Linux shrinker compat

The Linux shrinker has gone through three API changes since 2.6.22.
Rather than force every caller to understand all three APIs this
change consolidates the compatibility code in to the mm-compat.h
header.  The caller then can then use a single spl provided
shrinker API which does the right thing for your kernel.

SPL_SHRINKER_CALLBACK_PROTO(shrinker_callback, cb, nr_to_scan, gfp_mask);
SPL_SHRINKER_DECLARE(shrinker_struct, shrinker_callback, seeks);
spl_register_shrinker(&shrinker_struct);
spl_unregister_shrinker(&&shrinker_struct);
spl_exec_shrinker(&shrinker_struct, nr_to_scan, gfp_mask);

diff --git a/include/linux/mm_compat.h b/include/linux/mm_compat.h
index 5c5198b90fdea03a2405f3abc12c4b8c8b375168..7e2f6b8a5805306bf7b3929eb5fed8a72b754c85 100644 (file)
--- a/include/linux/mm_compat.h
+++ b/include/linux/mm_compat.h
@@ -56,4 +56,50 @@ extern invalidate_inodes_t invalidate_inodes_fn;
 #define invalidate_inodes(sb)  invalidate_inodes_fn(sb)
 #endif /* HAVE_INVALIDATE_INODES */
 
+#ifdef HAVE_SET_SHRINKER
+typedef struct spl_shrinker {
+       struct shrinker *shrinker;
+       shrinker_t fn;
+       int seeks;
+} spl_shrinker_t;
+
+static inline void
+spl_register_shrinker(spl_shrinker_t *ss)
+{
+       ss->shrinker = set_shrinker(ss->seeks, ss->fn);
+}
+
+static inline void
+spl_unregister_shrinker(spl_shrinker_t *ss)
+{
+       remove_shrinker(ss->shrinker);
+}
+
+# define SPL_SHRINKER_DECLARE(s, x, y) \
+       static spl_shrinker_t s = { .shrinker = NULL, .fn = x, .seeks = y }
+# define SPL_SHRINKER_CALLBACK_PROTO(fn, x, y, z) \
+       static int fn(int y, unsigned int z)
+# define spl_exec_shrinker(ss, nr, gfp) \
+       ((spl_shrinker_t *)ss)->fn(nr, gfp)
+
+#else /* HAVE_SET_SHRINKER */
+
+# define spl_register_shrinker(x)      register_shrinker(x)
+# define spl_unregister_shrinker(x)    unregister_shrinker(x)
+# define SPL_SHRINKER_DECLARE(s, x, y) \
+       static struct shrinker s = { .shrink = x, .seeks = y }
+
+# ifdef HAVE_3ARGS_SHRINKER_CALLBACK
+#  define SPL_SHRINKER_CALLBACK_PROTO(fn, x, y, z) \
+       static int fn(struct shrinker *x, int y, unsigned int z)
+#  define spl_exec_shrinker(ss, nr, gfp) \
+       ((struct shrinker *)ss)->shrink(NULL, nr, gfp)
+# else /* HAVE_3ARGS_SHRINKER_CALLBACK */
+#  define SPL_SHRINKER_CALLBACK_PROTO(fn, x, y, z) \
+       static int fn(int y, unsigned int z)
+#  define spl_exec_shrinker(ss, nr, gfp) \
+       ((struct shrinker *)ss)->shrink(nr, gfp)
+# endif /* HAVE_3ARGS_SHRINKER_CALLBACK */
+#endif /* HAVE_SET_SHRINKER */
+
 #endif /* SPL_MM_COMPAT_H */

diff --git a/module/spl/spl-kmem.c b/module/spl/spl-kmem.c
index 2f533bdf619b6f4f815d3e606aeb6084fb03a118..87594bde933980c3005c032aa041a178275dbff4 100644 (file)
--- a/module/spl/spl-kmem.c
+++ b/module/spl/spl-kmem.c
@@ -819,21 +819,10 @@ struct rw_semaphore spl_kmem_cache_sem; /* Cache list lock */
 static int spl_cache_flush(spl_kmem_cache_t *skc,
                            spl_kmem_magazine_t *skm, int flush);
 
