blob: fcd19d323f9f68079f92c4899218411f4f97d50b [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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.
Hugh Dickins0edd73b2005-06-21 17:15:04 -07009 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * 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
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/module.h>
27#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/fs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070029#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070030#include <linux/exportfs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070031#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/mm.h>
33#include <linux/mman.h>
34#include <linux/file.h>
35#include <linux/swap.h>
36#include <linux/pagemap.h>
37#include <linux/string.h>
38#include <linux/slab.h>
39#include <linux/backing-dev.h>
40#include <linux/shmem_fs.h>
41#include <linux/mount.h>
42#include <linux/writeback.h>
43#include <linux/vfs.h>
44#include <linux/blkdev.h>
45#include <linux/security.h>
46#include <linux/swapops.h>
47#include <linux/mempolicy.h>
48#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000049#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070050#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070051#include <linux/highmem.h>
Andrew Morton3fcfab12006-10-19 23:28:16 -070052#include <linux/backing-dev.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070053
Linus Torvalds1da177e2005-04-16 15:20:36 -070054#include <asm/uaccess.h>
55#include <asm/div64.h>
56#include <asm/pgtable.h>
57
58/* This magic number is used in glibc for posix shared memory */
59#define TMPFS_MAGIC 0x01021994
60
61#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
62#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
63#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
64
65#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
66#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
67
68#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
69
70/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
71#define SHMEM_PAGEIN VM_READ
72#define SHMEM_TRUNCATE VM_WRITE
73
74/* Definition to limit shmem_truncate's steps between cond_rescheds */
75#define LATENCY_LIMIT 64
76
77/* Pretend that each entry is of this size in directory's i_size */
78#define BOGO_DIRENT_SIZE 20
79
Linus Torvalds1da177e2005-04-16 15:20:36 -070080/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
81enum sgp_type {
82 SGP_QUICK, /* don't try more than file page cache lookup */
83 SGP_READ, /* don't exceed i_size, don't allocate page */
84 SGP_CACHE, /* don't exceed i_size, may allocate page */
85 SGP_WRITE, /* may exceed i_size, may allocate page */
Nick Piggin54cb8822007-07-19 01:46:59 -070086 SGP_FAULT, /* same as SGP_CACHE, return with page locked */
Linus Torvalds1da177e2005-04-16 15:20:36 -070087};
88
89static int shmem_getpage(struct inode *inode, unsigned long idx,
90 struct page **pagep, enum sgp_type sgp, int *type);
91
Al Viro6daa0e22005-10-21 03:18:50 -040092static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093{
94 /*
95 * The above definition of ENTRIES_PER_PAGE, and the use of
96 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
97 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -070098 *
99 * __GFP_MOVABLE is masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100 */
Mel Gorman769848c2007-07-17 04:03:05 -0700101 return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __GFP_ZERO,
102 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700103}
104
105static inline void shmem_dir_free(struct page *page)
106{
107 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
108}
109
110static struct page **shmem_dir_map(struct page *page)
111{
112 return (struct page **)kmap_atomic(page, KM_USER0);
113}
114
115static inline void shmem_dir_unmap(struct page **dir)
116{
117 kunmap_atomic(dir, KM_USER0);
118}
119
120static swp_entry_t *shmem_swp_map(struct page *page)
121{
122 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
123}
124
125static inline void shmem_swp_balance_unmap(void)
126{
127 /*
128 * When passing a pointer to an i_direct entry, to code which
129 * also handles indirect entries and so will shmem_swp_unmap,
130 * we must arrange for the preempt count to remain in balance.
131 * What kmap_atomic of a lowmem page does depends on config
132 * and architecture, so pretend to kmap_atomic some lowmem page.
133 */
134 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
135}
136
137static inline void shmem_swp_unmap(swp_entry_t *entry)
138{
139 kunmap_atomic(entry, KM_USER1);
140}
141
142static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
143{
144 return sb->s_fs_info;
145}
146
147/*
148 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
149 * for shared memory and for shared anonymous (/dev/zero) mappings
150 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
151 * consistent with the pre-accounting of private mappings ...
152 */
153static inline int shmem_acct_size(unsigned long flags, loff_t size)
154{
155 return (flags & VM_ACCOUNT)?
156 security_vm_enough_memory(VM_ACCT(size)): 0;
157}
158
159static inline void shmem_unacct_size(unsigned long flags, loff_t size)
160{
161 if (flags & VM_ACCOUNT)
162 vm_unacct_memory(VM_ACCT(size));
163}
164
165/*
166 * ... whereas tmpfs objects are accounted incrementally as
167 * pages are allocated, in order to allow huge sparse files.
168 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
169 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
170 */
171static inline int shmem_acct_block(unsigned long flags)
172{
173 return (flags & VM_ACCOUNT)?
174 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
175}
176
177static inline void shmem_unacct_blocks(unsigned long flags, long pages)
178{
179 if (!(flags & VM_ACCOUNT))
180 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
181}
182
Hugh Dickins759b9772007-03-05 00:30:28 -0800183static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700184static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800185static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800186static const struct inode_operations shmem_inode_operations;
187static const struct inode_operations shmem_dir_inode_operations;
188static const struct inode_operations shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189static struct vm_operations_struct shmem_vm_ops;
190
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700191static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 .ra_pages = 0, /* No readahead */
193 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
194 .unplug_io_fn = default_unplug_io_fn,
195};
196
197static LIST_HEAD(shmem_swaplist);
198static DEFINE_SPINLOCK(shmem_swaplist_lock);
199
200static void shmem_free_blocks(struct inode *inode, long pages)
201{
202 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700203 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 spin_lock(&sbinfo->stat_lock);
205 sbinfo->free_blocks += pages;
206 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
207 spin_unlock(&sbinfo->stat_lock);
208 }
209}
210
211/*
212 * shmem_recalc_inode - recalculate the size of an inode
213 *
214 * @inode: inode to recalc
215 *
216 * We have to calculate the free blocks since the mm can drop
217 * undirtied hole pages behind our back.
218 *
219 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
220 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
221 *
222 * It has to be called with the spinlock held.
223 */
224static void shmem_recalc_inode(struct inode *inode)
225{
226 struct shmem_inode_info *info = SHMEM_I(inode);
227 long freed;
228
229 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
230 if (freed > 0) {
231 info->alloced -= freed;
232 shmem_unacct_blocks(info->flags, freed);
233 shmem_free_blocks(inode, freed);
234 }
235}
236
237/*
238 * shmem_swp_entry - find the swap vector position in the info structure
239 *
240 * @info: info structure for the inode
241 * @index: index of the page to find
242 * @page: optional page to add to the structure. Has to be preset to
243 * all zeros
244 *
245 * If there is no space allocated yet it will return NULL when
246 * page is NULL, else it will use the page for the needed block,
247 * setting it to NULL on return to indicate that it has been used.
248 *
249 * The swap vector is organized the following way:
250 *
251 * There are SHMEM_NR_DIRECT entries directly stored in the
252 * shmem_inode_info structure. So small files do not need an addional
253 * allocation.
254 *
255 * For pages with index > SHMEM_NR_DIRECT there is the pointer
256 * i_indirect which points to a page which holds in the first half
257 * doubly indirect blocks, in the second half triple indirect blocks:
258 *
259 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
260 * following layout (for SHMEM_NR_DIRECT == 16):
261 *
262 * i_indirect -> dir --> 16-19
263 * | +-> 20-23
264 * |
265 * +-->dir2 --> 24-27
266 * | +-> 28-31
267 * | +-> 32-35
268 * | +-> 36-39
269 * |
270 * +-->dir3 --> 40-43
271 * +-> 44-47
272 * +-> 48-51
273 * +-> 52-55
274 */
275static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
276{
277 unsigned long offset;
278 struct page **dir;
279 struct page *subdir;
280
281 if (index < SHMEM_NR_DIRECT) {
282 shmem_swp_balance_unmap();
283 return info->i_direct+index;
284 }
285 if (!info->i_indirect) {
286 if (page) {
287 info->i_indirect = *page;
288 *page = NULL;
289 }
290 return NULL; /* need another page */
291 }
292
293 index -= SHMEM_NR_DIRECT;
294 offset = index % ENTRIES_PER_PAGE;
295 index /= ENTRIES_PER_PAGE;
296 dir = shmem_dir_map(info->i_indirect);
297
298 if (index >= ENTRIES_PER_PAGE/2) {
299 index -= ENTRIES_PER_PAGE/2;
300 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
301 index %= ENTRIES_PER_PAGE;
302 subdir = *dir;
303 if (!subdir) {
304 if (page) {
305 *dir = *page;
306 *page = NULL;
307 }
308 shmem_dir_unmap(dir);
309 return NULL; /* need another page */
310 }
311 shmem_dir_unmap(dir);
312 dir = shmem_dir_map(subdir);
313 }
314
315 dir += index;
316 subdir = *dir;
317 if (!subdir) {
318 if (!page || !(subdir = *page)) {
319 shmem_dir_unmap(dir);
320 return NULL; /* need a page */
321 }
322 *dir = subdir;
323 *page = NULL;
324 }
325 shmem_dir_unmap(dir);
326 return shmem_swp_map(subdir) + offset;
327}
328
329static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
330{
331 long incdec = value? 1: -1;
332
333 entry->val = value;
334 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700335 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
336 struct page *page = kmap_atomic_to_page(entry);
337 set_page_private(page, page_private(page) + incdec);
338 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339}
340
341/*
342 * shmem_swp_alloc - get the position of the swap entry for the page.
