blob: f514dd392cd93570e108ba5a489a28975d85034a [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>
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080052#include <linux/seq_file.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 {
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 SGP_READ, /* don't exceed i_size, don't allocate page */
83 SGP_CACHE, /* don't exceed i_size, may allocate page */
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -080084 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
Linus Torvalds1da177e2005-04-16 15:20:36 -070085 SGP_WRITE, /* may exceed i_size, may allocate page */
86};
87
Andrew Mortonb76db732008-02-08 04:21:49 -080088#ifdef CONFIG_TMPFS
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080089static unsigned long shmem_default_max_blocks(void)
90{
91 return totalram_pages / 2;
92}
93
94static unsigned long shmem_default_max_inodes(void)
95{
96 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
97}
Andrew Mortonb76db732008-02-08 04:21:49 -080098#endif
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080099
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100static int shmem_getpage(struct inode *inode, unsigned long idx,
101 struct page **pagep, enum sgp_type sgp, int *type);
102
Al Viro6daa0e22005-10-21 03:18:50 -0400103static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104{
105 /*
106 * The above definition of ENTRIES_PER_PAGE, and the use of
107 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
108 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -0700109 *
Mel Gormane12ba742007-10-16 01:25:52 -0700110 * Mobility flags are masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 */
Mel Gormane12ba742007-10-16 01:25:52 -0700112 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
Mel Gorman769848c2007-07-17 04:03:05 -0700113 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114}
115
116static inline void shmem_dir_free(struct page *page)
117{
118 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
119}
120
121static struct page **shmem_dir_map(struct page *page)
122{
123 return (struct page **)kmap_atomic(page, KM_USER0);
124}
125
126static inline void shmem_dir_unmap(struct page **dir)
127{
128 kunmap_atomic(dir, KM_USER0);
129}
130
131static swp_entry_t *shmem_swp_map(struct page *page)
132{
133 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
134}
135
136static inline void shmem_swp_balance_unmap(void)
137{
138 /*
139 * When passing a pointer to an i_direct entry, to code which
140 * also handles indirect entries and so will shmem_swp_unmap,
141 * we must arrange for the preempt count to remain in balance.
142 * What kmap_atomic of a lowmem page does depends on config
143 * and architecture, so pretend to kmap_atomic some lowmem page.
144 */
145 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
146}
147
148static inline void shmem_swp_unmap(swp_entry_t *entry)
149{
150 kunmap_atomic(entry, KM_USER1);
151}
152
153static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
154{
155 return sb->s_fs_info;
156}
157
158/*
159 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
160 * for shared memory and for shared anonymous (/dev/zero) mappings
161 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
162 * consistent with the pre-accounting of private mappings ...
163 */
164static inline int shmem_acct_size(unsigned long flags, loff_t size)
165{
166 return (flags & VM_ACCOUNT)?
167 security_vm_enough_memory(VM_ACCT(size)): 0;
168}
169
170static inline void shmem_unacct_size(unsigned long flags, loff_t size)
171{
172 if (flags & VM_ACCOUNT)
173 vm_unacct_memory(VM_ACCT(size));
174}
175
176/*
177 * ... whereas tmpfs objects are accounted incrementally as
178 * pages are allocated, in order to allow huge sparse files.
179 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
180 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
181 */
182static inline int shmem_acct_block(unsigned long flags)
183{
184 return (flags & VM_ACCOUNT)?
185 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
186}
187
188static inline void shmem_unacct_blocks(unsigned long flags, long pages)
189{
190 if (!(flags & VM_ACCOUNT))
191 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
192}
193
Hugh Dickins759b9772007-03-05 00:30:28 -0800194static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700195static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800196static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800197static const struct inode_operations shmem_inode_operations;
198static const struct inode_operations shmem_dir_inode_operations;
199static const struct inode_operations shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200static struct vm_operations_struct shmem_vm_ops;
201
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700202static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 .ra_pages = 0, /* No readahead */
204 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
205 .unplug_io_fn = default_unplug_io_fn,
206};
207
208static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800209static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210
211static void shmem_free_blocks(struct inode *inode, long pages)
212{
213 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700214 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 spin_lock(&sbinfo->stat_lock);
216 sbinfo->free_blocks += pages;
217 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
218 spin_unlock(&sbinfo->stat_lock);
219 }
220}
221
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800222static int shmem_reserve_inode(struct super_block *sb)
223{
224 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
225 if (sbinfo->max_inodes) {
226 spin_lock(&sbinfo->stat_lock);
227 if (!sbinfo->free_inodes) {
228 spin_unlock(&sbinfo->stat_lock);
229 return -ENOSPC;
230 }
231 sbinfo->free_inodes--;
232 spin_unlock(&sbinfo->stat_lock);
233 }
234 return 0;
235}
236
237static void shmem_free_inode(struct super_block *sb)
238{
239 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
240 if (sbinfo->max_inodes) {
241 spin_lock(&sbinfo->stat_lock);
242 sbinfo->free_inodes++;
243 spin_unlock(&sbinfo->stat_lock);
244 }
245}
246
Randy Dunlap46711812008-03-19 17:00:41 -0700247/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 * @inode: inode to recalc
250 *
251 * We have to calculate the free blocks since the mm can drop
252 * undirtied hole pages behind our back.
253 *
254 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
255 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
256 *
257 * It has to be called with the spinlock held.
258 */
259static void shmem_recalc_inode(struct inode *inode)
260{
261 struct shmem_inode_info *info = SHMEM_I(inode);
262 long freed;
263
264 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
265 if (freed > 0) {
266 info->alloced -= freed;
267 shmem_unacct_blocks(info->flags, freed);
268 shmem_free_blocks(inode, freed);
269 }
270}
271
Randy Dunlap46711812008-03-19 17:00:41 -0700272/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 * @info: info structure for the inode
275 * @index: index of the page to find
276 * @page: optional page to add to the structure. Has to be preset to
277 * all zeros
278 *
279 * If there is no space allocated yet it will return NULL when
280 * page is NULL, else it will use the page for the needed block,
281 * setting it to NULL on return to indicate that it has been used.
282 *
283 * The swap vector is organized the following way:
284 *
285 * There are SHMEM_NR_DIRECT entries directly stored in the
286 * shmem_inode_info structure. So small files do not need an addional
287 * allocation.
288 *
289 * For pages with index > SHMEM_NR_DIRECT there is the pointer
290 * i_indirect which points to a page which holds in the first half
291 * doubly indirect blocks, in the second half triple indirect blocks:
292 *
293 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
294 * following layout (for SHMEM_NR_DIRECT == 16):
295 *
296 * i_indirect -> dir --> 16-19
297 * | +-> 20-23
298 * |
299 * +-->dir2 --> 24-27
300 * | +-> 28-31
301 * | +-> 32-35
302 * | +-> 36-39
303 * |
304 * +-->dir3 --> 40-43
305 * +-> 44-47
306 * +-> 48-51
307 * +-> 52-55
308 */
309static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
310{
311 unsigned long offset;
312 struct page **dir;
313 struct page *subdir;
314
315 if (index < SHMEM_NR_DIRECT) {
316 shmem_swp_balance_unmap();
317 return info->i_direct+index;
318 }
319 if (!info->i_indirect) {
320 if (page) {
321 info->i_indirect = *page;
322 *page = NULL;
323 }
324 return NULL; /* need another page */
325 }
326
327 index -= SHMEM_NR_DIRECT;
328 offset = index % ENTRIES_PER_PAGE;
329 index /= ENTRIES_PER_PAGE;
330 dir = shmem_dir_map(info->i_indirect);
331
332 if (index >= ENTRIES_PER_PAGE/2) {
333 index -= ENTRIES_PER_PAGE/2;
334 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
335 index %= ENTRIES_PER_PAGE;
336 subdir = *dir;
337 if (!subdir) {
338 if (page) {
339 *dir = *page;
340 *page = NULL;
341 }
342 shmem_dir_unmap(dir);
343 return NULL; /* need another page */
344 }
345 shmem_dir_unmap(dir);
346 dir = shmem_dir_map(subdir);
347 }
348
349 dir += index;
350 subdir = *dir;
351 if (!subdir) {
352 if (!page || !(subdir = *page)) {
353 shmem_dir_unmap(dir);
354 return NULL; /* need a page */
355 }
356 *dir = subdir;
357 *page = NULL;
358 }
359 shmem_dir_unmap(dir);
360 return shmem_swp_map(subdir) + offset;
361}
362
363static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
364{
365 long incdec = value? 1: -1;
366
367 entry->val = value;
368 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700369 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
370 struct page *page = kmap_atomic_to_page(entry);
371 set_page_private(page, page_private(page) + incdec);
372 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373}
374
Randy Dunlap46711812008-03-19 17:00:41 -0700375/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700377 * @info: info structure for the inode
378 * @index: index of the page to find
379 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700380 *
381 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 */
383static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
384{
385 struct inode *inode = &info->vfs_inode;
386 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
387 struct page *page = NULL;
388 swp_entry_t *entry;
389
390 if (sgp != SGP_WRITE &&
391 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
392 return ERR_PTR(-EINVAL);
393
394 while (!(entry = shmem_swp_entry(info, index, &page))) {
395 if (sgp == SGP_READ)
396 return shmem_swp_map(ZERO_PAGE(0));
397 /*
398 * Test free_blocks against 1 not 0, since we have 1 data
399 * page (and perhaps indirect index pages) yet to allocate:
400 * a waste to allocate index if we cannot allocate data.
