[PATCH v7 1/2] btrfs: Fix metadata underflow caused by btrfs_reloc_clone_csum error

[Stefan Priebe - Profihost AG <s.priebe@profihost.ag>]

Hi Qu,

while V5 was running fine against the openSUSE-42.2 kernel (based on v4.4).

V7 results in OOPS to me:
BUG: unable to handle kernel NULL pointer dereference at 00000000000001f0
IP: [<ffffffffc03dde23>] __endio_write_update_ordered+0x33/0x140 [btrfs]
PGD 14e18d4067 PUD 14e1868067 PMD 0
Oops: 0000 [#1] SMP
Modules linked in: netconsole xt_multiport ipt_REJECT nf_reject_ipv4
xt_set iptable_filter ip_tables x_tables ip_set_hash_net ip_set
nfnetlink crc32_pclmul button loop btrfs xor usbhid raid6_pq ata_generic
virtio_blk virtio_net uhci_hcd ehci_hcd i2c_piix4 usbcore virtio_pci
i2c_core usb_common ata_piix floppy
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.4.52+112-ph #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.7.5-20140722_172050-sagunt 04/01/2014
task: ffffffffb4e0f500 ti: ffffffffb4e00000 task.ti: ffffffffb4e00000
RIP: 0010:[<ffffffffc03dde23>] [<ffffffffc03dde23>]
__endio_write_update_ordered+0x33/0x140 [btrfs]
RSP: 0018:ffff8814eae03cd8 EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffff8814e8fd5aa8 RCX: 0000000000000001
RDX: 0000000000100000 RSI: 0000000000100000 RDI: ffff8814e45885c0
RBP: ffff8814eae03d10 R08: ffff8814e8334000 R09: 000000018040003a
R10: ffffea00507d8d00 R11: ffff88141f634080 R12: ffff8814e45885c0
R13: ffff8814e125d700 R14: 0000000000100000 R15: ffff8800376c6a80
FS: 0000000000000000(0000) GS:ffff8814eae00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000001f0 CR3: 00000014e34c9000 CR4: 00000000001406f0Stack:
0000000000000000 0000000000100000 ffff8814e8fd5aa8 ffff8814e953f3c0
ffff8814e125d700 0000000000100000 ffff8800376c6a80 ffff8814eae03d38
ffffffffc03ddf67 ffff8814e86b6a80 ffff8814e8fd5aa8 0000000000000001
Call Trace:
[<ffffffffc03ddf67>] btrfs_endio_direct_write+0x37/0x60 [btrfs]
[<ffffffffb438f2f7>] bio_endio+0x57/0x60
[<ffffffffc04082c1>] btrfs_end_bio+0xa1/0x140 [btrfs]
[<ffffffffb438f2f7>] bio_endio+0x57/0x60
[<ffffffffb439763b>] blk_update_request+0x8b/0x330
[<ffffffffb43a05ba>] blk_mq_end_request+0x1a/0x70
[<ffffffffc039f30f>] virtblk_request_done+0x3f/0x70 [virtio_blk]
[<ffffffffb43a0688>] __blk_mq_complete_request+0x78/0xe0
[<ffffffffb43a070c>] blk_mq_complete_request+0x1c/0x20
[<ffffffffc039f184>] virtblk_done+0x64/0xe0 [virtio_blk]
[<ffffffffb446dd2a>] vring_interrupt+0x3a/0x90
[<ffffffffb40d3fe9>] __handle_irq_event_percpu+0x89/0x1b0
[<ffffffffb40d4133>] handle_irq_event_percpu+0x23/0x60
[<ffffffffb40d41ab>] handle_irq_event+0x3b/0x60
[<ffffffffb40d74ef>] handle_edge_irq+0x6f/0x150
[<ffffffffb4007cad>] handle_irq+0x1d/0x30
[<ffffffffb400750b>] do_IRQ+0x4b/0xd0
[<ffffffffb46af8cc>] common_interrupt+0x8c/0x8c
DWARF2 unwinder stuck at ret_from_intr+0x0/0x1b
Leftover inexact backtrace:
2017-03-12 20:33:08     <IRQ><EOI>
2017-03-12 20:33:08      [<ffffffffb404ba46>] ? native_safe_halt+0x6/0x10
[<ffffffffb400fa3e>] default_idle+0x1e/0xe0
[<ffffffffb401021f>] arch_cpu_idle+0xf/0x20
[<ffffffffb40c67eb>] default_idle_call+0x3b/0x40
[<ffffffffb40c6a8a>] cpu_startup_entry+0x29a/0x370
[<ffffffffb46a358c>] rest_init+0x7c/0x80
[<ffffffffb4f67fa5>] start_kernel+0x490/0x49d
[<ffffffffb4f67120>] ? early_idt_handler_array+0x120/0x120
[<ffffffffb4f674b3>] x86_64_start_reservations+0x2a/0x2c
[<ffffffffb4f675f0>] x86_64_start_kernel+0x13b/0x14a
Code: e5 41 57 41 56 41 55 41 54 49 89 fc 53 48 83 ec 10 48 8b 87 70 fc
ff ff 4c 8b 87 38 fe ff ff 48 c7 45 c8 00 00 00 00 48 89 75 d0 <48> 8b
b8 f0 01 00 00 48 3b 47 28 49 8b 84 24 78 fc ff ff 0f 84
RIP [<ffffffffc03dde23>] __endio_write_update_ordered+0x33/0x140 [btrfs]
RSP <ffff8814eae03cd8>
CR2: 00000000000001f0
---[ end trace 7529a0652fd7873e ]---
Kernel panic - not syncing: Fatal exception in interrupt
Kernel Offset: 0x33000000 from 0xffffffff81000000 (relocation range:
0xffffffff80000000-0xffffffffbfffffff)

Greets,
Stefan