343 * If it does not exist allocate the entry.
344 *
345 * @info: info structure for the inode
346 * @index: index of the page to find
347 * @sgp: check and recheck i_size? skip allocation?
348 */
349static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
350{
351 struct inode *inode = &info->vfs_inode;
352 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
353 struct page *page = NULL;
354 swp_entry_t *entry;
355
356 if (sgp != SGP_WRITE &&
357 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
358 return ERR_PTR(-EINVAL);
359
360 while (!(entry = shmem_swp_entry(info, index, &page))) {
361 if (sgp == SGP_READ)
362 return shmem_swp_map(ZERO_PAGE(0));
363 /*
364 * Test free_blocks against 1 not 0, since we have 1 data
365 * page (and perhaps indirect index pages) yet to allocate:
366 * a waste to allocate index if we cannot allocate data.
367 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700368 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 spin_lock(&sbinfo->stat_lock);
370 if (sbinfo->free_blocks <= 1) {
371 spin_unlock(&sbinfo->stat_lock);
372 return ERR_PTR(-ENOSPC);
373 }
374 sbinfo->free_blocks--;
375 inode->i_blocks += BLOCKS_PER_PAGE;
376 spin_unlock(&sbinfo->stat_lock);
377 }
378
379 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700380 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700381 if (page)
382 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 spin_lock(&info->lock);
384
385 if (!page) {
386 shmem_free_blocks(inode, 1);
387 return ERR_PTR(-ENOMEM);
388 }
389 if (sgp != SGP_WRITE &&
390 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
391 entry = ERR_PTR(-EINVAL);
392 break;
393 }
394 if (info->next_index <= index)
395 info->next_index = index + 1;
396 }
397 if (page) {
398 /* another task gave its page, or truncated the file */
399 shmem_free_blocks(inode, 1);
400 shmem_dir_free(page);
401 }
402 if (info->next_index <= index && !IS_ERR(entry))
403 info->next_index = index + 1;
404 return entry;
405}
406
407/*
408 * shmem_free_swp - free some swap entries in a directory
409 *
Hugh Dickins1ae70002007-03-29 01:20:36 -0700410 * @dir: pointer to the directory
411 * @edir: pointer after last entry of the directory
412 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700414static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
415 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700417 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 swp_entry_t *ptr;
419 int freed = 0;
420
421 for (ptr = dir; ptr < edir; ptr++) {
422 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700423 if (unlikely(punch_lock)) {
424 punch_unlock = punch_lock;
425 punch_lock = NULL;
426 spin_lock(punch_unlock);
427 if (!ptr->val)
428 continue;
429 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 free_swap_and_cache(*ptr);
431 *ptr = (swp_entry_t){0};
432 freed++;
433 }
434 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700435 if (punch_unlock)
436 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 return freed;
438}
439
Hugh Dickins1ae70002007-03-29 01:20:36 -0700440static int shmem_map_and_free_swp(struct page *subdir, int offset,
441 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442{
443 swp_entry_t *ptr;
444 int freed = 0;
445
446 ptr = shmem_swp_map(subdir);
447 for (; offset < limit; offset += LATENCY_LIMIT) {
448 int size = limit - offset;
449 if (size > LATENCY_LIMIT)
450 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700451 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
452 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 if (need_resched()) {
454 shmem_swp_unmap(ptr);
455 if (*dir) {
456 shmem_dir_unmap(*dir);
457 *dir = NULL;
458 }
459 cond_resched();
460 ptr = shmem_swp_map(subdir);
461 }
462 }
463 shmem_swp_unmap(ptr);
464 return freed;
465}
466
467static void shmem_free_pages(struct list_head *next)
468{
469 struct page *page;
470 int freed = 0;
471
472 do {
473 page = container_of(next, struct page, lru);
474 next = next->next;
475 shmem_dir_free(page);
476 freed++;
477 if (freed >= LATENCY_LIMIT) {
478 cond_resched();
479 freed = 0;
480 }
481 } while (next);
482}
483
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800484static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700485{
486 struct shmem_inode_info *info = SHMEM_I(inode);
487 unsigned long idx;
488 unsigned long size;
489 unsigned long limit;
490 unsigned long stage;
491 unsigned long diroff;
492 struct page **dir;
493 struct page *topdir;
494 struct page *middir;
495 struct page *subdir;
496 swp_entry_t *ptr;
497 LIST_HEAD(pages_to_free);
498 long nr_pages_to_free = 0;
499 long nr_swaps_freed = 0;
500 int offset;
501 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700502 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700503 spinlock_t *needs_lock;
504 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700505 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
507 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800508 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509 if (idx >= info->next_index)
510 return;
511
512 spin_lock(&info->lock);
513 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800514 if (likely(end == (loff_t) -1)) {
515 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700516 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800517 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700518 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700519 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800520 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700521 if (end + 1 >= inode->i_size) { /* we may free a little more */
522 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
523 PAGE_CACHE_SHIFT;
524 upper_limit = SHMEM_MAX_INDEX;
525 } else {
526 limit = (end + 1) >> PAGE_CACHE_SHIFT;
527 upper_limit = limit;
528 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700529 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800530 punch_hole = 1;
531 }
532
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800534 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 info->i_indirect = NULL;
536 nr_pages_to_free++;
537 list_add(&topdir->lru, &pages_to_free);
538 }
539 spin_unlock(&info->lock);
540
541 if (info->swapped && idx < SHMEM_NR_DIRECT) {
542 ptr = info->i_direct;
543 size = limit;
544 if (size > SHMEM_NR_DIRECT)
545 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700546 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800548
549 /*
550 * If there are no indirect blocks or we are punching a hole
551 * below indirect blocks, nothing to be done.
552 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700553 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 goto done2;
555
Hugh Dickins1ae70002007-03-29 01:20:36 -0700556 /*
557 * The truncation case has already dropped info->lock, and we're safe
558 * because i_size and next_index have already been lowered, preventing
559 * access beyond. But in the punch_hole case, we still need to take
560 * the lock when updating the swap directory, because there might be
561 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
562 * shmem_writepage. However, whenever we find we can remove a whole
563 * directory page (not at the misaligned start or end of the range),
564 * we first NULLify its pointer in the level above, and then have no
565 * need to take the lock when updating its contents: needs_lock and
566 * punch_lock (either pointing to info->lock or NULL) manage this.
567 */
568
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700569 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 limit -= SHMEM_NR_DIRECT;
571 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
572 offset = idx % ENTRIES_PER_PAGE;
573 idx -= offset;
574
575 dir = shmem_dir_map(topdir);
576 stage = ENTRIES_PER_PAGEPAGE/2;
577 if (idx < ENTRIES_PER_PAGEPAGE/2) {
578 middir = topdir;
579 diroff = idx/ENTRIES_PER_PAGE;
580 } else {
581 dir += ENTRIES_PER_PAGE/2;
582 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
583 while (stage <= idx)
584 stage += ENTRIES_PER_PAGEPAGE;
585 middir = *dir;
586 if (*dir) {
587 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
588 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700589 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700590 if (needs_lock) {
591 spin_lock(needs_lock);
592 *dir = NULL;
593 spin_unlock(needs_lock);
594 needs_lock = NULL;
595 } else
596 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 nr_pages_to_free++;
598 list_add(&middir->lru, &pages_to_free);
599 }
600 shmem_dir_unmap(dir);
601 dir = shmem_dir_map(middir);
602 } else {
603 diroff = 0;
604 offset = 0;
605 idx = stage;
606 }
607 }
608
609 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
610 if (unlikely(idx == stage)) {
611 shmem_dir_unmap(dir);
612 dir = shmem_dir_map(topdir) +
613 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
614 while (!*dir) {
615 dir++;
616 idx += ENTRIES_PER_PAGEPAGE;
617 if (idx >= limit)
618 goto done1;
619 }
620 stage = idx + ENTRIES_PER_PAGEPAGE;
621 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700622 if (punch_hole)
623 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700624 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700625 if (needs_lock) {
626 spin_lock(needs_lock);
627 *dir = NULL;
628 spin_unlock(needs_lock);
629 needs_lock = NULL;
630 } else
631 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700632 nr_pages_to_free++;
633 list_add(&middir->lru, &pages_to_free);
634 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 shmem_dir_unmap(dir);
636 cond_resched();
637 dir = shmem_dir_map(middir);
638 diroff = 0;
639 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700640 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700642 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
643 if (needs_lock) {
644 spin_lock(needs_lock);
645 dir[diroff] = NULL;
646 spin_unlock(needs_lock);
647 punch_lock = NULL;
648 } else
649 dir[diroff] = NULL;
650 nr_pages_to_free++;
651 list_add(&subdir->lru, &pages_to_free);
652 }
653 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654 size = limit - idx;
655 if (size > ENTRIES_PER_PAGE)
656 size = ENTRIES_PER_PAGE;
657 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700658 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 if (!dir)
660 dir = shmem_dir_map(middir);
661 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700662 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700664 set_page_private(subdir,
665 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700667 } else
668 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700669 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700670 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 }
672done1:
673 shmem_dir_unmap(dir);
674done2:
675 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
676 /*
677 * Call truncate_inode_pages again: racing shmem_unuse_inode
678 * may have swizzled a page in from swap since vmtruncate or
679 * generic_delete_inode did it, before we lowered next_index.
