From patchwork Thu Dec 9 17:07:32 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12667745 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 7BDB2C433FE for ; Thu, 9 Dec 2021 17:08:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239031AbhLIRLl (ORCPT ); Thu, 9 Dec 2021 12:11:41 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:43301 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233985AbhLIRLk (ORCPT ); Thu, 9 Dec 2021 12:11:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639069686; 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: in-reply-to:in-reply-to:references:references; bh=pAJiHrOcvAJQ2Gwmj0Q3Mj+KlP/03WjOznw/Bcn+pVg=; b=BFBx2vw2ZVjVvzCOEs9u3lUQRtmTQI2L0GfSE9wOSyoajxVL06527s6Ht5lpZl9U8Ktj1p f/4en+RMHg3v8yyO0Ip4DxVDyiQiCHF0Djsm1G6gU2035Q2/XLyLuGrN7WPEc38br3Vgu6 UINqeA1iKCz7iH7O3v2gPvLeJFhguI4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-20-hbSaPwq0Ne-Z2yD6afTaTQ-1; Thu, 09 Dec 2021 12:08:03 -0500 X-MC-Unique: hbSaPwq0Ne-Z2yD6afTaTQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 16EA681CCB6; Thu, 9 Dec 2021 17:08:01 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.122]) by smtp.corp.redhat.com (Postfix) with ESMTP id A18921002390; Thu, 9 Dec 2021 17:07:33 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v2 55/67] afs: Handle len being extending over page end in write_begin/write_end From: David Howells To: linux-cachefs@redhat.com Cc: "Matthew Wilcox (Oracle)" , Jeff Layton , Marc Dionne , linux-afs@lists.infradead.org, dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , JeffleXu , Linus Torvalds , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Thu, 09 Dec 2021 17:07:32 +0000 Message-ID: <163906965274.143852.11487892388439890377.stgit@warthog.procyon.org.uk> In-Reply-To: <163906878733.143852.5604115678965006622.stgit@warthog.procyon.org.uk> References: <163906878733.143852.5604115678965006622.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@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. [Removed the now-unnecessary index var; spotted by kernel test robot] Fixes: e1b1240c1ff5 ("netfs: Add write_begin helper") Reported-by: Matthew Wilcox (Oracle) Signed-off-by: David Howells Acked-by: Jeff Layton cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/162367681795.460125.11729955608839747375.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163819657068.215744.601051542491746150.stgit@warthog.procyon.org.uk/ # v1 --- fs/afs/write.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/fs/afs/write.c b/fs/afs/write.c index ca4909baf5e6..8e4e87d66855 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, @@ -36,7 +37,6 @@ int afs_write_begin(struct file *file, struct address_space *mapping, unsigned long priv; unsigned f, from; unsigned t, to; - pgoff_t index; int ret; _enter("{%llx:%llu},%llx,%x", @@ -51,8 +51,8 @@ int afs_write_begin(struct file *file, struct address_space *mapping, if (ret < 0) return ret; - index = folio_index(folio); - from = pos - index * PAGE_SIZE; + from = offset_in_folio(folio, pos); + len = min_t(size_t, len, folio_size(folio) - from); to = from + len; try_again: @@ -103,7 +103,8 @@ 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,