quota: avoid unnecessary dqget()/dqput() calls

Avoid unnecessary dqget()/dqput() calls in __dquot_initialize(),
that will introduce global lock contention otherwise.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Signed-off-by: Niu Yawei <yawei.niu@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 14 insertions, 1 deletions

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 7f30bdc57d13..251771916069 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1402,7 +1402,7 @@ static int dquot_active(const struct inode *inode)
  */
 static void __dquot_initialize(struct inode *inode, int type)
 {
-        int cnt;
+        int cnt, init_needed = 0;
         struct dquot *got[MAXQUOTAS];
         struct super_block *sb = inode->i_sb;
         qsize_t rsv;
@@ -1418,6 +1418,15 @@ static void __dquot_initialize(struct inode *inode, int type)
                 got[cnt] = NULL;
                 if (type != -1 && cnt != type)
                         continue;
+                /*
+                 * The i_dquot should have been initialized in most cases,
+                 * we check it without locking here to avoid unnecessary
+                 * dqget()/dqput() calls.
+                 */
+                if (inode->i_dquot[cnt])
+                        continue;
+                init_needed = 1;
+
                 switch (cnt) {
                 case USRQUOTA:
                         qid = make_kqid_uid(inode->i_uid);
@@ -1429,6 +1438,10 @@ static void __dquot_initialize(struct inode *inode, int type)
                 got[cnt] = dqget(sb, qid);
         }
 
+        /* All required i_dquot has been initialized */
+        if (!init_needed)
+                return;
+
         down_write(&sb_dqopt(sb)->dqptr_sem);
         if (IS_NOQUOTA(inode))
                 goto out_err;