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[PATCH] sis900: remove cfgpmcsr I/O space register define
[linux-2.6/mini2440.git] / mm / shmem.c
blobf7ac7b812f926a24b3ba71bb4757318ab75b357b
1 /*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
12 *
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16 *
17 * This file is released under the GPL.
18 */
19
20 /*
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
24 */
25
26 #include <linux/config.h>
27 #include <linux/module.h>
28 #include <linux/init.h>
29 #include <linux/devfs_fs_kernel.h>
30 #include <linux/fs.h>
31 #include <linux/mm.h>
32 #include <linux/mman.h>
33 #include <linux/file.h>
34 #include <linux/swap.h>
35 #include <linux/pagemap.h>
36 #include <linux/string.h>
37 #include <linux/slab.h>
38 #include <linux/backing-dev.h>
39 #include <linux/shmem_fs.h>
40 #include <linux/mount.h>
41 #include <linux/writeback.h>
42 #include <linux/vfs.h>
43 #include <linux/blkdev.h>
44 #include <linux/security.h>
45 #include <linux/swapops.h>
46 #include <linux/mempolicy.h>
47 #include <linux/namei.h>
48 #include <asm/uaccess.h>
49 #include <asm/div64.h>
50 #include <asm/pgtable.h>
51
52 /* This magic number is used in glibc for posix shared memory */
53 #define TMPFS_MAGIC 0x01021994
54
55 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
56 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
57 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
58
59 #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
60 #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
61
62 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
63
64 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
65 #define SHMEM_PAGEIN VM_READ
66 #define SHMEM_TRUNCATE VM_WRITE
67
68 /* Definition to limit shmem_truncate's steps between cond_rescheds */
69 #define LATENCY_LIMIT 64
70
71 /* Pretend that each entry is of this size in directory's i_size */
72 #define BOGO_DIRENT_SIZE 20
73
74 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
75 enum sgp_type {
76 SGP_QUICK, /* don't try more than file page cache lookup */
77 SGP_READ, /* don't exceed i_size, don't allocate page */
78 SGP_CACHE, /* don't exceed i_size, may allocate page */
79 SGP_WRITE, /* may exceed i_size, may allocate page */
80 };
81
82 static int shmem_getpage(struct inode *inode, unsigned long idx,
83 struct page **pagep, enum sgp_type sgp, int *type);
84
85 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
86 {
87 /*
88 * The above definition of ENTRIES_PER_PAGE, and the use of
89 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
90 * might be reconsidered if it ever diverges from PAGE_SIZE.
91 */
92 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
93 }
94
95 static inline void shmem_dir_free(struct page *page)
96 {
97 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
98 }
99
100 static struct page **shmem_dir_map(struct page *page)
101 {
102 return (struct page **)kmap_atomic(page, KM_USER0);
103 }
104
105 static inline void shmem_dir_unmap(struct page **dir)
106 {
107 kunmap_atomic(dir, KM_USER0);
108 }
109
110 static swp_entry_t *shmem_swp_map(struct page *page)
111 {
112 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
113 }
114
115 static inline void shmem_swp_balance_unmap(void)
116 {
117 /*
118 * When passing a pointer to an i_direct entry, to code which
119 * also handles indirect entries and so will shmem_swp_unmap,
120 * we must arrange for the preempt count to remain in balance.
121 * What kmap_atomic of a lowmem page does depends on config
122 * and architecture, so pretend to kmap_atomic some lowmem page.
123 */
124 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
125 }
126
127 static inline void shmem_swp_unmap(swp_entry_t *entry)
128 {
129 kunmap_atomic(entry, KM_USER1);
130 }
131
132 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
133 {
134 return sb->s_fs_info;
135 }
136
137 /*
138 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
139 * for shared memory and for shared anonymous (/dev/zero) mappings
140 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
141 * consistent with the pre-accounting of private mappings ...
142 */
143 static inline int shmem_acct_size(unsigned long flags, loff_t size)
144 {
145 return (flags & VM_ACCOUNT)?
146 security_vm_enough_memory(VM_ACCT(size)): 0;
147 }
148
149 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
150 {
151 if (flags & VM_ACCOUNT)
152 vm_unacct_memory(VM_ACCT(size));
153 }
154
155 /*
156 * ... whereas tmpfs objects are accounted incrementally as
157 * pages are allocated, in order to allow huge sparse files.
158 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
159 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
160 */
161 static inline int shmem_acct_block(unsigned long flags)
162 {
163 return (flags & VM_ACCOUNT)?
164 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
165 }
166
167 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
168 {
169 if (!(flags & VM_ACCOUNT))
170 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
171 }
172
173 static struct super_operations shmem_ops;
174 static struct address_space_operations shmem_aops;
175 static struct file_operations shmem_file_operations;
176 static struct inode_operations shmem_inode_operations;
177 static struct inode_operations shmem_dir_inode_operations;
178 static struct vm_operations_struct shmem_vm_ops;
179
180 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
181 .ra_pages = 0, /* No readahead */
182 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
183 .unplug_io_fn = default_unplug_io_fn,
184 };
185
186 static LIST_HEAD(shmem_swaplist);
187 static DEFINE_SPINLOCK(shmem_swaplist_lock);
188
189 static void shmem_free_blocks(struct inode *inode, long pages)
190 {
191 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
192 if (sbinfo->max_blocks) {
193 spin_lock(&sbinfo->stat_lock);
194 sbinfo->free_blocks += pages;
195 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
196 spin_unlock(&sbinfo->stat_lock);
197 }
198 }
199
200 /*
201 * shmem_recalc_inode - recalculate the size of an inode
202 *
203 * @inode: inode to recalc
204 *
205 * We have to calculate the free blocks since the mm can drop
206 * undirtied hole pages behind our back.
207 *
208 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
209 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
210 *
211 * It has to be called with the spinlock held.
212 */
213 static void shmem_recalc_inode(struct inode *inode)
214 {
215 struct shmem_inode_info *info = SHMEM_I(inode);
216 long freed;
217
218 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
219 if (freed > 0) {
220 info->alloced -= freed;
221 shmem_unacct_blocks(info->flags, freed);
222 shmem_free_blocks(inode, freed);
223 }
224 }
225
226 /*
227 * shmem_swp_entry - find the swap vector position in the info structure
228 *
229 * @info: info structure for the inode
230 * @index: index of the page to find
231 * @page: optional page to add to the structure. Has to be preset to
232 * all zeros
233 *
234 * If there is no space allocated yet it will return NULL when
235 * page is NULL, else it will use the page for the needed block,
236 * setting it to NULL on return to indicate that it has been used.
237 *
238 * The swap vector is organized the following way:
239 *
240 * There are SHMEM_NR_DIRECT entries directly stored in the
241 * shmem_inode_info structure. So small files do not need an addional
242 * allocation.
243 *
244 * For pages with index > SHMEM_NR_DIRECT there is the pointer
245 * i_indirect which points to a page which holds in the first half
246 * doubly indirect blocks, in the second half triple indirect blocks:
247 *
248 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
249 * following layout (for SHMEM_NR_DIRECT == 16):
250 *
251 * i_indirect -> dir --> 16-19
252 * | +-> 20-23
253 * |
254 * +-->dir2 --> 24-27
255 * | +-> 28-31
256 * | +-> 32-35
257 * | +-> 36-39
258 * |
259 * +-->dir3 --> 40-43
260 * +-> 44-47
261 * +-> 48-51
262 * +-> 52-55
263 */
264 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
265 {
266 unsigned long offset;
267 struct page **dir;
268 struct page *subdir;
269
270 if (index < SHMEM_NR_DIRECT) {
271 shmem_swp_balance_unmap();
272 return info->i_direct+index;
273 }
274 if (!info->i_indirect) {
275 if (page) {
276 info->i_indirect = *page;
277 *page = NULL;
278 }
279 return NULL; /* need another page */
280 }
281
282 index -= SHMEM_NR_DIRECT;
283 offset = index % ENTRIES_PER_PAGE;
284 index /= ENTRIES_PER_PAGE;
285 dir = shmem_dir_map(info->i_indirect);
286
287 if (index >= ENTRIES_PER_PAGE/2) {
288 index -= ENTRIES_PER_PAGE/2;
289 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
290 index %= ENTRIES_PER_PAGE;
291 subdir = *dir;
292 if (!subdir) {
293 if (page) {
294 *dir = *page;
295 *page = NULL;
296 }
297 shmem_dir_unmap(dir);
298 return NULL; /* need another page */
299 }
300 shmem_dir_unmap(dir);
301 dir = shmem_dir_map(subdir);
302 }
303
304 dir += index;
305 subdir = *dir;
306 if (!subdir) {
307 if (!page || !(subdir = *page)) {
308 shmem_dir_unmap(dir);
309 return NULL; /* need a page */
310 }
311 *dir = subdir;
312 *page = NULL;
313 }
314 shmem_dir_unmap(dir);
315 return shmem_swp_map(subdir) + offset;
316 }
317
318 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
319 {
320 long incdec = value? 1: -1;
321
322 entry->val = value;
323 info->swapped += incdec;
324 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
325 struct page *page = kmap_atomic_to_page(entry);
326 set_page_private(page, page_private(page) + incdec);
327 }
328 }
329
330 /*
331 * shmem_swp_alloc - get the position of the swap entry for the page.
