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Linux v2.6.13-rc3
[pohmelfs.git] / mm / shmem.c
blobe64fa726a790e0c4162fec88db0e1032dd8a5be0
1 /*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
12 *
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16 *
17 * This file is released under the GPL.
18 */
19
20 /*
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
24 */
25
26 #include <linux/config.h>
27 #include <linux/module.h>
28 #include <linux/init.h>
29 #include <linux/devfs_fs_kernel.h>
30 #include <linux/fs.h>
31 #include <linux/mm.h>
32 #include <linux/mman.h>
33 #include <linux/file.h>
34 #include <linux/swap.h>
35 #include <linux/pagemap.h>
36 #include <linux/string.h>
37 #include <linux/slab.h>
38 #include <linux/backing-dev.h>
39 #include <linux/shmem_fs.h>
40 #include <linux/mount.h>
41 #include <linux/writeback.h>
42 #include <linux/vfs.h>
43 #include <linux/blkdev.h>
44 #include <linux/security.h>
45 #include <linux/swapops.h>
46 #include <linux/mempolicy.h>
47 #include <linux/namei.h>
48 #include <linux/xattr.h>
49 #include <asm/uaccess.h>
50 #include <asm/div64.h>
51 #include <asm/pgtable.h>
52
53 /* This magic number is used in glibc for posix shared memory */
54 #define TMPFS_MAGIC 0x01021994
55
56 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
57 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
58 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
59
60 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
61 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
62
63 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
64
65 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
66 #define SHMEM_PAGEIN VM_READ
67 #define SHMEM_TRUNCATE VM_WRITE
68
69 /* Definition to limit shmem_truncate's steps between cond_rescheds */
70 #define LATENCY_LIMIT 64
71
72 /* Pretend that each entry is of this size in directory's i_size */
73 #define BOGO_DIRENT_SIZE 20
74
75 /* Keep swapped page count in private field of indirect struct page */
76 #define nr_swapped private
77
78 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
79 enum sgp_type {
80 SGP_QUICK, /* don't try more than file page cache lookup */
81 SGP_READ, /* don't exceed i_size, don't allocate page */
82 SGP_CACHE, /* don't exceed i_size, may allocate page */
83 SGP_WRITE, /* may exceed i_size, may allocate page */
84 };
85
86 static int shmem_getpage(struct inode *inode, unsigned long idx,
87 struct page **pagep, enum sgp_type sgp, int *type);
88
89 static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
90 {
91 /*
92 * The above definition of ENTRIES_PER_PAGE, and the use of
93 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
94 * might be reconsidered if it ever diverges from PAGE_SIZE.
95 */
96 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
97 }
98
99 static inline void shmem_dir_free(struct page *page)
100 {
101 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
102 }
103
104 static struct page **shmem_dir_map(struct page *page)
105 {
106 return (struct page **)kmap_atomic(page, KM_USER0);
107 }
108
109 static inline void shmem_dir_unmap(struct page **dir)
110 {
111 kunmap_atomic(dir, KM_USER0);
112 }
113
114 static swp_entry_t *shmem_swp_map(struct page *page)
115 {
116 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
117 }
118
119 static inline void shmem_swp_balance_unmap(void)
120 {
121 /*
122 * When passing a pointer to an i_direct entry, to code which
123 * also handles indirect entries and so will shmem_swp_unmap,
124 * we must arrange for the preempt count to remain in balance.
125 * What kmap_atomic of a lowmem page does depends on config
126 * and architecture, so pretend to kmap_atomic some lowmem page.
127 */
128 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
129 }
130
131 static inline void shmem_swp_unmap(swp_entry_t *entry)
132 {
133 kunmap_atomic(entry, KM_USER1);
134 }
135
136 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
137 {
138 return sb->s_fs_info;
139 }
140
141 /*
142 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
143 * for shared memory and for shared anonymous (/dev/zero) mappings
144 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
145 * consistent with the pre-accounting of private mappings ...
146 */
147 static inline int shmem_acct_size(unsigned long flags, loff_t size)
148 {
149 return (flags & VM_ACCOUNT)?
150 security_vm_enough_memory(VM_ACCT(size)): 0;
151 }
152
153 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
154 {
155 if (flags & VM_ACCOUNT)
156 vm_unacct_memory(VM_ACCT(size));
157 }
158
159 /*
160 * ... whereas tmpfs objects are accounted incrementally as
161 * pages are allocated, in order to allow huge sparse files.
162 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
163 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
164 */
165 static inline int shmem_acct_block(unsigned long flags)
166 {
167 return (flags & VM_ACCOUNT)?
168 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
169 }
170
171 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
172 {
173 if (!(flags & VM_ACCOUNT))
174 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
175 }
176
177 static struct super_operations shmem_ops;
178 static struct address_space_operations shmem_aops;
179 static struct file_operations shmem_file_operations;
180 static struct inode_operations shmem_inode_operations;
181 static struct inode_operations shmem_dir_inode_operations;
182 static struct inode_operations shmem_special_inode_operations;
183 static struct vm_operations_struct shmem_vm_ops;
184
185 static struct backing_dev_info shmem_backing_dev_info = {
186 .ra_pages = 0, /* No readahead */
187 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
188 .unplug_io_fn = default_unplug_io_fn,
189 };
190
191 static LIST_HEAD(shmem_swaplist);
192 static DEFINE_SPINLOCK(shmem_swaplist_lock);
193
194 static void shmem_free_blocks(struct inode *inode, long pages)
195 {
196 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
197 if (sbinfo->max_blocks) {
198 spin_lock(&sbinfo->stat_lock);
199 sbinfo->free_blocks += pages;
200 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
201 spin_unlock(&sbinfo->stat_lock);
202 }
203 }
204
205 /*
206 * shmem_recalc_inode - recalculate the size of an inode
207 *
208 * @inode: inode to recalc
209 *
210 * We have to calculate the free blocks since the mm can drop
211 * undirtied hole pages behind our back.
212 *
213 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
214 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
215 *
216 * It has to be called with the spinlock held.
217 */
218 static void shmem_recalc_inode(struct inode *inode)
219 {
220 struct shmem_inode_info *info = SHMEM_I(inode);
221 long freed;
222
223 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
224 if (freed > 0) {
225 info->alloced -= freed;
226 shmem_unacct_blocks(info->flags, freed);
227 shmem_free_blocks(inode, freed);
228 }
229 }
230
231 /*
232 * shmem_swp_entry - find the swap vector position in the info structure
233 *
234 * @info: info structure for the inode
235 * @index: index of the page to find
236 * @page: optional page to add to the structure. Has to be preset to
237 * all zeros
238 *
239 * If there is no space allocated yet it will return NULL when
240 * page is NULL, else it will use the page for the needed block,
241 * setting it to NULL on return to indicate that it has been used.
242 *
243 * The swap vector is organized the following way:
244 *
245 * There are SHMEM_NR_DIRECT entries directly stored in the
246 * shmem_inode_info structure. So small files do not need an addional
247 * allocation.
248 *
249 * For pages with index > SHMEM_NR_DIRECT there is the pointer
250 * i_indirect which points to a page which holds in the first half
251 * doubly indirect blocks, in the second half triple indirect blocks:
252 *
253 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
254 * following layout (for SHMEM_NR_DIRECT == 16):
255 *
256 * i_indirect -> dir --> 16-19
257 * | +-> 20-23
258 * |
259 * +-->dir2 --> 24-27
260 * | +-> 28-31
261 * | +-> 32-35
262 * | +-> 36-39
263 * |
264 * +-->dir3 --> 40-43
265 * +-> 44-47
266 * +-> 48-51
267 * +-> 52-55
268 */
269 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
270 {
271 unsigned long offset;
272 struct page **dir;
273 struct page *subdir;
274
275 if (index < SHMEM_NR_DIRECT) {
276 shmem_swp_balance_unmap();
277 return info->i_direct+index;
278 }
279 if (!info->i_indirect) {
280 if (page) {
281 info->i_indirect = *page;
282 *page = NULL;
283 }
284 return NULL; /* need another page */
285 }
286
287 index -= SHMEM_NR_DIRECT;
288 offset = index % ENTRIES_PER_PAGE;
289 index /= ENTRIES_PER_PAGE;
290 dir = shmem_dir_map(info->i_indirect);
291
292 if (index >= ENTRIES_PER_PAGE/2) {
293 index -= ENTRIES_PER_PAGE/2;
294 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
295 index %= ENTRIES_PER_PAGE;
296 subdir = *dir;
297 if (!subdir) {
298 if (page) {
299 *dir = *page;
300 *page = NULL;
301 }
302 shmem_dir_unmap(dir);
303 return NULL; /* need another page */
304 }
305 shmem_dir_unmap(dir);
306 dir = shmem_dir_map(subdir);
307 }
308
309 dir += index;
310 subdir = *dir;
311 if (!subdir) {
312 if (!page || !(subdir = *page)) {
313 shmem_dir_unmap(dir);
314 return NULL; /* need a page */
315 }
316 *dir = subdir;
317 *page = NULL;
318 }
319 shmem_dir_unmap(dir);
320 return shmem_swp_map(subdir) + offset;
321 }
322
323 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
324 {
325 long incdec = value? 1: -1;
326
327 entry->val = value;
328 info->swapped += incdec;
329 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
330 kmap_atomic_to_page(entry)->nr_swapped += incdec;
331 }
332
333 /*
334 * shmem_swp_alloc - get the position of the swap entry for the page.
