ldiskfs/kernel_patches/patches/rhel8.7/ext4-mballoc-skip-uninit-groups-cr0.patch

   1 Index: kernel-4.18.0-423.el8/fs/ext4/mballoc.c
   2 ===================================================================
   3 --- kernel-4.18.0-423.el8.orig/fs/ext4/mballoc.c
   4 +++ kernel-4.18.0-423.el8/fs/ext4/mballoc.c
   5 @@ -1958,6 +1958,21 @@ int ext4_mb_find_by_goal(struct ext4_all
   6         return 0;
   7  }
   8
   9 +static inline int ext4_mb_uninit_on_disk(struct super_block *sb,
  10 +                                   ext4_group_t group)
  11 +{
  12 +       struct ext4_group_desc *desc;
  13 +
  14 +       if (!ext4_has_group_desc_csum(sb))
  15 +               return 0;
  16 +
  17 +       desc = ext4_get_group_desc(sb, group, NULL);
  18 +       if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT))
  19 +               return 1;
  20 +
  21 +       return 0;
  22 +}
  23 +
  24  /*
  25   * The routine scans buddy structures (not bitmap!) from given order
  26   * to max order and tries to find big enough chunk to satisfy the req
  27 @@ -2196,6 +2211,12 @@ static int ext4_mb_good_group_nolock(str
  28
  29         /* We only do this if the grp has never been initialized */
  30         if (unlikely(EXT4_MB_GRP_NEED_INIT(grp))) {
  31 +               /* cr=0/1 is a very optimistic search to find large
  32 +                * good chunks almost for free. if buddy data is
  33 +                * not ready, then this optimization makes no sense */
  34 +
  35 +               if (cr < 2 && !ext4_mb_uninit_on_disk(ac->ac_sb, group))
  36 +                       return 0;
  37                 ret = ext4_mb_init_group(ac->ac_sb, group, GFP_NOFS);
  38                 if (ret)
  39                         return ret;