[PATCH] reduce MAX_NR_ZONES: move HIGHMEM counters into highmem.c/.h
[linux-2.6.git] / mm / shmem.c
1 /*
2  * Resizable virtual memory filesystem for Linux.
3  *
4  * Copyright (C) 2000 Linus Torvalds.
5  *               2000 Transmeta Corp.
6  *               2000-2001 Christoph Rohland
7  *               2000-2001 SAP AG
8  *               2002 Red Hat Inc.
9  * Copyright (C) 2002-2005 Hugh Dickins.
10  * Copyright (C) 2002-2005 VERITAS Software Corporation.
11  * Copyright (C) 2004 Andi Kleen, SuSE Labs
12  *
13  * Extended attribute support for tmpfs:
14  * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15  * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16  *
17  * This file is released under the GPL.
18  */
19
20 /*
21  * This virtual memory filesystem is heavily based on the ramfs. It
22  * extends ramfs by the ability to use swap and honor resource limits
23  * which makes it a completely usable filesystem.
24  */
25
26 #include <linux/module.h>
27 #include <linux/init.h>
28 #include <linux/fs.h>
29 #include <linux/mm.h>
30 #include <linux/mman.h>
31 #include <linux/file.h>
32 #include <linux/swap.h>
33 #include <linux/pagemap.h>
34 #include <linux/string.h>
35 #include <linux/slab.h>
36 #include <linux/backing-dev.h>
37 #include <linux/shmem_fs.h>
38 #include <linux/mount.h>
39 #include <linux/writeback.h>
40 #include <linux/vfs.h>
41 #include <linux/blkdev.h>
42 #include <linux/security.h>
43 #include <linux/swapops.h>
44 #include <linux/mempolicy.h>
45 #include <linux/namei.h>
46 #include <linux/ctype.h>
47 #include <linux/migrate.h>
48 #include <linux/highmem.h>
49
50 #include <asm/uaccess.h>
51 #include <asm/div64.h>
52 #include <asm/pgtable.h>
53
54 /* This magic number is used in glibc for posix shared memory */
55 #define TMPFS_MAGIC     0x01021994
56
57 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
58 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
59 #define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
60
61 #define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
62 #define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
63
64 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
65
66 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
67 #define SHMEM_PAGEIN     VM_READ
68 #define SHMEM_TRUNCATE   VM_WRITE
69
70 /* Definition to limit shmem_truncate's steps between cond_rescheds */
71 #define LATENCY_LIMIT    64
72
73 /* Pretend that each entry is of this size in directory's i_size */
74 #define BOGO_DIRENT_SIZE 20
75
76 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
77 enum sgp_type {
78         SGP_QUICK,      /* don't try more than file page cache lookup */
79         SGP_READ,       /* don't exceed i_size, don't allocate page */
80         SGP_CACHE,      /* don't exceed i_size, may allocate page */
81         SGP_WRITE,      /* may exceed i_size, may allocate page */
82 };
83
84 static int shmem_getpage(struct inode *inode, unsigned long idx,
85                          struct page **pagep, enum sgp_type sgp, int *type);
86
87 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
88 {
89         /*
90          * The above definition of ENTRIES_PER_PAGE, and the use of
91          * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
92          * might be reconsidered if it ever diverges from PAGE_SIZE.
93          */
94         return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
95 }
96
97 static inline void shmem_dir_free(struct page *page)
98 {
99         __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
100 }
101
102 static struct page **shmem_dir_map(struct page *page)
103 {
104         return (struct page **)kmap_atomic(page, KM_USER0);
105 }
106
107 static inline void shmem_dir_unmap(struct page **dir)
108 {
109         kunmap_atomic(dir, KM_USER0);
110 }
111
112 static swp_entry_t *shmem_swp_map(struct page *page)
113 {
114         return (swp_entry_t *)kmap_atomic(page, KM_USER1);
115 }
116
117 static inline void shmem_swp_balance_unmap(void)
118 {
119         /*
120          * When passing a pointer to an i_direct entry, to code which
121          * also handles indirect entries and so will shmem_swp_unmap,
122          * we must arrange for the preempt count to remain in balance.
123          * What kmap_atomic of a lowmem page does depends on config
124          * and architecture, so pretend to kmap_atomic some lowmem page.
125          */
126         (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
127 }
128
129 static inline void shmem_swp_unmap(swp_entry_t *entry)
130 {
131         kunmap_atomic(entry, KM_USER1);
132 }
133
134 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
135 {
136         return sb->s_fs_info;
137 }
138
139 /*
140  * shmem_file_setup pre-accounts the whole fixed size of a VM object,
141  * for shared memory and for shared anonymous (/dev/zero) mappings
142  * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
143  * consistent with the pre-accounting of private mappings ...
144  */
145 static inline int shmem_acct_size(unsigned long flags, loff_t size)
146 {
147         return (flags & VM_ACCOUNT)?
148                 security_vm_enough_memory(VM_ACCT(size)): 0;
149 }
150
151 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
152 {
153         if (flags & VM_ACCOUNT)
154                 vm_unacct_memory(VM_ACCT(size));
155 }
156
157 /*
158  * ... whereas tmpfs objects are accounted incrementally as
159  * pages are allocated, in order to allow huge sparse files.
160  * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
161  * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
162  */
163 static inline int shmem_acct_block(unsigned long flags)
164 {
165         return (flags & VM_ACCOUNT)?
166                 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
167 }
168
169 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
170 {
171         if (!(flags & VM_ACCOUNT))
172                 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
173 }
174
175 static struct super_operations shmem_ops;
176 static const struct address_space_operations shmem_aops;
177 static struct file_operations shmem_file_operations;
178 static struct inode_operations shmem_inode_operations;
179 static struct inode_operations shmem_dir_inode_operations;
180 static struct vm_operations_struct shmem_vm_ops;
181
182 static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
183         .ra_pages       = 0,    /* No readahead */
184         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
185         .unplug_io_fn   = default_unplug_io_fn,
186 };
187
188 static LIST_HEAD(shmem_swaplist);
189 static DEFINE_SPINLOCK(shmem_swaplist_lock);
190
191 static void shmem_free_blocks(struct inode *inode, long pages)
192 {
193         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
194         if (sbinfo->max_blocks) {
195                 spin_lock(&sbinfo->stat_lock);
196                 sbinfo->free_blocks += pages;
197                 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
198                 spin_unlock(&sbinfo->stat_lock);
199         }
200 }
201
202 /*
203  * shmem_recalc_inode - recalculate the size of an inode
204  *
205  * @inode: inode to recalc
206  *
207  * We have to calculate the free blocks since the mm can drop
208  * undirtied hole pages behind our back.
209  *
210  * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
211  * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
212  *
213  * It has to be called with the spinlock held.
214  */
215 static void shmem_recalc_inode(struct inode *inode)
216 {
217         struct shmem_inode_info *info = SHMEM_I(inode);
218         long freed;
219
220         freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
221         if (freed > 0) {
222                 info->alloced -= freed;
223                 shmem_unacct_blocks(info->flags, freed);
224                 shmem_free_blocks(inode, freed);
225         }
226 }
227
228 /*
229  * shmem_swp_entry - find the swap vector position in the info structure
230  *
231  * @info:  info structure for the inode
232  * @index: index of the page to find
233  * @page:  optional page to add to the structure. Has to be preset to
234  *         all zeros
235  *
236  * If there is no space allocated yet it will return NULL when
237  * page is NULL, else it will use the page for the needed block,
238  * setting it to NULL on return to indicate that it has been used.
239  *
240  * The swap vector is organized the following way:
241  *
242  * There are SHMEM_NR_DIRECT entries directly stored in the
243  * shmem_inode_info structure. So small files do not need an addional
244  * allocation.
245  *
246  * For pages with index > SHMEM_NR_DIRECT there is the pointer
247  * i_indirect which points to a page which holds in the first half
248  * doubly indirect blocks, in the second half triple indirect blocks:
249  *
250  * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
251  * following layout (for SHMEM_NR_DIRECT == 16):
252  *
253  * i_indirect -> dir --> 16-19
254  *            |      +-> 20-23
255  *            |
256  *            +-->dir2 --> 24-27
257  *            |        +-> 28-31
258  *            |        +-> 32-35
259  *            |        +-> 36-39
260  *            |
261  *            +-->dir3 --> 40-43
262  *                     +-> 44-47
263  *                     +-> 48-51
264  *                     +-> 52-55
265  */
266 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
267 {
268         unsigned long offset;
269         struct page **dir;
270         struct page *subdir;
271
272         if (index < SHMEM_NR_DIRECT) {
273                 shmem_swp_balance_unmap();
274                 return info->i_direct+index;
275         }
276         if (!info->i_indirect) {
277                 if (page) {
278                         info->i_indirect = *page;
279                         *page = NULL;
280                 }
281                 return NULL;                    /* need another page */
282         }
283
284         index -= SHMEM_NR_DIRECT;
285         offset = index % ENTRIES_PER_PAGE;
286         index /= ENTRIES_PER_PAGE;
287         dir = shmem_dir_map(info->i_indirect);
288
289         if (index >= ENTRIES_PER_PAGE/2) {
290                 index -= ENTRIES_PER_PAGE/2;
291                 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
292                 index %= ENTRIES_PER_PAGE;
293                 subdir = *dir;
294                 if (!subdir) {
295                         if (page) {
296                                 *dir = *page;
297                                 *page = NULL;
298                         }
299                         shmem_dir_unmap(dir);
300                         return NULL;            /* need another page */
301                 }
302                 shmem_dir_unmap(dir);
303                 dir = shmem_dir_map(subdir);
304         }
305
306         dir += index;
307         subdir = *dir;
308         if (!subdir) {
309                 if (!page || !(subdir = *page)) {
310                         shmem_dir_unmap(dir);
311                         return NULL;            /* need a page */
312                 }
313                 *dir = subdir;
314                 *page = NULL;
315         }
316         shmem_dir_unmap(dir);
317         return shmem_swp_map(subdir) + offset;
318 }
319
320 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
321 {
322         long incdec = value? 1: -1;
323
324         entry->val = value;
325         info->swapped += incdec;
326         if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
327                 struct page *page = kmap_atomic_to_page(entry);
328                 set_page_private(page, page_private(page) + incdec);
329         }
330 }
331
332 /*
333  * shmem_swp_alloc - get the position of the swap entry for the page.