401 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700402 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 spin_lock(&sbinfo->stat_lock);
404 if (sbinfo->free_blocks <= 1) {
405 spin_unlock(&sbinfo->stat_lock);
406 return ERR_PTR(-ENOSPC);
407 }
408 sbinfo->free_blocks--;
409 inode->i_blocks += BLOCKS_PER_PAGE;
410 spin_unlock(&sbinfo->stat_lock);
411 }
412
413 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700414 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700415 if (page)
416 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 spin_lock(&info->lock);
418
419 if (!page) {
420 shmem_free_blocks(inode, 1);
421 return ERR_PTR(-ENOMEM);
422 }
423 if (sgp != SGP_WRITE &&
424 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
425 entry = ERR_PTR(-EINVAL);
426 break;
427 }
428 if (info->next_index <= index)
429 info->next_index = index + 1;
430 }
431 if (page) {
432 /* another task gave its page, or truncated the file */
433 shmem_free_blocks(inode, 1);
434 shmem_dir_free(page);
435 }
436 if (info->next_index <= index && !IS_ERR(entry))
437 info->next_index = index + 1;
438 return entry;
439}
440
Randy Dunlap46711812008-03-19 17:00:41 -0700441/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 * shmem_free_swp - free some swap entries in a directory
Hugh Dickins1ae70002007-03-29 01:20:36 -0700443 * @dir: pointer to the directory
444 * @edir: pointer after last entry of the directory
445 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700447static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
448 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700450 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 swp_entry_t *ptr;
452 int freed = 0;
453
454 for (ptr = dir; ptr < edir; ptr++) {
455 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700456 if (unlikely(punch_lock)) {
457 punch_unlock = punch_lock;
458 punch_lock = NULL;
459 spin_lock(punch_unlock);
460 if (!ptr->val)
461 continue;
462 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 free_swap_and_cache(*ptr);
464 *ptr = (swp_entry_t){0};
465 freed++;
466 }
467 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700468 if (punch_unlock)
469 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 return freed;
471}
472
Hugh Dickins1ae70002007-03-29 01:20:36 -0700473static int shmem_map_and_free_swp(struct page *subdir, int offset,
474 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475{
476 swp_entry_t *ptr;
477 int freed = 0;
478
479 ptr = shmem_swp_map(subdir);
480 for (; offset < limit; offset += LATENCY_LIMIT) {
481 int size = limit - offset;
482 if (size > LATENCY_LIMIT)
483 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700484 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
485 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 if (need_resched()) {
487 shmem_swp_unmap(ptr);
488 if (*dir) {
489 shmem_dir_unmap(*dir);
490 *dir = NULL;
491 }
492 cond_resched();
493 ptr = shmem_swp_map(subdir);
494 }
495 }
496 shmem_swp_unmap(ptr);
497 return freed;
498}
499
500static void shmem_free_pages(struct list_head *next)
501{
502 struct page *page;
503 int freed = 0;
504
505 do {
506 page = container_of(next, struct page, lru);
507 next = next->next;
508 shmem_dir_free(page);
509 freed++;
510 if (freed >= LATENCY_LIMIT) {
511 cond_resched();
512 freed = 0;
513 }
514 } while (next);
515}
516
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800517static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518{
519 struct shmem_inode_info *info = SHMEM_I(inode);
520 unsigned long idx;
521 unsigned long size;
522 unsigned long limit;
523 unsigned long stage;
524 unsigned long diroff;
525 struct page **dir;
526 struct page *topdir;
527 struct page *middir;
528 struct page *subdir;
529 swp_entry_t *ptr;
530 LIST_HEAD(pages_to_free);
531 long nr_pages_to_free = 0;
532 long nr_swaps_freed = 0;
533 int offset;
534 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700535 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700536 spinlock_t *needs_lock;
537 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700538 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539
540 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800541 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700542 if (idx >= info->next_index)
543 return;
544
545 spin_lock(&info->lock);
546 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800547 if (likely(end == (loff_t) -1)) {
548 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700549 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800550 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700551 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700552 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800553 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700554 if (end + 1 >= inode->i_size) { /* we may free a little more */
555 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
556 PAGE_CACHE_SHIFT;
557 upper_limit = SHMEM_MAX_INDEX;
558 } else {
559 limit = (end + 1) >> PAGE_CACHE_SHIFT;
560 upper_limit = limit;
561 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700562 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800563 punch_hole = 1;
564 }
565
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800567 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 info->i_indirect = NULL;
569 nr_pages_to_free++;
570 list_add(&topdir->lru, &pages_to_free);
571 }
572 spin_unlock(&info->lock);
573
574 if (info->swapped && idx < SHMEM_NR_DIRECT) {
575 ptr = info->i_direct;
576 size = limit;
577 if (size > SHMEM_NR_DIRECT)
578 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700579 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800581
582 /*
583 * If there are no indirect blocks or we are punching a hole
584 * below indirect blocks, nothing to be done.
585 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700586 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 goto done2;
588
Hugh Dickins1ae70002007-03-29 01:20:36 -0700589 /*
590 * The truncation case has already dropped info->lock, and we're safe
591 * because i_size and next_index have already been lowered, preventing
592 * access beyond. But in the punch_hole case, we still need to take
593 * the lock when updating the swap directory, because there might be
594 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
595 * shmem_writepage. However, whenever we find we can remove a whole
596 * directory page (not at the misaligned start or end of the range),
597 * we first NULLify its pointer in the level above, and then have no
598 * need to take the lock when updating its contents: needs_lock and
599 * punch_lock (either pointing to info->lock or NULL) manage this.
600 */
601
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700602 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 limit -= SHMEM_NR_DIRECT;
604 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
605 offset = idx % ENTRIES_PER_PAGE;
606 idx -= offset;
607
608 dir = shmem_dir_map(topdir);
609 stage = ENTRIES_PER_PAGEPAGE/2;
610 if (idx < ENTRIES_PER_PAGEPAGE/2) {
611 middir = topdir;
612 diroff = idx/ENTRIES_PER_PAGE;
613 } else {
614 dir += ENTRIES_PER_PAGE/2;
615 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
616 while (stage <= idx)
617 stage += ENTRIES_PER_PAGEPAGE;
618 middir = *dir;
619 if (*dir) {
620 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
621 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700622 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700623 if (needs_lock) {
624 spin_lock(needs_lock);
625 *dir = NULL;
626 spin_unlock(needs_lock);
627 needs_lock = NULL;
628 } else
629 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700630 nr_pages_to_free++;
631 list_add(&middir->lru, &pages_to_free);
632 }
633 shmem_dir_unmap(dir);
634 dir = shmem_dir_map(middir);
635 } else {
636 diroff = 0;
637 offset = 0;
638 idx = stage;
639 }
640 }
641
642 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
643 if (unlikely(idx == stage)) {
644 shmem_dir_unmap(dir);
645 dir = shmem_dir_map(topdir) +
646 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
647 while (!*dir) {
648 dir++;
649 idx += ENTRIES_PER_PAGEPAGE;
650 if (idx >= limit)
651 goto done1;
652 }
653 stage = idx + ENTRIES_PER_PAGEPAGE;
654 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700655 if (punch_hole)
656 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700657 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700658 if (needs_lock) {
659 spin_lock(needs_lock);
660 *dir = NULL;
661 spin_unlock(needs_lock);
662 needs_lock = NULL;
663 } else
664 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700665 nr_pages_to_free++;
666 list_add(&middir->lru, &pages_to_free);
667 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 shmem_dir_unmap(dir);
669 cond_resched();
670 dir = shmem_dir_map(middir);
671 diroff = 0;
672 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700673 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700675 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
676 if (needs_lock) {
677 spin_lock(needs_lock);
678 dir[diroff] = NULL;
679 spin_unlock(needs_lock);
680 punch_lock = NULL;
681 } else
682 dir[diroff] = NULL;
683 nr_pages_to_free++;
684 list_add(&subdir->lru, &pages_to_free);
685 }
686 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 size = limit - idx;
688 if (size > ENTRIES_PER_PAGE)
689 size = ENTRIES_PER_PAGE;
690 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700691 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 if (!dir)
693 dir = shmem_dir_map(middir);
694 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700695 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700697 set_page_private(subdir,
698 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700700 } else
701 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700703 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704 }
705done1:
706 shmem_dir_unmap(dir);
707done2:
708 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
709 /*
710 * Call truncate_inode_pages again: racing shmem_unuse_inode
711 * may have swizzled a page in from swap since vmtruncate or
712 * generic_delete_inode did it, before we lowered next_index.
713 * Also, though shmem_getpage checks i_size before adding to
714 * cache, no recheck after: so fix the narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700715 *
716 * Recalling truncate_inode_pages_range and unmap_mapping_range
717 * every time for punch_hole (which never got a chance to clear
718 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
719 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800721 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700722 if (punch_hole)
723 unmap_mapping_range(inode->i_mapping, start,
724 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 }
726
727 spin_lock(&info->lock);
728 info->flags &= ~SHMEM_TRUNCATE;
729 info->swapped -= nr_swaps_freed;
730 if (nr_pages_to_free)
731 shmem_free_blocks(inode, nr_pages_to_free);
732 shmem_recalc_inode(inode);
733 spin_unlock(&info->lock);
734
735 /*
736 * Empty swap vector directory pages to be freed?
