blob: ba4ad28b7db6b81c141915a5d3eb4241fdbfd1a7 [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};
228
229static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800230static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
232static void shmem_free_blocks(struct inode *inode, long pages)
233{
234 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700235 if (sbinfo->max_blocks) {
Tim Chen7e496292010-08-09 17:19:05 -0700236 percpu_counter_add(&sbinfo->used_blocks, -pages);
237 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -0700239 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 }
241}
242
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800243static int shmem_reserve_inode(struct super_block *sb)
244{
245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
246 if (sbinfo->max_inodes) {
247 spin_lock(&sbinfo->stat_lock);
248 if (!sbinfo->free_inodes) {
249 spin_unlock(&sbinfo->stat_lock);
250 return -ENOSPC;
251 }
252 sbinfo->free_inodes--;
253 spin_unlock(&sbinfo->stat_lock);
254 }
255 return 0;
256}
257
258static void shmem_free_inode(struct super_block *sb)
259{
260 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
261 if (sbinfo->max_inodes) {
262 spin_lock(&sbinfo->stat_lock);
263 sbinfo->free_inodes++;
264 spin_unlock(&sbinfo->stat_lock);
265 }
266}
267
Randy Dunlap46711812008-03-19 17:00:41 -0700268/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 * @inode: inode to recalc
271 *
272 * We have to calculate the free blocks since the mm can drop
273 * undirtied hole pages behind our back.
274 *
275 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
276 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
277 *
278 * It has to be called with the spinlock held.
279 */
280static void shmem_recalc_inode(struct inode *inode)
281{
282 struct shmem_inode_info *info = SHMEM_I(inode);
283 long freed;
284
285 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
286 if (freed > 0) {
287 info->alloced -= freed;
288 shmem_unacct_blocks(info->flags, freed);
289 shmem_free_blocks(inode, freed);
290 }
291}
292
Randy Dunlap46711812008-03-19 17:00:41 -0700293/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 * @info: info structure for the inode
296 * @index: index of the page to find
297 * @page: optional page to add to the structure. Has to be preset to
298 * all zeros
299 *
300 * If there is no space allocated yet it will return NULL when
301 * page is NULL, else it will use the page for the needed block,
302 * setting it to NULL on return to indicate that it has been used.
303 *
304 * The swap vector is organized the following way:
305 *
306 * There are SHMEM_NR_DIRECT entries directly stored in the
307 * shmem_inode_info structure. So small files do not need an addional
308 * allocation.
309 *
310 * For pages with index > SHMEM_NR_DIRECT there is the pointer
311 * i_indirect which points to a page which holds in the first half
312 * doubly indirect blocks, in the second half triple indirect blocks:
313 *
314 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
315 * following layout (for SHMEM_NR_DIRECT == 16):
316 *
317 * i_indirect -> dir --> 16-19
318 * | +-> 20-23
319 * |
320 * +-->dir2 --> 24-27
321 * | +-> 28-31
322 * | +-> 32-35
323 * | +-> 36-39
324 * |
325 * +-->dir3 --> 40-43
326 * +-> 44-47
327 * +-> 48-51
328 * +-> 52-55
329 */
330static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
331{
332 unsigned long offset;
333 struct page **dir;
334 struct page *subdir;
335
336 if (index < SHMEM_NR_DIRECT) {
337 shmem_swp_balance_unmap();
338 return info->i_direct+index;
339 }
340 if (!info->i_indirect) {
341 if (page) {
342 info->i_indirect = *page;
343 *page = NULL;
344 }
345 return NULL; /* need another page */
346 }
347
348 index -= SHMEM_NR_DIRECT;
349 offset = index % ENTRIES_PER_PAGE;
350 index /= ENTRIES_PER_PAGE;
351 dir = shmem_dir_map(info->i_indirect);
352
353 if (index >= ENTRIES_PER_PAGE/2) {
354 index -= ENTRIES_PER_PAGE/2;
355 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
356 index %= ENTRIES_PER_PAGE;
357 subdir = *dir;
358 if (!subdir) {
359 if (page) {
360 *dir = *page;
361 *page = NULL;
362 }
363 shmem_dir_unmap(dir);
364 return NULL; /* need another page */
365 }
366 shmem_dir_unmap(dir);
367 dir = shmem_dir_map(subdir);
368 }
369
370 dir += index;
371 subdir = *dir;
372 if (!subdir) {
373 if (!page || !(subdir = *page)) {
374 shmem_dir_unmap(dir);
375 return NULL; /* need a page */
376 }
377 *dir = subdir;
378 *page = NULL;
379 }
380 shmem_dir_unmap(dir);
381 return shmem_swp_map(subdir) + offset;
382}
383
384static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
385{
386 long incdec = value? 1: -1;
387
388 entry->val = value;
389 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700390 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
391 struct page *page = kmap_atomic_to_page(entry);
392 set_page_private(page, page_private(page) + incdec);
393 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394}
395
Randy Dunlap46711812008-03-19 17:00:41 -0700396/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 * @info: info structure for the inode
399 * @index: index of the page to find
400 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700401 *
402 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 */
404static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
405{
406 struct inode *inode = &info->vfs_inode;
407 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
408 struct page *page = NULL;
409 swp_entry_t *entry;
410
411 if (sgp != SGP_WRITE &&
412 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
413 return ERR_PTR(-EINVAL);
414
415 while (!(entry = shmem_swp_entry(info, index, &page))) {
416 if (sgp == SGP_READ)
417 return shmem_swp_map(ZERO_PAGE(0));
418 /*
Tim Chen7e496292010-08-09 17:19:05 -0700419 * Test used_blocks against 1 less max_blocks, since we have 1 data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 * page (and perhaps indirect index pages) yet to allocate:
421 * a waste to allocate index if we cannot allocate data.
422 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700423 if (sbinfo->max_blocks) {
Hugh Dickinsfc5da222011-04-14 15:22:07 -0700424 if (percpu_counter_compare(&sbinfo->used_blocks,
425 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
Justin P. Mattockae0e47f2011-03-01 15:06:02 +0100782 * truncate_partial_page cannot miss it were
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 * 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{
Hugh Dickins778dd892011-05-11 15:13:37 -0700855 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 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 Dickins778dd892011-05-11 15:13:37 -0700878 if (offset >= 0) {
879 shmem_swp_balance_unmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 goto found;
Hugh Dickins778dd892011-05-11 15:13:37 -0700881 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 if (!info->i_indirect)
883 goto lost2;
884
885 dir = shmem_dir_map(info->i_indirect);
886 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
887
888 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
889 if (unlikely(idx == stage)) {
890 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800891 if (cond_resched_lock(&info->lock)) {
892 /* check it has not been truncated */
893 if (limit > info->next_index) {
894 limit = info->next_index;
895 if (idx >= limit)
896 goto lost2;
897 }
898 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700899 dir = shmem_dir_map(info->i_indirect) +
900 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
901 while (!*dir) {
902 dir++;
903 idx += ENTRIES_PER_PAGEPAGE;
904 if (idx >= limit)
905 goto lost1;
906 }
907 stage = idx + ENTRIES_PER_PAGEPAGE;
908 subdir = *dir;
909 shmem_dir_unmap(dir);
910 dir = shmem_dir_map(subdir);
911 }
912 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700913 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700914 ptr = shmem_swp_map(subdir);
915 size = limit - idx;
916 if (size > ENTRIES_PER_PAGE)
917 size = ENTRIES_PER_PAGE;
918 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickinse6c93662011-05-20 15:47:33 -0700919 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 if (offset >= 0) {
921 shmem_dir_unmap(dir);
Hugh Dickinse6c93662011-05-20 15:47:33 -0700922 ptr = shmem_swp_map(subdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 goto found;
924 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 }
926 }
927lost1:
928 shmem_dir_unmap(dir-1);
929lost2:
930 spin_unlock(&info->lock);
931 return 0;
932found:
933 idx += offset;
Hugh Dickins778dd892011-05-11 15:13:37 -0700934 ptr += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800935
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800936 /*
937 * Move _head_ to start search for next from here.
