From: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Date: Wed, 24 Oct 2018 20:24:02 +0800
Subject: btrfs: extent-tree: Detect bytes_pinned underflow earlier
Git-commit: e2907c1a6ae1842f9c1d5393bbe966c1ccfbc335
Patch-mainline: v5.0-rc1
References: bsc#1165949

Introduce a new wrapper update_bytes_pinned to replace open coded
bytes_pinned modifiers. Now the underflows of space_info::bytes_pinned
get detected and reported.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Acked-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/extent-tree.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -78,6 +78,7 @@ static inline void update_##name(struct
 }
 
 DECLARE_SPACE_INFO_UPDATE(bytes_may_use);
+DECLARE_SPACE_INFO_UPDATE(bytes_pinned);
 
 static int update_block_group(struct btrfs_trans_handle *trans,
 			      struct btrfs_fs_info *fs_info, u64 bytenr,
@@ -6309,7 +6310,7 @@ static int update_block_group(struct btr
 			old_val -= num_bytes;
 			btrfs_set_block_group_used(&cache->item, old_val);
 			cache->pinned += num_bytes;
-			cache->space_info->bytes_pinned += num_bytes;
+			update_bytes_pinned(cache->space_info, num_bytes);
 			cache->space_info->bytes_used -= num_bytes;
 			cache->space_info->disk_used -= num_bytes * factor;
 			spin_unlock(&cache->lock);
@@ -6386,7 +6387,7 @@ static int pin_down_extent(struct btrfs_
 	spin_lock(&cache->space_info->lock);
 	spin_lock(&cache->lock);
 	cache->pinned += num_bytes;
-	cache->space_info->bytes_pinned += num_bytes;
+	update_bytes_pinned(cache->space_info, num_bytes);
 	if (reserved) {
 		cache->reserved -= num_bytes;
 		cache->space_info->bytes_reserved -= num_bytes;
@@ -6760,7 +6761,7 @@ static int unpin_extent_range(struct btr
 		spin_lock(&space_info->lock);
 		spin_lock(&cache->lock);
 		cache->pinned -= len;
-		space_info->bytes_pinned -= len;
+		update_bytes_pinned(space_info, -len);
 
 		trace_btrfs_space_reservation(fs_info, "pinned",
 					      space_info->flags, len, 0);
@@ -10855,7 +10856,7 @@ void btrfs_delete_unused_bgs(struct btrf
 		spin_lock(&space_info->lock);
 		spin_lock(&block_group->lock);
 
-		space_info->bytes_pinned -= block_group->pinned;
+		update_bytes_pinned(space_info, -block_group->pinned);
 		space_info->bytes_readonly += block_group->pinned;
 		percpu_counter_add(&space_info->total_bytes_pinned,
 				   -block_group->pinned);