kern: Add initial virtual file system sources

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

1 files changed, 116 insertions, 0 deletions

diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c
new file mode 100644
index 0000000..d733a3f
--- /dev/null
+++ b/sys/kern/vfs_mount.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (c) 2025 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/param.h>
+#include <kern/spinlock.h>
+#include <kern/panic.h>
+#include <os/mount.h>
+#include <os/vfs.h>
+#include <lib/stdbool.h>
+#include <vm/kalloc.h>
+
+/*
+ * We can't quite distribute this lock in a sane way without
+ * complicating things significantly and thus the practicality
+ * of such is questionable. Unfortunately, having a global lock
+ * comes with some performance penalties due to contention. At
+ * the very least, we can prevent it from bouncing around between
+ * caches on multicore systems by aligning it to a cacheline boundary.
+ */
+__cacheline_aligned
+static struct spinlock mount_lock;
+
+/* Mount list */
+static TAILQ_HEAD(, mount) mountlist;
+static bool is_mountlist_init = false;
+
+/*
+ * Initialize the mountlist
+ */
+static void
+mountlist_init(void)
+{
+    if (is_mountlist_init) {
+        return;
+    }
+
+    TAILQ_INIT(&mountlist);
+    if (spinlock_init("mount", &mount_lock) != 0) {
+        panic("mount: failed to initialize mountlist\n");
+    }
+    is_mountlist_init = true;
+}
+
+int
+mount(struct mount_args *margs)
+{
+    struct fs_info *fip;
+    struct mount *mp;
+    int error;
+
+    if (margs == NULL) {
+        return -EINVAL;
+    }
+
+    if (margs->target == NULL || margs->fstype == NULL) {
+        return -EINVAL;
+    }
+
+    /* Initialize the mountlist if needed */
+    if (!is_mountlist_init) {
+        mountlist_init();
+    }
+
+    error = vfs_byname(margs->fstype, &fip);
+    if (error != 0) {
+        return error;
+    }
+
+    mp = kalloc(sizeof(*mp));
+    if (mp == NULL) {
+        return -ENOMEM;
+    }
+
+    mp->fip = fip;
+    error = vnode_init(&mp->vp, VDIR);
+    if (error < 0) {
+        kfree(mp);
+        return error;
+    }
+
+    /*
+     * TODO: We'd need to do a namei() here, add by-path
+     */
+    spinlock_acquire(&mount_lock, false);
+    TAILQ_INSERT_TAIL(&mountlist, mp, link);
+    spinlock_release(&mount_lock, false);
+    return 0;
+}