?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
[patch] remove gendisk->stamp_idle field
[linux-2.6.22.y-op.git] / mm / shmem.c
blobea064d89cda9510d16755ab95127eae62badf94b
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 /* Keep swapped page count in private field of indirect struct page */
75 #define nr_swapped private
76
77 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
78 enum sgp_type {
79 SGP_QUICK, /* don't try more than file page cache lookup */
80 SGP_READ, /* don't exceed i_size, don't allocate page */
81 SGP_CACHE, /* don't exceed i_size, may allocate page */
82 SGP_WRITE, /* may exceed i_size, may allocate page */
83 };
84
85 static int shmem_getpage(struct inode *inode, unsigned long idx,
86 struct page **pagep, enum sgp_type sgp, int *type);
87
88 static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
89 {
90 /*
91 * The above definition of ENTRIES_PER_PAGE, and the use of
92 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
93 * might be reconsidered if it ever diverges from PAGE_SIZE.
94 */
95 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
96 }
97
98 static inline void shmem_dir_free(struct page *page)
99 {
100 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
101 }
102
103 static struct page **shmem_dir_map(struct page *page)
104 {
105 return (struct page **)kmap_atomic(page, KM_USER0);
106 }
107
108 static inline void shmem_dir_unmap(struct page **dir)
109 {
110 kunmap_atomic(dir, KM_USER0);
111 }
112
113 static swp_entry_t *shmem_swp_map(struct page *page)
114 {
115 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
116 }
117
118 static inline void shmem_swp_balance_unmap(void)
119 {
120 /*
121 * When passing a pointer to an i_direct entry, to code which
122 * also handles indirect entries and so will shmem_swp_unmap,
123 * we must arrange for the preempt count to remain in balance.
124 * What kmap_atomic of a lowmem page does depends on config
125 * and architecture, so pretend to kmap_atomic some lowmem page.
126 */
127 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
128 }
129
130 static inline void shmem_swp_unmap(swp_entry_t *entry)
131 {
132 kunmap_atomic(entry, KM_USER1);
133 }
134
135 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
136 {
137 return sb->s_fs_info;
138 }
139
140 /*
141 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
142 * for shared memory and for shared anonymous (/dev/zero) mappings
143 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
144 * consistent with the pre-accounting of private mappings ...
145 */
146 static inline int shmem_acct_size(unsigned long flags, loff_t size)
147 {
148 return (flags & VM_ACCOUNT)?
149 security_vm_enough_memory(VM_ACCT(size)): 0;
150 }
151
152 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
153 {
154 if (flags & VM_ACCOUNT)
155 vm_unacct_memory(VM_ACCT(size));
156 }
157
158 /*
159 * ... whereas tmpfs objects are accounted incrementally as
160 * pages are allocated, in order to allow huge sparse files.
161 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
162 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
163 */
164 static inline int shmem_acct_block(unsigned long flags)
165 {
166 return (flags & VM_ACCOUNT)?
167 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
168 }
169
170 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
171 {
172 if (!(flags & VM_ACCOUNT))
173 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
174 }
175
176 static struct super_operations shmem_ops;
177 static struct address_space_operations shmem_aops;
178 static struct file_operations shmem_file_operations;
179 static struct inode_operations shmem_inode_operations;
180 static struct inode_operations shmem_dir_inode_operations;
181 static struct vm_operations_struct shmem_vm_ops;
182
183 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
184 .ra_pages = 0, /* No readahead */
185 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
186 .unplug_io_fn = default_unplug_io_fn,
187 };
188
189 static LIST_HEAD(shmem_swaplist);
190 static DEFINE_SPINLOCK(shmem_swaplist_lock);
191
192 static void shmem_free_blocks(struct inode *inode, long pages)
193 {
194 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
195 if (sbinfo->max_blocks) {
196 spin_lock(&sbinfo->stat_lock);
197 sbinfo->free_blocks += pages;
198 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
199 spin_unlock(&sbinfo->stat_lock);
200 }
201 }
202
203 /*
204 * shmem_recalc_inode - recalculate the size of an inode
205 *
206 * @inode: inode to recalc
207 *
208 * We have to calculate the free blocks since the mm can drop
209 * undirtied hole pages behind our back.
210 *
211 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
212 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
213 *
214 * It has to be called with the spinlock held.
215 */
216 static void shmem_recalc_inode(struct inode *inode)
217 {
218 struct shmem_inode_info *info = SHMEM_I(inode);
219 long freed;
220
221 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
222 if (freed > 0) {
223 info->alloced -= freed;
224 shmem_unacct_blocks(info->flags, freed);
225 shmem_free_blocks(inode, freed);
226 }
227 }
228
229 /*
230 * shmem_swp_entry - find the swap vector position in the info structure
231 *
232 * @info: info structure for the inode
233 * @index: index of the page to find
234 * @page: optional page to add to the structure. Has to be preset to
235 * all zeros
236 *
237 * If there is no space allocated yet it will return NULL when
238 * page is NULL, else it will use the page for the needed block,
239 * setting it to NULL on return to indicate that it has been used.
240 *
241 * The swap vector is organized the following way:
242 *
243 * There are SHMEM_NR_DIRECT entries directly stored in the
244 * shmem_inode_info structure. So small files do not need an addional
245 * allocation.
