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[SPARC64] mm: don't re-evaluate *ptep
[linux-2.6.22.y-op.git] / mm / shmem.c
blobdc25565a61e95c1aaacc8b4aa67b4c3862acea4a
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 <asm/uaccess.h>
49 #include <asm/div64.h>
50 #include <asm/pgtable.h>
51
52 /* This magic number is used in glibc for posix shared memory */
53 #define TMPFS_MAGIC 0x01021994
54
55 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
56 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
57 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
58
59 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
60 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
61
62 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
63
64 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
65 #define SHMEM_PAGEIN VM_READ
66 #define SHMEM_TRUNCATE VM_WRITE
67
68 /* Definition to limit shmem_truncate's steps between cond_rescheds */
69 #define LATENCY_LIMIT 64
70
71 /* Pretend that each entry is of this size in directory's i_size */
72 #define BOGO_DIRENT_SIZE 20
73
74 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
75 enum sgp_type {
76 SGP_QUICK, /* don't try more than file page cache lookup */
77 SGP_READ, /* don't exceed i_size, don't allocate page */
78 SGP_CACHE, /* don't exceed i_size, may allocate page */
79 SGP_WRITE, /* may exceed i_size, may allocate page */
80 };
81
82 static int shmem_getpage(struct inode *inode, unsigned long idx,
83 struct page **pagep, enum sgp_type sgp, int *type);
84
85 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
86 {
87 /*
88 * The above definition of ENTRIES_PER_PAGE, and the use of
89 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
90 * might be reconsidered if it ever diverges from PAGE_SIZE.
91 */
92 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
93 }
94
95 static inline void shmem_dir_free(struct page *page)
96 {
97 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
98 }
99
100 static struct page **shmem_dir_map(struct page *page)
101 {
102 return (struct page **)kmap_atomic(page, KM_USER0);
103 }
104
105 static inline void shmem_dir_unmap(struct page **dir)
106 {
107 kunmap_atomic(dir, KM_USER0);
108 }
109
110 static swp_entry_t *shmem_swp_map(struct page *page)
111 {
112 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
113 }
114
115 static inline void shmem_swp_balance_unmap(void)
116 {
117 /*
118 * When passing a pointer to an i_direct entry, to code which
119 * also handles indirect entries and so will shmem_swp_unmap,
120 * we must arrange for the preempt count to remain in balance.
121 * What kmap_atomic of a lowmem page does depends on config
122 * and architecture, so pretend to kmap_atomic some lowmem page.
123 */
124 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
125 }
126
127 static inline void shmem_swp_unmap(swp_entry_t *entry)
128 {
129 kunmap_atomic(entry, KM_USER1);
130 }
131
132 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
133 {
134 return sb->s_fs_info;
135 }
136
137 /*
138 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
139 * for shared memory and for shared anonymous (/dev/zero) mappings
140 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
141 * consistent with the pre-accounting of private mappings ...
142 */
143 static inline int shmem_acct_size(unsigned long flags, loff_t size)
144 {
145 return (flags & VM_ACCOUNT)?
146 security_vm_enough_memory(VM_ACCT(size)): 0;
147 }
148
149 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
150 {
151 if (flags & VM_ACCOUNT)
152 vm_unacct_memory(VM_ACCT(size));
153 }
154
155 /*
156 * ... whereas tmpfs objects are accounted incrementally as
157 * pages are allocated, in order to allow huge sparse files.
158 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
159 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
160 */
161 static inline int shmem_acct_block(unsigned long flags)
162 {
163 return (flags & VM_ACCOUNT)?
164 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
165 }
166
167 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
168 {
169 if (!(flags & VM_ACCOUNT))
170 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
171 }
172
173 static struct super_operations shmem_ops;
174 static struct address_space_operations shmem_aops;
175 static struct file_operations shmem_file_operations;
176 static struct inode_operations shmem_inode_operations;
177 static struct inode_operations shmem_dir_inode_operations;
178 static struct vm_operations_struct shmem_vm_ops;
179
180 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
181 .ra_pages = 0, /* No readahead */
182 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
183 .unplug_io_fn = default_unplug_io_fn,
184 };
185
186 static LIST_HEAD(shmem_swaplist);
187 static DEFINE_SPINLOCK(shmem_swaplist_lock);
188
189 static void shmem_free_blocks(struct inode *inode, long pages)
190 {
191 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
192 if (sbinfo->max_blocks) {
193 spin_lock(&sbinfo->stat_lock);
194 sbinfo->free_blocks += pages;
195 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
196 spin_unlock(&sbinfo->stat_lock);
197 }
198 }
199
200 /*
201 * shmem_recalc_inode - recalculate the size of an inode
202 *
203 * @inode: inode to recalc
204 *
205 * We have to calculate the free blocks since the mm can drop
206 * undirtied hole pages behind our back.
207 *
208 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
209 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
210 *
211 * It has to be called with the spinlock held.
212 */
213 static void shmem_recalc_inode(struct inode *inode)
214 {
215 struct shmem_inode_info *info = SHMEM_I(inode);
216 long freed;
217
218 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
219 if (freed > 0) {
220 info->alloced -= freed;
221 shmem_unacct_blocks(info->flags, freed);
222 shmem_free_blocks(inode, freed);
223 }
224 }
225
226 /*
227 * shmem_swp_entry - find the swap vector position in the info structure
228 *
229 * @info: info structure for the inode
230 * @index: index of the page to find
231 * @page: optional page to add to the structure. Has to be preset to
232 * all zeros
233 *
234 * If there is no space allocated yet it will return NULL when
235 * page is NULL, else it will use the page for the needed block,
236 * setting it to NULL on return to indicate that it has been used.
237 *
238 * The swap vector is organized the following way:
239 *
240 * There are SHMEM_NR_DIRECT entries directly stored in the
241 * shmem_inode_info structure. So small files do not need an addional
242 * allocation.
243 *
244 * For pages with index > SHMEM_NR_DIRECT there is the pointer
245 * i_indirect which points to a page which holds in the first half
246 * doubly indirect blocks, in the second half triple indirect blocks:
247 *
248 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
249 * following layout (for SHMEM_NR_DIRECT == 16):
250 *
251 * i_indirect -> dir --> 16-19
252 * | +-> 20-23
253 * |
254 * +-->dir2 --> 24-27
255 * | +-> 28-31
256 * | +-> 32-35
257 * | +-> 36-39
258 * |
259 * +-->dir3 --> 40-43
260 * +-> 44-47
261 * +-> 48-51
262 * +-> 52-55
263 */
264 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
265 {
266 unsigned long offset;
267 struct page **dir;
268 struct page *subdir;
269
270 if (index < SHMEM_NR_DIRECT) {
271 shmem_swp_balance_unmap();
272 return info->i_direct+index;
273 }
274 if (!info->i_indirect) {
275 if (page) {
276 info->i_indirect = *page;
277 *page = NULL;
278 }
279 return NULL; /* need another page */
280 }
281
282 index -= SHMEM_NR_DIRECT;
283 offset = index % ENTRIES_PER_PAGE;
284 index /= ENTRIES_PER_PAGE;
285 dir = shmem_dir_map(info->i_indirect);
286
287 if (index >= ENTRIES_PER_PAGE/2) {
288 index -= ENTRIES_PER_PAGE/2;
289 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
290 index %= ENTRIES_PER_PAGE;
291 subdir = *dir;
292 if (!subdir) {
293 if (page) {
294 *dir = *page;
295 *page = NULL;
296 }
297 shmem_dir_unmap(dir);
298 return NULL; /* need another page */
299 }
300 shmem_dir_unmap(dir);
301 dir = shmem_dir_map(subdir);
302 }
303
304 dir += index;
305 subdir = *dir;
306 if (!subdir) {
307 if (!page || !(subdir = *page)) {
308 shmem_dir_unmap(dir);
309 return NULL; /* need a page */
310 }
311 *dir = subdir;
312 *page = NULL;
313 }
314 shmem_dir_unmap(dir);
315 return shmem_swp_map(subdir) + offset;
316 }
317
318 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
319 {
320 long incdec = value? 1: -1;
321
322 entry->val = value;
323 info->swapped += incdec;
324 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
325 struct page *page = kmap_atomic_to_page(entry);
326 set_page_private(page, page_private(page) + incdec);
327 }
328 }
329
330 /*
331 * shmem_swp_alloc - get the position of the swap entry for the page.
