ext4: Fixed inode allocator to correctly track a flex_bg's used_dirs

When used_dirs was introduced for the flex_groups struct, it looks
like the accounting was not put into place properly, in some places
manipulating free_inodes rather than used_dirs.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 361c0b9..57f6eef 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -263,7 +263,7 @@
 					ext4_group_t f;
 
 					f = ext4_flex_group(sbi, block_group);
-					atomic_dec(&sbi->s_flex_groups[f].free_inodes);
+					atomic_dec(&sbi->s_flex_groups[f].used_dirs);
 				}
 
 			}
@@ -773,7 +773,7 @@
 		if (sbi->s_log_groups_per_flex) {
 			ext4_group_t f = ext4_flex_group(sbi, group);
 
-			atomic_inc(&sbi->s_flex_groups[f].free_inodes);
+			atomic_inc(&sbi->s_flex_groups[f].used_dirs);
 		}
 	}
 	gdp->bg_checksum = ext4_group_desc_csum(sbi, group, gdp);