[PATCH 3/5] mballoc: add comments to ext4_mb_mark_free_simple()

[Coly Li <i@coly.li>]

This patch tries to add comments to make ext4_mb_mark_free_simple more
readable.

Signed-off-by: Coly Li <bosong.ly@taobao.com>
Cc: Alex Tomas <alex@clusterfs.com>
Cc: Theodore Tso <tytso@google.com>
---
  fs/ext4/mballoc.c |    7 ++++++-
  1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 458dce0..c5534f4 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -630,7 +630,12 @@ static int __mb_check_buddy(struct ext4_buddy *e4b, char *file,
  #define mb_check_buddy(e4b)
  #endif

-/* FIXME!! need more doc */
+/*
+ * Devide blocks started from @first with length @len into
+ * smaller chunks with power of 2 blocks.
+ * Clear the bits in bitmap which the blocks of the chunk(s) covered,
+ * then increase bb_counters[] for corresponded chunk size.
+ */
  static void ext4_mb_mark_free_simple(struct super_block *sb,
  				void *buddy, ext4_grpblk_t first, ext4_grpblk_t len,
  					struct ext4_group_info *grp)
-- 
1.7.3.4