680 * Also, though shmem_getpage checks i_size before adding to
681 * cache, no recheck after: so fix the narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700682 *
683 * Recalling truncate_inode_pages_range and unmap_mapping_range
684 * every time for punch_hole (which never got a chance to clear
685 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
686 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800688 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700689 if (punch_hole)
690 unmap_mapping_range(inode->i_mapping, start,
691 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 }
693
694 spin_lock(&info->lock);
695 info->flags &= ~SHMEM_TRUNCATE;
696 info->swapped -= nr_swaps_freed;
697 if (nr_pages_to_free)
698 shmem_free_blocks(inode, nr_pages_to_free);
699 shmem_recalc_inode(inode);
700 spin_unlock(&info->lock);
701
702 /*
703 * Empty swap vector directory pages to be freed?
704 */
705 if (!list_empty(&pages_to_free)) {
706 pages_to_free.prev->next = NULL;
707 shmem_free_pages(pages_to_free.next);
708 }
709}
710
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800711static void shmem_truncate(struct inode *inode)
712{
713 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
714}
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
717{
718 struct inode *inode = dentry->d_inode;
719 struct page *page = NULL;
720 int error;
721
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700722 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700723 if (attr->ia_size < inode->i_size) {
724 /*
725 * If truncating down to a partial page, then
726 * if that page is already allocated, hold it
727 * in memory until the truncation is over, so
728 * truncate_partial_page cannnot miss it were
729 * it assigned to swap.
730 */
731 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
732 (void) shmem_getpage(inode,
733 attr->ia_size>>PAGE_CACHE_SHIFT,
734 &page, SGP_READ, NULL);
735 }
736 /*
737 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
738 * detect if any pages might have been added to cache
739 * after truncate_inode_pages. But we needn't bother
740 * if it's being fully truncated to zero-length: the
741 * nrpages check is efficient enough in that case.
742 */
743 if (attr->ia_size) {
744 struct shmem_inode_info *info = SHMEM_I(inode);
745 spin_lock(&info->lock);
746 info->flags &= ~SHMEM_PAGEIN;
747 spin_unlock(&info->lock);
748 }
749 }
750 }
751
752 error = inode_change_ok(inode, attr);
753 if (!error)
754 error = inode_setattr(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700755#ifdef CONFIG_TMPFS_POSIX_ACL
756 if (!error && (attr->ia_valid & ATTR_MODE))
757 error = generic_acl_chmod(inode, &shmem_acl_ops);
758#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 if (page)
760 page_cache_release(page);
761 return error;
762}
763
764static void shmem_delete_inode(struct inode *inode)
765{
766 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
767 struct shmem_inode_info *info = SHMEM_I(inode);
768
769 if (inode->i_op->truncate == shmem_truncate) {
Mark Fashehfef26652005-09-09 13:01:31 -0700770 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 shmem_unacct_size(info->flags, inode->i_size);
772 inode->i_size = 0;
773 shmem_truncate(inode);
774 if (!list_empty(&info->swaplist)) {
775 spin_lock(&shmem_swaplist_lock);
776 list_del_init(&info->swaplist);
777 spin_unlock(&shmem_swaplist_lock);
778 }
779 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700780 BUG_ON(inode->i_blocks);
781 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 spin_lock(&sbinfo->stat_lock);
783 sbinfo->free_inodes++;
784 spin_unlock(&sbinfo->stat_lock);
785 }
786 clear_inode(inode);
787}
788
789static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
790{
791 swp_entry_t *ptr;
792
793 for (ptr = dir; ptr < edir; ptr++) {
794 if (ptr->val == entry.val)
795 return ptr - dir;
796 }
797 return -1;
798}
799
800static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
801{
802 struct inode *inode;
803 unsigned long idx;
804 unsigned long size;
805 unsigned long limit;
806 unsigned long stage;
807 struct page **dir;
808 struct page *subdir;
809 swp_entry_t *ptr;
810 int offset;
811
812 idx = 0;
813 ptr = info->i_direct;
814 spin_lock(&info->lock);
815 limit = info->next_index;
816 size = limit;
817 if (size > SHMEM_NR_DIRECT)
818 size = SHMEM_NR_DIRECT;
819 offset = shmem_find_swp(entry, ptr, ptr+size);
820 if (offset >= 0) {
821 shmem_swp_balance_unmap();
822 goto found;
823 }
824 if (!info->i_indirect)
825 goto lost2;
826
827 dir = shmem_dir_map(info->i_indirect);
828 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
829
830 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
831 if (unlikely(idx == stage)) {
832 shmem_dir_unmap(dir-1);
833 dir = shmem_dir_map(info->i_indirect) +
834 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
835 while (!*dir) {
836 dir++;
837 idx += ENTRIES_PER_PAGEPAGE;
838 if (idx >= limit)
839 goto lost1;
840 }
841 stage = idx + ENTRIES_PER_PAGEPAGE;
842 subdir = *dir;
843 shmem_dir_unmap(dir);
844 dir = shmem_dir_map(subdir);
845 }
846 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700847 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848 ptr = shmem_swp_map(subdir);
849 size = limit - idx;
850 if (size > ENTRIES_PER_PAGE)
851 size = ENTRIES_PER_PAGE;
852 offset = shmem_find_swp(entry, ptr, ptr+size);
853 if (offset >= 0) {
854 shmem_dir_unmap(dir);
855 goto found;
856 }
857 shmem_swp_unmap(ptr);
858 }
859 }
860lost1:
861 shmem_dir_unmap(dir-1);
862lost2:
863 spin_unlock(&info->lock);
864 return 0;
865found:
866 idx += offset;
867 inode = &info->vfs_inode;
868 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
869 info->flags |= SHMEM_PAGEIN;
870 shmem_swp_set(info, ptr + offset, 0);
871 }
872 shmem_swp_unmap(ptr);
873 spin_unlock(&info->lock);
874 /*
875 * Decrement swap count even when the entry is left behind:
876 * try_to_unuse will skip over mms, then reincrement count.
877 */
878 swap_free(entry);
879 return 1;
880}
881
882/*
883 * shmem_unuse() search for an eventually swapped out shmem page.
884 */
885int shmem_unuse(swp_entry_t entry, struct page *page)
886{
887 struct list_head *p, *next;
888 struct shmem_inode_info *info;
889 int found = 0;
890
891 spin_lock(&shmem_swaplist_lock);
892 list_for_each_safe(p, next, &shmem_swaplist) {
893 info = list_entry(p, struct shmem_inode_info, swaplist);
894 if (!info->swapped)
895 list_del_init(&info->swaplist);
896 else if (shmem_unuse_inode(info, entry, page)) {
897 /* move head to start search for next from here */
898 list_move_tail(&shmem_swaplist, &info->swaplist);
899 found = 1;
900 break;
901 }
902 }
903 spin_unlock(&shmem_swaplist_lock);
904 return found;
905}
906
907/*
908 * Move the page from the page cache to the swap cache.
