-From c3d9c0df3ee8d43db22815ebbfbe8b803fa46e46 Mon Sep 17 00:00:00 2001
-From: Richard Yao <ryao@gentoo.org>
-Date: Tue, 5 Nov 2013 11:35:54 -0500
-Subject: [PATCH] Linux 3.12 compat: New shrinker API
-
-torvalds/linux@24f7c6 introduced a new shrinker API while
-torvalds/linux@a0b021 dropped support for the old shrinker API.
-This patch adds support for the new shrinker API by wrapping
-the old one with the new one.
-
-This change also reorganizes the autotools checks on the shrinker
-API such that the configure script will fail early if an unknown
-API is encountered in the future.
-
-Support for the set_shrinker() API which was used by Linux 2.6.22
-and older has been dropped. As a general rule compatibility is
-only maintained back to Linux 2.6.26.
-
-Signed-off-by: Richard Yao <ryao@gentoo.org>
-Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
-Closes zfsonlinux/zfs#1732
-Closes zfsonlinux/zfs#1822
-Closes #293
-Closes #307
----
- config/spl-build.m4 | 116 ++++++++++++++++++------
- include/linux/mm_compat.h | 226 +++++++++++++++++++++++++++++-----------------
- 2 files changed, 229 insertions(+), 113 deletions(-)
-
-diff --git a/config/spl-build.m4 b/config/spl-build.m4
-index b0e3348..7d744db 100644
---- a/config/spl-build.m4
-+++ b/config/spl-build.m4
-@@ -27,8 +27,7 @@ AC_DEFUN([SPL_AC_CONFIG_KERNEL], [
- SPL_AC_TYPE_ATOMIC64_XCHG
- SPL_AC_TYPE_UINTPTR_T
- SPL_AC_2ARGS_REGISTER_SYSCTL
-- SPL_AC_SET_SHRINKER
-- SPL_AC_3ARGS_SHRINKER_CALLBACK
-+ SPL_AC_SHRINKER_CALLBACK
- SPL_AC_PATH_IN_NAMEIDATA
- SPL_AC_TASK_CURR
- SPL_AC_CTL_UNNUMBERED
-@@ -885,37 +884,18 @@ AC_DEFUN([SPL_AC_2ARGS_REGISTER_SYSCTL],
- ])
- ])
-
--dnl #
--dnl # 2.6.23 API change
--dnl # Old set_shrinker API replaced with register_shrinker
--dnl #
--AC_DEFUN([SPL_AC_SET_SHRINKER], [
-- AC_MSG_CHECKING([whether set_shrinker() available])
-- SPL_LINUX_TRY_COMPILE([
-- #include <linux/mm.h>
-- ],[
-- return set_shrinker(DEFAULT_SEEKS, NULL);
-- ],[
-- AC_MSG_RESULT([yes])
-- AC_DEFINE(HAVE_SET_SHRINKER, 1,
-- [set_shrinker() available])
-- ],[
-- AC_MSG_RESULT([no])
-- ])
--])
--
--dnl #
--dnl # 2.6.35 API change,
--dnl # Add context to shrinker callback
--dnl #
--AC_DEFUN([SPL_AC_3ARGS_SHRINKER_CALLBACK],
-- [AC_MSG_CHECKING([whether shrinker callback wants 3 args])
-+AC_DEFUN([SPL_AC_SHRINKER_CALLBACK],[
- tmp_flags="$EXTRA_KCFLAGS"
- EXTRA_KCFLAGS="-Werror"
-+ dnl #
-+ dnl # 2.6.23 to 2.6.34 API change
-+ dnl # ->shrink(int nr_to_scan, gfp_t gfp_mask)
-+ dnl #
-+ AC_MSG_CHECKING([whether old 2-argument shrinker exists])
- SPL_LINUX_TRY_COMPILE([
- #include <linux/mm.h>
-
-- int shrinker_cb(struct shrinker *, int, unsigned int);
-+ int shrinker_cb(int nr_to_scan, gfp_t gfp_mask);