332 * If it does not exist allocate the entry.
333 *
334 * @info: info structure for the inode
335 * @index: index of the page to find
336 * @sgp: check and recheck i_size? skip allocation?
337 */
338 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
339 {
340 struct inode *inode = &info->vfs_inode;
341 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
342 struct page *page = NULL;
343 swp_entry_t *entry;
344
345 if (sgp != SGP_WRITE &&
346 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
347 return ERR_PTR(-EINVAL);
348
349 while (!(entry = shmem_swp_entry(info, index, &page))) {
350 if (sgp == SGP_READ)
351 return shmem_swp_map(ZERO_PAGE(0));
352 /*
353 * Test free_blocks against 1 not 0, since we have 1 data
354 * page (and perhaps indirect index pages) yet to allocate:
355 * a waste to allocate index if we cannot allocate data.
356 */
357 if (sbinfo->max_blocks) {
358 spin_lock(&sbinfo->stat_lock);
359 if (sbinfo->free_blocks <= 1) {
360 spin_unlock(&sbinfo->stat_lock);
361 return ERR_PTR(-ENOSPC);
362 }
363 sbinfo->free_blocks--;
364 inode->i_blocks += BLOCKS_PER_PAGE;
365 spin_unlock(&sbinfo->stat_lock);
366 }
367
368 spin_unlock(&info->lock);
369 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
370 if (page)
371 set_page_private(page, 0);
372 spin_lock(&info->lock);
373
374 if (!page) {
375 shmem_free_blocks(inode, 1);
376 return ERR_PTR(-ENOMEM);
377 }
378 if (sgp != SGP_WRITE &&
379 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
380 entry = ERR_PTR(-EINVAL);
381 break;
382 }
383 if (info->next_index <= index)
384 info->next_index = index + 1;
385 }
386 if (page) {
387 /* another task gave its page, or truncated the file */
388 shmem_free_blocks(inode, 1);
389 shmem_dir_free(page);
390 }
391 if (info->next_index <= index && !IS_ERR(entry))
392 info->next_index = index + 1;
393 return entry;
394 }
395
396 /*
397 * shmem_free_swp - free some swap entries in a directory
398 *
399 * @dir: pointer to the directory
400 * @edir: pointer after last entry of the directory
401 */
402 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
403 {
404 swp_entry_t *ptr;
405 int freed = 0;
406
407 for (ptr = dir; ptr < edir; ptr++) {
408 if (ptr->val) {
409 free_swap_and_cache(*ptr);
410 *ptr = (swp_entry_t){0};
411 freed++;
412 }
413 }
414 return freed;
415 }
416
417 static int shmem_map_and_free_swp(struct page *subdir,
418 int offset, int limit, struct page ***dir)
419 {
420 swp_entry_t *ptr;
421 int freed = 0;
422
423 ptr = shmem_swp_map(subdir);
424 for (; offset < limit; offset += LATENCY_LIMIT) {
425 int size = limit - offset;
426 if (size > LATENCY_LIMIT)
427 size = LATENCY_LIMIT;
428 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
429 if (need_resched()) {
430 shmem_swp_unmap(ptr);
431 if (*dir) {
432 shmem_dir_unmap(*dir);
433 *dir = NULL;
434 }
435 cond_resched();
436 ptr = shmem_swp_map(subdir);
437 }
438 }
439 shmem_swp_unmap(ptr);
440 return freed;
441 }
442
443 static void shmem_free_pages(struct list_head *next)
444 {
445 struct page *page;
446 int freed = 0;
447
448 do {
449 page = container_of(next, struct page, lru);
450 next = next->next;
451 shmem_dir_free(page);
452 freed++;
453 if (freed >= LATENCY_LIMIT) {
454 cond_resched();
455 freed = 0;
456 }
457 } while (next);
458 }
459
460 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
461 {
462 struct shmem_inode_info *info = SHMEM_I(inode);
463 unsigned long idx;
464 unsigned long size;
465 unsigned long limit;
466 unsigned long stage;
467 unsigned long diroff;
468 struct page **dir;
469 struct page *topdir;
470 struct page *middir;
471 struct page *subdir;
472 swp_entry_t *ptr;
473 LIST_HEAD(pages_to_free);
474 long nr_pages_to_free = 0;
475 long nr_swaps_freed = 0;
476 int offset;
477 int freed;
478 int punch_hole = 0;
479
480 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
481 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
482 if (idx >= info->next_index)
483 return;
484
485 spin_lock(&info->lock);
486 info->flags |= SHMEM_TRUNCATE;
487 if (likely(end == (loff_t) -1)) {
488 limit = info->next_index;
489 info->next_index = idx;
490 } else {
491 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
492 if (limit > info->next_index)
493 limit = info->next_index;
494 punch_hole = 1;
495 }
496
497 topdir = info->i_indirect;
498 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
499 info->i_indirect = NULL;
500 nr_pages_to_free++;
501 list_add(&topdir->lru, &pages_to_free);
502 }
503 spin_unlock(&info->lock);
504
505 if (info->swapped && idx < SHMEM_NR_DIRECT) {
506 ptr = info->i_direct;
507 size = limit;
508 if (size > SHMEM_NR_DIRECT)
509 size = SHMEM_NR_DIRECT;
510 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
511 }
512 if (!topdir)
513 goto done2;
514
515 BUG_ON(limit <= SHMEM_NR_DIRECT);
516 limit -= SHMEM_NR_DIRECT;
517 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
518 offset = idx % ENTRIES_PER_PAGE;
519 idx -= offset;
520
521 dir = shmem_dir_map(topdir);
522 stage = ENTRIES_PER_PAGEPAGE/2;
523 if (idx < ENTRIES_PER_PAGEPAGE/2) {
524 middir = topdir;
525 diroff = idx/ENTRIES_PER_PAGE;
526 } else {
527 dir += ENTRIES_PER_PAGE/2;
528 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
529 while (stage <= idx)
530 stage += ENTRIES_PER_PAGEPAGE;
531 middir = *dir;
532 if (*dir) {
533 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
534 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
535 if (!diroff && !offset) {
536 *dir = NULL;
537 nr_pages_to_free++;
538 list_add(&middir->lru, &pages_to_free);
539 }
540 shmem_dir_unmap(dir);
541 dir = shmem_dir_map(middir);
542 } else {
543 diroff = 0;
544 offset = 0;
545 idx = stage;
546 }
547 }
548
549 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
550 if (unlikely(idx == stage)) {
551 shmem_dir_unmap(dir);
552 dir = shmem_dir_map(topdir) +
553 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
554 while (!*dir) {
555 dir++;
556 idx += ENTRIES_PER_PAGEPAGE;
557 if (idx >= limit)
558 goto done1;
559 }
560 stage = idx + ENTRIES_PER_PAGEPAGE;
561 middir = *dir;
562 *dir = NULL;
563 nr_pages_to_free++;
564 list_add(&middir->lru, &pages_to_free);
565 shmem_dir_unmap(dir);
566 cond_resched();
567 dir = shmem_dir_map(middir);
568 diroff = 0;
569 }
570 subdir = dir[diroff];
571 if (subdir && page_private(subdir)) {
572 size = limit - idx;
573 if (size > ENTRIES_PER_PAGE)
574 size = ENTRIES_PER_PAGE;
575 freed = shmem_map_and_free_swp(subdir,
576 offset, size, &dir);
577 if (!dir)
578 dir = shmem_dir_map(middir);
579 nr_swaps_freed += freed;
580 if (offset)
581 spin_lock(&info->lock);
582 set_page_private(subdir, page_private(subdir) - freed);
583 if (offset)
584 spin_unlock(&info->lock);
585 if (!punch_hole)
586 BUG_ON(page_private(subdir) > offset);
587 }
588 if (offset)
589 offset = 0;
590 else if (subdir && !page_private(subdir)) {
591 dir[diroff] = NULL;
592 nr_pages_to_free++;
593 list_add(&subdir->lru, &pages_to_free);
594 }
595 }
596 done1:
597 shmem_dir_unmap(dir);
598 done2:
599 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
600 /*
601 * Call truncate_inode_pages again: racing shmem_unuse_inode
602 * may have swizzled a page in from swap since vmtruncate or
603 * generic_delete_inode did it, before we lowered next_index.
