blob: d221a1cfd7b196175ab9134aac147b22400c13e6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
Hugh Dickins0edd73b2005-06-21 17:15:04 -07009 * Copyright (C) 2002-2005 Hugh Dickins.
10 * Copyright (C) 2002-2005 VERITAS Software Corporation.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * Copyright (C) 2004 Andi Kleen, SuSE Labs
12 *
13 * Extended attribute support for tmpfs:
14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
16 *
Matt Mackall853ac432009-01-06 14:40:20 -080017 * tiny-shmem:
18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
19 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070020 * This file is released under the GPL.
21 */
22
Matt Mackall853ac432009-01-06 14:40:20 -080023#include <linux/fs.h>
24#include <linux/init.h>
25#include <linux/vfs.h>
26#include <linux/mount.h>
Hugh Dickinscaefba12009-04-13 14:40:12 -070027#include <linux/pagemap.h>
Matt Mackall853ac432009-01-06 14:40:20 -080028#include <linux/file.h>
29#include <linux/mm.h>
30#include <linux/module.h>
Tim Chen7e496292010-08-09 17:19:05 -070031#include <linux/percpu_counter.h>
Matt Mackall853ac432009-01-06 14:40:20 -080032#include <linux/swap.h>
33
34static struct vfsmount *shm_mnt;
35
36#ifdef CONFIG_SHMEM
Linus Torvalds1da177e2005-04-16 15:20:36 -070037/*
38 * This virtual memory filesystem is heavily based on the ramfs. It
39 * extends ramfs by the ability to use swap and honor resource limits
40 * which makes it a completely usable filesystem.
41 */
42
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070043#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070044#include <linux/exportfs.h>
Christoph Hellwig1c7c4742009-11-03 16:44:44 +010045#include <linux/posix_acl.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070046#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047#include <linux/mman.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#include <linux/string.h>
49#include <linux/slab.h>
50#include <linux/backing-dev.h>
51#include <linux/shmem_fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/writeback.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#include <linux/blkdev.h>
54#include <linux/security.h>
55#include <linux/swapops.h>
56#include <linux/mempolicy.h>
57#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000058#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070059#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070060#include <linux/highmem.h>
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -080061#include <linux/seq_file.h>
Mimi Zohar92562922008-10-07 14:00:12 -040062#include <linux/magic.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070063
Linus Torvalds1da177e2005-04-16 15:20:36 -070064#include <asm/uaccess.h>
65#include <asm/div64.h>
66#include <asm/pgtable.h>
67
Hugh Dickinscaefba12009-04-13 14:40:12 -070068/*
69 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
70 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
71 *
72 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
73 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
74 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
75 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
76 *
77 * We use / and * instead of shifts in the definitions below, so that the swap
78 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
79 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070080#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
Yuri Tikhonov61609d02009-04-13 14:40:11 -070081#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
Hugh Dickinscaefba12009-04-13 14:40:12 -070082
83#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
84#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
85
86#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
87#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
Linus Torvalds1da177e2005-04-16 15:20:36 -070090#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
91
92/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
93#define SHMEM_PAGEIN VM_READ
94#define SHMEM_TRUNCATE VM_WRITE
95
96/* Definition to limit shmem_truncate's steps between cond_rescheds */
97#define LATENCY_LIMIT 64
98
99/* Pretend that each entry is of this size in directory's i_size */
100#define BOGO_DIRENT_SIZE 20
101
Eric Parisb09e0fa2011-05-24 17:12:39 -0700102struct shmem_xattr {
103 struct list_head list; /* anchored by shmem_inode_info->xattr_list */
104 char *name; /* xattr name */
105 size_t size;
106 char value[0];
107};
108
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
110enum sgp_type {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 SGP_READ, /* don't exceed i_size, don't allocate page */
112 SGP_CACHE, /* don't exceed i_size, may allocate page */
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -0800113 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114 SGP_WRITE, /* may exceed i_size, may allocate page */
115};
116
Andrew Mortonb76db732008-02-08 04:21:49 -0800117#ifdef CONFIG_TMPFS
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800118static unsigned long shmem_default_max_blocks(void)
119{
120 return totalram_pages / 2;
121}
122
123static unsigned long shmem_default_max_inodes(void)
124{
125 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
126}
Andrew Mortonb76db732008-02-08 04:21:49 -0800127#endif
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -0800128
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129static int shmem_getpage(struct inode *inode, unsigned long idx,
130 struct page **pagep, enum sgp_type sgp, int *type);
131
Al Viro6daa0e22005-10-21 03:18:50 -0400132static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133{
134 /*
135 * The above definition of ENTRIES_PER_PAGE, and the use of
136 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
137 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -0700138 *
Mel Gormane12ba742007-10-16 01:25:52 -0700139 * Mobility flags are masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140 */
Mel Gormane12ba742007-10-16 01:25:52 -0700141 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
Mel Gorman769848c2007-07-17 04:03:05 -0700142 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143}
144
145static inline void shmem_dir_free(struct page *page)
146{
147 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
148}
149
150static struct page **shmem_dir_map(struct page *page)
151{
152 return (struct page **)kmap_atomic(page, KM_USER0);
153}
154
155static inline void shmem_dir_unmap(struct page **dir)
156{
157 kunmap_atomic(dir, KM_USER0);
158}
159
160static swp_entry_t *shmem_swp_map(struct page *page)
161{
162 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
163}
164
165static inline void shmem_swp_balance_unmap(void)
166{
167 /*
168 * When passing a pointer to an i_direct entry, to code which
169 * also handles indirect entries and so will shmem_swp_unmap,
170 * we must arrange for the preempt count to remain in balance.
171 * What kmap_atomic of a lowmem page does depends on config
172 * and architecture, so pretend to kmap_atomic some lowmem page.
173 */
174 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
175}
176
177static inline void shmem_swp_unmap(swp_entry_t *entry)
178{
179 kunmap_atomic(entry, KM_USER1);
180}
181
182static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
183{
184 return sb->s_fs_info;
185}
186
187/*
188 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
189 * for shared memory and for shared anonymous (/dev/zero) mappings
190 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
191 * consistent with the pre-accounting of private mappings ...
192 */
193static inline int shmem_acct_size(unsigned long flags, loff_t size)
194{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000195 return (flags & VM_NORESERVE) ?
196 0 : security_vm_enough_memory_kern(VM_ACCT(size));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197}
198
199static inline void shmem_unacct_size(unsigned long flags, loff_t size)
200{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000201 if (!(flags & VM_NORESERVE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 vm_unacct_memory(VM_ACCT(size));
203}
204
205/*
206 * ... whereas tmpfs objects are accounted incrementally as
207 * pages are allocated, in order to allow huge sparse files.
208 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
209 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
210 */
211static inline int shmem_acct_block(unsigned long flags)
212{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000213 return (flags & VM_NORESERVE) ?
214 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215}
216
217static inline void shmem_unacct_blocks(unsigned long flags, long pages)
218{
Hugh Dickins0b0a0802009-02-24 20:51:52 +0000219 if (flags & VM_NORESERVE)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
221}
222
Hugh Dickins759b9772007-03-05 00:30:28 -0800223static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700224static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800225static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800226static const struct inode_operations shmem_inode_operations;
227static const struct inode_operations shmem_dir_inode_operations;
228static const struct inode_operations shmem_special_inode_operations;
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +0400229static const struct vm_operations_struct shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700231static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232 .ra_pages = 0, /* No readahead */
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700233 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234};
235
236static LIST_HEAD(shmem_swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800237static DEFINE_MUTEX(shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238
239static void shmem_free_blocks(struct inode *inode, long pages)
240{
241 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700242 if (sbinfo->max_blocks) {
Tim Chen7e496292010-08-09 17:19:05 -0700243 percpu_counter_add(&sbinfo->used_blocks, -pages);
244 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -0700246 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247 }
248}
249
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800250static int shmem_reserve_inode(struct super_block *sb)
251{
252 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
253 if (sbinfo->max_inodes) {
254 spin_lock(&sbinfo->stat_lock);
255 if (!sbinfo->free_inodes) {
256 spin_unlock(&sbinfo->stat_lock);
257 return -ENOSPC;
258 }
259 sbinfo->free_inodes--;
260 spin_unlock(&sbinfo->stat_lock);
261 }
262 return 0;
263}
264
265static void shmem_free_inode(struct super_block *sb)
266{
267 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
268 if (sbinfo->max_inodes) {
269 spin_lock(&sbinfo->stat_lock);
270 sbinfo->free_inodes++;
271 spin_unlock(&sbinfo->stat_lock);
272 }
273}
274
Randy Dunlap46711812008-03-19 17:00:41 -0700275/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 * shmem_recalc_inode - recalculate the size of an inode
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277 * @inode: inode to recalc
278 *
279 * We have to calculate the free blocks since the mm can drop
280 * undirtied hole pages behind our back.
281 *
282 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
283 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
284 *
285 * It has to be called with the spinlock held.
286 */
287static void shmem_recalc_inode(struct inode *inode)
288{
289 struct shmem_inode_info *info = SHMEM_I(inode);
290 long freed;
291
292 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
293 if (freed > 0) {
294 info->alloced -= freed;
295 shmem_unacct_blocks(info->flags, freed);
296 shmem_free_blocks(inode, freed);
297 }
298}
299
Randy Dunlap46711812008-03-19 17:00:41 -0700300/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 * shmem_swp_entry - find the swap vector position in the info structure
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302 * @info: info structure for the inode
303 * @index: index of the page to find
304 * @page: optional page to add to the structure. Has to be preset to
305 * all zeros
306 *
307 * If there is no space allocated yet it will return NULL when
308 * page is NULL, else it will use the page for the needed block,
309 * setting it to NULL on return to indicate that it has been used.
310 *
311 * The swap vector is organized the following way:
312 *
313 * There are SHMEM_NR_DIRECT entries directly stored in the
314 * shmem_inode_info structure. So small files do not need an addional
315 * allocation.
316 *
317 * For pages with index > SHMEM_NR_DIRECT there is the pointer
318 * i_indirect which points to a page which holds in the first half
319 * doubly indirect blocks, in the second half triple indirect blocks:
320 *
321 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
322 * following layout (for SHMEM_NR_DIRECT == 16):
323 *
324 * i_indirect -> dir --> 16-19
325 * | +-> 20-23
326 * |
327 * +-->dir2 --> 24-27
328 * | +-> 28-31
329 * | +-> 32-35
330 * | +-> 36-39
331 * |
332 * +-->dir3 --> 40-43
333 * +-> 44-47
334 * +-> 48-51
335 * +-> 52-55
336 */
337static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
338{
339 unsigned long offset;
340 struct page **dir;
341 struct page *subdir;
342
343 if (index < SHMEM_NR_DIRECT) {
344 shmem_swp_balance_unmap();
345 return info->i_direct+index;
346 }
347 if (!info->i_indirect) {
348 if (page) {
349 info->i_indirect = *page;
350 *page = NULL;
351 }
352 return NULL; /* need another page */
353 }
354
355 index -= SHMEM_NR_DIRECT;
356 offset = index % ENTRIES_PER_PAGE;
357 index /= ENTRIES_PER_PAGE;
358 dir = shmem_dir_map(info->i_indirect);
359
360 if (index >= ENTRIES_PER_PAGE/2) {
361 index -= ENTRIES_PER_PAGE/2;
362 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
363 index %= ENTRIES_PER_PAGE;
364 subdir = *dir;
365 if (!subdir) {
366 if (page) {
367 *dir = *page;
368 *page = NULL;
369 }
370 shmem_dir_unmap(dir);
371 return NULL; /* need another page */
372 }
373 shmem_dir_unmap(dir);
374 dir = shmem_dir_map(subdir);
375 }
376
377 dir += index;
378 subdir = *dir;
379 if (!subdir) {
380 if (!page || !(subdir = *page)) {
381 shmem_dir_unmap(dir);
382 return NULL; /* need a page */
383 }
384 *dir = subdir;
385 *page = NULL;
386 }
387 shmem_dir_unmap(dir);
388 return shmem_swp_map(subdir) + offset;
389}
390
391static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
392{
393 long incdec = value? 1: -1;
394
395 entry->val = value;
396 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700397 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
398 struct page *page = kmap_atomic_to_page(entry);
399 set_page_private(page, page_private(page) + incdec);
400 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401}
402
Randy Dunlap46711812008-03-19 17:00:41 -0700403/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 * shmem_swp_alloc - get the position of the swap entry for the page.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 * @info: info structure for the inode
406 * @index: index of the page to find
407 * @sgp: check and recheck i_size? skip allocation?
Randy Dunlap46711812008-03-19 17:00:41 -0700408 *
409 * If the entry does not exist, allocate it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 */
411static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
412{
413 struct inode *inode = &info->vfs_inode;
414 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
415 struct page *page = NULL;
416 swp_entry_t *entry;
417
418 if (sgp != SGP_WRITE &&
419 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
420 return ERR_PTR(-EINVAL);
421
422 while (!(entry = shmem_swp_entry(info, index, &page))) {
423 if (sgp == SGP_READ)
424 return shmem_swp_map(ZERO_PAGE(0));
425 /*
Tim Chen7e496292010-08-09 17:19:05 -0700426 * Test used_blocks against 1 less max_blocks, since we have 1 data
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 * page (and perhaps indirect index pages) yet to allocate:
428 * a waste to allocate index if we cannot allocate data.