Al Viro1f895f72010-06-05 19:10:41 -0400938 * But be careful: shmem_evict_inode checks list_empty without taking
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800939 * mutex, and there's an instant in list_move_tail when info->swaplist
940 * would appear empty, if it were the only one on shmem_swaplist. We
941 * could avoid doing it if inode NULL; or use this minor optimization.
942 */
943 if (shmem_swaplist.next != &info->swaplist)
944 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800945
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800946 /*
Hugh Dickins778dd892011-05-11 15:13:37 -0700947 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
948 * but also to hold up shmem_evict_inode(): so inode cannot be freed
949 * beneath us (pagelock doesn't help until the page is in pagecache).
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800950 */
Hugh Dickins778dd892011-05-11 15:13:37 -0700951 mapping = info->vfs_inode.i_mapping;
952 error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
953 /* which does mem_cgroup_uncharge_cache_page on error */
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700954
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800955 if (error == -EEXIST) {
Hugh Dickins778dd892011-05-11 15:13:37 -0700956 struct page *filepage = find_get_page(mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800957 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800958 if (filepage) {
959 /*
960 * There might be a more uptodate page coming down
961 * from a stacked writepage: forget our swappage if so.
962 */
963 if (PageUptodate(filepage))
964 error = 0;
965 page_cache_release(filepage);
966 }
967 }
968 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800969 delete_from_swap_cache(page);
970 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800972 shmem_swp_set(info, ptr, 0);
973 swap_free(entry);
974 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975 }
Hugh Dickins778dd892011-05-11 15:13:37 -0700976 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977 spin_unlock(&info->lock);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800978 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979}
980
981/*
982 * shmem_unuse() search for an eventually swapped out shmem page.
983 */
984int shmem_unuse(swp_entry_t entry, struct page *page)
985{
986 struct list_head *p, *next;
987 struct shmem_inode_info *info;
988 int found = 0;
Hugh Dickins778dd892011-05-11 15:13:37 -0700989 int error;
990
991 /*
992 * Charge page using GFP_KERNEL while we can wait, before taking
993 * the shmem_swaplist_mutex which might hold up shmem_writepage().
994 * Charged back to the user (not to caller) when swap account is used.
995 * add_to_page_cache() will be called with GFP_NOWAIT.
996 */
997 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
998 if (error)
999 goto out;
1000 /*
1001 * Try to preload while we can wait, to not make a habit of
1002 * draining atomic reserves; but don't latch on to this cpu,
1003 * it's okay if sometimes we get rescheduled after this.
1004 */
1005 error = radix_tree_preload(GFP_KERNEL);
1006 if (error)
1007 goto uncharge;
1008 radix_tree_preload_end();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001009
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001010 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011 list_for_each_safe(p, next, &shmem_swaplist) {
1012 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001013 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001014 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001015 if (found)
Hugh Dickins778dd892011-05-11 15:13:37 -07001016 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001017 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001018 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickins778dd892011-05-11 15:13:37 -07001019
1020uncharge:
1021 if (!found)
1022 mem_cgroup_uncharge_cache_page(page);
1023 if (found < 0)
1024 error = found;
1025out:
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001026 unlock_page(page);
1027 page_cache_release(page);
Hugh Dickins778dd892011-05-11 15:13:37 -07001028 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029}
1030
1031/*
1032 * Move the page from the page cache to the swap cache.
1033 */
1034static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1035{
1036 struct shmem_inode_info *info;
1037 swp_entry_t *entry, swap;
1038 struct address_space *mapping;
1039 unsigned long index;
1040 struct inode *inode;
1041
1042 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001043 mapping = page->mapping;
1044 index = page->index;
1045 inode = mapping->host;
1046 info = SHMEM_I(inode);
1047 if (info->flags & VM_LOCKED)
1048 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001049 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001050 goto redirty;
1051
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001052 /*
1053 * shmem_backing_dev_info's capabilities prevent regular writeback or
1054 * sync from ever calling shmem_writepage; but a stacking filesystem
1055 * may use the ->writepage of its underlying filesystem, in which case
1056 * tmpfs should write out to swap only in response to memory pressure,
Jens Axboe5b0830c2009-09-23 19:37:09 +02001057 * and not for the writeback threads or sync. However, in those cases,
1058 * we do still want to check if there's a redundant swappage to be
1059 * discarded.
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001060 */
1061 if (wbc->for_reclaim)
1062 swap = get_swap_page();
1063 else
1064 swap.val = 0;
1065
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001066 /*
1067 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1068 * if it's not already there. Do it now because we cannot take
1069 * mutex while holding spinlock, and must do so before the page
1070 * is moved to swap cache, when its pagelock no longer protects
1071 * the inode from eviction. But don't unlock the mutex until
1072 * we've taken the spinlock, because shmem_unuse_inode() will
1073 * prune a !swapped inode from the swaplist under both locks.
1074 */
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001075 if (swap.val) {
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001076 mutex_lock(&shmem_swaplist_mutex);
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001077 if (list_empty(&info->swaplist))
1078 list_add_tail(&info->swaplist, &shmem_swaplist);
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001079 }
1080
Linus Torvalds1da177e2005-04-16 15:20:36 -07001081 spin_lock(&info->lock);
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001082 if (swap.val)
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001083 mutex_unlock(&shmem_swaplist_mutex);
1084
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 if (index >= info->next_index) {
1086 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1087 goto unlock;
1088 }
1089 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001090 if (entry->val) {
1091 /*
1092 * The more uptodate page coming down from a stacked
1093 * writepage should replace our old swappage.
1094 */
1095 free_swap_and_cache(*entry);
1096 shmem_swp_set(info, entry, 0);
1097 }
1098 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001099
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001100 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Minchan Kim4c73b1b2011-03-22 16:32:40 -07001101 delete_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001102 shmem_swp_set(info, entry, swap.val);
1103 shmem_swp_unmap(entry);
1104 spin_unlock(&info->lock);
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001105 swap_shmem_alloc(swap);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001106 BUG_ON(page_mapped(page));
Hugh Dickins9fab5612009-03-31 15:23:33 -07001107 swap_writepage(page, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108 return 0;
1109 }
1110
1111 shmem_swp_unmap(entry);
1112unlock:
1113 spin_unlock(&info->lock);
Daisuke Nishimura2ca45322009-09-21 17:02:52 -07001114 /*
1115 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1116 * clear SWAP_HAS_CACHE flag.