604 * Also, though shmem_getpage checks i_size before adding to
605 * cache, no recheck after: so fix the narrow window there too.
606 */
607 truncate_inode_pages_range(inode->i_mapping, start, end);
608 }
609
610 spin_lock(&info->lock);
611 info->flags &= ~SHMEM_TRUNCATE;
612 info->swapped -= nr_swaps_freed;
613 if (nr_pages_to_free)
614 shmem_free_blocks(inode, nr_pages_to_free);
615 shmem_recalc_inode(inode);
616 spin_unlock(&info->lock);
617
618 /*
619 * Empty swap vector directory pages to be freed?
620 */
621 if (!list_empty(&pages_to_free)) {
622 pages_to_free.prev->next = NULL;
623 shmem_free_pages(pages_to_free.next);
624 }
625 }
626
627 static void shmem_truncate(struct inode *inode)
628 {
629 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
630 }
631
632 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
633 {
634 struct inode *inode = dentry->d_inode;
635 struct page *page = NULL;
636 int error;
637
638 if (attr->ia_valid & ATTR_SIZE) {
639 if (attr->ia_size < inode->i_size) {
640 /*
641 * If truncating down to a partial page, then
642 * if that page is already allocated, hold it
643 * in memory until the truncation is over, so
644 * truncate_partial_page cannnot miss it were
645 * it assigned to swap.
646 */
647 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
648 (void) shmem_getpage(inode,
649 attr->ia_size>>PAGE_CACHE_SHIFT,
650 &page, SGP_READ, NULL);
651 }
652 /*
653 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
654 * detect if any pages might have been added to cache
655 * after truncate_inode_pages. But we needn't bother
656 * if it's being fully truncated to zero-length: the
657 * nrpages check is efficient enough in that case.
658 */
659 if (attr->ia_size) {
660 struct shmem_inode_info *info = SHMEM_I(inode);
661 spin_lock(&info->lock);
662 info->flags &= ~SHMEM_PAGEIN;
663 spin_unlock(&info->lock);
664 }
665 }
666 }
667
668 error = inode_change_ok(inode, attr);
669 if (!error)
670 error = inode_setattr(inode, attr);
671 if (page)
672 page_cache_release(page);
673 return error;
674 }
675
676 static void shmem_delete_inode(struct inode *inode)
677 {
678 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
679 struct shmem_inode_info *info = SHMEM_I(inode);
680
681 if (inode->i_op->truncate == shmem_truncate) {
682 truncate_inode_pages(inode->i_mapping, 0);
683 shmem_unacct_size(info->flags, inode->i_size);
684 inode->i_size = 0;
685 shmem_truncate(inode);
686 if (!list_empty(&info->swaplist)) {
687 spin_lock(&shmem_swaplist_lock);
688 list_del_init(&info->swaplist);
689 spin_unlock(&shmem_swaplist_lock);
690 }
691 }
692 BUG_ON(inode->i_blocks);
693 if (sbinfo->max_inodes) {
694 spin_lock(&sbinfo->stat_lock);
695 sbinfo->free_inodes++;
696 spin_unlock(&sbinfo->stat_lock);
697 }
698 clear_inode(inode);
699 }
700
701 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
702 {
703 swp_entry_t *ptr;
704
705 for (ptr = dir; ptr < edir; ptr++) {
706 if (ptr->val == entry.val)
707 return ptr - dir;
708 }
709 return -1;
710 }
711
712 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
713 {
714 struct inode *inode;
715 unsigned long idx;
716 unsigned long size;
717 unsigned long limit;
718 unsigned long stage;
719 struct page **dir;
720 struct page *subdir;
721 swp_entry_t *ptr;
722 int offset;
723
724 idx = 0;
725 ptr = info->i_direct;
726 spin_lock(&info->lock);
727 limit = info->next_index;
728 size = limit;
729 if (size > SHMEM_NR_DIRECT)
730 size = SHMEM_NR_DIRECT;
731 offset = shmem_find_swp(entry, ptr, ptr+size);
732 if (offset >= 0) {
733 shmem_swp_balance_unmap();
734 goto found;
735 }
736 if (!info->i_indirect)
737 goto lost2;
738
739 dir = shmem_dir_map(info->i_indirect);
740 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
741
742 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
743 if (unlikely(idx == stage)) {
744 shmem_dir_unmap(dir-1);
745 dir = shmem_dir_map(info->i_indirect) +
746 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
747 while (!*dir) {
748 dir++;
749 idx += ENTRIES_PER_PAGEPAGE;
750 if (idx >= limit)
751 goto lost1;
752 }
753 stage = idx + ENTRIES_PER_PAGEPAGE;
754 subdir = *dir;
755 shmem_dir_unmap(dir);
756 dir = shmem_dir_map(subdir);
757 }
758 subdir = *dir;
759 if (subdir && page_private(subdir)) {
760 ptr = shmem_swp_map(subdir);
761 size = limit - idx;
762 if (size > ENTRIES_PER_PAGE)
763 size = ENTRIES_PER_PAGE;
764 offset = shmem_find_swp(entry, ptr, ptr+size);
765 if (offset >= 0) {
766 shmem_dir_unmap(dir);
767 goto found;
768 }
769 shmem_swp_unmap(ptr);
770 }
771 }
772 lost1:
773 shmem_dir_unmap(dir-1);
774 lost2:
775 spin_unlock(&info->lock);
776 return 0;
777 found:
778 idx += offset;
779 inode = &info->vfs_inode;
780 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
781 info->flags |= SHMEM_PAGEIN;
782 shmem_swp_set(info, ptr + offset, 0);
783 }
784 shmem_swp_unmap(ptr);
785 spin_unlock(&info->lock);
786 /*
787 * Decrement swap count even when the entry is left behind:
788 * try_to_unuse will skip over mms, then reincrement count.
789 */
790 swap_free(entry);
791 return 1;
792 }
793
794 /*
795 * shmem_unuse() search for an eventually swapped out shmem page.
796 */
797 int shmem_unuse(swp_entry_t entry, struct page *page)
798 {
799 struct list_head *p, *next;
800 struct shmem_inode_info *info;
801 int found = 0;
802
803 spin_lock(&shmem_swaplist_lock);
804 list_for_each_safe(p, next, &shmem_swaplist) {
805 info = list_entry(p, struct shmem_inode_info, swaplist);
806 if (!info->swapped)
807 list_del_init(&info->swaplist);
808 else if (shmem_unuse_inode(info, entry, page)) {
809 /* move head to start search for next from here */
810 list_move_tail(&shmem_swaplist, &info->swaplist);
811 found = 1;
812 break;
813 }
814 }
815 spin_unlock(&shmem_swaplist_lock);
816 return found;
817 }
818
819 /*
820 * Move the page from the page cache to the swap cache.
