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>
 struct btrfs_trans_handle;
 struct btrfs_transaction;
 struct btrfs_pending_snapshot;
+struct btrfs_delayed_ref_root;
 extern struct kmem_cache *btrfs_trans_handle_cachep;
 extern struct kmem_cache *btrfs_bit_radix_cachep;
 extern struct kmem_cache *btrfs_path_cachep;
                           unsigned long count);
 int btrfs_async_run_delayed_refs(struct btrfs_fs_info *fs_info,
                                 unsigned long count, u64 transid, int wait);
+void btrfs_cleanup_ref_head_accounting(struct btrfs_fs_info *fs_info,
+                                 struct btrfs_delayed_ref_root *delayed_refs,
+                                 struct btrfs_delayed_ref_head *head);
 int btrfs_lookup_data_extent(struct btrfs_fs_info *fs_info, u64 start, u64 len);
 int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
                             struct btrfs_fs_info *fs_info, u64 bytenr,
 
                if (pin_bytes)
                        btrfs_pin_extent(fs_info, head->bytenr,
                                         head->num_bytes, 1);
+               btrfs_cleanup_ref_head_accounting(fs_info, delayed_refs, head);
                btrfs_put_delayed_ref_head(head);
                cond_resched();
                spin_lock(&delayed_refs->lock);
 
        return ret ? ret : 1;
 }
 
-static void cleanup_ref_head_accounting(struct btrfs_trans_handle *trans,
-                                       struct btrfs_delayed_ref_head *head)
+void btrfs_cleanup_ref_head_accounting(struct btrfs_fs_info *fs_info,
+                                 struct btrfs_delayed_ref_root *delayed_refs,
+                                 struct btrfs_delayed_ref_head *head)
 {
-       struct btrfs_fs_info *fs_info = trans->fs_info;
-       struct btrfs_delayed_ref_root *delayed_refs =
-               &trans->transaction->delayed_refs;
        int nr_items = 1;       /* Dropping this ref head update. */
 
        if (head->total_ref_mod < 0) {
                }
        }
 
-       cleanup_ref_head_accounting(trans, head);
+       btrfs_cleanup_ref_head_accounting(fs_info, delayed_refs, head);
 
        trace_run_delayed_ref_head(fs_info, head, 0);
        btrfs_delayed_ref_unlock(head);
        if (head->must_insert_reserved)
                ret = 1;
 
-       cleanup_ref_head_accounting(trans, head);
+       btrfs_cleanup_ref_head_accounting(trans->fs_info, delayed_refs, head);
        mutex_unlock(&head->mutex);
        btrfs_put_delayed_ref_head(head);
        return ret;