blob: 96fa79fb6ad37d483b816ec92804ecd2dfe0a825 [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 *
17 * This file is released under the GPL.
18 */
19
20/*
21 * This virtual memory filesystem is heavily based on the ramfs. It
22 * extends ramfs by the ability to use swap and honor resource limits
23 * which makes it a completely usable filesystem.
24 */
25
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/module.h>
27#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/fs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070029#include <linux/xattr.h>
Christoph Hellwiga5694252007-07-17 04:04:28 -070030#include <linux/exportfs.h>
Andreas Gruenbacher39f02472006-09-29 02:01:35 -070031#include <linux/generic_acl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/mm.h>
33#include <linux/mman.h>
34#include <linux/file.h>
35#include <linux/swap.h>
36#include <linux/pagemap.h>
37#include <linux/string.h>
38#include <linux/slab.h>
39#include <linux/backing-dev.h>
40#include <linux/shmem_fs.h>
41#include <linux/mount.h>
42#include <linux/writeback.h>
43#include <linux/vfs.h>
44#include <linux/blkdev.h>
45#include <linux/security.h>
46#include <linux/swapops.h>
47#include <linux/mempolicy.h>
48#include <linux/namei.h>
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +000049#include <linux/ctype.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070050#include <linux/migrate.h>
Christoph Lameterc1f60a52006-09-25 23:31:11 -070051#include <linux/highmem.h>
Andrew Morton3fcfab12006-10-19 23:28:16 -070052#include <linux/backing-dev.h>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070053
Linus Torvalds1da177e2005-04-16 15:20:36 -070054#include <asm/uaccess.h>
55#include <asm/div64.h>
56#include <asm/pgtable.h>
57
58/* This magic number is used in glibc for posix shared memory */
59#define TMPFS_MAGIC 0x01021994
60
61#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
62#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
63#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
64
65#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
66#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
67
68#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
69
70/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
71#define SHMEM_PAGEIN VM_READ
72#define SHMEM_TRUNCATE VM_WRITE
73
74/* Definition to limit shmem_truncate's steps between cond_rescheds */
75#define LATENCY_LIMIT 64
76
77/* Pretend that each entry is of this size in directory's i_size */
78#define BOGO_DIRENT_SIZE 20
79
Linus Torvalds1da177e2005-04-16 15:20:36 -070080/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
81enum sgp_type {
82 SGP_QUICK, /* don't try more than file page cache lookup */
83 SGP_READ, /* don't exceed i_size, don't allocate page */
84 SGP_CACHE, /* don't exceed i_size, may allocate page */
85 SGP_WRITE, /* may exceed i_size, may allocate page */
86};
87
88static int shmem_getpage(struct inode *inode, unsigned long idx,
89 struct page **pagep, enum sgp_type sgp, int *type);
90
Al Viro6daa0e22005-10-21 03:18:50 -040091static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092{
93 /*
94 * The above definition of ENTRIES_PER_PAGE, and the use of
95 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
96 * might be reconsidered if it ever diverges from PAGE_SIZE.
Mel Gorman769848c2007-07-17 04:03:05 -070097 *
98 * __GFP_MOVABLE is masked out as swap vectors cannot move
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 */
Mel Gorman769848c2007-07-17 04:03:05 -0700100 return alloc_pages((gfp_mask & ~__GFP_MOVABLE) | __GFP_ZERO,
101 PAGE_CACHE_SHIFT-PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102}
103
104static inline void shmem_dir_free(struct page *page)
105{
106 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
107}
108
109static struct page **shmem_dir_map(struct page *page)
110{
111 return (struct page **)kmap_atomic(page, KM_USER0);
112}
113
114static inline void shmem_dir_unmap(struct page **dir)
115{
116 kunmap_atomic(dir, KM_USER0);
117}
118
119static swp_entry_t *shmem_swp_map(struct page *page)
120{
121 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
122}
123
124static inline void shmem_swp_balance_unmap(void)
125{
126 /*
127 * When passing a pointer to an i_direct entry, to code which
128 * also handles indirect entries and so will shmem_swp_unmap,
129 * we must arrange for the preempt count to remain in balance.