821 */
822 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
823 {
824 struct shmem_inode_info *info;
825 swp_entry_t *entry, swap;
826 struct address_space *mapping;
827 unsigned long index;
828 struct inode *inode;
829
830 BUG_ON(!PageLocked(page));
831 BUG_ON(page_mapped(page));
832
833 mapping = page->mapping;
834 index = page->index;
835 inode = mapping->host;
836 info = SHMEM_I(inode);
837 if (info->flags & VM_LOCKED)
838 goto redirty;
839 swap = get_swap_page();
840 if (!swap.val)
841 goto redirty;
842
843 spin_lock(&info->lock);
844 shmem_recalc_inode(inode);
845 if (index >= info->next_index) {
846 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
847 goto unlock;
848 }
849 entry = shmem_swp_entry(info, index, NULL);
850 BUG_ON(!entry);
851 BUG_ON(entry->val);
852
853 if (move_to_swap_cache(page, swap) == 0) {
854 shmem_swp_set(info, entry, swap.val);
855 shmem_swp_unmap(entry);
856 spin_unlock(&info->lock);
857 if (list_empty(&info->swaplist)) {
858 spin_lock(&shmem_swaplist_lock);
859 /* move instead of add in case we're racing */
860 list_move_tail(&info->swaplist, &shmem_swaplist);
861 spin_unlock(&shmem_swaplist_lock);
862 }
863 unlock_page(page);
864 return 0;
865 }
866
867 shmem_swp_unmap(entry);
868 unlock:
869 spin_unlock(&info->lock);
870 swap_free(swap);
871 redirty:
872 set_page_dirty(page);
873 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */
874 }
875
876 #ifdef CONFIG_NUMA
877 static struct page *shmem_swapin_async(struct shared_policy *p,
878 swp_entry_t entry, unsigned long idx)
879 {
880 struct page *page;
881 struct vm_area_struct pvma;
882
883 /* Create a pseudo vma that just contains the policy */
884 memset(&pvma, 0, sizeof(struct vm_area_struct));
885 pvma.vm_end = PAGE_SIZE;
886 pvma.vm_pgoff = idx;
887 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
888 page = read_swap_cache_async(entry, &pvma, 0);
889 mpol_free(pvma.vm_policy);
890 return page;
891 }
892
893 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
894 unsigned long idx)
895 {
896 struct shared_policy *p = &info->policy;
897 int i, num;
898 struct page *page;
899 unsigned long offset;
900
901 num = valid_swaphandles(entry, &offset);
902 for (i = 0; i < num; offset++, i++) {
903 page = shmem_swapin_async(p,
904 swp_entry(swp_type(entry), offset), idx);
905 if (!page)
906 break;
907 page_cache_release(page);
908 }
909 lru_add_drain(); /* Push any new pages onto the LRU now */
910 return shmem_swapin_async(p, entry, idx);
911 }
912
913 static struct page *
914 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
915 unsigned long idx)
916 {
917 struct vm_area_struct pvma;
918 struct page *page;
919
920 memset(&pvma, 0, sizeof(struct vm_area_struct));
921 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
922 pvma.vm_pgoff = idx;
923 pvma.vm_end = PAGE_SIZE;
924 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
925 mpol_free(pvma.vm_policy);
926 return page;
927 }
928 #else
929 static inline struct page *
930 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
931 {
932 swapin_readahead(entry, 0, NULL);
933 return read_swap_cache_async(entry, NULL, 0);
934 }
935
936 static inline struct page *
937 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
938 {
939 return alloc_page(gfp | __GFP_ZERO);
940 }
941 #endif
942
943 /*
944 * shmem_getpage - either get the page from swap or allocate a new one
945 *
946 * If we allocate a new one we do not mark it dirty. That's up to the
947 * vm. If we swap it in we mark it dirty since we also free the swap
948 * entry since a page cannot live in both the swap and page cache
949 */
950 static int shmem_getpage(struct inode *inode, unsigned long idx,
951 struct page **pagep, enum sgp_type sgp, int *type)
952 {
953 struct address_space *mapping = inode->i_mapping;
954 struct shmem_inode_info *info = SHMEM_I(inode);
955 struct shmem_sb_info *sbinfo;
956 struct page *filepage = *pagep;
957 struct page *swappage;
958 swp_entry_t *entry;
959 swp_entry_t swap;
960 int error;
961
962 if (idx >= SHMEM_MAX_INDEX)
963 return -EFBIG;
964 /*
965 * Normally, filepage is NULL on entry, and either found
966 * uptodate immediately, or allocated and zeroed, or read
967 * in under swappage, which is then assigned to filepage.
968 * But shmem_prepare_write passes in a locked filepage,
969 * which may be found not uptodate by other callers too,
970 * and may need to be copied from the swappage read in.
971 */
972 repeat:
973 if (!filepage)
974 filepage = find_lock_page(mapping, idx);
975 if (filepage && PageUptodate(filepage))
976 goto done;
977 error = 0;
978 if (sgp == SGP_QUICK)
979 goto failed;
980
981 spin_lock(&info->lock);
982 shmem_recalc_inode(inode);
983 entry = shmem_swp_alloc(info, idx, sgp);
984 if (IS_ERR(entry)) {
985 spin_unlock(&info->lock);
986 error = PTR_ERR(entry);
987 goto failed;
988 }
989 swap = *entry;
990
991 if (swap.val) {
992 /* Look it up and read it in.. */
993 swappage = lookup_swap_cache(swap);
994 if (!swappage) {
995 shmem_swp_unmap(entry);
996 spin_unlock(&info->lock);
997 /* here we actually do the io */
998 if (type && *type == VM_FAULT_MINOR) {
999 inc_page_state(pgmajfault);
1000 *type = VM_FAULT_MAJOR;
1001 }
1002 swappage = shmem_swapin(info, swap, idx);
1003 if (!swappage) {
1004 spin_lock(&info->lock);
1005 entry = shmem_swp_alloc(info, idx, sgp);
1006 if (IS_ERR(entry))
1007 error = PTR_ERR(entry);
1008 else {
1009 if (entry->val == swap.val)
1010 error = -ENOMEM;
1011 shmem_swp_unmap(entry);
1012 }
1013 spin_unlock(&info->lock);
1014 if (error)
1015 goto failed;
1016 goto repeat;
1017 }
1018 wait_on_page_locked(swappage);
1019 page_cache_release(swappage);
1020 goto repeat;
1021 }
1022
1023 /* We have to do this with page locked to prevent races */
1024 if (TestSetPageLocked(swappage)) {
1025 shmem_swp_unmap(entry);
1026 spin_unlock(&info->lock);
1027 wait_on_page_locked(swappage);
1028 page_cache_release(swappage);
1029 goto repeat;
1030 }
1031 if (!PageSwapCache(swappage)) {
1032 /* Page migration has occured */
1033 shmem_swp_unmap(entry);
1034 spin_unlock(&info->lock);
1035 unlock_page(swappage);
1036 page_cache_release(swappage);
1037 goto repeat;
1038 }
1039 if (PageWriteback(swappage)) {
1040 shmem_swp_unmap(entry);
1041 spin_unlock(&info->lock);
1042 wait_on_page_writeback(swappage);
1043 unlock_page(swappage);
1044 page_cache_release(swappage);
1045 goto repeat;
1046 }
1047 if (!PageUptodate(swappage)) {
1048 shmem_swp_unmap(entry);
1049 spin_unlock(&info->lock);
1050 unlock_page(swappage);
1051 page_cache_release(swappage);
1052 error = -EIO;
1053 goto failed;
1054 }
1055
1056 if (filepage) {
1057 shmem_swp_set(info, entry, 0);
1058 shmem_swp_unmap(entry);
1059 delete_from_swap_cache(swappage);
1060 spin_unlock(&info->lock);
1061 copy_highpage(filepage, swappage);
1062 unlock_page(swappage);
1063 page_cache_release(swappage);
1064 flush_dcache_page(filepage);
1065 SetPageUptodate(filepage);
1066 set_page_dirty(filepage);
1067 swap_free(swap);
1068 } else if (!(error = move_from_swap_cache(
1069 swappage, idx, mapping))) {
1070 info->flags |= SHMEM_PAGEIN;
1071 shmem_swp_set(info, entry, 0);
1072 shmem_swp_unmap(entry);
1073 spin_unlock(&info->lock);
1074 filepage = swappage;
1075 swap_free(swap);
1076 } else {
1077 shmem_swp_unmap(entry);
1078 spin_unlock(&info->lock);
1079 unlock_page(swappage);
1080 page_cache_release(swappage);
1081 if (error == -ENOMEM) {
1082 /* let kswapd refresh zone for GFP_ATOMICs */
1083 blk_congestion_wait(WRITE, HZ/50);
1084 }
1085 goto repeat;
1086 }
1087 } else if (sgp == SGP_READ && !filepage) {
1088 shmem_swp_unmap(entry);
1089 filepage = find_get_page(mapping, idx);
1090 if (filepage &&
1091 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1092 spin_unlock(&info->lock);
1093 wait_on_page_locked(filepage);
1094 page_cache_release(filepage);
1095 filepage = NULL;
1096 goto repeat;
1097 }
1098 spin_unlock(&info->lock);
1099 } else {
1100 shmem_swp_unmap(entry);
1101 sbinfo = SHMEM_SB(inode->i_sb);
1102 if (sbinfo->max_blocks) {
1103 spin_lock(&sbinfo->stat_lock);
1104 if (sbinfo->free_blocks == 0 ||
1105 shmem_acct_block(info->flags)) {
1106 spin_unlock(&sbinfo->stat_lock);
1107 spin_unlock(&info->lock);
1108 error = -ENOSPC;
1109 goto failed;
1110 }
1111 sbinfo->free_blocks--;
1112 inode->i_blocks += BLOCKS_PER_PAGE;
1113 spin_unlock(&sbinfo->stat_lock);
1114 } else if (shmem_acct_block(info->flags)) {
1115 spin_unlock(&info->lock);
1116 error = -ENOSPC;
1117 goto failed;
1118 }
1119
1120 if (!filepage) {
1121 spin_unlock(&info->lock);
1122 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1123 info,
1124 idx);
1125 if (!filepage) {
1126 shmem_unacct_blocks(info->flags, 1);
1127 shmem_free_blocks(inode, 1);
1128 error = -ENOMEM;
1129 goto failed;
1130 }
1131
1132 spin_lock(&info->lock);
1133 entry = shmem_swp_alloc(info, idx, sgp);