332 * If it does not exist allocate the entry.
333 *
334 * @info: info structure for the inode
335 * @index: index of the page to find
336 * @sgp: check and recheck i_size? skip allocation?
337 */
338 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
339 {
340 struct inode *inode = &info->vfs_inode;
341 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
342 struct page *page = NULL;
343 swp_entry_t *entry;
344
345 if (sgp != SGP_WRITE &&
346 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
347 return ERR_PTR(-EINVAL);
348
349 while (!(entry = shmem_swp_entry(info, index, &page))) {
350 if (sgp == SGP_READ)
351 return shmem_swp_map(ZERO_PAGE(0));
352 /*
353 * Test free_blocks against 1 not 0, since we have 1 data
354 * page (and perhaps indirect index pages) yet to allocate:
355 * a waste to allocate index if we cannot allocate data.
356 */
357 if (sbinfo->max_blocks) {
358 spin_lock(&sbinfo->stat_lock);
359 if (sbinfo->free_blocks <= 1) {
360 spin_unlock(&sbinfo->stat_lock);
361 return ERR_PTR(-ENOSPC);
362 }
363 sbinfo->free_blocks--;
364 inode->i_blocks += BLOCKS_PER_PAGE;
365 spin_unlock(&sbinfo->stat_lock);
366 }
367
368 spin_unlock(&info->lock);
369 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
370 if (page)
371 set_page_private(page, 0);
372 spin_lock(&info->lock);
373
374 if (!page) {
375 shmem_free_blocks(inode, 1);
376 return ERR_PTR(-ENOMEM);
377 }
378 if (sgp != SGP_WRITE &&
379 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
380 entry = ERR_PTR(-EINVAL);
381 break;
382 }
383 if (info->next_index <= index)
384 info->next_index = index + 1;
385 }
386 if (page) {
387 /* another task gave its page, or truncated the file */
388 shmem_free_blocks(inode, 1);
389 shmem_dir_free(page);
390 }
391 if (info->next_index <= index && !IS_ERR(entry))
392 info->next_index = index + 1;
393 return entry;
394 }
395
396 /*
397 * shmem_free_swp - free some swap entries in a directory
398 *
399 * @dir: pointer to the directory
400 * @edir: pointer after last entry of the directory
401 */
402 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
403 {
404 swp_entry_t *ptr;
405 int freed = 0;
406
407 for (ptr = dir; ptr < edir; ptr++) {
408 if (ptr->val) {
409 free_swap_and_cache(*ptr);
410 *ptr = (swp_entry_t){0};
411 freed++;
412 }
413 }
414 return freed;
415 }
416
417 static int shmem_map_and_free_swp(struct page *subdir,
418 int offset, int limit, struct page ***dir)
419 {
420 swp_entry_t *ptr;
421 int freed = 0;
422
423 ptr = shmem_swp_map(subdir);
424 for (; offset < limit; offset += LATENCY_LIMIT) {
425 int size = limit - offset;
426 if (size > LATENCY_LIMIT)
427 size = LATENCY_LIMIT;
428 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
429 if (need_resched()) {
430 shmem_swp_unmap(ptr);
431 if (*dir) {
432 shmem_dir_unmap(*dir);
433 *dir = NULL;
434 }
435 cond_resched();
436 ptr = shmem_swp_map(subdir);
437 }
438 }
439 shmem_swp_unmap(ptr);
440 return freed;
441 }
442
443 static void shmem_free_pages(struct list_head *next)
444 {
445 struct page *page;
446 int freed = 0;
447
448 do {
449 page = container_of(next, struct page, lru);
450 next = next->next;
451 shmem_dir_free(page);
452 freed++;
453 if (freed >= LATENCY_LIMIT) {
454 cond_resched();
455 freed = 0;
456 }
457 } while (next);
458 }
459
460 static void shmem_truncate(struct inode *inode)
461 {
462 struct shmem_inode_info *info = SHMEM_I(inode);
463 unsigned long idx;
464 unsigned long size;
465 unsigned long limit;
466 unsigned long stage;
467 unsigned long diroff;
468 struct page **dir;
469 struct page *topdir;
470 struct page *middir;
471 struct page *subdir;
472 swp_entry_t *ptr;
473 LIST_HEAD(pages_to_free);
474 long nr_pages_to_free = 0;
475 long nr_swaps_freed = 0;
476 int offset;
477 int freed;
478
479 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
480 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
481 if (idx >= info->next_index)
482 return;
483
484 spin_lock(&info->lock);
485 info->flags |= SHMEM_TRUNCATE;
486 limit = info->next_index;
487 info->next_index = idx;
488 topdir = info->i_indirect;
489 if (topdir && idx <= SHMEM_NR_DIRECT) {
490 info->i_indirect = NULL;
491 nr_pages_to_free++;
492 list_add(&topdir->lru, &pages_to_free);
493 }
494 spin_unlock(&info->lock);
495
496 if (info->swapped && idx < SHMEM_NR_DIRECT) {
497 ptr = info->i_direct;
498 size = limit;
499 if (size > SHMEM_NR_DIRECT)
500 size = SHMEM_NR_DIRECT;
501 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
502 }
503 if (!topdir)
504 goto done2;
505
506 BUG_ON(limit <= SHMEM_NR_DIRECT);
507 limit -= SHMEM_NR_DIRECT;
508 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
509 offset = idx % ENTRIES_PER_PAGE;
510 idx -= offset;
511
512 dir = shmem_dir_map(topdir);
513 stage = ENTRIES_PER_PAGEPAGE/2;
514 if (idx < ENTRIES_PER_PAGEPAGE/2) {
515 middir = topdir;
516 diroff = idx/ENTRIES_PER_PAGE;
517 } else {
518 dir += ENTRIES_PER_PAGE/2;
519 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
520 while (stage <= idx)
521 stage += ENTRIES_PER_PAGEPAGE;
522 middir = *dir;
523 if (*dir) {
524 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
525 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
526 if (!diroff && !offset) {
527 *dir = NULL;
528 nr_pages_to_free++;
529 list_add(&middir->lru, &pages_to_free);
530 }
531 shmem_dir_unmap(dir);
532 dir = shmem_dir_map(middir);
533 } else {
534 diroff = 0;
535 offset = 0;
536 idx = stage;
537 }
538 }
539
540 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
541 if (unlikely(idx == stage)) {
542 shmem_dir_unmap(dir);
543 dir = shmem_dir_map(topdir) +
544 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
545 while (!*dir) {
546 dir++;
547 idx += ENTRIES_PER_PAGEPAGE;
548 if (idx >= limit)
549 goto done1;
550 }
551 stage = idx + ENTRIES_PER_PAGEPAGE;
552 middir = *dir;
553 *dir = NULL;
554 nr_pages_to_free++;
555 list_add(&middir->lru, &pages_to_free);
556 shmem_dir_unmap(dir);
557 cond_resched();
558 dir = shmem_dir_map(middir);
559 diroff = 0;
560 }
561 subdir = dir[diroff];
562 if (subdir && page_private(subdir)) {
563 size = limit - idx;
564 if (size > ENTRIES_PER_PAGE)
565 size = ENTRIES_PER_PAGE;
566 freed = shmem_map_and_free_swp(subdir,
567 offset, size, &dir);
568 if (!dir)
569 dir = shmem_dir_map(middir);
570 nr_swaps_freed += freed;
571 if (offset)
572 spin_lock(&info->lock);
573 set_page_private(subdir, page_private(subdir) - freed);
574 if (offset)
575 spin_unlock(&info->lock);
576 BUG_ON(page_private(subdir) > offset);
577 }
578 if (offset)
579 offset = 0;
580 else if (subdir) {
581 dir[diroff] = NULL;
582 nr_pages_to_free++;
583 list_add(&subdir->lru, &pages_to_free);
584 }
585 }
586 done1:
587 shmem_dir_unmap(dir);
588 done2:
589 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
590 /*
591 * Call truncate_inode_pages again: racing shmem_unuse_inode
592 * may have swizzled a page in from swap since vmtruncate or
593 * generic_delete_inode did it, before we lowered next_index.
