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Message-ID: <538541A3.2060102@gmail.com> Date: Wed, 28 May 2014 09:53:39 +0800 From: Niu Yawei <yawei.niu@...il.com> To: Christoph Hellwig <hch@...radead.org>, jack@...e.cz CC: linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org, yawei.niu@...el.com, andreas.dilger@...el.com, lai.siyao@...el.com Subject: [PATCH 2/3 v2] 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@...el.com> Signed-off-by: Niu Yawei <yawei.niu@...el.com> --- 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..dc6f711 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, dq_get = 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 case, + * we check it without locking here to avoid unnecessary + * dqget()/dqput() calls. */ + if (inode->i_dquot[cnt]) + continue; + dq_get = 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 (!dq_get) + return; + down_write(&sb_dqopt(sb)->dqptr_sem); if (IS_NOQUOTA(inode)) goto out_err; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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