blob: 4103a239ce843326faca51c61c5b0b105797b24b [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 *
Matt Mackall853ac432009-01-06 14:40:20 -080017 * tiny-shmem:
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
19 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 * This file is released under the GPL.
21 */
22
Matt Mackall853ac432009-01-06 14:40:20 -080023#include <linux/fs.h>
24#include <linux/init.h>
25#include <linux/vfs.h>
26#include <linux/mount.h>
27#include <linux/file.h>
28#include <linux/mm.h>
29#include <linux/module.h>
30#include <linux/swap.h>
31
32static struct vfsmount *shm_mnt;
33
34#ifdef CONFIG_SHMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -070035/*
36 * This virtual memory filesystem is heavily based on the ramfs. It
37 * extends ramfs by the ability to use swap and honor resource limits
38 * which makes it a completely usable filesystem.
39 */
40
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070041#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070042#include <linux/exportfs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070043#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <linux/mman.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/pagemap.h>
46#include <linux/string.h>
47#include <linux/slab.h>
48#include <linux/backing-dev.h>
49#include <linux/shmem_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070050#include <linux/writeback.h>
51#include <linux/vfs.h>
52#include <linux/blkdev.h>
53#include <linux/security.h>
54#include <linux/swapops.h>
55#include <linux/mempolicy.h>
56#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000057#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070058#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070059#include <linux/highmem.h>
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080060#include <linux/seq_file.h>
Mimi Zohar92562922008-10-07 14:00:12 -040061#include <linux/magic.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070062
Linus Torvalds1da177e2005-04-16 15:20:36 -070063#include <asm/uaccess.h>
64#include <asm/div64.h>
65#include <asm/pgtable.h>
66
Linus Torvalds1da177e2005-04-16 15:20:36 -070067#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
68#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
69#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
70
71#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
72#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
73
74#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
75
76/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
77#define SHMEM_PAGEIN VM_READ
78#define SHMEM_TRUNCATE VM_WRITE
79
80/* Definition to limit shmem_truncate's steps between cond_rescheds */
81#define LATENCY_LIMIT 64
82
83/* Pretend that each entry is of this size in directory's i_size */
84#define BOGO_DIRENT_SIZE 20
85
Linus Torvalds1da177e2005-04-16 15:20:36 -070086/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
87enum sgp_type {
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SGP_READ, /* don't exceed i_size, don't allocate page */
89 SGP_CACHE, /* don't exceed i_size, may allocate page */
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -080090 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 SGP_WRITE, /* may exceed i_size, may allocate page */
92};
93
Andrew Mortonb76db732008-02-08 04:21:49 -080094#ifdef CONFIG_TMPFS
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080095static unsigned long shmem_default_max_blocks(void)
96{
97 return totalram_pages / 2;
98}
99
100static unsigned long shmem_default_max_inodes(void)
101{
102 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
103}
Andrew Mortonb76db732008-02-08 04:21:49 -0800104#endif
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800105
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106static int shmem_getpage(struct inode *inode, unsigned long idx,
107 struct page **pagep, enum sgp_type sgp, int *type);
108
Al Viro6daa0e22005-10-21 03:18:50 -0400109static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110{
111 /*
112 * The above definition of ENTRIES_PER_PAGE, and the use of
113 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
114 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -0700115 *
Mel Gormane12ba742007-10-16 01:25:52 -0700116 * Mobility flags are masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 */
Mel Gormane12ba742007-10-16 01:25:52 -0700118 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
Mel Gorman769848c2007-07-17 04:03:05 -0700119 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120}
121
122static inline void shmem_dir_free(struct page *page)
123{
124 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
125}
126
127static struct page **shmem_dir_map(struct page *page)
128{
129 return (struct page **)kmap_atomic(page, KM_USER0);
130}
131
132static inline void shmem_dir_unmap(struct page **dir)
133{
134 kunmap_atomic(dir, KM_USER0);
135}
136
137static swp_entry_t *shmem_swp_map(struct page *page)
138{
139 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
140}
141
142static inline void shmem_swp_balance_unmap(void)
143{
144 /*
145 * When passing a pointer to an i_direct entry, to code which
146 * also handles indirect entries and so will shmem_swp_unmap,
147 * we must arrange for the preempt count to remain in balance.
148 * What kmap_atomic of a lowmem page does depends on config
149 * and architecture, so pretend to kmap_atomic some lowmem page.
150 */
151 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
152}
153
154static inline void shmem_swp_unmap(swp_entry_t *entry)
155{
156 kunmap_atomic(entry, KM_USER1);
157}
158
159static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
160{
161 return sb->s_fs_info;
162}
163
164/*
165 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
166 * for shared memory and for shared anonymous (/dev/zero) mappings
167 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
168 * consistent with the pre-accounting of private mappings ...
169 */
170static inline int shmem_acct_size(unsigned long flags, loff_t size)
171{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000172 return (flags & VM_NORESERVE) ?
173 0 : security_vm_enough_memory_kern(VM_ACCT(size));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174}
175
176static inline void shmem_unacct_size(unsigned long flags, loff_t size)
177{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000178 if (!(flags & VM_NORESERVE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 vm_unacct_memory(VM_ACCT(size));
180}
181
182/*
183 * ... whereas tmpfs objects are accounted incrementally as
184 * pages are allocated, in order to allow huge sparse files.
185 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
186 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
187 */
188static inline int shmem_acct_block(unsigned long flags)
189{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000190 return (flags & VM_NORESERVE) ?
191 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192}
193
194static inline void shmem_unacct_blocks(unsigned long flags, long pages)
195{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000196 if (flags & VM_NORESERVE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
198}
199
Hugh Dickins759b9772007-03-05 00:30:28 -0800200static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700201static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800202static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800203static const struct inode_operations shmem_inode_operations;
204static const struct inode_operations shmem_dir_inode_operations;
205static const struct inode_operations shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206static struct vm_operations_struct shmem_vm_ops;
207
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700208static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 .ra_pages = 0, /* No readahead */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700210 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 .unplug_io_fn = default_unplug_io_fn,
212};
213
214static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800215static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
217static void shmem_free_blocks(struct inode *inode, long pages)
218{
219 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700220 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 spin_lock(&sbinfo->stat_lock);
222 sbinfo->free_blocks += pages;
223 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
224 spin_unlock(&sbinfo->stat_lock);
225 }
226}
227
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800228static int shmem_reserve_inode(struct super_block *sb)
229{
230 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
231 if (sbinfo->max_inodes) {
232 spin_lock(&sbinfo->stat_lock);
233 if (!sbinfo->free_inodes) {
234 spin_unlock(&sbinfo->stat_lock);
235 return -ENOSPC;
236 }
237 sbinfo->free_inodes--;
238 spin_unlock(&sbinfo->stat_lock);
239 }
240 return 0;
241}
242
243static void shmem_free_inode(struct super_block *sb)
244{
245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
246 if (sbinfo->max_inodes) {
247 spin_lock(&sbinfo->stat_lock);
248 sbinfo->free_inodes++;
249 spin_unlock(&sbinfo->stat_lock);
250 }
251}
252
Randy Dunlap46711812008-03-19 17:00:41 -0700253/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 * @inode: inode to recalc
256 *
257 * We have to calculate the free blocks since the mm can drop
258 * undirtied hole pages behind our back.
259 *
260 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
261 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
262 *
263 * It has to be called with the spinlock held.
264 */
265static void shmem_recalc_inode(struct inode *inode)
266{
267 struct shmem_inode_info *info = SHMEM_I(inode);
268 long freed;
269
270 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
271 if (freed > 0) {
272 info->alloced -= freed;
273 shmem_unacct_blocks(info->flags, freed);
274 shmem_free_blocks(inode, freed);
275 }
276}
277
Randy Dunlap46711812008-03-19 17:00:41 -0700278/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 * @info: info structure for the inode
281 * @index: index of the page to find
282 * @page: optional page to add to the structure. Has to be preset to
283 * all zeros
284 *
285 * If there is no space allocated yet it will return NULL when
286 * page is NULL, else it will use the page for the needed block,
287 * setting it to NULL on return to indicate that it has been used.
288 *
289 * The swap vector is organized the following way:
290 *
291 * There are SHMEM_NR_DIRECT entries directly stored in the
292 * shmem_inode_info structure. So small files do not need an addional
293 * allocation.
