blob: d3d8799e2187233e23e1614990443203d4fff1ad [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * JFFS2 -- Journalling Flash File System, Version 2.
3 *
David Woodhousec00c3102007-04-25 14:16:47 +01004 * Copyright © 2001-2007 Red Hat, Inc.
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 *
6 * Created by David Woodhouse <dwmw2@infradead.org>
7 *
8 * For licensing information, see the file 'LICENCE' in this directory.
9 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 */
11
Joe Perches5a528952012-02-15 15:56:45 -080012#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/slab.h>
17#include <linux/init.h>
18#include <linux/list.h>
19#include <linux/fs.h>
Artem Bityutskiy9c740342006-10-11 14:52:47 +030020#include <linux/err.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/mount.h>
Andres Salomon92abc472011-10-16 18:15:16 -070022#include <linux/parser.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <linux/jffs2.h>
24#include <linux/pagemap.h>
David Howellsacaebfd2007-05-10 22:51:50 -070025#include <linux/mtd/super.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/ctype.h>
27#include <linux/namei.h>
Andres Salomon92abc472011-10-16 18:15:16 -070028#include <linux/seq_file.h>
David Woodhouse5f556aa2008-07-31 20:39:25 +010029#include <linux/exportfs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070030#include "compr.h"
31#include "nodelist.h"
32
33static void jffs2_put_super(struct super_block *);
34
Christoph Lametere18b8902006-12-06 20:33:20 -080035static struct kmem_cache *jffs2_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37static struct inode *jffs2_alloc_inode(struct super_block *sb)
38{
David Woodhouse4e571ab2008-05-01 12:28:04 +010039 struct jffs2_inode_info *f;
40
41 f = kmem_cache_alloc(jffs2_inode_cachep, GFP_KERNEL);
42 if (!f)
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 return NULL;
David Woodhouse4e571ab2008-05-01 12:28:04 +010044 return &f->vfs_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -070045}
46
Nick Pigginfa0d7e3d2011-01-07 17:49:49 +110047static void jffs2_i_callback(struct rcu_head *head)
48{
49 struct inode *inode = container_of(head, struct inode, i_rcu);
Nick Pigginfa0d7e3d2011-01-07 17:49:49 +110050 kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode));
51}
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053static void jffs2_destroy_inode(struct inode *inode)
54{
Nick Pigginfa0d7e3d2011-01-07 17:49:49 +110055 call_rcu(&inode->i_rcu, jffs2_i_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -070056}
57
Alexey Dobriyan51cc5062008-07-25 19:45:34 -070058static void jffs2_i_init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -070059{
David Woodhouse4e571ab2008-05-01 12:28:04 +010060 struct jffs2_inode_info *f = foo;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
David Woodhouse4e571ab2008-05-01 12:28:04 +010062 mutex_init(&f->sem);
63 inode_init_once(&f->vfs_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -070064}
65
Andres Salomon92abc472011-10-16 18:15:16 -070066static const char *jffs2_compr_name(unsigned int compr)
67{
68 switch (compr) {
69 case JFFS2_COMPR_MODE_NONE:
70 return "none";
Andres Salomon123005f2011-10-16 18:15:23 -070071#ifdef CONFIG_JFFS2_LZO
72 case JFFS2_COMPR_MODE_FORCELZO:
73 return "lzo";
74#endif
75#ifdef CONFIG_JFFS2_ZLIB
76 case JFFS2_COMPR_MODE_FORCEZLIB:
77 return "zlib";
78#endif
Andres Salomon92abc472011-10-16 18:15:16 -070079 default:
80 /* should never happen; programmer error */
81 WARN_ON(1);
82 return "";
83 }
84}
85
Al Viro34c80b12011-12-08 21:32:45 -050086static int jffs2_show_options(struct seq_file *s, struct dentry *root)
