1 files changed, 32 insertions, 2 deletions

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 7c97b3301459..1fe82cfc1d93 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -35,6 +35,7 @@ void extent_map_exit(void)
 void extent_map_tree_init(struct extent_map_tree *tree)
 {
         tree->map = RB_ROOT;
+        INIT_LIST_HEAD(&tree->modified_extents);
         rwlock_init(&tree->lock);
 }
 
@@ -54,7 +55,9 @@ struct extent_map *alloc_extent_map(void)
         em->in_tree = 0;
         em->flags = 0;
         em->compress_type = BTRFS_COMPRESS_NONE;
+        em->generation = 0;
         atomic_set(&em->refs, 1);
+        INIT_LIST_HEAD(&em->list);
         return em;
 }
 
@@ -72,6 +75,7 @@ void free_extent_map(struct extent_map *em)
         WARN_ON(atomic_read(&em->refs) == 0);
         if (atomic_dec_and_test(&em->refs)) {
                 WARN_ON(em->in_tree);
+                WARN_ON(!list_empty(&em->list));
                 kmem_cache_free(extent_map_cache, em);
         }
 }
@@ -198,6 +202,12 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
                         em->block_len += merge->block_len;
                         em->block_start = merge->block_start;
                         merge->in_tree = 0;
+                        if (merge->generation > em->generation) {
+                                em->generation = merge->generation;
+                                list_move(&em->list, &tree->modified_extents);
+                        }
+
+                        list_del_init(&merge->list);
                         rb_erase(&merge->rb_node, &tree->map);
                         free_extent_map(merge);
                 }
@@ -211,11 +221,29 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
                 em->block_len += merge->len;
                 rb_erase(&merge->rb_node, &tree->map);
                 merge->in_tree = 0;
+                if (merge->generation > em->generation) {
+                        em->generation = merge->generation;
+                        list_move(&em->list, &tree->modified_extents);
+                }
+                list_del_init(&merge->list);
                 free_extent_map(merge);
         }
 }
 
-int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
+/**
+ * unpint_extent_cache - unpin an extent from the cache
+ * @tree:       tree to unpin the extent in
+ * @start:      logical offset in the file
+ * @len:        length of the extent
+ * @gen:        generation that this extent has been modified in
+ * @prealloc:   if this is set we need to clear the prealloc flag
+ *
+ * Called after an extent has been written to disk properly.  Set the generation
+ * to the generation that actually added the file item to the inode so we know
+ * we need to sync this extent when we call fsync().
+ */
+int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
+                       u64 gen)
 {
         int ret = 0;
         struct extent_map *em;
@@ -228,10 +256,11 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len)
         if (!em)
                 goto out;
 
+        list_move(&em->list, &tree->modified_extents);
+        em->generation = gen;
         clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 
         try_merge_map(tree, em);
-
         free_extent_map(em);
 out:
         write_unlock(&tree->lock);
@@ -358,6 +387,7 @@ int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 
         WARN_ON(test_bit(EXTENT_FLAG_PINNED, &em->flags));
         rb_erase(&em->rb_node, &tree->map);
+        list_del_init(&em->list);
         em->in_tree = 0;
         return ret;
 }