294 *
295 * For pages with index > SHMEM_NR_DIRECT there is the pointer
296 * i_indirect which points to a page which holds in the first half
297 * doubly indirect blocks, in the second half triple indirect blocks:
298 *
299 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
300 * following layout (for SHMEM_NR_DIRECT == 16):
301 *
302 * i_indirect -> dir --> 16-19
303 * | +-> 20-23
304 * |
305 * +-->dir2 --> 24-27
306 * | +-> 28-31
307 * | +-> 32-35
308 * | +-> 36-39
309 * |
310 * +-->dir3 --> 40-43
311 * +-> 44-47
312 * +-> 48-51
313 * +-> 52-55
314 */
315static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
316{
317 unsigned long offset;
318 struct page **dir;
319 struct page *subdir;
320
321 if (index < SHMEM_NR_DIRECT) {
322 shmem_swp_balance_unmap();
323 return info->i_direct+index;
324 }
325 if (!info->i_indirect) {
326 if (page) {
327 info->i_indirect = *page;
328 *page = NULL;
329 }
330 return NULL; /* need another page */
331 }
332
333 index -= SHMEM_NR_DIRECT;
334 offset = index % ENTRIES_PER_PAGE;
335 index /= ENTRIES_PER_PAGE;
336 dir = shmem_dir_map(info->i_indirect);
337
338 if (index >= ENTRIES_PER_PAGE/2) {
339 index -= ENTRIES_PER_PAGE/2;
340 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
341 index %= ENTRIES_PER_PAGE;
342 subdir = *dir;
343 if (!subdir) {
344 if (page) {
345 *dir = *page;
346 *page = NULL;
347 }
348 shmem_dir_unmap(dir);
349 return NULL; /* need another page */
350 }
351 shmem_dir_unmap(dir);
352 dir = shmem_dir_map(subdir);
353 }
354
355 dir += index;
356 subdir = *dir;
357 if (!subdir) {
358 if (!page || !(subdir = *page)) {
359 shmem_dir_unmap(dir);
360 return NULL; /* need a page */
361 }
362 *dir = subdir;
363 *page = NULL;
364 }
365 shmem_dir_unmap(dir);
366 return shmem_swp_map(subdir) + offset;
367}
368
369static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
370{
371 long incdec = value? 1: -1;
372
373 entry->val = value;
374 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700375 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
376 struct page *page = kmap_atomic_to_page(entry);
377 set_page_private(page, page_private(page) + incdec);
378 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379}
380
Randy Dunlap46711812008-03-19 17:00:41 -0700381/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 * @info: info structure for the inode
384 * @index: index of the page to find
385 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700386 *
387 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 */
389static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
390{
391 struct inode *inode = &info->vfs_inode;
392 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
393 struct page *page = NULL;
394 swp_entry_t *entry;
395
396 if (sgp != SGP_WRITE &&
397 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
398 return ERR_PTR(-EINVAL);
399
400 while (!(entry = shmem_swp_entry(info, index, &page))) {
401 if (sgp == SGP_READ)
402 return shmem_swp_map(ZERO_PAGE(0));
403 /*
404 * Test free_blocks against 1 not 0, since we have 1 data
405 * page (and perhaps indirect index pages) yet to allocate:
406 * a waste to allocate index if we cannot allocate data.
407 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700408 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 spin_lock(&sbinfo->stat_lock);
410 if (sbinfo->free_blocks <= 1) {
411 spin_unlock(&sbinfo->stat_lock);
412 return ERR_PTR(-ENOSPC);
413 }
414 sbinfo->free_blocks--;
415 inode->i_blocks += BLOCKS_PER_PAGE;
416 spin_unlock(&sbinfo->stat_lock);
417 }
418
419 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700420 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700421 if (page)
422 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 spin_lock(&info->lock);
424
425 if (!page) {
426 shmem_free_blocks(inode, 1);
427 return ERR_PTR(-ENOMEM);
428 }
429 if (sgp != SGP_WRITE &&
430 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
431 entry = ERR_PTR(-EINVAL);
432 break;
433 }
434 if (info->next_index <= index)
435 info->next_index = index + 1;
436 }
437 if (page) {
438 /* another task gave its page, or truncated the file */
439 shmem_free_blocks(inode, 1);
440 shmem_dir_free(page);
441 }
442 if (info->next_index <= index && !IS_ERR(entry))
443 info->next_index = index + 1;
444 return entry;
445}
446
Randy Dunlap46711812008-03-19 17:00:41 -0700447/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 * shmem_free_swp - free some swap entries in a directory
Hugh Dickins1ae70002007-03-29 01:20:36 -0700449 * @dir: pointer to the directory
450 * @edir: pointer after last entry of the directory
451 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700453static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
454 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700456 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 swp_entry_t *ptr;
458 int freed = 0;
459
460 for (ptr = dir; ptr < edir; ptr++) {
461 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700462 if (unlikely(punch_lock)) {
463 punch_unlock = punch_lock;
464 punch_lock = NULL;
465 spin_lock(punch_unlock);
466 if (!ptr->val)
467 continue;
468 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 free_swap_and_cache(*ptr);
470 *ptr = (swp_entry_t){0};
471 freed++;
472 }
473 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700474 if (punch_unlock)
475 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 return freed;
477}
478
Hugh Dickins1ae70002007-03-29 01:20:36 -0700479static int shmem_map_and_free_swp(struct page *subdir, int offset,
480 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481{
482 swp_entry_t *ptr;
483 int freed = 0;
484
485 ptr = shmem_swp_map(subdir);
486 for (; offset < limit; offset += LATENCY_LIMIT) {
487 int size = limit - offset;
488 if (size > LATENCY_LIMIT)
489 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700490 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
491 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 if (need_resched()) {
493 shmem_swp_unmap(ptr);
494 if (*dir) {
495 shmem_dir_unmap(*dir);
496 *dir = NULL;
497 }
498 cond_resched();
499 ptr = shmem_swp_map(subdir);
500 }
501 }
502 shmem_swp_unmap(ptr);
503 return freed;
504}
505
506static void shmem_free_pages(struct list_head *next)
507{
508 struct page *page;
509 int freed = 0;
510
511 do {
512 page = container_of(next, struct page, lru);
513 next = next->next;
514 shmem_dir_free(page);
515 freed++;
516 if (freed >= LATENCY_LIMIT) {
517 cond_resched();
518 freed = 0;
519 }
520 } while (next);
521}
522
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800523static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524{
525 struct shmem_inode_info *info = SHMEM_I(inode);
526 unsigned long idx;
527 unsigned long size;
528 unsigned long limit;
529 unsigned long stage;
530 unsigned long diroff;
531 struct page **dir;
532 struct page *topdir;
533 struct page *middir;
534 struct page *subdir;
535 swp_entry_t *ptr;
536 LIST_HEAD(pages_to_free);
537 long nr_pages_to_free = 0;
538 long nr_swaps_freed = 0;
539 int offset;
540 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700541 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700542 spinlock_t *needs_lock;
543 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700544 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
546 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800547 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 if (idx >= info->next_index)
549 return;
550
551 spin_lock(&info->lock);
552 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800553 if (likely(end == (loff_t) -1)) {
554 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700555 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800556 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700557 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700558 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800559 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700560 if (end + 1 >= inode->i_size) { /* we may free a little more */
561 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
562 PAGE_CACHE_SHIFT;
563 upper_limit = SHMEM_MAX_INDEX;
564 } else {
565 limit = (end + 1) >> PAGE_CACHE_SHIFT;
566 upper_limit = limit;
567 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700568 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800569 punch_hole = 1;
570 }
571
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800573 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 info->i_indirect = NULL;
575 nr_pages_to_free++;
576 list_add(&topdir->lru, &pages_to_free);
577 }
578 spin_unlock(&info->lock);
579
580 if (info->swapped && idx < SHMEM_NR_DIRECT) {
581 ptr = info->i_direct;
582 size = limit;
583 if (size > SHMEM_NR_DIRECT)
584 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700585 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800587
588 /*
589 * If there are no indirect blocks or we are punching a hole
590 * below indirect blocks, nothing to be done.
591 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700592 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 goto done2;
594
Hugh Dickins1ae70002007-03-29 01:20:36 -0700595 /*
596 * The truncation case has already dropped info->lock, and we're safe
597 * because i_size and next_index have already been lowered, preventing
598 * access beyond. But in the punch_hole case, we still need to take
599 * the lock when updating the swap directory, because there might be
600 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
601 * shmem_writepage. However, whenever we find we can remove a whole
602 * directory page (not at the misaligned start or end of the range),
603 * we first NULLify its pointer in the level above, and then have no
604 * need to take the lock when updating its contents: needs_lock and
605 * punch_lock (either pointing to info->lock or NULL) manage this.
606 */
607
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700608 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 limit -= SHMEM_NR_DIRECT;
610 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
611 offset = idx % ENTRIES_PER_PAGE;
612 idx -= offset;
613
614 dir = shmem_dir_map(topdir);
615 stage = ENTRIES_PER_PAGEPAGE/2;
616 if (idx < ENTRIES_PER_PAGEPAGE/2) {
617 middir = topdir;
618 diroff = idx/ENTRIES_PER_PAGE;
619 } else {
620 dir += ENTRIES_PER_PAGE/2;
621 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
622 while (stage <= idx)
623 stage += ENTRIES_PER_PAGEPAGE;
624 middir = *dir;
625 if (*dir) {
626 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
627 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700628 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700629 if (needs_lock) {
630 spin_lock(needs_lock);
631 *dir = NULL;
632 spin_unlock(needs_lock);
633 needs_lock = NULL;
634 } else
635 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 nr_pages_to_free++;
637 list_add(&middir->lru, &pages_to_free);
638 }
639 shmem_dir_unmap(dir);
640 dir = shmem_dir_map(middir);
641 } else {
642 diroff = 0;
643 offset = 0;
644 idx = stage;
645 }
646 }
647
648 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
649 if (unlikely(idx == stage)) {
650 shmem_dir_unmap(dir);
651 dir = shmem_dir_map(topdir) +
652 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
653 while (!*dir) {
654 dir++;
655 idx += ENTRIES_PER_PAGEPAGE;
656 if (idx >= limit)
657 goto done1;
658 }
659 stage = idx + ENTRIES_PER_PAGEPAGE;
660 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700661 if (punch_hole)
662 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700663 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700664 if (needs_lock) {
665 spin_lock(needs_lock);
666 *dir = NULL;
667 spin_unlock(needs_lock);
668 needs_lock = NULL;
669 } else
670 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700671 nr_pages_to_free++;
672 list_add(&middir->lru, &pages_to_free);
673 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 shmem_dir_unmap(dir);
675 cond_resched();
676 dir = shmem_dir_map(middir);
677 diroff = 0;
678 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700679 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700681 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
682 if (needs_lock) {
683 spin_lock(needs_lock);
684 dir[diroff] = NULL;
685 spin_unlock(needs_lock);
686 punch_lock = NULL;
687 } else
688 dir[diroff] = NULL;
689 nr_pages_to_free++;
690 list_add(&subdir->lru, &pages_to_free);
691 }
692 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 size = limit - idx;
694 if (size > ENTRIES_PER_PAGE)
695 size = ENTRIES_PER_PAGE;
696 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700697 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 if (!dir)
699 dir = shmem_dir_map(middir);
700 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700701 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700703 set_page_private(subdir,
704 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700706 } else
707 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700709 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 }
711done1:
712 shmem_dir_unmap(dir);
713done2:
714 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
715 /*
716 * Call truncate_inode_pages again: racing shmem_unuse_inode
717 * may have swizzled a page in from swap since vmtruncate or
718 * generic_delete_inode did it, before we lowered next_index.