429 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700430 if (sbinfo->max_blocks) {
Hugh Dickinsfc5da222011-04-14 15:22:07 -0700431 if (percpu_counter_compare(&sbinfo->used_blocks,
432 sbinfo->max_blocks - 1) >= 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433 return ERR_PTR(-ENOSPC);
Tim Chen7e496292010-08-09 17:19:05 -0700434 percpu_counter_inc(&sbinfo->used_blocks);
435 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 inode->i_blocks += BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -0700437 spin_unlock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 }
439
440 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700441 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 spin_lock(&info->lock);
443
444 if (!page) {
445 shmem_free_blocks(inode, 1);
446 return ERR_PTR(-ENOMEM);
447 }
448 if (sgp != SGP_WRITE &&
449 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
450 entry = ERR_PTR(-EINVAL);
451 break;
452 }
453 if (info->next_index <= index)
454 info->next_index = index + 1;
455 }
456 if (page) {
457 /* another task gave its page, or truncated the file */
458 shmem_free_blocks(inode, 1);
459 shmem_dir_free(page);
460 }
461 if (info->next_index <= index && !IS_ERR(entry))
462 info->next_index = index + 1;
463 return entry;
464}
465
Randy Dunlap46711812008-03-19 17:00:41 -0700466/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 * shmem_free_swp - free some swap entries in a directory
Hugh Dickins1ae70002007-03-29 01:20:36 -0700468 * @dir: pointer to the directory
469 * @edir: pointer after last entry of the directory
470 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700472static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
473 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700475 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 swp_entry_t *ptr;
477 int freed = 0;
478
479 for (ptr = dir; ptr < edir; ptr++) {
480 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700481 if (unlikely(punch_lock)) {
482 punch_unlock = punch_lock;
483 punch_lock = NULL;
484 spin_lock(punch_unlock);
485 if (!ptr->val)
486 continue;
487 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 free_swap_and_cache(*ptr);
489 *ptr = (swp_entry_t){0};
490 freed++;
491 }
492 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700493 if (punch_unlock)
494 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 return freed;
496}
497
Hugh Dickins1ae70002007-03-29 01:20:36 -0700498static int shmem_map_and_free_swp(struct page *subdir, int offset,
499 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500{
501 swp_entry_t *ptr;
502 int freed = 0;
503
504 ptr = shmem_swp_map(subdir);
505 for (; offset < limit; offset += LATENCY_LIMIT) {
506 int size = limit - offset;
507 if (size > LATENCY_LIMIT)
508 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700509 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
510 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 if (need_resched()) {
512 shmem_swp_unmap(ptr);
513 if (*dir) {
514 shmem_dir_unmap(*dir);
515 *dir = NULL;
516 }
517 cond_resched();
518 ptr = shmem_swp_map(subdir);
519 }
520 }
521 shmem_swp_unmap(ptr);
522 return freed;
523}
524
525static void shmem_free_pages(struct list_head *next)
526{
527 struct page *page;
528 int freed = 0;
529
530 do {
531 page = container_of(next, struct page, lru);
532 next = next->next;
533 shmem_dir_free(page);
534 freed++;
535 if (freed >= LATENCY_LIMIT) {
536 cond_resched();
537 freed = 0;
538 }
539 } while (next);
540}
541
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800542static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543{
544 struct shmem_inode_info *info = SHMEM_I(inode);
545 unsigned long idx;
546 unsigned long size;
547 unsigned long limit;
548 unsigned long stage;
549 unsigned long diroff;
550 struct page **dir;
551 struct page *topdir;
552 struct page *middir;
553 struct page *subdir;
554 swp_entry_t *ptr;
555 LIST_HEAD(pages_to_free);
556 long nr_pages_to_free = 0;
557 long nr_swaps_freed = 0;
558 int offset;
559 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700560 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700561 spinlock_t *needs_lock;
562 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700563 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564
565 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800566 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567 if (idx >= info->next_index)
568 return;
569
570 spin_lock(&info->lock);
571 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800572 if (likely(end == (loff_t) -1)) {
573 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700574 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800575 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700576 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700577 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800578 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700579 if (end + 1 >= inode->i_size) { /* we may free a little more */
580 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
581 PAGE_CACHE_SHIFT;
582 upper_limit = SHMEM_MAX_INDEX;
583 } else {
584 limit = (end + 1) >> PAGE_CACHE_SHIFT;
585 upper_limit = limit;
586 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700587 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800588 punch_hole = 1;
589 }
590
Linus Torvalds1da177e2005-04-16 15:20:36 -0700591 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800592 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593 info->i_indirect = NULL;
594 nr_pages_to_free++;
595 list_add(&topdir->lru, &pages_to_free);
596 }
597 spin_unlock(&info->lock);
598
599 if (info->swapped && idx < SHMEM_NR_DIRECT) {
600 ptr = info->i_direct;
601 size = limit;
602 if (size > SHMEM_NR_DIRECT)
603 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700604 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800606
607 /*
608 * If there are no indirect blocks or we are punching a hole
609 * below indirect blocks, nothing to be done.
610 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700611 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 goto done2;
613
Hugh Dickins1ae70002007-03-29 01:20:36 -0700614 /*
615 * The truncation case has already dropped info->lock, and we're safe
616 * because i_size and next_index have already been lowered, preventing
617 * access beyond. But in the punch_hole case, we still need to take
618 * the lock when updating the swap directory, because there might be
619 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
620 * shmem_writepage. However, whenever we find we can remove a whole
621 * directory page (not at the misaligned start or end of the range),
622 * we first NULLify its pointer in the level above, and then have no
623 * need to take the lock when updating its contents: needs_lock and
624 * punch_lock (either pointing to info->lock or NULL) manage this.
625 */
626
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700627 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700628 limit -= SHMEM_NR_DIRECT;
629 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
630 offset = idx % ENTRIES_PER_PAGE;
631 idx -= offset;
632
633 dir = shmem_dir_map(topdir);
634 stage = ENTRIES_PER_PAGEPAGE/2;
635 if (idx < ENTRIES_PER_PAGEPAGE/2) {
636 middir = topdir;
637 diroff = idx/ENTRIES_PER_PAGE;
638 } else {
639 dir += ENTRIES_PER_PAGE/2;
640 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
641 while (stage <= idx)
642 stage += ENTRIES_PER_PAGEPAGE;
643 middir = *dir;
644 if (*dir) {
645 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
646 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700647 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700648 if (needs_lock) {
649 spin_lock(needs_lock);
650 *dir = NULL;
651 spin_unlock(needs_lock);
652 needs_lock = NULL;
653 } else
654 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655 nr_pages_to_free++;
656 list_add(&middir->lru, &pages_to_free);
657 }
658 shmem_dir_unmap(dir);
659 dir = shmem_dir_map(middir);
660 } else {
661 diroff = 0;
662 offset = 0;
663 idx = stage;
664 }
665 }
666
667 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
668 if (unlikely(idx == stage)) {
669 shmem_dir_unmap(dir);
670 dir = shmem_dir_map(topdir) +
671 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
672 while (!*dir) {
673 dir++;
674 idx += ENTRIES_PER_PAGEPAGE;
675 if (idx >= limit)
676 goto done1;
677 }
678 stage = idx + ENTRIES_PER_PAGEPAGE;
679 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700680 if (punch_hole)
681 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700682 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700683 if (needs_lock) {
684 spin_lock(needs_lock);
685 *dir = NULL;
686 spin_unlock(needs_lock);
687 needs_lock = NULL;
688 } else
689 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700690 nr_pages_to_free++;
691 list_add(&middir->lru, &pages_to_free);
692 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 shmem_dir_unmap(dir);
694 cond_resched();
695 dir = shmem_dir_map(middir);
696 diroff = 0;
697 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700698 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700699 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700700 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
701 if (needs_lock) {
702 spin_lock(needs_lock);
703 dir[diroff] = NULL;
704 spin_unlock(needs_lock);
705 punch_lock = NULL;
706 } else
707 dir[diroff] = NULL;
708 nr_pages_to_free++;
709 list_add(&subdir->lru, &pages_to_free);
710 }
711 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 size = limit - idx;
713 if (size > ENTRIES_PER_PAGE)
714 size = ENTRIES_PER_PAGE;
715 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700716 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717 if (!dir)
718 dir = shmem_dir_map(middir);
719 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700720 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700722 set_page_private(subdir,
723 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700725 } else
726 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700728 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 }
730done1:
731 shmem_dir_unmap(dir);
732done2:
733 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
734 /*
735 * Call truncate_inode_pages again: racing shmem_unuse_inode
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000736 * may have swizzled a page in from swap since
737 * truncate_pagecache or generic_delete_inode did it, before we
738 * lowered next_index. Also, though shmem_getpage checks
739 * i_size before adding to cache, no recheck after: so fix the
740 * narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700741 *
742 * Recalling truncate_inode_pages_range and unmap_mapping_range
743 * every time for punch_hole (which never got a chance to clear
744 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
745 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800747 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700748 if (punch_hole)
749 unmap_mapping_range(inode->i_mapping, start,
750 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700751 }
752
753 spin_lock(&info->lock);
754 info->flags &= ~SHMEM_TRUNCATE;
755 info->swapped -= nr_swaps_freed;
756 if (nr_pages_to_free)
757 shmem_free_blocks(inode, nr_pages_to_free);
758 shmem_recalc_inode(inode);
759 spin_unlock(&info->lock);
760
761 /*
762 * Empty swap vector directory pages to be freed?
763 */
764 if (!list_empty(&pages_to_free)) {
765 pages_to_free.prev->next = NULL;
766 shmem_free_pages(pages_to_free.next);
767 }
768}
769
770static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
771{
772 struct inode *inode = dentry->d_inode;
Nick Pigginaf5a30d2010-06-03 22:01:46 +1000773 loff_t newsize = attr->ia_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 int error;
775
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200776 error = inode_change_ok(inode, attr);
777 if (error)
778 return error;
779
Nick Pigginaf5a30d2010-06-03 22:01:46 +1000780 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)
781 && newsize != inode->i_size) {
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000782 struct page *page = NULL;
783
784 if (newsize < inode->i_size) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700785 /*
786 * If truncating down to a partial page, then
787 * if that page is already allocated, hold it
788 * in memory until the truncation is over, so
Justin P. Mattockae0e47f2011-03-01 15:06:02 +0100789 * truncate_partial_page cannot miss it were
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790 * it assigned to swap.
791 */
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000792 if (newsize & (PAGE_CACHE_SIZE-1)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 (void) shmem_getpage(inode,
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000794 newsize >> PAGE_CACHE_SHIFT,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700795 &page, SGP_READ, NULL);
Hugh Dickinsd3602442008-02-04 22:28:44 -0800796 if (page)
797 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 }
799 /*
800 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
801 * detect if any pages might have been added to cache
802 * after truncate_inode_pages. But we needn't bother
803 * if it's being fully truncated to zero-length: the
804 * nrpages check is efficient enough in that case.
