staging: zcache: enable zcache to be built/loaded as a module

Allow zcache to be built/loaded as a module.  Note runtime dependency
disallows loading if cleancache/frontswap lazy initialization patches
are not present.  Zsmalloc support has not yet been merged into zcache
but, once merged, could now easily be selected via a module_param.

If built-in (not built as a module), the original mechanism of enabling
via a kernel boot parameter is retained, but this should be considered
deprecated.

Note that module unload is explicitly not yet supported.

Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
[v1: Rebased with different order of patches]
[v2: Removed [CLEANCACHE|FRONTSWAP]_HAS_LAZY_INIT ifdef]
[v3: Rebased on top of ramster->zcache move]
[v4: Redid the Makefile]
[v5: s/ZCACHE2/ZCACHE/]
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: 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>

5 files changed, 55 insertions, 12 deletions

diff --git a/drivers/staging/zcache/Kconfig b/drivers/staging/zcache/Kconfig
index 05e87a1e5d93..2d7b2da3b9e0 100644
--- a/drivers/staging/zcache/Kconfig
+++ b/drivers/staging/zcache/Kconfig
@@ -1,5 +1,5 @@
 config ZCACHE
-        bool "Dynamic compression of swap pages and clean pagecache pages"
+        tristate "Dynamic compression of swap pages and clean pagecache pages"
         depends on CRYPTO=y && SWAP=y && CLEANCACHE && FRONTSWAP
         select CRYPTO_LZO
         default n
@@ -19,8 +19,8 @@ config ZCACHE_DEBUG
           how zcache is doing. You probably want to set this to 'N'.
 
 config RAMSTER
-        bool "Cross-machine RAM capacity sharing, aka peer-to-peer tmem"
-        depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE=y
+        tristate "Cross-machine RAM capacity sharing, aka peer-to-peer tmem"
+        depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE
         depends on NET
         # must ensure struct page is 8-byte aligned
         select HAVE_ALIGNED_STRUCT_PAGE if !64BIT
diff --git a/drivers/staging/zcache/tmem.c b/drivers/staging/zcache/tmem.c
index a2b7e03b6062..d7e51e4152eb 100644
--- a/drivers/staging/zcache/tmem.c
+++ b/drivers/staging/zcache/tmem.c
@@ -35,7 +35,8 @@
 #include <linux/list.h>
 #include <linux/spinlock.h>
 #include <linux/atomic.h>
-#ifdef CONFIG_RAMSTER
+#include <linux/export.h>
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
 #include <linux/delay.h>
 #endif
 
@@ -641,6 +642,7 @@ void *tmem_localify_get_pampd(struct tmem_pool *pool, struct tmem_oid *oidp,
         /* note, hashbucket remains locked */
         return pampd;
 }
+EXPORT_SYMBOL_GPL(tmem_localify_get_pampd);
 
 void tmem_localify_finish(struct tmem_obj *obj, uint32_t index,
                           void *pampd, void *saved_hb, bool delete)
@@ -658,6 +660,7 @@ void tmem_localify_finish(struct tmem_obj *obj, uint32_t index,
         }
         spin_unlock(&hb->lock);
 }
+EXPORT_SYMBOL_GPL(tmem_localify_finish);
 
 /*
  * For ramster only.  Helper function to support asynchronous tmem_get.
@@ -719,6 +722,7 @@ out:
         spin_unlock(&hb->lock);
         return ret;
 }
+EXPORT_SYMBOL_GPL(tmem_replace);
 #endif
 
 /*
diff --git a/drivers/staging/zcache/tmem.h b/drivers/staging/zcache/tmem.h
index adbe5a8f28aa..d128ce290f1f 100644
--- a/drivers/staging/zcache/tmem.h
+++ b/drivers/staging/zcache/tmem.h
@@ -126,7 +126,7 @@ static inline unsigned tmem_oid_hash(struct tmem_oid *oidp)
                                 TMEM_HASH_BUCKET_BITS);
 }
 
-#ifdef CONFIG_RAMSTER
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
 struct tmem_xhandle {
         uint8_t client_id;
         uint8_t xh_data_cksum;
@@ -171,7 +171,7 @@ struct tmem_obj {
         unsigned int objnode_tree_height;
         unsigned long objnode_count;
         long pampd_count;
-#ifdef CONFIG_RAMSTER
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
         /*
          * for current design of ramster, all pages belonging to
          * an object reside on the same remotenode and extra is
@@ -215,7 +215,7 @@ struct tmem_pamops {
                                 uint32_t);
         void (*free)(void *, struct tmem_pool *,
                                 struct tmem_oid *, uint32_t, bool);
-#ifdef CONFIG_RAMSTER
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
         void (*new_obj)(struct tmem_obj *);
         void (*free_obj)(struct tmem_pool *, struct tmem_obj *, bool);
         void *(*repatriate_preload)(void *, struct tmem_pool *,
@@ -247,7 +247,7 @@ extern int tmem_flush_page(struct tmem_pool *, struct tmem_oid *,
 extern int tmem_flush_object(struct tmem_pool *, struct tmem_oid *);
 extern int tmem_destroy_pool(struct tmem_pool *);
 extern void tmem_new_pool(struct tmem_pool *, uint32_t);
-#ifdef CONFIG_RAMSTER
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
 extern int tmem_replace(struct tmem_pool *, struct tmem_oid *, uint32_t index,
                         void *);
 extern void *tmem_localify_get_pampd(struct tmem_pool *, struct tmem_oid *,
diff --git a/drivers/staging/zcache/zcache-main.c b/drivers/staging/zcache/zcache-main.c
index 326c2ea17c38..522cb8e55142 100644
--- a/drivers/staging/zcache/zcache-main.c
+++ b/drivers/staging/zcache/zcache-main.c
@@ -37,8 +37,10 @@
 #include "debug.h"
 #ifdef CONFIG_RAMSTER
 static bool ramster_enabled __read_mostly;
+static int disable_frontswap_selfshrink;
 #else
 #define ramster_enabled false
+#define disable_frontswap_selfshrink 0
 #endif
 