335 * If it does not exist allocate the entry.
336 *
337 * @info: info structure for the inode
338 * @index: index of the page to find
339 * @sgp: check and recheck i_size? skip allocation?
340 */
341 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
342 {
343 struct inode *inode = &info->vfs_inode;
344 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
345 struct page *page = NULL;
346 swp_entry_t *entry;
347
348 if (sgp != SGP_WRITE &&
349 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
350 return ERR_PTR(-EINVAL);
351
352 while (!(entry = shmem_swp_entry(info, index, &page))) {
353 if (sgp == SGP_READ)
354 return shmem_swp_map(ZERO_PAGE(0));
355 /*
356 * Test free_blocks against 1 not 0, since we have 1 data
357 * page (and perhaps indirect index pages) yet to allocate:
358 * a waste to allocate index if we cannot allocate data.
359 */
360 if (sbinfo->max_blocks) {
361 spin_lock(&sbinfo->stat_lock);
362 if (sbinfo->free_blocks <= 1) {
363 spin_unlock(&sbinfo->stat_lock);
364 return ERR_PTR(-ENOSPC);
365 }
366 sbinfo->free_blocks--;
367 inode->i_blocks += BLOCKS_PER_PAGE;
368 spin_unlock(&sbinfo->stat_lock);
369 }
370
371 spin_unlock(&info->lock);
372 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
373 if (page) {
374 page->nr_swapped = 0;
375 }
376 spin_lock(&info->lock);
377
378 if (!page) {
379 shmem_free_blocks(inode, 1);
380 return ERR_PTR(-ENOMEM);
381 }
382 if (sgp != SGP_WRITE &&
383 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
384 entry = ERR_PTR(-EINVAL);
385 break;
386 }
387 if (info->next_index <= index)
388 info->next_index = index + 1;
389 }
390 if (page) {
391 /* another task gave its page, or truncated the file */
392 shmem_free_blocks(inode, 1);
393 shmem_dir_free(page);
394 }
395 if (info->next_index <= index && !IS_ERR(entry))
396 info->next_index = index + 1;
397 return entry;
398 }
399
400 /*
401 * shmem_free_swp - free some swap entries in a directory
402 *
403 * @dir: pointer to the directory
404 * @edir: pointer after last entry of the directory
405 */
406 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
407 {
408 swp_entry_t *ptr;
409 int freed = 0;
410
411 for (ptr = dir; ptr < edir; ptr++) {
412 if (ptr->val) {
413 free_swap_and_cache(*ptr);
414 *ptr = (swp_entry_t){0};
415 freed++;
416 }
417 }
418 return freed;
419 }
420
421 static int shmem_map_and_free_swp(struct page *subdir,
422 int offset, int limit, struct page ***dir)
423 {
424 swp_entry_t *ptr;
425 int freed = 0;
426
427 ptr = shmem_swp_map(subdir);
428 for (; offset < limit; offset += LATENCY_LIMIT) {
429 int size = limit - offset;
430 if (size > LATENCY_LIMIT)
431 size = LATENCY_LIMIT;
432 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
433 if (need_resched()) {
434 shmem_swp_unmap(ptr);
435 if (*dir) {
436 shmem_dir_unmap(*dir);
437 *dir = NULL;
438 }
439 cond_resched();
440 ptr = shmem_swp_map(subdir);
441 }
442 }
443 shmem_swp_unmap(ptr);
444 return freed;
445 }
446
447 static void shmem_free_pages(struct list_head *next)
448 {
449 struct page *page;
450 int freed = 0;
451
452 do {
453 page = container_of(next, struct page, lru);
454 next = next->next;
455 shmem_dir_free(page);
456 freed++;
457 if (freed >= LATENCY_LIMIT) {
458 cond_resched();
459 freed = 0;
460 }
461 } while (next);
462 }
463
464 static void shmem_truncate(struct inode *inode)
465 {
466 struct shmem_inode_info *info = SHMEM_I(inode);
467 unsigned long idx;
468 unsigned long size;
469 unsigned long limit;
470 unsigned long stage;
471 unsigned long diroff;
472 struct page **dir;
473 struct page *topdir;
474 struct page *middir;
475 struct page *subdir;
476 swp_entry_t *ptr;
477 LIST_HEAD(pages_to_free);
478 long nr_pages_to_free = 0;
479 long nr_swaps_freed = 0;
480 int offset;
481 int freed;
482
483 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
484 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
485 if (idx >= info->next_index)
486 return;
487
488 spin_lock(&info->lock);
489 info->flags |= SHMEM_TRUNCATE;
490 limit = info->next_index;
491 info->next_index = idx;
492 topdir = info->i_indirect;
493 if (topdir && idx <= SHMEM_NR_DIRECT) {
494 info->i_indirect = NULL;
495 nr_pages_to_free++;
496 list_add(&topdir->lru, &pages_to_free);
497 }
498 spin_unlock(&info->lock);
499
500 if (info->swapped && idx < SHMEM_NR_DIRECT) {
501 ptr = info->i_direct;
502 size = limit;
503 if (size > SHMEM_NR_DIRECT)
504 size = SHMEM_NR_DIRECT;
505 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
506 }
507 if (!topdir)
508 goto done2;
509
510 BUG_ON(limit <= SHMEM_NR_DIRECT);
511 limit -= SHMEM_NR_DIRECT;
512 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
513 offset = idx % ENTRIES_PER_PAGE;
514 idx -= offset;
515
516 dir = shmem_dir_map(topdir);
517 stage = ENTRIES_PER_PAGEPAGE/2;
518 if (idx < ENTRIES_PER_PAGEPAGE/2) {
519 middir = topdir;
520 diroff = idx/ENTRIES_PER_PAGE;
521 } else {
522 dir += ENTRIES_PER_PAGE/2;
523 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
524 while (stage <= idx)
525 stage += ENTRIES_PER_PAGEPAGE;
526 middir = *dir;
527 if (*dir) {
528 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
529 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
530 if (!diroff && !offset) {
531 *dir = NULL;
532 nr_pages_to_free++;
533 list_add(&middir->lru, &pages_to_free);
534 }
535 shmem_dir_unmap(dir);
536 dir = shmem_dir_map(middir);
537 } else {
538 diroff = 0;
539 offset = 0;
540 idx = stage;
541 }
542 }
543
544 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
545 if (unlikely(idx == stage)) {
546 shmem_dir_unmap(dir);
547 dir = shmem_dir_map(topdir) +
548 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
549 while (!*dir) {
550 dir++;
551 idx += ENTRIES_PER_PAGEPAGE;
552 if (idx >= limit)
553 goto done1;
554 }
555 stage = idx + ENTRIES_PER_PAGEPAGE;
556 middir = *dir;
557 *dir = NULL;
558 nr_pages_to_free++;
559 list_add(&middir->lru, &pages_to_free);
560 shmem_dir_unmap(dir);
561 cond_resched();
562 dir = shmem_dir_map(middir);
563 diroff = 0;
564 }
565 subdir = dir[diroff];
566 if (subdir && subdir->nr_swapped) {
567 size = limit - idx;
568 if (size > ENTRIES_PER_PAGE)
569 size = ENTRIES_PER_PAGE;
570 freed = shmem_map_and_free_swp(subdir,
571 offset, size, &dir);
572 if (!dir)
573 dir = shmem_dir_map(middir);
574 nr_swaps_freed += freed;
575 if (offset)
576 spin_lock(&info->lock);
577 subdir->nr_swapped -= freed;
578 if (offset)
579 spin_unlock(&info->lock);
580 BUG_ON(subdir->nr_swapped > offset);
581 }
582 if (offset)
583 offset = 0;
584 else if (subdir) {
585 dir[diroff] = NULL;
586 nr_pages_to_free++;
587 list_add(&subdir->lru, &pages_to_free);
588 }
589 }
590 done1:
591 shmem_dir_unmap(dir);
592 done2:
593 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
594 /*
595 * Call truncate_inode_pages again: racing shmem_unuse_inode
596 * may have swizzled a page in from swap since vmtruncate or
597 * generic_delete_inode did it, before we lowered next_index.
598 * Also, though shmem_getpage checks i_size before adding to
599 * cache, no recheck after: so fix the narrow window there too.