805 */
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000806 if (newsize) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 struct shmem_inode_info *info = SHMEM_I(inode);
808 spin_lock(&info->lock);
809 info->flags &= ~SHMEM_PAGEIN;
810 spin_unlock(&info->lock);
811 }
812 }
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000813
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200814 /* XXX(truncate): truncate_setsize should be called last */
815 truncate_setsize(inode, newsize);
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000816 if (page)
817 page_cache_release(page);
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000818 shmem_truncate_range(inode, newsize, (loff_t)-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 }
820
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200821 setattr_copy(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700822#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Hellwigdb78b872010-06-04 11:30:03 +0200823 if (attr->ia_valid & ATTR_MODE)
Christoph Hellwig1c7c4742009-11-03 16:44:44 +0100824 error = generic_acl_chmod(inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700825#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 return error;
827}
828
Al Viro1f895f72010-06-05 19:10:41 -0400829static void shmem_evict_inode(struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831 struct shmem_inode_info *info = SHMEM_I(inode);
Eric Parisb09e0fa2011-05-24 17:12:39 -0700832 struct shmem_xattr *xattr, *nxattr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000834 if (inode->i_mapping->a_ops == &shmem_aops) {
Mark Fashehfef26652005-09-09 13:01:31 -0700835 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700836 shmem_unacct_size(info->flags, inode->i_size);
837 inode->i_size = 0;
npiggin@suse.de3889e6e2010-05-27 01:05:36 +1000838 shmem_truncate_range(inode, 0, (loff_t)-1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 if (!list_empty(&info->swaplist)) {
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800840 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841 list_del_init(&info->swaplist);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800842 mutex_unlock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 }
844 }
Eric Parisb09e0fa2011-05-24 17:12:39 -0700845
846 list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
847 kfree(xattr->name);
848 kfree(xattr);
849 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700850 BUG_ON(inode->i_blocks);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -0800851 shmem_free_inode(inode->i_sb);
Al Viro1f895f72010-06-05 19:10:41 -0400852 end_writeback(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700853}
854
855static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
856{
857 swp_entry_t *ptr;
858
859 for (ptr = dir; ptr < edir; ptr++) {
860 if (ptr->val == entry.val)
861 return ptr - dir;
862 }
863 return -1;
864}
865
866static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
867{
Hugh Dickins778dd892011-05-11 15:13:37 -0700868 struct address_space *mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 unsigned long idx;
870 unsigned long size;
871 unsigned long limit;
872 unsigned long stage;
873 struct page **dir;
874 struct page *subdir;
875 swp_entry_t *ptr;
876 int offset;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800877 int error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878
879 idx = 0;
880 ptr = info->i_direct;
881 spin_lock(&info->lock);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800882 if (!info->swapped) {
883 list_del_init(&info->swaplist);
884 goto lost2;
885 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700886 limit = info->next_index;
887 size = limit;
888 if (size > SHMEM_NR_DIRECT)
889 size = SHMEM_NR_DIRECT;
890 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickins778dd892011-05-11 15:13:37 -0700891 if (offset >= 0) {
892 shmem_swp_balance_unmap();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700893 goto found;
Hugh Dickins778dd892011-05-11 15:13:37 -0700894 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895 if (!info->i_indirect)
896 goto lost2;
897
898 dir = shmem_dir_map(info->i_indirect);
899 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
900
901 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
902 if (unlikely(idx == stage)) {
903 shmem_dir_unmap(dir-1);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -0800904 if (cond_resched_lock(&info->lock)) {
905 /* check it has not been truncated */
906 if (limit > info->next_index) {
907 limit = info->next_index;
908 if (idx >= limit)
909 goto lost2;
910 }
911 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700912 dir = shmem_dir_map(info->i_indirect) +
913 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
914 while (!*dir) {
915 dir++;
916 idx += ENTRIES_PER_PAGEPAGE;
917 if (idx >= limit)
918 goto lost1;
919 }
920 stage = idx + ENTRIES_PER_PAGEPAGE;
921 subdir = *dir;
922 shmem_dir_unmap(dir);
923 dir = shmem_dir_map(subdir);
924 }
925 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700926 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700927 ptr = shmem_swp_map(subdir);
928 size = limit - idx;
929 if (size > ENTRIES_PER_PAGE)
930 size = ENTRIES_PER_PAGE;
931 offset = shmem_find_swp(entry, ptr, ptr+size);
Hugh Dickinse6c93662011-05-20 15:47:33 -0700932 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700933 if (offset >= 0) {
934 shmem_dir_unmap(dir);
Hugh Dickinse6c93662011-05-20 15:47:33 -0700935 ptr = shmem_swp_map(subdir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700936 goto found;
937 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938 }
939 }
940lost1:
941 shmem_dir_unmap(dir-1);
942lost2:
943 spin_unlock(&info->lock);
944 return 0;
945found:
946 idx += offset;
Hugh Dickins778dd892011-05-11 15:13:37 -0700947 ptr += offset;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800948
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800949 /*
950 * Move _head_ to start search for next from here.
Al Viro1f895f72010-06-05 19:10:41 -0400951 * But be careful: shmem_evict_inode checks list_empty without taking
Hugh Dickins1b1b32f2008-02-04 22:28:55 -0800952 * mutex, and there's an instant in list_move_tail when info->swaplist
953 * would appear empty, if it were the only one on shmem_swaplist. We
954 * could avoid doing it if inode NULL; or use this minor optimization.
955 */
956 if (shmem_swaplist.next != &info->swaplist)
957 list_move_tail(&shmem_swaplist, &info->swaplist);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800958
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800959 /*
Hugh Dickins778dd892011-05-11 15:13:37 -0700960 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
961 * but also to hold up shmem_evict_inode(): so inode cannot be freed
962 * beneath us (pagelock doesn't help until the page is in pagecache).
KAMEZAWA Hiroyukid13d1442009-01-07 18:07:56 -0800963 */
Hugh Dickins778dd892011-05-11 15:13:37 -0700964 mapping = info->vfs_inode.i_mapping;
965 error = add_to_page_cache_locked(page, mapping, idx, GFP_NOWAIT);
966 /* which does mem_cgroup_uncharge_cache_page on error */
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700967
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800968 if (error == -EEXIST) {
Hugh Dickins778dd892011-05-11 15:13:37 -0700969 struct page *filepage = find_get_page(mapping, idx);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800970 error = 1;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -0800971 if (filepage) {
972 /*
973 * There might be a more uptodate page coming down
974 * from a stacked writepage: forget our swappage if so.
975 */
976 if (PageUptodate(filepage))
977 error = 0;
978 page_cache_release(filepage);
979 }
980 }
981 if (!error) {
Hugh Dickins73b12622008-02-04 22:28:50 -0800982 delete_from_swap_cache(page);
983 set_page_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700984 info->flags |= SHMEM_PAGEIN;
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800985 shmem_swp_set(info, ptr, 0);
986 swap_free(entry);
987 error = 1; /* not an error, but entry was found */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988 }
Hugh Dickins778dd892011-05-11 15:13:37 -0700989 shmem_swp_unmap(ptr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 spin_unlock(&info->lock);
Hugh Dickins2e0e26c2008-02-04 22:28:53 -0800991 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992}
993
994/*
995 * shmem_unuse() search for an eventually swapped out shmem page.
996 */
997int shmem_unuse(swp_entry_t entry, struct page *page)
998{
999 struct list_head *p, *next;
1000 struct shmem_inode_info *info;
1001 int found = 0;
Hugh Dickins778dd892011-05-11 15:13:37 -07001002 int error;
1003
1004 /*
1005 * Charge page using GFP_KERNEL while we can wait, before taking
1006 * the shmem_swaplist_mutex which might hold up shmem_writepage().
1007 * Charged back to the user (not to caller) when swap account is used.
1008 * add_to_page_cache() will be called with GFP_NOWAIT.
1009 */
1010 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
1011 if (error)
1012 goto out;
1013 /*
1014 * Try to preload while we can wait, to not make a habit of
1015 * draining atomic reserves; but don't latch on to this cpu,
1016 * it's okay if sometimes we get rescheduled after this.
1017 */
1018 error = radix_tree_preload(GFP_KERNEL);
1019 if (error)
1020 goto uncharge;
1021 radix_tree_preload_end();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001022
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001023 mutex_lock(&shmem_swaplist_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001024 list_for_each_safe(p, next, &shmem_swaplist) {
1025 info = list_entry(p, struct shmem_inode_info, swaplist);
Hugh Dickins1b1b32f2008-02-04 22:28:55 -08001026 found = shmem_unuse_inode(info, entry, page);
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001027 cond_resched();
Hugh Dickins2e0e26c2008-02-04 22:28:53 -08001028 if (found)
Hugh Dickins778dd892011-05-11 15:13:37 -07001029 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030 }
Hugh Dickinscb5f7b92008-02-04 22:28:52 -08001031 mutex_unlock(&shmem_swaplist_mutex);
Hugh Dickins778dd892011-05-11 15:13:37 -07001032
1033uncharge:
1034 if (!found)
1035 mem_cgroup_uncharge_cache_page(page);
1036 if (found < 0)
1037 error = found;
1038out:
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001039 unlock_page(page);
1040 page_cache_release(page);
Hugh Dickins778dd892011-05-11 15:13:37 -07001041 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001042}
1043
1044/*
1045 * Move the page from the page cache to the swap cache.
1046 */
1047static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1048{
1049 struct shmem_inode_info *info;
1050 swp_entry_t *entry, swap;
1051 struct address_space *mapping;
1052 unsigned long index;
1053 struct inode *inode;
1054
1055 BUG_ON(!PageLocked(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 mapping = page->mapping;
1057 index = page->index;
1058 inode = mapping->host;
1059 info = SHMEM_I(inode);
1060 if (info->flags & VM_LOCKED)
1061 goto redirty;
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001062 if (!total_swap_pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001063 goto redirty;
1064
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001065 /*
1066 * shmem_backing_dev_info's capabilities prevent regular writeback or
1067 * sync from ever calling shmem_writepage; but a stacking filesystem
1068 * may use the ->writepage of its underlying filesystem, in which case
1069 * tmpfs should write out to swap only in response to memory pressure,
Jens Axboe5b0830c2009-09-23 19:37:09 +02001070 * and not for the writeback threads or sync. However, in those cases,
1071 * we do still want to check if there's a redundant swappage to be
1072 * discarded.
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001073 */
1074 if (wbc->for_reclaim)
1075 swap = get_swap_page();
1076 else
1077 swap.val = 0;
1078
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001079 /*
1080 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1081 * if it's not already there. Do it now because we cannot take
1082 * mutex while holding spinlock, and must do so before the page
1083 * is moved to swap cache, when its pagelock no longer protects
1084 * the inode from eviction. But don't unlock the mutex until
1085 * we've taken the spinlock, because shmem_unuse_inode() will
1086 * prune a !swapped inode from the swaplist under both locks.
1087 */
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001088 if (swap.val) {
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001089 mutex_lock(&shmem_swaplist_mutex);
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001090 if (list_empty(&info->swaplist))
1091 list_add_tail(&info->swaplist, &shmem_swaplist);
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001092 }
1093
Linus Torvalds1da177e2005-04-16 15:20:36 -07001094 spin_lock(&info->lock);
Hugh Dickins05bf86b2011-05-14 12:06:42 -07001095 if (swap.val)
Hugh Dickinsb1dea802011-05-11 15:13:36 -07001096 mutex_unlock(&shmem_swaplist_mutex);
1097
Linus Torvalds1da177e2005-04-16 15:20:36 -07001098 if (index >= info->next_index) {
1099 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
1100 goto unlock;
1101 }
1102 entry = shmem_swp_entry(info, index, NULL);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001103 if (entry->val) {
1104 /*
1105 * The more uptodate page coming down from a stacked
1106 * writepage should replace our old swappage.
1107 */
1108 free_swap_and_cache(*entry);
1109 shmem_swp_set(info, entry, 0);
1110 }
1111 shmem_recalc_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001113 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
Minchan Kim4c73b1b2011-03-22 16:32:40 -07001114 delete_from_page_cache(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001115 shmem_swp_set(info, entry, swap.val);
1116 shmem_swp_unmap(entry);
Hugh Dickinsaaa46862009-12-14 17:58:47 -08001117 swap_shmem_alloc(swap);
Hugh Dickins826267c2011-05-28 13:14:09 -07001118 spin_unlock(&info->lock);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001119 BUG_ON(page_mapped(page));
Hugh Dickins9fab5612009-03-31 15:23:33 -07001120 swap_writepage(page, wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121 return 0;
1122 }
1123
1124 shmem_swp_unmap(entry);
1125unlock:
1126 spin_unlock(&info->lock);
Daisuke Nishimura2ca45322009-09-21 17:02:52 -07001127 /*
1128 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
1129 * clear SWAP_HAS_CACHE flag.