909 */
910static int shmem_writepage(struct page *page, struct writeback_control *wbc)
911{
912 struct shmem_inode_info *info;
913 swp_entry_t *entry, swap;
914 struct address_space *mapping;
915 unsigned long index;
916 struct inode *inode;
917
918 BUG_ON(!PageLocked(page));
919 BUG_ON(page_mapped(page));
920
921 mapping = page->mapping;
922 index = page->index;
923 inode = mapping->host;
924 info = SHMEM_I(inode);
925 if (info->flags & VM_LOCKED)
926 goto redirty;
927 swap = get_swap_page();
928 if (!swap.val)
929 goto redirty;
930
931 spin_lock(&info->lock);
932 shmem_recalc_inode(inode);
933 if (index >= info->next_index) {
934 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
935 goto unlock;
936 }
937 entry = shmem_swp_entry(info, index, NULL);
938 BUG_ON(!entry);
939 BUG_ON(entry->val);
940
941 if (move_to_swap_cache(page, swap) == 0) {
942 shmem_swp_set(info, entry, swap.val);
943 shmem_swp_unmap(entry);
944 spin_unlock(&info->lock);
945 if (list_empty(&info->swaplist)) {
946 spin_lock(&shmem_swaplist_lock);
947 /* move instead of add in case we're racing */
948 list_move_tail(&info->swaplist, &shmem_swaplist);
949 spin_unlock(&shmem_swaplist_lock);
950 }
951 unlock_page(page);
952 return 0;
953 }
954
955 shmem_swp_unmap(entry);
956unlock:
957 spin_unlock(&info->lock);
958 swap_free(swap);
959redirty:
960 set_page_dirty(page);
Zach Brown994fc28c2005-12-15 14:28:17 -0800961 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962}
963
964#ifdef CONFIG_NUMA
Hugh Dickinsd15c0232006-03-22 00:08:46 -0800965static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +0000966{
967 char *nodelist = strchr(value, ':');
968 int err = 1;
969
970 if (nodelist) {
971 /* NUL-terminate policy string */
972 *nodelist++ = '\0';
973 if (nodelist_parse(nodelist, *policy_nodes))
974 goto out;
Hugh Dickinsa2109062007-06-08 13:46:46 -0700975 if (!nodes_subset(*policy_nodes, node_online_map))
976 goto out;
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +0000977 }
978 if (!strcmp(value, "default")) {
979 *policy = MPOL_DEFAULT;
980 /* Don't allow a nodelist */
981 if (!nodelist)
982 err = 0;
983 } else if (!strcmp(value, "prefer")) {
984 *policy = MPOL_PREFERRED;
985 /* Insist on a nodelist of one node only */
986 if (nodelist) {
987 char *rest = nodelist;
988 while (isdigit(*rest))
989 rest++;
990 if (!*rest)
991 err = 0;
992 }
993 } else if (!strcmp(value, "bind")) {
994 *policy = MPOL_BIND;
995 /* Insist on a nodelist */
996 if (nodelist)
997 err = 0;
998 } else if (!strcmp(value, "interleave")) {
999 *policy = MPOL_INTERLEAVE;
1000 /* Default to nodes online if no nodelist */
1001 if (!nodelist)
1002 *policy_nodes = node_online_map;
1003 err = 0;
1004 }
1005out:
1006 /* Restore string for error message */
1007 if (nodelist)
1008 *--nodelist = ':';
1009 return err;
1010}
1011
Linus Torvalds1da177e2005-04-16 15:20:36 -07001012static struct page *shmem_swapin_async(struct shared_policy *p,
1013 swp_entry_t entry, unsigned long idx)
1014{
1015 struct page *page;
1016 struct vm_area_struct pvma;
1017
1018 /* Create a pseudo vma that just contains the policy */
1019 memset(&pvma, 0, sizeof(struct vm_area_struct));
1020 pvma.vm_end = PAGE_SIZE;
1021 pvma.vm_pgoff = idx;
1022 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
1023 page = read_swap_cache_async(entry, &pvma, 0);
1024 mpol_free(pvma.vm_policy);
1025 return page;
1026}
1027
1028struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
1029 unsigned long idx)
1030{
1031 struct shared_policy *p = &info->policy;
1032 int i, num;
1033 struct page *page;
1034 unsigned long offset;
1035
1036 num = valid_swaphandles(entry, &offset);
1037 for (i = 0; i < num; offset++, i++) {
1038 page = shmem_swapin_async(p,
1039 swp_entry(swp_type(entry), offset), idx);
1040 if (!page)
1041 break;
1042 page_cache_release(page);
1043 }
1044 lru_add_drain(); /* Push any new pages onto the LRU now */
1045 return shmem_swapin_async(p, entry, idx);
1046}
1047
1048static struct page *
Al Viro6daa0e22005-10-21 03:18:50 -04001049shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 unsigned long idx)
1051{
1052 struct vm_area_struct pvma;
1053 struct page *page;
1054
1055 memset(&pvma, 0, sizeof(struct vm_area_struct));
1056 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1057 pvma.vm_pgoff = idx;
1058 pvma.vm_end = PAGE_SIZE;
1059 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
1060 mpol_free(pvma.vm_policy);
1061 return page;
1062}
1063#else
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001064static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
1065{
1066 return 1;
1067}
1068
Linus Torvalds1da177e2005-04-16 15:20:36 -07001069static inline struct page *
1070shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
1071{
1072 swapin_readahead(entry, 0, NULL);
1073 return read_swap_cache_async(entry, NULL, 0);
1074}
1075
1076static inline struct page *
Al Virodd0fc662005-10-07 07:46:04 +01001077shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078{
1079 return alloc_page(gfp | __GFP_ZERO);
1080}
1081#endif
1082
1083/*
1084 * shmem_getpage - either get the page from swap or allocate a new one
1085 *
1086 * If we allocate a new one we do not mark it dirty. That's up to the
1087 * vm. If we swap it in we mark it dirty since we also free the swap
1088 * entry since a page cannot live in both the swap and page cache
1089 */
1090static int shmem_getpage(struct inode *inode, unsigned long idx,
1091 struct page **pagep, enum sgp_type sgp, int *type)
1092{
1093 struct address_space *mapping = inode->i_mapping;
1094 struct shmem_inode_info *info = SHMEM_I(inode);
1095 struct shmem_sb_info *sbinfo;
1096 struct page *filepage = *pagep;
1097 struct page *swappage;
1098 swp_entry_t *entry;
1099 swp_entry_t swap;
1100 int error;
1101
1102 if (idx >= SHMEM_MAX_INDEX)
1103 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001104
1105 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001106 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001107
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 /*
1109 * Normally, filepage is NULL on entry, and either found
1110 * uptodate immediately, or allocated and zeroed, or read
1111 * in under swappage, which is then assigned to filepage.
Hugh Dickinsae9764162007-06-04 10:00:39 +02001112 * But shmem_readpage and shmem_prepare_write pass in a locked
1113 * filepage, which may be found not uptodate by other callers
1114 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 */
1116repeat:
1117 if (!filepage)
1118 filepage = find_lock_page(mapping, idx);
1119 if (filepage && PageUptodate(filepage))
1120 goto done;
1121 error = 0;
1122 if (sgp == SGP_QUICK)
1123 goto failed;
1124
1125 spin_lock(&info->lock);
1126 shmem_recalc_inode(inode);
1127 entry = shmem_swp_alloc(info, idx, sgp);
1128 if (IS_ERR(entry)) {
1129 spin_unlock(&info->lock);
1130 error = PTR_ERR(entry);
1131 goto failed;
1132 }
1133 swap = *entry;
1134
1135 if (swap.val) {
1136 /* Look it up and read it in.. */
1137 swappage = lookup_swap_cache(swap);
1138 if (!swappage) {
1139 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001141 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001142 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001143 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001145 spin_unlock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001146 swappage = shmem_swapin(info, swap, idx);
1147 if (!swappage) {
1148 spin_lock(&info->lock);
1149 entry = shmem_swp_alloc(info, idx, sgp);
1150 if (IS_ERR(entry))
1151 error = PTR_ERR(entry);
1152 else {
1153 if (entry->val == swap.val)
1154 error = -ENOMEM;
1155 shmem_swp_unmap(entry);
1156 }
1157 spin_unlock(&info->lock);
1158 if (error)
1159 goto failed;
1160 goto repeat;
1161 }
1162 wait_on_page_locked(swappage);
1163 page_cache_release(swappage);
1164 goto repeat;
1165 }
1166
1167 /* We have to do this with page locked to prevent races */
1168 if (TestSetPageLocked(swappage)) {
1169 shmem_swp_unmap(entry);
1170 spin_unlock(&info->lock);
1171 wait_on_page_locked(swappage);
1172 page_cache_release(swappage);
1173 goto repeat;
1174 }
1175 if (PageWriteback(swappage)) {
1176 shmem_swp_unmap(entry);
1177 spin_unlock(&info->lock);
1178 wait_on_page_writeback(swappage);
1179 unlock_page(swappage);
1180 page_cache_release(swappage);
1181 goto repeat;
1182 }
1183 if (!PageUptodate(swappage)) {
1184 shmem_swp_unmap(entry);
1185 spin_unlock(&info->lock);
1186 unlock_page(swappage);
1187 page_cache_release(swappage);
1188 error = -EIO;
1189 goto failed;
1190 }
1191
1192 if (filepage) {
1193 shmem_swp_set(info, entry, 0);
1194 shmem_swp_unmap(entry);
1195 delete_from_swap_cache(swappage);
1196 spin_unlock(&info->lock);
1197 copy_highpage(filepage, swappage);
1198 unlock_page(swappage);
1199 page_cache_release(swappage);
1200 flush_dcache_page(filepage);
1201 SetPageUptodate(filepage);
1202 set_page_dirty(filepage);
1203 swap_free(swap);
1204 } else if (!(error = move_from_swap_cache(
1205 swappage, idx, mapping))) {
1206 info->flags |= SHMEM_PAGEIN;
1207 shmem_swp_set(info, entry, 0);
1208 shmem_swp_unmap(entry);
1209 spin_unlock(&info->lock);
1210 filepage = swappage;
1211 swap_free(swap);
1212 } else {
1213 shmem_swp_unmap(entry);
1214 spin_unlock(&info->lock);
1215 unlock_page(swappage);
1216 page_cache_release(swappage);
1217 if (error == -ENOMEM) {
1218 /* let kswapd refresh zone for GFP_ATOMICs */
Andrew Morton3fcfab12006-10-19 23:28:16 -07001219 congestion_wait(WRITE, HZ/50);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220 }
1221 goto repeat;
1222 }
1223 } else if (sgp == SGP_READ && !filepage) {
1224 shmem_swp_unmap(entry);
1225 filepage = find_get_page(mapping, idx);
1226 if (filepage &&
1227 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1228 spin_unlock(&info->lock);
1229 wait_on_page_locked(filepage);
1230 page_cache_release(filepage);
1231 filepage = NULL;
1232 goto repeat;
1233 }
1234 spin_unlock(&info->lock);
1235 } else {
1236 shmem_swp_unmap(entry);
1237 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001238 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001239 spin_lock(&sbinfo->stat_lock);
1240 if (sbinfo->free_blocks == 0 ||
1241 shmem_acct_block(info->flags)) {
1242 spin_unlock(&sbinfo->stat_lock);
1243 spin_unlock(&info->lock);
1244 error = -ENOSPC;
1245 goto failed;
1246 }
1247 sbinfo->free_blocks--;
1248 inode->i_blocks += BLOCKS_PER_PAGE;
1249 spin_unlock(&sbinfo->stat_lock);
1250 } else if (shmem_acct_block(info->flags)) {
1251 spin_unlock(&info->lock);
1252 error = -ENOSPC;
1253 goto failed;
1254 }
1255
1256 if (!filepage) {
1257 spin_unlock(&info->lock);
1258 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1259 info,
1260 idx);
1261 if (!filepage) {
1262 shmem_unacct_blocks(info->flags, 1);
1263 shmem_free_blocks(inode, 1);
1264 error = -ENOMEM;
1265 goto failed;
1266 }
1267
1268 spin_lock(&info->lock);
1269 entry = shmem_swp_alloc(info, idx, sgp);
1270 if (IS_ERR(entry))
1271 error = PTR_ERR(entry);
1272 else {
1273 swap = *entry;
