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 08058C433F5 for ; Thu, 6 Jan 2022 14:53:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231523AbiAFOxh (ORCPT ); Thu, 6 Jan 2022 09:53:37 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:39386 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231135AbiAFOxg (ORCPT ); Thu, 6 Jan 2022 09:53:36 -0500 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 8851B1F385; Thu, 6 Jan 2022 14:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1641480815; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=taRFPvVd7GTR1wgkj/SY0ycPXUzREP3LepPm2Rl3EB0=; b=wjAOBwp6CpsA3NMk/R3mfDaL8hX22f2h7aMeFyo5gJgNdNyYEZwwcjwvBU2xEKSV9AigvE Hmh6PiIqaJrEUj6+frTyiDJrhyrF0vG2u8YaEMwmrmSqG/bkpD2dcYdwAwuUhCFC/Vx2Dg ofHaO6dvhbER2xGa9Apd25ZvxXeH70Y= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1641480815; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=taRFPvVd7GTR1wgkj/SY0ycPXUzREP3LepPm2Rl3EB0=; b=FS/5VRk8Wrr3sKBzO+Zu7Ro7Y96DRr4BMtc7XvMKlmZQPcEJkPvXNJo2ygoJE/eYFuud6I IFO5lGF0YYoVcuBg== Received: from ds.suse.cz (ds.suse.cz [10.100.12.205]) by relay2.suse.de (Postfix) with ESMTP id 7F546A3B85; Thu, 6 Jan 2022 14:53:35 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 06204DA799; Thu, 6 Jan 2022 15:53:04 +0100 (CET) Date: Thu, 6 Jan 2022 15:53:04 +0100 From: David Sterba To: fdmanana@kernel.org Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH v3] btrfs: fix log tree cleanup after a transaction abort Message-ID: <20220106145304.GC14046@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, fdmanana@kernel.org, linux-btrfs@vger.kernel.org References: <3aae7c6728257c7ce2279d6660ee2797e5e34bbd.1641300250.git.fdmanana@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3aae7c6728257c7ce2279d6660ee2797e5e34bbd.1641300250.git.fdmanana@suse.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Jan 04, 2022 at 12:54:15PM +0000, fdmanana@kernel.org wrote: > From: Filipe Manana > > After the recent changes made by commit c2e39305299f01 ("btrfs: clear > extent buffer uptodate when we fail to write it") and its followup fix, > commit 651740a5024117 ("btrfs: check WRITE_ERR when trying to read an > extent buffer"), we can now end up not cleaning up space reservations of > log tree extent buffers after a transaction abort happens, as well as not > cleaning up still dirty extent buffers. > > This happens because if writeback for a log tree extent buffer failed, > than we have cleared the EXTENT_BUFFER_UPTODATE from the extent buffer > and we have also set the bit EXTENT_BUFFER_WRITE_ERR on it. Later on, > when trying to free the log tree with free_log_tree(), which iterates > over the tree, we can end up getting an -EIO error when trying to read > a node or a leaf, since read_extent_buffer_pages() returns -EIO if an > extent buffer does not have EXTENT_BUFFER_UPTODATE set and has the > EXTENT_BUFFER_WRITE_ERR bit set. Getting that -EIO means that we return > immediately as we can not iterate over the entire tree. > > In that case we never update the reserved space for an extent buffer in > the respective block group and space_info object, as well as for any other > extent buffers that we not yet iterated over. > > When this happens we get the following traces when unmounting the fs: > > [174957.284509] BTRFS: error (device dm-0) in cleanup_transaction:1913: errno=-5 IO failure > [174957.286497] BTRFS: error (device dm-0) in free_log_tree:3420: errno=-5 IO failure > [174957.399379] ------------[ cut here ]------------ > [174957.402497] WARNING: CPU: 2 PID: 3206883 at fs/btrfs/block-group.c:127 btrfs_put_block_group+0x77/0xb0 [btrfs] > [174957.407523] Modules linked in: btrfs overlay dm_zero (...) > [174957.424917] CPU: 2 PID: 3206883 Comm: umount Tainted: G W 5.16.0-rc5-btrfs-next-109 #1 > [174957.426689] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > [174957.428716] RIP: 0010:btrfs_put_block_group+0x77/0xb0 [btrfs] > [174957.429717] Code: 21 48 8b bd (...) > [174957.432867] RSP: 0018:ffffb70d41cffdd0 EFLAGS: 00010206 > [174957.433632] RAX: 0000000000000001 RBX: ffff8b09c3848000 RCX: ffff8b0758edd1c8 > [174957.434689] RDX: 