kernel: vfs: Add vnode cache implementation

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

5 files changed, 246 insertions, 0 deletions

diff --git a/sys/include/sys/sysctl.h b/sys/include/sys/sysctl.h
index 0f1df26..9623137 100644
--- a/sys/include/sys/sysctl.h
+++ b/sys/include/sys/sysctl.h
@@ -39,6 +39,7 @@
 #define KERN_OSTYPE         0
 #define KERN_OSRELEASE      1
 #define KERN_VERSION        2
+#define KERN_VCACHE_TYPE    3
 
 /*
  * Option types (i.e., int, string, etc) for
diff --git a/sys/include/sys/vnode.h b/sys/include/sys/vnode.h
index 3f3b011..33d5b17 100644
--- a/sys/include/sys/vnode.h
+++ b/sys/include/sys/vnode.h
@@ -31,6 +31,7 @@
 #define _SYS_VNODE_H_
 
 #include <sys/types.h>
+#include <sys/queue.h>
 #include <sys/atomic.h>
 #include <sys/sio.h>
 
@@ -44,10 +45,18 @@ struct vnode {
     void *data;
     const struct vops *vops;
     uint32_t refcount;
+    TAILQ_ENTRY(vnode) vcache_link;
 };
 
 #define vfs_vref(VP) (atomic_inc_int(&(VP)->refcount))
 
+/* vcache types */
+#if defined(_KERNEL)
+#define VCACHE_TYPE_NONE   0
+#define VCACHE_TYPE_PROC   1
+#define VCACHE_TYPE_GLOBAL 2
+#endif  /* KERNEL */
+
 /* Vnode type flags */
 #define VNON    0x00    /* Uninitialized */
 #define VREG    0x01    /* Regular file */
@@ -86,6 +95,12 @@ struct vops {
 
 extern struct vnode *g_root_vnode;
 
+int vfs_vcache_type(void);
+int vfs_vcache_migrate(int newtype);
+
+int vfs_vcache_enter(struct vnode *vp);
+struct vnode *vfs_recycle_vnode(void);
+
 int vfs_alloc_vnode(struct vnode **res, int type);
 int vfs_release_vnode(struct vnode *vp);
 
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index a1bd91a..6334d06 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -52,6 +52,7 @@ static struct sysctl_entry common_optab[] = {
     [KERN_OSTYPE] = { KERN_OSTYPE, SYSCTL_OPTYPE_STR_RO, hyra },
     [KERN_OSRELEASE] = { KERN_OSRELEASE, SYSCTL_OPTYPE_STR_RO, &osrelease },
     [KERN_VERSION] = { KERN_VERSION, SYSCTL_OPTYPE_STR_RO, &hyra_version },
+    [KERN_VCACHE_TYPE] = { KERN_VCACHE_TYPE, SYSCTL_OPTYPE_STR, NULL }
 };
 
 static int
diff --git a/sys/kern/vfs_init.c b/sys/kern/vfs_init.c
index ab18d09..e563df0 100644
--- a/sys/kern/vfs_init.c
+++ b/sys/kern/vfs_init.c
@@ -56,6 +56,9 @@ vfs_init(void)
             vfsops->init(fs);
         }
     }
+
+    /* Use global vcache by default */
+    vfs_vcache_migrate(VCACHE_TYPE_GLOBAL);
 }
 
 struct fs_info *
diff --git a/sys/kern/vfs_vcache.c b/sys/kern/vfs_vcache.c
new file mode 100644
index 0000000..dc140f7
--- /dev/null
+++ b/sys/kern/vfs_vcache.c
@@ -0,0 +1,226 @@
+/*
+ * 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/vnode.h>
+#include <sys/errno.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <sys/sysctl.h>
+#include <sys/syslog.h>
+#include <sys/panic.h>
+#include <sys/spinlock.h>
+#include <vm/dynalloc.h>
+#include <string.h>
+
+#define VCACHE_SIZE 64
+
+#define pr_trace(fmt, ...) kprintf("vcache: " fmt, ##__VA_ARGS__)
+
+struct vcache {
+    TAILQ_HEAD(vcache_head, vnode) q;
+    ssize_t size;    /* In entries (-1 not set up) */
+} vcache = { .size = -1 };
+
+/*
+ * Our vcache will be here if our caching type is
+ * global.
+ */
+static int vcache_type = VCACHE_TYPE_NONE;
+__cacheline_aligned static struct spinlock vcache_lock;
+
+/*
+ * Pull a vnode from the head of the global
+ * vcache. Returns NULL if none are found.
+ *
+ * XXX: Caller must acquire vcache_lock.
+ */
+static struct vnode *
+vcache_global_pull(void)
+{
+    struct vnode *vp;
+
+    if (vcache.size <= 0) {
+        return NULL;
+    }
+
+    vp = TAILQ_FIRST(&vcache.q);
+    TAILQ_REMOVE(&vcache.q, vp, vcache_link);
+    --vcache.size;
+    return vp;
+}
+
+/*
+ * Add a new entry to the global vcache
+ *
+ * XXX: Caller must acquire vcache_lock.
+ * @vp: New vnode to add.
+ */
+static int
+vcache_global_add(struct vnode *vp)
+{
+    struct vnode *tmp;
+
+    /*
+     * Do some checks on the vcache size, should be >= 0
+     * but if it is -1 then we just need to initialize the
+     * queue. However, if it is less than -1... Then shit,
+     * good luck debugging I suppose.
+     *
+     * The global vcache naturally behaves as an LRU cache.
+     * If we need more space, the tail of the queue is evicted.
+     */
+    if (vcache.size < 0) {
+        TAILQ_INIT(&vcache.q);
+        vcache.size = 0;
+    } else if (vcache.size < -1) {
+        panic("vcache_global_add: Bad vcache size, catching fire\n");
+    } else if (vcache.size == VCACHE_SIZE) {
+        /* Evict the tail */
+        tmp = TAILQ_LAST(&vcache.q, vcache_head);
+        TAILQ_REMOVE(&vcache.q, tmp, vcache_link);
+        dynfree(tmp);
+        --vcache.size;
+    }
+
+    TAILQ_INSERT_TAIL(&vcache.q, vp, vcache_link);
+    ++vcache.size;
+    return 0;
+}
+
+/*
+ * Migrate the vnode cache (vcache) from one mode
+ * (e.g., global, proc, none) to another. This transition
+ * is done without an extreme performance impact through a
+ * process called lazy vcache migration (LZVM). For example,
+ * if we update the vcache type to be "proc" from an initial
+ * type of "global", the global vcache is made read-only until
+ * all entries are eventually invalidated naturally. In other
+ * words, both the global vcache and per-process vcaches will
+ * be checked during the migration process, however once the
+ * global vcache becomes empty it will no longer be checked.
+ */
+int
+vfs_vcache_migrate(int newtype)
+{
+    char *sysctl_val;
+    struct sysctl_args args;
+    int retval, name = KERN_VCACHE_TYPE;
+
+    switch (newtype) {
+    case VCACHE_TYPE_NONE:
+        sysctl_val = "none";
+        break;
+    case VCACHE_TYPE_PROC:
+        sysctl_val = "proc";
+        break;
+    case VCACHE_TYPE_GLOBAL:
+        sysctl_val = "global";
+        break;
+    default:
+        return -EINVAL;
+    }
+
+    /* Prepare the sysctl args */
+    args.name = &name;
+    args.nlen = 1;
+    args.oldp = NULL;
+    args.oldlenp = NULL;
+    args.newp = sysctl_val;
+    args.newlen = strlen(sysctl_val);
+
+    if ((retval = sysctl(&args)) != 0) {
+        return retval;
+    }
+
+    vcache_type = newtype;
+    return 0;
+}
+
+/*
+ * Add a vnode to vcache.
+ *
+ * @vp: Pointer of vnode to add.
+ */
+int
+vfs_vcache_enter(struct vnode *vp)
+{
+    int retval = 0;
+
+    switch (vcache_type) {
+    case VCACHE_TYPE_NONE:
+        break;
+    case VCACHE_TYPE_PROC:
+        /* TODO */
+        pr_trace("warn: proc vcache not supported, using global...\n");
+        vcache_type = VCACHE_TYPE_GLOBAL;
+        /* - FALL THROUGH - */
+    case VCACHE_TYPE_GLOBAL:
+        spinlock_acquire(&vcache_lock);
+        retval = vcache_global_add(vp);
+        spinlock_release(&vcache_lock);
+        break;
+    default:
+        pr_trace("warn: Bad vcache type, falling back to none\n");
+        vcache_type = VCACHE_TYPE_NONE;
+        break;
+    }
+
+    return retval;
+}
+
+/*
+ * Pull a random vnode from the vcache to
+ * recycle.
+ */
+struct vnode *
+vfs_recycle_vnode(void)
+{
+    struct vnode *vp = NULL;
+
+    switch (vcache_type) {
+    case VCACHE_TYPE_NONE:
+        break;
+    case VCACHE_TYPE_PROC:
+        /* TODO */
+        pr_trace("warn: proc vcache not supported, using global...\n");
+        vcache_type = VCACHE_TYPE_GLOBAL;
+        /* - FALL THROUGH - */
+    case VCACHE_TYPE_GLOBAL:
+        spinlock_acquire(&vcache_lock);
+        vp = vcache_global_pull();
+        spinlock_release(&vcache_lock);
+        break;
+    default:
+        pr_trace("warn: Bad vcache type, falling back to none\n");
+        vcache_type = VCACHE_TYPE_NONE;
+        break;
+    }
+
+    return vp;
+}