1274 shmem_swp_unmap(entry);
1275 }
1276 if (error || swap.val || 0 != add_to_page_cache_lru(
1277 filepage, mapping, idx, GFP_ATOMIC)) {
1278 spin_unlock(&info->lock);
1279 page_cache_release(filepage);
1280 shmem_unacct_blocks(info->flags, 1);
1281 shmem_free_blocks(inode, 1);
1282 filepage = NULL;
1283 if (error)
1284 goto failed;
1285 goto repeat;
1286 }
1287 info->flags |= SHMEM_PAGEIN;
1288 }
1289
1290 info->alloced++;
1291 spin_unlock(&info->lock);
1292 flush_dcache_page(filepage);
1293 SetPageUptodate(filepage);
1294 }
1295done:
1296 if (*pagep != filepage) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 *pagep = filepage;
Nick Piggin54cb8822007-07-19 01:46:59 -07001298 if (sgp != SGP_FAULT)
Nick Piggind00806b2007-07-19 01:46:57 -07001299 unlock_page(filepage);
1300
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301 }
1302 return 0;
1303
1304failed:
1305 if (*pagep != filepage) {
1306 unlock_page(filepage);
1307 page_cache_release(filepage);
1308 }
1309 return error;
1310}
1311
Nick Piggind0217ac2007-07-19 01:47:03 -07001312static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001314 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001316 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317
Nick Piggind0217ac2007-07-19 01:47:03 -07001318 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1319 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001320
Nick Piggind0217ac2007-07-19 01:47:03 -07001321 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret);
1322 if (error)
1323 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324
Nick Piggind0217ac2007-07-19 01:47:03 -07001325 mark_page_accessed(vmf->page);
Nick Piggin83c54072007-07-19 01:47:05 -07001326 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001327}
1328
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329#ifdef CONFIG_NUMA
1330int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1331{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001332 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1334}
1335
1336struct mempolicy *
1337shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1338{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001339 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 unsigned long idx;
1341
1342 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1343 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1344}
1345#endif
1346
1347int shmem_lock(struct file *file, int lock, struct user_struct *user)
1348{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001349 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 struct shmem_inode_info *info = SHMEM_I(inode);
1351 int retval = -ENOMEM;
1352
1353 spin_lock(&info->lock);
1354 if (lock && !(info->flags & VM_LOCKED)) {
1355 if (!user_shm_lock(inode->i_size, user))
1356 goto out_nomem;
1357 info->flags |= VM_LOCKED;
1358 }
1359 if (!lock && (info->flags & VM_LOCKED) && user) {
1360 user_shm_unlock(inode->i_size, user);
1361 info->flags &= ~VM_LOCKED;
1362 }
1363 retval = 0;
1364out_nomem:
1365 spin_unlock(&info->lock);
1366 return retval;
1367}
1368
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001369static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370{
1371 file_accessed(file);
1372 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001373 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001374 return 0;
1375}
1376
1377static struct inode *
1378shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1379{
1380 struct inode *inode;
1381 struct shmem_inode_info *info;
1382 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1383
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001384 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 spin_lock(&sbinfo->stat_lock);
1386 if (!sbinfo->free_inodes) {
1387 spin_unlock(&sbinfo->stat_lock);
1388 return NULL;
1389 }
1390 sbinfo->free_inodes--;
1391 spin_unlock(&sbinfo->stat_lock);
1392 }
1393
1394 inode = new_inode(sb);
1395 if (inode) {
1396 inode->i_mode = mode;
1397 inode->i_uid = current->fsuid;
1398 inode->i_gid = current->fsgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 inode->i_blocks = 0;
1400 inode->i_mapping->a_ops = &shmem_aops;
1401 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1402 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001403 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 info = SHMEM_I(inode);
1405 memset(info, 0, (char *)inode - (char *)info);
1406 spin_lock_init(&info->lock);
1407 INIT_LIST_HEAD(&info->swaplist);
1408
1409 switch (mode & S_IFMT) {
1410 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001411 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 init_special_inode(inode, mode, dev);
1413 break;
1414 case S_IFREG:
1415 inode->i_op = &shmem_inode_operations;
1416 inode->i_fop = &shmem_file_operations;
Robin Holt7339ff82006-01-14 13:20:48 -08001417 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1418 &sbinfo->policy_nodes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 break;
1420 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001421 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001422 /* Some things misbehave if size == 0 on a directory */
1423 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1424 inode->i_op = &shmem_dir_inode_operations;
1425 inode->i_fop = &simple_dir_operations;
1426 break;
1427 case S_IFLNK:
1428 /*
1429 * Must not load anything in the rbtree,
1430 * mpol_free_shared_policy will not be called.
1431 */
Robin Holt7339ff82006-01-14 13:20:48 -08001432 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1433 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001434 break;
1435 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001436 } else if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 spin_lock(&sbinfo->stat_lock);
1438 sbinfo->free_inodes++;
1439 spin_unlock(&sbinfo->stat_lock);
1440 }
1441 return inode;
1442}
1443
1444#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001445static const struct inode_operations shmem_symlink_inode_operations;
1446static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447
1448/*
Hugh Dickinsae9764162007-06-04 10:00:39 +02001449 * Normally tmpfs avoids the use of shmem_readpage and shmem_prepare_write;
1450 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1451 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 */
Hugh Dickinsae9764162007-06-04 10:00:39 +02001453static int shmem_readpage(struct file *file, struct page *page)
1454{
1455 struct inode *inode = page->mapping->host;
1456 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1457 unlock_page(page);
1458 return error;
1459}
1460
Linus Torvalds1da177e2005-04-16 15:20:36 -07001461static int
1462shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1463{
1464 struct inode *inode = page->mapping->host;
1465 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1466}
1467
1468static ssize_t
1469shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1470{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001471 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001472 loff_t pos;
1473 unsigned long written;
1474 ssize_t err;
1475
1476 if ((ssize_t) count < 0)
1477 return -EINVAL;
1478
1479 if (!access_ok(VERIFY_READ, buf, count))
1480 return -EFAULT;
1481
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001482 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001483
1484 pos = *ppos;
1485 written = 0;
1486
1487 err = generic_write_checks(file, &pos, &count, 0);
1488 if (err || !count)
1489 goto out;
1490
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001491 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001492 if (err)
1493 goto out;
1494
1495 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1496
1497 do {
1498 struct page *page = NULL;
1499 unsigned long bytes, index, offset;
1500 char *kaddr;
1501 int left;
1502
1503 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1504 index = pos >> PAGE_CACHE_SHIFT;
1505 bytes = PAGE_CACHE_SIZE - offset;
1506 if (bytes > count)
1507 bytes = count;
1508
1509 /*
1510 * We don't hold page lock across copy from user -
1511 * what would it guard against? - so no deadlock here.
1512 * But it still may be a good idea to prefault below.
1513 */
1514
1515 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1516 if (err)
1517 break;
1518
1519 left = bytes;
1520 if (PageHighMem(page)) {
1521 volatile unsigned char dummy;
1522 __get_user(dummy, buf);
1523 __get_user(dummy, buf + bytes - 1);
1524
1525 kaddr = kmap_atomic(page, KM_USER0);
1526 left = __copy_from_user_inatomic(kaddr + offset,
1527 buf, bytes);
1528 kunmap_atomic(kaddr, KM_USER0);
1529 }
1530 if (left) {
1531 kaddr = kmap(page);
1532 left = __copy_from_user(kaddr + offset, buf, bytes);
1533 kunmap(page);
1534 }
1535
1536 written += bytes;
1537 count -= bytes;
1538 pos += bytes;
1539 buf += bytes;
1540 if (pos > inode->i_size)
1541 i_size_write(inode, pos);
1542
1543 flush_dcache_page(page);
1544 set_page_dirty(page);
1545 mark_page_accessed(page);
1546 page_cache_release(page);
1547
1548 if (left) {
1549 pos -= left;
1550 written -= left;
1551 err = -EFAULT;
1552 break;
1553 }
1554
1555 /*
1556 * Our dirty pages are not counted in nr_dirty,
1557 * and we do not attempt to balance dirty pages.
1558 */
1559
1560 cond_resched();
1561 } while (count);
1562
1563 *ppos = pos;
1564 if (written)
1565 err = written;
1566out:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001567 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 return err;
1569}
1570
1571static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1572{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001573 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 struct address_space *mapping = inode->i_mapping;
1575 unsigned long index, offset;
1576
1577 index = *ppos >> PAGE_CACHE_SHIFT;
1578 offset = *ppos & ~PAGE_CACHE_MASK;
1579
1580 for (;;) {
1581 struct page *page = NULL;
1582 unsigned long end_index, nr, ret;
1583 loff_t i_size = i_size_read(inode);
1584
1585 end_index = i_size >> PAGE_CACHE_SHIFT;
1586 if (index > end_index)
1587 break;
1588 if (index == end_index) {
1589 nr = i_size & ~PAGE_CACHE_MASK;
1590 if (nr <= offset)
1591 break;
1592 }
1593
1594 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1595 if (desc->error) {
1596 if (desc->error == -EINVAL)
1597 desc->error = 0;
1598 break;
1599 }
1600
1601 /*
1602 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001603 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 */
1605 nr = PAGE_CACHE_SIZE;
1606 i_size = i_size_read(inode);
1607 end_index = i_size >> PAGE_CACHE_SHIFT;
1608 if (index == end_index) {
1609 nr = i_size & ~PAGE_CACHE_MASK;
1610 if (nr <= offset) {
1611 if (page)
1612 page_cache_release(page);
1613 break;
1614 }
1615 }
1616 nr -= offset;
1617
1618 if (page) {
1619 /*
1620 * If users can be writing to this page using arbitrary
1621 * virtual addresses, take care about potential aliasing
1622 * before reading the page on the kernel side.
