2 * Copyright (C) 1995, 1996 Gero Kuhlmann <gero@gkminix.han.de>
4 * Allow an NFS filesystem to be mounted as root. The way this works is:
5 * (1) Use the IP autoconfig mechanism to set local IP addresses and routes.
6 * (2) Construct the device string and the options string using DHCP
7 * option 17 and/or kernel command line options.
8 * (3) When mount_root() sets up the root file system, pass these strings
9 * to the NFS client's regular mount interface via sys_mount().
14 * Alan Cox : Removed get_address name clash with FPU.
15 * Alan Cox : Reformatted a bit.
16 * Gero Kuhlmann : Code cleanup
17 * Michael Rausch : Fixed recognition of an incoming RARP answer.
18 * Martin Mares : (2.0) Auto-configuration via BOOTP supported.
19 * Martin Mares : Manual selection of interface & BOOTP/RARP.
20 * Martin Mares : Using network routes instead of host routes,
21 * allowing the default configuration to be used
22 * for normal operation of the host.
23 * Martin Mares : Randomized timer with exponential backoff
24 * installed to minimize network congestion.
25 * Martin Mares : Code cleanup.
26 * Martin Mares : (2.1) BOOTP and RARP made configuration options.
27 * Martin Mares : Server hostname generation fixed.
28 * Gerd Knorr : Fixed wired inode handling
29 * Martin Mares : (2.2) "0.0.0.0" addresses from command line ignored.
30 * Martin Mares : RARP replies not tested for server address.
31 * Gero Kuhlmann : (2.3) Some bug fixes and code cleanup again (please
32 * send me your new patches _before_ bothering
33 * Linus so that I don' always have to cleanup
34 * _afterwards_ - thanks)
35 * Gero Kuhlmann : Last changes of Martin Mares undone.
36 * Gero Kuhlmann : RARP replies are tested for specified server
37 * again. However, it's now possible to have
38 * different RARP and NFS servers.
39 * Gero Kuhlmann : "0.0.0.0" addresses from command line are
40 * now mapped to INADDR_NONE.
41 * Gero Kuhlmann : Fixed a bug which prevented BOOTP path name
42 * from being used (thanks to Leo Spiekman)
43 * Andy Walker : Allow to specify the NFS server in nfs_root
44 * without giving a path name
45 * Swen Thümmler : Allow to specify the NFS options in nfs_root
46 * without giving a path name. Fix BOOTP request
47 * for domainname (domainname is NIS domain, not
48 * DNS domain!). Skip dummy devices for BOOTP.
49 * Jacek Zapala : Fixed a bug which prevented server-ip address
50 * from nfsroot parameter from being used.
51 * Olaf Kirch : Adapted to new NFS code.
52 * Jakub Jelinek : Free used code segment.
53 * Marko Kohtala : Fixed some bugs.
54 * Martin Mares : Debug message cleanup
55 * Martin Mares : Changed to use the new generic IP layer autoconfig
56 * code. BOOTP and RARP moved there.
57 * Martin Mares : Default path now contains host name instead of
58 * host IP address (but host name defaults to IP
60 * Martin Mares : Use root_server_addr appropriately during setup.
61 * Martin Mares : Rewrote parameter parsing, now hopefully giving
63 * Trond Myklebust : Add in preliminary support for NFSv3 and TCP.
64 * Fix bug in root_nfs_addr(). nfs_data.namlen
65 * is NOT for the length of the hostname.
66 * Hua Qin : Support for mounting root file system via
68 * Fabian Frederick: Option parser rebuilt (using parser lib)
69 * Chuck Lever : Use super.c's text-based mount option parsing
70 * Chuck Lever : Add "nfsrootdebug".
73 #include <linux/types.h>
74 #include <linux/string.h>
75 #include <linux/init.h>
76 #include <linux/nfs.h>
77 #include <linux/nfs_fs.h>
78 #include <linux/utsname.h>
79 #include <linux/root_dev.h>
80 #include <net/ipconfig.h>
84 #define NFSDBG_FACILITY NFSDBG_ROOT
86 /* Default path we try to mount. "%s" gets replaced by our IP address */
87 #define NFS_ROOT "/tftpboot/%s"
89 /* Default NFSROOT mount options. */
90 #define NFS_DEF_OPTIONS "udp"
92 /* Parameters passed from the kernel command line */
93 static char nfs_root_parms
[256] __initdata
= "";
95 /* Text-based mount options passed to super.c */
96 static char nfs_root_options
[256] __initdata
= NFS_DEF_OPTIONS
;
98 /* Address of NFS server */
99 static __be32 servaddr __initdata
= htonl(INADDR_NONE
);
101 /* Name of directory to mount */
102 static char nfs_export_path
[NFS_MAXPATHLEN
+ 1] __initdata
= "";
104 /* server:export path string passed to super.c */
105 static char nfs_root_device
[NFS_MAXPATHLEN
+ 1] __initdata
= "";
109 * When the "nfsrootdebug" kernel command line option is specified,
110 * enable debugging messages for NFSROOT.
112 static int __init
nfs_root_debug(char *__unused
)
114 nfs_debug
|= NFSDBG_ROOT
| NFSDBG_MOUNT
;
118 __setup("nfsrootdebug", nfs_root_debug
);
122 * Parse NFS server and directory information passed on the kernel
125 * nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
127 * If there is a "%s" token in the <root-dir> string, it is replaced
128 * by the ASCII-representation of the client's IP address.
