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316 lines
9.7 KiB
316 lines
9.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright (C) 1995, 1996 Gero Kuhlmann <[email protected]> |
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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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|
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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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#if defined(CONFIG_NFS_V2) |
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#define NFS_DEF_OPTIONS "vers=2,tcp,rsize=4096,wsize=4096" |
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#elif defined(CONFIG_NFS_V3) |
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#define NFS_DEF_OPTIONS "vers=3,tcp,rsize=4096,wsize=4096" |
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#else |
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#define NFS_DEF_OPTIONS "vers=4,tcp,rsize=4096,wsize=4096" |
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#endif |
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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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