737 */
738 if (!list_empty(&pages_to_free)) {
739 pages_to_free.prev->next = NULL;
740 shmem_free_pages(pages_to_free.next);
741 }
742}
743
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800744static void shmem_truncate(struct inode *inode)
745{
746 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
747}
748
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
750{
751 struct inode *inode = dentry->d_inode;
752 struct page *page = NULL;
753 int error;
754
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700755 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 if (attr->ia_size < inode->i_size) {
757 /*
758 * If truncating down to a partial page, then
759 * if that page is already allocated, hold it
760 * in memory until the truncation is over, so
761 * truncate_partial_page cannnot miss it were
762 * it assigned to swap.
763 */
764 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
765 (void) shmem_getpage(inode,
766 attr->ia_size>>PAGE_CACHE_SHIFT,
767 &page, SGP_READ, NULL);
Hugh Dickinsd3602442008-02-04 22:28:44 -0800768 if (page)
769 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 }
771 /*
772 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
773 * detect if any pages might have been added to cache
774 * after truncate_inode_pages. But we needn't bother
775 * if it's being fully truncated to zero-length: the
776 * nrpages check is efficient enough in that case.
777 */
778 if (attr->ia_size) {
779 struct shmem_inode_info *info = SHMEM_I(inode);
780 spin_lock(&info->lock);
781 info->flags &= ~SHMEM_PAGEIN;
782 spin_unlock(&info->lock);
783 }
784 }
785 }
786
787 error = inode_change_ok(inode, attr);
788 if (!error)
789 error = inode_setattr(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700790#ifdef CONFIG_TMPFS_POSIX_ACL
791 if (!error && (attr->ia_valid & ATTR_MODE))
792 error = generic_acl_chmod(inode, &shmem_acl_ops);
793#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 if (page)
795 page_cache_release(page);
796 return error;
797}
798
799static void shmem_delete_inode(struct inode *inode)
800{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 struct shmem_inode_info *info = SHMEM_I(inode);
802
803 if (inode->i_op->truncate == shmem_truncate) {
Mark Fashehfef26652005-09-09 13:01:31 -0700804 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700805 shmem_unacct_size(info->flags, inode->i_size);
806 inode->i_size = 0;
807 shmem_truncate(inode);
808 if (!list_empty(&info->swaplist)) {
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800809 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 list_del_init(&info->swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800811 mutex_unlock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 }
813 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700814 BUG_ON(inode->i_blocks);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800815 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 clear_inode(inode);
817}
818
819static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
820{
821 swp_entry_t *ptr;
822
823 for (ptr = dir; ptr < edir; ptr++) {
824 if (ptr->val == entry.val)
825 return ptr - dir;
826 }
827 return -1;
828}
829
830static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
831{
832 struct inode *inode;
833 unsigned long idx;
834 unsigned long size;
835 unsigned long limit;
836 unsigned long stage;
837 struct page **dir;
838 struct page *subdir;
839 swp_entry_t *ptr;
840 int offset;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800841 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
843 idx = 0;
844 ptr = info->i_direct;
845 spin_lock(&info->lock);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800846 if (!info->swapped) {
847 list_del_init(&info->swaplist);
848 goto lost2;
849 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700850 limit = info->next_index;
851 size = limit;
852 if (size > SHMEM_NR_DIRECT)
853 size = SHMEM_NR_DIRECT;
854 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800855 if (offset >= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 goto found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857 if (!info->i_indirect)
858 goto lost2;
859
860 dir = shmem_dir_map(info->i_indirect);
861 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
862
863 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
864 if (unlikely(idx == stage)) {
865 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800866 if (cond_resched_lock(&info->lock)) {
867 /* check it has not been truncated */
868 if (limit > info->next_index) {
869 limit = info->next_index;
870 if (idx >= limit)
871 goto lost2;
872 }
873 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 dir = shmem_dir_map(info->i_indirect) +
875 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
876 while (!*dir) {
877 dir++;
878 idx += ENTRIES_PER_PAGEPAGE;
879 if (idx >= limit)
880 goto lost1;
881 }
882 stage = idx + ENTRIES_PER_PAGEPAGE;
883 subdir = *dir;
884 shmem_dir_unmap(dir);
885 dir = shmem_dir_map(subdir);
886 }
887 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700888 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 ptr = shmem_swp_map(subdir);
890 size = limit - idx;
891 if (size > ENTRIES_PER_PAGE)
892 size = ENTRIES_PER_PAGE;
893 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800894 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 if (offset >= 0) {
896 shmem_dir_unmap(dir);
897 goto found;
898 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 }
900 }
901lost1:
902 shmem_dir_unmap(dir-1);
903lost2:
904 spin_unlock(&info->lock);
905 return 0;
906found:
907 idx += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800908 inode = igrab(&info->vfs_inode);
909 spin_unlock(&info->lock);
910
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800911 /*
912 * Move _head_ to start search for next from here.
913 * But be careful: shmem_delete_inode checks list_empty without taking
914 * mutex, and there's an instant in list_move_tail when info->swaplist
915 * would appear empty, if it were the only one on shmem_swaplist. We
916 * could avoid doing it if inode NULL; or use this minor optimization.
917 */
918 if (shmem_swaplist.next != &info->swaplist)
919 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800920 mutex_unlock(&shmem_swaplist_mutex);
921
922 error = 1;
923 if (!inode)
924 goto out;
Hugh Dickins82369552008-02-07 00:14:22 -0800925 /* Precharge page while we can wait, compensate afterwards */
926 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800927 if (error)
928 goto out;
Hugh Dickins82369552008-02-07 00:14:22 -0800929 error = radix_tree_preload(GFP_KERNEL);
930 if (error)
931 goto uncharge;
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800932 error = 1;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800933
934 spin_lock(&info->lock);
935 ptr = shmem_swp_entry(info, idx, NULL);
936 if (ptr && ptr->val == entry.val)
937 error = add_to_page_cache(page, inode->i_mapping,
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800938 idx, GFP_NOWAIT);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800939 if (error == -EEXIST) {
940 struct page *filepage = find_get_page(inode->i_mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800941 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800942 if (filepage) {
943 /*
944 * There might be a more uptodate page coming down
945 * from a stacked writepage: forget our swappage if so.
946 */
947 if (PageUptodate(filepage))
948 error = 0;
949 page_cache_release(filepage);
950 }
951 }
952 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800953 delete_from_swap_cache(page);
954 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800956 shmem_swp_set(info, ptr, 0);
957 swap_free(entry);
958 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800960 if (ptr)
961 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962 spin_unlock(&info->lock);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800963 radix_tree_preload_end();
Hugh Dickins82369552008-02-07 00:14:22 -0800964uncharge:
965 mem_cgroup_uncharge_page(page);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800966out:
967 unlock_page(page);
968 page_cache_release(page);
969 iput(inode); /* allows for NULL */
970 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971}
972
973/*
974 * shmem_unuse() search for an eventually swapped out shmem page.
975 */
976int shmem_unuse(swp_entry_t entry, struct page *page)
977{
978 struct list_head *p, *next;
979 struct shmem_inode_info *info;
980 int found = 0;
981
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800982 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 list_for_each_safe(p, next, &shmem_swaplist) {
984 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800985 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800986 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800987 if (found)
988 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800990 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800991out: return found; /* 0 or 1 or -ENOMEM */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992}
993
994/*
995 * Move the page from the page cache to the swap cache.
996 */
997static int shmem_writepage(struct page *page, struct writeback_control *wbc)
998{
999 struct shmem_inode_info *info;
1000 swp_entry_t *entry, swap;
1001 struct address_space *mapping;
1002 unsigned long index;
1003 struct inode *inode;
1004
1005 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006 mapping = page->mapping;
1007 index = page->index;
1008 inode = mapping->host;
1009 info = SHMEM_I(inode);
1010 if (info->flags & VM_LOCKED)
1011 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001012 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001013 goto redirty;
1014
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001015 /*
1016 * shmem_backing_dev_info's capabilities prevent regular writeback or
1017 * sync from ever calling shmem_writepage; but a stacking filesystem
1018 * may use the ->writepage of its underlying filesystem, in which case
1019 * tmpfs should write out to swap only in response to memory pressure,
1020 * and not for pdflush or sync. However, in those cases, we do still
1021 * want to check if there's a redundant swappage to be discarded.
1022 */
1023 if (wbc->for_reclaim)
1024 swap = get_swap_page();
1025 else
1026 swap.val = 0;
1027
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 spin_lock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 if (index >= info->next_index) {
1030 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1031 goto unlock;
1032 }
1033 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001034 if (entry->val) {
1035 /*
1036 * The more uptodate page coming down from a stacked
1037 * writepage should replace our old swappage.
