diff options
Diffstat (limited to 'kernel/fs/nfs/nfsroot.c')
| -rw-r--r-- | kernel/fs/nfs/nfsroot.c | 309 |
1 files changed, 309 insertions, 0 deletions
diff --git a/kernel/fs/nfs/nfsroot.c b/kernel/fs/nfs/nfsroot.c new file mode 100644 index 000000000..9bc9f04fb --- /dev/null +++ b/kernel/fs/nfs/nfsroot.c @@ -0,0 +1,309 @@ +/* + * Copyright (C) 1995, 1996 Gero Kuhlmann <gero@gkminix.han.de> + * + * Allow an NFS filesystem to be mounted as root. The way this works is: + * (1) Use the IP autoconfig mechanism to set local IP addresses and routes. + * (2) Construct the device string and the options string using DHCP + * option 17 and/or kernel command line options. + * (3) When mount_root() sets up the root file system, pass these strings + * to the NFS client's regular mount interface via sys_mount(). + * + * + * Changes: + * + * Alan Cox : Removed get_address name clash with FPU. + * Alan Cox : Reformatted a bit. + * Gero Kuhlmann : Code cleanup + * Michael Rausch : Fixed recognition of an incoming RARP answer. + * Martin Mares : (2.0) Auto-configuration via BOOTP supported. + * Martin Mares : Manual selection of interface & BOOTP/RARP. + * Martin Mares : Using network routes instead of host routes, + * allowing the default configuration to be used + * for normal operation of the host. + * Martin Mares : Randomized timer with exponential backoff + * installed to minimize network congestion. + * Martin Mares : Code cleanup. + * Martin Mares : (2.1) BOOTP and RARP made configuration options. + * Martin Mares : Server hostname generation fixed. + * Gerd Knorr : Fixed wired inode handling + * Martin Mares : (2.2) "0.0.0.0" addresses from command line ignored. + * Martin Mares : RARP replies not tested for server address. + * Gero Kuhlmann : (2.3) Some bug fixes and code cleanup again (please + * send me your new patches _before_ bothering + * Linus so that I don' always have to cleanup + * _afterwards_ - thanks) + * Gero Kuhlmann : Last changes of Martin Mares undone. + * Gero Kuhlmann : RARP replies are tested for specified server + * again. However, it's now possible to have + * different RARP and NFS servers. + * Gero Kuhlmann : "0.0.0.0" addresses from command line are + * now mapped to INADDR_NONE. + * Gero Kuhlmann : Fixed a bug which prevented BOOTP path name + * from being used (thanks to Leo Spiekman) + * Andy Walker : Allow to specify the NFS server in nfs_root + * without giving a path name + * Swen Thümmler : Allow to specify the NFS options in nfs_root + * without giving a path name. Fix BOOTP request + * for domainname (domainname is NIS domain, not + * DNS domain!). Skip dummy devices for BOOTP. + * Jacek Zapala : Fixed a bug which prevented server-ip address + * from nfsroot parameter from being used. + * Olaf Kirch : Adapted to new NFS code. + * Jakub Jelinek : Free used code segment. + * Marko Kohtala : Fixed some bugs. + * Martin Mares : Debug message cleanup + * Martin Mares : Changed to use the new generic IP layer autoconfig + * code. BOOTP and RARP moved there. + * Martin Mares : Default path now contains host name instead of + * host IP address (but host name defaults to IP + * address anyway). + * Martin Mares : Use root_server_addr appropriately during setup. + * Martin Mares : Rewrote parameter parsing, now hopefully giving + * correct overriding. + * Trond Myklebust : Add in preliminary support for NFSv3 and TCP. + * Fix bug in root_nfs_addr(). nfs_data.namlen + * is NOT for the length of the hostname. + * Hua Qin : Support for mounting root file system via + * NFS over TCP. + * Fabian Frederick: Option parser rebuilt (using parser lib) + * Chuck Lever : Use super.c's text-based mount option parsing + * Chuck Lever : Add "nfsrootdebug". + */ + +#include <linux/types.h> +#include <linux/string.h> +#include <linux/init.h> +#include <linux/nfs.h> +#include <linux/nfs_fs.h> +#include <linux/utsname.h> +#include <linux/root_dev.h> +#include <net/ipconfig.h> + +#include "internal.h" + +#define NFSDBG_FACILITY NFSDBG_ROOT + +/* Default path we try to mount. "%s" gets replaced by our IP address */ +#define NFS_ROOT "/tftpboot/%s" + +/* Default NFSROOT mount options. */ +#define NFS_DEF_OPTIONS "vers=2,udp,rsize=4096,wsize=4096" + +/* Parameters passed from the kernel command line */ +static char nfs_root_parms[256] __initdata = ""; + +/* Text-based mount options passed to super.c */ +static char nfs_root_options[256] __initdata = NFS_DEF_OPTIONS; + +/* Address of NFS server */ +static __be32 servaddr __initdata = htonl(INADDR_NONE); + +/* Name of directory to mount */ +static char nfs_export_path[NFS_MAXPATHLEN + 1] __initdata = ""; + +/* server:export path string passed to super.c */ +static char nfs_root_device[NFS_MAXPATHLEN + 1] __initdata = ""; + +#ifdef NFS_DEBUG +/* + * When the "nfsrootdebug" kernel command line option is specified, + * enable debugging messages for NFSROOT. + */ +static int __init nfs_root_debug(char *__unused) +{ + nfs_debug |= NFSDBG_ROOT | NFSDBG_MOUNT; + return 1; +} + +__setup("nfsrootdebug", nfs_root_debug); +#endif + +/* + * Parse NFS server and directory information passed on the kernel + * command line. + * + * nfsroot=[<server-ip>:]<root-dir>[,<nfs-options>] + * + * If there is a "%s" token in the <root-dir> string, it is replaced + * by the ASCII-representation of the client's IP address. + */ +static int __init nfs_root_setup(char *line) +{ + ROOT_DEV = Root_NFS; + + if (line[0] == '/' || line[0] == ',' || (line[0] >= '0' && line[0] <= '9')) { + strlcpy(nfs_root_parms, line, sizeof(nfs_root_parms)); + } else { + size_t n = strlen(line) + sizeof(NFS_ROOT) - 1; + if (n >= sizeof(nfs_root_parms)) + line[sizeof(nfs_root_parms) - sizeof(NFS_ROOT) - 2] = '\0'; + sprintf(nfs_root_parms, NFS_ROOT, line); + } + + /* + * Extract the IP address of the NFS server containing our + * root file system, if one was specified. + * + * Note: root_nfs_parse_addr() removes the server-ip from + * nfs_root_parms, if it exists. + */ + root_server_addr = root_nfs_parse_addr(nfs_root_parms); + + return 1; +} + +__setup("nfsroot=", nfs_root_setup); + +static int __init root_nfs_copy(char *dest, const char *src, + const size_t destlen) +{ + if (strlcpy(dest, src, destlen) > destlen) + return -1; + return 0; +} + +static int __init root_nfs_cat(char *dest, const char *src, + const size_t destlen) +{ + size_t len = strlen(dest); + + if (len && dest[len - 1] != ',') + if (strlcat(dest, ",", destlen) > destlen) + return -1; + + if (strlcat(dest, src, destlen) > destlen) + return -1; + return 0; +} + +/* + * Parse out root export path and mount options from + * passed-in string @incoming. + * + * Copy the export path into @exppath. + */ +static int __init root_nfs_parse_options(char *incoming, char *exppath, + const size_t exppathlen) +{ + char *p; + + /* + * Set the NFS remote path + */ + p = strsep(&incoming, ","); + if (*p != '\0' && strcmp(p, "default") != 0) + if (root_nfs_copy(exppath, p, exppathlen)) + return -1; + + /* + * @incoming now points to the rest of the string; if it + * contains something, append it to our root options buffer + */ + if (incoming != NULL && *incoming != '\0') + if (root_nfs_cat(nfs_root_options, incoming, + sizeof(nfs_root_options))) + return -1; + return 0; +} + +/* + * Decode the export directory path name and NFS options from + * the kernel command line. This has to be done late in order to + * use a dynamically acquired client IP address for the remote + * root directory path. + * + * Returns zero if successful; otherwise -1 is returned. + */ +static int __init root_nfs_data(char *cmdline) +{ + char mand_options[sizeof("nolock,addr=") + INET_ADDRSTRLEN + 1]; + int len, retval = -1; + char *tmp = NULL; + const size_t tmplen = sizeof(nfs_export_path); + + tmp = kzalloc(tmplen, GFP_KERNEL); + if (tmp == NULL) + goto out_nomem; + strcpy(tmp, NFS_ROOT); + + if (root_server_path[0] != '\0') { + dprintk("Root-NFS: DHCPv4 option 17: %s\n", + root_server_path); + if (root_nfs_parse_options(root_server_path, tmp, tmplen)) + goto out_optionstoolong; + } + + if (cmdline[0] != '\0') { + dprintk("Root-NFS: nfsroot=%s\n", cmdline); + if (root_nfs_parse_options(cmdline, tmp, tmplen)) + goto out_optionstoolong; + } + + /* + * Append mandatory options for nfsroot so they override + * what has come before + */ + snprintf(mand_options, sizeof(mand_options), "nolock,addr=%pI4", + &servaddr); + if (root_nfs_cat(nfs_root_options, mand_options, + sizeof(nfs_root_options))) + goto out_optionstoolong; + + /* + * Set up nfs_root_device. For NFS mounts, this looks like + * + * server:/path + * + * At this point, utsname()->nodename contains our local + * IP address or hostname, set by ipconfig. If "%s" exists + * in tmp, substitute the nodename, then shovel the whole + * mess into nfs_root_device. + */ + len = snprintf(nfs_export_path, sizeof(nfs_export_path), + tmp, utsname()->nodename); + if (len >= (int)sizeof(nfs_export_path)) + goto out_devnametoolong; + len = snprintf(nfs_root_device, sizeof(nfs_root_device), + "%pI4:%s", &servaddr, nfs_export_path); + if (len >= (int)sizeof(nfs_root_device)) + goto out_devnametoolong; + + retval = 0; + +out: + kfree(tmp); + return retval; +out_nomem: + printk(KERN_ERR "Root-NFS: could not allocate memory\n"); + goto out; +out_optionstoolong: + printk(KERN_ERR "Root-NFS: mount options string too long\n"); + goto out; +out_devnametoolong: + printk(KERN_ERR "Root-NFS: root device name too long.\n"); + goto out; +} + +/** + * nfs_root_data - Return prepared 'data' for NFSROOT mount + * @root_device: OUT: address of string containing NFSROOT device + * @root_data: OUT: address of string containing NFSROOT mount options + * + * Returns zero and sets @root_device and @root_data if successful, + * otherwise -1 is returned. + */ +int __init nfs_root_data(char **root_device, char **root_data) +{ + servaddr = root_server_addr; + if (servaddr == htonl(INADDR_NONE)) { + printk(KERN_ERR "Root-NFS: no NFS server address\n"); + return -1; + } + + if (root_nfs_data(nfs_root_parms) < 0) + return -1; + + *root_device = nfs_root_device; + *root_data = nfs_root_options; + return 0; +} |