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

   1 commit 1ea06bec78a128adc995ca32bd906a6c9bb9cf91
   2 Author: Niu Yawei <yawei.niu@gmail.com>
   3 Date:   Wed Jun 4 12:20:30 2014 +0800
   4
   5     quota: avoid unnecessary dqget()/dqput() calls
   6
   7     Avoid unnecessary dqget()/dqput() calls in __dquot_initialize(),
   8     that will introduce global lock contention otherwise.
   9
  10     Signed-off-by: Lai Siyao <lai.siyao@intel.com>
  11     Signed-off-by: Niu Yawei <yawei.niu@intel.com>
  12     Signed-off-by: Jan Kara <jack@suse.cz>
  13 Index: linux-2.6.32-431.5.1.el6/fs/quota/dquot.c
  14 ===================================================================
  15 --- linux-2.6.32-431.5.1.el6.orig/fs/quota/dquot.c
  16 +++ linux-2.6.32-431.5.1.el6/fs/quota/dquot.c
  17 @@ -1230,7 +1230,7 @@ static int info_bdq_free(struct dquot *d
  18  int dquot_initialize(struct inode *inode, int type)
  19  {
  20         unsigned int id = 0;
  21 -       int cnt, ret = 0;
  22 +       int cnt, ret = 0, init_needed = 0;
  23         struct dquot *got[MAXQUOTAS] = { NULL, NULL };
  24         struct super_block *sb = inode->i_sb;
  25         qsize_t rsv;
  26 @@ -1244,6 +1244,15 @@ int dquot_initialize(struct inode *inode
  27         for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  28                 if (type != -1 && cnt != type)
  29                         continue;
  30 +               /*
  31 +                * The i_dquot should have been initialized in most cases,
  32 +                * we check it without locking here to avoid unnecessary
  33 +                * dqget()/dqput() calls.
  34 +                */
  35 +               if (inode->i_dquot[cnt])
  36 +                       continue;
  37 +               init_needed = 1;
  38 +
  39                 switch (cnt) {
  40                 case USRQUOTA:
  41                         id = inode->i_uid;
  42 @@ -1255,6 +1264,10 @@ int dquot_initialize(struct inode *inode
  43                 got[cnt] = dqget(sb, id, cnt);
  44         }
  45
  46 +       /* All required i_dquot has been initialized */
  47 +       if (!init_needed)
  48 +               return 0;
  49 +
  50         spin_lock(&inode->i_lock);
  51         if (IS_NOQUOTA(inode))
  52                 goto out_err;
  53 @@ -1264,6 +1277,9 @@ int dquot_initialize(struct inode *inode
  54                 /* Avoid races with quotaoff() */
  55                 if (!sb_has_quota_active(sb, cnt))
  56                         continue;
  57 +               /* We could race with quotaon or dqget() could have failed */
  58 +               if (!got[cnt])
  59 +                       continue;
  60                 if (!inode->i_dquot[cnt]) {
  61                         inode->i_dquot[cnt] = got[cnt];
  62                         got[cnt] = NULL;