fix-wrong-size-computation-in-ext4_mb_normalize_request

   1 ext4: fix wrong size computation in ext4_mb_normalize_request()
   2
   3 From: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
   4
   5 As the member fe_len defined in struct ext4_free_extent is expressed as
   6 number of clusters, the variable "size" computation is wrong, we need to
   7 first translate fe_len to block number, then to bytes.
   8
   9 Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com>
  10 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  11 Reviewed-by: Lukas Czerner <lczerner@redhat.com>
  12 ---
  13  fs/ext4/mballoc.c | 5 +++--
  14  1 file changed, 3 insertions(+), 2 deletions(-)
  15
  16 diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
  17 index 18a1619..0e9466f 100644
  18 --- a/fs/ext4/mballoc.c
  19 +++ b/fs/ext4/mballoc.c
  20 @@ -3075,8 +3075,9 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac,
  21                                                         (23 - bsbits)) << 23;
  22                 size = 8 * 1024 * 1024;
  23         } else {
  24 -               start_off = (loff_t)ac->ac_o_ex.fe_logical << bsbits;
  25 -               size      = ac->ac_o_ex.fe_len << bsbits;
  26 +               start_off = (loff_t) ac->ac_o_ex.fe_logical << bsbits;
  27 +               size      = (loff_t) EXT4_C2B(EXT4_SB(ac->ac_sb),
  28 +                                             ac->ac_o_ex.fe_len) << bsbits;
  29         }
  30         size = size >> bsbits;
  31         start = start_off >> bsbits;