1038 */
1039 free_swap_and_cache(*entry);
1040 shmem_swp_set(info, entry, 0);
1041 }
1042 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001044 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Hugh Dickins73b12622008-02-04 22:28:50 -08001045 remove_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001046 shmem_swp_set(info, entry, swap.val);
1047 shmem_swp_unmap(entry);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001048 if (list_empty(&info->swaplist))
1049 inode = igrab(inode);
1050 else
1051 inode = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001052 spin_unlock(&info->lock);
Hugh Dickins73b12622008-02-04 22:28:50 -08001053 swap_duplicate(swap);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001054 BUG_ON(page_mapped(page));
Hugh Dickins73b12622008-02-04 22:28:50 -08001055 page_cache_release(page); /* pagecache ref */
1056 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057 unlock_page(page);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001058 if (inode) {
1059 mutex_lock(&shmem_swaplist_mutex);
1060 /* move instead of add in case we're racing */
1061 list_move_tail(&info->swaplist, &shmem_swaplist);
1062 mutex_unlock(&shmem_swaplist_mutex);
1063 iput(inode);
1064 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001065 return 0;
1066 }
1067
1068 shmem_swp_unmap(entry);
1069unlock:
1070 spin_unlock(&info->lock);
1071 swap_free(swap);
1072redirty:
1073 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001074 if (wbc->for_reclaim)
1075 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1076 unlock_page(page);
1077 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078}
1079
1080#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001081#ifdef CONFIG_TMPFS
1082static int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001083{
1084 char *nodelist = strchr(value, ':');
1085 int err = 1;
1086
1087 if (nodelist) {
1088 /* NUL-terminate policy string */
1089 *nodelist++ = '\0';
1090 if (nodelist_parse(nodelist, *policy_nodes))
1091 goto out;
Lee Schermerhorn37b07e42007-10-16 01:25:39 -07001092 if (!nodes_subset(*policy_nodes, node_states[N_HIGH_MEMORY]))
Hugh Dickinsa2109062007-06-08 13:46:46 -07001093 goto out;
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001094 }
1095 if (!strcmp(value, "default")) {
1096 *policy = MPOL_DEFAULT;
1097 /* Don't allow a nodelist */
1098 if (!nodelist)
1099 err = 0;
1100 } else if (!strcmp(value, "prefer")) {
1101 *policy = MPOL_PREFERRED;
1102 /* Insist on a nodelist of one node only */
1103 if (nodelist) {
1104 char *rest = nodelist;
1105 while (isdigit(*rest))
1106 rest++;
1107 if (!*rest)
1108 err = 0;
1109 }
1110 } else if (!strcmp(value, "bind")) {
1111 *policy = MPOL_BIND;
1112 /* Insist on a nodelist */
1113 if (nodelist)
1114 err = 0;
1115 } else if (!strcmp(value, "interleave")) {
1116 *policy = MPOL_INTERLEAVE;
Lee Schermerhorn37b07e42007-10-16 01:25:39 -07001117 /*
1118 * Default to online nodes with memory if no nodelist
1119 */
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001120 if (!nodelist)
Lee Schermerhorn37b07e42007-10-16 01:25:39 -07001121 *policy_nodes = node_states[N_HIGH_MEMORY];
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001122 err = 0;
1123 }
1124out:
1125 /* Restore string for error message */
1126 if (nodelist)
1127 *--nodelist = ':';
1128 return err;
1129}
1130
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001131static void shmem_show_mpol(struct seq_file *seq, int policy,
1132 const nodemask_t policy_nodes)
1133{
1134 char *policy_string;
1135
1136 switch (policy) {
1137 case MPOL_PREFERRED:
1138 policy_string = "prefer";
1139 break;
1140 case MPOL_BIND:
1141 policy_string = "bind";
1142 break;
1143 case MPOL_INTERLEAVE:
1144 policy_string = "interleave";
1145 break;
1146 default:
1147 /* MPOL_DEFAULT */
1148 return;
1149 }
1150
1151 seq_printf(seq, ",mpol=%s", policy_string);
1152
1153 if (policy != MPOL_INTERLEAVE ||
1154 !nodes_equal(policy_nodes, node_states[N_HIGH_MEMORY])) {
1155 char buffer[64];
1156 int len;
1157
1158 len = nodelist_scnprintf(buffer, sizeof(buffer), policy_nodes);
1159 if (len < sizeof(buffer))
1160 seq_printf(seq, ":%s", buffer);
1161 else
1162 seq_printf(seq, ":?");
1163 }
1164}
1165#endif /* CONFIG_TMPFS */
1166
Hugh Dickins02098fe2008-02-04 22:28:42 -08001167static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1168 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001171 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
1173 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001174 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001176 pvma.vm_ops = NULL;
1177 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001178 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 mpol_free(pvma.vm_policy);
1180 return page;
1181}
1182
Hugh Dickins02098fe2008-02-04 22:28:42 -08001183static struct page *shmem_alloc_page(gfp_t gfp,
1184 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001185{
1186 struct vm_area_struct pvma;
1187 struct page *page;
1188
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001189 /* Create a pseudo vma that just contains the policy */
1190 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001191 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001192 pvma.vm_ops = NULL;
1193 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001194 page = alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195 mpol_free(pvma.vm_policy);
1196 return page;
1197}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001198#else /* !CONFIG_NUMA */
1199#ifdef CONFIG_TMPFS
Lee Schermerhorn37b07e42007-10-16 01:25:39 -07001200static inline int shmem_parse_mpol(char *value, int *policy,
1201 nodemask_t *policy_nodes)
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001202{
1203 return 1;
1204}
1205
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001206static inline void shmem_show_mpol(struct seq_file *seq, int policy,
1207 const nodemask_t policy_nodes)
1208{
1209}
1210#endif /* CONFIG_TMPFS */
1211
Hugh Dickins02098fe2008-02-04 22:28:42 -08001212static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1213 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001215 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216}
1217
Hugh Dickins02098fe2008-02-04 22:28:42 -08001218static inline struct page *shmem_alloc_page(gfp_t gfp,
1219 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001220{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001221 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001223#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224
1225/*
1226 * shmem_getpage - either get the page from swap or allocate a new one
1227 *
1228 * If we allocate a new one we do not mark it dirty. That's up to the
1229 * vm. If we swap it in we mark it dirty since we also free the swap
1230 * entry since a page cannot live in both the swap and page cache
1231 */
1232static int shmem_getpage(struct inode *inode, unsigned long idx,
1233 struct page **pagep, enum sgp_type sgp, int *type)
1234{
1235 struct address_space *mapping = inode->i_mapping;
1236 struct shmem_inode_info *info = SHMEM_I(inode);
1237 struct shmem_sb_info *sbinfo;
1238 struct page *filepage = *pagep;
1239 struct page *swappage;
1240 swp_entry_t *entry;
1241 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001242 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243 int error;
1244
1245 if (idx >= SHMEM_MAX_INDEX)
1246 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001247
1248 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001249 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001250
Linus Torvalds1da177e2005-04-16 15:20:36 -07001251 /*
1252 * Normally, filepage is NULL on entry, and either found
1253 * uptodate immediately, or allocated and zeroed, or read
1254 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001255 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae976412007-06-04 10:00:39 +02001256 * filepage, which may be found not uptodate by other callers
1257 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001258 */
1259repeat:
1260 if (!filepage)
1261 filepage = find_lock_page(mapping, idx);
1262 if (filepage && PageUptodate(filepage))
1263 goto done;
1264 error = 0;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001265 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001266 if (!filepage) {
1267 /*
1268 * Try to preload while we can wait, to not make a habit of
1269 * draining atomic reserves; but don't latch on to this cpu.
