An assertion triggered with four syscalls on fresh Btrfs image (xfstests reproducer)

[Anatoly Trosinenko]

An assertion can be triggered when performing operations on fresh,
non-crafted FS (bug #200413).

How to reproduce with kvm-xfstests:

1) Checkout master branch of torvalds/linux (tested on commit bab5c80b211)
2) Copy fstests/kernel-configs/x86_64-config-4.14 to .config and
compile after `make olddefconfig`
3) Take the attached repro.c and execute the following commands:

$ gcc --static repro.c -o repro # Inside /tmp/kvm-xfstest-$USER
$ kvm-xfstest shell

2) Inside the xfstests shell execute:

# mount /vtmp
# mkfs.btrfs /dev/vdc -O no-holes -b 256M -f
# mount /vdc
# cd /vdc
# /vtmp/repro

What happens:

root@kvm-xfstests:~# mount /vtmp
root@kvm-xfstests:~# mkfs.btrfs /dev/vdc -O no-holes -b 256M -f
btrfs-progs v4.13.3
See http://btrfs.wiki.kernel.org for more information.

Label:              (null)
UUID:               d3d0578c-4a7d-4604-a3ae-ccea8db13de3
Node size:          16384
Sector size:        4096
Filesystem size:    256.00MiB
Block group profiles:
  Data:             single            8.00MiB
  Metadata:         DUP              32.00MiB
  System:           DUP               8.00MiB
SSD detected:       no
Incompat features:  extref, skinny-metadata, no-holes
Number of devices:  1
Devices:
   ID        SIZE  PATH
    1   256.00MiB  /dev/vdc