Andres Salomon92abc472011-10-16 18:15:16 -070087{
Al Viro34c80b12011-12-08 21:32:45 -050088 struct jffs2_sb_info *c = JFFS2_SB_INFO(root->d_sb);
Andres Salomon92abc472011-10-16 18:15:16 -070089 struct jffs2_mount_opts *opts = &c->mount_opts;
90
91 if (opts->override_compr)
92 seq_printf(s, ",compr=%s", jffs2_compr_name(opts->compr));
Daniel Drake8da8ba22012-04-10 22:22:35 +010093 if (opts->rp_size)
94 seq_printf(s, ",rp_size=%u", opts->rp_size / 1024);
Andres Salomon92abc472011-10-16 18:15:16 -070095
96 return 0;
97}
98
Linus Torvalds1da177e2005-04-16 15:20:36 -070099static int jffs2_sync_fs(struct super_block *sb, int wait)
100{
101 struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
102
Artem Bityutskiya445f782012-08-23 10:10:07 +0300103#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
104 cancel_delayed_work_sync(&c->wbuf_dwork);
105#endif
106
David Woodhouseced22072008-04-22 15:13:40 +0100107 mutex_lock(&c->alloc_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 jffs2_flush_wbuf_pad(c);
David Woodhouseced22072008-04-22 15:13:40 +0100109 mutex_unlock(&c->alloc_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110 return 0;
111}
112
David Woodhouse5f556aa2008-07-31 20:39:25 +0100113static struct inode *jffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
114 uint32_t generation)
115{
116 /* We don't care about i_generation. We'll destroy the flash
117 before we start re-using inode numbers anyway. And even
118 if that wasn't true, we'd have other problems...*/
119 return jffs2_iget(sb, ino);
120}
121
122static struct dentry *jffs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
123 int fh_len, int fh_type)
124{
125 return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
126 jffs2_nfs_get_inode);
127}
128
129static struct dentry *jffs2_fh_to_parent(struct super_block *sb, struct fid *fid,
130 int fh_len, int fh_type)
131{
132 return generic_fh_to_parent(sb, fid, fh_len, fh_type,
133 jffs2_nfs_get_inode);
134}
135
136static struct dentry *jffs2_get_parent(struct dentry *child)
137{
138 struct jffs2_inode_info *f;
139 uint32_t pino;
140
141 BUG_ON(!S_ISDIR(child->d_inode->i_mode));
142
143 f = JFFS2_INODE_INFO(child->d_inode);
144
145 pino = f->inocache->pino_nlink;
146
147 JFFS2_DEBUG("Parent of directory ino #%u is #%u\n",
148 f->inocache->ino, pino);
149
150 return d_obtain_alias(jffs2_iget(child->d_inode->i_sb, pino));
151}
152
Alexey Dobriyanac4cfdd2009-09-21 17:01:10 -0700153static const struct export_operations jffs2_export_ops = {
David Woodhouse5f556aa2008-07-31 20:39:25 +0100154 .get_parent = jffs2_get_parent,
155 .fh_to_dentry = jffs2_fh_to_dentry,
156 .fh_to_parent = jffs2_fh_to_parent,
157};
158
Andres Salomon92abc472011-10-16 18:15:16 -0700159/*
160 * JFFS2 mount options.
161 *
162 * Opt_override_compr: override default compressor
Daniel Drake8da8ba22012-04-10 22:22:35 +0100163 * Opt_rp_size: size of reserved pool in KiB
Andres Salomon92abc472011-10-16 18:15:16 -0700164 * Opt_err: just end of array marker
165 */
166enum {
167 Opt_override_compr,
Daniel Drake8da8ba22012-04-10 22:22:35 +0100168 Opt_rp_size,
Andres Salomon92abc472011-10-16 18:15:16 -0700169 Opt_err,
170};
171
172static const match_table_t tokens = {
173 {Opt_override_compr, "compr=%s"},
Daniel Drake8da8ba22012-04-10 22:22:35 +0100174 {Opt_rp_size, "rp_size=%u"},
Andres Salomon92abc472011-10-16 18:15:16 -0700175 {Opt_err, NULL},
176};
177
178static int jffs2_parse_options(struct jffs2_sb_info *c, char *data)
179{
180 substring_t args[MAX_OPT_ARGS];
181 char *p, *name;
Daniel Drake8da8ba22012-04-10 22:22:35 +0100182 unsigned int opt;
Andres Salomon92abc472011-10-16 18:15:16 -0700183
184 if (!data)
