Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux...
[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  * tiny-shmem:
18  * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
19  *
20  * This file is released under the GPL.
21  */
22
23 #include <linux/fs.h>
24 #include <linux/init.h>
25 #include <linux/vfs.h>
26 #include <linux/mount.h>
27 #include <linux/pagemap.h>
28 #include <linux/file.h>
29 #include <linux/mm.h>
30 #include <linux/module.h>
31 #include <linux/swap.h>
32 #include <linux/ima.h>
33
34 static struct vfsmount *shm_mnt;
35
36 #ifdef CONFIG_SHMEM
37 /*
38  * This virtual memory filesystem is heavily based on the ramfs. It
39  * extends ramfs by the ability to use swap and honor resource limits
40  * which makes it a completely usable filesystem.
41  */
42
43 #include <linux/xattr.h>
44 #include <linux/exportfs.h>
45 #include <linux/generic_acl.h>
46 #include <linux/mman.h>
47 #include <linux/string.h>
48 #include <linux/slab.h>
49 #include <linux/backing-dev.h>
50 #include <linux/shmem_fs.h>
51 #include <linux/writeback.h>
52 #include <linux/blkdev.h>
53 #include <linux/security.h>
54 #include <linux/swapops.h>
55 #include <linux/mempolicy.h>
56 #include <linux/namei.h>
57 #include <linux/ctype.h>
58 #include <linux/migrate.h>
59 #include <linux/highmem.h>
60 #include <linux/seq_file.h>
61 #include <linux/magic.h>
62
63 #include <asm/uaccess.h>
64 #include <asm/div64.h>
65 #include <asm/pgtable.h>
66
67 /*
68  * The maximum size of a shmem/tmpfs file is limited by the maximum size of
69  * its triple-indirect swap vector - see illustration at shmem_swp_entry().
70  *
71  * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
72  * but one eighth of that on a 64-bit kernel.  With 8kB page size, maximum
73  * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
74  * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
75  *
76  * We use / and * instead of shifts in the definitions below, so that the swap
77  * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
78  */
79 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
80 #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
81
82 #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
83 #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
84
85 #define SHMEM_MAX_BYTES  min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
86 #define SHMEM_MAX_INDEX  ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
87
88 #define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
89 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
90
91 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
92 #define SHMEM_PAGEIN     VM_READ
93 #define SHMEM_TRUNCATE   VM_WRITE
94
95 /* Definition to limit shmem_truncate's steps between cond_rescheds */
96 #define LATENCY_LIMIT    64
97
98 /* Pretend that each entry is of this size in directory's i_size */
99 #define BOGO_DIRENT_SIZE 20
100
101 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
102 enum sgp_type {
103         SGP_READ,       /* don't exceed i_size, don't allocate page */
104         SGP_CACHE,      /* don't exceed i_size, may allocate page */
105         SGP_DIRTY,      /* like SGP_CACHE, but set new page dirty */
106         SGP_WRITE,      /* may exceed i_size, may allocate page */
107 };
108
109 #ifdef CONFIG_TMPFS
110 static unsigned long shmem_default_max_blocks(void)
111 {
112         return totalram_pages / 2;
113 }
114
115 static unsigned long shmem_default_max_inodes(void)
116 {
117         return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
118 }
119 #endif
120
121 static int shmem_getpage(struct inode *inode, unsigned long idx,
122                          struct page **pagep, enum sgp_type sgp, int *type);
123
124 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
125 {
126         /*
127          * The above definition of ENTRIES_PER_PAGE, and the use of
128          * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
129          * might be reconsidered if it ever diverges from PAGE_SIZE.
130          *
131          * Mobility flags are masked out as swap vectors cannot move
132          */
133         return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
134                                 PAGE_CACHE_SHIFT-PAGE_SHIFT);
135 }
136
137 static inline void shmem_dir_free(struct page *page)
138 {
139         __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
140 }
141
142 static struct page **shmem_dir_map(struct page *page)
143 {
144         return (struct page **)kmap_atomic(page, KM_USER0);
145 }
146
147 static inline void shmem_dir_unmap(struct page **dir)
148 {
149         kunmap_atomic(dir, KM_USER0);
150 }
151
152 static swp_entry_t *shmem_swp_map(struct page *page)
153 {
154         return (swp_entry_t *)kmap_atomic(page, KM_USER1);
155 }
156
157 static inline void shmem_swp_balance_unmap(void)
158 {
159         /*
160          * When passing a pointer to an i_direct entry, to code which
161          * also handles indirect entries and so will shmem_swp_unmap,
162          * we must arrange for the preempt count to remain in balance.
163          * What kmap_atomic of a lowmem page does depends on config
164          * and architecture, so pretend to kmap_atomic some lowmem page.
165          */
166         (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
167 }
168
169 static inline void shmem_swp_unmap(swp_entry_t *entry)
170 {
171         kunmap_atomic(entry, KM_USER1);
172 }
173
174 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
175 {
176         return sb->s_fs_info;
177 }
178
179 /*
180  * shmem_file_setup pre-accounts the whole fixed size of a VM object,
181  * for shared memory and for shared anonymous (/dev/zero) mappings
182  * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
183  * consistent with the pre-accounting of private mappings ...
184  */
185 static inline int shmem_acct_size(unsigned long flags, loff_t size)
186 {
187         return (flags & VM_NORESERVE) ?
188                 0 : security_vm_enough_memory_kern(VM_ACCT(size));
189 }
190
191 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
192 {
193         if (!(flags & VM_NORESERVE))
194                 vm_unacct_memory(VM_ACCT(size));
195 }
196
197 /*
198  * ... whereas tmpfs objects are accounted incrementally as
199  * pages are allocated, in order to allow huge sparse files.
200  * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
201  * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
202  */
203 static inline int shmem_acct_block(unsigned long flags)
204 {
205         return (flags & VM_NORESERVE) ?
206                 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
207 }
208
209 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
210 {
211         if (flags & VM_NORESERVE)
212                 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
213 }
214
215 static const struct super_operations shmem_ops;
216 static const struct address_space_operations shmem_aops;
217 static const struct file_operations shmem_file_operations;
218 static const struct inode_operations shmem_inode_operations;
219 static const struct inode_operations shmem_dir_inode_operations;
220 static const struct inode_operations shmem_special_inode_operations;
221 static struct vm_operations_struct shmem_vm_ops;
222
223 static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
224         .ra_pages       = 0,    /* No readahead */
225         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
226         .unplug_io_fn   = default_unplug_io_fn,
227 };
228
229 static LIST_HEAD(shmem_swaplist);
230 static DEFINE_MUTEX(shmem_swaplist_mutex);
231
232 static void shmem_free_blocks(struct inode *inode, long pages)
233 {
234         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
235         if (sbinfo->max_blocks) {
236                 spin_lock(&sbinfo->stat_lock);
237                 sbinfo->free_blocks += pages;
238                 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
239                 spin_unlock(&sbinfo->stat_lock);
240         }
241 }
242
243 static int shmem_reserve_inode(struct super_block *sb)
244 {
245         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
246         if (sbinfo->max_inodes) {
247                 spin_lock(&sbinfo->stat_lock);
248                 if (!sbinfo->free_inodes) {
249                         spin_unlock(&sbinfo->stat_lock);
250                         return -ENOSPC;
251                 }
252                 sbinfo->free_inodes--;
253                 spin_unlock(&sbinfo->stat_lock);
254         }
255         return 0;
256 }
257
258 static void shmem_free_inode(struct super_block *sb)
259 {
260         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
261         if (sbinfo->max_inodes) {
262                 spin_lock(&sbinfo->stat_lock);
263                 sbinfo->free_inodes++;
264                 spin_unlock(&sbinfo->stat_lock);
265         }
266 }
267
268 /**
269  * shmem_recalc_inode - recalculate the size of an inode
270  * @inode: inode to recalc
271  *
272  * We have to calculate the free blocks since the mm can drop
273  * undirtied hole pages behind our back.
274  *
275  * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
276  * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
277  *
278  * It has to be called with the spinlock held.
279  */
280 static void shmem_recalc_inode(struct inode *inode)
281 {
282         struct shmem_inode_info *info = SHMEM_I(inode);
283         long freed;
284
285         freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
286         if (freed > 0) {
287                 info->alloced -= freed;
288                 shmem_unacct_blocks(info->flags, freed);
289                 shmem_free_blocks(inode, freed);
290         }
291 }
292
293 /**
294  * shmem_swp_entry - find the swap vector position in the info structure
295  * @info:  info structure for the inode
296  * @index: index of the page to find
297  * @page:  optional page to add to the structure. Has to be preset to
298  *         all zeros
299  *
300  * If there is no space allocated yet it will return NULL when
301  * page is NULL, else it will use the page for the needed block,
302  * setting it to NULL on return to indicate that it has been used.
303  *
304  * The swap vector is organized the following way:
305  *
306  * There are SHMEM_NR_DIRECT entries directly stored in the
307  * shmem_inode_info structure. So small files do not need an addional
308  * allocation.
309  *
310  * For pages with index > SHMEM_NR_DIRECT there is the pointer
311  * i_indirect which points to a page which holds in the first half
312  * doubly indirect blocks, in the second half triple indirect blocks:
313  *
314  * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
315  * following layout (for SHMEM_NR_DIRECT == 16):
316  *
317  * i_indirect -> dir --> 16-19
318  *            |      +-> 20-23
319  *            |
320  *            +-->dir2 --> 24-27
321  *            |        +-> 28-31
322  *            |        +-> 32-35
323  *            |        +-> 36-39
324  *            |
325  *            +-->dir3 --> 40-43
326  *                     +-> 44-47
327  *                     +-> 48-51
328  *                     +-> 52-55
329  */
330 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
331 {
332         unsigned long offset;
333         struct page **dir;
334         struct page *subdir;
335
336         if (index < SHMEM_NR_DIRECT) {
337                 shmem_swp_balance_unmap();
338                 return info->i_direct+index;
339         }
340         if (!info->i_indirect) {
341                 if (page) {
342                         info->i_indirect = *page;
343                         *page = NULL;
344                 }
345                 return NULL;                    /* need another page */
346         }
347
348         index -= SHMEM_NR_DIRECT;
349         offset = index % ENTRIES_PER_PAGE;
350         index /= ENTRIES_PER_PAGE;
351         dir = shmem_dir_map(info->i_indirect);
352
353         if (index >= ENTRIES_PER_PAGE/2) {
354                 index -= ENTRIES_PER_PAGE/2;
355                 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
356                 index %= ENTRIES_PER_PAGE;
357                 subdir = *dir;
358                 if (!subdir) {
359                         if (page) {
360                                 *dir = *page;
361                                 *page = NULL;
362                         }
363                         shmem_dir_unmap(dir);
364                         return NULL;            /* need another page */
365                 }
366                 shmem_dir_unmap(dir);
367                 dir = shmem_dir_map(subdir);
368         }
369
370         dir += index;
371         subdir = *dir;
372         if (!subdir) {
373                 if (!page || !(subdir = *page)) {
374                         shmem_dir_unmap(dir);
375                         return NULL;            /* need a page */
376                 }
377                 *dir = subdir;
378                 *page = NULL;
379         }
380         shmem_dir_unmap(dir);
381         return shmem_swp_map(subdir) + offset;
382 }
383
384 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
385 {
386         long incdec = value? 1: -1;
387
388         entry->val = value;
389         info->swapped += incdec;
390         if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
391                 struct page *page = kmap_atomic_to_page(entry);
392                 set_page_private(page, page_private(page) + incdec);
393         }
394 }
395
396 /**
397  * shmem_swp_alloc - get the position of the swap entry for the page.
