[4.2.y-ckt stable] Patch "FS-Cache: Don't override netfs's primary_index if registering failed" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    FS-Cache: Don't override netfs's primary_index if registering failed

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt1.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 4320c52152e28dd95e05c896044fe38fe6bbecee Mon Sep 17 00:00:00 2001
From: Kinglong Mee <kinglongmee at gmail.com>
Date: Wed, 4 Nov 2015 15:20:24 +0000
Subject: FS-Cache: Don't override netfs's primary_index if registering failed

commit b130ed5998e62879a66bad08931a2b5e832da95c upstream.

Only override netfs->primary_index when registering success.

Signed-off-by: Kinglong Mee <kinglongmee at gmail.com>
Signed-off-by: David Howells <dhowells at redhat.com>
Signed-off-by: Al Viro <viro at zeniv.linux.org.uk>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/fscache/netfs.c | 35 +++++++++++++++++------------------
 1 file changed, 17 insertions(+), 18 deletions(-)

diff --git a/fs/fscache/netfs.c b/fs/fscache/netfs.c
index 458cc96..9b28649 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;
--
1.9.1