[PATCH] hugetlbfs: clean up hugetlbfs_delete_inode
[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/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).
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         if (inode->i_data.nrpages)
228                 truncate_hugepages(&inode->i_data, 0);
229         clear_inode(inode);
230 }
231
232 static void hugetlbfs_do_delete_inode(struct inode *inode)
233 {
234         struct super_operations *op = inode->i_sb->s_op;
235
236         list_del_init(&inode->i_list);
237         list_del_init(&inode->i_sb_list);
238         inode->i_state |= I_FREEING;
239         inodes_stat.nr_inodes--;
240         spin_unlock(&inode_lock);
241
242         security_inode_delete(inode);
243
244         if (op->delete_inode) {
245                 void (*delete)(struct inode *) = op->delete_inode;
246                 if (!is_bad_inode(inode))
247                         DQUOT_INIT(inode);
248                 /* Filesystems implementing their own
249                  * s_op->delete_inode are required to call
250                  * truncate_inode_pages and clear_inode()
251                  * internally
252                  */
253                 delete(inode);
254         } else {
255                 truncate_inode_pages(&inode->i_data, 0);
256                 clear_inode(inode);
257         }
258
259         spin_lock(&inode_lock);
260         hlist_del_init(&inode->i_hash);
261         spin_unlock(&inode_lock);
262         wake_up_inode(inode);
263         if (inode->i_state != I_CLEAR)
264                 BUG();
265         destroy_inode(inode);
266 }
267
268 static void hugetlbfs_forget_inode(struct inode *inode)
269 {
270         struct super_block *super_block = inode->i_sb;
271
272         if (hlist_unhashed(&inode->i_hash))
273                 goto out_truncate;
274
275         if (!(inode->i_state & (I_DIRTY|I_LOCK))) {
276                 list_del(&inode->i_list);
277                 list_add(&inode->i_list, &inode_unused);
278         }
279         inodes_stat.nr_unused++;
280         if (!super_block || (super_block->s_flags & MS_ACTIVE)) {
281                 spin_unlock(&inode_lock);
282                 return;
283         }
284
285         /* write_inode_now() ? */
286         inodes_stat.nr_unused--;
287         hlist_del_init(&inode->i_hash);
288 out_truncate:
289         list_del_init(&inode->i_list);
290         list_del_init(&inode->i_sb_list);
291         inode->i_state |= I_FREEING;
292         inodes_stat.nr_inodes--;
293         spin_unlock(&inode_lock);
294         if (inode->i_data.nrpages)
295                 truncate_hugepages(&inode->i_data, 0);
296
297         clear_inode(inode);
298         destroy_inode(inode);
299 }
300
301 static void hugetlbfs_drop_inode(struct inode *inode)
302 {
303         if (!inode->i_nlink)
304                 hugetlbfs_do_delete_inode(inode);
305         else
306                 hugetlbfs_forget_inode(inode);
307 }
308
309 /*
310  * h_pgoff is in HPAGE_SIZE units.
311  * vma->vm_pgoff is in PAGE_SIZE units.
312  */
313 static inline void
314 hugetlb_vmtruncate_list(struct prio_tree_root *root, unsigned long h_pgoff)
315 {
316         struct vm_area_struct *vma;
317         struct prio_tree_iter iter;
318
319         vma_prio_tree_foreach(vma, &iter, root, h_pgoff, ULONG_MAX) {
320                 unsigned long h_vm_pgoff;
321                 unsigned long v_offset;
322
323                 h_vm_pgoff = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
324                 v_offset = (h_pgoff - h_vm_pgoff) << HPAGE_SHIFT;
325                 /*
326                  * Is this VMA fully outside the truncation point?
327                  */
328                 if (h_vm_pgoff >= h_pgoff)
329                         v_offset = 0;
330
331                 unmap_hugepage_range(vma,
332                                 vma->vm_start + v_offset, vma->vm_end);
333         }
334 }
335
336 /*
337  * Expanding truncates are not allowed.
