quota: Reduce contention on dq_data_lock
dq_data_lock is currently used to protect all modifications of quota
accounting information, consistency of quota accounting on the inode,
and dquot pointers from inode. As a result contention on the lock can be
pretty heavy.
Reduce the contention on the lock by protecting quota accounting
information by a new dquot->dq_dqb_lock and consistency of quota
accounting with inode usage by inode->i_lock.
This change reduces time to create 500000 files on ext4 on ramdisk by 50
different processes in separate directories by 6% when user quota is
turned on. When those 50 processes belong to 50 different users, the
improvement is about 9%.
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 78f3a86..c94b6ba 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -504,7 +504,7 @@
/* Update space and inode usage. Get also other information from
* global quota file so that we don't overwrite any changes there.
* We are */
- spin_lock(&dq_data_lock);
+ spin_lock(&dquot->dq_dqb_lock);
spacechange = dquot->dq_dqb.dqb_curspace -
OCFS2_DQUOT(dquot)->dq_origspace;
inodechange = dquot->dq_dqb.dqb_curinodes -
@@ -560,7 +560,7 @@
__clear_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
OCFS2_DQUOT(dquot)->dq_origspace = dquot->dq_dqb.dqb_curspace;
OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;
- spin_unlock(&dq_data_lock);
+ spin_unlock(&dquot->dq_dqb_lock);
err = ocfs2_qinfo_lock(info, freeing);
if (err < 0) {
mlog(ML_ERROR, "Failed to lock quota info, losing quota write"
@@ -924,10 +924,10 @@
/* In case user set some limits, sync dquot immediately to global
* quota file so that information propagates quicker */
- spin_lock(&dq_data_lock);
+ spin_lock(&dquot->dq_dqb_lock);
if (dquot->dq_flags & mask)
sync = 1;
- spin_unlock(&dq_data_lock);
+ spin_unlock(&dquot->dq_dqb_lock);
/* This is a slight hack but we can't afford getting global quota
* lock if we already have a transaction started. */
if (!sync || journal_current_handle()) {