We weren't doing any of the accounting cleanup when we aborted
transactions.  Fix this by making cleanup_ref_head_accounting global and
calling it from the abort code, this fixes the issue where our
accounting was all wrong after the fs aborts.

The test generic/475 on a 2G VM can trigger the problems eg.:

  [ 8502.136957] WARNING: CPU: 0 PID: 11064 at fs/btrfs/extent-tree.c:5986 btrfs_free_block_grou +ps+0x3dc/0x410 [btrfs]
  [ 8502.148372] CPU: 0 PID: 11064 Comm: umount Not tainted 5.0.0-rc1-default+ #394
  [ 8502.150807] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.2-0-gf9626 +cc-prebuilt.qemu-project.org 04/01/2014
  [ 8502.154317] RIP: 0010:btrfs_free_block_groups+0x3dc/0x410 [btrfs]
  [ 8502.160623] RSP: 0018:ffffb1ab84b93de8 EFLAGS: 00010206
  [ 8502.161906] RAX: 0000000001000000 RBX: ffff9f34b1756400 RCX: 0000000000000000
  [ 8502.163448] RDX: 0000000000000002 RSI: 0000000000000001 RDI: ffff9f34b1755400
  [ 8502.164906] RBP: ffff9f34b7e8c000 R08: 0000000000000001 R09: 0000000000000000
  [ 8502.166716] R10: 0000000000000000 R11: 0000000000000001 R12: ffff9f34b7e8c108
  [ 8502.168498] R13: ffff9f34b7e8c158 R14: 0000000000000000 R15: dead000000000100
  [ 8502.170296] FS:  00007fb1cf15ffc0(0000) GS:ffff9f34bd400000(0000) knlGS:0000000000000000
  [ 8502.172439] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [ 8502.173669] CR2: 00007fb1ced507b0 CR3: 000000002f7a6000 CR4: 00000000000006f0
  [ 8502.175094] Call Trace:
  [ 8502.175759]  close_ctree+0x17f/0x350 [btrfs]
  [ 8502.176721]  generic_shutdown_super+0x64/0x100
  [ 8502.177702]  kill_anon_super+0x14/0x30
  [ 8502.178607]  btrfs_kill_super+0x12/0xa0 [btrfs]
  [ 8502.179602]  deactivate_locked_super+0x29/0x60
  [ 8502.180595]  cleanup_mnt+0x3b/0x70
  [ 8502.181406]  task_work_run+0x98/0xc0
  [ 8502.182255]  exit_to_usermode_loop+0x83/0x90
  [ 8502.183113]  do_syscall_64+0x15b/0x180
  [ 8502.183919]  entry_SYSCALL_64_after_hwframe+0x49/0xbe

Corresponding to

  release_global_block_rsv() {
  ...
  WARN_ON(fs_info->delayed_refs_rsv.reserved > 0);

CC: stable@vger.kernel.org
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add log dump ]
Signed-off-by: David Sterba <dsterba@suse.com>