1623 */
1624 if (mapping_writably_mapped(mapping))
1625 flush_dcache_page(page);
1626 /*
1627 * Mark the page accessed if we read the beginning.
1628 */
1629 if (!offset)
1630 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001631 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001633 page_cache_get(page);
1634 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635
1636 /*
1637 * Ok, we have the page, and it's up-to-date, so
1638 * now we can copy it to user space...
1639 *
1640 * The actor routine returns how many bytes were actually used..
1641 * NOTE! This may not be the same as how much of a user buffer
1642 * we filled up (we may be padding etc), so we can only update
1643 * "pos" here (the actor routine has to update the user buffer
1644 * pointers and the remaining count).
1645 */
1646 ret = actor(desc, page, offset, nr);
1647 offset += ret;
1648 index += offset >> PAGE_CACHE_SHIFT;
1649 offset &= ~PAGE_CACHE_MASK;
1650
1651 page_cache_release(page);
1652 if (ret != nr || !desc->count)
1653 break;
1654
1655 cond_resched();
1656 }
1657
1658 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1659 file_accessed(filp);
1660}
1661
1662static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1663{
1664 read_descriptor_t desc;
1665
1666 if ((ssize_t) count < 0)
1667 return -EINVAL;
1668 if (!access_ok(VERIFY_WRITE, buf, count))
1669 return -EFAULT;
1670 if (!count)
1671 return 0;
1672
1673 desc.written = 0;
1674 desc.count = count;
1675 desc.arg.buf = buf;
1676 desc.error = 0;
1677
1678 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1679 if (desc.written)
1680 return desc.written;
1681 return desc.error;
1682}
1683
David Howells726c3342006-06-23 02:02:58 -07001684static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001685{
David Howells726c3342006-06-23 02:02:58 -07001686 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687
1688 buf->f_type = TMPFS_MAGIC;
1689 buf->f_bsize = PAGE_CACHE_SIZE;
1690 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001691 spin_lock(&sbinfo->stat_lock);
1692 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001693 buf->f_blocks = sbinfo->max_blocks;
1694 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001695 }
1696 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697 buf->f_files = sbinfo->max_inodes;
1698 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001699 }
1700 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001701 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001702 return 0;
1703}
1704
1705/*
1706 * File creation. Allocate an inode, and we're done..
1707 */
1708static int
1709shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1710{
1711 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1712 int error = -ENOSPC;
1713
1714 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001715 error = security_inode_init_security(inode, dir, NULL, NULL,
1716 NULL);
1717 if (error) {
1718 if (error != -EOPNOTSUPP) {
1719 iput(inode);
1720 return error;
1721 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001722 }
1723 error = shmem_acl_init(inode, dir);
1724 if (error) {
1725 iput(inode);
1726 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001727 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728 if (dir->i_mode & S_ISGID) {
1729 inode->i_gid = dir->i_gid;
1730 if (S_ISDIR(mode))
1731 inode->i_mode |= S_ISGID;
1732 }
1733 dir->i_size += BOGO_DIRENT_SIZE;
1734 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1735 d_instantiate(dentry, inode);
1736 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 }
1738 return error;
1739}
1740
1741static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1742{
1743 int error;
1744
1745 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1746 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001747 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748 return 0;
1749}
1750
1751static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1752 struct nameidata *nd)
1753{
1754 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1755}
1756
1757/*
1758 * Link a file..
1759 */
1760static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1761{
1762 struct inode *inode = old_dentry->d_inode;
1763 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1764
1765 /*
1766 * No ordinary (disk based) filesystem counts links as inodes;
1767 * but each new link needs a new dentry, pinning lowmem, and
1768 * tmpfs dentries cannot be pruned until they are unlinked.
1769 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001770 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 spin_lock(&sbinfo->stat_lock);
1772 if (!sbinfo->free_inodes) {
1773 spin_unlock(&sbinfo->stat_lock);
1774 return -ENOSPC;
1775 }
1776 sbinfo->free_inodes--;
1777 spin_unlock(&sbinfo->stat_lock);
1778 }
1779
1780 dir->i_size += BOGO_DIRENT_SIZE;
1781 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001782 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001783 atomic_inc(&inode->i_count); /* New dentry reference */
1784 dget(dentry); /* Extra pinning count for the created dentry */
1785 d_instantiate(dentry, inode);
1786 return 0;
1787}
1788
1789static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1790{
1791 struct inode *inode = dentry->d_inode;
1792
1793 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1794 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001795 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001796 spin_lock(&sbinfo->stat_lock);
1797 sbinfo->free_inodes++;
1798 spin_unlock(&sbinfo->stat_lock);
1799 }
1800 }
1801
1802 dir->i_size -= BOGO_DIRENT_SIZE;
1803 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001804 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001805 dput(dentry); /* Undo the count from "create" - this does all the work */
1806 return 0;
1807}
1808
1809static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1810{
1811 if (!simple_empty(dentry))
1812 return -ENOTEMPTY;
1813
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001814 drop_nlink(dentry->d_inode);
1815 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 return shmem_unlink(dir, dentry);
1817}
1818
1819/*
1820 * The VFS layer already does all the dentry stuff for rename,
1821 * we just have to decrement the usage count for the target if
1822 * it exists so that the VFS layer correctly free's it when it
1823 * gets overwritten.
1824 */
1825static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1826{
1827 struct inode *inode = old_dentry->d_inode;
1828 int they_are_dirs = S_ISDIR(inode->i_mode);
1829
1830 if (!simple_empty(new_dentry))
1831 return -ENOTEMPTY;
1832
1833 if (new_dentry->d_inode) {
1834 (void) shmem_unlink(new_dir, new_dentry);
1835 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001836 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001838 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001839 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840 }
1841
1842 old_dir->i_size -= BOGO_DIRENT_SIZE;
1843 new_dir->i_size += BOGO_DIRENT_SIZE;
1844 old_dir->i_ctime = old_dir->i_mtime =
1845 new_dir->i_ctime = new_dir->i_mtime =
1846 inode->i_ctime = CURRENT_TIME;
1847 return 0;
1848}
1849
1850static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1851{
1852 int error;
1853 int len;
1854 struct inode *inode;
1855 struct page *page = NULL;
1856 char *kaddr;
1857 struct shmem_inode_info *info;
1858
1859 len = strlen(symname) + 1;
1860 if (len > PAGE_CACHE_SIZE)
1861 return -ENAMETOOLONG;
1862
1863 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1864 if (!inode)
1865 return -ENOSPC;
1866
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001867 error = security_inode_init_security(inode, dir, NULL, NULL,
1868 NULL);
1869 if (error) {
1870 if (error != -EOPNOTSUPP) {
1871 iput(inode);
1872 return error;
1873 }
1874 error = 0;
1875 }
1876
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 info = SHMEM_I(inode);
1878 inode->i_size = len-1;
1879 if (len <= (char *)inode - (char *)info) {
1880 /* do it inline */
1881 memcpy(info, symname, len);
1882 inode->i_op = &shmem_symlink_inline_operations;
1883 } else {
1884 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1885 if (error) {
1886 iput(inode);
1887 return error;
1888 }
1889 inode->i_op = &shmem_symlink_inode_operations;
1890 kaddr = kmap_atomic(page, KM_USER0);
1891 memcpy(kaddr, symname, len);
1892 kunmap_atomic(kaddr, KM_USER0);
1893 set_page_dirty(page);
1894 page_cache_release(page);
1895 }
1896 if (dir->i_mode & S_ISGID)
1897 inode->i_gid = dir->i_gid;
1898 dir->i_size += BOGO_DIRENT_SIZE;
1899 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1900 d_instantiate(dentry, inode);
1901 dget(dentry);
1902 return 0;
1903}
1904
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001905static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906{
1907 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001908 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001909}
1910
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001911static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912{
1913 struct page *page = NULL;
1914 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1915 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001916 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917}
1918
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001919static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920{
1921 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001922 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 kunmap(page);
1924 mark_page_accessed(page);
1925 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926 }
1927}
1928
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001929static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930 .readlink = generic_readlink,
1931 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932};
1933
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001934static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001935 .truncate = shmem_truncate,
1936 .readlink = generic_readlink,
1937 .follow_link = shmem_follow_link,
1938 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939};
1940
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001941#ifdef CONFIG_TMPFS_POSIX_ACL
1942/**
1943 * Superblocks without xattr inode operations will get security.* xattr
1944 * support from the VFS "for free". As soon as we have any other xattrs
1945 * like ACLs, we also need to implement the security.* handlers at
1946 * filesystem level, though.
