FAILED: patch "[PATCH] FS-Cache: Don't override netfs's primary_index if registering" failed to apply to 3.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From b130ed5998e62879a66bad08931a2b5e832da95c Mon Sep 17 00:00:00 2001
From: Kinglong Mee <kinglongmee@gmail.com>
Date: Wed, 4 Nov 2015 15:20:24 +0000
Subject: [PATCH] FS-Cache: Don't override netfs's primary_index if registering
 failed

Only override netfs->primary_index when registering success.

Cc: stable@vger.kernel.org # v2.6.30+
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index 458cc968d9a0..9b28649df3a1 100644
--- a/fs/fscache/netfs.c
+++ b/fs/fscache/netfs.c
@@ -22,6 +22,7 @@ static LIST_HEAD(fscache_netfs_list);
 int __fscache_register_netfs(struct fscache_netfs *netfs)
 {
 	struct fscache_netfs *ptr;
+	struct fscache_cookie *cookie;
 	int ret;
 
 	_enter("{%s}", netfs->name);
@@ -29,26 +30,25 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 	INIT_LIST_HEAD(&netfs->link);
 
 	/* allocate a cookie for the primary index */
-	netfs->primary_index =
-		kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
+	cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
 
-	if (!netfs->primary_index) {
+	if (!cookie) {
 		_leave(" = -ENOMEM");
 		return -ENOMEM;
 	}
 
 	/* initialise the primary index cookie */
-	atomic_set(&netfs->primary_index->usage, 1);
-	atomic_set(&netfs->primary_index->n_children, 0);
-	atomic_set(&netfs->primary_index->n_active, 1);
+	atomic_set(&cookie->usage, 1);
+	atomic_set(&cookie->n_children, 0);
+	atomic_set(&cookie->n_active, 1);
 
-	netfs->primary_index->def		= &fscache_fsdef_netfs_def;
-	netfs->primary_index->parent		= &fscache_fsdef_index;
-	netfs->primary_index->netfs_data	= netfs;
-	netfs->primary_index->flags		= 1 << FSCACHE_COOKIE_ENABLED;
+	cookie->def		= &fscache_fsdef_netfs_def;
+	cookie->parent		= &fscache_fsdef_index;
+	cookie->netfs_data	= netfs;
+	cookie->flags		= 1 << FSCACHE_COOKIE_ENABLED;
 
-	spin_lock_init(&netfs->primary_index->lock);
-	INIT_HLIST_HEAD(&netfs->primary_index->backing_objects);
+	spin_lock_init(&cookie->lock);
+	INIT_HLIST_HEAD(&cookie->backing_objects);
 
 	/* check the netfs type is not already present */
 	down_write(&fscache_addremove_sem);
@@ -59,9 +59,10 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 			goto already_registered;
 	}
 
-	atomic_inc(&netfs->primary_index->parent->usage);
-	atomic_inc(&netfs->primary_index->parent->n_children);
+	atomic_inc(&cookie->parent->usage);
+	atomic_inc(&cookie->parent->n_children);
 
+	netfs->primary_index = cookie;
 	list_add(&netfs->link, &fscache_netfs_list);
 	ret = 0;
 
@@ -70,10 +71,8 @@ int __fscache_register_netfs(struct fscache_netfs *netfs)
 already_registered:
 	up_write(&fscache_addremove_sem);
 
-	if (ret < 0) {
-		kmem_cache_free(fscache_cookie_jar, netfs->primary_index);
-		netfs->primary_index = NULL;
-	}
+	if (ret < 0)
+		kmem_cache_free(fscache_cookie_jar, cookie);
 
 	_leave(" = %d", ret);
 	return ret;