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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,T_MIXED_ES, 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 43AC6C67839 for ; Wed, 12 Dec 2018 16:02:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 068E820672 for ; Wed, 12 Dec 2018 16:02:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 068E820672 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.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 S1727848AbeLLQCB (ORCPT ); Wed, 12 Dec 2018 11:02:01 -0500 Received: from mx2.suse.de ([195.135.220.15]:44536 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726281AbeLLQCB (ORCPT ); Wed, 12 Dec 2018 11:02:01 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 3E8EAAFD8; Wed, 12 Dec 2018 16:01:58 +0000 (UTC) Subject: Re: [PATCH 6/8] btrfs: loop in inode_rsv_refill To: Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com References: <20181203152459.21630-1-josef@toxicpanda.com> <20181203152459.21630-7-josef@toxicpanda.com> From: Nikolay Borisov Openpgp: preference=signencrypt Autocrypt: addr=nborisov@suse.com; prefer-encrypt=mutual; keydata= xsFNBFiKBz4BEADNHZmqwhuN6EAzXj9SpPpH/nSSP8YgfwoOqwrP+JR4pIqRK0AWWeWCSwmZ T7g+RbfPFlmQp+EwFWOtABXlKC54zgSf+uulGwx5JAUFVUIRBmnHOYi/lUiE0yhpnb1KCA7f u/W+DkwGerXqhhe9TvQoGwgCKNfzFPZoM+gZrm+kWv03QLUCr210n4cwaCPJ0Nr9Z3c582xc bCUVbsjt7BN0CFa2BByulrx5xD9sDAYIqfLCcZetAqsTRGxM7LD0kh5WlKzOeAXj5r8DOrU2 GdZS33uKZI/kZJZVytSmZpswDsKhnGzRN1BANGP8sC+WD4eRXajOmNh2HL4P+meO1TlM3GLl EQd2shHFY0qjEo7wxKZI1RyZZ5AgJnSmehrPCyuIyVY210CbMaIKHUIsTqRgY5GaNME24w7h TyyVCy2qAM8fLJ4Vw5bycM/u5xfWm7gyTb9V1TkZ3o1MTrEsrcqFiRrBY94Rs0oQkZvunqia c+NprYSaOG1Cta14o94eMH271Kka/reEwSZkC7T+o9hZ4zi2CcLcY0DXj0qdId7vUKSJjEep c++s8ncFekh1MPhkOgNj8pk17OAESanmDwksmzh1j12lgA5lTFPrJeRNu6/isC2zyZhTwMWs k3LkcTa8ZXxh0RfWAqgx/ogKPk4ZxOXQEZetkEyTFghbRH2BIwARAQABzSJOaWtvbGF5IEJv cmlzb3YgPG5ib3Jpc292QHN1c2UuZGU+wsF4BBMBAgAiBQJYijkSAhsDBgsJCAcDAgYVCAIJ CgsEFgIDAQIeAQIXgAAKCRBxvoJG5T8oV/B6D/9a8EcRPdHg8uLEPywuJR8URwXzkofT5bZE IfGF0Z+Lt2ADe+nLOXrwKsamhweUFAvwEUxxnndovRLPOpWerTOAl47lxad08080jXnGfYFS Dc+ew7C3SFI4tFFHln8Y22Q9075saZ2yQS1ywJy+TFPADIprAZXnPbbbNbGtJLoq0LTiESnD w/SUC6sfikYwGRS94Dc9qO4nWyEvBK3Ql8NkoY0Sjky3B0vL572Gq0ytILDDGYuZVo4alUs8 LeXS5ukoZIw1QYXVstDJQnYjFxYgoQ5uGVi4t7FsFM/6ykYDzbIPNOx49Rbh9W4uKsLVhTzG BDTzdvX4ARl9La2kCQIjjWRg+XGuBM5rxT/NaTS78PXjhqWNYlGc5OhO0l8e5DIS2tXwYMDY LuHYNkkpMFksBslldvNttSNei7xr5VwjVqW4vASk2Aak5AleXZS+xIq2FADPS/XSgIaepyTV tkfnyreep1pk09cjfXY4A7qpEFwazCRZg9LLvYVc2M2eFQHDMtXsH59nOMstXx2OtNMcx5p8 0a5FHXE/HoXz3p9bD0uIUq6p04VYOHsMasHqHPbsMAq9V2OCytJQPWwe46bBjYZCOwG0+x58 fBFreP/NiJNeTQPOa6FoxLOLXMuVtpbcXIqKQDoEte9aMpoj9L24f60G4q+pL/54ql2VRscK d87BTQRYigc+ARAAyJSq9EFk28++SLfg791xOh28tLI6Yr8wwEOvM3wKeTfTZd+caVb9gBBy wxYhIopKlK1zq2YP7ZjTP1aPJGoWvcQZ8fVFdK/1nW+Z8/NTjaOx1mfrrtTGtFxVBdSCgqBB