[PATCH 4.9 013/108] gfs2: Use rhashtable walk interface in glock_hash_walk

Greg Kroah-Hartman
2017-06-15T17:57:32Z

From: Herbert Xu <herbert@gondor.apana.org.au>

[ Upstream commit 6a25478077d987edc5e2f880590a2bc5fcab4441 ]

The function glock_hash_walk walks the rhashtable by hand. This
is broken because if it catches the hash table in the middle of
a rehash, then it will miss entries.

This patch replaces the manual walk by using the rhashtable walk
interface.

Fixes: 88ffbf3e037e ("GFS2: Use resizable hash table for glocks")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/gfs2/glock.c | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)

--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -1425,26 +1425,32 @@ static struct shrinker glock_shrinker =
* @sdp: the filesystem
* @bucket: the bucket
*
+ * Note that the function can be called multiple times on the same
+ * object. So the user must ensure that the function can cope with
+ * that.
*/

static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
{
struct gfs2_glock *gl;
- struct rhash_head *pos;
- const struct bucket_table *tbl;
- int i;
-
- rcu_read_lock();
- tbl = rht_dereference_rcu(gl_hash_table.tbl, &gl_hash_table);
- for (i = 0; i < tbl->size; i++) {
- rht_for_each_entry_rcu(gl, pos, tbl, i, gl_node) {
+ struct rhashtable_iter iter;
+
+ rhashtable_walk_enter(&gl_hash_table, &iter);
+
+ do {
+ gl = ERR_PTR(rhashtable_walk_start(&iter));
+ if (gl)
+ continue;
+
+ while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl))
if ((gl->gl_name.ln_sbd == sdp) &&
lockref_get_not_dead(&gl->gl_lockref))
examiner(gl);
- }
- }
- rcu_read_unlock();
- cond_resched();
+
+ rhashtable_walk_stop(&iter);
+ } while (cond_resched(), gl == ERR_PTR(-EAGAIN));
+
+ rhashtable_walk_exit(&iter);
}

/**