594 * Also, though shmem_getpage checks i_size before adding to
595 * cache, no recheck after: so fix the narrow window there too.
596 */
597 truncate_inode_pages(inode->i_mapping, inode->i_size);
598 }
599
600 spin_lock(&info->lock);
601 info->flags &= ~SHMEM_TRUNCATE;
602 info->swapped -= nr_swaps_freed;
603 if (nr_pages_to_free)
604 shmem_free_blocks(inode, nr_pages_to_free);
605 shmem_recalc_inode(inode);
606 spin_unlock(&info->lock);
607
608 /*
609 * Empty swap vector directory pages to be freed?
610 */
611 if (!list_empty(&pages_to_free)) {
612 pages_to_free.prev->next = NULL;
613 shmem_free_pages(pages_to_free.next);
614 }
615 }
616
617 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
618 {
619 struct inode *inode = dentry->d_inode;
620 struct page *page = NULL;
621 int error;
622
623 if (attr->ia_valid & ATTR_SIZE) {
624 if (attr->ia_size < inode->i_size) {
625 /*
626 * If truncating down to a partial page, then
627 * if that page is already allocated, hold it
628 * in memory until the truncation is over, so
629 * truncate_partial_page cannnot miss it were
630 * it assigned to swap.
631 */
632 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
633 (void) shmem_getpage(inode,
634 attr->ia_size>>PAGE_CACHE_SHIFT,
635 &page, SGP_READ, NULL);
636 }
637 /*
638 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
639 * detect if any pages might have been added to cache
640 * after truncate_inode_pages. But we needn't bother
641 * if it's being fully truncated to zero-length: the
642 * nrpages check is efficient enough in that case.
643 */
644 if (attr->ia_size) {
645 struct shmem_inode_info *info = SHMEM_I(inode);
646 spin_lock(&info->lock);
647 info->flags &= ~SHMEM_PAGEIN;
648 spin_unlock(&info->lock);
649 }
650 }
651 }
652
653 error = inode_change_ok(inode, attr);
654 if (!error)
655 error = inode_setattr(inode, attr);
656 if (page)
657 page_cache_release(page);
658 return error;
659 }
660
661 static void shmem_delete_inode(struct inode *inode)
662 {
663 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
664 struct shmem_inode_info *info = SHMEM_I(inode);
665
666 if (inode->i_op->truncate == shmem_truncate) {
667 truncate_inode_pages(inode->i_mapping, 0);
668 shmem_unacct_size(info->flags, inode->i_size);
669 inode->i_size = 0;
670 shmem_truncate(inode);
671 if (!list_empty(&info->swaplist)) {
672 spin_lock(&shmem_swaplist_lock);
673 list_del_init(&info->swaplist);
674 spin_unlock(&shmem_swaplist_lock);
675 }
676 }
677 BUG_ON(inode->i_blocks);
678 if (sbinfo->max_inodes) {
679 spin_lock(&sbinfo->stat_lock);
680 sbinfo->free_inodes++;
681 spin_unlock(&sbinfo->stat_lock);
682 }
683 clear_inode(inode);
684 }
685
686 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
687 {
688 swp_entry_t *ptr;
689
690 for (ptr = dir; ptr < edir; ptr++) {
691 if (ptr->val == entry.val)
692 return ptr - dir;
693 }
694 return -1;
695 }
696
697 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
698 {
699 struct inode *inode;
700 unsigned long idx;
701 unsigned long size;
702 unsigned long limit;
703 unsigned long stage;
704 struct page **dir;
705 struct page *subdir;
706 swp_entry_t *ptr;
707 int offset;
708
709 idx = 0;
710 ptr = info->i_direct;
711 spin_lock(&info->lock);
712 limit = info->next_index;
713 size = limit;
714 if (size > SHMEM_NR_DIRECT)
715 size = SHMEM_NR_DIRECT;
716 offset = shmem_find_swp(entry, ptr, ptr+size);
717 if (offset >= 0) {
718 shmem_swp_balance_unmap();
719 goto found;
720 }
721 if (!info->i_indirect)
722 goto lost2;
723
724 dir = shmem_dir_map(info->i_indirect);
725 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
726
727 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
728 if (unlikely(idx == stage)) {
729 shmem_dir_unmap(dir-1);
730 dir = shmem_dir_map(info->i_indirect) +
731 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
732 while (!*dir) {
733 dir++;
734 idx += ENTRIES_PER_PAGEPAGE;
735 if (idx >= limit)
736 goto lost1;
737 }
738 stage = idx + ENTRIES_PER_PAGEPAGE;
739 subdir = *dir;
740 shmem_dir_unmap(dir);
741 dir = shmem_dir_map(subdir);
742 }
743 subdir = *dir;
744 if (subdir && page_private(subdir)) {
745 ptr = shmem_swp_map(subdir);
746 size = limit - idx;
747 if (size > ENTRIES_PER_PAGE)
748 size = ENTRIES_PER_PAGE;
749 offset = shmem_find_swp(entry, ptr, ptr+size);
750 if (offset >= 0) {
751 shmem_dir_unmap(dir);
752 goto found;
753 }
754 shmem_swp_unmap(ptr);
755 }
756 }
757 lost1:
758 shmem_dir_unmap(dir-1);
759 lost2:
760 spin_unlock(&info->lock);
761 return 0;
762 found:
763 idx += offset;
764 inode = &info->vfs_inode;
765 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
766 info->flags |= SHMEM_PAGEIN;
767 shmem_swp_set(info, ptr + offset, 0);
768 }
769 shmem_swp_unmap(ptr);
770 spin_unlock(&info->lock);
771 /*
772 * Decrement swap count even when the entry is left behind:
773 * try_to_unuse will skip over mms, then reincrement count.
774 */
775 swap_free(entry);
776 return 1;
777 }
778
779 /*
780 * shmem_unuse() search for an eventually swapped out shmem page.
781 */
782 int shmem_unuse(swp_entry_t entry, struct page *page)
783 {
784 struct list_head *p, *next;
785 struct shmem_inode_info *info;
786 int found = 0;
787
788 spin_lock(&shmem_swaplist_lock);
789 list_for_each_safe(p, next, &shmem_swaplist) {
790 info = list_entry(p, struct shmem_inode_info, swaplist);
791 if (!info->swapped)
792 list_del_init(&info->swaplist);
793 else if (shmem_unuse_inode(info, entry, page)) {
794 /* move head to start search for next from here */
795 list_move_tail(&shmem_swaplist, &info->swaplist);
796 found = 1;
797 break;
798 }
799 }
800 spin_unlock(&shmem_swaplist_lock);
801 return found;
802 }
803
804 /*
805 * Move the page from the page cache to the swap cache.