1134 if (IS_ERR(entry))
1135 error = PTR_ERR(entry);
1136 else {
1137 swap = *entry;
1138 shmem_swp_unmap(entry);
1139 }
1140 if (error || swap.val || 0 != add_to_page_cache_lru(
1141 filepage, mapping, idx, GFP_ATOMIC)) {
1142 spin_unlock(&info->lock);
1143 page_cache_release(filepage);
1144 shmem_unacct_blocks(info->flags, 1);
1145 shmem_free_blocks(inode, 1);
1146 filepage = NULL;
1147 if (error)
1148 goto failed;
1149 goto repeat;
1150 }
1151 info->flags |= SHMEM_PAGEIN;
1152 }
1153
1154 info->alloced++;
1155 spin_unlock(&info->lock);
1156 flush_dcache_page(filepage);
1157 SetPageUptodate(filepage);
1158 }
1159 done:
1160 if (*pagep != filepage) {
1161 unlock_page(filepage);
1162 *pagep = filepage;
1163 }
1164 return 0;
1165
1166 failed:
1167 if (*pagep != filepage) {
1168 unlock_page(filepage);
1169 page_cache_release(filepage);
1170 }
1171 return error;
1172 }
1173
1174 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1175 {
1176 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1177 struct page *page = NULL;
1178 unsigned long idx;
1179 int error;
1180
1181 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1182 idx += vma->vm_pgoff;
1183 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1184 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1185 return NOPAGE_SIGBUS;
1186
1187 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1188 if (error)
1189 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1190
1191 mark_page_accessed(page);
1192 return page;
1193 }
1194
1195 static int shmem_populate(struct vm_area_struct *vma,
1196 unsigned long addr, unsigned long len,
1197 pgprot_t prot, unsigned long pgoff, int nonblock)
1198 {
1199 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1200 struct mm_struct *mm = vma->vm_mm;
1201 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1202 unsigned long size;
1203
1204 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1205 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1206 return -EINVAL;
1207
1208 while ((long) len > 0) {
1209 struct page *page = NULL;
1210 int err;
1211 /*
1212 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1213 */
1214 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1215 if (err)
1216 return err;
1217 /* Page may still be null, but only if nonblock was set. */
1218 if (page) {
1219 mark_page_accessed(page);
1220 err = install_page(mm, vma, addr, page, prot);
1221 if (err) {
1222 page_cache_release(page);
1223 return err;
1224 }
1225 } else if (vma->vm_flags & VM_NONLINEAR) {
1226 /* No page was found just because we can't read it in
1227 * now (being here implies nonblock != 0), but the page
1228 * may exist, so set the PTE to fault it in later. */
1229 err = install_file_pte(mm, vma, addr, pgoff, prot);
1230 if (err)
1231 return err;
1232 }
1233
1234 len -= PAGE_SIZE;
1235 addr += PAGE_SIZE;
1236 pgoff++;
1237 }
1238 return 0;
1239 }
1240
1241 #ifdef CONFIG_NUMA
1242 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1243 {
1244 struct inode *i = vma->vm_file->f_dentry->d_inode;
1245 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1246 }
1247
1248 struct mempolicy *
1249 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1250 {
1251 struct inode *i = vma->vm_file->f_dentry->d_inode;
1252 unsigned long idx;
1253
1254 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1255 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1256 }
1257 #endif
1258
1259 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1260 {
1261 struct inode *inode = file->f_dentry->d_inode;
1262 struct shmem_inode_info *info = SHMEM_I(inode);
1263 int retval = -ENOMEM;
1264
1265 spin_lock(&info->lock);
1266 if (lock && !(info->flags & VM_LOCKED)) {
1267 if (!user_shm_lock(inode->i_size, user))
1268 goto out_nomem;
1269 info->flags |= VM_LOCKED;
1270 }
1271 if (!lock && (info->flags & VM_LOCKED) && user) {
1272 user_shm_unlock(inode->i_size, user);
1273 info->flags &= ~VM_LOCKED;
1274 }
1275 retval = 0;
1276 out_nomem:
1277 spin_unlock(&info->lock);
1278 return retval;
1279 }
1280
1281 int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1282 {
1283 file_accessed(file);
1284 vma->vm_ops = &shmem_vm_ops;
1285 return 0;
1286 }
1287
1288 static struct inode *
1289 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1290 {
1291 struct inode *inode;
1292 struct shmem_inode_info *info;
1293 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1294
1295 if (sbinfo->max_inodes) {
1296 spin_lock(&sbinfo->stat_lock);
1297 if (!sbinfo->free_inodes) {
1298 spin_unlock(&sbinfo->stat_lock);
1299 return NULL;
1300 }
1301 sbinfo->free_inodes--;
1302 spin_unlock(&sbinfo->stat_lock);
1303 }
1304
1305 inode = new_inode(sb);
1306 if (inode) {
1307 inode->i_mode = mode;
1308 inode->i_uid = current->fsuid;
1309 inode->i_gid = current->fsgid;
1310 inode->i_blksize = PAGE_CACHE_SIZE;
1311 inode->i_blocks = 0;
1312 inode->i_mapping->a_ops = &shmem_aops;
1313 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1314 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1315 info = SHMEM_I(inode);
1316 memset(info, 0, (char *)inode - (char *)info);
1317 spin_lock_init(&info->lock);
1318 INIT_LIST_HEAD(&info->swaplist);
1319
1320 switch (mode & S_IFMT) {
1321 default:
1322 init_special_inode(inode, mode, dev);
1323 break;
1324 case S_IFREG:
1325 inode->i_op = &shmem_inode_operations;
1326 inode->i_fop = &shmem_file_operations;
1327 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1328 &sbinfo->policy_nodes);
1329 break;
1330 case S_IFDIR:
1331 inode->i_nlink++;
1332 /* Some things misbehave if size == 0 on a directory */
1333 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1334 inode->i_op = &shmem_dir_inode_operations;
1335 inode->i_fop = &simple_dir_operations;
1336 break;
1337 case S_IFLNK:
1338 /*
1339 * Must not load anything in the rbtree,
1340 * mpol_free_shared_policy will not be called.
1341 */
1342 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1343 NULL);
1344 break;
1345 }
1346 } else if (sbinfo->max_inodes) {
1347 spin_lock(&sbinfo->stat_lock);
1348 sbinfo->free_inodes++;
1349 spin_unlock(&sbinfo->stat_lock);
1350 }
1351 return inode;
1352 }
1353
1354 #ifdef CONFIG_TMPFS
1355 static struct inode_operations shmem_symlink_inode_operations;
1356 static struct inode_operations shmem_symlink_inline_operations;
1357
1358 /*
1359 * Normally tmpfs makes no use of shmem_prepare_write, but it
1360 * lets a tmpfs file be used read-write below the loop driver.
1361 */
1362 static int
1363 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1364 {
1365 struct inode *inode = page->mapping->host;
1366 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1367 }
1368
1369 static ssize_t
1370 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1371 {
1372 struct inode *inode = file->f_dentry->d_inode;
1373 loff_t pos;
1374 unsigned long written;
1375 ssize_t err;
1376
1377 if ((ssize_t) count < 0)
1378 return -EINVAL;
1379
1380 if (!access_ok(VERIFY_READ, buf, count))
1381 return -EFAULT;
1382
1383 mutex_lock(&inode->i_mutex);
1384
1385 pos = *ppos;
1386 written = 0;
1387
1388 err = generic_write_checks(file, &pos, &count, 0);
1389 if (err || !count)
1390 goto out;
1391
1392 err = remove_suid(file->f_dentry);
1393 if (err)
1394 goto out;
1395
1396 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1397
1398 do {
1399 struct page *page = NULL;
1400 unsigned long bytes, index, offset;
1401 char *kaddr;
1402 int left;
1403
1404 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1405 index = pos >> PAGE_CACHE_SHIFT;
1406 bytes = PAGE_CACHE_SIZE - offset;
1407 if (bytes > count)
1408 bytes = count;
1409
1410 /*
1411 * We don't hold page lock across copy from user -
1412 * what would it guard against? - so no deadlock here.
1413 * But it still may be a good idea to prefault below.
1414 */
1415
1416 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1417 if (err)
1418 break;
1419
1420 left = bytes;
1421 if (PageHighMem(page)) {
1422 volatile unsigned char dummy;
1423 __get_user(dummy, buf);
1424 __get_user(dummy, buf + bytes - 1);
1425
1426 kaddr = kmap_atomic(page, KM_USER0);
1427 left = __copy_from_user_inatomic(kaddr + offset,
1428 buf, bytes);
1429 kunmap_atomic(kaddr, KM_USER0);
1430 }
1431 if (left) {
1432 kaddr = kmap(page);
1433 left = __copy_from_user(kaddr + offset, buf, bytes);
1434 kunmap(page);
1435 }
1436
1437 written += bytes;
1438 count -= bytes;
1439 pos += bytes;
1440 buf += bytes;
1441 if (pos > inode->i_size)
1442 i_size_write(inode, pos);
1443
1444 flush_dcache_page(page);
1445 set_page_dirty(page);
1446 mark_page_accessed(page);
1447 page_cache_release(page);
1448
1449 if (left) {
1450 pos -= left;
1451 written -= left;
1452 err = -EFAULT;
1453 break;
1454 }
1455
1456 /*
1457 * Our dirty pages are not counted in nr_dirty,
1458 * and we do not attempt to balance dirty pages.