719 * Also, though shmem_getpage checks i_size before adding to
720 * cache, no recheck after: so fix the narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700721 *
722 * Recalling truncate_inode_pages_range and unmap_mapping_range
723 * every time for punch_hole (which never got a chance to clear
724 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
725 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800727 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700728 if (punch_hole)
729 unmap_mapping_range(inode->i_mapping, start,
730 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 }
732
733 spin_lock(&info->lock);
734 info->flags &= ~SHMEM_TRUNCATE;
735 info->swapped -= nr_swaps_freed;
736 if (nr_pages_to_free)
737 shmem_free_blocks(inode, nr_pages_to_free);
738 shmem_recalc_inode(inode);
739 spin_unlock(&info->lock);
740
741 /*
742 * Empty swap vector directory pages to be freed?
743 */
744 if (!list_empty(&pages_to_free)) {
745 pages_to_free.prev->next = NULL;
746 shmem_free_pages(pages_to_free.next);
747 }
748}
749
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800750static void shmem_truncate(struct inode *inode)
751{
752 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
753}
754
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
756{
757 struct inode *inode = dentry->d_inode;
758 struct page *page = NULL;
759 int error;
760
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700761 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 if (attr->ia_size < inode->i_size) {
763 /*
764 * If truncating down to a partial page, then
765 * if that page is already allocated, hold it
766 * in memory until the truncation is over, so
767 * truncate_partial_page cannnot miss it were
768 * it assigned to swap.
769 */
770 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
771 (void) shmem_getpage(inode,
772 attr->ia_size>>PAGE_CACHE_SHIFT,
773 &page, SGP_READ, NULL);
Hugh Dickinsd3602442008-02-04 22:28:44 -0800774 if (page)
775 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 }
777 /*
778 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
779 * detect if any pages might have been added to cache
780 * after truncate_inode_pages. But we needn't bother
781 * if it's being fully truncated to zero-length: the
782 * nrpages check is efficient enough in that case.
783 */
784 if (attr->ia_size) {
785 struct shmem_inode_info *info = SHMEM_I(inode);
786 spin_lock(&info->lock);
787 info->flags &= ~SHMEM_PAGEIN;
788 spin_unlock(&info->lock);
789 }
790 }
791 }
792
793 error = inode_change_ok(inode, attr);
794 if (!error)
795 error = inode_setattr(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700796#ifdef CONFIG_TMPFS_POSIX_ACL
797 if (!error && (attr->ia_valid & ATTR_MODE))
798 error = generic_acl_chmod(inode, &shmem_acl_ops);
799#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 if (page)
801 page_cache_release(page);
802 return error;
803}
804
805static void shmem_delete_inode(struct inode *inode)
806{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 struct shmem_inode_info *info = SHMEM_I(inode);
808
809 if (inode->i_op->truncate == shmem_truncate) {
Mark Fashehfef26652005-09-09 13:01:31 -0700810 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 shmem_unacct_size(info->flags, inode->i_size);
812 inode->i_size = 0;
813 shmem_truncate(inode);
814 if (!list_empty(&info->swaplist)) {
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800815 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 list_del_init(&info->swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800817 mutex_unlock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 }
819 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700820 BUG_ON(inode->i_blocks);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800821 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 clear_inode(inode);
823}
824
825static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
826{
827 swp_entry_t *ptr;
828
829 for (ptr = dir; ptr < edir; ptr++) {
830 if (ptr->val == entry.val)
831 return ptr - dir;
832 }
833 return -1;
834}
835
836static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
837{
838 struct inode *inode;
839 unsigned long idx;
840 unsigned long size;
841 unsigned long limit;
842 unsigned long stage;
843 struct page **dir;
844 struct page *subdir;
845 swp_entry_t *ptr;
846 int offset;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800847 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848
849 idx = 0;
850 ptr = info->i_direct;
851 spin_lock(&info->lock);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800852 if (!info->swapped) {
853 list_del_init(&info->swaplist);
854 goto lost2;
855 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 limit = info->next_index;
857 size = limit;
858 if (size > SHMEM_NR_DIRECT)
859 size = SHMEM_NR_DIRECT;
860 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800861 if (offset >= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 goto found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 if (!info->i_indirect)
864 goto lost2;
865
866 dir = shmem_dir_map(info->i_indirect);
867 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
868
869 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
870 if (unlikely(idx == stage)) {
871 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800872 if (cond_resched_lock(&info->lock)) {
873 /* check it has not been truncated */
874 if (limit > info->next_index) {
875 limit = info->next_index;
876 if (idx >= limit)
877 goto lost2;
878 }
879 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 dir = shmem_dir_map(info->i_indirect) +
881 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
882 while (!*dir) {
883 dir++;
884 idx += ENTRIES_PER_PAGEPAGE;
885 if (idx >= limit)
886 goto lost1;
887 }
888 stage = idx + ENTRIES_PER_PAGEPAGE;
889 subdir = *dir;
890 shmem_dir_unmap(dir);
891 dir = shmem_dir_map(subdir);
892 }
893 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700894 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 ptr = shmem_swp_map(subdir);
896 size = limit - idx;
897 if (size > ENTRIES_PER_PAGE)
898 size = ENTRIES_PER_PAGE;
899 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800900 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 if (offset >= 0) {
902 shmem_dir_unmap(dir);
903 goto found;
904 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 }
906 }
907lost1:
908 shmem_dir_unmap(dir-1);
909lost2:
910 spin_unlock(&info->lock);
911 return 0;
912found:
913 idx += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800914 inode = igrab(&info->vfs_inode);
915 spin_unlock(&info->lock);
916
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800917 /*
918 * Move _head_ to start search for next from here.
919 * But be careful: shmem_delete_inode checks list_empty without taking
920 * mutex, and there's an instant in list_move_tail when info->swaplist
921 * would appear empty, if it were the only one on shmem_swaplist. We
922 * could avoid doing it if inode NULL; or use this minor optimization.
923 */
924 if (shmem_swaplist.next != &info->swaplist)
925 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800926 mutex_unlock(&shmem_swaplist_mutex);
927
928 error = 1;
929 if (!inode)
930 goto out;
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800931 /*
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -0800932 * Charge page using GFP_KERNEL while we can wait.
933 * Charged back to the user(not to caller) when swap account is used.
934 * add_to_page_cache() will be called with GFP_NOWAIT.
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800935 */
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -0800936 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800937 if (error)
938 goto out;
Hugh Dickins82369552008-02-07 00:14:22 -0800939 error = radix_tree_preload(GFP_KERNEL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700940 if (error) {
941 mem_cgroup_uncharge_cache_page(page);
942 goto out;
943 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800944 error = 1;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800945
946 spin_lock(&info->lock);
947 ptr = shmem_swp_entry(info, idx, NULL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700948 if (ptr && ptr->val == entry.val) {
Nick Piggine2867812008-07-25 19:45:30 -0700949 error = add_to_page_cache_locked(page, inode->i_mapping,
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800950 idx, GFP_NOWAIT);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700951 /* does mem_cgroup_uncharge_cache_page on error */
952 } else /* we must compensate for our precharge above */
953 mem_cgroup_uncharge_cache_page(page);
954
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800955 if (error == -EEXIST) {
956 struct page *filepage = find_get_page(inode->i_mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800957 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800958 if (filepage) {
959 /*
960 * There might be a more uptodate page coming down
961 * from a stacked writepage: forget our swappage if so.
962 */
963 if (PageUptodate(filepage))
964 error = 0;
965 page_cache_release(filepage);
966 }
967 }
968 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800969 delete_from_swap_cache(page);
970 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800972 shmem_swp_set(info, ptr, 0);
973 swap_free(entry);
974 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800976 if (ptr)
977 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 spin_unlock(&info->lock);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800979 radix_tree_preload_end();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800980out:
981 unlock_page(page);
982 page_cache_release(page);
983 iput(inode); /* allows for NULL */
984 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985}
986
987/*
988 * shmem_unuse() search for an eventually swapped out shmem page.
989 */
990int shmem_unuse(swp_entry_t entry, struct page *page)
991{
992 struct list_head *p, *next;
993 struct shmem_inode_info *info;
994 int found = 0;
995
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800996 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700997 list_for_each_safe(p, next, &shmem_swaplist) {
998 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800999 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001000 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001001 if (found)
1002 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001004 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001005out: return found; /* 0 or 1 or -ENOMEM */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001006}
1007
1008/*
1009 * Move the page from the page cache to the swap cache.
