/home/lenb/src/to-linus branch 'acpi-2.6.12'
[linux-2.6] / fs / hugetlbfs / inode.c
1 /*
2  * hugetlbpage-backed filesystem.  Based on ramfs.
3  *
4  * William Irwin, 2002
5  *
6  * Copyright (C) 2002 Linus Torvalds.
7  */
8
9 #include <linux/module.h>
10 #include <linux/thread_info.h>
11 #include <asm/current.h>
12 #include <linux/sched.h>                /* remove ASAP */
13 #include <linux/fs.h>
14 #include <linux/mount.h>
15 #include <linux/file.h>
16 #include <linux/writeback.h>
17 #include <linux/pagemap.h>
18 #include <linux/highmem.h>
19 #include <linux/init.h>
20 #include <linux/string.h>
21 #include <linux/backing-dev.h>
22 #include <linux/hugetlb.h>
23 #include <linux/pagevec.h>
24 #include <linux/quotaops.h>
25 #include <linux/slab.h>
26 #include <linux/dnotify.h>
27 #include <linux/statfs.h>
28 #include <linux/security.h>
29
30 #include <asm/uaccess.h>
31
32 /* some random number */
33 #define HUGETLBFS_MAGIC 0x958458f6
34
35 static struct super_operations hugetlbfs_ops;
36 static struct address_space_operations hugetlbfs_aops;
37 struct file_operations hugetlbfs_file_operations;
38 static struct inode_operations hugetlbfs_dir_inode_operations;
39 static struct inode_operations hugetlbfs_inode_operations;
40
41 static struct backing_dev_info hugetlbfs_backing_dev_info = {
42         .ra_pages       = 0,    /* No readahead */
43         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
44 };
45
46 int sysctl_hugetlb_shm_group;
47
48 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
49 {
50         struct inode *inode = file->f_dentry->d_inode;
51         struct address_space *mapping = inode->i_mapping;
52         loff_t len, vma_len;
53         int ret;
54
55         if ((vma->vm_flags & (VM_MAYSHARE | VM_WRITE)) == VM_WRITE)
56                 return -EINVAL;
57
58         if (vma->vm_pgoff & (HPAGE_SIZE / PAGE_SIZE - 1))
59                 return -EINVAL;
60
61         if (vma->vm_start & ~HPAGE_MASK)
62                 return -EINVAL;
63
64         if (vma->vm_end & ~HPAGE_MASK)
65                 return -EINVAL;
66
67         if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
68                 return -EINVAL;
69
70         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
71
72         down(&inode->i_sem);
73         file_accessed(file);
74         vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
75         vma->vm_ops = &hugetlb_vm_ops;
76
77         ret = -ENOMEM;
78         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
79         if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
80                 goto out;
81
82         ret = hugetlb_prefault(mapping, vma);
83         if (ret)
84                 goto out;
85
86         if (inode->i_size < len)
87                 inode->i_size = len;
88 out:
89         up(&inode->i_sem);
90
91         return ret;
92 }
93
94 /*
95  * Called under down_write(mmap_sem), page_table_lock is not held
96  */
97
98 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
99 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
100                 unsigned long len, unsigned long pgoff, unsigned long flags);
101 #else
102 static unsigned long
103 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
104                 unsigned long len, unsigned long pgoff, unsigned long flags)
105 {
106         struct mm_struct *mm = current->mm;
107         struct vm_area_struct *vma;
108         unsigned long start_addr;
109
110         if (len & ~HPAGE_MASK)
111                 return -EINVAL;
112         if (len > TASK_SIZE)
113                 return -ENOMEM;
114
115         if (addr) {
116                 addr = ALIGN(addr, HPAGE_SIZE);
117                 vma = find_vma(mm, addr);
118                 if (TASK_SIZE - len >= addr &&
119                     (!vma || addr + len <= vma->vm_start))
120                         return addr;
121         }
122
123         start_addr = mm->free_area_cache;
124
125         if (len <= mm->cached_hole_size)
126                 start_addr = TASK_UNMAPPED_BASE;
127
128 full_search:
129         addr = ALIGN(start_addr, HPAGE_SIZE);
130
131         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
132                 /* At this point:  (!vma || addr < vma->vm_end). */
133                 if (TASK_SIZE - len < addr) {
134                         /*
135                          * Start a new search - just in case we missed
136                          * some holes.