600 */
601 truncate_inode_pages(inode->i_mapping, inode->i_size);
602 }
603
604 spin_lock(&info->lock);
605 info->flags &= ~SHMEM_TRUNCATE;
606 info->swapped -= nr_swaps_freed;
607 if (nr_pages_to_free)
608 shmem_free_blocks(inode, nr_pages_to_free);
609 shmem_recalc_inode(inode);
610 spin_unlock(&info->lock);
611
612 /*
613 * Empty swap vector directory pages to be freed?
614 */
615 if (!list_empty(&pages_to_free)) {
616 pages_to_free.prev->next = NULL;
617 shmem_free_pages(pages_to_free.next);
618 }
619 }
620
621 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
622 {
623 struct inode *inode = dentry->d_inode;
624 struct page *page = NULL;
625 int error;
626
627 if (attr->ia_valid & ATTR_SIZE) {
628 if (attr->ia_size < inode->i_size) {
629 /*
630 * If truncating down to a partial page, then
631 * if that page is already allocated, hold it
632 * in memory until the truncation is over, so
633 * truncate_partial_page cannnot miss it were
634 * it assigned to swap.
635 */
636 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
637 (void) shmem_getpage(inode,
638 attr->ia_size>>PAGE_CACHE_SHIFT,
639 &page, SGP_READ, NULL);
640 }
641 /*
642 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
643 * detect if any pages might have been added to cache
644 * after truncate_inode_pages. But we needn't bother
645 * if it's being fully truncated to zero-length: the
646 * nrpages check is efficient enough in that case.
647 */
648 if (attr->ia_size) {
649 struct shmem_inode_info *info = SHMEM_I(inode);
650 spin_lock(&info->lock);
651 info->flags &= ~SHMEM_PAGEIN;
652 spin_unlock(&info->lock);
653 }
654 }
655 }
656
657 error = inode_change_ok(inode, attr);
658 if (!error)
659 error = inode_setattr(inode, attr);
660 if (page)
661 page_cache_release(page);
662 return error;
663 }
664
665 static void shmem_delete_inode(struct inode *inode)
666 {
667 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
668 struct shmem_inode_info *info = SHMEM_I(inode);
669
670 if (inode->i_op->truncate == shmem_truncate) {
671 shmem_unacct_size(info->flags, inode->i_size);
672 inode->i_size = 0;
673 shmem_truncate(inode);
674 if (!list_empty(&info->swaplist)) {
675 spin_lock(&shmem_swaplist_lock);
676 list_del_init(&info->swaplist);
677 spin_unlock(&shmem_swaplist_lock);
678 }
679 }
680 BUG_ON(inode->i_blocks);
681 if (sbinfo->max_inodes) {
682 spin_lock(&sbinfo->stat_lock);
683 sbinfo->free_inodes++;
684 spin_unlock(&sbinfo->stat_lock);
685 }
686 clear_inode(inode);
687 }
688
689 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
690 {
691 swp_entry_t *ptr;
692
693 for (ptr = dir; ptr < edir; ptr++) {
694 if (ptr->val == entry.val)
695 return ptr - dir;
696 }
697 return -1;
698 }
699
700 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
701 {
702 struct inode *inode;
703 unsigned long idx;
704 unsigned long size;
705 unsigned long limit;
706 unsigned long stage;
707 struct page **dir;
708 struct page *subdir;
709 swp_entry_t *ptr;
710 int offset;
711
712 idx = 0;
713 ptr = info->i_direct;
714 spin_lock(&info->lock);
715 limit = info->next_index;
716 size = limit;
717 if (size > SHMEM_NR_DIRECT)
718 size = SHMEM_NR_DIRECT;
719 offset = shmem_find_swp(entry, ptr, ptr+size);
720 if (offset >= 0) {
721 shmem_swp_balance_unmap();
722 goto found;
723 }
724 if (!info->i_indirect)
725 goto lost2;
726
727 dir = shmem_dir_map(info->i_indirect);
728 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
729
730 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
731 if (unlikely(idx == stage)) {
732 shmem_dir_unmap(dir-1);
733 dir = shmem_dir_map(info->i_indirect) +
734 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
735 while (!*dir) {
736 dir++;
737 idx += ENTRIES_PER_PAGEPAGE;
738 if (idx >= limit)
739 goto lost1;
740 }
741 stage = idx + ENTRIES_PER_PAGEPAGE;
742 subdir = *dir;
743 shmem_dir_unmap(dir);
744 dir = shmem_dir_map(subdir);
745 }
746 subdir = *dir;
747 if (subdir && subdir->nr_swapped) {
748 ptr = shmem_swp_map(subdir);
749 size = limit - idx;
750 if (size > ENTRIES_PER_PAGE)
751 size = ENTRIES_PER_PAGE;
752 offset = shmem_find_swp(entry, ptr, ptr+size);
753 if (offset >= 0) {
754 shmem_dir_unmap(dir);
755 goto found;
756 }
757 shmem_swp_unmap(ptr);
758 }
759 }
760 lost1:
761 shmem_dir_unmap(dir-1);
762 lost2:
763 spin_unlock(&info->lock);
764 return 0;
765 found:
766 idx += offset;
767 inode = &info->vfs_inode;
768 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
769 info->flags |= SHMEM_PAGEIN;
770 shmem_swp_set(info, ptr + offset, 0);
771 }
772 shmem_swp_unmap(ptr);
773 spin_unlock(&info->lock);
774 /*
775 * Decrement swap count even when the entry is left behind:
776 * try_to_unuse will skip over mms, then reincrement count.
777 */
778 swap_free(entry);
779 return 1;
780 }
781
782 /*
783 * shmem_unuse() search for an eventually swapped out shmem page.
784 */
785 int shmem_unuse(swp_entry_t entry, struct page *page)
786 {
787 struct list_head *p, *next;
788 struct shmem_inode_info *info;
789 int found = 0;
790
791 spin_lock(&shmem_swaplist_lock);
792 list_for_each_safe(p, next, &shmem_swaplist) {
793 info = list_entry(p, struct shmem_inode_info, swaplist);
794 if (!info->swapped)
795 list_del_init(&info->swaplist);
796 else if (shmem_unuse_inode(info, entry, page)) {
797 /* move head to start search for next from here */
798 list_move_tail(&shmem_swaplist, &info->swaplist);
799 found = 1;
800 break;
801 }
802 }
803 spin_unlock(&shmem_swaplist_lock);
804 return found;
805 }
806
807 /*
808 * Move the page from the page cache to the swap cache.
809 */
810 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
811 {
812 struct shmem_inode_info *info;
813 swp_entry_t *entry, swap;
814 struct address_space *mapping;
815 unsigned long index;
816 struct inode *inode;
817
818 BUG_ON(!PageLocked(page));
819 BUG_ON(page_mapped(page));
820
821 mapping = page->mapping;
822 index = page->index;
823 inode = mapping->host;
824 info = SHMEM_I(inode);
825 if (info->flags & VM_LOCKED)
826 goto redirty;
827 swap = get_swap_page();
828 if (!swap.val)
829 goto redirty;
830
831 spin_lock(&info->lock);
832 shmem_recalc_inode(inode);
833 if (index >= info->next_index) {
834 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
835 goto unlock;
836 }
837 entry = shmem_swp_entry(info, index, NULL);
838 BUG_ON(!entry);
839 BUG_ON(entry->val);
840
841 if (move_to_swap_cache(page, swap) == 0) {
842 shmem_swp_set(info, entry, swap.val);
843 shmem_swp_unmap(entry);
844 spin_unlock(&info->lock);
845 if (list_empty(&info->swaplist)) {
846 spin_lock(&shmem_swaplist_lock);
847 /* move instead of add in case we're racing */
848 list_move_tail(&info->swaplist, &shmem_swaplist);
849 spin_unlock(&shmem_swaplist_lock);
850 }
851 unlock_page(page);
852 return 0;
853 }
854
855 shmem_swp_unmap(entry);
856 unlock:
857 spin_unlock(&info->lock);
858 swap_free(swap);
859 redirty:
860 set_page_dirty(page);
861 return WRITEPAGE_ACTIVATE; /* Return with the page locked */
862 }
863
864 #ifdef CONFIG_NUMA
865 static struct page *shmem_swapin_async(struct shared_policy *p,
866 swp_entry_t entry, unsigned long idx)
867 {
868 struct page *page;
869 struct vm_area_struct pvma;
870
871 /* Create a pseudo vma that just contains the policy */
872 memset(&pvma, 0, sizeof(struct vm_area_struct));
873 pvma.vm_end = PAGE_SIZE;
874 pvma.vm_pgoff = idx;
875 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
876 page = read_swap_cache_async(entry, &pvma, 0);
877 mpol_free(pvma.vm_policy);
878 return page;
879 }
880
881 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
882 unsigned long idx)
883 {
884 struct shared_policy *p = &info->policy;
885 int i, num;
886 struct page *page;
887 unsigned long offset;
888
889 num = valid_swaphandles(entry, &offset);
890 for (i = 0; i < num; offset++, i++) {
891 page = shmem_swapin_async(p,
892 swp_entry(swp_type(entry), offset), idx);
893 if (!page)
894 break;
895 page_cache_release(page);
896 }
897 lru_add_drain(); /* Push any new pages onto the LRU now */
898 return shmem_swapin_async(p, entry, idx);
899 }
900
901 static struct page *
902 shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
903 unsigned long idx)
904 {
905 struct vm_area_struct pvma;
906 struct page *page;
907
908 memset(&pvma, 0, sizeof(struct vm_area_struct));
909 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
910 pvma.vm_pgoff = idx;
911 pvma.vm_end = PAGE_SIZE;
912 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
913 mpol_free(pvma.vm_policy);
914 return page;
915 }
916 #else
917 static inline struct page *
918 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
919 {
920 swapin_readahead(entry, 0, NULL);
921 return read_swap_cache_async(entry, NULL, 0);
922 }
923
924 static inline struct page *
925 shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info,
926 unsigned long idx)
927 {
928 return alloc_page(gfp | __GFP_ZERO);
929 }
930 #endif
931
932 /*
933 * shmem_getpage - either get the page from swap or allocate a new one
934 *
935 * If we allocate a new one we do not mark it dirty. That's up to the
936 * vm. If we swap it in we mark it dirty since we also free the swap
937 * entry since a page cannot live in both the swap and page cache
938 */
939 static int shmem_getpage(struct inode *inode, unsigned long idx,
940 struct page **pagep, enum sgp_type sgp, int *type)
941 {
942 struct address_space *mapping = inode->i_mapping;
943 struct shmem_inode_info *info = SHMEM_I(inode);
944 struct shmem_sb_info *sbinfo;
945 struct page *filepage = *pagep;
946 struct page *swappage;
947 swp_entry_t *entry;
948 swp_entry_t swap;
949 int error;
950
951 if (idx >= SHMEM_MAX_INDEX)
952 return -EFBIG;
953 /*
954 * Normally, filepage is NULL on entry, and either found
955 * uptodate immediately, or allocated and zeroed, or read
956 * in under swappage, which is then assigned to filepage.