334  *                   If it does not exist allocate the entry.
335  *
336  * @info:       info structure for the inode
337  * @index:      index of the page to find
338  * @sgp:        check and recheck i_size? skip allocation?
339  */
340 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
341 {
342         struct inode *inode = &info->vfs_inode;
343         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
344         struct page *page = NULL;
345         swp_entry_t *entry;
346
347         if (sgp != SGP_WRITE &&
348             ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
349                 return ERR_PTR(-EINVAL);
350
351         while (!(entry = shmem_swp_entry(info, index, &page))) {
352                 if (sgp == SGP_READ)
353                         return shmem_swp_map(ZERO_PAGE(0));
354                 /*
355                  * Test free_blocks against 1 not 0, since we have 1 data
356                  * page (and perhaps indirect index pages) yet to allocate:
357                  * a waste to allocate index if we cannot allocate data.
358                  */
359                 if (sbinfo->max_blocks) {
360                         spin_lock(&sbinfo->stat_lock);
361                         if (sbinfo->free_blocks <= 1) {
362                                 spin_unlock(&sbinfo->stat_lock);
363                                 return ERR_PTR(-ENOSPC);
364                         }
365                         sbinfo->free_blocks--;
366                         inode->i_blocks += BLOCKS_PER_PAGE;
367                         spin_unlock(&sbinfo->stat_lock);
368                 }
369
370                 spin_unlock(&info->lock);
371                 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
372                 if (page)
373                         set_page_private(page, 0);
374                 spin_lock(&info->lock);
375
376                 if (!page) {
377                         shmem_free_blocks(inode, 1);
378                         return ERR_PTR(-ENOMEM);
379                 }
380                 if (sgp != SGP_WRITE &&
381                     ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
382                         entry = ERR_PTR(-EINVAL);
383                         break;
384                 }
385                 if (info->next_index <= index)
386                         info->next_index = index + 1;
387         }
388         if (page) {
389                 /* another task gave its page, or truncated the file */
390                 shmem_free_blocks(inode, 1);
391                 shmem_dir_free(page);
392         }
393         if (info->next_index <= index && !IS_ERR(entry))
394                 info->next_index = index + 1;
395         return entry;
396 }
397
398 /*
399  * shmem_free_swp - free some swap entries in a directory
400  *
401  * @dir:   pointer to the directory
402  * @edir:  pointer after last entry of the directory
403  */
404 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
405 {
406         swp_entry_t *ptr;
407         int freed = 0;
408
409         for (ptr = dir; ptr < edir; ptr++) {
410                 if (ptr->val) {
411                         free_swap_and_cache(*ptr);
412                         *ptr = (swp_entry_t){0};
413                         freed++;
414                 }
415         }
416         return freed;
417 }
418
419 static int shmem_map_and_free_swp(struct page *subdir,
420                 int offset, int limit, struct page ***dir)
421 {
422         swp_entry_t *ptr;
423         int freed = 0;
424
425         ptr = shmem_swp_map(subdir);
426         for (; offset < limit; offset += LATENCY_LIMIT) {
427                 int size = limit - offset;
428                 if (size > LATENCY_LIMIT)
429                         size = LATENCY_LIMIT;
430                 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
431                 if (need_resched()) {
432                         shmem_swp_unmap(ptr);
433                         if (*dir) {
434                                 shmem_dir_unmap(*dir);
435                                 *dir = NULL;
436                         }
437                         cond_resched();
438                         ptr = shmem_swp_map(subdir);
439                 }
440         }
441         shmem_swp_unmap(ptr);
442         return freed;
443 }
444
445 static void shmem_free_pages(struct list_head *next)
446 {
447         struct page *page;
448         int freed = 0;
449
450         do {
451                 page = container_of(next, struct page, lru);
452                 next = next->next;
453                 shmem_dir_free(page);
454                 freed++;
455                 if (freed >= LATENCY_LIMIT) {
456                         cond_resched();
457                         freed = 0;
458                 }
459         } while (next);
460 }
461
462 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
463 {
464         struct shmem_inode_info *info = SHMEM_I(inode);
465         unsigned long idx;
466         unsigned long size;
467         unsigned long limit;
468         unsigned long stage;
469         unsigned long diroff;
470         struct page **dir;
471         struct page *topdir;
472         struct page *middir;
473         struct page *subdir;
474         swp_entry_t *ptr;
475         LIST_HEAD(pages_to_free);
476         long nr_pages_to_free = 0;
477         long nr_swaps_freed = 0;
478         int offset;
479         int freed;
480         int punch_hole = 0;
481
482         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
483         idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
484         if (idx >= info->next_index)
485                 return;
486
487         spin_lock(&info->lock);
488         info->flags |= SHMEM_TRUNCATE;
489         if (likely(end == (loff_t) -1)) {
490                 limit = info->next_index;
491                 info->next_index = idx;
492         } else {
493                 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
494                 if (limit > info->next_index)
495                         limit = info->next_index;
496                 punch_hole = 1;
497         }
498
499         topdir = info->i_indirect;
500         if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
501                 info->i_indirect = NULL;
502                 nr_pages_to_free++;
503                 list_add(&topdir->lru, &pages_to_free);
504         }
505         spin_unlock(&info->lock);
506
507         if (info->swapped && idx < SHMEM_NR_DIRECT) {
508                 ptr = info->i_direct;
509                 size = limit;
510                 if (size > SHMEM_NR_DIRECT)
511                         size = SHMEM_NR_DIRECT;
512                 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
513         }
514         if (!topdir)
515                 goto done2;
516
517         BUG_ON(limit <= SHMEM_NR_DIRECT);
518         limit -= SHMEM_NR_DIRECT;
519         idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
520         offset = idx % ENTRIES_PER_PAGE;
521         idx -= offset;
522
523         dir = shmem_dir_map(topdir);
524         stage = ENTRIES_PER_PAGEPAGE/2;
525         if (idx < ENTRIES_PER_PAGEPAGE/2) {
526                 middir = topdir;
527                 diroff = idx/ENTRIES_PER_PAGE;
528         } else {
529                 dir += ENTRIES_PER_PAGE/2;
530                 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
531                 while (stage <= idx)
532                         stage += ENTRIES_PER_PAGEPAGE;
533                 middir = *dir;
534                 if (*dir) {
535                         diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
536                                 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
537                         if (!diroff && !offset) {
538                                 *dir = NULL;
539                                 nr_pages_to_free++;
540                                 list_add(&middir->lru, &pages_to_free);
541                         }
542                         shmem_dir_unmap(dir);
543                         dir = shmem_dir_map(middir);
544                 } else {
545                         diroff = 0;
546                         offset = 0;
547                         idx = stage;
548                 }
549         }
550
551         for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
552                 if (unlikely(idx == stage)) {
553                         shmem_dir_unmap(dir);
554                         dir = shmem_dir_map(topdir) +
555                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
556                         while (!*dir) {
557                                 dir++;
558                                 idx += ENTRIES_PER_PAGEPAGE;
559                                 if (idx >= limit)
560                                         goto done1;
561                         }
562                         stage = idx + ENTRIES_PER_PAGEPAGE;
563                         middir = *dir;
564                         *dir = NULL;
565                         nr_pages_to_free++;
566                         list_add(&middir->lru, &pages_to_free);
567                         shmem_dir_unmap(dir);
568                         cond_resched();
569                         dir = shmem_dir_map(middir);
570                         diroff = 0;
571                 }
572                 subdir = dir[diroff];
573                 if (subdir && page_private(subdir)) {
574                         size = limit - idx;
575                         if (size > ENTRIES_PER_PAGE)
576                                 size = ENTRIES_PER_PAGE;
577                         freed = shmem_map_and_free_swp(subdir,
578                                                 offset, size, &dir);
579                         if (!dir)
580                                 dir = shmem_dir_map(middir);
581                         nr_swaps_freed += freed;
582                         if (offset)
583                                 spin_lock(&info->lock);
584                         set_page_private(subdir, page_private(subdir) - freed);
585                         if (offset)
586                                 spin_unlock(&info->lock);
587                         if (!punch_hole)
588                                 BUG_ON(page_private(subdir) > offset);
589                 }
590                 if (offset)
591                         offset = 0;
592                 else if (subdir && !page_private(subdir)) {
593                         dir[diroff] = NULL;
594                         nr_pages_to_free++;
595                         list_add(&subdir->lru, &pages_to_free);
596                 }
597         }
598 done1:
599         shmem_dir_unmap(dir);
600 done2:
601         if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
602                 /*
603                  * Call truncate_inode_pages again: racing shmem_unuse_inode
604                  * may have swizzled a page in from swap since vmtruncate or
605                  * generic_delete_inode did it, before we lowered next_index.