338  */
339 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
340 {
341         unsigned long pgoff;
342         struct address_space *mapping = inode->i_mapping;
343
344         if (offset > inode->i_size)
345                 return -EINVAL;
346
347         BUG_ON(offset & ~HPAGE_MASK);
348         pgoff = offset >> HPAGE_SHIFT;
349
350         inode->i_size = offset;
351         spin_lock(&mapping->i_mmap_lock);
352         if (!prio_tree_empty(&mapping->i_mmap))
353                 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
354         spin_unlock(&mapping->i_mmap_lock);
355         truncate_hugepages(mapping, offset);
356         return 0;
357 }
358
359 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
360 {
361         struct inode *inode = dentry->d_inode;
362         int error;
363         unsigned int ia_valid = attr->ia_valid;
364
365         BUG_ON(!inode);
366
367         error = inode_change_ok(inode, attr);
368         if (error)
369                 goto out;
370
371         if (ia_valid & ATTR_SIZE) {
372                 error = -EINVAL;
373                 if (!(attr->ia_size & ~HPAGE_MASK))
374                         error = hugetlb_vmtruncate(inode, attr->ia_size);
375                 if (error)
376                         goto out;
377                 attr->ia_valid &= ~ATTR_SIZE;
378         }
379         error = inode_setattr(inode, attr);
380 out:
381         return error;
382 }
383
384 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid, 
385                                         gid_t gid, int mode, dev_t dev)
386 {
387         struct inode *inode;
388
389         inode = new_inode(sb);
390         if (inode) {
391                 struct hugetlbfs_inode_info *info;
392                 inode->i_mode = mode;
393                 inode->i_uid = uid;
394                 inode->i_gid = gid;
395                 inode->i_blksize = HPAGE_SIZE;
396                 inode->i_blocks = 0;
397                 inode->i_mapping->a_ops = &hugetlbfs_aops;
398                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
399                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
400                 info = HUGETLBFS_I(inode);
401                 mpol_shared_policy_init(&info->policy);
402                 switch (mode & S_IFMT) {
403                 default:
404                         init_special_inode(inode, mode, dev);
405                         break;
406                 case S_IFREG:
407                         inode->i_op = &hugetlbfs_inode_operations;
408                         inode->i_fop = &hugetlbfs_file_operations;
409                         break;
410                 case S_IFDIR:
411                         inode->i_op = &hugetlbfs_dir_inode_operations;
412                         inode->i_fop = &simple_dir_operations;
413
414                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
415                         inode->i_nlink++;
416                         break;
417                 case S_IFLNK:
418                         inode->i_op = &page_symlink_inode_operations;
419                         break;
420                 }
421         }
422         return inode;
423 }
424
425 /*
426  * File creation. Allocate an inode, and we're done..
427  */
428 static int hugetlbfs_mknod(struct inode *dir,
429                         struct dentry *dentry, int mode, dev_t dev)
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                 if (S_ISDIR(mode))
438                         mode |= S_ISGID;
439         } else {
440                 gid = current->fsgid;
441         }
442         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
443         if (inode) {
444                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
445                 d_instantiate(dentry, inode);
446                 dget(dentry);   /* Extra count - pin the dentry in core */
447                 error = 0;
448         }
449         return error;
450 }
451
452 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
453 {
454         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
455         if (!retval)
456                 dir->i_nlink++;
457         return retval;
458 }
459
460 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
461 {
462         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
463 }
464
465 static int hugetlbfs_symlink(struct inode *dir,
466                         struct dentry *dentry, const char *symname)
467 {
468         struct inode *inode;
469         int error = -ENOSPC;
470         gid_t gid;
471
472         if (dir->i_mode & S_ISGID)
473                 gid = dir->i_gid;