957 * But shmem_prepare_write passes in a locked filepage,
958 * which may be found not uptodate by other callers too,
959 * and may need to be copied from the swappage read in.
960 */
961 repeat:
962 if (!filepage)
963 filepage = find_lock_page(mapping, idx);
964 if (filepage && PageUptodate(filepage))
965 goto done;
966 error = 0;
967 if (sgp == SGP_QUICK)
968 goto failed;
969
970 spin_lock(&info->lock);
971 shmem_recalc_inode(inode);
972 entry = shmem_swp_alloc(info, idx, sgp);
973 if (IS_ERR(entry)) {
974 spin_unlock(&info->lock);
975 error = PTR_ERR(entry);
976 goto failed;
977 }
978 swap = *entry;
979
980 if (swap.val) {
981 /* Look it up and read it in.. */
982 swappage = lookup_swap_cache(swap);
983 if (!swappage) {
984 shmem_swp_unmap(entry);
985 spin_unlock(&info->lock);
986 /* here we actually do the io */
987 if (type && *type == VM_FAULT_MINOR) {
988 inc_page_state(pgmajfault);
989 *type = VM_FAULT_MAJOR;
990 }
991 swappage = shmem_swapin(info, swap, idx);
992 if (!swappage) {
993 spin_lock(&info->lock);
994 entry = shmem_swp_alloc(info, idx, sgp);
995 if (IS_ERR(entry))
996 error = PTR_ERR(entry);
997 else {
998 if (entry->val == swap.val)
999 error = -ENOMEM;
1000 shmem_swp_unmap(entry);
1001 }
1002 spin_unlock(&info->lock);
1003 if (error)
1004 goto failed;
1005 goto repeat;
1006 }
1007 wait_on_page_locked(swappage);
1008 page_cache_release(swappage);
1009 goto repeat;
1010 }
1011
1012 /* We have to do this with page locked to prevent races */
1013 if (TestSetPageLocked(swappage)) {
1014 shmem_swp_unmap(entry);
1015 spin_unlock(&info->lock);
1016 wait_on_page_locked(swappage);
1017 page_cache_release(swappage);
1018 goto repeat;
1019 }
1020 if (PageWriteback(swappage)) {
1021 shmem_swp_unmap(entry);
1022 spin_unlock(&info->lock);
1023 wait_on_page_writeback(swappage);
1024 unlock_page(swappage);
1025 page_cache_release(swappage);
1026 goto repeat;
1027 }
1028 if (!PageUptodate(swappage)) {
1029 shmem_swp_unmap(entry);
1030 spin_unlock(&info->lock);
1031 unlock_page(swappage);
1032 page_cache_release(swappage);
1033 error = -EIO;
1034 goto failed;
1035 }
1036
1037 if (filepage) {
1038 shmem_swp_set(info, entry, 0);
1039 shmem_swp_unmap(entry);
1040 delete_from_swap_cache(swappage);
1041 spin_unlock(&info->lock);
1042 copy_highpage(filepage, swappage);
1043 unlock_page(swappage);
1044 page_cache_release(swappage);
1045 flush_dcache_page(filepage);
1046 SetPageUptodate(filepage);
1047 set_page_dirty(filepage);
1048 swap_free(swap);
1049 } else if (!(error = move_from_swap_cache(
1050 swappage, idx, mapping))) {
1051 info->flags |= SHMEM_PAGEIN;
1052 shmem_swp_set(info, entry, 0);
1053 shmem_swp_unmap(entry);
1054 spin_unlock(&info->lock);
1055 filepage = swappage;
1056 swap_free(swap);
1057 } else {
1058 shmem_swp_unmap(entry);
1059 spin_unlock(&info->lock);
1060 unlock_page(swappage);
1061 page_cache_release(swappage);
1062 if (error == -ENOMEM) {
1063 /* let kswapd refresh zone for GFP_ATOMICs */
1064 blk_congestion_wait(WRITE, HZ/50);
1065 }
1066 goto repeat;
1067 }
1068 } else if (sgp == SGP_READ && !filepage) {
1069 shmem_swp_unmap(entry);
1070 filepage = find_get_page(mapping, idx);
1071 if (filepage &&
1072 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1073 spin_unlock(&info->lock);
1074 wait_on_page_locked(filepage);
1075 page_cache_release(filepage);
1076 filepage = NULL;
1077 goto repeat;
1078 }
1079 spin_unlock(&info->lock);
1080 } else {
1081 shmem_swp_unmap(entry);
1082 sbinfo = SHMEM_SB(inode->i_sb);
1083 if (sbinfo->max_blocks) {
1084 spin_lock(&sbinfo->stat_lock);
1085 if (sbinfo->free_blocks == 0 ||
1086 shmem_acct_block(info->flags)) {
1087 spin_unlock(&sbinfo->stat_lock);
1088 spin_unlock(&info->lock);
1089 error = -ENOSPC;
1090 goto failed;
1091 }
1092 sbinfo->free_blocks--;
1093 inode->i_blocks += BLOCKS_PER_PAGE;
1094 spin_unlock(&sbinfo->stat_lock);
1095 } else if (shmem_acct_block(info->flags)) {
1096 spin_unlock(&info->lock);
1097 error = -ENOSPC;
1098 goto failed;
1099 }
1100
1101 if (!filepage) {
1102 spin_unlock(&info->lock);
1103 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1104 info,
1105 idx);
1106 if (!filepage) {
1107 shmem_unacct_blocks(info->flags, 1);
1108 shmem_free_blocks(inode, 1);
1109 error = -ENOMEM;
1110 goto failed;
1111 }
1112
1113 spin_lock(&info->lock);
1114 entry = shmem_swp_alloc(info, idx, sgp);
1115 if (IS_ERR(entry))
1116 error = PTR_ERR(entry);
1117 else {
1118 swap = *entry;
1119 shmem_swp_unmap(entry);
1120 }
1121 if (error || swap.val || 0 != add_to_page_cache_lru(
1122 filepage, mapping, idx, GFP_ATOMIC)) {
1123 spin_unlock(&info->lock);
1124 page_cache_release(filepage);
1125 shmem_unacct_blocks(info->flags, 1);
1126 shmem_free_blocks(inode, 1);
1127 filepage = NULL;
1128 if (error)
1129 goto failed;
1130 goto repeat;
1131 }
1132 info->flags |= SHMEM_PAGEIN;
1133 }
1134
1135 info->alloced++;
1136 spin_unlock(&info->lock);
1137 flush_dcache_page(filepage);
1138 SetPageUptodate(filepage);
1139 }
1140 done:
1141 if (*pagep != filepage) {
1142 unlock_page(filepage);
1143 *pagep = filepage;
1144 }
1145 return 0;
1146
1147 failed:
1148 if (*pagep != filepage) {
1149 unlock_page(filepage);
1150 page_cache_release(filepage);
1151 }
1152 return error;
1153 }
1154
1155 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1156 {
1157 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1158 struct page *page = NULL;
1159 unsigned long idx;
1160 int error;
1161
1162 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1163 idx += vma->vm_pgoff;
1164 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1165 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1166 return NOPAGE_SIGBUS;
1167
1168 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1169 if (error)
1170 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1171
1172 mark_page_accessed(page);
1173 return page;
1174 }
1175
1176 static int shmem_populate(struct vm_area_struct *vma,
1177 unsigned long addr, unsigned long len,
1178 pgprot_t prot, unsigned long pgoff, int nonblock)
1179 {
1180 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1181 struct mm_struct *mm = vma->vm_mm;
1182 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1183 unsigned long size;
1184
1185 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1186 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1187 return -EINVAL;
1188
1189 while ((long) len > 0) {
1190 struct page *page = NULL;
1191 int err;
1192 /*