606                  * Also, though shmem_getpage checks i_size before adding to
607                  * cache, no recheck after: so fix the narrow window there too.
608                  */
609                 truncate_inode_pages_range(inode->i_mapping, start, end);
610         }
611
612         spin_lock(&info->lock);
613         info->flags &= ~SHMEM_TRUNCATE;
614         info->swapped -= nr_swaps_freed;
615         if (nr_pages_to_free)
616                 shmem_free_blocks(inode, nr_pages_to_free);
617         shmem_recalc_inode(inode);
618         spin_unlock(&info->lock);
619
620         /*
621          * Empty swap vector directory pages to be freed?
622          */
623         if (!list_empty(&pages_to_free)) {
624                 pages_to_free.prev->next = NULL;
625                 shmem_free_pages(pages_to_free.next);
626         }
627 }
628
629 static void shmem_truncate(struct inode *inode)
630 {
631         shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
632 }
633
634 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
635 {
636         struct inode *inode = dentry->d_inode;
637         struct page *page = NULL;
638         int error;
639
640         if (attr->ia_valid & ATTR_SIZE) {
641                 if (attr->ia_size < inode->i_size) {
642                         /*
643                          * If truncating down to a partial page, then
644                          * if that page is already allocated, hold it
645                          * in memory until the truncation is over, so
646                          * truncate_partial_page cannnot miss it were
647                          * it assigned to swap.
648                          */
649                         if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
650                                 (void) shmem_getpage(inode,
651                                         attr->ia_size>>PAGE_CACHE_SHIFT,
652                                                 &page, SGP_READ, NULL);
653                         }
654                         /*
655                          * Reset SHMEM_PAGEIN flag so that shmem_truncate can
656                          * detect if any pages might have been added to cache
657                          * after truncate_inode_pages.  But we needn't bother
658                          * if it's being fully truncated to zero-length: the
659                          * nrpages check is efficient enough in that case.
660                          */
661                         if (attr->ia_size) {
662                                 struct shmem_inode_info *info = SHMEM_I(inode);
663                                 spin_lock(&info->lock);
664                                 info->flags &= ~SHMEM_PAGEIN;
665                                 spin_unlock(&info->lock);
666                         }
667                 }
668         }
669
670         error = inode_change_ok(inode, attr);
671         if (!error)
672                 error = inode_setattr(inode, attr);
673         if (page)
674                 page_cache_release(page);
675         return error;
676 }
677
678 static void shmem_delete_inode(struct inode *inode)
679 {
680         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
681         struct shmem_inode_info *info = SHMEM_I(inode);
682
683         if (inode->i_op->truncate == shmem_truncate) {
684                 truncate_inode_pages(inode->i_mapping, 0);
685                 shmem_unacct_size(info->flags, inode->i_size);
686                 inode->i_size = 0;
687                 shmem_truncate(inode);
688                 if (!list_empty(&info->swaplist)) {
689                         spin_lock(&shmem_swaplist_lock);
690                         list_del_init(&info->swaplist);
691                         spin_unlock(&shmem_swaplist_lock);
692                 }
693         }
694         BUG_ON(inode->i_blocks);
695         if (sbinfo->max_inodes) {
696                 spin_lock(&sbinfo->stat_lock);
697                 sbinfo->free_inodes++;
698                 spin_unlock(&sbinfo->stat_lock);
699         }
700         clear_inode(inode);
701 }
702
703 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
704 {
705         swp_entry_t *ptr;
706
707         for (ptr = dir; ptr < edir; ptr++) {
708                 if (ptr->val == entry.val)
709                         return ptr - dir;
710         }
711         return -1;
712 }
713
714 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
715 {
716         struct inode *inode;
717         unsigned long idx;
718         unsigned long size;
719         unsigned long limit;
720         unsigned long stage;
721         struct page **dir;
722         struct page *subdir;
723         swp_entry_t *ptr;
724         int offset;
725
726         idx = 0;
727         ptr = info->i_direct;
728         spin_lock(&info->lock);
729         limit = info->next_index;
730         size = limit;
731         if (size > SHMEM_NR_DIRECT)
732                 size = SHMEM_NR_DIRECT;
733         offset = shmem_find_swp(entry, ptr, ptr+size);
734         if (offset >= 0) {
735                 shmem_swp_balance_unmap();
736                 goto found;
737         }
738         if (!info->i_indirect)
739                 goto lost2;
740
741         dir = shmem_dir_map(info->i_indirect);
742         stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
743
744         for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
745                 if (unlikely(idx == stage)) {
746                         shmem_dir_unmap(dir-1);
747                         dir = shmem_dir_map(info->i_indirect) +
748                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
749                         while (!*dir) {
750                                 dir++;
751                                 idx += ENTRIES_PER_PAGEPAGE;
752                                 if (idx >= limit)
753                                         goto lost1;
754                         }
755                         stage = idx + ENTRIES_PER_PAGEPAGE;
756                         subdir = *dir;
757                         shmem_dir_unmap(dir);
758                         dir = shmem_dir_map(subdir);
759                 }
760                 subdir = *dir;
761                 if (subdir && page_private(subdir)) {
762                         ptr = shmem_swp_map(subdir);
763                         size = limit - idx;
764                         if (size > ENTRIES_PER_PAGE)
765                                 size = ENTRIES_PER_PAGE;
766                         offset = shmem_find_swp(entry, ptr, ptr+size);
767                         if (offset >= 0) {
768                                 shmem_dir_unmap(dir);
769                                 goto found;
770                         }
771                         shmem_swp_unmap(ptr);
772                 }
773         }
774 lost1:
775         shmem_dir_unmap(dir-1);
776 lost2:
777         spin_unlock(&info->lock);
778         return 0;
779 found:
780         idx += offset;
781         inode = &info->vfs_inode;
782         if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
783                 info->flags |= SHMEM_PAGEIN;
784                 shmem_swp_set(info, ptr + offset, 0);
785         }
786         shmem_swp_unmap(ptr);
787         spin_unlock(&info->lock);
788         /*
789          * Decrement swap count even when the entry is left behind:
790          * try_to_unuse will skip over mms, then reincrement count.
791          */
792         swap_free(entry);
793         return 1;
794 }
795
796 /*
797  * shmem_unuse() search for an eventually swapped out shmem page.
798  */
799 int shmem_unuse(swp_entry_t entry, struct page *page)
800 {
801         struct list_head *p, *next;
802         struct shmem_inode_info *info;
803         int found = 0;
804
805         spin_lock(&shmem_swaplist_lock);
806         list_for_each_safe(p, next, &shmem_swaplist) {
807                 info = list_entry(p, struct shmem_inode_info, swaplist);
808                 if (!info->swapped)
809                         list_del_init(&info->swaplist);
810                 else if (shmem_unuse_inode(info, entry, page)) {
811                         /* move head to start search for next from here */
812                         list_move_tail(&shmem_swaplist, &info->swaplist);
813                         found = 1;
814                         break;
815                 }
816         }
817         spin_unlock(&shmem_swaplist_lock);
818         return found;
819 }
820
821 /*
822  * Move the page from the page cache to the swap cache.