398  * @info:       info structure for the inode
399  * @index:      index of the page to find
400  * @sgp:        check and recheck i_size? skip allocation?
401  *
402  * If the entry does not exist, allocate it.
403  */
404 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
405 {
406         struct inode *inode = &info->vfs_inode;
407         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
408         struct page *page = NULL;
409         swp_entry_t *entry;
410
411         if (sgp != SGP_WRITE &&
412             ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
413                 return ERR_PTR(-EINVAL);
414
415         while (!(entry = shmem_swp_entry(info, index, &page))) {
416                 if (sgp == SGP_READ)
417                         return shmem_swp_map(ZERO_PAGE(0));
418                 /*
419                  * Test free_blocks against 1 not 0, since we have 1 data
420                  * page (and perhaps indirect index pages) yet to allocate:
421                  * a waste to allocate index if we cannot allocate data.
422                  */
423                 if (sbinfo->max_blocks) {
424                         spin_lock(&sbinfo->stat_lock);
425                         if (sbinfo->free_blocks <= 1) {
426                                 spin_unlock(&sbinfo->stat_lock);
427                                 return ERR_PTR(-ENOSPC);
428                         }
429                         sbinfo->free_blocks--;
430                         inode->i_blocks += BLOCKS_PER_PAGE;
431                         spin_unlock(&sbinfo->stat_lock);
432                 }
433
434                 spin_unlock(&info->lock);
435                 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
436                 if (page)
437                         set_page_private(page, 0);
438                 spin_lock(&info->lock);
439
440                 if (!page) {
441                         shmem_free_blocks(inode, 1);
442                         return ERR_PTR(-ENOMEM);
443                 }
444                 if (sgp != SGP_WRITE &&
445                     ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
446                         entry = ERR_PTR(-EINVAL);
447                         break;
448                 }
449                 if (info->next_index <= index)
450                         info->next_index = index + 1;
451         }
452         if (page) {
453                 /* another task gave its page, or truncated the file */
454                 shmem_free_blocks(inode, 1);
455                 shmem_dir_free(page);
456         }
457         if (info->next_index <= index && !IS_ERR(entry))
458                 info->next_index = index + 1;
459         return entry;
460 }
461
462 /**
463  * shmem_free_swp - free some swap entries in a directory
464  * @dir:        pointer to the directory
465  * @edir:       pointer after last entry of the directory
466  * @punch_lock: pointer to spinlock when needed for the holepunch case
467  */
468 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
469                                                 spinlock_t *punch_lock)
470 {
471         spinlock_t *punch_unlock = NULL;
472         swp_entry_t *ptr;
473         int freed = 0;
474
475         for (ptr = dir; ptr < edir; ptr++) {
476                 if (ptr->val) {
477                         if (unlikely(punch_lock)) {
478                                 punch_unlock = punch_lock;
479                                 punch_lock = NULL;
480                                 spin_lock(punch_unlock);
481                                 if (!ptr->val)
482                                         continue;
483                         }
484                         free_swap_and_cache(*ptr);
485                         *ptr = (swp_entry_t){0};
486                         freed++;
487                 }
488         }
489         if (punch_unlock)
490                 spin_unlock(punch_unlock);
491         return freed;
492 }
493
494 static int shmem_map_and_free_swp(struct page *subdir, int offset,
495                 int limit, struct page ***dir, spinlock_t *punch_lock)
496 {
497         swp_entry_t *ptr;
498         int freed = 0;
499
500         ptr = shmem_swp_map(subdir);
501         for (; offset < limit; offset += LATENCY_LIMIT) {
502                 int size = limit - offset;
503                 if (size > LATENCY_LIMIT)
504                         size = LATENCY_LIMIT;
505                 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
506                                                         punch_lock);
507                 if (need_resched()) {
508                         shmem_swp_unmap(ptr);
509                         if (*dir) {
510                                 shmem_dir_unmap(*dir);
511                                 *dir = NULL;
512                         }
513                         cond_resched();
514                         ptr = shmem_swp_map(subdir);
515                 }
516         }
517         shmem_swp_unmap(ptr);
518         return freed;
519 }
520
521 static void shmem_free_pages(struct list_head *next)
522 {
523         struct page *page;
524         int freed = 0;
525
526         do {
527                 page = container_of(next, struct page, lru);
528                 next = next->next;
529                 shmem_dir_free(page);
530                 freed++;
531                 if (freed >= LATENCY_LIMIT) {
532                         cond_resched();
533                         freed = 0;
534                 }
535         } while (next);
536 }
537
538 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
539 {
540         struct shmem_inode_info *info = SHMEM_I(inode);
541         unsigned long idx;
542         unsigned long size;
543         unsigned long limit;
544         unsigned long stage;
545         unsigned long diroff;
546         struct page **dir;
547         struct page *topdir;
548         struct page *middir;
549         struct page *subdir;
550         swp_entry_t *ptr;
551         LIST_HEAD(pages_to_free);
552         long nr_pages_to_free = 0;
553         long nr_swaps_freed = 0;
554         int offset;
555         int freed;
556         int punch_hole;
557         spinlock_t *needs_lock;
558         spinlock_t *punch_lock;
559         unsigned long upper_limit;
560
561         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
562         idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
563         if (idx >= info->next_index)
564                 return;
565
566         spin_lock(&info->lock);
567         info->flags |= SHMEM_TRUNCATE;
568         if (likely(end == (loff_t) -1)) {
569                 limit = info->next_index;
570                 upper_limit = SHMEM_MAX_INDEX;
571                 info->next_index = idx;
572                 needs_lock = NULL;
573                 punch_hole = 0;
574         } else {
575                 if (end + 1 >= inode->i_size) { /* we may free a little more */
576                         limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
577                                                         PAGE_CACHE_SHIFT;
578                         upper_limit = SHMEM_MAX_INDEX;
579                 } else {
580                         limit = (end + 1) >> PAGE_CACHE_SHIFT;
581                         upper_limit = limit;
582                 }
583                 needs_lock = &info->lock;
584                 punch_hole = 1;
585         }
586
587         topdir = info->i_indirect;
588         if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
589                 info->i_indirect = NULL;
590                 nr_pages_to_free++;
591                 list_add(&topdir->lru, &pages_to_free);
592         }
593         spin_unlock(&info->lock);
594
595         if (info->swapped && idx < SHMEM_NR_DIRECT) {
596                 ptr = info->i_direct;
597                 size = limit;
598                 if (size > SHMEM_NR_DIRECT)
599                         size = SHMEM_NR_DIRECT;
600                 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
601         }
602
603         /*
604          * If there are no indirect blocks or we are punching a hole
605          * below indirect blocks, nothing to be done.
606          */
607         if (!topdir || limit <= SHMEM_NR_DIRECT)
608                 goto done2;
609
610         /*
611          * The truncation case has already dropped info->lock, and we're safe
612          * because i_size and next_index have already been lowered, preventing
613          * access beyond.  But in the punch_hole case, we still need to take
614          * the lock when updating the swap directory, because there might be
615          * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
616          * shmem_writepage.  However, whenever we find we can remove a whole
617          * directory page (not at the misaligned start or end of the range),
618          * we first NULLify its pointer in the level above, and then have no
619          * need to take the lock when updating its contents: needs_lock and
620          * punch_lock (either pointing to info->lock or NULL) manage this.
621          */
622
623         upper_limit -= SHMEM_NR_DIRECT;
624         limit -= SHMEM_NR_DIRECT;
625         idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
626         offset = idx % ENTRIES_PER_PAGE;
627         idx -= offset;
628
629         dir = shmem_dir_map(topdir);
630         stage = ENTRIES_PER_PAGEPAGE/2;
631         if (idx < ENTRIES_PER_PAGEPAGE/2) {
632                 middir = topdir;
633                 diroff = idx/ENTRIES_PER_PAGE;
634         } else {
635                 dir += ENTRIES_PER_PAGE/2;
636                 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
637                 while (stage <= idx)
638                         stage += ENTRIES_PER_PAGEPAGE;
639                 middir = *dir;
640                 if (*dir) {
641                         diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
642                                 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
643                         if (!diroff && !offset && upper_limit >= stage) {
644                                 if (needs_lock) {
645                                         spin_lock(needs_lock);
646                                         *dir = NULL;
647                                         spin_unlock(needs_lock);
648                                         needs_lock = NULL;
649                                 } else
650                                         *dir = NULL;
651                                 nr_pages_to_free++;
652                                 list_add(&middir->lru, &pages_to_free);
653                         }
654                         shmem_dir_unmap(dir);
655                         dir = shmem_dir_map(middir);
656                 } else {
657                         diroff = 0;
658                         offset = 0;
659                         idx = stage;
660                 }
661         }
662
663         for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
664                 if (unlikely(idx == stage)) {
665                         shmem_dir_unmap(dir);
666                         dir = shmem_dir_map(topdir) +
667                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
668                         while (!*dir) {
669                                 dir++;
670                                 idx += ENTRIES_PER_PAGEPAGE;
671                                 if (idx >= limit)
672                                         goto done1;
673                         }
674                         stage = idx + ENTRIES_PER_PAGEPAGE;
675                         middir = *dir;
676                         if (punch_hole)
677                                 needs_lock = &info->lock;
678                         if (upper_limit >= stage) {
679                                 if (needs_lock) {
680                                         spin_lock(needs_lock);
681                                         *dir = NULL;
682                                         spin_unlock(needs_lock);
683                                         needs_lock = NULL;
684                                 } else
685                                         *dir = NULL;
686                                 nr_pages_to_free++;
687                                 list_add(&middir->lru, &pages_to_free);
688                         }
689                         shmem_dir_unmap(dir);
690                         cond_resched();
691                         dir = shmem_dir_map(middir);
692                         diroff = 0;
693                 }
694                 punch_lock = needs_lock;
695                 subdir = dir[diroff];
696                 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
697                         if (needs_lock) {
698                                 spin_lock(needs_lock);
699                                 dir[diroff] = NULL;
700                                 spin_unlock(needs_lock);
701                                 punch_lock = NULL;
702                         } else
703                                 dir[diroff] = NULL;
704                         nr_pages_to_free++;
705                         list_add(&subdir->lru, &pages_to_free);
706                 }
707                 if (subdir && page_private(subdir) /* has swap entries */) {
708                         size = limit - idx;
709                         if (size > ENTRIES_PER_PAGE)
710                                 size = ENTRIES_PER_PAGE;
711                         freed = shmem_map_and_free_swp(subdir,
712                                         offset, size, &dir, punch_lock);
713                         if (!dir)
714                                 dir = shmem_dir_map(middir);
715                         nr_swaps_freed += freed;
716                         if (offset || punch_lock) {
717                                 spin_lock(&info->lock);
718                                 set_page_private(subdir,
719                                         page_private(subdir) - freed);
720                                 spin_unlock(&info->lock);
721                         } else
722                                 BUG_ON(page_private(subdir) != freed);
723                 }
724                 offset = 0;
725         }
726 done1:
727         shmem_dir_unmap(dir);
728 done2:
729         if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
730                 /*
731                  * Call truncate_inode_pages again: racing shmem_unuse_inode
732                  * may have swizzled a page in from swap since vmtruncate or
733                  * generic_delete_inode did it, before we lowered next_index.
