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[PATCH] kill extraneous printk in kernel_restart()
[linux-2.6.22.y-op.git] / mm / shmem.c
blobeda907c3a86aa14399e8a30aab95ec8dc8cff88c
1 /*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
12 *
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16 *
17 * This file is released under the GPL.
18 */
19
20 /*
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
24 */
25
26 #include <linux/module.h>
27 #include <linux/init.h>
28 #include <linux/fs.h>
29 #include <linux/mm.h>
30 #include <linux/mman.h>
31 #include <linux/file.h>
32 #include <linux/swap.h>
33 #include <linux/pagemap.h>
34 #include <linux/string.h>
35 #include <linux/slab.h>
36 #include <linux/backing-dev.h>
37 #include <linux/shmem_fs.h>
38 #include <linux/mount.h>
39 #include <linux/writeback.h>
40 #include <linux/vfs.h>
41 #include <linux/blkdev.h>
42 #include <linux/security.h>
43 #include <linux/swapops.h>
44 #include <linux/mempolicy.h>
45 #include <linux/namei.h>
46 #include <linux/ctype.h>
47 #include <linux/migrate.h>
48 #include <linux/highmem.h>
49
50 #include <asm/uaccess.h>
51 #include <asm/div64.h>
52 #include <asm/pgtable.h>
53
54 /* This magic number is used in glibc for posix shared memory */
55 #define TMPFS_MAGIC 0x01021994
56
57 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
58 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
59 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
60
61 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
62 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
63
64 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
65
66 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
67 #define SHMEM_PAGEIN VM_READ
68 #define SHMEM_TRUNCATE VM_WRITE
69
70 /* Definition to limit shmem_truncate's steps between cond_rescheds */
71 #define LATENCY_LIMIT 64
72
73 /* Pretend that each entry is of this size in directory's i_size */
74 #define BOGO_DIRENT_SIZE 20
75
76 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
77 enum sgp_type {
78 SGP_QUICK, /* don't try more than file page cache lookup */
79 SGP_READ, /* don't exceed i_size, don't allocate page */
80 SGP_CACHE, /* don't exceed i_size, may allocate page */
81 SGP_WRITE, /* may exceed i_size, may allocate page */
82 };
83
84 static int shmem_getpage(struct inode *inode, unsigned long idx,
85 struct page **pagep, enum sgp_type sgp, int *type);
86
87 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
88 {
89 /*
90 * The above definition of ENTRIES_PER_PAGE, and the use of
91 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
92 * might be reconsidered if it ever diverges from PAGE_SIZE.
93 */
94 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
95 }
96
97 static inline void shmem_dir_free(struct page *page)
98 {
99 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
100 }
101
102 static struct page **shmem_dir_map(struct page *page)
103 {
104 return (struct page **)kmap_atomic(page, KM_USER0);
105 }
106
107 static inline void shmem_dir_unmap(struct page **dir)
108 {
109 kunmap_atomic(dir, KM_USER0);
110 }
111
112 static swp_entry_t *shmem_swp_map(struct page *page)
113 {
114 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
115 }
116
117 static inline void shmem_swp_balance_unmap(void)
118 {
119 /*
120 * When passing a pointer to an i_direct entry, to code which
121 * also handles indirect entries and so will shmem_swp_unmap,
122 * we must arrange for the preempt count to remain in balance.
123 * What kmap_atomic of a lowmem page does depends on config
124 * and architecture, so pretend to kmap_atomic some lowmem page.
125 */
126 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
127 }
128
129 static inline void shmem_swp_unmap(swp_entry_t *entry)
130 {
131 kunmap_atomic(entry, KM_USER1);
132 }
133
134 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
135 {
136 return sb->s_fs_info;
137 }
138
139 /*
140 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
141 * for shared memory and for shared anonymous (/dev/zero) mappings
142 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
143 * consistent with the pre-accounting of private mappings ...
144 */
145 static inline int shmem_acct_size(unsigned long flags, loff_t size)
146 {
147 return (flags & VM_ACCOUNT)?
148 security_vm_enough_memory(VM_ACCT(size)): 0;
149 }
150
151 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
152 {
153 if (flags & VM_ACCOUNT)
154 vm_unacct_memory(VM_ACCT(size));
155 }
156
157 /*
158 * ... whereas tmpfs objects are accounted incrementally as
159 * pages are allocated, in order to allow huge sparse files.
160 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
161 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
162 */
163 static inline int shmem_acct_block(unsigned long flags)
164 {
165 return (flags & VM_ACCOUNT)?
166 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
167 }
168
169 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
170 {
171 if (!(flags & VM_ACCOUNT))
172 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
173 }
174
175 static struct super_operations shmem_ops;
176 static const struct address_space_operations shmem_aops;
177 static struct file_operations shmem_file_operations;
178 static struct inode_operations shmem_inode_operations;
179 static struct inode_operations shmem_dir_inode_operations;
180 static struct vm_operations_struct shmem_vm_ops;
181
182 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
183 .ra_pages = 0, /* No readahead */
184 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
185 .unplug_io_fn = default_unplug_io_fn,
186 };
187
188 static LIST_HEAD(shmem_swaplist);
189 static DEFINE_SPINLOCK(shmem_swaplist_lock);
190
191 static void shmem_free_blocks(struct inode *inode, long pages)
192 {
193 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
194 if (sbinfo->max_blocks) {
195 spin_lock(&sbinfo->stat_lock);
196 sbinfo->free_blocks += pages;
197 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
198 spin_unlock(&sbinfo->stat_lock);
199 }
200 }
201
202 /*
203 * shmem_recalc_inode - recalculate the size of an inode
204 *
205 * @inode: inode to recalc
206 *
207 * We have to calculate the free blocks since the mm can drop
208 * undirtied hole pages behind our back.
209 *
210 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
211 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
212 *
213 * It has to be called with the spinlock held.
214 */
215 static void shmem_recalc_inode(struct inode *inode)
216 {
217 struct shmem_inode_info *info = SHMEM_I(inode);
218 long freed;
219
220 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
221 if (freed > 0) {
222 info->alloced -= freed;
223 shmem_unacct_blocks(info->flags, freed);
224 shmem_free_blocks(inode, freed);
225 }
226 }
227
228 /*
229 * shmem_swp_entry - find the swap vector position in the info structure
230 *
231 * @info: info structure for the inode
232 * @index: index of the page to find
233 * @page: optional page to add to the structure. Has to be preset to
234 * all zeros
235 *
236 * If there is no space allocated yet it will return NULL when
237 * page is NULL, else it will use the page for the needed block,
238 * setting it to NULL on return to indicate that it has been used.
239 *
240 * The swap vector is organized the following way:
241 *
242 * There are SHMEM_NR_DIRECT entries directly stored in the
243 * shmem_inode_info structure. So small files do not need an addional
244 * allocation.
245 *
246 * For pages with index > SHMEM_NR_DIRECT there is the pointer
247 * i_indirect which points to a page which holds in the first half
248 * doubly indirect blocks, in the second half triple indirect blocks:
249 *
250 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
251 * following layout (for SHMEM_NR_DIRECT == 16):
252 *
253 * i_indirect -> dir --> 16-19
254 * | +-> 20-23
255 * |
256 * +-->dir2 --> 24-27
257 * | +-> 28-31
258 * | +-> 32-35
259 * | +-> 36-39
260 * |
261 * +-->dir3 --> 40-43
262 * +-> 44-47
263 * +-> 48-51
264 * +-> 52-55
265 */
266 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
267 {
268 unsigned long offset;
269 struct page **dir;
270 struct page *subdir;
271
272 if (index < SHMEM_NR_DIRECT) {
273 shmem_swp_balance_unmap();
274 return info->i_direct+index;
275 }
276 if (!info->i_indirect) {
277 if (page) {
278 info->i_indirect = *page;
279 *page = NULL;
280 }
281 return NULL; /* need another page */
282 }
283
284 index -= SHMEM_NR_DIRECT;
285 offset = index % ENTRIES_PER_PAGE;
286 index /= ENTRIES_PER_PAGE;
287 dir = shmem_dir_map(info->i_indirect);
288
289 if (index >= ENTRIES_PER_PAGE/2) {
290 index -= ENTRIES_PER_PAGE/2;
291 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
292 index %= ENTRIES_PER_PAGE;
293 subdir = *dir;
294 if (!subdir) {
295 if (page) {
296 *dir = *page;
297 *page = NULL;
298 }
299 shmem_dir_unmap(dir);
300 return NULL; /* need another page */
301 }
302 shmem_dir_unmap(dir);
303 dir = shmem_dir_map(subdir);
304 }
305
306 dir += index;
307 subdir = *dir;
308 if (!subdir) {
309 if (!page || !(subdir = *page)) {
310 shmem_dir_unmap(dir);
311 return NULL; /* need a page */
312 }
313 *dir = subdir;
314 *page = NULL;
315 }
316 shmem_dir_unmap(dir);
317 return shmem_swp_map(subdir) + offset;
318 }
319
320 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
321 {
322 long incdec = value? 1: -1;
323
324 entry->val = value;
325 info->swapped += incdec;
326 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
327 struct page *page = kmap_atomic_to_page(entry);
328 set_page_private(page, page_private(page) + incdec);
329 }
330 }
331
332 /*
333 * shmem_swp_alloc - get the position of the swap entry for the page.