1010 */
1011static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1012{
1013 struct shmem_inode_info *info;
1014 swp_entry_t *entry, swap;
1015 struct address_space *mapping;
1016 unsigned long index;
1017 struct inode *inode;
1018
1019 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 mapping = page->mapping;
1021 index = page->index;
1022 inode = mapping->host;
1023 info = SHMEM_I(inode);
1024 if (info->flags & VM_LOCKED)
1025 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001026 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001027 goto redirty;
1028
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001029 /*
1030 * shmem_backing_dev_info's capabilities prevent regular writeback or
1031 * sync from ever calling shmem_writepage; but a stacking filesystem
1032 * may use the ->writepage of its underlying filesystem, in which case
1033 * tmpfs should write out to swap only in response to memory pressure,
1034 * and not for pdflush or sync. However, in those cases, we do still
1035 * want to check if there's a redundant swappage to be discarded.
1036 */
1037 if (wbc->for_reclaim)
1038 swap = get_swap_page();
1039 else
1040 swap.val = 0;
1041
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042 spin_lock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 if (index >= info->next_index) {
1044 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1045 goto unlock;
1046 }
1047 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001048 if (entry->val) {
1049 /*
1050 * The more uptodate page coming down from a stacked
1051 * writepage should replace our old swappage.
1052 */
1053 free_swap_and_cache(*entry);
1054 shmem_swp_set(info, entry, 0);
1055 }
1056 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001057
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001058 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Hugh Dickins73b12622008-02-04 22:28:50 -08001059 remove_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001060 shmem_swp_set(info, entry, swap.val);
1061 shmem_swp_unmap(entry);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001062 if (list_empty(&info->swaplist))
1063 inode = igrab(inode);
1064 else
1065 inode = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001066 spin_unlock(&info->lock);
Hugh Dickins73b12622008-02-04 22:28:50 -08001067 swap_duplicate(swap);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001068 BUG_ON(page_mapped(page));
Hugh Dickins73b12622008-02-04 22:28:50 -08001069 page_cache_release(page); /* pagecache ref */
1070 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071 unlock_page(page);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001072 if (inode) {
1073 mutex_lock(&shmem_swaplist_mutex);
1074 /* move instead of add in case we're racing */
1075 list_move_tail(&info->swaplist, &shmem_swaplist);
1076 mutex_unlock(&shmem_swaplist_mutex);
1077 iput(inode);
1078 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001079 return 0;
1080 }
1081
1082 shmem_swp_unmap(entry);
1083unlock:
1084 spin_unlock(&info->lock);
1085 swap_free(swap);
1086redirty:
1087 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001088 if (wbc->for_reclaim)
1089 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1090 unlock_page(page);
1091 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001092}
1093
1094#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001095#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001096static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001097{
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001098 char buffer[64];
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001099
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001100 if (!mpol || mpol->mode == MPOL_DEFAULT)
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001101 return; /* show nothing */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001102
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001103 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001104
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001105 seq_printf(seq, ",mpol=%s", buffer);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001106}
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001107
1108static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1109{
1110 struct mempolicy *mpol = NULL;
1111 if (sbinfo->mpol) {
1112 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1113 mpol = sbinfo->mpol;
1114 mpol_get(mpol);
1115 spin_unlock(&sbinfo->stat_lock);
1116 }
1117 return mpol;
1118}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001119#endif /* CONFIG_TMPFS */
1120
Hugh Dickins02098fe2008-02-04 22:28:42 -08001121static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1122 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123{
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001124 struct mempolicy mpol, *spol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001126 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001128 spol = mpol_cond_copy(&mpol,
1129 mpol_shared_policy_lookup(&info->policy, idx));
1130
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001132 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001134 pvma.vm_ops = NULL;
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001135 pvma.vm_policy = spol;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001136 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137 return page;
1138}
1139
Hugh Dickins02098fe2008-02-04 22:28:42 -08001140static struct page *shmem_alloc_page(gfp_t gfp,
1141 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142{
1143 struct vm_area_struct pvma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001144
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001145 /* Create a pseudo vma that just contains the policy */
1146 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001147 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001148 pvma.vm_ops = NULL;
1149 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001150
1151 /*
1152 * alloc_page_vma() will drop the shared policy reference
1153 */
1154 return alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001156#else /* !CONFIG_NUMA */
1157#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001158static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001159{
1160}
1161#endif /* CONFIG_TMPFS */
1162
Hugh Dickins02098fe2008-02-04 22:28:42 -08001163static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1164 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001166 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167}
1168
Hugh Dickins02098fe2008-02-04 22:28:42 -08001169static inline struct page *shmem_alloc_page(gfp_t gfp,
1170 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001172 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001174#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001176#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1177static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1178{
1179 return NULL;
1180}
1181#endif
1182
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183/*
1184 * shmem_getpage - either get the page from swap or allocate a new one
1185 *
1186 * If we allocate a new one we do not mark it dirty. That's up to the
1187 * vm. If we swap it in we mark it dirty since we also free the swap
1188 * entry since a page cannot live in both the swap and page cache
1189 */
1190static int shmem_getpage(struct inode *inode, unsigned long idx,
1191 struct page **pagep, enum sgp_type sgp, int *type)
1192{
1193 struct address_space *mapping = inode->i_mapping;
1194 struct shmem_inode_info *info = SHMEM_I(inode);
1195 struct shmem_sb_info *sbinfo;
1196 struct page *filepage = *pagep;
1197 struct page *swappage;
1198 swp_entry_t *entry;
1199 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001200 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 int error;
1202
1203 if (idx >= SHMEM_MAX_INDEX)
1204 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001205
1206 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001207 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001208
Linus Torvalds1da177e2005-04-16 15:20:36 -07001209 /*
1210 * Normally, filepage is NULL on entry, and either found
1211 * uptodate immediately, or allocated and zeroed, or read
1212 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001213 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae976412007-06-04 10:00:39 +02001214 * filepage, which may be found not uptodate by other callers
1215 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216 */
1217repeat:
1218 if (!filepage)
1219 filepage = find_lock_page(mapping, idx);
1220 if (filepage && PageUptodate(filepage))
1221 goto done;
1222 error = 0;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001223 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001224 if (!filepage) {
1225 /*
1226 * Try to preload while we can wait, to not make a habit of
1227 * draining atomic reserves; but don't latch on to this cpu.
1228 */
1229 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1230 if (error)
1231 goto failed;
1232 radix_tree_preload_end();
1233 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234
1235 spin_lock(&info->lock);
1236 shmem_recalc_inode(inode);
1237 entry = shmem_swp_alloc(info, idx, sgp);
1238 if (IS_ERR(entry)) {
1239 spin_unlock(&info->lock);
1240 error = PTR_ERR(entry);
1241 goto failed;
1242 }
1243 swap = *entry;
1244
1245 if (swap.val) {
1246 /* Look it up and read it in.. */
1247 swappage = lookup_swap_cache(swap);
1248 if (!swappage) {
1249 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001251 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001252 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001253 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001254 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001255 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001256 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 if (!swappage) {
1258 spin_lock(&info->lock);
1259 entry = shmem_swp_alloc(info, idx, sgp);
1260 if (IS_ERR(entry))
1261 error = PTR_ERR(entry);
1262 else {
1263 if (entry->val == swap.val)
1264 error = -ENOMEM;
1265 shmem_swp_unmap(entry);
1266 }
1267 spin_unlock(&info->lock);
1268 if (error)
1269 goto failed;
1270 goto repeat;
1271 }
1272 wait_on_page_locked(swappage);
1273 page_cache_release(swappage);
1274 goto repeat;
1275 }
1276
1277 /* We have to do this with page locked to prevent races */
Nick Piggin529ae9a2008-08-02 12:01:03 +02001278 if (!trylock_page(swappage)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279 shmem_swp_unmap(entry);
1280 spin_unlock(&info->lock);
1281 wait_on_page_locked(swappage);
1282 page_cache_release(swappage);
1283 goto repeat;
1284 }
1285 if (PageWriteback(swappage)) {
1286 shmem_swp_unmap(entry);
1287 spin_unlock(&info->lock);
1288 wait_on_page_writeback(swappage);
1289 unlock_page(swappage);
1290 page_cache_release(swappage);
1291 goto repeat;
1292 }
1293 if (!PageUptodate(swappage)) {
1294 shmem_swp_unmap(entry);
1295 spin_unlock(&info->lock);
1296 unlock_page(swappage);
1297 page_cache_release(swappage);
1298 error = -EIO;
1299 goto failed;
1300 }
1301
1302 if (filepage) {
1303 shmem_swp_set(info, entry, 0);
1304 shmem_swp_unmap(entry);
1305 delete_from_swap_cache(swappage);
1306 spin_unlock(&info->lock);
1307 copy_highpage(filepage, swappage);
1308 unlock_page(swappage);
1309 page_cache_release(swappage);
1310 flush_dcache_page(filepage);
1311 SetPageUptodate(filepage);
1312 set_page_dirty(filepage);
1313 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -07001314 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1315 idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 info->flags |= SHMEM_PAGEIN;
1317 shmem_swp_set(info, entry, 0);
1318 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001319 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320 spin_unlock(&info->lock);
1321 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001322 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323 swap_free(swap);
1324 } else {
1325 shmem_swp_unmap(entry);
1326 spin_unlock(&info->lock);
Hugh Dickins82369552008-02-07 00:14:22 -08001327 if (error == -ENOMEM) {
1328 /* allow reclaim from this memory cgroup */
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001329 error = mem_cgroup_shrink_usage(swappage,
1330 current->mm,
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001331 gfp);
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001332 if (error) {
1333 unlock_page(swappage);
1334 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001335 goto failed;
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001336 }
Hugh Dickins82369552008-02-07 00:14:22 -08001337 }
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001338 unlock_page(swappage);