1117 */
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -07001118 swapcache_free(swap, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119redirty:
1120 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001121 if (wbc->for_reclaim)
1122 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1123 unlock_page(page);
1124 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001125}
1126
1127#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001128#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001129static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001130{
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001131 char buffer[64];
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001132
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001133 if (!mpol || mpol->mode == MPOL_DEFAULT)
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001134 return; /* show nothing */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001135
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001136 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001137
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001138 seq_printf(seq, ",mpol=%s", buffer);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001139}
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001140
1141static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1142{
1143 struct mempolicy *mpol = NULL;
1144 if (sbinfo->mpol) {
1145 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1146 mpol = sbinfo->mpol;
1147 mpol_get(mpol);
1148 spin_unlock(&sbinfo->stat_lock);
1149 }
1150 return mpol;
1151}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001152#endif /* CONFIG_TMPFS */
1153
Hugh Dickins02098fe2008-02-04 22:28:42 -08001154static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1155 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001156{
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001157 struct mempolicy mpol, *spol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001159 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001160
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001161 spol = mpol_cond_copy(&mpol,
1162 mpol_shared_policy_lookup(&info->policy, idx));
1163
Linus Torvalds1da177e2005-04-16 15:20:36 -07001164 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001165 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001166 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001167 pvma.vm_ops = NULL;
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001168 pvma.vm_policy = spol;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001169 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001170 return page;
1171}
1172
Hugh Dickins02098fe2008-02-04 22:28:42 -08001173static struct page *shmem_alloc_page(gfp_t gfp,
1174 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001175{
1176 struct vm_area_struct pvma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001178 /* Create a pseudo vma that just contains the policy */
1179 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001180 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001181 pvma.vm_ops = NULL;
1182 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001183
1184 /*
1185 * alloc_page_vma() will drop the shared policy reference
1186 */
1187 return alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001189#else /* !CONFIG_NUMA */
1190#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001191static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001192{
1193}
1194#endif /* CONFIG_TMPFS */
1195
Hugh Dickins02098fe2008-02-04 22:28:42 -08001196static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1197 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001199 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001200}
1201
Hugh Dickins02098fe2008-02-04 22:28:42 -08001202static inline struct page *shmem_alloc_page(gfp_t gfp,
1203 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001204{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001205 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001207#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001208
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001209#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1210static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1211{
1212 return NULL;
1213}
1214#endif
1215
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216/*
1217 * shmem_getpage - either get the page from swap or allocate a new one
1218 *
1219 * If we allocate a new one we do not mark it dirty. That's up to the
1220 * vm. If we swap it in we mark it dirty since we also free the swap
1221 * entry since a page cannot live in both the swap and page cache
1222 */
1223static int shmem_getpage(struct inode *inode, unsigned long idx,
1224 struct page **pagep, enum sgp_type sgp, int *type)
1225{
1226 struct address_space *mapping = inode->i_mapping;
1227 struct shmem_inode_info *info = SHMEM_I(inode);
1228 struct shmem_sb_info *sbinfo;
1229 struct page *filepage = *pagep;
1230 struct page *swappage;
Shaohua Liff36b802010-08-09 17:19:06 -07001231 struct page *prealloc_page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 swp_entry_t *entry;
1233 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001234 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001235 int error;
1236
1237 if (idx >= SHMEM_MAX_INDEX)
1238 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001239
1240 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001241 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001242
Linus Torvalds1da177e2005-04-16 15:20:36 -07001243 /*
1244 * Normally, filepage is NULL on entry, and either found
1245 * uptodate immediately, or allocated and zeroed, or read
1246 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001247 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae976412007-06-04 10:00:39 +02001248 * filepage, which may be found not uptodate by other callers
1249 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 */
1251repeat:
1252 if (!filepage)
1253 filepage = find_lock_page(mapping, idx);
1254 if (filepage && PageUptodate(filepage))
1255 goto done;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001256 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001257 if (!filepage) {
1258 /*
1259 * Try to preload while we can wait, to not make a habit of
1260 * draining atomic reserves; but don't latch on to this cpu.
1261 */
1262 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1263 if (error)
1264 goto failed;
1265 radix_tree_preload_end();
Shaohua Liff36b802010-08-09 17:19:06 -07001266 if (sgp != SGP_READ && !prealloc_page) {
1267 /* We don't care if this fails */
1268 prealloc_page = shmem_alloc_page(gfp, info, idx);
1269 if (prealloc_page) {
1270 if (mem_cgroup_cache_charge(prealloc_page,
1271 current->mm, GFP_KERNEL)) {
1272 page_cache_release(prealloc_page);
1273 prealloc_page = NULL;
1274 }
1275 }
1276 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001277 }
Shaohua Liff36b802010-08-09 17:19:06 -07001278 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279
1280 spin_lock(&info->lock);
1281 shmem_recalc_inode(inode);
1282 entry = shmem_swp_alloc(info, idx, sgp);
1283 if (IS_ERR(entry)) {
1284 spin_unlock(&info->lock);
1285 error = PTR_ERR(entry);
1286 goto failed;
1287 }
1288 swap = *entry;
1289
1290 if (swap.val) {
1291 /* Look it up and read it in.. */
1292 swappage = lookup_swap_cache(swap);
1293 if (!swappage) {
1294 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001296 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001297 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001298 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001299 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001300 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001301 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001302 if (!swappage) {
1303 spin_lock(&info->lock);
1304 entry = shmem_swp_alloc(info, idx, sgp);
1305 if (IS_ERR(entry))
1306 error = PTR_ERR(entry);
1307 else {
1308 if (entry->val == swap.val)
1309 error = -ENOMEM;
1310 shmem_swp_unmap(entry);
1311 }
1312 spin_unlock(&info->lock);
1313 if (error)
1314 goto failed;
1315 goto repeat;
1316 }
1317 wait_on_page_locked(swappage);
1318 page_cache_release(swappage);
1319 goto repeat;
1320 }
1321
1322 /* We have to do this with page locked to prevent races */
Nick Piggin529ae9a2008-08-02 12:01:03 +02001323 if (!trylock_page(swappage)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001324 shmem_swp_unmap(entry);
1325 spin_unlock(&info->lock);
1326 wait_on_page_locked(swappage);
1327 page_cache_release(swappage);
1328 goto repeat;
1329 }
1330 if (PageWriteback(swappage)) {
1331 shmem_swp_unmap(entry);
1332 spin_unlock(&info->lock);
1333 wait_on_page_writeback(swappage);
1334 unlock_page(swappage);
1335 page_cache_release(swappage);
1336 goto repeat;
1337 }
1338 if (!PageUptodate(swappage)) {
1339 shmem_swp_unmap(entry);
1340 spin_unlock(&info->lock);
1341 unlock_page(swappage);
1342 page_cache_release(swappage);
1343 error = -EIO;
1344 goto failed;
1345 }
1346
1347 if (filepage) {
1348 shmem_swp_set(info, entry, 0);
1349 shmem_swp_unmap(entry);
1350 delete_from_swap_cache(swappage);
1351 spin_unlock(&info->lock);
1352 copy_highpage(filepage, swappage);
1353 unlock_page(swappage);
1354 page_cache_release(swappage);
1355 flush_dcache_page(filepage);
1356 SetPageUptodate(filepage);
1357 set_page_dirty(filepage);
1358 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -07001359 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1360 idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 info->flags |= SHMEM_PAGEIN;
1362 shmem_swp_set(info, entry, 0);
1363 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001364 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365 spin_unlock(&info->lock);
1366 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001367 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001368 swap_free(swap);
1369 } else {
1370 shmem_swp_unmap(entry);
1371 spin_unlock(&info->lock);
Hugh Dickins82369552008-02-07 00:14:22 -08001372 if (error == -ENOMEM) {
Daisuke Nishimuraae3abae2009-04-30 15:08:19 -07001373 /*
1374 * reclaim from proper memory cgroup and
1375 * call memcg's OOM if needed.
1376 */
1377 error = mem_cgroup_shmem_charge_fallback(
1378 swappage,
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001379 current->mm,
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001380 gfp);
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001381 if (error) {
1382 unlock_page(swappage);
1383 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001384 goto failed;
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001385 }
Hugh Dickins82369552008-02-07 00:14:22 -08001386 }
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001387 unlock_page(swappage);
1388 page_cache_release(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 goto repeat;
1390 }
1391 } else if (sgp == SGP_READ && !filepage) {
1392 shmem_swp_unmap(entry);
1393 filepage = find_get_page(mapping, idx);
1394 if (filepage &&
Nick Piggin529ae9a2008-08-02 12:01:03 +02001395 (!PageUptodate(filepage) || !trylock_page(filepage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396 spin_unlock(&info->lock);
1397 wait_on_page_locked(filepage);
1398 page_cache_release(filepage);
1399 filepage = NULL;
1400 goto repeat;
1401 }
1402 spin_unlock(&info->lock);
1403 } else {
1404 shmem_swp_unmap(entry);
1405 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001406 if (sbinfo->max_blocks) {
Hugh Dickinsfc5da222011-04-14 15:22:07 -07001407 if (percpu_counter_compare(&sbinfo->used_blocks,
1408 sbinfo->max_blocks) >= 0 ||
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001409 shmem_acct_block(info->flags))
1410 goto nospace;
Tim Chen7e496292010-08-09 17:19:05 -07001411 percpu_counter_inc(&sbinfo->used_blocks);
1412 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001413 inode->i_blocks += BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -07001414 spin_unlock(&inode->i_lock);
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001415 } else if (shmem_acct_block(info->flags))
1416 goto nospace;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417
1418 if (!filepage) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001419 int ret;
1420
Shaohua Liff36b802010-08-09 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 Liff36b802010-08-09 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 Liff36b802010-08-09 17:19:06 -07001493 error = 0;
1494 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001496nospace:
1497 /*
1498 * Perhaps the page was brought in from swap between find_lock_page
1499 * and taking info->lock? We allow for that at add_to_page_cache_lru,
1500 * but must also avoid reporting a spurious ENOSPC while working on a
1501 * full tmpfs. (When filepage has been passed in to shmem_getpage, it
1502 * is already in page cache, which prevents this race from occurring.)
