-In dquot_initialize(), we'd call dqget() only when i_dquot not
-initialized, which can avoid 2 pair of dqget()/dqput() in most
-case. It could relieve the global locks contenion caused by
-dqget()/dqput().
-Index: linux-2.6.32-358.0.1.el6/fs/quota/dquot.c
+commit 1ea06bec78a128adc995ca32bd906a6c9bb9cf91
+Author: Niu Yawei <yawei.niu@gmail.com>
+Date: Wed Jun 4 12:20:30 2014 +0800
+
+ 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>
+Index: linux-2.6.32-431.5.1.el6/fs/quota/dquot.c
===================================================================
---- linux-2.6.32-358.0.1.el6.orig/fs/quota/dquot.c
-+++ linux-2.6.32-358.0.1.el6/fs/quota/dquot.c
+--- linux-2.6.32-431.5.1.el6.orig/fs/quota/dquot.c
++++ linux-2.6.32-431.5.1.el6/fs/quota/dquot.c
@@ -1230,7 +1230,7 @@ static int info_bdq_free(struct dquot *d
int dquot_initialize(struct inode *inode, int type)
{
unsigned int id = 0;
- int cnt, ret = 0;
-+ int cnt, ret = 0, dq_get = 0;
++ int cnt, ret = 0, init_needed = 0;
struct dquot *got[MAXQUOTAS] = { NULL, NULL };
struct super_block *sb = inode->i_sb;
qsize_t rsv;
-@@ -1240,7 +1240,14 @@ int dquot_initialize(struct inode *inode
- if (IS_NOQUOTA(inode))
- return 0;
-
-- /* First get references to structures we might need. */
-+ /* In most case, the i_dquot should have been initialized, except
-+ * the newly allocated one. We'd always try to skip the dqget() and
-+ * dqput() calls to avoid unnecessary global lock contention. */
-+ if (!(inode->i_state & I_NEW))
-+ goto init_idquot;
-+
-+get_dquots:
-+ dq_get = 1;
+@@ -1244,6 +1244,15 @@ int dquot_initialize(struct inode *inode
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && cnt != type)
continue;
-@@ -1254,7 +1261,7 @@ int dquot_initialize(struct inode *inode
- }
++ /*
++ * 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:
+ id = inode->i_uid;
+@@ -1255,6 +1264,10 @@ int dquot_initialize(struct inode *inode
got[cnt] = dqget(sb, id, cnt);
}
--
-+init_idquot:
+
++ /* All required i_dquot has been initialized */
++ if (!init_needed)
++ return 0;
++
spin_lock(&inode->i_lock);
if (IS_NOQUOTA(inode))
goto out_err;
-@@ -1265,6 +1272,10 @@ int dquot_initialize(struct inode *inode
+@@ -1264,6 +1277,9 @@ int dquot_initialize(struct inode *inode
+ /* Avoid races with quotaoff() */
if (!sb_has_quota_active(sb, cnt))
continue;
++ /* We could race with quotaon or dqget() could have failed */
++ if (!got[cnt])
++ continue;
if (!inode->i_dquot[cnt]) {
-+ if (dq_get == 0) {
-+ spin_unlock(&inode->i_lock);
-+ goto get_dquots;
-+ }
inode->i_dquot[cnt] = got[cnt];
got[cnt] = NULL;
- /*
-@@ -1272,7 +1283,7 @@ int dquot_initialize(struct inode *inode
- * did a write before quota was turned on
- */
- rsv = inode_get_rsv_space(inode);
-- if (unlikely(rsv)) {
-+ if (unlikely(rsv) && likely(inode->i_dquot[cnt])) {
- spin_lock(&dq_data_lock);
- dquot_resv_space(inode->i_dquot[cnt], rsv);
- spin_unlock(&dq_data_lock);