blob: 5941f980136367c8e0bc28c39b80f2acadee54c2 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
Hugh Dickins0edd73b2005-06-21 17:15:04 -07009 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * Copyright (C) 2004 Andi Kleen, SuSE Labs
12 *
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16 *
Matt Mackall853ac432009-01-06 14:40:20 -080017 * tiny-shmem:
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
19 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 * This file is released under the GPL.
21 */
22
Matt Mackall853ac432009-01-06 14:40:20 -080023#include <linux/fs.h>
24#include <linux/init.h>
25#include <linux/vfs.h>
26#include <linux/mount.h>
27#include <linux/file.h>
28#include <linux/mm.h>
29#include <linux/module.h>
30#include <linux/swap.h>
31
32static struct vfsmount *shm_mnt;
33
34#ifdef CONFIG_SHMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -070035/*
36 * This virtual memory filesystem is heavily based on the ramfs. It
37 * extends ramfs by the ability to use swap and honor resource limits
38 * which makes it a completely usable filesystem.
39 */
40
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070041#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070042#include <linux/exportfs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070043#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <linux/mman.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <linux/pagemap.h>
46#include <linux/string.h>
47#include <linux/slab.h>
48#include <linux/backing-dev.h>
49#include <linux/shmem_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070050#include <linux/writeback.h>
51#include <linux/vfs.h>
52#include <linux/blkdev.h>
53#include <linux/security.h>
54#include <linux/swapops.h>
55#include <linux/mempolicy.h>
56#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000057#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070058#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070059#include <linux/highmem.h>
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080060#include <linux/seq_file.h>
Mimi Zohar92562922008-10-07 14:00:12 -040061#include <linux/magic.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070062
Linus Torvalds1da177e2005-04-16 15:20:36 -070063#include <asm/uaccess.h>
64#include <asm/div64.h>
65#include <asm/pgtable.h>
66
Linus Torvalds1da177e2005-04-16 15:20:36 -070067#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
68#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
69#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
70
71#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
72#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
73
74#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
75
76/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
77#define SHMEM_PAGEIN VM_READ
78#define SHMEM_TRUNCATE VM_WRITE
79
80/* Definition to limit shmem_truncate's steps between cond_rescheds */
81#define LATENCY_LIMIT 64
82
83/* Pretend that each entry is of this size in directory's i_size */
84#define BOGO_DIRENT_SIZE 20
85
Linus Torvalds1da177e2005-04-16 15:20:36 -070086/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
87enum sgp_type {
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 SGP_READ, /* don't exceed i_size, don't allocate page */
89 SGP_CACHE, /* don't exceed i_size, may allocate page */
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -080090 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 SGP_WRITE, /* may exceed i_size, may allocate page */
92};
93
Andrew Mortonb76db732008-02-08 04:21:49 -080094#ifdef CONFIG_TMPFS
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080095static unsigned long shmem_default_max_blocks(void)
96{
97 return totalram_pages / 2;
98}
99
100static unsigned long shmem_default_max_inodes(void)
101{
102 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
103}
Andrew Mortonb76db732008-02-08 04:21:49 -0800104#endif
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800105
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106static int shmem_getpage(struct inode *inode, unsigned long idx,
107 struct page **pagep, enum sgp_type sgp, int *type);
108
Al Viro6daa0e22005-10-21 03:18:50 -0400109static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110{
111 /*
112 * The above definition of ENTRIES_PER_PAGE, and the use of
113 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
114 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -0700115 *
Mel Gormane12ba742007-10-16 01:25:52 -0700116 * Mobility flags are masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 */
Mel Gormane12ba742007-10-16 01:25:52 -0700118 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
Mel Gorman769848c2007-07-17 04:03:05 -0700119 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120}
121
122static inline void shmem_dir_free(struct page *page)
123{
124 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
125}
126
127static struct page **shmem_dir_map(struct page *page)
128{
129 return (struct page **)kmap_atomic(page, KM_USER0);
130}
131
132static inline void shmem_dir_unmap(struct page **dir)
133{
134 kunmap_atomic(dir, KM_USER0);
135}
136
137static swp_entry_t *shmem_swp_map(struct page *page)
138{
139 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
140}
141
142static inline void shmem_swp_balance_unmap(void)
143{
144 /*
145 * When passing a pointer to an i_direct entry, to code which
146 * also handles indirect entries and so will shmem_swp_unmap,
147 * we must arrange for the preempt count to remain in balance.
148 * What kmap_atomic of a lowmem page does depends on config
149 * and architecture, so pretend to kmap_atomic some lowmem page.
150 */
151 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
152}
153
154static inline void shmem_swp_unmap(swp_entry_t *entry)
155{
156 kunmap_atomic(entry, KM_USER1);
157}
158
159static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
160{
161 return sb->s_fs_info;
162}
163
164/*
165 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
166 * for shared memory and for shared anonymous (/dev/zero) mappings
167 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
168 * consistent with the pre-accounting of private mappings ...
169 */
170static inline int shmem_acct_size(unsigned long flags, loff_t size)
171{
Alan Cox731572d2008-10-29 14:01:20 -0700172 return (flags & VM_ACCOUNT) ?
173 security_vm_enough_memory_kern(VM_ACCT(size)) : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174}
175
176static inline void shmem_unacct_size(unsigned long flags, loff_t size)
177{
178 if (flags & VM_ACCOUNT)
179 vm_unacct_memory(VM_ACCT(size));
180}
181
182/*
183 * ... whereas tmpfs objects are accounted incrementally as
184 * pages are allocated, in order to allow huge sparse files.
185 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
186 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
187 */
188static inline int shmem_acct_block(unsigned long flags)
189{
Alan Cox731572d2008-10-29 14:01:20 -0700190 return (flags & VM_ACCOUNT) ?
191 0 : security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192}
193
194static inline void shmem_unacct_blocks(unsigned long flags, long pages)
195{
196 if (!(flags & VM_ACCOUNT))
197 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
198}
199
Hugh Dickins759b9772007-03-05 00:30:28 -0800200static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700201static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800202static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800203static const struct inode_operations shmem_inode_operations;
204static const struct inode_operations shmem_dir_inode_operations;
205static const struct inode_operations shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206static struct vm_operations_struct shmem_vm_ops;
207
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700208static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 .ra_pages = 0, /* No readahead */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700210 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 .unplug_io_fn = default_unplug_io_fn,
212};
213
214static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800215static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
217static void shmem_free_blocks(struct inode *inode, long pages)
218{
219 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700220 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 spin_lock(&sbinfo->stat_lock);
222 sbinfo->free_blocks += pages;
223 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
224 spin_unlock(&sbinfo->stat_lock);
225 }
226}
227
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800228static int shmem_reserve_inode(struct super_block *sb)
229{
230 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
231 if (sbinfo->max_inodes) {
232 spin_lock(&sbinfo->stat_lock);
233 if (!sbinfo->free_inodes) {
234 spin_unlock(&sbinfo->stat_lock);
235 return -ENOSPC;
236 }
237 sbinfo->free_inodes--;
238 spin_unlock(&sbinfo->stat_lock);
239 }
240 return 0;
241}
242
243static void shmem_free_inode(struct super_block *sb)
244{
245 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
246 if (sbinfo->max_inodes) {
247 spin_lock(&sbinfo->stat_lock);
248 sbinfo->free_inodes++;
249 spin_unlock(&sbinfo->stat_lock);
250 }
251}
252
Randy Dunlap46711812008-03-19 17:00:41 -0700253/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 * @inode: inode to recalc
256 *
257 * We have to calculate the free blocks since the mm can drop
258 * undirtied hole pages behind our back.
259 *
260 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
261 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
262 *
263 * It has to be called with the spinlock held.
264 */
265static void shmem_recalc_inode(struct inode *inode)
266{
267 struct shmem_inode_info *info = SHMEM_I(inode);
268 long freed;
269
270 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
271 if (freed > 0) {
272 info->alloced -= freed;
273 shmem_unacct_blocks(info->flags, freed);
274 shmem_free_blocks(inode, freed);
275 }
276}
277
Randy Dunlap46711812008-03-19 17:00:41 -0700278/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 * @info: info structure for the inode
281 * @index: index of the page to find
282 * @page: optional page to add to the structure. Has to be preset to
283 * all zeros
284 *
285 * If there is no space allocated yet it will return NULL when
286 * page is NULL, else it will use the page for the needed block,
287 * setting it to NULL on return to indicate that it has been used.
288 *
289 * The swap vector is organized the following way:
290 *
291 * There are SHMEM_NR_DIRECT entries directly stored in the
292 * shmem_inode_info structure. So small files do not need an addional
293 * allocation.