474         else
475                 gid = current->fsgid;
476
477         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
478                                         gid, S_IFLNK|S_IRWXUGO, 0);
479         if (inode) {
480                 int l = strlen(symname)+1;
481                 error = page_symlink(inode, symname, l);
482                 if (!error) {
483                         d_instantiate(dentry, inode);
484                         dget(dentry);
485                 } else
486                         iput(inode);
487         }
488         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
489
490         return error;
491 }
492
493 /*
494  * For direct-IO reads into hugetlb pages
495  */
496 static int hugetlbfs_set_page_dirty(struct page *page)
497 {
498         return 0;
499 }
500
501 static int hugetlbfs_statfs(struct super_block *sb, struct kstatfs *buf)
502 {
503         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
504
505         buf->f_type = HUGETLBFS_MAGIC;
506         buf->f_bsize = HPAGE_SIZE;
507         if (sbinfo) {
508                 spin_lock(&sbinfo->stat_lock);
509                 buf->f_blocks = sbinfo->max_blocks;
510                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
511                 buf->f_files = sbinfo->max_inodes;
512                 buf->f_ffree = sbinfo->free_inodes;
513                 spin_unlock(&sbinfo->stat_lock);
514         }
515         buf->f_namelen = NAME_MAX;
516         return 0;
517 }
518
519 static void hugetlbfs_put_super(struct super_block *sb)
520 {
521         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
522
523         if (sbi) {
524                 sb->s_fs_info = NULL;
525                 kfree(sbi);
526         }
527 }
528
529 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
530 {
531         if (sbinfo->free_inodes >= 0) {
532                 spin_lock(&sbinfo->stat_lock);
533                 if (unlikely(!sbinfo->free_inodes)) {
534                         spin_unlock(&sbinfo->stat_lock);
535                         return 0;
536                 }
537                 sbinfo->free_inodes--;
538                 spin_unlock(&sbinfo->stat_lock);
539         }
540
541         return 1;
542 }
543
544 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
545 {
546         if (sbinfo->free_inodes >= 0) {
547                 spin_lock(&sbinfo->stat_lock);
548                 sbinfo->free_inodes++;
549                 spin_unlock(&sbinfo->stat_lock);
550         }
551 }
552
553
554 static kmem_cache_t *hugetlbfs_inode_cachep;
555
556 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
557 {
558         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
559         struct hugetlbfs_inode_info *p;
560
561         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
562                 return NULL;
563         p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
564         if (unlikely(!p)) {
565                 hugetlbfs_inc_free_inodes(sbinfo);
566                 return NULL;
567         }
568         return &p->vfs_inode;
569 }
570
571 static void hugetlbfs_destroy_inode(struct inode *inode)
572 {
573         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
574         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
575         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
576 }
577
578 static struct address_space_operations hugetlbfs_aops = {
579         .readpage       = hugetlbfs_readpage,
580         .prepare_write  = hugetlbfs_prepare_write,
581         .commit_write   = hugetlbfs_commit_write,
582         .set_page_dirty = hugetlbfs_set_page_dirty,
583 };
584
585
586 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
587 {
588         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
589
590         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
591             SLAB_CTOR_CONSTRUCTOR)
592                 inode_init_once(&ei->vfs_inode);
593 }
594
595 struct file_operations hugetlbfs_file_operations = {
596         .mmap                   = hugetlbfs_file_mmap,
597         .fsync                  = simple_sync_file,
598         .get_unmapped_area      = hugetlb_get_unmapped_area,
599 };
600
601 static struct inode_operations hugetlbfs_dir_inode_operations = {
602         .create         = hugetlbfs_create,
603         .lookup         = simple_lookup,
604         .link           = simple_link,
605         .unlink         = simple_unlink,
606         .symlink        = hugetlbfs_symlink,
607         .mkdir          = hugetlbfs_mkdir,
608         .rmdir          = simple_rmdir,
609         .mknod          = hugetlbfs_mknod,