334 * If it does not exist allocate the entry.
335 *
336 * @info: info structure for the inode
337 * @index: index of the page to find
338 * @sgp: check and recheck i_size? skip allocation?
339 */
340 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
341 {
342 struct inode *inode = &info->vfs_inode;
343 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
344 struct page *page = NULL;
345 swp_entry_t *entry;
346
347 if (sgp != SGP_WRITE &&
348 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
349 return ERR_PTR(-EINVAL);
350
351 while (!(entry = shmem_swp_entry(info, index, &page))) {
352 if (sgp == SGP_READ)
353 return shmem_swp_map(ZERO_PAGE(0));
354 /*
355 * Test free_blocks against 1 not 0, since we have 1 data
356 * page (and perhaps indirect index pages) yet to allocate:
357 * a waste to allocate index if we cannot allocate data.
358 */
359 if (sbinfo->max_blocks) {
360 spin_lock(&sbinfo->stat_lock);
361 if (sbinfo->free_blocks <= 1) {
362 spin_unlock(&sbinfo->stat_lock);
363 return ERR_PTR(-ENOSPC);
364 }
365 sbinfo->free_blocks--;
366 inode->i_blocks += BLOCKS_PER_PAGE;
367 spin_unlock(&sbinfo->stat_lock);
368 }
369
370 spin_unlock(&info->lock);
371 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
372 if (page)
373 set_page_private(page, 0);
374 spin_lock(&info->lock);
375
376 if (!page) {
377 shmem_free_blocks(inode, 1);
378 return ERR_PTR(-ENOMEM);
379 }
380 if (sgp != SGP_WRITE &&
381 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
382 entry = ERR_PTR(-EINVAL);
383 break;
384 }
385 if (info->next_index <= index)
386 info->next_index = index + 1;
387 }
388 if (page) {
389 /* another task gave its page, or truncated the file */
390 shmem_free_blocks(inode, 1);
391 shmem_dir_free(page);
392 }
393 if (info->next_index <= index && !IS_ERR(entry))
394 info->next_index = index + 1;
395 return entry;
396 }
397
398 /*
399 * shmem_free_swp - free some swap entries in a directory
400 *
401 * @dir: pointer to the directory
402 * @edir: pointer after last entry of the directory
403 */
404 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
405 {
406 swp_entry_t *ptr;
407 int freed = 0;
408
409 for (ptr = dir; ptr < edir; ptr++) {
410 if (ptr->val) {
411 free_swap_and_cache(*ptr);
412 *ptr = (swp_entry_t){0};
413 freed++;
414 }
415 }
416 return freed;
417 }
418
419 static int shmem_map_and_free_swp(struct page *subdir,
420 int offset, int limit, struct page ***dir)
421 {
422 swp_entry_t *ptr;
423 int freed = 0;
424
425 ptr = shmem_swp_map(subdir);
426 for (; offset < limit; offset += LATENCY_LIMIT) {
427 int size = limit - offset;
428 if (size > LATENCY_LIMIT)
429 size = LATENCY_LIMIT;
430 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
431 if (need_resched()) {
432 shmem_swp_unmap(ptr);
433 if (*dir) {
434 shmem_dir_unmap(*dir);
435 *dir = NULL;
436 }
437 cond_resched();
438 ptr = shmem_swp_map(subdir);
439 }
440 }
441 shmem_swp_unmap(ptr);
442 return freed;
443 }
444
445 static void shmem_free_pages(struct list_head *next)
446 {
447 struct page *page;
448 int freed = 0;
449
450 do {
451 page = container_of(next, struct page, lru);
452 next = next->next;
453 shmem_dir_free(page);
454 freed++;
455 if (freed >= LATENCY_LIMIT) {
456 cond_resched();
457 freed = 0;
458 }
459 } while (next);
460 }
461
462 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
463 {
464 struct shmem_inode_info *info = SHMEM_I(inode);
465 unsigned long idx;
466 unsigned long size;
467 unsigned long limit;
468 unsigned long stage;
469 unsigned long diroff;
470 struct page **dir;
471 struct page *topdir;
472 struct page *middir;
473 struct page *subdir;
474 swp_entry_t *ptr;
475 LIST_HEAD(pages_to_free);
476 long nr_pages_to_free = 0;
477 long nr_swaps_freed = 0;
478 int offset;
479 int freed;
480 int punch_hole = 0;
481
482 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
483 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
484 if (idx >= info->next_index)
485 return;
486
487 spin_lock(&info->lock);
488 info->flags |= SHMEM_TRUNCATE;
489 if (likely(end == (loff_t) -1)) {
490 limit = info->next_index;
491 info->next_index = idx;
492 } else {
493 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
494 if (limit > info->next_index)
495 limit = info->next_index;
496 punch_hole = 1;
497 }
498
499 topdir = info->i_indirect;
500 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
501 info->i_indirect = NULL;
502 nr_pages_to_free++;
503 list_add(&topdir->lru, &pages_to_free);
504 }
505 spin_unlock(&info->lock);
506
507 if (info->swapped && idx < SHMEM_NR_DIRECT) {
508 ptr = info->i_direct;
509 size = limit;
510 if (size > SHMEM_NR_DIRECT)
511 size = SHMEM_NR_DIRECT;
512 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
513 }
514 if (!topdir)
515 goto done2;
516
517 BUG_ON(limit <= SHMEM_NR_DIRECT);
518 limit -= SHMEM_NR_DIRECT;
519 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
520 offset = idx % ENTRIES_PER_PAGE;
521 idx -= offset;
522
523 dir = shmem_dir_map(topdir);
524 stage = ENTRIES_PER_PAGEPAGE/2;
525 if (idx < ENTRIES_PER_PAGEPAGE/2) {
526 middir = topdir;
527 diroff = idx/ENTRIES_PER_PAGE;
528 } else {
529 dir += ENTRIES_PER_PAGE/2;
530 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
531 while (stage <= idx)
532 stage += ENTRIES_PER_PAGEPAGE;
533 middir = *dir;
534 if (*dir) {
535 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
536 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
537 if (!diroff && !offset) {
538 *dir = NULL;
539 nr_pages_to_free++;
540 list_add(&middir->lru, &pages_to_free);
541 }
542 shmem_dir_unmap(dir);
543 dir = shmem_dir_map(middir);
544 } else {
545 diroff = 0;
546 offset = 0;
547 idx = stage;
548 }
549 }
550
551 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
552 if (unlikely(idx == stage)) {
553 shmem_dir_unmap(dir);
554 dir = shmem_dir_map(topdir) +
555 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
556 while (!*dir) {
557 dir++;
558 idx += ENTRIES_PER_PAGEPAGE;
559 if (idx >= limit)
560 goto done1;
561 }
562 stage = idx + ENTRIES_PER_PAGEPAGE;
563 middir = *dir;
564 *dir = NULL;
565 nr_pages_to_free++;
566 list_add(&middir->lru, &pages_to_free);
567 shmem_dir_unmap(dir);
568 cond_resched();
569 dir = shmem_dir_map(middir);
570 diroff = 0;
571 }
572 subdir = dir[diroff];
573 if (subdir && page_private(subdir)) {
574 size = limit - idx;
575 if (size > ENTRIES_PER_PAGE)
576 size = ENTRIES_PER_PAGE;
577 freed = shmem_map_and_free_swp(subdir,
578 offset, size, &dir);
579 if (!dir)
580 dir = shmem_dir_map(middir);
581 nr_swaps_freed += freed;
582 if (offset)
583 spin_lock(&info->lock);
584 set_page_private(subdir, page_private(subdir) - freed);
585 if (offset)
586 spin_unlock(&info->lock);
587 if (!punch_hole)
588 BUG_ON(page_private(subdir) > offset);
589 }
590 if (offset)
591 offset = 0;
592 else if (subdir && !page_private(subdir)) {
593 dir[diroff] = NULL;
594 nr_pages_to_free++;
595 list_add(&subdir->lru, &pages_to_free);
596 }
597 }
598 done1:
599 shmem_dir_unmap(dir);
600 done2:
601 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
602 /*
603 * Call truncate_inode_pages again: racing shmem_unuse_inode
604 * may have swizzled a page in from swap since vmtruncate or
605 * generic_delete_inode did it, before we lowered next_index.
606 * Also, though shmem_getpage checks i_size before adding to
607 * cache, no recheck after: so fix the narrow window there too.