806 */
807 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
808 {
809 struct shmem_inode_info *info;
810 swp_entry_t *entry, swap;
811 struct address_space *mapping;
812 unsigned long index;
813 struct inode *inode;
814
815 BUG_ON(!PageLocked(page));
816 BUG_ON(page_mapped(page));
817
818 mapping = page->mapping;
819 index = page->index;
820 inode = mapping->host;
821 info = SHMEM_I(inode);
822 if (info->flags & VM_LOCKED)
823 goto redirty;
824 swap = get_swap_page();
825 if (!swap.val)
826 goto redirty;
827
828 spin_lock(&info->lock);
829 shmem_recalc_inode(inode);
830 if (index >= info->next_index) {
831 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
832 goto unlock;
833 }
834 entry = shmem_swp_entry(info, index, NULL);
835 BUG_ON(!entry);
836 BUG_ON(entry->val);
837
838 if (move_to_swap_cache(page, swap) == 0) {
839 shmem_swp_set(info, entry, swap.val);
840 shmem_swp_unmap(entry);
841 spin_unlock(&info->lock);
842 if (list_empty(&info->swaplist)) {
843 spin_lock(&shmem_swaplist_lock);
844 /* move instead of add in case we're racing */
845 list_move_tail(&info->swaplist, &shmem_swaplist);
846 spin_unlock(&shmem_swaplist_lock);
847 }
848 unlock_page(page);
849 return 0;
850 }
851
852 shmem_swp_unmap(entry);
853 unlock:
854 spin_unlock(&info->lock);
855 swap_free(swap);
856 redirty:
857 set_page_dirty(page);
858 return WRITEPAGE_ACTIVATE; /* Return with the page locked */
859 }
860
861 #ifdef CONFIG_NUMA
862 static struct page *shmem_swapin_async(struct shared_policy *p,
863 swp_entry_t entry, unsigned long idx)
864 {
865 struct page *page;
866 struct vm_area_struct pvma;
867
868 /* Create a pseudo vma that just contains the policy */
869 memset(&pvma, 0, sizeof(struct vm_area_struct));
870 pvma.vm_end = PAGE_SIZE;
871 pvma.vm_pgoff = idx;
872 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
873 page = read_swap_cache_async(entry, &pvma, 0);
874 mpol_free(pvma.vm_policy);
875 return page;
876 }
877
878 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
879 unsigned long idx)
880 {
881 struct shared_policy *p = &info->policy;
882 int i, num;
883 struct page *page;
884 unsigned long offset;
885
886 num = valid_swaphandles(entry, &offset);
887 for (i = 0; i < num; offset++, i++) {
888 page = shmem_swapin_async(p,
889 swp_entry(swp_type(entry), offset), idx);
890 if (!page)
891 break;
892 page_cache_release(page);
893 }
894 lru_add_drain(); /* Push any new pages onto the LRU now */
895 return shmem_swapin_async(p, entry, idx);
896 }
897
898 static struct page *
899 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
900 unsigned long idx)
901 {
902 struct vm_area_struct pvma;
903 struct page *page;
904
905 memset(&pvma, 0, sizeof(struct vm_area_struct));
906 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
907 pvma.vm_pgoff = idx;
908 pvma.vm_end = PAGE_SIZE;
909 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
910 mpol_free(pvma.vm_policy);
911 return page;
912 }
913 #else
914 static inline struct page *
915 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
916 {
917 swapin_readahead(entry, 0, NULL);
918 return read_swap_cache_async(entry, NULL, 0);
919 }
920
921 static inline struct page *
922 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
923 {
924 return alloc_page(gfp | __GFP_ZERO);
925 }
926 #endif
927
928 /*
929 * shmem_getpage - either get the page from swap or allocate a new one
930 *
931 * If we allocate a new one we do not mark it dirty. That's up to the
932 * vm. If we swap it in we mark it dirty since we also free the swap
933 * entry since a page cannot live in both the swap and page cache
934 */
935 static int shmem_getpage(struct inode *inode, unsigned long idx,
936 struct page **pagep, enum sgp_type sgp, int *type)
937 {
938 struct address_space *mapping = inode->i_mapping;
939 struct shmem_inode_info *info = SHMEM_I(inode);
940 struct shmem_sb_info *sbinfo;
941 struct page *filepage = *pagep;
942 struct page *swappage;
943 swp_entry_t *entry;
944 swp_entry_t swap;
945 int error;
946
947 if (idx >= SHMEM_MAX_INDEX)
948 return -EFBIG;
949 /*
950 * Normally, filepage is NULL on entry, and either found
951 * uptodate immediately, or allocated and zeroed, or read
952 * in under swappage, which is then assigned to filepage.
953 * But shmem_prepare_write passes in a locked filepage,
954 * which may be found not uptodate by other callers too,
955 * and may need to be copied from the swappage read in.
956 */
957 repeat:
958 if (!filepage)
959 filepage = find_lock_page(mapping, idx);
960 if (filepage && PageUptodate(filepage))
961 goto done;
962 error = 0;
963 if (sgp == SGP_QUICK)
964 goto failed;
965
966 spin_lock(&info->lock);
967 shmem_recalc_inode(inode);
968 entry = shmem_swp_alloc(info, idx, sgp);
969 if (IS_ERR(entry)) {
970 spin_unlock(&info->lock);
971 error = PTR_ERR(entry);
972 goto failed;
973 }
974 swap = *entry;
975
976 if (swap.val) {
977 /* Look it up and read it in.. */
978 swappage = lookup_swap_cache(swap);
979 if (!swappage) {
980 shmem_swp_unmap(entry);
981 spin_unlock(&info->lock);
982 /* here we actually do the io */
983 if (type && *type == VM_FAULT_MINOR) {
984 inc_page_state(pgmajfault);
985 *type = VM_FAULT_MAJOR;
986 }
987 swappage = shmem_swapin(info, swap, idx);
988 if (!swappage) {
989 spin_lock(&info->lock);
990 entry = shmem_swp_alloc(info, idx, sgp);
991 if (IS_ERR(entry))
992 error = PTR_ERR(entry);
993 else {
994 if (entry->val == swap.val)
995 error = -ENOMEM;
996 shmem_swp_unmap(entry);
997 }
998 spin_unlock(&info->lock);
999 if (error)
1000 goto failed;
1001 goto repeat;
1002 }
1003 wait_on_page_locked(swappage);
1004 page_cache_release(swappage);
1005 goto repeat;
1006 }
1007
1008 /* We have to do this with page locked to prevent races */
1009 if (TestSetPageLocked(swappage)) {
1010 shmem_swp_unmap(entry);
1011 spin_unlock(&info->lock);
1012 wait_on_page_locked(swappage);
1013 page_cache_release(swappage);
1014 goto repeat;
1015 }
1016 if (PageWriteback(swappage)) {
1017 shmem_swp_unmap(entry);
1018 spin_unlock(&info->lock);
1019 wait_on_page_writeback(swappage);
1020 unlock_page(swappage);
1021 page_cache_release(swappage);
1022 goto repeat;
1023 }
1024 if (!PageUptodate(swappage)) {
1025 shmem_swp_unmap(entry);
1026 spin_unlock(&info->lock);
1027 unlock_page(swappage);
1028 page_cache_release(swappage);
1029 error = -EIO;
1030 goto failed;
1031 }
1032
1033 if (filepage) {
1034 shmem_swp_set(info, entry, 0);
1035 shmem_swp_unmap(entry);
1036 delete_from_swap_cache(swappage);
1037 spin_unlock(&info->lock);
1038 copy_highpage(filepage, swappage);
1039 unlock_page(swappage);
1040 page_cache_release(swappage);
1041 flush_dcache_page(filepage);
1042 SetPageUptodate(filepage);
1043 set_page_dirty(filepage);
1044 swap_free(swap);
1045 } else if (!(error = move_from_swap_cache(
1046 swappage, idx, mapping))) {
1047 info->flags |= SHMEM_PAGEIN;
1048 shmem_swp_set(info, entry, 0);
1049 shmem_swp_unmap(entry);
1050 spin_unlock(&info->lock);
1051 filepage = swappage;
1052 swap_free(swap);
1053 } else {
1054 shmem_swp_unmap(entry);
1055 spin_unlock(&info->lock);
1056 unlock_page(swappage);
1057 page_cache_release(swappage);
1058 if (error == -ENOMEM) {
1059 /* let kswapd refresh zone for GFP_ATOMICs */
1060 blk_congestion_wait(WRITE, HZ/50);
1061 }
1062 goto repeat;
1063 }
1064 } else if (sgp == SGP_READ && !filepage) {
1065 shmem_swp_unmap(entry);
1066 filepage = find_get_page(mapping, idx);
1067 if (filepage &&