137                          */
138                         if (start_addr != TASK_UNMAPPED_BASE) {
139                                 start_addr = TASK_UNMAPPED_BASE;
140                                 goto full_search;
141                         }
142                         return -ENOMEM;
143                 }
144
145                 if (!vma || addr + len <= vma->vm_start)
146                         return addr;
147                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
148         }
149 }
150 #endif
151
152 /*
153  * Read a page. Again trivial. If it didn't already exist
154  * in the page cache, it is zero-filled.
155  */
156 static int hugetlbfs_readpage(struct file *file, struct page * page)
157 {
158         unlock_page(page);
159         return -EINVAL;
160 }
161
162 static int hugetlbfs_prepare_write(struct file *file,
163                         struct page *page, unsigned offset, unsigned to)
164 {
165         return -EINVAL;
166 }
167
168 static int hugetlbfs_commit_write(struct file *file,
169                         struct page *page, unsigned offset, unsigned to)
170 {
171         return -EINVAL;
172 }
173
174 static void huge_pagevec_release(struct pagevec *pvec)
175 {
176         int i;
177
178         for (i = 0; i < pagevec_count(pvec); ++i)
179                 put_page(pvec->pages[i]);
180
181         pagevec_reinit(pvec);
182 }
183
184 static void truncate_huge_page(struct page *page)
185 {
186         clear_page_dirty(page);
187         ClearPageUptodate(page);
188         remove_from_page_cache(page);
189         put_page(page);
190 }
191
192 static void truncate_hugepages(struct address_space *mapping, loff_t lstart)
193 {
194         const pgoff_t start = lstart >> HPAGE_SHIFT;
195         struct pagevec pvec;
196         pgoff_t next;
197         int i;
198
199         pagevec_init(&pvec, 0);
200         next = start;
201         while (1) {
202                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
203                         if (next == start)
204                                 break;
205                         next = start;
206                         continue;
207                 }
208
209                 for (i = 0; i < pagevec_count(&pvec); ++i) {
210                         struct page *page = pvec.pages[i];
211
212                         lock_page(page);
213                         if (page->index > next)
214                                 next = page->index;
215                         ++next;
216                         truncate_huge_page(page);
217                         unlock_page(page);
218                         hugetlb_put_quota(mapping);
219                 }
220                 huge_pagevec_release(&pvec);
221         }
222         BUG_ON(!lstart && mapping->nrpages);
223 }
224
225 static void hugetlbfs_delete_inode(struct inode *inode)
226 {
227         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(inode->i_sb);
228
229         hlist_del_init(&inode->i_hash);
230         list_del_init(&inode->i_list);
231         list_del_init(&inode->i_sb_list);
232         inode->i_state |= I_FREEING;
233         inodes_stat.nr_inodes--;
234         spin_unlock(&inode_lock);
235
236         if (inode->i_data.nrpages)
237                 truncate_hugepages(&inode->i_data, 0);
238
239         security_inode_delete(inode);
240
241         if (sbinfo->free_inodes >= 0) {
242                 spin_lock(&sbinfo->stat_lock);
243                 sbinfo->free_inodes++;
244                 spin_unlock(&sbinfo->stat_lock);
245         }
246
247         clear_inode(inode);
248         destroy_inode(inode);
249 }
250
251 static void hugetlbfs_forget_inode(struct inode *inode)
252 {
253         struct super_block *super_block = inode->i_sb;
254         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(super_block);
255
256         if (hlist_unhashed(&inode->i_hash))
257                 goto out_truncate;
258
259         if (!(inode->i_state & (I_DIRTY|I_LOCK))) {
260                 list_del(&inode->i_list);
261                 list_add(&inode->i_list, &inode_unused);
262         }
263         inodes_stat.nr_unused++;
264         if (!super_block || (super_block->s_flags & MS_ACTIVE)) {
265                 spin_unlock(&inode_lock);
266                 return;
267         }
268
269         /* write_inode_now() ? */
270         inodes_stat.nr_unused--;
271         hlist_del_init(&inode->i_hash);
272 out_truncate:
273         list_del_init(&inode->i_list);
274         list_del_init(&inode->i_sb_list);
275         inode->i_state |= I_FREEING;
276         inodes_stat.nr_inodes--;
277         spin_unlock(&inode_lock);
278         if (inode->i_data.nrpages)
279                 truncate_hugepages(&inode->i_data, 0);
280
281         if (sbinfo->free_inodes >= 0) {
282                 spin_lock(&sbinfo->stat_lock);
283                 sbinfo->free_inodes++;
284                 spin_unlock(&sbinfo->stat_lock);
285         }
286
287         clear_inode(inode);
288         destroy_inode(inode);
289 }
290
291 static void hugetlbfs_drop_inode(struct inode *inode)
292 {
293         if (!inode->i_nlink)
294                 hugetlbfs_delete_inode(inode);
295         else
296                 hugetlbfs_forget_inode(inode);
297 }
298
299 /*
300  * h_pgoff is in HPAGE_SIZE units.