1130 */
KAMEZAWA Hiroyukicb4b86b2009-06-16 15:32:52 -07001131 swapcache_free(swap, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001132redirty:
1133 set_page_dirty(page);
Hugh Dickinsd9fe5262008-02-04 22:28:51 -08001134 if (wbc->for_reclaim)
1135 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1136 unlock_page(page);
1137 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138}
1139
1140#ifdef CONFIG_NUMA
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001141#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001142static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001143{
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001144 char buffer[64];
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001145
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001146 if (!mpol || mpol->mode == MPOL_DEFAULT)
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001147 return; /* show nothing */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001148
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001149 mpol_to_str(buffer, sizeof(buffer), mpol, 1);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001150
Lee Schermerhorn095f1fc2008-04-28 02:13:23 -07001151 seq_printf(seq, ",mpol=%s", buffer);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001152}
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001153
1154static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1155{
1156 struct mempolicy *mpol = NULL;
1157 if (sbinfo->mpol) {
1158 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1159 mpol = sbinfo->mpol;
1160 mpol_get(mpol);
1161 spin_unlock(&sbinfo->stat_lock);
1162 }
1163 return mpol;
1164}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001165#endif /* CONFIG_TMPFS */
1166
Hugh Dickins02098fe2008-02-04 22:28:42 -08001167static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1168 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001169{
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001170 struct mempolicy mpol, *spol;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001171 struct vm_area_struct pvma;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001172 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001173
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001174 spol = mpol_cond_copy(&mpol,
1175 mpol_shared_policy_lookup(&info->policy, idx));
1176
Linus Torvalds1da177e2005-04-16 15:20:36 -07001177 /* Create a pseudo vma that just contains the policy */
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001178 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001179 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001180 pvma.vm_ops = NULL;
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001181 pvma.vm_policy = spol;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001182 page = swapin_readahead(entry, gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001183 return page;
1184}
1185
Hugh Dickins02098fe2008-02-04 22:28:42 -08001186static struct page *shmem_alloc_page(gfp_t gfp,
1187 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188{
1189 struct vm_area_struct pvma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001190
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001191 /* Create a pseudo vma that just contains the policy */
1192 pvma.vm_start = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 pvma.vm_pgoff = idx;
Hugh Dickinsc4cc6d02008-02-04 22:28:40 -08001194 pvma.vm_ops = NULL;
1195 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
Lee Schermerhorn52cd3b02008-04-28 02:13:16 -07001196
1197 /*
1198 * alloc_page_vma() will drop the shared policy reference
1199 */
1200 return alloc_page_vma(gfp, &pvma, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001202#else /* !CONFIG_NUMA */
1203#ifdef CONFIG_TMPFS
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001204static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001205{
1206}
1207#endif /* CONFIG_TMPFS */
1208
Hugh Dickins02098fe2008-02-04 22:28:42 -08001209static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
1210 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001211{
Hugh Dickins02098fe2008-02-04 22:28:42 -08001212 return swapin_readahead(entry, gfp, NULL, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213}
1214
Hugh Dickins02098fe2008-02-04 22:28:42 -08001215static inline struct page *shmem_alloc_page(gfp_t gfp,
1216 struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217{
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001218 return alloc_page(gfp);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08001220#endif /* CONFIG_NUMA */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001221
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001222#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
1223static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1224{
1225 return NULL;
1226}
1227#endif
1228
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229/*
1230 * shmem_getpage - either get the page from swap or allocate a new one
1231 *
1232 * If we allocate a new one we do not mark it dirty. That's up to the
1233 * vm. If we swap it in we mark it dirty since we also free the swap
1234 * entry since a page cannot live in both the swap and page cache
1235 */
1236static int shmem_getpage(struct inode *inode, unsigned long idx,
1237 struct page **pagep, enum sgp_type sgp, int *type)
1238{
1239 struct address_space *mapping = inode->i_mapping;
1240 struct shmem_inode_info *info = SHMEM_I(inode);
1241 struct shmem_sb_info *sbinfo;
1242 struct page *filepage = *pagep;
1243 struct page *swappage;
Shaohua Liff36b802010-08-09 17:19:06 -07001244 struct page *prealloc_page = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245 swp_entry_t *entry;
1246 swp_entry_t swap;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001247 gfp_t gfp;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001248 int error;
1249
1250 if (idx >= SHMEM_MAX_INDEX)
1251 return -EFBIG;
Nick Piggin54cb8822007-07-19 01:46:59 -07001252
1253 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001254 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001255
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256 /*
1257 * Normally, filepage is NULL on entry, and either found
1258 * uptodate immediately, or allocated and zeroed, or read
1259 * in under swappage, which is then assigned to filepage.
Hugh Dickins5402b972008-02-04 22:28:44 -08001260 * But shmem_readpage (required for splice) passes in a locked
Hugh Dickinsae976412007-06-04 10:00:39 +02001261 * filepage, which may be found not uptodate by other callers
1262 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001263 */
1264repeat:
1265 if (!filepage)
1266 filepage = find_lock_page(mapping, idx);
1267 if (filepage && PageUptodate(filepage))
1268 goto done;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001269 gfp = mapping_gfp_mask(mapping);
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001270 if (!filepage) {
1271 /*
1272 * Try to preload while we can wait, to not make a habit of
1273 * draining atomic reserves; but don't latch on to this cpu.
1274 */
1275 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
1276 if (error)
1277 goto failed;
1278 radix_tree_preload_end();
Shaohua Liff36b802010-08-09 17:19:06 -07001279 if (sgp != SGP_READ && !prealloc_page) {
1280 /* We don't care if this fails */
1281 prealloc_page = shmem_alloc_page(gfp, info, idx);
1282 if (prealloc_page) {
1283 if (mem_cgroup_cache_charge(prealloc_page,
1284 current->mm, GFP_KERNEL)) {
1285 page_cache_release(prealloc_page);
1286 prealloc_page = NULL;
1287 }
1288 }
1289 }
Hugh Dickinsb409f9f2008-02-04 22:28:54 -08001290 }
Shaohua Liff36b802010-08-09 17:19:06 -07001291 error = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292
1293 spin_lock(&info->lock);
1294 shmem_recalc_inode(inode);
1295 entry = shmem_swp_alloc(info, idx, sgp);
1296 if (IS_ERR(entry)) {
1297 spin_unlock(&info->lock);
1298 error = PTR_ERR(entry);
1299 goto failed;
1300 }
1301 swap = *entry;
1302
1303 if (swap.val) {
1304 /* Look it up and read it in.. */
1305 swappage = lookup_swap_cache(swap);
1306 if (!swappage) {
1307 shmem_swp_unmap(entry);
Christoph Lameterf8891e52006-06-30 01:55:45 -07001308 spin_unlock(&info->lock);
Ying Han456f9982011-05-26 16:25:38 -07001309 /* here we actually do the io */
1310 if (type)
1311 *type |= VM_FAULT_MAJOR;
Hugh Dickins02098fe2008-02-04 22:28:42 -08001312 swappage = shmem_swapin(swap, gfp, info, idx);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001313 if (!swappage) {
1314 spin_lock(&info->lock);
1315 entry = shmem_swp_alloc(info, idx, sgp);
1316 if (IS_ERR(entry))
1317 error = PTR_ERR(entry);
1318 else {
1319 if (entry->val == swap.val)
1320 error = -ENOMEM;
1321 shmem_swp_unmap(entry);
1322 }
1323 spin_unlock(&info->lock);
1324 if (error)
1325 goto failed;
1326 goto repeat;
1327 }
1328 wait_on_page_locked(swappage);
1329 page_cache_release(swappage);
1330 goto repeat;
1331 }
1332
1333 /* We have to do this with page locked to prevent races */
Nick Piggin529ae9a2008-08-02 12:01:03 +02001334 if (!trylock_page(swappage)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001335 shmem_swp_unmap(entry);
1336 spin_unlock(&info->lock);
1337 wait_on_page_locked(swappage);
1338 page_cache_release(swappage);
1339 goto repeat;
1340 }
1341 if (PageWriteback(swappage)) {
1342 shmem_swp_unmap(entry);
1343 spin_unlock(&info->lock);
1344 wait_on_page_writeback(swappage);
1345 unlock_page(swappage);
1346 page_cache_release(swappage);
1347 goto repeat;
1348 }
1349 if (!PageUptodate(swappage)) {
1350 shmem_swp_unmap(entry);
1351 spin_unlock(&info->lock);
1352 unlock_page(swappage);
1353 page_cache_release(swappage);
1354 error = -EIO;
1355 goto failed;
1356 }
1357
1358 if (filepage) {
1359 shmem_swp_set(info, entry, 0);
1360 shmem_swp_unmap(entry);
1361 delete_from_swap_cache(swappage);
1362 spin_unlock(&info->lock);
1363 copy_highpage(filepage, swappage);
1364 unlock_page(swappage);
1365 page_cache_release(swappage);
1366 flush_dcache_page(filepage);
1367 SetPageUptodate(filepage);
1368 set_page_dirty(filepage);
1369 swap_free(swap);
Nick Piggine2867812008-07-25 19:45:30 -07001370 } else if (!(error = add_to_page_cache_locked(swappage, mapping,
1371 idx, GFP_NOWAIT))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372 info->flags |= SHMEM_PAGEIN;
1373 shmem_swp_set(info, entry, 0);
1374 shmem_swp_unmap(entry);
Hugh Dickins73b12622008-02-04 22:28:50 -08001375 delete_from_swap_cache(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376 spin_unlock(&info->lock);
1377 filepage = swappage;
Hugh Dickins73b12622008-02-04 22:28:50 -08001378 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001379 swap_free(swap);
1380 } else {
1381 shmem_swp_unmap(entry);
1382 spin_unlock(&info->lock);
Hugh Dickins82369552008-02-07 00:14:22 -08001383 if (error == -ENOMEM) {
Daisuke Nishimuraae3abae2009-04-30 15:08:19 -07001384 /*
1385 * reclaim from proper memory cgroup and
1386 * call memcg's OOM if needed.
1387 */
1388 error = mem_cgroup_shmem_charge_fallback(
1389 swappage,
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001390 current->mm,
KAMEZAWA Hiroyukic9b0ed52008-07-25 01:47:15 -07001391 gfp);
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001392 if (error) {
1393 unlock_page(swappage);
1394 page_cache_release(swappage);
Hugh Dickins82369552008-02-07 00:14:22 -08001395 goto failed;
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001396 }
Hugh Dickins82369552008-02-07 00:14:22 -08001397 }
KAMEZAWA Hiroyukib5a84312009-01-07 18:08:35 -08001398 unlock_page(swappage);
1399 page_cache_release(swappage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001400 goto repeat;
1401 }
1402 } else if (sgp == SGP_READ && !filepage) {
1403 shmem_swp_unmap(entry);
1404 filepage = find_get_page(mapping, idx);
1405 if (filepage &&
Nick Piggin529ae9a2008-08-02 12:01:03 +02001406 (!PageUptodate(filepage) || !trylock_page(filepage))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001407 spin_unlock(&info->lock);
1408 wait_on_page_locked(filepage);
1409 page_cache_release(filepage);
1410 filepage = NULL;
1411 goto repeat;
1412 }
1413 spin_unlock(&info->lock);
1414 } else {
1415 shmem_swp_unmap(entry);
1416 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001417 if (sbinfo->max_blocks) {
Hugh Dickinsfc5da222011-04-14 15:22:07 -07001418 if (percpu_counter_compare(&sbinfo->used_blocks,
1419 sbinfo->max_blocks) >= 0 ||
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001420 shmem_acct_block(info->flags))
1421 goto nospace;
Tim Chen7e496292010-08-09 17:19:05 -07001422 percpu_counter_inc(&sbinfo->used_blocks);
1423 spin_lock(&inode->i_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 inode->i_blocks += BLOCKS_PER_PAGE;
Tim Chen7e496292010-08-09 17:19:05 -07001425 spin_unlock(&inode->i_lock);
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001426 } else if (shmem_acct_block(info->flags))
1427 goto nospace;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428
1429 if (!filepage) {
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001430 int ret;
1431
Shaohua Liff36b802010-08-09 17:19:06 -07001432 if (!prealloc_page) {
1433 spin_unlock(&info->lock);
1434 filepage = shmem_alloc_page(gfp, info, idx);
1435 if (!filepage) {
1436 shmem_unacct_blocks(info->flags, 1);
1437 shmem_free_blocks(inode, 1);
1438 error = -ENOMEM;
1439 goto failed;
1440 }
1441 SetPageSwapBacked(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442
Shaohua Liff36b802010-08-09 17:19:06 -07001443 /*
1444 * Precharge page while we can wait, compensate
1445 * after
1446 */
1447 error = mem_cgroup_cache_charge(filepage,
1448 current->mm, GFP_KERNEL);
1449 if (error) {
1450 page_cache_release(filepage);
1451 shmem_unacct_blocks(info->flags, 1);
1452 shmem_free_blocks(inode, 1);
1453 filepage = NULL;
1454 goto failed;
1455 }
1456
1457 spin_lock(&info->lock);
1458 } else {
1459 filepage = prealloc_page;
1460 prealloc_page = NULL;
1461 SetPageSwapBacked(filepage);
Hugh Dickins82369552008-02-07 00:14:22 -08001462 }
1463
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 entry = shmem_swp_alloc(info, idx, sgp);
1465 if (IS_ERR(entry))
1466 error = PTR_ERR(entry);
1467 else {
1468 swap = *entry;
1469 shmem_swp_unmap(entry);
1470 }
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001471 ret = error || swap.val;
1472 if (ret)
1473 mem_cgroup_uncharge_cache_page(filepage);
1474 else
1475 ret = add_to_page_cache_lru(filepage, mapping,
1476 idx, GFP_NOWAIT);
1477 /*
1478 * At add_to_page_cache_lru() failure, uncharge will
1479 * be done automatically.
1480 */
1481 if (ret) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482 spin_unlock(&info->lock);
1483 page_cache_release(filepage);
1484 shmem_unacct_blocks(info->flags, 1);
1485 shmem_free_blocks(inode, 1);
1486 filepage = NULL;
1487 if (error)
1488 goto failed;
1489 goto repeat;
1490 }
1491 info->flags |= SHMEM_PAGEIN;
1492 }
1493
1494 info->alloced++;
1495 spin_unlock(&info->lock);
Hugh Dickinse84e2e12007-11-28 18:55:10 +00001496 clear_highpage(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001497 flush_dcache_page(filepage);
1498 SetPageUptodate(filepage);
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001499 if (sgp == SGP_DIRTY)
1500 set_page_dirty(filepage);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001501 }
1502done:
Hugh Dickinsd3602442008-02-04 22:28:44 -08001503 *pagep = filepage;
Shaohua Liff36b802010-08-09 17:19:06 -07001504 error = 0;
1505 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001506
Hugh Dickins59a16ea2011-05-11 15:13:38 -07001507nospace:
1508 /*
1509 * Perhaps the page was brought in from swap between find_lock_page
1510 * and taking info->lock? We allow for that at add_to_page_cache_lru,
1511 * but must also avoid reporting a spurious ENOSPC while working on a
1512 * full tmpfs. (When filepage has been passed in to shmem_getpage, it
1513 * is already in page cache, which prevents this race from occurring.)
