diff options
| author | Jan Kara | 2017-06-08 15:00:20 +0200 |
|---|---|---|
| committer | Jan Kara | 2017-08-17 18:56:07 +0200 |
| commit | 62676838cb39f4e4f44dd697c4d5d4214bda8cb1 (patch) | |
| tree | 79460ae1e1a4703ab739915d6e821661d9493780 | |
| parent | bc8230ee8e2ba967af780cdaf2dcc0f8e5eb45ca (diff) | |
quota: Do more fine-grained locking in dquot_acquire()
We need dqio_sem held just for reading when calling ->read_dqblk() in
dquot_acquire(). Also dqio_sem is not needed when setting DQ_READ_B and
DQ_ACTIVE_B as concurrent reads and dquot activations are serialized by
dq_lock. So acquire and release dqio_sem closer to the place where it is
needed. This reduces lock hold time and will make locking changes
easier.
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/quota/dquot.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 29d447598642..21358f31923d 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -406,9 +406,11 @@ int dquot_acquire(struct dquot *dquot) struct quota_info *dqopt = sb_dqopt(dquot->dq_sb); mutex_lock(&dquot->dq_lock); - down_write(&dqopt->dqio_sem); - if (!test_bit(DQ_READ_B, &dquot->dq_flags)) + if (!test_bit(DQ_READ_B, &dquot->dq_flags)) { + down_read(&dqopt->dqio_sem); ret = dqopt->ops[dquot->dq_id.type]->read_dqblk(dquot); + up_read(&dqopt->dqio_sem); + } if (ret < 0) goto out_iolock; /* Make sure flags update is visible after dquot has been filled */ @@ -416,12 +418,14 @@ int dquot_acquire(struct dquot *dquot) set_bit(DQ_READ_B, &dquot->dq_flags); /* Instantiate dquot if needed */ if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) { + down_write(&dqopt->dqio_sem); ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot); /* Write the info if needed */ if (info_dirty(&dqopt->info[dquot->dq_id.type])) { ret2 = dqopt->ops[dquot->dq_id.type]->write_file_info( dquot->dq_sb, dquot->dq_id.type); } + up_write(&dqopt->dqio_sem); if (ret < 0) goto out_iolock; if (ret2 < 0) { @@ -436,7 +440,6 @@ int dquot_acquire(struct dquot *dquot) smp_mb__before_atomic(); set_bit(DQ_ACTIVE_B, &dquot->dq_flags); out_iolock: - up_write(&dqopt->dqio_sem); mutex_unlock(&dquot->dq_lock); return ret; } |