246 *
247 * For pages with index > SHMEM_NR_DIRECT there is the pointer
248 * i_indirect which points to a page which holds in the first half
249 * doubly indirect blocks, in the second half triple indirect blocks:
250 *
251 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
252 * following layout (for SHMEM_NR_DIRECT == 16):
253 *
254 * i_indirect -> dir --> 16-19
255 * | +-> 20-23
256 * |
257 * +-->dir2 --> 24-27
258 * | +-> 28-31
259 * | +-> 32-35
260 * | +-> 36-39
261 * |
262 * +-->dir3 --> 40-43
263 * +-> 44-47
264 * +-> 48-51
265 * +-> 52-55
266 */
267 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
268 {
269 unsigned long offset;
270 struct page **dir;
271 struct page *subdir;
272
273 if (index < SHMEM_NR_DIRECT) {
274 shmem_swp_balance_unmap();
275 return info->i_direct+index;
276 }
277 if (!info->i_indirect) {
278 if (page) {
279 info->i_indirect = *page;
280 *page = NULL;
281 }
282 return NULL; /* need another page */
283 }
284
285 index -= SHMEM_NR_DIRECT;
286 offset = index % ENTRIES_PER_PAGE;
287 index /= ENTRIES_PER_PAGE;
288 dir = shmem_dir_map(info->i_indirect);
289
290 if (index >= ENTRIES_PER_PAGE/2) {
291 index -= ENTRIES_PER_PAGE/2;
292 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
293 index %= ENTRIES_PER_PAGE;
294 subdir = *dir;
295 if (!subdir) {
296 if (page) {
297 *dir = *page;
298 *page = NULL;
299 }
300 shmem_dir_unmap(dir);
301 return NULL; /* need another page */
302 }
303 shmem_dir_unmap(dir);
304 dir = shmem_dir_map(subdir);
305 }
306
307 dir += index;
308 subdir = *dir;
309 if (!subdir) {
310 if (!page || !(subdir = *page)) {
311 shmem_dir_unmap(dir);
312 return NULL; /* need a page */
313 }
314 *dir = subdir;
315 *page = NULL;
316 }
317 shmem_dir_unmap(dir);
318 return shmem_swp_map(subdir) + offset;
319 }
320
321 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
322 {
323 long incdec = value? 1: -1;
324
325 entry->val = value;
326 info->swapped += incdec;
327 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
328 kmap_atomic_to_page(entry)->nr_swapped += incdec;
329 }
330
331 /*
332 * shmem_swp_alloc - get the position of the swap entry for the page.
333 * If it does not exist allocate the entry.
334 *
335 * @info: info structure for the inode
336 * @index: index of the page to find
337 * @sgp: check and recheck i_size? skip allocation?
338 */
339 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
340 {
341 struct inode *inode = &info->vfs_inode;
342 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
343 struct page *page = NULL;
344 swp_entry_t *entry;
345
346 if (sgp != SGP_WRITE &&
347 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
348 return ERR_PTR(-EINVAL);
349
350 while (!(entry = shmem_swp_entry(info, index, &page))) {
351 if (sgp == SGP_READ)
352 return shmem_swp_map(ZERO_PAGE(0));
353 /*
354 * Test free_blocks against 1 not 0, since we have 1 data
355 * page (and perhaps indirect index pages) yet to allocate:
356 * a waste to allocate index if we cannot allocate data.
357 */
358 if (sbinfo->max_blocks) {
359 spin_lock(&sbinfo->stat_lock);
360 if (sbinfo->free_blocks <= 1) {
361 spin_unlock(&sbinfo->stat_lock);
362 return ERR_PTR(-ENOSPC);
363 }
364 sbinfo->free_blocks--;
365 inode->i_blocks += BLOCKS_PER_PAGE;
366 spin_unlock(&sbinfo->stat_lock);
367 }
368
369 spin_unlock(&info->lock);
370 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
371 if (page) {
372 page->nr_swapped = 0;
373 }
374 spin_lock(&info->lock);
375
376 if (!page) {
377 shmem_free_blocks(inode, 1);
378 return ERR_PTR(-ENOMEM);
379 }
380 if (sgp != SGP_WRITE &&
381 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
382 entry = ERR_PTR(-EINVAL);
383 break;
384 }
385 if (info->next_index <= index)
386 info->next_index = index + 1;
387 }
388 if (page) {
389 /* another task gave its page, or truncated the file */
390 shmem_free_blocks(inode, 1);
391 shmem_dir_free(page);
392 }
393 if (info->next_index <= index && !IS_ERR(entry))
394 info->next_index = index + 1;
395 return entry;
396 }
397
398 /*
399 * shmem_free_swp - free some swap entries in a directory
400 *
401 * @dir: pointer to the directory
402 * @edir: pointer after last entry of the directory
403 */
404 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
405 {
406 swp_entry_t *ptr;
407 int freed = 0;
408
409 for (ptr = dir; ptr < edir; ptr++) {
410 if (ptr->val) {
411 free_swap_and_cache(*ptr);
412 *ptr = (swp_entry_t){0};
413 freed++;
414 }
415 }
416 return freed;
417 }
418
419 static int shmem_map_and_free_swp(struct page *subdir,
420 int offset, int limit, struct page ***dir)
421 {
422 swp_entry_t *ptr;
423 int freed = 0;
424
425 ptr = shmem_swp_map(subdir);
426 for (; offset < limit; offset += LATENCY_LIMIT) {
427 int size = limit - offset;
428 if (size > LATENCY_LIMIT)
429 size = LATENCY_LIMIT;
