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- <html>
- <head>
- <title>NFS Client How-To</title>
- </head>
- <body background="backgd.gif">
- <hr><hr>
- <table width ="100%">
- <tr align="center" bgcolor="#e4e4e4">
- <td>
- <h1><big><font color="#3c34ec"><i>NFS Client How-To</i></font></big></h1>
- <p>Last Updated: June 18, 2012</p>
- </td>
- </tr>
- </table>
- <hr><hr>
- <table width ="100%">
- <tr bgcolor="#e4e4e4">
- <td>
- <h1>Table of Contents</h1>
- </td>
- </tr>
- </table>
- <center><table width ="80%">
- <tr>
- <td>
- <table>
- <tr>
- <td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
- <td>
- <a href="#nfsconfiguration">Adding NFS to the NuttX Configuration</a>
- </td>
- </tr>
- </table>
- <table>
- <tr>
- <td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
- <td>
- <a href="#mountinterface">Mount Interface</a>
- </td>
- </tr>
- </table>
- <table>
- <tr>
- <td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
- <td>
- <a href="#nfsmount">NFS Mount Command</a>
- </td>
- </tr>
- </table>
- <table>
- <tr>
- <td valign="top" width="22"><img height="20" width="20" src="favicon.ico"></td>
- <td>
- <a href="#serverconfig">Configuring the NFS server (Ubuntu)</a>
- </td>
- </tr>
- </table>
- </td>
- </tr>
- </table></center>
- <table width ="100%">
- <tr bgcolor="#e4e4e4">
- <td>
- <a name="nfsconfiguration"><h1>Adding NFS to the NuttX Configuration</h1></a>
- </td>
- </tr>
- </table>
- <p>
- The NFS client is easily added to your configuration:
- You simply need to add <code>CONFIG_NFS</code> to your <code>nuttx/.config</code> file.
- There are, however, a few dependencies on other system settings:
- </p>
- <ol>
- <li>
- First, there are things that you must configure in order to be able to use any file system:
- </li>
- <ul>
- <li>
- <code>CONFIG_DISABLE_MOUNTPOINT=n</code>. You must include support for mount points in the pseudo-file system.
- </li>
- </ul>
- <li>
- And there are several dependencies on the networking configuration.
- At a minimum, you need to have the following selections:
- </li>
- <ul>
- <li>
- <code>CONFIG_NET=y</code>. General networking support.
- </li>
- <li>
- <code>CONFIG_NET_UDP=y</code>. Support for UDP.
- </li>
- </ul>
- </ol>
- <table width ="100%">
- <tr bgcolor="#e4e4e4">
- <td>
- <a name="mountinterface"><h1>Mount Interface</h1></a>
- </td>
- </tr>
- </table>
- <p>
- A low-level, C-callable interface is provided to mount a file system.
- That interface is called <code>mount()</code> and is mentioned in the <a href="NuttxPortingGuide.html#NxFileSystem"><code>porting guide</code></a> and is prototyped in the header file <code>include/sys/mount.h</code>:
- </p>
- <ul><pre>
- int mount(const char *source, const char *target, const char *filesystemtype, unsigned long mountflags, const void *data);
- </pre></ul>
- <p>
- <b>Synopsis</b>:
- <code>mount()</code> attaches the filesystem specified by the <code>source</code> block device name into the root file system at the path specified by <code>target</code>.
- </p>
- <p>
- <b>Input Parameters</b>:
- <ul>
- <li><code>source</code>. A null-terminated string providing the fill path to a block driver in the NuttX pseudo-file system.
- <li><code>target</code>. The location in the NuttX pseudo-file system where the volume will be mounted.
- <li><code>filesystemtype</code>. A string identifying the type of file system to use.
- <li><code>mountflags</code>. Various flags that can be used to qualify how the file system is mounted.
- <li><code>data</code>. Opaque data that is passed to the file system with the mount occurs.
- </ul>
- </p>
- <p>
- <b>Returned Values</b>
- Zero is returned on success; -1 is returned on an error and <code>errno</code> is set appropriately:
- <ul>
- <li><code>EACCES</code>.
- A component of a path was not searchable or mounting a read-only filesystem was attempted without giving the <code>MS_RDONLY</code> flag.
- </li>
- <li><code>EBUSY</code>.
- <code>source</code> is already mounted.
- </li>
- <li><code>EFAULT</code>.
- One of the pointer arguments points outside the user address space.
- </li>
- <li><code>EINVAL</code>.
- <code>source</code> had an invalid superblock.
- </li>
- <li><code>ENODEV</code>.
- <code>filesystemtype</code> not configured
- </li>
- <li><code>ENOENT</code>.
