btrfs: Set relative data on clear btrfs_block_group_cache->pinned

Bug1:
  space_info->bytes_readonly was set to very large(negative) value in
  btrfs_remove_block_group().

Reason:
  Current code set block_group_cache->pinned = 0 in btrfs_delete_unused_bgs(),
  but above space was not counted to space_info->bytes_readonly.

  Then in btrfs_remove_block_group():
    block_group->space_info->bytes_readonly -= block_group->key.offset;
  We can see following value in trace:
    btrfs_remove_block_group: pid=2677 comm=btrfs-cleaner WARNING: bytes_readonly=12582912, key.offset=134217728

Bug2:
  space_info->total_bytes_pinned grow to value larger than fs size.
  In a 1.2G fs, we can get following trace log:
  at first:
    ZL_DEBUG: add_pinned_bytes: pid=2710 comm=sync change total_bytes_pinned flags=1 869793792 + 95944704 = 965738496
  after some op:
    ZL_DEBUG: add_pinned_bytes: pid=2770 comm=sync change total_bytes_pinned flags=1 1780178944 + 95944704 = 1876123648
  after some op:
    ZL_DEBUG: add_pinned_bytes: pid=3193 comm=sync change total_bytes_pinned flags=1 2924568576 + 95551488 = 3020120064
  ...

Reason:
  Similar to bug1, we also need to adjust space_info->total_bytes_pinned
  in above code block.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 01f4db6554a1..7a14a4aa50a7 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -9922,8 +9922,18 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
                 mutex_unlock(&fs_info->unused_bg_unpin_mutex);
 
                 /* Reset pinned so btrfs_put_block_group doesn't complain */
+                spin_lock(&space_info->lock);
+                spin_lock(&block_group->lock);
+
+                space_info->bytes_pinned -= block_group->pinned;
+                space_info->bytes_readonly += block_group->pinned;
+                percpu_counter_add(&space_info->total_bytes_pinned,
+                                   -block_group->pinned);
                 block_group->pinned = 0;
 
+                spin_unlock(&block_group->lock);
+                spin_unlock(&space_info->lock);
+
                 /*
                  * Btrfs_remove_chunk will abort the transaction if things go
                  * horribly wrong.