430 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
431 if (need_resched()) {
432 shmem_swp_unmap(ptr);
433 if (*dir) {
434 shmem_dir_unmap(*dir);
435 *dir = NULL;
436 }
437 cond_resched();
438 ptr = shmem_swp_map(subdir);
439 }
440 }
441 shmem_swp_unmap(ptr);
442 return freed;
443 }
444
445 static void shmem_free_pages(struct list_head *next)
446 {
447 struct page *page;
448 int freed = 0;
449
450 do {
451 page = container_of(next, struct page, lru);
452 next = next->next;
453 shmem_dir_free(page);
454 freed++;
455 if (freed >= LATENCY_LIMIT) {
456 cond_resched();
457 freed = 0;
458 }
459 } while (next);
460 }
461
462 static void shmem_truncate(struct inode *inode)
463 {
464 struct shmem_inode_info *info = SHMEM_I(inode);
465 unsigned long idx;
466 unsigned long size;
467 unsigned long limit;
468 unsigned long stage;
469 unsigned long diroff;
470 struct page **dir;
471 struct page *topdir;
472 struct page *middir;
473 struct page *subdir;
474 swp_entry_t *ptr;
475 LIST_HEAD(pages_to_free);
476 long nr_pages_to_free = 0;
477 long nr_swaps_freed = 0;
478 int offset;
479 int freed;
480
481 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
482 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
483 if (idx >= info->next_index)
484 return;
485
486 spin_lock(&info->lock);
487 info->flags |= SHMEM_TRUNCATE;
488 limit = info->next_index;
489 info->next_index = idx;
490 topdir = info->i_indirect;
491 if (topdir && idx <= SHMEM_NR_DIRECT) {
492 info->i_indirect = NULL;
493 nr_pages_to_free++;
494 list_add(&topdir->lru, &pages_to_free);
495 }
496 spin_unlock(&info->lock);
497
498 if (info->swapped && idx < SHMEM_NR_DIRECT) {
499 ptr = info->i_direct;
500 size = limit;
501 if (size > SHMEM_NR_DIRECT)
502 size = SHMEM_NR_DIRECT;
503 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
504 }
505 if (!topdir)
506 goto done2;
507
508 BUG_ON(limit <= SHMEM_NR_DIRECT);
509 limit -= SHMEM_NR_DIRECT;
510 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
511 offset = idx % ENTRIES_PER_PAGE;
512 idx -= offset;
513
514 dir = shmem_dir_map(topdir);
515 stage = ENTRIES_PER_PAGEPAGE/2;
516 if (idx < ENTRIES_PER_PAGEPAGE/2) {
517 middir = topdir;
518 diroff = idx/ENTRIES_PER_PAGE;
519 } else {
520 dir += ENTRIES_PER_PAGE/2;
521 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
522 while (stage <= idx)
523 stage += ENTRIES_PER_PAGEPAGE;
524 middir = *dir;
525 if (*dir) {
526 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
527 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
528 if (!diroff && !offset) {
529 *dir = NULL;
530 nr_pages_to_free++;
531 list_add(&middir->lru, &pages_to_free);
532 }
533 shmem_dir_unmap(dir);
534 dir = shmem_dir_map(middir);
535 } else {
536 diroff = 0;
537 offset = 0;
538 idx = stage;
539 }
540 }
541
542 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
543 if (unlikely(idx == stage)) {
544 shmem_dir_unmap(dir);
545 dir = shmem_dir_map(topdir) +
546 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
547 while (!*dir) {
548 dir++;
549 idx += ENTRIES_PER_PAGEPAGE;
550 if (idx >= limit)
551 goto done1;
552 }
553 stage = idx + ENTRIES_PER_PAGEPAGE;
554 middir = *dir;
555 *dir = NULL;
556 nr_pages_to_free++;
557 list_add(&middir->lru, &pages_to_free);
558 shmem_dir_unmap(dir);
559 cond_resched();
560 dir = shmem_dir_map(middir);
561 diroff = 0;
562 }
563 subdir = dir[diroff];
564 if (subdir && subdir->nr_swapped) {
565 size = limit - idx;
566 if (size > ENTRIES_PER_PAGE)
567 size = ENTRIES_PER_PAGE;
568 freed = shmem_map_and_free_swp(subdir,
569 offset, size, &dir);
570 if (!dir)
571 dir = shmem_dir_map(middir);
572 nr_swaps_freed += freed;
573 if (offset)
574 spin_lock(&info->lock);
575 subdir->nr_swapped -= freed;
576 if (offset)
577 spin_unlock(&info->lock);
578 BUG_ON(subdir->nr_swapped > offset);
579 }
580 if (offset)
581 offset = 0;
582 else if (subdir) {
583 dir[diroff] = NULL;
584 nr_pages_to_free++;
585 list_add(&subdir->lru, &pages_to_free);
586 }
587 }
588 done1:
589 shmem_dir_unmap(dir);
590 done2:
591 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
592 /*
593 * Call truncate_inode_pages again: racing shmem_unuse_inode
594 * may have swizzled a page in from swap since vmtruncate or
595 * generic_delete_inode did it, before we lowered next_index.
596 * Also, though shmem_getpage checks i_size before adding to
597 * cache, no recheck after: so fix the narrow window there too.
598 */
599 truncate_inode_pages(inode->i_mapping, inode->i_size);
600 }
601
602 spin_lock(&info->lock);
603 info->flags &= ~SHMEM_TRUNCATE;
604 info->swapped -= nr_swaps_freed;
605 if (nr_pages_to_free)
606 shmem_free_blocks(inode, nr_pages_to_free);
607 shmem_recalc_inode(inode);
608 spin_unlock(&info->lock);
609
610 /*
611 * Empty swap vector directory pages to be freed?