734                  * Also, though shmem_getpage checks i_size before adding to
735                  * cache, no recheck after: so fix the narrow window there too.
736                  *
737                  * Recalling truncate_inode_pages_range and unmap_mapping_range
738                  * every time for punch_hole (which never got a chance to clear
739                  * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
740                  * yet hardly ever necessary: try to optimize them out later.
741                  */
742                 truncate_inode_pages_range(inode->i_mapping, start, end);
743                 if (punch_hole)
744                         unmap_mapping_range(inode->i_mapping, start,
745                                                         end - start, 1);
746         }
747
748         spin_lock(&info->lock);
749         info->flags &= ~SHMEM_TRUNCATE;
750         info->swapped -= nr_swaps_freed;
751         if (nr_pages_to_free)
752                 shmem_free_blocks(inode, nr_pages_to_free);
753         shmem_recalc_inode(inode);
754         spin_unlock(&info->lock);
755
756         /*
757          * Empty swap vector directory pages to be freed?
758          */
759         if (!list_empty(&pages_to_free)) {
760                 pages_to_free.prev->next = NULL;
761                 shmem_free_pages(pages_to_free.next);
762         }
763 }
764
765 static void shmem_truncate(struct inode *inode)
766 {
767         shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
768 }
769
770 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
771 {
772         struct inode *inode = dentry->d_inode;
773         struct page *page = NULL;
774         int error;
775
776         if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
777                 if (attr->ia_size < inode->i_size) {
778                         /*
779                          * If truncating down to a partial page, then
780                          * if that page is already allocated, hold it
781                          * in memory until the truncation is over, so
782                          * truncate_partial_page cannnot miss it were
783                          * it assigned to swap.
784                          */
785                         if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
786                                 (void) shmem_getpage(inode,
787                                         attr->ia_size>>PAGE_CACHE_SHIFT,
788                                                 &page, SGP_READ, NULL);
789                                 if (page)
790                                         unlock_page(page);
791                         }
792                         /*
793                          * Reset SHMEM_PAGEIN flag so that shmem_truncate can
794                          * detect if any pages might have been added to cache
795                          * after truncate_inode_pages.  But we needn't bother
796                          * if it's being fully truncated to zero-length: the
797                          * nrpages check is efficient enough in that case.
798                          */
799                         if (attr->ia_size) {
800                                 struct shmem_inode_info *info = SHMEM_I(inode);
801                                 spin_lock(&info->lock);
802                                 info->flags &= ~SHMEM_PAGEIN;
803                                 spin_unlock(&info->lock);
804                         }
805                 }
806         }
807
808         error = inode_change_ok(inode, attr);
809         if (!error)
810                 error = inode_setattr(inode, attr);
811 #ifdef CONFIG_TMPFS_POSIX_ACL
812         if (!error && (attr->ia_valid & ATTR_MODE))
813                 error = generic_acl_chmod(inode, &shmem_acl_ops);
814 #endif
815         if (page)
816                 page_cache_release(page);
817         return error;
818 }
819
820 static void shmem_delete_inode(struct inode *inode)
821 {
822         struct shmem_inode_info *info = SHMEM_I(inode);
823
824         if (inode->i_op->truncate == shmem_truncate) {
825                 truncate_inode_pages(inode->i_mapping, 0);
826                 shmem_unacct_size(info->flags, inode->i_size);
827                 inode->i_size = 0;
828                 shmem_truncate(inode);
829                 if (!list_empty(&info->swaplist)) {
830                         mutex_lock(&shmem_swaplist_mutex);
831                         list_del_init(&info->swaplist);
832                         mutex_unlock(&shmem_swaplist_mutex);
833                 }
834         }
835         BUG_ON(inode->i_blocks);
836         shmem_free_inode(inode->i_sb);
837         clear_inode(inode);
838 }
839
840 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
841 {
842         swp_entry_t *ptr;
843
844         for (ptr = dir; ptr < edir; ptr++) {
845                 if (ptr->val == entry.val)
846                         return ptr - dir;
847         }
848         return -1;
849 }
850
851 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
852 {
853         struct inode *inode;
854         unsigned long idx;
855         unsigned long size;
856         unsigned long limit;
857         unsigned long stage;
858         struct page **dir;
859         struct page *subdir;
860         swp_entry_t *ptr;
861         int offset;
862         int error;
863
864         idx = 0;
865         ptr = info->i_direct;
866         spin_lock(&info->lock);
867         if (!info->swapped) {
868                 list_del_init(&info->swaplist);
869                 goto lost2;
870         }
871         limit = info->next_index;
872         size = limit;
873         if (size > SHMEM_NR_DIRECT)
874                 size = SHMEM_NR_DIRECT;
875         offset = shmem_find_swp(entry, ptr, ptr+size);
876         if (offset >= 0)
877                 goto found;
878         if (!info->i_indirect)
879                 goto lost2;
880
881         dir = shmem_dir_map(info->i_indirect);
882         stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
883
884         for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
885                 if (unlikely(idx == stage)) {
886                         shmem_dir_unmap(dir-1);
887                         if (cond_resched_lock(&info->lock)) {
888                                 /* check it has not been truncated */
889                                 if (limit > info->next_index) {
890                                         limit = info->next_index;
891                                         if (idx >= limit)
892                                                 goto lost2;
893                                 }
894                         }
895                         dir = shmem_dir_map(info->i_indirect) +
896                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
897                         while (!*dir) {
898                                 dir++;
899                                 idx += ENTRIES_PER_PAGEPAGE;
900                                 if (idx >= limit)
901                                         goto lost1;
902                         }
903                         stage = idx + ENTRIES_PER_PAGEPAGE;
904                         subdir = *dir;
905                         shmem_dir_unmap(dir);
906                         dir = shmem_dir_map(subdir);
907                 }
908                 subdir = *dir;
909                 if (subdir && page_private(subdir)) {
910                         ptr = shmem_swp_map(subdir);
911                         size = limit - idx;
912                         if (size > ENTRIES_PER_PAGE)
913                                 size = ENTRIES_PER_PAGE;
914                         offset = shmem_find_swp(entry, ptr, ptr+size);
915                         shmem_swp_unmap(ptr);
916                         if (offset >= 0) {
917                                 shmem_dir_unmap(dir);
918                                 goto found;
919                         }
920                 }
921         }
922 lost1:
923         shmem_dir_unmap(dir-1);
924 lost2:
925         spin_unlock(&info->lock);
926         return 0;
927 found:
928         idx += offset;
929         inode = igrab(&info->vfs_inode);
930         spin_unlock(&info->lock);
931
932         /*
933          * Move _head_ to start search for next from here.
934          * But be careful: shmem_delete_inode checks list_empty without taking
935          * mutex, and there's an instant in list_move_tail when info->swaplist
936          * would appear empty, if it were the only one on shmem_swaplist.  We
937          * could avoid doing it if inode NULL; or use this minor optimization.
938          */
939         if (shmem_swaplist.next != &info->swaplist)
940                 list_move_tail(&shmem_swaplist, &info->swaplist);
941         mutex_unlock(&shmem_swaplist_mutex);
942
943         error = 1;
944         if (!inode)
945                 goto out;
946         /*
947          * Charge page using GFP_KERNEL while we can wait.
948          * Charged back to the user(not to caller) when swap account is used.
949          * add_to_page_cache() will be called with GFP_NOWAIT.
950          */
951         error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
952         if (error)
953                 goto out;
954         error = radix_tree_preload(GFP_KERNEL);
955         if (error) {
956                 mem_cgroup_uncharge_cache_page(page);
957                 goto out;
958         }
959         error = 1;
960
961         spin_lock(&info->lock);
962         ptr = shmem_swp_entry(info, idx, NULL);
963         if (ptr && ptr->val == entry.val) {
964                 error = add_to_page_cache_locked(page, inode->i_mapping,
965                                                 idx, GFP_NOWAIT);
966                 /* does mem_cgroup_uncharge_cache_page on error */
967         } else  /* we must compensate for our precharge above */
968                 mem_cgroup_uncharge_cache_page(page);
969
970         if (error == -EEXIST) {
971                 struct page *filepage = find_get_page(inode->i_mapping, idx);
972                 error = 1;
973                 if (filepage) {
974                         /*
975                          * There might be a more uptodate page coming down
976                          * from a stacked writepage: forget our swappage if so.
977                          */
978                         if (PageUptodate(filepage))
979                                 error = 0;
980                         page_cache_release(filepage);
981                 }
982         }
983         if (!error) {
984                 delete_from_swap_cache(page);
985                 set_page_dirty(page);
986                 info->flags |= SHMEM_PAGEIN;
987                 shmem_swp_set(info, ptr, 0);
988                 swap_free(entry);
989                 error = 1;      /* not an error, but entry was found */
990         }
991         if (ptr)
992                 shmem_swp_unmap(ptr);
993         spin_unlock(&info->lock);
994         radix_tree_preload_end();
995 out:
996         unlock_page(page);
997         page_cache_release(page);
998         iput(inode);            /* allows for NULL */
999         return error;
1000 }
1001
1002 /*
1003  * shmem_unuse() search for an eventually swapped out shmem page.
1004  */
1005 int shmem_unuse(swp_entry_t entry, struct page *page)
1006 {
1007         struct list_head *p, *next;
1008         struct shmem_inode_info *info;
1009         int found = 0;
1010
1011         mutex_lock(&shmem_swaplist_mutex);
1012         list_for_each_safe(p, next, &shmem_swaplist) {
1013                 info = list_entry(p, struct shmem_inode_info, swaplist);
1014                 found = shmem_unuse_inode(info, entry, page);
1015                 cond_resched();
1016                 if (found)
1017                         goto out;
1018         }
1019         mutex_unlock(&shmem_swaplist_mutex);
1020 out:    return found;   /* 0 or 1 or -ENOMEM */
1021 }
1022
1023 /*
1024  * Move the page from the page cache to the swap cache.
