From: Niu Yawei Subject: [PATCH 2/5] quota: avoid unnecessary dqget()/dqput() calls Date: Wed, 04 Jun 2014 12:20:30 +0800 Message-ID: <538E9E8E.4060903@gmail.com> References: <537DD5BA.1050105@gmail.com> <538464AD.6050407@gmail.com> <20140527101219.GA28035@infradead.org> <538541FE.3070203@gmail.com> <20140602083436.GC3224@quack.suse.cz> <538D9AB0.9090607@gmail.com> <20140603154301.GE30706@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, yawei.niu@intel.com, andreas.dilger@intel.com, lai.siyao@intel.com To: Jan Kara Return-path: In-Reply-To: <20140603154301.GE30706@quack.suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Avoid unnecessary dqget()/dqput() calls in __dquot_initialize(), that will introduce global lock contention otherwise. Signed-off-by: Lai Siyao Signed-off-by: Niu Yawei --- fs/quota/dquot.c | 13 ++++++++++++- 1 files changed, 12 insertions(+), 1 deletions(-) diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 9cd5f63..a00201d 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -1400,7 +1400,7 @@ 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; @@ -1416,6 +1416,13 @@ 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); @@ -1427,6 +1434,10 @@ 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; -- 1.7.1