- A pathname was empty or had a nonexistent component.
- </li>
- <li><code>ENOMEM</code>.
- Could not allocate a memory to copy filenames or data into.
- </li>
- <li><code>ENOTBLK</code>.
- <code>source</code> is not a block device
- </li>
- </ul>
- </p>
- <p>
- This same interface can be used to mount a remote, NFS file system using some special parameters.
- The NFS mount differs from the <i>normal</i> file system mount in that: (1) there is no block driver for the NFS file system, and (2) special parameters must be passed as <code>data</code> to describe the remote NFS server.
- Thus the following code snippet might represent how an NFS file system is mounted:
- </p>
- <ul><pre>
- #include <sys/mount.h>
- #include <nuttx/fs/nfs.h>
- struct nfs_args data;
- char *mountpoint;
- ret = mount(NULL, mountpoint, string "nfs", 0, (FAR void *)&data);
- </pre></ul>
- <p>
- NOTE that: (1) the block driver parameter is <code>NULL</code>.
- The <code>mount()</code> is smart enough to know that no block driver is needed with the NFS file system.
- (2) The NFS file system is identified with the simple string "nfs"
- (3) A reference to <code>struct nfs_args</code> is passed as an NFS-specific argument.
- </p>
- <p>
- The NFS-specific interface is described in the file <code>include/nuttx/fs/nfs.h</code>.
- There you can see that <code>struct nfs_args</code> is defined as:
- </p>
- <ul><pre>
- struct nfs_args
- {
- uint8_t addrlen; /* Length of address */
- uint8_t sotype; /* Socket type */
- uint8_t flags; /* Flags, determines if following are valid: */
- uint8_t timeo; /* Time value in deciseconds (with NFSMNT_TIMEO) */
- uint8_t retrans; /* Times to retry send (with NFSMNT_RETRANS) */
- uint16_t wsize; /* Write size in bytes (with NFSMNT_WSIZE) */
- uint16_t rsize; /* Read size in bytes (with NFSMNT_RSIZE) */
- uint16_t readdirsize; /* readdir size in bytes (with NFSMNT_READDIRSIZE) */
- char *path; /* Server's path of the directory being mount */
- struct sockaddr_storage addr; /* File server address (requires 32-bit alignment) */
- };
- </pre></ul>
- <table width ="100%">
- <tr bgcolor="#e4e4e4">
- <td>
- <a name="nfsmount"><h1>NFS Mount Command</h1></a>
- </td>
- </tr>
- </table>
- <p>
- The <a href="NuttShell.html">NuttShell (NSH)</a> also supports a command called <code>nfsmount</code>
- that can be used to mount a remote file system via the NSH command line.
- </p>
- <p>
- <b>Command Syntax:</b>
- </p>
- <ul><pre>
- nfsmount <server-address> <mount-point> <remote-path>
- </pre></ul>
- <p>
- <b>Synopsis</b>.
- The <code>nfsmount</code> command mounts a network file system in the NuttX pseudo filesystem.
- The <code>nfsmount</code> will use NFSv3 UDP protocol to mount the remote file system.
- </p>
- <p>
- <b>Command Line Arguments</b>.
- The <code>nfsmount</code> takes three arguments:
- </p>
- <ol>
- <li>
- The <code><server-address></code> is the IP address of the server exporting the file system you wish to mount.
- This implementation of NFS for the NuttX RTOS is only for a local area network, so the server and client must be in the same network.
- </li>
- <li>
- The <code><mount-point ></code> is the location in the NuttX pseudo filesystem where the mounted volume will appear.
- This mount point can only reside in the NuttX pseudo filesystem.
- By convention, this mount point is a subdirectory under <code>/mnt</code>.
- The mount command will create whatever pseudo directories that may be needed to complete the full path (but the full path must not already exist).
- </li>
- <li>
- The <code><remote-path></code> is the file system <code>/</code> directory being exported from server.
- This <code>/</code> directory must have been configured for exportation on the server before when the NFS server was set up.
- </li>
- </ol>
- <p>
- After the volume has been mounted in the NuttX pseudo filesystem, it may be access in the same way as other objects in the file system.
- </p>
- <p>
- <b>Example</b>.
- Suppose that the NFS server has been configured to export the directory <code>/export/shared</code>.
- The the following command would mount that file system (assuming that the target also has privileges to mount the file system).
- </p>
- <ul><pre>
- NuttShell (NSH)
- nsh> ls /mnt
- /mnt:
- nsh: ls: no such directory: /mnt
- nsh> nfsmount 10.0.0.1 /mnt/nfs /export/shared
- nsh> ls -l /mnt/nfs
- /mnt/nfs:
- drwxrwxrwx 4096 ..
