0bea6a619e100e0baa4eee8bc689c935b88ff2cc
[linux-2.6.git] / 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/capability.h>
22 #include <linux/backing-dev.h>
23 #include <linux/hugetlb.h>
24 #include <linux/pagevec.h>
25 #include <linux/quotaops.h>
26 #include <linux/slab.h>
27 #include <linux/dnotify.h>
28 #include <linux/statfs.h>
29 #include <linux/security.h>
30
31 #include <asm/uaccess.h>
32
33 /* some random number */
34 #define HUGETLBFS_MAGIC 0x958458f6
35
36 static struct super_operations hugetlbfs_ops;
37 static const struct address_space_operations hugetlbfs_aops;
38 const struct file_operations hugetlbfs_file_operations;
39 static struct inode_operations hugetlbfs_dir_inode_operations;
40 static struct inode_operations hugetlbfs_inode_operations;
41
42 static struct backing_dev_info hugetlbfs_backing_dev_info = {
43         .ra_pages       = 0,    /* No readahead */
44         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
45 };
46
47 int sysctl_hugetlb_shm_group;
48
49 static void huge_pagevec_release(struct pagevec *pvec)
50 {
51         int i;
52
53         for (i = 0; i < pagevec_count(pvec); ++i)
54                 put_page(pvec->pages[i]);
55
56         pagevec_reinit(pvec);
57 }
58
59 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
60 {
61         struct inode *inode = file->f_dentry->d_inode;
62         loff_t len, vma_len;
63         int ret;
64
65         if (vma->vm_pgoff & (HPAGE_SIZE / PAGE_SIZE - 1))
66                 return -EINVAL;
67
68         if (vma->vm_start & ~HPAGE_MASK)
69                 return -EINVAL;
70
71         if (vma->vm_end & ~HPAGE_MASK)
72                 return -EINVAL;
73
74         if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
75                 return -EINVAL;
76
77         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
78
79         mutex_lock(&inode->i_mutex);
80         file_accessed(file);
81         vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
82         vma->vm_ops = &hugetlb_vm_ops;
83
84         ret = -ENOMEM;
85         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
86
87         if (vma->vm_flags & VM_MAYSHARE &&
88             hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
89                                   len >> HPAGE_SHIFT))
90                 goto out;
91
92         ret = 0;
93         hugetlb_prefault_arch_hook(vma->vm_mm);
94         if (vma->vm_flags & VM_WRITE && inode->i_size < len)
95                 inode->i_size = len;
96 out:
97         mutex_unlock(&inode->i_mutex);
98
99         return ret;
100 }
101
102 /*
103  * Called under down_write(mmap_sem).
104  */
105
106 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
107 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
108                 unsigned long len, unsigned long pgoff, unsigned long flags);
109 #else
110 static unsigned long
111 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
112                 unsigned long len, unsigned long pgoff, unsigned long flags)
113 {
114         struct mm_struct *mm = current->mm;
115         struct vm_area_struct *vma;
116         unsigned long start_addr;
117
118         if (len & ~HPAGE_MASK)
119                 return -EINVAL;
120         if (len > TASK_SIZE)
121                 return -ENOMEM;
122
123         if (addr) {
124                 addr = ALIGN(addr, HPAGE_SIZE);
125                 vma = find_vma(mm, addr);
126                 if (TASK_SIZE - len >= addr &&
127                     (!vma || addr + len <= vma->vm_start))
128                         return addr;
129         }
130
131         start_addr = mm->free_area_cache;
132
133         if (len <= mm->cached_hole_size)
134                 start_addr = TASK_UNMAPPED_BASE;
135
136 full_search:
137         addr = ALIGN(start_addr, HPAGE_SIZE);
138
139         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
140                 /* At this point:  (!vma || addr < vma->vm_end). */
141                 if (TASK_SIZE - len < addr) {
142                         /*
143                          * Start a new search - just in case we missed
144                          * some holes.
145                          */
146                         if (start_addr != TASK_UNMAPPED_BASE) {
147                                 start_addr = TASK_UNMAPPED_BASE;
148                                 goto full_search;
149                         }
150                         return -ENOMEM;
151                 }
152
153                 if (!vma || addr + len <= vma->vm_start)
154                         return addr;
155                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
156         }
157 }
158 #endif
159
160 /*
161  * Read a page. Again trivial. If it didn't already exist
162  * in the page cache, it is zero-filled.