- ],[
- struct shrinker cache_shrinker = {
- .shrink = shrinker_cb,
-@@ -924,10 +904,86 @@ AC_DEFUN([SPL_AC_3ARGS_SHRINKER_CALLBACK],
- register_shrinker(&cache_shrinker);
- ],[
- AC_MSG_RESULT(yes)
-- AC_DEFINE(HAVE_3ARGS_SHRINKER_CALLBACK, 1,
-- [shrinker callback wants 3 args])
-+ AC_DEFINE(HAVE_2ARGS_OLD_SHRINKER_CALLBACK, 1,
-+ [old shrinker callback wants 2 args])
- ],[
- AC_MSG_RESULT(no)
-+ dnl #
-+ dnl # 2.6.35 - 2.6.39 API change
-+ dnl # ->shrink(struct shrinker *,
-+ dnl # int nr_to_scan, gfp_t gfp_mask)
-+ dnl #
-+ AC_MSG_CHECKING([whether old 3-argument shrinker exists])
-+ SPL_LINUX_TRY_COMPILE([
-+ #include <linux/mm.h>
-+
-+ int shrinker_cb(struct shrinker *, int nr_to_scan,
-+ gfp_t gfp_mask);
-+ ],[
-+ struct shrinker cache_shrinker = {
-+ .shrink = shrinker_cb,
-+ .seeks = DEFAULT_SEEKS,
-+ };
-+ register_shrinker(&cache_shrinker);
-+ ],[
-+ AC_MSG_RESULT(yes)
-+ AC_DEFINE(HAVE_3ARGS_SHRINKER_CALLBACK, 1,
-+ [old shrinker callback wants 3 args])
-+ ],[
-+ AC_MSG_RESULT(no)
-+ dnl #
-+ dnl # 3.0 - 3.11 API change
-+ dnl # ->shrink(struct shrinker *,
-+ dnl # struct shrink_control *sc)
-+ dnl #
-+ AC_MSG_CHECKING(
-+ [whether new 2-argument shrinker exists])
-+ SPL_LINUX_TRY_COMPILE([
-+ #include <linux/mm.h>
-+
-+ int shrinker_cb(struct shrinker *,
-+ struct shrink_control *sc);
-+ ],[
-+ struct shrinker cache_shrinker = {
-+ .shrink = shrinker_cb,
-+ .seeks = DEFAULT_SEEKS,
-+ };
-+ register_shrinker(&cache_shrinker);
-+ ],[
-+ AC_MSG_RESULT(yes)
-+ AC_DEFINE(HAVE_2ARGS_NEW_SHRINKER_CALLBACK, 1,
-+ [new shrinker callback wants 2 args])
-+ ],[
-+ AC_MSG_RESULT(no)
-+ dnl #
-+ dnl # 3.12 API change,
-+ dnl # ->shrink() is logically split in to
-+ dnl # ->count_objects() and ->scan_objects()
-+ dnl #
-+ AC_MSG_CHECKING(
-+ [whether ->count_objects callback exists])
-+ SPL_LINUX_TRY_COMPILE([
-+ #include <linux/mm.h>
-+
-+ unsigned long shrinker_cb(
-+ struct shrinker *,
-+ struct shrink_control *sc);
-+ ],[
-+ struct shrinker cache_shrinker = {
-+ .count_objects = shrinker_cb,
-+ .scan_objects = shrinker_cb,
-+ .seeks = DEFAULT_SEEKS,
-+ };
-+ register_shrinker(&cache_shrinker);
-+ ],[
-+ AC_MSG_RESULT(yes)
-+ AC_DEFINE(HAVE_SPLIT_SHRINKER_CALLBACK,
-+ 1, [->count_objects exists])
-+ ],[
-+ AC_MSG_ERROR(error)
-+ ])
-+ ])
-+ ])
- ])
- EXTRA_KCFLAGS="$tmp_flags"
- ])
-diff --git a/include/linux/mm_compat.h b/include/linux/mm_compat.h
-index cb1bef9..37c9b08 100644
---- a/include/linux/mm_compat.h
-+++ b/include/linux/mm_compat.h
-@@ -148,107 +148,167 @@ typedef int (*shrink_icache_memory_t)(struct shrinker *,
- #endif /* HAVE_SHRINK_ICACHE_MEMORY */
-
- /*
-- * Linux 2.6. - 2.6. Shrinker API Compatibility.
