[PATCH] btrfs: add lockdep_assert_held to need_preemptive_reclaim

[Niels Dossche <dossche.niels@gmail.com>]

In a previous patch I extended the locking for member accesses of
space_info. It was then suggested to also add a lockdep assertion for
space_info->lock to need_preemptive_reclaim.

Suggested-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Niels Dossche <dossche.niels@gmail.com>
---
 fs/btrfs/space-info.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c
index 294242c194d8..5464bd168d5b 100644
--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -734,9 +734,13 @@ static bool need_preemptive_reclaim(struct btrfs_fs_info *fs_info,
 {
 	u64 global_rsv_size = fs_info->global_block_rsv.reserved;
 	u64 ordered, delalloc;
-	u64 thresh = div_factor_fine(space_info->total_bytes, 90);
+	u64 thresh;
 	u64 used;
 
+	lockdep_assert_held(&space_info->lock);
+
+	thresh = div_factor_fine(space_info->total_bytes, 90);
+
 	/* If we're just plain full then async reclaim just slows us down. */
 	if ((space_info->bytes_used + space_info->bytes_reserved +
 	     global_rsv_size) >= thresh)
-- 
2.35.1