1068 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1069 spin_unlock(&info->lock);
1070 wait_on_page_locked(filepage);
1071 page_cache_release(filepage);
1072 filepage = NULL;
1073 goto repeat;
1074 }
1075 spin_unlock(&info->lock);
1076 } else {
1077 shmem_swp_unmap(entry);
1078 sbinfo = SHMEM_SB(inode->i_sb);
1079 if (sbinfo->max_blocks) {
1080 spin_lock(&sbinfo->stat_lock);
1081 if (sbinfo->free_blocks == 0 ||
1082 shmem_acct_block(info->flags)) {
1083 spin_unlock(&sbinfo->stat_lock);
1084 spin_unlock(&info->lock);
1085 error = -ENOSPC;
1086 goto failed;
1087 }
1088 sbinfo->free_blocks--;
1089 inode->i_blocks += BLOCKS_PER_PAGE;
1090 spin_unlock(&sbinfo->stat_lock);
1091 } else if (shmem_acct_block(info->flags)) {
1092 spin_unlock(&info->lock);
1093 error = -ENOSPC;
1094 goto failed;
1095 }
1096
1097 if (!filepage) {
1098 spin_unlock(&info->lock);
1099 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1100 info,
1101 idx);
1102 if (!filepage) {
1103 shmem_unacct_blocks(info->flags, 1);
1104 shmem_free_blocks(inode, 1);
1105 error = -ENOMEM;
1106 goto failed;
1107 }
1108
1109 spin_lock(&info->lock);
1110 entry = shmem_swp_alloc(info, idx, sgp);
1111 if (IS_ERR(entry))
1112 error = PTR_ERR(entry);
1113 else {
1114 swap = *entry;
1115 shmem_swp_unmap(entry);
1116 }
1117 if (error || swap.val || 0 != add_to_page_cache_lru(
1118 filepage, mapping, idx, GFP_ATOMIC)) {
1119 spin_unlock(&info->lock);
1120 page_cache_release(filepage);
1121 shmem_unacct_blocks(info->flags, 1);
1122 shmem_free_blocks(inode, 1);
1123 filepage = NULL;
1124 if (error)
1125 goto failed;
1126 goto repeat;
1127 }
1128 info->flags |= SHMEM_PAGEIN;
1129 }
1130
1131 info->alloced++;
1132 spin_unlock(&info->lock);
1133 flush_dcache_page(filepage);
1134 SetPageUptodate(filepage);
1135 }
1136 done:
1137 if (*pagep != filepage) {
1138 unlock_page(filepage);
1139 *pagep = filepage;
1140 }
1141 return 0;
1142
1143 failed:
1144 if (*pagep != filepage) {
1145 unlock_page(filepage);
1146 page_cache_release(filepage);
1147 }
1148 return error;
1149 }
1150
1151 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1152 {
1153 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1154 struct page *page = NULL;
1155 unsigned long idx;
1156 int error;
1157
1158 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1159 idx += vma->vm_pgoff;
1160 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1161 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1162 return NOPAGE_SIGBUS;
1163
1164 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1165 if (error)
1166 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1167
1168 mark_page_accessed(page);
1169 return page;
1170 }
1171
1172 static int shmem_populate(struct vm_area_struct *vma,
1173 unsigned long addr, unsigned long len,
1174 pgprot_t prot, unsigned long pgoff, int nonblock)
1175 {
1176 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1177 struct mm_struct *mm = vma->vm_mm;
1178 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1179 unsigned long size;
1180
1181 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1182 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1183 return -EINVAL;
1184
1185 while ((long) len > 0) {
1186 struct page *page = NULL;
1187 int err;
1188 /*
1189 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1190 */
1191 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1192 if (err)
1193 return err;
1194 /* Page may still be null, but only if nonblock was set. */
1195 if (page) {
1196 mark_page_accessed(page);
1197 err = install_page(mm, vma, addr, page, prot);
1198 if (err) {
1199 page_cache_release(page);
1200 return err;
1201 }
1202 } else if (vma->vm_flags & VM_NONLINEAR) {
1203 /* No page was found just because we can't read it in
1204 * now (being here implies nonblock != 0), but the page
1205 * may exist, so set the PTE to fault it in later. */
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 init_special_inode(inode, mode, dev);
1300 break;
1301 case S_IFREG:
1302 inode->i_op = &shmem_inode_operations;
1303 inode->i_fop = &shmem_file_operations;
1304 mpol_shared_policy_init(&info->policy);
1305 break;
1306 case S_IFDIR:
1307 inode->i_nlink++;
1308 /* Some things misbehave if size == 0 on a directory */
1309 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1310 inode->i_op = &shmem_dir_inode_operations;
1311 inode->i_fop = &simple_dir_operations;
1312 break;
1313 case S_IFLNK:
1314 /*
1315 * Must not load anything in the rbtree,
1316 * mpol_free_shared_policy will not be called.
1317 */
1318 mpol_shared_policy_init(&info->policy);
1319 break;
1320 }
1321 } else if (sbinfo->max_inodes) {
1322 spin_lock(&sbinfo->stat_lock);
1323 sbinfo->free_inodes++;
1324 spin_unlock(&sbinfo->stat_lock);
1325 }
1326 return inode;
1327 }
1328
1329 #ifdef CONFIG_TMPFS
1330 static struct inode_operations shmem_symlink_inode_operations;
1331 static struct inode_operations shmem_symlink_inline_operations;
1332
1333 /*
1334 * Normally tmpfs makes no use of shmem_prepare_write, but it
1335 * lets a tmpfs file be used read-write below the loop driver.
1336 */
1337 static int
1338 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1339 {
1340 struct inode *inode = page->mapping->host;
1341 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1342 }
1343
1344 static ssize_t
1345 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1346 {
1347 struct inode *inode = file->f_dentry->d_inode;
1348 loff_t pos;
1349 unsigned long written;
1350 ssize_t err;
1351
1352 if ((ssize_t) count < 0)
1353 return -EINVAL;
1354
1355 if (!access_ok(VERIFY_READ, buf, count))
1356 return -EFAULT;
1357
1358 down(&inode->i_sem);
1359
1360 pos = *ppos;
1361 written = 0;
1362
1363 err = generic_write_checks(file, &pos, &count, 0);
1364 if (err || !count)
1365 goto out;
1366
1367 err = remove_suid(file->f_dentry);
1368 if (err)
1369 goto out;
1370
1371 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1372
1373 do {
1374 struct page *page = NULL;
1375 unsigned long bytes, index, offset;
1376 char *kaddr;
1377 int left;
1378
1379 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1380 index = pos >> PAGE_CACHE_SHIFT;
1381 bytes = PAGE_CACHE_SIZE - offset;
1382 if (bytes > count)
1383 bytes = count;
1384
1385 /*
1386 * We don't hold page lock across copy from user -
1387 * what would it guard against? - so no deadlock here.
1388 * But it still may be a good idea to prefault below.
1389 */
1390
1391 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1392 if (err)
1393 break;
1394
1395 left = bytes;
1396 if (PageHighMem(page)) {
1397 volatile unsigned char dummy;
1398 __get_user(dummy, buf);
1399 __get_user(dummy, buf + bytes - 1);
1400
1401 kaddr = kmap_atomic(page, KM_USER0);
1402 left = __copy_from_user_inatomic(kaddr + offset,
1403 buf, bytes);
1404 kunmap_atomic(kaddr, KM_USER0);
1405 }
1406 if (left) {
1407 kaddr = kmap(page);
1408 left = __copy_from_user(kaddr + offset, buf, bytes);
1409 kunmap(page);
1410 }
1411
1412 written += bytes;
1413 count -= bytes;
1414 pos += bytes;
1415 buf += bytes;
1416 if (pos > inode->i_size)
1417 i_size_write(inode, pos);
1418
1419 flush_dcache_page(page);
1420 set_page_dirty(page);
1421 mark_page_accessed(page);
1422 page_cache_release(page);
1423
1424 if (left) {
1425 pos -= left;
1426 written -= left;
1427 err = -EFAULT;
1428 break;
1429 }
1430
1431 /*
1432 * Our dirty pages are not counted in nr_dirty,
1433 * and we do not attempt to balance dirty pages.
