311 lines
9.5 KiB
C
311 lines
9.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1995, 1996 Gero Kuhlmann <gero@gkminix.han.de>
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*
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* Allow an NFS filesystem to be mounted as root. The way this works is:
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* (1) Use the IP autoconfig mechanism to set local IP addresses and routes.
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* (2) Construct the device string and the options string using DHCP
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* option 17 and/or kernel command line options.
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* (3) When mount_root() sets up the root file system, pass these strings
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* to the NFS client's regular mount interface via sys_mount().
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*
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*
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* Changes:
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*
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* Alan Cox : Removed get_address name clash with FPU.
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* Alan Cox : Reformatted a bit.
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* Gero Kuhlmann : Code cleanup
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* Michael Rausch : Fixed recognition of an incoming RARP answer.
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* Martin Mares : (2.0) Auto-configuration via BOOTP supported.
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* Martin Mares : Manual selection of interface & BOOTP/RARP.
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* Martin Mares : Using network routes instead of host routes,
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* allowing the default configuration to be used
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* for normal operation of the host.
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* Martin Mares : Randomized timer with exponential backoff
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* installed to minimize network congestion.
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* Martin Mares : Code cleanup.
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* Martin Mares : (2.1) BOOTP and RARP made configuration options.
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* Martin Mares : Server hostname generation fixed.
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* Gerd Knorr : Fixed wired inode handling
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* Martin Mares : (2.2) "0.0.0.0" addresses from command line ignored.
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* Martin Mares : RARP replies not tested for server address.
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* Gero Kuhlmann : (2.3) Some bug fixes and code cleanup again (please
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* send me your new patches _before_ bothering
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* Linus so that I don' always have to cleanup
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* _afterwards_ - thanks)
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* Gero Kuhlmann : Last changes of Martin Mares undone.
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* Gero Kuhlmann : RARP replies are tested for specified server
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* again. However, it's now possible to have
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* different RARP and NFS servers.
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* Gero Kuhlmann : "0.0.0.0" addresses from command line are
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* now mapped to INADDR_NONE.
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* Gero Kuhlmann : Fixed a bug which prevented BOOTP path name
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* from being used (thanks to Leo Spiekman)
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* Andy Walker : Allow to specify the NFS server in nfs_root
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* without giving a path name
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* Swen Thümmler : Allow to specify the NFS options in nfs_root
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* without giving a path name. Fix BOOTP request
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* for domainname (domainname is NIS domain, not
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* DNS domain!). Skip dummy devices for BOOTP.
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* Jacek Zapala : Fixed a bug which prevented server-ip address
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* from nfsroot parameter from being used.
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* Olaf Kirch : Adapted to new NFS code.
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* Jakub Jelinek : Free used code segment.
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* Marko Kohtala : Fixed some bugs.
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* Martin Mares : Debug message cleanup
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* Martin Mares : Changed to use the new generic IP layer autoconfig
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* code. BOOTP and RARP moved there.
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* Martin Mares : Default path now contains host name instead of
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* host IP address (but host name defaults to IP
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* address anyway).
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* Martin Mares : Use root_server_addr appropriately during setup.
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* Martin Mares : Rewrote parameter parsing, now hopefully giving
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* correct overriding.
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* Trond Myklebust : Add in preliminary support for NFSv3 and TCP.
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* Fix bug in root_nfs_addr(). nfs_data.namlen
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* is NOT for the length of the hostname.
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* Hua Qin : Support for mounting root file system via
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* NFS over TCP.
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* Fabian Frederick: Option parser rebuilt (using parser lib)
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* Chuck Lever : Use super.c's text-based mount option parsing
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* Chuck Lever : Add "nfsrootdebug".
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*/
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#include <linux/types.h>
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#include <linux/string.h>
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#include <linux/init.h>
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#include <linux/nfs.h>
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#include <linux/nfs_fs.h>
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#include <linux/utsname.h>
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#include <linux/root_dev.h>
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#include <net/ipconfig.h>
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#include "internal.h"
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#define NFSDBG_FACILITY NFSDBG_ROOT
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/* Default path we try to mount. "%s" gets replaced by our IP address */
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#define NFS_ROOT "/tftpboot/%s"
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/* Default NFSROOT mount options. */
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#define NFS_DEF_OPTIONS "vers=2,udp,rsize=4096,wsize=4096"
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/* Parameters passed from the kernel command line */
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static char nfs_root_parms[NFS_MAXPATHLEN + 1] __initdata = "";
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/* Text-based mount options passed to super.c */
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static char nfs_root_options[256] __initdata = NFS_DEF_OPTIONS;
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/* Address of NFS server */
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static __be32 servaddr __initdata = htonl(INADDR_NONE);
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/* Name of directory to mount */
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static char nfs_export_path[NFS_MAXPATHLEN + 1] __initdata = "";
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/* server:export path string passed to super.c */
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static char nfs_root_device[NFS_MAXPATHLEN + 1] __initdata = "";
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#ifdef NFS_DEBUG
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/*
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* When the "nfsrootdebug" kernel command line option is specified,
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* enable debugging messages for NFSROOT.
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*/
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static int __init nfs_root_debug(char *__unused)
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{
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nfs_debug |= NFSDBG_ROOT | NFSDBG_MOUNT;
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return 1;
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}
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__setup("nfsrootdebug", nfs_root_debug);
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#endif
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/*
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* Parse NFS server and directory information passed on the kernel
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* command line.
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*
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* nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>]
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*
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* If there is a "%s" token in the <root-dir> string, it is replaced
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* by the ASCII-representation of the client's IP address.