294 *
295 * For pages with index > SHMEM_NR_DIRECT there is the pointer
296 * i_indirect which points to a page which holds in the first half
297 * doubly indirect blocks, in the second half triple indirect blocks:
298 *
299 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
300 * following layout (for SHMEM_NR_DIRECT == 16):
301 *
302 * i_indirect -> dir --> 16-19
303 * | +-> 20-23
304 * |
305 * +-->dir2 --> 24-27
306 * | +-> 28-31
307 * | +-> 32-35
308 * | +-> 36-39
309 * |
310 * +-->dir3 --> 40-43
311 * +-> 44-47
312 * +-> 48-51
313 * +-> 52-55
314 */
315static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
316{
317 unsigned long offset;
318 struct page **dir;
319 struct page *subdir;
320
321 if (index < SHMEM_NR_DIRECT) {
322 shmem_swp_balance_unmap();
323 return info->i_direct+index;
324 }
325 if (!info->i_indirect) {
326 if (page) {
327 info->i_indirect = *page;
328 *page = NULL;
329 }
330 return NULL; /* need another page */
331 }
332
333 index -= SHMEM_NR_DIRECT;
334 offset = index % ENTRIES_PER_PAGE;
335 index /= ENTRIES_PER_PAGE;
336 dir = shmem_dir_map(info->i_indirect);
337
338 if (index >= ENTRIES_PER_PAGE/2) {
339 index -= ENTRIES_PER_PAGE/2;
340 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
341 index %= ENTRIES_PER_PAGE;
342 subdir = *dir;
343 if (!subdir) {
344 if (page) {
345 *dir = *page;
346 *page = NULL;
347 }
348 shmem_dir_unmap(dir);
349 return NULL; /* need another page */
350 }
351 shmem_dir_unmap(dir);
352 dir = shmem_dir_map(subdir);
353 }
354
355 dir += index;
356 subdir = *dir;
357 if (!subdir) {
358 if (!page || !(subdir = *page)) {
359 shmem_dir_unmap(dir);
360 return NULL; /* need a page */
361 }
362 *dir = subdir;
363 *page = NULL;
364 }
365 shmem_dir_unmap(dir);
366 return shmem_swp_map(subdir) + offset;
367}
368
369static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
370{
371 long incdec = value? 1: -1;
372
373 entry->val = value;
374 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700375 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
376 struct page *page = kmap_atomic_to_page(entry);
377 set_page_private(page, page_private(page) + incdec);
378 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379}
380
Randy Dunlap46711812008-03-19 17:00:41 -0700381/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700383 * @info: info structure for the inode
384 * @index: index of the page to find
385 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700386 *
387 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 */
389static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
390{
391 struct inode *inode = &info->vfs_inode;
392 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
393 struct page *page = NULL;
394 swp_entry_t *entry;
395
396 if (sgp != SGP_WRITE &&
397 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
398 return ERR_PTR(-EINVAL);
399
400 while (!(entry = shmem_swp_entry(info, index, &page))) {
401 if (sgp == SGP_READ)
402 return shmem_swp_map(ZERO_PAGE(0));
403 /*
404 * Test free_blocks against 1 not 0, since we have 1 data
405 * page (and perhaps indirect index pages) yet to allocate:
406 * a waste to allocate index if we cannot allocate data.
407 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700408 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409 spin_lock(&sbinfo->stat_lock);
410 if (sbinfo->free_blocks <= 1) {
411 spin_unlock(&sbinfo->stat_lock);
412 return ERR_PTR(-ENOSPC);
413 }
414 sbinfo->free_blocks--;
415 inode->i_blocks += BLOCKS_PER_PAGE;
416 spin_unlock(&sbinfo->stat_lock);
417 }
418
419 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700420 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700421 if (page)
422 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 spin_lock(&info->lock);
424
425 if (!page) {
426 shmem_free_blocks(inode, 1);
427 return ERR_PTR(-ENOMEM);
428 }
429 if (sgp != SGP_WRITE &&
430 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
431 entry = ERR_PTR(-EINVAL);
432 break;
433 }
434 if (info->next_index <= index)
435 info->next_index = index + 1;
436 }
437 if (page) {
438 /* another task gave its page, or truncated the file */
439 shmem_free_blocks(inode, 1);
440 shmem_dir_free(page);
441 }
442 if (info->next_index <= index && !IS_ERR(entry))
443 info->next_index = index + 1;
444 return entry;
445}
446
Randy Dunlap46711812008-03-19 17:00:41 -0700447/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 * shmem_free_swp - free some swap entries in a directory
Hugh Dickins1ae70002007-03-29 01:20:36 -0700449 * @dir: pointer to the directory
450 * @edir: pointer after last entry of the directory
451 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700453static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
454 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700456 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457 swp_entry_t *ptr;
458 int freed = 0;
459
460 for (ptr = dir; ptr < edir; ptr++) {
461 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700462 if (unlikely(punch_lock)) {
463 punch_unlock = punch_lock;
464 punch_lock = NULL;
465 spin_lock(punch_unlock);
466 if (!ptr->val)
467 continue;
468 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 free_swap_and_cache(*ptr);
470 *ptr = (swp_entry_t){0};
471 freed++;
472 }
473 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700474 if (punch_unlock)
475 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 return freed;
477}
478
Hugh Dickins1ae70002007-03-29 01:20:36 -0700479static int shmem_map_and_free_swp(struct page *subdir, int offset,
480 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481{
482 swp_entry_t *ptr;
483 int freed = 0;
484
485 ptr = shmem_swp_map(subdir);
486 for (; offset < limit; offset += LATENCY_LIMIT) {
487 int size = limit - offset;
488 if (size > LATENCY_LIMIT)
489 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700490 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
491 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700492 if (need_resched()) {
493 shmem_swp_unmap(ptr);
494 if (*dir) {
495 shmem_dir_unmap(*dir);
496 *dir = NULL;
497 }
498 cond_resched();
499 ptr = shmem_swp_map(subdir);
500 }
501 }
502 shmem_swp_unmap(ptr);
503 return freed;
504}
505
506static void shmem_free_pages(struct list_head *next)
507{
508 struct page *page;
509 int freed = 0;
510
511 do {
512 page = container_of(next, struct page, lru);
513 next = next->next;
514 shmem_dir_free(page);
515 freed++;
516 if (freed >= LATENCY_LIMIT) {
517 cond_resched();
518 freed = 0;
519 }
520 } while (next);
521}
522
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800523static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524{
525 struct shmem_inode_info *info = SHMEM_I(inode);
526 unsigned long idx;
527 unsigned long size;
528 unsigned long limit;
529 unsigned long stage;
530 unsigned long diroff;
531 struct page **dir;
532 struct page *topdir;
533 struct page *middir;
534 struct page *subdir;
535 swp_entry_t *ptr;
536 LIST_HEAD(pages_to_free);
537 long nr_pages_to_free = 0;
538 long nr_swaps_freed = 0;
539 int offset;
540 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700541 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700542 spinlock_t *needs_lock;
543 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700544 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545
546 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800547 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 if (idx >= info->next_index)
549 return;
550
551 spin_lock(&info->lock);
552 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800553 if (likely(end == (loff_t) -1)) {
554 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700555 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800556 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700557 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700558 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800559 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700560 if (end + 1 >= inode->i_size) { /* we may free a little more */
561 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
562 PAGE_CACHE_SHIFT;
563 upper_limit = SHMEM_MAX_INDEX;
564 } else {
565 limit = (end + 1) >> PAGE_CACHE_SHIFT;
566 upper_limit = limit;
567 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700568 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800569 punch_hole = 1;
570 }
571
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800573 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 info->i_indirect = NULL;
575 nr_pages_to_free++;
576 list_add(&topdir->lru, &pages_to_free);
577 }
578 spin_unlock(&info->lock);
579
580 if (info->swapped && idx < SHMEM_NR_DIRECT) {
581 ptr = info->i_direct;
582 size = limit;
583 if (size > SHMEM_NR_DIRECT)
584 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700585 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800587
588 /*
589 * If there are no indirect blocks or we are punching a hole
590 * below indirect blocks, nothing to be done.
591 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700592 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 goto done2;
594
Hugh Dickins1ae70002007-03-29 01:20:36 -0700595 /*
596 * The truncation case has already dropped info->lock, and we're safe
597 * because i_size and next_index have already been lowered, preventing
598 * access beyond. But in the punch_hole case, we still need to take
599 * the lock when updating the swap directory, because there might be
600 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
601 * shmem_writepage. However, whenever we find we can remove a whole
602 * directory page (not at the misaligned start or end of the range),
603 * we first NULLify its pointer in the level above, and then have no
604 * need to take the lock when updating its contents: needs_lock and
605 * punch_lock (either pointing to info->lock or NULL) manage this.
606 */
607
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700608 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 limit -= SHMEM_NR_DIRECT;
610 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
611 offset = idx % ENTRIES_PER_PAGE;
612 idx -= offset;
613
614 dir = shmem_dir_map(topdir);
615 stage = ENTRIES_PER_PAGEPAGE/2;
616 if (idx < ENTRIES_PER_PAGEPAGE/2) {
617 middir = topdir;
618 diroff = idx/ENTRIES_PER_PAGE;
619 } else {
620 dir += ENTRIES_PER_PAGE/2;
621 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
622 while (stage <= idx)
623 stage += ENTRIES_PER_PAGEPAGE;
624 middir = *dir;
625 if (*dir) {
626 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
627 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700628 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700629 if (needs_lock) {
630 spin_lock(needs_lock);
631 *dir = NULL;
632 spin_unlock(needs_lock);
633 needs_lock = NULL;
634 } else
635 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 nr_pages_to_free++;
637 list_add(&middir->lru, &pages_to_free);
638 }
639 shmem_dir_unmap(dir);
640 dir = shmem_dir_map(middir);
641 } else {
642 diroff = 0;
643 offset = 0;
644 idx = stage;
645 }
646 }
647
648 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
649 if (unlikely(idx == stage)) {
650 shmem_dir_unmap(dir);
651 dir = shmem_dir_map(topdir) +
652 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
653 while (!*dir) {
654 dir++;
655 idx += ENTRIES_PER_PAGEPAGE;
656 if (idx >= limit)
657 goto done1;
658 }
659 stage = idx + ENTRIES_PER_PAGEPAGE;
660 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700661 if (punch_hole)
662 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700663 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700664 if (needs_lock) {
665 spin_lock(needs_lock);
666 *dir = NULL;
667 spin_unlock(needs_lock);
668 needs_lock = NULL;
669 } else
670 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700671 nr_pages_to_free++;
672 list_add(&middir->lru, &pages_to_free);
673 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 shmem_dir_unmap(dir);
675 cond_resched();
676 dir = shmem_dir_map(middir);
677 diroff = 0;
678 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700679 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700681 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
682 if (needs_lock) {
683 spin_lock(needs_lock);
684 dir[diroff] = NULL;
685 spin_unlock(needs_lock);
686 punch_lock = NULL;
687 } else
688 dir[diroff] = NULL;
689 nr_pages_to_free++;
690 list_add(&subdir->lru, &pages_to_free);
691 }
692 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 size = limit - idx;
694 if (size > ENTRIES_PER_PAGE)
695 size = ENTRIES_PER_PAGE;
696 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700697 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 if (!dir)
699 dir = shmem_dir_map(middir);
700 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700701 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700703 set_page_private(subdir,
704 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700706 } else
707 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700709 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 }
711done1:
712 shmem_dir_unmap(dir);
713done2:
714 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
715 /*
716 * Call truncate_inode_pages again: racing shmem_unuse_inode
717 * may have swizzled a page in from swap since vmtruncate or
718 * generic_delete_inode did it, before we lowered next_index.