1514 */
1515 if (!filepage) {
1516 struct page *page = find_get_page(mapping, idx);
1517 if (page) {
1518 spin_unlock(&info->lock);
1519 page_cache_release(page);
1520 goto repeat;
1521 }
1522 }
1523 spin_unlock(&info->lock);
1524 error = -ENOSPC;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001525failed:
1526 if (*pagep != filepage) {
1527 unlock_page(filepage);
1528 page_cache_release(filepage);
1529 }
Shaohua Liff36b802010-08-09 17:19:06 -07001530out:
1531 if (prealloc_page) {
1532 mem_cgroup_uncharge_cache_page(prealloc_page);
1533 page_cache_release(prealloc_page);
1534 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535 return error;
1536}
1537
Nick Piggind0217ac2007-07-19 01:47:03 -07001538static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001540 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001541 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001542 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001543
Nick Piggind0217ac2007-07-19 01:47:03 -07001544 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1545 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001546
Hugh Dickins27d54b32008-02-04 22:28:43 -08001547 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
Nick Piggind0217ac2007-07-19 01:47:03 -07001548 if (error)
1549 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Ying Han456f9982011-05-26 16:25:38 -07001550 if (ret & VM_FAULT_MAJOR) {
1551 count_vm_event(PGMAJFAULT);
1552 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1553 }
Nick Piggin83c54072007-07-19 01:47:05 -07001554 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555}
1556
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557#ifdef CONFIG_NUMA
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001558static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001559{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001560 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001561 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1562}
1563
Adrian Bunkd8dc74f2007-10-16 01:26:26 -07001564static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1565 unsigned long addr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001566{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001567 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001568 unsigned long idx;
1569
1570 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1571 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1572}
1573#endif
1574
1575int shmem_lock(struct file *file, int lock, struct user_struct *user)
1576{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001577 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 struct shmem_inode_info *info = SHMEM_I(inode);
1579 int retval = -ENOMEM;
1580
1581 spin_lock(&info->lock);
1582 if (lock && !(info->flags & VM_LOCKED)) {
1583 if (!user_shm_lock(inode->i_size, user))
1584 goto out_nomem;
1585 info->flags |= VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001586 mapping_set_unevictable(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 }
1588 if (!lock && (info->flags & VM_LOCKED) && user) {
1589 user_shm_unlock(inode->i_size, user);
1590 info->flags &= ~VM_LOCKED;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001591 mapping_clear_unevictable(file->f_mapping);
1592 scan_mapping_unevictable_pages(file->f_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 }
1594 retval = 0;
Lee Schermerhorn89e004ea2008-10-18 20:26:43 -07001595
Linus Torvalds1da177e2005-04-16 15:20:36 -07001596out_nomem:
1597 spin_unlock(&info->lock);
1598 return retval;
1599}
1600
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001601static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602{
1603 file_accessed(file);
1604 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001605 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001606 return 0;
1607}
1608
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001609static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1610 int mode, dev_t dev, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611{
1612 struct inode *inode;
1613 struct shmem_inode_info *info;
1614 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1615
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001616 if (shmem_reserve_inode(sb))
1617 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618
1619 inode = new_inode(sb);
1620 if (inode) {
Christoph Hellwig85fe4022010-10-23 11:19:54 -04001621 inode->i_ino = get_next_ino();
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001622 inode_init_owner(inode, dir, mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001623 inode->i_blocks = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001624 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1625 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001626 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627 info = SHMEM_I(inode);
1628 memset(info, 0, (char *)inode - (char *)info);
1629 spin_lock_init(&info->lock);
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001630 info->flags = flags & VM_NORESERVE;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 INIT_LIST_HEAD(&info->swaplist);
Eric Parisb09e0fa2011-05-24 17:12:39 -07001632 INIT_LIST_HEAD(&info->xattr_list);
Al Viro72c04902009-06-24 16:58:48 -04001633 cache_no_acl(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634
1635 switch (mode & S_IFMT) {
1636 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001637 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 init_special_inode(inode, mode, dev);
1639 break;
1640 case S_IFREG:
Hugh Dickins14fcc232008-07-28 15:46:19 -07001641 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001642 inode->i_op = &shmem_inode_operations;
1643 inode->i_fop = &shmem_file_operations;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001644 mpol_shared_policy_init(&info->policy,
1645 shmem_get_sbmpol(sbinfo));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001646 break;
1647 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001648 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001649 /* Some things misbehave if size == 0 on a directory */
1650 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1651 inode->i_op = &shmem_dir_inode_operations;
1652 inode->i_fop = &simple_dir_operations;
1653 break;
1654 case S_IFLNK:
1655 /*
1656 * Must not load anything in the rbtree,
1657 * mpol_free_shared_policy will not be called.
1658 */
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07001659 mpol_shared_policy_init(&info->policy, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001660 break;
1661 }
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001662 } else
1663 shmem_free_inode(sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001664 return inode;
1665}
1666
1667#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001668static const struct inode_operations shmem_symlink_inode_operations;
1669static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001670
1671/*
Nick Piggin800d15a2007-10-16 01:25:03 -07001672 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
Hugh Dickinsae976412007-06-04 10:00:39 +02001673 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1674 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001676static int shmem_readpage(struct file *file, struct page *page)
1677{
1678 struct inode *inode = page->mapping->host;
1679 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1680 unlock_page(page);
1681 return error;
1682}
1683
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684static int
Nick Piggin800d15a2007-10-16 01:25:03 -07001685shmem_write_begin(struct file *file, struct address_space *mapping,
1686 loff_t pos, unsigned len, unsigned flags,
1687 struct page **pagep, void **fsdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001688{
Nick Piggin800d15a2007-10-16 01:25:03 -07001689 struct inode *inode = mapping->host;
1690 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1691 *pagep = NULL;
1692 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1693}
1694
1695static int
1696shmem_write_end(struct file *file, struct address_space *mapping,
1697 loff_t pos, unsigned len, unsigned copied,
1698 struct page *page, void *fsdata)
1699{
1700 struct inode *inode = mapping->host;
1701
Hugh Dickinsd3602442008-02-04 22:28:44 -08001702 if (pos + copied > inode->i_size)
1703 i_size_write(inode, pos + copied);
1704
Nick Piggin800d15a2007-10-16 01:25:03 -07001705 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02001706 unlock_page(page);
Nick Piggin800d15a2007-10-16 01:25:03 -07001707 page_cache_release(page);
1708
Nick Piggin800d15a2007-10-16 01:25:03 -07001709 return copied;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710}
1711
Linus Torvalds1da177e2005-04-16 15:20:36 -07001712static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1713{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001714 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001715 struct address_space *mapping = inode->i_mapping;
1716 unsigned long index, offset;
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001717 enum sgp_type sgp = SGP_READ;
1718
1719 /*
1720 * Might this read be for a stacking filesystem? Then when reading
1721 * holes of a sparse file, we actually need to allocate those pages,
1722 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1723 */
1724 if (segment_eq(get_fs(), KERNEL_DS))
1725 sgp = SGP_DIRTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001726
1727 index = *ppos >> PAGE_CACHE_SHIFT;
1728 offset = *ppos & ~PAGE_CACHE_MASK;
1729
1730 for (;;) {
1731 struct page *page = NULL;
1732 unsigned long end_index, nr, ret;
1733 loff_t i_size = i_size_read(inode);
1734
1735 end_index = i_size >> PAGE_CACHE_SHIFT;
1736 if (index > end_index)
1737 break;
1738 if (index == end_index) {
1739 nr = i_size & ~PAGE_CACHE_MASK;
1740 if (nr <= offset)
1741 break;
1742 }
1743
Hugh Dickinsa0ee5ec2008-02-04 22:28:51 -08001744 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 if (desc->error) {
1746 if (desc->error == -EINVAL)
1747 desc->error = 0;
1748 break;
1749 }
Hugh Dickinsd3602442008-02-04 22:28:44 -08001750 if (page)
1751 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001752
1753 /*
1754 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001755 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001756 */
1757 nr = PAGE_CACHE_SIZE;
1758 i_size = i_size_read(inode);
1759 end_index = i_size >> PAGE_CACHE_SHIFT;
1760 if (index == end_index) {
1761 nr = i_size & ~PAGE_CACHE_MASK;
1762 if (nr <= offset) {
1763 if (page)
1764 page_cache_release(page);
1765 break;
1766 }
1767 }
1768 nr -= offset;
1769
1770 if (page) {
1771 /*
1772 * If users can be writing to this page using arbitrary
1773 * virtual addresses, take care about potential aliasing
1774 * before reading the page on the kernel side.
1775 */
1776 if (mapping_writably_mapped(mapping))
1777 flush_dcache_page(page);
1778 /*
1779 * Mark the page accessed if we read the beginning.
1780 */
1781 if (!offset)
1782 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001783 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001784 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001785 page_cache_get(page);
1786 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001787
1788 /*
1789 * Ok, we have the page, and it's up-to-date, so
1790 * now we can copy it to user space...
1791 *
1792 * The actor routine returns how many bytes were actually used..
1793 * NOTE! This may not be the same as how much of a user buffer
1794 * we filled up (we may be padding etc), so we can only update
1795 * "pos" here (the actor routine has to update the user buffer
1796 * pointers and the remaining count).
1797 */
1798 ret = actor(desc, page, offset, nr);
1799 offset += ret;
1800 index += offset >> PAGE_CACHE_SHIFT;
1801 offset &= ~PAGE_CACHE_MASK;
1802
1803 page_cache_release(page);
1804 if (ret != nr || !desc->count)
1805 break;
1806
1807 cond_resched();
1808 }
1809
1810 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1811 file_accessed(filp);
1812}
1813
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001814static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1815 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001816{
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001817 struct file *filp = iocb->ki_filp;
1818 ssize_t retval;
1819 unsigned long seg;
1820 size_t count;
1821 loff_t *ppos = &iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001822
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001823 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1824 if (retval)
1825 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001827 for (seg = 0; seg < nr_segs; seg++) {
1828 read_descriptor_t desc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001829
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07001830 desc.written = 0;
1831 desc.arg.buf = iov[seg].iov_base;
1832 desc.count = iov[seg].iov_len;
1833 if (desc.count == 0)
1834 continue;
1835 desc.error = 0;
1836 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1837 retval += desc.written;
1838 if (desc.error) {
1839 retval = retval ?: desc.error;
1840 break;
1841 }
1842 if (desc.count > 0)
1843 break;
1844 }
1845 return retval;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001846}
1847
David Howells726c3342006-06-23 02:02:58 -07001848static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849{
David Howells726c3342006-06-23 02:02:58 -07001850 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851
1852 buf->f_type = TMPFS_MAGIC;
1853 buf->f_bsize = PAGE_CACHE_SIZE;
1854 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001855 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856 buf->f_blocks = sbinfo->max_blocks;
Tim Chen7e496292010-08-09 17:19:05 -07001857 buf->f_bavail = buf->f_bfree =
1858 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001859 }
1860 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001861 buf->f_files = sbinfo->max_inodes;
1862 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863 }
1864 /* else leave those fields 0 like simple_statfs */
1865 return 0;
1866}
1867
1868/*
1869 * File creation. Allocate an inode, and we're done..
1870 */
1871static int
1872shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1873{
Hugh Dickins0b0a0802009-02-24 20:51:52 +00001874 struct inode *inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001875 int error = -ENOSPC;
1876
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03001877 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001878 if (inode) {
Eric Paris2a7dba32011-02-01 11:05:39 -05001879 error = security_inode_init_security(inode, dir,
1880 &dentry->d_name, NULL,
1881 NULL, NULL);
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001882 if (error) {
1883 if (error != -EOPNOTSUPP) {
1884 iput(inode);
1885 return error;
1886 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001887 }
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001888#ifdef CONFIG_TMPFS_POSIX_ACL
1889 error = generic_acl_init(inode, dir);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001890 if (error) {
1891 iput(inode);
1892 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001893 }
Al Viro718deb62009-12-16 19:35:36 -05001894#else
1895 error = 0;
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01001896#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07001897 dir->i_size += BOGO_DIRENT_SIZE;
1898 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1899 d_instantiate(dentry, inode);
1900 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901 }
1902 return error;
1903}
1904
1905static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1906{
1907 int error;
1908
1909 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1910 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001911 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001912 return 0;
1913}
1914
1915static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1916 struct nameidata *nd)
1917{
1918 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1919}
1920
1921/*
1922 * Link a file..
1923 */
1924static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1925{
1926 struct inode *inode = old_dentry->d_inode;
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001927 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001928
1929 /*
1930 * No ordinary (disk based) filesystem counts links as inodes;
1931 * but each new link needs a new dentry, pinning lowmem, and
1932 * tmpfs dentries cannot be pruned until they are unlinked.