823  */
824 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
825 {
826         struct shmem_inode_info *info;
827         swp_entry_t *entry, swap;
828         struct address_space *mapping;
829         unsigned long index;
830         struct inode *inode;
831
832         BUG_ON(!PageLocked(page));
833         BUG_ON(page_mapped(page));
834
835         mapping = page->mapping;
836         index = page->index;
837         inode = mapping->host;
838         info = SHMEM_I(inode);
839         if (info->flags & VM_LOCKED)
840                 goto redirty;
841         swap = get_swap_page();
842         if (!swap.val)
843                 goto redirty;
844
845         spin_lock(&info->lock);
846         shmem_recalc_inode(inode);
847         if (index >= info->next_index) {
848                 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
849                 goto unlock;
850         }
851         entry = shmem_swp_entry(info, index, NULL);
852         BUG_ON(!entry);
853         BUG_ON(entry->val);
854
855         if (move_to_swap_cache(page, swap) == 0) {
856                 shmem_swp_set(info, entry, swap.val);
857                 shmem_swp_unmap(entry);
858                 spin_unlock(&info->lock);
859                 if (list_empty(&info->swaplist)) {
860                         spin_lock(&shmem_swaplist_lock);
861                         /* move instead of add in case we're racing */
862                         list_move_tail(&info->swaplist, &shmem_swaplist);
863                         spin_unlock(&shmem_swaplist_lock);
864                 }
865                 unlock_page(page);
866                 return 0;
867         }
868
869         shmem_swp_unmap(entry);
870 unlock:
871         spin_unlock(&info->lock);
872         swap_free(swap);
873 redirty:
874         set_page_dirty(page);
875         return AOP_WRITEPAGE_ACTIVATE;  /* Return with the page locked */
876 }
877
878 #ifdef CONFIG_NUMA
879 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
880 {
881         char *nodelist = strchr(value, ':');
882         int err = 1;
883
884         if (nodelist) {
885                 /* NUL-terminate policy string */
886                 *nodelist++ = '\0';
887                 if (nodelist_parse(nodelist, *policy_nodes))
888                         goto out;
889         }
890         if (!strcmp(value, "default")) {
891                 *policy = MPOL_DEFAULT;
892                 /* Don't allow a nodelist */
893                 if (!nodelist)
894                         err = 0;
895         } else if (!strcmp(value, "prefer")) {
896                 *policy = MPOL_PREFERRED;
897                 /* Insist on a nodelist of one node only */
898                 if (nodelist) {
899                         char *rest = nodelist;
900                         while (isdigit(*rest))
901                                 rest++;
902                         if (!*rest)
903                                 err = 0;
904                 }
905         } else if (!strcmp(value, "bind")) {
906                 *policy = MPOL_BIND;
907                 /* Insist on a nodelist */
908                 if (nodelist)
909                         err = 0;
910         } else if (!strcmp(value, "interleave")) {
911                 *policy = MPOL_INTERLEAVE;
912                 /* Default to nodes online if no nodelist */
913                 if (!nodelist)
914                         *policy_nodes = node_online_map;
915                 err = 0;
916         }
917 out:
918         /* Restore string for error message */
919         if (nodelist)
920                 *--nodelist = ':';
921         return err;
922 }
923
924 static struct page *shmem_swapin_async(struct shared_policy *p,
925                                        swp_entry_t entry, unsigned long idx)
926 {
927         struct page *page;
928         struct vm_area_struct pvma;
929
930         /* Create a pseudo vma that just contains the policy */
931         memset(&pvma, 0, sizeof(struct vm_area_struct));
932         pvma.vm_end = PAGE_SIZE;
933         pvma.vm_pgoff = idx;
934         pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
935         page = read_swap_cache_async(entry, &pvma, 0);
936         mpol_free(pvma.vm_policy);
937         return page;
938 }
939
940 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
941                           unsigned long idx)
942 {
943         struct shared_policy *p = &info->policy;
944         int i, num;
945         struct page *page;
946         unsigned long offset;
947
948         num = valid_swaphandles(entry, &offset);
949         for (i = 0; i < num; offset++, i++) {
950                 page = shmem_swapin_async(p,
951                                 swp_entry(swp_type(entry), offset), idx);
952                 if (!page)
953                         break;
954                 page_cache_release(page);
955         }
956         lru_add_drain();        /* Push any new pages onto the LRU now */
957         return shmem_swapin_async(p, entry, idx);
958 }
959
960 static struct page *
961 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
962                  unsigned long idx)
963 {
964         struct vm_area_struct pvma;
965         struct page *page;
966
967         memset(&pvma, 0, sizeof(struct vm_area_struct));
968         pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
969         pvma.vm_pgoff = idx;
970         pvma.vm_end = PAGE_SIZE;
971         page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
972         mpol_free(pvma.vm_policy);
973         return page;
974 }
975 #else
976 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
977 {
978         return 1;
979 }
980
981 static inline struct page *
982 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
983 {
984         swapin_readahead(entry, 0, NULL);
985         return read_swap_cache_async(entry, NULL, 0);
986 }
987
988 static inline struct page *
989 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
990 {
991         return alloc_page(gfp | __GFP_ZERO);
992 }
993 #endif
994
995 /*
996  * shmem_getpage - either get the page from swap or allocate a new one
997  *
998  * If we allocate a new one we do not mark it dirty. That's up to the
999  * vm. If we swap it in we mark it dirty since we also free the swap
1000  * entry since a page cannot live in both the swap and page cache
1001  */
1002 static int shmem_getpage(struct inode *inode, unsigned long idx,
1003                         struct page **pagep, enum sgp_type sgp, int *type)
1004 {
1005         struct address_space *mapping = inode->i_mapping;
1006         struct shmem_inode_info *info = SHMEM_I(inode);
1007         struct shmem_sb_info *sbinfo;
1008         struct page *filepage = *pagep;
1009         struct page *swappage;
1010         swp_entry_t *entry;
1011         swp_entry_t swap;
1012         int error;
1013
1014         if (idx >= SHMEM_MAX_INDEX)
1015                 return -EFBIG;
1016         /*
1017          * Normally, filepage is NULL on entry, and either found
1018          * uptodate immediately, or allocated and zeroed, or read
1019          * in under swappage, which is then assigned to filepage.
1020          * But shmem_prepare_write passes in a locked filepage,
1021          * which may be found not uptodate by other callers too,
1022          * and may need to be copied from the swappage read in.
1023          */
1024 repeat:
1025         if (!filepage)
1026                 filepage = find_lock_page(mapping, idx);
1027         if (filepage && PageUptodate(filepage))
1028                 goto done;
1029         error = 0;
1030         if (sgp == SGP_QUICK)
1031                 goto failed;
1032
1033         spin_lock(&info->lock);
1034         shmem_recalc_inode(inode);
1035         entry = shmem_swp_alloc(info, idx, sgp);
1036         if (IS_ERR(entry)) {
1037                 spin_unlock(&info->lock);
1038                 error = PTR_ERR(entry);
1039                 goto failed;
1040         }
1041         swap = *entry;
1042
1043         if (swap.val) {
1044                 /* Look it up and read it in.. */
1045                 swappage = lookup_swap_cache(swap);
1046                 if (!swappage) {
1047                         shmem_swp_unmap(entry);
1048                         /* here we actually do the io */
1049                         if (type && *type == VM_FAULT_MINOR) {
1050                                 __count_vm_event(PGMAJFAULT);
1051                                 *type = VM_FAULT_MAJOR;
1052                         }
1053                         spin_unlock(&info->lock);
1054                         swappage = shmem_swapin(info, swap, idx);
1055                         if (!swappage) {
1056                                 spin_lock(&info->lock);
1057                                 entry = shmem_swp_alloc(info, idx, sgp);
1058                                 if (IS_ERR(entry))
1059                                         error = PTR_ERR(entry);
1060                                 else {
1061                                         if (entry->val == swap.val)
1062                                                 error = -ENOMEM;
1063                                         shmem_swp_unmap(entry);
1064                                 }
1065                                 spin_unlock(&info->lock);
1066                                 if (error)
1067                                         goto failed;
1068                                 goto repeat;
1069                         }
1070                         wait_on_page_locked(swappage);
1071                         page_cache_release(swappage);
1072                         goto repeat;
1073                 }
1074
1075                 /* We have to do this with page locked to prevent races */
1076                 if (TestSetPageLocked(swappage)) {
1077                         shmem_swp_unmap(entry);
1078                         spin_unlock(&info->lock);
1079                         wait_on_page_locked(swappage);
1080                         page_cache_release(swappage);
1081                         goto repeat;
1082                 }
1083                 if (PageWriteback(swappage)) {
1084                         shmem_swp_unmap(entry);
1085                         spin_unlock(&info->lock);
1086                         wait_on_page_writeback(swappage);
1087                         unlock_page(swappage);
1088                         page_cache_release(swappage);
1089                         goto repeat;
1090                 }
1091                 if (!PageUptodate(swappage)) {
1092                         shmem_swp_unmap(entry);
1093                         spin_unlock(&info->lock);
1094                         unlock_page(swappage);
1095                         page_cache_release(swappage);
1096                         error = -EIO;
1097                         goto failed;
1098                 }
1099
1100                 if (filepage) {
1101                         shmem_swp_set(info, entry, 0);
1102                         shmem_swp_unmap(entry);
1103                         delete_from_swap_cache(swappage);
1104                         spin_unlock(&info->lock);
1105                         copy_highpage(filepage, swappage);
1106                         unlock_page(swappage);
1107                         page_cache_release(swappage);
1108                         flush_dcache_page(filepage);
1109                         SetPageUptodate(filepage);
1110                         set_page_dirty(filepage);
1111                         swap_free(swap);
1112                 } else if (!(error = move_from_swap_cache(
1113                                 swappage, idx, mapping))) {
1114                         info->flags |= SHMEM_PAGEIN;
1115                         shmem_swp_set(info, entry, 0);
1116                         shmem_swp_unmap(entry);
1117                         spin_unlock(&info->lock);
1118                         filepage = swappage;
1119                         swap_free(swap);
1120                 } else {
1121                         shmem_swp_unmap(entry);
1122                         spin_unlock(&info->lock);
1123                         unlock_page(swappage);
1124                         page_cache_release(swappage);
1125                         if (error == -ENOMEM) {
1126                                 /* let kswapd refresh zone for GFP_ATOMICs */
1127                                 blk_congestion_wait(WRITE, HZ/50);
1128                         }
1129                         goto repeat;
1130                 }
1131         } else if (sgp == SGP_READ && !filepage) {
1132                 shmem_swp_unmap(entry);
1133                 filepage = find_get_page(mapping, idx);
1134                 if (filepage &&
1135                     (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1136                         spin_unlock(&info->lock);
1137                         wait_on_page_locked(filepage);
1138                         page_cache_release(filepage);