1270 */
1271 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1272 if (error)
1273 goto failed;
1274 radix_tree_preload_end();
1275 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276
1277 spin_lock(&info->lock);
1278 shmem_recalc_inode(inode);
1279 entry = shmem_swp_alloc(info, idx, sgp);
1280 if (IS_ERR(entry)) {
1281 spin_unlock(&info->lock);
1282 error = PTR_ERR(entry);
1283 goto failed;
1284 }
1285 swap = *entry;
1286
1287 if (swap.val) {
1288 /* Look it up and read it in.. */
1289 swappage = lookup_swap_cache(swap);
1290 if (!swappage) {
1291 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001293 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001294 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001295 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001297 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001298 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 if (!swappage) {
1300 spin_lock(&info->lock);
1301 entry = shmem_swp_alloc(info, idx, sgp);
1302 if (IS_ERR(entry))
1303 error = PTR_ERR(entry);
1304 else {
1305 if (entry->val == swap.val)
1306 error = -ENOMEM;
1307 shmem_swp_unmap(entry);
1308 }
1309 spin_unlock(&info->lock);
1310 if (error)
1311 goto failed;
1312 goto repeat;
1313 }
1314 wait_on_page_locked(swappage);
1315 page_cache_release(swappage);
1316 goto repeat;
1317 }
1318
1319 /* We have to do this with page locked to prevent races */
1320 if (TestSetPageLocked(swappage)) {
1321 shmem_swp_unmap(entry);
1322 spin_unlock(&info->lock);
1323 wait_on_page_locked(swappage);
1324 page_cache_release(swappage);
1325 goto repeat;
1326 }
1327 if (PageWriteback(swappage)) {
1328 shmem_swp_unmap(entry);
1329 spin_unlock(&info->lock);
1330 wait_on_page_writeback(swappage);
1331 unlock_page(swappage);
1332 page_cache_release(swappage);
1333 goto repeat;
1334 }
1335 if (!PageUptodate(swappage)) {
1336 shmem_swp_unmap(entry);
1337 spin_unlock(&info->lock);
1338 unlock_page(swappage);
1339 page_cache_release(swappage);
1340 error = -EIO;
1341 goto failed;
1342 }
1343
1344 if (filepage) {
1345 shmem_swp_set(info, entry, 0);
1346 shmem_swp_unmap(entry);
1347 delete_from_swap_cache(swappage);
1348 spin_unlock(&info->lock);
1349 copy_highpage(filepage, swappage);
1350 unlock_page(swappage);
1351 page_cache_release(swappage);
1352 flush_dcache_page(filepage);
1353 SetPageUptodate(filepage);
1354 set_page_dirty(filepage);
1355 swap_free(swap);
Hugh Dickins73b12622008-02-04 22:28:50 -08001356 } else if (!(error = add_to_page_cache(
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001357 swappage, mapping, idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 info->flags |= SHMEM_PAGEIN;
1359 shmem_swp_set(info, entry, 0);
1360 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001361 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 spin_unlock(&info->lock);
1363 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001364 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 swap_free(swap);
1366 } else {
1367 shmem_swp_unmap(entry);
1368 spin_unlock(&info->lock);
1369 unlock_page(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001370 if (error == -ENOMEM) {
1371 /* allow reclaim from this memory cgroup */
Hugh Dickins7e924aa2008-03-04 14:29:08 -08001372 error = mem_cgroup_cache_charge(swappage,
Hugh Dickins82369552008-02-07 00:14:22 -08001373 current->mm, gfp & ~__GFP_HIGHMEM);
Hugh Dickins7e924aa2008-03-04 14:29:08 -08001374 if (error) {
1375 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001376 goto failed;
Hugh Dickins7e924aa2008-03-04 14:29:08 -08001377 }
1378 mem_cgroup_uncharge_page(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001379 }
Hugh Dickins7e924aa2008-03-04 14:29:08 -08001380 page_cache_release(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 goto repeat;
1382 }
1383 } else if (sgp == SGP_READ && !filepage) {
1384 shmem_swp_unmap(entry);
1385 filepage = find_get_page(mapping, idx);
1386 if (filepage &&
1387 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1388 spin_unlock(&info->lock);
1389 wait_on_page_locked(filepage);
1390 page_cache_release(filepage);
1391 filepage = NULL;
1392 goto repeat;
1393 }
1394 spin_unlock(&info->lock);
1395 } else {
1396 shmem_swp_unmap(entry);
1397 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001398 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 spin_lock(&sbinfo->stat_lock);
1400 if (sbinfo->free_blocks == 0 ||
1401 shmem_acct_block(info->flags)) {
1402 spin_unlock(&sbinfo->stat_lock);
1403 spin_unlock(&info->lock);
1404 error = -ENOSPC;
1405 goto failed;
1406 }
1407 sbinfo->free_blocks--;
1408 inode->i_blocks += BLOCKS_PER_PAGE;
1409 spin_unlock(&sbinfo->stat_lock);
1410 } else if (shmem_acct_block(info->flags)) {
1411 spin_unlock(&info->lock);
1412 error = -ENOSPC;
1413 goto failed;
1414 }
1415
1416 if (!filepage) {
1417 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001418 filepage = shmem_alloc_page(gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 if (!filepage) {
1420 shmem_unacct_blocks(info->flags, 1);
1421 shmem_free_blocks(inode, 1);
1422 error = -ENOMEM;
1423 goto failed;
1424 }
1425
Hugh Dickins82369552008-02-07 00:14:22 -08001426 /* Precharge page while we can wait, compensate after */
1427 error = mem_cgroup_cache_charge(filepage, current->mm,
1428 gfp & ~__GFP_HIGHMEM);
1429 if (error) {
1430 page_cache_release(filepage);
1431 shmem_unacct_blocks(info->flags, 1);
1432 shmem_free_blocks(inode, 1);
1433 filepage = NULL;
1434 goto failed;
1435 }
1436
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 spin_lock(&info->lock);
1438 entry = shmem_swp_alloc(info, idx, sgp);
1439 if (IS_ERR(entry))
1440 error = PTR_ERR(entry);
1441 else {
1442 swap = *entry;
1443 shmem_swp_unmap(entry);
1444 }
1445 if (error || swap.val || 0 != add_to_page_cache_lru(
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001446 filepage, mapping, idx, GFP_NOWAIT)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 spin_unlock(&info->lock);
Hugh Dickins82369552008-02-07 00:14:22 -08001448 mem_cgroup_uncharge_page(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001449 page_cache_release(filepage);
1450 shmem_unacct_blocks(info->flags, 1);
1451 shmem_free_blocks(inode, 1);
1452 filepage = NULL;
1453 if (error)
1454 goto failed;
1455 goto repeat;
1456 }
Hugh Dickins82369552008-02-07 00:14:22 -08001457 mem_cgroup_uncharge_page(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458 info->flags |= SHMEM_PAGEIN;
1459 }
1460
1461 info->alloced++;
1462 spin_unlock(&info->lock);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001463 clear_highpage(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 flush_dcache_page(filepage);
1465 SetPageUptodate(filepage);
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001466 if (sgp == SGP_DIRTY)
1467 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468 }
1469done:
Hugh Dickinsd3602442008-02-04 22:28:44 -08001470 *pagep = filepage;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 return 0;
1472
1473failed:
1474 if (*pagep != filepage) {
1475 unlock_page(filepage);
1476 page_cache_release(filepage);
1477 }
1478 return error;
1479}
1480
Nick Piggind0217ac2007-07-19 01:47:03 -07001481static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001483 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001484 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001485 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486
Nick Piggind0217ac2007-07-19 01:47:03 -07001487 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1488 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001489
Hugh Dickins27d54b32008-02-04 22:28:43 -08001490 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001491 if (error)
1492 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493
Nick Piggind0217ac2007-07-19 01:47:03 -07001494 mark_page_accessed(vmf->page);
Nick Piggin83c54072007-07-19 01:47:05 -07001495 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496}
1497
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001499static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001501 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1503}
1504
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001505static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1506 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001508 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001509 unsigned long idx;
1510
1511 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1512 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1513}
1514#endif
1515
1516int shmem_lock(struct file *file, int lock, struct user_struct *user)
1517{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001518 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 struct shmem_inode_info *info = SHMEM_I(inode);
1520 int retval = -ENOMEM;
1521
1522 spin_lock(&info->lock);
1523 if (lock && !(info->flags & VM_LOCKED)) {
1524 if (!user_shm_lock(inode->i_size, user))
1525 goto out_nomem;
1526 info->flags |= VM_LOCKED;
1527 }
1528 if (!lock && (info->flags & VM_LOCKED) && user) {
1529 user_shm_unlock(inode->i_size, user);
1530 info->flags &= ~VM_LOCKED;
1531 }
1532 retval = 0;
1533out_nomem:
1534 spin_unlock(&info->lock);
1535 return retval;
1536}
1537
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001538static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539{
1540 file_accessed(file);
1541 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001542 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543 return 0;
1544}
1545
1546static struct inode *
1547shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1548{
1549 struct inode *inode;
1550 struct shmem_inode_info *info;
1551 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1552
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001553 if (shmem_reserve_inode(sb))
1554 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555
1556 inode = new_inode(sb);
1557 if (inode) {
1558 inode->i_mode = mode;
1559 inode->i_uid = current->fsuid;
1560 inode->i_gid = current->fsgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 inode->i_blocks = 0;
1562 inode->i_mapping->a_ops = &shmem_aops;
1563 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1564 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001565 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566 info = SHMEM_I(inode);
1567 memset(info, 0, (char *)inode - (char *)info);
1568 spin_lock_init(&info->lock);
1569 INIT_LIST_HEAD(&info->swaplist);
1570
1571 switch (mode & S_IFMT) {
1572 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001573 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 init_special_inode(inode, mode, dev);
1575 break;
1576 case S_IFREG:
1577 inode->i_op = &shmem_inode_operations;
1578 inode->i_fop = &shmem_file_operations;
Robin Holt7339ff82006-01-14 13:20:48 -08001579 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1580 &sbinfo->policy_nodes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001581 break;
1582 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001583 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 /* Some things misbehave if size == 0 on a directory */
1585 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1586 inode->i_op = &shmem_dir_inode_operations;
1587 inode->i_fop = &simple_dir_operations;
1588 break;
1589 case S_IFLNK:
1590 /*
1591 * Must not load anything in the rbtree,
1592 * mpol_free_shared_policy will not be called.