719 * Also, though shmem_getpage checks i_size before adding to
720 * cache, no recheck after: so fix the narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700721 *
722 * Recalling truncate_inode_pages_range and unmap_mapping_range
723 * every time for punch_hole (which never got a chance to clear
724 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
725 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800727 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700728 if (punch_hole)
729 unmap_mapping_range(inode->i_mapping, start,
730 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731 }
732
733 spin_lock(&info->lock);
734 info->flags &= ~SHMEM_TRUNCATE;
735 info->swapped -= nr_swaps_freed;
736 if (nr_pages_to_free)
737 shmem_free_blocks(inode, nr_pages_to_free);
738 shmem_recalc_inode(inode);
739 spin_unlock(&info->lock);
740
741 /*
742 * Empty swap vector directory pages to be freed?
743 */
744 if (!list_empty(&pages_to_free)) {
745 pages_to_free.prev->next = NULL;
746 shmem_free_pages(pages_to_free.next);
747 }
748}
749
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800750static void shmem_truncate(struct inode *inode)
751{
752 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
753}
754
Linus Torvalds1da177e2005-04-16 15:20:36 -0700755static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
756{
757 struct inode *inode = dentry->d_inode;
758 struct page *page = NULL;
759 int error;
760
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700761 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700762 if (attr->ia_size < inode->i_size) {
763 /*
764 * If truncating down to a partial page, then
765 * if that page is already allocated, hold it
766 * in memory until the truncation is over, so
767 * truncate_partial_page cannnot miss it were
768 * it assigned to swap.
769 */
770 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
771 (void) shmem_getpage(inode,
772 attr->ia_size>>PAGE_CACHE_SHIFT,
773 &page, SGP_READ, NULL);
Hugh Dickinsd3602442008-02-04 22:28:44 -0800774 if (page)
775 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700776 }
777 /*
778 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
779 * detect if any pages might have been added to cache
780 * after truncate_inode_pages. But we needn't bother
781 * if it's being fully truncated to zero-length: the
782 * nrpages check is efficient enough in that case.
783 */
784 if (attr->ia_size) {
785 struct shmem_inode_info *info = SHMEM_I(inode);
786 spin_lock(&info->lock);
787 info->flags &= ~SHMEM_PAGEIN;
788 spin_unlock(&info->lock);
789 }
790 }
791 }
792
793 error = inode_change_ok(inode, attr);
794 if (!error)
795 error = inode_setattr(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700796#ifdef CONFIG_TMPFS_POSIX_ACL
797 if (!error && (attr->ia_valid & ATTR_MODE))
798 error = generic_acl_chmod(inode, &shmem_acl_ops);
799#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 if (page)
801 page_cache_release(page);
802 return error;
803}
804
805static void shmem_delete_inode(struct inode *inode)
806{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 struct shmem_inode_info *info = SHMEM_I(inode);
808
809 if (inode->i_op->truncate == shmem_truncate) {
Mark Fashehfef26652005-09-09 13:01:31 -0700810 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811 shmem_unacct_size(info->flags, inode->i_size);
812 inode->i_size = 0;
813 shmem_truncate(inode);
814 if (!list_empty(&info->swaplist)) {
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800815 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700816 list_del_init(&info->swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800817 mutex_unlock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 }
819 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700820 BUG_ON(inode->i_blocks);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800821 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 clear_inode(inode);
823}
824
825static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
826{
827 swp_entry_t *ptr;
828
829 for (ptr = dir; ptr < edir; ptr++) {
830 if (ptr->val == entry.val)
831 return ptr - dir;
832 }
833 return -1;
834}
835
836static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
837{
838 struct inode *inode;
839 unsigned long idx;
840 unsigned long size;
841 unsigned long limit;
842 unsigned long stage;
843 struct page **dir;
844 struct page *subdir;
845 swp_entry_t *ptr;
846 int offset;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800847 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848
849 idx = 0;
850 ptr = info->i_direct;
851 spin_lock(&info->lock);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800852 if (!info->swapped) {
853 list_del_init(&info->swaplist);
854 goto lost2;
855 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700856 limit = info->next_index;
857 size = limit;
858 if (size > SHMEM_NR_DIRECT)
859 size = SHMEM_NR_DIRECT;
860 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800861 if (offset >= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 goto found;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 if (!info->i_indirect)
864 goto lost2;
865
866 dir = shmem_dir_map(info->i_indirect);
867 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
868
869 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
870 if (unlikely(idx == stage)) {
871 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800872 if (cond_resched_lock(&info->lock)) {
873 /* check it has not been truncated */
874 if (limit > info->next_index) {
875 limit = info->next_index;
876 if (idx >= limit)
877 goto lost2;
878 }
879 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700880 dir = shmem_dir_map(info->i_indirect) +
881 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
882 while (!*dir) {
883 dir++;
884 idx += ENTRIES_PER_PAGEPAGE;
885 if (idx >= limit)
886 goto lost1;
887 }
888 stage = idx + ENTRIES_PER_PAGEPAGE;
889 subdir = *dir;
890 shmem_dir_unmap(dir);
891 dir = shmem_dir_map(subdir);
892 }
893 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700894 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 ptr = shmem_swp_map(subdir);
896 size = limit - idx;
897 if (size > ENTRIES_PER_PAGE)
898 size = ENTRIES_PER_PAGE;
899 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800900 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700901 if (offset >= 0) {
902 shmem_dir_unmap(dir);
903 goto found;
904 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700905 }
906 }
907lost1:
908 shmem_dir_unmap(dir-1);
909lost2:
910 spin_unlock(&info->lock);
911 return 0;
912found:
913 idx += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800914 inode = igrab(&info->vfs_inode);
915 spin_unlock(&info->lock);
916
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800917 /*
918 * Move _head_ to start search for next from here.
919 * But be careful: shmem_delete_inode checks list_empty without taking
920 * mutex, and there's an instant in list_move_tail when info->swaplist
921 * would appear empty, if it were the only one on shmem_swaplist. We
922 * could avoid doing it if inode NULL; or use this minor optimization.
923 */
924 if (shmem_swaplist.next != &info->swaplist)
925 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800926 mutex_unlock(&shmem_swaplist_mutex);
927
928 error = 1;
929 if (!inode)
930 goto out;
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700931 /* Precharge page using GFP_KERNEL while we can wait */
Hugh Dickins82369552008-02-07 00:14:22 -0800932 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800933 if (error)
934 goto out;
Hugh Dickins82369552008-02-07 00:14:22 -0800935 error = radix_tree_preload(GFP_KERNEL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700936 if (error) {
937 mem_cgroup_uncharge_cache_page(page);
938 goto out;
939 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800940 error = 1;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800941
942 spin_lock(&info->lock);
943 ptr = shmem_swp_entry(info, idx, NULL);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700944 if (ptr && ptr->val == entry.val) {
Nick Piggine2867812008-07-25 19:45:30 -0700945 error = add_to_page_cache_locked(page, inode->i_mapping,
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800946 idx, GFP_NOWAIT);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700947 /* does mem_cgroup_uncharge_cache_page on error */
948 } else /* we must compensate for our precharge above */
949 mem_cgroup_uncharge_cache_page(page);
950
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800951 if (error == -EEXIST) {
952 struct page *filepage = find_get_page(inode->i_mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800953 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800954 if (filepage) {
955 /*
956 * There might be a more uptodate page coming down
957 * from a stacked writepage: forget our swappage if so.
958 */
959 if (PageUptodate(filepage))
960 error = 0;
961 page_cache_release(filepage);
962 }
963 }
964 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800965 delete_from_swap_cache(page);
966 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800968 shmem_swp_set(info, ptr, 0);
969 swap_free(entry);
970 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971 }
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800972 if (ptr)
973 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700974 spin_unlock(&info->lock);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -0800975 radix_tree_preload_end();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800976out:
977 unlock_page(page);
978 page_cache_release(page);
979 iput(inode); /* allows for NULL */
980 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981}
982
983/*
984 * shmem_unuse() search for an eventually swapped out shmem page.
985 */
986int shmem_unuse(swp_entry_t entry, struct page *page)
987{
988 struct list_head *p, *next;
989 struct shmem_inode_info *info;
990 int found = 0;
991
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800992 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 list_for_each_safe(p, next, &shmem_swaplist) {
994 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800995 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800996 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800997 if (found)
998 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001000 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001001out: return found; /* 0 or 1 or -ENOMEM */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001002}
1003
1004/*
1005 * Move the page from the page cache to the swap cache.
