Btrfs: Fix some data=ordered related data corruptions

Stress testing was showing data checksum errors, most of which were caused
by a lookup bug in the extent_map tree.  The tree was caching the last
pointer returned, and searches would check the last pointer first.

But, search callers also expect the search to return the very first
matching extent in the range, which wasn't always true with the last
pointer usage.

For now, the code to cache the last return value is just removed.  It is
easy to fix, but I think lookups are rare enough that it isn't required anymore.

This commit also replaces do_sync_mapping_range with a local copy of the
related functions.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 0 insertions, 9 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 71b1ac15535..8a502ee2f23 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -42,7 +42,6 @@ void extent_map_exit(void)
 void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
 {
 	tree->map.rb_node = NULL;
-	tree->last = NULL;
 	spin_lock_init(&tree->lock);
 }
 EXPORT_SYMBOL(extent_map_tree_init);
@@ -239,7 +238,6 @@ int add_extent_mapping(struct extent_map_tree *tree,
 		merge->in_tree = 0;
 		free_extent_map(merge);
 	}
-	tree->last = em;
 out:
 	return ret;
 }
@@ -273,10 +271,6 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 	u64 end = range_end(start, len);
 
 	BUG_ON(spin_trylock(&tree->lock));
-	em = tree->last;
-	if (em && end > em->start && start < extent_map_end(em))
-		goto found;
-
 	rb_node = __tree_search(&tree->map, start, &prev, &next);
 	if (!rb_node && prev) {
 		em = rb_entry(prev, struct extent_map, rb_node);
@@ -305,7 +299,6 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 
 found:
 	atomic_inc(&em->refs);
-	tree->last = em;
 out:
 	return em;
 }
@@ -327,8 +320,6 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 	BUG_ON(spin_trylock(&tree->lock));
 	rb_erase(&em->rb_node, &tree->map);
 	em->in_tree = 0;
-	if (tree->last == em)
-		tree->last = NULL;
 	return ret;
 }
 EXPORT_SYMBOL(remove_extent_mapping);