0000000000000001 RSI: ffffffffc0b467e7 RDI: ffff8b0758edd000 > [174957.436068] RBP: ffff8b0758edd000 R08: 0000000000000000 R09: 0000000000000000 > [174957.437114] R10: 0000000000000246 R11: 0000000000000000 R12: ffff8b09c3848148 > [174957.438140] R13: ffff8b09c3848198 R14: ffff8b0758edd188 R15: dead000000000100 > [174957.439317] FS: 00007f328fb82800(0000) GS:ffff8b0a2d200000(0000) knlGS:0000000000000000 > [174957.440402] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [174957.441164] CR2: 00007fff13563e98 CR3: 0000000404f4e005 CR4: 0000000000370ee0 > [174957.442117] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [174957.443076] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [174957.443948] Call Trace: > [174957.444264] > [174957.444538] btrfs_free_block_groups+0x255/0x3c0 [btrfs] > [174957.445238] close_ctree+0x301/0x357 [btrfs] > [174957.445803] ? call_rcu+0x16c/0x290 > [174957.446250] generic_shutdown_super+0x74/0x120 > [174957.446832] kill_anon_super+0x14/0x30 > [174957.447305] btrfs_kill_super+0x12/0x20 [btrfs] > [174957.447890] deactivate_locked_super+0x31/0xa0 > [174957.448440] cleanup_mnt+0x147/0x1c0 > [174957.448888] task_work_run+0x5c/0xa0 > [174957.449336] exit_to_user_mode_prepare+0x1e5/0x1f0 > [174957.449934] syscall_exit_to_user_mode+0x16/0x40 > [174957.450512] do_syscall_64+0x48/0xc0 > [174957.450980] entry_SYSCALL_64_after_hwframe+0x44/0xae > [174957.451605] RIP: 0033:0x7f328fdc4a97 > [174957.452059] Code: 03 0c 00 f7 (...) > [174957.454320] RSP: 002b:00007fff13564ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 > [174957.455262] RAX: 0000000000000000 RBX: 00007f328feea264 RCX: 00007f328fdc4a97 > [174957.456131] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000560b8ae51dd0 > [174957.457118] RBP: 0000560b8ae51ba0 R08: 0000000000000000 R09: 00007fff13563c40 > [174957.458005] R10: 00007f328fe49fc0 R11: 0000000000000246 R12: 0000000000000000 > [174957.459113] R13: 0000560b8ae51dd0 R14: 0000560b8ae51cb0 R15: 0000000000000000 > [174957.460193] > [174957.460534] irq event stamp: 0 > [174957.461003] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [174957.461947] hardirqs last disabled at (0): [] copy_process+0x934/0x2040 > [174957.463147] softirqs last enabled at (0): [] copy_process+0x934/0x2040 > [174957.465116] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [174957.466323] ---[ end trace bc7ee0c490bce3af ]--- > [174957.467282] ------------[ cut here ]------------ > [174957.468184] WARNING: CPU: 2 PID: 3206883 at fs/btrfs/block-group.c:3976 btrfs_free_block_groups+0x330/0x3c0 [btrfs] > [174957.470066] Modules linked in: btrfs overlay dm_zero (...) > [174957.483137] CPU: 2 PID: 3206883 Comm: umount Tainted: G W 5.16.0-rc5-btrfs-next-109 #1 > [174957.484691] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > [174957.486853] RIP: 0010:btrfs_free_block_groups+0x330/0x3c0 [btrfs] > [174957.488050] Code: 00 00 00 ad de (...) > [174957.491479] RSP: 0018:ffffb70d41cffde0 EFLAGS: 00010206 > [174957.492520] RAX: ffff8b08d79310b0 RBX: ffff8b09c3848000 RCX: 0000000000000000 > [174957.493868] RDX: 0000000000000001 RSI: fffff443055ee600 RDI: ffffffffb1131846 > [174957.495183] RBP: ffff8b08d79310b0 R08: 0000000000000000 R09: 0000000000000000 > [174957.496580] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8b08d7931000 > [174957.498027] R13: ffff8b09c38492b0 R14: dead000000000122 R15: dead000000000100 > [174957.499438] FS: 00007f328fb82800(0000) GS:ffff8b0a2d200000(0000) knlGS:0000000000000000 > [174957.500990] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [174957.502117] CR2: 00007fff13563e98 CR3: 0000000404f4e005 CR4: 0000000000370ee0 > [174957.503513] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [174957.504864] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [174957.506167] Call Trace: > [174957.506654] > [174957.507047] close_ctree+0x301/0x357 [btrfs] > [174957.507867] ? call_rcu+0x16c/0x290 > [174957.508567] generic_shutdown_super+0x74/0x120 > [174957.509447] kill_anon_super+0x14/0x30 > [174957.510194] btrfs_kill_super+0x12/0x20 [btrfs] > [174957.511123] deactivate_locked_super+0x31/0xa0 > [174957.511976] cleanup_mnt+0x147/0x1c0 > [174957.512610] task_work_run+0x5c/0xa0 > [174957.513309] exit_to_user_mode_prepare+0x1e5/0x1f0 > [174957.514231] syscall_exit_to_user_mode+0x16/0x40 > [174957.515069] do_syscall_64+0x48/0xc0 > [174957.515718] entry_SYSCALL_64_after_hwframe+0x44/0xae > [174957.516688] RIP: 0033:0x7f328fdc4a97 > [174957.517413] Code: 03 0c 00 f7 d8 (...) > [174957.521052] RSP: 002b:00007fff13564ec8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6 > [174957.522514] RAX: 0000000000000000 RBX: 00007f328feea264 RCX: 00007f328fdc4a97 > [174957.523950] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000560b8ae51dd0 > [174957.525375] RBP: 0000560b8ae51ba0 R08: 0000000000000000 R09: 00007fff13563c40 > [174957.526763] R10: 00007f328fe49fc0 R11: 0000000000000246 R12: 0000000000000000 > [174957.528058] R13: 0000560b8ae51dd0 R14: 0000560b8ae51cb0 R15: 0000000000000000 > [174957.529404] > [174957.529843] irq event stamp: 0 > [174957.530256] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [174957.531061] hardirqs last disabled at (0): [] copy_process+0x934/0x2040 > [174957.532075] softirqs last enabled at (0): [] copy_process+0x934/0x2040 > [174957.533083] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [174957.533865] ---[ end trace bc7ee0c490bce3b0 ]--- > [174957.534452] BTRFS info (device dm-0): space_info 4 has 1070841856 free, is not full > [174957.535404] BTRFS info (device dm-0): space_info total=1073741824, used=2785280, pinned=0, reserved=49152, may_use=0, readonly=65536 zone_unusable=0 > [174957.537029] BTRFS info (device dm-0): global_block_rsv: size 0 reserved 0 > [174957.537859] BTRFS info (device dm-0): trans_block_rsv: size 0 reserved 0 > [174957.538697] BTRFS info (device dm-0): chunk_block_rsv: size 0 reserved 0 > [174957.539552] BTRFS info (device dm-0): delayed_block_rsv: size 0 reserved 0 > [174957.540403] BTRFS info (device dm-0): delayed_refs_rsv: size 0 reserved 0 > > This also means that in case we have log tree extent buffers that are > still dirty, we can end up not cleaning them up in case we find an > extent buffer with EXTENT_BUFFER_WRITE_ERR set on it, as in that case > we have no way for iterating over the rest of the tree. > > This issue is very often triggered with test cases generic/475 and > generic/648 from fstests. > > So instead of trying to iterate a log tree when freeing it after a > transaction abort, iterate over the io tree that tracks the ranges of the > log tree's extent buffers, and unaccount each extent buffer's range as > well as clear any extent buffers that are still dirty. Also because when > we trigger writeback of log tree extent buffers we clear their range from > the ->dirty_log_pages io tree, we need to make sure the range is kept but > with a different bit, so that we can find it if we ever run into a > transaction abort - so when triggering the writeback, instead of clearing > the range, convert it to the EXTENT_UPTODATE bit. > > As a final note, while the commits mentioned above make this issue easy to > trigger with tests that use the device mapper to simulate device errors, > the issue could happen before, it was just much less likely. For example > after writing an extent buffer of a log tree, it could be evicted from > memory due to memory pressure, and then later during transaction commit > while cleaning up the log tree through walk_log_tree() we get an -EIO when > trying to read the extent buffer from disk - resulting in cleanup of the > remaining log tree extent buffers not being made. > > Signed-off-by: Filipe Manana > --- > > V3: Renamed subject (was "btrfs: fix reserved space leak on log tree nodes after transaction abort"). > Reworked the patch to take into account that after writeback is triggered through log syncing, > the range of the extent buffers is removed from the log dirty pages io tree. That was making > the mentioned test cases still fail often (just a bit less often however). > Also take into account that if fail during the cleanup, we stopped iterating over the tree > and leaving some extent buffers not being cleaned up - this was actually often triggered by > generic/648. Added to misc-next, thanks.