1339 page_cache_release(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 goto repeat;
1341 }
1342 } else if (sgp == SGP_READ && !filepage) {
1343 shmem_swp_unmap(entry);
1344 filepage = find_get_page(mapping, idx);
1345 if (filepage &&
Nick Piggin529ae9a2008-08-02 12:01:03 +02001346 (!PageUptodate(filepage) || !trylock_page(filepage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001347 spin_unlock(&info->lock);
1348 wait_on_page_locked(filepage);
1349 page_cache_release(filepage);
1350 filepage = NULL;
1351 goto repeat;
1352 }
1353 spin_unlock(&info->lock);
1354 } else {
1355 shmem_swp_unmap(entry);
1356 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001357 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 spin_lock(&sbinfo->stat_lock);
1359 if (sbinfo->free_blocks == 0 ||
1360 shmem_acct_block(info->flags)) {
1361 spin_unlock(&sbinfo->stat_lock);
1362 spin_unlock(&info->lock);
1363 error = -ENOSPC;
1364 goto failed;
1365 }
1366 sbinfo->free_blocks--;
1367 inode->i_blocks += BLOCKS_PER_PAGE;
1368 spin_unlock(&sbinfo->stat_lock);
1369 } else if (shmem_acct_block(info->flags)) {
1370 spin_unlock(&info->lock);
1371 error = -ENOSPC;
1372 goto failed;
1373 }
1374
1375 if (!filepage) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001376 int ret;
1377
Linus Torvalds1da177e2005-04-16 15:20:36 -07001378 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001379 filepage = shmem_alloc_page(gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380 if (!filepage) {
1381 shmem_unacct_blocks(info->flags, 1);
1382 shmem_free_blocks(inode, 1);
1383 error = -ENOMEM;
1384 goto failed;
1385 }
Rik van Rielb2e18532008-10-18 20:26:30 -07001386 SetPageSwapBacked(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001387
Hugh Dickins82369552008-02-07 00:14:22 -08001388 /* Precharge page while we can wait, compensate after */
1389 error = mem_cgroup_cache_charge(filepage, current->mm,
KAMEZAWA Hiroyuki2c26fdd2009-01-07 18:08:10 -08001390 GFP_KERNEL);
Hugh Dickins82369552008-02-07 00:14:22 -08001391 if (error) {
1392 page_cache_release(filepage);
1393 shmem_unacct_blocks(info->flags, 1);
1394 shmem_free_blocks(inode, 1);
1395 filepage = NULL;
1396 goto failed;
1397 }
1398
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 spin_lock(&info->lock);
1400 entry = shmem_swp_alloc(info, idx, sgp);
1401 if (IS_ERR(entry))
1402 error = PTR_ERR(entry);
1403 else {
1404 swap = *entry;
1405 shmem_swp_unmap(entry);
1406 }
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001407 ret = error || swap.val;
1408 if (ret)
1409 mem_cgroup_uncharge_cache_page(filepage);
1410 else
1411 ret = add_to_page_cache_lru(filepage, mapping,
1412 idx, GFP_NOWAIT);
1413 /*
1414 * At add_to_page_cache_lru() failure, uncharge will
1415 * be done automatically.
1416 */
1417 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 spin_unlock(&info->lock);
1419 page_cache_release(filepage);
1420 shmem_unacct_blocks(info->flags, 1);
1421 shmem_free_blocks(inode, 1);
1422 filepage = NULL;
1423 if (error)
1424 goto failed;
1425 goto repeat;
1426 }
1427 info->flags |= SHMEM_PAGEIN;
1428 }
1429
1430 info->alloced++;
1431 spin_unlock(&info->lock);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001432 clear_highpage(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 flush_dcache_page(filepage);
1434 SetPageUptodate(filepage);
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001435 if (sgp == SGP_DIRTY)
1436 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 }
1438done:
Hugh Dickinsd3602442008-02-04 22:28:44 -08001439 *pagep = filepage;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001440 return 0;
1441
1442failed:
1443 if (*pagep != filepage) {
1444 unlock_page(filepage);
1445 page_cache_release(filepage);
1446 }
1447 return error;
1448}
1449
Nick Piggind0217ac2007-07-19 01:47:03 -07001450static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001452 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001454 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455
Nick Piggind0217ac2007-07-19 01:47:03 -07001456 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1457 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001458
Hugh Dickins27d54b32008-02-04 22:28:43 -08001459 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001460 if (error)
1461 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462
Nick Piggin83c54072007-07-19 01:47:05 -07001463 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464}
1465
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001467static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001468{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001469 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001470 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1471}
1472
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001473static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1474 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001476 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 unsigned long idx;
1478
1479 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1480 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1481}
1482#endif
1483
1484int shmem_lock(struct file *file, int lock, struct user_struct *user)
1485{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001486 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001487 struct shmem_inode_info *info = SHMEM_I(inode);
1488 int retval = -ENOMEM;
1489
1490 spin_lock(&info->lock);
1491 if (lock && !(info->flags & VM_LOCKED)) {
1492 if (!user_shm_lock(inode->i_size, user))
1493 goto out_nomem;
1494 info->flags |= VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001495 mapping_set_unevictable(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 }
1497 if (!lock && (info->flags & VM_LOCKED) && user) {
1498 user_shm_unlock(inode->i_size, user);
1499 info->flags &= ~VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001500 mapping_clear_unevictable(file->f_mapping);
1501 scan_mapping_unevictable_pages(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 }
1503 retval = 0;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001504
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505out_nomem:
1506 spin_unlock(&info->lock);
1507 return retval;
1508}
1509
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001510static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001511{
1512 file_accessed(file);
1513 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001514 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 return 0;
1516}
1517
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001518static struct inode *shmem_get_inode(struct super_block *sb, int mode,
1519 dev_t dev, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001520{
1521 struct inode *inode;
1522 struct shmem_inode_info *info;
1523 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1524
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001525 if (shmem_reserve_inode(sb))
1526 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527
1528 inode = new_inode(sb);
1529 if (inode) {
1530 inode->i_mode = mode;
David Howells76aac0e2008-11-14 10:39:12 +11001531 inode->i_uid = current_fsuid();
1532 inode->i_gid = current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001533 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1535 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001536 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 info = SHMEM_I(inode);
1538 memset(info, 0, (char *)inode - (char *)info);
1539 spin_lock_init(&info->lock);
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001540 info->flags = flags & VM_NORESERVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 INIT_LIST_HEAD(&info->swaplist);
1542
1543 switch (mode & S_IFMT) {
1544 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001545 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 init_special_inode(inode, mode, dev);
1547 break;
1548 case S_IFREG:
Hugh Dickins14fcc232008-07-28 15:46:19 -07001549 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 inode->i_op = &shmem_inode_operations;
1551 inode->i_fop = &shmem_file_operations;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001552 mpol_shared_policy_init(&info->policy,
1553 shmem_get_sbmpol(sbinfo));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 break;
1555 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001556 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557 /* Some things misbehave if size == 0 on a directory */
1558 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1559 inode->i_op = &shmem_dir_inode_operations;
1560 inode->i_fop = &simple_dir_operations;
1561 break;
1562 case S_IFLNK:
1563 /*
1564 * Must not load anything in the rbtree,
1565 * mpol_free_shared_policy will not be called.
1566 */
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001567 mpol_shared_policy_init(&info->policy, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 break;
1569 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001570 } else
1571 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001572 return inode;
1573}
1574
1575#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001576static const struct inode_operations shmem_symlink_inode_operations;
1577static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578
1579/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001580 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae976412007-06-04 10:00:39 +02001581 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1582 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001584static int shmem_readpage(struct file *file, struct page *page)
1585{
1586 struct inode *inode = page->mapping->host;
1587 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1588 unlock_page(page);
1589 return error;
1590}
1591
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001593shmem_write_begin(struct file *file, struct address_space *mapping,
1594 loff_t pos, unsigned len, unsigned flags,
1595 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596{
Nick Piggin800d15a2007-10-16 01:25:03 -07001597 struct inode *inode = mapping->host;
1598 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1599 *pagep = NULL;
1600 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1601}
1602
1603static int
1604shmem_write_end(struct file *file, struct address_space *mapping,
1605 loff_t pos, unsigned len, unsigned copied,
1606 struct page *page, void *fsdata)
1607{
1608 struct inode *inode = mapping->host;
1609
Hugh Dickinsd3602442008-02-04 22:28:44 -08001610 if (pos + copied > inode->i_size)
1611 i_size_write(inode, pos + copied);
1612
1613 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001614 set_page_dirty(page);
1615 page_cache_release(page);
1616
Nick Piggin800d15a2007-10-16 01:25:03 -07001617 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618}
1619
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1621{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001622 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 struct address_space *mapping = inode->i_mapping;
1624 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001625 enum sgp_type sgp = SGP_READ;
1626
1627 /*
1628 * Might this read be for a stacking filesystem? Then when reading
1629 * holes of a sparse file, we actually need to allocate those pages,
1630 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1631 */
1632 if (segment_eq(get_fs(), KERNEL_DS))
1633 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634
1635 index = *ppos >> PAGE_CACHE_SHIFT;
1636 offset = *ppos & ~PAGE_CACHE_MASK;
1637
1638 for (;;) {
1639 struct page *page = NULL;
1640 unsigned long end_index, nr, ret;
1641 loff_t i_size = i_size_read(inode);
1642
1643 end_index = i_size >> PAGE_CACHE_SHIFT;
1644 if (index > end_index)
1645 break;
1646 if (index == end_index) {
1647 nr = i_size & ~PAGE_CACHE_MASK;
1648 if (nr <= offset)
1649 break;
1650 }
1651
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001652 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001653 if (desc->error) {
1654 if (desc->error == -EINVAL)
1655 desc->error = 0;
1656 break;
1657 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001658 if (page)
1659 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660
1661 /*
1662 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001663 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 */
1665 nr = PAGE_CACHE_SIZE;
1666 i_size = i_size_read(inode);
1667 end_index = i_size >> PAGE_CACHE_SHIFT;
1668 if (index == end_index) {
1669 nr = i_size & ~PAGE_CACHE_MASK;
1670 if (nr <= offset) {
1671 if (page)
1672 page_cache_release(page);
1673 break;
1674 }
1675 }
1676 nr -= offset;
1677
1678 if (page) {
1679 /*
1680 * If users can be writing to this page using arbitrary
1681 * virtual addresses, take care about potential aliasing
1682 * before reading the page on the kernel side.