608 */
609 truncate_inode_pages_range(inode->i_mapping, start, end);
610 }
611
612 spin_lock(&info->lock);
613 info->flags &= ~SHMEM_TRUNCATE;
614 info->swapped -= nr_swaps_freed;
615 if (nr_pages_to_free)
616 shmem_free_blocks(inode, nr_pages_to_free);
617 shmem_recalc_inode(inode);
618 spin_unlock(&info->lock);
619
620 /*
621 * Empty swap vector directory pages to be freed?
622 */
623 if (!list_empty(&pages_to_free)) {
624 pages_to_free.prev->next = NULL;
625 shmem_free_pages(pages_to_free.next);
626 }
627 }
628
629 static void shmem_truncate(struct inode *inode)
630 {
631 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
632 }
633
634 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
635 {
636 struct inode *inode = dentry->d_inode;
637 struct page *page = NULL;
638 int error;
639
640 if (attr->ia_valid & ATTR_SIZE) {
641 if (attr->ia_size < inode->i_size) {
642 /*
643 * If truncating down to a partial page, then
644 * if that page is already allocated, hold it
645 * in memory until the truncation is over, so
646 * truncate_partial_page cannnot miss it were
647 * it assigned to swap.
648 */
649 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
650 (void) shmem_getpage(inode,
651 attr->ia_size>>PAGE_CACHE_SHIFT,
652 &page, SGP_READ, NULL);
653 }
654 /*
655 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
656 * detect if any pages might have been added to cache
657 * after truncate_inode_pages. But we needn't bother
658 * if it's being fully truncated to zero-length: the
659 * nrpages check is efficient enough in that case.
660 */
661 if (attr->ia_size) {
662 struct shmem_inode_info *info = SHMEM_I(inode);
663 spin_lock(&info->lock);
664 info->flags &= ~SHMEM_PAGEIN;
665 spin_unlock(&info->lock);
666 }
667 }
668 }
669
670 error = inode_change_ok(inode, attr);
671 if (!error)
672 error = inode_setattr(inode, attr);
673 if (page)
674 page_cache_release(page);
675 return error;
676 }
677
678 static void shmem_delete_inode(struct inode *inode)
679 {
680 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
681 struct shmem_inode_info *info = SHMEM_I(inode);
682
683 if (inode->i_op->truncate == shmem_truncate) {
684 truncate_inode_pages(inode->i_mapping, 0);
685 shmem_unacct_size(info->flags, inode->i_size);
686 inode->i_size = 0;
687 shmem_truncate(inode);
688 if (!list_empty(&info->swaplist)) {
689 spin_lock(&shmem_swaplist_lock);
690 list_del_init(&info->swaplist);
691 spin_unlock(&shmem_swaplist_lock);
692 }
693 }
694 BUG_ON(inode->i_blocks);
695 if (sbinfo->max_inodes) {
696 spin_lock(&sbinfo->stat_lock);
697 sbinfo->free_inodes++;
698 spin_unlock(&sbinfo->stat_lock);
699 }
700 clear_inode(inode);
701 }
702
703 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
704 {
705 swp_entry_t *ptr;
706
707 for (ptr = dir; ptr < edir; ptr++) {
708 if (ptr->val == entry.val)
709 return ptr - dir;
710 }
711 return -1;
712 }
713
714 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
715 {
716 struct inode *inode;
717 unsigned long idx;
718 unsigned long size;
719 unsigned long limit;
720 unsigned long stage;
721 struct page **dir;
722 struct page *subdir;
723 swp_entry_t *ptr;
724 int offset;
725
726 idx = 0;
727 ptr = info->i_direct;
728 spin_lock(&info->lock);
729 limit = info->next_index;
730 size = limit;
731 if (size > SHMEM_NR_DIRECT)
732 size = SHMEM_NR_DIRECT;
733 offset = shmem_find_swp(entry, ptr, ptr+size);
734 if (offset >= 0) {
735 shmem_swp_balance_unmap();
736 goto found;
737 }
738 if (!info->i_indirect)
739 goto lost2;
740
741 dir = shmem_dir_map(info->i_indirect);
742 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
743
744 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
745 if (unlikely(idx == stage)) {
746 shmem_dir_unmap(dir-1);
747 dir = shmem_dir_map(info->i_indirect) +
748 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
749 while (!*dir) {
750 dir++;
751 idx += ENTRIES_PER_PAGEPAGE;
752 if (idx >= limit)
753 goto lost1;
754 }
755 stage = idx + ENTRIES_PER_PAGEPAGE;
756 subdir = *dir;
757 shmem_dir_unmap(dir);
758 dir = shmem_dir_map(subdir);
759 }
760 subdir = *dir;
761 if (subdir && page_private(subdir)) {
762 ptr = shmem_swp_map(subdir);
763 size = limit - idx;
764 if (size > ENTRIES_PER_PAGE)
765 size = ENTRIES_PER_PAGE;
766 offset = shmem_find_swp(entry, ptr, ptr+size);
767 if (offset >= 0) {
768 shmem_dir_unmap(dir);
769 goto found;
770 }
771 shmem_swp_unmap(ptr);
772 }
773 }
774 lost1:
775 shmem_dir_unmap(dir-1);
776 lost2:
777 spin_unlock(&info->lock);
778 return 0;
779 found:
780 idx += offset;
781 inode = &info->vfs_inode;
782 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
783 info->flags |= SHMEM_PAGEIN;
784 shmem_swp_set(info, ptr + offset, 0);
785 }
786 shmem_swp_unmap(ptr);
787 spin_unlock(&info->lock);
788 /*
789 * Decrement swap count even when the entry is left behind:
790 * try_to_unuse will skip over mms, then reincrement count.
791 */
792 swap_free(entry);
793 return 1;
794 }
795
796 /*
797 * shmem_unuse() search for an eventually swapped out shmem page.
798 */
799 int shmem_unuse(swp_entry_t entry, struct page *page)
800 {
801 struct list_head *p, *next;
802 struct shmem_inode_info *info;
803 int found = 0;
804
805 spin_lock(&shmem_swaplist_lock);
806 list_for_each_safe(p, next, &shmem_swaplist) {
807 info = list_entry(p, struct shmem_inode_info, swaplist);
808 if (!info->swapped)
809 list_del_init(&info->swaplist);
810 else if (shmem_unuse_inode(info, entry, page)) {
811 /* move head to start search for next from here */
812 list_move_tail(&shmem_swaplist, &info->swaplist);
813 found = 1;
814 break;
815 }
816 }
817 spin_unlock(&shmem_swaplist_lock);
818 return found;
819 }
820
821 /*
822 * Move the page from the page cache to the swap cache.