-+ * Due to frequent changes in the shrinker API the following
-+ * compatibility wrappers should be used. They are as follows:
-+ *
-+ * SPL_SHRINKER_DECLARE is used to declare the shrinker which is
-+ * passed to spl_register_shrinker()/spl_unregister_shrinker(). Use
-+ * shrinker_name to set the shrinker variable name, shrinker_callback
-+ * to set the callback function, and seek_cost to define the cost of
-+ * reclaiming an object.
-+ *
-+ * SPL_SHRINKER_DECLARE(shrinker_name, shrinker_callback, seek_cost);
-+ *
-+ * SPL_SHRINKER_CALLBACK_FWD_DECLARE is used when a forward declaration
-+ * of the shrinker callback function is required. Only the callback
-+ * function needs to be passed.
-+ *
-+ * SPL_SHRINKER_CALLBACK_FWD_DECLARE(shrinker_callback);
-+ *
-+ * SPL_SHRINKER_CALLBACK_WRAPPER is used to declare the callback function
-+ * which is registered with the shrinker. This function will call your
-+ * custom shrinker which must use the following prototype. Notice the
-+ * leading __'s, these must be appended to the callback_function name.
-+ *
-+ * int __shrinker_callback(struct shrinker *, struct shrink_control *)
-+ * SPL_SHRINKER_CALLBACK_WRAPPER(shrinker_callback);a
-+ *
-+ *
-+ * Example:
-+ *
-+ * SPL_SHRINKER_CALLBACK_FWD_DECLARE(my_shrinker_fn);
-+ * SPL_SHRINKER_DECLARE(my_shrinker, my_shrinker_fn, 1);
-+ *
-+ * static int
-+ * __my_shrinker_fn(struct shrinker *shrink, struct shrink_control *sc)
-+ * {
-+ * if (sc->nr_to_scan) {
-+ * ...scan objects in the cache and reclaim them...
-+ * }
-+ *
-+ * ...calculate number of objects in the cache...
-+ *
-+ * return (number of objects in the cache);
-+ * }
-+ * SPL_SHRINKER_CALLBACK_WRAPPER(my_shrinker_fn);
- */
--#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_register_shrinker(x) register_shrinker(x)
-+#define spl_unregister_shrinker(x) unregister_shrinker(x)
-
--# define SPL_SHRINKER_DECLARE(s, x, y) \
-- static spl_shrinker_t s = { \
-- .shrinker = NULL, \
-- .fn = x, \
-- .seeks = y \
-- }
--
--# define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-- static int fn(int, unsigned int)
--# define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
--static int \
--fn(int nr_to_scan, unsigned int gfp_mask) \
--{ \
-- struct shrink_control sc; \
-- \
-- sc.nr_to_scan = nr_to_scan; \
-- sc.gfp_mask = gfp_mask; \
-- \
-- return __ ## fn(NULL, &sc); \
-+/*
-+ * Linux 2.6.23 - 2.6.34 Shrinker API Compatibility.
-+ */
-+#if defined(HAVE_2ARGS_OLD_SHRINKER_CALLBACK)
-+#define SPL_SHRINKER_DECLARE(s, x, y) \
-+static struct shrinker s = { \
-+ .shrink = x, \
-+ .seeks = y \
- }
-
--#else
-+#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-+static int fn(int nr_to_scan, unsigned int gfp_mask)
-
--# 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 \
-- }
-+#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
-+static int \
-+fn(int nr_to_scan, unsigned int gfp_mask) \
-+{ \
-+ struct shrink_control sc; \
-+ \
-+ sc.nr_to_scan = nr_to_scan; \
-+ sc.gfp_mask = gfp_mask; \
-+ \
-+ return (__ ## fn(NULL, &sc)); \
-+}
-
- /*
-- * Linux 2.6. - 2.6. Shrinker API Compatibility.
-+ * Linux 2.6.35 to 2.6.39 Shrinker API Compatibility.