612 */
613 if (!list_empty(&pages_to_free)) {
614 pages_to_free.prev->next = NULL;
615 shmem_free_pages(pages_to_free.next);
616 }
617 }
618
619 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
620 {
621 struct inode *inode = dentry->d_inode;
622 struct page *page = NULL;
623 int error;
624
625 if (attr->ia_valid & ATTR_SIZE) {
626 if (attr->ia_size < inode->i_size) {
627 /*
628 * If truncating down to a partial page, then
629 * if that page is already allocated, hold it
630 * in memory until the truncation is over, so
631 * truncate_partial_page cannnot miss it were
632 * it assigned to swap.
633 */
634 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
635 (void) shmem_getpage(inode,
636 attr->ia_size>>PAGE_CACHE_SHIFT,
637 &page, SGP_READ, NULL);
638 }
639 /*
640 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
641 * detect if any pages might have been added to cache
642 * after truncate_inode_pages. But we needn't bother
643 * if it's being fully truncated to zero-length: the
644 * nrpages check is efficient enough in that case.
645 */
646 if (attr->ia_size) {
647 struct shmem_inode_info *info = SHMEM_I(inode);
648 spin_lock(&info->lock);
649 info->flags &= ~SHMEM_PAGEIN;
650 spin_unlock(&info->lock);
651 }
652 }
653 }
654
655 error = inode_change_ok(inode, attr);
656 if (!error)
657 error = inode_setattr(inode, attr);
658 if (page)
659 page_cache_release(page);
660 return error;
661 }
662
663 static void shmem_delete_inode(struct inode *inode)
664 {
665 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
666 struct shmem_inode_info *info = SHMEM_I(inode);
667
668 if (inode->i_op->truncate == shmem_truncate) {
669 truncate_inode_pages(inode->i_mapping, 0);
670 shmem_unacct_size(info->flags, inode->i_size);
671 inode->i_size = 0;
672 shmem_truncate(inode);
673 if (!list_empty(&info->swaplist)) {
674 spin_lock(&shmem_swaplist_lock);
675 list_del_init(&info->swaplist);
676 spin_unlock(&shmem_swaplist_lock);
677 }
678 }
679 BUG_ON(inode->i_blocks);
680 if (sbinfo->max_inodes) {
681 spin_lock(&sbinfo->stat_lock);
682 sbinfo->free_inodes++;
683 spin_unlock(&sbinfo->stat_lock);
684 }
685 clear_inode(inode);
686 }
687
688 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
689 {
690 swp_entry_t *ptr;
691
692 for (ptr = dir; ptr < edir; ptr++) {
693 if (ptr->val == entry.val)
694 return ptr - dir;
695 }
696 return -1;
697 }
698
699 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
700 {
701 struct inode *inode;
702 unsigned long idx;
703 unsigned long size;
704 unsigned long limit;
705 unsigned long stage;
706 struct page **dir;
707 struct page *subdir;
708 swp_entry_t *ptr;
709 int offset;
710
711 idx = 0;
712 ptr = info->i_direct;
713 spin_lock(&info->lock);
714 limit = info->next_index;
715 size = limit;
716 if (size > SHMEM_NR_DIRECT)
717 size = SHMEM_NR_DIRECT;
718 offset = shmem_find_swp(entry, ptr, ptr+size);
719 if (offset >= 0) {
720 shmem_swp_balance_unmap();
721 goto found;
722 }
723 if (!info->i_indirect)
724 goto lost2;
725
726 dir = shmem_dir_map(info->i_indirect);
727 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
728
729 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
730 if (unlikely(idx == stage)) {
731 shmem_dir_unmap(dir-1);
732 dir = shmem_dir_map(info->i_indirect) +
733 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
734 while (!*dir) {
735 dir++;
736 idx += ENTRIES_PER_PAGEPAGE;
737 if (idx >= limit)
738 goto lost1;
739 }
740 stage = idx + ENTRIES_PER_PAGEPAGE;
741 subdir = *dir;
742 shmem_dir_unmap(dir);
743 dir = shmem_dir_map(subdir);
744 }
745 subdir = *dir;
746 if (subdir && subdir->nr_swapped) {
747 ptr = shmem_swp_map(subdir);
748 size = limit - idx;
749 if (size > ENTRIES_PER_PAGE)
750 size = ENTRIES_PER_PAGE;
751 offset = shmem_find_swp(entry, ptr, ptr+size);
752 if (offset >= 0) {
753 shmem_dir_unmap(dir);
754 goto found;
755 }
756 shmem_swp_unmap(ptr);
757 }
758 }
759 lost1:
760 shmem_dir_unmap(dir-1);
761 lost2:
762 spin_unlock(&info->lock);
763 return 0;
764 found:
765 idx += offset;
766 inode = &info->vfs_inode;
767 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
768 info->flags |= SHMEM_PAGEIN;
769 shmem_swp_set(info, ptr + offset, 0);
770 }
771 shmem_swp_unmap(ptr);
772 spin_unlock(&info->lock);
773 /*
774 * Decrement swap count even when the entry is left behind:
775 * try_to_unuse will skip over mms, then reincrement count.
776 */
777 swap_free(entry);
778 return 1;
779 }
780
781 /*
782 * shmem_unuse() search for an eventually swapped out shmem page.
783 */
784 int shmem_unuse(swp_entry_t entry, struct page *page)
785 {
786 struct list_head *p, *next;
787 struct shmem_inode_info *info;
788 int found = 0;
789
790 spin_lock(&shmem_swaplist_lock);
791 list_for_each_safe(p, next, &shmem_swaplist) {
792 info = list_entry(p, struct shmem_inode_info, swaplist);
793 if (!info->swapped)
794 list_del_init(&info->swaplist);
795 else if (shmem_unuse_inode(info, entry, page)) {
796 /* move head to start search for next from here */
797 list_move_tail(&shmem_swaplist, &info->swaplist);
798 found = 1;
799 break;
800 }
801 }
802 spin_unlock(&shmem_swaplist_lock);
803 return found;
804 }
805
806 /*
807 * Move the page from the page cache to the swap cache.