1025  */
1026 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1027 {
1028         struct shmem_inode_info *info;
1029         swp_entry_t *entry, swap;
1030         struct address_space *mapping;
1031         unsigned long index;
1032         struct inode *inode;
1033
1034         BUG_ON(!PageLocked(page));
1035         mapping = page->mapping;
1036         index = page->index;
1037         inode = mapping->host;
1038         info = SHMEM_I(inode);
1039         if (info->flags & VM_LOCKED)
1040                 goto redirty;
1041         if (!total_swap_pages)
1042                 goto redirty;
1043
1044         /*
1045          * shmem_backing_dev_info's capabilities prevent regular writeback or
1046          * sync from ever calling shmem_writepage; but a stacking filesystem
1047          * may use the ->writepage of its underlying filesystem, in which case
1048          * tmpfs should write out to swap only in response to memory pressure,
1049          * and not for pdflush or sync.  However, in those cases, we do still
1050          * want to check if there's a redundant swappage to be discarded.
1051          */
1052         if (wbc->for_reclaim)
1053                 swap = get_swap_page();
1054         else
1055                 swap.val = 0;
1056
1057         spin_lock(&info->lock);
1058         if (index >= info->next_index) {
1059                 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1060                 goto unlock;
1061         }
1062         entry = shmem_swp_entry(info, index, NULL);
1063         if (entry->val) {
1064                 /*
1065                  * The more uptodate page coming down from a stacked
1066                  * writepage should replace our old swappage.
1067                  */
1068                 free_swap_and_cache(*entry);
1069                 shmem_swp_set(info, entry, 0);
1070         }
1071         shmem_recalc_inode(inode);
1072
1073         if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1074                 remove_from_page_cache(page);
1075                 shmem_swp_set(info, entry, swap.val);
1076                 shmem_swp_unmap(entry);
1077                 if (list_empty(&info->swaplist))
1078                         inode = igrab(inode);
1079                 else
1080                         inode = NULL;
1081                 spin_unlock(&info->lock);
1082                 swap_duplicate(swap);
1083                 BUG_ON(page_mapped(page));
1084                 page_cache_release(page);       /* pagecache ref */
1085                 swap_writepage(page, wbc);
1086                 if (inode) {
1087                         mutex_lock(&shmem_swaplist_mutex);
1088                         /* move instead of add in case we're racing */
1089                         list_move_tail(&info->swaplist, &shmem_swaplist);
1090                         mutex_unlock(&shmem_swaplist_mutex);
1091                         iput(inode);
1092                 }
1093                 return 0;
1094         }
1095
1096         shmem_swp_unmap(entry);
1097 unlock:
1098         spin_unlock(&info->lock);
1099         /*
1100          * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1101          * clear SWAP_HAS_CACHE flag.
1102          */
1103         swapcache_free(swap, NULL);
1104 redirty:
1105         set_page_dirty(page);
1106         if (wbc->for_reclaim)
1107                 return AOP_WRITEPAGE_ACTIVATE;  /* Return with page locked */
1108         unlock_page(page);
1109         return 0;
1110 }
1111
1112 #ifdef CONFIG_NUMA
1113 #ifdef CONFIG_TMPFS
1114 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1115 {
1116         char buffer[64];
1117
1118         if (!mpol || mpol->mode == MPOL_DEFAULT)
1119                 return;         /* show nothing */
1120
1121         mpol_to_str(buffer, sizeof(buffer), mpol, 1);
1122
1123         seq_printf(seq, ",mpol=%s", buffer);
1124 }
1125
1126 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1127 {
1128         struct mempolicy *mpol = NULL;
1129         if (sbinfo->mpol) {
1130                 spin_lock(&sbinfo->stat_lock);  /* prevent replace/use races */
1131                 mpol = sbinfo->mpol;
1132                 mpol_get(mpol);
1133                 spin_unlock(&sbinfo->stat_lock);
1134         }
1135         return mpol;
1136 }
1137 #endif /* CONFIG_TMPFS */
1138
1139 static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1140                         struct shmem_inode_info *info, unsigned long idx)
1141 {
1142         struct mempolicy mpol, *spol;
1143         struct vm_area_struct pvma;
1144         struct page *page;
1145
1146         spol = mpol_cond_copy(&mpol,
1147                                 mpol_shared_policy_lookup(&info->policy, idx));
1148
1149         /* Create a pseudo vma that just contains the policy */
1150         pvma.vm_start = 0;
1151         pvma.vm_pgoff = idx;
1152         pvma.vm_ops = NULL;
1153         pvma.vm_policy = spol;
1154         page = swapin_readahead(entry, gfp, &pvma, 0);
1155         return page;
1156 }
1157
1158 static struct page *shmem_alloc_page(gfp_t gfp,
1159                         struct shmem_inode_info *info, unsigned long idx)
1160 {
1161         struct vm_area_struct pvma;
1162
1163         /* Create a pseudo vma that just contains the policy */
1164         pvma.vm_start = 0;
1165         pvma.vm_pgoff = idx;
1166         pvma.vm_ops = NULL;
1167         pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1168
1169         /*
1170          * alloc_page_vma() will drop the shared policy reference
1171          */
1172         return alloc_page_vma(gfp, &pvma, 0);
1173 }
1174 #else /* !CONFIG_NUMA */
1175 #ifdef CONFIG_TMPFS
1176 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
1177 {
1178 }
1179 #endif /* CONFIG_TMPFS */
1180
1181 static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1182                         struct shmem_inode_info *info, unsigned long idx)
1183 {
1184         return swapin_readahead(entry, gfp, NULL, 0);
1185 }
1186
1187 static inline struct page *shmem_alloc_page(gfp_t gfp,
1188                         struct shmem_inode_info *info, unsigned long idx)
1189 {
1190         return alloc_page(gfp);
1191 }
1192 #endif /* CONFIG_NUMA */
1193
1194 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1195 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1196 {
1197         return NULL;
1198 }
1199 #endif
1200
1201 /*
1202  * shmem_getpage - either get the page from swap or allocate a new one
1203  *
1204  * If we allocate a new one we do not mark it dirty. That's up to the
1205  * vm. If we swap it in we mark it dirty since we also free the swap
1206  * entry since a page cannot live in both the swap and page cache
1207  */
1208 static int shmem_getpage(struct inode *inode, unsigned long idx,
1209                         struct page **pagep, enum sgp_type sgp, int *type)
1210 {
1211         struct address_space *mapping = inode->i_mapping;
1212         struct shmem_inode_info *info = SHMEM_I(inode);
1213         struct shmem_sb_info *sbinfo;
1214         struct page *filepage = *pagep;
1215         struct page *swappage;
1216         swp_entry_t *entry;
1217         swp_entry_t swap;
1218         gfp_t gfp;
1219         int error;
1220
1221         if (idx >= SHMEM_MAX_INDEX)
1222                 return -EFBIG;
1223
1224         if (type)
1225                 *type = 0;
1226
1227         /*
1228          * Normally, filepage is NULL on entry, and either found
1229          * uptodate immediately, or allocated and zeroed, or read
1230          * in under swappage, which is then assigned to filepage.
1231          * But shmem_readpage (required for splice) passes in a locked
1232          * filepage, which may be found not uptodate by other callers
1233          * too, and may need to be copied from the swappage read in.
1234          */
1235 repeat:
1236         if (!filepage)
1237                 filepage = find_lock_page(mapping, idx);
1238         if (filepage && PageUptodate(filepage))
1239                 goto done;
1240         error = 0;
1241         gfp = mapping_gfp_mask(mapping);
1242         if (!filepage) {
1243                 /*
1244                  * Try to preload while we can wait, to not make a habit of
1245                  * draining atomic reserves; but don't latch on to this cpu.
1246                  */
1247                 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1248                 if (error)
1249                         goto failed;
1250                 radix_tree_preload_end();
1251         }
1252
1253         spin_lock(&info->lock);
1254         shmem_recalc_inode(inode);
1255         entry = shmem_swp_alloc(info, idx, sgp);
1256         if (IS_ERR(entry)) {
1257                 spin_unlock(&info->lock);
1258                 error = PTR_ERR(entry);
1259                 goto failed;
1260         }
1261         swap = *entry;
1262
1263         if (swap.val) {
1264                 /* Look it up and read it in.. */
1265                 swappage = lookup_swap_cache(swap);
1266                 if (!swappage) {
1267                         shmem_swp_unmap(entry);
1268                         /* here we actually do the io */
1269                         if (type && !(*type & VM_FAULT_MAJOR)) {
1270                                 __count_vm_event(PGMAJFAULT);
1271                                 *type |= VM_FAULT_MAJOR;
1272                         }
1273                         spin_unlock(&info->lock);
1274                         swappage = shmem_swapin(swap, gfp, info, idx);
1275                         if (!swappage) {
1276                                 spin_lock(&info->lock);
1277                                 entry = shmem_swp_alloc(info, idx, sgp);
1278                                 if (IS_ERR(entry))
1279                                         error = PTR_ERR(entry);
1280                                 else {
1281                                         if (entry->val == swap.val)
1282                                                 error = -ENOMEM;
1283                                         shmem_swp_unmap(entry);
1284                                 }
1285                                 spin_unlock(&info->lock);
1286                                 if (error)
1287                                         goto failed;
1288                                 goto repeat;
1289                         }
1290                         wait_on_page_locked(swappage);
1291                         page_cache_release(swappage);
1292                         goto repeat;
1293                 }
1294
1295                 /* We have to do this with page locked to prevent races */
1296                 if (!trylock_page(swappage)) {
1297                         shmem_swp_unmap(entry);
1298                         spin_unlock(&info->lock);
1299                         wait_on_page_locked(swappage);
1300                         page_cache_release(swappage);
1301                         goto repeat;
1302                 }
1303                 if (PageWriteback(swappage)) {
1304                         shmem_swp_unmap(entry);
1305                         spin_unlock(&info->lock);
1306                         wait_on_page_writeback(swappage);
1307                         unlock_page(swappage);
1308                         page_cache_release(swappage);
1309                         goto repeat;
1310                 }
1311                 if (!PageUptodate(swappage)) {
1312                         shmem_swp_unmap(entry);
1313                         spin_unlock(&info->lock);
1314                         unlock_page(swappage);
1315                         page_cache_release(swappage);
1316                         error = -EIO;
1317                         goto failed;
1318                 }
1319
1320                 if (filepage) {
1321                         shmem_swp_set(info, entry, 0);
1322                         shmem_swp_unmap(entry);
1323                         delete_from_swap_cache(swappage);
1324                         spin_unlock(&info->lock);
1325                         copy_highpage(filepage, swappage);
1326                         unlock_page(swappage);
1327                         page_cache_release(swappage);
1328                         flush_dcache_page(filepage);
1329                         SetPageUptodate(filepage);
1330                         set_page_dirty(filepage);
1331                         swap_free(swap);
1332                 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1333                                         idx, GFP_NOWAIT))) {
1334                         info->flags |= SHMEM_PAGEIN;
1335                         shmem_swp_set(info, entry, 0);
1336                         shmem_swp_unmap(entry);
1337                         delete_from_swap_cache(swappage);
1338                         spin_unlock(&info->lock);
1339                         filepage = swappage;
1340                         set_page_dirty(filepage);
1341                         swap_free(swap);
1342                 } else {
1343                         shmem_swp_unmap(entry);
1344                         spin_unlock(&info->lock);
1345                         if (error == -ENOMEM) {
1346                                 /*
1347                                  * reclaim from proper memory cgroup and
1348                                  * call memcg's OOM if needed.
