blob: dfaa0f4e9789f5e8f395ac1dee7975c1abffdc1d [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>
Hugh Dickinscaefba12009-04-13 14:40:12 -070027#include <linux/pagemap.h>
Matt Mackall853ac432009-01-06 14:40:20 -080028#include <linux/file.h>
29#include <linux/mm.h>
30#include <linux/module.h>
Tim Chen7e496292010-08-09 17:19:05 -070031#include <linux/percpu_counter.h>
Matt Mackall853ac432009-01-06 14:40:20 -080032#include <linux/swap.h>
33
34static struct vfsmount *shm_mnt;
35
36#ifdef CONFIG_SHMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -070037/*
38 * This virtual memory filesystem is heavily based on the ramfs. It
39 * extends ramfs by the ability to use swap and honor resource limits
40 * which makes it a completely usable filesystem.
41 */
42
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070043#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070044#include <linux/exportfs.h>
Christoph Hellwig1c7c4742009-11-03 16:44:44 +010045#include <linux/posix_acl.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070046#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047#include <linux/mman.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <linux/string.h>
49#include <linux/slab.h>
50#include <linux/backing-dev.h>
51#include <linux/shmem_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/writeback.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#include <linux/blkdev.h>
54#include <linux/security.h>
55#include <linux/swapops.h>
56#include <linux/mempolicy.h>
57#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000058#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070059#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070060#include <linux/highmem.h>
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080061#include <linux/seq_file.h>
Mimi Zohar92562922008-10-07 14:00:12 -040062#include <linux/magic.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064#include <asm/uaccess.h>
65#include <asm/div64.h>
66#include <asm/pgtable.h>
67
Hugh Dickinscaefba12009-04-13 14:40:12 -070068/*
69 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
70 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
71 *
72 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
73 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
74 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
75 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
76 *
77 * We use / and * instead of shifts in the definitions below, so that the swap
78 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
79 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070080#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
Yuri Tikhonov61609d02009-04-13 14:40:11 -070081#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
Hugh Dickinscaefba12009-04-13 14:40:12 -070082
83#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
84#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
85
86#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
87#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
91
92/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
93#define SHMEM_PAGEIN VM_READ
94#define SHMEM_TRUNCATE VM_WRITE
95
96/* Definition to limit shmem_truncate's steps between cond_rescheds */
97#define LATENCY_LIMIT 64
98
99/* Pretend that each entry is of this size in directory's i_size */
100#define BOGO_DIRENT_SIZE 20
101
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
103enum sgp_type {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104 SGP_READ, /* don't exceed i_size, don't allocate page */
105 SGP_CACHE, /* don't exceed i_size, may allocate page */
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -0800106 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107 SGP_WRITE, /* may exceed i_size, may allocate page */
108};
109
Andrew Mortonb76db732008-02-08 04:21:49 -0800110#ifdef CONFIG_TMPFS
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800111static unsigned long shmem_default_max_blocks(void)
112{
113 return totalram_pages / 2;
114}
115
116static unsigned long shmem_default_max_inodes(void)
117{
118 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
119}
Andrew Mortonb76db732008-02-08 04:21:49 -0800120#endif
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800121
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122static int shmem_getpage(struct inode *inode, unsigned long idx,
123 struct page **pagep, enum sgp_type sgp, int *type);
124
Al Viro6daa0e22005-10-21 03:18:50 -0400125static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126{
127 /*
128 * The above definition of ENTRIES_PER_PAGE, and the use of
129 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
130 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -0700131 *
Mel Gormane12ba742007-10-16 01:25:52 -0700132 * Mobility flags are masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 */
Mel Gormane12ba742007-10-16 01:25:52 -0700134 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
Mel Gorman769848c2007-07-17 04:03:05 -0700135 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136}
137
138static inline void shmem_dir_free(struct page *page)
139{
140 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
141}
142
143static struct page **shmem_dir_map(struct page *page)
144{
145 return (struct page **)kmap_atomic(page, KM_USER0);
146}
147
148static inline void shmem_dir_unmap(struct page **dir)
149{
150 kunmap_atomic(dir, KM_USER0);
151}
152
153static swp_entry_t *shmem_swp_map(struct page *page)
154{
155 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
156}
157
158static inline void shmem_swp_balance_unmap(void)
159{
160 /*
161 * When passing a pointer to an i_direct entry, to code which
162 * also handles indirect entries and so will shmem_swp_unmap,
163 * we must arrange for the preempt count to remain in balance.
164 * What kmap_atomic of a lowmem page does depends on config
165 * and architecture, so pretend to kmap_atomic some lowmem page.
166 */
167 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
168}
169
170static inline void shmem_swp_unmap(swp_entry_t *entry)
171{
172 kunmap_atomic(entry, KM_USER1);
173}
174
175static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
176{
177 return sb->s_fs_info;
178}
179
180/*
181 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
182 * for shared memory and for shared anonymous (/dev/zero) mappings
183 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
184 * consistent with the pre-accounting of private mappings ...
185 */
186static inline int shmem_acct_size(unsigned long flags, loff_t size)
187{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000188 return (flags & VM_NORESERVE) ?
189 0 : security_vm_enough_memory_kern(VM_ACCT(size));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190}
191
192static inline void shmem_unacct_size(unsigned long flags, loff_t size)
193{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000194 if (!(flags & VM_NORESERVE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195 vm_unacct_memory(VM_ACCT(size));
196}
197
198/*
199 * ... whereas tmpfs objects are accounted incrementally as
200 * pages are allocated, in order to allow huge sparse files.
201 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
202 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
203 */
204static inline int shmem_acct_block(unsigned long flags)
205{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000206 return (flags & VM_NORESERVE) ?
207 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208}
209
210static inline void shmem_unacct_blocks(unsigned long flags, long pages)
211{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000212 if (flags & VM_NORESERVE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
214}
215
Hugh Dickins759b9772007-03-05 00:30:28 -0800216static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700217static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800218static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800219static const struct inode_operations shmem_inode_operations;
220static const struct inode_operations shmem_dir_inode_operations;
221static const struct inode_operations shmem_special_inode_operations;
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +0400222static const struct vm_operations_struct shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700224static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 .ra_pages = 0, /* No readahead */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700226 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 .unplug_io_fn = default_unplug_io_fn,
228};
229
230static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800231static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
233static void shmem_free_blocks(struct inode *inode, long pages)
234{
235 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700236 if (sbinfo->max_blocks) {
Tim Chen7e496292010-08-09 17:19:05 -0700237 percpu_counter_add(&sbinfo->used_blocks, -pages);
238 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -0700240 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241 }
242}
243
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800244static int shmem_reserve_inode(struct super_block *sb)
245{
246 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
247 if (sbinfo->max_inodes) {
248 spin_lock(&sbinfo->stat_lock);
249 if (!sbinfo->free_inodes) {
250 spin_unlock(&sbinfo->stat_lock);
251 return -ENOSPC;
252 }
253 sbinfo->free_inodes--;
254 spin_unlock(&sbinfo->stat_lock);
255 }
256 return 0;
257}
258
259static void shmem_free_inode(struct super_block *sb)
260{
261 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
262 if (sbinfo->max_inodes) {
263 spin_lock(&sbinfo->stat_lock);
264 sbinfo->free_inodes++;
265 spin_unlock(&sbinfo->stat_lock);
266 }
267}
268
Randy Dunlap46711812008-03-19 17:00:41 -0700269/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 * @inode: inode to recalc
272 *
273 * We have to calculate the free blocks since the mm can drop
274 * undirtied hole pages behind our back.
275 *
276 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
277 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
278 *
279 * It has to be called with the spinlock held.
280 */
281static void shmem_recalc_inode(struct inode *inode)
282{
283 struct shmem_inode_info *info = SHMEM_I(inode);
284 long freed;
285
286 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
287 if (freed > 0) {
288 info->alloced -= freed;
289 shmem_unacct_blocks(info->flags, freed);
290 shmem_free_blocks(inode, freed);
291 }
292}
293
Randy Dunlap46711812008-03-19 17:00:41 -0700294/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 * @info: info structure for the inode
297 * @index: index of the page to find
298 * @page: optional page to add to the structure. Has to be preset to
299 * all zeros
300 *
301 * If there is no space allocated yet it will return NULL when
302 * page is NULL, else it will use the page for the needed block,
303 * setting it to NULL on return to indicate that it has been used.
304 *
305 * The swap vector is organized the following way:
306 *
307 * There are SHMEM_NR_DIRECT entries directly stored in the
308 * shmem_inode_info structure. So small files do not need an addional
309 * allocation.
310 *
311 * For pages with index > SHMEM_NR_DIRECT there is the pointer
312 * i_indirect which points to a page which holds in the first half
313 * doubly indirect blocks, in the second half triple indirect blocks:
314 *
315 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
316 * following layout (for SHMEM_NR_DIRECT == 16):
317 *
318 * i_indirect -> dir --> 16-19
319 * | +-> 20-23
320 * |
321 * +-->dir2 --> 24-27
322 * | +-> 28-31
323 * | +-> 32-35
324 * | +-> 36-39
325 * |
326 * +-->dir3 --> 40-43
327 * +-> 44-47
328 * +-> 48-51
329 * +-> 52-55
330 */
331static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
332{
333 unsigned long offset;
334 struct page **dir;
335 struct page *subdir;
336
337 if (index < SHMEM_NR_DIRECT) {
338 shmem_swp_balance_unmap();
339 return info->i_direct+index;
340 }
341 if (!info->i_indirect) {
342 if (page) {
343 info->i_indirect = *page;
344 *page = NULL;
345 }
346 return NULL; /* need another page */
347 }
348
349 index -= SHMEM_NR_DIRECT;
350 offset = index % ENTRIES_PER_PAGE;
351 index /= ENTRIES_PER_PAGE;
352 dir = shmem_dir_map(info->i_indirect);
353
354 if (index >= ENTRIES_PER_PAGE/2) {
355 index -= ENTRIES_PER_PAGE/2;
356 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
357 index %= ENTRIES_PER_PAGE;
358 subdir = *dir;
359 if (!subdir) {
360 if (page) {
361 *dir = *page;
362 *page = NULL;
363 }
364 shmem_dir_unmap(dir);
365 return NULL; /* need another page */
366 }
367 shmem_dir_unmap(dir);
368 dir = shmem_dir_map(subdir);
369 }
370
371 dir += index;
372 subdir = *dir;
373 if (!subdir) {
374 if (!page || !(subdir = *page)) {
375 shmem_dir_unmap(dir);
376 return NULL; /* need a page */
377 }
378 *dir = subdir;
379 *page = NULL;
380 }
381 shmem_dir_unmap(dir);
382 return shmem_swp_map(subdir) + offset;
383}
384
385static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
386{
387 long incdec = value? 1: -1;
388
389 entry->val = value;
390 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700391 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
392 struct page *page = kmap_atomic_to_page(entry);
393 set_page_private(page, page_private(page) + incdec);
394 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395}
396
Randy Dunlap46711812008-03-19 17:00:41 -0700397/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399 * @info: info structure for the inode
400 * @index: index of the page to find
401 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700402 *
403 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 */
405static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
406{
407 struct inode *inode = &info->vfs_inode;
408 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
409 struct page *page = NULL;
410 swp_entry_t *entry;
411
412 if (sgp != SGP_WRITE &&
413 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
414 return ERR_PTR(-EINVAL);
415
416 while (!(entry = shmem_swp_entry(info, index, &page))) {
417 if (sgp == SGP_READ)
418 return shmem_swp_map(ZERO_PAGE(0));
419 /*
Tim Chen7e496292010-08-09 17:19:05 -0700420 * Test used_blocks against 1 less max_blocks, since we have 1 data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 * page (and perhaps indirect index pages) yet to allocate:
422 * a waste to allocate index if we cannot allocate data.