1193 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1194 */
1195 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1196 if (err)
1197 return err;
1198 if (page) {
1199 mark_page_accessed(page);
1200 err = install_page(mm, vma, addr, page, prot);
1201 if (err) {
1202 page_cache_release(page);
1203 return err;
1204 }
1205 } else if (nonblock) {
1206 err = install_file_pte(mm, vma, addr, pgoff, prot);
1207 if (err)
1208 return err;
1209 }
1210
1211 len -= PAGE_SIZE;
1212 addr += PAGE_SIZE;
1213 pgoff++;
1214 }
1215 return 0;
1216 }
1217
1218 #ifdef CONFIG_NUMA
1219 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1220 {
1221 struct inode *i = vma->vm_file->f_dentry->d_inode;
1222 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1223 }
1224
1225 struct mempolicy *
1226 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1227 {
1228 struct inode *i = vma->vm_file->f_dentry->d_inode;
1229 unsigned long idx;
1230
1231 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1232 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1233 }
1234 #endif
1235
1236 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1237 {
1238 struct inode *inode = file->f_dentry->d_inode;
1239 struct shmem_inode_info *info = SHMEM_I(inode);
1240 int retval = -ENOMEM;
1241
1242 spin_lock(&info->lock);
1243 if (lock && !(info->flags & VM_LOCKED)) {
1244 if (!user_shm_lock(inode->i_size, user))
1245 goto out_nomem;
1246 info->flags |= VM_LOCKED;
1247 }
1248 if (!lock && (info->flags & VM_LOCKED) && user) {
1249 user_shm_unlock(inode->i_size, user);
1250 info->flags &= ~VM_LOCKED;
1251 }
1252 retval = 0;
1253 out_nomem:
1254 spin_unlock(&info->lock);
1255 return retval;
1256 }
1257
1258 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1259 {
1260 file_accessed(file);
1261 vma->vm_ops = &shmem_vm_ops;
1262 return 0;
1263 }
1264
1265 static struct inode *
1266 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1267 {
1268 struct inode *inode;
1269 struct shmem_inode_info *info;
1270 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1271
1272 if (sbinfo->max_inodes) {
1273 spin_lock(&sbinfo->stat_lock);
1274 if (!sbinfo->free_inodes) {
1275 spin_unlock(&sbinfo->stat_lock);
1276 return NULL;
1277 }
1278 sbinfo->free_inodes--;
1279 spin_unlock(&sbinfo->stat_lock);
1280 }
1281
1282 inode = new_inode(sb);
1283 if (inode) {
1284 inode->i_mode = mode;
1285 inode->i_uid = current->fsuid;
1286 inode->i_gid = current->fsgid;
1287 inode->i_blksize = PAGE_CACHE_SIZE;
1288 inode->i_blocks = 0;
1289 inode->i_mapping->a_ops = &shmem_aops;
1290 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1291 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1292 info = SHMEM_I(inode);
1293 memset(info, 0, (char *)inode - (char *)info);
1294 spin_lock_init(&info->lock);
1295 INIT_LIST_HEAD(&info->swaplist);
1296
1297 switch (mode & S_IFMT) {
1298 default:
1299 inode->i_op = &shmem_special_inode_operations;
1300 init_special_inode(inode, mode, dev);
1301 break;
1302 case S_IFREG:
1303 inode->i_op = &shmem_inode_operations;
1304 inode->i_fop = &shmem_file_operations;
1305 mpol_shared_policy_init(&info->policy);
1306 break;
1307 case S_IFDIR:
1308 inode->i_nlink++;
1309 /* Some things misbehave if size == 0 on a directory */
1310 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1311 inode->i_op = &shmem_dir_inode_operations;
1312 inode->i_fop = &simple_dir_operations;
1313 break;
1314 case S_IFLNK:
1315 /*
1316 * Must not load anything in the rbtree,
1317 * mpol_free_shared_policy will not be called.
1318 */
1319 mpol_shared_policy_init(&info->policy);
1320 break;
1321 }
1322 } else if (sbinfo->max_inodes) {
1323 spin_lock(&sbinfo->stat_lock);
1324 sbinfo->free_inodes++;
1325 spin_unlock(&sbinfo->stat_lock);
1326 }
1327 return inode;
1328 }
1329
1330 #ifdef CONFIG_TMPFS
1331 static struct inode_operations shmem_symlink_inode_operations;
1332 static struct inode_operations shmem_symlink_inline_operations;
1333
1334 /*
1335 * Normally tmpfs makes no use of shmem_prepare_write, but it
1336 * lets a tmpfs file be used read-write below the loop driver.
1337 */
1338 static int
1339 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1340 {
1341 struct inode *inode = page->mapping->host;
1342 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1343 }
1344
1345 static ssize_t
1346 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1347 {
1348 struct inode *inode = file->f_dentry->d_inode;
1349 loff_t pos;
1350 unsigned long written;
1351 ssize_t err;
1352
1353 if ((ssize_t) count < 0)
1354 return -EINVAL;
1355
1356 if (!access_ok(VERIFY_READ, buf, count))
1357 return -EFAULT;
1358
1359 down(&inode->i_sem);
1360
1361 pos = *ppos;
1362 written = 0;
1363
1364 err = generic_write_checks(file, &pos, &count, 0);
1365 if (err || !count)
1366 goto out;
1367
1368 err = remove_suid(file->f_dentry);
1369 if (err)
1370 goto out;
1371
1372 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1373
1374 do {
1375 struct page *page = NULL;
1376 unsigned long bytes, index, offset;
1377 char *kaddr;
1378 int left;
1379
1380 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1381 index = pos >> PAGE_CACHE_SHIFT;
1382 bytes = PAGE_CACHE_SIZE - offset;
1383 if (bytes > count)
1384 bytes = count;
1385
1386 /*
1387 * We don't hold page lock across copy from user -
1388 * what would it guard against? - so no deadlock here.
1389 * But it still may be a good idea to prefault below.
1390 */
1391
1392 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1393 if (err)
1394 break;
1395
1396 left = bytes;
1397 if (PageHighMem(page)) {
1398 volatile unsigned char dummy;
1399 __get_user(dummy, buf);
1400 __get_user(dummy, buf + bytes - 1);
1401
1402 kaddr = kmap_atomic(page, KM_USER0);
1403 left = __copy_from_user_inatomic(kaddr + offset,
1404 buf, bytes);
1405 kunmap_atomic(kaddr, KM_USER0);
1406 }
1407 if (left) {
1408 kaddr = kmap(page);
1409 left = __copy_from_user(kaddr + offset, buf, bytes);
1410 kunmap(page);
1411 }
1412
1413 written += bytes;
1414 count -= bytes;
1415 pos += bytes;
1416 buf += bytes;
1417 if (pos > inode->i_size)
1418 i_size_write(inode, pos);
1419
1420 flush_dcache_page(page);
1421 set_page_dirty(page);
1422 mark_page_accessed(page);
1423 page_cache_release(page);
1424
1425 if (left) {
1426 pos -= left;
1427 written -= left;
1428 err = -EFAULT;
1429 break;
1430 }
1431
1432 /*
1433 * Our dirty pages are not counted in nr_dirty,
1434 * and we do not attempt to balance dirty pages.
