nfs: Support multiple mounts with the same path basename

NFSv4 mounts NFS file systems to the flat root of a pseudo file
system. This change allow the same basename to be used.

rtemsbsd/fs/nfsclient/nfs.c

@@ -830,8 +830,10 @@ rtems_nfs_initialize(
     rtems_filesystem_mount_table_entry_t *mt_entry, const void *data)
 {
 	struct nfs_args args;
-	const char *fspath = NULL;
+	static int mount_counter;
+	char fspath[NAME_MAX + 1];
 	char *at;
+	int len;
 	int error;
 
 	if (RTEMS_DEBUG) {
@@ -923,15 +925,30 @@ rtems_nfs_initialize(
 
 	rtems_bsd_vfs_mount_init(mt_entry);
 
-	fspath = mt_entry->target;
+	at = mt_entry->target + strlen(mt_entry->target);
-	if (*fspath == '/') {
+	len = 0;
-		++fspath;
+	while (at != mt_entry->target && !rtems_filesystem_is_delimiter(at[-1])) {
+		at--;
+		len++;
 	}
-	if (strchr(fspath, '/') != 0) {
+
+	/*
+	 * Account for the mount number and leading `/`
+	 */
+	if (len >= sizeof(fspath) - (6 + 2)) {
 		error = EINVAL;
 		goto out;
 	}
 
+	/*
+	 * Append a unique number to the end of the path created in
+	 * the FreeBSD root file system. All mounts are in the root
+	 * directory of the root file system and so flat. A user could
+	 * use different mount paths with the same end name. Without
+	 * the counter appended they would clash.
+	 */
+	snprintf(fspath, sizeof(fspath), "/%s-%d", at, mount_counter++);
+
 	if (getnfsargs(mt_entry->dev, &args) < 0) {
 		if (RTEMS_DEBUG)
 			printf(
@@ -949,7 +966,7 @@ rtems_nfs_initialize(
 	 * export then find the vnode and hold it. Make sure we find the root
 	 * node of the NFS share and the not the root file system's mount node.
 	 */
-	error = rtems_bsd_rootfs_mkdir(fspath);
+	error = rtems_bsd_rootfs_mkdir(fspath + 1);
 	if (error == 0) {
 		struct addrinfo *ai;
 		enum tryret tryret;

rtemsbsd/rtems/rtems-bsd-syscall-api.c

@@ -889,6 +889,7 @@ rtems_bsd_sysgen_open_node(
 	struct vnode *cdir;
 	struct vnode *rdir;
 	const char *opath;
+	rtems_filesystem_location_info_t *rootloc;
 	int opathlen;
 	int fd;
 	int error;
@@ -902,6 +903,8 @@ rtems_bsd_sysgen_open_node(
 
 	fdp = td->td_proc->p_fd;
 
+	rootloc = &iop->pathinfo.mt_entry->mt_fs_root->location;
+
 	/*
 	 * There is no easy or clean means to open a vnode and follow the
 	 * POSIX open semantics. See `kern_openat`. You can open a vnode but
@@ -912,12 +915,17 @@ rtems_bsd_sysgen_open_node(
 	 * parent directory vnode to position ourselves in the parent
 	 * directory. The pathloc vnode points to the '.' or '..'  directory.
 	 */
+	if (rtems_bsd_libio_loc_to_vnode(&iop->pathinfo) ==
+	    rtems_bsd_libio_loc_to_vnode(rootloc)) {
+		opath = ".";
+	} else {
 		opath = path + strlen(path);
 		opathlen = 0;
 		while (opath != path && !rtems_filesystem_is_delimiter(opath[-1])) {
 			opath--;
 			opathlen++;
 		}
+	}
 	if (rtems_filesystem_is_current_directory(opath, opathlen) ||
 	    rtems_filesystem_is_parent_directory(opath, opathlen)) {
 		if (((oflag + 1) & _FWRITE) == _FWRITE) {
@@ -929,8 +937,6 @@ rtems_bsd_sysgen_open_node(
 		opath = ".";
 		cdir = rtems_bsd_libio_loc_to_vnode(&iop->pathinfo);
 	} else {
-		rtems_filesystem_location_info_t *rootloc =
-		    &iop->pathinfo.mt_entry->mt_fs_root->location;
 		/*
 		 * We need the parent directory so open can find the
 		 * entry. If we are creating the file the pathinfo
@@ -943,18 +949,6 @@ rtems_bsd_sysgen_open_node(
 		}
 		if (fdp->fd_cdir == NULL) {
 			cdir = rtems_bsd_libio_loc_to_vnode_dir(rootloc);
-		} else if (rtems_bsd_libio_loc_to_vnode(&iop->pathinfo) ==
-				rtems_bsd_libio_loc_to_vnode(rootloc)) {
-			/*
-			 * If this is a directory and this is the root node of
-			 * the mounted file system we need to move up the
-			 * hidden pseudo file system node.
-			 */
-			if (isdir) {
-				cdir = rootvnode;
-			} else {
-				cdir = rtems_bsd_libio_loc_to_vnode(rootloc);
-			}
 		}
 	}