-#ifdef HAVE_SET_SHRINKER
-static struct shrinker *spl_kmem_cache_shrinker;
-#else
-# ifdef HAVE_3ARGS_SHRINKER_CALLBACK
-static int spl_kmem_cache_generic_shrinker(struct shrinker *shrinker_cb,
-    int nr_to_scan, unsigned int gfp_mask);
-# else
-static int spl_kmem_cache_generic_shrinker(
-    int nr_to_scan, unsigned int gfp_mask);
-# endif /* HAVE_3ARGS_SHRINKER_CALLBACK */
-static struct shrinker spl_kmem_cache_shrinker = {
-       .shrink = spl_kmem_cache_generic_shrinker,
-       .seeks = KMC_DEFAULT_SEEKS,
-};
-#endif /* HAVE_SET_SHRINKER */
+SPL_SHRINKER_CALLBACK_PROTO(spl_kmem_cache_generic_shrinker,
+       shrinker_cb, nr_to_scan, gfp_mask);
+SPL_SHRINKER_DECLARE(spl_kmem_cache_shrinker,
+       spl_kmem_cache_generic_shrinker, KMC_DEFAULT_SEEKS);
 
 static void *
 kv_alloc(spl_kmem_cache_t *skc, int size, int flags)
@@ -1859,14 +1848,8 @@ EXPORT_SYMBOL(spl_kmem_cache_free);
  * objects should be freed, because Solaris semantics are to free
  * all available objects we may free more objects than requested.
  */
-#ifdef HAVE_3ARGS_SHRINKER_CALLBACK
-static int
-spl_kmem_cache_generic_shrinker(struct shrinker *shrinker_cb,
-                               int nr_to_scan, unsigned int gfp_mask)
-#else
-static int
-spl_kmem_cache_generic_shrinker(int nr_to_scan, unsigned int gfp_mask)
-#endif /* HAVE_3ARGS_SHRINKER_CALLBACK */
+SPL_SHRINKER_CALLBACK_PROTO(spl_kmem_cache_generic_shrinker,
+    shrinker_cb, nr_to_scan, gfp_mask)
 {
        spl_kmem_cache_t *skc;
        int unused = 0;
@@ -1930,11 +1913,7 @@ EXPORT_SYMBOL(spl_kmem_cache_reap_now);
 void
 spl_kmem_reap(void)
 {
-#ifdef HAVE_3ARGS_SHRINKER_CALLBACK
-       spl_kmem_cache_generic_shrinker(NULL, KMC_REAP_CHUNK, GFP_KERNEL);
-#else
-       spl_kmem_cache_generic_shrinker(KMC_REAP_CHUNK, GFP_KERNEL);
-#endif /* HAVE_3ARGS_SHRINKER_CALLBACK */
+       spl_exec_shrinker(&spl_kmem_cache_shrinker, KMC_REAP_CHUNK, GFP_KERNEL);
 }
 EXPORT_SYMBOL(spl_kmem_reap);
 
@@ -2135,14 +2114,7 @@ spl_kmem_init(void)
        init_rwsem(&spl_kmem_cache_sem);
        INIT_LIST_HEAD(&spl_kmem_cache_list);
 
-#ifdef HAVE_SET_SHRINKER
-       spl_kmem_cache_shrinker = set_shrinker(KMC_DEFAULT_SEEKS,
-                                              spl_kmem_cache_generic_shrinker);
-       if (spl_kmem_cache_shrinker == NULL)
-               SRETURN(rc = -ENOMEM);
-#else
-       register_shrinker(&spl_kmem_cache_shrinker);
-#endif
+       spl_register_shrinker(&spl_kmem_cache_shrinker);
 
 #ifdef DEBUG_KMEM
        kmem_alloc_used_set(0);
@@ -2178,11 +2150,7 @@ spl_kmem_fini(void)
 #endif /* DEBUG_KMEM */
        SENTRY;
 
-#ifdef HAVE_SET_SHRINKER
-       remove_shrinker(spl_kmem_cache_shrinker);
-#else
-       unregister_shrinker(&spl_kmem_cache_shrinker);
-#endif
+       spl_unregister_shrinker(&spl_kmem_cache_shrinker);
 
        SEXIT;
 }