130 static int __init
nfs_root_setup(char *line
)
134 if (line
[0] == '/' || line
[0] == ',' || (line
[0] >= '0' && line
[0] <= '9')) {
135 strlcpy(nfs_root_parms
, line
, sizeof(nfs_root_parms
));
137 size_t n
= strlen(line
) + sizeof(NFS_ROOT
) - 1;
138 if (n
>= sizeof(nfs_root_parms
))
139 line
[sizeof(nfs_root_parms
) - sizeof(NFS_ROOT
) - 2] = '\0';
140 sprintf(nfs_root_parms
, NFS_ROOT
, line
);
144 * Extract the IP address of the NFS server containing our
145 * root file system, if one was specified.
147 * Note: root_nfs_parse_addr() removes the server-ip from
148 * nfs_root_parms, if it exists.
150 root_server_addr
= root_nfs_parse_addr(nfs_root_parms
);
155 __setup("nfsroot=", nfs_root_setup
);
157 static int __init
root_nfs_copy(char *dest
, const char *src
,
158 const size_t destlen
)
160 if (strlcpy(dest
, src
, destlen
) > destlen
)
165 static int __init
root_nfs_cat(char *dest
, const char *src
,
166 const size_t destlen
)
168 size_t len
= strlen(dest
);
170 if (len
&& dest
[len
- 1] != ',')
171 if (strlcat(dest
, ",", destlen
) > destlen
)
174 if (strlcat(dest
, src
, destlen
) > destlen
)
180 * Parse out root export path and mount options from
181 * passed-in string @incoming.
183 * Copy the export path into @exppath.
185 static int __init
root_nfs_parse_options(char *incoming
, char *exppath
,
186 const size_t exppathlen
)
191 * Set the NFS remote path
193 p
= strsep(&incoming
, ",");
194 if (*p
!= '\0' && strcmp(p
, "default") != 0)
195 if (root_nfs_copy(exppath
, p
, exppathlen
))
199 * @incoming now points to the rest of the string; if it
200 * contains something, append it to our root options buffer
202 if (incoming
!= NULL
&& *incoming
!= '\0')
203 if (root_nfs_cat(nfs_root_options
, incoming
,
204 sizeof(nfs_root_options
)))
210 * Decode the export directory path name and NFS options from
211 * the kernel command line. This has to be done late in order to
212 * use a dynamically acquired client IP address for the remote
213 * root directory path.
215 * Returns zero if successful; otherwise -1 is returned.
217 static int __init
root_nfs_data(char *cmdline
)
219 char mand_options
[sizeof("nolock,addr=") + INET_ADDRSTRLEN
+ 1];
220 int len
, retval
= -1;
222 const size_t tmplen
= sizeof(nfs_export_path
);
224 tmp
= kzalloc(tmplen
, GFP_KERNEL
);
227 strcpy(tmp
, NFS_ROOT
);
229 if (root_server_path
[0] != '\0') {
230 dprintk("Root-NFS: DHCPv4 option 17: %s\n",
232 if (root_nfs_parse_options(root_server_path
, tmp
, tmplen
))
233 goto out_optionstoolong
;
236 if (cmdline
[0] != '\0') {
237 dprintk("Root-NFS: nfsroot=%s\n", cmdline
);
238 if (root_nfs_parse_options(cmdline
, tmp
, tmplen
))
239 goto out_optionstoolong
;
243 * Append mandatory options for nfsroot so they override
244 * what has come before
246 snprintf(mand_options
, sizeof(mand_options
), "nolock,addr=%pI4",
248 if (root_nfs_cat(nfs_root_options
, mand_options
,
249 sizeof(nfs_root_options
)))
250 goto out_optionstoolong
;
253 * Set up nfs_root_device. For NFS mounts, this looks like
257 * At this point, utsname()->nodename contains our local
258 * IP address or hostname, set by ipconfig. If "%s" exists
259 * in tmp, substitute the nodename, then shovel the whole
260 * mess into nfs_root_device.
262 len
= snprintf(nfs_export_path
, sizeof(nfs_export_path
),
263 tmp
, utsname()->nodename
);
264 if (len
> (int)sizeof(nfs_export_path
))
265 goto out_devnametoolong
;
266 len
= snprintf(nfs_root_device
, sizeof(nfs_root_device
),
267 "%pI4:%s", &servaddr
, nfs_export_path
);
268 if (len
> (int)sizeof(nfs_root_device
))
269 goto out_devnametoolong
;
277 printk(KERN_ERR
"Root-NFS: could not allocate memory\n");
280 printk(KERN_ERR
"Root-NFS: mount options string too long\n");
283 printk(KERN_ERR
"Root-NFS: root device name too long.\n");
288 * nfs_root_data - Return prepared 'data' for NFSROOT mount
289 * @root_device: OUT: address of string containing NFSROOT device
290 * @root_data: OUT: address of string containing NFSROOT mount options
292 * Returns zero and sets @root_device and @root_data if successful,
293 * otherwise -1 is returned.
295 int __init
nfs_root_data(char **root_device
, char **root_data
)
297 servaddr
= root_server_addr
;
298 if (servaddr
== htonl(INADDR_NONE
)) {
299 printk(KERN_ERR
"Root-NFS: no NFS server address\n");
303 if (root_nfs_data(nfs_root_parms
) < 0)
306 *root_device
= nfs_root_device
;
307 *root_data
= nfs_root_options
;