185 return 0;
186
187 while ((p = strsep(&data, ","))) {
188 int token;
189
190 if (!*p)
191 continue;
192
193 token = match_token(p, tokens, args);
194 switch (token) {
195 case Opt_override_compr:
196 name = match_strdup(&args[0]);
197
198 if (!name)
199 return -ENOMEM;
Andres Salomon123005f2011-10-16 18:15:23 -0700200 if (!strcmp(name, "none"))
Andres Salomon92abc472011-10-16 18:15:16 -0700201 c->mount_opts.compr = JFFS2_COMPR_MODE_NONE;
Andres Salomon123005f2011-10-16 18:15:23 -0700202#ifdef CONFIG_JFFS2_LZO
203 else if (!strcmp(name, "lzo"))
204 c->mount_opts.compr = JFFS2_COMPR_MODE_FORCELZO;
205#endif
206#ifdef CONFIG_JFFS2_ZLIB
207 else if (!strcmp(name, "zlib"))
208 c->mount_opts.compr =
209 JFFS2_COMPR_MODE_FORCEZLIB;
210#endif
211 else {
Joe Perches5a528952012-02-15 15:56:45 -0800212 pr_err("Error: unknown compressor \"%s\"\n",
Joe Perchesda320f02012-02-15 15:56:44 -0800213 name);
Andres Salomon123005f2011-10-16 18:15:23 -0700214 kfree(name);
215 return -EINVAL;
Andres Salomon92abc472011-10-16 18:15:16 -0700216 }
217 kfree(name);
Andres Salomon123005f2011-10-16 18:15:23 -0700218 c->mount_opts.override_compr = true;
Andres Salomon92abc472011-10-16 18:15:16 -0700219 break;
Daniel Drake8da8ba22012-04-10 22:22:35 +0100220 case Opt_rp_size:
221 if (match_int(&args[0], &opt))
222 return -EINVAL;
223 opt *= 1024;
224 if (opt > c->mtd->size) {
225 pr_warn("Too large reserve pool specified, max "
226 "is %llu KB\n", c->mtd->size / 1024);
227 return -EINVAL;
228 }
229 c->mount_opts.rp_size = opt;
230 break;
Andres Salomon92abc472011-10-16 18:15:16 -0700231 default:
Joe Perches5a528952012-02-15 15:56:45 -0800232 pr_err("Error: unrecognized mount option '%s' or missing value\n",
Joe Perchesda320f02012-02-15 15:56:44 -0800233 p);
Andres Salomon92abc472011-10-16 18:15:16 -0700234 return -EINVAL;
235 }
236 }
237
238 return 0;
239}
240
241static int jffs2_remount_fs(struct super_block *sb, int *flags, char *data)
242{
243 struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
244 int err;
245
246 err = jffs2_parse_options(c, data);
247 if (err)
248 return -EINVAL;
249
250 return jffs2_do_remount_fs(sb, flags, data);
251}
252
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800253static const struct super_operations jffs2_super_operations =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254{
255 .alloc_inode = jffs2_alloc_inode,
256 .destroy_inode =jffs2_destroy_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 .put_super = jffs2_put_super,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 .statfs = jffs2_statfs,
259 .remount_fs = jffs2_remount_fs,
Al Virob57922d2010-06-07 14:34:48 -0400260 .evict_inode = jffs2_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261 .dirty_inode = jffs2_dirty_inode,
Andres Salomon92abc472011-10-16 18:15:16 -0700262 .show_options = jffs2_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 .sync_fs = jffs2_sync_fs,
264};
265
David Howellsacaebfd2007-05-10 22:51:50 -0700266/*
267 * fill in the superblock
268 */
269static int jffs2_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 struct jffs2_sb_info *c;
Jan Blunckdb719222010-08-15 22:51:10 +0200272 int ret;
273
Joe Perches9c261b32012-02-15 15:56:43 -0800274 jffs2_dbg(1, "jffs2_get_sb_mtd():"
David Howellsacaebfd2007-05-10 22:51:50 -0700275 " New superblock for device %d (\"%s\")\n",
Joe Perches9c261b32012-02-15 15:56:43 -0800276 sb->s_mtd->index, sb->s_mtd->name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277
Panagiotis Issarisf8314dc2006-09-27 01:49:37 -0700278 c = kzalloc(sizeof(*c), GFP_KERNEL);
Arnd Bergmann1a028dd2010-09-16 16:11:09 +0200279 if (!c)
