Patch "gfs2: Use rhashtable walk interface in glock_hash_walk" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    gfs2: Use rhashtable walk interface in glock_hash_walk

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     gfs2-use-rhashtable-walk-interface-in-glock_hash_walk.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Jun 15 09:31:48 CEST 2017
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Tue, 23 May 2017 21:53:36 -0400
Subject: gfs2: Use rhashtable walk interface in glock_hash_walk

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);
 }
 
 /**


Patches currently in stable-queue which might be from herbert@gondor.apana.org.au are

queue-4.9/gfs2-use-rhashtable-walk-interface-in-glock_hash_walk.patch
queue-4.9/tipc-fix-tipc_sk_reinit-race-conditions.patch