301  * vma->vm_pgoff is in PAGE_SIZE units.
302  */
303 static inline void
304 hugetlb_vmtruncate_list(struct prio_tree_root *root, unsigned long h_pgoff)
305 {
306         struct vm_area_struct *vma;
307         struct prio_tree_iter iter;
308
309         vma_prio_tree_foreach(vma, &iter, root, h_pgoff, ULONG_MAX) {
310                 unsigned long h_vm_pgoff;
311                 unsigned long v_length;
312                 unsigned long v_offset;
313
314                 h_vm_pgoff = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
315                 v_offset = (h_pgoff - h_vm_pgoff) << HPAGE_SHIFT;
316                 /*
317                  * Is this VMA fully outside the truncation point?
318                  */
319                 if (h_vm_pgoff >= h_pgoff)
320                         v_offset = 0;
321
322                 v_length = vma->vm_end - vma->vm_start;
323
324                 zap_hugepage_range(vma,
325                                 vma->vm_start + v_offset,
326                                 v_length - v_offset);
327         }
328 }
329
330 /*
331  * Expanding truncates are not allowed.
332  */
333 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
334 {
335         unsigned long pgoff;
336         struct address_space *mapping = inode->i_mapping;
337
338         if (offset > inode->i_size)
339                 return -EINVAL;
340
341         BUG_ON(offset & ~HPAGE_MASK);
342         pgoff = offset >> HPAGE_SHIFT;
343
344         inode->i_size = offset;
345         spin_lock(&mapping->i_mmap_lock);
346         if (!prio_tree_empty(&mapping->i_mmap))
347                 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
348         spin_unlock(&mapping->i_mmap_lock);
349         truncate_hugepages(mapping, offset);
350         return 0;
351 }
352
353 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
354 {
355         struct inode *inode = dentry->d_inode;
356         int error;
357         unsigned int ia_valid = attr->ia_valid;
358
359         BUG_ON(!inode);
360
361         error = inode_change_ok(inode, attr);
362         if (error)
363                 goto out;
364
365         if (ia_valid & ATTR_SIZE) {
366                 error = -EINVAL;
367                 if (!(attr->ia_size & ~HPAGE_MASK))
368                         error = hugetlb_vmtruncate(inode, attr->ia_size);
369                 if (error)
370                         goto out;
371                 attr->ia_valid &= ~ATTR_SIZE;
372         }
373         error = inode_setattr(inode, attr);
374 out:
375         return error;
376 }
377
378 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid, 
379                                         gid_t gid, int mode, dev_t dev)
380 {
381         struct inode *inode;
382         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
383
384         if (sbinfo->free_inodes >= 0) {
385                 spin_lock(&sbinfo->stat_lock);
386                 if (!sbinfo->free_inodes) {
387                         spin_unlock(&sbinfo->stat_lock);
388                         return NULL;
389                 }
390                 sbinfo->free_inodes--;
391                 spin_unlock(&sbinfo->stat_lock);
392         }
393
394         inode = new_inode(sb);
395         if (inode) {
396                 struct hugetlbfs_inode_info *info;
397                 inode->i_mode = mode;
398                 inode->i_uid = uid;
399                 inode->i_gid = gid;
400                 inode->i_blksize = HPAGE_SIZE;
401                 inode->i_blocks = 0;
402                 inode->i_mapping->a_ops = &hugetlbfs_aops;
403                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
404                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
405                 info = HUGETLBFS_I(inode);
406                 mpol_shared_policy_init(&info->policy);
407                 switch (mode & S_IFMT) {
408                 default:
409                         init_special_inode(inode, mode, dev);
410                         break;
411                 case S_IFREG:
412                         inode->i_op = &hugetlbfs_inode_operations;
413                         inode->i_fop = &hugetlbfs_file_operations;
414                         break;
415                 case S_IFDIR:
416                         inode->i_op = &hugetlbfs_dir_inode_operations;
417                         inode->i_fop = &simple_dir_operations;
418
419                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
420                         inode->i_nlink++;
421                         break;
422                 case S_IFLNK:
423                         inode->i_op = &page_symlink_inode_operations;
424                         break;
425                 }
426         }
427         return inode;
428 }
429
430 /*
431  * File creation. Allocate an inode, and we're done..