1947 */
1948
1949static size_t shmem_xattr_security_list(struct inode *inode, char *list,
1950 size_t list_len, const char *name,
1951 size_t name_len)
1952{
1953 return security_inode_listsecurity(inode, list, list_len);
1954}
1955
1956static int shmem_xattr_security_get(struct inode *inode, const char *name,
1957 void *buffer, size_t size)
1958{
1959 if (strcmp(name, "") == 0)
1960 return -EINVAL;
1961 return security_inode_getsecurity(inode, name, buffer, size,
1962 -EOPNOTSUPP);
1963}
1964
1965static int shmem_xattr_security_set(struct inode *inode, const char *name,
1966 const void *value, size_t size, int flags)
1967{
1968 if (strcmp(name, "") == 0)
1969 return -EINVAL;
1970 return security_inode_setsecurity(inode, name, value, size, flags);
1971}
1972
Adrian Bunk1f370a22006-12-06 20:38:21 -08001973static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001974 .prefix = XATTR_SECURITY_PREFIX,
1975 .list = shmem_xattr_security_list,
1976 .get = shmem_xattr_security_get,
1977 .set = shmem_xattr_security_set,
1978};
1979
1980static struct xattr_handler *shmem_xattr_handlers[] = {
1981 &shmem_xattr_acl_access_handler,
1982 &shmem_xattr_acl_default_handler,
1983 &shmem_xattr_security_handler,
1984 NULL
1985};
1986#endif
1987
David M. Grimes91828a42006-10-17 00:09:45 -07001988static struct dentry *shmem_get_parent(struct dentry *child)
1989{
1990 return ERR_PTR(-ESTALE);
1991}
1992
1993static int shmem_match(struct inode *ino, void *vfh)
1994{
1995 __u32 *fh = vfh;
1996 __u64 inum = fh[2];
1997 inum = (inum << 32) | fh[1];
1998 return ino->i_ino == inum && fh[0] == ino->i_generation;
1999}
2000
2001static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
2002{
2003 struct dentry *de = NULL;
2004 struct inode *inode;
2005 __u32 *fh = vfh;
2006 __u64 inum = fh[2];
2007 inum = (inum << 32) | fh[1];
2008
2009 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
2010 if (inode) {
2011 de = d_find_alias(inode);
2012 iput(inode);
2013 }
2014
2015 return de? de: ERR_PTR(-ESTALE);
2016}
2017
2018static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
2019 int len, int type,
2020 int (*acceptable)(void *context, struct dentry *de),
2021 void *context)
2022{
2023 if (len < 3)
2024 return ERR_PTR(-ESTALE);
2025
2026 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
2027 context);
2028}
2029
2030static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2031 int connectable)
2032{
2033 struct inode *inode = dentry->d_inode;
2034
2035 if (*len < 3)
2036 return 255;
2037
2038 if (hlist_unhashed(&inode->i_hash)) {
2039 /* Unfortunately insert_inode_hash is not idempotent,
2040 * so as we hash inodes here rather than at creation
2041 * time, we need a lock to ensure we only try
2042 * to do it once
2043 */
2044 static DEFINE_SPINLOCK(lock);
2045 spin_lock(&lock);
2046 if (hlist_unhashed(&inode->i_hash))
2047 __insert_inode_hash(inode,
2048 inode->i_ino + inode->i_generation);
2049 spin_unlock(&lock);
2050 }
2051
2052 fh[0] = inode->i_generation;
2053 fh[1] = inode->i_ino;
2054 fh[2] = ((__u64)inode->i_ino) >> 32;
2055
2056 *len = 3;
2057 return 1;
2058}
2059
2060static struct export_operations shmem_export_ops = {
2061 .get_parent = shmem_get_parent,
2062 .get_dentry = shmem_get_dentry,
2063 .encode_fh = shmem_encode_fh,
2064 .decode_fh = shmem_decode_fh,
2065};
2066
Robin Holt7339ff82006-01-14 13:20:48 -08002067static int shmem_parse_options(char *options, int *mode, uid_t *uid,
2068 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
2069 int *policy, nodemask_t *policy_nodes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070{
2071 char *this_char, *value, *rest;
2072
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002073 while (options != NULL) {
2074 this_char = options;
2075 for (;;) {
2076 /*
2077 * NUL-terminate this option: unfortunately,
2078 * mount options form a comma-separated list,
2079 * but mpol's nodelist may also contain commas.
2080 */
2081 options = strchr(options, ',');
2082 if (options == NULL)
2083 break;
2084 options++;
2085 if (!isdigit(*options)) {
2086 options[-1] = '\0';
2087 break;
2088 }
2089 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002090 if (!*this_char)
2091 continue;
2092 if ((value = strchr(this_char,'=')) != NULL) {
2093 *value++ = 0;
2094 } else {
2095 printk(KERN_ERR
2096 "tmpfs: No value for mount option '%s'\n",
2097 this_char);
2098 return 1;
2099 }
2100
2101 if (!strcmp(this_char,"size")) {
2102 unsigned long long size;
2103 size = memparse(value,&rest);
2104 if (*rest == '%') {
2105 size <<= PAGE_SHIFT;
2106 size *= totalram_pages;
2107 do_div(size, 100);
2108 rest++;
2109 }
2110 if (*rest)
2111 goto bad_val;
2112 *blocks = size >> PAGE_CACHE_SHIFT;
2113 } else if (!strcmp(this_char,"nr_blocks")) {
2114 *blocks = memparse(value,&rest);
2115 if (*rest)
2116 goto bad_val;
2117 } else if (!strcmp(this_char,"nr_inodes")) {
2118 *inodes = memparse(value,&rest);
2119 if (*rest)
2120 goto bad_val;
2121 } else if (!strcmp(this_char,"mode")) {
2122 if (!mode)
2123 continue;
2124 *mode = simple_strtoul(value,&rest,8);
2125 if (*rest)
2126 goto bad_val;
2127 } else if (!strcmp(this_char,"uid")) {
2128 if (!uid)
2129 continue;
2130 *uid = simple_strtoul(value,&rest,0);
2131 if (*rest)
2132 goto bad_val;
2133 } else if (!strcmp(this_char,"gid")) {
2134 if (!gid)
2135 continue;
2136 *gid = simple_strtoul(value,&rest,0);
2137 if (*rest)
2138 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002139 } else if (!strcmp(this_char,"mpol")) {
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002140 if (shmem_parse_mpol(value,policy,policy_nodes))
Robin Holt7339ff82006-01-14 13:20:48 -08002141 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142 } else {
2143 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2144 this_char);
2145 return 1;
2146 }
2147 }
2148 return 0;
2149
2150bad_val:
2151 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2152 value, this_char);
2153 return 1;
2154
2155}
2156
2157static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2158{
2159 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002160 unsigned long max_blocks = sbinfo->max_blocks;
2161 unsigned long max_inodes = sbinfo->max_inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002162 int policy = sbinfo->policy;
2163 nodemask_t policy_nodes = sbinfo->policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002164 unsigned long blocks;
2165 unsigned long inodes;
2166 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002167
Robin Holt7339ff82006-01-14 13:20:48 -08002168 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2169 &max_inodes, &policy, &policy_nodes))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002170 return error;
2171
2172 spin_lock(&sbinfo->stat_lock);
2173 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2174 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2175 if (max_blocks < blocks)
2176 goto out;
2177 if (max_inodes < inodes)
2178 goto out;
2179 /*
2180 * Those tests also disallow limited->unlimited while any are in
2181 * use, so i_blocks will always be zero when max_blocks is zero;
2182 * but we must separately disallow unlimited->limited, because
2183 * in that case we have no record of how much is already in use.
2184 */
2185 if (max_blocks && !sbinfo->max_blocks)
2186 goto out;
2187 if (max_inodes && !sbinfo->max_inodes)
2188 goto out;
2189
2190 error = 0;
2191 sbinfo->max_blocks = max_blocks;
2192 sbinfo->free_blocks = max_blocks - blocks;
2193 sbinfo->max_inodes = max_inodes;
2194 sbinfo->free_inodes = max_inodes - inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002195 sbinfo->policy = policy;
2196 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002197out:
2198 spin_unlock(&sbinfo->stat_lock);
2199 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002200}
2201#endif
2202
2203static void shmem_put_super(struct super_block *sb)
2204{
2205 kfree(sb->s_fs_info);
2206 sb->s_fs_info = NULL;
2207}
2208
Linus Torvalds1da177e2005-04-16 15:20:36 -07002209static int shmem_fill_super(struct super_block *sb,
2210 void *data, int silent)
2211{
2212 struct inode *inode;
2213 struct dentry *root;
2214 int mode = S_IRWXUGO | S_ISVTX;
2215 uid_t uid = current->fsuid;
2216 gid_t gid = current->fsgid;
2217 int err = -ENOMEM;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002218 struct shmem_sb_info *sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002219 unsigned long blocks = 0;
2220 unsigned long inodes = 0;
Robin Holt7339ff82006-01-14 13:20:48 -08002221 int policy = MPOL_DEFAULT;
2222 nodemask_t policy_nodes = node_online_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002224#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002225 /*
2226 * Per default we only allow half of the physical ram per
2227 * tmpfs instance, limiting inodes to one per page of lowmem;
2228 * but the internal instance is left unlimited.