1593 */
Robin Holt7339ff82006-01-14 13:20:48 -08001594 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1595 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596 break;
1597 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001598 } else
1599 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600 return inode;
1601}
1602
1603#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001604static const struct inode_operations shmem_symlink_inode_operations;
1605static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606
1607/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001608 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae976412007-06-04 10:00:39 +02001609 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1610 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001612static int shmem_readpage(struct file *file, struct page *page)
1613{
1614 struct inode *inode = page->mapping->host;
1615 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1616 unlock_page(page);
1617 return error;
1618}
1619
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001621shmem_write_begin(struct file *file, struct address_space *mapping,
1622 loff_t pos, unsigned len, unsigned flags,
1623 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624{
Nick Piggin800d15a2007-10-16 01:25:03 -07001625 struct inode *inode = mapping->host;
1626 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1627 *pagep = NULL;
1628 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1629}
1630
1631static int
1632shmem_write_end(struct file *file, struct address_space *mapping,
1633 loff_t pos, unsigned len, unsigned copied,
1634 struct page *page, void *fsdata)
1635{
1636 struct inode *inode = mapping->host;
1637
Hugh Dickinsd3602442008-02-04 22:28:44 -08001638 if (pos + copied > inode->i_size)
1639 i_size_write(inode, pos + copied);
1640
1641 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001642 set_page_dirty(page);
1643 page_cache_release(page);
1644
Nick Piggin800d15a2007-10-16 01:25:03 -07001645 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646}
1647
Linus Torvalds1da177e2005-04-16 15:20:36 -07001648static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1649{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001650 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651 struct address_space *mapping = inode->i_mapping;
1652 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001653 enum sgp_type sgp = SGP_READ;
1654
1655 /*
1656 * Might this read be for a stacking filesystem? Then when reading
1657 * holes of a sparse file, we actually need to allocate those pages,
1658 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1659 */
1660 if (segment_eq(get_fs(), KERNEL_DS))
1661 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001662
1663 index = *ppos >> PAGE_CACHE_SHIFT;
1664 offset = *ppos & ~PAGE_CACHE_MASK;
1665
1666 for (;;) {
1667 struct page *page = NULL;
1668 unsigned long end_index, nr, ret;
1669 loff_t i_size = i_size_read(inode);
1670
1671 end_index = i_size >> PAGE_CACHE_SHIFT;
1672 if (index > end_index)
1673 break;
1674 if (index == end_index) {
1675 nr = i_size & ~PAGE_CACHE_MASK;
1676 if (nr <= offset)
1677 break;
1678 }
1679
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001680 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 if (desc->error) {
1682 if (desc->error == -EINVAL)
1683 desc->error = 0;
1684 break;
1685 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001686 if (page)
1687 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688
1689 /*
1690 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001691 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 */
1693 nr = PAGE_CACHE_SIZE;
1694 i_size = i_size_read(inode);
1695 end_index = i_size >> PAGE_CACHE_SHIFT;
1696 if (index == end_index) {
1697 nr = i_size & ~PAGE_CACHE_MASK;
1698 if (nr <= offset) {
1699 if (page)
1700 page_cache_release(page);
1701 break;
1702 }
1703 }
1704 nr -= offset;
1705
1706 if (page) {
1707 /*
1708 * If users can be writing to this page using arbitrary
1709 * virtual addresses, take care about potential aliasing
1710 * before reading the page on the kernel side.
1711 */
1712 if (mapping_writably_mapped(mapping))
1713 flush_dcache_page(page);
1714 /*
1715 * Mark the page accessed if we read the beginning.
1716 */
1717 if (!offset)
1718 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001719 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001720 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001721 page_cache_get(page);
1722 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001723
1724 /*
1725 * Ok, we have the page, and it's up-to-date, so
1726 * now we can copy it to user space...
1727 *
1728 * The actor routine returns how many bytes were actually used..
1729 * NOTE! This may not be the same as how much of a user buffer
1730 * we filled up (we may be padding etc), so we can only update
1731 * "pos" here (the actor routine has to update the user buffer
1732 * pointers and the remaining count).
1733 */
1734 ret = actor(desc, page, offset, nr);
1735 offset += ret;
1736 index += offset >> PAGE_CACHE_SHIFT;
1737 offset &= ~PAGE_CACHE_MASK;
1738
1739 page_cache_release(page);
1740 if (ret != nr || !desc->count)
1741 break;
1742
1743 cond_resched();
1744 }
1745
1746 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1747 file_accessed(filp);
1748}
1749
1750static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1751{
1752 read_descriptor_t desc;
1753
1754 if ((ssize_t) count < 0)
1755 return -EINVAL;
1756 if (!access_ok(VERIFY_WRITE, buf, count))
1757 return -EFAULT;
1758 if (!count)
1759 return 0;
1760
1761 desc.written = 0;
1762 desc.count = count;
1763 desc.arg.buf = buf;
1764 desc.error = 0;
1765
1766 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1767 if (desc.written)
1768 return desc.written;
1769 return desc.error;
1770}
1771
David Howells726c3342006-06-23 02:02:58 -07001772static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001773{
David Howells726c3342006-06-23 02:02:58 -07001774 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001775
1776 buf->f_type = TMPFS_MAGIC;
1777 buf->f_bsize = PAGE_CACHE_SIZE;
1778 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001779 spin_lock(&sbinfo->stat_lock);
1780 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001781 buf->f_blocks = sbinfo->max_blocks;
1782 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001783 }
1784 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001785 buf->f_files = sbinfo->max_inodes;
1786 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 }
1788 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001789 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001790 return 0;
1791}
1792
1793/*
1794 * File creation. Allocate an inode, and we're done..
1795 */
1796static int
1797shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1798{
1799 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1800 int error = -ENOSPC;
1801
1802 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001803 error = security_inode_init_security(inode, dir, NULL, NULL,
1804 NULL);
1805 if (error) {
1806 if (error != -EOPNOTSUPP) {
1807 iput(inode);
1808 return error;
1809 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001810 }
1811 error = shmem_acl_init(inode, dir);
1812 if (error) {
1813 iput(inode);
1814 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001815 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816 if (dir->i_mode & S_ISGID) {
1817 inode->i_gid = dir->i_gid;
1818 if (S_ISDIR(mode))
1819 inode->i_mode |= S_ISGID;
1820 }
1821 dir->i_size += BOGO_DIRENT_SIZE;
1822 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1823 d_instantiate(dentry, inode);
1824 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825 }
1826 return error;
1827}
1828
1829static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1830{
1831 int error;
1832
1833 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1834 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001835 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 return 0;
1837}
1838
1839static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1840 struct nameidata *nd)
1841{
1842 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1843}
1844
1845/*
1846 * Link a file..
1847 */
1848static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1849{
1850 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001851 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001852
1853 /*
1854 * No ordinary (disk based) filesystem counts links as inodes;
1855 * but each new link needs a new dentry, pinning lowmem, and
1856 * tmpfs dentries cannot be pruned until they are unlinked.
1857 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001858 ret = shmem_reserve_inode(inode->i_sb);
1859 if (ret)
1860 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861
1862 dir->i_size += BOGO_DIRENT_SIZE;
1863 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001864 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001865 atomic_inc(&inode->i_count); /* New dentry reference */
1866 dget(dentry); /* Extra pinning count for the created dentry */
1867 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001868out:
1869 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001870}
1871
1872static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1873{
1874 struct inode *inode = dentry->d_inode;
1875
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001876 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1877 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878
1879 dir->i_size -= BOGO_DIRENT_SIZE;
1880 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001881 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 dput(dentry); /* Undo the count from "create" - this does all the work */
1883 return 0;
1884}
1885
1886static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1887{
1888 if (!simple_empty(dentry))
1889 return -ENOTEMPTY;
1890
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001891 drop_nlink(dentry->d_inode);
1892 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893 return shmem_unlink(dir, dentry);
1894}
1895
1896/*
1897 * The VFS layer already does all the dentry stuff for rename,
1898 * we just have to decrement the usage count for the target if
1899 * it exists so that the VFS layer correctly free's it when it
1900 * gets overwritten.
1901 */
1902static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1903{
1904 struct inode *inode = old_dentry->d_inode;
1905 int they_are_dirs = S_ISDIR(inode->i_mode);
1906
1907 if (!simple_empty(new_dentry))
1908 return -ENOTEMPTY;
1909
1910 if (new_dentry->d_inode) {
1911 (void) shmem_unlink(new_dir, new_dentry);
1912 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001913 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001915 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001916 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001917 }
1918
1919 old_dir->i_size -= BOGO_DIRENT_SIZE;
1920 new_dir->i_size += BOGO_DIRENT_SIZE;
1921 old_dir->i_ctime = old_dir->i_mtime =
1922 new_dir->i_ctime = new_dir->i_mtime =
1923 inode->i_ctime = CURRENT_TIME;
1924 return 0;
1925}
1926
1927static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1928{
1929 int error;
1930 int len;
1931 struct inode *inode;
1932 struct page *page = NULL;
1933 char *kaddr;
1934 struct shmem_inode_info *info;
1935
1936 len = strlen(symname) + 1;
1937 if (len > PAGE_CACHE_SIZE)
1938 return -ENAMETOOLONG;
1939
1940 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1941 if (!inode)
1942 return -ENOSPC;
1943
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001944 error = security_inode_init_security(inode, dir, NULL, NULL,
1945 NULL);
1946 if (error) {
1947 if (error != -EOPNOTSUPP) {
1948 iput(inode);
1949 return error;
1950 }
1951 error = 0;
1952 }
1953
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 info = SHMEM_I(inode);
1955 inode->i_size = len-1;
1956 if (len <= (char *)inode - (char *)info) {
1957 /* do it inline */
1958 memcpy(info, symname, len);
1959 inode->i_op = &shmem_symlink_inline_operations;
1960 } else {
1961 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1962 if (error) {
1963 iput(inode);
1964 return error;
1965 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001966 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001967 inode->i_op = &shmem_symlink_inode_operations;
1968 kaddr = kmap_atomic(page, KM_USER0);
1969 memcpy(kaddr, symname, len);
1970 kunmap_atomic(kaddr, KM_USER0);
1971 set_page_dirty(page);
1972 page_cache_release(page);
1973 }
1974 if (dir->i_mode & S_ISGID)
1975 inode->i_gid = dir->i_gid;
1976 dir->i_size += BOGO_DIRENT_SIZE;
1977 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1978 d_instantiate(dentry, inode);
1979 dget(dentry);
1980 return 0;
1981}
1982
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001983static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001984{
1985 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001986 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001987}
1988
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001989static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990{
1991 struct page *page = NULL;
1992 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1993 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08001994 if (page)
1995 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001996 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001997}
1998
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001999static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002000{
2001 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002002 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002003 kunmap(page);
2004 mark_page_accessed(page);
2005 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002006 }
2007}
2008
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002009static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002010 .readlink = generic_readlink,
2011 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012};
2013
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002014static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015 .truncate = shmem_truncate,
2016 .readlink = generic_readlink,
2017 .follow_link = shmem_follow_link,
2018 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019};
2020
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002021#ifdef CONFIG_TMPFS_POSIX_ACL
Randy Dunlap46711812008-03-19 17:00:41 -07002022/*
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002023 * Superblocks without xattr inode operations will get security.* xattr
2024 * support from the VFS "for free". As soon as we have any other xattrs
2025 * like ACLs, we also need to implement the security.* handlers at
2026 * filesystem level, though.