610         .rename         = simple_rename,
611         .setattr        = hugetlbfs_setattr,
612 };
613
614 static struct inode_operations hugetlbfs_inode_operations = {
615         .setattr        = hugetlbfs_setattr,
616 };
617
618 static struct super_operations hugetlbfs_ops = {
619         .alloc_inode    = hugetlbfs_alloc_inode,
620         .destroy_inode  = hugetlbfs_destroy_inode,
621         .statfs         = hugetlbfs_statfs,
622         .delete_inode   = hugetlbfs_delete_inode,
623         .drop_inode     = hugetlbfs_drop_inode,
624         .put_super      = hugetlbfs_put_super,
625 };
626
627 static int
628 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
629 {
630         char *opt, *value, *rest;
631
632         if (!options)
633                 return 0;
634         while ((opt = strsep(&options, ",")) != NULL) {
635                 if (!*opt)
636                         continue;
637
638                 value = strchr(opt, '=');
639                 if (!value || !*value)
640                         return -EINVAL;
641                 else
642                         *value++ = '\0';
643
644                 if (!strcmp(opt, "uid"))
645                         pconfig->uid = simple_strtoul(value, &value, 0);
646                 else if (!strcmp(opt, "gid"))
647                         pconfig->gid = simple_strtoul(value, &value, 0);
648                 else if (!strcmp(opt, "mode"))
649                         pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
650                 else if (!strcmp(opt, "size")) {
651                         unsigned long long size = memparse(value, &rest);
652                         if (*rest == '%') {
653                                 size <<= HPAGE_SHIFT;
654                                 size *= max_huge_pages;
655                                 do_div(size, 100);
656                                 rest++;
657                         }
658                         size &= HPAGE_MASK;
659                         pconfig->nr_blocks = (size >> HPAGE_SHIFT);
660                         value = rest;
661                 } else if (!strcmp(opt,"nr_inodes")) {
662                         pconfig->nr_inodes = memparse(value, &rest);
663                         value = rest;
664                 } else
665                         return -EINVAL;
666
667                 if (*value)
668                         return -EINVAL;
669         }
670         return 0;
671 }
672
673 static int
674 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
675 {
676         struct inode * inode;
677         struct dentry * root;
678         int ret;
679         struct hugetlbfs_config config;
680         struct hugetlbfs_sb_info *sbinfo;
681
682         config.nr_blocks = -1; /* No limit on size by default */
683         config.nr_inodes = -1; /* No limit on number of inodes by default */
684         config.uid = current->fsuid;
685         config.gid = current->fsgid;
686         config.mode = 0755;
687         ret = hugetlbfs_parse_options(data, &config);
688
689         if (ret)
690                 return ret;
691
692         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
693         if (!sbinfo)
694                 return -ENOMEM;
695         sb->s_fs_info = sbinfo;
696         spin_lock_init(&sbinfo->stat_lock);
697         sbinfo->max_blocks = config.nr_blocks;
698         sbinfo->free_blocks = config.nr_blocks;
699         sbinfo->max_inodes = config.nr_inodes;
700         sbinfo->free_inodes = config.nr_inodes;
701         sb->s_maxbytes = MAX_LFS_FILESIZE;
702         sb->s_blocksize = HPAGE_SIZE;
703         sb->s_blocksize_bits = HPAGE_SHIFT;
704         sb->s_magic = HUGETLBFS_MAGIC;
705         sb->s_op = &hugetlbfs_ops;
706         sb->s_time_gran = 1;
707         inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
708                                         S_IFDIR | config.mode, 0);
709         if (!inode)
710                 goto out_free;
711
712         root = d_alloc_root(inode);
713         if (!root) {
714                 iput(inode);
715                 goto out_free;
716         }
717         sb->s_root = root;
718         return 0;
719 out_free:
720         kfree(sbinfo);
721         return -ENOMEM;
722 }
723
724 int hugetlb_get_quota(struct address_space *mapping)
725 {
726         int ret = 0;
727         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
728
729         if (sbinfo->free_blocks > -1) {
730                 spin_lock(&sbinfo->stat_lock);
731                 if (sbinfo->free_blocks > 0)
732                         sbinfo->free_blocks--;