1434 */
1435
1436 cond_resched();
1437 } while (count);
1438
1439 *ppos = pos;
1440 if (written)
1441 err = written;
1442 out:
1443 up(&inode->i_sem);
1444 return err;
1445 }
1446
1447 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1448 {
1449 struct inode *inode = filp->f_dentry->d_inode;
1450 struct address_space *mapping = inode->i_mapping;
1451 unsigned long index, offset;
1452
1453 index = *ppos >> PAGE_CACHE_SHIFT;
1454 offset = *ppos & ~PAGE_CACHE_MASK;
1455
1456 for (;;) {
1457 struct page *page = NULL;
1458 unsigned long end_index, nr, ret;
1459 loff_t i_size = i_size_read(inode);
1460
1461 end_index = i_size >> PAGE_CACHE_SHIFT;
1462 if (index > end_index)
1463 break;
1464 if (index == end_index) {
1465 nr = i_size & ~PAGE_CACHE_MASK;
1466 if (nr <= offset)
1467 break;
1468 }
1469
1470 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1471 if (desc->error) {
1472 if (desc->error == -EINVAL)
1473 desc->error = 0;
1474 break;
1475 }
1476
1477 /*
1478 * We must evaluate after, since reads (unlike writes)
1479 * are called without i_sem protection against truncate
1480 */
1481 nr = PAGE_CACHE_SIZE;
1482 i_size = i_size_read(inode);
1483 end_index = i_size >> PAGE_CACHE_SHIFT;
1484 if (index == end_index) {
1485 nr = i_size & ~PAGE_CACHE_MASK;
1486 if (nr <= offset) {
1487 if (page)
1488 page_cache_release(page);
1489 break;
1490 }
1491 }
1492 nr -= offset;
1493
1494 if (page) {
1495 /*
1496 * If users can be writing to this page using arbitrary
1497 * virtual addresses, take care about potential aliasing
1498 * before reading the page on the kernel side.
1499 */
1500 if (mapping_writably_mapped(mapping))
1501 flush_dcache_page(page);
1502 /*
1503 * Mark the page accessed if we read the beginning.
1504 */
1505 if (!offset)
1506 mark_page_accessed(page);
1507 } else {
1508 page = ZERO_PAGE(0);
1509 page_cache_get(page);
1510 }
1511
1512 /*
1513 * Ok, we have the page, and it's up-to-date, so
1514 * now we can copy it to user space...
1515 *
1516 * The actor routine returns how many bytes were actually used..
1517 * NOTE! This may not be the same as how much of a user buffer
1518 * we filled up (we may be padding etc), so we can only update
1519 * "pos" here (the actor routine has to update the user buffer
1520 * pointers and the remaining count).
1521 */
1522 ret = actor(desc, page, offset, nr);
1523 offset += ret;
1524 index += offset >> PAGE_CACHE_SHIFT;
1525 offset &= ~PAGE_CACHE_MASK;
1526
1527 page_cache_release(page);
1528 if (ret != nr || !desc->count)
1529 break;
1530
1531 cond_resched();
1532 }
1533
1534 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1535 file_accessed(filp);
1536 }
1537
1538 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1539 {
1540 read_descriptor_t desc;
1541
1542 if ((ssize_t) count < 0)
1543 return -EINVAL;
1544 if (!access_ok(VERIFY_WRITE, buf, count))
1545 return -EFAULT;
1546 if (!count)
1547 return 0;
1548
1549 desc.written = 0;
1550 desc.count = count;
1551 desc.arg.buf = buf;
1552 desc.error = 0;
1553
1554 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1555 if (desc.written)
1556 return desc.written;
1557 return desc.error;
1558 }
1559
1560 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1561 size_t count, read_actor_t actor, void *target)
1562 {
1563 read_descriptor_t desc;
1564
1565 if (!count)
1566 return 0;
1567
1568 desc.written = 0;
1569 desc.count = count;
1570 desc.arg.data = target;
1571 desc.error = 0;
1572
1573 do_shmem_file_read(in_file, ppos, &desc, actor);
1574 if (desc.written)
1575 return desc.written;
1576 return desc.error;
1577 }
1578
1579 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1580 {
1581 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1582
1583 buf->f_type = TMPFS_MAGIC;
1584 buf->f_bsize = PAGE_CACHE_SIZE;
1585 buf->f_namelen = NAME_MAX;
1586 spin_lock(&sbinfo->stat_lock);
1587 if (sbinfo->max_blocks) {
1588 buf->f_blocks = sbinfo->max_blocks;
1589 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1590 }
1591 if (sbinfo->max_inodes) {
1592 buf->f_files = sbinfo->max_inodes;
1593 buf->f_ffree = sbinfo->free_inodes;
1594 }
1595 /* else leave those fields 0 like simple_statfs */
1596 spin_unlock(&sbinfo->stat_lock);
1597 return 0;
1598 }
1599
1600 /*
1601 * File creation. Allocate an inode, and we're done..
1602 */
1603 static int
1604 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1605 {
1606 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1607 int error = -ENOSPC;
1608
1609 if (inode) {
1610 error = security_inode_init_security(inode, dir, NULL, NULL,
1611 NULL);
1612 if (error) {
1613 if (error != -EOPNOTSUPP) {
1614 iput(inode);
1615 return error;
1616 }
1617 error = 0;
1618 }
1619 if (dir->i_mode & S_ISGID) {
1620 inode->i_gid = dir->i_gid;
1621 if (S_ISDIR(mode))
1622 inode->i_mode |= S_ISGID;
1623 }
1624 dir->i_size += BOGO_DIRENT_SIZE;
1625 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1626 d_instantiate(dentry, inode);
1627 dget(dentry); /* Extra count - pin the dentry in core */
1628 }
1629 return error;
1630 }
1631
1632 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1633 {
1634 int error;
1635
1636 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1637 return error;
1638 dir->i_nlink++;
1639 return 0;
1640 }
1641
1642 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1643 struct nameidata *nd)
1644 {
1645 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1646 }
1647
1648 /*
1649 * Link a file..
1650 */
1651 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1652 {
1653 struct inode *inode = old_dentry->d_inode;
1654 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1655
1656 /*
1657 * No ordinary (disk based) filesystem counts links as inodes;
1658 * but each new link needs a new dentry, pinning lowmem, and
1659 * tmpfs dentries cannot be pruned until they are unlinked.
1660 */
1661 if (sbinfo->max_inodes) {
1662 spin_lock(&sbinfo->stat_lock);
1663 if (!sbinfo->free_inodes) {
1664 spin_unlock(&sbinfo->stat_lock);
1665 return -ENOSPC;
1666 }
1667 sbinfo->free_inodes--;
1668 spin_unlock(&sbinfo->stat_lock);
1669 }
1670
1671 dir->i_size += BOGO_DIRENT_SIZE;
1672 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1673 inode->i_nlink++;
1674 atomic_inc(&inode->i_count); /* New dentry reference */
1675 dget(dentry); /* Extra pinning count for the created dentry */
1676 d_instantiate(dentry, inode);
1677 return 0;
1678 }
1679
1680 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1681 {
1682 struct inode *inode = dentry->d_inode;
1683
1684 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1685 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1686 if (sbinfo->max_inodes) {
1687 spin_lock(&sbinfo->stat_lock);
1688 sbinfo->free_inodes++;
1689 spin_unlock(&sbinfo->stat_lock);
1690 }
1691 }
1692
1693 dir->i_size -= BOGO_DIRENT_SIZE;
1694 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1695 inode->i_nlink--;
1696 dput(dentry); /* Undo the count from "create" - this does all the work */
1697 return 0;
1698 }
1699
1700 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1701 {
1702 if (!simple_empty(dentry))
1703 return -ENOTEMPTY;
1704
1705 dir->i_nlink--;
1706 return shmem_unlink(dir, dentry);
1707 }
1708
1709 /*
1710 * The VFS layer already does all the dentry stuff for rename,
1711 * we just have to decrement the usage count for the target if
1712 * it exists so that the VFS layer correctly free's it when it
1713 * gets overwritten.