1139                         filepage = NULL;
1140                         goto repeat;
1141                 }
1142                 spin_unlock(&info->lock);
1143         } else {
1144                 shmem_swp_unmap(entry);
1145                 sbinfo = SHMEM_SB(inode->i_sb);
1146                 if (sbinfo->max_blocks) {
1147                         spin_lock(&sbinfo->stat_lock);
1148                         if (sbinfo->free_blocks == 0 ||
1149                             shmem_acct_block(info->flags)) {
1150                                 spin_unlock(&sbinfo->stat_lock);
1151                                 spin_unlock(&info->lock);
1152                                 error = -ENOSPC;
1153                                 goto failed;
1154                         }
1155                         sbinfo->free_blocks--;
1156                         inode->i_blocks += BLOCKS_PER_PAGE;
1157                         spin_unlock(&sbinfo->stat_lock);
1158                 } else if (shmem_acct_block(info->flags)) {
1159                         spin_unlock(&info->lock);
1160                         error = -ENOSPC;
1161                         goto failed;
1162                 }
1163
1164                 if (!filepage) {
1165                         spin_unlock(&info->lock);
1166                         filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1167                                                     info,
1168                                                     idx);
1169                         if (!filepage) {
1170                                 shmem_unacct_blocks(info->flags, 1);
1171                                 shmem_free_blocks(inode, 1);
1172                                 error = -ENOMEM;
1173                                 goto failed;
1174                         }
1175
1176                         spin_lock(&info->lock);
1177                         entry = shmem_swp_alloc(info, idx, sgp);
1178                         if (IS_ERR(entry))
1179                                 error = PTR_ERR(entry);
1180                         else {
1181                                 swap = *entry;
1182                                 shmem_swp_unmap(entry);
1183                         }
1184                         if (error || swap.val || 0 != add_to_page_cache_lru(
1185                                         filepage, mapping, idx, GFP_ATOMIC)) {
1186                                 spin_unlock(&info->lock);
1187                                 page_cache_release(filepage);
1188                                 shmem_unacct_blocks(info->flags, 1);
1189                                 shmem_free_blocks(inode, 1);
1190                                 filepage = NULL;
1191                                 if (error)
1192                                         goto failed;
1193                                 goto repeat;
1194                         }
1195                         info->flags |= SHMEM_PAGEIN;
1196                 }
1197
1198                 info->alloced++;
1199                 spin_unlock(&info->lock);
1200                 flush_dcache_page(filepage);
1201                 SetPageUptodate(filepage);
1202         }
1203 done:
1204         if (*pagep != filepage) {
1205                 unlock_page(filepage);
1206                 *pagep = filepage;
1207         }
1208         return 0;
1209
1210 failed:
1211         if (*pagep != filepage) {
1212                 unlock_page(filepage);
1213                 page_cache_release(filepage);
1214         }
1215         return error;
1216 }
1217
1218 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1219 {
1220         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1221         struct page *page = NULL;
1222         unsigned long idx;
1223         int error;
1224
1225         idx = (address - vma->vm_start) >> PAGE_SHIFT;
1226         idx += vma->vm_pgoff;
1227         idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1228         if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1229                 return NOPAGE_SIGBUS;
1230
1231         error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1232         if (error)
1233                 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1234
1235         mark_page_accessed(page);
1236         return page;
1237 }
1238
1239 static int shmem_populate(struct vm_area_struct *vma,
1240         unsigned long addr, unsigned long len,
1241         pgprot_t prot, unsigned long pgoff, int nonblock)
1242 {
1243         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1244         struct mm_struct *mm = vma->vm_mm;
1245         enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1246         unsigned long size;
1247
1248         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1249         if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1250                 return -EINVAL;
1251
1252         while ((long) len > 0) {
1253                 struct page *page = NULL;
1254                 int err;
1255                 /*
1256                  * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1257                  */
1258                 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1259                 if (err)
1260                         return err;
1261                 /* Page may still be null, but only if nonblock was set. */
1262                 if (page) {
1263                         mark_page_accessed(page);
1264                         err = install_page(mm, vma, addr, page, prot);
1265                         if (err) {
1266                                 page_cache_release(page);
1267                                 return err;
1268                         }
1269                 } else if (vma->vm_flags & VM_NONLINEAR) {
1270                         /* No page was found just because we can't read it in
1271                          * now (being here implies nonblock != 0), but the page
1272                          * may exist, so set the PTE to fault it in later. */
1273                         err = install_file_pte(mm, vma, addr, pgoff, prot);
1274                         if (err)
1275                                 return err;
1276                 }
1277
1278                 len -= PAGE_SIZE;
1279                 addr += PAGE_SIZE;
1280                 pgoff++;
1281         }
1282         return 0;
1283 }
1284
1285 #ifdef CONFIG_NUMA
1286 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1287 {
1288         struct inode *i = vma->vm_file->f_dentry->d_inode;
1289         return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1290 }
1291
1292 struct mempolicy *
1293 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1294 {
1295         struct inode *i = vma->vm_file->f_dentry->d_inode;
1296         unsigned long idx;
1297
1298         idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1299         return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1300 }
1301 #endif
1302
1303 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1304 {
1305         struct inode *inode = file->f_dentry->d_inode;
1306         struct shmem_inode_info *info = SHMEM_I(inode);
1307         int retval = -ENOMEM;
1308
1309         spin_lock(&info->lock);
1310         if (lock && !(info->flags & VM_LOCKED)) {
1311                 if (!user_shm_lock(inode->i_size, user))
1312                         goto out_nomem;
1313                 info->flags |= VM_LOCKED;
1314         }
1315         if (!lock && (info->flags & VM_LOCKED) && user) {
1316                 user_shm_unlock(inode->i_size, user);
1317                 info->flags &= ~VM_LOCKED;
1318         }
1319         retval = 0;
1320 out_nomem:
1321         spin_unlock(&info->lock);
1322         return retval;
1323 }
1324
1325 int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1326 {
1327         file_accessed(file);
1328         vma->vm_ops = &shmem_vm_ops;
1329         return 0;
1330 }
1331
1332 static struct inode *
1333 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1334 {
1335         struct inode *inode;
1336         struct shmem_inode_info *info;
1337         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1338
1339         if (sbinfo->max_inodes) {
1340                 spin_lock(&sbinfo->stat_lock);
1341                 if (!sbinfo->free_inodes) {
1342                         spin_unlock(&sbinfo->stat_lock);
1343                         return NULL;
1344                 }
1345                 sbinfo->free_inodes--;
1346                 spin_unlock(&sbinfo->stat_lock);
1347         }
1348
1349         inode = new_inode(sb);
1350         if (inode) {
1351                 inode->i_mode = mode;
1352                 inode->i_uid = current->fsuid;
1353                 inode->i_gid = current->fsgid;
1354                 inode->i_blksize = PAGE_CACHE_SIZE;
1355                 inode->i_blocks = 0;
1356                 inode->i_mapping->a_ops = &shmem_aops;
1357                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1358                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1359                 info = SHMEM_I(inode);
1360                 memset(info, 0, (char *)inode - (char *)info);
1361                 spin_lock_init(&info->lock);
1362                 INIT_LIST_HEAD(&info->swaplist);
1363
1364                 switch (mode & S_IFMT) {
1365                 default:
1366                         init_special_inode(inode, mode, dev);
1367                         break;
1368                 case S_IFREG:
1369                         inode->i_op = &shmem_inode_operations;
1370                         inode->i_fop = &shmem_file_operations;
1371                         mpol_shared_policy_init(&info->policy, sbinfo->policy,
1372                                                         &sbinfo->policy_nodes);
1373                         break;
1374                 case S_IFDIR:
1375                         inode->i_nlink++;
1376                         /* Some things misbehave if size == 0 on a directory */
1377                         inode->i_size = 2 * BOGO_DIRENT_SIZE;
1378                         inode->i_op = &shmem_dir_inode_operations;
1379                         inode->i_fop = &simple_dir_operations;
1380                         break;
1381                 case S_IFLNK:
1382                         /*
1383                          * Must not load anything in the rbtree,
1384                          * mpol_free_shared_policy will not be called.
1385                          */
1386                         mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1387                                                 NULL);
1388                         break;
1389                 }
1390         } else if (sbinfo->max_inodes) {
1391                 spin_lock(&sbinfo->stat_lock);
1392                 sbinfo->free_inodes++;
1393                 spin_unlock(&sbinfo->stat_lock);
1394         }
1395         return inode;
1396 }
1397
1398 #ifdef CONFIG_TMPFS
1399 static struct inode_operations shmem_symlink_inode_operations;
1400 static struct inode_operations shmem_symlink_inline_operations;
1401
1402 /*
1403  * Normally tmpfs makes no use of shmem_prepare_write, but it
1404  * lets a tmpfs file be used read-write below the loop driver.
1405  */
1406 static int
1407 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1408 {
1409         struct inode *inode = page->mapping->host;
1410         return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1411 }
1412
1413 static ssize_t
1414 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1415 {
1416         struct inode    *inode = file->f_dentry->d_inode;
1417         loff_t          pos;
1418         unsigned long   written;
1419         ssize_t         err;
1420
1421         if ((ssize_t) count < 0)
1422                 return -EINVAL;
1423
1424         if (!access_ok(VERIFY_READ, buf, count))
1425                 return -EFAULT;
1426
1427         mutex_lock(&inode->i_mutex);
1428
1429         pos = *ppos;
1430         written = 0;
1431
1432         err = generic_write_checks(file, &pos, &count, 0);
1433         if (err || !count)
1434                 goto out;
1435
1436         err = remove_suid(file->f_dentry);
1437         if (err)
1438                 goto out;
1439
1440         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1441
1442         do {
1443                 struct page *page = NULL;
1444                 unsigned long bytes, index, offset;
1445                 char *kaddr;
1446                 int left;
1447
1448                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1449                 index = pos >> PAGE_CACHE_SHIFT;
1450                 bytes = PAGE_CACHE_SIZE - offset;
1451                 if (bytes > count)
1452                         bytes = count;
1453
1454                 /*
1455                  * We don't hold page lock across copy from user -
1456                  * what would it guard against? - so no deadlock here.
1457                  * But it still may be a good idea to prefault below.