808 */
809 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
810 {
811 struct shmem_inode_info *info;
812 swp_entry_t *entry, swap;
813 struct address_space *mapping;
814 unsigned long index;
815 struct inode *inode;
816
817 BUG_ON(!PageLocked(page));
818 BUG_ON(page_mapped(page));
819
820 mapping = page->mapping;
821 index = page->index;
822 inode = mapping->host;
823 info = SHMEM_I(inode);
824 if (info->flags & VM_LOCKED)
825 goto redirty;
826 swap = get_swap_page();
827 if (!swap.val)
828 goto redirty;
829
830 spin_lock(&info->lock);
831 shmem_recalc_inode(inode);
832 if (index >= info->next_index) {
833 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
834 goto unlock;
835 }
836 entry = shmem_swp_entry(info, index, NULL);
837 BUG_ON(!entry);
838 BUG_ON(entry->val);
839
840 if (move_to_swap_cache(page, swap) == 0) {
841 shmem_swp_set(info, entry, swap.val);
842 shmem_swp_unmap(entry);
843 spin_unlock(&info->lock);
844 if (list_empty(&info->swaplist)) {
845 spin_lock(&shmem_swaplist_lock);
846 /* move instead of add in case we're racing */
847 list_move_tail(&info->swaplist, &shmem_swaplist);
848 spin_unlock(&shmem_swaplist_lock);
849 }
850 unlock_page(page);
851 return 0;
852 }
853
854 shmem_swp_unmap(entry);
855 unlock:
856 spin_unlock(&info->lock);
857 swap_free(swap);
858 redirty:
859 set_page_dirty(page);
860 return WRITEPAGE_ACTIVATE; /* Return with the page locked */
861 }
862
863 #ifdef CONFIG_NUMA
864 static struct page *shmem_swapin_async(struct shared_policy *p,
865 swp_entry_t entry, unsigned long idx)
866 {
867 struct page *page;
868 struct vm_area_struct pvma;
869
870 /* Create a pseudo vma that just contains the policy */
871 memset(&pvma, 0, sizeof(struct vm_area_struct));
872 pvma.vm_end = PAGE_SIZE;
873 pvma.vm_pgoff = idx;
874 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
875 page = read_swap_cache_async(entry, &pvma, 0);
876 mpol_free(pvma.vm_policy);
877 return page;
878 }
879
880 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
881 unsigned long idx)
882 {
883 struct shared_policy *p = &info->policy;
884 int i, num;
885 struct page *page;
886 unsigned long offset;
887
888 num = valid_swaphandles(entry, &offset);
889 for (i = 0; i < num; offset++, i++) {
890 page = shmem_swapin_async(p,
891 swp_entry(swp_type(entry), offset), idx);
892 if (!page)
893 break;
894 page_cache_release(page);
895 }
896 lru_add_drain(); /* Push any new pages onto the LRU now */
897 return shmem_swapin_async(p, entry, idx);
898 }
899
900 static struct page *
901 shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
902 unsigned long idx)
903 {
904 struct vm_area_struct pvma;
905 struct page *page;
906
907 memset(&pvma, 0, sizeof(struct vm_area_struct));
908 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
909 pvma.vm_pgoff = idx;
910 pvma.vm_end = PAGE_SIZE;
911 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
912 mpol_free(pvma.vm_policy);
913 return page;
914 }
915 #else
916 static inline struct page *
917 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
918 {
919 swapin_readahead(entry, 0, NULL);
920 return read_swap_cache_async(entry, NULL, 0);
921 }
922
923 static inline struct page *
924 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
925 {
926 return alloc_page(gfp | __GFP_ZERO);
927 }
928 #endif
929
930 /*
931 * shmem_getpage - either get the page from swap or allocate a new one
932 *
933 * If we allocate a new one we do not mark it dirty. That's up to the
934 * vm. If we swap it in we mark it dirty since we also free the swap
935 * entry since a page cannot live in both the swap and page cache
936 */
937 static int shmem_getpage(struct inode *inode, unsigned long idx,
938 struct page **pagep, enum sgp_type sgp, int *type)
939 {
940 struct address_space *mapping = inode->i_mapping;
941 struct shmem_inode_info *info = SHMEM_I(inode);
942 struct shmem_sb_info *sbinfo;
943 struct page *filepage = *pagep;
944 struct page *swappage;
945 swp_entry_t *entry;
946 swp_entry_t swap;
947 int error;
948
949 if (idx >= SHMEM_MAX_INDEX)
950 return -EFBIG;
951 /*
952 * Normally, filepage is NULL on entry, and either found
953 * uptodate immediately, or allocated and zeroed, or read
954 * in under swappage, which is then assigned to filepage.
955 * But shmem_prepare_write passes in a locked filepage,
956 * which may be found not uptodate by other callers too,
957 * and may need to be copied from the swappage read in.