1349                                  */
1350                                 error = mem_cgroup_shmem_charge_fallback(
1351                                                                 swappage,
1352                                                                 current->mm,
1353                                                                 gfp);
1354                                 if (error) {
1355                                         unlock_page(swappage);
1356                                         page_cache_release(swappage);
1357                                         goto failed;
1358                                 }
1359                         }
1360                         unlock_page(swappage);
1361                         page_cache_release(swappage);
1362                         goto repeat;
1363                 }
1364         } else if (sgp == SGP_READ && !filepage) {
1365                 shmem_swp_unmap(entry);
1366                 filepage = find_get_page(mapping, idx);
1367                 if (filepage &&
1368                     (!PageUptodate(filepage) || !trylock_page(filepage))) {
1369                         spin_unlock(&info->lock);
1370                         wait_on_page_locked(filepage);
1371                         page_cache_release(filepage);
1372                         filepage = NULL;
1373                         goto repeat;
1374                 }
1375                 spin_unlock(&info->lock);
1376         } else {
1377                 shmem_swp_unmap(entry);
1378                 sbinfo = SHMEM_SB(inode->i_sb);
1379                 if (sbinfo->max_blocks) {
1380                         spin_lock(&sbinfo->stat_lock);
1381                         if (sbinfo->free_blocks == 0 ||
1382                             shmem_acct_block(info->flags)) {
1383                                 spin_unlock(&sbinfo->stat_lock);
1384                                 spin_unlock(&info->lock);
1385                                 error = -ENOSPC;
1386                                 goto failed;
1387                         }
1388                         sbinfo->free_blocks--;
1389                         inode->i_blocks += BLOCKS_PER_PAGE;
1390                         spin_unlock(&sbinfo->stat_lock);
1391                 } else if (shmem_acct_block(info->flags)) {
1392                         spin_unlock(&info->lock);
1393                         error = -ENOSPC;
1394                         goto failed;
1395                 }
1396
1397                 if (!filepage) {
1398                         int ret;
1399
1400                         spin_unlock(&info->lock);
1401                         filepage = shmem_alloc_page(gfp, info, idx);
1402                         if (!filepage) {
1403                                 shmem_unacct_blocks(info->flags, 1);
1404                                 shmem_free_blocks(inode, 1);
1405                                 error = -ENOMEM;
1406                                 goto failed;
1407                         }
1408                         SetPageSwapBacked(filepage);
1409
1410                         /* Precharge page while we can wait, compensate after */
1411                         error = mem_cgroup_cache_charge(filepage, current->mm,
1412                                         GFP_KERNEL);
1413                         if (error) {
1414                                 page_cache_release(filepage);
1415                                 shmem_unacct_blocks(info->flags, 1);
1416                                 shmem_free_blocks(inode, 1);
1417                                 filepage = NULL;
1418                                 goto failed;
1419                         }
1420
1421                         spin_lock(&info->lock);
1422                         entry = shmem_swp_alloc(info, idx, sgp);
1423                         if (IS_ERR(entry))
1424                                 error = PTR_ERR(entry);
1425                         else {
1426                                 swap = *entry;
1427                                 shmem_swp_unmap(entry);
1428                         }
1429                         ret = error || swap.val;
1430                         if (ret)
1431                                 mem_cgroup_uncharge_cache_page(filepage);
1432                         else
1433                                 ret = add_to_page_cache_lru(filepage, mapping,
1434                                                 idx, GFP_NOWAIT);
1435                         /*
1436                          * At add_to_page_cache_lru() failure, uncharge will
1437                          * be done automatically.
1438                          */
1439                         if (ret) {
1440                                 spin_unlock(&info->lock);
1441                                 page_cache_release(filepage);
1442                                 shmem_unacct_blocks(info->flags, 1);
1443                                 shmem_free_blocks(inode, 1);
1444                                 filepage = NULL;
1445                                 if (error)
1446                                         goto failed;
1447                                 goto repeat;
1448                         }
1449                         info->flags |= SHMEM_PAGEIN;
1450                 }
1451
1452                 info->alloced++;
1453                 spin_unlock(&info->lock);
1454                 clear_highpage(filepage);
1455                 flush_dcache_page(filepage);
1456                 SetPageUptodate(filepage);
1457                 if (sgp == SGP_DIRTY)
1458                         set_page_dirty(filepage);
1459         }
1460 done:
1461         *pagep = filepage;
1462         return 0;
1463
1464 failed:
1465         if (*pagep != filepage) {
1466                 unlock_page(filepage);
1467                 page_cache_release(filepage);
1468         }
1469         return error;
1470 }
1471
1472 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1473 {
1474         struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1475         int error;
1476         int ret;
1477
1478         if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1479                 return VM_FAULT_SIGBUS;
1480
1481         error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1482         if (error)
1483                 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1484
1485         return ret | VM_FAULT_LOCKED;
1486 }
1487
1488 #ifdef CONFIG_NUMA
1489 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1490 {
1491         struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1492         return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1493 }
1494
1495 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1496                                           unsigned long addr)
1497 {
1498         struct inode *i = vma->vm_file->f_path.dentry->d_inode;
1499         unsigned long idx;
1500
1501         idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1502         return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1503 }
1504 #endif
1505
1506 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1507 {
1508         struct inode *inode = file->f_path.dentry->d_inode;
1509         struct shmem_inode_info *info = SHMEM_I(inode);
1510         int retval = -ENOMEM;
1511
1512         spin_lock(&info->lock);
1513         if (lock && !(info->flags & VM_LOCKED)) {
1514                 if (!user_shm_lock(inode->i_size, user))
1515                         goto out_nomem;
1516                 info->flags |= VM_LOCKED;
1517                 mapping_set_unevictable(file->f_mapping);
1518         }
1519         if (!lock && (info->flags & VM_LOCKED) && user) {
1520                 user_shm_unlock(inode->i_size, user);
1521                 info->flags &= ~VM_LOCKED;
1522                 mapping_clear_unevictable(file->f_mapping);
1523                 scan_mapping_unevictable_pages(file->f_mapping);
1524         }
1525         retval = 0;
1526
1527 out_nomem:
1528         spin_unlock(&info->lock);
1529         return retval;
1530 }
1531
1532 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1533 {
1534         file_accessed(file);
1535         vma->vm_ops = &shmem_vm_ops;
1536         vma->vm_flags |= VM_CAN_NONLINEAR;
1537         return 0;
1538 }
1539
1540 static struct inode *shmem_get_inode(struct super_block *sb, int mode,
1541                                         dev_t dev, unsigned long flags)
1542 {
1543         struct inode *inode;
1544         struct shmem_inode_info *info;
1545         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1546
1547         if (shmem_reserve_inode(sb))
1548                 return NULL;
1549
1550         inode = new_inode(sb);
1551         if (inode) {
1552                 inode->i_mode = mode;
1553                 inode->i_uid = current_fsuid();
1554                 inode->i_gid = current_fsgid();
1555                 inode->i_blocks = 0;
1556                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1557                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1558                 inode->i_generation = get_seconds();
1559                 info = SHMEM_I(inode);
1560                 memset(info, 0, (char *)inode - (char *)info);
1561                 spin_lock_init(&info->lock);
1562                 info->flags = flags & VM_NORESERVE;
1563                 INIT_LIST_HEAD(&info->swaplist);
1564                 cache_no_acl(inode);
1565
1566                 switch (mode & S_IFMT) {
1567                 default:
1568                         inode->i_op = &shmem_special_inode_operations;
1569                         init_special_inode(inode, mode, dev);
1570                         break;
1571                 case S_IFREG:
1572                         inode->i_mapping->a_ops = &shmem_aops;
1573                         inode->i_op = &shmem_inode_operations;
1574                         inode->i_fop = &shmem_file_operations;
1575                         mpol_shared_policy_init(&info->policy,
1576                                                  shmem_get_sbmpol(sbinfo));
1577                         break;
1578                 case S_IFDIR:
1579                         inc_nlink(inode);
1580                         /* Some things misbehave if size == 0 on a directory */
1581                         inode->i_size = 2 * BOGO_DIRENT_SIZE;
1582                         inode->i_op = &shmem_dir_inode_operations;
1583                         inode->i_fop = &simple_dir_operations;
1584                         break;
1585                 case S_IFLNK:
1586                         /*
1587                          * Must not load anything in the rbtree,
1588                          * mpol_free_shared_policy will not be called.
1589                          */
1590                         mpol_shared_policy_init(&info->policy, NULL);
1591                         break;
1592                 }
1593         } else
1594                 shmem_free_inode(sb);
1595         return inode;
1596 }
1597
1598 #ifdef CONFIG_TMPFS
1599 static const struct inode_operations shmem_symlink_inode_operations;
1600 static const struct inode_operations shmem_symlink_inline_operations;
1601
1602 /*
1603  * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1604  * but providing them allows a tmpfs file to be used for splice, sendfile, and
1605  * below the loop driver, in the generic fashion that many filesystems support.
1606  */
1607 static int shmem_readpage(struct file *file, struct page *page)
1608 {
1609         struct inode *inode = page->mapping->host;
1610         int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1611         unlock_page(page);
1612         return error;
1613 }
1614
1615 static int
1616 shmem_write_begin(struct file *file, struct address_space *mapping,
1617                         loff_t pos, unsigned len, unsigned flags,
1618                         struct page **pagep, void **fsdata)
1619 {
1620         struct inode *inode = mapping->host;
1621         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1622         *pagep = NULL;
1623         return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1624 }
1625
1626 static int
1627 shmem_write_end(struct file *file, struct address_space *mapping,
1628                         loff_t pos, unsigned len, unsigned copied,
1629                         struct page *page, void *fsdata)
1630 {
1631         struct inode *inode = mapping->host;
1632
1633         if (pos + copied > inode->i_size)
1634                 i_size_write(inode, pos + copied);
1635
1636         set_page_dirty(page);
1637         unlock_page(page);
1638         page_cache_release(page);
1639
1640         return copied;
1641 }
1642
1643 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1644 {
1645         struct inode *inode = filp->f_path.dentry->d_inode;
1646         struct address_space *mapping = inode->i_mapping;
1647         unsigned long index, offset;
1648         enum sgp_type sgp = SGP_READ;
1649
1650         /*
1651          * Might this read be for a stacking filesystem?  Then when reading
1652          * holes of a sparse file, we actually need to allocate those pages,
1653          * and even mark them dirty, so it cannot exceed the max_blocks limit.