David Howells454e2392006-06-23 02:02:57 -0700280 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281
David Howellsacaebfd2007-05-10 22:51:50 -0700282 c->mtd = sb->s_mtd;
283 c->os_priv = sb;
284 sb->s_fs_info = c;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Andres Salomon92abc472011-10-16 18:15:16 -0700286 ret = jffs2_parse_options(c, data);
287 if (ret) {
288 kfree(c);
289 return -EINVAL;
290 }
291
David Howellsacaebfd2007-05-10 22:51:50 -0700292 /* Initialize JFFS2 superblock locks, the further initialization will
293 * be done later */
David Woodhouseced22072008-04-22 15:13:40 +0100294 mutex_init(&c->alloc_sem);
295 mutex_init(&c->erase_free_sem);
Artem B. Bityuckiyb6220592005-07-12 17:37:12 +0100296 init_waitqueue_head(&c->erase_wait);
297 init_waitqueue_head(&c->inocache_wq);
298 spin_lock_init(&c->erase_completion_lock);
299 spin_lock_init(&c->inocache_lock);
300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 sb->s_op = &jffs2_super_operations;
David Woodhouse5f556aa2008-07-31 20:39:25 +0100302 sb->s_export_op = &jffs2_export_ops;
David Howellsacaebfd2007-05-10 22:51:50 -0700303 sb->s_flags = sb->s_flags | MS_NOATIME;
KaiGai Koheiaa98d7c2006-05-13 15:09:47 +0900304 sb->s_xattr = jffs2_xattr_handlers;
305#ifdef CONFIG_JFFS2_FS_POSIX_ACL
306 sb->s_flags |= MS_POSIXACL;
307#endif
Jan Blunckdb719222010-08-15 22:51:10 +0200308 ret = jffs2_do_fill_super(sb, data, silent);
Jan Blunckdb719222010-08-15 22:51:10 +0200309 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310}
311
Al Viro848b83a2010-07-25 00:56:46 +0400312static struct dentry *jffs2_mount(struct file_system_type *fs_type,
David Howells454e2392006-06-23 02:02:57 -0700313 int flags, const char *dev_name,
Al Viro848b83a2010-07-25 00:56:46 +0400314 void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315{
Al Viro848b83a2010-07-25 00:56:46 +0400316 return mount_mtd(fs_type, flags, dev_name, data, jffs2_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317}
318
319static void jffs2_put_super (struct super_block *sb)
320{
321 struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
322
Joe Perches9c261b32012-02-15 15:56:43 -0800323 jffs2_dbg(2, "%s()\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
David Woodhouseced22072008-04-22 15:13:40 +0100325 mutex_lock(&c->alloc_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 jffs2_flush_wbuf_pad(c);
David Woodhouseced22072008-04-22 15:13:40 +0100327 mutex_unlock(&c->alloc_sem);
Ferenc Havasie631ddb2005-09-07 09:35:26 +0100328
329 jffs2_sum_exit(c);
330
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 jffs2_free_ino_caches(c);
332 jffs2_free_raw_node_refs(c);
Ferenc Havasi4ce1f562005-08-31 14:51:04 +0100333 if (jffs2_blocks_use_vmalloc(c))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 vfree(c->blocks);
335 else
336 kfree(c->blocks);
337 jffs2_flash_cleanup(c);
338 kfree(c->inocache_list);
KaiGai Koheiaa98d7c2006-05-13 15:09:47 +0900339 jffs2_clear_xattr_subsystem(c);
Artem Bityutskiy327cf292011-12-30 16:35:35 +0200340 mtd_sync(c->mtd);
Joe Perches9c261b32012-02-15 15:56:43 -0800341 jffs2_dbg(1, "%s(): returning\n", __func__);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342}
343
344static void jffs2_kill_sb(struct super_block *sb)
345{
346 struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
Artem B. Bityuckiya69dde92005-05-18 12:37:28 +0100347 if (!(sb->s_flags & MS_RDONLY))
348 jffs2_stop_garbage_collect_thread(c);
David Howellsacaebfd2007-05-10 22:51:50 -0700349 kill_mtd_super(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 kfree(c);
351}
352
353static struct file_system_type jffs2_fs_type = {
354 .owner = THIS_MODULE,