1933 */
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001934 ret = shmem_reserve_inode(inode->i_sb);
1935 if (ret)
1936 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937
1938 dir->i_size += BOGO_DIRENT_SIZE;
1939 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001940 inc_nlink(inode);
Al Viro7de9c6e2010-10-23 11:11:40 -04001941 ihold(inode); /* New dentry reference */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001942 dget(dentry); /* Extra pinning count for the created dentry */
1943 d_instantiate(dentry, inode);
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001944out:
1945 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001946}
1947
1948static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1949{
1950 struct inode *inode = dentry->d_inode;
1951
Pavel Emelyanov5b04c682008-02-04 22:28:47 -08001952 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1953 shmem_free_inode(inode->i_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001954
1955 dir->i_size -= BOGO_DIRENT_SIZE;
1956 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001957 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001958 dput(dentry); /* Undo the count from "create" - this does all the work */
1959 return 0;
1960}
1961
1962static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1963{
1964 if (!simple_empty(dentry))
1965 return -ENOTEMPTY;
1966
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001967 drop_nlink(dentry->d_inode);
1968 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969 return shmem_unlink(dir, dentry);
1970}
1971
1972/*
1973 * The VFS layer already does all the dentry stuff for rename,
1974 * we just have to decrement the usage count for the target if
1975 * it exists so that the VFS layer correctly free's it when it
1976 * gets overwritten.
1977 */
1978static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1979{
1980 struct inode *inode = old_dentry->d_inode;
1981 int they_are_dirs = S_ISDIR(inode->i_mode);
1982
1983 if (!simple_empty(new_dentry))
1984 return -ENOTEMPTY;
1985
1986 if (new_dentry->d_inode) {
1987 (void) shmem_unlink(new_dir, new_dentry);
1988 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001989 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001990 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001991 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001992 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001993 }
1994
1995 old_dir->i_size -= BOGO_DIRENT_SIZE;
1996 new_dir->i_size += BOGO_DIRENT_SIZE;
1997 old_dir->i_ctime = old_dir->i_mtime =
1998 new_dir->i_ctime = new_dir->i_mtime =
1999 inode->i_ctime = CURRENT_TIME;
2000 return 0;
2001}
2002
2003static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
2004{
2005 int error;
2006 int len;
2007 struct inode *inode;
2008 struct page *page = NULL;
2009 char *kaddr;
2010 struct shmem_inode_info *info;
2011
2012 len = strlen(symname) + 1;
2013 if (len > PAGE_CACHE_SIZE)
2014 return -ENAMETOOLONG;
2015
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002016 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002017 if (!inode)
2018 return -ENOSPC;
2019
Eric Paris2a7dba32011-02-01 11:05:39 -05002020 error = security_inode_init_security(inode, dir, &dentry->d_name, NULL,
2021 NULL, NULL);
Stephen Smalley570bc1c2005-09-09 13:01:43 -07002022 if (error) {
2023 if (error != -EOPNOTSUPP) {
2024 iput(inode);
2025 return error;
2026 }
2027 error = 0;
2028 }
2029
Linus Torvalds1da177e2005-04-16 15:20:36 -07002030 info = SHMEM_I(inode);
2031 inode->i_size = len-1;
Eric Parisb09e0fa2011-05-24 17:12:39 -07002032 if (len <= SHMEM_SYMLINK_INLINE_LEN) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002033 /* do it inline */
Eric Parisb09e0fa2011-05-24 17:12:39 -07002034 memcpy(info->inline_symlink, symname, len);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002035 inode->i_op = &shmem_symlink_inline_operations;
2036 } else {
2037 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2038 if (error) {
2039 iput(inode);
2040 return error;
2041 }
Hugh Dickins14fcc232008-07-28 15:46:19 -07002042 inode->i_mapping->a_ops = &shmem_aops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002043 inode->i_op = &shmem_symlink_inode_operations;
2044 kaddr = kmap_atomic(page, KM_USER0);
2045 memcpy(kaddr, symname, len);
2046 kunmap_atomic(kaddr, KM_USER0);
2047 set_page_dirty(page);
Wu Fengguang6746aff2009-09-16 11:50:14 +02002048 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049 page_cache_release(page);
2050 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002051 dir->i_size += BOGO_DIRENT_SIZE;
2052 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2053 d_instantiate(dentry, inode);
2054 dget(dentry);
2055 return 0;
2056}
2057
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002058static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002059{
Eric Parisb09e0fa2011-05-24 17:12:39 -07002060 nd_set_link(nd, SHMEM_I(dentry->d_inode)->inline_symlink);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002061 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002062}
2063
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002064static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002065{
2066 struct page *page = NULL;
2067 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2068 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Hugh Dickinsd3602442008-02-04 22:28:44 -08002069 if (page)
2070 unlock_page(page);
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002071 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002072}
2073
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002074static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002075{
2076 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07002077 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002078 kunmap(page);
2079 mark_page_accessed(page);
2080 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081 }
2082}
2083
Eric Parisb09e0fa2011-05-24 17:12:39 -07002084#ifdef CONFIG_TMPFS_XATTR
2085/*
2086 * Superblocks without xattr inode operations may get some security.* xattr
2087 * support from the LSM "for free". As soon as we have any other xattrs
2088 * like ACLs, we also need to implement the security.* handlers at
2089 * filesystem level, though.
2090 */
2091
2092static int shmem_xattr_get(struct dentry *dentry, const char *name,
2093 void *buffer, size_t size)
2094{
2095 struct shmem_inode_info *info;
2096 struct shmem_xattr *xattr;
2097 int ret = -ENODATA;
2098
2099 info = SHMEM_I(dentry->d_inode);
2100
2101 spin_lock(&info->lock);
2102 list_for_each_entry(xattr, &info->xattr_list, list) {
2103 if (strcmp(name, xattr->name))
2104 continue;
2105
2106 ret = xattr->size;
2107 if (buffer) {
2108 if (size < xattr->size)
2109 ret = -ERANGE;
2110 else
2111 memcpy(buffer, xattr->value, xattr->size);
2112 }
2113 break;
2114 }
2115 spin_unlock(&info->lock);
2116 return ret;
2117}
2118
2119static int shmem_xattr_set(struct dentry *dentry, const char *name,
2120 const void *value, size_t size, int flags)
2121{
2122 struct inode *inode = dentry->d_inode;
2123 struct shmem_inode_info *info = SHMEM_I(inode);
2124 struct shmem_xattr *xattr;
2125 struct shmem_xattr *new_xattr = NULL;
2126 size_t len;
2127 int err = 0;
2128
2129 /* value == NULL means remove */
2130 if (value) {
2131 /* wrap around? */
2132 len = sizeof(*new_xattr) + size;
2133 if (len <= sizeof(*new_xattr))
2134 return -ENOMEM;
2135
2136 new_xattr = kmalloc(len, GFP_KERNEL);
2137 if (!new_xattr)
2138 return -ENOMEM;
2139
2140 new_xattr->name = kstrdup(name, GFP_KERNEL);
2141 if (!new_xattr->name) {
2142 kfree(new_xattr);
2143 return -ENOMEM;
2144 }
2145
2146 new_xattr->size = size;
2147 memcpy(new_xattr->value, value, size);
2148 }
2149
2150 spin_lock(&info->lock);
2151 list_for_each_entry(xattr, &info->xattr_list, list) {
2152 if (!strcmp(name, xattr->name)) {
2153 if (flags & XATTR_CREATE) {
2154 xattr = new_xattr;
2155 err = -EEXIST;
2156 } else if (new_xattr) {
2157 list_replace(&xattr->list, &new_xattr->list);
2158 } else {
2159 list_del(&xattr->list);
2160 }
2161 goto out;
2162 }
2163 }
2164 if (flags & XATTR_REPLACE) {
2165 xattr = new_xattr;
2166 err = -ENODATA;
2167 } else {
2168 list_add(&new_xattr->list, &info->xattr_list);
2169 xattr = NULL;
2170 }
2171out:
2172 spin_unlock(&info->lock);
2173 if (xattr)
2174 kfree(xattr->name);
2175 kfree(xattr);
2176 return err;
2177}
2178
2179
2180static const struct xattr_handler *shmem_xattr_handlers[] = {
2181#ifdef CONFIG_TMPFS_POSIX_ACL
2182 &generic_acl_access_handler,
2183 &generic_acl_default_handler,
2184#endif
2185 NULL
2186};
2187
2188static int shmem_xattr_validate(const char *name)
2189{
2190 struct { const char *prefix; size_t len; } arr[] = {
2191 { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
2192 { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
2193 };
2194 int i;
2195
2196 for (i = 0; i < ARRAY_SIZE(arr); i++) {
2197 size_t preflen = arr[i].len;
2198 if (strncmp(name, arr[i].prefix, preflen) == 0) {
2199 if (!name[preflen])
2200 return -EINVAL;
2201 return 0;
2202 }
2203 }
2204 return -EOPNOTSUPP;
2205}
2206
2207static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
2208 void *buffer, size_t size)
2209{
2210 int err;
2211
2212 /*
2213 * If this is a request for a synthetic attribute in the system.*
2214 * namespace use the generic infrastructure to resolve a handler
2215 * for it via sb->s_xattr.
2216 */
2217 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2218 return generic_getxattr(dentry, name, buffer, size);
2219
2220 err = shmem_xattr_validate(name);
2221 if (err)
2222 return err;
2223
2224 return shmem_xattr_get(dentry, name, buffer, size);
2225}
2226
2227static int shmem_setxattr(struct dentry *dentry, const char *name,
2228 const void *value, size_t size, int flags)
2229{
2230 int err;
2231
2232 /*
2233 * If this is a request for a synthetic attribute in the system.*
2234 * namespace use the generic infrastructure to resolve a handler
2235 * for it via sb->s_xattr.
2236 */
2237 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2238 return generic_setxattr(dentry, name, value, size, flags);
2239
2240 err = shmem_xattr_validate(name);
2241 if (err)
2242 return err;
2243
2244 if (size == 0)
2245 value = ""; /* empty EA, do not remove */
2246
2247 return shmem_xattr_set(dentry, name, value, size, flags);
2248
2249}
2250
2251static int shmem_removexattr(struct dentry *dentry, const char *name)
2252{
2253 int err;
2254
2255 /*
2256 * If this is a request for a synthetic attribute in the system.*
2257 * namespace use the generic infrastructure to resolve a handler
2258 * for it via sb->s_xattr.
2259 */
2260 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2261 return generic_removexattr(dentry, name);
2262
2263 err = shmem_xattr_validate(name);
2264 if (err)
2265 return err;
2266
2267 return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
2268}
2269
2270static bool xattr_is_trusted(const char *name)
2271{
2272 return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
2273}
2274
2275static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
2276{
2277 bool trusted = capable(CAP_SYS_ADMIN);
2278 struct shmem_xattr *xattr;
2279 struct shmem_inode_info *info;
2280 size_t used = 0;
2281
2282 info = SHMEM_I(dentry->d_inode);
2283
2284 spin_lock(&info->lock);
2285 list_for_each_entry(xattr, &info->xattr_list, list) {
2286 size_t len;
2287
2288 /* skip "trusted." attributes for unprivileged callers */
2289 if (!trusted && xattr_is_trusted(xattr->name))
2290 continue;
2291
2292 len = strlen(xattr->name) + 1;
2293 used += len;
2294 if (buffer) {
2295 if (size < used) {
2296 used = -ERANGE;
2297 break;
2298 }
2299 memcpy(buffer, xattr->name, len);
2300 buffer += len;
2301 }
2302 }
2303 spin_unlock(&info->lock);
2304
2305 return used;
2306}
2307#endif /* CONFIG_TMPFS_XATTR */
2308
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002309static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002310 .readlink = generic_readlink,
2311 .follow_link = shmem_follow_link_inline,
Eric Parisb09e0fa2011-05-24 17:12:39 -07002312#ifdef CONFIG_TMPFS_XATTR
2313 .setxattr = shmem_setxattr,
2314 .getxattr = shmem_getxattr,
2315 .listxattr = shmem_listxattr,
2316 .removexattr = shmem_removexattr,
2317#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318};
2319
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002320static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002321 .readlink = generic_readlink,
2322 .follow_link = shmem_follow_link,
2323 .put_link = shmem_put_link,
Eric Parisb09e0fa2011-05-24 17:12:39 -07002324#ifdef CONFIG_TMPFS_XATTR
2325 .setxattr = shmem_setxattr,
2326 .getxattr = shmem_getxattr,
2327 .listxattr = shmem_listxattr,
2328 .removexattr = shmem_removexattr,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002329#endif
Eric Parisb09e0fa2011-05-24 17:12:39 -07002330};
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002331
David M. Grimes91828a42006-10-17 00:09:45 -07002332static struct dentry *shmem_get_parent(struct dentry *child)
2333{
2334 return ERR_PTR(-ESTALE);
2335}
2336
2337static int shmem_match(struct inode *ino, void *vfh)
2338{
2339 __u32 *fh = vfh;
2340 __u64 inum = fh[2];
2341 inum = (inum << 32) | fh[1];
2342 return ino->i_ino == inum && fh[0] == ino->i_generation;
2343}
2344
Christoph Hellwig480b1162007-10-21 16:42:13 -07002345static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2346 struct fid *fid, int fh_len, int fh_type)
David M. Grimes91828a42006-10-17 00:09:45 -07002347{
David M. Grimes91828a42006-10-17 00:09:45 -07002348 struct inode *inode;
Christoph Hellwig480b1162007-10-21 16:42:13 -07002349 struct dentry *dentry = NULL;
2350 u64 inum = fid->raw[2];
2351 inum = (inum << 32) | fid->raw[1];
David M. Grimes91828a42006-10-17 00:09:45 -07002352
Christoph Hellwig480b1162007-10-21 16:42:13 -07002353 if (fh_len < 3)
2354 return NULL;
2355
2356 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2357 shmem_match, fid->raw);
David M. Grimes91828a42006-10-17 00:09:45 -07002358 if (inode) {
Christoph Hellwig480b1162007-10-21 16:42:13 -07002359 dentry = d_find_alias(inode);
David M. Grimes91828a42006-10-17 00:09:45 -07002360 iput(inode);
2361 }
2362
Christoph Hellwig480b1162007-10-21 16:42:13 -07002363 return dentry;
David M. Grimes91828a42006-10-17 00:09:45 -07002364}
2365
2366static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2367 int connectable)
2368{
2369 struct inode *inode = dentry->d_inode;
2370
Aneesh Kumar K.V5fe0c232011-01-29 18:43:25 +05302371 if (*len < 3) {
2372 *len = 3;
David M. Grimes91828a42006-10-17 00:09:45 -07002373 return 255;
Aneesh Kumar K.V5fe0c232011-01-29 18:43:25 +05302374 }
David M. Grimes91828a42006-10-17 00:09:45 -07002375
Al Viro1d3382c2010-10-23 15:19:20 -04002376 if (inode_unhashed(inode)) {
David M. Grimes91828a42006-10-17 00:09:45 -07002377 /* Unfortunately insert_inode_hash is not idempotent,
2378 * so as we hash inodes here rather than at creation
2379 * time, we need a lock to ensure we only try
2380 * to do it once
2381 */
2382 static DEFINE_SPINLOCK(lock);
2383 spin_lock(&lock);
Al Viro1d3382c2010-10-23 15:19:20 -04002384 if (inode_unhashed(inode))
David M. Grimes91828a42006-10-17 00:09:45 -07002385 __insert_inode_hash(inode,
2386 inode->i_ino + inode->i_generation);
2387 spin_unlock(&lock);
2388 }
2389
2390 fh[0] = inode->i_generation;
2391 fh[1] = inode->i_ino;
2392 fh[2] = ((__u64)inode->i_ino) >> 32;
2393
2394 *len = 3;
2395 return 1;
2396}
2397
Christoph Hellwig39655162007-10-21 16:42:17 -07002398static const struct export_operations shmem_export_ops = {
David M. Grimes91828a42006-10-17 00:09:45 -07002399 .get_parent = shmem_get_parent,
David M. Grimes91828a42006-10-17 00:09:45 -07002400 .encode_fh = shmem_encode_fh,
Christoph Hellwig480b1162007-10-21 16:42:13 -07002401 .fh_to_dentry = shmem_fh_to_dentry,
David M. Grimes91828a42006-10-17 00:09:45 -07002402};
2403
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002404static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2405 bool remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002406{
2407 char *this_char, *value, *rest;
2408
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002409 while (options != NULL) {
2410 this_char = options;
2411 for (;;) {
2412 /*
2413 * NUL-terminate this option: unfortunately,
2414 * mount options form a comma-separated list,
2415 * but mpol's nodelist may also contain commas.