1654          */
1655         if (segment_eq(get_fs(), KERNEL_DS))
1656                 sgp = SGP_DIRTY;
1657
1658         index = *ppos >> PAGE_CACHE_SHIFT;
1659         offset = *ppos & ~PAGE_CACHE_MASK;
1660
1661         for (;;) {
1662                 struct page *page = NULL;
1663                 unsigned long end_index, nr, ret;
1664                 loff_t i_size = i_size_read(inode);
1665
1666                 end_index = i_size >> PAGE_CACHE_SHIFT;
1667                 if (index > end_index)
1668                         break;
1669                 if (index == end_index) {
1670                         nr = i_size & ~PAGE_CACHE_MASK;
1671                         if (nr <= offset)
1672                                 break;
1673                 }
1674
1675                 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1676                 if (desc->error) {
1677                         if (desc->error == -EINVAL)
1678                                 desc->error = 0;
1679                         break;
1680                 }
1681                 if (page)
1682                         unlock_page(page);
1683
1684                 /*
1685                  * We must evaluate after, since reads (unlike writes)
1686                  * are called without i_mutex protection against truncate
1687                  */
1688                 nr = PAGE_CACHE_SIZE;
1689                 i_size = i_size_read(inode);
1690                 end_index = i_size >> PAGE_CACHE_SHIFT;
1691                 if (index == end_index) {
1692                         nr = i_size & ~PAGE_CACHE_MASK;
1693                         if (nr <= offset) {
1694                                 if (page)
1695                                         page_cache_release(page);
1696                                 break;
1697                         }
1698                 }
1699                 nr -= offset;
1700
1701                 if (page) {
1702                         /*
1703                          * If users can be writing to this page using arbitrary
1704                          * virtual addresses, take care about potential aliasing
1705                          * before reading the page on the kernel side.
1706                          */
1707                         if (mapping_writably_mapped(mapping))
1708                                 flush_dcache_page(page);
1709                         /*
1710                          * Mark the page accessed if we read the beginning.
1711                          */
1712                         if (!offset)
1713                                 mark_page_accessed(page);
1714                 } else {
1715                         page = ZERO_PAGE(0);
1716                         page_cache_get(page);
1717                 }
1718
1719                 /*
1720                  * Ok, we have the page, and it's up-to-date, so
1721                  * now we can copy it to user space...
1722                  *
1723                  * The actor routine returns how many bytes were actually used..
1724                  * NOTE! This may not be the same as how much of a user buffer
1725                  * we filled up (we may be padding etc), so we can only update
1726                  * "pos" here (the actor routine has to update the user buffer
1727                  * pointers and the remaining count).
1728                  */
1729                 ret = actor(desc, page, offset, nr);
1730                 offset += ret;
1731                 index += offset >> PAGE_CACHE_SHIFT;
1732                 offset &= ~PAGE_CACHE_MASK;
1733
1734                 page_cache_release(page);
1735                 if (ret != nr || !desc->count)
1736                         break;
1737
1738                 cond_resched();
1739         }
1740
1741         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1742         file_accessed(filp);
1743 }
1744
1745 static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1746                 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1747 {
1748         struct file *filp = iocb->ki_filp;
1749         ssize_t retval;
1750         unsigned long seg;
1751         size_t count;
1752         loff_t *ppos = &iocb->ki_pos;
1753
1754         retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1755         if (retval)
1756                 return retval;
1757
1758         for (seg = 0; seg < nr_segs; seg++) {
1759                 read_descriptor_t desc;
1760
1761                 desc.written = 0;
1762                 desc.arg.buf = iov[seg].iov_base;
1763                 desc.count = iov[seg].iov_len;
1764                 if (desc.count == 0)
1765                         continue;
1766                 desc.error = 0;
1767                 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1768                 retval += desc.written;
1769                 if (desc.error) {
1770                         retval = retval ?: desc.error;
1771                         break;
1772                 }
1773                 if (desc.count > 0)
1774                         break;
1775         }
1776         return retval;
1777 }
1778
1779 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1780 {
1781         struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1782
1783         buf->f_type = TMPFS_MAGIC;
1784         buf->f_bsize = PAGE_CACHE_SIZE;
1785         buf->f_namelen = NAME_MAX;
1786         spin_lock(&sbinfo->stat_lock);
1787         if (sbinfo->max_blocks) {
1788                 buf->f_blocks = sbinfo->max_blocks;
1789                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1790         }
1791         if (sbinfo->max_inodes) {
1792                 buf->f_files = sbinfo->max_inodes;
1793                 buf->f_ffree = sbinfo->free_inodes;
1794         }
1795         /* else leave those fields 0 like simple_statfs */
1796         spin_unlock(&sbinfo->stat_lock);
1797         return 0;
1798 }
1799
1800 /*
1801  * File creation. Allocate an inode, and we're done..
1802  */
1803 static int
1804 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1805 {
1806         struct inode *inode;
1807         int error = -ENOSPC;
1808
1809         inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE);
1810         if (inode) {
1811                 error = security_inode_init_security(inode, dir, NULL, NULL,
1812                                                      NULL);
1813                 if (error) {
1814                         if (error != -EOPNOTSUPP) {
1815                                 iput(inode);
1816                                 return error;
1817                         }
1818                 }
1819                 error = shmem_acl_init(inode, dir);
1820                 if (error) {
1821                         iput(inode);
1822                         return error;
1823                 }
1824                 if (dir->i_mode & S_ISGID) {
1825                         inode->i_gid = dir->i_gid;
1826                         if (S_ISDIR(mode))
1827                                 inode->i_mode |= S_ISGID;
1828                 }
1829                 dir->i_size += BOGO_DIRENT_SIZE;
1830                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1831                 d_instantiate(dentry, inode);
1832                 dget(dentry); /* Extra count - pin the dentry in core */
1833         }
1834         return error;
1835 }
1836
1837 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1838 {
1839         int error;
1840
1841         if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1842                 return error;
1843         inc_nlink(dir);
1844         return 0;
1845 }
1846
1847 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1848                 struct nameidata *nd)
1849 {
1850         return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1851 }
1852
1853 /*
1854  * Link a file..
1855  */
1856 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1857 {
1858         struct inode *inode = old_dentry->d_inode;
1859         int ret;
1860
1861         /*
1862          * No ordinary (disk based) filesystem counts links as inodes;
1863          * but each new link needs a new dentry, pinning lowmem, and
1864          * tmpfs dentries cannot be pruned until they are unlinked.
1865          */
1866         ret = shmem_reserve_inode(inode->i_sb);
1867         if (ret)
1868                 goto out;
1869
1870         dir->i_size += BOGO_DIRENT_SIZE;
1871         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1872         inc_nlink(inode);
1873         atomic_inc(&inode->i_count);    /* New dentry reference */
1874         dget(dentry);           /* Extra pinning count for the created dentry */
1875         d_instantiate(dentry, inode);
1876 out:
1877         return ret;
1878 }
1879
1880 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1881 {
1882         struct inode *inode = dentry->d_inode;
1883
1884         if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1885                 shmem_free_inode(inode->i_sb);
1886
1887         dir->i_size -= BOGO_DIRENT_SIZE;
1888         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1889         drop_nlink(inode);
1890         dput(dentry);   /* Undo the count from "create" - this does all the work */
1891         return 0;
1892 }
1893
1894 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1895 {
1896         if (!simple_empty(dentry))
1897                 return -ENOTEMPTY;
1898
1899         drop_nlink(dentry->d_inode);
1900         drop_nlink(dir);
1901         return shmem_unlink(dir, dentry);
1902 }
1903
1904 /*
1905  * The VFS layer already does all the dentry stuff for rename,
1906  * we just have to decrement the usage count for the target if
1907  * it exists so that the VFS layer correctly free's it when it
1908  * gets overwritten.
1909  */
1910 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1911 {
1912         struct inode *inode = old_dentry->d_inode;
1913         int they_are_dirs = S_ISDIR(inode->i_mode);
1914
1915         if (!simple_empty(new_dentry))
1916                 return -ENOTEMPTY;
1917
1918         if (new_dentry->d_inode) {
1919                 (void) shmem_unlink(new_dir, new_dentry);
1920                 if (they_are_dirs)
1921                         drop_nlink(old_dir);
1922         } else if (they_are_dirs) {
1923                 drop_nlink(old_dir);
1924                 inc_nlink(new_dir);
1925         }
1926
1927         old_dir->i_size -= BOGO_DIRENT_SIZE;
1928         new_dir->i_size += BOGO_DIRENT_SIZE;
1929         old_dir->i_ctime = old_dir->i_mtime =
1930         new_dir->i_ctime = new_dir->i_mtime =
1931         inode->i_ctime = CURRENT_TIME;
1932         return 0;
1933 }
1934
1935 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1936 {
1937         int error;
1938         int len;
1939         struct inode *inode;
1940         struct page *page = NULL;
1941         char *kaddr;
1942         struct shmem_inode_info *info;
1943
1944         len = strlen(symname) + 1;
1945         if (len > PAGE_CACHE_SIZE)
1946                 return -ENAMETOOLONG;
1947
1948         inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
1949         if (!inode)
1950                 return -ENOSPC;
1951
1952         error = security_inode_init_security(inode, dir, NULL, NULL,
1953                                              NULL);
1954         if (error) {
1955                 if (error != -EOPNOTSUPP) {
1956                         iput(inode);
1957                         return error;
1958                 }
1959                 error = 0;
1960         }
1961
1962         info = SHMEM_I(inode);
1963         inode->i_size = len-1;
1964         if (len <= (char *)inode - (char *)info) {
1965                 /* do it inline */
1966                 memcpy(info, symname, len);
1967                 inode->i_op = &shmem_symlink_inline_operations;
1968         } else {
1969                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1970                 if (error) {
1971                         iput(inode);
1972                         return error;
1973                 }
1974                 inode->i_mapping->a_ops = &shmem_aops;
1975                 inode->i_op = &shmem_symlink_inode_operations;
1976                 kaddr = kmap_atomic(page, KM_USER0);
1977                 memcpy(kaddr, symname, len);
1978                 kunmap_atomic(kaddr, KM_USER0);
1979                 set_page_dirty(page);
1980                 unlock_page(page);
1981                 page_cache_release(page);
1982         }
1983         if (dir->i_mode & S_ISGID)
1984                 inode->i_gid = dir->i_gid;
1985         dir->i_size += BOGO_DIRENT_SIZE;
1986         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1987         d_instantiate(dentry, inode);
1988         dget(dentry);
1989         return 0;
1990 }
1991
1992 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1993 {
1994         nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1995         return NULL;
1996 }
1997
1998 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1999 {
2000         struct page *page = NULL;
2001         int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2002         nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
2003         if (page)
2004                 unlock_page(page);
2005         return page;
2006 }
2007
2008 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2009 {
2010         if (!IS_ERR(nd_get_link(nd))) {
2011                 struct page *page = cookie;
2012                 kunmap(page);
2013                 mark_page_accessed(page);
2014                 page_cache_release(page);
2015         }
2016 }
2017
2018 static const struct inode_operations shmem_symlink_inline_operations = {
2019         .readlink       = generic_readlink,
2020         .follow_link    = shmem_follow_link_inline,
2021 };
2022
2023 static const struct inode_operations shmem_symlink_inode_operations = {
2024         .truncate       = shmem_truncate,
2025         .readlink       = generic_readlink,
2026         .follow_link    = shmem_follow_link,
2027         .put_link       = shmem_put_link,
2028 };
2029
2030 #ifdef CONFIG_TMPFS_POSIX_ACL
2031 /*
2032  * Superblocks without xattr inode operations will get security.* xattr
2033  * support from the VFS "for free". As soon as we have any other xattrs
2034  * like ACLs, we also need to implement the security.* handlers at
2035  * filesystem level, though.
