When dquot has space already allocated in a quota file, we just
overwrite that place when writing dquot. So we don't need any protection
against other modifications of quota file as these keep dquot in place.
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/quota/quota_v2.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/fs/quota/quota_v2.c b/fs/quota/quota_v2.c
index 482733abe4ac..7a05b80f3b8c 100644
--- a/fs/quota/quota_v2.c
+++ b/fs/quota/quota_v2.c
@@ -300,12 +300,23 @@ static int v2_write_dquot(struct dquot *dquot)
{
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
int ret;
-
- down_write(&dqopt->dqio_sem);
+ bool alloc = false;
+
+ /*
+ * If space for dquot is already allocated, we don't need any
+ * protection as we'll only overwrite the place of dquot. We are
+ * still protected by concurrent writes of the same dquot by
+ * dquot->dq_lock.
+ */
+ if (!dquot->dq_off) {
+ alloc = true;
+ down_write(&dqopt->dqio_sem);
+ }
ret = qtree_write_dquot(
sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv,
dquot);
- up_write(&dqopt->dqio_sem);
+ if (alloc)
+ up_write(&dqopt->dqio_sem);
return ret;
}
--
2.12.3