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*/
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static int __init nfs_root_setup(char *line)
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{
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ROOT_DEV = Root_NFS;
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if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) {
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strlcpy(nfs_root_parms, line, sizeof(nfs_root_parms));
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} else {
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size_t n = strlen(line) + sizeof(NFS_ROOT) - 1;
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if (n >= sizeof(nfs_root_parms))
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line[sizeof(nfs_root_parms) - sizeof(NFS_ROOT) - 2] = '\0';
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sprintf(nfs_root_parms, NFS_ROOT, line);
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}
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/*
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* Extract the IP address of the NFS server containing our
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* root file system, if one was specified.
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*
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* Note: root_nfs_parse_addr() removes the server-ip from
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* nfs_root_parms, if it exists.
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*/
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root_server_addr = root_nfs_parse_addr(nfs_root_parms);
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return 1;
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}
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__setup("nfsroot=", nfs_root_setup);
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static int __init root_nfs_copy(char *dest, const char *src,
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const size_t destlen)
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{
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if (strlcpy(dest, src, destlen) > destlen)
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return -1;
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return 0;
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}
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static int __init root_nfs_cat(char *dest, const char *src,
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const size_t destlen)
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{
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size_t len = strlen(dest);
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if (len && dest[len - 1] != ',')
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if (strlcat(dest, ",", destlen) > destlen)
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return -1;
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if (strlcat(dest, src, destlen) > destlen)
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return -1;
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return 0;
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}
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/*
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* Parse out root export path and mount options from
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* passed-in string @incoming.
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*
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* Copy the export path into @exppath.
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*/
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static int __init root_nfs_parse_options(char *incoming, char *exppath,
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const size_t exppathlen)
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{
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char *p;
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/*
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* Set the NFS remote path
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*/
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p = strsep(&incoming, ",");
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if (*p != '\0' && strcmp(p, "default") != 0)
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if (root_nfs_copy(exppath, p, exppathlen))
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return -1;
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/*
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* @incoming now points to the rest of the string; if it
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* contains something, append it to our root options buffer
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*/
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if (incoming != NULL && *incoming != '\0')
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if (root_nfs_cat(nfs_root_options, incoming,
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sizeof(nfs_root_options)))
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return -1;
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return 0;
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}
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/*
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* Decode the export directory path name and NFS options from
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* the kernel command line. This has to be done late in order to
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* use a dynamically acquired client IP address for the remote
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* root directory path.
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*
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* Returns zero if successful; otherwise -1 is returned.
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*/
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static int __init root_nfs_data(char *cmdline)
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{
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char mand_options[sizeof("nolock,addr=") + INET_ADDRSTRLEN + 1];
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int len, retval = -1;
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char *tmp = NULL;
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const size_t tmplen = sizeof(nfs_export_path);
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tmp = kzalloc(tmplen, GFP_KERNEL);
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if (tmp == NULL)
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goto out_nomem;
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strcpy(tmp, NFS_ROOT);
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if (root_server_path[0] != '\0') {
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dprintk("Root-NFS: DHCPv4 option 17: %s\n",
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root_server_path);
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if (root_nfs_parse_options(root_server_path, tmp, tmplen))
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goto out_optionstoolong;
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}
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if (cmdline[0] != '\0') {
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dprintk("Root-NFS: nfsroot=%s\n", cmdline);
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if (root_nfs_parse_options(cmdline, tmp, tmplen))
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goto out_optionstoolong;
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}
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/*
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* Append mandatory options for nfsroot so they override
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* what has come before
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*/
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snprintf(mand_options, sizeof(mand_options), "nolock,addr=%pI4",
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&servaddr);
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if (root_nfs_cat(nfs_root_options, mand_options,
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sizeof(nfs_root_options)))
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goto out_optionstoolong;
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/*
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* Set up nfs_root_device. For NFS mounts, this looks like
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*
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* server:/path
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*
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* At this point, utsname()->nodename contains our local
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* IP address or hostname, set by ipconfig. If "%s" exists
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* in tmp, substitute the nodename, then shovel the whole
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* mess into nfs_root_device.
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*/
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len = snprintf(nfs_export_path, sizeof(nfs_export_path),
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tmp, utsname()->nodename);
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if (len >= (int)sizeof(nfs_export_path))
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goto out_devnametoolong;
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len = snprintf(nfs_root_device, sizeof(nfs_root_device),
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"%pI4:%s", &servaddr, nfs_export_path);
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if (len >= (int)sizeof(nfs_root_device))
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goto out_devnametoolong;
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retval = 0;
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out:
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kfree(tmp);
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return retval;
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out_nomem:
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printk(KERN_ERR "Root-NFS: could not allocate memory\n");
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goto out;
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out_optionstoolong:
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printk(KERN_ERR "Root-NFS: mount options string too long\n");
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goto out;
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out_devnametoolong:
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printk(KERN_ERR "Root-NFS: root device name too long.\n");
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goto out;
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}
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/**
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* nfs_root_data - Return prepared 'data' for NFSROOT mount
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* @root_device: OUT: address of string containing NFSROOT device
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* @root_data: OUT: address of string containing NFSROOT mount options
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*
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* Returns zero and sets @root_device and @root_data if successful,
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* otherwise -1 is returned.
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*/
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int __init nfs_root_data(char **root_device, char **root_data)
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{
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servaddr = root_server_addr;
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if (servaddr == htonl(INADDR_NONE)) {
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printk(KERN_ERR "Root-NFS: no NFS server address\n");
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return -1;
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}
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if (root_nfs_data(nfs_root_parms) < 0)
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return -1;
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*root_device = nfs_root_device;
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*root_data = nfs_root_options;
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return 0;
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}
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