jHTnlDYV1R5plJqK+ggEP1a0mr/rpQ9dFGvgf/5jkVpRnH6BY0aYFPprRL8ZCcdv2DeeicOO YMobD5g7g/poQzHLLeT0+y1qiLIFefNABLN06Lf0GBZC5l8hCM3Rpb4ObyQ4B9PmL/KTn2FV Xq/c0scGMdXD2QeWLePC+yLMhf1fZby1vVJ59pXGq+o7XXfYA7xX0JsTUNxVPx/MgK8aLjYW hX+TRA4bCr4uYt/S3ThDRywSX6Hr1lyp4FJBwgyb8iv42it8KvoeOsHqVbuCIGRCXqGGiaeX Wa0M/oxN1vJjMSIEVzBAPi16tztL/wQtFHJtZAdCnuzFAz8ue6GzvsyBj97pzkBVacwp3/Mw qbiu7sDz7yB0d7J2tFBJYNpVt/Lce6nQhrvon0VqiWeMHxgtQ4k92Eja9u80JDaKnHDdjdwq FUikZirB28UiLPQV6PvCckgIiukmz/5ctAfKpyYRGfez+JbAGl6iCvHYt/wAZ7Oqe/3Cirs5 KhaXBcMmJR1qo8QH8eYZ+qhFE3bSPH446+5oEw8A9v5oonKV7zMAEQEAAcLBXwQYAQIACQUC WIoHPgIbDAAKCRBxvoJG5T8oV1pyD/4zdXdOL0lhkSIjJWGqz7Idvo0wjVHSSQCbOwZDWNTN JBTP0BUxHpPu/Z8gRNNP9/k6i63T4eL1xjy4umTwJaej1X15H8Hsh+zakADyWHadbjcUXCkg OJK4NsfqhMuaIYIHbToi9K5pAKnV953xTrK6oYVyd/Rmkmb+wgsbYQJ0Ur1Ficwhp6qU1CaJ mJwFjaWaVgUERoxcejL4ruds66LM9Z1Qqgoer62ZneID6ovmzpCWbi2sfbz98+kW46aA/w8r 7sulgs1KXWhBSv5aWqKU8C4twKjlV2XsztUUsyrjHFj91j31pnHRklBgXHTD/pSRsN0UvM26 lPs0g3ryVlG5wiZ9+JbI3sKMfbdfdOeLxtL25ujs443rw1s/PVghphoeadVAKMPINeRCgoJH zZV/2Z/myWPRWWl/79amy/9MfxffZqO9rfugRBORY0ywPHLDdo9Kmzoxoxp9w3uTrTLZaT9M KIuxEcV8wcVjr+Wr9zRl06waOCkgrQbTPp631hToxo+4rA1jiQF2M80HAet65ytBVR2pFGZF zGYYLqiG+mpUZ+FPjxk9kpkRYz61mTLSY7tuFljExfJWMGfgSg1OxfLV631jV1TcdUnx+h3l Sqs2vMhAVt14zT8mpIuu2VNxcontxgVr1kzYA/tQg32fVRbGr449j1gw57BV9i0vww== Message-ID: <6a7a6a50-9a58-032e-e62a-c551b257b0ac@suse.com> Date: Wed, 12 Dec 2018 18:01:57 +0200 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: <20181203152459.21630-7-josef@toxicpanda.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 3.12.18 г. 17:24 ч., Josef Bacik wrote: > With severe fragmentation we can end up with our inode rsv size being > huge during writeout, which would cause us to need to make very large > metadata reservations. However we may not actually need that much once The sentence beginning with "However" needs more information, why might we not need that much once writeout is complete? > writeout is complete. So instead try to make our reservation, and if we > couldn't make it re-calculate our new reservation size and try again. Why do you think that recalculating the requested bytes will be different the 2nd time ? > If our reservation size doesn't change between tries then we know we are > actually out of space and can error out. > > Signed-off-by: Josef Bacik > --- > fs/btrfs/extent-tree.c | 58 +++++++++++++++++++++++++++++++++++++------------- > 1 file changed, 43 insertions(+), 15 deletions(-) > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 0ee77a98f867..0e1a499035ac 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -5787,6 +5787,21 @@ int btrfs_block_rsv_refill(struct btrfs_root *root, > return ret; > } > > +static inline void __get_refill_bytes(struct btrfs_block_rsv *block_rsv, > + u64 *metadata_bytes, u64 *qgroup_bytes) This function needs a better name. Something like calc_required_bytes or