423 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700424 if (sbinfo->max_blocks) {
Tim Chen7e496292010-08-09 17:19:05 -0700425 if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 return ERR_PTR(-ENOSPC);
Tim Chen7e496292010-08-09 17:19:05 -0700427 percpu_counter_inc(&sbinfo->used_blocks);
428 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 inode->i_blocks += BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -0700430 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 }
432
433 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700434 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700435 spin_lock(&info->lock);
436
437 if (!page) {
438 shmem_free_blocks(inode, 1);
439 return ERR_PTR(-ENOMEM);
440 }
441 if (sgp != SGP_WRITE &&
442 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
443 entry = ERR_PTR(-EINVAL);
444 break;
445 }
446 if (info->next_index <= index)
447 info->next_index = index + 1;
448 }
449 if (page) {
450 /* another task gave its page, or truncated the file */
451 shmem_free_blocks(inode, 1);
452 shmem_dir_free(page);
453 }
454 if (info->next_index <= index && !IS_ERR(entry))
455 info->next_index = index + 1;
456 return entry;
457}
458
Randy Dunlap46711812008-03-19 17:00:41 -0700459/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 * shmem_free_swp - free some swap entries in a directory
Hugh Dickins1ae70002007-03-29 01:20:36 -0700461 * @dir: pointer to the directory
462 * @edir: pointer after last entry of the directory
463 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700465static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
466 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700468 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 swp_entry_t *ptr;
470 int freed = 0;
471
472 for (ptr = dir; ptr < edir; ptr++) {
473 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700474 if (unlikely(punch_lock)) {
475 punch_unlock = punch_lock;
476 punch_lock = NULL;
477 spin_lock(punch_unlock);
478 if (!ptr->val)
479 continue;
480 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 free_swap_and_cache(*ptr);
482 *ptr = (swp_entry_t){0};
483 freed++;
484 }
485 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700486 if (punch_unlock)
487 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 return freed;
489}
490
Hugh Dickins1ae70002007-03-29 01:20:36 -0700491static int shmem_map_and_free_swp(struct page *subdir, int offset,
492 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493{
494 swp_entry_t *ptr;
495 int freed = 0;
496
497 ptr = shmem_swp_map(subdir);
498 for (; offset < limit; offset += LATENCY_LIMIT) {
499 int size = limit - offset;
500 if (size > LATENCY_LIMIT)
501 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700502 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
503 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 if (need_resched()) {
505 shmem_swp_unmap(ptr);
506 if (*dir) {
507 shmem_dir_unmap(*dir);
508 *dir = NULL;
509 }
510 cond_resched();
511 ptr = shmem_swp_map(subdir);
512 }
513 }
514 shmem_swp_unmap(ptr);
515 return freed;
516}
517
518static void shmem_free_pages(struct list_head *next)
519{
520 struct page *page;
521 int freed = 0;
522
523 do {
524 page = container_of(next, struct page, lru);
525 next = next->next;
526 shmem_dir_free(page);
527 freed++;
528 if (freed >= LATENCY_LIMIT) {
529 cond_resched();
530 freed = 0;
531 }
532 } while (next);
533}
534
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800535static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536{
537 struct shmem_inode_info *info = SHMEM_I(inode);
538 unsigned long idx;
539 unsigned long size;
540 unsigned long limit;
541 unsigned long stage;
542 unsigned long diroff;
543 struct page **dir;
544 struct page *topdir;
545 struct page *middir;
546 struct page *subdir;
547 swp_entry_t *ptr;
548 LIST_HEAD(pages_to_free);
549 long nr_pages_to_free = 0;
550 long nr_swaps_freed = 0;
551 int offset;
552 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700553 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700554 spinlock_t *needs_lock;
555 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700556 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
558 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800559 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560 if (idx >= info->next_index)
561 return;
562
563 spin_lock(&info->lock);
564 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800565 if (likely(end == (loff_t) -1)) {
566 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700567 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800568 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700569 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700570 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800571 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700572 if (end + 1 >= inode->i_size) { /* we may free a little more */
573 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
574 PAGE_CACHE_SHIFT;
575 upper_limit = SHMEM_MAX_INDEX;
576 } else {
577 limit = (end + 1) >> PAGE_CACHE_SHIFT;
578 upper_limit = limit;
579 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700580 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800581 punch_hole = 1;
582 }
583
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800585 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 info->i_indirect = NULL;
587 nr_pages_to_free++;
588 list_add(&topdir->lru, &pages_to_free);
589 }
590 spin_unlock(&info->lock);
591
592 if (info->swapped && idx < SHMEM_NR_DIRECT) {
593 ptr = info->i_direct;
594 size = limit;
595 if (size > SHMEM_NR_DIRECT)
596 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700597 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800599
600 /*
601 * If there are no indirect blocks or we are punching a hole
602 * below indirect blocks, nothing to be done.
603 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700604 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 goto done2;
606
Hugh Dickins1ae70002007-03-29 01:20:36 -0700607 /*
608 * The truncation case has already dropped info->lock, and we're safe
609 * because i_size and next_index have already been lowered, preventing
610 * access beyond. But in the punch_hole case, we still need to take
611 * the lock when updating the swap directory, because there might be
612 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
613 * shmem_writepage. However, whenever we find we can remove a whole
614 * directory page (not at the misaligned start or end of the range),
615 * we first NULLify its pointer in the level above, and then have no
616 * need to take the lock when updating its contents: needs_lock and
617 * punch_lock (either pointing to info->lock or NULL) manage this.
618 */
619
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700620 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 limit -= SHMEM_NR_DIRECT;
622 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
623 offset = idx % ENTRIES_PER_PAGE;
624 idx -= offset;
625
626 dir = shmem_dir_map(topdir);
627 stage = ENTRIES_PER_PAGEPAGE/2;
628 if (idx < ENTRIES_PER_PAGEPAGE/2) {
629 middir = topdir;
630 diroff = idx/ENTRIES_PER_PAGE;
631 } else {
632 dir += ENTRIES_PER_PAGE/2;
633 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
634 while (stage <= idx)
635 stage += ENTRIES_PER_PAGEPAGE;
636 middir = *dir;
637 if (*dir) {
638 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
639 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700640 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700641 if (needs_lock) {
642 spin_lock(needs_lock);
643 *dir = NULL;
644 spin_unlock(needs_lock);
645 needs_lock = NULL;
646 } else
647 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 nr_pages_to_free++;
649 list_add(&middir->lru, &pages_to_free);
650 }
651 shmem_dir_unmap(dir);
652 dir = shmem_dir_map(middir);
653 } else {
654 diroff = 0;
655 offset = 0;
656 idx = stage;
657 }
658 }
659
660 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
661 if (unlikely(idx == stage)) {
662 shmem_dir_unmap(dir);
663 dir = shmem_dir_map(topdir) +
664 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
665 while (!*dir) {
666 dir++;
667 idx += ENTRIES_PER_PAGEPAGE;
668 if (idx >= limit)
669 goto done1;
670 }
671 stage = idx + ENTRIES_PER_PAGEPAGE;
672 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700673 if (punch_hole)
674 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700675 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700676 if (needs_lock) {
677 spin_lock(needs_lock);
678 *dir = NULL;
679 spin_unlock(needs_lock);
680 needs_lock = NULL;
681 } else
682 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700683 nr_pages_to_free++;
684 list_add(&middir->lru, &pages_to_free);
685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 shmem_dir_unmap(dir);
687 cond_resched();
688 dir = shmem_dir_map(middir);
689 diroff = 0;
690 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700691 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700693 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
694 if (needs_lock) {
695 spin_lock(needs_lock);
696 dir[diroff] = NULL;
697 spin_unlock(needs_lock);
698 punch_lock = NULL;
699 } else
700 dir[diroff] = NULL;
701 nr_pages_to_free++;
702 list_add(&subdir->lru, &pages_to_free);
703 }
704 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 size = limit - idx;
706 if (size > ENTRIES_PER_PAGE)
707 size = ENTRIES_PER_PAGE;
708 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700709 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 if (!dir)
711 dir = shmem_dir_map(middir);
712 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700713 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700715 set_page_private(subdir,
716 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700718 } else
719 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700720 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700721 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 }
723done1:
724 shmem_dir_unmap(dir);
725done2:
726 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
727 /*
728 * Call truncate_inode_pages again: racing shmem_unuse_inode
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000729 * may have swizzled a page in from swap since
730 * truncate_pagecache or generic_delete_inode did it, before we
731 * lowered next_index. Also, though shmem_getpage checks
732 * i_size before adding to cache, no recheck after: so fix the
733 * narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700734 *
735 * Recalling truncate_inode_pages_range and unmap_mapping_range
736 * every time for punch_hole (which never got a chance to clear
737 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
738 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800740 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700741 if (punch_hole)
742 unmap_mapping_range(inode->i_mapping, start,
743 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 }
745
746 spin_lock(&info->lock);
747 info->flags &= ~SHMEM_TRUNCATE;
748 info->swapped -= nr_swaps_freed;
749 if (nr_pages_to_free)
750 shmem_free_blocks(inode, nr_pages_to_free);
751 shmem_recalc_inode(inode);
752 spin_unlock(&info->lock);
753
754 /*
755 * Empty swap vector directory pages to be freed?