1714 */
1715 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1716 {
1717 struct inode *inode = old_dentry->d_inode;
1718 int they_are_dirs = S_ISDIR(inode->i_mode);
1719
1720 if (!simple_empty(new_dentry))
1721 return -ENOTEMPTY;
1722
1723 if (new_dentry->d_inode) {
1724 (void) shmem_unlink(new_dir, new_dentry);
1725 if (they_are_dirs)
1726 old_dir->i_nlink--;
1727 } else if (they_are_dirs) {
1728 old_dir->i_nlink--;
1729 new_dir->i_nlink++;
1730 }
1731
1732 old_dir->i_size -= BOGO_DIRENT_SIZE;
1733 new_dir->i_size += BOGO_DIRENT_SIZE;
1734 old_dir->i_ctime = old_dir->i_mtime =
1735 new_dir->i_ctime = new_dir->i_mtime =
1736 inode->i_ctime = CURRENT_TIME;
1737 return 0;
1738 }
1739
1740 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1741 {
1742 int error;
1743 int len;
1744 struct inode *inode;
1745 struct page *page = NULL;
1746 char *kaddr;
1747 struct shmem_inode_info *info;
1748
1749 len = strlen(symname) + 1;
1750 if (len > PAGE_CACHE_SIZE)
1751 return -ENAMETOOLONG;
1752
1753 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1754 if (!inode)
1755 return -ENOSPC;
1756
1757 error = security_inode_init_security(inode, dir, NULL, NULL,
1758 NULL);
1759 if (error) {
1760 if (error != -EOPNOTSUPP) {
1761 iput(inode);
1762 return error;
1763 }
1764 error = 0;
1765 }
1766
1767 info = SHMEM_I(inode);
1768 inode->i_size = len-1;
1769 if (len <= (char *)inode - (char *)info) {
1770 /* do it inline */
1771 memcpy(info, symname, len);
1772 inode->i_op = &shmem_symlink_inline_operations;
1773 } else {
1774 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1775 if (error) {
1776 iput(inode);
1777 return error;
1778 }
1779 inode->i_op = &shmem_symlink_inode_operations;
1780 kaddr = kmap_atomic(page, KM_USER0);
1781 memcpy(kaddr, symname, len);
1782 kunmap_atomic(kaddr, KM_USER0);
1783 set_page_dirty(page);
1784 page_cache_release(page);
1785 }
1786 if (dir->i_mode & S_ISGID)
1787 inode->i_gid = dir->i_gid;
1788 dir->i_size += BOGO_DIRENT_SIZE;
1789 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1790 d_instantiate(dentry, inode);
1791 dget(dentry);
1792 return 0;
1793 }
1794
1795 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1796 {
1797 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1798 return NULL;
1799 }
1800
1801 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1802 {
1803 struct page *page = NULL;
1804 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1805 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1806 return page;
1807 }
1808
1809 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1810 {
1811 if (!IS_ERR(nd_get_link(nd))) {
1812 struct page *page = cookie;
1813 kunmap(page);
1814 mark_page_accessed(page);
1815 page_cache_release(page);
1816 }
1817 }
1818
1819 static struct inode_operations shmem_symlink_inline_operations = {
1820 .readlink = generic_readlink,
1821 .follow_link = shmem_follow_link_inline,
1822 };
1823
1824 static struct inode_operations shmem_symlink_inode_operations = {
1825 .truncate = shmem_truncate,
1826 .readlink = generic_readlink,
1827 .follow_link = shmem_follow_link,
1828 .put_link = shmem_put_link,
1829 };
1830
1831 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
1832 {
1833 char *this_char, *value, *rest;
1834
1835 while ((this_char = strsep(&options, ",")) != NULL) {
1836 if (!*this_char)
1837 continue;
1838 if ((value = strchr(this_char,'=')) != NULL) {
1839 *value++ = 0;
1840 } else {
1841 printk(KERN_ERR
1842 "tmpfs: No value for mount option '%s'\n",
1843 this_char);
1844 return 1;
1845 }
1846
1847 if (!strcmp(this_char,"size")) {
1848 unsigned long long size;
1849 size = memparse(value,&rest);
1850 if (*rest == '%') {
1851 size <<= PAGE_SHIFT;
1852 size *= totalram_pages;
1853 do_div(size, 100);
1854 rest++;
1855 }
1856 if (*rest)
1857 goto bad_val;
1858 *blocks = size >> PAGE_CACHE_SHIFT;
1859 } else if (!strcmp(this_char,"nr_blocks")) {
1860 *blocks = memparse(value,&rest);
1861 if (*rest)
1862 goto bad_val;
1863 } else if (!strcmp(this_char,"nr_inodes")) {
1864 *inodes = memparse(value,&rest);
1865 if (*rest)
1866 goto bad_val;
1867 } else if (!strcmp(this_char,"mode")) {
1868 if (!mode)
1869 continue;
1870 *mode = simple_strtoul(value,&rest,8);
1871 if (*rest)
1872 goto bad_val;
1873 } else if (!strcmp(this_char,"uid")) {
1874 if (!uid)
1875 continue;
1876 *uid = simple_strtoul(value,&rest,0);
1877 if (*rest)
1878 goto bad_val;
1879 } else if (!strcmp(this_char,"gid")) {
1880 if (!gid)
1881 continue;
1882 *gid = simple_strtoul(value,&rest,0);
1883 if (*rest)
1884 goto bad_val;
1885 } else {
1886 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1887 this_char);
1888 return 1;
1889 }
1890 }
1891 return 0;
1892
1893 bad_val:
1894 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1895 value, this_char);
1896 return 1;
1897
1898 }
1899
1900 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1901 {
1902 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1903 unsigned long max_blocks = sbinfo->max_blocks;
1904 unsigned long max_inodes = sbinfo->max_inodes;
1905 unsigned long blocks;
1906 unsigned long inodes;
1907 int error = -EINVAL;
1908
1909 if (shmem_parse_options(data, NULL, NULL, NULL,
1910 &max_blocks, &max_inodes))
1911 return error;
1912
1913 spin_lock(&sbinfo->stat_lock);
1914 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1915 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1916 if (max_blocks < blocks)
1917 goto out;
1918 if (max_inodes < inodes)
1919 goto out;
1920 /*
1921 * Those tests also disallow limited->unlimited while any are in
1922 * use, so i_blocks will always be zero when max_blocks is zero;
1923 * but we must separately disallow unlimited->limited, because
1924 * in that case we have no record of how much is already in use.
1925 */
1926 if (max_blocks && !sbinfo->max_blocks)
1927 goto out;
1928 if (max_inodes && !sbinfo->max_inodes)
1929 goto out;
1930
1931 error = 0;
1932 sbinfo->max_blocks = max_blocks;
1933 sbinfo->free_blocks = max_blocks - blocks;
1934 sbinfo->max_inodes = max_inodes;
1935 sbinfo->free_inodes = max_inodes - inodes;
1936 out:
1937 spin_unlock(&sbinfo->stat_lock);
1938 return error;
1939 }
1940 #endif
1941
1942 static void shmem_put_super(struct super_block *sb)
1943 {
1944 kfree(sb->s_fs_info);
1945 sb->s_fs_info = NULL;
1946 }
1947
1948 static int shmem_fill_super(struct super_block *sb,
1949 void *data, int silent)
1950 {
1951 struct inode *inode;
1952 struct dentry *root;
1953 int mode = S_IRWXUGO | S_ISVTX;
1954 uid_t uid = current->fsuid;
1955 gid_t gid = current->fsgid;
1956 int err = -ENOMEM;
1957 struct shmem_sb_info *sbinfo;
1958 unsigned long blocks = 0;
1959 unsigned long inodes = 0;
1960
1961 #ifdef CONFIG_TMPFS
1962 /*
1963 * Per default we only allow half of the physical ram per
1964 * tmpfs instance, limiting inodes to one per page of lowmem;
1965 * but the internal instance is left unlimited.