1435 */
1436
1437 cond_resched();
1438 } while (count);
1439
1440 *ppos = pos;
1441 if (written)
1442 err = written;
1443 out:
1444 up(&inode->i_sem);
1445 return err;
1446 }
1447
1448 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1449 {
1450 struct inode *inode = filp->f_dentry->d_inode;
1451 struct address_space *mapping = inode->i_mapping;
1452 unsigned long index, offset;
1453
1454 index = *ppos >> PAGE_CACHE_SHIFT;
1455 offset = *ppos & ~PAGE_CACHE_MASK;
1456
1457 for (;;) {
1458 struct page *page = NULL;
1459 unsigned long end_index, nr, ret;
1460 loff_t i_size = i_size_read(inode);
1461
1462 end_index = i_size >> PAGE_CACHE_SHIFT;
1463 if (index > end_index)
1464 break;
1465 if (index == end_index) {
1466 nr = i_size & ~PAGE_CACHE_MASK;
1467 if (nr <= offset)
1468 break;
1469 }
1470
1471 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1472 if (desc->error) {
1473 if (desc->error == -EINVAL)
1474 desc->error = 0;
1475 break;
1476 }
1477
1478 /*
1479 * We must evaluate after, since reads (unlike writes)
1480 * are called without i_sem protection against truncate
1481 */
1482 nr = PAGE_CACHE_SIZE;
1483 i_size = i_size_read(inode);
1484 end_index = i_size >> PAGE_CACHE_SHIFT;
1485 if (index == end_index) {
1486 nr = i_size & ~PAGE_CACHE_MASK;
1487 if (nr <= offset) {
1488 if (page)
1489 page_cache_release(page);
1490 break;
1491 }
1492 }
1493 nr -= offset;
1494
1495 if (page) {
1496 /*
1497 * If users can be writing to this page using arbitrary
1498 * virtual addresses, take care about potential aliasing
1499 * before reading the page on the kernel side.
1500 */
1501 if (mapping_writably_mapped(mapping))
1502 flush_dcache_page(page);
1503 /*
1504 * Mark the page accessed if we read the beginning.
1505 */
1506 if (!offset)
1507 mark_page_accessed(page);
1508 } else
1509 page = ZERO_PAGE(0);
1510
1511 /*
1512 * Ok, we have the page, and it's up-to-date, so
1513 * now we can copy it to user space...
1514 *
1515 * The actor routine returns how many bytes were actually used..
1516 * NOTE! This may not be the same as how much of a user buffer
1517 * we filled up (we may be padding etc), so we can only update
1518 * "pos" here (the actor routine has to update the user buffer
1519 * pointers and the remaining count).
1520 */
1521 ret = actor(desc, page, offset, nr);
1522 offset += ret;
1523 index += offset >> PAGE_CACHE_SHIFT;
1524 offset &= ~PAGE_CACHE_MASK;
1525
1526 page_cache_release(page);
1527 if (ret != nr || !desc->count)
1528 break;
1529
1530 cond_resched();
1531 }
1532
1533 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1534 file_accessed(filp);
1535 }
1536
1537 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1538 {
1539 read_descriptor_t desc;
1540
1541 if ((ssize_t) count < 0)
1542 return -EINVAL;
1543 if (!access_ok(VERIFY_WRITE, buf, count))
1544 return -EFAULT;
1545 if (!count)
1546 return 0;
1547
1548 desc.written = 0;
1549 desc.count = count;
1550 desc.arg.buf = buf;
1551 desc.error = 0;
1552
1553 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1554 if (desc.written)
1555 return desc.written;
1556 return desc.error;
1557 }
1558
1559 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1560 size_t count, read_actor_t actor, void *target)
1561 {
1562 read_descriptor_t desc;
1563
1564 if (!count)
1565 return 0;
1566
1567 desc.written = 0;
1568 desc.count = count;
1569 desc.arg.data = target;
1570 desc.error = 0;
1571
1572 do_shmem_file_read(in_file, ppos, &desc, actor);
1573 if (desc.written)
1574 return desc.written;
1575 return desc.error;
1576 }
1577
1578 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1579 {
1580 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1581
1582 buf->f_type = TMPFS_MAGIC;
1583 buf->f_bsize = PAGE_CACHE_SIZE;
1584 buf->f_namelen = NAME_MAX;
1585 spin_lock(&sbinfo->stat_lock);
1586 if (sbinfo->max_blocks) {
1587 buf->f_blocks = sbinfo->max_blocks;
1588 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1589 }
1590 if (sbinfo->max_inodes) {
1591 buf->f_files = sbinfo->max_inodes;
1592 buf->f_ffree = sbinfo->free_inodes;
1593 }
1594 /* else leave those fields 0 like simple_statfs */
1595 spin_unlock(&sbinfo->stat_lock);
1596 return 0;
1597 }
1598
1599 /*
1600 * File creation. Allocate an inode, and we're done..
1601 */
1602 static int
1603 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1604 {
1605 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1606 int error = -ENOSPC;
1607
1608 if (inode) {
1609 if (dir->i_mode & S_ISGID) {
1610 inode->i_gid = dir->i_gid;
1611 if (S_ISDIR(mode))
1612 inode->i_mode |= S_ISGID;
1613 }
1614 dir->i_size += BOGO_DIRENT_SIZE;
1615 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1616 d_instantiate(dentry, inode);
1617 dget(dentry); /* Extra count - pin the dentry in core */
1618 error = 0;
1619 }
1620 return error;
1621 }
1622
1623 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1624 {
1625 int error;
1626
1627 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1628 return error;
1629 dir->i_nlink++;
1630 return 0;
1631 }
1632
1633 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1634 struct nameidata *nd)
1635 {
1636 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1637 }
1638
1639 /*
1640 * Link a file..
1641 */
1642 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1643 {
1644 struct inode *inode = old_dentry->d_inode;
1645 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1646
1647 /*
1648 * No ordinary (disk based) filesystem counts links as inodes;
1649 * but each new link needs a new dentry, pinning lowmem, and
1650 * tmpfs dentries cannot be pruned until they are unlinked.
1651 */
1652 if (sbinfo->max_inodes) {
1653 spin_lock(&sbinfo->stat_lock);
1654 if (!sbinfo->free_inodes) {
1655 spin_unlock(&sbinfo->stat_lock);
1656 return -ENOSPC;
1657 }
1658 sbinfo->free_inodes--;
1659 spin_unlock(&sbinfo->stat_lock);
1660 }
1661
1662 dir->i_size += BOGO_DIRENT_SIZE;
1663 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1664 inode->i_nlink++;
1665 atomic_inc(&inode->i_count); /* New dentry reference */
1666 dget(dentry); /* Extra pinning count for the created dentry */
1667 d_instantiate(dentry, inode);
1668 return 0;
1669 }
1670
1671 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1672 {
1673 struct inode *inode = dentry->d_inode;
1674
1675 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1676 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1677 if (sbinfo->max_inodes) {
1678 spin_lock(&sbinfo->stat_lock);
1679 sbinfo->free_inodes++;
1680 spin_unlock(&sbinfo->stat_lock);
1681 }
1682 }
1683
1684 dir->i_size -= BOGO_DIRENT_SIZE;
1685 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1686 inode->i_nlink--;
1687 dput(dentry); /* Undo the count from "create" - this does all the work */
1688 return 0;
1689 }
1690
1691 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1692 {
1693 if (!simple_empty(dentry))
1694 return -ENOTEMPTY;
1695
1696 dir->i_nlink--;
1697 return shmem_unlink(dir, dentry);
1698 }
1699
1700 /*
1701 * The VFS layer already does all the dentry stuff for rename,
1702 * we just have to decrement the usage count for the target if
1703 * it exists so that the VFS layer correctly free's it when it
1704 * gets overwritten.