2027 */
2028
2029static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2030 size_t list_len, const char *name,
2031 size_t name_len)
2032{
2033 return security_inode_listsecurity(inode, list, list_len);
2034}
2035
2036static int shmem_xattr_security_get(struct inode *inode, const char *name,
2037 void *buffer, size_t size)
2038{
2039 if (strcmp(name, "") == 0)
2040 return -EINVAL;
David P. Quigley42492592008-02-04 22:29:39 -08002041 return xattr_getsecurity(inode, name, buffer, size);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002042}
2043
2044static int shmem_xattr_security_set(struct inode *inode, const char *name,
2045 const void *value, size_t size, int flags)
2046{
2047 if (strcmp(name, "") == 0)
2048 return -EINVAL;
2049 return security_inode_setsecurity(inode, name, value, size, flags);
2050}
2051
Adrian Bunk1f370a22006-12-06 20:38:21 -08002052static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002053 .prefix = XATTR_SECURITY_PREFIX,
2054 .list = shmem_xattr_security_list,
2055 .get = shmem_xattr_security_get,
2056 .set = shmem_xattr_security_set,
2057};
2058
2059static struct xattr_handler *shmem_xattr_handlers[] = {
2060 &shmem_xattr_acl_access_handler,
2061 &shmem_xattr_acl_default_handler,
2062 &shmem_xattr_security_handler,
2063 NULL
2064};
2065#endif
2066
David M. Grimes91828a42006-10-17 00:09:45 -07002067static struct dentry *shmem_get_parent(struct dentry *child)
2068{
2069 return ERR_PTR(-ESTALE);
2070}
2071
2072static int shmem_match(struct inode *ino, void *vfh)
2073{
2074 __u32 *fh = vfh;
2075 __u64 inum = fh[2];
2076 inum = (inum << 32) | fh[1];
2077 return ino->i_ino == inum && fh[0] == ino->i_generation;
2078}
2079
Christoph Hellwig480b1162007-10-21 16:42:13 -07002080static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2081 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002082{
David M. Grimes91828a42006-10-17 00:09:45 -07002083 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002084 struct dentry *dentry = NULL;
2085 u64 inum = fid->raw[2];
2086 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002087
Christoph Hellwig480b1162007-10-21 16:42:13 -07002088 if (fh_len < 3)
2089 return NULL;
2090
2091 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2092 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002093 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002094 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002095 iput(inode);
2096 }
2097
Christoph Hellwig480b1162007-10-21 16:42:13 -07002098 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002099}
2100
2101static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2102 int connectable)
2103{
2104 struct inode *inode = dentry->d_inode;
2105
2106 if (*len < 3)
2107 return 255;
2108
2109 if (hlist_unhashed(&inode->i_hash)) {
2110 /* Unfortunately insert_inode_hash is not idempotent,
2111 * so as we hash inodes here rather than at creation
2112 * time, we need a lock to ensure we only try
2113 * to do it once
2114 */
2115 static DEFINE_SPINLOCK(lock);
2116 spin_lock(&lock);
2117 if (hlist_unhashed(&inode->i_hash))
2118 __insert_inode_hash(inode,
2119 inode->i_ino + inode->i_generation);
2120 spin_unlock(&lock);
2121 }
2122
2123 fh[0] = inode->i_generation;
2124 fh[1] = inode->i_ino;
2125 fh[2] = ((__u64)inode->i_ino) >> 32;
2126
2127 *len = 3;
2128 return 1;
2129}
2130
Christoph Hellwig39655162007-10-21 16:42:17 -07002131static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002132 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002133 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002134 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002135};
2136
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002137static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2138 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002139{
2140 char *this_char, *value, *rest;
2141
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002142 while (options != NULL) {
2143 this_char = options;
2144 for (;;) {
2145 /*
2146 * NUL-terminate this option: unfortunately,
2147 * mount options form a comma-separated list,
2148 * but mpol's nodelist may also contain commas.
2149 */
2150 options = strchr(options, ',');
2151 if (options == NULL)
2152 break;
2153 options++;
2154 if (!isdigit(*options)) {
2155 options[-1] = '\0';
2156 break;
2157 }
2158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 if (!*this_char)
2160 continue;
2161 if ((value = strchr(this_char,'=')) != NULL) {
2162 *value++ = 0;
2163 } else {
2164 printk(KERN_ERR
2165 "tmpfs: No value for mount option '%s'\n",
2166 this_char);
2167 return 1;
2168 }
2169
2170 if (!strcmp(this_char,"size")) {
2171 unsigned long long size;
2172 size = memparse(value,&rest);
2173 if (*rest == '%') {
2174 size <<= PAGE_SHIFT;
2175 size *= totalram_pages;
2176 do_div(size, 100);
2177 rest++;
2178 }
2179 if (*rest)
2180 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002181 sbinfo->max_blocks =
2182 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002184 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 if (*rest)
2186 goto bad_val;
2187 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002188 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002189 if (*rest)
2190 goto bad_val;
2191 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002192 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002194 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002195 if (*rest)
2196 goto bad_val;
2197 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002198 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002200 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201 if (*rest)
2202 goto bad_val;
2203 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002204 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002205 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002206 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002207 if (*rest)
2208 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002209 } else if (!strcmp(this_char,"mpol")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002210 if (shmem_parse_mpol(value, &sbinfo->policy,
2211 &sbinfo->policy_nodes))
Robin Holt7339ff82006-01-14 13:20:48 -08002212 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002213 } else {
2214 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2215 this_char);
2216 return 1;
2217 }
2218 }
2219 return 0;
2220
2221bad_val:
2222 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2223 value, this_char);
2224 return 1;
2225
2226}
2227
2228static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2229{
2230 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002231 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002232 unsigned long blocks;
2233 unsigned long inodes;
2234 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002236 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002237 return error;
2238
2239 spin_lock(&sbinfo->stat_lock);
2240 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2241 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002242 if (config.max_blocks < blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002243 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002244 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002245 goto out;
2246 /*
2247 * Those tests also disallow limited->unlimited while any are in
2248 * use, so i_blocks will always be zero when max_blocks is zero;
2249 * but we must separately disallow unlimited->limited, because
2250 * in that case we have no record of how much is already in use.
2251 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002252 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002253 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002254 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002255 goto out;
2256
2257 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002258 sbinfo->max_blocks = config.max_blocks;
2259 sbinfo->free_blocks = config.max_blocks - blocks;
2260 sbinfo->max_inodes = config.max_inodes;
2261 sbinfo->free_inodes = config.max_inodes - inodes;
2262 sbinfo->policy = config.policy;
2263 sbinfo->policy_nodes = config.policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002264out:
2265 spin_unlock(&sbinfo->stat_lock);
2266 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002268
2269static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2270{
2271 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2272
2273 if (sbinfo->max_blocks != shmem_default_max_blocks())
2274 seq_printf(seq, ",size=%luk",
2275 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2276 if (sbinfo->max_inodes != shmem_default_max_inodes())
2277 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2278 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2279 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2280 if (sbinfo->uid != 0)
2281 seq_printf(seq, ",uid=%u", sbinfo->uid);
2282 if (sbinfo->gid != 0)
2283 seq_printf(seq, ",gid=%u", sbinfo->gid);
2284 shmem_show_mpol(seq, sbinfo->policy, sbinfo->policy_nodes);
2285 return 0;
2286}
2287#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
2289static void shmem_put_super(struct super_block *sb)
2290{
2291 kfree(sb->s_fs_info);
2292 sb->s_fs_info = NULL;
2293}
2294
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295static int shmem_fill_super(struct super_block *sb,
2296 void *data, int silent)
2297{
2298 struct inode *inode;
2299 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002300 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002301 int err = -ENOMEM;
2302
2303 /* Round up to L1_CACHE_BYTES to resist false sharing */
2304 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2305 L1_CACHE_BYTES), GFP_KERNEL);
2306 if (!sbinfo)
2307 return -ENOMEM;
2308
2309 sbinfo->max_blocks = 0;
2310 sbinfo->max_inodes = 0;
2311 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2312 sbinfo->uid = current->fsuid;
2313 sbinfo->gid = current->fsgid;
2314 sbinfo->policy = MPOL_DEFAULT;
2315 sbinfo->policy_nodes = node_states[N_HIGH_MEMORY];
2316 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002317
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002318#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002319 /*
2320 * Per default we only allow half of the physical ram per
2321 * tmpfs instance, limiting inodes to one per page of lowmem;
2322 * but the internal instance is left unlimited.