163  */
164 static int hugetlbfs_readpage(struct file *file, struct page * page)
165 {
166         unlock_page(page);
167         return -EINVAL;
168 }
169
170 static int hugetlbfs_prepare_write(struct file *file,
171                         struct page *page, unsigned offset, unsigned to)
172 {
173         return -EINVAL;
174 }
175
176 static int hugetlbfs_commit_write(struct file *file,
177                         struct page *page, unsigned offset, unsigned to)
178 {
179         return -EINVAL;
180 }
181
182 static void truncate_huge_page(struct page *page)
183 {
184         clear_page_dirty(page);
185         ClearPageUptodate(page);
186         remove_from_page_cache(page);
187         put_page(page);
188 }
189
190 static void truncate_hugepages(struct inode *inode, loff_t lstart)
191 {
192         struct address_space *mapping = &inode->i_data;
193         const pgoff_t start = lstart >> HPAGE_SHIFT;
194         struct pagevec pvec;
195         pgoff_t next;
196         int i, freed = 0;
197
198         pagevec_init(&pvec, 0);
199         next = start;
200         while (1) {
201                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
202                         if (next == start)
203                                 break;
204                         next = start;
205                         continue;
206                 }
207
208                 for (i = 0; i < pagevec_count(&pvec); ++i) {
209                         struct page *page = pvec.pages[i];
210
211                         lock_page(page);
212                         if (page->index > next)
213                                 next = page->index;
214                         ++next;
215                         truncate_huge_page(page);
216                         unlock_page(page);
217                         hugetlb_put_quota(mapping);
218                         freed++;
219                 }
220                 huge_pagevec_release(&pvec);
221         }
222         BUG_ON(!lstart && mapping->nrpages);
223         hugetlb_unreserve_pages(inode, start, freed);
224 }
225
226 static void hugetlbfs_delete_inode(struct inode *inode)
227 {
228         truncate_hugepages(inode, 0);
229         clear_inode(inode);
230 }
231
232 static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
233 {
234         struct super_block *sb = inode->i_sb;
235
236         if (!hlist_unhashed(&inode->i_hash)) {
237                 if (!(inode->i_state & (I_DIRTY|I_LOCK)))
238                         list_move(&inode->i_list, &inode_unused);
239                 inodes_stat.nr_unused++;
240                 if (!sb || (sb->s_flags & MS_ACTIVE)) {
241                         spin_unlock(&inode_lock);
242                         return;
243                 }
244                 inode->i_state |= I_WILL_FREE;
245                 spin_unlock(&inode_lock);
246                 /*
247                  * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
248                  * in our backing_dev_info.
249                  */
250                 write_inode_now(inode, 1);
251                 spin_lock(&inode_lock);
252                 inode->i_state &= ~I_WILL_FREE;
253                 inodes_stat.nr_unused--;
254                 hlist_del_init(&inode->i_hash);
255         }
256         list_del_init(&inode->i_list);
257         list_del_init(&inode->i_sb_list);
258         inode->i_state |= I_FREEING;
259         inodes_stat.nr_inodes--;
260         spin_unlock(&inode_lock);
261         truncate_hugepages(inode, 0);
262         clear_inode(inode);
263         destroy_inode(inode);
264 }
265
266 static void hugetlbfs_drop_inode(struct inode *inode)
267 {
268         if (!inode->i_nlink)
269                 generic_delete_inode(inode);
270         else
271                 hugetlbfs_forget_inode(inode);
272 }
273
274 static inline void
275 hugetlb_vmtruncate_list(struct prio_tree_root *root, pgoff_t pgoff)
276 {
277         struct vm_area_struct *vma;
278         struct prio_tree_iter iter;
279
280         vma_prio_tree_foreach(vma, &iter, root, pgoff, ULONG_MAX) {
281                 unsigned long v_offset;
282
283                 /*
284                  * Can the expression below overflow on 32-bit arches?
285                  * No, because the prio_tree returns us only those vmas
286                  * which overlap the truncated area starting at pgoff,
287                  * and no vma on a 32-bit arch can span beyond the 4GB.