- drwxrwxrwx 4096 testdir/
- -rw-rw-rw- 6 ctest.txt
- -rw-r--r-- 15 btest.txt
- drwxrwxrwx 4096 .
- nsh> echo "This is a test" >/mnt/nfs/testdir/testfile.txt
- nsh> ls -l /mnt/nfs/testdir
- /mnt/nfs/testdir:
- -rw-rw-rw- 21 another.txt
- drwxrwxrwx 4096 ..
- drwxrwxrwx 4096 .
- -rw-rw-rw- 16 testfile.txt
- nsh> cat /mnt/nfs/testdir/testfile.txt
- This is a test
- </pre></ul>
- <table width ="100%">
- <tr bgcolor="#e4e4e4">
- <td>
- <a name="serverconfig"><h1>Configuring the NFS server (Ubuntu)</h1></a>
- </td>
- </tr>
- </table>
- <p>
- Setting up the server will be done in two steps:
- First, setting up the configuration file for NFS, and then starting the NFS services.
- But first, you need to install the nfs server on Ubuntu with these two commands:
- </p>
- <ul><pre>
- # sudo apt-get install nfs-common</FONT>
- # sudo apt-get install nfs-kernel-server</FONT>
- </pre></ul>
- <p>
- After that, we need to make or choose the directory we want to export from the NFS server.
- In our case, we are going to make a new directory called <code>/export</code>.
- </p>
- <ul><pre>
- # sudo mkdir /export
- </pre></ul>
- <p>
- It is important that <code>/export</code> directory allow access to everyone (777 permissions) as we will be accessing the NFS share from the client with no authentication.
- </p>
- <ul><pre>
- # sudo chmod 777 /export
- </pre></ul>
- <p>
- When all this is done, we will need to edit the configuration file to set up an NFS server: <code>/etc/exports</code>.
- This file contains a list of entries;
- each entry indicates a volume that is shared and how it is shared.
- For more information for a complete description of all the setup options for this file you can check in the man pages (<code>man export</code>).</p>
- An entry in <code>/etc/exports</code> will typically look like this:
- </p>
- <ul><pre>
- directory machine1(option11,option12)
- </pre></ul>
- <p>
- So for our example we export <code>/export</code> to the client 10.0.0.2 add the entry:
- </p>
- <ul><pre>
- /export 10.0.0.2(rw)
- </pre></ul>
- <p>
- In our case we are using all the default options except for the <code>ro</code> that we replaced with <code>rw</code> so that our client will have read and write access to the directory that we are exporting.
- </p>
- </p>
- After we do all the require configurations, we are ready to start the server with the next command:
- </p>
- <ul><pre>
- # sudo /etc/init.d/nfs-kernel-server start
- </pre></ul>
- </p>
- Note: If you later decide to add more NFS exports to the /etc/exports file, you will need to either restart NFS daemon
- or run command exportfs.
- </p>
- <ul><pre>
- # sudo /etc/init.d/nfs-kernel-server start
- </pre></ul>
- <p>Or</p>
- <ul><pre>
- # exportfs -ra
- </pre></ul>
- <p>
- Now we can check if the export directory and our mount point is properly set up.
- </p>
- <ul><pre>
- # sudo showmount -e
- # sudo showmount -a
- </pre></ul>
- <p>
- And also we can verify if NFS is running in the system with:
- </p>
- <P STYLE="margin-left: 0.49in; margin-bottom: 0in; line-height: 100%">
- <ul><pre>
- # rpcinfo –p</FONT>
- program vers proto port
- 100000 2 tcp 111 portmapper
- 100000 2 udp 111 portmapper
- 100011 1 udp 749 rquotad
- 100011 2 udp 749 rquotad
- 100005 1 udp 759 mountd
- 100005 1 tcp 761 mountd
- 100005 2 udp 764 mountd
- 100005 2 tcp 766 mountd
- 100005 3 udp 769 mountd
- 100005 3 tcp 771 mountd
- 100003 2 udp 2049 nfs
- 100003 3 udp 2049 nfs
- 300019 1 tcp 830 amd
- 300019 1 udp 831 amd
- 100024 1 udp 944 status
- 100024 1 tcp 946 status
- 100021 1 udp 1042 nlockmgr
- 100021 3 udp 1042 nlockmgr
- 100021 4 udp 1042 nlockmgr
- 100021 1 tcp 1629 nlockmgr
- 100021 3 tcp 1629 nlockmgr
- 100021 4 tcp 1629 nlockmgr
- </pre></ul>
- <p>
- Now your NFS sever is sharing <code>/export</code> directory to be accessed.
- </p>
- </body>
- </html>
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