1683 */
1684 if (mapping_writably_mapped(mapping))
1685 flush_dcache_page(page);
1686 /*
1687 * Mark the page accessed if we read the beginning.
1688 */
1689 if (!offset)
1690 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001691 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001693 page_cache_get(page);
1694 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695
1696 /*
1697 * Ok, we have the page, and it's up-to-date, so
1698 * now we can copy it to user space...
1699 *
1700 * The actor routine returns how many bytes were actually used..
1701 * NOTE! This may not be the same as how much of a user buffer
1702 * we filled up (we may be padding etc), so we can only update
1703 * "pos" here (the actor routine has to update the user buffer
1704 * pointers and the remaining count).
1705 */
1706 ret = actor(desc, page, offset, nr);
1707 offset += ret;
1708 index += offset >> PAGE_CACHE_SHIFT;
1709 offset &= ~PAGE_CACHE_MASK;
1710
1711 page_cache_release(page);
1712 if (ret != nr || !desc->count)
1713 break;
1714
1715 cond_resched();
1716 }
1717
1718 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1719 file_accessed(filp);
1720}
1721
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001722static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1723 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001724{
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001725 struct file *filp = iocb->ki_filp;
1726 ssize_t retval;
1727 unsigned long seg;
1728 size_t count;
1729 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001731 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1732 if (retval)
1733 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001734
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001735 for (seg = 0; seg < nr_segs; seg++) {
1736 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001738 desc.written = 0;
1739 desc.arg.buf = iov[seg].iov_base;
1740 desc.count = iov[seg].iov_len;
1741 if (desc.count == 0)
1742 continue;
1743 desc.error = 0;
1744 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1745 retval += desc.written;
1746 if (desc.error) {
1747 retval = retval ?: desc.error;
1748 break;
1749 }
1750 if (desc.count > 0)
1751 break;
1752 }
1753 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001754}
1755
David Howells726c3342006-06-23 02:02:58 -07001756static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001757{
David Howells726c3342006-06-23 02:02:58 -07001758 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001759
1760 buf->f_type = TMPFS_MAGIC;
1761 buf->f_bsize = PAGE_CACHE_SIZE;
1762 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001763 spin_lock(&sbinfo->stat_lock);
1764 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 buf->f_blocks = sbinfo->max_blocks;
1766 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001767 }
1768 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 buf->f_files = sbinfo->max_inodes;
1770 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 }
1772 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001773 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774 return 0;
1775}
1776
1777/*
1778 * File creation. Allocate an inode, and we're done..
1779 */
1780static int
1781shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1782{
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001783 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 int error = -ENOSPC;
1785
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001786 inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001788 error = security_inode_init_security(inode, dir, NULL, NULL,
1789 NULL);
1790 if (error) {
1791 if (error != -EOPNOTSUPP) {
1792 iput(inode);
1793 return error;
1794 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001795 }
1796 error = shmem_acl_init(inode, dir);
1797 if (error) {
1798 iput(inode);
1799 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001800 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801 if (dir->i_mode & S_ISGID) {
1802 inode->i_gid = dir->i_gid;
1803 if (S_ISDIR(mode))
1804 inode->i_mode |= S_ISGID;
1805 }
1806 dir->i_size += BOGO_DIRENT_SIZE;
1807 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1808 d_instantiate(dentry, inode);
1809 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001810 }
1811 return error;
1812}
1813
1814static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1815{
1816 int error;
1817
1818 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1819 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001820 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001821 return 0;
1822}
1823
1824static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1825 struct nameidata *nd)
1826{
1827 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1828}
1829
1830/*
1831 * Link a file..
1832 */
1833static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1834{
1835 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001836 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001837
1838 /*
1839 * No ordinary (disk based) filesystem counts links as inodes;
1840 * but each new link needs a new dentry, pinning lowmem, and
1841 * tmpfs dentries cannot be pruned until they are unlinked.
1842 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001843 ret = shmem_reserve_inode(inode->i_sb);
1844 if (ret)
1845 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846
1847 dir->i_size += BOGO_DIRENT_SIZE;
1848 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001849 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001850 atomic_inc(&inode->i_count); /* New dentry reference */
1851 dget(dentry); /* Extra pinning count for the created dentry */
1852 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001853out:
1854 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001855}
1856
1857static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1858{
1859 struct inode *inode = dentry->d_inode;
1860
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001861 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1862 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863
1864 dir->i_size -= BOGO_DIRENT_SIZE;
1865 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001866 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001867 dput(dentry); /* Undo the count from "create" - this does all the work */
1868 return 0;
1869}
1870
1871static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1872{
1873 if (!simple_empty(dentry))
1874 return -ENOTEMPTY;
1875
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001876 drop_nlink(dentry->d_inode);
1877 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 return shmem_unlink(dir, dentry);
1879}
1880
1881/*
1882 * The VFS layer already does all the dentry stuff for rename,
1883 * we just have to decrement the usage count for the target if
1884 * it exists so that the VFS layer correctly free's it when it
1885 * gets overwritten.
1886 */
1887static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1888{
1889 struct inode *inode = old_dentry->d_inode;
1890 int they_are_dirs = S_ISDIR(inode->i_mode);
1891
1892 if (!simple_empty(new_dentry))
1893 return -ENOTEMPTY;
1894
1895 if (new_dentry->d_inode) {
1896 (void) shmem_unlink(new_dir, new_dentry);
1897 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001898 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001899 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001900 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001901 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902 }
1903
1904 old_dir->i_size -= BOGO_DIRENT_SIZE;
1905 new_dir->i_size += BOGO_DIRENT_SIZE;
1906 old_dir->i_ctime = old_dir->i_mtime =
1907 new_dir->i_ctime = new_dir->i_mtime =
1908 inode->i_ctime = CURRENT_TIME;
1909 return 0;
1910}
1911
1912static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1913{
1914 int error;
1915 int len;
1916 struct inode *inode;
1917 struct page *page = NULL;
1918 char *kaddr;
1919 struct shmem_inode_info *info;
1920
1921 len = strlen(symname) + 1;
1922 if (len > PAGE_CACHE_SIZE)
1923 return -ENAMETOOLONG;
1924
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001925 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001926 if (!inode)
1927 return -ENOSPC;
1928
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001929 error = security_inode_init_security(inode, dir, NULL, NULL,
1930 NULL);
1931 if (error) {
1932 if (error != -EOPNOTSUPP) {
1933 iput(inode);
1934 return error;
1935 }
1936 error = 0;
1937 }
1938
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939 info = SHMEM_I(inode);
1940 inode->i_size = len-1;
1941 if (len <= (char *)inode - (char *)info) {
1942 /* do it inline */
1943 memcpy(info, symname, len);
1944 inode->i_op = &shmem_symlink_inline_operations;
1945 } else {
1946 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1947 if (error) {
1948 iput(inode);
1949 return error;
1950 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001951 unlock_page(page);
Hugh Dickins14fcc232008-07-28 15:46:19 -07001952 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001953 inode->i_op = &shmem_symlink_inode_operations;
1954 kaddr = kmap_atomic(page, KM_USER0);
1955 memcpy(kaddr, symname, len);
1956 kunmap_atomic(kaddr, KM_USER0);
1957 set_page_dirty(page);
1958 page_cache_release(page);
1959 }
1960 if (dir->i_mode & S_ISGID)
1961 inode->i_gid = dir->i_gid;
1962 dir->i_size += BOGO_DIRENT_SIZE;
1963 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1964 d_instantiate(dentry, inode);
1965 dget(dentry);
1966 return 0;
1967}
1968
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001969static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001970{
1971 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001972 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973}
1974
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001975static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976{
1977 struct page *page = NULL;
1978 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1979 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08001980 if (page)
1981 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001982 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001983}
1984
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001985static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986{
1987 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001988 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001989 kunmap(page);
1990 mark_page_accessed(page);
1991 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001992 }
1993}
1994
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001995static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001996 .readlink = generic_readlink,
1997 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001998};
1999
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002000static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002001 .truncate = shmem_truncate,
2002 .readlink = generic_readlink,
2003 .follow_link = shmem_follow_link,
2004 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002005};
2006
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002007#ifdef CONFIG_TMPFS_POSIX_ACL
Randy Dunlap46711812008-03-19 17:00:41 -07002008/*
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002009 * Superblocks without xattr inode operations will get security.* xattr
2010 * support from the VFS "for free". As soon as we have any other xattrs
2011 * like ACLs, we also need to implement the security.* handlers at
2012 * filesystem level, though.
