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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E43A9EEB56E for ; Fri, 8 Sep 2023 21:40:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343576AbjIHVkz (ORCPT ); Fri, 8 Sep 2023 17:40:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245363AbjIHVky (ORCPT ); Fri, 8 Sep 2023 17:40:54 -0400 Received: from wout5-smtp.messagingengine.com (wout5-smtp.messagingengine.com [64.147.123.21]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BED721FD9 for ; Fri, 8 Sep 2023 14:40:49 -0700 (PDT) Received: from compute5.internal (compute5.nyi.internal [10.202.2.45]) by mailout.west.internal (Postfix) with ESMTP id 512C03200684; Fri, 8 Sep 2023 17:40:46 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute5.internal (MEProxy); Fri, 08 Sep 2023 17:40:46 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bur.io; h=cc:cc :content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1694209245; x=1694295645; bh=Yh BC0ah4/DaL7x2ymEY1X+U7Yr8J2T4vBcFRl6cHrFc=; b=iNo0xElabItHG+taVz u5NPmPyZUB6d5ubyx41CHfY+Ns+NeKQnO98z8tKroLFTswtjNYCz9io5/rXjp6ib oVdud9YXPP2xYv4EG4kuKwn5YbGpTeevZVH9BflU+8jd2wkXKjyeGmdYdW4hdWj9 sNxRggfzdJvhX3d4wkkFof3aIU9OTjwjOiiNlW6ZN8C7kprwQhuMu98cevX1xXN7 vuyPStfsrcJTPJ/iaqUINe4pK8/qPGkWMM+dNk781YojpwYApBqS9fQtNq0Q9htE AY8i/cBCCfbmFufI6m3sSNmPsaDvAUgZrqkaHo5C/2ox09bEHpljmOEVi1ij6C8z gcvw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm1; t=1694209245; x=1694295645; bh=YhBC0ah4/DaL7 x2ymEY1X+U7Yr8J2T4vBcFRl6cHrFc=; b=aBqaP/C5ZeTE0r+pvAHC2elkC3de2 uk//gOaksiW2uIOi7V0Z7e9M/41XtaQzLdqogClQk78oGXhqSkf+zjZzIwK5yxyW 2rHk3N9BjZ/8QYffaPSnArg33YtcnyNXahovswAAs9WL9s6aHHx23n7h4Ma2A1hH 1ifYkOvYpwku9UHLyX3wMBnOdil6cDwFhviYO5i9J1QT1oj0LMwjnWZJMoWi7RIp zb06YbYmIVLbBlxLspMIjjpu7wUQ2bZ+98lyAa7ldg8BsRpb1l29dlr4pD/TF6Vu 7LZ32MVZC+Z5oXCdsJLYy49tsjMhmyYXpokOd51y3VHK8e7hi6lIcF2rA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrudehkedgtdduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehorhhi shcuuehurhhkohhvuceosghorhhishessghurhdrihhoqeenucggtffrrghtthgvrhhnpe ekvdekffejleelhfevhedvjeduhfejtdfhvdevieeiiedugfeugfdtjefgfeeljeenucev lhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegsohhrihhsse gsuhhrrdhioh X-ME-Proxy: Feedback-ID: i083147f8:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 8 Sep 2023 17:40:45 -0400 (EDT) Date: Fri, 8 Sep 2023 14:41:46 -0700 From: Boris Burkov To: David Sterba Cc: linux-btrfs@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH v5 15/18] btrfs: check generation when recording simple quota delta Message-ID: <20230908214146.GA172348@zen> References: <04ffbfcc145951c2f570312901b2c03c3c74e48e.1690495785.git.boris@bur.io> <20230907122449.GL3159@twin.jikos.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230907122449.GL3159@twin.jikos.cz> Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Sep 07, 2023 at 02:24:49PM +0200, David Sterba wrote: > On Thu, Jul 27, 2023 at 03:13:02PM -0700, Boris Burkov wrote: > > Simple quotas count extents only from the moment the feature is enabled. > > Therefore, if we do something like: > > 1. create subvol S > > 2. write F in S > > 3. enable quotas > > 4. remove F > > 5. write G in S > > > > then after 3. and 4. we would expect the simple quota usage of S to be 0 > > (putting aside some metadata extents that might be written) and after > > 5., it should be the size of G plus metadata. Therefore, we need to be > > able to determine whether a particular quota delta we are processing > > predates simple quota enablement. > > > > To do this, store the transaction id when quotas were enabled. In > > fs_info for immediate use and in the quota status item to make it > > recoverable on mount. When we see a delta, check if the generation of > > the extent item is less than that of quota enablement. If so, we should > > ignore the delta from this extent. > > > > Signed-off-by: Boris Burkov > > --- > > fs/btrfs/accessors.h | 2 ++ > > fs/btrfs/extent-tree.c | 4 ++++ > > fs/btrfs/fs.h | 2 ++ > > fs/btrfs/qgroup.c | 14 ++++++++++++-- > > fs/btrfs/qgroup.h | 1 + > > include/uapi/linux/btrfs_tree.h | 7 +++++++ > > 6 files changed, 28 insertions(+), 2 deletions(-) > > > > diff --git a/fs/btrfs/accessors.h b/fs/btrfs/accessors.h > > index a23045c05937..513f8edbd98e 100644 > > --- a/fs/btrfs/accessors.h > > +++ b/fs/btrfs/accessors.h > > @@ -970,6 +970,8 @@ BTRFS_SETGET_FUNCS(qgroup_status_flags, struct btrfs_qgroup_status_item, > > flags, 64); > > BTRFS_SETGET_FUNCS(qgroup_status_rescan, struct btrfs_qgroup_status_item, > > rescan, 64); > > +BTRFS_SETGET_FUNCS(qgroup_status_enable_gen, struct btrfs_qgroup_status_item, > > + enable_gen, 64); > > > > /* btrfs_qgroup_info_item */ > > BTRFS_SETGET_FUNCS(qgroup_info_generation, struct btrfs_qgroup_info_item, > > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c > > index 1b5efd03ef83..395ab46e520b 100644 > > --- a/fs/btrfs/extent-tree.c > > +++ b/fs/btrfs/extent-tree.c > > @@ -1513,6 +1513,7 @@ static int run_delayed_data_ref(struct btrfs_trans_handle *trans, > > .rsv_bytes = href->reserved_bytes, > > .is_data = true, > > .is_inc = true, > > + .generation = trans->transid, > > }; > > > > if (extent_op) > > @@ -1676,6 +1677,7 @@ static int run_delayed_tree_ref(struct btrfs_trans_handle *trans, > > .rsv_bytes = 0, > > .is_data = false, > > .is_inc = true, > > + .generation = trans->transid, > > }; > > > > BUG_ON(!extent_op || !extent_op->update_flags); > > @@ -3217,6 +3219,7 @@ static int __btrfs_free_extent(struct btrfs_trans_handle *trans, > > .rsv_bytes = 0, > > .is_data = is_data, > > .is_inc = false, > > + .generation = btrfs_extent_generation(leaf, ei), > > }; > > > > /* In this branch refs == 1 */ > > @@ -4850,6 +4853,7 @@ int btrfs_alloc_logged_file_extent(struct btrfs_trans_handle *trans, > > struct btrfs_simple_quota_delta delta = { > > .root = root_objectid, > > .num_bytes = ins->offset, > > + .generation = trans->transid, > > .rsv_bytes = 0, > > .is_data = true, > > .is_inc = true, > > diff --git a/fs/btrfs/fs.h b/fs/btrfs/fs.h > > index f76f450c2abf..da7b623ff15f 100644 > > --- a/fs/btrfs/fs.h > > +++ b/fs/btrfs/fs.h > > @@ -802,6 +802,8 @@ struct btrfs_fs_info { > > spinlock_t eb_leak_lock; > > struct list_head allocated_ebs; > > #endif > > + > > + u64 quota_enable_gen; > > Please move it to the other quota/qgroup related members, at the end of > fs_info there's only debugging stuff. > > > }; > > > > static inline void btrfs_set_last_root_drop_gen(struct btrfs_fs_info *fs_info, > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > > index 58e9ed0deedd..a8a603242431 100644 > > --- a/fs/btrfs/qgroup.c > > +++ b/fs/btrfs/qgroup.c > > @@ -454,6 +454,8 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info *fs_info) > > } > > fs_info->qgroup_flags = btrfs_qgroup_status_flags(l, ptr); > > simple = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_SIMPLE; > > + if (simple) > > + fs_info->quota_enable_gen = btrfs_qgroup_status_enable_gen(l, ptr); > > if (btrfs_qgroup_status_generation(l, ptr) != > > fs_info->generation && !simple) { > > qgroup_mark_inconsistent(fs_info); > > @@ -1107,10 +1109,12 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info, > > btrfs_set_qgroup_status_generation(leaf, ptr, trans->transid); > > btrfs_set_qgroup_status_version(leaf, ptr, BTRFS_QGROUP_STATUS_VERSION); > > fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON; > > - if (simple) > > + if (simple) { > > fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_SIMPLE; > > - else > > + btrfs_set_qgroup_status_enable_gen(leaf, ptr, trans->transid); > > + } else { > > fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT; > > + } > > btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags & > > BTRFS_QGROUP_STATUS_FLAGS_MASK); > > btrfs_set_qgroup_status_rescan(leaf, ptr, 0); > > @@ -1202,6 +1206,8 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info, > > goto out_free_path; > > } > > > > + fs_info->quota_enable_gen = trans->transid; > > + > > mutex_unlock(&fs_info->qgroup_ioctl_lock); > > /* > > * Commit the transaction while not holding qgroup_ioctl_lock, to avoid > > @@ -4622,6 +4628,10 @@ int btrfs_record_simple_quota_delta(struct btrfs_fs_info *fs_info, > > if (!is_fstree(root)) > > return 0; > > > > + /* If the extent predates enabling quotas, don't count it. */ > > + if (delta->generation < fs_info->quota_enable_gen) > > + return 0; > > + > > spin_lock(&fs_info->qgroup_lock); > > qgroup = find_qgroup_rb(fs_info, root); > > if (!qgroup) { > > diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h > > index ce6fa8694ca7..ae1ce14b365c 100644 > > --- a/fs/btrfs/qgroup.h > > +++ b/fs/btrfs/qgroup.h > > @@ -241,6 +241,7 @@ struct btrfs_simple_quota_delta { > > u64 rsv_bytes; /* The number of bytes reserved for this extent */ > > bool is_inc; /* Whether we are using or freeing the extent */ > > bool is_data; /* Whether the extent is data or metadata */ > > + u64 generation; /* The generation the extent was created in */ > > Please reorder it so it does not leave gaps between struct members. > > > }; > > > > static inline u64 btrfs_qgroup_subvolid(u64 qgroupid) > > diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h > > index eacb26caf3c6..1120ce3dae42 100644 > > --- a/include/uapi/linux/btrfs_tree.h > > +++ b/include/uapi/linux/btrfs_tree.h > > @@ -1242,6 +1242,13 @@ struct btrfs_qgroup_status_item { > > * of the scan. It contains a logical address > > */ > > __le64 rescan; > > + > > + /* > > + * the generation when quotas are enabled. Used by simple quotas to > > + * avoid decrementing when freeing an extent that was written before > > + * enable. > > + */ > > + __le64 enable_gen; > > This is public interface and btrfs_qgroup_status_item is used in many > places in user space at least in btrfs-progs. This needs a lot of > sanity checks. Totally agreed in principle, but not exactly sure how to proceed in practice. I would definitely appreciate some tips/help! How we interact with the new field: - When enabling squota, set it, the incompat bit, and the status flag - When reading in the qgroup status_item, if the status flag is set, then read the enable_gen. I believe this prevents us from ever reading garbage while trying to read an old fs (status flag won't be set) and it prevents any btrfs-progs from getting confused by a wrong-sized status item, since it would choke on the incompat bit first. Am I missing some other case? I can try to make it more explicitly zeroed when we enable qgroups but not squotas? I can add an ASSERT that the incompat bit is set as expected when we read the status item with the flag on (that seems good no matter what)? I can also write a wrapper for getting it which does the incompat/status flag checking to make it more clear that it isn't safe to read in general. Or a comment on the struct saying it depends on the incompat bit? Thanks for all the review, by the way. > > > } __attribute__ ((__packed__)); > > > > struct btrfs_qgroup_info_item { > > -- > > 2.41.0