2416 */
2417 options = strchr(options, ',');
2418 if (options == NULL)
2419 break;
2420 options++;
2421 if (!isdigit(*options)) {
2422 options[-1] = '\0';
2423 break;
2424 }
2425 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002426 if (!*this_char)
2427 continue;
2428 if ((value = strchr(this_char,'=')) != NULL) {
2429 *value++ = 0;
2430 } else {
2431 printk(KERN_ERR
2432 "tmpfs: No value for mount option '%s'\n",
2433 this_char);
2434 return 1;
2435 }
2436
2437 if (!strcmp(this_char,"size")) {
2438 unsigned long long size;
2439 size = memparse(value,&rest);
2440 if (*rest == '%') {
2441 size <<= PAGE_SHIFT;
2442 size *= totalram_pages;
2443 do_div(size, 100);
2444 rest++;
2445 }
2446 if (*rest)
2447 goto bad_val;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002448 sbinfo->max_blocks =
2449 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450 } else if (!strcmp(this_char,"nr_blocks")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002451 sbinfo->max_blocks = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002452 if (*rest)
2453 goto bad_val;
2454 } else if (!strcmp(this_char,"nr_inodes")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002455 sbinfo->max_inodes = memparse(value, &rest);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002456 if (*rest)
2457 goto bad_val;
2458 } else if (!strcmp(this_char,"mode")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002459 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002460 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002461 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002462 if (*rest)
2463 goto bad_val;
2464 } else if (!strcmp(this_char,"uid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002465 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002466 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002467 sbinfo->uid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002468 if (*rest)
2469 goto bad_val;
2470 } else if (!strcmp(this_char,"gid")) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002471 if (remount)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002472 continue;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002473 sbinfo->gid = simple_strtoul(value, &rest, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002474 if (*rest)
2475 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002476 } else if (!strcmp(this_char,"mpol")) {
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002477 if (mpol_parse_str(value, &sbinfo->mpol, 1))
Robin Holt7339ff82006-01-14 13:20:48 -08002478 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002479 } else {
2480 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2481 this_char);
2482 return 1;
2483 }
2484 }
2485 return 0;
2486
2487bad_val:
2488 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2489 value, this_char);
2490 return 1;
2491
2492}
2493
2494static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2495{
2496 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002497 struct shmem_sb_info config = *sbinfo;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002498 unsigned long inodes;
2499 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002501 if (shmem_parse_options(data, &config, true))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002502 return error;
2503
2504 spin_lock(&sbinfo->stat_lock);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002505 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
Tim Chen7e496292010-08-09 17:19:05 -07002506 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002507 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002508 if (config.max_inodes < inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002509 goto out;
2510 /*
2511 * Those tests also disallow limited->unlimited while any are in
2512 * use, so i_blocks will always be zero when max_blocks is zero;
2513 * but we must separately disallow unlimited->limited, because
2514 * in that case we have no record of how much is already in use.
2515 */
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002516 if (config.max_blocks && !sbinfo->max_blocks)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002517 goto out;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002518 if (config.max_inodes && !sbinfo->max_inodes)
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002519 goto out;
2520
2521 error = 0;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002522 sbinfo->max_blocks = config.max_blocks;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002523 sbinfo->max_inodes = config.max_inodes;
2524 sbinfo->free_inodes = config.max_inodes - inodes;
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002525
2526 mpol_put(sbinfo->mpol);
2527 sbinfo->mpol = config.mpol; /* transfers initial ref */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002528out:
2529 spin_unlock(&sbinfo->stat_lock);
2530 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002531}
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002532
2533static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2534{
2535 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2536
2537 if (sbinfo->max_blocks != shmem_default_max_blocks())
2538 seq_printf(seq, ",size=%luk",
2539 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2540 if (sbinfo->max_inodes != shmem_default_max_inodes())
2541 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2542 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2543 seq_printf(seq, ",mode=%03o", sbinfo->mode);
2544 if (sbinfo->uid != 0)
2545 seq_printf(seq, ",uid=%u", sbinfo->uid);
2546 if (sbinfo->gid != 0)
2547 seq_printf(seq, ",gid=%u", sbinfo->gid);
Lee Schermerhorn71fe8042008-04-28 02:13:26 -07002548 shmem_show_mpol(seq, sbinfo->mpol);
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002549 return 0;
2550}
2551#endif /* CONFIG_TMPFS */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002552
2553static void shmem_put_super(struct super_block *sb)
2554{
Hugh Dickins602586a2010-08-17 15:23:56 -07002555 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2556
2557 percpu_counter_destroy(&sbinfo->used_blocks);
2558 kfree(sbinfo);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002559 sb->s_fs_info = NULL;
2560}
2561
Kay Sievers2b2af542009-04-30 15:23:42 +02002562int shmem_fill_super(struct super_block *sb, void *data, int silent)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002563{
2564 struct inode *inode;
2565 struct dentry *root;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002566 struct shmem_sb_info *sbinfo;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002567 int err = -ENOMEM;
2568
2569 /* Round up to L1_CACHE_BYTES to resist false sharing */
Pekka Enberg425fbf02009-09-21 17:03:50 -07002570 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002571 L1_CACHE_BYTES), GFP_KERNEL);
2572 if (!sbinfo)
2573 return -ENOMEM;
2574
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002575 sbinfo->mode = S_IRWXUGO | S_ISVTX;
David Howells76aac0e2008-11-14 10:39:12 +11002576 sbinfo->uid = current_fsuid();
2577 sbinfo->gid = current_fsgid();
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002578 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002579
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002580#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581 /*
2582 * Per default we only allow half of the physical ram per
2583 * tmpfs instance, limiting inodes to one per page of lowmem;
2584 * but the internal instance is left unlimited.
2585 */
2586 if (!(sb->s_flags & MS_NOUSER)) {
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002587 sbinfo->max_blocks = shmem_default_max_blocks();
2588 sbinfo->max_inodes = shmem_default_max_inodes();
2589 if (shmem_parse_options(data, sbinfo, false)) {
2590 err = -EINVAL;
2591 goto failed;
2592 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002593 }
David M. Grimes91828a42006-10-17 00:09:45 -07002594 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595#else
2596 sb->s_flags |= MS_NOUSER;
2597#endif
2598
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002599 spin_lock_init(&sbinfo->stat_lock);
Hugh Dickins602586a2010-08-17 15:23:56 -07002600 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2601 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002602 sbinfo->free_inodes = sbinfo->max_inodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002603
Linus Torvalds1da177e2005-04-16 15:20:36 -07002604 sb->s_maxbytes = SHMEM_MAX_BYTES;
2605 sb->s_blocksize = PAGE_CACHE_SIZE;
2606 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2607 sb->s_magic = TMPFS_MAGIC;
2608 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002609 sb->s_time_gran = 1;
Eric Parisb09e0fa2011-05-24 17:12:39 -07002610#ifdef CONFIG_TMPFS_XATTR
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002611 sb->s_xattr = shmem_xattr_handlers;
Eric Parisb09e0fa2011-05-24 17:12:39 -07002612#endif
2613#ifdef CONFIG_TMPFS_POSIX_ACL
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002614 sb->s_flags |= MS_POSIXACL;
2615#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002616
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002617 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002618 if (!inode)
2619 goto failed;
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002620 inode->i_uid = sbinfo->uid;
2621 inode->i_gid = sbinfo->gid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002622 root = d_alloc_root(inode);
2623 if (!root)
2624 goto failed_iput;
2625 sb->s_root = root;
2626 return 0;
2627
2628failed_iput:
2629 iput(inode);
2630failed:
2631 shmem_put_super(sb);
2632 return err;
2633}
2634
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002635static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636
2637static struct inode *shmem_alloc_inode(struct super_block *sb)
2638{
2639 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002640 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002641 if (!p)
2642 return NULL;
2643 return &p->vfs_inode;
2644}
2645
Nick Pigginfa0d7e32011-01-07 17:49:49 +11002646static void shmem_i_callback(struct rcu_head *head)
2647{
2648 struct inode *inode = container_of(head, struct inode, i_rcu);
2649 INIT_LIST_HEAD(&inode->i_dentry);
2650 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2651}
2652
Linus Torvalds1da177e2005-04-16 15:20:36 -07002653static void shmem_destroy_inode(struct inode *inode)
2654{
2655 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2656 /* only struct inode is valid if it's an inline symlink */
2657 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2658 }
Nick Pigginfa0d7e32011-01-07 17:49:49 +11002659 call_rcu(&inode->i_rcu, shmem_i_callback);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002660}
2661
Alexey Dobriyan51cc5062008-07-25 19:45:34 -07002662static void init_once(void *foo)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663{
2664 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2665
Christoph Lametera35afb82007-05-16 22:10:57 -07002666 inode_init_once(&p->vfs_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002667}
2668
2669static int init_inodecache(void)
2670{
2671 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2672 sizeof(struct shmem_inode_info),
Alexey Dobriyan040b5c62007-10-16 23:26:10 -07002673 0, SLAB_PANIC, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002674 return 0;
2675}
2676
2677static void destroy_inodecache(void)
2678{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002679 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002680}
2681
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002682static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002683 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002684 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002685#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002686 .readpage = shmem_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -07002687 .write_begin = shmem_write_begin,
2688 .write_end = shmem_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002689#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002690 .migratepage = migrate_page,
Andi Kleenaa261f52009-09-16 11:50:16 +02002691 .error_remove_page = generic_error_remove_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002692};
2693
Helge Deller15ad7cd2006-12-06 20:40:36 -08002694static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002695 .mmap = shmem_mmap,
2696#ifdef CONFIG_TMPFS
2697 .llseek = generic_file_llseek,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002698 .read = do_sync_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002699 .write = do_sync_write,
Hugh Dickinsbcd78e42008-07-23 21:27:35 -07002700 .aio_read = shmem_file_aio_read,
Hugh Dickins5402b972008-02-04 22:28:44 -08002701 .aio_write = generic_file_aio_write,
Christoph Hellwig1b061d92010-05-26 17:53:41 +02002702 .fsync = noop_fsync,
Hugh Dickinsae976412007-06-04 10:00:39 +02002703 .splice_read = generic_file_splice_read,