823 */
824 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
825 {
826 struct shmem_inode_info *info;
827 swp_entry_t *entry, swap;
828 struct address_space *mapping;
829 unsigned long index;
830 struct inode *inode;
831
832 BUG_ON(!PageLocked(page));
833 BUG_ON(page_mapped(page));
834
835 mapping = page->mapping;
836 index = page->index;
837 inode = mapping->host;
838 info = SHMEM_I(inode);
839 if (info->flags & VM_LOCKED)
840 goto redirty;
841 swap = get_swap_page();
842 if (!swap.val)
843 goto redirty;
844
845 spin_lock(&info->lock);
846 shmem_recalc_inode(inode);
847 if (index >= info->next_index) {
848 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
849 goto unlock;
850 }
851 entry = shmem_swp_entry(info, index, NULL);
852 BUG_ON(!entry);
853 BUG_ON(entry->val);
854
855 if (move_to_swap_cache(page, swap) == 0) {
856 shmem_swp_set(info, entry, swap.val);
857 shmem_swp_unmap(entry);
858 spin_unlock(&info->lock);
859 if (list_empty(&info->swaplist)) {
860 spin_lock(&shmem_swaplist_lock);
861 /* move instead of add in case we're racing */
862 list_move_tail(&info->swaplist, &shmem_swaplist);
863 spin_unlock(&shmem_swaplist_lock);
864 }
865 unlock_page(page);
866 return 0;
867 }
868
869 shmem_swp_unmap(entry);
870 unlock:
871 spin_unlock(&info->lock);
872 swap_free(swap);
873 redirty:
874 set_page_dirty(page);
875 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */
876 }
877
878 #ifdef CONFIG_NUMA
879 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
880 {
881 char *nodelist = strchr(value, ':');
882 int err = 1;
883
884 if (nodelist) {
885 /* NUL-terminate policy string */
886 *nodelist++ = '\0';
887 if (nodelist_parse(nodelist, *policy_nodes))
888 goto out;
889 }
890 if (!strcmp(value, "default")) {
891 *policy = MPOL_DEFAULT;
892 /* Don't allow a nodelist */
893 if (!nodelist)
894 err = 0;
895 } else if (!strcmp(value, "prefer")) {
896 *policy = MPOL_PREFERRED;
897 /* Insist on a nodelist of one node only */
898 if (nodelist) {
899 char *rest = nodelist;
900 while (isdigit(*rest))
901 rest++;
902 if (!*rest)
903 err = 0;
904 }
905 } else if (!strcmp(value, "bind")) {
906 *policy = MPOL_BIND;
907 /* Insist on a nodelist */
908 if (nodelist)
909 err = 0;
910 } else if (!strcmp(value, "interleave")) {
911 *policy = MPOL_INTERLEAVE;
912 /* Default to nodes online if no nodelist */
913 if (!nodelist)
914 *policy_nodes = node_online_map;
915 err = 0;
916 }
917 out:
918 /* Restore string for error message */
919 if (nodelist)
920 *--nodelist = ':';
921 return err;
922 }
923
924 static struct page *shmem_swapin_async(struct shared_policy *p,
925 swp_entry_t entry, unsigned long idx)
926 {
927 struct page *page;
928 struct vm_area_struct pvma;
929
930 /* Create a pseudo vma that just contains the policy */
931 memset(&pvma, 0, sizeof(struct vm_area_struct));
932 pvma.vm_end = PAGE_SIZE;
933 pvma.vm_pgoff = idx;
934 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
935 page = read_swap_cache_async(entry, &pvma, 0);
936 mpol_free(pvma.vm_policy);
937 return page;
938 }
939
940 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
941 unsigned long idx)
942 {
943 struct shared_policy *p = &info->policy;
944 int i, num;
945 struct page *page;
946 unsigned long offset;
947
948 num = valid_swaphandles(entry, &offset);
949 for (i = 0; i < num; offset++, i++) {
950 page = shmem_swapin_async(p,
951 swp_entry(swp_type(entry), offset), idx);
952 if (!page)
953 break;
954 page_cache_release(page);
955 }
956 lru_add_drain(); /* Push any new pages onto the LRU now */
957 return shmem_swapin_async(p, entry, idx);
958 }
959
960 static struct page *
961 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
962 unsigned long idx)
963 {
964 struct vm_area_struct pvma;
965 struct page *page;
966
967 memset(&pvma, 0, sizeof(struct vm_area_struct));
968 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
969 pvma.vm_pgoff = idx;
970 pvma.vm_end = PAGE_SIZE;
971 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
972 mpol_free(pvma.vm_policy);
973 return page;
974 }
975 #else
976 static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
977 {
978 return 1;
979 }
980
981 static inline struct page *
982 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
983 {
984 swapin_readahead(entry, 0, NULL);
985 return read_swap_cache_async(entry, NULL, 0);
986 }
987
988 static inline struct page *
989 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
990 {
991 return alloc_page(gfp | __GFP_ZERO);
992 }
993 #endif
994
995 /*
996 * shmem_getpage - either get the page from swap or allocate a new one
997 *
998 * If we allocate a new one we do not mark it dirty. That's up to the
999 * vm. If we swap it in we mark it dirty since we also free the swap
1000 * entry since a page cannot live in both the swap and page cache
1001 */
1002 static int shmem_getpage(struct inode *inode, unsigned long idx,
1003 struct page **pagep, enum sgp_type sgp, int *type)
1004 {
1005 struct address_space *mapping = inode->i_mapping;
1006 struct shmem_inode_info *info = SHMEM_I(inode);
1007 struct shmem_sb_info *sbinfo;
1008 struct page *filepage = *pagep;
1009 struct page *swappage;
1010 swp_entry_t *entry;
1011 swp_entry_t swap;
1012 int error;
1013
1014 if (idx >= SHMEM_MAX_INDEX)
1015 return -EFBIG;
1016 /*
1017 * Normally, filepage is NULL on entry, and either found
1018 * uptodate immediately, or allocated and zeroed, or read
1019 * in under swappage, which is then assigned to filepage.
1020 * But shmem_prepare_write passes in a locked filepage,
1021 * which may be found not uptodate by other callers too,
1022 * and may need to be copied from the swappage read in.
1023 */
1024 repeat:
1025 if (!filepage)
1026 filepage = find_lock_page(mapping, idx);
1027 if (filepage && PageUptodate(filepage))
1028 goto done;
1029 error = 0;
1030 if (sgp == SGP_QUICK)
1031 goto failed;
1032
1033 spin_lock(&info->lock);
1034 shmem_recalc_inode(inode);
1035 entry = shmem_swp_alloc(info, idx, sgp);
1036 if (IS_ERR(entry)) {
1037 spin_unlock(&info->lock);
1038 error = PTR_ERR(entry);
1039 goto failed;
1040 }
1041 swap = *entry;
1042
1043 if (swap.val) {
1044 /* Look it up and read it in.. */
1045 swappage = lookup_swap_cache(swap);
1046 if (!swappage) {
1047 shmem_swp_unmap(entry);
1048 /* here we actually do the io */
1049 if (type && *type == VM_FAULT_MINOR) {
1050 __count_vm_event(PGMAJFAULT);
1051 *type = VM_FAULT_MAJOR;
1052 }
1053 spin_unlock(&info->lock);
1054 swappage = shmem_swapin(info, swap, idx);
1055 if (!swappage) {
1056 spin_lock(&info->lock);
1057 entry = shmem_swp_alloc(info, idx, sgp);
1058 if (IS_ERR(entry))
1059 error = PTR_ERR(entry);
1060 else {
1061 if (entry->val == swap.val)
1062 error = -ENOMEM;
1063 shmem_swp_unmap(entry);
1064 }
1065 spin_unlock(&info->lock);
1066 if (error)
1067 goto failed;
1068 goto repeat;
1069 }
1070 wait_on_page_locked(swappage);
1071 page_cache_release(swappage);
1072 goto repeat;
1073 }
1074
1075 /* We have to do this with page locked to prevent races */
1076 if (TestSetPageLocked(swappage)) {
1077 shmem_swp_unmap(entry);
1078 spin_unlock(&info->lock);
1079 wait_on_page_locked(swappage);
1080 page_cache_release(swappage);
1081 goto repeat;
1082 }
1083 if (PageWriteback(swappage)) {
1084 shmem_swp_unmap(entry);
1085 spin_unlock(&info->lock);
1086 wait_on_page_writeback(swappage);
1087 unlock_page(swappage);
1088 page_cache_release(swappage);
1089 goto repeat;
1090 }
1091 if (!PageUptodate(swappage)) {
1092 shmem_swp_unmap(entry);
1093 spin_unlock(&info->lock);
1094 unlock_page(swappage);
1095 page_cache_release(swappage);
1096 error = -EIO;
1097 goto failed;
1098 }
1099
1100 if (filepage) {
1101 shmem_swp_set(info, entry, 0);
1102 shmem_swp_unmap(entry);
1103 delete_from_swap_cache(swappage);
1104 spin_unlock(&info->lock);
1105 copy_highpage(filepage, swappage);
1106 unlock_page(swappage);
1107 page_cache_release(swappage);
1108 flush_dcache_page(filepage);
1109 SetPageUptodate(filepage);
1110 set_page_dirty(filepage);
1111 swap_free(swap);
1112 } else if (!(error = move_from_swap_cache(
1113 swappage, idx, mapping))) {
1114 info->flags |= SHMEM_PAGEIN;
1115 shmem_swp_set(info, entry, 0);
1116 shmem_swp_unmap(entry);
1117 spin_unlock(&info->lock);
1118 filepage = swappage;
1119 swap_free(swap);
1120 } else {
1121 shmem_swp_unmap(entry);
1122 spin_unlock(&info->lock);
1123 unlock_page(swappage);
1124 page_cache_release(swappage);
1125 if (error == -ENOMEM) {
1126 /* let kswapd refresh zone for GFP_ATOMICs */
1127 blk_congestion_wait(WRITE, HZ/50);
1128 }
1129 goto repeat;
1130 }
1131 } else if (sgp == SGP_READ && !filepage) {
1132 shmem_swp_unmap(entry);
1133 filepage = find_get_page(mapping, idx);
1134 if (filepage &&
1135 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1136 spin_unlock(&info->lock);
1137 wait_on_page_locked(filepage);