432  */
433 static int hugetlbfs_mknod(struct inode *dir,
434                         struct dentry *dentry, int mode, dev_t dev)
435 {
436         struct inode *inode;
437         int error = -ENOSPC;
438         gid_t gid;
439
440         if (dir->i_mode & S_ISGID) {
441                 gid = dir->i_gid;
442                 if (S_ISDIR(mode))
443                         mode |= S_ISGID;
444         } else {
445                 gid = current->fsgid;
446         }
447         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
448         if (inode) {
449                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
450                 d_instantiate(dentry, inode);
451                 dget(dentry);   /* Extra count - pin the dentry in core */
452                 error = 0;
453         }
454         return error;
455 }
456
457 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
458 {
459         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
460         if (!retval)
461                 dir->i_nlink++;
462         return retval;
463 }
464
465 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
466 {
467         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
468 }
469
470 static int hugetlbfs_symlink(struct inode *dir,
471                         struct dentry *dentry, const char *symname)
472 {
473         struct inode *inode;
474         int error = -ENOSPC;
475         gid_t gid;
476
477         if (dir->i_mode & S_ISGID)
478                 gid = dir->i_gid;
479         else
480                 gid = current->fsgid;
481
482         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
483                                         gid, S_IFLNK|S_IRWXUGO, 0);
484         if (inode) {
485                 int l = strlen(symname)+1;
486                 error = page_symlink(inode, symname, l);
487                 if (!error) {
488                         d_instantiate(dentry, inode);
489                         dget(dentry);
490                 } else
491                         iput(inode);
492         }
493         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
494
495         return error;
496 }
497
498 /*
499  * For direct-IO reads into hugetlb pages
500  */
501 static int hugetlbfs_set_page_dirty(struct page *page)
502 {
503         return 0;
504 }
505
506 static int hugetlbfs_statfs(struct super_block *sb, struct kstatfs *buf)
507 {
508         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
509
510         buf->f_type = HUGETLBFS_MAGIC;
511         buf->f_bsize = HPAGE_SIZE;
512         if (sbinfo) {
513                 spin_lock(&sbinfo->stat_lock);
514                 buf->f_blocks = sbinfo->max_blocks;
515                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
516                 buf->f_files = sbinfo->max_inodes;
517                 buf->f_ffree = sbinfo->free_inodes;
518                 spin_unlock(&sbinfo->stat_lock);
519         }
520         buf->f_namelen = NAME_MAX;
521         return 0;
522 }
523
524 static void hugetlbfs_put_super(struct super_block *sb)
525 {
526         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
527
528         if (sbi) {
529                 sb->s_fs_info = NULL;
530                 kfree(sbi);
531         }
532 }
533
534 static kmem_cache_t *hugetlbfs_inode_cachep;
535
536 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
537 {
538         struct hugetlbfs_inode_info *p;
539
540         p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
541         if (!p)
542                 return NULL;
543         return &p->vfs_inode;
544 }
545
546 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
547 {
548         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
549
550         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
551             SLAB_CTOR_CONSTRUCTOR)
552                 inode_init_once(&ei->vfs_inode);
553 }
554
555 static void hugetlbfs_destroy_inode(struct inode *inode)
556 {
557         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
558         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
559 }
560
561 static struct address_space_operations hugetlbfs_aops = {
562         .readpage       = hugetlbfs_readpage,
563         .prepare_write  = hugetlbfs_prepare_write,
564         .commit_write   = hugetlbfs_commit_write,
565         .set_page_dirty = hugetlbfs_set_page_dirty,
566 };
567
568 struct file_operations hugetlbfs_file_operations = {
569         .mmap                   = hugetlbfs_file_mmap,
570         .fsync                  = simple_sync_file,
571         .get_unmapped_area      = hugetlb_get_unmapped_area,
572 };
573
574 static struct inode_operations hugetlbfs_dir_inode_operations = {
575         .create         = hugetlbfs_create,
