[PATCH 3.16.y-ckt 083/126] FS-Cache: Don't override netfs's primary_index if registering failed

[Luis Henriques]

3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me 
know.

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

From: Kinglong Mee <kinglong...@gmail.com>

commit b130ed5998e62879a66bad08931a2b5e832da95c upstream.

Only override netfs->primary_index when registering success.

Signed-off-by: Kinglong Mee <kinglong...@gmail.com>
Signed-off-by: David Howells <dhowe...@redhat.com>
Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Luis Henriques <luis.henriq...@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 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;
--
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