMem(page) && copied != bytes && n > 0); > + > + return copied; > } > EXPORT_SYMBOL(copy_page_from_iter_atomic); > > -- > 2.39.2 >