 #ifndef __PG_WAS_ACTIVE
@@ -81,8 +83,12 @@ static char *namestr __read_mostly = "zcache";
         (__GFP_FS | __GFP_NORETRY | __GFP_NOWARN | __GFP_NOMEMALLOC)
 
 /* crypto API for zcache  */
+#ifdef CONFIG_ZCACHE_MODULE
+static char *zcache_comp_name = "lzo";
+#else
 #define ZCACHE_COMP_NAME_SZ CRYPTO_MAX_ALG_NAME
 static char zcache_comp_name[ZCACHE_COMP_NAME_SZ] __read_mostly;
+#endif
 static struct crypto_comp * __percpu *zcache_comp_pcpu_tfms __read_mostly;
 
 enum comp_op {
@@ -1721,6 +1727,7 @@ struct frontswap_ops *zcache_frontswap_register_ops(void)
  * OR NOTHING HAPPENS!
  */
 
+#ifndef CONFIG_ZCACHE_MODULE
 static int __init enable_zcache(char *s)
 {
         zcache_enabled = true;
@@ -1787,18 +1794,27 @@ static int __init enable_zcache_compressor(char *s)
         return 1;
 }
 __setup("zcache=", enable_zcache_compressor);
+#endif
 
 
-static int __init zcache_comp_init(void)
+static int zcache_comp_init(void)
 {
         int ret = 0;
 
         /* check crypto algorithm */
+#ifdef CONFIG_ZCACHE_MODULE
+        ret = crypto_has_comp(zcache_comp_name, 0, 0);
+        if (!ret) {
+                ret = -1;
+                goto out;
+        }
+#else
         if (*zcache_comp_name != '\0') {
                 ret = crypto_has_comp(zcache_comp_name, 0, 0);
                 if (!ret)
                         pr_info("zcache: %s not supported\n",
                                         zcache_comp_name);
+                goto out;
         }
         if (!ret)
                 strcpy(zcache_comp_name, "lzo");
@@ -1807,6 +1823,7 @@ static int __init zcache_comp_init(void)
                 ret = 1;
                 goto out;
         }
+#endif
         pr_info("zcache: using %s compressor\n", zcache_comp_name);
 
         /* alloc percpu transforms */
@@ -1818,10 +1835,13 @@ out:
         return ret;
 }
 
-static int __init zcache_init(void)
+static int zcache_init(void)
 {
         int ret = 0;
 
+#ifdef CONFIG_ZCACHE_MODULE
+        zcache_enabled = 1;
+#endif
         if (ramster_enabled) {
                 namestr = "ramster";
                 ramster_register_pamops(&zcache_pamops);
@@ -1894,9 +1914,28 @@ static int __init zcache_init(void)
         }
         if (ramster_enabled)
                 ramster_init(!disable_cleancache, !disable_frontswap,
-                                frontswap_has_exclusive_gets, false);
+                                frontswap_has_exclusive_gets,
+                                !disable_frontswap_selfshrink);
 out:
         return ret;
 }
 
+#ifdef CONFIG_ZCACHE_MODULE
+#ifdef CONFIG_RAMSTER
+module_param(ramster_enabled, int, S_IRUGO);
+module_param(disable_frontswap_selfshrink, int, S_IRUGO);
+#endif
+module_param(disable_cleancache, int, S_IRUGO);
+module_param(disable_frontswap, int, S_IRUGO);
+#ifdef FRONTSWAP_HAS_EXCLUSIVE_GETS
+module_param(frontswap_has_exclusive_gets, bool, S_IRUGO);
+#endif
+module_param(disable_frontswap_ignore_nonactive, int, S_IRUGO);
+module_param(zcache_comp_name, charp, S_IRUGO);
+module_init(zcache_init);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Dan Magenheimer <dan.magenheimer@oracle.com>");
+MODULE_DESCRIPTION("In-kernel compression of cleancache/frontswap pages");
+#else
 late_initcall(zcache_init);
+#endif
diff --git a/drivers/staging/zcache/zcache.h b/drivers/staging/zcache/zcache.h
index 81722b33b087..849120095e79 100644
--- a/drivers/staging/zcache/zcache.h
+++ b/drivers/staging/zcache/zcache.h
@@ -39,7 +39,7 @@ extern int zcache_flush_page(int, int, struct tmem_oid *, uint32_t);
 extern int zcache_flush_object(int, int, struct tmem_oid *);
 extern void zcache_decompress_to_page(char *, unsigned int, struct page *);
 
-#ifdef CONFIG_RAMSTER
+#if defined(CONFIG_RAMSTER) || defined(CONFIG_RAMSTER_MODULE)
 extern void *zcache_pampd_create(char *, unsigned int, bool, int,
                                 struct tmem_handle *);
 int zcache_autocreate_pool(unsigned int cli_id, unsigned int pool_id, bool eph);