1503 */
1504 if (!filepage) {
1505 struct page *page = find_get_page(mapping, idx);
1506 if (page) {
1507 spin_unlock(&info->lock);
1508 page_cache_release(page);
1509 goto repeat;
1510 }
1511 }
1512 spin_unlock(&info->lock);
1513 error = -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001514failed:
1515 if (*pagep != filepage) {
1516 unlock_page(filepage);
1517 page_cache_release(filepage);
1518 }
Shaohua Liff36b802010-08-09 17:19:06 -07001519out:
1520 if (prealloc_page) {
1521 mem_cgroup_uncharge_cache_page(prealloc_page);
1522 page_cache_release(prealloc_page);
1523 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 return error;
1525}
1526
Nick Piggind0217ac2007-07-19 01:47:03 -07001527static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001529 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001530 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001531 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001532
Nick Piggind0217ac2007-07-19 01:47:03 -07001533 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1534 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001535
Hugh Dickins27d54b32008-02-04 22:28:43 -08001536 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001537 if (error)
1538 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539
Nick Piggin83c54072007-07-19 01:47:05 -07001540 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541}
1542
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001544static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001546 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1548}
1549
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001550static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1551 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001552{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001553 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001554 unsigned long idx;
1555
1556 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1557 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1558}
1559#endif
1560
1561int shmem_lock(struct file *file, int lock, struct user_struct *user)
1562{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001563 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 struct shmem_inode_info *info = SHMEM_I(inode);
1565 int retval = -ENOMEM;
1566
1567 spin_lock(&info->lock);
1568 if (lock && !(info->flags & VM_LOCKED)) {
1569 if (!user_shm_lock(inode->i_size, user))
1570 goto out_nomem;
1571 info->flags |= VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001572 mapping_set_unevictable(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573 }
1574 if (!lock && (info->flags & VM_LOCKED) && user) {
1575 user_shm_unlock(inode->i_size, user);
1576 info->flags &= ~VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001577 mapping_clear_unevictable(file->f_mapping);
1578 scan_mapping_unevictable_pages(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579 }
1580 retval = 0;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001581
Linus Torvalds1da177e2005-04-16 15:20:36 -07001582out_nomem:
1583 spin_unlock(&info->lock);
1584 return retval;
1585}
1586
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001587static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588{
1589 file_accessed(file);
1590 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001591 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 return 0;
1593}
1594
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001595static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1596 int mode, dev_t dev, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597{
1598 struct inode *inode;
1599 struct shmem_inode_info *info;
1600 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1601
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001602 if (shmem_reserve_inode(sb))
1603 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
1605 inode = new_inode(sb);
1606 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -04001607 inode->i_ino = get_next_ino();
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001608 inode_init_owner(inode, dir, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001610 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1611 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001612 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 info = SHMEM_I(inode);
1614 memset(info, 0, (char *)inode - (char *)info);
1615 spin_lock_init(&info->lock);
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001616 info->flags = flags & VM_NORESERVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 INIT_LIST_HEAD(&info->swaplist);
Al Viro72c04902009-06-24 16:58:48 -04001618 cache_no_acl(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001619
1620 switch (mode & S_IFMT) {
1621 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001622 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 init_special_inode(inode, mode, dev);
1624 break;
1625 case S_IFREG:
Hugh Dickins14fcc232008-07-28 15:46:19 -07001626 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 inode->i_op = &shmem_inode_operations;
1628 inode->i_fop = &shmem_file_operations;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001629 mpol_shared_policy_init(&info->policy,
1630 shmem_get_sbmpol(sbinfo));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 break;
1632 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001633 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634 /* Some things misbehave if size == 0 on a directory */
1635 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1636 inode->i_op = &shmem_dir_inode_operations;
1637 inode->i_fop = &simple_dir_operations;
1638 break;
1639 case S_IFLNK:
1640 /*
1641 * Must not load anything in the rbtree,
1642 * mpol_free_shared_policy will not be called.
1643 */
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001644 mpol_shared_policy_init(&info->policy, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 break;
1646 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001647 } else
1648 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649 return inode;
1650}
1651
1652#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001653static const struct inode_operations shmem_symlink_inode_operations;
1654static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655
1656/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001657 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae976412007-06-04 10:00:39 +02001658 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1659 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001661static int shmem_readpage(struct file *file, struct page *page)
1662{
1663 struct inode *inode = page->mapping->host;
1664 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1665 unlock_page(page);
1666 return error;
1667}
1668
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001670shmem_write_begin(struct file *file, struct address_space *mapping,
1671 loff_t pos, unsigned len, unsigned flags,
1672 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673{
Nick Piggin800d15a2007-10-16 01:25:03 -07001674 struct inode *inode = mapping->host;
1675 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1676 *pagep = NULL;
1677 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1678}
1679
1680static int
1681shmem_write_end(struct file *file, struct address_space *mapping,
1682 loff_t pos, unsigned len, unsigned copied,
1683 struct page *page, void *fsdata)
1684{
1685 struct inode *inode = mapping->host;
1686
Hugh Dickinsd3602442008-02-04 22:28:44 -08001687 if (pos + copied > inode->i_size)
1688 i_size_write(inode, pos + copied);
1689
Nick Piggin800d15a2007-10-16 01:25:03 -07001690 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02001691 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001692 page_cache_release(page);
1693
Nick Piggin800d15a2007-10-16 01:25:03 -07001694 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001695}
1696
Linus Torvalds1da177e2005-04-16 15:20:36 -07001697static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1698{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001699 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001700 struct address_space *mapping = inode->i_mapping;
1701 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001702 enum sgp_type sgp = SGP_READ;
1703
1704 /*
1705 * Might this read be for a stacking filesystem? Then when reading
1706 * holes of a sparse file, we actually need to allocate those pages,
1707 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1708 */
1709 if (segment_eq(get_fs(), KERNEL_DS))
1710 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001711
1712 index = *ppos >> PAGE_CACHE_SHIFT;
1713 offset = *ppos & ~PAGE_CACHE_MASK;
1714
1715 for (;;) {
1716 struct page *page = NULL;
1717 unsigned long end_index, nr, ret;
1718 loff_t i_size = i_size_read(inode);
1719
1720 end_index = i_size >> PAGE_CACHE_SHIFT;
1721 if (index > end_index)
1722 break;
1723 if (index == end_index) {
1724 nr = i_size & ~PAGE_CACHE_MASK;
1725 if (nr <= offset)
1726 break;
1727 }
1728
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001729 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730 if (desc->error) {
1731 if (desc->error == -EINVAL)
1732 desc->error = 0;
1733 break;
1734 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001735 if (page)
1736 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737
1738 /*
1739 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001740 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741 */
1742 nr = PAGE_CACHE_SIZE;
1743 i_size = i_size_read(inode);
1744 end_index = i_size >> PAGE_CACHE_SHIFT;
1745 if (index == end_index) {
1746 nr = i_size & ~PAGE_CACHE_MASK;
1747 if (nr <= offset) {
1748 if (page)
1749 page_cache_release(page);
1750 break;
1751 }
1752 }
1753 nr -= offset;
1754
1755 if (page) {
1756 /*
1757 * If users can be writing to this page using arbitrary
1758 * virtual addresses, take care about potential aliasing
1759 * before reading the page on the kernel side.
1760 */
1761 if (mapping_writably_mapped(mapping))
1762 flush_dcache_page(page);
1763 /*
1764 * Mark the page accessed if we read the beginning.
1765 */
1766 if (!offset)
1767 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001768 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001769 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001770 page_cache_get(page);
1771 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001772
1773 /*
1774 * Ok, we have the page, and it's up-to-date, so
1775 * now we can copy it to user space...
1776 *
1777 * The actor routine returns how many bytes were actually used..
1778 * NOTE! This may not be the same as how much of a user buffer
1779 * we filled up (we may be padding etc), so we can only update
1780 * "pos" here (the actor routine has to update the user buffer
1781 * pointers and the remaining count).