288                  */
289                 if (vma->vm_pgoff < pgoff)
290                         v_offset = (pgoff - vma->vm_pgoff) << PAGE_SHIFT;
291                 else
292                         v_offset = 0;
293
294                 __unmap_hugepage_range(vma,
295                                 vma->vm_start + v_offset, vma->vm_end);
296         }
297 }
298
299 /*
300  * Expanding truncates are not allowed.
301  */
302 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
303 {
304         pgoff_t pgoff;
305         struct address_space *mapping = inode->i_mapping;
306
307         if (offset > inode->i_size)
308                 return -EINVAL;
309
310         BUG_ON(offset & ~HPAGE_MASK);
311         pgoff = offset >> PAGE_SHIFT;
312
313         inode->i_size = offset;
314         spin_lock(&mapping->i_mmap_lock);
315         if (!prio_tree_empty(&mapping->i_mmap))
316                 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
317         spin_unlock(&mapping->i_mmap_lock);
318         truncate_hugepages(inode, offset);
319         return 0;
320 }
321
322 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
323 {
324         struct inode *inode = dentry->d_inode;
325         int error;
326         unsigned int ia_valid = attr->ia_valid;
327
328         BUG_ON(!inode);
329
330         error = inode_change_ok(inode, attr);
331         if (error)
332                 goto out;
333
334         if (ia_valid & ATTR_SIZE) {
335                 error = -EINVAL;
336                 if (!(attr->ia_size & ~HPAGE_MASK))
337                         error = hugetlb_vmtruncate(inode, attr->ia_size);
338                 if (error)
339                         goto out;
340                 attr->ia_valid &= ~ATTR_SIZE;
341         }
342         error = inode_setattr(inode, attr);
343 out:
344         return error;
345 }
346
347 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid, 
348                                         gid_t gid, int mode, dev_t dev)
349 {
350         struct inode *inode;
351
352         inode = new_inode(sb);
353         if (inode) {
354                 struct hugetlbfs_inode_info *info;
355                 inode->i_mode = mode;
356                 inode->i_uid = uid;
357                 inode->i_gid = gid;
358                 inode->i_blocks = 0;
359                 inode->i_mapping->a_ops = &hugetlbfs_aops;
360                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
361                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
362                 INIT_LIST_HEAD(&inode->i_mapping->private_list);
363                 info = HUGETLBFS_I(inode);
364                 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
365                 switch (mode & S_IFMT) {
366                 default:
367                         init_special_inode(inode, mode, dev);
368                         break;
369                 case S_IFREG:
370                         inode->i_op = &hugetlbfs_inode_operations;
371                         inode->i_fop = &hugetlbfs_file_operations;
372                         break;
373                 case S_IFDIR:
374                         inode->i_op = &hugetlbfs_dir_inode_operations;
375                         inode->i_fop = &simple_dir_operations;
376
377                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
378                         inc_nlink(inode);
379                         break;
380                 case S_IFLNK:
381                         inode->i_op = &page_symlink_inode_operations;
382                         break;
383                 }
384         }
385         return inode;
386 }
387
388 /*
389  * File creation. Allocate an inode, and we're done..