958 */
959 repeat:
960 if (!filepage)
961 filepage = find_lock_page(mapping, idx);
962 if (filepage && PageUptodate(filepage))
963 goto done;
964 error = 0;
965 if (sgp == SGP_QUICK)
966 goto failed;
967
968 spin_lock(&info->lock);
969 shmem_recalc_inode(inode);
970 entry = shmem_swp_alloc(info, idx, sgp);
971 if (IS_ERR(entry)) {
972 spin_unlock(&info->lock);
973 error = PTR_ERR(entry);
974 goto failed;
975 }
976 swap = *entry;
977
978 if (swap.val) {
979 /* Look it up and read it in.. */
980 swappage = lookup_swap_cache(swap);
981 if (!swappage) {
982 shmem_swp_unmap(entry);
983 spin_unlock(&info->lock);
984 /* here we actually do the io */
985 if (type && *type == VM_FAULT_MINOR) {
986 inc_page_state(pgmajfault);
987 *type = VM_FAULT_MAJOR;
988 }
989 swappage = shmem_swapin(info, swap, idx);
990 if (!swappage) {
991 spin_lock(&info->lock);
992 entry = shmem_swp_alloc(info, idx, sgp);
993 if (IS_ERR(entry))
994 error = PTR_ERR(entry);
995 else {
996 if (entry->val == swap.val)
997 error = -ENOMEM;
998 shmem_swp_unmap(entry);
999 }
1000 spin_unlock(&info->lock);
1001 if (error)
1002 goto failed;
1003 goto repeat;
1004 }
1005 wait_on_page_locked(swappage);
1006 page_cache_release(swappage);
1007 goto repeat;
1008 }
1009
1010 /* We have to do this with page locked to prevent races */
1011 if (TestSetPageLocked(swappage)) {
1012 shmem_swp_unmap(entry);
1013 spin_unlock(&info->lock);
1014 wait_on_page_locked(swappage);
1015 page_cache_release(swappage);
1016 goto repeat;
1017 }
1018 if (PageWriteback(swappage)) {
1019 shmem_swp_unmap(entry);
1020 spin_unlock(&info->lock);
1021 wait_on_page_writeback(swappage);
1022 unlock_page(swappage);
1023 page_cache_release(swappage);
1024 goto repeat;
1025 }
1026 if (!PageUptodate(swappage)) {
1027 shmem_swp_unmap(entry);
1028 spin_unlock(&info->lock);
1029 unlock_page(swappage);
1030 page_cache_release(swappage);
1031 error = -EIO;
1032 goto failed;
1033 }
1034
1035 if (filepage) {
1036 shmem_swp_set(info, entry, 0);
1037 shmem_swp_unmap(entry);
1038 delete_from_swap_cache(swappage);
1039 spin_unlock(&info->lock);
1040 copy_highpage(filepage, swappage);
1041 unlock_page(swappage);
1042 page_cache_release(swappage);
1043 flush_dcache_page(filepage);
1044 SetPageUptodate(filepage);
1045 set_page_dirty(filepage);
1046 swap_free(swap);
1047 } else if (!(error = move_from_swap_cache(
1048 swappage, idx, mapping))) {
1049 info->flags |= SHMEM_PAGEIN;
1050 shmem_swp_set(info, entry, 0);
1051 shmem_swp_unmap(entry);
1052 spin_unlock(&info->lock);
1053 filepage = swappage;
1054 swap_free(swap);
1055 } else {
1056 shmem_swp_unmap(entry);
1057 spin_unlock(&info->lock);
1058 unlock_page(swappage);
1059 page_cache_release(swappage);
1060 if (error == -ENOMEM) {
1061 /* let kswapd refresh zone for GFP_ATOMICs */
1062 blk_congestion_wait(WRITE, HZ/50);
1063 }
1064 goto repeat;
1065 }
1066 } else if (sgp == SGP_READ && !filepage) {
1067 shmem_swp_unmap(entry);
1068 filepage = find_get_page(mapping, idx);
1069 if (filepage &&
1070 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1071 spin_unlock(&info->lock);
1072 wait_on_page_locked(filepage);
1073 page_cache_release(filepage);
1074 filepage = NULL;
1075 goto repeat;
1076 }
1077 spin_unlock(&info->lock);
1078 } else {
1079 shmem_swp_unmap(entry);
1080 sbinfo = SHMEM_SB(inode->i_sb);
1081 if (sbinfo->max_blocks) {
1082 spin_lock(&sbinfo->stat_lock);
1083 if (sbinfo->free_blocks == 0 ||
1084 shmem_acct_block(info->flags)) {
1085 spin_unlock(&sbinfo->stat_lock);
1086 spin_unlock(&info->lock);
1087 error = -ENOSPC;
1088 goto failed;
1089 }
1090 sbinfo->free_blocks--;
1091 inode->i_blocks += BLOCKS_PER_PAGE;
1092 spin_unlock(&sbinfo->stat_lock);
1093 } else if (shmem_acct_block(info->flags)) {
1094 spin_unlock(&info->lock);
1095 error = -ENOSPC;
1096 goto failed;
1097 }
1098
1099 if (!filepage) {
1100 spin_unlock(&info->lock);
1101 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1102 info,
1103 idx);
1104 if (!filepage) {
1105 shmem_unacct_blocks(info->flags, 1);
1106 shmem_free_blocks(inode, 1);
1107 error = -ENOMEM;
1108 goto failed;
1109 }
1110
1111 spin_lock(&info->lock);
1112 entry = shmem_swp_alloc(info, idx, sgp);
1113 if (IS_ERR(entry))
1114 error = PTR_ERR(entry);
1115 else {
1116 swap = *entry;
1117 shmem_swp_unmap(entry);
1118 }
1119 if (error || swap.val || 0 != add_to_page_cache_lru(
1120 filepage, mapping, idx, GFP_ATOMIC)) {
1121 spin_unlock(&info->lock);
1122 page_cache_release(filepage);
1123 shmem_unacct_blocks(info->flags, 1);
1124 shmem_free_blocks(inode, 1);
1125 filepage = NULL;
1126 if (error)
1127 goto failed;
1128 goto repeat;
1129 }
1130 info->flags |= SHMEM_PAGEIN;
1131 }
1132
1133 info->alloced++;
1134 spin_unlock(&info->lock);
1135 flush_dcache_page(filepage);
1136 SetPageUptodate(filepage);
1137 }
1138 done:
1139 if (*pagep != filepage) {
1140 unlock_page(filepage);
1141 *pagep = filepage;
1142 }
1143 return 0;
1144
1145 failed:
1146 if (*pagep != filepage) {
1147 unlock_page(filepage);