calc_refill_bytes > +{ > + *metadata_bytes = 0; > + *qgroup_bytes = 0; > + > + spin_lock(&block_rsv->lock); > + if (block_rsv->reserved < block_rsv->size) > + *metadata_bytes = block_rsv->size - block_rsv->reserved; > + if (block_rsv->qgroup_rsv_reserved < block_rsv->qgroup_rsv_size) > + *qgroup_bytes = block_rsv->qgroup_rsv_size - > + block_rsv->qgroup_rsv_reserved; > + spin_unlock(&block_rsv->lock); > +} > + > /** > * btrfs_inode_rsv_refill - refill the inode block rsv. > * @inode - the inode we are refilling. > @@ -5802,25 +5817,39 @@ static int btrfs_inode_rsv_refill(struct btrfs_inode *inode, > { > struct btrfs_root *root = inode->root; > struct btrfs_block_rsv *block_rsv = &inode->block_rsv; > - u64 num_bytes = 0; > + u64 num_bytes = 0, last = 0; > u64 qgroup_num_bytes = 0; > int ret = -ENOSPC; > > - spin_lock(&block_rsv->lock); > - if (block_rsv->reserved < block_rsv->size) > - num_bytes = block_rsv->size - block_rsv->reserved; > - if (block_rsv->qgroup_rsv_reserved < block_rsv->qgroup_rsv_size) > - qgroup_num_bytes = block_rsv->qgroup_rsv_size - > - block_rsv->qgroup_rsv_reserved; > - spin_unlock(&block_rsv->lock); > - > + __get_refill_bytes(block_rsv, &num_bytes, &qgroup_num_bytes); > if (num_bytes == 0) > return 0; > > - ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_num_bytes, true); > - if (ret) > - return ret; > - ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush); > + do { > + ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_num_bytes, true); > + if (ret) > + return ret; > + ret = reserve_metadata_bytes(root, block_rsv, num_bytes, flush); > + if (ret) { > + btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes); > + last = num_bytes; > + /* > + * If we are fragmented we can end up with a lot of > + * outstanding extents which will make our size be much > + * larger than our reserved amount. If we happen to > + * try to do a reservation here that may result in us > + * trying to do a pretty hefty reservation, which we may > + * not need once delalloc flushing happens. If this is The "If we happen" sentence needs to be reworded because it's -ENOPARSE. Perhaps one of the "to do a reservation" should go away? > + * the case try and do the reserve again. > + */ > + if (flush == BTRFS_RESERVE_FLUSH_ALL) > + __get_refill_bytes(block_rsv, &num_bytes, > + &qgroup_num_bytes); > + if (num_bytes == 0) > + return 0; > + } > + } while (ret && last != num_bytes); > + > if (!ret) { > block_rsv_add_bytes(block_rsv, num_bytes, false); > trace_btrfs_space_reservation(root->fs_info, "delalloc", > @@ -5830,8 +5859,7 @@ static int btrfs_inode_rsv_refill(struct btrfs_inode *inode, > spin_lock(&block_rsv->lock); > block_rsv->qgroup_rsv_reserved += qgroup_num_bytes; > spin_unlock(&block_rsv->lock); > - } else > - btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes); > + } > return ret; > } > >