390  */
391 static int hugetlbfs_mknod(struct inode *dir,
392                         struct dentry *dentry, int mode, dev_t dev)
393 {
394         struct inode *inode;
395         int error = -ENOSPC;
396         gid_t gid;
397
398         if (dir->i_mode & S_ISGID) {
399                 gid = dir->i_gid;
400                 if (S_ISDIR(mode))
401                         mode |= S_ISGID;
402         } else {
403                 gid = current->fsgid;
404         }
405         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
406         if (inode) {
407                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
408                 d_instantiate(dentry, inode);
409                 dget(dentry);   /* Extra count - pin the dentry in core */
410                 error = 0;
411         }
412         return error;
413 }
414
415 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
416 {
417         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
418         if (!retval)
419                 inc_nlink(dir);
420         return retval;
421 }
422
423 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
424 {
425         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
426 }
427
428 static int hugetlbfs_symlink(struct inode *dir,
429                         struct dentry *dentry, const char *symname)
430 {
431         struct inode *inode;
432         int error = -ENOSPC;
433         gid_t gid;
434
435         if (dir->i_mode & S_ISGID)
436                 gid = dir->i_gid;
437         else
438                 gid = current->fsgid;
439
440         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
441                                         gid, S_IFLNK|S_IRWXUGO, 0);
442         if (inode) {
443                 int l = strlen(symname)+1;
444                 error = page_symlink(inode, symname, l);
445                 if (!error) {
446                         d_instantiate(dentry, inode);
447                         dget(dentry);
448                 } else
449                         iput(inode);
450         }
451         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
452
453         return error;
454 }
455
456 /*
457  * For direct-IO reads into hugetlb pages
458  */
459 static int hugetlbfs_set_page_dirty(struct page *page)
460 {
461         return 0;
462 }
463
464 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
465 {
466         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
467
468         buf->f_type = HUGETLBFS_MAGIC;
469         buf->f_bsize = HPAGE_SIZE;
470         if (sbinfo) {
471                 spin_lock(&sbinfo->stat_lock);
472                 /* If no limits set, just report 0 for max/free/used
473                  * blocks, like simple_statfs() */
474                 if (sbinfo->max_blocks >= 0) {
475                         buf->f_blocks = sbinfo->max_blocks;
476                         buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
477                         buf->f_files = sbinfo->max_inodes;
478                         buf->f_ffree = sbinfo->free_inodes;
479                 }
480                 spin_unlock(&sbinfo->stat_lock);
481         }
482         buf->f_namelen = NAME_MAX;
483         return 0;
484 }
485
486 static void hugetlbfs_put_super(struct super_block *sb)
487 {
488         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
489
490         if (sbi) {
491                 sb->s_fs_info = NULL;
492                 kfree(sbi);
493         }
494 }
495
496 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
497 {
498         if (sbinfo->free_inodes >= 0) {
499                 spin_lock(&sbinfo->stat_lock);
500                 if (unlikely(!sbinfo->free_inodes)) {
501                         spin_unlock(&sbinfo->stat_lock);
502                         return 0;
503                 }
504                 sbinfo->free_inodes--;
505                 spin_unlock(&sbinfo->stat_lock);
506         }
507
508         return 1;
509 }
510
511 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
512 {
513         if (sbinfo->free_inodes >= 0) {
514                 spin_lock(&sbinfo->stat_lock);
515                 sbinfo->free_inodes++;
516                 spin_unlock(&sbinfo->stat_lock);
517         }
518 }
519
520
521 static kmem_cache_t *hugetlbfs_inode_cachep;
522
523 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
524 {
525         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
526         struct hugetlbfs_inode_info *p;
527
528         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
529                 return NULL;
530         p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
531         if (unlikely(!p)) {
532                 hugetlbfs_inc_free_inodes(sbinfo);
533                 return NULL;
534         }
535         return &p->vfs_inode;
536 }
537
538 static void hugetlbfs_destroy_inode(struct inode *inode)
539 {
540         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
541         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
542         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
543 }
544