1459 */
1460
1461 cond_resched();
1462 } while (count);
1463
1464 *ppos = pos;
1465 if (written)
1466 err = written;
1467 out:
1468 mutex_unlock(&inode->i_mutex);
1469 return err;
1470 }
1471
1472 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1473 {
1474 struct inode *inode = filp->f_dentry->d_inode;
1475 struct address_space *mapping = inode->i_mapping;
1476 unsigned long index, offset;
1477
1478 index = *ppos >> PAGE_CACHE_SHIFT;
1479 offset = *ppos & ~PAGE_CACHE_MASK;
1480
1481 for (;;) {
1482 struct page *page = NULL;
1483 unsigned long end_index, nr, ret;
1484 loff_t i_size = i_size_read(inode);
1485
1486 end_index = i_size >> PAGE_CACHE_SHIFT;
1487 if (index > end_index)
1488 break;
1489 if (index == end_index) {
1490 nr = i_size & ~PAGE_CACHE_MASK;
1491 if (nr <= offset)
1492 break;
1493 }
1494
1495 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1496 if (desc->error) {
1497 if (desc->error == -EINVAL)
1498 desc->error = 0;
1499 break;
1500 }
1501
1502 /*
1503 * We must evaluate after, since reads (unlike writes)
1504 * are called without i_mutex protection against truncate
1505 */
1506 nr = PAGE_CACHE_SIZE;
1507 i_size = i_size_read(inode);
1508 end_index = i_size >> PAGE_CACHE_SHIFT;
1509 if (index == end_index) {
1510 nr = i_size & ~PAGE_CACHE_MASK;
1511 if (nr <= offset) {
1512 if (page)
1513 page_cache_release(page);
1514 break;
1515 }
1516 }
1517 nr -= offset;
1518
1519 if (page) {
1520 /*
1521 * If users can be writing to this page using arbitrary
1522 * virtual addresses, take care about potential aliasing
1523 * before reading the page on the kernel side.
1524 */
1525 if (mapping_writably_mapped(mapping))
1526 flush_dcache_page(page);
1527 /*
1528 * Mark the page accessed if we read the beginning.
1529 */
1530 if (!offset)
1531 mark_page_accessed(page);
1532 } else {
1533 page = ZERO_PAGE(0);
1534 page_cache_get(page);
1535 }
1536
1537 /*
1538 * Ok, we have the page, and it's up-to-date, so
1539 * now we can copy it to user space...
1540 *
1541 * The actor routine returns how many bytes were actually used..
1542 * NOTE! This may not be the same as how much of a user buffer
1543 * we filled up (we may be padding etc), so we can only update
1544 * "pos" here (the actor routine has to update the user buffer
1545 * pointers and the remaining count).
1546 */
1547 ret = actor(desc, page, offset, nr);
1548 offset += ret;
1549 index += offset >> PAGE_CACHE_SHIFT;
1550 offset &= ~PAGE_CACHE_MASK;
1551
1552 page_cache_release(page);
1553 if (ret != nr || !desc->count)
1554 break;
1555
1556 cond_resched();
1557 }
1558
1559 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1560 file_accessed(filp);
1561 }
1562
1563 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1564 {
1565 read_descriptor_t desc;
1566
1567 if ((ssize_t) count < 0)
1568 return -EINVAL;
1569 if (!access_ok(VERIFY_WRITE, buf, count))
1570 return -EFAULT;
1571 if (!count)
1572 return 0;
1573
1574 desc.written = 0;
1575 desc.count = count;
1576 desc.arg.buf = buf;
1577 desc.error = 0;
1578
1579 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1580 if (desc.written)
1581 return desc.written;
1582 return desc.error;
1583 }
1584
1585 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1586 size_t count, read_actor_t actor, void *target)
1587 {
1588 read_descriptor_t desc;
1589
1590 if (!count)
1591 return 0;
1592
1593 desc.written = 0;
1594 desc.count = count;
1595 desc.arg.data = target;
1596 desc.error = 0;
1597
1598 do_shmem_file_read(in_file, ppos, &desc, actor);
1599 if (desc.written)
1600 return desc.written;
1601 return desc.error;
1602 }
1603
1604 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1605 {
1606 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1607
1608 buf->f_type = TMPFS_MAGIC;
1609 buf->f_bsize = PAGE_CACHE_SIZE;
1610 buf->f_namelen = NAME_MAX;
1611 spin_lock(&sbinfo->stat_lock);
1612 if (sbinfo->max_blocks) {
1613 buf->f_blocks = sbinfo->max_blocks;
1614 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1615 }
1616 if (sbinfo->max_inodes) {
1617 buf->f_files = sbinfo->max_inodes;
1618 buf->f_ffree = sbinfo->free_inodes;
1619 }
1620 /* else leave those fields 0 like simple_statfs */
1621 spin_unlock(&sbinfo->stat_lock);
1622 return 0;
1623 }
1624
1625 /*
1626 * File creation. Allocate an inode, and we're done..
1627 */
1628 static int
1629 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1630 {
1631 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1632 int error = -ENOSPC;
1633
1634 if (inode) {
1635 error = security_inode_init_security(inode, dir, NULL, NULL,
1636 NULL);
1637 if (error) {
1638 if (error != -EOPNOTSUPP) {
1639 iput(inode);
1640 return error;
1641 }
1642 error = 0;
1643 }
1644 if (dir->i_mode & S_ISGID) {
1645 inode->i_gid = dir->i_gid;
1646 if (S_ISDIR(mode))
1647 inode->i_mode |= S_ISGID;
1648 }
1649 dir->i_size += BOGO_DIRENT_SIZE;
1650 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1651 d_instantiate(dentry, inode);
1652 dget(dentry); /* Extra count - pin the dentry in core */
1653 }
1654 return error;
1655 }
1656
1657 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1658 {
1659 int error;
1660
1661 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1662 return error;
1663 dir->i_nlink++;
1664 return 0;
1665 }
1666
1667 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1668 struct nameidata *nd)
1669 {
1670 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1671 }
1672
1673 /*
1674 * Link a file..
1675 */
1676 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1677 {
1678 struct inode *inode = old_dentry->d_inode;
1679 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1680
1681 /*
1682 * No ordinary (disk based) filesystem counts links as inodes;
1683 * but each new link needs a new dentry, pinning lowmem, and
1684 * tmpfs dentries cannot be pruned until they are unlinked.
1685 */
1686 if (sbinfo->max_inodes) {
1687 spin_lock(&sbinfo->stat_lock);
1688 if (!sbinfo->free_inodes) {
1689 spin_unlock(&sbinfo->stat_lock);
1690 return -ENOSPC;
1691 }
1692 sbinfo->free_inodes--;
1693 spin_unlock(&sbinfo->stat_lock);
1694 }
1695
1696 dir->i_size += BOGO_DIRENT_SIZE;
1697 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1698 inode->i_nlink++;
1699 atomic_inc(&inode->i_count); /* New dentry reference */
1700 dget(dentry); /* Extra pinning count for the created dentry */
1701 d_instantiate(dentry, inode);
1702 return 0;
1703 }
1704
1705 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1706 {
1707 struct inode *inode = dentry->d_inode;
1708
1709 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1710 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1711 if (sbinfo->max_inodes) {
1712 spin_lock(&sbinfo->stat_lock);
1713 sbinfo->free_inodes++;
1714 spin_unlock(&sbinfo->stat_lock);
1715 }
1716 }
1717
1718 dir->i_size -= BOGO_DIRENT_SIZE;
1719 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1720 inode->i_nlink--;
1721 dput(dentry); /* Undo the count from "create" - this does all the work */
1722 return 0;
1723 }
1724
1725 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1726 {
1727 if (!simple_empty(dentry))
1728 return -ENOTEMPTY;
1729
1730 dir->i_nlink--;
1731 return shmem_unlink(dir, dentry);
1732 }
1733
1734 /*
1735 * The VFS layer already does all the dentry stuff for rename,
1736 * we just have to decrement the usage count for the target if
1737 * it exists so that the VFS layer correctly free's it when it
1738 * gets overwritten.