756 */
757 if (!list_empty(&pages_to_free)) {
758 pages_to_free.prev->next = NULL;
759 shmem_free_pages(pages_to_free.next);
760 }
761}
762
763static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
764{
765 struct inode *inode = dentry->d_inode;
Nick Pigginaf5a30d2010-06-03 22:01:46 +1000766 loff_t newsize = attr->ia_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 int error;
768
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200769 error = inode_change_ok(inode, attr);
770 if (error)
771 return error;
772
Nick Pigginaf5a30d2010-06-03 22:01:46 +1000773 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)
774 && newsize != inode->i_size) {
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000775 struct page *page = NULL;
776
777 if (newsize < inode->i_size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 /*
779 * If truncating down to a partial page, then
780 * if that page is already allocated, hold it
781 * in memory until the truncation is over, so
782 * truncate_partial_page cannnot miss it were
783 * it assigned to swap.
784 */
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000785 if (newsize & (PAGE_CACHE_SIZE-1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 (void) shmem_getpage(inode,
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000787 newsize >> PAGE_CACHE_SHIFT,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700788 &page, SGP_READ, NULL);
Hugh Dickinsd3602442008-02-04 22:28:44 -0800789 if (page)
790 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700791 }
792 /*
793 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
794 * detect if any pages might have been added to cache
795 * after truncate_inode_pages. But we needn't bother
796 * if it's being fully truncated to zero-length: the
797 * nrpages check is efficient enough in that case.
798 */
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000799 if (newsize) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 struct shmem_inode_info *info = SHMEM_I(inode);
801 spin_lock(&info->lock);
802 info->flags &= ~SHMEM_PAGEIN;
803 spin_unlock(&info->lock);
804 }
805 }
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000806
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200807 /* XXX(truncate): truncate_setsize should be called last */
808 truncate_setsize(inode, newsize);
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000809 if (page)
810 page_cache_release(page);
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000811 shmem_truncate_range(inode, newsize, (loff_t)-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 }
813
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200814 setattr_copy(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700815#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200816 if (attr->ia_valid & ATTR_MODE)
Christoph Hellwig1c7c4742009-11-03 16:44:44 +0100817 error = generic_acl_chmod(inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700818#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 return error;
820}
821
Al Viro1f895f72010-06-05 19:10:41 -0400822static void shmem_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 struct shmem_inode_info *info = SHMEM_I(inode);
825
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000826 if (inode->i_mapping->a_ops == &shmem_aops) {
Mark Fashehfef26652005-09-09 13:01:31 -0700827 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 shmem_unacct_size(info->flags, inode->i_size);
829 inode->i_size = 0;
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000830 shmem_truncate_range(inode, 0, (loff_t)-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 if (!list_empty(&info->swaplist)) {
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800832 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833 list_del_init(&info->swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800834 mutex_unlock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 }
836 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700837 BUG_ON(inode->i_blocks);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800838 shmem_free_inode(inode->i_sb);
Al Viro1f895f72010-06-05 19:10:41 -0400839 end_writeback(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840}
841
842static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
843{
844 swp_entry_t *ptr;
845
846 for (ptr = dir; ptr < edir; ptr++) {
847 if (ptr->val == entry.val)
848 return ptr - dir;
849 }
850 return -1;
851}
852
853static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
854{
855 struct inode *inode;
856 unsigned long idx;
857 unsigned long size;
858 unsigned long limit;
859 unsigned long stage;
860 struct page **dir;
861 struct page *subdir;
862 swp_entry_t *ptr;
863 int offset;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800864 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700865
866 idx = 0;
867 ptr = info->i_direct;
868 spin_lock(&info->lock);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800869 if (!info->swapped) {
870 list_del_init(&info->swaplist);
871 goto lost2;
872 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 limit = info->next_index;
874 size = limit;
875 if (size > SHMEM_NR_DIRECT)
876 size = SHMEM_NR_DIRECT;
877 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800878 if (offset >= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700879 goto found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 if (!info->i_indirect)
881 goto lost2;
882
883 dir = shmem_dir_map(info->i_indirect);
884 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
885
886 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
887 if (unlikely(idx == stage)) {
888 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800889 if (cond_resched_lock(&info->lock)) {
890 /* check it has not been truncated */
891 if (limit > info->next_index) {
892 limit = info->next_index;
893 if (idx >= limit)
894 goto lost2;
895 }
896 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 dir = shmem_dir_map(info->i_indirect) +
898 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
899 while (!*dir) {
900 dir++;
901 idx += ENTRIES_PER_PAGEPAGE;
902 if (idx >= limit)
903 goto lost1;
904 }
905 stage = idx + ENTRIES_PER_PAGEPAGE;
906 subdir = *dir;
907 shmem_dir_unmap(dir);
908 dir = shmem_dir_map(subdir);
909 }
910 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700911 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 ptr = shmem_swp_map(subdir);
913 size = limit - idx;
914 if (size > ENTRIES_PER_PAGE)
915 size = ENTRIES_PER_PAGE;
916 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800917 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700918 if (offset >= 0) {
919 shmem_dir_unmap(dir);
920 goto found;
921 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700922 }
923 }
924lost1:
925 shmem_dir_unmap(dir-1);
926lost2:
927 spin_unlock(&info->lock);
928 return 0;
929found:
930 idx += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800931 inode = igrab(&info->vfs_inode);
932 spin_unlock(&info->lock);
933
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800934 /*
935 * Move _head_ to start search for next from here.
Al Viro1f895f72010-06-05 19:10:41 -0400936 * But be careful: shmem_evict_inode checks list_empty without taking
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800937 * mutex, and there's an instant in list_move_tail when info->swaplist
938 * would appear empty, if it were the only one on shmem_swaplist. We
939 * could avoid doing it if inode NULL; or use this minor optimization.
940 */
941 if (shmem_swaplist.next != &info->swaplist)
942 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800943 mutex_unlock(&shmem_swaplist_mutex);
944
945 error = 1;
946 if (!inode)
947 goto out;
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800948 /*
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -0800949 * Charge page using GFP_KERNEL while we can wait.
950 * Charged back to the user(not to caller) when swap account is used.
951 * add_to_page_cache() will be called with GFP_NOWAIT.
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800952 */
Hugh Dickins82369552008-02-07 00:14:22 -0800953 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800954 if (error)
955 goto out;
Hugh Dickins82369552008-02-07 00:14:22 -0800956 error = radix_tree_preload(GFP_KERNEL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700957 if (error) {
958 mem_cgroup_uncharge_cache_page(page);
959 goto out;
960 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800961 error = 1;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800962
963 spin_lock(&info->lock);
964 ptr = shmem_swp_entry(info, idx, NULL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700965 if (ptr && ptr->val == entry.val) {
Nick Piggine2867812008-07-25 19:45:30 -0700966 error = add_to_page_cache_locked(page, inode->i_mapping,
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800967 idx, GFP_NOWAIT);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700968 /* does mem_cgroup_uncharge_cache_page on error */
969 } else /* we must compensate for our precharge above */
970 mem_cgroup_uncharge_cache_page(page);
971
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800972 if (error == -EEXIST) {
973 struct page *filepage = find_get_page(inode->i_mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800974 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800975 if (filepage) {
976 /*
977 * There might be a more uptodate page coming down
978 * from a stacked writepage: forget our swappage if so.
979 */
980 if (PageUptodate(filepage))
981 error = 0;
982 page_cache_release(filepage);
983 }
984 }
985 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800986 delete_from_swap_cache(page);
987 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800989 shmem_swp_set(info, ptr, 0);
990 swap_free(entry);
991 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800993 if (ptr)
994 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700995 spin_unlock(&info->lock);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800996 radix_tree_preload_end();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800997out:
998 unlock_page(page);
999 page_cache_release(page);
1000 iput(inode); /* allows for NULL */
1001 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002}
1003
1004/*
1005 * shmem_unuse() search for an eventually swapped out shmem page.
1006 */
1007int shmem_unuse(swp_entry_t entry, struct page *page)
1008{
1009 struct list_head *p, *next;
1010 struct shmem_inode_info *info;
1011 int found = 0;
1012
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001013 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001014 list_for_each_safe(p, next, &shmem_swaplist) {
1015 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001016 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001017 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001018 if (found)
1019 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001021 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001022 /*
1023 * Can some race bring us here? We've been holding page lock,
1024 * so I think not; but would rather try again later than BUG()
1025 */
1026 unlock_page(page);
1027 page_cache_release(page);
1028out:
1029 return (found < 0) ? found : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030}
1031
1032/*
1033 * Move the page from the page cache to the swap cache.
1034 */
1035static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1036{
1037 struct shmem_inode_info *info;
1038 swp_entry_t *entry, swap;
1039 struct address_space *mapping;
1040 unsigned long index;
1041 struct inode *inode;
1042
1043 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001044 mapping = page->mapping;
1045 index = page->index;
1046 inode = mapping->host;
1047 info = SHMEM_I(inode);
1048 if (info->flags & VM_LOCKED)
1049 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001050 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001051 goto redirty;
1052
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001053 /*
1054 * shmem_backing_dev_info's capabilities prevent regular writeback or
1055 * sync from ever calling shmem_writepage; but a stacking filesystem
1056 * may use the ->writepage of its underlying filesystem, in which case
1057 * tmpfs should write out to swap only in response to memory pressure,
Jens Axboe5b0830c2009-09-23 19:37:09 +02001058 * and not for the writeback threads or sync. However, in those cases,
1059 * we do still want to check if there's a redundant swappage to be
1060 * discarded.
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001061 */
1062 if (wbc->for_reclaim)
1063 swap = get_swap_page();
1064 else
1065 swap.val = 0;
1066
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 spin_lock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068 if (index >= info->next_index) {
1069 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1070 goto unlock;
1071 }
1072 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001073 if (entry->val) {
1074 /*
1075 * The more uptodate page coming down from a stacked
1076 * writepage should replace our old swappage.