545 static const struct address_space_operations hugetlbfs_aops = {
546         .readpage       = hugetlbfs_readpage,
547         .prepare_write  = hugetlbfs_prepare_write,
548         .commit_write   = hugetlbfs_commit_write,
549         .set_page_dirty = hugetlbfs_set_page_dirty,
550 };
551
552
553 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
554 {
555         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
556
557         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
558             SLAB_CTOR_CONSTRUCTOR)
559                 inode_init_once(&ei->vfs_inode);
560 }
561
562 const struct file_operations hugetlbfs_file_operations = {
563         .mmap                   = hugetlbfs_file_mmap,
564         .fsync                  = simple_sync_file,
565         .get_unmapped_area      = hugetlb_get_unmapped_area,
566 };
567
568 static struct inode_operations hugetlbfs_dir_inode_operations = {
569         .create         = hugetlbfs_create,
570         .lookup         = simple_lookup,
571         .link           = simple_link,
572         .unlink         = simple_unlink,
573         .symlink        = hugetlbfs_symlink,
574         .mkdir          = hugetlbfs_mkdir,
575         .rmdir          = simple_rmdir,
576         .mknod          = hugetlbfs_mknod,
577         .rename         = simple_rename,
578         .setattr        = hugetlbfs_setattr,
579 };
580
581 static struct inode_operations hugetlbfs_inode_operations = {
582         .setattr        = hugetlbfs_setattr,
583 };
584
585 static struct super_operations hugetlbfs_ops = {
586         .alloc_inode    = hugetlbfs_alloc_inode,
587         .destroy_inode  = hugetlbfs_destroy_inode,
588         .statfs         = hugetlbfs_statfs,
589         .delete_inode   = hugetlbfs_delete_inode,
590         .drop_inode     = hugetlbfs_drop_inode,
591         .put_super      = hugetlbfs_put_super,
592 };
593
594 static int
595 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
596 {
597         char *opt, *value, *rest;
598
599         if (!options)
600                 return 0;
601         while ((opt = strsep(&options, ",")) != NULL) {
602                 if (!*opt)
603                         continue;
604
605                 value = strchr(opt, '=');
606                 if (!value || !*value)
607                         return -EINVAL;
608                 else
609                         *value++ = '\0';
610
611                 if (!strcmp(opt, "uid"))
612                         pconfig->uid = simple_strtoul(value, &value, 0);
613                 else if (!strcmp(opt, "gid"))
614                         pconfig->gid = simple_strtoul(value, &value, 0);
615                 else if (!strcmp(opt, "mode"))
616                         pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
617                 else if (!strcmp(opt, "size")) {
618                         unsigned long long size = memparse(value, &rest);
619                         if (*rest == '%') {
620                                 size <<= HPAGE_SHIFT;
621                                 size *= max_huge_pages;
622                                 do_div(size, 100);
623                                 rest++;
624                         }
625                         pconfig->nr_blocks = (size >> HPAGE_SHIFT);
626                         value = rest;
627                 } else if (!strcmp(opt,"nr_inodes")) {
628                         pconfig->nr_inodes = memparse(value, &rest);
629                         value = rest;
630                 } else
631                         return -EINVAL;
632
633                 if (*value)
634                         return -EINVAL;
635         }
636         return 0;
637 }
638
639 static int
640 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
641 {
642         struct inode * inode;
643         struct dentry * root;
644         int ret;
645         struct hugetlbfs_config config;
646         struct hugetlbfs_sb_info *sbinfo;
647
648         config.nr_blocks = -1; /* No limit on size by default */
649         config.nr_inodes = -1; /* No limit on number of inodes by default */
650         config.uid = current->fsuid;
651         config.gid = current->fsgid;
652         config.mode = 0755;
653         ret = hugetlbfs_parse_options(data, &config);
654
655         if (ret)
656                 return ret;
657
658         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
659         if (!sbinfo)
660                 return -ENOMEM;
661         sb->s_fs_info = sbinfo;
662         spin_lock_init(&sbinfo->stat_lock);
663         sbinfo->max_blocks = config.nr_blocks;
664         sbinfo->free_blocks = config.nr_blocks;
665         sbinfo->max_inodes = config.nr_inodes;
666         sbinfo->free_inodes = config.nr_inodes;
667         sb->s_maxbytes = MAX_LFS_FILESIZE;
668         sb->s_blocksize = HPAGE_SIZE;
669         sb->s_blocksize_bits = HPAGE_SHIFT;
670         sb->s_magic = HUGETLBFS_MAGIC;
671         sb->s_op = &hugetlbfs_ops;
672         sb->s_time_gran = 1;
673         inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
674                                         S_IFDIR | config.mode, 0);