1138 page_cache_release(filepage);
1139 filepage = NULL;
1140 goto repeat;
1141 }
1142 spin_unlock(&info->lock);
1143 } else {
1144 shmem_swp_unmap(entry);
1145 sbinfo = SHMEM_SB(inode->i_sb);
1146 if (sbinfo->max_blocks) {
1147 spin_lock(&sbinfo->stat_lock);
1148 if (sbinfo->free_blocks == 0 ||
1149 shmem_acct_block(info->flags)) {
1150 spin_unlock(&sbinfo->stat_lock);
1151 spin_unlock(&info->lock);
1152 error = -ENOSPC;
1153 goto failed;
1154 }
1155 sbinfo->free_blocks--;
1156 inode->i_blocks += BLOCKS_PER_PAGE;
1157 spin_unlock(&sbinfo->stat_lock);
1158 } else if (shmem_acct_block(info->flags)) {
1159 spin_unlock(&info->lock);
1160 error = -ENOSPC;
1161 goto failed;
1162 }
1163
1164 if (!filepage) {
1165 spin_unlock(&info->lock);
1166 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1167 info,
1168 idx);
1169 if (!filepage) {
1170 shmem_unacct_blocks(info->flags, 1);
1171 shmem_free_blocks(inode, 1);
1172 error = -ENOMEM;
1173 goto failed;
1174 }
1175
1176 spin_lock(&info->lock);
1177 entry = shmem_swp_alloc(info, idx, sgp);
1178 if (IS_ERR(entry))
1179 error = PTR_ERR(entry);
1180 else {
1181 swap = *entry;
1182 shmem_swp_unmap(entry);
1183 }
1184 if (error || swap.val || 0 != add_to_page_cache_lru(
1185 filepage, mapping, idx, GFP_ATOMIC)) {
1186 spin_unlock(&info->lock);
1187 page_cache_release(filepage);
1188 shmem_unacct_blocks(info->flags, 1);
1189 shmem_free_blocks(inode, 1);
1190 filepage = NULL;
1191 if (error)
1192 goto failed;
1193 goto repeat;
1194 }
1195 info->flags |= SHMEM_PAGEIN;
1196 }
1197
1198 info->alloced++;
1199 spin_unlock(&info->lock);
1200 flush_dcache_page(filepage);
1201 SetPageUptodate(filepage);
1202 }
1203 done:
1204 if (*pagep != filepage) {
1205 unlock_page(filepage);
1206 *pagep = filepage;
1207 }
1208 return 0;
1209
1210 failed:
1211 if (*pagep != filepage) {
1212 unlock_page(filepage);
1213 page_cache_release(filepage);
1214 }
1215 return error;
1216 }
1217
1218 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1219 {
1220 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1221 struct page *page = NULL;
1222 unsigned long idx;
1223 int error;
1224
1225 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1226 idx += vma->vm_pgoff;
1227 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1228 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1229 return NOPAGE_SIGBUS;
1230
1231 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1232 if (error)
1233 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1234
1235 mark_page_accessed(page);
1236 return page;
1237 }
1238
1239 static int shmem_populate(struct vm_area_struct *vma,
1240 unsigned long addr, unsigned long len,
1241 pgprot_t prot, unsigned long pgoff, int nonblock)
1242 {
1243 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1244 struct mm_struct *mm = vma->vm_mm;
1245 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1246 unsigned long size;
1247
1248 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1249 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1250 return -EINVAL;
1251
1252 while ((long) len > 0) {
1253 struct page *page = NULL;
1254 int err;
1255 /*
1256 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1257 */
1258 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1259 if (err)
1260 return err;
1261 /* Page may still be null, but only if nonblock was set. */
1262 if (page) {
1263 mark_page_accessed(page);
1264 err = install_page(mm, vma, addr, page, prot);
1265 if (err) {
1266 page_cache_release(page);
1267 return err;
1268 }
1269 } else if (vma->vm_flags & VM_NONLINEAR) {
1270 /* No page was found just because we can't read it in
1271 * now (being here implies nonblock != 0), but the page
1272 * may exist, so set the PTE to fault it in later. */
1273 err = install_file_pte(mm, vma, addr, pgoff, prot);
1274 if (err)
1275 return err;
1276 }
1277
1278 len -= PAGE_SIZE;
1279 addr += PAGE_SIZE;
1280 pgoff++;
1281 }
1282 return 0;
1283 }
1284
1285 #ifdef CONFIG_NUMA
1286 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1287 {
1288 struct inode *i = vma->vm_file->f_dentry->d_inode;
1289 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1290 }
1291
1292 struct mempolicy *
1293 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1294 {
1295 struct inode *i = vma->vm_file->f_dentry->d_inode;
1296 unsigned long idx;
1297
1298 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1299 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1300 }
1301 #endif
1302
1303 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1304 {
1305 struct inode *inode = file->f_dentry->d_inode;
1306 struct shmem_inode_info *info = SHMEM_I(inode);
1307 int retval = -ENOMEM;
1308
1309 spin_lock(&info->lock);
1310 if (lock && !(info->flags & VM_LOCKED)) {
1311 if (!user_shm_lock(inode->i_size, user))
1312 goto out_nomem;
1313 info->flags |= VM_LOCKED;
1314 }
1315 if (!lock && (info->flags & VM_LOCKED) && user) {
1316 user_shm_unlock(inode->i_size, user);
1317 info->flags &= ~VM_LOCKED;
1318 }
1319 retval = 0;
1320 out_nomem:
1321 spin_unlock(&info->lock);
1322 return retval;
1323 }
1324
1325 int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1326 {
1327 file_accessed(file);
1328 vma->vm_ops = &shmem_vm_ops;
1329 return 0;
1330 }
1331
1332 static struct inode *
1333 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1334 {
1335 struct inode *inode;
1336 struct shmem_inode_info *info;
1337 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1338
1339 if (sbinfo->max_inodes) {
1340 spin_lock(&sbinfo->stat_lock);
1341 if (!sbinfo->free_inodes) {
1342 spin_unlock(&sbinfo->stat_lock);
1343 return NULL;
1344 }
1345 sbinfo->free_inodes--;
1346 spin_unlock(&sbinfo->stat_lock);
1347 }
1348
1349 inode = new_inode(sb);
1350 if (inode) {
1351 inode->i_mode = mode;
1352 inode->i_uid = current->fsuid;
1353 inode->i_gid = current->fsgid;
1354 inode->i_blocks = 0;
1355 inode->i_mapping->a_ops = &shmem_aops;
1356 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1357 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1358 info = SHMEM_I(inode);
1359 memset(info, 0, (char *)inode - (char *)info);
1360 spin_lock_init(&info->lock);
1361 INIT_LIST_HEAD(&info->swaplist);
1362
1363 switch (mode & S_IFMT) {
1364 default:
1365 init_special_inode(inode, mode, dev);
1366 break;
1367 case S_IFREG:
1368 inode->i_op = &shmem_inode_operations;
1369 inode->i_fop = &shmem_file_operations;
1370 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1371 &sbinfo->policy_nodes);
1372 break;
1373 case S_IFDIR:
1374 inode->i_nlink++;
1375 /* Some things misbehave if size == 0 on a directory */
1376 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1377 inode->i_op = &shmem_dir_inode_operations;
1378 inode->i_fop = &simple_dir_operations;
1379 break;
1380 case S_IFLNK:
1381 /*
1382 * Must not load anything in the rbtree,
1383 * mpol_free_shared_policy will not be called.
1384 */
1385 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1386 NULL);
1387 break;
1388 }
1389 } else if (sbinfo->max_inodes) {
1390 spin_lock(&sbinfo->stat_lock);
1391 sbinfo->free_inodes++;
1392 spin_unlock(&sbinfo->stat_lock);
1393 }
1394 return inode;
1395 }
1396
1397 #ifdef CONFIG_TMPFS
1398 static struct inode_operations shmem_symlink_inode_operations;
1399 static struct inode_operations shmem_symlink_inline_operations;
1400
1401 /*
1402 * Normally tmpfs makes no use of shmem_prepare_write, but it
1403 * lets a tmpfs file be used read-write below the loop driver.
1404 */
1405 static int
1406 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1407 {
1408 struct inode *inode = page->mapping->host;
1409 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1410 }
1411
1412 static ssize_t
1413 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1414 {
1415 struct inode *inode = file->f_dentry->d_inode;
1416 loff_t pos;
1417 unsigned long written;
1418 ssize_t err;
1419
1420 if ((ssize_t) count < 0)
1421 return -EINVAL;
1422
1423 if (!access_ok(VERIFY_READ, buf, count))
1424 return -EFAULT;
1425
1426 mutex_lock(&inode->i_mutex);
1427
1428 pos = *ppos;
1429 written = 0;
1430
1431 err = generic_write_checks(file, &pos, &count, 0);
1432 if (err || !count)
1433 goto out;
1434
1435 err = remove_suid(file->f_dentry);
1436 if (err)
1437 goto out;
1438
1439 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1440
1441 do {
1442 struct page *page = NULL;
1443 unsigned long bytes, index, offset;
1444 char *kaddr;
1445 int left;
1446
1447 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1448 index = pos >> PAGE_CACHE_SHIFT;
1449 bytes = PAGE_CACHE_SIZE - offset;
1450 if (bytes > count)
1451 bytes = count;
1452
1453 /*
1454 * We don't hold page lock across copy from user -
1455 * what would it guard against? - so no deadlock here.
1456 * But it still may be a good idea to prefault below.