1077 */
1078 free_swap_and_cache(*entry);
1079 shmem_swp_set(info, entry, 0);
1080 }
1081 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001082
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001083 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Hugh Dickins73b12622008-02-04 22:28:50 -08001084 remove_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 shmem_swp_set(info, entry, swap.val);
1086 shmem_swp_unmap(entry);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001087 if (list_empty(&info->swaplist))
1088 inode = igrab(inode);
1089 else
1090 inode = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001091 spin_unlock(&info->lock);
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001092 swap_shmem_alloc(swap);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001093 BUG_ON(page_mapped(page));
Hugh Dickins73b12622008-02-04 22:28:50 -08001094 page_cache_release(page); /* pagecache ref */
Hugh Dickins9fab5612009-03-31 15:23:33 -07001095 swap_writepage(page, wbc);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001096 if (inode) {
1097 mutex_lock(&shmem_swaplist_mutex);
1098 /* move instead of add in case we're racing */
1099 list_move_tail(&info->swaplist, &shmem_swaplist);
1100 mutex_unlock(&shmem_swaplist_mutex);
1101 iput(inode);
1102 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001103 return 0;
1104 }
1105
1106 shmem_swp_unmap(entry);
1107unlock:
1108 spin_unlock(&info->lock);
Daisuke Nishimura2ca45322009-09-21 17:02:52 -07001109 /*
1110 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1111 * clear SWAP_HAS_CACHE flag.
1112 */
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -07001113 swapcache_free(swap, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114redirty:
1115 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001116 if (wbc->for_reclaim)
1117 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1118 unlock_page(page);
1119 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001120}
1121
1122#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001123#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001124static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001125{
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001126 char buffer[64];
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001127
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001128 if (!mpol || mpol->mode == MPOL_DEFAULT)
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001129 return; /* show nothing */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001130
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001131 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001132
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001133 seq_printf(seq, ",mpol=%s", buffer);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001134}
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001135
1136static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1137{
1138 struct mempolicy *mpol = NULL;
1139 if (sbinfo->mpol) {
1140 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1141 mpol = sbinfo->mpol;
1142 mpol_get(mpol);
1143 spin_unlock(&sbinfo->stat_lock);
1144 }
1145 return mpol;
1146}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001147#endif /* CONFIG_TMPFS */
1148
Hugh Dickins02098fe2008-02-04 22:28:42 -08001149static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1150 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151{
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001152 struct mempolicy mpol, *spol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001153 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001154 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001155
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001156 spol = mpol_cond_copy(&mpol,
1157 mpol_shared_policy_lookup(&info->policy, idx));
1158
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001160 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001162 pvma.vm_ops = NULL;
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001163 pvma.vm_policy = spol;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001164 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001165 return page;
1166}
1167
Hugh Dickins02098fe2008-02-04 22:28:42 -08001168static struct page *shmem_alloc_page(gfp_t gfp,
1169 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170{
1171 struct vm_area_struct pvma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001173 /* Create a pseudo vma that just contains the policy */
1174 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001176 pvma.vm_ops = NULL;
1177 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001178
1179 /*
1180 * alloc_page_vma() will drop the shared policy reference
1181 */
1182 return alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001184#else /* !CONFIG_NUMA */
1185#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001186static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001187{
1188}
1189#endif /* CONFIG_TMPFS */
1190
Hugh Dickins02098fe2008-02-04 22:28:42 -08001191static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1192 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001194 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195}
1196
Hugh Dickins02098fe2008-02-04 22:28:42 -08001197static inline struct page *shmem_alloc_page(gfp_t gfp,
1198 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001199{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001200 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001202#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001203
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001204#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1205static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1206{
1207 return NULL;
1208}
1209#endif
1210
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211/*
1212 * shmem_getpage - either get the page from swap or allocate a new one
1213 *
1214 * If we allocate a new one we do not mark it dirty. That's up to the
1215 * vm. If we swap it in we mark it dirty since we also free the swap
1216 * entry since a page cannot live in both the swap and page cache
1217 */
1218static int shmem_getpage(struct inode *inode, unsigned long idx,
1219 struct page **pagep, enum sgp_type sgp, int *type)
1220{
1221 struct address_space *mapping = inode->i_mapping;
1222 struct shmem_inode_info *info = SHMEM_I(inode);
1223 struct shmem_sb_info *sbinfo;
1224 struct page *filepage = *pagep;
1225 struct page *swappage;
Shaohua Liff36b8012010-08-09 17:19:06 -07001226 struct page *prealloc_page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227 swp_entry_t *entry;
1228 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001229 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230 int error;
1231
1232 if (idx >= SHMEM_MAX_INDEX)
1233 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001234
1235 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001236 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001237
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 /*
1239 * Normally, filepage is NULL on entry, and either found
1240 * uptodate immediately, or allocated and zeroed, or read
1241 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001242 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae9764162007-06-04 10:00:39 +02001243 * filepage, which may be found not uptodate by other callers
1244 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 */
1246repeat:
1247 if (!filepage)
1248 filepage = find_lock_page(mapping, idx);
1249 if (filepage && PageUptodate(filepage))
1250 goto done;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001251 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001252 if (!filepage) {
1253 /*
1254 * Try to preload while we can wait, to not make a habit of
1255 * draining atomic reserves; but don't latch on to this cpu.
1256 */
1257 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1258 if (error)
1259 goto failed;
1260 radix_tree_preload_end();
Shaohua Liff36b8012010-08-09 17:19:06 -07001261 if (sgp != SGP_READ && !prealloc_page) {
1262 /* We don't care if this fails */
1263 prealloc_page = shmem_alloc_page(gfp, info, idx);
1264 if (prealloc_page) {
1265 if (mem_cgroup_cache_charge(prealloc_page,
1266 current->mm, GFP_KERNEL)) {
1267 page_cache_release(prealloc_page);
1268 prealloc_page = NULL;
1269 }
1270 }
1271 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001272 }
Shaohua Liff36b8012010-08-09 17:19:06 -07001273 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001274
1275 spin_lock(&info->lock);
1276 shmem_recalc_inode(inode);
1277 entry = shmem_swp_alloc(info, idx, sgp);
1278 if (IS_ERR(entry)) {
1279 spin_unlock(&info->lock);
1280 error = PTR_ERR(entry);
1281 goto failed;
1282 }
1283 swap = *entry;
1284
1285 if (swap.val) {
1286 /* Look it up and read it in.. */
1287 swappage = lookup_swap_cache(swap);
1288 if (!swappage) {
1289 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001291 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001292 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001293 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001294 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001295 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001296 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001297 if (!swappage) {
1298 spin_lock(&info->lock);
1299 entry = shmem_swp_alloc(info, idx, sgp);
1300 if (IS_ERR(entry))
1301 error = PTR_ERR(entry);
1302 else {
1303 if (entry->val == swap.val)
1304 error = -ENOMEM;
1305 shmem_swp_unmap(entry);
1306 }
1307 spin_unlock(&info->lock);
1308 if (error)
1309 goto failed;
1310 goto repeat;
1311 }
1312 wait_on_page_locked(swappage);
1313 page_cache_release(swappage);
1314 goto repeat;
1315 }
1316
1317 /* We have to do this with page locked to prevent races */
Nick Piggin529ae9a2008-08-02 12:01:03 +02001318 if (!trylock_page(swappage)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 shmem_swp_unmap(entry);
1320 spin_unlock(&info->lock);
1321 wait_on_page_locked(swappage);
1322 page_cache_release(swappage);
1323 goto repeat;
1324 }
1325 if (PageWriteback(swappage)) {
1326 shmem_swp_unmap(entry);
1327 spin_unlock(&info->lock);
1328 wait_on_page_writeback(swappage);
1329 unlock_page(swappage);
1330 page_cache_release(swappage);
1331 goto repeat;
1332 }
1333 if (!PageUptodate(swappage)) {
1334 shmem_swp_unmap(entry);
1335 spin_unlock(&info->lock);
1336 unlock_page(swappage);
1337 page_cache_release(swappage);
1338 error = -EIO;
1339 goto failed;
1340 }
1341
1342 if (filepage) {
1343 shmem_swp_set(info, entry, 0);
1344 shmem_swp_unmap(entry);
1345 delete_from_swap_cache(swappage);
1346 spin_unlock(&info->lock);
1347 copy_highpage(filepage, swappage);
1348 unlock_page(swappage);
1349 page_cache_release(swappage);
1350 flush_dcache_page(filepage);
1351 SetPageUptodate(filepage);
1352 set_page_dirty(filepage);
1353 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -07001354 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1355 idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001356 info->flags |= SHMEM_PAGEIN;
1357 shmem_swp_set(info, entry, 0);
1358 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001359 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001360 spin_unlock(&info->lock);
1361 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001362 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001363 swap_free(swap);
1364 } else {
1365 shmem_swp_unmap(entry);
1366 spin_unlock(&info->lock);
Hugh Dickins82369552008-02-07 00:14:22 -08001367 if (error == -ENOMEM) {
Daisuke Nishimuraae3abae2009-04-30 15:08:19 -07001368 /*
1369 * reclaim from proper memory cgroup and
1370 * call memcg's OOM if needed.