1782 */
1783 ret = actor(desc, page, offset, nr);
1784 offset += ret;
1785 index += offset >> PAGE_CACHE_SHIFT;
1786 offset &= ~PAGE_CACHE_MASK;
1787
1788 page_cache_release(page);
1789 if (ret != nr || !desc->count)
1790 break;
1791
1792 cond_resched();
1793 }
1794
1795 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1796 file_accessed(filp);
1797}
1798
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001799static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1800 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001801{
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001802 struct file *filp = iocb->ki_filp;
1803 ssize_t retval;
1804 unsigned long seg;
1805 size_t count;
1806 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001808 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1809 if (retval)
1810 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001812 for (seg = 0; seg < nr_segs; seg++) {
1813 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001815 desc.written = 0;
1816 desc.arg.buf = iov[seg].iov_base;
1817 desc.count = iov[seg].iov_len;
1818 if (desc.count == 0)
1819 continue;
1820 desc.error = 0;
1821 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1822 retval += desc.written;
1823 if (desc.error) {
1824 retval = retval ?: desc.error;
1825 break;
1826 }
1827 if (desc.count > 0)
1828 break;
1829 }
1830 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001831}
1832
David Howells726c3342006-06-23 02:02:58 -07001833static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001834{
David Howells726c3342006-06-23 02:02:58 -07001835 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836
1837 buf->f_type = TMPFS_MAGIC;
1838 buf->f_bsize = PAGE_CACHE_SIZE;
1839 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001840 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 buf->f_blocks = sbinfo->max_blocks;
Tim Chen7e496292010-08-09 17:19:05 -07001842 buf->f_bavail = buf->f_bfree =
1843 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001844 }
1845 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846 buf->f_files = sbinfo->max_inodes;
1847 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 }
1849 /* else leave those fields 0 like simple_statfs */
1850 return 0;
1851}
1852
1853/*
1854 * File creation. Allocate an inode, and we're done..
1855 */
1856static int
1857shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1858{
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001859 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001860 int error = -ENOSPC;
1861
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001862 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 if (inode) {
Eric Paris2a7dba32011-02-01 11:05:39 -05001864 error = security_inode_init_security(inode, dir,
1865 &dentry->d_name, NULL,
1866 NULL, NULL);
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001867 if (error) {
1868 if (error != -EOPNOTSUPP) {
1869 iput(inode);
1870 return error;
1871 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001872 }
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001873#ifdef CONFIG_TMPFS_POSIX_ACL
1874 error = generic_acl_init(inode, dir);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001875 if (error) {
1876 iput(inode);
1877 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001878 }
Al Viro718deb62009-12-16 19:35:36 -05001879#else
1880 error = 0;
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001881#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001882 dir->i_size += BOGO_DIRENT_SIZE;
1883 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1884 d_instantiate(dentry, inode);
1885 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001886 }
1887 return error;
1888}
1889
1890static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1891{
1892 int error;
1893
1894 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1895 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001896 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001897 return 0;
1898}
1899
1900static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1901 struct nameidata *nd)
1902{
1903 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1904}
1905
1906/*
1907 * Link a file..
1908 */
1909static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1910{
1911 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001912 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001913
1914 /*
1915 * No ordinary (disk based) filesystem counts links as inodes;
1916 * but each new link needs a new dentry, pinning lowmem, and
1917 * tmpfs dentries cannot be pruned until they are unlinked.
1918 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001919 ret = shmem_reserve_inode(inode->i_sb);
1920 if (ret)
1921 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922
1923 dir->i_size += BOGO_DIRENT_SIZE;
1924 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001925 inc_nlink(inode);
Al Viro7de9c6e2010-10-23 11:11:40 -04001926 ihold(inode); /* New dentry reference */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001927 dget(dentry); /* Extra pinning count for the created dentry */
1928 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001929out:
1930 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931}
1932
1933static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1934{
1935 struct inode *inode = dentry->d_inode;
1936
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001937 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1938 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001939
1940 dir->i_size -= BOGO_DIRENT_SIZE;
1941 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001942 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 dput(dentry); /* Undo the count from "create" - this does all the work */
1944 return 0;
1945}
1946
1947static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1948{
1949 if (!simple_empty(dentry))
1950 return -ENOTEMPTY;
1951
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001952 drop_nlink(dentry->d_inode);
1953 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954 return shmem_unlink(dir, dentry);
1955}
1956
1957/*
1958 * The VFS layer already does all the dentry stuff for rename,
1959 * we just have to decrement the usage count for the target if
1960 * it exists so that the VFS layer correctly free's it when it
1961 * gets overwritten.
1962 */
1963static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1964{
1965 struct inode *inode = old_dentry->d_inode;
1966 int they_are_dirs = S_ISDIR(inode->i_mode);
1967
1968 if (!simple_empty(new_dentry))
1969 return -ENOTEMPTY;
1970
1971 if (new_dentry->d_inode) {
1972 (void) shmem_unlink(new_dir, new_dentry);
1973 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001974 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001975 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001976 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001977 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 }
1979
1980 old_dir->i_size -= BOGO_DIRENT_SIZE;
1981 new_dir->i_size += BOGO_DIRENT_SIZE;
1982 old_dir->i_ctime = old_dir->i_mtime =
1983 new_dir->i_ctime = new_dir->i_mtime =
1984 inode->i_ctime = CURRENT_TIME;
1985 return 0;
1986}
1987
1988static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1989{
1990 int error;
1991 int len;
1992 struct inode *inode;
1993 struct page *page = NULL;
1994 char *kaddr;
1995 struct shmem_inode_info *info;
1996
1997 len = strlen(symname) + 1;
1998 if (len > PAGE_CACHE_SIZE)
1999 return -ENAMETOOLONG;
2000
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002001 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002002 if (!inode)
2003 return -ENOSPC;
2004
Eric Paris2a7dba32011-02-01 11:05:39 -05002005 error = security_inode_init_security(inode, dir, &dentry->d_name, NULL,
2006 NULL, NULL);
Stephen Smalley570bc1c2005-09-09 13:01:43 -07002007 if (error) {
2008 if (error != -EOPNOTSUPP) {
2009 iput(inode);
2010 return error;
2011 }
2012 error = 0;
2013 }
2014
Linus Torvalds1da177e2005-04-16 15:20:36 -07002015 info = SHMEM_I(inode);
2016 inode->i_size = len-1;
2017 if (len <= (char *)inode - (char *)info) {
2018 /* do it inline */
2019 memcpy(info, symname, len);
2020 inode->i_op = &shmem_symlink_inline_operations;
2021 } else {
2022 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2023 if (error) {
2024 iput(inode);
2025 return error;
2026 }
Hugh Dickins14fcc232008-07-28 15:46:19 -07002027 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002028 inode->i_op = &shmem_symlink_inode_operations;
2029 kaddr = kmap_atomic(page, KM_USER0);
2030 memcpy(kaddr, symname, len);
2031 kunmap_atomic(kaddr, KM_USER0);
2032 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02002033 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002034 page_cache_release(page);
2035 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002036 dir->i_size += BOGO_DIRENT_SIZE;
2037 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2038 d_instantiate(dentry, inode);
2039 dget(dentry);
2040 return 0;
2041}
2042
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002043static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002044{
2045 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002046 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047}
2048
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002049static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050{
2051 struct page *page = NULL;
2052 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2053 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08002054 if (page)
2055 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002056 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002057}
2058
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002059static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002060{
2061 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002062 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063 kunmap(page);
2064 mark_page_accessed(page);
2065 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002066 }
2067}
2068
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002069static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002070 .readlink = generic_readlink,
2071 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072};
2073
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002074static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075 .readlink = generic_readlink,
2076 .follow_link = shmem_follow_link,
2077 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078};
2079
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002080#ifdef CONFIG_TMPFS_POSIX_ACL
Randy Dunlap46711812008-03-19 17:00:41 -07002081/*
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002082 * Superblocks without xattr inode operations will get security.* xattr
2083 * support from the VFS "for free". As soon as we have any other xattrs
2084 * like ACLs, we also need to implement the security.* handlers at
2085 * filesystem level, though.
