Message-ID: <20210823115638.GY5047@twin.jikos.cz>
Date:   Mon, 23 Aug 2021 13:56:38 +0200
From:   David Sterba <dsterba@...e.cz>
To:     Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>
Cc:     clm@...com, josef@...icpanda.com, dsterba@...e.com,
        linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org, gregkh@...uxfoundation.org,
        linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] btrfs: reset replace target device to allocation state
 on close

On Sat, Aug 21, 2021 at 01:50:40AM +0800, Desmond Cheong Zhi Xi wrote:
> This crash was observed with a failed assertion on device close:
> 
>   BTRFS: Transaction aborted (error -28)
>   WARNING: CPU: 1 PID: 3902 at fs/btrfs/extent-tree.c:2150 btrfs_run_delayed_refs+0x1d2/0x1e0 [btrfs]
>   Modules linked in: btrfs blake2b_generic libcrc32c crc32c_intel xor zstd_decompress zstd_compress xxhash lzo_compress lzo_decompress raid6_pq loop
>   CPU: 1 PID: 3902 Comm: kworker/u8:4 Not tainted 5.14.0-rc5-default+ #1532
>   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
>   Workqueue: events_unbound btrfs_async_reclaim_metadata_space [btrfs]
>   RIP: 0010:btrfs_run_delayed_refs+0x1d2/0x1e0 [btrfs]
>   RSP: 0018:ffffb7a5452d7d80 EFLAGS: 00010282
>   RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
>   RDX: 0000000000000001 RSI: ffffffffabee13c4 RDI: 00000000ffffffff
>   RBP: ffff97834176a378 R08: 0000000000000001 R09: 0000000000000001
>   R10: 0000000000000000 R11: 0000000000000001 R12: ffff97835195d388
>   R13: 0000000005b08000 R14: ffff978385484000 R15: 000000000000016c
>   FS:  0000000000000000(0000) GS:ffff9783bd800000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 000056190d003fe8 CR3: 000000002a81e005 CR4: 0000000000170ea0
>   Call Trace:
>    flush_space+0x197/0x2f0 [btrfs]
>    btrfs_async_reclaim_metadata_space+0x139/0x300 [btrfs]
>    process_one_work+0x262/0x5e0
>    worker_thread+0x4c/0x320
>    ? process_one_work+0x5e0/0x5e0
>    kthread+0x144/0x170
>    ? set_kthread_struct+0x40/0x40
>    ret_from_fork+0x1f/0x30
>   irq event stamp: 19334989
>   hardirqs last  enabled at (19334997): [<ffffffffab0e0c87>] console_unlock+0x2b7/0x400
>   hardirqs last disabled at (19335006): [<ffffffffab0e0d0d>] console_unlock+0x33d/0x400
>   softirqs last  enabled at (19334900): [<ffffffffaba0030d>] __do_softirq+0x30d/0x574
>   softirqs last disabled at (19334893): [<ffffffffab0721ec>] irq_exit_rcu+0x12c/0x140
>   ---[ end trace 45939e308e0dd3c7 ]---
>   BTRFS: error (device vdd) in btrfs_run_delayed_refs:2150: errno=-28 No space left
>   BTRFS info (device vdd): forced readonly
>   BTRFS warning (device vdd): failed setting block group ro: -30
>   BTRFS info (device vdd): suspending dev_replace for unmount
>   assertion failed: !test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state), in fs/btrfs/volumes.c:1150
>   ------------[ cut here ]------------
>   kernel BUG at fs/btrfs/ctree.h:3431!
>   invalid opcode: 0000 [#1] PREEMPT SMP
>   CPU: 1 PID: 3982 Comm: umount Tainted: G        W         5.14.0-rc5-default+ #1532
>   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
>   RIP: 0010:assertfail.constprop.0+0x18/0x1a [btrfs]
>   RSP: 0018:ffffb7a5454c7db8 EFLAGS: 00010246
>   RAX: 0000000000000068 RBX: ffff978364b91c00 RCX: 0000000000000000
>   RDX: 0000000000000000 RSI: ffffffffabee13c4 RDI: 00000000ffffffff
>   RBP: ffff9783523a4c00 R08: 0000000000000001 R09: 0000000000000001
>   R10: 0000000000000000 R11: 0000000000000001 R12: ffff9783523a4d18
>   R13: 0000000000000000 R14: 0000000000000004 R15: 0000000000000003
>   FS:  00007f61c8f42800(0000) GS:ffff9783bd800000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 000056190cffa810 CR3: 0000000030b96002 CR4: 0000000000170ea0
>   Call Trace:
>    btrfs_close_one_device.cold+0x11/0x55 [btrfs]
>    close_fs_devices+0x44/0xb0 [btrfs]
>    btrfs_close_devices+0x48/0x160 [btrfs]
>    generic_shutdown_super+0x69/0x100
>    kill_anon_super+0x14/0x30
>    btrfs_kill_super+0x12/0x20 [btrfs]
>    deactivate_locked_super+0x2c/0xa0
>    cleanup_mnt+0x144/0x1b0
>    task_work_run+0x59/0xa0
>    exit_to_user_mode_loop+0xe7/0xf0
>    exit_to_user_mode_prepare+0xaf/0xf0
>    syscall_exit_to_user_mode+0x19/0x50
>    do_syscall_64+0x4a/0x90
>    entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> This happens when close_ctree is called while a dev_replace hasn't
> completed. In close_ctree, we suspend the dev_replace, but keep the
> replace target around so that we can resume the dev_replace procedure
> when we mount the root again. This is the call trace:
> 
>   close_ctree():
>     btrfs_dev_replace_suspend_for_unmount();
>     btrfs_close_devices():
>       btrfs_close_fs_devices():
>         btrfs_close_one_device():
>           ASSERT(!test_bit(BTRFS_DEV_STATE_REPLACE_TGT,
>                  &device->dev_state));
> 
> However, since the replace target sticks around, there is a device
> with BTRFS_DEV_STATE_REPLACE_TGT set on close, and we fail the
> assertion in btrfs_close_one_device.
> 
> To fix this, if we come across the replace target device when
> closing, we should properly reset it back to allocation state. This
> fix also ensures that if a non-target device has a corrupted state and
> has the BTRFS_DEV_STATE_REPLACE_TGT bit set, the assertion will still
> catch the error.
> 
> Reported-by: David Sterba <dsterba@...e.com>
> Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@...il.com>

Thanks, added to misc-next.

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