2323 */
2324 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002325 sbinfo->max_blocks = shmem_default_max_blocks();
2326 sbinfo->max_inodes = shmem_default_max_inodes();
2327 if (shmem_parse_options(data, sbinfo, false)) {
2328 err = -EINVAL;
2329 goto failed;
2330 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002331 }
David M. Grimes91828a42006-10-17 00:09:45 -07002332 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333#else
2334 sb->s_flags |= MS_NOUSER;
2335#endif
2336
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002337 spin_lock_init(&sbinfo->stat_lock);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002338 sbinfo->free_blocks = sbinfo->max_blocks;
2339 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002340
Linus Torvalds1da177e2005-04-16 15:20:36 -07002341 sb->s_maxbytes = SHMEM_MAX_BYTES;
2342 sb->s_blocksize = PAGE_CACHE_SIZE;
2343 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2344 sb->s_magic = TMPFS_MAGIC;
2345 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002346 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002347#ifdef CONFIG_TMPFS_POSIX_ACL
2348 sb->s_xattr = shmem_xattr_handlers;
2349 sb->s_flags |= MS_POSIXACL;
2350#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002351
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002352 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002353 if (!inode)
2354 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002355 inode->i_uid = sbinfo->uid;
2356 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002357 root = d_alloc_root(inode);
2358 if (!root)
2359 goto failed_iput;
2360 sb->s_root = root;
2361 return 0;
2362
2363failed_iput:
2364 iput(inode);
2365failed:
2366 shmem_put_super(sb);
2367 return err;
2368}
2369
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002370static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002371
2372static struct inode *shmem_alloc_inode(struct super_block *sb)
2373{
2374 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002375 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 if (!p)
2377 return NULL;
2378 return &p->vfs_inode;
2379}
2380
2381static void shmem_destroy_inode(struct inode *inode)
2382{
2383 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2384 /* only struct inode is valid if it's an inline symlink */
2385 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2386 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002387 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2389}
2390
Christoph Lameter4ba9b9d2007-10-16 23:25:51 -07002391static void init_once(struct kmem_cache *cachep, void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002392{
2393 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2394
Christoph Lametera35afb82007-05-16 22:10:57 -07002395 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002396#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002397 p->i_acl = NULL;
2398 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002399#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002400}
2401
2402static int init_inodecache(void)
2403{
2404 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2405 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002406 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407 return 0;
2408}
2409
2410static void destroy_inodecache(void)
2411{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002412 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002413}
2414
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002415static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002416 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002417 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002419 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002420 .write_begin = shmem_write_begin,
2421 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002423 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002424};
2425
Helge Deller15ad7cd2006-12-06 20:40:36 -08002426static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427 .mmap = shmem_mmap,
2428#ifdef CONFIG_TMPFS
2429 .llseek = generic_file_llseek,
2430 .read = shmem_file_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002431 .write = do_sync_write,
2432 .aio_write = generic_file_aio_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002433 .fsync = simple_sync_file,
Hugh Dickinsae976412007-06-04 10:00:39 +02002434 .splice_read = generic_file_splice_read,
2435 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002436#endif
2437};
2438
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002439static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440 .truncate = shmem_truncate,
2441 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002442 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002443#ifdef CONFIG_TMPFS_POSIX_ACL
2444 .setxattr = generic_setxattr,
2445 .getxattr = generic_getxattr,
2446 .listxattr = generic_listxattr,
2447 .removexattr = generic_removexattr,
2448 .permission = shmem_permission,
2449#endif
2450
Linus Torvalds1da177e2005-04-16 15:20:36 -07002451};
2452
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002453static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002454#ifdef CONFIG_TMPFS
2455 .create = shmem_create,
2456 .lookup = simple_lookup,
2457 .link = shmem_link,
2458 .unlink = shmem_unlink,
2459 .symlink = shmem_symlink,
2460 .mkdir = shmem_mkdir,
2461 .rmdir = shmem_rmdir,
2462 .mknod = shmem_mknod,
2463 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002464#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002465#ifdef CONFIG_TMPFS_POSIX_ACL
2466 .setattr = shmem_notify_change,
2467 .setxattr = generic_setxattr,
2468 .getxattr = generic_getxattr,
2469 .listxattr = generic_listxattr,
2470 .removexattr = generic_removexattr,
2471 .permission = shmem_permission,
2472#endif
2473};
2474
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002475static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002476#ifdef CONFIG_TMPFS_POSIX_ACL
2477 .setattr = shmem_notify_change,
2478 .setxattr = generic_setxattr,
2479 .getxattr = generic_getxattr,
2480 .listxattr = generic_listxattr,
2481 .removexattr = generic_removexattr,
2482 .permission = shmem_permission,
2483#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002484};
2485
Hugh Dickins759b9772007-03-05 00:30:28 -08002486static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487 .alloc_inode = shmem_alloc_inode,
2488 .destroy_inode = shmem_destroy_inode,
2489#ifdef CONFIG_TMPFS
2490 .statfs = shmem_statfs,
2491 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002492 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002493#endif
2494 .delete_inode = shmem_delete_inode,
2495 .drop_inode = generic_delete_inode,
2496 .put_super = shmem_put_super,
2497};
2498
2499static struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002500 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002501#ifdef CONFIG_NUMA
2502 .set_policy = shmem_set_policy,
2503 .get_policy = shmem_get_policy,
2504#endif
2505};
2506
2507
David Howells454e2392006-06-23 02:02:57 -07002508static int shmem_get_sb(struct file_system_type *fs_type,
2509 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002510{
David Howells454e2392006-06-23 02:02:57 -07002511 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512}
2513
2514static struct file_system_type tmpfs_fs_type = {
2515 .owner = THIS_MODULE,
2516 .name = "tmpfs",
2517 .get_sb = shmem_get_sb,
2518 .kill_sb = kill_litter_super,
2519};
2520static struct vfsmount *shm_mnt;
2521
2522static int __init init_tmpfs(void)
2523{
2524 int error;
2525
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002526 error = bdi_init(&shmem_backing_dev_info);
2527 if (error)
2528 goto out4;
2529
Linus Torvalds1da177e2005-04-16 15:20:36 -07002530 error = init_inodecache();
2531 if (error)
2532 goto out3;
2533
2534 error = register_filesystem(&tmpfs_fs_type);
2535 if (error) {
2536 printk(KERN_ERR "Could not register tmpfs\n");
2537 goto out2;
2538 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002539
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002540 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002541 tmpfs_fs_type.name, NULL);
2542 if (IS_ERR(shm_mnt)) {
2543 error = PTR_ERR(shm_mnt);
2544 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2545 goto out1;
2546 }
2547 return 0;
2548
2549out1:
2550 unregister_filesystem(&tmpfs_fs_type);
2551out2:
2552 destroy_inodecache();
2553out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002554 bdi_destroy(&shmem_backing_dev_info);
2555out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556 shm_mnt = ERR_PTR(error);
2557 return error;
2558}
2559module_init(init_tmpfs)
2560
Randy Dunlap46711812008-03-19 17:00:41 -07002561/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002563 * @name: name for dentry (to be seen in /proc/<pid>/maps
2564 * @size: size to be set for the file
Randy Dunlap46711812008-03-19 17:00:41 -07002565 * @flags: vm_flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07002566 */
2567struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2568{
2569 int error;
2570 struct file *file;
2571 struct inode *inode;
2572 struct dentry *dentry, *root;
2573 struct qstr this;
2574
2575 if (IS_ERR(shm_mnt))
2576 return (void *)shm_mnt;
2577
2578 if (size < 0 || size > SHMEM_MAX_BYTES)
2579 return ERR_PTR(-EINVAL);
2580
2581 if (shmem_acct_size(flags, size))
2582 return ERR_PTR(-ENOMEM);
2583
2584 error = -ENOMEM;
2585 this.name = name;
2586 this.len = strlen(name);
2587 this.hash = 0; /* will go */
2588 root = shm_mnt->mnt_root;
2589 dentry = d_alloc(root, &this);
2590 if (!dentry)
2591 goto put_memory;
2592
2593 error = -ENFILE;
2594 file = get_empty_filp();
2595 if (!file)
2596 goto put_dentry;
2597
2598 error = -ENOSPC;
2599 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2600 if (!inode)
2601 goto close_file;
2602
2603 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2604 d_instantiate(dentry, inode);
2605 inode->i_size = size;
2606 inode->i_nlink = 0; /* It is unlinked */
Dave Hansence8d2cd2007-10-16 23:31:13 -07002607 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
2608 &shmem_file_operations);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002609 return file;
2610
2611close_file:
2612 put_filp(file);
2613put_dentry:
2614 dput(dentry);
2615put_memory:
2616 shmem_unacct_size(flags, size);
2617 return ERR_PTR(error);
2618}
2619
Randy Dunlap46711812008-03-19 17:00:41 -07002620/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002621 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07002622 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2623 */
2624int shmem_zero_setup(struct vm_area_struct *vma)
2625{
2626 struct file *file;
2627 loff_t size = vma->vm_end - vma->vm_start;
2628
2629 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2630 if (IS_ERR(file))
2631 return PTR_ERR(file);
2632
2633 if (vma->vm_file)
2634 fput(vma->vm_file);
2635 vma->vm_file = file;
2636 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002637 return 0;
2638}