1006 */
1007static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1008{
1009 struct shmem_inode_info *info;
1010 swp_entry_t *entry, swap;
1011 struct address_space *mapping;
1012 unsigned long index;
1013 struct inode *inode;
1014
1015 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016 mapping = page->mapping;
1017 index = page->index;
1018 inode = mapping->host;
1019 info = SHMEM_I(inode);
1020 if (info->flags & VM_LOCKED)
1021 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001022 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001023 goto redirty;
1024
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001025 /*
1026 * shmem_backing_dev_info's capabilities prevent regular writeback or
1027 * sync from ever calling shmem_writepage; but a stacking filesystem
1028 * may use the ->writepage of its underlying filesystem, in which case
1029 * tmpfs should write out to swap only in response to memory pressure,
1030 * and not for pdflush or sync. However, in those cases, we do still
1031 * want to check if there's a redundant swappage to be discarded.
1032 */
1033 if (wbc->for_reclaim)
1034 swap = get_swap_page();
1035 else
1036 swap.val = 0;
1037
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 spin_lock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 if (index >= info->next_index) {
1040 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1041 goto unlock;
1042 }
1043 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001044 if (entry->val) {
1045 /*
1046 * The more uptodate page coming down from a stacked
1047 * writepage should replace our old swappage.
1048 */
1049 free_swap_and_cache(*entry);
1050 shmem_swp_set(info, entry, 0);
1051 }
1052 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001053
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001054 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Hugh Dickins73b12622008-02-04 22:28:50 -08001055 remove_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 shmem_swp_set(info, entry, swap.val);
1057 shmem_swp_unmap(entry);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001058 if (list_empty(&info->swaplist))
1059 inode = igrab(inode);
1060 else
1061 inode = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001062 spin_unlock(&info->lock);
Hugh Dickins73b12622008-02-04 22:28:50 -08001063 swap_duplicate(swap);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001064 BUG_ON(page_mapped(page));
Hugh Dickins73b12622008-02-04 22:28:50 -08001065 page_cache_release(page); /* pagecache ref */
1066 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 unlock_page(page);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001068 if (inode) {
1069 mutex_lock(&shmem_swaplist_mutex);
1070 /* move instead of add in case we're racing */
1071 list_move_tail(&info->swaplist, &shmem_swaplist);
1072 mutex_unlock(&shmem_swaplist_mutex);
1073 iput(inode);
1074 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075 return 0;
1076 }
1077
1078 shmem_swp_unmap(entry);
1079unlock:
1080 spin_unlock(&info->lock);
1081 swap_free(swap);
1082redirty:
1083 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001084 if (wbc->for_reclaim)
1085 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1086 unlock_page(page);
1087 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001088}
1089
1090#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001091#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001092static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001093{
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001094 char buffer[64];
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001095
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001096 if (!mpol || mpol->mode == MPOL_DEFAULT)
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001097 return; /* show nothing */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001098
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001099 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001100
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001101 seq_printf(seq, ",mpol=%s", buffer);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001102}
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001103
1104static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1105{
1106 struct mempolicy *mpol = NULL;
1107 if (sbinfo->mpol) {
1108 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1109 mpol = sbinfo->mpol;
1110 mpol_get(mpol);
1111 spin_unlock(&sbinfo->stat_lock);
1112 }
1113 return mpol;
1114}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001115#endif /* CONFIG_TMPFS */
1116
Hugh Dickins02098fe2008-02-04 22:28:42 -08001117static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1118 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001119{
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001120 struct mempolicy mpol, *spol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001122 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001124 spol = mpol_cond_copy(&mpol,
1125 mpol_shared_policy_lookup(&info->policy, idx));
1126
Linus Torvalds1da177e2005-04-16 15:20:36 -07001127 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001128 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001130 pvma.vm_ops = NULL;
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001131 pvma.vm_policy = spol;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001132 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001133 return page;
1134}
1135
Hugh Dickins02098fe2008-02-04 22:28:42 -08001136static struct page *shmem_alloc_page(gfp_t gfp,
1137 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138{
1139 struct vm_area_struct pvma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001140
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001141 /* Create a pseudo vma that just contains the policy */
1142 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001144 pvma.vm_ops = NULL;
1145 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001146
1147 /*
1148 * alloc_page_vma() will drop the shared policy reference
1149 */
1150 return alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001151}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001152#else /* !CONFIG_NUMA */
1153#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001154static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001155{
1156}
1157#endif /* CONFIG_TMPFS */
1158
Hugh Dickins02098fe2008-02-04 22:28:42 -08001159static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1160 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001162 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163}
1164
Hugh Dickins02098fe2008-02-04 22:28:42 -08001165static inline struct page *shmem_alloc_page(gfp_t gfp,
1166 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001167{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001168 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001170#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001172#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1173static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1174{
1175 return NULL;
1176}
1177#endif
1178
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179/*
1180 * shmem_getpage - either get the page from swap or allocate a new one
1181 *
1182 * If we allocate a new one we do not mark it dirty. That's up to the
1183 * vm. If we swap it in we mark it dirty since we also free the swap
1184 * entry since a page cannot live in both the swap and page cache
1185 */
1186static int shmem_getpage(struct inode *inode, unsigned long idx,
1187 struct page **pagep, enum sgp_type sgp, int *type)
1188{
1189 struct address_space *mapping = inode->i_mapping;
1190 struct shmem_inode_info *info = SHMEM_I(inode);
1191 struct shmem_sb_info *sbinfo;
1192 struct page *filepage = *pagep;
1193 struct page *swappage;
1194 swp_entry_t *entry;
1195 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001196 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197 int error;
1198
1199 if (idx >= SHMEM_MAX_INDEX)
1200 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001201
1202 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001203 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001204
Linus Torvalds1da177e2005-04-16 15:20:36 -07001205 /*
1206 * Normally, filepage is NULL on entry, and either found
1207 * uptodate immediately, or allocated and zeroed, or read
1208 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001209 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae976412007-06-04 10:00:39 +02001210 * filepage, which may be found not uptodate by other callers
1211 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001212 */
1213repeat:
1214 if (!filepage)
1215 filepage = find_lock_page(mapping, idx);
1216 if (filepage && PageUptodate(filepage))
1217 goto done;
1218 error = 0;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001219 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001220 if (!filepage) {
1221 /*
1222 * Try to preload while we can wait, to not make a habit of
1223 * draining atomic reserves; but don't latch on to this cpu.
1224 */
1225 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1226 if (error)
1227 goto failed;
1228 radix_tree_preload_end();
1229 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001230
1231 spin_lock(&info->lock);
1232 shmem_recalc_inode(inode);
1233 entry = shmem_swp_alloc(info, idx, sgp);
1234 if (IS_ERR(entry)) {
1235 spin_unlock(&info->lock);
1236 error = PTR_ERR(entry);
1237 goto failed;
1238 }
1239 swap = *entry;
1240
1241 if (swap.val) {
1242 /* Look it up and read it in.. */
1243 swappage = lookup_swap_cache(swap);
1244 if (!swappage) {
1245 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001246 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001247 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001248 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001249 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001250 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001251 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001252 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001253 if (!swappage) {
1254 spin_lock(&info->lock);
1255 entry = shmem_swp_alloc(info, idx, sgp);
1256 if (IS_ERR(entry))
1257 error = PTR_ERR(entry);
1258 else {
1259 if (entry->val == swap.val)
1260 error = -ENOMEM;
1261 shmem_swp_unmap(entry);
1262 }
1263 spin_unlock(&info->lock);
1264 if (error)
1265 goto failed;
1266 goto repeat;
1267 }
1268 wait_on_page_locked(swappage);
1269 page_cache_release(swappage);
1270 goto repeat;
1271 }
1272
1273 /* We have to do this with page locked to prevent races */
Nick Piggin529ae9a2008-08-02 12:01:03 +02001274 if (!trylock_page(swappage)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001275 shmem_swp_unmap(entry);
1276 spin_unlock(&info->lock);
1277 wait_on_page_locked(swappage);
1278 page_cache_release(swappage);
1279 goto repeat;
1280 }
1281 if (PageWriteback(swappage)) {
1282 shmem_swp_unmap(entry);
1283 spin_unlock(&info->lock);
1284 wait_on_page_writeback(swappage);
1285 unlock_page(swappage);
1286 page_cache_release(swappage);
1287 goto repeat;
1288 }
1289 if (!PageUptodate(swappage)) {
1290 shmem_swp_unmap(entry);
1291 spin_unlock(&info->lock);
1292 unlock_page(swappage);
1293 page_cache_release(swappage);
1294 error = -EIO;
1295 goto failed;
1296 }
1297
1298 if (filepage) {
1299 shmem_swp_set(info, entry, 0);
1300 shmem_swp_unmap(entry);
1301 delete_from_swap_cache(swappage);
1302 spin_unlock(&info->lock);
1303 copy_highpage(filepage, swappage);
1304 unlock_page(swappage);
1305 page_cache_release(swappage);
1306 flush_dcache_page(filepage);
1307 SetPageUptodate(filepage);
1308 set_page_dirty(filepage);
1309 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -07001310 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1311 idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312 info->flags |= SHMEM_PAGEIN;
1313 shmem_swp_set(info, entry, 0);
1314 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001315 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316 spin_unlock(&info->lock);
1317 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001318 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001319 swap_free(swap);
1320 } else {
1321 shmem_swp_unmap(entry);
1322 spin_unlock(&info->lock);
1323 unlock_page(swappage);
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001324 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001325 if (error == -ENOMEM) {
1326 /* allow reclaim from this memory cgroup */
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001327 error = mem_cgroup_shrink_usage(current->mm,
1328 gfp);
1329 if (error)