576         .lookup         = simple_lookup,
577         .link           = simple_link,
578         .unlink         = simple_unlink,
579         .symlink        = hugetlbfs_symlink,
580         .mkdir          = hugetlbfs_mkdir,
581         .rmdir          = simple_rmdir,
582         .mknod          = hugetlbfs_mknod,
583         .rename         = simple_rename,
584         .setattr        = hugetlbfs_setattr,
585 };
586
587 static struct inode_operations hugetlbfs_inode_operations = {
588         .setattr        = hugetlbfs_setattr,
589 };
590
591 static struct super_operations hugetlbfs_ops = {
592         .alloc_inode    = hugetlbfs_alloc_inode,
593         .destroy_inode  = hugetlbfs_destroy_inode,
594         .statfs         = hugetlbfs_statfs,
595         .drop_inode     = hugetlbfs_drop_inode,
596         .put_super      = hugetlbfs_put_super,
597 };
598
599 static int
600 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
601 {
602         char *opt, *value, *rest;
603
604         if (!options)
605                 return 0;
606         while ((opt = strsep(&options, ",")) != NULL) {
607                 if (!*opt)
608                         continue;
609
610                 value = strchr(opt, '=');
611                 if (!value || !*value)
612                         return -EINVAL;
613                 else
614                         *value++ = '\0';
615
616                 if (!strcmp(opt, "uid"))
617                         pconfig->uid = simple_strtoul(value, &value, 0);
618                 else if (!strcmp(opt, "gid"))
619                         pconfig->gid = simple_strtoul(value, &value, 0);
620                 else if (!strcmp(opt, "mode"))
621                         pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
622                 else if (!strcmp(opt, "size")) {
623                         unsigned long long size = memparse(value, &rest);
624                         if (*rest == '%') {
625                                 size <<= HPAGE_SHIFT;
626                                 size *= max_huge_pages;
627                                 do_div(size, 100);
628                                 rest++;
629                         }
630                         size &= HPAGE_MASK;
631                         pconfig->nr_blocks = (size >> HPAGE_SHIFT);
632                         value = rest;
633                 } else if (!strcmp(opt,"nr_inodes")) {
634                         pconfig->nr_inodes = memparse(value, &rest);
635                         value = rest;
636                 } else
637                         return -EINVAL;
638
639                 if (*value)
640                         return -EINVAL;
641         }
642         return 0;
643 }
644
645 static int
646 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
647 {
648         struct inode * inode;
649         struct dentry * root;
650         int ret;
651         struct hugetlbfs_config config;
652         struct hugetlbfs_sb_info *sbinfo;
653
654         config.nr_blocks = -1; /* No limit on size by default */
655         config.nr_inodes = -1; /* No limit on number of inodes by default */
656         config.uid = current->fsuid;
657         config.gid = current->fsgid;
658         config.mode = 0755;
659         ret = hugetlbfs_parse_options(data, &config);
660
661         if (ret)
662                 return ret;
663
664         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
665         if (!sbinfo)
666                 return -ENOMEM;
667         sb->s_fs_info = sbinfo;
668         spin_lock_init(&sbinfo->stat_lock);
669         sbinfo->max_blocks = config.nr_blocks;
670         sbinfo->free_blocks = config.nr_blocks;
671         sbinfo->max_inodes = config.nr_inodes;
672         sbinfo->free_inodes = config.nr_inodes;
673         sb->s_maxbytes = MAX_LFS_FILESIZE;
674         sb->s_blocksize = HPAGE_SIZE;
675         sb->s_blocksize_bits = HPAGE_SHIFT;
676         sb->s_magic = HUGETLBFS_MAGIC;
677         sb->s_op = &hugetlbfs_ops;
678         sb->s_time_gran = 1;
679         inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
680                                         S_IFDIR | config.mode, 0);
681         if (!inode)
682                 goto out_free;
683
684         root = d_alloc_root(inode);
685         if (!root) {
686                 iput(inode);
687                 goto out_free;
688         }
689         sb->s_root = root;
690         return 0;
691 out_free:
692         kfree(sbinfo);
693         return -ENOMEM;
694 }
695
696 int hugetlb_get_quota(struct address_space *mapping)
697 {
698         int ret = 0;
699         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
700
701         if (sbinfo->free_blocks > -1) {
702                 spin_lock(&sbinfo->stat_lock);
