initialize-fe_logical

   1 ext4: make sure ex.fe_logical is initialized
   2
   3 The lowest levels of mballoc set all of the fields of struct
   4 ext4_free_extent except for fe_logical, since they are just trying to
   5 find the requested free set of blocks, and the logical block hasn't
   6 been set yet.  This makes some static code checkers sad.  Set it to
   7 various different debug values, which would be useful when
   8 debugging mballoc if these values were to ever show up due to the
   9 parts of mballoc triyng to use ac->ac_b_ex.fe_logical before it is
  10 properly upper layers of mballoc failing to properly set, usually by
  11 ext4_mb_use_best_found().
  12
  13 Addresses-Coverity-Id: #139697
  14 Addresses-Coverity-Id: #139698
  15 Addresses-Coverity-Id: #139699
  16
  17 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  18
  19
  20 ---
  21  fs/ext4/mballoc.c | 4 +++-
  22  1 file changed, 3 insertions(+), 1 deletion(-)
  23
  24 diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
  25 index 04a5c75..0d42f63 100644
  26 --- a/fs/ext4/mballoc.c
  27 +++ b/fs/ext4/mballoc.c
  28 @@ -1808,6 +1808,7 @@ int ext4_mb_find_by_goal(struct ext4_allocation_context *ac,
  29         ext4_lock_group(ac->ac_sb, group);
  30         max = mb_find_extent(e4b, ac->ac_g_ex.fe_start,
  31                              ac->ac_g_ex.fe_len, &ex);
  32 +       ex.fe_logical = 0xDEADFA11; /* debug value */
  33
  34         if (max >= ac->ac_g_ex.fe_len && ac->ac_g_ex.fe_len == sbi->s_stripe) {
  35                 ext4_fsblk_t start;
  36 @@ -1936,7 +1937,7 @@ void ext4_mb_complex_scan_group(struct ext4_allocation_context *ac,
  37                          */
  38                         break;
  39                 }
  40 -
  41 +               ex.fe_logical = 0xDEADC0DE; /* debug value */
  42                 ext4_mb_measure_extent(ac, &ex, e4b);
  43
  44                 i += ex.fe_len;
  45 @@ -1977,6 +1978,7 @@ void ext4_mb_scan_aligned(struct ext4_allocation_context *ac,
  46                         max = mb_find_extent(e4b, i, sbi->s_stripe, &ex);
  47                         if (max >= sbi->s_stripe) {
  48                                 ac->ac_found++;
  49 +                               ex.fe_logical = 0xDEADF00D; /* debug value */
  50                                 ac->ac_b_ex = ex;
  51                                 ext4_mb_use_best_found(ac, e4b);
  52                                 break;