733                 else
734                         ret = -ENOMEM;
735                 spin_unlock(&sbinfo->stat_lock);
736         }
737
738         return ret;
739 }
740
741 void hugetlb_put_quota(struct address_space *mapping)
742 {
743         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
744
745         if (sbinfo->free_blocks > -1) {
746                 spin_lock(&sbinfo->stat_lock);
747                 sbinfo->free_blocks++;
748                 spin_unlock(&sbinfo->stat_lock);
749         }
750 }
751
752 static struct super_block *hugetlbfs_get_sb(struct file_system_type *fs_type,
753         int flags, const char *dev_name, void *data)
754 {
755         return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super);
756 }
757
758 static struct file_system_type hugetlbfs_fs_type = {
759         .name           = "hugetlbfs",
760         .get_sb         = hugetlbfs_get_sb,
761         .kill_sb        = kill_litter_super,
762 };
763
764 static struct vfsmount *hugetlbfs_vfsmount;
765
766 /*
767  * Return the next identifier for a shm file
768  */
769 static unsigned long hugetlbfs_counter(void)
770 {
771         static DEFINE_SPINLOCK(lock);
772         static unsigned long counter;
773         unsigned long ret;
774
775         spin_lock(&lock);
776         ret = ++counter;
777         spin_unlock(&lock);
778         return ret;
779 }
780
781 static int can_do_hugetlb_shm(void)
782 {
783         return likely(capable(CAP_IPC_LOCK) ||
784                         in_group_p(sysctl_hugetlb_shm_group) ||
785                         can_do_mlock());
786 }
787
788 struct file *hugetlb_zero_setup(size_t size)
789 {
790         int error = -ENOMEM;
791         struct file *file;
792         struct inode *inode;
793         struct dentry *dentry, *root;
794         struct qstr quick_string;
795         char buf[16];
796
797         if (!can_do_hugetlb_shm())
798                 return ERR_PTR(-EPERM);
799
800         if (!is_hugepage_mem_enough(size))
801                 return ERR_PTR(-ENOMEM);
802
803         if (!user_shm_lock(size, current->user))
804                 return ERR_PTR(-ENOMEM);
805
806         root = hugetlbfs_vfsmount->mnt_root;
807         snprintf(buf, 16, "%lu", hugetlbfs_counter());
808         quick_string.name = buf;
809         quick_string.len = strlen(quick_string.name);
810         quick_string.hash = 0;
811         dentry = d_alloc(root, &quick_string);
812         if (!dentry)
813                 goto out_shm_unlock;
814
815         error = -ENFILE;
816         file = get_empty_filp();
817         if (!file)
818                 goto out_dentry;
819
820         error = -ENOSPC;
821         inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
822                                 current->fsgid, S_IFREG | S_IRWXUGO, 0);
823         if (!inode)
824                 goto out_file;
825
826         d_instantiate(dentry, inode);
827         inode->i_size = size;
828         inode->i_nlink = 0;
829         file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
830         file->f_dentry = dentry;
831         file->f_mapping = inode->i_mapping;
832         file->f_op = &hugetlbfs_file_operations;
833         file->f_mode = FMODE_WRITE | FMODE_READ;
834         return file;
835
836 out_file:
837         put_filp(file);
838 out_dentry:
839         dput(dentry);
840 out_shm_unlock:
841         user_shm_unlock(size, current->user);
842         return ERR_PTR(error);
843 }
844
845 static int __init init_hugetlbfs_fs(void)
846 {
847         int error;
848         struct vfsmount *vfsmount;
849
850         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
851                                         sizeof(struct hugetlbfs_inode_info),
852                                         0, 0, init_once, NULL);
853         if (hugetlbfs_inode_cachep == NULL)
854                 return -ENOMEM;
855
856         error = register_filesystem(&hugetlbfs_fs_type);
857         if (error)
858                 goto out;
859
860         vfsmount = kern_mount(&hugetlbfs_fs_type);
861
862         if (!IS_ERR(vfsmount)) {
863                 hugetlbfs_vfsmount = vfsmount;
864                 return 0;
865         }
866
867         error = PTR_ERR(vfsmount);
868
869  out:
870         if (error)
871                 kmem_cache_destroy(hugetlbfs_inode_cachep);
872         return error;
873 }
874
875 static void __exit exit_hugetlbfs_fs(void)
876 {
877         kmem_cache_destroy(hugetlbfs_inode_cachep);
878         unregister_filesystem(&hugetlbfs_fs_type);
879 }
880
881 module_init(init_hugetlbfs_fs)
882 module_exit(exit_hugetlbfs_fs)
883
884 MODULE_LICENSE("GPL");