1739 */
1740 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1741 {
1742 struct inode *inode = old_dentry->d_inode;
1743 int they_are_dirs = S_ISDIR(inode->i_mode);
1744
1745 if (!simple_empty(new_dentry))
1746 return -ENOTEMPTY;
1747
1748 if (new_dentry->d_inode) {
1749 (void) shmem_unlink(new_dir, new_dentry);
1750 if (they_are_dirs)
1751 old_dir->i_nlink--;
1752 } else if (they_are_dirs) {
1753 old_dir->i_nlink--;
1754 new_dir->i_nlink++;
1755 }
1756
1757 old_dir->i_size -= BOGO_DIRENT_SIZE;
1758 new_dir->i_size += BOGO_DIRENT_SIZE;
1759 old_dir->i_ctime = old_dir->i_mtime =
1760 new_dir->i_ctime = new_dir->i_mtime =
1761 inode->i_ctime = CURRENT_TIME;
1762 return 0;
1763 }
1764
1765 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1766 {
1767 int error;
1768 int len;
1769 struct inode *inode;
1770 struct page *page = NULL;
1771 char *kaddr;
1772 struct shmem_inode_info *info;
1773
1774 len = strlen(symname) + 1;
1775 if (len > PAGE_CACHE_SIZE)
1776 return -ENAMETOOLONG;
1777
1778 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1779 if (!inode)
1780 return -ENOSPC;
1781
1782 error = security_inode_init_security(inode, dir, NULL, NULL,
1783 NULL);
1784 if (error) {
1785 if (error != -EOPNOTSUPP) {
1786 iput(inode);
1787 return error;
1788 }
1789 error = 0;
1790 }
1791
1792 info = SHMEM_I(inode);
1793 inode->i_size = len-1;
1794 if (len <= (char *)inode - (char *)info) {
1795 /* do it inline */
1796 memcpy(info, symname, len);
1797 inode->i_op = &shmem_symlink_inline_operations;
1798 } else {
1799 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1800 if (error) {
1801 iput(inode);
1802 return error;
1803 }
1804 inode->i_op = &shmem_symlink_inode_operations;
1805 kaddr = kmap_atomic(page, KM_USER0);
1806 memcpy(kaddr, symname, len);
1807 kunmap_atomic(kaddr, KM_USER0);
1808 set_page_dirty(page);
1809 page_cache_release(page);
1810 }
1811 if (dir->i_mode & S_ISGID)
1812 inode->i_gid = dir->i_gid;
1813 dir->i_size += BOGO_DIRENT_SIZE;
1814 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1815 d_instantiate(dentry, inode);
1816 dget(dentry);
1817 return 0;
1818 }
1819
1820 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1821 {
1822 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1823 return NULL;
1824 }
1825
1826 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1827 {
1828 struct page *page = NULL;
1829 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1830 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1831 return page;
1832 }
1833
1834 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1835 {
1836 if (!IS_ERR(nd_get_link(nd))) {
1837 struct page *page = cookie;
1838 kunmap(page);
1839 mark_page_accessed(page);
1840 page_cache_release(page);
1841 }
1842 }
1843
1844 static struct inode_operations shmem_symlink_inline_operations = {
1845 .readlink = generic_readlink,
1846 .follow_link = shmem_follow_link_inline,
1847 };
1848
1849 static struct inode_operations shmem_symlink_inode_operations = {
1850 .truncate = shmem_truncate,
1851 .readlink = generic_readlink,
1852 .follow_link = shmem_follow_link,
1853 .put_link = shmem_put_link,
1854 };
1855
1856 static int shmem_parse_options(char *options, int *mode, uid_t *uid,
1857 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
1858 int *policy, nodemask_t *policy_nodes)
1859 {
1860 char *this_char, *value, *rest;
1861
1862 while ((this_char = strsep(&options, ",")) != NULL) {
1863 if (!*this_char)
1864 continue;
1865 if ((value = strchr(this_char,'=')) != NULL) {
1866 *value++ = 0;
1867 } else {
1868 printk(KERN_ERR
1869 "tmpfs: No value for mount option '%s'\n",
1870 this_char);
1871 return 1;
1872 }
1873
1874 if (!strcmp(this_char,"size")) {
1875 unsigned long long size;
1876 size = memparse(value,&rest);
1877 if (*rest == '%') {
1878 size <<= PAGE_SHIFT;
1879 size *= totalram_pages;
1880 do_div(size, 100);
1881 rest++;
1882 }
1883 if (*rest)
1884 goto bad_val;
1885 *blocks = size >> PAGE_CACHE_SHIFT;
1886 } else if (!strcmp(this_char,"nr_blocks")) {
1887 *blocks = memparse(value,&rest);
1888 if (*rest)
1889 goto bad_val;
1890 } else if (!strcmp(this_char,"nr_inodes")) {
1891 *inodes = memparse(value,&rest);
1892 if (*rest)
1893 goto bad_val;
1894 } else if (!strcmp(this_char,"mode")) {
1895 if (!mode)
1896 continue;
1897 *mode = simple_strtoul(value,&rest,8);
1898 if (*rest)
1899 goto bad_val;
1900 } else if (!strcmp(this_char,"uid")) {
1901 if (!uid)
1902 continue;
1903 *uid = simple_strtoul(value,&rest,0);
1904 if (*rest)
1905 goto bad_val;
1906 } else if (!strcmp(this_char,"gid")) {
1907 if (!gid)
1908 continue;
1909 *gid = simple_strtoul(value,&rest,0);
1910 if (*rest)
1911 goto bad_val;
1912 } else if (!strcmp(this_char,"mpol")) {
1913 if (!strcmp(value,"default"))
1914 *policy = MPOL_DEFAULT;
1915 else if (!strcmp(value,"preferred"))
1916 *policy = MPOL_PREFERRED;
1917 else if (!strcmp(value,"bind"))
1918 *policy = MPOL_BIND;
1919 else if (!strcmp(value,"interleave"))
1920 *policy = MPOL_INTERLEAVE;
1921 else
1922 goto bad_val;
1923 } else if (!strcmp(this_char,"mpol_nodelist")) {
1924 nodelist_parse(value, *policy_nodes);
1925 } else {
1926 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1927 this_char);
1928 return 1;
1929 }
1930 }
1931 return 0;
1932
1933 bad_val:
1934 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1935 value, this_char);
1936 return 1;
1937
1938 }
1939
1940 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1941 {
1942 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1943 unsigned long max_blocks = sbinfo->max_blocks;
1944 unsigned long max_inodes = sbinfo->max_inodes;
1945 int policy = sbinfo->policy;
1946 nodemask_t policy_nodes = sbinfo->policy_nodes;
1947 unsigned long blocks;
1948 unsigned long inodes;
1949 int error = -EINVAL;
1950
1951 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
1952 &max_inodes, &policy, &policy_nodes))
1953 return error;
1954
1955 spin_lock(&sbinfo->stat_lock);
1956 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1957 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1958 if (max_blocks < blocks)
1959 goto out;
1960 if (max_inodes < inodes)
1961 goto out;
1962 /*
1963 * Those tests also disallow limited->unlimited while any are in
1964 * use, so i_blocks will always be zero when max_blocks is zero;
1965 * but we must separately disallow unlimited->limited, because
1966 * in that case we have no record of how much is already in use.
1967 */
1968 if (max_blocks && !sbinfo->max_blocks)
1969 goto out;
1970 if (max_inodes && !sbinfo->max_inodes)
1971 goto out;
1972
1973 error = 0;
1974 sbinfo->max_blocks = max_blocks;
1975 sbinfo->free_blocks = max_blocks - blocks;
1976 sbinfo->max_inodes = max_inodes;
1977 sbinfo->free_inodes = max_inodes - inodes;
1978 sbinfo->policy = policy;
1979 sbinfo->policy_nodes = policy_nodes;
1980 out:
1981 spin_unlock(&sbinfo->stat_lock);
1982 return error;
1983 }
1984 #endif
1985
1986 static void shmem_put_super(struct super_block *sb)
1987 {
1988 kfree(sb->s_fs_info);
1989 sb->s_fs_info = NULL;
1990 }
1991
1992 static int shmem_fill_super(struct super_block *sb,
1993 void *data, int silent)
1994 {
1995 struct inode *inode;
1996 struct dentry *root;
1997 int mode = S_IRWXUGO | S_ISVTX;
1998 uid_t uid = current->fsuid;
1999 gid_t gid = current->fsgid;
2000 int err = -ENOMEM;
2001 struct shmem_sb_info *sbinfo;
2002 unsigned long blocks = 0;
2003 unsigned long inodes = 0;
2004 int policy = MPOL_DEFAULT;
2005 nodemask_t policy_nodes = node_online_map;
2006
2007 #ifdef CONFIG_TMPFS
2008 /*
2009 * Per default we only allow half of the physical ram per
2010 * tmpfs instance, limiting inodes to one per page of lowmem;
2011 * but the internal instance is left unlimited.