Hugh Dickins82369552008-02-07 00:14:22 -08001330 goto failed;
1331 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 goto repeat;
1333 }
1334 } else if (sgp == SGP_READ && !filepage) {
1335 shmem_swp_unmap(entry);
1336 filepage = find_get_page(mapping, idx);
1337 if (filepage &&
Nick Piggin529ae9a2008-08-02 12:01:03 +02001338 (!PageUptodate(filepage) || !trylock_page(filepage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 spin_unlock(&info->lock);
1340 wait_on_page_locked(filepage);
1341 page_cache_release(filepage);
1342 filepage = NULL;
1343 goto repeat;
1344 }
1345 spin_unlock(&info->lock);
1346 } else {
1347 shmem_swp_unmap(entry);
1348 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001349 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 spin_lock(&sbinfo->stat_lock);
1351 if (sbinfo->free_blocks == 0 ||
1352 shmem_acct_block(info->flags)) {
1353 spin_unlock(&sbinfo->stat_lock);
1354 spin_unlock(&info->lock);
1355 error = -ENOSPC;
1356 goto failed;
1357 }
1358 sbinfo->free_blocks--;
1359 inode->i_blocks += BLOCKS_PER_PAGE;
1360 spin_unlock(&sbinfo->stat_lock);
1361 } else if (shmem_acct_block(info->flags)) {
1362 spin_unlock(&info->lock);
1363 error = -ENOSPC;
1364 goto failed;
1365 }
1366
1367 if (!filepage) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001368 int ret;
1369
Linus Torvalds1da177e2005-04-16 15:20:36 -07001370 spin_unlock(&info->lock);
Hugh Dickins02098fe2008-02-04 22:28:42 -08001371 filepage = shmem_alloc_page(gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 if (!filepage) {
1373 shmem_unacct_blocks(info->flags, 1);
1374 shmem_free_blocks(inode, 1);
1375 error = -ENOMEM;
1376 goto failed;
1377 }
Rik van Rielb2e18532008-10-18 20:26:30 -07001378 SetPageSwapBacked(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379
Hugh Dickins82369552008-02-07 00:14:22 -08001380 /* Precharge page while we can wait, compensate after */
1381 error = mem_cgroup_cache_charge(filepage, current->mm,
1382 gfp & ~__GFP_HIGHMEM);
1383 if (error) {
1384 page_cache_release(filepage);
1385 shmem_unacct_blocks(info->flags, 1);
1386 shmem_free_blocks(inode, 1);
1387 filepage = NULL;
1388 goto failed;
1389 }
1390
Linus Torvalds1da177e2005-04-16 15:20:36 -07001391 spin_lock(&info->lock);
1392 entry = shmem_swp_alloc(info, idx, sgp);
1393 if (IS_ERR(entry))
1394 error = PTR_ERR(entry);
1395 else {
1396 swap = *entry;
1397 shmem_swp_unmap(entry);
1398 }
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001399 ret = error || swap.val;
1400 if (ret)
1401 mem_cgroup_uncharge_cache_page(filepage);
1402 else
1403 ret = add_to_page_cache_lru(filepage, mapping,
1404 idx, GFP_NOWAIT);
1405 /*
1406 * At add_to_page_cache_lru() failure, uncharge will
1407 * be done automatically.
1408 */
1409 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001410 spin_unlock(&info->lock);
1411 page_cache_release(filepage);
1412 shmem_unacct_blocks(info->flags, 1);
1413 shmem_free_blocks(inode, 1);
1414 filepage = NULL;
1415 if (error)
1416 goto failed;
1417 goto repeat;
1418 }
1419 info->flags |= SHMEM_PAGEIN;
1420 }
1421
1422 info->alloced++;
1423 spin_unlock(&info->lock);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001424 clear_highpage(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 flush_dcache_page(filepage);
1426 SetPageUptodate(filepage);
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001427 if (sgp == SGP_DIRTY)
1428 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 }
1430done:
Hugh Dickinsd3602442008-02-04 22:28:44 -08001431 *pagep = filepage;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432 return 0;
1433
1434failed:
1435 if (*pagep != filepage) {
1436 unlock_page(filepage);
1437 page_cache_release(filepage);
1438 }
1439 return error;
1440}
1441
Nick Piggind0217ac2007-07-19 01:47:03 -07001442static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001443{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001444 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001446 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447
Nick Piggind0217ac2007-07-19 01:47:03 -07001448 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1449 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001450
Hugh Dickins27d54b32008-02-04 22:28:43 -08001451 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001452 if (error)
1453 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454
Nick Piggin83c54072007-07-19 01:47:05 -07001455 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001456}
1457
Linus Torvalds1da177e2005-04-16 15:20:36 -07001458#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001459static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001461 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1463}
1464
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001465static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1466 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001467{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001468 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001469 unsigned long idx;
1470
1471 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1472 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1473}
1474#endif
1475
1476int shmem_lock(struct file *file, int lock, struct user_struct *user)
1477{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001478 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 struct shmem_inode_info *info = SHMEM_I(inode);
1480 int retval = -ENOMEM;
1481
1482 spin_lock(&info->lock);
1483 if (lock && !(info->flags & VM_LOCKED)) {
1484 if (!user_shm_lock(inode->i_size, user))
1485 goto out_nomem;
1486 info->flags |= VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001487 mapping_set_unevictable(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001488 }
1489 if (!lock && (info->flags & VM_LOCKED) && user) {
1490 user_shm_unlock(inode->i_size, user);
1491 info->flags &= ~VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001492 mapping_clear_unevictable(file->f_mapping);
1493 scan_mapping_unevictable_pages(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001494 }
1495 retval = 0;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001496
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497out_nomem:
1498 spin_unlock(&info->lock);
1499 return retval;
1500}
1501
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001502static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001503{
1504 file_accessed(file);
1505 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001506 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507 return 0;
1508}
1509
1510static struct inode *
1511shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1512{
1513 struct inode *inode;
1514 struct shmem_inode_info *info;
1515 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1516
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001517 if (shmem_reserve_inode(sb))
1518 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519
1520 inode = new_inode(sb);
1521 if (inode) {
1522 inode->i_mode = mode;
David Howells76aac0e2008-11-14 10:39:12 +11001523 inode->i_uid = current_fsuid();
1524 inode->i_gid = current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1527 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001528 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001529 info = SHMEM_I(inode);
1530 memset(info, 0, (char *)inode - (char *)info);
1531 spin_lock_init(&info->lock);
1532 INIT_LIST_HEAD(&info->swaplist);
1533
1534 switch (mode & S_IFMT) {
1535 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001536 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537 init_special_inode(inode, mode, dev);
1538 break;
1539 case S_IFREG:
Hugh Dickins14fcc232008-07-28 15:46:19 -07001540 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 inode->i_op = &shmem_inode_operations;
1542 inode->i_fop = &shmem_file_operations;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001543 mpol_shared_policy_init(&info->policy,
1544 shmem_get_sbmpol(sbinfo));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001545 break;
1546 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001547 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001548 /* Some things misbehave if size == 0 on a directory */
1549 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1550 inode->i_op = &shmem_dir_inode_operations;
1551 inode->i_fop = &simple_dir_operations;
1552 break;
1553 case S_IFLNK:
1554 /*
1555 * Must not load anything in the rbtree,
1556 * mpol_free_shared_policy will not be called.
1557 */
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001558 mpol_shared_policy_init(&info->policy, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559 break;
1560 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001561 } else
1562 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001563 return inode;
1564}
1565
1566#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001567static const struct inode_operations shmem_symlink_inode_operations;
1568static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001569
1570/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001571 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae976412007-06-04 10:00:39 +02001572 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1573 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001574 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001575static int shmem_readpage(struct file *file, struct page *page)
1576{
1577 struct inode *inode = page->mapping->host;
1578 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1579 unlock_page(page);
1580 return error;
1581}
1582
Linus Torvalds1da177e2005-04-16 15:20:36 -07001583static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001584shmem_write_begin(struct file *file, struct address_space *mapping,
1585 loff_t pos, unsigned len, unsigned flags,
1586 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587{
Nick Piggin800d15a2007-10-16 01:25:03 -07001588 struct inode *inode = mapping->host;
1589 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1590 *pagep = NULL;
1591 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1592}
1593
1594static int
1595shmem_write_end(struct file *file, struct address_space *mapping,
1596 loff_t pos, unsigned len, unsigned copied,
1597 struct page *page, void *fsdata)
1598{
1599 struct inode *inode = mapping->host;
1600
Hugh Dickinsd3602442008-02-04 22:28:44 -08001601 if (pos + copied > inode->i_size)
1602 i_size_write(inode, pos + copied);
1603
1604 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001605 set_page_dirty(page);
1606 page_cache_release(page);
1607
Nick Piggin800d15a2007-10-16 01:25:03 -07001608 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001609}
1610
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1612{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001613 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 struct address_space *mapping = inode->i_mapping;
1615 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001616 enum sgp_type sgp = SGP_READ;
1617
1618 /*
1619 * Might this read be for a stacking filesystem? Then when reading
1620 * holes of a sparse file, we actually need to allocate those pages,
1621 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1622 */
1623 if (segment_eq(get_fs(), KERNEL_DS))
1624 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625
1626 index = *ppos >> PAGE_CACHE_SHIFT;
1627 offset = *ppos & ~PAGE_CACHE_MASK;
1628
1629 for (;;) {
1630 struct page *page = NULL;
1631 unsigned long end_index, nr, ret;
1632 loff_t i_size = i_size_read(inode);
1633
1634 end_index = i_size >> PAGE_CACHE_SHIFT;
1635 if (index > end_index)
1636 break;
1637 if (index == end_index) {
1638 nr = i_size & ~PAGE_CACHE_MASK;
1639 if (nr <= offset)
1640 break;
1641 }
1642
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001643 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 if (desc->error) {
1645 if (desc->error == -EINVAL)
1646 desc->error = 0;
1647 break;
1648 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001649 if (page)
1650 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001651
1652 /*
1653 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001654 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001655 */
1656 nr = PAGE_CACHE_SIZE;
1657 i_size = i_size_read(inode);
1658 end_index = i_size >> PAGE_CACHE_SHIFT;
1659 if (index == end_index) {
1660 nr = i_size & ~PAGE_CACHE_MASK;
1661 if (nr <= offset) {
1662 if (page)
1663 page_cache_release(page);
1664 break;
1665 }
1666 }
1667 nr -= offset;
1668
1669 if (page) {
1670 /*
1671 * If users can be writing to this page using arbitrary
1672 * virtual addresses, take care about potential aliasing
1673 * before reading the page on the kernel side.
