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=-6.5 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 94786C6786E for ; Fri, 26 Oct 2018 12:33:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 59F3920824 for ; Fri, 26 Oct 2018 12:33:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 59F3920824 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=gmx.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-btrfs-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727667AbeJZVKR (ORCPT ); Fri, 26 Oct 2018 17:10:17 -0400 Received: from mout.gmx.net ([212.227.15.18]:39183 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727555AbeJZVKR (ORCPT ); Fri, 26 Oct 2018 17:10:17 -0400 Received: from [0.0.0.0] ([210.140.77.29]) by mail.gmx.com (mrgmx002 [212.227.17.184]) with ESMTPSA (Nemesis) id 0MZCUG-1g1mlh1IGi-00Kv4S; Fri, 26 Oct 2018 14:33:16 +0200 Received: from [0.0.0.0] ([210.140.77.29]) by mail.gmx.com (mrgmx002 [212.227.17.184]) with ESMTPSA (Nemesis) id 0MZCUG-1g1mlh1IGi-00Kv4S; Fri, 26 Oct 2018 14:33:16 +0200 Subject: Re: [PATCH 1/5] btrfs: Ensure at least 1g is free for balance To: Nikolay Borisov , linux-btrfs@vger.kernel.org References: <1540554201-11305-1-git-send-email-nborisov@suse.com> <1540554201-11305-2-git-send-email-nborisov@suse.com> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: <82fb00a5-5e82-7f54-ec6e-286b51a51442@gmx.com> Date: Fri, 26 Oct 2018 20:32:57 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:BZa19/kfrVAFoNu81kPOkBkzmZ/nSzYYQWlgzYGISCx2V2oqYtK ZH7cSwuBFTVW3NmWDozt2khwcIhAf9h2C9kaS5+EJPQbFyDEaYfMbsI91NnpQ7I7X62s3hi y5LM832bPEfJIaZkLhbN1K8vamL/l+WOJnEZLcBaae/oN/+XKZ4YGaYevyst2tdUn5+NZAp MZhNHO2aDqpIHLk54e0gw== X-UI-Out-Filterresults: notjunk:1;V01:K0:Ls9VaqfvI4M=:wrHGmQ7sdptAr0dP2FfU94 /6xFQso8ad9iMWLAhesRdlr40tFTY6wbge7NOkWptCPrZOyLdHjDm2rGHUfOxvrU5XDWgwOiZ ICIVXsaiQLEPl+zy8ta1r1NKJ51XaDMQdzq7reT2xz6b0p9MyHYqFcNqMs7ED9qeekNUM41/c uoh5DVQmFxdTdp0cvM3negd+e74eIFHUgU/9IVjKBbV+WAYkzewo5RiicO6Ms6xv42JXGwnSv +gNaP5iQx41kfQD+0Q6jvcaTBH4vXUFLuGHtStuysmmwozT5x+6sortqqZJ0Afaq9+eW49Fam cCW2iZO9lsbkLWNulEY5Yt+nR//gqsaWuUM4gPNmtWAcM5inheXIderiUK9YHIvk6+AgN2bM6 bYjDf8KSsC1KEgRLmVKYHldV9cCSyRTstpVw/MSVs4tdOzub9JnKWuXWrR2riu6eEsRvdbVaA ivMOj3ovas0+WH5y7GTwZiWmtUTLz+tT07evYXAIsScesSrsNDKfM9e1xRIWEJgkegNaG8FXd pGH60vwB9rGLULTKPY8g6e/dTgoe1dsdZ2Xavf/6QyCoyw+LLUhSGQWkvpWw+uVnUPi8bTj8c kxCMkqrXz05f2YjZT4LdYOtdrSjDh9DR9aumItfw4N9Pmiv7sAKCWpS26sll9HjY228I5DY0p ip/wcjlU2kNw2+IWwbMc8HmtF1WyzndhzRu6qm9fg4T0UWSKcLKGb0U5oYKtTyoKhbSrFa6Ty CgTKZfdmINug498A8/DGypOe+2+av/VbMV+fKM+a91qRpSIBcLXk7H+svTtAc/0z6oL+gWTtA 17hmG/aB2YOuKkzRzAMqPE4V8udUGL21wtDNoQX7W5GDnnxl84= Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2018/10/26 下午8:08, Nikolay Borisov wrote: > > > On 26.10.2018 15:04, Qu Wenruo wrote: >> >> >> On 2018/10/26 下午7:43, Nikolay Borisov wrote: >>> The first part of balance operation is to shrink every constituting >>> device to ensure there is free space for chunk allocation. However, the code >>> has been buggy ever since its introduction since calculating the space to shrink >>> the device by was bounded by 1 mb. Most likely the original intention was to >>> have an upper bound of 1g and not 1m, since the largest chunk size is 1g. >> >> Minor nitpick, largest chunk size -> largest chunk stripe size. >> >> As for data chunk, it's possible to get a 10G chunk, but still only 1G >> stripe up limit. >> >>> This >>> means the first stage in __btrfs_balance so far has been a null op since it >>> effectively freed just a single megabyte. >>> >>> Fix this by setting an upper bound of size_to_free of 1g. >> >> One question come to me naturally, what if we failed to shrink the device? >> >> In fact if btrfs_shrink_device() returns ENOSPC we just skip to >> relocation part, so it doesn't look like to cause regression. >> >> If this can be mentioned in the commit message, it would save reviewer >> minutes to read the code. > > Will incorporate it in v2. > >> >> >> >> BTW, I think for that (ret == ENOSPC) after btrfs_shrink_device(), we >> should continue other than break, to get more chance to secure >> unallocated space. > > I agree but this should be done in a separate patch, this one deals with > the silly upper bound of 1m. No problem, just a hint for a new patch :) Thanks, Qu > >> >> Thanks, >> Qu >> >>> >>> Signed-off-by: Nikolay Borisov >>> --- >>> fs/btrfs/volumes.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >>> index f435d397019e..8b0fd7bf3447 100644 >>> --- a/fs/btrfs/volumes.c >>> +++ b/fs/btrfs/volumes.c >>> @@ -3467,7 +3467,7 @@ static int __btrfs_balance(struct btrfs_fs_info *fs_info) >>> list_for_each_entry(device, devices, dev_list) { >>> old_size = btrfs_device_get_total_bytes(device); >>> size_to_free = div_factor(old_size, 1); >>> - size_to_free = min_t(u64, size_to_free, SZ_1M); >>> + size_to_free = min_t(u64, size_to_free, SZ_1G); >>> if (!test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) || >>> btrfs_device_get_total_bytes(device) - >>> btrfs_device_get_bytes_used(device) > size_to_free || >>> >>