Extend kobj compatibility KPI to support operating on files before and

after the root file system is mounted.
This is one of the changes that will allow to put root file system on ZFS.

2 files changed, 102 insertions, 16 deletions

diff --git a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
index b205238cbb91..4db68f4ad651 100644
--- a/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
+++ b/sys/cddl/compat/opensolaris/kern/opensolaris_kobj.c
@@ -30,12 +30,13 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
+#include <sys/systm.h>
 #include <sys/kthread.h>
 #include <sys/namei.h>
 #include <sys/proc.h>
 #include <sys/filedesc.h>
-#include <sys/vnode.h>
 #include <sys/fcntl.h>
+#include <sys/linker.h>
 #include <sys/kobj.h>
 
 void
@@ -62,8 +63,8 @@ kobj_zalloc(size_t size, int flag)
 	return (p);
 }
 
-struct _buf *
-kobj_open_file(const char *file)
+static void *
+kobj_open_file_vnode(const char *file)
 {
 	struct thread *td = curthread;
 	struct nameidata nd;
@@ -79,16 +80,45 @@ kobj_open_file(const char *file)
 	error = vn_open_cred(&nd, &flags, 0, td->td_ucred, -1);
 	NDFREE(&nd, NDF_ONLY_PNBUF);
 	if (error != 0)
-		return ((struct _buf *)-1);
+		return (NULL);
 	/* We just unlock so we hold a reference. */
 	VOP_UNLOCK(nd.ni_vp, 0, td);
-	return ((struct _buf *)nd.ni_vp);
+	return (nd.ni_vp);
 }
 
-int
-kobj_get_filesize(struct _buf *file, uint64_t *size)
+static void *
+kobj_open_file_loader(const char *file)
+{
+
+	return (preload_search_by_name(file));
+}
+
+struct _buf *
+kobj_open_file(const char *file)
+{
+	struct _buf *out;
+
+	out = kmem_alloc(sizeof(*out), KM_SLEEP);
+	out->mounted = root_mounted();
+	/*
+	 * If root is already mounted we read file using file system,
+	 * if not, we use loader.
+	 */
+	if (out->mounted)
+		out->ptr = kobj_open_file_vnode(file);
+	else
+		out->ptr = kobj_open_file_loader(file);
+	if (out->ptr == NULL) {
+		kmem_free(out, sizeof(*out));
+		return ((struct _buf *)-1);
+	}
+	return (out);
+}
+
+static int
+kobj_get_filesize_vnode(struct _buf *file, uint64_t *size)
 {
-	struct vnode *vp = (struct vnode *)file;
+	struct vnode *vp = file->ptr;
 	struct thread *td = curthread;
 	struct vattr va;
 	int error;
@@ -101,10 +131,32 @@ kobj_get_filesize(struct _buf *file, uint64_t *size)
 	return (error);
 }
 
+static int
+kobj_get_filesize_loader(struct _buf *file, uint64_t *size)
+{
+	void *ptr;
+
+	ptr = preload_search_info(file->ptr, MODINFO_SIZE);
+	if (ptr == NULL)
+		return (ENOENT);
+	*size = (uint64_t)*(size_t *)ptr;
+	return (0);
+}
+
 int
-kobj_read_file(struct _buf *file, char *buf, unsigned size, unsigned off)
+kobj_get_filesize(struct _buf *file, uint64_t *size)
+{
+
+	if (file->mounted)
+		return (kobj_get_filesize_vnode(file, size));
+	else
+		return (kobj_get_filesize_loader(file, size));
+}
+
+int
+kobj_read_file_vnode(struct _buf *file, char *buf, unsigned size, unsigned off)
 {
-	struct vnode *vp = (struct vnode *)file;
+	struct vnode *vp = file->ptr;
 	struct thread *td = curthread;
 	struct uio auio;
 	struct iovec aiov;
@@ -130,13 +182,39 @@ kobj_read_file(struct _buf *file, char *buf, unsigned size, unsigned off)
 	return (error != 0 ? -1 : size - auio.uio_resid);
 }
 
+int
+kobj_read_file_loader(struct _buf *file, char *buf, unsigned size, unsigned off)
+{
+	char *ptr;
+
+	ptr = preload_search_info(file->ptr, MODINFO_ADDR);
+	if (ptr == NULL)
+		return (ENOENT);
+	ptr = *(void **)ptr;
+	bcopy(ptr + off, buf, size);
+	return (0);
+}
+
+int
+kobj_read_file(struct _buf *file, char *buf, unsigned size, unsigned off)
+{
+
+	if (file->mounted)
+		return (kobj_read_file_vnode(file, buf, size, off));
+	else
+		return (kobj_read_file_loader(file, buf, size, off));
+}
+
 void
 kobj_close_file(struct _buf *file)
 {
-	struct vnode *vp = (struct vnode *)file;
-	struct thread *td = curthread;
-	int flags;
 
-	flags = FREAD;
-	vn_close(vp, flags, td->td_ucred, td);
+	if (file->mounted) {
+		struct vnode *vp = file->ptr;
+		struct thread *td = curthread;
+		int flags = FREAD;
+
+		vn_close(vp, flags, td->td_ucred, td);
+	}
+	kmem_free(file, sizeof(*file));
 }
diff --git a/sys/cddl/compat/opensolaris/sys/kobj.h b/sys/cddl/compat/opensolaris/sys/kobj.h
index 87c639e44764..e060ff04ce2f 100644
--- a/sys/cddl/compat/opensolaris/sys/kobj.h
+++ b/sys/cddl/compat/opensolaris/sys/kobj.h
@@ -31,6 +31,13 @@
 
 #include <sys/types.h>
 #include <sys/kmem.h>
+#include_next <sys/kobj.h>
+#ifdef AT_UID
+#undef AT_UID
+#endif
+#ifdef AT_GID
+#undef AT_GID
+#endif
 #include <sys/vnode.h>
 
 #define	KM_NOWAIT	0x01
@@ -41,7 +48,8 @@ void *kobj_alloc(size_t size, int flag);
 void *kobj_zalloc(size_t size, int flag);
 
 struct _buf {
-	void	*dummy;
+	void *ptr;
+	int mounted;
 };
 
 struct _buf *kobj_open_file(const char *path);