1148 page_cache_release(filepage);
1149 }
1150 return error;
1151 }
1152
1153 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1154 {
1155 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1156 struct page *page = NULL;
1157 unsigned long idx;
1158 int error;
1159
1160 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1161 idx += vma->vm_pgoff;
1162 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1163 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1164 return NOPAGE_SIGBUS;
1165
1166 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1167 if (error)
1168 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1169
1170 mark_page_accessed(page);
1171 return page;
1172 }
1173
1174 static int shmem_populate(struct vm_area_struct *vma,
1175 unsigned long addr, unsigned long len,
1176 pgprot_t prot, unsigned long pgoff, int nonblock)
1177 {
1178 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1179 struct mm_struct *mm = vma->vm_mm;
1180 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1181 unsigned long size;
1182
1183 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1184 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1185 return -EINVAL;
1186
1187 while ((long) len > 0) {
1188 struct page *page = NULL;
1189 int err;
1190 /*
1191 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1192 */
1193 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1194 if (err)
1195 return err;
1196 /* Page may still be null, but only if nonblock was set. */
1197 if (page) {
1198 mark_page_accessed(page);
1199 err = install_page(mm, vma, addr, page, prot);
1200 if (err) {
1201 page_cache_release(page);
1202 return err;
1203 }
1204 } else {
1205 /* No page was found just because we can't read it in
1206 * now (being here implies nonblock != 0), but the page
1207 * may exist, so set the PTE to fault it in later. */
1208 err = install_file_pte(mm, vma, addr, pgoff, prot);
1209 if (err)
1210 return err;
1211 }
1212
1213 len -= PAGE_SIZE;
1214 addr += PAGE_SIZE;
1215 pgoff++;
1216 }
1217 return 0;
1218 }
1219
1220 #ifdef CONFIG_NUMA
1221 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1222 {
1223 struct inode *i = vma->vm_file->f_dentry->d_inode;
1224 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1225 }
1226
1227 struct mempolicy *
1228 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1229 {
1230 struct inode *i = vma->vm_file->f_dentry->d_inode;
1231 unsigned long idx;
1232
1233 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1234 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1235 }
1236 #endif
1237
1238 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1239 {
1240 struct inode *inode = file->f_dentry->d_inode;
1241 struct shmem_inode_info *info = SHMEM_I(inode);
1242 int retval = -ENOMEM;
1243
1244 spin_lock(&info->lock);
1245 if (lock && !(info->flags & VM_LOCKED)) {
1246 if (!user_shm_lock(inode->i_size, user))
1247 goto out_nomem;
1248 info->flags |= VM_LOCKED;
1249 }
1250 if (!lock && (info->flags & VM_LOCKED) && user) {
1251 user_shm_unlock(inode->i_size, user);
1252 info->flags &= ~VM_LOCKED;
1253 }
1254 retval = 0;
1255 out_nomem:
1256 spin_unlock(&info->lock);
1257 return retval;
1258 }
1259
1260 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1261 {
1262 file_accessed(file);
1263 vma->vm_ops = &shmem_vm_ops;
1264 return 0;
1265 }
1266
1267 static struct inode *
1268 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1269 {
1270 struct inode *inode;
1271 struct shmem_inode_info *info;
1272 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1273
1274 if (sbinfo->max_inodes) {
1275 spin_lock(&sbinfo->stat_lock);
1276 if (!sbinfo->free_inodes) {
1277 spin_unlock(&sbinfo->stat_lock);
1278 return NULL;
1279 }
1280 sbinfo->free_inodes--;
1281 spin_unlock(&sbinfo->stat_lock);
1282 }
1283
1284 inode = new_inode(sb);
1285 if (inode) {
1286 inode->i_mode = mode;
1287 inode->i_uid = current->fsuid;
1288 inode->i_gid = current->fsgid;
1289 inode->i_blksize = PAGE_CACHE_SIZE;
1290 inode->i_blocks = 0;
1291 inode->i_mapping->a_ops = &shmem_aops;
1292 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1293 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1294 info = SHMEM_I(inode);
1295 memset(info, 0, (char *)inode - (char *)info);
1296 spin_lock_init(&info->lock);
1297 INIT_LIST_HEAD(&info->swaplist);
1298
1299 switch (mode & S_IFMT) {
1300 default:
1301 init_special_inode(inode, mode, dev);
1302 break;
1303 case S_IFREG:
1304 inode->i_op = &shmem_inode_operations;
1305 inode->i_fop = &shmem_file_operations;
1306 mpol_shared_policy_init(&info->policy);
1307 break;
1308 case S_IFDIR:
1309 inode->i_nlink++;
1310 /* Some things misbehave if size == 0 on a directory */
1311 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1312 inode->i_op = &shmem_dir_inode_operations;
1313 inode->i_fop = &simple_dir_operations;
1314 break;
1315 case S_IFLNK:
1316 /*
1317 * Must not load anything in the rbtree,
1318 * mpol_free_shared_policy will not be called.