1371 */
1372 error = mem_cgroup_shmem_charge_fallback(
1373 swappage,
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001374 current->mm,
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001375 gfp);
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001376 if (error) {
1377 unlock_page(swappage);
1378 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001379 goto failed;
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001380 }
Hugh Dickins82369552008-02-07 00:14:22 -08001381 }
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001382 unlock_page(swappage);
1383 page_cache_release(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 goto repeat;
1385 }
1386 } else if (sgp == SGP_READ && !filepage) {
1387 shmem_swp_unmap(entry);
1388 filepage = find_get_page(mapping, idx);
1389 if (filepage &&
Nick Piggin529ae9a2008-08-02 12:01:03 +02001390 (!PageUptodate(filepage) || !trylock_page(filepage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 spin_unlock(&info->lock);
1392 wait_on_page_locked(filepage);
1393 page_cache_release(filepage);
1394 filepage = NULL;
1395 goto repeat;
1396 }
1397 spin_unlock(&info->lock);
1398 } else {
1399 shmem_swp_unmap(entry);
1400 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001401 if (sbinfo->max_blocks) {
Tim Chen7e496292010-08-09 17:19:05 -07001402 if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 shmem_acct_block(info->flags)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001404 spin_unlock(&info->lock);
1405 error = -ENOSPC;
1406 goto failed;
1407 }
Tim Chen7e496292010-08-09 17:19:05 -07001408 percpu_counter_inc(&sbinfo->used_blocks);
1409 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 inode->i_blocks += BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -07001411 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 } else if (shmem_acct_block(info->flags)) {
1413 spin_unlock(&info->lock);
1414 error = -ENOSPC;
1415 goto failed;
1416 }
1417
1418 if (!filepage) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001419 int ret;
1420
Shaohua Liff36b8012010-08-09 17:19:06 -07001421 if (!prealloc_page) {
1422 spin_unlock(&info->lock);
1423 filepage = shmem_alloc_page(gfp, info, idx);
1424 if (!filepage) {
1425 shmem_unacct_blocks(info->flags, 1);
1426 shmem_free_blocks(inode, 1);
1427 error = -ENOMEM;
1428 goto failed;
1429 }
1430 SetPageSwapBacked(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431
Shaohua Liff36b8012010-08-09 17:19:06 -07001432 /*
1433 * Precharge page while we can wait, compensate
1434 * after
1435 */
1436 error = mem_cgroup_cache_charge(filepage,
1437 current->mm, GFP_KERNEL);
1438 if (error) {
1439 page_cache_release(filepage);
1440 shmem_unacct_blocks(info->flags, 1);
1441 shmem_free_blocks(inode, 1);
1442 filepage = NULL;
1443 goto failed;
1444 }
1445
1446 spin_lock(&info->lock);
1447 } else {
1448 filepage = prealloc_page;
1449 prealloc_page = NULL;
1450 SetPageSwapBacked(filepage);
Hugh Dickins82369552008-02-07 00:14:22 -08001451 }
1452
Linus Torvalds1da177e2005-04-16 15:20:36 -07001453 entry = shmem_swp_alloc(info, idx, sgp);
1454 if (IS_ERR(entry))
1455 error = PTR_ERR(entry);
1456 else {
1457 swap = *entry;
1458 shmem_swp_unmap(entry);
1459 }
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001460 ret = error || swap.val;
1461 if (ret)
1462 mem_cgroup_uncharge_cache_page(filepage);
1463 else
1464 ret = add_to_page_cache_lru(filepage, mapping,
1465 idx, GFP_NOWAIT);
1466 /*
1467 * At add_to_page_cache_lru() failure, uncharge will
1468 * be done automatically.
1469 */
1470 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 spin_unlock(&info->lock);
1472 page_cache_release(filepage);
1473 shmem_unacct_blocks(info->flags, 1);
1474 shmem_free_blocks(inode, 1);
1475 filepage = NULL;
1476 if (error)
1477 goto failed;
1478 goto repeat;
1479 }
1480 info->flags |= SHMEM_PAGEIN;
1481 }
1482
1483 info->alloced++;
1484 spin_unlock(&info->lock);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001485 clear_highpage(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001486 flush_dcache_page(filepage);
1487 SetPageUptodate(filepage);
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001488 if (sgp == SGP_DIRTY)
1489 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 }
1491done:
Hugh Dickinsd3602442008-02-04 22:28:44 -08001492 *pagep = filepage;
Shaohua Liff36b8012010-08-09 17:19:06 -07001493 error = 0;
1494 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495
1496failed:
1497 if (*pagep != filepage) {
1498 unlock_page(filepage);
1499 page_cache_release(filepage);
1500 }
Shaohua Liff36b8012010-08-09 17:19:06 -07001501out:
1502 if (prealloc_page) {
1503 mem_cgroup_uncharge_cache_page(prealloc_page);
1504 page_cache_release(prealloc_page);
1505 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506 return error;
1507}
1508
Nick Piggind0217ac2007-07-19 01:47:03 -07001509static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001511 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001513 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514
Nick Piggind0217ac2007-07-19 01:47:03 -07001515 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1516 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001517
Hugh Dickins27d54b32008-02-04 22:28:43 -08001518 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001519 if (error)
1520 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001521
Nick Piggin83c54072007-07-19 01:47:05 -07001522 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001523}
1524
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001526static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001528 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1530}
1531
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001532static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1533 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001535 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001536 unsigned long idx;
1537
1538 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1539 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1540}
1541#endif
1542
1543int shmem_lock(struct file *file, int lock, struct user_struct *user)
1544{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001545 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 struct shmem_inode_info *info = SHMEM_I(inode);
1547 int retval = -ENOMEM;
1548
1549 spin_lock(&info->lock);
1550 if (lock && !(info->flags & VM_LOCKED)) {
1551 if (!user_shm_lock(inode->i_size, user))
1552 goto out_nomem;
1553 info->flags |= VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001554 mapping_set_unevictable(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 }
1556 if (!lock && (info->flags & VM_LOCKED) && user) {
1557 user_shm_unlock(inode->i_size, user);
1558 info->flags &= ~VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001559 mapping_clear_unevictable(file->f_mapping);
1560 scan_mapping_unevictable_pages(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 }
1562 retval = 0;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001563
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564out_nomem:
1565 spin_unlock(&info->lock);
1566 return retval;
1567}
1568
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001569static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570{
1571 file_accessed(file);
1572 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001573 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 return 0;
1575}
1576
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001577static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1578 int mode, dev_t dev, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579{
1580 struct inode *inode;
1581 struct shmem_inode_info *info;
1582 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1583
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001584 if (shmem_reserve_inode(sb))
1585 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001586
1587 inode = new_inode(sb);
1588 if (inode) {
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001589 inode_init_owner(inode, dir, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001590 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001591 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1592 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001593 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001594 info = SHMEM_I(inode);
1595 memset(info, 0, (char *)inode - (char *)info);
1596 spin_lock_init(&info->lock);
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001597 info->flags = flags & VM_NORESERVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001598 INIT_LIST_HEAD(&info->swaplist);
Al Viro72c04902009-06-24 16:58:48 -04001599 cache_no_acl(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001600
1601 switch (mode & S_IFMT) {
1602 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001603 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 init_special_inode(inode, mode, dev);
1605 break;
1606 case S_IFREG:
Hugh Dickins14fcc232008-07-28 15:46:19 -07001607 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001608 inode->i_op = &shmem_inode_operations;
1609 inode->i_fop = &shmem_file_operations;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001610 mpol_shared_policy_init(&info->policy,
1611 shmem_get_sbmpol(sbinfo));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 break;
1613 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001614 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001615 /* Some things misbehave if size == 0 on a directory */
1616 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1617 inode->i_op = &shmem_dir_inode_operations;
1618 inode->i_fop = &simple_dir_operations;
1619 break;
1620 case S_IFLNK:
1621 /*
1622 * Must not load anything in the rbtree,
1623 * mpol_free_shared_policy will not be called.
1624 */
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001625 mpol_shared_policy_init(&info->policy, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 break;
1627 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001628 } else
1629 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001630 return inode;
1631}
1632
1633#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001634static const struct inode_operations shmem_symlink_inode_operations;
1635static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636
1637/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001638 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae9764162007-06-04 10:00:39 +02001639 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1640 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 */
Hugh Dickinsae9764162007-06-04 10:00:39 +02001642static int shmem_readpage(struct file *file, struct page *page)
1643{
1644 struct inode *inode = page->mapping->host;
1645 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1646 unlock_page(page);
1647 return error;
1648}
1649
Linus Torvalds1da177e2005-04-16 15:20:36 -07001650static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001651shmem_write_begin(struct file *file, struct address_space *mapping,
1652 loff_t pos, unsigned len, unsigned flags,
1653 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654{
Nick Piggin800d15a2007-10-16 01:25:03 -07001655 struct inode *inode = mapping->host;
1656 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1657 *pagep = NULL;
1658 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1659}
1660
1661static int
1662shmem_write_end(struct file *file, struct address_space *mapping,
1663 loff_t pos, unsigned len, unsigned copied,
1664 struct page *page, void *fsdata)
1665{
1666 struct inode *inode = mapping->host;
1667
Hugh Dickinsd3602442008-02-04 22:28:44 -08001668 if (pos + copied > inode->i_size)
1669 i_size_write(inode, pos + copied);
1670
Nick Piggin800d15a2007-10-16 01:25:03 -07001671 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02001672 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001673 page_cache_release(page);
1674
Nick Piggin800d15a2007-10-16 01:25:03 -07001675 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001676}
1677
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1679{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001680 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001681 struct address_space *mapping = inode->i_mapping;
1682 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001683 enum sgp_type sgp = SGP_READ;
1684
1685 /*
1686 * Might this read be for a stacking filesystem? Then when reading
1687 * holes of a sparse file, we actually need to allocate those pages,
1688 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1689 */
1690 if (segment_eq(get_fs(), KERNEL_DS))
1691 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692
1693 index = *ppos >> PAGE_CACHE_SHIFT;
1694 offset = *ppos & ~PAGE_CACHE_MASK;
1695
1696 for (;;) {
1697 struct page *page = NULL;
1698 unsigned long end_index, nr, ret;
1699 loff_t i_size = i_size_read(inode);
1700
1701 end_index = i_size >> PAGE_CACHE_SHIFT;
1702 if (index > end_index)
1703 break;
1704 if (index == end_index) {
1705 nr = i_size & ~PAGE_CACHE_MASK;
1706 if (nr <= offset)
1707 break;
1708 }
1709
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001710 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711 if (desc->error) {
1712 if (desc->error == -EINVAL)
1713 desc->error = 0;
1714 break;
1715 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001716 if (page)
1717 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001718
1719 /*
1720 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001721 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001722 */
1723 nr = PAGE_CACHE_SIZE;
1724 i_size = i_size_read(inode);
1725 end_index = i_size >> PAGE_CACHE_SHIFT;
1726 if (index == end_index) {
1727 nr = i_size & ~PAGE_CACHE_MASK;
1728 if (nr <= offset) {
1729 if (page)
1730 page_cache_release(page);
1731 break;
1732 }
1733 }
1734 nr -= offset;
1735
1736 if (page) {
1737 /*
1738 * If users can be writing to this page using arbitrary
1739 * virtual addresses, take care about potential aliasing
1740 * before reading the page on the kernel side.
1741 */
1742 if (mapping_writably_mapped(mapping))
1743 flush_dcache_page(page);
1744 /*
1745 * Mark the page accessed if we read the beginning.