1457 */
1458
1459 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1460 if (err)
1461 break;
1462
1463 left = bytes;
1464 if (PageHighMem(page)) {
1465 volatile unsigned char dummy;
1466 __get_user(dummy, buf);
1467 __get_user(dummy, buf + bytes - 1);
1468
1469 kaddr = kmap_atomic(page, KM_USER0);
1470 left = __copy_from_user_inatomic(kaddr + offset,
1471 buf, bytes);
1472 kunmap_atomic(kaddr, KM_USER0);
1473 }
1474 if (left) {
1475 kaddr = kmap(page);
1476 left = __copy_from_user(kaddr + offset, buf, bytes);
1477 kunmap(page);
1478 }
1479
1480 written += bytes;
1481 count -= bytes;
1482 pos += bytes;
1483 buf += bytes;
1484 if (pos > inode->i_size)
1485 i_size_write(inode, pos);
1486
1487 flush_dcache_page(page);
1488 set_page_dirty(page);
1489 mark_page_accessed(page);
1490 page_cache_release(page);
1491
1492 if (left) {
1493 pos -= left;
1494 written -= left;
1495 err = -EFAULT;
1496 break;
1497 }
1498
1499 /*
1500 * Our dirty pages are not counted in nr_dirty,
1501 * and we do not attempt to balance dirty pages.
1502 */
1503
1504 cond_resched();
1505 } while (count);
1506
1507 *ppos = pos;
1508 if (written)
1509 err = written;
1510 out:
1511 mutex_unlock(&inode->i_mutex);
1512 return err;
1513 }
1514
1515 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1516 {
1517 struct inode *inode = filp->f_dentry->d_inode;
1518 struct address_space *mapping = inode->i_mapping;
1519 unsigned long index, offset;
1520
1521 index = *ppos >> PAGE_CACHE_SHIFT;
1522 offset = *ppos & ~PAGE_CACHE_MASK;
1523
1524 for (;;) {
1525 struct page *page = NULL;
1526 unsigned long end_index, nr, ret;
1527 loff_t i_size = i_size_read(inode);
1528
1529 end_index = i_size >> PAGE_CACHE_SHIFT;
1530 if (index > end_index)
1531 break;
1532 if (index == end_index) {
1533 nr = i_size & ~PAGE_CACHE_MASK;
1534 if (nr <= offset)
1535 break;
1536 }
1537
1538 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1539 if (desc->error) {
1540 if (desc->error == -EINVAL)
1541 desc->error = 0;
1542 break;
1543 }
1544
1545 /*
1546 * We must evaluate after, since reads (unlike writes)
1547 * are called without i_mutex protection against truncate
1548 */
1549 nr = PAGE_CACHE_SIZE;
1550 i_size = i_size_read(inode);
1551 end_index = i_size >> PAGE_CACHE_SHIFT;
1552 if (index == end_index) {
1553 nr = i_size & ~PAGE_CACHE_MASK;
1554 if (nr <= offset) {
1555 if (page)
1556 page_cache_release(page);
1557 break;
1558 }
1559 }
1560 nr -= offset;
1561
1562 if (page) {
1563 /*
1564 * If users can be writing to this page using arbitrary
1565 * virtual addresses, take care about potential aliasing
1566 * before reading the page on the kernel side.
1567 */
1568 if (mapping_writably_mapped(mapping))
1569 flush_dcache_page(page);
1570 /*
1571 * Mark the page accessed if we read the beginning.
1572 */
1573 if (!offset)
1574 mark_page_accessed(page);
1575 } else {
1576 page = ZERO_PAGE(0);
1577 page_cache_get(page);
1578 }
1579
1580 /*
1581 * Ok, we have the page, and it's up-to-date, so
1582 * now we can copy it to user space...
1583 *
1584 * The actor routine returns how many bytes were actually used..
1585 * NOTE! This may not be the same as how much of a user buffer
1586 * we filled up (we may be padding etc), so we can only update
1587 * "pos" here (the actor routine has to update the user buffer
1588 * pointers and the remaining count).
1589 */
1590 ret = actor(desc, page, offset, nr);
1591 offset += ret;
1592 index += offset >> PAGE_CACHE_SHIFT;
1593 offset &= ~PAGE_CACHE_MASK;
1594
1595 page_cache_release(page);
1596 if (ret != nr || !desc->count)
1597 break;
1598
1599 cond_resched();
1600 }
1601
1602 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1603 file_accessed(filp);
1604 }
1605
1606 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1607 {
1608 read_descriptor_t desc;
1609
1610 if ((ssize_t) count < 0)
1611 return -EINVAL;
1612 if (!access_ok(VERIFY_WRITE, buf, count))
1613 return -EFAULT;
1614 if (!count)
1615 return 0;
1616
1617 desc.written = 0;
1618 desc.count = count;
1619 desc.arg.buf = buf;
1620 desc.error = 0;
1621
1622 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1623 if (desc.written)
1624 return desc.written;
1625 return desc.error;
1626 }
1627
1628 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1629 size_t count, read_actor_t actor, void *target)
1630 {
1631 read_descriptor_t desc;
1632
1633 if (!count)
1634 return 0;
1635
1636 desc.written = 0;
1637 desc.count = count;
1638 desc.arg.data = target;
1639 desc.error = 0;
1640
1641 do_shmem_file_read(in_file, ppos, &desc, actor);
1642 if (desc.written)
1643 return desc.written;
1644 return desc.error;
1645 }
1646
1647 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1648 {
1649 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1650
1651 buf->f_type = TMPFS_MAGIC;
1652 buf->f_bsize = PAGE_CACHE_SIZE;
1653 buf->f_namelen = NAME_MAX;
1654 spin_lock(&sbinfo->stat_lock);
1655 if (sbinfo->max_blocks) {
1656 buf->f_blocks = sbinfo->max_blocks;
1657 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1658 }
1659 if (sbinfo->max_inodes) {
1660 buf->f_files = sbinfo->max_inodes;
1661 buf->f_ffree = sbinfo->free_inodes;
1662 }
1663 /* else leave those fields 0 like simple_statfs */
1664 spin_unlock(&sbinfo->stat_lock);
1665 return 0;
1666 }
1667
1668 /*
1669 * File creation. Allocate an inode, and we're done..
1670 */
1671 static int
1672 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1673 {
1674 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1675 int error = -ENOSPC;
1676
1677 if (inode) {
1678 error = security_inode_init_security(inode, dir, NULL, NULL,
1679 NULL);
1680 if (error) {
1681 if (error != -EOPNOTSUPP) {
1682 iput(inode);
1683 return error;
1684 }
1685 error = 0;
1686 }
1687 if (dir->i_mode & S_ISGID) {
1688 inode->i_gid = dir->i_gid;
1689 if (S_ISDIR(mode))
1690 inode->i_mode |= S_ISGID;
1691 }
1692 dir->i_size += BOGO_DIRENT_SIZE;
1693 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1694 d_instantiate(dentry, inode);
1695 dget(dentry); /* Extra count - pin the dentry in core */
1696 }
1697 return error;
1698 }
1699
1700 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1701 {
1702 int error;
1703
1704 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1705 return error;
1706 dir->i_nlink++;
1707 return 0;
1708 }
1709
1710 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1711 struct nameidata *nd)
1712 {
1713 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1714 }
1715
1716 /*
1717 * Link a file..
1718 */
1719 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1720 {
1721 struct inode *inode = old_dentry->d_inode;
1722 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1723
1724 /*
1725 * No ordinary (disk based) filesystem counts links as inodes;
1726 * but each new link needs a new dentry, pinning lowmem, and
1727 * tmpfs dentries cannot be pruned until they are unlinked.
1728 */
1729 if (sbinfo->max_inodes) {
1730 spin_lock(&sbinfo->stat_lock);
1731 if (!sbinfo->free_inodes) {
1732 spin_unlock(&sbinfo->stat_lock);
1733 return -ENOSPC;
1734 }
1735 sbinfo->free_inodes--;
1736 spin_unlock(&sbinfo->stat_lock);
1737 }
1738
1739 dir->i_size += BOGO_DIRENT_SIZE;
1740 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1741 inode->i_nlink++;
1742 atomic_inc(&inode->i_count); /* New dentry reference */
1743 dget(dentry); /* Extra pinning count for the created dentry */
1744 d_instantiate(dentry, inode);
1745 return 0;
1746 }
1747
1748 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1749 {
1750 struct inode *inode = dentry->d_inode;
1751
1752 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1753 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1754 if (sbinfo->max_inodes) {
1755 spin_lock(&sbinfo->stat_lock);
1756 sbinfo->free_inodes++;
1757 spin_unlock(&sbinfo->stat_lock);
1758 }
1759 }
1760
1761 dir->i_size -= BOGO_DIRENT_SIZE;
1762 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1763 inode->i_nlink--;
1764 dput(dentry); /* Undo the count from "create" - this does all the work */
1765 return 0;
1766 }
1767
1768 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1769 {
1770 if (!simple_empty(dentry))
1771 return -ENOTEMPTY;
1772
1773 dentry->d_inode->i_nlink--;
1774 dir->i_nlink--;
1775 return shmem_unlink(dir, dentry);
1776 }
1777
1778 /*
1779 * The VFS layer already does all the dentry stuff for rename,
1780 * we just have to decrement the usage count for the target if
1781 * it exists so that the VFS layer correctly free's it when it
1782 * gets overwritten.
