Merge tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "Two regression fixes:

   - hangs caused by a missing barrier in the locking code

   - memory leaks of extent_state due to bad handling of a cached
     pointer"

* tag 'for-5.3-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: fix extent_state leak in btrfs_lock_and_flush_ordered_range
  btrfs: Fix deadlock caused by missing memory barrier

2 files changed, 12 insertions, 8 deletions

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 98fccce4208c..393eceda57c8 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -346,9 +346,12 @@ void btrfs_tree_unlock(struct extent_buffer *eb)
 	if (blockers) {
 		btrfs_assert_no_spinning_writers(eb);
 		eb->blocking_writers--;
-		/* Use the lighter barrier after atomic */
-		smp_mb__after_atomic();
-		cond_wake_up_nomb(&eb->write_lock_wq);
+		/*
+		 * We need to order modifying blocking_writers above with
+		 * actually waking up the sleepers to ensure they see the
+		 * updated value of blocking_writers
+		 */
+		cond_wake_up(&eb->write_lock_wq);
 	} else {
 		btrfs_assert_spinning_writers_put(eb);
 		write_unlock(&eb->lock);
diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 1744ba8b2754..ae7f64a8facb 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -985,13 +985,14 @@ void btrfs_lock_and_flush_ordered_range(struct extent_io_tree *tree,
 					struct extent_state **cached_state)
 {
 	struct btrfs_ordered_extent *ordered;
-	struct extent_state *cachedp = NULL;
+	struct extent_state *cache = NULL;
+	struct extent_state **cachedp = &cache;
 
 	if (cached_state)
-		cachedp = *cached_state;
+		cachedp = cached_state;
 
 	while (1) {
-		lock_extent_bits(tree, start, end, &cachedp);
+		lock_extent_bits(tree, start, end, cachedp);
 		ordered = btrfs_lookup_ordered_range(inode, start,
 						     end - start + 1);
 		if (!ordered) {
@@ -1001,10 +1002,10 @@ void btrfs_lock_and_flush_ordered_range(struct extent_io_tree *tree,
 			 * aren't exposing it outside of this function
 			 */
 			if (!cached_state)
-				refcount_dec(&cachedp->refs);
+				refcount_dec(&cache->refs);
 			break;
 		}
-		unlock_extent_cached(tree, start, end, &cachedp);
+		unlock_extent_cached(tree, start, end, cachedp);
 		btrfs_start_ordered_extent(&inode->vfs_inode, ordered, 1);
 		btrfs_put_ordered_extent(ordered);
 	}