1319 */
1320 mpol_shared_policy_init(&info->policy);
1321 break;
1322 }
1323 } else if (sbinfo->max_inodes) {
1324 spin_lock(&sbinfo->stat_lock);
1325 sbinfo->free_inodes++;
1326 spin_unlock(&sbinfo->stat_lock);
1327 }
1328 return inode;
1329 }
1330
1331 #ifdef CONFIG_TMPFS
1332 static struct inode_operations shmem_symlink_inode_operations;
1333 static struct inode_operations shmem_symlink_inline_operations;
1334
1335 /*
1336 * Normally tmpfs makes no use of shmem_prepare_write, but it
1337 * lets a tmpfs file be used read-write below the loop driver.
1338 */
1339 static int
1340 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1341 {
1342 struct inode *inode = page->mapping->host;
1343 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1344 }
1345
1346 static ssize_t
1347 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1348 {
1349 struct inode *inode = file->f_dentry->d_inode;
1350 loff_t pos;
1351 unsigned long written;
1352 ssize_t err;
1353
1354 if ((ssize_t) count < 0)
1355 return -EINVAL;
1356
1357 if (!access_ok(VERIFY_READ, buf, count))
1358 return -EFAULT;
1359
1360 down(&inode->i_sem);
1361
1362 pos = *ppos;
1363 written = 0;
1364
1365 err = generic_write_checks(file, &pos, &count, 0);
1366 if (err || !count)
1367 goto out;
1368
1369 err = remove_suid(file->f_dentry);
1370 if (err)
1371 goto out;
1372
1373 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1374
1375 do {
1376 struct page *page = NULL;
1377 unsigned long bytes, index, offset;
1378 char *kaddr;
1379 int left;
1380
1381 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1382 index = pos >> PAGE_CACHE_SHIFT;
1383 bytes = PAGE_CACHE_SIZE - offset;
1384 if (bytes > count)
1385 bytes = count;
1386
1387 /*
1388 * We don't hold page lock across copy from user -
1389 * what would it guard against? - so no deadlock here.
1390 * But it still may be a good idea to prefault below.
1391 */
1392
1393 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1394 if (err)
1395 break;
1396
1397 left = bytes;
1398 if (PageHighMem(page)) {
1399 volatile unsigned char dummy;
1400 __get_user(dummy, buf);
1401 __get_user(dummy, buf + bytes - 1);
1402
1403 kaddr = kmap_atomic(page, KM_USER0);
1404 left = __copy_from_user_inatomic(kaddr + offset,
1405 buf, bytes);
1406 kunmap_atomic(kaddr, KM_USER0);
1407 }
1408 if (left) {
1409 kaddr = kmap(page);
1410 left = __copy_from_user(kaddr + offset, buf, bytes);
1411 kunmap(page);
1412 }
1413
1414 written += bytes;
1415 count -= bytes;
1416 pos += bytes;
1417 buf += bytes;
1418 if (pos > inode->i_size)
1419 i_size_write(inode, pos);
1420
1421 flush_dcache_page(page);
1422 set_page_dirty(page);
1423 mark_page_accessed(page);
1424 page_cache_release(page);
1425
1426 if (left) {
1427 pos -= left;
1428 written -= left;
1429 err = -EFAULT;
1430 break;
1431 }
1432
1433 /*
1434 * Our dirty pages are not counted in nr_dirty,
1435 * and we do not attempt to balance dirty pages.
1436 */
1437
1438 cond_resched();
1439 } while (count);
1440
1441 *ppos = pos;
1442 if (written)
1443 err = written;
1444 out:
1445 up(&inode->i_sem);
1446 return err;
1447 }
1448
1449 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1450 {
1451 struct inode *inode = filp->f_dentry->d_inode;
1452 struct address_space *mapping = inode->i_mapping;
1453 unsigned long index, offset;
1454
1455 index = *ppos >> PAGE_CACHE_SHIFT;
1456 offset = *ppos & ~PAGE_CACHE_MASK;
1457
1458 for (;;) {
1459 struct page *page = NULL;
1460 unsigned long end_index, nr, ret;
1461 loff_t i_size = i_size_read(inode);
1462
1463 end_index = i_size >> PAGE_CACHE_SHIFT;
1464 if (index > end_index)
1465 break;
1466 if (index == end_index) {
1467 nr = i_size & ~PAGE_CACHE_MASK;
1468 if (nr <= offset)
1469 break;
1470 }
1471
1472 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1473 if (desc->error) {
1474 if (desc->error == -EINVAL)
1475 desc->error = 0;
1476 break;
1477 }
1478
1479 /*
1480 * We must evaluate after, since reads (unlike writes)
1481 * are called without i_sem protection against truncate
1482 */
1483 nr = PAGE_CACHE_SIZE;
1484 i_size = i_size_read(inode);
1485 end_index = i_size >> PAGE_CACHE_SHIFT;
1486 if (index == end_index) {
1487 nr = i_size & ~PAGE_CACHE_MASK;
1488 if (nr <= offset) {
1489 if (page)
1490 page_cache_release(page);
1491 break;
1492 }
1493 }
1494 nr -= offset;
1495
1496 if (page) {
1497 /*
1498 * If users can be writing to this page using arbitrary
1499 * virtual addresses, take care about potential aliasing
1500 * before reading the page on the kernel side.
1501 */
1502 if (mapping_writably_mapped(mapping))
1503 flush_dcache_page(page);
1504 /*
1505 * Mark the page accessed if we read the beginning.
1506 */
1507 if (!offset)
1508 mark_page_accessed(page);
1509 } else
1510 page = ZERO_PAGE(0);
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