1458                  */
1459
1460                 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1461                 if (err)
1462                         break;
1463
1464                 left = bytes;
1465                 if (PageHighMem(page)) {
1466                         volatile unsigned char dummy;
1467                         __get_user(dummy, buf);
1468                         __get_user(dummy, buf + bytes - 1);
1469
1470                         kaddr = kmap_atomic(page, KM_USER0);
1471                         left = __copy_from_user_inatomic(kaddr + offset,
1472                                                         buf, bytes);
1473                         kunmap_atomic(kaddr, KM_USER0);
1474                 }
1475                 if (left) {
1476                         kaddr = kmap(page);
1477                         left = __copy_from_user(kaddr + offset, buf, bytes);
1478                         kunmap(page);
1479                 }
1480
1481                 written += bytes;
1482                 count -= bytes;
1483                 pos += bytes;
1484                 buf += bytes;
1485                 if (pos > inode->i_size)
1486                         i_size_write(inode, pos);
1487
1488                 flush_dcache_page(page);
1489                 set_page_dirty(page);
1490                 mark_page_accessed(page);
1491                 page_cache_release(page);
1492
1493                 if (left) {
1494                         pos -= left;
1495                         written -= left;
1496                         err = -EFAULT;
1497                         break;
1498                 }
1499
1500                 /*
1501                  * Our dirty pages are not counted in nr_dirty,
1502                  * and we do not attempt to balance dirty pages.
1503                  */
1504
1505                 cond_resched();
1506         } while (count);
1507
1508         *ppos = pos;
1509         if (written)
1510                 err = written;
1511 out:
1512         mutex_unlock(&inode->i_mutex);
1513         return err;
1514 }
1515
1516 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1517 {
1518         struct inode *inode = filp->f_dentry->d_inode;
1519         struct address_space *mapping = inode->i_mapping;
1520         unsigned long index, offset;
1521
1522         index = *ppos >> PAGE_CACHE_SHIFT;
1523         offset = *ppos & ~PAGE_CACHE_MASK;
1524
1525         for (;;) {
1526                 struct page *page = NULL;
1527                 unsigned long end_index, nr, ret;
1528                 loff_t i_size = i_size_read(inode);
1529
1530                 end_index = i_size >> PAGE_CACHE_SHIFT;
1531                 if (index > end_index)
1532                         break;
1533                 if (index == end_index) {
1534                         nr = i_size & ~PAGE_CACHE_MASK;
1535                         if (nr <= offset)
1536                                 break;
1537                 }
1538
1539                 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1540                 if (desc->error) {
1541                         if (desc->error == -EINVAL)
1542                                 desc->error = 0;
1543                         break;
1544                 }
1545
1546                 /*
1547                  * We must evaluate after, since reads (unlike writes)
1548                  * are called without i_mutex protection against truncate
1549                  */
1550                 nr = PAGE_CACHE_SIZE;
1551                 i_size = i_size_read(inode);
1552                 end_index = i_size >> PAGE_CACHE_SHIFT;
1553                 if (index == end_index) {
1554                         nr = i_size & ~PAGE_CACHE_MASK;
1555                         if (nr <= offset) {
1556                                 if (page)
1557                                         page_cache_release(page);
1558                                 break;
1559                         }
1560                 }
1561                 nr -= offset;
1562
1563                 if (page) {
1564                         /*
1565                          * If users can be writing to this page using arbitrary
1566                          * virtual addresses, take care about potential aliasing
1567                          * before reading the page on the kernel side.
1568                          */
1569                         if (mapping_writably_mapped(mapping))
1570                                 flush_dcache_page(page);
1571                         /*
1572                          * Mark the page accessed if we read the beginning.
1573                          */
1574                         if (!offset)
1575                                 mark_page_accessed(page);
1576                 } else {
1577                         page = ZERO_PAGE(0);
1578                         page_cache_get(page);
1579                 }
1580
1581                 /*
1582                  * Ok, we have the page, and it's up-to-date, so
1583                  * now we can copy it to user space...
1584                  *
1585                  * The actor routine returns how many bytes were actually used..
1586                  * NOTE! This may not be the same as how much of a user buffer
1587                  * we filled up (we may be padding etc), so we can only update
1588                  * "pos" here (the actor routine has to update the user buffer
1589                  * pointers and the remaining count).
1590                  */
1591                 ret = actor(desc, page, offset, nr);
1592                 offset += ret;
1593                 index += offset >> PAGE_CACHE_SHIFT;
1594                 offset &= ~PAGE_CACHE_MASK;
1595
1596                 page_cache_release(page);
1597                 if (ret != nr || !desc->count)
1598                         break;
1599
1600                 cond_resched();
1601         }
1602
1603         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1604         file_accessed(filp);
1605 }
1606
1607 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1608 {
1609         read_descriptor_t desc;
1610
1611         if ((ssize_t) count < 0)
1612                 return -EINVAL;
1613         if (!access_ok(VERIFY_WRITE, buf, count))
1614                 return -EFAULT;
1615         if (!count)
1616                 return 0;
1617
1618         desc.written = 0;
1619         desc.count = count;
1620         desc.arg.buf = buf;
1621         desc.error = 0;
1622
1623         do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1624         if (desc.written)
1625                 return desc.written;
1626         return desc.error;
1627 }
1628
1629 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1630                          size_t count, read_actor_t actor, void *target)
1631 {
1632         read_descriptor_t desc;
1633
1634         if (!count)
1635                 return 0;
1636
1637         desc.written = 0;
1638         desc.count = count;
1639         desc.arg.data = target;
1640         desc.error = 0;
1641
1642         do_shmem_file_read(in_file, ppos, &desc, actor);
1643         if (desc.written)
1644                 return desc.written;
1645         return desc.error;
1646 }
1647
1648 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1649 {
1650         struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1651
1652         buf->f_type = TMPFS_MAGIC;
1653         buf->f_bsize = PAGE_CACHE_SIZE;
1654         buf->f_namelen = NAME_MAX;
1655         spin_lock(&sbinfo->stat_lock);
1656         if (sbinfo->max_blocks) {
1657                 buf->f_blocks = sbinfo->max_blocks;
1658                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1659         }
1660         if (sbinfo->max_inodes) {
1661                 buf->f_files = sbinfo->max_inodes;
1662                 buf->f_ffree = sbinfo->free_inodes;
1663         }
1664         /* else leave those fields 0 like simple_statfs */
1665         spin_unlock(&sbinfo->stat_lock);
1666         return 0;
1667 }
1668
1669 /*
1670  * File creation. Allocate an inode, and we're done..
1671  */
1672 static int
1673 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1674 {
1675         struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1676         int error = -ENOSPC;
1677
1678         if (inode) {
1679                 error = security_inode_init_security(inode, dir, NULL, NULL,
1680                                                      NULL);
1681                 if (error) {
1682                         if (error != -EOPNOTSUPP) {
1683                                 iput(inode);
1684                                 return error;
1685                         }
1686                         error = 0;
1687                 }
1688                 if (dir->i_mode & S_ISGID) {
1689                         inode->i_gid = dir->i_gid;
1690                         if (S_ISDIR(mode))
1691                                 inode->i_mode |= S_ISGID;
1692                 }
1693                 dir->i_size += BOGO_DIRENT_SIZE;
1694                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1695                 d_instantiate(dentry, inode);
1696                 dget(dentry); /* Extra count - pin the dentry in core */
1697         }
1698         return error;
1699 }
1700
1701 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1702 {
1703         int error;
1704
1705         if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1706                 return error;
1707         dir->i_nlink++;
1708         return 0;
1709 }
1710
1711 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1712                 struct nameidata *nd)
1713 {
1714         return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1715 }
1716
1717 /*
1718  * Link a file..
1719  */
1720 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1721 {
1722         struct inode *inode = old_dentry->d_inode;
1723         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1724
1725         /*
1726          * No ordinary (disk based) filesystem counts links as inodes;
1727          * but each new link needs a new dentry, pinning lowmem, and
1728          * tmpfs dentries cannot be pruned until they are unlinked.
1729          */
1730         if (sbinfo->max_inodes) {
1731                 spin_lock(&sbinfo->stat_lock);
1732                 if (!sbinfo->free_inodes) {
1733                         spin_unlock(&sbinfo->stat_lock);
1734                         return -ENOSPC;
1735                 }
1736                 sbinfo->free_inodes--;
1737                 spin_unlock(&sbinfo->stat_lock);
1738         }
1739
1740         dir->i_size += BOGO_DIRENT_SIZE;
1741         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1742         inode->i_nlink++;
1743         atomic_inc(&inode->i_count);    /* New dentry reference */
1744         dget(dentry);           /* Extra pinning count for the created dentry */
1745         d_instantiate(dentry, inode);
1746         return 0;
1747 }
1748
1749 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1750 {
1751         struct inode *inode = dentry->d_inode;
1752
1753         if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1754                 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1755                 if (sbinfo->max_inodes) {
1756                         spin_lock(&sbinfo->stat_lock);
1757                         sbinfo->free_inodes++;
1758                         spin_unlock(&sbinfo->stat_lock);
1759                 }
1760         }
1761
1762         dir->i_size -= BOGO_DIRENT_SIZE;
1763         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1764         inode->i_nlink--;
1765         dput(dentry);   /* Undo the count from "create" - this does all the work */
1766         return 0;
1767 }
1768
1769 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1770 {
1771         if (!simple_empty(dentry))
1772                 return -ENOTEMPTY;
1773
1774         dentry->d_inode->i_nlink--;
1775         dir->i_nlink--;
1776         return shmem_unlink(dir, dentry);
1777 }
1778
1779 /*
1780  * The VFS layer already does all the dentry stuff for rename,
1781  * we just have to decrement the usage count for the target if
1782  * it exists so that the VFS layer correctly free's it when it
1783  * gets overwritten.