675         if (!inode)
676                 goto out_free;
677
678         root = d_alloc_root(inode);
679         if (!root) {
680                 iput(inode);
681                 goto out_free;
682         }
683         sb->s_root = root;
684         return 0;
685 out_free:
686         kfree(sbinfo);
687         return -ENOMEM;
688 }
689
690 int hugetlb_get_quota(struct address_space *mapping)
691 {
692         int ret = 0;
693         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
694
695         if (sbinfo->free_blocks > -1) {
696                 spin_lock(&sbinfo->stat_lock);
697                 if (sbinfo->free_blocks > 0)
698                         sbinfo->free_blocks--;
699                 else
700                         ret = -ENOMEM;
701                 spin_unlock(&sbinfo->stat_lock);
702         }
703
704         return ret;
705 }
706
707 void hugetlb_put_quota(struct address_space *mapping)
708 {
709         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
710
711         if (sbinfo->free_blocks > -1) {
712                 spin_lock(&sbinfo->stat_lock);
713                 sbinfo->free_blocks++;
714                 spin_unlock(&sbinfo->stat_lock);
715         }
716 }
717
718 static int hugetlbfs_get_sb(struct file_system_type *fs_type,
719         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
720 {
721         return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
722 }
723
724 static struct file_system_type hugetlbfs_fs_type = {
725         .name           = "hugetlbfs",
726         .get_sb         = hugetlbfs_get_sb,
727         .kill_sb        = kill_litter_super,
728 };
729
730 static struct vfsmount *hugetlbfs_vfsmount;
731
732 static int can_do_hugetlb_shm(void)
733 {
734         return likely(capable(CAP_IPC_LOCK) ||
735                         in_group_p(sysctl_hugetlb_shm_group) ||
736                         can_do_mlock());
737 }
738
739 struct file *hugetlb_zero_setup(size_t size)
740 {
741         int error = -ENOMEM;
742         struct file *file;
743         struct inode *inode;
744         struct dentry *dentry, *root;
745         struct qstr quick_string;
746         char buf[16];
747         static atomic_t counter;
748
749         if (!can_do_hugetlb_shm())
750                 return ERR_PTR(-EPERM);
751
752         if (!user_shm_lock(size, current->user))
753                 return ERR_PTR(-ENOMEM);
754
755         root = hugetlbfs_vfsmount->mnt_root;
756         snprintf(buf, 16, "%u", atomic_inc_return(&counter));
757         quick_string.name = buf;
758         quick_string.len = strlen(quick_string.name);
759         quick_string.hash = 0;
760         dentry = d_alloc(root, &quick_string);
761         if (!dentry)
762                 goto out_shm_unlock;
763
764         error = -ENFILE;
765         file = get_empty_filp();
766         if (!file)
767                 goto out_dentry;
768
769         error = -ENOSPC;
770         inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
771                                 current->fsgid, S_IFREG | S_IRWXUGO, 0);
772         if (!inode)
773                 goto out_file;
774
775         error = -ENOMEM;
776         if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
777                 goto out_inode;
778
779         d_instantiate(dentry, inode);
780         inode->i_size = size;
781         inode->i_nlink = 0;
782         file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
783         file->f_dentry = dentry;
784         file->f_mapping = inode->i_mapping;
785         file->f_op = &hugetlbfs_file_operations;
786         file->f_mode = FMODE_WRITE | FMODE_READ;
787         return file;
788
789 out_inode:
790         iput(inode);
791 out_file:
792         put_filp(file);
793 out_dentry:
794         dput(dentry);
795 out_shm_unlock:
796         user_shm_unlock(size, current->user);
797         return ERR_PTR(error);
798 }
799
800 static int __init init_hugetlbfs_fs(void)
801 {
802         int error;
803         struct vfsmount *vfsmount;
804
805         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
806                                         sizeof(struct hugetlbfs_inode_info),
807                                         0, 0, init_once, NULL);
808         if (hugetlbfs_inode_cachep == NULL)
809                 return -ENOMEM;
810
811         error = register_filesystem(&hugetlbfs_fs_type);
812         if (error)
813                 goto out;
814
815         vfsmount = kern_mount(&hugetlbfs_fs_type);
816
817         if (!IS_ERR(vfsmount)) {
818                 hugetlbfs_vfsmount = vfsmount;
819                 return 0;
820         }
821
822         error = PTR_ERR(vfsmount);
823
824  out:
825         if (error)
826                 kmem_cache_destroy(hugetlbfs_inode_cachep);
827         return error;
828 }
829
830 static void __exit exit_hugetlbfs_fs(void)
831 {
832         kmem_cache_destroy(hugetlbfs_inode_cachep);
833         unregister_filesystem(&hugetlbfs_fs_type);
834 }
835
836 module_init(init_hugetlbfs_fs)
837 module_exit(exit_hugetlbfs_fs)
838
839 MODULE_LICENSE("GPL");