[PATCH 2/5] quota: avoid unnecessary dqget()/dqput() calls
From: Niu Yawei <hidden>
Date: 2014-06-04 04:20:36
Also in:
linux-fsdevel
Subsystem:
diskquota, filesystems (vfs and infrastructure), the rest · Maintainers:
Jan Kara, Alexander Viro, Christian Brauner, Linus Torvalds
Avoid unnecessary dqget()/dqput() calls in __dquot_initialize(), that will introduce global lock contention otherwise. Signed-off-by: Lai Siyao <redacted> Signed-off-by: Niu Yawei <redacted> --- 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