2012 */
2013 if (!(sb->s_flags & MS_NOUSER)) {
2014 blocks = totalram_pages / 2;
2015 inodes = totalram_pages - totalhigh_pages;
2016 if (inodes > blocks)
2017 inodes = blocks;
2018 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2019 &inodes, &policy, &policy_nodes))
2020 return -EINVAL;
2021 }
2022 #else
2023 sb->s_flags |= MS_NOUSER;
2024 #endif
2025
2026 /* Round up to L1_CACHE_BYTES to resist false sharing */
2027 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2028 L1_CACHE_BYTES), GFP_KERNEL);
2029 if (!sbinfo)
2030 return -ENOMEM;
2031
2032 spin_lock_init(&sbinfo->stat_lock);
2033 sbinfo->max_blocks = blocks;
2034 sbinfo->free_blocks = blocks;
2035 sbinfo->max_inodes = inodes;
2036 sbinfo->free_inodes = inodes;
2037 sbinfo->policy = policy;
2038 sbinfo->policy_nodes = policy_nodes;
2039
2040 sb->s_fs_info = sbinfo;
2041 sb->s_maxbytes = SHMEM_MAX_BYTES;
2042 sb->s_blocksize = PAGE_CACHE_SIZE;
2043 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2044 sb->s_magic = TMPFS_MAGIC;
2045 sb->s_op = &shmem_ops;
2046
2047 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2048 if (!inode)
2049 goto failed;
2050 inode->i_uid = uid;
2051 inode->i_gid = gid;
2052 root = d_alloc_root(inode);
2053 if (!root)
2054 goto failed_iput;
2055 sb->s_root = root;
2056 return 0;
2057
2058 failed_iput:
2059 iput(inode);
2060 failed:
2061 shmem_put_super(sb);
2062 return err;
2063 }
2064
2065 static kmem_cache_t *shmem_inode_cachep;
2066
2067 static struct inode *shmem_alloc_inode(struct super_block *sb)
2068 {
2069 struct shmem_inode_info *p;
2070 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2071 if (!p)
2072 return NULL;
2073 return &p->vfs_inode;
2074 }
2075
2076 static void shmem_destroy_inode(struct inode *inode)
2077 {
2078 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2079 /* only struct inode is valid if it's an inline symlink */
2080 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2081 }
2082 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2083 }
2084
2085 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2086 {
2087 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2088
2089 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2090 SLAB_CTOR_CONSTRUCTOR) {
2091 inode_init_once(&p->vfs_inode);
2092 }
2093 }
2094
2095 static int init_inodecache(void)
2096 {
2097 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2098 sizeof(struct shmem_inode_info),
2099 0, 0, init_once, NULL);
2100 if (shmem_inode_cachep == NULL)
2101 return -ENOMEM;
2102 return 0;
2103 }
2104
2105 static void destroy_inodecache(void)
2106 {
2107 if (kmem_cache_destroy(shmem_inode_cachep))
2108 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2109 }
2110
2111 static struct address_space_operations shmem_aops = {
2112 .writepage = shmem_writepage,
2113 .set_page_dirty = __set_page_dirty_nobuffers,
2114 #ifdef CONFIG_TMPFS
2115 .prepare_write = shmem_prepare_write,
2116 .commit_write = simple_commit_write,
2117 #endif
2118 };
2119
2120 static struct file_operations shmem_file_operations = {
2121 .mmap = shmem_mmap,
2122 #ifdef CONFIG_TMPFS
2123 .llseek = generic_file_llseek,
2124 .read = shmem_file_read,
2125 .write = shmem_file_write,
2126 .fsync = simple_sync_file,
2127 .sendfile = shmem_file_sendfile,
2128 #endif
2129 };
2130
2131 static struct inode_operations shmem_inode_operations = {
2132 .truncate = shmem_truncate,
2133 .setattr = shmem_notify_change,
2134 .truncate_range = shmem_truncate_range,
2135 };
2136
2137 static struct inode_operations shmem_dir_inode_operations = {
2138 #ifdef CONFIG_TMPFS
2139 .create = shmem_create,
2140 .lookup = simple_lookup,
2141 .link = shmem_link,
2142 .unlink = shmem_unlink,
2143 .symlink = shmem_symlink,
2144 .mkdir = shmem_mkdir,
2145 .rmdir = shmem_rmdir,
2146 .mknod = shmem_mknod,
2147 .rename = shmem_rename,
2148 #endif
2149 };
2150
2151 static struct super_operations shmem_ops = {
2152 .alloc_inode = shmem_alloc_inode,
2153 .destroy_inode = shmem_destroy_inode,
2154 #ifdef CONFIG_TMPFS
2155 .statfs = shmem_statfs,
2156 .remount_fs = shmem_remount_fs,
2157 #endif
2158 .delete_inode = shmem_delete_inode,
2159 .drop_inode = generic_delete_inode,
2160 .put_super = shmem_put_super,
2161 };
2162
2163 static struct vm_operations_struct shmem_vm_ops = {
2164 .nopage = shmem_nopage,
2165 .populate = shmem_populate,
2166 #ifdef CONFIG_NUMA
2167 .set_policy = shmem_set_policy,
2168 .get_policy = shmem_get_policy,
2169 #endif
2170 };
2171
2172
2173 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2174 int flags, const char *dev_name, void *data)
2175 {
2176 return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2177 }
2178
2179 static struct file_system_type tmpfs_fs_type = {
2180 .owner = THIS_MODULE,
2181 .name = "tmpfs",
2182 .get_sb = shmem_get_sb,
2183 .kill_sb = kill_litter_super,
2184 };
2185 static struct vfsmount *shm_mnt;
2186
2187 static int __init init_tmpfs(void)
2188 {
2189 int error;
2190
2191 error = init_inodecache();
2192 if (error)
2193 goto out3;
2194
2195 error = register_filesystem(&tmpfs_fs_type);
2196 if (error) {
2197 printk(KERN_ERR "Could not register tmpfs\n");
2198 goto out2;
2199 }
2200 #ifdef CONFIG_TMPFS
2201 devfs_mk_dir("shm");
2202 #endif
2203 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2204 tmpfs_fs_type.name, NULL);
2205 if (IS_ERR(shm_mnt)) {
2206 error = PTR_ERR(shm_mnt);
2207 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2208 goto out1;
2209 }
2210 return 0;
2211
2212 out1:
2213 unregister_filesystem(&tmpfs_fs_type);
2214 out2:
2215 destroy_inodecache();
2216 out3:
2217 shm_mnt = ERR_PTR(error);
2218 return error;
2219 }
2220 module_init(init_tmpfs)
2221
2222 /*
2223 * shmem_file_setup - get an unlinked file living in tmpfs
2224 *
2225 * @name: name for dentry (to be seen in /proc/<pid>/maps
2226 * @size: size to be set for the file
2227 *
2228 */
2229 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2230 {
2231 int error;
2232 struct file *file;
2233 struct inode *inode;
2234 struct dentry *dentry, *root;
2235 struct qstr this;
2236
2237 if (IS_ERR(shm_mnt))
2238 return (void *)shm_mnt;
2239
2240 if (size < 0 || size > SHMEM_MAX_BYTES)
2241 return ERR_PTR(-EINVAL);
2242
2243 if (shmem_acct_size(flags, size))
2244 return ERR_PTR(-ENOMEM);
2245
2246 error = -ENOMEM;
2247 this.name = name;
2248 this.len = strlen(name);
2249 this.hash = 0; /* will go */
2250 root = shm_mnt->mnt_root;
2251 dentry = d_alloc(root, &this);
2252 if (!dentry)
2253 goto put_memory;
2254
2255 error = -ENFILE;
2256 file = get_empty_filp();
2257 if (!file)
2258 goto put_dentry;
2259
2260 error = -ENOSPC;
2261 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2262 if (!inode)
2263 goto close_file;
2264
2265 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2266 d_instantiate(dentry, inode);
2267 inode->i_size = size;
2268 inode->i_nlink = 0; /* It is unlinked */
2269 file->f_vfsmnt = mntget(shm_mnt);
2270 file->f_dentry = dentry;
2271 file->f_mapping = inode->i_mapping;
2272 file->f_op = &shmem_file_operations;
2273 file->f_mode = FMODE_WRITE | FMODE_READ;
2274 return file;
2275
2276 close_file:
2277 put_filp(file);
2278 put_dentry:
2279 dput(dentry);
2280 put_memory:
2281 shmem_unacct_size(flags, size);
2282 return ERR_PTR(error);
2283 }
2284
2285 /*
2286 * shmem_zero_setup - setup a shared anonymous mapping
2287 *
2288 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2289 */
2290 int shmem_zero_setup(struct vm_area_struct *vma)
2291 {
2292 struct file *file;
2293 loff_t size = vma->vm_end - vma->vm_start;
2294
2295 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2296 if (IS_ERR(file))
2297 return PTR_ERR(file);
2298
2299 if (vma->vm_file)
2300 fput(vma->vm_file);
2301 vma->vm_file = file;
2302 vma->vm_ops = &shmem_vm_ops;
2303 return 0;
2304 }
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