btrfs: fix string and comment grammatical issues and typos

Signed-off-by: Nicholas D Steeves <nsteeves@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/tests/free-space-tests.c b/fs/btrfs/tests/free-space-tests.c
index 5142475..0eeb8f3 100644
--- a/fs/btrfs/tests/free-space-tests.c
+++ b/fs/btrfs/tests/free-space-tests.c
@@ -25,7 +25,7 @@
 #define BITS_PER_BITMAP		(PAGE_SIZE * 8)
 
 /*
- * This test just does basic sanity checking, making sure we can add an exten
+ * This test just does basic sanity checking, making sure we can add an extent
  * entry and remove space from either end and the middle, and make sure we can
  * remove space that covers adjacent extent entries.
  */
@@ -396,8 +396,9 @@
  * wasn't optimal as they could be spread all over the block group while under
  * concurrency (extra overhead and fragmentation).
  *
- * This stealing approach is benefical, since we always prefer to allocate from
- * extent entries, both for clustered and non-clustered allocation requests.
+ * This stealing approach is beneficial, since we always prefer to allocate
+ * from extent entries, both for clustered and non-clustered allocation
+ * requests.
  */
 static int
 test_steal_space_from_bitmap_to_extent(struct btrfs_block_group_cache *cache)