1784  */
1785 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1786 {
1787         struct inode *inode = old_dentry->d_inode;
1788         int they_are_dirs = S_ISDIR(inode->i_mode);
1789
1790         if (!simple_empty(new_dentry))
1791                 return -ENOTEMPTY;
1792
1793         if (new_dentry->d_inode) {
1794                 (void) shmem_unlink(new_dir, new_dentry);
1795                 if (they_are_dirs)
1796                         old_dir->i_nlink--;
1797         } else if (they_are_dirs) {
1798                 old_dir->i_nlink--;
1799                 new_dir->i_nlink++;
1800         }
1801
1802         old_dir->i_size -= BOGO_DIRENT_SIZE;
1803         new_dir->i_size += BOGO_DIRENT_SIZE;
1804         old_dir->i_ctime = old_dir->i_mtime =
1805         new_dir->i_ctime = new_dir->i_mtime =
1806         inode->i_ctime = CURRENT_TIME;
1807         return 0;
1808 }
1809
1810 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1811 {
1812         int error;
1813         int len;
1814         struct inode *inode;
1815         struct page *page = NULL;
1816         char *kaddr;
1817         struct shmem_inode_info *info;
1818
1819         len = strlen(symname) + 1;
1820         if (len > PAGE_CACHE_SIZE)
1821                 return -ENAMETOOLONG;
1822
1823         inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1824         if (!inode)
1825                 return -ENOSPC;
1826
1827         error = security_inode_init_security(inode, dir, NULL, NULL,
1828                                              NULL);
1829         if (error) {
1830                 if (error != -EOPNOTSUPP) {
1831                         iput(inode);
1832                         return error;
1833                 }
1834                 error = 0;
1835         }
1836
1837         info = SHMEM_I(inode);
1838         inode->i_size = len-1;
1839         if (len <= (char *)inode - (char *)info) {
1840                 /* do it inline */
1841                 memcpy(info, symname, len);
1842                 inode->i_op = &shmem_symlink_inline_operations;
1843         } else {
1844                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1845                 if (error) {
1846                         iput(inode);
1847                         return error;
1848                 }
1849                 inode->i_op = &shmem_symlink_inode_operations;
1850                 kaddr = kmap_atomic(page, KM_USER0);
1851                 memcpy(kaddr, symname, len);
1852                 kunmap_atomic(kaddr, KM_USER0);
1853                 set_page_dirty(page);
1854                 page_cache_release(page);
1855         }
1856         if (dir->i_mode & S_ISGID)
1857                 inode->i_gid = dir->i_gid;
1858         dir->i_size += BOGO_DIRENT_SIZE;
1859         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1860         d_instantiate(dentry, inode);
1861         dget(dentry);
1862         return 0;
1863 }
1864
1865 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1866 {
1867         nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1868         return NULL;
1869 }
1870
1871 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1872 {
1873         struct page *page = NULL;
1874         int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1875         nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1876         return page;
1877 }
1878
1879 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1880 {
1881         if (!IS_ERR(nd_get_link(nd))) {
1882                 struct page *page = cookie;
1883                 kunmap(page);
1884                 mark_page_accessed(page);
1885                 page_cache_release(page);
1886         }
1887 }
1888
1889 static struct inode_operations shmem_symlink_inline_operations = {
1890         .readlink       = generic_readlink,
1891         .follow_link    = shmem_follow_link_inline,
1892 };
1893
1894 static struct inode_operations shmem_symlink_inode_operations = {
1895         .truncate       = shmem_truncate,
1896         .readlink       = generic_readlink,
1897         .follow_link    = shmem_follow_link,
1898         .put_link       = shmem_put_link,
1899 };
1900
1901 static int shmem_parse_options(char *options, int *mode, uid_t *uid,
1902         gid_t *gid, unsigned long *blocks, unsigned long *inodes,
1903         int *policy, nodemask_t *policy_nodes)
1904 {
1905         char *this_char, *value, *rest;
1906
1907         while (options != NULL) {
1908                 this_char = options;
1909                 for (;;) {
1910                         /*
1911                          * NUL-terminate this option: unfortunately,
1912                          * mount options form a comma-separated list,
1913                          * but mpol's nodelist may also contain commas.
1914                          */
1915                         options = strchr(options, ',');
1916                         if (options == NULL)
1917                                 break;
1918                         options++;
1919                         if (!isdigit(*options)) {
1920                                 options[-1] = '\0';
1921                                 break;
1922                         }
1923                 }
1924                 if (!*this_char)
1925                         continue;
1926                 if ((value = strchr(this_char,'=')) != NULL) {
1927                         *value++ = 0;
1928                 } else {
1929                         printk(KERN_ERR
1930                             "tmpfs: No value for mount option '%s'\n",
1931                             this_char);
1932                         return 1;
1933                 }
1934
1935                 if (!strcmp(this_char,"size")) {
1936                         unsigned long long size;
1937                         size = memparse(value,&rest);
1938                         if (*rest == '%') {
1939                                 size <<= PAGE_SHIFT;
1940                                 size *= totalram_pages;
1941                                 do_div(size, 100);
1942                                 rest++;
1943                         }
1944                         if (*rest)
1945                                 goto bad_val;
1946                         *blocks = size >> PAGE_CACHE_SHIFT;
1947                 } else if (!strcmp(this_char,"nr_blocks")) {
1948                         *blocks = memparse(value,&rest);
1949                         if (*rest)
1950                                 goto bad_val;
1951                 } else if (!strcmp(this_char,"nr_inodes")) {
1952                         *inodes = memparse(value,&rest);
1953                         if (*rest)
1954                                 goto bad_val;
1955                 } else if (!strcmp(this_char,"mode")) {
1956                         if (!mode)
1957                                 continue;
1958                         *mode = simple_strtoul(value,&rest,8);
1959                         if (*rest)
1960                                 goto bad_val;
1961                 } else if (!strcmp(this_char,"uid")) {
1962                         if (!uid)
1963                                 continue;
1964                         *uid = simple_strtoul(value,&rest,0);
1965                         if (*rest)
1966                                 goto bad_val;
1967                 } else if (!strcmp(this_char,"gid")) {
1968                         if (!gid)
1969                                 continue;
1970                         *gid = simple_strtoul(value,&rest,0);
1971                         if (*rest)
1972                                 goto bad_val;
1973                 } else if (!strcmp(this_char,"mpol")) {
1974                         if (shmem_parse_mpol(value,policy,policy_nodes))
1975                                 goto bad_val;
1976                 } else {
1977                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1978                                this_char);
1979                         return 1;
1980                 }
1981         }
1982         return 0;
1983
1984 bad_val:
1985         printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1986                value, this_char);
1987         return 1;
1988
1989 }
1990
1991 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1992 {
1993         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1994         unsigned long max_blocks = sbinfo->max_blocks;
1995         unsigned long max_inodes = sbinfo->max_inodes;
1996         int policy = sbinfo->policy;
1997         nodemask_t policy_nodes = sbinfo->policy_nodes;
1998         unsigned long blocks;
1999         unsigned long inodes;
2000         int error = -EINVAL;
2001
2002         if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2003                                 &max_inodes, &policy, &policy_nodes))
2004                 return error;
2005
2006         spin_lock(&sbinfo->stat_lock);
2007         blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2008         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2009         if (max_blocks < blocks)
2010                 goto out;
2011         if (max_inodes < inodes)
2012                 goto out;
2013         /*
2014          * Those tests also disallow limited->unlimited while any are in
2015          * use, so i_blocks will always be zero when max_blocks is zero;
2016          * but we must separately disallow unlimited->limited, because
2017          * in that case we have no record of how much is already in use.
2018          */
2019         if (max_blocks && !sbinfo->max_blocks)
2020                 goto out;
2021         if (max_inodes && !sbinfo->max_inodes)
2022                 goto out;
2023
2024         error = 0;
2025         sbinfo->max_blocks  = max_blocks;
2026         sbinfo->free_blocks = max_blocks - blocks;
2027         sbinfo->max_inodes  = max_inodes;
2028         sbinfo->free_inodes = max_inodes - inodes;
2029         sbinfo->policy = policy;
2030         sbinfo->policy_nodes = policy_nodes;
2031 out:
2032         spin_unlock(&sbinfo->stat_lock);
2033         return error;
2034 }
2035 #endif
2036
2037 static void shmem_put_super(struct super_block *sb)
2038 {
2039         kfree(sb->s_fs_info);
2040         sb->s_fs_info = NULL;
2041 }
2042
2043 static int shmem_fill_super(struct super_block *sb,
2044                             void *data, int silent)
2045 {
2046         struct inode *inode;
2047         struct dentry *root;
2048         int mode   = S_IRWXUGO | S_ISVTX;
2049         uid_t uid = current->fsuid;
2050         gid_t gid = current->fsgid;
2051         int err = -ENOMEM;
2052         struct shmem_sb_info *sbinfo;
2053         unsigned long blocks = 0;
2054         unsigned long inodes = 0;
2055         int policy = MPOL_DEFAULT;
2056         nodemask_t policy_nodes = node_online_map;
2057
2058 #ifdef CONFIG_TMPFS
2059         /*
2060          * Per default we only allow half of the physical ram per
2061          * tmpfs instance, limiting inodes to one per page of lowmem;
2062          * but the internal instance is left unlimited.