2086 */
2087
Christoph Hellwig431547b2009-11-13 09:52:56 +00002088static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002089 size_t list_len, const char *name,
Christoph Hellwig431547b2009-11-13 09:52:56 +00002090 size_t name_len, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002091{
Christoph Hellwig431547b2009-11-13 09:52:56 +00002092 return security_inode_listsecurity(dentry->d_inode, list, list_len);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002093}
2094
Christoph Hellwig431547b2009-11-13 09:52:56 +00002095static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
2096 void *buffer, size_t size, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002097{
2098 if (strcmp(name, "") == 0)
2099 return -EINVAL;
Christoph Hellwig431547b2009-11-13 09:52:56 +00002100 return xattr_getsecurity(dentry->d_inode, name, buffer, size);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002101}
2102
Christoph Hellwig431547b2009-11-13 09:52:56 +00002103static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
2104 const void *value, size_t size, int flags, int handler_flags)
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002105{
2106 if (strcmp(name, "") == 0)
2107 return -EINVAL;
Christoph Hellwig431547b2009-11-13 09:52:56 +00002108 return security_inode_setsecurity(dentry->d_inode, name, value,
2109 size, flags);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002110}
2111
Stephen Hemmingerbb435452010-05-13 17:53:14 -07002112static const struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002113 .prefix = XATTR_SECURITY_PREFIX,
2114 .list = shmem_xattr_security_list,
2115 .get = shmem_xattr_security_get,
2116 .set = shmem_xattr_security_set,
2117};
2118
Stephen Hemmingerbb435452010-05-13 17:53:14 -07002119static const struct xattr_handler *shmem_xattr_handlers[] = {
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002120 &generic_acl_access_handler,
2121 &generic_acl_default_handler,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002122 &shmem_xattr_security_handler,
2123 NULL
2124};
2125#endif
2126
David M. Grimes91828a42006-10-17 00:09:45 -07002127static struct dentry *shmem_get_parent(struct dentry *child)
2128{
2129 return ERR_PTR(-ESTALE);
2130}
2131
2132static int shmem_match(struct inode *ino, void *vfh)
2133{
2134 __u32 *fh = vfh;
2135 __u64 inum = fh[2];
2136 inum = (inum << 32) | fh[1];
2137 return ino->i_ino == inum && fh[0] == ino->i_generation;
2138}
2139
Christoph Hellwig480b1162007-10-21 16:42:13 -07002140static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2141 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002142{
David M. Grimes91828a42006-10-17 00:09:45 -07002143 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002144 struct dentry *dentry = NULL;
2145 u64 inum = fid->raw[2];
2146 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002147
Christoph Hellwig480b1162007-10-21 16:42:13 -07002148 if (fh_len < 3)
2149 return NULL;
2150
2151 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2152 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002153 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002154 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002155 iput(inode);
2156 }
2157
Christoph Hellwig480b1162007-10-21 16:42:13 -07002158 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002159}
2160
2161static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2162 int connectable)
2163{
2164 struct inode *inode = dentry->d_inode;
2165
Aneesh Kumar K.V5fe0c232011-01-29 18:43:25 +05302166 if (*len < 3) {
2167 *len = 3;
David M. Grimes91828a42006-10-17 00:09:45 -07002168 return 255;
Aneesh Kumar K.V5fe0c232011-01-29 18:43:25 +05302169 }
David M. Grimes91828a42006-10-17 00:09:45 -07002170
Al Viro1d3382c2010-10-23 15:19:20 -04002171 if (inode_unhashed(inode)) {
David M. Grimes91828a42006-10-17 00:09:45 -07002172 /* Unfortunately insert_inode_hash is not idempotent,
2173 * so as we hash inodes here rather than at creation
2174 * time, we need a lock to ensure we only try
2175 * to do it once
2176 */
2177 static DEFINE_SPINLOCK(lock);
2178 spin_lock(&lock);
Al Viro1d3382c2010-10-23 15:19:20 -04002179 if (inode_unhashed(inode))
David M. Grimes91828a42006-10-17 00:09:45 -07002180 __insert_inode_hash(inode,
2181 inode->i_ino + inode->i_generation);
2182 spin_unlock(&lock);
2183 }
2184
2185 fh[0] = inode->i_generation;
2186 fh[1] = inode->i_ino;
2187 fh[2] = ((__u64)inode->i_ino) >> 32;
2188
2189 *len = 3;
2190 return 1;
2191}
2192
Christoph Hellwig39655162007-10-21 16:42:17 -07002193static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002194 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002195 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002196 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002197};
2198
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002199static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2200 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002201{
2202 char *this_char, *value, *rest;
2203
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002204 while (options != NULL) {
2205 this_char = options;
2206 for (;;) {
2207 /*
2208 * NUL-terminate this option: unfortunately,
2209 * mount options form a comma-separated list,
2210 * but mpol's nodelist may also contain commas.
2211 */
2212 options = strchr(options, ',');
2213 if (options == NULL)
2214 break;
2215 options++;
2216 if (!isdigit(*options)) {
2217 options[-1] = '\0';
2218 break;
2219 }
2220 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002221 if (!*this_char)
2222 continue;
2223 if ((value = strchr(this_char,'=')) != NULL) {
2224 *value++ = 0;
2225 } else {
2226 printk(KERN_ERR
2227 "tmpfs: No value for mount option '%s'\n",
2228 this_char);
2229 return 1;
2230 }
2231
2232 if (!strcmp(this_char,"size")) {
2233 unsigned long long size;
2234 size = memparse(value,&rest);
2235 if (*rest == '%') {
2236 size <<= PAGE_SHIFT;
2237 size *= totalram_pages;
2238 do_div(size, 100);
2239 rest++;
2240 }
2241 if (*rest)
2242 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002243 sbinfo->max_blocks =
2244 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002245 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002246 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002247 if (*rest)
2248 goto bad_val;
2249 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002250 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002251 if (*rest)
2252 goto bad_val;
2253 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002254 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002255 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002256 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002257 if (*rest)
2258 goto bad_val;
2259 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002260 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002261 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002262 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002263 if (*rest)
2264 goto bad_val;
2265 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002266 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002267 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002268 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269 if (*rest)
2270 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002271 } else if (!strcmp(this_char,"mpol")) {
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002272 if (mpol_parse_str(value, &sbinfo->mpol, 1))
Robin Holt7339ff82006-01-14 13:20:48 -08002273 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002274 } else {
2275 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2276 this_char);
2277 return 1;
2278 }
2279 }
2280 return 0;
2281
2282bad_val:
2283 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2284 value, this_char);
2285 return 1;
2286
2287}
2288
2289static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2290{
2291 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002292 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002293 unsigned long inodes;
2294 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002295
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002296 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002297 return error;
2298
2299 spin_lock(&sbinfo->stat_lock);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002300 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
Tim Chen7e496292010-08-09 17:19:05 -07002301 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002302 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002303 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002304 goto out;
2305 /*
2306 * Those tests also disallow limited->unlimited while any are in
2307 * use, so i_blocks will always be zero when max_blocks is zero;
2308 * but we must separately disallow unlimited->limited, because
2309 * in that case we have no record of how much is already in use.
2310 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002311 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002312 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002313 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002314 goto out;
2315
2316 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002317 sbinfo->max_blocks = config.max_blocks;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002318 sbinfo->max_inodes = config.max_inodes;
2319 sbinfo->free_inodes = config.max_inodes - inodes;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002320
2321 mpol_put(sbinfo->mpol);
2322 sbinfo->mpol = config.mpol; /* transfers initial ref */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002323out:
2324 spin_unlock(&sbinfo->stat_lock);
2325 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002326}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002327
2328static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2329{
2330 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2331
2332 if (sbinfo->max_blocks != shmem_default_max_blocks())
2333 seq_printf(seq, ",size=%luk",
2334 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2335 if (sbinfo->max_inodes != shmem_default_max_inodes())
2336 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2337 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2338 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2339 if (sbinfo->uid != 0)
2340 seq_printf(seq, ",uid=%u", sbinfo->uid);
2341 if (sbinfo->gid != 0)
2342 seq_printf(seq, ",gid=%u", sbinfo->gid);
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002343 shmem_show_mpol(seq, sbinfo->mpol);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002344 return 0;
2345}
2346#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347
2348static void shmem_put_super(struct super_block *sb)
2349{
Hugh Dickins602586a2010-08-17 15:23:56 -07002350 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2351
2352 percpu_counter_destroy(&sbinfo->used_blocks);
2353 kfree(sbinfo);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354 sb->s_fs_info = NULL;
2355}
2356
Kay Sievers2b2af542009-04-30 15:23:42 +02002357int shmem_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002358{
2359 struct inode *inode;
2360 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002361 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002362 int err = -ENOMEM;
2363
2364 /* Round up to L1_CACHE_BYTES to resist false sharing */
Pekka Enberg425fbf02009-09-21 17:03:50 -07002365 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002366 L1_CACHE_BYTES), GFP_KERNEL);
2367 if (!sbinfo)
2368 return -ENOMEM;
2369
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002370 sbinfo->mode = S_IRWXUGO | S_ISVTX;
David Howells76aac0e2008-11-14 10:39:12 +11002371 sbinfo->uid = current_fsuid();
2372 sbinfo->gid = current_fsgid();
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002373 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002374
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002375#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002376 /*
2377 * Per default we only allow half of the physical ram per
2378 * tmpfs instance, limiting inodes to one per page of lowmem;
2379 * but the internal instance is left unlimited.
