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>

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 7f30bdc57d13be7a86bb2e06c20c0e78ea3aa056..251771916069d9af8f1b6e507487affe4f3f5e6e 100644 (file)
--- 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;