2013 */
2014
2015static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2016 size_t list_len, const char *name,
2017 size_t name_len)
2018{
2019 return security_inode_listsecurity(inode, list, list_len);
2020}
2021
2022static int shmem_xattr_security_get(struct inode *inode, const char *name,
2023 void *buffer, size_t size)
2024{
2025 if (strcmp(name, "") == 0)
2026 return -EINVAL;
David P. Quigley42492592008-02-04 22:29:39 -08002027 return xattr_getsecurity(inode, name, buffer, size);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002028}
2029
2030static int shmem_xattr_security_set(struct inode *inode, const char *name,
2031 const void *value, size_t size, int flags)
2032{
2033 if (strcmp(name, "") == 0)
2034 return -EINVAL;
2035 return security_inode_setsecurity(inode, name, value, size, flags);
2036}
2037
Adrian Bunk1f370a22006-12-06 20:38:21 -08002038static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002039 .prefix = XATTR_SECURITY_PREFIX,
2040 .list = shmem_xattr_security_list,
2041 .get = shmem_xattr_security_get,
2042 .set = shmem_xattr_security_set,
2043};
2044
2045static struct xattr_handler *shmem_xattr_handlers[] = {
2046 &shmem_xattr_acl_access_handler,
2047 &shmem_xattr_acl_default_handler,
2048 &shmem_xattr_security_handler,
2049 NULL
2050};
2051#endif
2052
David M. Grimes91828a42006-10-17 00:09:45 -07002053static struct dentry *shmem_get_parent(struct dentry *child)
2054{
2055 return ERR_PTR(-ESTALE);
2056}
2057
2058static int shmem_match(struct inode *ino, void *vfh)
2059{
2060 __u32 *fh = vfh;
2061 __u64 inum = fh[2];
2062 inum = (inum << 32) | fh[1];
2063 return ino->i_ino == inum && fh[0] == ino->i_generation;
2064}
2065
Christoph Hellwig480b1162007-10-21 16:42:13 -07002066static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2067 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002068{
David M. Grimes91828a42006-10-17 00:09:45 -07002069 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002070 struct dentry *dentry = NULL;
2071 u64 inum = fid->raw[2];
2072 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002073
Christoph Hellwig480b1162007-10-21 16:42:13 -07002074 if (fh_len < 3)
2075 return NULL;
2076
2077 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2078 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002079 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002080 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002081 iput(inode);
2082 }
2083
Christoph Hellwig480b1162007-10-21 16:42:13 -07002084 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002085}
2086
2087static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2088 int connectable)
2089{
2090 struct inode *inode = dentry->d_inode;
2091
2092 if (*len < 3)
2093 return 255;
2094
2095 if (hlist_unhashed(&inode->i_hash)) {
2096 /* Unfortunately insert_inode_hash is not idempotent,
2097 * so as we hash inodes here rather than at creation
2098 * time, we need a lock to ensure we only try
2099 * to do it once
2100 */
2101 static DEFINE_SPINLOCK(lock);
2102 spin_lock(&lock);
2103 if (hlist_unhashed(&inode->i_hash))
2104 __insert_inode_hash(inode,
2105 inode->i_ino + inode->i_generation);
2106 spin_unlock(&lock);
2107 }
2108
2109 fh[0] = inode->i_generation;
2110 fh[1] = inode->i_ino;
2111 fh[2] = ((__u64)inode->i_ino) >> 32;
2112
2113 *len = 3;
2114 return 1;
2115}
2116
Christoph Hellwig39655162007-10-21 16:42:17 -07002117static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002118 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002119 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002120 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002121};
2122
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002123static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2124 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002125{
2126 char *this_char, *value, *rest;
2127
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002128 while (options != NULL) {
2129 this_char = options;
2130 for (;;) {
2131 /*
2132 * NUL-terminate this option: unfortunately,
2133 * mount options form a comma-separated list,
2134 * but mpol's nodelist may also contain commas.
2135 */
2136 options = strchr(options, ',');
2137 if (options == NULL)
2138 break;
2139 options++;
2140 if (!isdigit(*options)) {
2141 options[-1] = '\0';
2142 break;
2143 }
2144 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145 if (!*this_char)
2146 continue;
2147 if ((value = strchr(this_char,'=')) != NULL) {
2148 *value++ = 0;
2149 } else {
2150 printk(KERN_ERR
2151 "tmpfs: No value for mount option '%s'\n",
2152 this_char);
2153 return 1;
2154 }
2155
2156 if (!strcmp(this_char,"size")) {
2157 unsigned long long size;
2158 size = memparse(value,&rest);
2159 if (*rest == '%') {
2160 size <<= PAGE_SHIFT;
2161 size *= totalram_pages;
2162 do_div(size, 100);
2163 rest++;
2164 }
2165 if (*rest)
2166 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002167 sbinfo->max_blocks =
2168 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002170 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171 if (*rest)
2172 goto bad_val;
2173 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002174 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 if (*rest)
2176 goto bad_val;
2177 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002178 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002180 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 if (*rest)
2182 goto bad_val;
2183 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002184 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002186 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002187 if (*rest)
2188 goto bad_val;
2189 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002190 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002191 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002192 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002193 if (*rest)
2194 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002195 } else if (!strcmp(this_char,"mpol")) {
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002196 if (mpol_parse_str(value, &sbinfo->mpol, 1))
Robin Holt7339ff82006-01-14 13:20:48 -08002197 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002198 } else {
2199 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2200 this_char);
2201 return 1;
2202 }
2203 }
2204 return 0;
2205
2206bad_val:
2207 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2208 value, this_char);
2209 return 1;
2210
2211}
2212
2213static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2214{
2215 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002216 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002217 unsigned long blocks;
2218 unsigned long inodes;
2219 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002220
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002221 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002222 return error;
2223
2224 spin_lock(&sbinfo->stat_lock);
2225 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2226 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002227 if (config.max_blocks < blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002228 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002229 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002230 goto out;
2231 /*
2232 * Those tests also disallow limited->unlimited while any are in
2233 * use, so i_blocks will always be zero when max_blocks is zero;
2234 * but we must separately disallow unlimited->limited, because
2235 * in that case we have no record of how much is already in use.
2236 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002237 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002238 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002239 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002240 goto out;
2241
2242 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002243 sbinfo->max_blocks = config.max_blocks;
2244 sbinfo->free_blocks = config.max_blocks - blocks;
2245 sbinfo->max_inodes = config.max_inodes;
2246 sbinfo->free_inodes = config.max_inodes - inodes;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002247
2248 mpol_put(sbinfo->mpol);
2249 sbinfo->mpol = config.mpol; /* transfers initial ref */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002250out:
2251 spin_unlock(&sbinfo->stat_lock);
2252 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002253}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002254
2255static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2256{
2257 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2258
2259 if (sbinfo->max_blocks != shmem_default_max_blocks())
2260 seq_printf(seq, ",size=%luk",
2261 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2262 if (sbinfo->max_inodes != shmem_default_max_inodes())
2263 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2264 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2265 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2266 if (sbinfo->uid != 0)
2267 seq_printf(seq, ",uid=%u", sbinfo->uid);
2268 if (sbinfo->gid != 0)
2269 seq_printf(seq, ",gid=%u", sbinfo->gid);
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002270 shmem_show_mpol(seq, sbinfo->mpol);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002271 return 0;
2272}
2273#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274
2275static void shmem_put_super(struct super_block *sb)
2276{
2277 kfree(sb->s_fs_info);
2278 sb->s_fs_info = NULL;
2279}
2280
Linus Torvalds1da177e2005-04-16 15:20:36 -07002281static int shmem_fill_super(struct super_block *sb,
2282 void *data, int silent)
2283{
2284 struct inode *inode;
2285 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002286 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002287 int err = -ENOMEM;
2288
2289 /* Round up to L1_CACHE_BYTES to resist false sharing */
2290 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2291 L1_CACHE_BYTES), GFP_KERNEL);
2292 if (!sbinfo)
2293 return -ENOMEM;
2294
2295 sbinfo->max_blocks = 0;
2296 sbinfo->max_inodes = 0;
2297 sbinfo->mode = S_IRWXUGO | S_ISVTX;
David Howells76aac0e2008-11-14 10:39:12 +11002298 sbinfo->uid = current_fsuid();
2299 sbinfo->gid = current_fsgid();
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002300 sbinfo->mpol = NULL;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002301 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002303#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304 /*
2305 * Per default we only allow half of the physical ram per
2306 * tmpfs instance, limiting inodes to one per page of lowmem;
2307 * but the internal instance is left unlimited.
