From patchwork Mon Jun 14 13:20:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12318943 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75857C48BE6 for ; Mon, 14 Jun 2021 13:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C0576128C for ; Mon, 14 Jun 2021 13:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233804AbhFNNWc (ORCPT ); Mon, 14 Jun 2021 09:22:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:25970 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233805AbhFNNWb (ORCPT ); Mon, 14 Jun 2021 09:22:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623676828; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=5xj7L/EwGhvToopXR0OONDmVKcDoSh/SbGg3r7noEik=; b=GJInl8RNuvYv0+IGbuIujmh0dTID8KAnkIZK2M3c/TYKqqLmrZQ7Bq0GDxOA3GbAcdGp9G +0KaLbFMAt6pLnvCmjT/4u/XlnD6D6eg51qyXyCklUp5UZwrqRA2Nw07bZtnJgA3LJHa9c /wUVF7e4AHWs7urYA8WOQ9oYrI8Qd3g= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-103-1A-oh0Z1P4qcVXxowJTRmg-1; Mon, 14 Jun 2021 09:20:24 -0400 X-MC-Unique: 1A-oh0Z1P4qcVXxowJTRmg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0603C100CFB9; Mon, 14 Jun 2021 13:20:20 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-118-65.rdu2.redhat.com [10.10.118.65]) by smtp.corp.redhat.com (Postfix) with ESMTP id CA16D19C46; Mon, 14 Jun 2021 13:20:18 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 1/3] afs: Handle len being extending over page end in write_begin/write_end From: David Howells To: jlayton@kernel.org, willy@infradead.org Cc: linux-afs@lists.infradead.org, dhowells@redhat.com, linux-afs@lists.infradead.org, ceph-devel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 14 Jun 2021 14:20:17 +0100 Message-ID: <162367681795.460125.11729955608839747375.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org With transparent huge pages, in the future, write_begin() and write_end() may be passed a length parameter that, in combination with the offset into the page, exceeds the length of that page. This allows grab_cache_page_write_begin() to better choose the size of THP to allocate. Fix afs's functions to handle this by trimming the length as needed after the page has been allocated. Fixes: e1b1240c1ff5 ("netfs: Add write_begin helper") Reported-by: Matthew Wilcox (Oracle) Signed-off-by: David Howells cc: linux-afs@lists.infradead.org --- fs/afs/write.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/afs/write.c b/fs/afs/write.c index a523bb86915d..f68274c39f47 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -25,7 +25,8 @@ int afs_set_page_dirty(struct page *page) } /* - * prepare to perform part of a write to a page + * Prepare to perform part of a write to a page. Note that len may extend + * beyond the end of the page. */ int afs_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, @@ -52,7 +53,8 @@ int afs_write_begin(struct file *file, struct address_space *mapping, return ret; index = page->index; - from = pos - index * PAGE_SIZE; + from = offset_in_thp(page, pos); + len = min_t(size_t, len, thp_size(page) - from); to = from + len; try_again: @@ -103,7 +105,8 @@ int afs_write_begin(struct file *file, struct address_space *mapping, } /* - * finalise part of a write to a page + * Finalise part of a write to a page. Note that len may extend beyond the end + * of the page. */ int afs_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, @@ -111,7 +114,7 @@ int afs_write_end(struct file *file, struct address_space *mapping, { struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); unsigned long priv; - unsigned int f, from = pos & (thp_size(page) - 1); + unsigned int f, from = offset_in_thp(page, pos); unsigned int t, to = from + copied; loff_t i_size, maybe_i_size;