ocf: Request map allocation improvements

configure.d/1_kvmalloc.conf

@@ -0,0 +1,68 @@
+#!/bin/bash
+#
+# Copyright(c) 2026 Unvertical
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+. $(dirname $3)/conf_framework.sh
+
+# kvmalloc() supports GFP_NOIO (i.e. falls back to vmalloc() with NOIO
+# semantics) since commit a421ef303008 ("mm: allow !GFP_KERNEL allocations
+# for kvmalloc"), v5.17. It's a behavioral change, not detectable directly,
+# but the very same commit dropped ceph_kvmalloc(), so use it as a marker.
+# ceph_kvmalloc() isn't exported, so only check its declaration (typeof
+# doesn't emit a symbol reference that modpost would reject).
+# Default to the memalloc scope variant, as it's correct on every kernel.
+check() {
+	cur_name=$(basename $2)
+	config_file_path=$1
+	if compile_module $cur_name "__typeof__(&ceph_kvmalloc) f = NULL; (void)f;" "linux/ceph/libceph.h"
+	then
+		echo $cur_name "2" >> $config_file_path
+	elif compile_module $cur_name "struct ceph_client *c = NULL; (void)c;" "linux/ceph/libceph.h"
+	then
+		echo $cur_name "1" >> $config_file_path
+	else
+		echo $cur_name "2" >> $config_file_path
+	fi
+}
+
+apply() {
+    case "$1" in
+    "1")
+		add_function "
+	static inline void *cas_kvzalloc(size_t size, gfp_t flags)
+	{
+		return kvzalloc(size, flags);
+	}" ;;
+    "2")
+		add_function "
+#include <linux/sched/mm.h>
+	static inline void *cas_kvzalloc(size_t size, gfp_t flags)
+	{
+		unsigned int memalloc_flags;
+		void *ptr;
+
+		if ((flags & (__GFP_IO | __GFP_FS)) == (__GFP_IO | __GFP_FS))
+			return kvzalloc(size, flags);
+
+		if (flags & __GFP_IO)
+			memalloc_flags = memalloc_nofs_save();
+		else
+			memalloc_flags = memalloc_noio_save();
+
+		ptr = kvzalloc(size, GFP_KERNEL);
+
+		if (flags & __GFP_IO)
+			memalloc_nofs_restore(memalloc_flags);
+		else
+			memalloc_noio_restore(memalloc_flags);
+
+		return ptr;
+	}" ;;
+    *)
+        exit 1
+    esac
+}
+
+conf_run $@

modules/cas_cache/ocf_env.h

@@ -42,6 +42,20 @@ static inline void env_free(const void *ptr)
 	kfree(ptr);
 }
 
+/*
+ * Try a physically contiguous allocation first and fall back to vmalloc()
+ * if that fails.
+ */
+static inline void *env_kvzalloc(size_t size, int flags)
+{
+	return cas_kvzalloc(size, flags);
+}
+
+static inline void env_kvfree(const void *ptr)
+{
+	kvfree(ptr);
+}
+
 static inline void *env_vmalloc_flags(size_t size, int flags)
 {
 	return cas_vmalloc(size, flags | __GFP_HIGHMEM);