- */
--# if defined(HAVE_SHRINK_CONTROL_STRUCT)
--# define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-- static int fn(struct shrinker *, struct shrink_control *)
--# define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
--static int \
--fn(struct shrinker *shrink, struct shrink_control *sc) { \
-- return __ ## fn(shrink, sc); \
-+#elif defined(HAVE_3ARGS_SHRINKER_CALLBACK)
-+#define SPL_SHRINKER_DECLARE(s, x, y) \
-+static struct shrinker s = { \
-+ .shrink = x, \
-+ .seeks = y \
-+}
-+
-+#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-+static int fn(struct shrinker *, int, unsigned int)
-+
-+#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
-+static int \
-+fn(struct shrinker *shrink, int nr_to_scan, unsigned int gfp_mask) \
-+{ \
-+ struct shrink_control sc; \
-+ \
-+ sc.nr_to_scan = nr_to_scan; \
-+ sc.gfp_mask = gfp_mask; \
-+ \
-+ return (__ ## fn(shrink, &sc)); \
- }
-
- /*
-- * Linux 2.6. - 2.6. Shrinker API Compatibility.
-+ * Linux 3.0 to 3.11 Shrinker API Compatibility.
- */
--# elif defined(HAVE_3ARGS_SHRINKER_CALLBACK)
--# define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-- static int fn(struct shrinker *, int, unsigned int)
--# define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
--static int \
--fn(struct shrinker *shrink, int nr_to_scan, unsigned int gfp_mask) \
--{ \
-- struct shrink_control sc; \
-- \
-- sc.nr_to_scan = nr_to_scan; \
-- sc.gfp_mask = gfp_mask; \
-- \
-- return __ ## fn(shrink, &sc); \
-+#elif defined(HAVE_2ARGS_NEW_SHRINKER_CALLBACK)
-+#define SPL_SHRINKER_DECLARE(s, x, y) \
-+static struct shrinker s = { \
-+ .shrink = x, \
-+ .seeks = y \
-+}
-+
-+#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-+static int fn(struct shrinker *, struct shrink_control *)
-+
-+#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
-+static int \
-+fn(struct shrinker *shrink, struct shrink_control *sc) \
-+{ \
-+ return (__ ## fn(shrink, sc)); \
- }
-
- /*
-- * Linux 2.6. - 2.6. Shrinker API Compatibility.
-+ * Linux 3.12 and later Shrinker API Compatibility.
- */
--# else
--# define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-- static int fn(int, unsigned int)
--# define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
--static int \
--fn(int nr_to_scan, unsigned int gfp_mask) \
--{ \
-- struct shrink_control sc; \
-- \
-- sc.nr_to_scan = nr_to_scan; \
-- sc.gfp_mask = gfp_mask; \
-- \
-- return __ ## fn(NULL, &sc); \
-+#elif defined(HAVE_SPLIT_SHRINKER_CALLBACK)
-+#define SPL_SHRINKER_DECLARE(s, x, y) \
-+static struct shrinker s = { \
-+ .count_objects = x ## _count_objects, \
-+ .scan_objects = x ## _scan_objects, \
-+ .seeks = y \
- }
-
--# endif
--#endif /* HAVE_SET_SHRINKER */
-+#define SPL_SHRINKER_CALLBACK_FWD_DECLARE(fn) \
-+static unsigned long fn ## _count_objects(struct shrinker *, \
-+ struct shrink_control *); \
-+static unsigned long fn ## _scan_objects(struct shrinker *, \
-+ struct shrink_control *)
-+
-+#define SPL_SHRINKER_CALLBACK_WRAPPER(fn) \
-+static unsigned long \
-+fn ## _count_objects(struct shrinker *shrink, struct shrink_control *sc)\
-+{ \
-+ int __ret__; \
-+ \
-+ sc->nr_to_scan = 0; \
-+ __ret__ = __ ## fn(NULL, sc); \
-+ \
-+ /* Errors may not be returned and must be converted to zeros */ \
-+ return ((__ret__ < 0) ? 0 : __ret__); \
-+} \
-+ \
-+static unsigned long \
-+fn ## _scan_objects(struct shrinker *shrink, struct shrink_control *sc) \
-+{ \
-+ int __ret__; \
-+ \
-+ __ret__ = __ ## fn(NULL, sc); \
-+ return ((__ret__ < 0) ? SHRINK_STOP : __ret__); \
-+}
-+#else
-+/*
-+ * Linux 2.x to 2.6.22, or a newer shrinker API has been introduced.
-+ */
-+#error "Unknown shrinker callback"
-+#endif
-
- #endif /* SPL_MM_COMPAT_H */
---
-1.8.5.1
-