1746 */
1747 if (!offset)
1748 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001749 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001751 page_cache_get(page);
1752 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001753
1754 /*
1755 * Ok, we have the page, and it's up-to-date, so
1756 * now we can copy it to user space...
1757 *
1758 * The actor routine returns how many bytes were actually used..
1759 * NOTE! This may not be the same as how much of a user buffer
1760 * we filled up (we may be padding etc), so we can only update
1761 * "pos" here (the actor routine has to update the user buffer
1762 * pointers and the remaining count).
1763 */
1764 ret = actor(desc, page, offset, nr);
1765 offset += ret;
1766 index += offset >> PAGE_CACHE_SHIFT;
1767 offset &= ~PAGE_CACHE_MASK;
1768
1769 page_cache_release(page);
1770 if (ret != nr || !desc->count)
1771 break;
1772
1773 cond_resched();
1774 }
1775
1776 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1777 file_accessed(filp);
1778}
1779
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001780static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1781 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782{
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001783 struct file *filp = iocb->ki_filp;
1784 ssize_t retval;
1785 unsigned long seg;
1786 size_t count;
1787 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001788
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001789 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1790 if (retval)
1791 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001792
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001793 for (seg = 0; seg < nr_segs; seg++) {
1794 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001796 desc.written = 0;
1797 desc.arg.buf = iov[seg].iov_base;
1798 desc.count = iov[seg].iov_len;
1799 if (desc.count == 0)
1800 continue;
1801 desc.error = 0;
1802 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1803 retval += desc.written;
1804 if (desc.error) {
1805 retval = retval ?: desc.error;
1806 break;
1807 }
1808 if (desc.count > 0)
1809 break;
1810 }
1811 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001812}
1813
David Howells726c3342006-06-23 02:02:58 -07001814static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815{
David Howells726c3342006-06-23 02:02:58 -07001816 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817
1818 buf->f_type = TMPFS_MAGIC;
1819 buf->f_bsize = PAGE_CACHE_SIZE;
1820 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001821 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822 buf->f_blocks = sbinfo->max_blocks;
Tim Chen7e496292010-08-09 17:19:05 -07001823 buf->f_bavail = buf->f_bfree =
1824 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001825 }
1826 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827 buf->f_files = sbinfo->max_inodes;
1828 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829 }
1830 /* else leave those fields 0 like simple_statfs */
1831 return 0;
1832}
1833
1834/*
1835 * File creation. Allocate an inode, and we're done..
1836 */
1837static int
1838shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1839{
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001840 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 int error = -ENOSPC;
1842
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001843 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001844 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001845 error = security_inode_init_security(inode, dir, NULL, NULL,
1846 NULL);
1847 if (error) {
1848 if (error != -EOPNOTSUPP) {
1849 iput(inode);
1850 return error;
1851 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001852 }
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001853#ifdef CONFIG_TMPFS_POSIX_ACL
1854 error = generic_acl_init(inode, dir);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001855 if (error) {
1856 iput(inode);
1857 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001858 }
Al Viro718deb62009-12-16 19:35:36 -05001859#else
1860 error = 0;
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001861#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862 dir->i_size += BOGO_DIRENT_SIZE;
1863 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1864 d_instantiate(dentry, inode);
1865 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001866 }
1867 return error;
1868}
1869
1870static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1871{
1872 int error;
1873
1874 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1875 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001876 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001877 return 0;
1878}
1879
1880static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1881 struct nameidata *nd)
1882{
1883 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1884}
1885
1886/*
1887 * Link a file..
1888 */
1889static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1890{
1891 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001892 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001893
1894 /*
1895 * No ordinary (disk based) filesystem counts links as inodes;
1896 * but each new link needs a new dentry, pinning lowmem, and
1897 * tmpfs dentries cannot be pruned until they are unlinked.
1898 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001899 ret = shmem_reserve_inode(inode->i_sb);
1900 if (ret)
1901 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001902
1903 dir->i_size += BOGO_DIRENT_SIZE;
1904 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001905 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001906 atomic_inc(&inode->i_count); /* New dentry reference */
1907 dget(dentry); /* Extra pinning count for the created dentry */
1908 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001909out:
1910 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911}
1912
1913static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1914{
1915 struct inode *inode = dentry->d_inode;
1916
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001917 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1918 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919
1920 dir->i_size -= BOGO_DIRENT_SIZE;
1921 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001922 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001923 dput(dentry); /* Undo the count from "create" - this does all the work */
1924 return 0;
1925}
1926
1927static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1928{
1929 if (!simple_empty(dentry))
1930 return -ENOTEMPTY;
1931
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001932 drop_nlink(dentry->d_inode);
1933 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 return shmem_unlink(dir, dentry);
1935}
1936
1937/*
1938 * The VFS layer already does all the dentry stuff for rename,
1939 * we just have to decrement the usage count for the target if
1940 * it exists so that the VFS layer correctly free's it when it
1941 * gets overwritten.
1942 */
1943static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1944{
1945 struct inode *inode = old_dentry->d_inode;
1946 int they_are_dirs = S_ISDIR(inode->i_mode);
1947
1948 if (!simple_empty(new_dentry))
1949 return -ENOTEMPTY;
1950
1951 if (new_dentry->d_inode) {
1952 (void) shmem_unlink(new_dir, new_dentry);
1953 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001954 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001956 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001957 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 }
1959
1960 old_dir->i_size -= BOGO_DIRENT_SIZE;
1961 new_dir->i_size += BOGO_DIRENT_SIZE;
1962 old_dir->i_ctime = old_dir->i_mtime =
1963 new_dir->i_ctime = new_dir->i_mtime =
1964 inode->i_ctime = CURRENT_TIME;
1965 return 0;
1966}
1967
1968static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1969{
1970 int error;
1971 int len;
1972 struct inode *inode;
1973 struct page *page = NULL;
1974 char *kaddr;
1975 struct shmem_inode_info *info;
1976
1977 len = strlen(symname) + 1;
1978 if (len > PAGE_CACHE_SIZE)
1979 return -ENAMETOOLONG;
1980
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001981 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 if (!inode)
1983 return -ENOSPC;
1984
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001985 error = security_inode_init_security(inode, dir, NULL, NULL,
1986 NULL);
1987 if (error) {
1988 if (error != -EOPNOTSUPP) {
1989 iput(inode);
1990 return error;
1991 }
1992 error = 0;
1993 }
1994
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995 info = SHMEM_I(inode);
1996 inode->i_size = len-1;
1997 if (len <= (char *)inode - (char *)info) {
1998 /* do it inline */
1999 memcpy(info, symname, len);
2000 inode->i_op = &shmem_symlink_inline_operations;
2001 } else {
2002 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2003 if (error) {
2004 iput(inode);
2005 return error;
2006 }
Hugh Dickins14fcc232008-07-28 15:46:19 -07002007 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002008 inode->i_op = &shmem_symlink_inode_operations;
2009 kaddr = kmap_atomic(page, KM_USER0);
2010 memcpy(kaddr, symname, len);
2011 kunmap_atomic(kaddr, KM_USER0);
2012 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02002013 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014 page_cache_release(page);
2015 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016 dir->i_size += BOGO_DIRENT_SIZE;
2017 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2018 d_instantiate(dentry, inode);
2019 dget(dentry);
2020 return 0;
2021}
2022
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002023static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002024{
2025 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002026 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002027}
2028
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002029static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030{
2031 struct page *page = NULL;
2032 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2033 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08002034 if (page)
2035 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002036 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037}
2038
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002039static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040{
2041 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002042 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 kunmap(page);
2044 mark_page_accessed(page);
2045 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002046 }
2047}
2048
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002049static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050 .readlink = generic_readlink,
2051 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002052};
2053
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002054static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055 .readlink = generic_readlink,
2056 .follow_link = shmem_follow_link,
2057 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058};
2059
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002060#ifdef CONFIG_TMPFS_POSIX_ACL
Randy Dunlap46711812008-03-19 17:00:41 -07002061/*
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002062 * Superblocks without xattr inode operations will get security.* xattr
2063 * support from the VFS "for free". As soon as we have any other xattrs
2064 * like ACLs, we also need to implement the security.* handlers at
2065 * filesystem level, though.
2066 */
2067
Christoph Hellwig431547b2009-11-13 09:52:56 +00002068static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002069 size_t list_len, const char *name,
Christoph Hellwig431547b2009-11-13 09:52:56 +00002070 size_t name_len, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002071{
Christoph Hellwig431547b2009-11-13 09:52:56 +00002072 return security_inode_listsecurity(dentry->d_inode, list, list_len);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002073}
2074
Christoph Hellwig431547b2009-11-13 09:52:56 +00002075static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
2076 void *buffer, size_t size, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002077{
2078 if (strcmp(name, "") == 0)
2079 return -EINVAL;
Christoph Hellwig431547b2009-11-13 09:52:56 +00002080 return xattr_getsecurity(dentry->d_inode, name, buffer, size);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002081}
2082
Christoph Hellwig431547b2009-11-13 09:52:56 +00002083static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
2084 const void *value, size_t size, int flags, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002085{
2086 if (strcmp(name, "") == 0)
2087 return -EINVAL;
Christoph Hellwig431547b2009-11-13 09:52:56 +00002088 return security_inode_setsecurity(dentry->d_inode, name, value,
2089 size, flags);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002090}
2091
Stephen Hemmingerbb435452010-05-13 17:53:14 -07002092static const struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002093 .prefix = XATTR_SECURITY_PREFIX,
2094 .list = shmem_xattr_security_list,
2095 .get = shmem_xattr_security_get,
2096 .set = shmem_xattr_security_set,
2097};
2098
Stephen Hemmingerbb435452010-05-13 17:53:14 -07002099static const struct xattr_handler *shmem_xattr_handlers[] = {
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002100 &generic_acl_access_handler,
2101 &generic_acl_default_handler,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002102 &shmem_xattr_security_handler,
2103 NULL
2104};
2105#endif
2106
David M. Grimes91828a42006-10-17 00:09:45 -07002107static struct dentry *shmem_get_parent(struct dentry *child)
2108{
2109 return ERR_PTR(-ESTALE);
2110}
2111
2112static int shmem_match(struct inode *ino, void *vfh)
2113{
2114 __u32 *fh = vfh;
2115 __u64 inum = fh[2];
2116 inum = (inum << 32) | fh[1];
2117 return ino->i_ino == inum && fh[0] == ino->i_generation;
2118}
2119
Christoph Hellwig480b1162007-10-21 16:42:13 -07002120static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2121 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002122{
David M. Grimes91828a42006-10-17 00:09:45 -07002123 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002124 struct dentry *dentry = NULL;
2125 u64 inum = fid->raw[2];
2126 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002127
Christoph Hellwig480b1162007-10-21 16:42:13 -07002128 if (fh_len < 3)
2129 return NULL;
2130
2131 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2132 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002133 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002134 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002135 iput(inode);
2136 }
2137
Christoph Hellwig480b1162007-10-21 16:42:13 -07002138 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002139}
2140
2141static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2142 int connectable)
2143{
2144 struct inode *inode = dentry->d_inode;
2145
2146 if (*len < 3)
2147 return 255;
2148
2149 if (hlist_unhashed(&inode->i_hash)) {
2150 /* Unfortunately insert_inode_hash is not idempotent,
2151 * so as we hash inodes here rather than at creation
2152 * time, we need a lock to ensure we only try
2153 * to do it once
2154 */
2155 static DEFINE_SPINLOCK(lock);
2156 spin_lock(&lock);
2157 if (hlist_unhashed(&inode->i_hash))
2158 __insert_inode_hash(inode,
2159 inode->i_ino + inode->i_generation);
2160 spin_unlock(&lock);
2161 }
2162
2163 fh[0] = inode->i_generation;
2164 fh[1] = inode->i_ino;
2165 fh[2] = ((__u64)inode->i_ino) >> 32;
2166
2167 *len = 3;
2168 return 1;
2169}
2170
Christoph Hellwig39655162007-10-21 16:42:17 -07002171static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002172 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002173 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002174 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002175};
2176
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002177static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2178 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002179{
2180 char *this_char, *value, *rest;
2181
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002182 while (options != NULL) {
2183 this_char = options;
2184 for (;;) {
2185 /*
2186 * NUL-terminate this option: unfortunately,
2187 * mount options form a comma-separated list,
2188 * but mpol's nodelist may also contain commas.
