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Groups > linux.kernel > #1665968

[PATCH 14/27] VFS: Add a sample program for fsopen/fsmount [ver #5]

From David Howells <dhowells@redhat.com>
Newsgroups linux.kernel
Subject [PATCH 14/27] VFS: Add a sample program for fsopen/fsmount [ver #5]
Date 2017-06-14 17:20 +0200
Message-ID <tSifp-6QJ-63@gated-at.bofh.it> (permalink)
References <tSifn-6QJ-7@gated-at.bofh.it>
Organization Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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Add a sample program for driving fsopen/fsmount.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 samples/fsmount/test-fsmount.c |   92 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 samples/fsmount/test-fsmount.c

diff --git a/samples/fsmount/test-fsmount.c b/samples/fsmount/test-fsmount.c
new file mode 100644
index 000000000000..30caad8e05a3
--- /dev/null
+++ b/samples/fsmount/test-fsmount.c
@@ -0,0 +1,92 @@
+/* fd-based mount test.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#define PR_ERRMSG_ENABLE		48
+#define PR_ERRMSG_READ			49
+
+#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0)
+
+static __attribute__((noreturn))
+void mount_error(int fd, const char *s)
+{
+	char buf[4096];
+	int err, n, perr;
+
+	do {
+		err = errno;
+		errno = 0;
+		n = prctl(PR_ERRMSG_READ, buf, sizeof(buf));
+		perr = errno;
+		errno = err;
+		if (n > 0) {
+			fprintf(stderr, "Error: '%s': %*.*s: %m\n", s, n, n, buf);
+		} else {
+			fprintf(stderr, "%s: %m\n", s);
+		}
+	} while (perr == 0);
+	exit(1);
+}
+
+#define E_write(fd, s)							\
+	do {								\
+		if (write(fd, s, sizeof(s) - 1) == -1)			\
+			mount_error(fd, s);				\
+	} while (0)
+
+static inline int fsopen(const char *fs_name, int reserved, int flags)
+{
+	return syscall(333, fs_name, reserved, flags);
+}
+
+static inline int fsmount(int fsfd, int dfd, const char *path,
+			  unsigned int at_flags, unsigned int flags)
+{
+	return syscall(334, fsfd, dfd, path, at_flags, flags);
+}
+
+int main()
+{
+	int mfd;
+
+	if (prctl(PR_ERRMSG_ENABLE, 1) < 0) {
+		perror("prctl/en");
+		exit(1);
+	}
+
+	/* Mount an NFS filesystem */
+	mfd = fsopen("nfs4", -1, 0);
+	if (mfd == -1) {
+		perror("fsopen");
+		exit(1);
+	}
+
+	E_write(mfd, "s warthog:/data");
+	E_write(mfd, "o fsc");
+	E_write(mfd, "o sync");
+	E_write(mfd, "o intr");
+	E_write(mfd, "o vers=4.2");
+	E_write(mfd, "o addr=90.155.74.18");
+	E_write(mfd, "o clientaddr=90.155.74.21");
+	E_write(mfd, "x create");
+	if (fsmount(mfd, AT_FDCWD, "/mnt", 0, 0) < 0)
+		mount_error(mfd, "fsmount");
+	E(close(mfd));
+
+	exit(0);
+}

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Thread

[RFC][PATCH 00/27] VFS: Introduce filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 11/27] VFS: Remove unused code after filesystem context  changes [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 20/27] NFS: Split nfs_parse_mount_options() [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 03/27] VFS: Make get_mnt_ns() return the namespace [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
    Re: [PATCH 03/27] VFS: Make get_mnt_ns() return the namespace [ver  #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 11:20 +0200
  [PATCH 27/27] kernfs, sysfs, cgroup: Support fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
    Re: [PATCH 27/27] kernfs, sysfs, cgroup: Support fs_context [ver #5] Tejun Heo <tj@kernel.org> - 2017-06-14 20:00 +0200
    Re: [PATCH 27/27] ... and the intel_rdt driver David Howells <dhowells@redhat.com> - 2017-06-15 00:40 +0200
  [PATCH 26/27] cpuset: Use fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 16/27] proc: Add fs_context support to procfs [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
    Re: [PATCH 16/27] proc: Add fs_context support to procfs [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 12:20 +0200
  [PATCH 01/27] Provide a function to create a NUL-terminated string  from unterminated data [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 09/27] VFS: Add LSM hooks for filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
    Re: [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 12:10 +0200
      Re: [PATCH 25/27] ipc: Convert mqueue fs to fs_context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-15 16:50 +0200
  [PATCH 23/27] NFS: Do some tidying of the parsing code [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 22/27] NFS: Add a small buffer in nfs_fs_context to avoid  string dup [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 14/27] VFS: Add a sample program for fsopen/fsmount [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 02/27] VFS: Clean up whitespace in fs/namespace.c and  fs/super.c [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 04/27] VFS: Make get_filesystem() return the affected  filesystem [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 18/27] NFS: Constify mount argument match tables [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:20 +0200
  [PATCH 05/27] VFS: Provide empty name qstr [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
  [PATCH 15/27] procfs: Move proc_fill_super() to fs/proc/root.c [ver  #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
  [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem  context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
    Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem  context [ver #5] Randy Dunlap <rdunlap@infradead.org> - 2017-06-14 20:10 +0200
      Updated docs David Howells <dhowells@redhat.com> - 2017-06-15 01:00 +0200
        Re: Updated docs Randy Dunlap <rdunlap@infradead.org> - 2017-06-15 04:00 +0200
    Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem  context [ver #5] Casey Schaufler <casey@schaufler-ca.com> - 2017-06-14 22:10 +0200
      Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 22:50 +0200
        Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem  context [ver #5] Casey Schaufler <casey@schaufler-ca.com> - 2017-06-14 23:00 +0200
          Re: [PATCH 08/27] VFS: Introduce the structs and doc for a  filesystem context [ver #5] Theodore Ts'o <tytso@mit.edu> - 2017-06-17 12:00 +0200
            Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-17 16:20 +0200
              Re: [PATCH 08/27] VFS: Introduce the structs and doc for a  filesystem context [ver #5] Jeff Layton <jlayton@redhat.com> - 2017-06-17 17:00 +0200
                Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem  context [ver #5] Randy Dunlap <rdunlap@infradead.org> - 2017-06-17 17:20 +0200
                Re: [PATCH 08/27] VFS: Introduce the structs and doc for a filesystem context [ver #5] David Howells <dhowells@redhat.com> - 2017-06-19 09:50 +0200
  [PATCH 21/27] NFS: Deindent nfs_fs_context_parse_option() [ver #5] David Howells <dhowells@redhat.com> - 2017-06-14 17:30 +0200
  Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from  internal superblock flags [ver #5] Al Viro <viro@ZenIV.linux.org.uk> - 2017-06-15 11:50 +0200
    Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from  internal superblock flags [ver #5] Christoph Hellwig <hch@infradead.org> - 2017-06-16 11:10 +0200
      Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] David Howells <dhowells@redhat.com> - 2017-06-16 17:00 +0200
        Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from  internal superblock flags [ver #5] Christoph Hellwig <hch@infradead.org> - 2017-06-16 18:00 +0200
          Re: [PATCH 07/27] VFS: Differentiate mount flags (MS_*) from internal superblock flags [ver #5] David Howells <dhowells@redhat.com> - 2017-06-16 18:00 +0200

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