[   21.994083] BTRFS: device fsid d3d0578c-4a7d-4604-a3ae-ccea8db13de3
devid 1 transid 5 /dev/vdc
root@kvm-xfstests:~# mount /vdc
[   41.484960] BTRFS info (device vdc): disk space caching is enabled
[   41.485697] BTRFS info (device vdc): has skinny extents
[   41.486289] BTRFS info (device vdc): flagging fs with big metadata feature
[   41.490678] BTRFS info (device vdc): creating UUID tree
root@kvm-xfstests:~# cd /vdc
root@kvm-xfstests:/vdc# /vtmp/repro
[   50.271476] assertion failed: len == i_size || (len ==
fs_info->sectorsize && btrfs_file_extent_compression(leaf, extent) !=
BTRFS_COMPRESS_NONE), file: fs/btrfs/tree-log.c, line: 4639
[   50.273424] ------------[ cut here ]------------
[   50.273895] kernel BUG at fs/btrfs/ctree.h:3438!
[   50.274366] invalid opcode: 0000 [#1] SMP PTI
[   50.274809] CPU: 1 PID: 389 Comm: repro Not tainted
4.19.0-rc7-xfstests-01009-gbab5c80b211 #1
[   50.275661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.10.2-1ubuntu1 04/01/2014
[   50.276560] RIP: 0010:btrfs_log_trailing_hole+0x253/0x2b0
[   50.277105] Code: 72 fd ff 84 c0 0f 85 1b fe ff ff b9 1f 12 00 00
48 c7 c2 f9 fc 22 be 48 c7 c6 70 fd 22 be 48 c7 c7 00 92 22 be e8 5f
65 c6 ff <0f> 0b b9 02 12 00 00 48 c7 c2 f9 fc 22 be 48 c7 c6 16 fd 22
be 48
[   50.278962] RSP: 0018:ffff9c8e0094fb70 EFLAGS: 00010282
[   50.279489] RAX: 00000000000000ac RBX: 0000000000000101 RCX: 0000000000000000
[   50.280206] RDX: 0000000000000000 RSI: ffff9907bddd54c8 RDI: ffff9907bddd54c8
[   50.280920] RBP: ffff9907b8aa2410 R08: 000000107a675b89 R09: 0000000000000000
[   50.281635] R10: 0000000000000003 R11: 0000000000000000 R12: 00000000000008da
[   50.282350] R13: 00000000000008da R14: ffff9907b8100000 R15: ffff9907b82b7700
[   50.283065] FS:  000000000163b880(0000) GS:ffff9907bdc00000(0000)
knlGS:0000000000000000
[   50.283873] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   50.284453] CR2: 000000000040dad0 CR3: 0000000079ebc001 CR4: 00000000003606e0
[   50.285173] Call Trace:
[   50.285425]  btrfs_log_inode+0xe64/0xf20
[   50.285851]  btrfs_log_inode_parent+0x295/0xb10
[   50.286301]  btrfs_log_dentry_safe+0x4a/0x70
[   50.286727]  btrfs_sync_file+0x43c/0x4e0
[   50.287119]  ? do_fsync+0x38/0x60
[   50.287477]  ? btrfs_fdatawrite_range+0x50/0x50
[   50.287945]  do_fsync+0x38/0x60
[   50.288300]  __x64_sys_fsync+0x10/0x20
[   50.288698]  do_syscall_64+0x56/0x1a0
[   50.289078]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[   50.289593] RIP: 0033:0x44a0d1
[   50.289911] Code: 0f 48 83 c4 28 c3 0f 1f 00 b8 00 01 00 00 eb e1
e8 54 1a 00 00 0f 1f 40 00 8b 05 46 27 27 00 85 c0 75 16 b8 4a 00 00
00 0f 05 <48> 3d 00 f0 ff ff 77 3f f3 c3 0f 1f 44 00 00 53 89 fb 48 83
ec 10
[   50.291771] RSP: 002b:00007ffe1c00b9b8 EFLAGS: 00000246 ORIG_RAX:
000000000000004a
[   50.292580] RAX: ffffffffffffffda RBX: 0000000000400400 RCX: 000000000044a0d1
[   50.293279] RDX: 000000000000046d RSI: 0000000000000000 RDI: 0000000000000003
[   50.294014] RBP: 00007ffe1c00b9d0 R08: 00000000006bbe18 R09: 0000000000000000
[   50.294713] R10: 000000000000046d R11: 0000000000000246 R12: 0000000000401920
[   50.295438] R13: 0000000000000000 R14: 00000000006b9018 R15: 0000000000000000
[   50.296211] ---[ end trace f1cccab515ece57c ]---
[   50.296687] RIP: 0010:btrfs_log_trailing_hole+0x253/0x2b0
[   50.297228] Code: 72 fd ff 84 c0 0f 85 1b fe ff ff b9 1f 12 00 00
48 c7 c2 f9 fc 22 be 48 c7 c6 70 fd 22 be 48 c7 c7 00 92 22 be e8 5f
65 c6 ff <0f> 0b b9 02 12 00 00 48 c7 c2 f9 fc 22 be 48 c7 c6 16 fd 22
be 48
[   50.299102] RSP: 0018:ffff9c8e0094fb70 EFLAGS: 00010282
[   50.299635] RAX: 00000000000000ac RBX: 0000000000000101 RCX: 0000000000000000
[   50.300358] RDX: 0000000000000000 RSI: ffff9907bddd54c8 RDI: ffff9907bddd54c8
[   50.301074] RBP: ffff9907b8aa2410 R08: 000000107a675b89 R09: 0000000000000000
[   50.301791] R10: 0000000000000003 R11: 0000000000000000 R12: 00000000000008da
[   50.302515] R13: 00000000000008da R14: ffff9907b8100000 R15: ffff9907b82b7700
[   50.303234] FS:  000000000163b880(0000) GS:ffff9907bdc00000(0000)
knlGS:0000000000000000
[   50.304049] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   50.304637] CR2: 000000000040dad0 CR3: 0000000079ebc001 CR4: 00000000003606e0
Segmentation fault
root@kvm-xfstests:/vdc#

Best regards
Anatoly
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main() {
  int fd = creat("./abc", 0x30);
  truncate("./abc", 350);
  fallocate(fd, 0, 1133, 1133);
  fsync(fd);
  return 0;
}