1705 */
1706 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1707 {
1708 struct inode *inode = old_dentry->d_inode;
1709 int they_are_dirs = S_ISDIR(inode->i_mode);
1710
1711 if (!simple_empty(new_dentry))
1712 return -ENOTEMPTY;
1713
1714 if (new_dentry->d_inode) {
1715 (void) shmem_unlink(new_dir, new_dentry);
1716 if (they_are_dirs)
1717 old_dir->i_nlink--;
1718 } else if (they_are_dirs) {
1719 old_dir->i_nlink--;
1720 new_dir->i_nlink++;
1721 }
1722
1723 old_dir->i_size -= BOGO_DIRENT_SIZE;
1724 new_dir->i_size += BOGO_DIRENT_SIZE;
1725 old_dir->i_ctime = old_dir->i_mtime =
1726 new_dir->i_ctime = new_dir->i_mtime =
1727 inode->i_ctime = CURRENT_TIME;
1728 return 0;
1729 }
1730
1731 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1732 {
1733 int error;
1734 int len;
1735 struct inode *inode;
1736 struct page *page = NULL;
1737 char *kaddr;
1738 struct shmem_inode_info *info;
1739
1740 len = strlen(symname) + 1;
1741 if (len > PAGE_CACHE_SIZE)
1742 return -ENAMETOOLONG;
1743
1744 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1745 if (!inode)
1746 return -ENOSPC;
1747
1748 info = SHMEM_I(inode);
1749 inode->i_size = len-1;
1750 if (len <= (char *)inode - (char *)info) {
1751 /* do it inline */
1752 memcpy(info, symname, len);
1753 inode->i_op = &shmem_symlink_inline_operations;
1754 } else {
1755 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1756 if (error) {
1757 iput(inode);
1758 return error;
1759 }
1760 inode->i_op = &shmem_symlink_inode_operations;
1761 kaddr = kmap_atomic(page, KM_USER0);
1762 memcpy(kaddr, symname, len);
1763 kunmap_atomic(kaddr, KM_USER0);
1764 set_page_dirty(page);
1765 page_cache_release(page);
1766 }
1767 if (dir->i_mode & S_ISGID)
1768 inode->i_gid = dir->i_gid;
1769 dir->i_size += BOGO_DIRENT_SIZE;
1770 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1771 d_instantiate(dentry, inode);
1772 dget(dentry);
1773 return 0;
1774 }
1775
1776 static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1777 {
1778 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1779 return 0;
1780 }
1781
1782 static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1783 {
1784 struct page *page = NULL;
1785 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1786 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1787 return 0;
1788 }
1789
1790 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
1791 {
1792 if (!IS_ERR(nd_get_link(nd))) {
1793 struct page *page;
1794
1795 page = find_get_page(dentry->d_inode->i_mapping, 0);
1796 if (!page)
1797 BUG();
1798 kunmap(page);
1799 mark_page_accessed(page);
1800 page_cache_release(page);
1801 page_cache_release(page);
1802 }
1803 }
1804
1805 static struct inode_operations shmem_symlink_inline_operations = {
1806 .readlink = generic_readlink,
1807 .follow_link = shmem_follow_link_inline,
1808 #ifdef CONFIG_TMPFS_XATTR
1809 .setxattr = generic_setxattr,
1810 .getxattr = generic_getxattr,
1811 .listxattr = generic_listxattr,
1812 .removexattr = generic_removexattr,
1813 #endif
1814 };
1815
1816 static struct inode_operations shmem_symlink_inode_operations = {
1817 .truncate = shmem_truncate,
1818 .readlink = generic_readlink,
1819 .follow_link = shmem_follow_link,
1820 .put_link = shmem_put_link,
1821 #ifdef CONFIG_TMPFS_XATTR
1822 .setxattr = generic_setxattr,
1823 .getxattr = generic_getxattr,
1824 .listxattr = generic_listxattr,
1825 .removexattr = generic_removexattr,
1826 #endif
1827 };
1828
1829 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
1830 {
1831 char *this_char, *value, *rest;
1832
1833 while ((this_char = strsep(&options, ",")) != NULL) {
1834 if (!*this_char)
1835 continue;
1836 if ((value = strchr(this_char,'=')) != NULL) {
1837 *value++ = 0;
1838 } else {
1839 printk(KERN_ERR
1840 "tmpfs: No value for mount option '%s'\n",
1841 this_char);
1842 return 1;
1843 }
1844
1845 if (!strcmp(this_char,"size")) {
1846 unsigned long long size;
1847 size = memparse(value,&rest);
1848 if (*rest == '%') {
1849 size <<= PAGE_SHIFT;
1850 size *= totalram_pages;
1851 do_div(size, 100);
1852 rest++;
1853 }
1854 if (*rest)
1855 goto bad_val;
1856 *blocks = size >> PAGE_CACHE_SHIFT;
1857 } else if (!strcmp(this_char,"nr_blocks")) {
1858 *blocks = memparse(value,&rest);
1859 if (*rest)
1860 goto bad_val;
1861 } else if (!strcmp(this_char,"nr_inodes")) {
1862 *inodes = memparse(value,&rest);
1863 if (*rest)
1864 goto bad_val;
1865 } else if (!strcmp(this_char,"mode")) {
1866 if (!mode)
1867 continue;
1868 *mode = simple_strtoul(value,&rest,8);
1869 if (*rest)
1870 goto bad_val;
1871 } else if (!strcmp(this_char,"uid")) {
1872 if (!uid)
1873 continue;
1874 *uid = simple_strtoul(value,&rest,0);
1875 if (*rest)
1876 goto bad_val;
1877 } else if (!strcmp(this_char,"gid")) {
1878 if (!gid)
1879 continue;
1880 *gid = simple_strtoul(value,&rest,0);
1881 if (*rest)
1882 goto bad_val;
1883 } else {
1884 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1885 this_char);
1886 return 1;
1887 }
1888 }
1889 return 0;
1890
1891 bad_val:
1892 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1893 value, this_char);
1894 return 1;
1895
1896 }
1897
1898 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1899 {
1900 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1901 unsigned long max_blocks = sbinfo->max_blocks;
1902 unsigned long max_inodes = sbinfo->max_inodes;
1903 unsigned long blocks;
1904 unsigned long inodes;
1905 int error = -EINVAL;
1906
1907 if (shmem_parse_options(data, NULL, NULL, NULL,
1908 &max_blocks, &max_inodes))
1909 return error;
1910
1911 spin_lock(&sbinfo->stat_lock);
1912 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1913 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1914 if (max_blocks < blocks)
1915 goto out;
1916 if (max_inodes < inodes)
1917 goto out;
1918 /*
1919 * Those tests also disallow limited->unlimited while any are in
1920 * use, so i_blocks will always be zero when max_blocks is zero;
1921 * but we must separately disallow unlimited->limited, because
1922 * in that case we have no record of how much is already in use.
1923 */
1924 if (max_blocks && !sbinfo->max_blocks)
1925 goto out;
1926 if (max_inodes && !sbinfo->max_inodes)
1927 goto out;
1928
1929 error = 0;
1930 sbinfo->max_blocks = max_blocks;
1931 sbinfo->free_blocks = max_blocks - blocks;
1932 sbinfo->max_inodes = max_inodes;
1933 sbinfo->free_inodes = max_inodes - inodes;
1934 out:
1935 spin_unlock(&sbinfo->stat_lock);
1936 return error;
1937 }
1938 #endif
1939
1940 static void shmem_put_super(struct super_block *sb)
1941 {
1942 kfree(sb->s_fs_info);
1943 sb->s_fs_info = NULL;
1944 }
1945
1946 #ifdef CONFIG_TMPFS_XATTR
1947 static struct xattr_handler *shmem_xattr_handlers[];
1948 #else
1949 #define shmem_xattr_handlers NULL
1950 #endif
1951
1952 static int shmem_fill_super(struct super_block *sb,
1953 void *data, int silent)
1954 {
1955 struct inode *inode;
1956 struct dentry *root;
1957 int mode = S_IRWXUGO | S_ISVTX;
1958 uid_t uid = current->fsuid;
1959 gid_t gid = current->fsgid;
1960 int err = -ENOMEM;
1961 struct shmem_sb_info *sbinfo;
1962 unsigned long blocks = 0;
1963 unsigned long inodes = 0;
1964
1965 #ifdef CONFIG_TMPFS
1966 /*
1967 * Per default we only allow half of the physical ram per
1968 * tmpfs instance, limiting inodes to one per page of lowmem;
1969 * but the internal instance is left unlimited.