1966 */
1967 if (!(sb->s_flags & MS_NOUSER)) {
1968 blocks = totalram_pages / 2;
1969 inodes = totalram_pages - totalhigh_pages;
1970 if (inodes > blocks)
1971 inodes = blocks;
1972 if (shmem_parse_options(data, &mode, &uid, &gid,
1973 &blocks, &inodes))
1974 return -EINVAL;
1975 }
1976 #else
1977 sb->s_flags |= MS_NOUSER;
1978 #endif
1979
1980 /* Round up to L1_CACHE_BYTES to resist false sharing */
1981 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
1982 L1_CACHE_BYTES), GFP_KERNEL);
1983 if (!sbinfo)
1984 return -ENOMEM;
1985
1986 spin_lock_init(&sbinfo->stat_lock);
1987 sbinfo->max_blocks = blocks;
1988 sbinfo->free_blocks = blocks;
1989 sbinfo->max_inodes = inodes;
1990 sbinfo->free_inodes = inodes;
1991
1992 sb->s_fs_info = sbinfo;
1993 sb->s_maxbytes = SHMEM_MAX_BYTES;
1994 sb->s_blocksize = PAGE_CACHE_SIZE;
1995 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
1996 sb->s_magic = TMPFS_MAGIC;
1997 sb->s_op = &shmem_ops;
1998
1999 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2000 if (!inode)
2001 goto failed;
2002 inode->i_uid = uid;
2003 inode->i_gid = gid;
2004 root = d_alloc_root(inode);
2005 if (!root)
2006 goto failed_iput;
2007 sb->s_root = root;
2008 return 0;
2009
2010 failed_iput:
2011 iput(inode);
2012 failed:
2013 shmem_put_super(sb);
2014 return err;
2015 }
2016
2017 static kmem_cache_t *shmem_inode_cachep;
2018
2019 static struct inode *shmem_alloc_inode(struct super_block *sb)
2020 {
2021 struct shmem_inode_info *p;
2022 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2023 if (!p)
2024 return NULL;
2025 return &p->vfs_inode;
2026 }
2027
2028 static void shmem_destroy_inode(struct inode *inode)
2029 {
2030 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2031 /* only struct inode is valid if it's an inline symlink */
2032 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2033 }
2034 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2035 }
2036
2037 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2038 {
2039 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2040
2041 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2042 SLAB_CTOR_CONSTRUCTOR) {
2043 inode_init_once(&p->vfs_inode);
2044 }
2045 }
2046
2047 static int init_inodecache(void)
2048 {
2049 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2050 sizeof(struct shmem_inode_info),
2051 0, 0, init_once, NULL);
2052 if (shmem_inode_cachep == NULL)
2053 return -ENOMEM;
2054 return 0;
2055 }
2056
2057 static void destroy_inodecache(void)
2058 {
2059 if (kmem_cache_destroy(shmem_inode_cachep))
2060 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2061 }
2062
2063 static struct address_space_operations shmem_aops = {
2064 .writepage = shmem_writepage,
2065 .set_page_dirty = __set_page_dirty_nobuffers,
2066 #ifdef CONFIG_TMPFS
2067 .prepare_write = shmem_prepare_write,
2068 .commit_write = simple_commit_write,
2069 #endif
2070 };
2071
2072 static struct file_operations shmem_file_operations = {
2073 .mmap = shmem_mmap,
2074 #ifdef CONFIG_TMPFS
2075 .llseek = generic_file_llseek,
2076 .read = shmem_file_read,
2077 .write = shmem_file_write,
2078 .fsync = simple_sync_file,
2079 .sendfile = shmem_file_sendfile,
2080 #endif
2081 };
2082
2083 static struct inode_operations shmem_inode_operations = {
2084 .truncate = shmem_truncate,
2085 .setattr = shmem_notify_change,
2086 };
2087
2088 static struct inode_operations shmem_dir_inode_operations = {
2089 #ifdef CONFIG_TMPFS
2090 .create = shmem_create,
2091 .lookup = simple_lookup,
2092 .link = shmem_link,
2093 .unlink = shmem_unlink,
2094 .symlink = shmem_symlink,
2095 .mkdir = shmem_mkdir,
2096 .rmdir = shmem_rmdir,
2097 .mknod = shmem_mknod,
2098 .rename = shmem_rename,
2099 #endif
2100 };
2101
2102 static struct super_operations shmem_ops = {
2103 .alloc_inode = shmem_alloc_inode,
2104 .destroy_inode = shmem_destroy_inode,
2105 #ifdef CONFIG_TMPFS
2106 .statfs = shmem_statfs,
2107 .remount_fs = shmem_remount_fs,
2108 #endif
2109 .delete_inode = shmem_delete_inode,
2110 .drop_inode = generic_delete_inode,
2111 .put_super = shmem_put_super,
2112 };
2113
2114 static struct vm_operations_struct shmem_vm_ops = {
2115 .nopage = shmem_nopage,
2116 .populate = shmem_populate,
2117 #ifdef CONFIG_NUMA
2118 .set_policy = shmem_set_policy,
2119 .get_policy = shmem_get_policy,
2120 #endif
2121 };
2122
2123
2124 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2125 int flags, const char *dev_name, void *data)
2126 {
2127 return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2128 }
2129
2130 static struct file_system_type tmpfs_fs_type = {
2131 .owner = THIS_MODULE,
2132 .name = "tmpfs",
2133 .get_sb = shmem_get_sb,
2134 .kill_sb = kill_litter_super,
2135 };
2136 static struct vfsmount *shm_mnt;
2137
2138 static int __init init_tmpfs(void)
2139 {
2140 int error;
2141
2142 error = init_inodecache();
2143 if (error)
2144 goto out3;
2145
2146 error = register_filesystem(&tmpfs_fs_type);
2147 if (error) {
2148 printk(KERN_ERR "Could not register tmpfs\n");
2149 goto out2;
2150 }
2151 #ifdef CONFIG_TMPFS
2152 devfs_mk_dir("shm");
2153 #endif
2154 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2155 tmpfs_fs_type.name, NULL);
2156 if (IS_ERR(shm_mnt)) {
2157 error = PTR_ERR(shm_mnt);
2158 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2159 goto out1;
2160 }
2161 return 0;
2162
2163 out1:
2164 unregister_filesystem(&tmpfs_fs_type);
2165 out2:
2166 destroy_inodecache();
2167 out3:
2168 shm_mnt = ERR_PTR(error);
2169 return error;
2170 }
2171 module_init(init_tmpfs)
2172
2173 /*
2174 * shmem_file_setup - get an unlinked file living in tmpfs
2175 *
2176 * @name: name for dentry (to be seen in /proc/<pid>/maps
2177 * @size: size to be set for the file
2178 *
2179 */
2180 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2181 {
2182 int error;
2183 struct file *file;
2184 struct inode *inode;
2185 struct dentry *dentry, *root;
2186 struct qstr this;
2187
2188 if (IS_ERR(shm_mnt))
2189 return (void *)shm_mnt;
2190
2191 if (size < 0 || size > SHMEM_MAX_BYTES)
2192 return ERR_PTR(-EINVAL);
2193
2194 if (shmem_acct_size(flags, size))
2195 return ERR_PTR(-ENOMEM);
2196
2197 error = -ENOMEM;
2198 this.name = name;
2199 this.len = strlen(name);
2200 this.hash = 0; /* will go */
2201 root = shm_mnt->mnt_root;
2202 dentry = d_alloc(root, &this);
2203 if (!dentry)
2204 goto put_memory;
2205
2206 error = -ENFILE;
2207 file = get_empty_filp();
2208 if (!file)
2209 goto put_dentry;
2210
2211 error = -ENOSPC;
2212 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2213 if (!inode)
2214 goto close_file;
2215
2216 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2217 d_instantiate(dentry, inode);
2218 inode->i_size = size;
2219 inode->i_nlink = 0; /* It is unlinked */
2220 file->f_vfsmnt = mntget(shm_mnt);
2221 file->f_dentry = dentry;
2222 file->f_mapping = inode->i_mapping;
2223 file->f_op = &shmem_file_operations;
2224 file->f_mode = FMODE_WRITE | FMODE_READ;
2225 return file;
2226
2227 close_file:
2228 put_filp(file);
2229 put_dentry:
2230 dput(dentry);
2231 put_memory:
2232 shmem_unacct_size(flags, size);
2233 return ERR_PTR(error);
2234 }
2235
2236 /*
2237 * shmem_zero_setup - setup a shared anonymous mapping
2238 *
2239 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2240 */
2241 int shmem_zero_setup(struct vm_area_struct *vma)
2242 {
2243 struct file *file;
2244 loff_t size = vma->vm_end - vma->vm_start;
2245
2246 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2247 if (IS_ERR(file))
2248 return PTR_ERR(file);
2249
2250 if (vma->vm_file)
2251 fput(vma->vm_file);
2252 vma->vm_file = file;
2253 vma->vm_ops = &shmem_vm_ops;
2254 return 0;
2255 }
linux v2.6.22.y-op