130 * What kmap_atomic of a lowmem page does depends on config
131 * and architecture, so pretend to kmap_atomic some lowmem page.
132 */
133 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
134}
135
136static inline void shmem_swp_unmap(swp_entry_t *entry)
137{
138 kunmap_atomic(entry, KM_USER1);
139}
140
141static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
142{
143 return sb->s_fs_info;
144}
145
146/*
147 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
148 * for shared memory and for shared anonymous (/dev/zero) mappings
149 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
150 * consistent with the pre-accounting of private mappings ...
151 */
152static inline int shmem_acct_size(unsigned long flags, loff_t size)
153{
154 return (flags & VM_ACCOUNT)?
155 security_vm_enough_memory(VM_ACCT(size)): 0;
156}
157
158static inline void shmem_unacct_size(unsigned long flags, loff_t size)
159{
160 if (flags & VM_ACCOUNT)
161 vm_unacct_memory(VM_ACCT(size));
162}
163
164/*
165 * ... whereas tmpfs objects are accounted incrementally as
166 * pages are allocated, in order to allow huge sparse files.
167 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
168 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
169 */
170static inline int shmem_acct_block(unsigned long flags)
171{
172 return (flags & VM_ACCOUNT)?
173 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
174}
175
176static inline void shmem_unacct_blocks(unsigned long flags, long pages)
177{
178 if (!(flags & VM_ACCOUNT))
179 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
180}
181
Hugh Dickins759b9772007-03-05 00:30:28 -0800182static const struct super_operations shmem_ops;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700183static const struct address_space_operations shmem_aops;
Helge Deller15ad7cd2006-12-06 20:40:36 -0800184static const struct file_operations shmem_file_operations;
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -0800185static const struct inode_operations shmem_inode_operations;
186static const struct inode_operations shmem_dir_inode_operations;
187static const struct inode_operations shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188static struct vm_operations_struct shmem_vm_ops;
189
Ravikiran G Thirumalai6c231b72005-09-06 15:17:45 -0700190static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 .ra_pages = 0, /* No readahead */
192 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
193 .unplug_io_fn = default_unplug_io_fn,
194};
195
196static LIST_HEAD(shmem_swaplist);
197static DEFINE_SPINLOCK(shmem_swaplist_lock);
198
199static void shmem_free_blocks(struct inode *inode, long pages)
200{
201 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700202 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 spin_lock(&sbinfo->stat_lock);
204 sbinfo->free_blocks += pages;
205 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
206 spin_unlock(&sbinfo->stat_lock);
207 }
208}
209
210/*
211 * shmem_recalc_inode - recalculate the size of an inode
212 *
213 * @inode: inode to recalc
214 *
215 * We have to calculate the free blocks since the mm can drop
216 * undirtied hole pages behind our back.
217 *
218 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
219 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
220 *
221 * It has to be called with the spinlock held.
222 */
223static void shmem_recalc_inode(struct inode *inode)
224{
225 struct shmem_inode_info *info = SHMEM_I(inode);
226 long freed;
227
228 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
229 if (freed > 0) {
230 info->alloced -= freed;
231 shmem_unacct_blocks(info->flags, freed);
232 shmem_free_blocks(inode, freed);
233 }
234}
235
236/*
237 * shmem_swp_entry - find the swap vector position in the info structure
238 *
239 * @info: info structure for the inode
240 * @index: index of the page to find
241 * @page: optional page to add to the structure. Has to be preset to
242 * all zeros
243 *
244 * If there is no space allocated yet it will return NULL when
245 * page is NULL, else it will use the page for the needed block,
246 * setting it to NULL on return to indicate that it has been used.