2308 */
2309 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002310 sbinfo->max_blocks = shmem_default_max_blocks();
2311 sbinfo->max_inodes = shmem_default_max_inodes();
2312 if (shmem_parse_options(data, sbinfo, false)) {
2313 err = -EINVAL;
2314 goto failed;
2315 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 }
David M. Grimes91828a42006-10-17 00:09:45 -07002317 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318#else
2319 sb->s_flags |= MS_NOUSER;
2320#endif
2321
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002322 spin_lock_init(&sbinfo->stat_lock);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002323 sbinfo->free_blocks = sbinfo->max_blocks;
2324 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002325
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326 sb->s_maxbytes = SHMEM_MAX_BYTES;
2327 sb->s_blocksize = PAGE_CACHE_SIZE;
2328 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2329 sb->s_magic = TMPFS_MAGIC;
2330 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002331 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002332#ifdef CONFIG_TMPFS_POSIX_ACL
2333 sb->s_xattr = shmem_xattr_handlers;
2334 sb->s_flags |= MS_POSIXACL;
2335#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002336
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002337 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338 if (!inode)
2339 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002340 inode->i_uid = sbinfo->uid;
2341 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002342 root = d_alloc_root(inode);
2343 if (!root)
2344 goto failed_iput;
2345 sb->s_root = root;
2346 return 0;
2347
2348failed_iput:
2349 iput(inode);
2350failed:
2351 shmem_put_super(sb);
2352 return err;
2353}
2354
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002355static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002356
2357static struct inode *shmem_alloc_inode(struct super_block *sb)
2358{
2359 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002360 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002361 if (!p)
2362 return NULL;
2363 return &p->vfs_inode;
2364}
2365
2366static void shmem_destroy_inode(struct inode *inode)
2367{
2368 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2369 /* only struct inode is valid if it's an inline symlink */
2370 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2371 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002372 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2374}
2375
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07002376static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002377{
2378 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2379
Christoph Lametera35afb82007-05-16 22:10:57 -07002380 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002381#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002382 p->i_acl = NULL;
2383 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002384#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385}
2386
2387static int init_inodecache(void)
2388{
2389 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2390 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002391 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002392 return 0;
2393}
2394
2395static void destroy_inodecache(void)
2396{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002397 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002398}
2399
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002400static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002401 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002402 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002404 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002405 .write_begin = shmem_write_begin,
2406 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002407#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002408 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409};
2410
Helge Deller15ad7cd2006-12-06 20:40:36 -08002411static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412 .mmap = shmem_mmap,
2413#ifdef CONFIG_TMPFS
2414 .llseek = generic_file_llseek,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002415 .read = do_sync_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002416 .write = do_sync_write,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002417 .aio_read = shmem_file_aio_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002418 .aio_write = generic_file_aio_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419 .fsync = simple_sync_file,
Hugh Dickinsae976412007-06-04 10:00:39 +02002420 .splice_read = generic_file_splice_read,
2421 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002422#endif
2423};
2424
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002425static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 .truncate = shmem_truncate,
2427 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002428 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002429#ifdef CONFIG_TMPFS_POSIX_ACL
2430 .setxattr = generic_setxattr,
2431 .getxattr = generic_getxattr,
2432 .listxattr = generic_listxattr,
2433 .removexattr = generic_removexattr,
2434 .permission = shmem_permission,
2435#endif
2436
Linus Torvalds1da177e2005-04-16 15:20:36 -07002437};
2438
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002439static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440#ifdef CONFIG_TMPFS
2441 .create = shmem_create,
2442 .lookup = simple_lookup,
2443 .link = shmem_link,
2444 .unlink = shmem_unlink,
2445 .symlink = shmem_symlink,
2446 .mkdir = shmem_mkdir,
2447 .rmdir = shmem_rmdir,
2448 .mknod = shmem_mknod,
2449 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002451#ifdef CONFIG_TMPFS_POSIX_ACL
2452 .setattr = shmem_notify_change,
2453 .setxattr = generic_setxattr,
2454 .getxattr = generic_getxattr,
2455 .listxattr = generic_listxattr,
2456 .removexattr = generic_removexattr,
2457 .permission = shmem_permission,
2458#endif
2459};
2460
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002461static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002462#ifdef CONFIG_TMPFS_POSIX_ACL
2463 .setattr = shmem_notify_change,
2464 .setxattr = generic_setxattr,
2465 .getxattr = generic_getxattr,
2466 .listxattr = generic_listxattr,
2467 .removexattr = generic_removexattr,
2468 .permission = shmem_permission,
2469#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002470};
2471
Hugh Dickins759b9772007-03-05 00:30:28 -08002472static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473 .alloc_inode = shmem_alloc_inode,
2474 .destroy_inode = shmem_destroy_inode,
2475#ifdef CONFIG_TMPFS
2476 .statfs = shmem_statfs,
2477 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002478 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479#endif
2480 .delete_inode = shmem_delete_inode,
2481 .drop_inode = generic_delete_inode,
2482 .put_super = shmem_put_super,
2483};
2484
2485static struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002486 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002487#ifdef CONFIG_NUMA
2488 .set_policy = shmem_set_policy,
2489 .get_policy = shmem_get_policy,
2490#endif
2491};
2492
2493
David Howells454e2392006-06-23 02:02:57 -07002494static int shmem_get_sb(struct file_system_type *fs_type,
2495 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002496{
David Howells454e2392006-06-23 02:02:57 -07002497 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002498}
2499
2500static struct file_system_type tmpfs_fs_type = {
2501 .owner = THIS_MODULE,
2502 .name = "tmpfs",
2503 .get_sb = shmem_get_sb,
2504 .kill_sb = kill_litter_super,
2505};
Linus Torvalds1da177e2005-04-16 15:20:36 -07002506
2507static int __init init_tmpfs(void)
2508{
2509 int error;
2510
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002511 error = bdi_init(&shmem_backing_dev_info);
2512 if (error)
2513 goto out4;
2514
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 error = init_inodecache();
2516 if (error)
2517 goto out3;
2518
2519 error = register_filesystem(&tmpfs_fs_type);
2520 if (error) {
2521 printk(KERN_ERR "Could not register tmpfs\n");
2522 goto out2;
2523 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002524
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002525 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002526 tmpfs_fs_type.name, NULL);
2527 if (IS_ERR(shm_mnt)) {
2528 error = PTR_ERR(shm_mnt);
2529 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2530 goto out1;
2531 }
2532 return 0;
2533
2534out1:
2535 unregister_filesystem(&tmpfs_fs_type);
2536out2:
2537 destroy_inodecache();
2538out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002539 bdi_destroy(&shmem_backing_dev_info);
2540out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002541 shm_mnt = ERR_PTR(error);
2542 return error;
2543}
Matt Mackall853ac432009-01-06 14:40:20 -08002544
2545#else /* !CONFIG_SHMEM */
2546
2547/*
2548 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2549 *
2550 * This is intended for small system where the benefits of the full
2551 * shmem code (swap-backed and resource-limited) are outweighed by
2552 * their complexity. On systems without swap this code should be
2553 * effectively equivalent, but much lighter weight.
2554 */
2555
2556#include <linux/ramfs.h>
2557
2558static struct file_system_type tmpfs_fs_type = {
2559 .name = "tmpfs",
2560 .get_sb = ramfs_get_sb,
2561 .kill_sb = kill_litter_super,
2562};
2563
2564static int __init init_tmpfs(void)
2565{
2566 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2567
2568 shm_mnt = kern_mount(&tmpfs_fs_type);
2569 BUG_ON(IS_ERR(shm_mnt));
2570
2571 return 0;
2572}
2573
2574int shmem_unuse(swp_entry_t entry, struct page *page)
2575{
2576 return 0;
2577}
2578
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002579#define shmem_vm_ops generic_file_vm_ops
2580#define shmem_file_operations ramfs_file_operations
2581#define shmem_get_inode(sb, mode, dev, flags) ramfs_get_inode(sb, mode, dev)
2582#define shmem_acct_size(flags, size) 0
2583#define shmem_unacct_size(flags, size) do {} while (0)
2584#define SHMEM_MAX_BYTES LLONG_MAX
Matt Mackall853ac432009-01-06 14:40:20 -08002585
2586#endif /* CONFIG_SHMEM */
2587
2588/* common code */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002589
Randy Dunlap46711812008-03-19 17:00:41 -07002590/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002591 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002592 * @name: name for dentry (to be seen in /proc/<pid>/maps
2593 * @size: size to be set for the file
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002594 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595 */
2596struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2597{
2598 int error;
2599 struct file *file;
2600 struct inode *inode;
2601 struct dentry *dentry, *root;
2602 struct qstr this;
2603
2604 if (IS_ERR(shm_mnt))
2605 return (void *)shm_mnt;
2606
2607 if (size < 0 || size > SHMEM_MAX_BYTES)
2608 return ERR_PTR(-EINVAL);
2609
2610 if (shmem_acct_size(flags, size))
2611 return ERR_PTR(-ENOMEM);
2612
2613 error = -ENOMEM;
2614 this.name = name;
2615 this.len = strlen(name);
2616 this.hash = 0; /* will go */
2617 root = shm_mnt->mnt_root;
2618 dentry = d_alloc(root, &this);
2619 if (!dentry)
2620 goto put_memory;
2621
2622 error = -ENFILE;
2623 file = get_empty_filp();
2624 if (!file)
2625 goto put_dentry;
2626
2627 error = -ENOSPC;
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002628 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629 if (!inode)
2630 goto close_file;
2631
Linus Torvalds1da177e2005-04-16 15:20:36 -07002632 d_instantiate(dentry, inode);
2633 inode->i_size = size;
2634 inode->i_nlink = 0; /* It is unlinked */
Dave Hansence8d2cd2007-10-16 23:31:13 -07002635 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
Matt Mackall853ac432009-01-06 14:40:20 -08002636 &shmem_file_operations);
2637
2638#ifndef CONFIG_MMU
2639 error = ramfs_nommu_expand_for_mapping(inode, size);
2640 if (error)
2641 goto close_file;
2642#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002643 return file;
2644
2645close_file:
2646 put_filp(file);
2647put_dentry:
2648 dput(dentry);
2649put_memory:
2650 shmem_unacct_size(flags, size);
2651 return ERR_PTR(error);
2652}
Keith Packard395e0dd2008-06-20 00:08:06 -07002653EXPORT_SYMBOL_GPL(shmem_file_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002654
Randy Dunlap46711812008-03-19 17:00:41 -07002655/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002656 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07002657 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2658 */
2659int shmem_zero_setup(struct vm_area_struct *vma)
2660{
2661 struct file *file;
2662 loff_t size = vma->vm_end - vma->vm_start;
2663
2664 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2665 if (IS_ERR(file))
2666 return PTR_ERR(file);
2667
2668 if (vma->vm_file)
2669 fput(vma->vm_file);
2670 vma->vm_file = file;
2671 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002672 return 0;
2673}
Matt Mackall853ac432009-01-06 14:40:20 -08002674
2675module_init(init_tmpfs)