703                 if (sbinfo->free_blocks > 0)
704                         sbinfo->free_blocks--;
705                 else
706                         ret = -ENOMEM;
707                 spin_unlock(&sbinfo->stat_lock);
708         }
709
710         return ret;
711 }
712
713 void hugetlb_put_quota(struct address_space *mapping)
714 {
715         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
716
717         if (sbinfo->free_blocks > -1) {
718                 spin_lock(&sbinfo->stat_lock);
719                 sbinfo->free_blocks++;
720                 spin_unlock(&sbinfo->stat_lock);
721         }
722 }
723
724 static struct super_block *hugetlbfs_get_sb(struct file_system_type *fs_type,
725         int flags, const char *dev_name, void *data)
726 {
727         return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super);
728 }
729
730 static struct file_system_type hugetlbfs_fs_type = {
731         .name           = "hugetlbfs",
732         .get_sb         = hugetlbfs_get_sb,
733         .kill_sb        = kill_litter_super,
734 };
735
736 static struct vfsmount *hugetlbfs_vfsmount;
737
738 /*
739  * Return the next identifier for a shm file
740  */
741 static unsigned long hugetlbfs_counter(void)
742 {
743         static DEFINE_SPINLOCK(lock);
744         static unsigned long counter;
745         unsigned long ret;
746
747         spin_lock(&lock);
748         ret = ++counter;
749         spin_unlock(&lock);
750         return ret;
751 }
752
753 static int can_do_hugetlb_shm(void)
754 {
755         return likely(capable(CAP_IPC_LOCK) ||
756                         in_group_p(sysctl_hugetlb_shm_group) ||
757                         can_do_mlock());
758 }
759
760 struct file *hugetlb_zero_setup(size_t size)
761 {
762         int error = -ENOMEM;
763         struct file *file;
764         struct inode *inode;
765         struct dentry *dentry, *root;
766         struct qstr quick_string;
767         char buf[16];
768
769         if (!can_do_hugetlb_shm())
770                 return ERR_PTR(-EPERM);
771
772         if (!is_hugepage_mem_enough(size))
773                 return ERR_PTR(-ENOMEM);
774
775         if (!user_shm_lock(size, current->user))
776                 return ERR_PTR(-ENOMEM);
777
778         root = hugetlbfs_vfsmount->mnt_root;
779         snprintf(buf, 16, "%lu", hugetlbfs_counter());
780         quick_string.name = buf;
781         quick_string.len = strlen(quick_string.name);
782         quick_string.hash = 0;
783         dentry = d_alloc(root, &quick_string);
784         if (!dentry)
785                 goto out_shm_unlock;
786
787         error = -ENFILE;
788         file = get_empty_filp();
789         if (!file)
790                 goto out_dentry;
791
792         error = -ENOSPC;
793         inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
794                                 current->fsgid, S_IFREG | S_IRWXUGO, 0);
795         if (!inode)
796                 goto out_file;
797
798         d_instantiate(dentry, inode);
799         inode->i_size = size;
800         inode->i_nlink = 0;
801         file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
802         file->f_dentry = dentry;
803         file->f_mapping = inode->i_mapping;
804         file->f_op = &hugetlbfs_file_operations;
805         file->f_mode = FMODE_WRITE | FMODE_READ;
806         return file;
807
808 out_file:
809         put_filp(file);
810 out_dentry:
811         dput(dentry);
812 out_shm_unlock:
813         user_shm_unlock(size, current->user);
814         return ERR_PTR(error);
815 }
816
817 static int __init init_hugetlbfs_fs(void)
818 {
819         int error;
820         struct vfsmount *vfsmount;
821
822         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
823                                         sizeof(struct hugetlbfs_inode_info),
824                                         0, 0, init_once, NULL);
825         if (hugetlbfs_inode_cachep == NULL)
826                 return -ENOMEM;
827
828         error = register_filesystem(&hugetlbfs_fs_type);
829         if (error)
830                 goto out;
831
832         vfsmount = kern_mount(&hugetlbfs_fs_type);
833
834         if (!IS_ERR(vfsmount)) {
835                 hugetlbfs_vfsmount = vfsmount;
836                 return 0;
837         }
838
839         error = PTR_ERR(vfsmount);
840
841  out:
842         if (error)
843                 kmem_cache_destroy(hugetlbfs_inode_cachep);
844         return error;
845 }
846
847 static void __exit exit_hugetlbfs_fs(void)
848 {
849         kmem_cache_destroy(hugetlbfs_inode_cachep);
850         unregister_filesystem(&hugetlbfs_fs_type);
851 }
852
853 module_init(init_hugetlbfs_fs)
854 module_exit(exit_hugetlbfs_fs)
855
856 MODULE_LICENSE("GPL");