Commit d9a75a60 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Be more careful with the quota sync generation 



The quota sync generation is only ever updated under sd_quota_sync_mutex
by gfs2_quota_sync(), but its current value is fetched ouside of that
mutex, so use WRITE_ONCE() and READ_ONCE() when accessing it without
holding that mutex.

Pass the current sync generation to do_sync() from its callers to ensure
that we're not recording the wrong generation when the syncing is
done.  Also, make sure that qd->qd_sync_gen only ever moves forward.

In gfs2_quota_sync(), only write the new sync generation when we know
that there are changes.  This eliminates the need for function
sd_changed(), which we will remove in the next commit.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent 8d89e068

fs/gfs2/quota.c

+19 −8
Original line number Diff line number Diff line
@@ -891,7 +891,8 @@ static int gfs2_adjust_quota(struct gfs2_sbd *sdp, loff_t loc, 
	return err;

}



static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)

static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda,

		   u64 sync_gen)

{

	struct gfs2_sbd *sdp = (*qda)->qd_sbd;

	struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
@@ -982,8 +983,13 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda) 
	gfs2_log_flush(ip->i_gl->gl_name.ln_sbd, ip->i_gl,

		       GFS2_LOG_HEAD_FLUSH_NORMAL | GFS2_LFC_DO_SYNC);

	if (!error) {

		for (x = 0; x < num_qd; x++)

			qda[x]->qd_sync_gen = sdp->sd_quota_sync_gen;

		for (x = 0; x < num_qd; x++) {

			qd = qda[x];

			spin_lock(&qd->qd_lockref.lock);

			if (qd->qd_sync_gen < sync_gen)

				qd->qd_sync_gen = sync_gen;

			spin_unlock(&qd->qd_lockref.lock);

		}

	}

	return error;

}
@@ -1177,7 +1183,9 @@ void gfs2_quota_unlock(struct gfs2_inode *ip) 
	}



	if (count) {

		do_sync(count, qda);

		u64 sync_gen = READ_ONCE(sdp->sd_quota_sync_gen);



		do_sync(count, qda, sync_gen);

		for (x = 0; x < count; x++)

			qd_unlock(qda[x]);

	}
@@ -1323,6 +1331,7 @@ int gfs2_quota_sync(struct super_block *sb, int type) 
	struct gfs2_sbd *sdp = sb->s_fs_info;

	struct gfs2_quota_data **qda;

	unsigned int max_qd = PAGE_SIZE / sizeof(struct gfs2_holder);

	u64 sync_gen;

	int error = 0;



	if (sb_rdonly(sdp->sd_vfs))
@@ -1335,7 +1344,7 @@ int gfs2_quota_sync(struct super_block *sb, int type) 
		return -ENOMEM;



	mutex_lock(&sdp->sd_quota_sync_mutex);

	sdp->sd_quota_sync_gen++;

	sync_gen = sdp->sd_quota_sync_gen + 1;



	do {

		struct gfs2_quota_data *iter;
@@ -1344,7 +1353,7 @@ int gfs2_quota_sync(struct super_block *sb, int type) 


		spin_lock(&qd_lock);

		list_for_each_entry(iter, &sdp->sd_quota_list, qd_list) {

			if (qd_grab_sync(sdp, iter, sdp->sd_quota_sync_gen)) {

			if (qd_grab_sync(sdp, iter, sync_gen)) {

				qda[num_qd++] = iter;

				if (num_qd == max_qd)

					break;
@@ -1365,8 +1374,10 @@ int gfs2_quota_sync(struct super_block *sb, int type) 
			break;

		}



		if (!error)

			error = do_sync(num_qd, qda);

		if (!error) {

			WRITE_ONCE(sdp->sd_quota_sync_gen, sync_gen);

			error = do_sync(num_qd, qda, sync_gen);

		}



		for (x = 0; x < num_qd; x++)

			qd_unlock(qda[x]);