2063          */
2064         if (!(sb->s_flags & MS_NOUSER)) {
2065                 blocks = totalram_pages / 2;
2066                 inodes = totalram_pages - totalhigh_pages;
2067                 if (inodes > blocks)
2068                         inodes = blocks;
2069                 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2070                                         &inodes, &policy, &policy_nodes))
2071                         return -EINVAL;
2072         }
2073 #else
2074         sb->s_flags |= MS_NOUSER;
2075 #endif
2076
2077         /* Round up to L1_CACHE_BYTES to resist false sharing */
2078         sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2079                                 L1_CACHE_BYTES), GFP_KERNEL);
2080         if (!sbinfo)
2081                 return -ENOMEM;
2082
2083         spin_lock_init(&sbinfo->stat_lock);
2084         sbinfo->max_blocks = blocks;
2085         sbinfo->free_blocks = blocks;
2086         sbinfo->max_inodes = inodes;
2087         sbinfo->free_inodes = inodes;
2088         sbinfo->policy = policy;
2089         sbinfo->policy_nodes = policy_nodes;
2090
2091         sb->s_fs_info = sbinfo;
2092         sb->s_maxbytes = SHMEM_MAX_BYTES;
2093         sb->s_blocksize = PAGE_CACHE_SIZE;
2094         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2095         sb->s_magic = TMPFS_MAGIC;
2096         sb->s_op = &shmem_ops;
2097         sb->s_time_gran = 1;
2098
2099         inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2100         if (!inode)
2101                 goto failed;
2102         inode->i_uid = uid;
2103         inode->i_gid = gid;
2104         root = d_alloc_root(inode);
2105         if (!root)
2106                 goto failed_iput;
2107         sb->s_root = root;
2108         return 0;
2109
2110 failed_iput:
2111         iput(inode);
2112 failed:
2113         shmem_put_super(sb);
2114         return err;
2115 }
2116
2117 static struct kmem_cache *shmem_inode_cachep;
2118
2119 static struct inode *shmem_alloc_inode(struct super_block *sb)
2120 {
2121         struct shmem_inode_info *p;
2122         p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2123         if (!p)
2124                 return NULL;
2125         return &p->vfs_inode;
2126 }
2127
2128 static void shmem_destroy_inode(struct inode *inode)
2129 {
2130         if ((inode->i_mode & S_IFMT) == S_IFREG) {
2131                 /* only struct inode is valid if it's an inline symlink */
2132                 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2133         }
2134         kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2135 }
2136
2137 static void init_once(void *foo, struct kmem_cache *cachep,
2138                       unsigned long flags)
2139 {
2140         struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2141
2142         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2143             SLAB_CTOR_CONSTRUCTOR) {
2144                 inode_init_once(&p->vfs_inode);
2145         }
2146 }
2147
2148 static int init_inodecache(void)
2149 {
2150         shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2151                                 sizeof(struct shmem_inode_info),
2152                                 0, 0, init_once, NULL);
2153         if (shmem_inode_cachep == NULL)
2154                 return -ENOMEM;
2155         return 0;
2156 }
2157
2158 static void destroy_inodecache(void)
2159 {
2160         if (kmem_cache_destroy(shmem_inode_cachep))
2161                 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2162 }
2163
2164 static const struct address_space_operations shmem_aops = {
2165         .writepage      = shmem_writepage,
2166         .set_page_dirty = __set_page_dirty_nobuffers,
2167 #ifdef CONFIG_TMPFS
2168         .prepare_write  = shmem_prepare_write,
2169         .commit_write   = simple_commit_write,
2170 #endif
2171         .migratepage    = migrate_page,
2172 };
2173
2174 static struct file_operations shmem_file_operations = {
2175         .mmap           = shmem_mmap,
2176 #ifdef CONFIG_TMPFS
2177         .llseek         = generic_file_llseek,
2178         .read           = shmem_file_read,
2179         .write          = shmem_file_write,
2180         .fsync          = simple_sync_file,
2181         .sendfile       = shmem_file_sendfile,
2182 #endif
2183 };
2184
2185 static struct inode_operations shmem_inode_operations = {
2186         .truncate       = shmem_truncate,
2187         .setattr        = shmem_notify_change,
2188         .truncate_range = shmem_truncate_range,
2189 };
2190
2191 static struct inode_operations shmem_dir_inode_operations = {
2192 #ifdef CONFIG_TMPFS
2193         .create         = shmem_create,
2194         .lookup         = simple_lookup,
2195         .link           = shmem_link,
2196         .unlink         = shmem_unlink,
2197         .symlink        = shmem_symlink,
2198         .mkdir          = shmem_mkdir,
2199         .rmdir          = shmem_rmdir,
2200         .mknod          = shmem_mknod,
2201         .rename         = shmem_rename,
2202 #endif
2203 };
2204
2205 static struct super_operations shmem_ops = {
2206         .alloc_inode    = shmem_alloc_inode,
2207         .destroy_inode  = shmem_destroy_inode,
2208 #ifdef CONFIG_TMPFS
2209         .statfs         = shmem_statfs,
2210         .remount_fs     = shmem_remount_fs,
2211 #endif
2212         .delete_inode   = shmem_delete_inode,
2213         .drop_inode     = generic_delete_inode,
2214         .put_super      = shmem_put_super,
2215 };
2216
2217 static struct vm_operations_struct shmem_vm_ops = {
2218         .nopage         = shmem_nopage,
2219         .populate       = shmem_populate,
2220 #ifdef CONFIG_NUMA
2221         .set_policy     = shmem_set_policy,
2222         .get_policy     = shmem_get_policy,
2223 #endif
2224 };
2225
2226
2227 static int shmem_get_sb(struct file_system_type *fs_type,
2228         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2229 {
2230         return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2231 }
2232
2233 static struct file_system_type tmpfs_fs_type = {
2234         .owner          = THIS_MODULE,
2235         .name           = "tmpfs",
2236         .get_sb         = shmem_get_sb,
2237         .kill_sb        = kill_litter_super,
2238 };
2239 static struct vfsmount *shm_mnt;
2240
2241 static int __init init_tmpfs(void)
2242 {
2243         int error;
2244
2245         error = init_inodecache();
2246         if (error)
2247                 goto out3;
2248
2249         error = register_filesystem(&tmpfs_fs_type);
2250         if (error) {
2251                 printk(KERN_ERR "Could not register tmpfs\n");
2252                 goto out2;
2253         }
2254
2255         shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2256                                 tmpfs_fs_type.name, NULL);
2257         if (IS_ERR(shm_mnt)) {
2258                 error = PTR_ERR(shm_mnt);
2259                 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2260                 goto out1;
2261         }
2262         return 0;
2263
2264 out1:
2265         unregister_filesystem(&tmpfs_fs_type);
2266 out2:
2267         destroy_inodecache();
2268 out3:
2269         shm_mnt = ERR_PTR(error);
2270         return error;
2271 }
2272 module_init(init_tmpfs)
2273
2274 /*
2275  * shmem_file_setup - get an unlinked file living in tmpfs
2276  *
2277  * @name: name for dentry (to be seen in /proc/<pid>/maps
2278  * @size: size to be set for the file
2279  *
2280  */
2281 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2282 {
2283         int error;
2284         struct file *file;
2285         struct inode *inode;
2286         struct dentry *dentry, *root;
2287         struct qstr this;
2288
2289         if (IS_ERR(shm_mnt))
2290                 return (void *)shm_mnt;
2291
2292         if (size < 0 || size > SHMEM_MAX_BYTES)
2293                 return ERR_PTR(-EINVAL);
2294
2295         if (shmem_acct_size(flags, size))
2296                 return ERR_PTR(-ENOMEM);
2297
2298         error = -ENOMEM;
2299         this.name = name;
2300         this.len = strlen(name);
2301         this.hash = 0; /* will go */
2302         root = shm_mnt->mnt_root;
2303         dentry = d_alloc(root, &this);
2304         if (!dentry)
2305                 goto put_memory;
2306
2307         error = -ENFILE;
2308         file = get_empty_filp();
2309         if (!file)
2310                 goto put_dentry;
2311
2312         error = -ENOSPC;
2313         inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2314         if (!inode)
2315                 goto close_file;
2316
2317         SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2318         d_instantiate(dentry, inode);
2319         inode->i_size = size;
2320         inode->i_nlink = 0;     /* It is unlinked */
2321         file->f_vfsmnt = mntget(shm_mnt);
2322         file->f_dentry = dentry;
2323         file->f_mapping = inode->i_mapping;
2324         file->f_op = &shmem_file_operations;
2325         file->f_mode = FMODE_WRITE | FMODE_READ;
2326         return file;
2327
2328 close_file:
2329         put_filp(file);
2330 put_dentry:
2331         dput(dentry);
2332 put_memory:
2333         shmem_unacct_size(flags, size);
2334         return ERR_PTR(error);
2335 }
2336
2337 /*
2338  * shmem_zero_setup - setup a shared anonymous mapping
2339  *
2340  * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2341  */
2342 int shmem_zero_setup(struct vm_area_struct *vma)
2343 {
2344         struct file *file;
2345         loff_t size = vma->vm_end - vma->vm_start;
2346
2347         file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2348         if (IS_ERR(file))
2349                 return PTR_ERR(file);
2350
2351         if (vma->vm_file)
2352                 fput(vma->vm_file);
2353         vma->vm_file = file;
2354         vma->vm_ops = &shmem_vm_ops;
2355         return 0;
2356 }