From patchwork Mon Nov 2 07:31:14 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 11873089 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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 ED431C388F2 for ; Mon, 2 Nov 2020 07:31:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1552221FF for ; Mon, 2 Nov 2020 07:31:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="UEnjJ7wP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728093AbgKBHbX (ORCPT ); Mon, 2 Nov 2020 02:31:23 -0500 Received: from mx2.suse.de ([195.135.220.15]:44118 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726819AbgKBHbV (ORCPT ); Mon, 2 Nov 2020 02:31:21 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1604302280; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=fWvBZviczV9Wz6AR6xlBLzNE41HcgXB/TRqIGz895O0=; b=UEnjJ7wPHK/5bxF5pKoE7RZYl8eKgbgcWh7/XBDuZgxtSnrNmlVBtuuWTC1704WtMrpr+c PZ3OlKSo5/WcbJ3EzFoxL3lgKYD35YJ+X/yzQHpzrse1MN4IeR6XZbMJGWb9O5Ee2J81+Y 0e31E7NlNCYqsWWbW/jq1lVbzddQr2w= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9C9FFACF6 for ; Mon, 2 Nov 2020 07:31:20 +0000 (UTC) From: Qu Wenruo To: linux-btrfs@vger.kernel.org Subject: [PATCH] btrfs: fix build warning due to u64 devided by u32 for 32bit arch Date: Mon, 2 Nov 2020 15:31:14 +0800 Message-Id: <20201102073114.66750-1-wqu@suse.com> X-Mailer: git-send-email 2.29.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org [BUG] When building the kernel with subpage preparation patches, 32bit arches will complain about the following linking error: ld: fs/btrfs/extent_io.o: in function `release_extent_buffer': fs/btrfs/extent_io.c:5340: undefined reference to `__udivdi3' [CAUSE] For 32bits, dividing u64 with u32 need to call div_u64(), not directly call u64 / u32. [FIX] Instead of calling the div_u64() macros, here we introduce a helper, btrfs_sector_shift(), to calculate the sector shift, and we just do bit shift to avoid executing the expensive division instruction. The sector_shift may be better cached in btrfs_fs_info, but so far there are only very limited callers for that, thus the fs_info::sector_shift can be there for further cleanup. David, can this patch be folded into the offending commit? The patch is small enough, and doesn't change btrfs_fs_info. Thus should be OK to fold. Fixes: ef57afc454fb ("btrfs: extent_io: make btrfs_fs_info::buffer_radix to take sector size devided values") Signed-off-by: Qu Wenruo --- fs/btrfs/ctree.h | 5 +++++ fs/btrfs/extent_io.c | 14 +++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 8a83bce3225c..eb282af985f5 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -3489,6 +3489,11 @@ static inline int __btrfs_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag) return !!(btrfs_super_compat_ro_flags(disk_super) & flag); } +static inline u8 btrfs_sector_shift(struct btrfs_fs_info *fs_info) +{ + return ilog2(fs_info->sectorsize); +} + /* acl.c */ #ifdef CONFIG_BTRFS_FS_POSIX_ACL struct posix_acl *btrfs_get_acl(struct inode *inode, int type); diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 80b35885004a..3452019aef79 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -5129,10 +5129,10 @@ struct extent_buffer *find_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb; + u8 sector_shift = btrfs_sector_shift(fs_info); rcu_read_lock(); - eb = radix_tree_lookup(&fs_info->buffer_radix, - start / fs_info->sectorsize); + eb = radix_tree_lookup(&fs_info->buffer_radix, start >> sector_shift); if (eb && atomic_inc_not_zero(&eb->refs)) { rcu_read_unlock(); /* @@ -5167,6 +5167,7 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, u64 start) { struct extent_buffer *eb, *exists = NULL; + u8 sector_shift = btrfs_sector_shift(fs_info); int ret; eb = find_extent_buffer(fs_info, start); @@ -5184,7 +5185,7 @@ struct extent_buffer *alloc_test_extent_buffer(struct btrfs_fs_info *fs_info, } spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, - start / fs_info->sectorsize, eb); + start >> sector_shift, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { @@ -5215,6 +5216,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, struct extent_buffer *exists = NULL; struct page *p; struct address_space *mapping = fs_info->btree_inode->i_mapping; + u8 sector_shift = btrfs_sector_shift(fs_info); int uptodate = 1; int ret; @@ -5292,7 +5294,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info, spin_lock(&fs_info->buffer_lock); ret = radix_tree_insert(&fs_info->buffer_radix, - start / fs_info->sectorsize, eb); + start >> sector_shift, eb); spin_unlock(&fs_info->buffer_lock); radix_tree_preload_end(); if (ret == -EEXIST) { @@ -5337,6 +5339,8 @@ static inline void btrfs_release_extent_buffer_rcu(struct rcu_head *head) static int release_extent_buffer(struct extent_buffer *eb) __releases(&eb->refs_lock) { + u8 sector_shift = btrfs_sector_shift(eb->fs_info); + lockdep_assert_held(&eb->refs_lock); WARN_ON(atomic_read(&eb->refs) == 0); @@ -5348,7 +5352,7 @@ static int release_extent_buffer(struct extent_buffer *eb) spin_lock(&fs_info->buffer_lock); radix_tree_delete(&fs_info->buffer_radix, - eb->start / fs_info->sectorsize); + eb->start >> sector_shift); spin_unlock(&fs_info->buffer_lock); } else { spin_unlock(&eb->refs_lock);