Re: [PATCH v2 2/3] btrfs: zoned: fix compressed writes

[Josef Bacik <josef@toxicpanda.com>]

On 5/18/21 11:40 AM, Johannes Thumshirn wrote:
> When multiple processes write data to the same block group on a compressed
> zoned filesystem, the underlying device could report I/O errors and data
> corruption is possible.
> 
> This happens because on a zoned file system, compressed data writes where
> sent to the device via a REQ_OP_WRITE instead of a REQ_OP_ZONE_APPEND
> operation. But with REQ_OP_WRITE and parallel submission it cannot be
> guaranteed that the data is always submitted aligned to the underlying
> zone's write pointer.
> 
> The change to using REQ_OP_ZONE_APPEND instead of REQ_OP_WRITE on a zoned
> filesystem is non intrusive on a regular file system or when submitting to
> a conventional zone on a zoned filesystem, as it is guarded by
> btrfs_use_zone_append.
> 
> Reported-by: David Sterba <dsterba@suse.com>
> Fixes: 9d294a685fbc ("btrfs: zoned: enable to mount ZONED incompat flag")
> Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

This one is causing panics with btrfs/027 with -o compress.  I bisected it to 
something else earlier, but it was still happening today and I bisected again 
and this is what popped out.  I also went the extra step to revert the patch as 
I have already fucked this up once, and the problem didn't re-occur with this 
patch reverted.  The panic looks like this

May 22 00:33:16 xfstests2 kernel: BTRFS critical (device dm-9): mapping failed 
logical 22429696 bio len 53248 len 49152
May 22 00:33:16 xfstests2 kernel: ------------[ cut here ]------------
May 22 00:33:16 xfstests2 kernel: kernel BUG at fs/btrfs/volumes.c:6643!
May 22 00:33:16 xfstests2 kernel: invalid opcode: 0000 [#1] SMP NOPTI
May 22 00:33:16 xfstests2 kernel: CPU: 1 PID: 2236088 Comm: kworker/u4:4 Not 
tainted 5.13.0-rc2+ #240
May 22 00:33:16 xfstests2 kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 
2009), BIOS 1.13.0-2.fc32 04/01/2014
May 22 00:33:16 xfstests2 kernel: Workqueue: btrfs-delalloc btrfs_work_helper
May 22 00:33:16 xfstests2 kernel: RIP: 0010:btrfs_map_bio.cold+0x58/0x5a
May 22 00:33:16 xfstests2 kernel: Code: 50 e8 6b 83 ff ff e8 5b 0d 88 ff 48 83 
c4 18 e9 94 8f 88 ff 48 8b 3c 24 4c 89 f1 4c 89 fa 48 c7 c6 f8 db 62 96 e8 47 83 
ff ff <0f> 0b 4c 89 e7 e8 52 1f 83 ff e9 03 98 88 ff 49 8b 7a 50 44 89 f2
May 22 00:33:16 xfstests2 kernel: RSP: 0018:ffffb310c1de7c88 EFLAGS: 00010282
May 22 00:33:16 xfstests2 kernel: RAX: 0000000000000055 RBX: 0000000000000000 
RCX: 0000000000000000
May 22 00:33:16 xfstests2 kernel: RDX: ffff9b9a7bd27540 RSI: ffff9b9a7bd18e10 
RDI: ffff9b9a7bd18e10
May 22 00:33:16 xfstests2 kernel: RBP: ffff9b9a482ad7f8 R08: 0000000000000000 
R09: 0000000000000000
May 22 00:33:16 xfstests2 kernel: R10: ffffb310c1de7a48 R11: ffffffff96973748 
R12: 0000000000000000
May 22 00:33:16 xfstests2 kernel: R13: ffff9b9a001e7300 R14: 000000000000d000 
R15: 0000000001564000
May 22 00:33:16 xfstests2 kernel: FS:  0000000000000000(0000) 
GS:ffff9b9a7bd00000(0000) knlGS:0000000000000000
May 22 00:33:16 xfstests2 kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
May 22 00:33:16 xfstests2 kernel: CR2: 00005621fe4566e0 CR3: 000000013943a005 
CR4: 0000000000370ee0
May 22 00:33:16 xfstests2 kernel: Call Trace:
May 22 00:33:16 xfstests2 kernel:  btrfs_submit_compressed_write+0x2d7/0x470
May 22 00:33:16 xfstests2 kernel:  submit_compressed_extents+0x364/0x420
May 22 00:33:16 xfstests2 kernel:  ? lock_acquire+0x15d/0x380
May 22 00:33:16 xfstests2 kernel:  ? lock_release+0x1cd/0x2a0
May 22 00:33:16 xfstests2 kernel:  ? submit_compressed_extents+0x420/0x420
May 22 00:33:16 xfstests2 kernel:  btrfs_work_helper+0x133/0x520
May 22 00:33:16 xfstests2 kernel:  process_one_work+0x26b/0x570
May 22 00:33:16 xfstests2 kernel:  worker_thread+0x55/0x3c0
May 22 00:33:16 xfstests2 kernel:  ? process_one_work+0x570/0x570
May 22 00:33:16 xfstests2 kernel:  kthread+0x134/0x150
May 22 00:33:16 xfstests2 kernel:  ? __kthread_bind_mask+0x60/0x60
May 22 00:33:16 xfstests2 kernel:  ret_from_fork+0x1f/0x30

Thanks,

Josef