diff options
| author | Jan Kara <jack@suse.cz> | 2017-06-08 16:09:46 +0200 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2017-08-17 19:03:16 +0200 |
| commit | d2faa415166b2883428efa92f451774ef44373ac (patch) | |
| tree | 24e3f4fc0ef864c48f0751090937c09752657942 | |
| parent | 8fc32c2b0db2c9ee0dffebea65bcdea03a29ba5a (diff) | |
quota: Do not acquire dqio_sem for dquot overwrites in v2 format
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@dilger.ca>
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/quota/quota_v2.c | 17 |
1 files 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; } |