355 .name = "jffs2",
Al Viro848b83a2010-07-25 00:56:46 +0400356 .mount = jffs2_mount,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700357 .kill_sb = jffs2_kill_sb,
358};
359
360static int __init init_jffs2_fs(void)
361{
362 int ret;
363
David Woodhouse3e68fbb2006-05-15 00:49:43 +0100364 /* Paranoia checks for on-medium structures. If we ask GCC
365 to pack them with __attribute__((packed)) then it _also_
366 assumes that they're not aligned -- so it emits crappy
367 code on some architectures. Ideally we want an attribute
368 which means just 'no padding', without the alignment
369 thing. But GCC doesn't have that -- we have to just
370 hope the structs are the right sizes, instead. */
Alexey Dobriyan2ecd05a2006-10-11 01:22:05 -0700371 BUILD_BUG_ON(sizeof(struct jffs2_unknown_node) != 12);
372 BUILD_BUG_ON(sizeof(struct jffs2_raw_dirent) != 40);
373 BUILD_BUG_ON(sizeof(struct jffs2_raw_inode) != 68);
374 BUILD_BUG_ON(sizeof(struct jffs2_raw_summary) != 32);
David Woodhouse3e68fbb2006-05-15 00:49:43 +0100375
Joe Perches5a528952012-02-15 15:56:45 -0800376 pr_info("version 2.2."
Andrew Victor2f82ce12005-02-09 09:24:26 +0000377#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378 " (NAND)"
379#endif
Ferenc Havasie631ddb2005-09-07 09:35:26 +0100380#ifdef CONFIG_JFFS2_SUMMARY
381 " (SUMMARY) "
382#endif
David Woodhousec00c3102007-04-25 14:16:47 +0100383 " © 2001-2006 Red Hat, Inc.\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384
385 jffs2_inode_cachep = kmem_cache_create("jffs2_i",
386 sizeof(struct jffs2_inode_info),
Paul Jacksonfffb60f2006-03-24 03:16:06 -0800387 0, (SLAB_RECLAIM_ACCOUNT|
388 SLAB_MEM_SPREAD),
Paul Mundt20c2df82007-07-20 10:11:58 +0900389 jffs2_i_init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700390 if (!jffs2_inode_cachep) {
Joe Perches5a528952012-02-15 15:56:45 -0800391 pr_err("error: Failed to initialise inode cache\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 return -ENOMEM;
393 }
394 ret = jffs2_compressors_init();
395 if (ret) {
Joe Perches5a528952012-02-15 15:56:45 -0800396 pr_err("error: Failed to initialise compressors\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 goto out;
398 }
399 ret = jffs2_create_slab_caches();
400 if (ret) {
Joe Perches5a528952012-02-15 15:56:45 -0800401 pr_err("error: Failed to initialise slab caches\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 goto out_compressors;
403 }
404 ret = register_filesystem(&jffs2_fs_type);
405 if (ret) {
Joe Perches5a528952012-02-15 15:56:45 -0800406 pr_err("error: Failed to register filesystem\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 goto out_slab;
408 }
409 return 0;
410
411 out_slab:
412 jffs2_destroy_slab_caches();
413 out_compressors:
414 jffs2_compressors_exit();
415 out:
416 kmem_cache_destroy(jffs2_inode_cachep);
417 return ret;
418}
419
420static void __exit exit_jffs2_fs(void)
421{
422 unregister_filesystem(&jffs2_fs_type);
423 jffs2_destroy_slab_caches();
424 jffs2_compressors_exit();
Kirill A. Shutemov8c0a8532012-09-26 11:33:07 +1000425
426 /*
427 * Make sure all delayed rcu free inodes are flushed before we
428 * destroy cache.
429 */
430 rcu_barrier();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 kmem_cache_destroy(jffs2_inode_cachep);
432}
433
434module_init(init_jffs2_fs);
435module_exit(exit_jffs2_fs);
436
437MODULE_DESCRIPTION("The Journalling Flash File System, v2");
438MODULE_AUTHOR("Red Hat, Inc.");
Thomas Gleixner182ec4e2005-11-07 11:16:07 +0000439MODULE_LICENSE("GPL"); // Actually dual-licensed, but it doesn't matter for
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440 // the sake of this tag. It's Free Software.