frontswap: make frontswap_init use a pointer for the ops

This simplifies the code in the frontswap - we can get rid of the
'backend_registered' test and instead check against frontswap_ops.

[v1: Rebase on top of 703ba7fe5e0 (ramster->zcache move]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Andor Daam <andor.daam@googlemail.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Florian Schmaus <fschmaus@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Stefan Hengelein <ilendir@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 7 insertions, 7 deletions

diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index e23d814b5392..09c69c8026f9 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -1707,9 +1707,9 @@ static struct frontswap_ops zcache_frontswap_ops = {
         .init = zcache_frontswap_init
 };
 
-struct frontswap_ops zcache_frontswap_register_ops(void)
+struct frontswap_ops *zcache_frontswap_register_ops(void)
 {
-        struct frontswap_ops old_ops =
+        struct frontswap_ops *old_ops =
                 frontswap_register_ops(&zcache_frontswap_ops);
 
         return old_ops;
@@ -1874,7 +1874,7 @@ static int __init zcache_init(void)
                         pr_warn("%s: cleancache_ops overridden\n", namestr);
         }
         if (zcache_enabled && !disable_frontswap) {
-                struct frontswap_ops old_ops;
+                struct frontswap_ops *old_ops;
 
                 old_ops = zcache_frontswap_register_ops();
                 if (frontswap_has_exclusive_gets)
@@ -1886,7 +1886,7 @@ static int __init zcache_init(void)
                         namestr, frontswap_has_exclusive_gets,
                         !disable_frontswap_ignore_nonactive);
 #endif
-                if (old_ops.init != NULL)
+                if (old_ops != NULL)
                         pr_warn("%s: frontswap_ops overridden\n", namestr);
         }
         if (ramster_enabled)
diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
index 3ee836d42581..7a01a5fd0f63 100644
--- a/drivers/xen/tmem.c
+++ b/drivers/xen/tmem.c
@@ -362,7 +362,7 @@ static int __init no_frontswap(char *s)
 }
 __setup("nofrontswap", no_frontswap);
 
-static struct frontswap_ops __initdata tmem_frontswap_ops = {
+static struct frontswap_ops tmem_frontswap_ops = {
         .store = tmem_frontswap_store,
         .load = tmem_frontswap_load,
         .invalidate_page = tmem_frontswap_flush_page,
@@ -378,11 +378,11 @@ static int __init xen_tmem_init(void)
 #ifdef CONFIG_FRONTSWAP
         if (tmem_enabled && use_frontswap) {
                 char *s = "";
-                struct frontswap_ops old_ops =
+                struct frontswap_ops *old_ops =
                         frontswap_register_ops(&tmem_frontswap_ops);
 
                 tmem_frontswap_poolid = -1;
-                if (old_ops.init != NULL)
+                if (old_ops)
                         s = " (WARNING: frontswap_ops overridden)";
                 printk(KERN_INFO "frontswap enabled, RAM provided by "
                                  "Xen Transcendent Memory%s\n", s);