2229 */
2230 if (!(sb->s_flags & MS_NOUSER)) {
2231 blocks = totalram_pages / 2;
2232 inodes = totalram_pages - totalhigh_pages;
2233 if (inodes > blocks)
2234 inodes = blocks;
Robin Holt7339ff82006-01-14 13:20:48 -08002235 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2236 &inodes, &policy, &policy_nodes))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002237 return -EINVAL;
2238 }
David M. Grimes91828a42006-10-17 00:09:45 -07002239 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002240#else
2241 sb->s_flags |= MS_NOUSER;
2242#endif
2243
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002244 /* Round up to L1_CACHE_BYTES to resist false sharing */
2245 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2246 L1_CACHE_BYTES), GFP_KERNEL);
2247 if (!sbinfo)
2248 return -ENOMEM;
2249
2250 spin_lock_init(&sbinfo->stat_lock);
2251 sbinfo->max_blocks = blocks;
2252 sbinfo->free_blocks = blocks;
2253 sbinfo->max_inodes = inodes;
2254 sbinfo->free_inodes = inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002255 sbinfo->policy = policy;
2256 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002257
2258 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002259 sb->s_maxbytes = SHMEM_MAX_BYTES;
2260 sb->s_blocksize = PAGE_CACHE_SIZE;
2261 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2262 sb->s_magic = TMPFS_MAGIC;
2263 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002264 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002265#ifdef CONFIG_TMPFS_POSIX_ACL
2266 sb->s_xattr = shmem_xattr_handlers;
2267 sb->s_flags |= MS_POSIXACL;
2268#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002269
Linus Torvalds1da177e2005-04-16 15:20:36 -07002270 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2271 if (!inode)
2272 goto failed;
2273 inode->i_uid = uid;
2274 inode->i_gid = gid;
2275 root = d_alloc_root(inode);
2276 if (!root)
2277 goto failed_iput;
2278 sb->s_root = root;
2279 return 0;
2280
2281failed_iput:
2282 iput(inode);
2283failed:
2284 shmem_put_super(sb);
2285 return err;
2286}
2287
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002288static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002289
2290static struct inode *shmem_alloc_inode(struct super_block *sb)
2291{
2292 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002293 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 if (!p)
2295 return NULL;
2296 return &p->vfs_inode;
2297}
2298
2299static void shmem_destroy_inode(struct inode *inode)
2300{
2301 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2302 /* only struct inode is valid if it's an inline symlink */
2303 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2304 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002305 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2307}
2308
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002309static void init_once(void *foo, struct kmem_cache *cachep,
2310 unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002311{
2312 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2313
Christoph Lametera35afb82007-05-16 22:10:57 -07002314 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002315#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002316 p->i_acl = NULL;
2317 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002318#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319}
2320
2321static int init_inodecache(void)
2322{
2323 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2324 sizeof(struct shmem_inode_info),
Paul Mundt20c2df82007-07-20 10:11:58 +09002325 0, 0, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 if (shmem_inode_cachep == NULL)
2327 return -ENOMEM;
2328 return 0;
2329}
2330
2331static void destroy_inodecache(void)
2332{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002333 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002334}
2335
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002336static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002338 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002339#ifdef CONFIG_TMPFS
Hugh Dickinsae9764162007-06-04 10:00:39 +02002340 .readpage = shmem_readpage,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002341 .prepare_write = shmem_prepare_write,
2342 .commit_write = simple_commit_write,
2343#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002344 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002345};
2346
Helge Deller15ad7cd2006-12-06 20:40:36 -08002347static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002348 .mmap = shmem_mmap,
2349#ifdef CONFIG_TMPFS
2350 .llseek = generic_file_llseek,
2351 .read = shmem_file_read,
2352 .write = shmem_file_write,
2353 .fsync = simple_sync_file,
Hugh Dickinsae9764162007-06-04 10:00:39 +02002354 .splice_read = generic_file_splice_read,
2355 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356#endif
2357};
2358
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002359static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002360 .truncate = shmem_truncate,
2361 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002362 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002363#ifdef CONFIG_TMPFS_POSIX_ACL
2364 .setxattr = generic_setxattr,
2365 .getxattr = generic_getxattr,
2366 .listxattr = generic_listxattr,
2367 .removexattr = generic_removexattr,
2368 .permission = shmem_permission,
2369#endif
2370
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371};
2372
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002373static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374#ifdef CONFIG_TMPFS
2375 .create = shmem_create,
2376 .lookup = simple_lookup,
2377 .link = shmem_link,
2378 .unlink = shmem_unlink,
2379 .symlink = shmem_symlink,
2380 .mkdir = shmem_mkdir,
2381 .rmdir = shmem_rmdir,
2382 .mknod = shmem_mknod,
2383 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002385#ifdef CONFIG_TMPFS_POSIX_ACL
2386 .setattr = shmem_notify_change,
2387 .setxattr = generic_setxattr,
2388 .getxattr = generic_getxattr,
2389 .listxattr = generic_listxattr,
2390 .removexattr = generic_removexattr,
2391 .permission = shmem_permission,
2392#endif
2393};
2394
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002395static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002396#ifdef CONFIG_TMPFS_POSIX_ACL
2397 .setattr = shmem_notify_change,
2398 .setxattr = generic_setxattr,
2399 .getxattr = generic_getxattr,
2400 .listxattr = generic_listxattr,
2401 .removexattr = generic_removexattr,
2402 .permission = shmem_permission,
2403#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002404};
2405
Hugh Dickins759b9772007-03-05 00:30:28 -08002406static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407 .alloc_inode = shmem_alloc_inode,
2408 .destroy_inode = shmem_destroy_inode,
2409#ifdef CONFIG_TMPFS
2410 .statfs = shmem_statfs,
2411 .remount_fs = shmem_remount_fs,
2412#endif
2413 .delete_inode = shmem_delete_inode,
2414 .drop_inode = generic_delete_inode,
2415 .put_super = shmem_put_super,
2416};
2417
2418static struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002419 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002420#ifdef CONFIG_NUMA
2421 .set_policy = shmem_set_policy,
2422 .get_policy = shmem_get_policy,
2423#endif
2424};
2425
2426
David Howells454e2392006-06-23 02:02:57 -07002427static int shmem_get_sb(struct file_system_type *fs_type,
2428 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429{
David Howells454e2392006-06-23 02:02:57 -07002430 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002431}
2432
2433static struct file_system_type tmpfs_fs_type = {
2434 .owner = THIS_MODULE,
2435 .name = "tmpfs",
2436 .get_sb = shmem_get_sb,
2437 .kill_sb = kill_litter_super,
2438};
2439static struct vfsmount *shm_mnt;
2440
2441static int __init init_tmpfs(void)
2442{
2443 int error;
2444
2445 error = init_inodecache();
2446 if (error)
2447 goto out3;
2448
2449 error = register_filesystem(&tmpfs_fs_type);
2450 if (error) {
2451 printk(KERN_ERR "Could not register tmpfs\n");
2452 goto out2;
2453 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002454
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002455 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002456 tmpfs_fs_type.name, NULL);
2457 if (IS_ERR(shm_mnt)) {
2458 error = PTR_ERR(shm_mnt);
2459 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2460 goto out1;
2461 }
2462 return 0;
2463
2464out1:
2465 unregister_filesystem(&tmpfs_fs_type);
2466out2:
2467 destroy_inodecache();
2468out3:
2469 shm_mnt = ERR_PTR(error);
2470 return error;
2471}
2472module_init(init_tmpfs)
2473
2474/*
2475 * shmem_file_setup - get an unlinked file living in tmpfs
2476 *
2477 * @name: name for dentry (to be seen in /proc/<pid>/maps
2478 * @size: size to be set for the file
2479 *
2480 */
2481struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2482{
2483 int error;
2484 struct file *file;
2485 struct inode *inode;
2486 struct dentry *dentry, *root;
2487 struct qstr this;
2488
2489 if (IS_ERR(shm_mnt))
2490 return (void *)shm_mnt;
2491
2492 if (size < 0 || size > SHMEM_MAX_BYTES)
2493 return ERR_PTR(-EINVAL);
2494
2495 if (shmem_acct_size(flags, size))
2496 return ERR_PTR(-ENOMEM);
2497
2498 error = -ENOMEM;
2499 this.name = name;
2500 this.len = strlen(name);
2501 this.hash = 0; /* will go */
2502 root = shm_mnt->mnt_root;
2503 dentry = d_alloc(root, &this);
2504 if (!dentry)
2505 goto put_memory;
2506
2507 error = -ENFILE;
2508 file = get_empty_filp();
2509 if (!file)
2510 goto put_dentry;
2511
2512 error = -ENOSPC;
2513 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2514 if (!inode)
2515 goto close_file;
2516
2517 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2518 d_instantiate(dentry, inode);
2519 inode->i_size = size;
2520 inode->i_nlink = 0; /* It is unlinked */
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002521 file->f_path.mnt = mntget(shm_mnt);
2522 file->f_path.dentry = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 file->f_mapping = inode->i_mapping;
2524 file->f_op = &shmem_file_operations;
2525 file->f_mode = FMODE_WRITE | FMODE_READ;
2526 return file;
2527
2528close_file:
2529 put_filp(file);
2530put_dentry:
2531 dput(dentry);
2532put_memory:
2533 shmem_unacct_size(flags, size);
2534 return ERR_PTR(error);
2535}
2536
2537/*
2538 * shmem_zero_setup - setup a shared anonymous mapping
2539 *
2540 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2541 */
2542int shmem_zero_setup(struct vm_area_struct *vma)
2543{
2544 struct file *file;
2545 loff_t size = vma->vm_end - vma->vm_start;
2546
2547 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2548 if (IS_ERR(file))
2549 return PTR_ERR(file);
2550
2551 if (vma->vm_file)
2552 fput(vma->vm_file);
2553 vma->vm_file = file;
2554 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555 return 0;
2556}