2704 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002705#endif
2706};
2707
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002708static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002709 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002710 .truncate_range = shmem_truncate_range,
Eric Parisb09e0fa2011-05-24 17:12:39 -07002711#ifdef CONFIG_TMPFS_XATTR
2712 .setxattr = shmem_setxattr,
2713 .getxattr = shmem_getxattr,
2714 .listxattr = shmem_listxattr,
2715 .removexattr = shmem_removexattr,
2716#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002717#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002718 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002719#endif
2720
Linus Torvalds1da177e2005-04-16 15:20:36 -07002721};
2722
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002723static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002724#ifdef CONFIG_TMPFS
2725 .create = shmem_create,
2726 .lookup = simple_lookup,
2727 .link = shmem_link,
2728 .unlink = shmem_unlink,
2729 .symlink = shmem_symlink,
2730 .mkdir = shmem_mkdir,
2731 .rmdir = shmem_rmdir,
2732 .mknod = shmem_mknod,
2733 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002734#endif
Eric Parisb09e0fa2011-05-24 17:12:39 -07002735#ifdef CONFIG_TMPFS_XATTR
2736 .setxattr = shmem_setxattr,
2737 .getxattr = shmem_getxattr,
2738 .listxattr = shmem_listxattr,
2739 .removexattr = shmem_removexattr,
2740#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002741#ifdef CONFIG_TMPFS_POSIX_ACL
2742 .setattr = shmem_notify_change,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002743 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002744#endif
2745};
2746
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002747static const struct inode_operations shmem_special_inode_operations = {
Eric Parisb09e0fa2011-05-24 17:12:39 -07002748#ifdef CONFIG_TMPFS_XATTR
2749 .setxattr = shmem_setxattr,
2750 .getxattr = shmem_getxattr,
2751 .listxattr = shmem_listxattr,
2752 .removexattr = shmem_removexattr,
2753#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002754#ifdef CONFIG_TMPFS_POSIX_ACL
2755 .setattr = shmem_notify_change,
Christoph Hellwig1c7c4742009-11-03 16:44:44 +01002756 .check_acl = generic_check_acl,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002757#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002758};
2759
Hugh Dickins759b9772007-03-05 00:30:28 -08002760static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002761 .alloc_inode = shmem_alloc_inode,
2762 .destroy_inode = shmem_destroy_inode,
2763#ifdef CONFIG_TMPFS
2764 .statfs = shmem_statfs,
2765 .remount_fs = shmem_remount_fs,
akpm@linux-foundation.org680d7942008-02-08 04:21:48 -08002766 .show_options = shmem_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767#endif
Al Viro1f895f72010-06-05 19:10:41 -04002768 .evict_inode = shmem_evict_inode,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002769 .drop_inode = generic_delete_inode,
2770 .put_super = shmem_put_super,
2771};
2772
Alexey Dobriyanf0f37e22009-09-27 22:29:37 +04002773static const struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002774 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775#ifdef CONFIG_NUMA
2776 .set_policy = shmem_set_policy,
2777 .get_policy = shmem_get_policy,
2778#endif
2779};
2780
2781
Al Viro3c26ff62010-07-25 11:46:36 +04002782static struct dentry *shmem_mount(struct file_system_type *fs_type,
2783 int flags, const char *dev_name, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002784{
Al Viro3c26ff62010-07-25 11:46:36 +04002785 return mount_nodev(fs_type, flags, data, shmem_fill_super);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002786}
2787
2788static struct file_system_type tmpfs_fs_type = {
2789 .owner = THIS_MODULE,
2790 .name = "tmpfs",
Al Viro3c26ff62010-07-25 11:46:36 +04002791 .mount = shmem_mount,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792 .kill_sb = kill_litter_super,
2793};
Linus Torvalds1da177e2005-04-16 15:20:36 -07002794
Kay Sievers2b2af542009-04-30 15:23:42 +02002795int __init init_tmpfs(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002796{
2797 int error;
2798
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002799 error = bdi_init(&shmem_backing_dev_info);
2800 if (error)
2801 goto out4;
2802
Linus Torvalds1da177e2005-04-16 15:20:36 -07002803 error = init_inodecache();
2804 if (error)
2805 goto out3;
2806
2807 error = register_filesystem(&tmpfs_fs_type);
2808 if (error) {
2809 printk(KERN_ERR "Could not register tmpfs\n");
2810 goto out2;
2811 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002812
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002813 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002814 tmpfs_fs_type.name, NULL);
2815 if (IS_ERR(shm_mnt)) {
2816 error = PTR_ERR(shm_mnt);
2817 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2818 goto out1;
2819 }
2820 return 0;
2821
2822out1:
2823 unregister_filesystem(&tmpfs_fs_type);
2824out2:
2825 destroy_inodecache();
2826out3:
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -07002827 bdi_destroy(&shmem_backing_dev_info);
2828out4:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002829 shm_mnt = ERR_PTR(error);
2830 return error;
2831}
Matt Mackall853ac432009-01-06 14:40:20 -08002832
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002833#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2834/**
2835 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2836 * @inode: the inode to be searched
2837 * @pgoff: the offset to be searched
2838 * @pagep: the pointer for the found page to be stored
2839 * @ent: the pointer for the found swap entry to be stored
2840 *
2841 * If a page is found, refcount of it is incremented. Callers should handle
2842 * these refcount.
2843 */
2844void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2845 struct page **pagep, swp_entry_t *ent)
2846{
2847 swp_entry_t entry = { .val = 0 }, *ptr;
2848 struct page *page = NULL;
2849 struct shmem_inode_info *info = SHMEM_I(inode);
2850
2851 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2852 goto out;
2853
2854 spin_lock(&info->lock);
2855 ptr = shmem_swp_entry(info, pgoff, NULL);
2856#ifdef CONFIG_SWAP
2857 if (ptr && ptr->val) {
2858 entry.val = ptr->val;
2859 page = find_get_page(&swapper_space, entry.val);
2860 } else
2861#endif
2862 page = find_get_page(inode->i_mapping, pgoff);
2863 if (ptr)
2864 shmem_swp_unmap(ptr);
2865 spin_unlock(&info->lock);
2866out:
2867 *pagep = page;
2868 *ent = entry;
2869}
2870#endif
2871
Matt Mackall853ac432009-01-06 14:40:20 -08002872#else /* !CONFIG_SHMEM */
2873
2874/*
2875 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2876 *
2877 * This is intended for small system where the benefits of the full
2878 * shmem code (swap-backed and resource-limited) are outweighed by
2879 * their complexity. On systems without swap this code should be
2880 * effectively equivalent, but much lighter weight.
2881 */
2882
2883#include <linux/ramfs.h>
2884
2885static struct file_system_type tmpfs_fs_type = {
2886 .name = "tmpfs",
Al Viro3c26ff62010-07-25 11:46:36 +04002887 .mount = ramfs_mount,
Matt Mackall853ac432009-01-06 14:40:20 -08002888 .kill_sb = kill_litter_super,
2889};
2890
Kay Sievers2b2af542009-04-30 15:23:42 +02002891int __init init_tmpfs(void)
Matt Mackall853ac432009-01-06 14:40:20 -08002892{
2893 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
2894
2895 shm_mnt = kern_mount(&tmpfs_fs_type);
2896 BUG_ON(IS_ERR(shm_mnt));
2897
2898 return 0;
2899}
2900
2901int shmem_unuse(swp_entry_t entry, struct page *page)
2902{
2903 return 0;
2904}
2905
Hugh Dickins3f96b792009-09-21 17:03:37 -07002906int shmem_lock(struct file *file, int lock, struct user_struct *user)
2907{
2908 return 0;
2909}
2910
Daisuke Nishimura87946a72010-05-26 14:42:39 -07002911#ifdef CONFIG_CGROUP_MEM_RES_CTLR
2912/**
2913 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file
2914 * @inode: the inode to be searched
2915 * @pgoff: the offset to be searched
2916 * @pagep: the pointer for the found page to be stored
2917 * @ent: the pointer for the found swap entry to be stored
2918 *
2919 * If a page is found, refcount of it is incremented. Callers should handle
2920 * these refcount.
2921 */
2922void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff,
2923 struct page **pagep, swp_entry_t *ent)
2924{
2925 struct page *page = NULL;
2926
2927 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
2928 goto out;
2929 page = find_get_page(inode->i_mapping, pgoff);
2930out:
2931 *pagep = page;
2932 *ent = (swp_entry_t){ .val = 0 };
2933}
2934#endif
2935
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002936#define shmem_vm_ops generic_file_vm_ops
2937#define shmem_file_operations ramfs_file_operations
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002938#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002939#define shmem_acct_size(flags, size) 0
2940#define shmem_unacct_size(flags, size) do {} while (0)
Hugh Dickinscaefba12009-04-13 14:40:12 -07002941#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
Matt Mackall853ac432009-01-06 14:40:20 -08002942
2943#endif /* CONFIG_SHMEM */
2944
2945/* common code */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002946
Randy Dunlap46711812008-03-19 17:00:41 -07002947/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07002948 * shmem_file_setup - get an unlinked file living in tmpfs
Linus Torvalds1da177e2005-04-16 15:20:36 -07002949 * @name: name for dentry (to be seen in /proc/<pid>/maps
2950 * @size: size to be set for the file
Hugh Dickins0b0a0802009-02-24 20:51:52 +00002951 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
Linus Torvalds1da177e2005-04-16 15:20:36 -07002952 */
Sergei Trofimovich168f5ac2009-06-16 15:33:02 -07002953struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002954{
2955 int error;
2956 struct file *file;
2957 struct inode *inode;
Al Viro2c48b9c2009-08-09 00:52:35 +04002958 struct path path;
2959 struct dentry *root;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002960 struct qstr this;
2961
2962 if (IS_ERR(shm_mnt))
2963 return (void *)shm_mnt;
2964
2965 if (size < 0 || size > SHMEM_MAX_BYTES)
2966 return ERR_PTR(-EINVAL);
2967
2968 if (shmem_acct_size(flags, size))
2969 return ERR_PTR(-ENOMEM);
2970
2971 error = -ENOMEM;
2972 this.name = name;
2973 this.len = strlen(name);
2974 this.hash = 0; /* will go */
2975 root = shm_mnt->mnt_root;
Al Viro2c48b9c2009-08-09 00:52:35 +04002976 path.dentry = d_alloc(root, &this);
2977 if (!path.dentry)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002978 goto put_memory;
Al Viro2c48b9c2009-08-09 00:52:35 +04002979 path.mnt = mntget(shm_mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002980
Linus Torvalds1da177e2005-04-16 15:20:36 -07002981 error = -ENOSPC;
Dmitry Monakhov454abaf2010-03-04 17:32:18 +03002982 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002983 if (!inode)
Al Viro4b42af82009-08-05 18:25:56 +04002984 goto put_dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002985
Al Viro2c48b9c2009-08-09 00:52:35 +04002986 d_instantiate(path.dentry, inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002987 inode->i_size = size;
2988 inode->i_nlink = 0; /* It is unlinked */
Matt Mackall853ac432009-01-06 14:40:20 -08002989#ifndef CONFIG_MMU
2990 error = ramfs_nommu_expand_for_mapping(inode, size);
2991 if (error)
Al Viro4b42af82009-08-05 18:25:56 +04002992 goto put_dentry;
Matt Mackall853ac432009-01-06 14:40:20 -08002993#endif
Al Viro4b42af82009-08-05 18:25:56 +04002994
2995 error = -ENFILE;
Al Viro2c48b9c2009-08-09 00:52:35 +04002996 file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
Al Viro4b42af82009-08-05 18:25:56 +04002997 &shmem_file_operations);
2998 if (!file)
2999 goto put_dentry;
3000
Linus Torvalds1da177e2005-04-16 15:20:36 -07003001 return file;
3002
Linus Torvalds1da177e2005-04-16 15:20:36 -07003003put_dentry:
Al Viro2c48b9c2009-08-09 00:52:35 +04003004 path_put(&path);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003005put_memory:
3006 shmem_unacct_size(flags, size);
3007 return ERR_PTR(error);
3008}
Keith Packard395e0dd2008-06-20 00:08:06 -07003009EXPORT_SYMBOL_GPL(shmem_file_setup);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003010
Randy Dunlap46711812008-03-19 17:00:41 -07003011/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07003012 * shmem_zero_setup - setup a shared anonymous mapping
Linus Torvalds1da177e2005-04-16 15:20:36 -07003013 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
3014 */
3015int shmem_zero_setup(struct vm_area_struct *vma)
3016{
3017 struct file *file;
3018 loff_t size = vma->vm_end - vma->vm_start;
3019
3020 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
3021 if (IS_ERR(file))
3022 return PTR_ERR(file);
3023
3024 if (vma->vm_file)
3025 fput(vma->vm_file);
3026 vma->vm_file = file;
3027 vma->vm_ops = &shmem_vm_ops;
Hugh Dickinsbee4c362011-03-22 16:33:43 -07003028 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003029 return 0;
3030}