2380 */
2381 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002382 sbinfo->max_blocks = shmem_default_max_blocks();
2383 sbinfo->max_inodes = shmem_default_max_inodes();
2384 if (shmem_parse_options(data, sbinfo, false)) {
2385 err = -EINVAL;
2386 goto failed;
2387 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388 }
David M. Grimes91828a42006-10-17 00:09:45 -07002389 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002390#else
2391 sb->s_flags |= MS_NOUSER;
2392#endif
2393
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002394 spin_lock_init(&sbinfo->stat_lock);
Hugh Dickins602586a2010-08-17 15:23:56 -07002395 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2396 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002397 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002398
Linus Torvalds1da177e2005-04-16 15:20:36 -07002399 sb->s_maxbytes = SHMEM_MAX_BYTES;
2400 sb->s_blocksize = PAGE_CACHE_SIZE;
2401 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2402 sb->s_magic = TMPFS_MAGIC;
2403 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002404 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002405#ifdef CONFIG_TMPFS_POSIX_ACL
2406 sb->s_xattr = shmem_xattr_handlers;
2407 sb->s_flags |= MS_POSIXACL;
2408#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002409
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002410 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411 if (!inode)
2412 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002413 inode->i_uid = sbinfo->uid;
2414 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002415 root = d_alloc_root(inode);
2416 if (!root)
2417 goto failed_iput;
2418 sb->s_root = root;
2419 return 0;
2420
2421failed_iput:
2422 iput(inode);
2423failed:
2424 shmem_put_super(sb);
2425 return err;
2426}
2427
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002428static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002429
2430static struct inode *shmem_alloc_inode(struct super_block *sb)
2431{
2432 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002433 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002434 if (!p)
2435 return NULL;
2436 return &p->vfs_inode;
2437}
2438
Nick Pigginfa0d7e32011-01-07 17:49:49 +11002439static void shmem_i_callback(struct rcu_head *head)
2440{
2441 struct inode *inode = container_of(head, struct inode, i_rcu);
2442 INIT_LIST_HEAD(&inode->i_dentry);
2443 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2444}
2445
Linus Torvalds1da177e2005-04-16 15:20:36 -07002446static void shmem_destroy_inode(struct inode *inode)
2447{
2448 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2449 /* only struct inode is valid if it's an inline symlink */
2450 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2451 }
Nick Pigginfa0d7e32011-01-07 17:49:49 +11002452 call_rcu(&inode->i_rcu, shmem_i_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002453}
2454
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07002455static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002456{
2457 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2458
Christoph Lametera35afb82007-05-16 22:10:57 -07002459 inode_init_once(&p->vfs_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460}
2461
2462static int init_inodecache(void)
2463{
2464 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2465 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002466 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002467 return 0;
2468}
2469
2470static void destroy_inodecache(void)
2471{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002472 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473}
2474
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002475static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002476 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002477 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002478#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002479 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002480 .write_begin = shmem_write_begin,
2481 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002482#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002483 .migratepage = migrate_page,
Andi Kleenaa261f52009-09-16 11:50:16 +02002484 .error_remove_page = generic_error_remove_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002485};
2486
Helge Deller15ad7cd2006-12-06 20:40:36 -08002487static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002488 .mmap = shmem_mmap,
2489#ifdef CONFIG_TMPFS
2490 .llseek = generic_file_llseek,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002491 .read = do_sync_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002492 .write = do_sync_write,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002493 .aio_read = shmem_file_aio_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002494 .aio_write = generic_file_aio_write,
Christoph Hellwig1b061d92010-05-26 17:53:41 +02002495 .fsync = noop_fsync,
Hugh Dickinsae976412007-06-04 10:00:39 +02002496 .splice_read = generic_file_splice_read,
2497 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002498#endif
2499};
2500
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002501static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002502 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002503 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002504#ifdef CONFIG_TMPFS_POSIX_ACL
2505 .setxattr = generic_setxattr,
2506 .getxattr = generic_getxattr,
2507 .listxattr = generic_listxattr,
2508 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002509 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002510#endif
2511
Linus Torvalds1da177e2005-04-16 15:20:36 -07002512};
2513
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002514static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002515#ifdef CONFIG_TMPFS
2516 .create = shmem_create,
2517 .lookup = simple_lookup,
2518 .link = shmem_link,
2519 .unlink = shmem_unlink,
2520 .symlink = shmem_symlink,
2521 .mkdir = shmem_mkdir,
2522 .rmdir = shmem_rmdir,
2523 .mknod = shmem_mknod,
2524 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002525#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002526#ifdef CONFIG_TMPFS_POSIX_ACL
2527 .setattr = shmem_notify_change,
2528 .setxattr = generic_setxattr,
2529 .getxattr = generic_getxattr,
2530 .listxattr = generic_listxattr,
2531 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002532 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002533#endif
2534};
2535
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002536static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002537#ifdef CONFIG_TMPFS_POSIX_ACL
2538 .setattr = shmem_notify_change,
2539 .setxattr = generic_setxattr,
2540 .getxattr = generic_getxattr,
2541 .listxattr = generic_listxattr,
2542 .removexattr = generic_removexattr,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002543 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002544#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002545};
2546
Hugh Dickins759b9772007-03-05 00:30:28 -08002547static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002548 .alloc_inode = shmem_alloc_inode,
2549 .destroy_inode = shmem_destroy_inode,
2550#ifdef CONFIG_TMPFS
2551 .statfs = shmem_statfs,
2552 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002553 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002554#endif
Al Viro1f895f72010-06-05 19:10:41 -04002555 .evict_inode = shmem_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556 .drop_inode = generic_delete_inode,
2557 .put_super = shmem_put_super,
2558};
2559
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04002560static const struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002561 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562#ifdef CONFIG_NUMA
2563 .set_policy = shmem_set_policy,
2564 .get_policy = shmem_get_policy,
2565#endif
2566};
2567
2568
Al Viro3c26ff62010-07-25 11:46:36 +04002569static struct dentry *shmem_mount(struct file_system_type *fs_type,
2570 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002571{
Al Viro3c26ff62010-07-25 11:46:36 +04002572 return mount_nodev(fs_type, flags, data, shmem_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002573}
2574
2575static struct file_system_type tmpfs_fs_type = {
2576 .owner = THIS_MODULE,
2577 .name = "tmpfs",
Al Viro3c26ff62010-07-25 11:46:36 +04002578 .mount = shmem_mount,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579 .kill_sb = kill_litter_super,
2580};
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581
Kay Sievers2b2af542009-04-30 15:23:42 +02002582int __init init_tmpfs(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002583{
2584 int error;
2585
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002586 error = bdi_init(&shmem_backing_dev_info);
2587 if (error)
2588 goto out4;
2589
Linus Torvalds1da177e2005-04-16 15:20:36 -07002590 error = init_inodecache();
2591 if (error)
2592 goto out3;
2593
2594 error = register_filesystem(&tmpfs_fs_type);
2595 if (error) {
2596 printk(KERN_ERR "Could not register tmpfs\n");
2597 goto out2;
2598 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002599
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002600 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002601 tmpfs_fs_type.name, NULL);
2602 if (IS_ERR(shm_mnt)) {
2603 error = PTR_ERR(shm_mnt);
2604 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2605 goto out1;
2606 }
2607 return 0;
2608
2609out1:
2610 unregister_filesystem(&tmpfs_fs_type);
2611out2:
2612 destroy_inodecache();
2613out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002614 bdi_destroy(&shmem_backing_dev_info);
2615out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002616 shm_mnt = ERR_PTR(error);
2617 return error;
2618}
Matt Mackall853ac432009-01-06 14:40:20 -08002619
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002620#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2621/**
2622 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2623 * @inode: the inode to be searched
2624 * @pgoff: the offset to be searched
2625 * @pagep: the pointer for the found page to be stored
2626 * @ent: the pointer for the found swap entry to be stored
2627 *
2628 * If a page is found, refcount of it is incremented. Callers should handle
2629 * these refcount.