2189 */
2190 options = strchr(options, ',');
2191 if (options == NULL)
2192 break;
2193 options++;
2194 if (!isdigit(*options)) {
2195 options[-1] = '\0';
2196 break;
2197 }
2198 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199 if (!*this_char)
2200 continue;
2201 if ((value = strchr(this_char,'=')) != NULL) {
2202 *value++ = 0;
2203 } else {
2204 printk(KERN_ERR
2205 "tmpfs: No value for mount option '%s'\n",
2206 this_char);
2207 return 1;
2208 }
2209
2210 if (!strcmp(this_char,"size")) {
2211 unsigned long long size;
2212 size = memparse(value,&rest);
2213 if (*rest == '%') {
2214 size <<= PAGE_SHIFT;
2215 size *= totalram_pages;
2216 do_div(size, 100);
2217 rest++;
2218 }
2219 if (*rest)
2220 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002221 sbinfo->max_blocks =
2222 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002223 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002224 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002225 if (*rest)
2226 goto bad_val;
2227 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002228 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002229 if (*rest)
2230 goto bad_val;
2231 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002232 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002233 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002234 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002235 if (*rest)
2236 goto bad_val;
2237 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002238 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002240 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002241 if (*rest)
2242 goto bad_val;
2243 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002244 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002246 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 if (*rest)
2248 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002249 } else if (!strcmp(this_char,"mpol")) {
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002250 if (mpol_parse_str(value, &sbinfo->mpol, 1))
Robin Holt7339ff82006-01-14 13:20:48 -08002251 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252 } else {
2253 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2254 this_char);
2255 return 1;
2256 }
2257 }
2258 return 0;
2259
2260bad_val:
2261 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2262 value, this_char);
2263 return 1;
2264
2265}
2266
2267static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2268{
2269 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002270 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002271 unsigned long inodes;
2272 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002273
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002274 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002275 return error;
2276
2277 spin_lock(&sbinfo->stat_lock);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002278 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
Tim Chen7e496292010-08-09 17:19:05 -07002279 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002280 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002281 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002282 goto out;
2283 /*
2284 * Those tests also disallow limited->unlimited while any are in
2285 * use, so i_blocks will always be zero when max_blocks is zero;
2286 * but we must separately disallow unlimited->limited, because
2287 * in that case we have no record of how much is already in use.
2288 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002289 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002290 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002291 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002292 goto out;
2293
2294 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002295 sbinfo->max_blocks = config.max_blocks;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002296 sbinfo->max_inodes = config.max_inodes;
2297 sbinfo->free_inodes = config.max_inodes - inodes;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002298
2299 mpol_put(sbinfo->mpol);
2300 sbinfo->mpol = config.mpol; /* transfers initial ref */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002301out:
2302 spin_unlock(&sbinfo->stat_lock);
2303 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002304}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002305
2306static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2307{
2308 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2309
2310 if (sbinfo->max_blocks != shmem_default_max_blocks())
2311 seq_printf(seq, ",size=%luk",
2312 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2313 if (sbinfo->max_inodes != shmem_default_max_inodes())
2314 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2315 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2316 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2317 if (sbinfo->uid != 0)
2318 seq_printf(seq, ",uid=%u", sbinfo->uid);
2319 if (sbinfo->gid != 0)
2320 seq_printf(seq, ",gid=%u", sbinfo->gid);
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002321 shmem_show_mpol(seq, sbinfo->mpol);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002322 return 0;
2323}
2324#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325
2326static void shmem_put_super(struct super_block *sb)
2327{
2328 kfree(sb->s_fs_info);
2329 sb->s_fs_info = NULL;
2330}
2331
Kay Sievers2b2af542009-04-30 15:23:42 +02002332int shmem_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333{
2334 struct inode *inode;
2335 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002336 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002337 int err = -ENOMEM;
2338
2339 /* Round up to L1_CACHE_BYTES to resist false sharing */
Pekka Enberg425fbf02009-09-21 17:03:50 -07002340 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002341 L1_CACHE_BYTES), GFP_KERNEL);
2342 if (!sbinfo)
2343 return -ENOMEM;
2344
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002345 sbinfo->mode = S_IRWXUGO | S_ISVTX;
David Howells76aac0e2008-11-14 10:39:12 +11002346 sbinfo->uid = current_fsuid();
2347 sbinfo->gid = current_fsgid();
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002348 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002350#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 /*
2352 * Per default we only allow half of the physical ram per
2353 * tmpfs instance, limiting inodes to one per page of lowmem;
2354 * but the internal instance is left unlimited.
2355 */
2356 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002357 sbinfo->max_blocks = shmem_default_max_blocks();
2358 sbinfo->max_inodes = shmem_default_max_inodes();
2359 if (shmem_parse_options(data, sbinfo, false)) {
2360 err = -EINVAL;
2361 goto failed;
2362 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002363 }
David M. Grimes91828a42006-10-17 00:09:45 -07002364 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002365#else
2366 sb->s_flags |= MS_NOUSER;
2367#endif
2368
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002369 spin_lock_init(&sbinfo->stat_lock);
Tim Chen7e496292010-08-09 17:19:05 -07002370 percpu_counter_init(&sbinfo->used_blocks, 0);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002371 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002372
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373 sb->s_maxbytes = SHMEM_MAX_BYTES;
2374 sb->s_blocksize = PAGE_CACHE_SIZE;
2375 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2376 sb->s_magic = TMPFS_MAGIC;
2377 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002378 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002379#ifdef CONFIG_TMPFS_POSIX_ACL
2380 sb->s_xattr = shmem_xattr_handlers;
2381 sb->s_flags |= MS_POSIXACL;
2382#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002383
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002384 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002385 if (!inode)
2386 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002387 inode->i_uid = sbinfo->uid;
2388 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002389 root = d_alloc_root(inode);
2390 if (!root)
2391 goto failed_iput;
2392 sb->s_root = root;
2393 return 0;
2394
2395failed_iput:
2396 iput(inode);
2397failed:
2398 shmem_put_super(sb);
2399 return err;
2400}
2401
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002402static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403
2404static struct inode *shmem_alloc_inode(struct super_block *sb)
2405{
2406 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002407 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002408 if (!p)
2409 return NULL;
2410 return &p->vfs_inode;
2411}
2412
2413static void shmem_destroy_inode(struct inode *inode)
2414{
2415 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2416 /* only struct inode is valid if it's an inline symlink */
2417 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2418 }
2419 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2420}
2421
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07002422static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423{
2424 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2425
Christoph Lametera35afb82007-05-16 22:10:57 -07002426 inode_init_once(&p->vfs_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427}
2428
2429static int init_inodecache(void)
2430{
2431 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2432 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002433 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 return 0;
2435}
2436
2437static void destroy_inodecache(void)
2438{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002439 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440}
2441
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002442static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002443 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002444 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002445#ifdef CONFIG_TMPFS
Hugh Dickinsae9764162007-06-04 10:00:39 +02002446 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002447 .write_begin = shmem_write_begin,
2448 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002449#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002450 .migratepage = migrate_page,
Andi Kleenaa261f52009-09-16 11:50:16 +02002451 .error_remove_page = generic_error_remove_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002452};
2453
Helge Deller15ad7cd2006-12-06 20:40:36 -08002454static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002455 .mmap = shmem_mmap,
2456#ifdef CONFIG_TMPFS
2457 .llseek = generic_file_llseek,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002458 .read = do_sync_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002459 .write = do_sync_write,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002460 .aio_read = shmem_file_aio_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002461 .aio_write = generic_file_aio_write,
Christoph Hellwig1b061d92010-05-26 17:53:41 +02002462 .fsync = noop_fsync,
Hugh Dickinsae9764162007-06-04 10:00:39 +02002463 .splice_read = generic_file_splice_read,
2464 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002465#endif
2466};
2467
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002468static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002470 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002471#ifdef CONFIG_TMPFS_POSIX_ACL
2472 .setxattr = generic_setxattr,
2473 .getxattr = generic_getxattr,
