lustre/kernel_patches/patches/quota-avoid-dqget-calls.patch

   1 In dquot_initialize(), we'd call dqget() only when i_dquot not
   2 initialized, which can avoid 2 pair of dqget()/dqput() in most
   3 case. It could relieve the global locks contenion caused by
   4 dqget()/dqput().
   5 Index: linux-2.6.32-358.0.1.el6/fs/quota/dquot.c
   6 ===================================================================
   7 --- linux-2.6.32-358.0.1.el6.orig/fs/quota/dquot.c
   8 +++ linux-2.6.32-358.0.1.el6/fs/quota/dquot.c
   9 @@ -1230,7 +1230,7 @@ static int info_bdq_free(struct dquot *d
  10  int dquot_initialize(struct inode *inode, int type)
  11  {
  12         unsigned int id = 0;
  13 -       int cnt, ret = 0;
  14 +       int cnt, ret = 0, dq_get = 0;
  15         struct dquot *got[MAXQUOTAS] = { NULL, NULL };
  16         struct super_block *sb = inode->i_sb;
  17         qsize_t rsv;
  18 @@ -1240,7 +1240,14 @@ int dquot_initialize(struct inode *inode
  19         if (IS_NOQUOTA(inode))
  20                 return 0;
  21
  22 -       /* First get references to structures we might need. */
  23 +       /* In most case, the i_dquot should have been initialized, except
  24 +        * the newly allocated one. We'd always try to skip the dqget() and
  25 +        * dqput() calls to avoid unnecessary global lock contention. */
  26 +       if (!(inode->i_state & I_NEW))
  27 +               goto init_idquot;
  28 +
  29 +get_dquots:
  30 +       dq_get = 1;
  31         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  32                 if (type != -1 && cnt != type)
  33                         continue;
  34 @@ -1254,7 +1261,7 @@ int dquot_initialize(struct inode *inode
  35                 }
  36                 got[cnt] = dqget(sb, id, cnt);
  37         }
  38 -
  39 +init_idquot:
  40         spin_lock(&inode->i_lock);
  41         if (IS_NOQUOTA(inode))
  42                 goto out_err;
  43 @@ -1265,6 +1272,10 @@ int dquot_initialize(struct inode *inode
  44                 if (!sb_has_quota_active(sb, cnt))
  45                         continue;
  46                 if (!inode->i_dquot[cnt]) {
  47 +                       if (dq_get == 0) {
  48 +                               spin_unlock(&inode->i_lock);
  49 +                               goto get_dquots;
  50 +                       }
  51                         inode->i_dquot[cnt] = got[cnt];
  52                         got[cnt] = NULL;
  53                         /*
  54 @@ -1272,7 +1283,7 @@ int dquot_initialize(struct inode *inode
  55                          * did a write before quota was turned on
  56                          */
  57                         rsv = inode_get_rsv_space(inode);
  58 -                       if (unlikely(rsv)) {
  59 +                       if (unlikely(rsv) && likely(inode->i_dquot[cnt])) {
  60                                 spin_lock(&dq_data_lock);
  61                                 dquot_resv_space(inode->i_dquot[cnt], rsv);
  62                                 spin_unlock(&dq_data_lock);