2630 */
2631void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2632 struct page **pagep, swp_entry_t *ent)
2633{
2634 swp_entry_t entry = { .val = 0 }, *ptr;
2635 struct page *page = NULL;
2636 struct shmem_inode_info *info = SHMEM_I(inode);
2637
2638 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2639 goto out;
2640
2641 spin_lock(&info->lock);
2642 ptr = shmem_swp_entry(info, pgoff, NULL);
2643#ifdef CONFIG_SWAP
2644 if (ptr && ptr->val) {
2645 entry.val = ptr->val;
2646 page = find_get_page(&swapper_space, entry.val);
2647 } else
2648#endif
2649 page = find_get_page(inode->i_mapping, pgoff);
2650 if (ptr)
2651 shmem_swp_unmap(ptr);
2652 spin_unlock(&info->lock);
2653out:
2654 *pagep = page;
2655 *ent = entry;
2656}
2657#endif
2658
Matt Mackall853ac432009-01-06 14:40:20 -08002659#else /* !CONFIG_SHMEM */
2660
2661/*
2662 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2663 *
2664 * This is intended for small system where the benefits of the full
2665 * shmem code (swap-backed and resource-limited) are outweighed by
2666 * their complexity. On systems without swap this code should be
2667 * effectively equivalent, but much lighter weight.
2668 */
2669
2670#include <linux/ramfs.h>
2671
2672static struct file_system_type tmpfs_fs_type = {
2673 .name = "tmpfs",
Al Viro3c26ff62010-07-25 11:46:36 +04002674 .mount = ramfs_mount,
Matt Mackall853ac432009-01-06 14:40:20 -08002675 .kill_sb = kill_litter_super,
2676};
2677
Kay Sievers2b2af542009-04-30 15:23:42 +02002678int __init init_tmpfs(void)
Matt Mackall853ac432009-01-06 14:40:20 -08002679{
2680 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2681
2682 shm_mnt = kern_mount(&tmpfs_fs_type);
2683 BUG_ON(IS_ERR(shm_mnt));
2684
2685 return 0;
2686}
2687
2688int shmem_unuse(swp_entry_t entry, struct page *page)
2689{
2690 return 0;
2691}
2692
Hugh Dickins3f96b792009-09-21 17:03:37 -07002693int shmem_lock(struct file *file, int lock, struct user_struct *user)
2694{
2695 return 0;
2696}
2697
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002698#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2699/**
2700 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2701 * @inode: the inode to be searched
2702 * @pgoff: the offset to be searched
2703 * @pagep: the pointer for the found page to be stored
2704 * @ent: the pointer for the found swap entry to be stored
2705 *
2706 * If a page is found, refcount of it is incremented. Callers should handle
2707 * these refcount.
2708 */
2709void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2710 struct page **pagep, swp_entry_t *ent)
2711{
2712 struct page *page = NULL;
2713
2714 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2715 goto out;
2716 page = find_get_page(inode->i_mapping, pgoff);
2717out:
2718 *pagep = page;
2719 *ent = (swp_entry_t){ .val = 0 };
2720}
2721#endif
2722
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002723#define shmem_vm_ops generic_file_vm_ops
2724#define shmem_file_operations ramfs_file_operations
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002725#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002726#define shmem_acct_size(flags, size) 0
2727#define shmem_unacct_size(flags, size) do {} while (0)
Hugh Dickinscaefba12009-04-13 14:40:12 -07002728#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
Matt Mackall853ac432009-01-06 14:40:20 -08002729
2730#endif /* CONFIG_SHMEM */
2731
2732/* common code */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002733
Randy Dunlap46711812008-03-19 17:00:41 -07002734/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002735 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002736 * @name: name for dentry (to be seen in /proc/<pid>/maps
2737 * @size: size to be set for the file
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002738 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
Linus Torvalds1da177e2005-04-16 15:20:36 -07002739 */
Sergei Trofimovich168f5ac2009-06-16 15:33:02 -07002740struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002741{
2742 int error;
2743 struct file *file;
2744 struct inode *inode;
Al Viro2c48b9c2009-08-09 00:52:35 +04002745 struct path path;
2746 struct dentry *root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002747 struct qstr this;
2748
2749 if (IS_ERR(shm_mnt))
2750 return (void *)shm_mnt;
2751
2752 if (size < 0 || size > SHMEM_MAX_BYTES)
2753 return ERR_PTR(-EINVAL);
2754
2755 if (shmem_acct_size(flags, size))
2756 return ERR_PTR(-ENOMEM);
2757
2758 error = -ENOMEM;
2759 this.name = name;
2760 this.len = strlen(name);
2761 this.hash = 0; /* will go */
2762 root = shm_mnt->mnt_root;
Al Viro2c48b9c2009-08-09 00:52:35 +04002763 path.dentry = d_alloc(root, &this);
2764 if (!path.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002765 goto put_memory;
Al Viro2c48b9c2009-08-09 00:52:35 +04002766 path.mnt = mntget(shm_mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767
Linus Torvalds1da177e2005-04-16 15:20:36 -07002768 error = -ENOSPC;
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002769 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770 if (!inode)
Al Viro4b42af82009-08-05 18:25:56 +04002771 goto put_dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002772
Al Viro2c48b9c2009-08-09 00:52:35 +04002773 d_instantiate(path.dentry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002774 inode->i_size = size;
2775 inode->i_nlink = 0; /* It is unlinked */
Matt Mackall853ac432009-01-06 14:40:20 -08002776#ifndef CONFIG_MMU
2777 error = ramfs_nommu_expand_for_mapping(inode, size);
2778 if (error)
Al Viro4b42af82009-08-05 18:25:56 +04002779 goto put_dentry;
Matt Mackall853ac432009-01-06 14:40:20 -08002780#endif
Al Viro4b42af82009-08-05 18:25:56 +04002781
2782 error = -ENFILE;
Al Viro2c48b9c2009-08-09 00:52:35 +04002783 file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
Al Viro4b42af82009-08-05 18:25:56 +04002784 &shmem_file_operations);
2785 if (!file)
2786 goto put_dentry;
2787
Linus Torvalds1da177e2005-04-16 15:20:36 -07002788 return file;
2789
Linus Torvalds1da177e2005-04-16 15:20:36 -07002790put_dentry:
Al Viro2c48b9c2009-08-09 00:52:35 +04002791 path_put(&path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792put_memory:
2793 shmem_unacct_size(flags, size);
2794 return ERR_PTR(error);
2795}
Keith Packard395e0dd2008-06-20 00:08:06 -07002796EXPORT_SYMBOL_GPL(shmem_file_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002797
Randy Dunlap46711812008-03-19 17:00:41 -07002798/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002799 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07002800 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2801 */
2802int shmem_zero_setup(struct vm_area_struct *vma)
2803{
2804 struct file *file;
2805 loff_t size = vma->vm_end - vma->vm_start;
2806
2807 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2808 if (IS_ERR(file))
2809 return PTR_ERR(file);
2810
2811 if (vma->vm_file)
2812 fput(vma->vm_file);
2813 vma->vm_file = file;
2814 vma->vm_ops = &shmem_vm_ops;
Hugh Dickinsbee4c362011-03-22 16:33:43 -07002815 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002816 return 0;
2817}