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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 E1DA1C43441 for ; Tue, 27 Nov 2018 08:30:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A0E4420873 for ; Tue, 27 Nov 2018 08:30:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A0E4420873 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 S1729224AbeK0T1G (ORCPT ); Tue, 27 Nov 2018 14:27:06 -0500 Received: from mx2.suse.de ([195.135.220.15]:37028 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729152AbeK0T1G (ORCPT ); Tue, 27 Nov 2018 14:27:06 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2BE41ADF4; Tue, 27 Nov 2018 08:29:58 +0000 (UTC) Subject: Re: [PATCH 3/3] btrfs: replace cleaner_delayed_iput_mutex with a waitqueue To: Josef Bacik , linux-btrfs@vger.kernel.org, kernel-team@fb.com References: <20181121190922.25038-1-josef@toxicpanda.com> <20181121190922.25038-4-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: <34807ceb-525c-2552-b2c0-a850da135f74@suse.com> Date: Tue, 27 Nov 2018 10:29:57 +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: <20181121190922.25038-4-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 21.11.18 г. 21:09 ч., Josef Bacik wrote: > The throttle path doesn't take cleaner_delayed_iput_mutex, which means Which one is the throttle path? btrfs_end_transaction_throttle is only called during snapshot drop and relocation? What scenario triggered your observation and prompted this fix? > we could think we're done flushing iputs in the data space reservation > path when we could have a throttler doing an iput. There's no real > reason to serialize the delayed iput flushing, so instead of taking the > cleaner_delayed_iput_mutex whenever we flush the delayed iputs just > replace it with an atomic counter and a waitqueue. This removes the > short (or long depending on how big the inode is) window where we think > there are no more pending iputs when there really are some. > > Signed-off-by: Josef Bacik > --- > fs/btrfs/ctree.h | 4 +++- > fs/btrfs/disk-io.c | 5 ++--- > fs/btrfs/extent-tree.c | 9 +++++---- > fs/btrfs/inode.c | 21 +++++++++++++++++++++ > 4 files changed, 31 insertions(+), 8 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index 709de7471d86..a835fe7076eb 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -912,7 +912,8 @@ struct btrfs_fs_info { > > spinlock_t delayed_iput_lock; > struct list_head delayed_iputs; > - struct mutex cleaner_delayed_iput_mutex; > + atomic_t nr_delayed_iputs; > + wait_queue_head_t delayed_iputs_wait; > > /* this protects tree_mod_seq_list */ > spinlock_t tree_mod_seq_lock; > @@ -3237,6 +3238,7 @@ int btrfs_orphan_cleanup(struct btrfs_root *root); > int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size); > void btrfs_add_delayed_iput(struct inode *inode); > void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info); > +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info); > int btrfs_prealloc_file_range(struct inode *inode, int mode, > u64 start, u64 num_bytes, u64 min_size, > loff_t actual_len, u64 *alloc_hint); > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index c5918ff8241b..3f81dfaefa32 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1692,9 +1692,7 @@ static int cleaner_kthread(void *arg) > goto sleep; > } > > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > btrfs_run_delayed_iputs(fs_info); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > > again = btrfs_clean_one_deleted_snapshot(root); > mutex_unlock(&fs_info->cleaner_mutex); > @@ -2651,7 +2649,6 @@ int open_ctree(struct super_block *sb, > mutex_init(&fs_info->delete_unused_bgs_mutex); > mutex_init(&fs_info->reloc_mutex); > mutex_init(&fs_info->delalloc_root_mutex); > - mutex_init(&fs_info->cleaner_delayed_iput_mutex); > seqlock_init(&fs_info->profiles_lock); > > INIT_LIST_HEAD(&fs_info->dirty_cowonly_roots); > @@ -2673,6 +2670,7 @@ int open_ctree(struct super_block *sb, > atomic_set(&fs_info->defrag_running, 0); > atomic_set(&fs_info->qgroup_op_seq, 0); > atomic_set(&fs_info->reada_works_cnt, 0); > + atomic_set(&fs_info->nr_delayed_iputs, 0); > atomic64_set(&fs_info->tree_mod_seq, 0); > fs_info->sb = sb; > fs_info->max_inline = BTRFS_DEFAULT_MAX_INLINE; > @@ -2750,6 +2748,7 @@ int open_ctree(struct super_block *sb, > init_waitqueue_head(&fs_info->transaction_wait); > init_waitqueue_head(&fs_info->transaction_blocked_wait); > init_waitqueue_head(&fs_info->async_submit_wait); > + init_waitqueue_head(&fs_info->delayed_iputs_wait); > > INIT_LIST_HEAD(&fs_info->pinned_chunks); > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > index 3a90dc1d6b31..36f43876be22 100644 > --- a/fs/btrfs/extent-tree.c > +++ b/fs/btrfs/extent-tree.c > @@ -4272,8 +4272,9 @@ int btrfs_alloc_data_chunk_ondemand(struct btrfs_inode *inode, u64 bytes) > * operations. Wait for it to finish so that > * more space is released. > */ > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > + ret = btrfs_wait_on_delayed_iputs(fs_info); > + if (ret) > + return ret; > goto again; > } else { > btrfs_end_transaction(trans); > @@ -4838,9 +4839,9 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info, > * pinned space, so make sure we run the iputs before we do our pinned > * bytes check below. > */ > - mutex_lock(&fs_info->cleaner_delayed_iput_mutex); > btrfs_run_delayed_iputs(fs_info); > - mutex_unlock(&fs_info->cleaner_delayed_iput_mutex); > + wait_event(fs_info->delayed_iputs_wait, > + atomic_read(&fs_info->nr_delayed_iputs) == 0); Why open code btrfs_wait_on_delayed_iputs(fs_info)? Just make it use wait_event instead of the killable version and use the function uniformally across the code base. > > trans = btrfs_join_transaction(fs_info->extent_root); > if (IS_ERR(trans)) > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 3c42d8887183..57bf514a90eb 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -3260,6 +3260,7 @@ void btrfs_add_delayed_iput(struct inode *inode) > if (atomic_add_unless(&inode->i_count, -1, 1)) > return; > > + atomic_inc(&fs_info->nr_delayed_iputs); > spin_lock(&fs_info->delayed_iput_lock); > ASSERT(list_empty(&binode->delayed_iput)); > list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs); > @@ -3279,11 +3280,31 @@ void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info) > list_del_init(&inode->delayed_iput); > spin_unlock(&fs_info->delayed_iput_lock); > iput(&inode->vfs_inode); > + if (atomic_dec_and_test(&fs_info->nr_delayed_iputs)) > + wake_up(&fs_info->delayed_iputs_wait); > spin_lock(&fs_info->delayed_iput_lock); > } > spin_unlock(&fs_info->delayed_iput_lock); > } > > +/** > + * btrfs_wait_on_delayed_iputs - wait on the delayed iputs to be done running > + * @fs_info - the fs_info for this fs > + * @return - EINTR if we were killed, 0 if nothing's pending > + * > + * This will wait on any delayed iputs that are currently running with KILLABLE > + * set. Once they are all done running we will return, unless we are killed in > + * which case we return EINTR. > + */ > +int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info) > +{ > + int ret = wait_event_killable(fs_info->delayed_iputs_wait, > + atomic_read(&fs_info->nr_delayed_iputs) == 0); > + if (ret) > + return -EINTR; > + return 0; > +} > + > /* > * This creates an orphan entry for the given inode in case something goes wrong > * in the middle of an unlink. >