2036  */
2037
2038 static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2039                                         size_t list_len, const char *name,
2040                                         size_t name_len)
2041 {
2042         return security_inode_listsecurity(inode, list, list_len);
2043 }
2044
2045 static int shmem_xattr_security_get(struct inode *inode, const char *name,
2046                                     void *buffer, size_t size)
2047 {
2048         if (strcmp(name, "") == 0)
2049                 return -EINVAL;
2050         return xattr_getsecurity(inode, name, buffer, size);
2051 }
2052
2053 static int shmem_xattr_security_set(struct inode *inode, const char *name,
2054                                     const void *value, size_t size, int flags)
2055 {
2056         if (strcmp(name, "") == 0)
2057                 return -EINVAL;
2058         return security_inode_setsecurity(inode, name, value, size, flags);
2059 }
2060
2061 static struct xattr_handler shmem_xattr_security_handler = {
2062         .prefix = XATTR_SECURITY_PREFIX,
2063         .list   = shmem_xattr_security_list,
2064         .get    = shmem_xattr_security_get,
2065         .set    = shmem_xattr_security_set,
2066 };
2067
2068 static struct xattr_handler *shmem_xattr_handlers[] = {
2069         &shmem_xattr_acl_access_handler,
2070         &shmem_xattr_acl_default_handler,
2071         &shmem_xattr_security_handler,
2072         NULL
2073 };
2074 #endif
2075
2076 static struct dentry *shmem_get_parent(struct dentry *child)
2077 {
2078         return ERR_PTR(-ESTALE);
2079 }
2080
2081 static int shmem_match(struct inode *ino, void *vfh)
2082 {
2083         __u32 *fh = vfh;
2084         __u64 inum = fh[2];
2085         inum = (inum << 32) | fh[1];
2086         return ino->i_ino == inum && fh[0] == ino->i_generation;
2087 }
2088
2089 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2090                 struct fid *fid, int fh_len, int fh_type)
2091 {
2092         struct inode *inode;
2093         struct dentry *dentry = NULL;
2094         u64 inum = fid->raw[2];
2095         inum = (inum << 32) | fid->raw[1];
2096
2097         if (fh_len < 3)
2098                 return NULL;
2099
2100         inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2101                         shmem_match, fid->raw);
2102         if (inode) {
2103                 dentry = d_find_alias(inode);
2104                 iput(inode);
2105         }
2106
2107         return dentry;
2108 }
2109
2110 static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2111                                 int connectable)
2112 {
2113         struct inode *inode = dentry->d_inode;
2114
2115         if (*len < 3)
2116                 return 255;
2117
2118         if (hlist_unhashed(&inode->i_hash)) {
2119                 /* Unfortunately insert_inode_hash is not idempotent,
2120                  * so as we hash inodes here rather than at creation
2121                  * time, we need a lock to ensure we only try
2122                  * to do it once
2123                  */
2124                 static DEFINE_SPINLOCK(lock);
2125                 spin_lock(&lock);
2126                 if (hlist_unhashed(&inode->i_hash))
2127                         __insert_inode_hash(inode,
2128                                             inode->i_ino + inode->i_generation);
2129                 spin_unlock(&lock);
2130         }
2131
2132         fh[0] = inode->i_generation;
2133         fh[1] = inode->i_ino;
2134         fh[2] = ((__u64)inode->i_ino) >> 32;
2135
2136         *len = 3;
2137         return 1;
2138 }
2139
2140 static const struct export_operations shmem_export_ops = {
2141         .get_parent     = shmem_get_parent,
2142         .encode_fh      = shmem_encode_fh,
2143         .fh_to_dentry   = shmem_fh_to_dentry,
2144 };
2145
2146 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2147                                bool remount)
2148 {
2149         char *this_char, *value, *rest;
2150
2151         while (options != NULL) {
2152                 this_char = options;
2153                 for (;;) {
2154                         /*
2155                          * NUL-terminate this option: unfortunately,
2156                          * mount options form a comma-separated list,
2157                          * but mpol's nodelist may also contain commas.
2158                          */
2159                         options = strchr(options, ',');
2160                         if (options == NULL)
2161                                 break;
2162                         options++;
2163                         if (!isdigit(*options)) {
2164                                 options[-1] = '\0';
2165                                 break;
2166                         }
2167                 }
2168                 if (!*this_char)
2169                         continue;
2170                 if ((value = strchr(this_char,'=')) != NULL) {
2171                         *value++ = 0;
2172                 } else {
2173                         printk(KERN_ERR
2174                             "tmpfs: No value for mount option '%s'\n",
2175                             this_char);
2176                         return 1;
2177                 }
2178
2179                 if (!strcmp(this_char,"size")) {
2180                         unsigned long long size;
2181                         size = memparse(value,&rest);
2182                         if (*rest == '%') {
2183                                 size <<= PAGE_SHIFT;
2184                                 size *= totalram_pages;
2185                                 do_div(size, 100);
2186                                 rest++;
2187                         }
2188                         if (*rest)
2189                                 goto bad_val;
2190                         sbinfo->max_blocks =
2191                                 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2192                 } else if (!strcmp(this_char,"nr_blocks")) {
2193                         sbinfo->max_blocks = memparse(value, &rest);
2194                         if (*rest)
2195                                 goto bad_val;
2196                 } else if (!strcmp(this_char,"nr_inodes")) {
2197                         sbinfo->max_inodes = memparse(value, &rest);
2198                         if (*rest)
2199                                 goto bad_val;
2200                 } else if (!strcmp(this_char,"mode")) {
2201                         if (remount)
2202                                 continue;
2203                         sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2204                         if (*rest)
2205                                 goto bad_val;
2206                 } else if (!strcmp(this_char,"uid")) {
2207                         if (remount)
2208                                 continue;
2209                         sbinfo->uid = simple_strtoul(value, &rest, 0);
2210                         if (*rest)
2211                                 goto bad_val;
2212                 } else if (!strcmp(this_char,"gid")) {
2213                         if (remount)
2214                                 continue;
2215                         sbinfo->gid = simple_strtoul(value, &rest, 0);
2216                         if (*rest)
2217                                 goto bad_val;
2218                 } else if (!strcmp(this_char,"mpol")) {
2219                         if (mpol_parse_str(value, &sbinfo->mpol, 1))
2220                                 goto bad_val;
2221                 } else {
2222                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2223                                this_char);
2224                         return 1;
2225                 }
2226         }
2227         return 0;
2228
2229 bad_val:
2230         printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2231                value, this_char);
2232         return 1;
2233
2234 }
2235
2236 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2237 {
2238         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2239         struct shmem_sb_info config = *sbinfo;
2240         unsigned long blocks;
2241         unsigned long inodes;
2242         int error = -EINVAL;
2243
2244         if (shmem_parse_options(data, &config, true))
2245                 return error;
2246
2247         spin_lock(&sbinfo->stat_lock);
2248         blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2249         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2250         if (config.max_blocks < blocks)
2251                 goto out;
2252         if (config.max_inodes < inodes)
2253                 goto out;
2254         /*
2255          * Those tests also disallow limited->unlimited while any are in
2256          * use, so i_blocks will always be zero when max_blocks is zero;
2257          * but we must separately disallow unlimited->limited, because
2258          * in that case we have no record of how much is already in use.
2259          */
2260         if (config.max_blocks && !sbinfo->max_blocks)
2261                 goto out;
2262         if (config.max_inodes && !sbinfo->max_inodes)
2263                 goto out;
2264
2265         error = 0;
2266         sbinfo->max_blocks  = config.max_blocks;
2267         sbinfo->free_blocks = config.max_blocks - blocks;
2268         sbinfo->max_inodes  = config.max_inodes;
2269         sbinfo->free_inodes = config.max_inodes - inodes;
2270
2271         mpol_put(sbinfo->mpol);
2272         sbinfo->mpol        = config.mpol;      /* transfers initial ref */
2273 out:
2274         spin_unlock(&sbinfo->stat_lock);
2275         return error;
2276 }
2277
2278 static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2279 {
2280         struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2281
2282         if (sbinfo->max_blocks != shmem_default_max_blocks())
2283                 seq_printf(seq, ",size=%luk",
2284                         sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2285         if (sbinfo->max_inodes != shmem_default_max_inodes())
2286                 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2287         if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2288                 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2289         if (sbinfo->uid != 0)
2290                 seq_printf(seq, ",uid=%u", sbinfo->uid);
2291         if (sbinfo->gid != 0)
2292                 seq_printf(seq, ",gid=%u", sbinfo->gid);
2293         shmem_show_mpol(seq, sbinfo->mpol);
2294         return 0;
2295 }
2296 #endif /* CONFIG_TMPFS */
2297
2298 static void shmem_put_super(struct super_block *sb)
2299 {
2300         kfree(sb->s_fs_info);
2301         sb->s_fs_info = NULL;
2302 }
2303
2304 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2305 {
2306         struct inode *inode;
2307         struct dentry *root;
2308         struct shmem_sb_info *sbinfo;
2309         int err = -ENOMEM;
2310
2311         /* Round up to L1_CACHE_BYTES to resist false sharing */
2312         sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2313                                 L1_CACHE_BYTES), GFP_KERNEL);
2314         if (!sbinfo)
2315                 return -ENOMEM;
2316
2317         sbinfo->mode = S_IRWXUGO | S_ISVTX;
2318         sbinfo->uid = current_fsuid();
2319         sbinfo->gid = current_fsgid();
2320         sb->s_fs_info = sbinfo;
2321
2322 #ifdef CONFIG_TMPFS
2323         /*
2324          * Per default we only allow half of the physical ram per
2325          * tmpfs instance, limiting inodes to one per page of lowmem;
2326          * but the internal instance is left unlimited.
