kernel: vm: Add objects, page struct and pagers

This commit expands the virtual memory subsystem by providing the
initial implementation of virtual memory objects, pager descriptors and
pagers. This change currently implemenents a minimal vnode pager.

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/sys/include/vm/vm_pager.h b/sys/include/vm/vm_pager.h
new file mode 100644
index 0000000..80a5a6c
--- /dev/null
+++ b/sys/include/vm/vm_pager.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _VM_PAGER_H_
+#define _VM_PAGER_H_
+
+#include <sys/types.h>
+#include <vm/vm_page.h>
+#include <vm/vm_obj.h>
+
+struct vm_object;
+
+/*
+ * Pager operations.
+ *
+ * @init: Init pager
+ * @get: Read a page.
+ * @put: Write a page.
+ */
+struct vm_pagerops {
+    void(*init)(void);
+    int(*get)(struct vm_object *obp, struct vm_page **pgs, off_t off, size_t len);
+    int(*put)(struct vm_object *obp, struct vm_page *pgs, size_t len);
+};
+
+int vm_pager_get(struct vm_object *obp, struct vm_page **pgs, off_t off, size_t len);
+
+#endif  /* !_VM_PAGER_H_ */