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 X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 B549AC43613 for ; Fri, 21 Jun 2019 09:56:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9286E20665 for ; Fri, 21 Jun 2019 09:56:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726229AbfFUJ4J (ORCPT ); Fri, 21 Jun 2019 05:56:09 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:33512 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbfFUJ4J (ORCPT ); Fri, 21 Jun 2019 05:56:09 -0400 Received: by mail-qt1-f193.google.com with SMTP id x2so6330468qtr.0; Fri, 21 Jun 2019 02:56:08 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zoSCQQgDyqdNTKrY/BA7yRe6rgMh4ABI0Zse4HOFW8I=; b=iGbUzHSUsXKE4Mhdgla4u6B7/wCG8Wbmf5kDEQ4BN4k1tQ8eg8CQayXAinNe5wTRGl RgZb3XHyc3YUpW/i6jHAP2Slc280FCqKj4v1pyc3XxorwWYgJ9iHTb3QF2zwUZuUT/fB RVFxSEKbmMSV8JQPOW68FxPyBLivkZCncf9tp4NEz/ZV8fRl8ykLK+pjeyJSfF38jqXP fZ/ntGqcFdrzhmJSLFKtHne4UkS5Eca6PdGXe4CgH4tx2t6iI6BUU5qzbt4HSsqu9fdx 8QeL7UYNipQ2zOZjrEfWxkurPIbyI4/KAK3wyWO30U6rxA8itr/IkMri5NUHlFDujyDV SESw== X-Gm-Message-State: APjAAAVriE4RiYeS1vHfGyvxgGyYEdIomySOqmqhCFsE87bF3ZM05ExW xUv5sqP0emizTYgZgFatYR7PYimq627vK1UvQCs= X-Google-Smtp-Source: APXvYqxw7aZjDgZ7ucZwG6IV1T0CZcfI+f0WlXd3bEKJ5eJl95/WgLNK/53xguy0PsbHRE0STqxRzd1MrkBr3wNBVjI= X-Received: by 2002:ac8:2379:: with SMTP id b54mr56769954qtb.168.1561110967884; Fri, 21 Jun 2019 02:56:07 -0700 (PDT) MIME-Version: 1.0 References: <20190620143800.20640-1-geert@linux-m68k.org> In-Reply-To: From: Geert Uytterhoeven Date: Fri, 21 Jun 2019 11:55:56 +0200 Message-ID: Subject: Re: [PATCH -next] f2fs: Use div_u64*() for 64-bit divisions To: Chao Yu Cc: Qiuyang Sun , Jaegeuk Kim , linux-f2fs-devel@lists.sourceforge.net, Linux-Next , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-next-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-next@vger.kernel.org Hi Chao, On Fri, Jun 21, 2019 at 11:54 AM Chao Yu wrote: > Since the original patch hasn't been merged to upstream, I think we can merge > this into original patch, how do you think? Thanks, that's fine for me. > On 2019/6/20 22:38, Geert Uytterhoeven wrote: > > On 32-bit (e.g. m68k): > > > > fs/f2fs/gc.o: In function `f2fs_resize_fs': > > gc.c:(.text+0x3056): undefined reference to `__umoddi3' > > gc.c:(.text+0x30c4): undefined reference to `__udivdi3' > > > > Fix this by using div_u64_rem() and div_u64() for 64-by-32 modulo resp. > > division operations. > > > > Reported-by: noreply@ellerman.id.au > > Fixes: d2ae7494d043bfaf ("f2fs: ioctl for removing a range from F2FS") > > Signed-off-by: Geert Uytterhoeven > > --- > > This assumes BLKS_PER_SEC(sbi) is 32-bit. > > > > #define BLKS_PER_SEC(sbi) \ > > ((sbi)->segs_per_sec * (sbi)->blocks_per_seg) > > > > Notes: > > 1. f2fs_sb_info.segs_per_sec and f2fs_sb_info.blocks_per_seg are both > > unsigned int, > > 2. The multiplication is done in 32-bit arithmetic, hence the result > > is of type unsigned int. > > 3. Is it guaranteed that the result will always fit in 32-bit, or can > > this overflow? > > 4. fs/f2fs/debug.c:update_sit_info() assigns BLKS_PER_SEC(sbi) to > > unsigned long long blks_per_sec, anticipating a 64-bit value. > > --- > > fs/f2fs/gc.c | 6 ++++-- > > 1 file changed, 4 insertions(+), 2 deletions(-) > > > > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c > > index 5b1076505ade9f84..c65f87f11de029f4 100644 > > --- a/fs/f2fs/gc.c > > +++ b/fs/f2fs/gc.c > > @@ -1438,13 +1438,15 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > unsigned int secs; > > int gc_mode, gc_type; > > int err = 0; > > + __u32 rem; > > > > old_block_count = le64_to_cpu(F2FS_RAW_SUPER(sbi)->block_count); > > if (block_count > old_block_count) > > return -EINVAL; > > > > /* new fs size should align to section size */ > > - if (block_count % BLKS_PER_SEC(sbi)) > > + div_u64_rem(block_count, BLKS_PER_SEC(sbi), &rem); > > + if (rem) > > return -EINVAL; > > > > if (block_count == old_block_count) > > @@ -1463,7 +1465,7 @@ int f2fs_resize_fs(struct f2fs_sb_info *sbi, __u64 block_count) > > freeze_bdev(sbi->sb->s_bdev); > > > > shrunk_blocks = old_block_count - block_count; > > - secs = shrunk_blocks / BLKS_PER_SEC(sbi); > > + secs = div_u64(shrunk_blocks, BLKS_PER_SEC(sbi)); > > spin_lock(&sbi->stat_lock); > > if (shrunk_blocks + valid_user_blocks(sbi) + > > sbi->current_reserved_blocks + sbi->unusable_block_count + Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds