kern: vfs: Add support for image-like paths

Typically filesystems are tree-like, however certain filesystems in the
form of images have fixed paths baked into them. This optimizes handling
so there isn't a need to unpack it into a rootfs/tmpfs

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

3 files changed, 45 insertions, 1 deletions

diff --git a/src/sys/include/sys/mount.h b/src/sys/include/sys/mount.h
index c93eb2b..c9f686c 100644
--- a/src/sys/include/sys/mount.h
+++ b/src/sys/include/sys/mount.h
@@ -48,6 +48,7 @@
 #define MOUNT_INITRD "initrd"   /* Initial ramdisk */
 
 /* Forward declarations */
+struct fs_info;
 struct vfsops;
 struct mount;
 
@@ -58,11 +59,13 @@ extern struct vfsops g_omar_vfsops;
  * Represents a mountpoint
  *
  * @vp: Vnode of mount
+ * @fs: The filesystem backing this mountpoint
  * @name: Mountname
  * @link: TAILQ link
  */
 struct mount {
     struct vnode *vp;
+    struct fs_info *fs;
     char name[FSNAME_MAX];
     TAILQ_ENTRY(mount) link;
 };
@@ -98,15 +101,27 @@ struct mount_args {
  *
  * @name: Filesystem type name
  * @vfsops: VFS operations vector
+ * @attr: Attribute mask that may be set by fs
  * @refcount: Mount count of this type
+ *
+ * XXX: The attributes mask is set by the filesystem and
+ *      intended as an optimization to provide a way for
+ *      filesystems set flags to modify behavior during
+ *      things like the lookup stage.
  */
 struct fs_info {
     char name[FSNAME_MAX];
     const struct vfsops *vfsops;
+    uint16_t attr;
     int refcount;
 };
 
 /*
+ * Filesystem attributes mask
+ */
+#define FS_ATTR_IMAGE BIT (0)    /* Is an image kind e.g., OSMORA OMAR */
+
+/*
  * VFS operations vector
  *
  * @init: Initialize the filesystem
diff --git a/src/sys/os/vfs_mount.c b/src/sys/os/vfs_mount.c
index 8f09096..034b324 100644
--- a/src/sys/os/vfs_mount.c
+++ b/src/sys/os/vfs_mount.c
@@ -228,7 +228,7 @@ mount(struct mount_args *margs, uint32_t flags)
         return error;
     }
 
-    /* The filesystem should give us its vnode */
+    mpp->fs = fip;
     mpp->vp = margs->vp_res;
     return 0;
 }
diff --git a/src/sys/os/vfs_namei.c b/src/sys/os/vfs_namei.c
index 8727965..18d35f2 100644
--- a/src/sys/os/vfs_namei.c
+++ b/src/sys/os/vfs_namei.c
@@ -43,6 +43,10 @@ int
 namei(struct nameidata *ndp)
 {
     struct mount *mp = NULL;
+    struct vnode *vp;
+    struct vop *vops;
+    struct vop_lookup_args lookup;
+    struct fs_info *fip;
     char namebuf[NAME_MAX];
     const char *p, *pcur;
     size_t len, i = 0;
@@ -63,6 +67,31 @@ namei(struct nameidata *ndp)
         return error;
     }
 
+    vp = mp->vp;
+    fip = mp->fs;
+
+    if ((vops = vp->vops) == NULL) {
+        printf("namei: failed to get vops\n");
+        return -EIO;
+    }
+
+    /* We need vops->lookup() */
+    if (vops->lookup == NULL) {
+        printf("namei: vops does not have lookup op\n");
+        return -EIO;
+    }
+
+    /*
+     * If this is an image we are looking up, then throw
+     * a path right at it.
+     */
+    if (ISSET(fip->attr, FS_ATTR_IMAGE)) {
+        lookup.name = ndp->path;
+        lookup.dirvp = mp->vp;
+        lookup.vpp = &vp;
+        return vops->lookup(&lookup);
+    }
+
     printf("namei: f: %s\n", ndp->path);
     printf("namei: d: /\n", ndp->path);