kernel: vm: Add vnode pager

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

1 files changed, 112 insertions, 0 deletions

diff --git a/sys/vm/vm_vnode.c b/sys/vm/vm_vnode.c
new file mode 100644
index 0000000..707f7b4
--- /dev/null
+++ b/sys/vm/vm_vnode.c
@@ -0,0 +1,112 @@
+/*
+ * 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.
+ */
+
+#include <sys/types.h>
+#include <sys/errno.h>
+#include <sys/sio.h>
+#include <sys/vfs.h>
+#include <sys/cdefs.h>
+#include <vm/obj.h>
+#include <vm/vm.h>
+#include <vm/pager.h>
+
+static int vn_pager_get(struct vm_object *obj, off_t off, size_t len,
+                        struct vm_page *pg);
+
+static int vn_pager_store(struct vm_object *obj, off_t off, size_t len,
+                          struct vm_page *pg);
+
+/* Pager operations */
+struct vm_pagerops g_vnode_pagerops = {
+    .get = vn_pager_get,
+    .store = vn_pager_store
+};
+
+static inline void
+vn_prep_sio(struct sio_txn *sio, char *pg, off_t off, size_t len)
+{
+    sio->len = __ALIGN_DOWN(len, vm_get_page_size());
+    sio->buf = pg;
+    sio->offset = off;
+    sio->len = len;
+}
+
+static int
+vn_pager_io(struct vm_object *obj, off_t off, size_t len,
+            struct vm_page *pg, bool out)
+{
+    struct sio_txn sio;
+    struct vnode *vp;
+    ssize_t paged_bytes;
+    char *dest;
+    int res = 0;
+
+    if (obj == NULL || pg == NULL) {
+        return -EIO;
+    }
+
+    spinlock_acquire(&obj->lock);
+    dest = PHYS_TO_VIRT(pg->physaddr);
+
+    /* Attempt to fetch the vnode */
+    if ((vp = obj->vnode) == NULL) {
+        res = -EIO;
+        goto done;
+    }
+
+    /* Prepare the SIO transaction */
+    vn_prep_sio(&sio, dest, off, len);
+    if (sio.len == 0) {
+        res = -EIO;
+        goto done;
+    }
+
+    /* Perform I/O on the backing store */
+    paged_bytes = out ? vfs_write(vp, &sio) : vfs_read(vp, &sio);
+    if (paged_bytes < 0) {
+        /* Failure */
+        res = paged_bytes;
+        goto done;
+    }
+done:
+    spinlock_release(&obj->lock);
+    return res;
+}
+
+static int
+vn_pager_store(struct vm_object *obj, off_t off, size_t len, struct vm_page *pg)
+{
+    return vn_pager_io(obj, off, len, pg, true);
+}
+
+static int
+vn_pager_get(struct vm_object *obj, off_t off, size_t len, struct vm_page *pg)
+{
+    return vn_pager_io(obj, off, len, pg, false);
+}