2474 .listxattr = generic_listxattr,
2475 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002476 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002477#endif
2478
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479};
2480
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002481static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482#ifdef CONFIG_TMPFS
2483 .create = shmem_create,
2484 .lookup = simple_lookup,
2485 .link = shmem_link,
2486 .unlink = shmem_unlink,
2487 .symlink = shmem_symlink,
2488 .mkdir = shmem_mkdir,
2489 .rmdir = shmem_rmdir,
2490 .mknod = shmem_mknod,
2491 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002492#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002493#ifdef CONFIG_TMPFS_POSIX_ACL
2494 .setattr = shmem_notify_change,
2495 .setxattr = generic_setxattr,
2496 .getxattr = generic_getxattr,
2497 .listxattr = generic_listxattr,
2498 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002499 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002500#endif
2501};
2502
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002503static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002504#ifdef CONFIG_TMPFS_POSIX_ACL
2505 .setattr = shmem_notify_change,
2506 .setxattr = generic_setxattr,
2507 .getxattr = generic_getxattr,
2508 .listxattr = generic_listxattr,
2509 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002510 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002511#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512};
2513
Hugh Dickins759b9772007-03-05 00:30:28 -08002514static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515 .alloc_inode = shmem_alloc_inode,
2516 .destroy_inode = shmem_destroy_inode,
2517#ifdef CONFIG_TMPFS
2518 .statfs = shmem_statfs,
2519 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002520 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002521#endif
Al Viro1f895f72010-06-05 19:10:41 -04002522 .evict_inode = shmem_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002523 .drop_inode = generic_delete_inode,
2524 .put_super = shmem_put_super,
2525};
2526
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04002527static const struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002528 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002529#ifdef CONFIG_NUMA
2530 .set_policy = shmem_set_policy,
2531 .get_policy = shmem_get_policy,
2532#endif
2533};
2534
2535
David Howells454e2392006-06-23 02:02:57 -07002536static int shmem_get_sb(struct file_system_type *fs_type,
2537 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002538{
David Howells454e2392006-06-23 02:02:57 -07002539 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002540}
2541
2542static struct file_system_type tmpfs_fs_type = {
2543 .owner = THIS_MODULE,
2544 .name = "tmpfs",
2545 .get_sb = shmem_get_sb,
2546 .kill_sb = kill_litter_super,
2547};
Linus Torvalds1da177e2005-04-16 15:20:36 -07002548
Kay Sievers2b2af542009-04-30 15:23:42 +02002549int __init init_tmpfs(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002550{
2551 int error;
2552
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002553 error = bdi_init(&shmem_backing_dev_info);
2554 if (error)
2555 goto out4;
2556
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 error = init_inodecache();
2558 if (error)
2559 goto out3;
2560
2561 error = register_filesystem(&tmpfs_fs_type);
2562 if (error) {
2563 printk(KERN_ERR "Could not register tmpfs\n");
2564 goto out2;
2565 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002566
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002567 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002568 tmpfs_fs_type.name, NULL);
2569 if (IS_ERR(shm_mnt)) {
2570 error = PTR_ERR(shm_mnt);
2571 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2572 goto out1;
2573 }
2574 return 0;
2575
2576out1:
2577 unregister_filesystem(&tmpfs_fs_type);
2578out2:
2579 destroy_inodecache();
2580out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002581 bdi_destroy(&shmem_backing_dev_info);
2582out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002583 shm_mnt = ERR_PTR(error);
2584 return error;
2585}
Matt Mackall853ac432009-01-06 14:40:20 -08002586
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002587#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2588/**
2589 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2590 * @inode: the inode to be searched
2591 * @pgoff: the offset to be searched
2592 * @pagep: the pointer for the found page to be stored
2593 * @ent: the pointer for the found swap entry to be stored
2594 *
2595 * If a page is found, refcount of it is incremented. Callers should handle
2596 * these refcount.
2597 */
2598void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2599 struct page **pagep, swp_entry_t *ent)
2600{
2601 swp_entry_t entry = { .val = 0 }, *ptr;
2602 struct page *page = NULL;
2603 struct shmem_inode_info *info = SHMEM_I(inode);
2604
2605 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2606 goto out;
2607
2608 spin_lock(&info->lock);
2609 ptr = shmem_swp_entry(info, pgoff, NULL);
2610#ifdef CONFIG_SWAP
2611 if (ptr && ptr->val) {
2612 entry.val = ptr->val;
2613 page = find_get_page(&swapper_space, entry.val);
2614 } else
2615#endif
2616 page = find_get_page(inode->i_mapping, pgoff);
2617 if (ptr)
2618 shmem_swp_unmap(ptr);
2619 spin_unlock(&info->lock);
2620out:
2621 *pagep = page;
2622 *ent = entry;
2623}
2624#endif
2625
Matt Mackall853ac432009-01-06 14:40:20 -08002626#else /* !CONFIG_SHMEM */
2627
2628/*
2629 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2630 *
2631 * This is intended for small system where the benefits of the full
2632 * shmem code (swap-backed and resource-limited) are outweighed by
2633 * their complexity. On systems without swap this code should be
2634 * effectively equivalent, but much lighter weight.
2635 */
2636
2637#include <linux/ramfs.h>
2638
2639static struct file_system_type tmpfs_fs_type = {
2640 .name = "tmpfs",
2641 .get_sb = ramfs_get_sb,
2642 .kill_sb = kill_litter_super,
2643};
2644
Kay Sievers2b2af542009-04-30 15:23:42 +02002645int __init init_tmpfs(void)
Matt Mackall853ac432009-01-06 14:40:20 -08002646{
2647 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2648
2649 shm_mnt = kern_mount(&tmpfs_fs_type);
2650 BUG_ON(IS_ERR(shm_mnt));
2651
2652 return 0;
2653}
2654
2655int shmem_unuse(swp_entry_t entry, struct page *page)
2656{
2657 return 0;
2658}
2659
Hugh Dickins3f96b792009-09-21 17:03:37 -07002660int shmem_lock(struct file *file, int lock, struct user_struct *user)
2661{
2662 return 0;
2663}
2664
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002665#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2666/**
2667 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2668 * @inode: the inode to be searched
2669 * @pgoff: the offset to be searched
2670 * @pagep: the pointer for the found page to be stored
2671 * @ent: the pointer for the found swap entry to be stored
2672 *
2673 * If a page is found, refcount of it is incremented. Callers should handle
2674 * these refcount.
2675 */
2676void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2677 struct page **pagep, swp_entry_t *ent)
2678{
2679 struct page *page = NULL;
2680
2681 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2682 goto out;
2683 page = find_get_page(inode->i_mapping, pgoff);
2684out:
2685 *pagep = page;
2686 *ent = (swp_entry_t){ .val = 0 };
2687}
2688#endif
2689
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002690#define shmem_vm_ops generic_file_vm_ops
2691#define shmem_file_operations ramfs_file_operations
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002692#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002693#define shmem_acct_size(flags, size) 0
2694#define shmem_unacct_size(flags, size) do {} while (0)
Hugh Dickinscaefba12009-04-13 14:40:12 -07002695#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
Matt Mackall853ac432009-01-06 14:40:20 -08002696
2697#endif /* CONFIG_SHMEM */
2698
2699/* common code */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002700
Randy Dunlap46711812008-03-19 17:00:41 -07002701/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002702 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002703 * @name: name for dentry (to be seen in /proc/<pid>/maps
2704 * @size: size to be set for the file
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002705 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
Linus Torvalds1da177e2005-04-16 15:20:36 -07002706 */
Sergei Trofimovich168f5ac2009-06-16 15:33:02 -07002707struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002708{
2709 int error;
2710 struct file *file;
2711 struct inode *inode;
Al Viro2c48b9c2009-08-09 00:52:35 +04002712 struct path path;
2713 struct dentry *root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002714 struct qstr this;
2715
2716 if (IS_ERR(shm_mnt))
2717 return (void *)shm_mnt;
2718
2719 if (size < 0 || size > SHMEM_MAX_BYTES)
2720 return ERR_PTR(-EINVAL);
2721
2722 if (shmem_acct_size(flags, size))
2723 return ERR_PTR(-ENOMEM);
2724
2725 error = -ENOMEM;
2726 this.name = name;
2727 this.len = strlen(name);
2728 this.hash = 0; /* will go */
2729 root = shm_mnt->mnt_root;
Al Viro2c48b9c2009-08-09 00:52:35 +04002730 path.dentry = d_alloc(root, &this);
2731 if (!path.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002732 goto put_memory;
Al Viro2c48b9c2009-08-09 00:52:35 +04002733 path.mnt = mntget(shm_mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735 error = -ENOSPC;
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002736 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002737 if (!inode)
Al Viro4b42af82009-08-05 18:25:56 +04002738 goto put_dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002739
Al Viro2c48b9c2009-08-09 00:52:35 +04002740 d_instantiate(path.dentry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002741 inode->i_size = size;
2742 inode->i_nlink = 0; /* It is unlinked */
Matt Mackall853ac432009-01-06 14:40:20 -08002743#ifndef CONFIG_MMU
2744 error = ramfs_nommu_expand_for_mapping(inode, size);
2745 if (error)
Al Viro4b42af82009-08-05 18:25:56 +04002746 goto put_dentry;
Matt Mackall853ac432009-01-06 14:40:20 -08002747#endif
Al Viro4b42af82009-08-05 18:25:56 +04002748
2749 error = -ENFILE;
Al Viro2c48b9c2009-08-09 00:52:35 +04002750 file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
Al Viro4b42af82009-08-05 18:25:56 +04002751 &shmem_file_operations);
2752 if (!file)
2753 goto put_dentry;
2754
Linus Torvalds1da177e2005-04-16 15:20:36 -07002755 return file;
2756
Linus Torvalds1da177e2005-04-16 15:20:36 -07002757put_dentry:
Al Viro2c48b9c2009-08-09 00:52:35 +04002758 path_put(&path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002759put_memory:
2760 shmem_unacct_size(flags, size);
2761 return ERR_PTR(error);
2762}
Keith Packard395e0dd2008-06-20 00:08:06 -07002763EXPORT_SYMBOL_GPL(shmem_file_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002764
Randy Dunlap46711812008-03-19 17:00:41 -07002765/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002766 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2768 */
2769int shmem_zero_setup(struct vm_area_struct *vma)
2770{
2771 struct file *file;
2772 loff_t size = vma->vm_end - vma->vm_start;
2773
2774 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2775 if (IS_ERR(file))
2776 return PTR_ERR(file);
2777
2778 if (vma->vm_file)
2779 fput(vma->vm_file);
2780 vma->vm_file = file;
2781 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002782 return 0;
2783}