1674 */
1675 if (mapping_writably_mapped(mapping))
1676 flush_dcache_page(page);
1677 /*
1678 * Mark the page accessed if we read the beginning.
1679 */
1680 if (!offset)
1681 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001682 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001683 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001684 page_cache_get(page);
1685 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686
1687 /*
1688 * Ok, we have the page, and it's up-to-date, so
1689 * now we can copy it to user space...
1690 *
1691 * The actor routine returns how many bytes were actually used..
1692 * NOTE! This may not be the same as how much of a user buffer
1693 * we filled up (we may be padding etc), so we can only update
1694 * "pos" here (the actor routine has to update the user buffer
1695 * pointers and the remaining count).
1696 */
1697 ret = actor(desc, page, offset, nr);
1698 offset += ret;
1699 index += offset >> PAGE_CACHE_SHIFT;
1700 offset &= ~PAGE_CACHE_MASK;
1701
1702 page_cache_release(page);
1703 if (ret != nr || !desc->count)
1704 break;
1705
1706 cond_resched();
1707 }
1708
1709 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1710 file_accessed(filp);
1711}
1712
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001713static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1714 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715{
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001716 struct file *filp = iocb->ki_filp;
1717 ssize_t retval;
1718 unsigned long seg;
1719 size_t count;
1720 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001721
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001722 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1723 if (retval)
1724 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001726 for (seg = 0; seg < nr_segs; seg++) {
1727 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001729 desc.written = 0;
1730 desc.arg.buf = iov[seg].iov_base;
1731 desc.count = iov[seg].iov_len;
1732 if (desc.count == 0)
1733 continue;
1734 desc.error = 0;
1735 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1736 retval += desc.written;
1737 if (desc.error) {
1738 retval = retval ?: desc.error;
1739 break;
1740 }
1741 if (desc.count > 0)
1742 break;
1743 }
1744 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745}
1746
David Howells726c3342006-06-23 02:02:58 -07001747static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001748{
David Howells726c3342006-06-23 02:02:58 -07001749 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001750
1751 buf->f_type = TMPFS_MAGIC;
1752 buf->f_bsize = PAGE_CACHE_SIZE;
1753 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001754 spin_lock(&sbinfo->stat_lock);
1755 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756 buf->f_blocks = sbinfo->max_blocks;
1757 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001758 }
1759 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001760 buf->f_files = sbinfo->max_inodes;
1761 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001762 }
1763 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001764 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001765 return 0;
1766}
1767
1768/*
1769 * File creation. Allocate an inode, and we're done..
1770 */
1771static int
1772shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1773{
1774 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1775 int error = -ENOSPC;
1776
1777 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001778 error = security_inode_init_security(inode, dir, NULL, NULL,
1779 NULL);
1780 if (error) {
1781 if (error != -EOPNOTSUPP) {
1782 iput(inode);
1783 return error;
1784 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001785 }
1786 error = shmem_acl_init(inode, dir);
1787 if (error) {
1788 iput(inode);
1789 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001790 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 if (dir->i_mode & S_ISGID) {
1792 inode->i_gid = dir->i_gid;
1793 if (S_ISDIR(mode))
1794 inode->i_mode |= S_ISGID;
1795 }
1796 dir->i_size += BOGO_DIRENT_SIZE;
1797 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1798 d_instantiate(dentry, inode);
1799 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001800 }
1801 return error;
1802}
1803
1804static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1805{
1806 int error;
1807
1808 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1809 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001810 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811 return 0;
1812}
1813
1814static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1815 struct nameidata *nd)
1816{
1817 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1818}
1819
1820/*
1821 * Link a file..
1822 */
1823static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1824{
1825 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001826 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001827
1828 /*
1829 * No ordinary (disk based) filesystem counts links as inodes;
1830 * but each new link needs a new dentry, pinning lowmem, and
1831 * tmpfs dentries cannot be pruned until they are unlinked.
1832 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001833 ret = shmem_reserve_inode(inode->i_sb);
1834 if (ret)
1835 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836
1837 dir->i_size += BOGO_DIRENT_SIZE;
1838 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001839 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001840 atomic_inc(&inode->i_count); /* New dentry reference */
1841 dget(dentry); /* Extra pinning count for the created dentry */
1842 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001843out:
1844 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001845}
1846
1847static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1848{
1849 struct inode *inode = dentry->d_inode;
1850
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001851 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1852 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001853
1854 dir->i_size -= BOGO_DIRENT_SIZE;
1855 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001856 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001857 dput(dentry); /* Undo the count from "create" - this does all the work */
1858 return 0;
1859}
1860
1861static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1862{
1863 if (!simple_empty(dentry))
1864 return -ENOTEMPTY;
1865
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001866 drop_nlink(dentry->d_inode);
1867 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001868 return shmem_unlink(dir, dentry);
1869}
1870
1871/*
1872 * The VFS layer already does all the dentry stuff for rename,
1873 * we just have to decrement the usage count for the target if
1874 * it exists so that the VFS layer correctly free's it when it
1875 * gets overwritten.
1876 */
1877static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1878{
1879 struct inode *inode = old_dentry->d_inode;
1880 int they_are_dirs = S_ISDIR(inode->i_mode);
1881
1882 if (!simple_empty(new_dentry))
1883 return -ENOTEMPTY;
1884
1885 if (new_dentry->d_inode) {
1886 (void) shmem_unlink(new_dir, new_dentry);
1887 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001888 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001889 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001890 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001891 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001892 }
1893
1894 old_dir->i_size -= BOGO_DIRENT_SIZE;
1895 new_dir->i_size += BOGO_DIRENT_SIZE;
1896 old_dir->i_ctime = old_dir->i_mtime =
1897 new_dir->i_ctime = new_dir->i_mtime =
1898 inode->i_ctime = CURRENT_TIME;
1899 return 0;
1900}
1901
1902static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1903{
1904 int error;
1905 int len;
1906 struct inode *inode;
1907 struct page *page = NULL;
1908 char *kaddr;
1909 struct shmem_inode_info *info;
1910
1911 len = strlen(symname) + 1;
1912 if (len > PAGE_CACHE_SIZE)
1913 return -ENAMETOOLONG;
1914
1915 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1916 if (!inode)
1917 return -ENOSPC;
1918
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001919 error = security_inode_init_security(inode, dir, NULL, NULL,
1920 NULL);
1921 if (error) {
1922 if (error != -EOPNOTSUPP) {
1923 iput(inode);
1924 return error;
1925 }
1926 error = 0;
1927 }
1928
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 info = SHMEM_I(inode);
1930 inode->i_size = len-1;
1931 if (len <= (char *)inode - (char *)info) {
1932 /* do it inline */
1933 memcpy(info, symname, len);
1934 inode->i_op = &shmem_symlink_inline_operations;
1935 } else {
1936 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1937 if (error) {
1938 iput(inode);
1939 return error;
1940 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001941 unlock_page(page);
Hugh Dickins14fcc232008-07-28 15:46:19 -07001942 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943 inode->i_op = &shmem_symlink_inode_operations;
1944 kaddr = kmap_atomic(page, KM_USER0);
1945 memcpy(kaddr, symname, len);
1946 kunmap_atomic(kaddr, KM_USER0);
1947 set_page_dirty(page);
1948 page_cache_release(page);
1949 }
1950 if (dir->i_mode & S_ISGID)
1951 inode->i_gid = dir->i_gid;
1952 dir->i_size += BOGO_DIRENT_SIZE;
1953 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1954 d_instantiate(dentry, inode);
1955 dget(dentry);
1956 return 0;
1957}
1958
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001959static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960{
1961 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001962 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963}
1964
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001965static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966{
1967 struct page *page = NULL;
1968 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1969 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08001970 if (page)
1971 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001972 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973}
1974
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001975static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001976{
1977 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001978 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001979 kunmap(page);
1980 mark_page_accessed(page);
1981 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982 }
1983}
1984
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001985static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001986 .readlink = generic_readlink,
1987 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001988};
1989
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001990static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001991 .truncate = shmem_truncate,
1992 .readlink = generic_readlink,
1993 .follow_link = shmem_follow_link,
1994 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001995};
1996
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001997#ifdef CONFIG_TMPFS_POSIX_ACL
Randy Dunlap46711812008-03-19 17:00:41 -07001998/*
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001999 * Superblocks without xattr inode operations will get security.* xattr
2000 * support from the VFS "for free". As soon as we have any other xattrs
2001 * like ACLs, we also need to implement the security.* handlers at
2002 * filesystem level, though.
