linux-kernel - [PATCH 3.10 63/64] FS-Cache: Increase reference of parent after registering, netfs success

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Message-Id: <20160214222223.327361846@linuxfoundation.org>
Date:	Sun, 14 Feb 2016 14:23:35 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Kinglong Mee <kinglongmee@...il.com>,
	David Howells <dhowells@...hat.com>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 3.10 63/64] FS-Cache: Increase reference of parent after registering, netfs success

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kinglong Mee <kinglongmee@...il.com>

commit 86108c2e34a26e4bec3c6ddb23390bf8cedcf391 upstream.

If netfs exist, fscache should not increase the reference of parent's
usage and n_children, otherwise, never be decreased.

v2: thanks David's suggest,
 move increasing reference of parent if success
 use kmem_cache_free() freeing primary_index directly

v3: don't move "netfs->primary_index->parent = &fscache_fsdef_index;"

Signed-off-by: Kinglong Mee <kinglongmee@...il.com>
Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/fscache/netfs.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -45,9 +45,6 @@ int __fscache_register_netfs(struct fsca
 	netfs->primary_index->parent		= &fscache_fsdef_index;
 	netfs->primary_index->netfs_data	= netfs;
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
-
 	spin_lock_init(&netfs->primary_index->lock);
 	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
 
@@ -60,6 +57,9 @@ int __fscache_register_netfs(struct fsca
 			goto already_registered;
 	}
 
+	atomic_inc(&netfs->primary_index->parent->usage);
+	atomic_inc(&netfs->primary_index->parent->n_children);
+
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;
 
@@ -70,8 +70,7 @@ already_registered:
 	up_write(&fscache_addremove_sem);
 
 	if (ret < 0) {
-		netfs->primary_index->parent = NULL;
-		__fscache_cookie_put(netfs->primary_index);
+		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
 		netfs->primary_index = NULL;
 	}