1783 */
1784 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1785 {
1786 struct inode *inode = old_dentry->d_inode;
1787 int they_are_dirs = S_ISDIR(inode->i_mode);
1788
1789 if (!simple_empty(new_dentry))
1790 return -ENOTEMPTY;
1791
1792 if (new_dentry->d_inode) {
1793 (void) shmem_unlink(new_dir, new_dentry);
1794 if (they_are_dirs)
1795 old_dir->i_nlink--;
1796 } else if (they_are_dirs) {
1797 old_dir->i_nlink--;
1798 new_dir->i_nlink++;
1799 }
1800
1801 old_dir->i_size -= BOGO_DIRENT_SIZE;
1802 new_dir->i_size += BOGO_DIRENT_SIZE;
1803 old_dir->i_ctime = old_dir->i_mtime =
1804 new_dir->i_ctime = new_dir->i_mtime =
1805 inode->i_ctime = CURRENT_TIME;
1806 return 0;
1807 }
1808
1809 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1810 {
1811 int error;
1812 int len;
1813 struct inode *inode;
1814 struct page *page = NULL;
1815 char *kaddr;
1816 struct shmem_inode_info *info;
1817
1818 len = strlen(symname) + 1;
1819 if (len > PAGE_CACHE_SIZE)
1820 return -ENAMETOOLONG;
1821
1822 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1823 if (!inode)
1824 return -ENOSPC;
1825
1826 error = security_inode_init_security(inode, dir, NULL, NULL,
1827 NULL);
1828 if (error) {
1829 if (error != -EOPNOTSUPP) {
1830 iput(inode);
1831 return error;
1832 }
1833 error = 0;
1834 }
1835
1836 info = SHMEM_I(inode);
1837 inode->i_size = len-1;
1838 if (len <= (char *)inode - (char *)info) {
1839 /* do it inline */
1840 memcpy(info, symname, len);
1841 inode->i_op = &shmem_symlink_inline_operations;
1842 } else {
1843 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1844 if (error) {
1845 iput(inode);
1846 return error;
1847 }
1848 inode->i_op = &shmem_symlink_inode_operations;
1849 kaddr = kmap_atomic(page, KM_USER0);
1850 memcpy(kaddr, symname, len);
1851 kunmap_atomic(kaddr, KM_USER0);
1852 set_page_dirty(page);
1853 page_cache_release(page);
1854 }
1855 if (dir->i_mode & S_ISGID)
1856 inode->i_gid = dir->i_gid;
1857 dir->i_size += BOGO_DIRENT_SIZE;
1858 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1859 d_instantiate(dentry, inode);
1860 dget(dentry);
1861 return 0;
1862 }
1863
1864 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1865 {
1866 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1867 return NULL;
1868 }
1869
1870 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1871 {
1872 struct page *page = NULL;
1873 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1874 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1875 return page;
1876 }
1877
1878 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1879 {
1880 if (!IS_ERR(nd_get_link(nd))) {
1881 struct page *page = cookie;
1882 kunmap(page);
1883 mark_page_accessed(page);
1884 page_cache_release(page);
1885 }
1886 }
1887
1888 static struct inode_operations shmem_symlink_inline_operations = {
1889 .readlink = generic_readlink,
1890 .follow_link = shmem_follow_link_inline,
1891 };
1892
1893 static struct inode_operations shmem_symlink_inode_operations = {
1894 .truncate = shmem_truncate,
1895 .readlink = generic_readlink,
1896 .follow_link = shmem_follow_link,
1897 .put_link = shmem_put_link,
1898 };
1899
1900 static int shmem_parse_options(char *options, int *mode, uid_t *uid,
1901 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
1902 int *policy, nodemask_t *policy_nodes)
1903 {
1904 char *this_char, *value, *rest;
1905
1906 while (options != NULL) {
1907 this_char = options;
1908 for (;;) {
1909 /*
1910 * NUL-terminate this option: unfortunately,
1911 * mount options form a comma-separated list,
1912 * but mpol's nodelist may also contain commas.
1913 */
1914 options = strchr(options, ',');
1915 if (options == NULL)
1916 break;
1917 options++;
1918 if (!isdigit(*options)) {
1919 options[-1] = '\0';
1920 break;
1921 }
1922 }
1923 if (!*this_char)
1924 continue;
1925 if ((value = strchr(this_char,'=')) != NULL) {
1926 *value++ = 0;
1927 } else {
1928 printk(KERN_ERR
1929 "tmpfs: No value for mount option '%s'\n",
1930 this_char);
1931 return 1;
1932 }
1933
1934 if (!strcmp(this_char,"size")) {
1935 unsigned long long size;
1936 size = memparse(value,&rest);
1937 if (*rest == '%') {
1938 size <<= PAGE_SHIFT;
1939 size *= totalram_pages;
1940 do_div(size, 100);
1941 rest++;
1942 }
1943 if (*rest)
1944 goto bad_val;
1945 *blocks = size >> PAGE_CACHE_SHIFT;
1946 } else if (!strcmp(this_char,"nr_blocks")) {
1947 *blocks = memparse(value,&rest);
1948 if (*rest)
1949 goto bad_val;
1950 } else if (!strcmp(this_char,"nr_inodes")) {
1951 *inodes = memparse(value,&rest);
1952 if (*rest)
1953 goto bad_val;
1954 } else if (!strcmp(this_char,"mode")) {
1955 if (!mode)
1956 continue;
1957 *mode = simple_strtoul(value,&rest,8);
1958 if (*rest)
1959 goto bad_val;
1960 } else if (!strcmp(this_char,"uid")) {
1961 if (!uid)
1962 continue;
1963 *uid = simple_strtoul(value,&rest,0);
1964 if (*rest)
1965 goto bad_val;
1966 } else if (!strcmp(this_char,"gid")) {
1967 if (!gid)
1968 continue;
1969 *gid = simple_strtoul(value,&rest,0);
1970 if (*rest)
1971 goto bad_val;
1972 } else if (!strcmp(this_char,"mpol")) {
1973 if (shmem_parse_mpol(value,policy,policy_nodes))
1974 goto bad_val;
1975 } else {
1976 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1977 this_char);
1978 return 1;
1979 }
1980 }
1981 return 0;
1982
1983 bad_val:
1984 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1985 value, this_char);
1986 return 1;
1987
1988 }
1989
1990 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1991 {
1992 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1993 unsigned long max_blocks = sbinfo->max_blocks;
1994 unsigned long max_inodes = sbinfo->max_inodes;
1995 int policy = sbinfo->policy;
1996 nodemask_t policy_nodes = sbinfo->policy_nodes;
1997 unsigned long blocks;
1998 unsigned long inodes;
1999 int error = -EINVAL;
2000
2001 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2002 &max_inodes, &policy, &policy_nodes))
2003 return error;
2004
2005 spin_lock(&sbinfo->stat_lock);
2006 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2007 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2008 if (max_blocks < blocks)
2009 goto out;
2010 if (max_inodes < inodes)
2011 goto out;
2012 /*
2013 * Those tests also disallow limited->unlimited while any are in
2014 * use, so i_blocks will always be zero when max_blocks is zero;
2015 * but we must separately disallow unlimited->limited, because
2016 * in that case we have no record of how much is already in use.
2017 */
2018 if (max_blocks && !sbinfo->max_blocks)
2019 goto out;
2020 if (max_inodes && !sbinfo->max_inodes)
2021 goto out;
2022
2023 error = 0;
2024 sbinfo->max_blocks = max_blocks;
2025 sbinfo->free_blocks = max_blocks - blocks;
2026 sbinfo->max_inodes = max_inodes;
2027 sbinfo->free_inodes = max_inodes - inodes;
2028 sbinfo->policy = policy;
2029 sbinfo->policy_nodes = policy_nodes;
2030 out:
2031 spin_unlock(&sbinfo->stat_lock);
2032 return error;
2033 }
2034 #endif
2035
2036 static void shmem_put_super(struct super_block *sb)
2037 {
2038 kfree(sb->s_fs_info);
2039 sb->s_fs_info = NULL;
2040 }
2041
2042 static int shmem_fill_super(struct super_block *sb,
2043 void *data, int silent)
2044 {
2045 struct inode *inode;
2046 struct dentry *root;
2047 int mode = S_IRWXUGO | S_ISVTX;
2048 uid_t uid = current->fsuid;
2049 gid_t gid = current->fsgid;
2050 int err = -ENOMEM;
2051 struct shmem_sb_info *sbinfo;
2052 unsigned long blocks = 0;
2053 unsigned long inodes = 0;
2054 int policy = MPOL_DEFAULT;
2055 nodemask_t policy_nodes = node_online_map;
2056
2057 #ifdef CONFIG_TMPFS
2058 /*
2059 * Per default we only allow half of the physical ram per
2060 * tmpfs instance, limiting inodes to one per page of lowmem;
2061 * but the internal instance is left unlimited.