2003 */
2004
2005static size_t shmem_xattr_security_list(struct inode *inode, char *list,
2006 size_t list_len, const char *name,
2007 size_t name_len)
2008{
2009 return security_inode_listsecurity(inode, list, list_len);
2010}
2011
2012static int shmem_xattr_security_get(struct inode *inode, const char *name,
2013 void *buffer, size_t size)
2014{
2015 if (strcmp(name, "") == 0)
2016 return -EINVAL;
David P. Quigley42492592008-02-04 22:29:39 -08002017 return xattr_getsecurity(inode, name, buffer, size);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002018}
2019
2020static int shmem_xattr_security_set(struct inode *inode, const char *name,
2021 const void *value, size_t size, int flags)
2022{
2023 if (strcmp(name, "") == 0)
2024 return -EINVAL;
2025 return security_inode_setsecurity(inode, name, value, size, flags);
2026}
2027
Adrian Bunk1f370a22006-12-06 20:38:21 -08002028static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002029 .prefix = XATTR_SECURITY_PREFIX,
2030 .list = shmem_xattr_security_list,
2031 .get = shmem_xattr_security_get,
2032 .set = shmem_xattr_security_set,
2033};
2034
2035static struct xattr_handler *shmem_xattr_handlers[] = {
2036 &shmem_xattr_acl_access_handler,
2037 &shmem_xattr_acl_default_handler,
2038 &shmem_xattr_security_handler,
2039 NULL
2040};
2041#endif
2042
David M. Grimes91828a42006-10-17 00:09:45 -07002043static struct dentry *shmem_get_parent(struct dentry *child)
2044{
2045 return ERR_PTR(-ESTALE);
2046}
2047
2048static int shmem_match(struct inode *ino, void *vfh)
2049{
2050 __u32 *fh = vfh;
2051 __u64 inum = fh[2];
2052 inum = (inum << 32) | fh[1];
2053 return ino->i_ino == inum && fh[0] == ino->i_generation;
2054}
2055
Christoph Hellwig480b1162007-10-21 16:42:13 -07002056static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2057 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002058{
David M. Grimes91828a42006-10-17 00:09:45 -07002059 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002060 struct dentry *dentry = NULL;
2061 u64 inum = fid->raw[2];
2062 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002063
Christoph Hellwig480b1162007-10-21 16:42:13 -07002064 if (fh_len < 3)
2065 return NULL;
2066
2067 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2068 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002069 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002070 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002071 iput(inode);
2072 }
2073
Christoph Hellwig480b1162007-10-21 16:42:13 -07002074 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002075}
2076
2077static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2078 int connectable)
2079{
2080 struct inode *inode = dentry->d_inode;
2081
2082 if (*len < 3)
2083 return 255;
2084
2085 if (hlist_unhashed(&inode->i_hash)) {
2086 /* Unfortunately insert_inode_hash is not idempotent,
2087 * so as we hash inodes here rather than at creation
2088 * time, we need a lock to ensure we only try
2089 * to do it once
2090 */
2091 static DEFINE_SPINLOCK(lock);
2092 spin_lock(&lock);
2093 if (hlist_unhashed(&inode->i_hash))
2094 __insert_inode_hash(inode,
2095 inode->i_ino + inode->i_generation);
2096 spin_unlock(&lock);
2097 }
2098
2099 fh[0] = inode->i_generation;
2100 fh[1] = inode->i_ino;
2101 fh[2] = ((__u64)inode->i_ino) >> 32;
2102
2103 *len = 3;
2104 return 1;
2105}
2106
Christoph Hellwig39655162007-10-21 16:42:17 -07002107static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002108 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002109 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002110 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002111};
2112
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002113static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2114 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002115{
2116 char *this_char, *value, *rest;
2117
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002118 while (options != NULL) {
2119 this_char = options;
2120 for (;;) {
2121 /*
2122 * NUL-terminate this option: unfortunately,
2123 * mount options form a comma-separated list,
2124 * but mpol's nodelist may also contain commas.
2125 */
2126 options = strchr(options, ',');
2127 if (options == NULL)
2128 break;
2129 options++;
2130 if (!isdigit(*options)) {
2131 options[-1] = '\0';
2132 break;
2133 }
2134 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002135 if (!*this_char)
2136 continue;
2137 if ((value = strchr(this_char,'=')) != NULL) {
2138 *value++ = 0;
2139 } else {
2140 printk(KERN_ERR
2141 "tmpfs: No value for mount option '%s'\n",
2142 this_char);
2143 return 1;
2144 }
2145
2146 if (!strcmp(this_char,"size")) {
2147 unsigned long long size;
2148 size = memparse(value,&rest);
2149 if (*rest == '%') {
2150 size <<= PAGE_SHIFT;
2151 size *= totalram_pages;
2152 do_div(size, 100);
2153 rest++;
2154 }
2155 if (*rest)
2156 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002157 sbinfo->max_blocks =
2158 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002159 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002160 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002161 if (*rest)
2162 goto bad_val;
2163 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002164 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002165 if (*rest)
2166 goto bad_val;
2167 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002168 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002169 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002170 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002171 if (*rest)
2172 goto bad_val;
2173 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002174 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002176 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002177 if (*rest)
2178 goto bad_val;
2179 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002180 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002181 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002182 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002183 if (*rest)
2184 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002185 } else if (!strcmp(this_char,"mpol")) {
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002186 if (mpol_parse_str(value, &sbinfo->mpol, 1))
Robin Holt7339ff82006-01-14 13:20:48 -08002187 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002188 } else {
2189 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2190 this_char);
2191 return 1;
2192 }
2193 }
2194 return 0;
2195
2196bad_val:
2197 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2198 value, this_char);
2199 return 1;
2200
2201}
2202
2203static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2204{
2205 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002206 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002207 unsigned long blocks;
2208 unsigned long inodes;
2209 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002211 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002212 return error;
2213
2214 spin_lock(&sbinfo->stat_lock);
2215 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2216 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002217 if (config.max_blocks < blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002218 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002219 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002220 goto out;
2221 /*
2222 * Those tests also disallow limited->unlimited while any are in
2223 * use, so i_blocks will always be zero when max_blocks is zero;
2224 * but we must separately disallow unlimited->limited, because
2225 * in that case we have no record of how much is already in use.
2226 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002227 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002228 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002229 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002230 goto out;
2231
2232 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002233 sbinfo->max_blocks = config.max_blocks;
2234 sbinfo->free_blocks = config.max_blocks - blocks;
2235 sbinfo->max_inodes = config.max_inodes;
2236 sbinfo->free_inodes = config.max_inodes - inodes;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002237
2238 mpol_put(sbinfo->mpol);
2239 sbinfo->mpol = config.mpol; /* transfers initial ref */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002240out:
2241 spin_unlock(&sbinfo->stat_lock);
2242 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002244
2245static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2246{
2247 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2248
2249 if (sbinfo->max_blocks != shmem_default_max_blocks())
2250 seq_printf(seq, ",size=%luk",
2251 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2252 if (sbinfo->max_inodes != shmem_default_max_inodes())
2253 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2254 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2255 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2256 if (sbinfo->uid != 0)
2257 seq_printf(seq, ",uid=%u", sbinfo->uid);
2258 if (sbinfo->gid != 0)
2259 seq_printf(seq, ",gid=%u", sbinfo->gid);
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002260 shmem_show_mpol(seq, sbinfo->mpol);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002261 return 0;
2262}
2263#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002264
2265static void shmem_put_super(struct super_block *sb)
2266{
2267 kfree(sb->s_fs_info);
2268 sb->s_fs_info = NULL;
2269}
2270
Linus Torvalds1da177e2005-04-16 15:20:36 -07002271static int shmem_fill_super(struct super_block *sb,
2272 void *data, int silent)
2273{
2274 struct inode *inode;
2275 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002276 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002277 int err = -ENOMEM;
2278
2279 /* Round up to L1_CACHE_BYTES to resist false sharing */
2280 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2281 L1_CACHE_BYTES), GFP_KERNEL);
2282 if (!sbinfo)
2283 return -ENOMEM;
2284
2285 sbinfo->max_blocks = 0;
2286 sbinfo->max_inodes = 0;
2287 sbinfo->mode = S_IRWXUGO | S_ISVTX;
David Howells76aac0e2008-11-14 10:39:12 +11002288 sbinfo->uid = current_fsuid();
2289 sbinfo->gid = current_fsgid();
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002290 sbinfo->mpol = NULL;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002291 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002292
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002293#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002294 /*
2295 * Per default we only allow half of the physical ram per
2296 * tmpfs instance, limiting inodes to one per page of lowmem;
2297 * but the internal instance is left unlimited.
