[PATCH 2/7] nfsd: Support running nfsd_name_to_handle_at() in the root jail

[trondmy@kernel.org]

From: Trond Myklebust <trond.myklebust@hammerspace.com>

When running nfsd_name_to_handle_at(), we usually want to see the same
namespace as knfsd, so add helpers.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
 support/include/nfsd_path.h |  4 +++
 support/misc/nfsd_path.c    | 66 +++++++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/support/include/nfsd_path.h b/support/include/nfsd_path.h
index 8331ff96a277..3b73aadd8af7 100644
--- a/support/include/nfsd_path.h
+++ b/support/include/nfsd_path.h
@@ -6,6 +6,7 @@
 
 #include <sys/stat.h>
 
+struct file_handle;
 struct statfs64;
 
 void 		nfsd_path_init(void);
@@ -25,4 +26,7 @@ char *		nfsd_realpath(const char *path, char *resolved_path);
 ssize_t		nfsd_path_read(int fd, char *buf, size_t len);
 ssize_t		nfsd_path_write(int fd, const char *buf, size_t len);
 
+int		nfsd_name_to_handle_at(int fd, const char *path,
+				       struct file_handle *fh,
+				       int *mount_id, int flags);
 #endif
diff --git a/support/misc/nfsd_path.c b/support/misc/nfsd_path.c
index ab6c98dbe395..1f6dfd4b642b 100644
--- a/support/misc/nfsd_path.c
+++ b/support/misc/nfsd_path.c
@@ -6,6 +6,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/vfs.h>
+#include <fcntl.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -14,6 +15,7 @@
 #include "xmalloc.h"
 #include "xlog.h"
 #include "xstat.h"
+#include "nfslib.h"
 #include "nfsd_path.h"
 #include "workqueue.h"
 
@@ -340,3 +342,67 @@ nfsd_path_write(int fd, const char *buf, size_t len)
 		return write(fd, buf, len);
 	return nfsd_run_write(nfsd_wq, fd, buf, len);
 }
+
+#if defined(HAVE_NAME_TO_HANDLE_AT)
+struct nfsd_handle_data {
+	int fd;
+	const char *path;
+	struct file_handle *fh;
+	int *mount_id;
+	int flags;
+	int ret;
+	int err;
+};
+
+static void
+nfsd_name_to_handle_func(void *data)
+{
+	struct nfsd_handle_data *d = data;
+
+	d->ret = name_to_handle_at(d->fd, d->path,
+			d->fh, d->mount_id, d->flags);
+	if (d->ret < 0)
+		d->err = errno;
+}
+
+static int
+nfsd_run_name_to_handle_at(struct xthread_workqueue *wq,
+		int fd, const char *path, struct file_handle *fh,
+		int *mount_id, int flags)
+{
+	struct nfsd_handle_data data = {
+		fd,
+		path,
+		fh,
+		mount_id,
+		flags,
+		0,
+		0
+	};
+
+	xthread_work_run_sync(wq, nfsd_name_to_handle_func, &data);
+	if (data.ret < 0)
+		errno = data.err;
+	return data.ret;
+}
+
+int
+nfsd_name_to_handle_at(int fd, const char *path, struct file_handle *fh,
+		int *mount_id, int flags)
+{
+	if (!nfsd_wq)
+		return name_to_handle_at(fd, path, fh, mount_id, flags);
+
+	return nfsd_run_name_to_handle_at(nfsd_wq, fd, path, fh,
+			mount_id, flags);
+}
+#else
+int
+nfsd_name_to_handle_at(int UNUSED(fd), const char *UNUSED(path),
+		struct file_handle *UNUSED(fh),
+		int *UNUSED(mount_id), int UNUSED(flags))
+{
+	errno = ENOSYS;
+	return -1;
+}
+#endif
-- 
2.25.2