2062 */
2063 if (!(sb->s_flags & MS_NOUSER)) {
2064 blocks = totalram_pages / 2;
2065 inodes = totalram_pages - totalhigh_pages;
2066 if (inodes > blocks)
2067 inodes = blocks;
2068 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2069 &inodes, &policy, &policy_nodes))
2070 return -EINVAL;
2071 }
2072 #else
2073 sb->s_flags |= MS_NOUSER;
2074 #endif
2075
2076 /* Round up to L1_CACHE_BYTES to resist false sharing */
2077 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2078 L1_CACHE_BYTES), GFP_KERNEL);
2079 if (!sbinfo)
2080 return -ENOMEM;
2081
2082 spin_lock_init(&sbinfo->stat_lock);
2083 sbinfo->max_blocks = blocks;
2084 sbinfo->free_blocks = blocks;
2085 sbinfo->max_inodes = inodes;
2086 sbinfo->free_inodes = inodes;
2087 sbinfo->policy = policy;
2088 sbinfo->policy_nodes = policy_nodes;
2089
2090 sb->s_fs_info = sbinfo;
2091 sb->s_maxbytes = SHMEM_MAX_BYTES;
2092 sb->s_blocksize = PAGE_CACHE_SIZE;
2093 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2094 sb->s_magic = TMPFS_MAGIC;
2095 sb->s_op = &shmem_ops;
2096 sb->s_time_gran = 1;
2097
2098 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2099 if (!inode)
2100 goto failed;
2101 inode->i_uid = uid;
2102 inode->i_gid = gid;
2103 root = d_alloc_root(inode);
2104 if (!root)
2105 goto failed_iput;
2106 sb->s_root = root;
2107 return 0;
2108
2109 failed_iput:
2110 iput(inode);
2111 failed:
2112 shmem_put_super(sb);
2113 return err;
2114 }
2115
2116 static struct kmem_cache *shmem_inode_cachep;
2117
2118 static struct inode *shmem_alloc_inode(struct super_block *sb)
2119 {
2120 struct shmem_inode_info *p;
2121 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2122 if (!p)
2123 return NULL;
2124 return &p->vfs_inode;
2125 }
2126
2127 static void shmem_destroy_inode(struct inode *inode)
2128 {
2129 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2130 /* only struct inode is valid if it's an inline symlink */
2131 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2132 }
2133 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2134 }
2135
2136 static void init_once(void *foo, struct kmem_cache *cachep,
2137 unsigned long flags)
2138 {
2139 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2140
2141 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2142 SLAB_CTOR_CONSTRUCTOR) {
2143 inode_init_once(&p->vfs_inode);
2144 }
2145 }
2146
2147 static int init_inodecache(void)
2148 {
2149 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2150 sizeof(struct shmem_inode_info),
2151 0, 0, init_once, NULL);
2152 if (shmem_inode_cachep == NULL)
2153 return -ENOMEM;
2154 return 0;
2155 }
2156
2157 static void destroy_inodecache(void)
2158 {
2159 kmem_cache_destroy(shmem_inode_cachep);
2160 }
2161
2162 static const struct address_space_operations shmem_aops = {
2163 .writepage = shmem_writepage,
2164 .set_page_dirty = __set_page_dirty_nobuffers,
2165 #ifdef CONFIG_TMPFS
2166 .prepare_write = shmem_prepare_write,
2167 .commit_write = simple_commit_write,
2168 #endif
2169 .migratepage = migrate_page,
2170 };
2171
2172 static struct file_operations shmem_file_operations = {
2173 .mmap = shmem_mmap,
2174 #ifdef CONFIG_TMPFS
2175 .llseek = generic_file_llseek,
2176 .read = shmem_file_read,
2177 .write = shmem_file_write,
2178 .fsync = simple_sync_file,
2179 .sendfile = shmem_file_sendfile,
2180 #endif
2181 };
2182
2183 static struct inode_operations shmem_inode_operations = {
2184 .truncate = shmem_truncate,
2185 .setattr = shmem_notify_change,
2186 .truncate_range = shmem_truncate_range,
2187 };
2188
2189 static struct inode_operations shmem_dir_inode_operations = {
2190 #ifdef CONFIG_TMPFS
2191 .create = shmem_create,
2192 .lookup = simple_lookup,
2193 .link = shmem_link,
2194 .unlink = shmem_unlink,
2195 .symlink = shmem_symlink,
2196 .mkdir = shmem_mkdir,
2197 .rmdir = shmem_rmdir,
2198 .mknod = shmem_mknod,
2199 .rename = shmem_rename,
2200 #endif
2201 };
2202
2203 static struct super_operations shmem_ops = {
2204 .alloc_inode = shmem_alloc_inode,
2205 .destroy_inode = shmem_destroy_inode,
2206 #ifdef CONFIG_TMPFS
2207 .statfs = shmem_statfs,
2208 .remount_fs = shmem_remount_fs,
2209 #endif
2210 .delete_inode = shmem_delete_inode,
2211 .drop_inode = generic_delete_inode,
2212 .put_super = shmem_put_super,
2213 };
2214
2215 static struct vm_operations_struct shmem_vm_ops = {
2216 .nopage = shmem_nopage,
2217 .populate = shmem_populate,
2218 #ifdef CONFIG_NUMA
2219 .set_policy = shmem_set_policy,
2220 .get_policy = shmem_get_policy,
2221 #endif
2222 };
2223
2224
2225 static int shmem_get_sb(struct file_system_type *fs_type,
2226 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
2227 {
2228 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
2229 }
2230
2231 static struct file_system_type tmpfs_fs_type = {
2232 .owner = THIS_MODULE,
2233 .name = "tmpfs",
2234 .get_sb = shmem_get_sb,
2235 .kill_sb = kill_litter_super,
2236 };
2237 static struct vfsmount *shm_mnt;
2238
2239 static int __init init_tmpfs(void)
2240 {
2241 int error;
2242
2243 error = init_inodecache();
2244 if (error)
2245 goto out3;
2246
2247 error = register_filesystem(&tmpfs_fs_type);
2248 if (error) {
2249 printk(KERN_ERR "Could not register tmpfs\n");
2250 goto out2;
2251 }
2252
2253 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
2254 tmpfs_fs_type.name, NULL);
2255 if (IS_ERR(shm_mnt)) {
2256 error = PTR_ERR(shm_mnt);
2257 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2258 goto out1;
2259 }
2260 return 0;
2261
2262 out1:
2263 unregister_filesystem(&tmpfs_fs_type);
2264 out2:
2265 destroy_inodecache();
2266 out3:
2267 shm_mnt = ERR_PTR(error);
2268 return error;
2269 }
2270 module_init(init_tmpfs)
2271
2272 /*
2273 * shmem_file_setup - get an unlinked file living in tmpfs
2274 *
2275 * @name: name for dentry (to be seen in /proc/<pid>/maps
2276 * @size: size to be set for the file
2277 *
2278 */
2279 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2280 {
2281 int error;
2282 struct file *file;
2283 struct inode *inode;
2284 struct dentry *dentry, *root;
2285 struct qstr this;
2286
2287 if (IS_ERR(shm_mnt))
2288 return (void *)shm_mnt;
2289
2290 if (size < 0 || size > SHMEM_MAX_BYTES)
2291 return ERR_PTR(-EINVAL);
2292
2293 if (shmem_acct_size(flags, size))
2294 return ERR_PTR(-ENOMEM);
2295
2296 error = -ENOMEM;
2297 this.name = name;
2298 this.len = strlen(name);
2299 this.hash = 0; /* will go */
2300 root = shm_mnt->mnt_root;
2301 dentry = d_alloc(root, &this);
2302 if (!dentry)
2303 goto put_memory;
2304
2305 error = -ENFILE;
2306 file = get_empty_filp();
2307 if (!file)
2308 goto put_dentry;
2309
2310 error = -ENOSPC;
2311 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2312 if (!inode)
2313 goto close_file;
2314
2315 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2316 d_instantiate(dentry, inode);
2317 inode->i_size = size;
2318 inode->i_nlink = 0; /* It is unlinked */
2319 file->f_vfsmnt = mntget(shm_mnt);
2320 file->f_dentry = dentry;
2321 file->f_mapping = inode->i_mapping;
2322 file->f_op = &shmem_file_operations;
2323 file->f_mode = FMODE_WRITE | FMODE_READ;
2324 return file;
2325
2326 close_file:
2327 put_filp(file);
2328 put_dentry:
2329 dput(dentry);
2330 put_memory:
2331 shmem_unacct_size(flags, size);
2332 return ERR_PTR(error);
2333 }
2334
2335 /*
2336 * shmem_zero_setup - setup a shared anonymous mapping
2337 *
2338 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2339 */
2340 int shmem_zero_setup(struct vm_area_struct *vma)
2341 {
2342 struct file *file;
2343 loff_t size = vma->vm_end - vma->vm_start;
2344
2345 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2346 if (IS_ERR(file))
2347 return PTR_ERR(file);
2348
2349 if (vma->vm_file)
2350 fput(vma->vm_file);
2351 vma->vm_file = file;
2352 vma->vm_ops = &shmem_vm_ops;
2353 return 0;
2354 }
linux v2.6.22.y-op