1970 */
1971 if (!(sb->s_flags & MS_NOUSER)) {
1972 blocks = totalram_pages / 2;
1973 inodes = totalram_pages - totalhigh_pages;
1974 if (inodes > blocks)
1975 inodes = blocks;
1976 if (shmem_parse_options(data, &mode, &uid, &gid,
1977 &blocks, &inodes))
1978 return -EINVAL;
1979 }
1980 #else
1981 sb->s_flags |= MS_NOUSER;
1982 #endif
1983
1984 /* Round up to L1_CACHE_BYTES to resist false sharing */
1985 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
1986 L1_CACHE_BYTES), GFP_KERNEL);
1987 if (!sbinfo)
1988 return -ENOMEM;
1989
1990 spin_lock_init(&sbinfo->stat_lock);
1991 sbinfo->max_blocks = blocks;
1992 sbinfo->free_blocks = blocks;
1993 sbinfo->max_inodes = inodes;
1994 sbinfo->free_inodes = inodes;
1995
1996 sb->s_fs_info = sbinfo;
1997 sb->s_maxbytes = SHMEM_MAX_BYTES;
1998 sb->s_blocksize = PAGE_CACHE_SIZE;
1999 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2000 sb->s_magic = TMPFS_MAGIC;
2001 sb->s_op = &shmem_ops;
2002 sb->s_xattr = shmem_xattr_handlers;
2003
2004 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2005 if (!inode)
2006 goto failed;
2007 inode->i_uid = uid;
2008 inode->i_gid = gid;
2009 root = d_alloc_root(inode);
2010 if (!root)
2011 goto failed_iput;
2012 sb->s_root = root;
2013 return 0;
2014
2015 failed_iput:
2016 iput(inode);
2017 failed:
2018 shmem_put_super(sb);
2019 return err;
2020 }
2021
2022 static kmem_cache_t *shmem_inode_cachep;
2023
2024 static struct inode *shmem_alloc_inode(struct super_block *sb)
2025 {
2026 struct shmem_inode_info *p;
2027 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2028 if (!p)
2029 return NULL;
2030 return &p->vfs_inode;
2031 }
2032
2033 static void shmem_destroy_inode(struct inode *inode)
2034 {
2035 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2036 /* only struct inode is valid if it's an inline symlink */
2037 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2038 }
2039 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2040 }
2041
2042 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2043 {
2044 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2045
2046 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2047 SLAB_CTOR_CONSTRUCTOR) {
2048 inode_init_once(&p->vfs_inode);
2049 }
2050 }
2051
2052 static int init_inodecache(void)
2053 {
2054 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2055 sizeof(struct shmem_inode_info),
2056 0, 0, init_once, NULL);
2057 if (shmem_inode_cachep == NULL)
2058 return -ENOMEM;
2059 return 0;
2060 }
2061
2062 static void destroy_inodecache(void)
2063 {
2064 if (kmem_cache_destroy(shmem_inode_cachep))
2065 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2066 }
2067
2068 static struct address_space_operations shmem_aops = {
2069 .writepage = shmem_writepage,
2070 .set_page_dirty = __set_page_dirty_nobuffers,
2071 #ifdef CONFIG_TMPFS
2072 .prepare_write = shmem_prepare_write,
2073 .commit_write = simple_commit_write,
2074 #endif
2075 };
2076
2077 static struct file_operations shmem_file_operations = {
2078 .mmap = shmem_mmap,
2079 #ifdef CONFIG_TMPFS
2080 .llseek = generic_file_llseek,
2081 .read = shmem_file_read,
2082 .write = shmem_file_write,
2083 .fsync = simple_sync_file,
2084 .sendfile = shmem_file_sendfile,
2085 #endif
2086 };
2087
2088 static struct inode_operations shmem_inode_operations = {
2089 .truncate = shmem_truncate,
2090 .setattr = shmem_notify_change,
2091 #ifdef CONFIG_TMPFS_XATTR
2092 .setxattr = generic_setxattr,
2093 .getxattr = generic_getxattr,
2094 .listxattr = generic_listxattr,
2095 .removexattr = generic_removexattr,
2096 #endif
2097 };
2098
2099 static struct inode_operations shmem_dir_inode_operations = {
2100 #ifdef CONFIG_TMPFS
2101 .create = shmem_create,
2102 .lookup = simple_lookup,
2103 .link = shmem_link,
2104 .unlink = shmem_unlink,
2105 .symlink = shmem_symlink,
2106 .mkdir = shmem_mkdir,
2107 .rmdir = shmem_rmdir,
2108 .mknod = shmem_mknod,
2109 .rename = shmem_rename,
2110 #ifdef CONFIG_TMPFS_XATTR
2111 .setxattr = generic_setxattr,
2112 .getxattr = generic_getxattr,
2113 .listxattr = generic_listxattr,
2114 .removexattr = generic_removexattr,
2115 #endif
2116 #endif
2117 };
2118
2119 static struct inode_operations shmem_special_inode_operations = {
2120 #ifdef CONFIG_TMPFS_XATTR
2121 .setxattr = generic_setxattr,
2122 .getxattr = generic_getxattr,
2123 .listxattr = generic_listxattr,
2124 .removexattr = generic_removexattr,
2125 #endif
2126 };
2127
2128 static struct super_operations shmem_ops = {
2129 .alloc_inode = shmem_alloc_inode,
2130 .destroy_inode = shmem_destroy_inode,
2131 #ifdef CONFIG_TMPFS
2132 .statfs = shmem_statfs,
2133 .remount_fs = shmem_remount_fs,
2134 #endif
2135 .delete_inode = shmem_delete_inode,
2136 .drop_inode = generic_delete_inode,
2137 .put_super = shmem_put_super,
2138 };
2139
2140 static struct vm_operations_struct shmem_vm_ops = {
2141 .nopage = shmem_nopage,
2142 .populate = shmem_populate,
2143 #ifdef CONFIG_NUMA
2144 .set_policy = shmem_set_policy,
2145 .get_policy = shmem_get_policy,
2146 #endif
2147 };
2148
2149
2150 #ifdef CONFIG_TMPFS_SECURITY
2151
2152 static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len,
2153 const char *name, size_t name_len)
2154 {
2155 return security_inode_listsecurity(inode, list, list_len);
2156 }
2157
2158 static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size)
2159 {
2160 if (strcmp(name, "") == 0)
2161 return -EINVAL;
2162 return security_inode_getsecurity(inode, name, buffer, size);
2163 }
2164
2165 static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags)
2166 {
2167 if (strcmp(name, "") == 0)
2168 return -EINVAL;
2169 return security_inode_setsecurity(inode, name, value, size, flags);
2170 }
2171
2172 static struct xattr_handler shmem_xattr_security_handler = {
2173 .prefix = XATTR_SECURITY_PREFIX,
2174 .list = shmem_xattr_security_list,
2175 .get = shmem_xattr_security_get,
2176 .set = shmem_xattr_security_set,
2177 };
2178
2179 #endif /* CONFIG_TMPFS_SECURITY */
2180
2181 #ifdef CONFIG_TMPFS_XATTR
2182
2183 static struct xattr_handler *shmem_xattr_handlers[] = {
2184 #ifdef CONFIG_TMPFS_SECURITY
2185 &shmem_xattr_security_handler,
2186 #endif
2187 NULL
2188 };
2189
2190 #endif /* CONFIG_TMPFS_XATTR */
2191
2192 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2193 int flags, const char *dev_name, void *data)
2194 {
2195 return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2196 }
2197
2198 static struct file_system_type tmpfs_fs_type = {
2199 .owner = THIS_MODULE,
2200 .name = "tmpfs",
2201 .get_sb = shmem_get_sb,
2202 .kill_sb = kill_litter_super,
2203 };
2204 static struct vfsmount *shm_mnt;
2205
2206 static int __init init_tmpfs(void)
2207 {
2208 int error;
2209
2210 error = init_inodecache();
2211 if (error)
2212 goto out3;
2213
2214 error = register_filesystem(&tmpfs_fs_type);
2215 if (error) {
2216 printk(KERN_ERR "Could not register tmpfs\n");
2217 goto out2;
2218 }
2219 #ifdef CONFIG_TMPFS
2220 devfs_mk_dir("shm");
2221 #endif
2222 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2223 tmpfs_fs_type.name, NULL);
2224 if (IS_ERR(shm_mnt)) {
2225 error = PTR_ERR(shm_mnt);
2226 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2227 goto out1;
2228 }
2229 return 0;
2230
2231 out1:
2232 unregister_filesystem(&tmpfs_fs_type);
2233 out2:
2234 destroy_inodecache();
2235 out3:
2236 shm_mnt = ERR_PTR(error);
2237 return error;
2238 }
2239 module_init(init_tmpfs)
2240
2241 /*
2242 * shmem_file_setup - get an unlinked file living in tmpfs
2243 *
2244 * @name: name for dentry (to be seen in /proc/<pid>/maps
2245 * @size: size to be set for the file
2246 *
2247 */
2248 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2249 {
2250 int error;
2251 struct file *file;
2252 struct inode *inode;
2253 struct dentry *dentry, *root;
2254 struct qstr this;
2255
2256 if (IS_ERR(shm_mnt))
2257 return (void *)shm_mnt;
2258
2259 if (size < 0 || size > SHMEM_MAX_BYTES)
2260 return ERR_PTR(-EINVAL);
2261
2262 if (shmem_acct_size(flags, size))
2263 return ERR_PTR(-ENOMEM);
2264
2265 error = -ENOMEM;
2266 this.name = name;
2267 this.len = strlen(name);
2268 this.hash = 0; /* will go */
2269 root = shm_mnt->mnt_root;
2270 dentry = d_alloc(root, &this);
2271 if (!dentry)
2272 goto put_memory;
2273
2274 error = -ENFILE;
2275 file = get_empty_filp();
2276 if (!file)
2277 goto put_dentry;
2278
2279 error = -ENOSPC;
2280 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2281 if (!inode)
2282 goto close_file;
2283
2284 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2285 d_instantiate(dentry, inode);
2286 inode->i_size = size;
2287 inode->i_nlink = 0; /* It is unlinked */
2288 file->f_vfsmnt = mntget(shm_mnt);
2289 file->f_dentry = dentry;
2290 file->f_mapping = inode->i_mapping;
2291 file->f_op = &shmem_file_operations;
2292 file->f_mode = FMODE_WRITE | FMODE_READ;
2293 return file;
2294
2295 close_file:
2296 put_filp(file);
2297 put_dentry:
2298 dput(dentry);
2299 put_memory:
2300 shmem_unacct_size(flags, size);
2301 return ERR_PTR(error);
2302 }
2303
2304 /*
2305 * shmem_zero_setup - setup a shared anonymous mapping
2306 *
2307 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2308 */
2309 int shmem_zero_setup(struct vm_area_struct *vma)
2310 {
2311 struct file *file;
2312 loff_t size = vma->vm_end - vma->vm_start;
2313
2314 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2315 if (IS_ERR(file))
2316 return PTR_ERR(file);
2317
2318 if (vma->vm_file)
2319 fput(vma->vm_file);
2320 vma->vm_file = file;
2321 vma->vm_ops = &shmem_vm_ops;
2322 return 0;
2323 }