2298 */
2299 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002300 sbinfo->max_blocks = shmem_default_max_blocks();
2301 sbinfo->max_inodes = shmem_default_max_inodes();
2302 if (shmem_parse_options(data, sbinfo, false)) {
2303 err = -EINVAL;
2304 goto failed;
2305 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002306 }
David M. Grimes91828a42006-10-17 00:09:45 -07002307 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002308#else
2309 sb->s_flags |= MS_NOUSER;
2310#endif
2311
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002312 spin_lock_init(&sbinfo->stat_lock);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002313 sbinfo->free_blocks = sbinfo->max_blocks;
2314 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002315
Linus Torvalds1da177e2005-04-16 15:20:36 -07002316 sb->s_maxbytes = SHMEM_MAX_BYTES;
2317 sb->s_blocksize = PAGE_CACHE_SIZE;
2318 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2319 sb->s_magic = TMPFS_MAGIC;
2320 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002321 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002322#ifdef CONFIG_TMPFS_POSIX_ACL
2323 sb->s_xattr = shmem_xattr_handlers;
2324 sb->s_flags |= MS_POSIXACL;
2325#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002326
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002327 inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002328 if (!inode)
2329 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002330 inode->i_uid = sbinfo->uid;
2331 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332 root = d_alloc_root(inode);
2333 if (!root)
2334 goto failed_iput;
2335 sb->s_root = root;
2336 return 0;
2337
2338failed_iput:
2339 iput(inode);
2340failed:
2341 shmem_put_super(sb);
2342 return err;
2343}
2344
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002345static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002346
2347static struct inode *shmem_alloc_inode(struct super_block *sb)
2348{
2349 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002350 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002351 if (!p)
2352 return NULL;
2353 return &p->vfs_inode;
2354}
2355
2356static void shmem_destroy_inode(struct inode *inode)
2357{
2358 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2359 /* only struct inode is valid if it's an inline symlink */
2360 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2361 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002362 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002363 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2364}
2365
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07002366static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002367{
2368 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2369
Christoph Lametera35afb82007-05-16 22:10:57 -07002370 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002371#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002372 p->i_acl = NULL;
2373 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002374#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002375}
2376
2377static int init_inodecache(void)
2378{
2379 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2380 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002381 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002382 return 0;
2383}
2384
2385static void destroy_inodecache(void)
2386{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002387 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388}
2389
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002390static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002391 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002392 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002393#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002394 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002395 .write_begin = shmem_write_begin,
2396 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002397#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002398 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002399};
2400
Helge Deller15ad7cd2006-12-06 20:40:36 -08002401static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002402 .mmap = shmem_mmap,
2403#ifdef CONFIG_TMPFS
2404 .llseek = generic_file_llseek,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002405 .read = do_sync_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002406 .write = do_sync_write,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002407 .aio_read = shmem_file_aio_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002408 .aio_write = generic_file_aio_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002409 .fsync = simple_sync_file,
Hugh Dickinsae976412007-06-04 10:00:39 +02002410 .splice_read = generic_file_splice_read,
2411 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002412#endif
2413};
2414
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002415static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002416 .truncate = shmem_truncate,
2417 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002418 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002419#ifdef CONFIG_TMPFS_POSIX_ACL
2420 .setxattr = generic_setxattr,
2421 .getxattr = generic_getxattr,
2422 .listxattr = generic_listxattr,
2423 .removexattr = generic_removexattr,
2424 .permission = shmem_permission,
2425#endif
2426
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427};
2428
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002429static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430#ifdef CONFIG_TMPFS
2431 .create = shmem_create,
2432 .lookup = simple_lookup,
2433 .link = shmem_link,
2434 .unlink = shmem_unlink,
2435 .symlink = shmem_symlink,
2436 .mkdir = shmem_mkdir,
2437 .rmdir = shmem_rmdir,
2438 .mknod = shmem_mknod,
2439 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002440#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002441#ifdef CONFIG_TMPFS_POSIX_ACL
2442 .setattr = shmem_notify_change,
2443 .setxattr = generic_setxattr,
2444 .getxattr = generic_getxattr,
2445 .listxattr = generic_listxattr,
2446 .removexattr = generic_removexattr,
2447 .permission = shmem_permission,
2448#endif
2449};
2450
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002451static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002452#ifdef CONFIG_TMPFS_POSIX_ACL
2453 .setattr = shmem_notify_change,
2454 .setxattr = generic_setxattr,
2455 .getxattr = generic_getxattr,
2456 .listxattr = generic_listxattr,
2457 .removexattr = generic_removexattr,
2458 .permission = shmem_permission,
2459#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460};
2461
Hugh Dickins759b9772007-03-05 00:30:28 -08002462static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002463 .alloc_inode = shmem_alloc_inode,
2464 .destroy_inode = shmem_destroy_inode,
2465#ifdef CONFIG_TMPFS
2466 .statfs = shmem_statfs,
2467 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002468 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002469#endif
2470 .delete_inode = shmem_delete_inode,
2471 .drop_inode = generic_delete_inode,
2472 .put_super = shmem_put_super,
2473};
2474
2475static struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002476 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002477#ifdef CONFIG_NUMA
2478 .set_policy = shmem_set_policy,
2479 .get_policy = shmem_get_policy,
2480#endif
2481};
2482
2483
David Howells454e2392006-06-23 02:02:57 -07002484static int shmem_get_sb(struct file_system_type *fs_type,
2485 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002486{
David Howells454e2392006-06-23 02:02:57 -07002487 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002488}
2489
2490static struct file_system_type tmpfs_fs_type = {
2491 .owner = THIS_MODULE,
2492 .name = "tmpfs",
2493 .get_sb = shmem_get_sb,
2494 .kill_sb = kill_litter_super,
2495};
Linus Torvalds1da177e2005-04-16 15:20:36 -07002496
2497static int __init init_tmpfs(void)
2498{
2499 int error;
2500
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002501 error = bdi_init(&shmem_backing_dev_info);
2502 if (error)
2503 goto out4;
2504
Linus Torvalds1da177e2005-04-16 15:20:36 -07002505 error = init_inodecache();
2506 if (error)
2507 goto out3;
2508
2509 error = register_filesystem(&tmpfs_fs_type);
2510 if (error) {
2511 printk(KERN_ERR "Could not register tmpfs\n");
2512 goto out2;
2513 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002514
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002515 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002516 tmpfs_fs_type.name, NULL);
2517 if (IS_ERR(shm_mnt)) {
2518 error = PTR_ERR(shm_mnt);
2519 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2520 goto out1;
2521 }
2522 return 0;
2523
2524out1:
2525 unregister_filesystem(&tmpfs_fs_type);
2526out2:
2527 destroy_inodecache();
2528out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002529 bdi_destroy(&shmem_backing_dev_info);
2530out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002531 shm_mnt = ERR_PTR(error);
2532 return error;
2533}
Matt Mackall853ac432009-01-06 14:40:20 -08002534
2535#else /* !CONFIG_SHMEM */
2536
2537/*
2538 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2539 *
2540 * This is intended for small system where the benefits of the full
2541 * shmem code (swap-backed and resource-limited) are outweighed by
2542 * their complexity. On systems without swap this code should be
2543 * effectively equivalent, but much lighter weight.
2544 */
2545
2546#include <linux/ramfs.h>
2547
2548static struct file_system_type tmpfs_fs_type = {
2549 .name = "tmpfs",
2550 .get_sb = ramfs_get_sb,
2551 .kill_sb = kill_litter_super,
2552};
2553
2554static int __init init_tmpfs(void)
2555{
2556 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2557
2558 shm_mnt = kern_mount(&tmpfs_fs_type);
2559 BUG_ON(IS_ERR(shm_mnt));
2560
2561 return 0;
2562}
2563
2564int shmem_unuse(swp_entry_t entry, struct page *page)
2565{
2566 return 0;
2567}
2568
2569#define shmem_file_operations ramfs_file_operations
2570#define shmem_vm_ops generic_file_vm_ops
2571#define shmem_get_inode ramfs_get_inode
2572#define shmem_acct_size(a, b) 0
2573#define shmem_unacct_size(a, b) do {} while (0)
2574#define SHMEM_MAX_BYTES LLONG_MAX
2575
2576#endif /* CONFIG_SHMEM */
2577
2578/* common code */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579
Randy Dunlap46711812008-03-19 17:00:41 -07002580/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002582 * @name: name for dentry (to be seen in /proc/<pid>/maps
2583 * @size: size to be set for the file
Randy Dunlap46711812008-03-19 17:00:41 -07002584 * @flags: vm_flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07002585 */
2586struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2587{
2588 int error;
2589 struct file *file;
2590 struct inode *inode;
2591 struct dentry *dentry, *root;
2592 struct qstr this;
2593
2594 if (IS_ERR(shm_mnt))
2595 return (void *)shm_mnt;
2596
2597 if (size < 0 || size > SHMEM_MAX_BYTES)
2598 return ERR_PTR(-EINVAL);
2599
2600 if (shmem_acct_size(flags, size))
2601 return ERR_PTR(-ENOMEM);
2602
2603 error = -ENOMEM;
2604 this.name = name;
2605 this.len = strlen(name);
2606 this.hash = 0; /* will go */
2607 root = shm_mnt->mnt_root;
2608 dentry = d_alloc(root, &this);
2609 if (!dentry)
2610 goto put_memory;
2611
2612 error = -ENFILE;
2613 file = get_empty_filp();
2614 if (!file)
2615 goto put_dentry;
2616
2617 error = -ENOSPC;
2618 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2619 if (!inode)
2620 goto close_file;
2621
Matt Mackall853ac432009-01-06 14:40:20 -08002622#ifdef CONFIG_SHMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -07002623 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
Matt Mackall853ac432009-01-06 14:40:20 -08002624#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002625 d_instantiate(dentry, inode);
2626 inode->i_size = size;
2627 inode->i_nlink = 0; /* It is unlinked */
Dave Hansence8d2cd2007-10-16 23:31:13 -07002628 init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
Matt Mackall853ac432009-01-06 14:40:20 -08002629 &shmem_file_operations);
2630
2631#ifndef CONFIG_MMU
2632 error = ramfs_nommu_expand_for_mapping(inode, size);
2633 if (error)
2634 goto close_file;
2635#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636 return file;
2637
2638close_file:
2639 put_filp(file);
2640put_dentry:
2641 dput(dentry);
2642put_memory:
2643 shmem_unacct_size(flags, size);
2644 return ERR_PTR(error);
2645}
Keith Packard395e0dd2008-06-20 00:08:06 -07002646EXPORT_SYMBOL_GPL(shmem_file_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002647
Randy Dunlap46711812008-03-19 17:00:41 -07002648/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07002650 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2651 */
2652int shmem_zero_setup(struct vm_area_struct *vma)
2653{
2654 struct file *file;
2655 loff_t size = vma->vm_end - vma->vm_start;
2656
2657 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2658 if (IS_ERR(file))
2659 return PTR_ERR(file);
2660
2661 if (vma->vm_file)
2662 fput(vma->vm_file);
2663 vma->vm_file = file;
2664 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002665 return 0;
2666}
Matt Mackall853ac432009-01-06 14:40:20 -08002667
2668module_init(init_tmpfs)