2327          */
2328         if (!(sb->s_flags & MS_NOUSER)) {
2329                 sbinfo->max_blocks = shmem_default_max_blocks();
2330                 sbinfo->max_inodes = shmem_default_max_inodes();
2331                 if (shmem_parse_options(data, sbinfo, false)) {
2332                         err = -EINVAL;
2333                         goto failed;
2334                 }
2335         }
2336         sb->s_export_op = &shmem_export_ops;
2337 #else
2338         sb->s_flags |= MS_NOUSER;
2339 #endif
2340
2341         spin_lock_init(&sbinfo->stat_lock);
2342         sbinfo->free_blocks = sbinfo->max_blocks;
2343         sbinfo->free_inodes = sbinfo->max_inodes;
2344
2345         sb->s_maxbytes = SHMEM_MAX_BYTES;
2346         sb->s_blocksize = PAGE_CACHE_SIZE;
2347         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2348         sb->s_magic = TMPFS_MAGIC;
2349         sb->s_op = &shmem_ops;
2350         sb->s_time_gran = 1;
2351 #ifdef CONFIG_TMPFS_POSIX_ACL
2352         sb->s_xattr = shmem_xattr_handlers;
2353         sb->s_flags |= MS_POSIXACL;
2354 #endif
2355
2356         inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2357         if (!inode)
2358                 goto failed;
2359         inode->i_uid = sbinfo->uid;
2360         inode->i_gid = sbinfo->gid;
2361         root = d_alloc_root(inode);
2362         if (!root)
2363                 goto failed_iput;
2364         sb->s_root = root;
2365         return 0;
2366
2367 failed_iput:
2368         iput(inode);
2369 failed:
2370         shmem_put_super(sb);
2371         return err;
2372 }
2373
2374 static struct kmem_cache *shmem_inode_cachep;
2375
2376 static struct inode *shmem_alloc_inode(struct super_block *sb)
2377 {
2378         struct shmem_inode_info *p;
2379         p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2380         if (!p)
2381                 return NULL;
2382         return &p->vfs_inode;
2383 }
2384
2385 static void shmem_destroy_inode(struct inode *inode)
2386 {
2387         if ((inode->i_mode & S_IFMT) == S_IFREG) {
2388                 /* only struct inode is valid if it's an inline symlink */
2389                 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2390         }
2391         kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2392 }
2393
2394 static void init_once(void *foo)
2395 {
2396         struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2397
2398         inode_init_once(&p->vfs_inode);
2399 }
2400
2401 static int init_inodecache(void)
2402 {
2403         shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2404                                 sizeof(struct shmem_inode_info),
2405                                 0, SLAB_PANIC, init_once);
2406         return 0;
2407 }
2408
2409 static void destroy_inodecache(void)
2410 {
2411         kmem_cache_destroy(shmem_inode_cachep);
2412 }
2413
2414 static const struct address_space_operations shmem_aops = {
2415         .writepage      = shmem_writepage,
2416         .set_page_dirty = __set_page_dirty_no_writeback,
2417 #ifdef CONFIG_TMPFS
2418         .readpage       = shmem_readpage,
2419         .write_begin    = shmem_write_begin,
2420         .write_end      = shmem_write_end,
2421 #endif
2422         .migratepage    = migrate_page,
2423         .error_remove_page = generic_error_remove_page,
2424 };
2425
2426 static const struct file_operations shmem_file_operations = {
2427         .mmap           = shmem_mmap,
2428 #ifdef CONFIG_TMPFS
2429         .llseek         = generic_file_llseek,
2430         .read           = do_sync_read,
2431         .write          = do_sync_write,
2432         .aio_read       = shmem_file_aio_read,
2433         .aio_write      = generic_file_aio_write,
2434         .fsync          = simple_sync_file,
2435         .splice_read    = generic_file_splice_read,
2436         .splice_write   = generic_file_splice_write,
2437 #endif
2438 };
2439
2440 static const struct inode_operations shmem_inode_operations = {
2441         .truncate       = shmem_truncate,
2442         .setattr        = shmem_notify_change,
2443         .truncate_range = shmem_truncate_range,
2444 #ifdef CONFIG_TMPFS_POSIX_ACL
2445         .setxattr       = generic_setxattr,
2446         .getxattr       = generic_getxattr,
2447         .listxattr      = generic_listxattr,
2448         .removexattr    = generic_removexattr,
2449         .check_acl      = shmem_check_acl,
2450 #endif
2451
2452 };
2453
2454 static const struct inode_operations shmem_dir_inode_operations = {
2455 #ifdef CONFIG_TMPFS
2456         .create         = shmem_create,
2457         .lookup         = simple_lookup,
2458         .link           = shmem_link,
2459         .unlink         = shmem_unlink,
2460         .symlink        = shmem_symlink,
2461         .mkdir          = shmem_mkdir,
2462         .rmdir          = shmem_rmdir,
2463         .mknod          = shmem_mknod,
2464         .rename         = shmem_rename,
2465 #endif
2466 #ifdef CONFIG_TMPFS_POSIX_ACL
2467         .setattr        = shmem_notify_change,
2468         .setxattr       = generic_setxattr,
2469         .getxattr       = generic_getxattr,
2470         .listxattr      = generic_listxattr,
2471         .removexattr    = generic_removexattr,
2472         .check_acl      = shmem_check_acl,
2473 #endif
2474 };
2475
2476 static const struct inode_operations shmem_special_inode_operations = {
2477 #ifdef CONFIG_TMPFS_POSIX_ACL
2478         .setattr        = shmem_notify_change,
2479         .setxattr       = generic_setxattr,
2480         .getxattr       = generic_getxattr,
2481         .listxattr      = generic_listxattr,
2482         .removexattr    = generic_removexattr,
2483         .check_acl      = shmem_check_acl,
2484 #endif
2485 };
2486
2487 static const struct super_operations shmem_ops = {
2488         .alloc_inode    = shmem_alloc_inode,
2489         .destroy_inode  = shmem_destroy_inode,
2490 #ifdef CONFIG_TMPFS
2491         .statfs         = shmem_statfs,
2492         .remount_fs     = shmem_remount_fs,
2493         .show_options   = shmem_show_options,
2494 #endif
2495         .delete_inode   = shmem_delete_inode,
2496         .drop_inode     = generic_delete_inode,
2497         .put_super      = shmem_put_super,
2498 };
2499
2500 static struct vm_operations_struct shmem_vm_ops = {
2501         .fault          = shmem_fault,
2502 #ifdef CONFIG_NUMA
2503         .set_policy     = shmem_set_policy,
2504         .get_policy     = shmem_get_policy,
2505 #endif
2506 };
2507
2508
2509 static int shmem_get_sb(struct file_system_type *fs_type,
2510         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2511 {
2512         return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2513 }
2514
2515 static struct file_system_type tmpfs_fs_type = {
2516         .owner          = THIS_MODULE,
2517         .name           = "tmpfs",
2518         .get_sb         = shmem_get_sb,
2519         .kill_sb        = kill_litter_super,
2520 };
2521
2522 int __init init_tmpfs(void)
2523 {
2524         int error;
2525
2526         error = bdi_init(&shmem_backing_dev_info);
2527         if (error)
2528                 goto out4;
2529
2530         error = init_inodecache();
2531         if (error)
2532                 goto out3;
2533
2534         error = register_filesystem(&tmpfs_fs_type);
2535         if (error) {
2536                 printk(KERN_ERR "Could not register tmpfs\n");
2537                 goto out2;
2538         }
2539
2540         shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2541                                 tmpfs_fs_type.name, NULL);
2542         if (IS_ERR(shm_mnt)) {
2543                 error = PTR_ERR(shm_mnt);
2544                 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2545                 goto out1;
2546         }
2547         return 0;
2548
2549 out1:
2550         unregister_filesystem(&tmpfs_fs_type);
2551 out2:
2552         destroy_inodecache();
2553 out3:
2554         bdi_destroy(&shmem_backing_dev_info);
2555 out4:
2556         shm_mnt = ERR_PTR(error);
2557         return error;
2558 }
2559
2560 #else /* !CONFIG_SHMEM */
2561
2562 /*
2563  * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2564  *
2565  * This is intended for small system where the benefits of the full
2566  * shmem code (swap-backed and resource-limited) are outweighed by
2567  * their complexity. On systems without swap this code should be
2568  * effectively equivalent, but much lighter weight.
2569  */
2570
2571 #include <linux/ramfs.h>
2572
2573 static struct file_system_type tmpfs_fs_type = {
2574         .name           = "tmpfs",
2575         .get_sb         = ramfs_get_sb,
2576         .kill_sb        = kill_litter_super,
2577 };
2578
2579 int __init init_tmpfs(void)
2580 {
2581         BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2582
2583         shm_mnt = kern_mount(&tmpfs_fs_type);
2584         BUG_ON(IS_ERR(shm_mnt));
2585
2586         return 0;
2587 }
2588
2589 int shmem_unuse(swp_entry_t entry, struct page *page)
2590 {
2591         return 0;
2592 }
2593
2594 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2595 {
2596         return 0;
2597 }
2598
2599 #define shmem_vm_ops                            generic_file_vm_ops
2600 #define shmem_file_operations                   ramfs_file_operations
2601 #define shmem_get_inode(sb, mode, dev, flags)   ramfs_get_inode(sb, mode, dev)
2602 #define shmem_acct_size(flags, size)            0
2603 #define shmem_unacct_size(flags, size)          do {} while (0)
2604 #define SHMEM_MAX_BYTES                         MAX_LFS_FILESIZE
2605
2606 #endif /* CONFIG_SHMEM */
2607
2608 /* common code */
2609
2610 /**
2611  * shmem_file_setup - get an unlinked file living in tmpfs
2612  * @name: name for dentry (to be seen in /proc/<pid>/maps
2613  * @size: size to be set for the file
2614  * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2615  */
2616 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2617 {
2618         int error;
2619         struct file *file;
2620         struct inode *inode;
2621         struct dentry *dentry, *root;
2622         struct qstr this;
2623
2624         if (IS_ERR(shm_mnt))
2625                 return (void *)shm_mnt;
2626
2627         if (size < 0 || size > SHMEM_MAX_BYTES)
2628                 return ERR_PTR(-EINVAL);
2629
2630         if (shmem_acct_size(flags, size))
2631                 return ERR_PTR(-ENOMEM);
2632
2633         error = -ENOMEM;
2634         this.name = name;
2635         this.len = strlen(name);
2636         this.hash = 0; /* will go */
2637         root = shm_mnt->mnt_root;
2638         dentry = d_alloc(root, &this);
2639         if (!dentry)
2640                 goto put_memory;
2641
2642         error = -ENFILE;
2643         file = get_empty_filp();
2644         if (!file)
2645                 goto put_dentry;
2646
2647         error = -ENOSPC;
2648         inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
2649         if (!inode)
2650                 goto close_file;
2651
2652         d_instantiate(dentry, inode);
2653         inode->i_size = size;
2654         inode->i_nlink = 0;     /* It is unlinked */
2655         init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
2656                   &shmem_file_operations);
2657
2658 #ifndef CONFIG_MMU
2659         error = ramfs_nommu_expand_for_mapping(inode, size);
2660         if (error)
2661                 goto close_file;
2662 #endif
2663         ima_counts_get(file);
2664         return file;
2665
2666 close_file:
2667         put_filp(file);
2668 put_dentry:
2669         dput(dentry);
2670 put_memory:
2671         shmem_unacct_size(flags, size);
2672         return ERR_PTR(error);
2673 }
2674 EXPORT_SYMBOL_GPL(shmem_file_setup);
2675
2676 /**
2677  * shmem_zero_setup - setup a shared anonymous mapping
2678  * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2679  */
2680 int shmem_zero_setup(struct vm_area_struct *vma)
2681 {
2682         struct file *file;
2683         loff_t size = vma->vm_end - vma->vm_start;
2684
2685         file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2686         if (IS_ERR(file))
2687                 return PTR_ERR(file);
2688
2689         if (vma->vm_file)
2690                 fput(vma->vm_file);
2691         vma->vm_file = file;
2692         vma->vm_ops = &shmem_vm_ops;
2693         return 0;
2694 }