247 *
248 * The swap vector is organized the following way:
249 *
250 * There are SHMEM_NR_DIRECT entries directly stored in the
251 * shmem_inode_info structure. So small files do not need an addional
252 * allocation.
253 *
254 * For pages with index > SHMEM_NR_DIRECT there is the pointer
255 * i_indirect which points to a page which holds in the first half
256 * doubly indirect blocks, in the second half triple indirect blocks:
257 *
258 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
259 * following layout (for SHMEM_NR_DIRECT == 16):
260 *
261 * i_indirect -> dir --> 16-19
262 * | +-> 20-23
263 * |
264 * +-->dir2 --> 24-27
265 * | +-> 28-31
266 * | +-> 32-35
267 * | +-> 36-39
268 * |
269 * +-->dir3 --> 40-43
270 * +-> 44-47
271 * +-> 48-51
272 * +-> 52-55
273 */
274static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
275{
276 unsigned long offset;
277 struct page **dir;
278 struct page *subdir;
279
280 if (index < SHMEM_NR_DIRECT) {
281 shmem_swp_balance_unmap();
282 return info->i_direct+index;
283 }
284 if (!info->i_indirect) {
285 if (page) {
286 info->i_indirect = *page;
287 *page = NULL;
288 }
289 return NULL; /* need another page */
290 }
291
292 index -= SHMEM_NR_DIRECT;
293 offset = index % ENTRIES_PER_PAGE;
294 index /= ENTRIES_PER_PAGE;
295 dir = shmem_dir_map(info->i_indirect);
296
297 if (index >= ENTRIES_PER_PAGE/2) {
298 index -= ENTRIES_PER_PAGE/2;
299 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
300 index %= ENTRIES_PER_PAGE;
301 subdir = *dir;
302 if (!subdir) {
303 if (page) {
304 *dir = *page;
305 *page = NULL;
306 }
307 shmem_dir_unmap(dir);
308 return NULL; /* need another page */
309 }
310 shmem_dir_unmap(dir);
311 dir = shmem_dir_map(subdir);
312 }
313
314 dir += index;
315 subdir = *dir;
316 if (!subdir) {
317 if (!page || !(subdir = *page)) {
318 shmem_dir_unmap(dir);
319 return NULL; /* need a page */
320 }
321 *dir = subdir;
322 *page = NULL;
323 }
324 shmem_dir_unmap(dir);
325 return shmem_swp_map(subdir) + offset;
326}
327
328static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
329{
330 long incdec = value? 1: -1;
331
332 entry->val = value;
333 info->swapped += incdec;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700334 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
335 struct page *page = kmap_atomic_to_page(entry);
336 set_page_private(page, page_private(page) + incdec);
337 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338}
339
340/*
341 * shmem_swp_alloc - get the position of the swap entry for the page.
342 * If it does not exist allocate the entry.
343 *
344 * @info: info structure for the inode
345 * @index: index of the page to find
346 * @sgp: check and recheck i_size? skip allocation?
347 */
348static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
349{
350 struct inode *inode = &info->vfs_inode;
351 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
352 struct page *page = NULL;
353 swp_entry_t *entry;
354
355 if (sgp != SGP_WRITE &&
356 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
357 return ERR_PTR(-EINVAL);
358
359 while (!(entry = shmem_swp_entry(info, index, &page))) {
360 if (sgp == SGP_READ)
361 return shmem_swp_map(ZERO_PAGE(0));
362 /*
363 * Test free_blocks against 1 not 0, since we have 1 data
364 * page (and perhaps indirect index pages) yet to allocate:
365 * a waste to allocate index if we cannot allocate data.
366 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700367 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 spin_lock(&sbinfo->stat_lock);
369 if (sbinfo->free_blocks <= 1) {
370 spin_unlock(&sbinfo->stat_lock);
371 return ERR_PTR(-ENOSPC);
372 }
373 sbinfo->free_blocks--;
374 inode->i_blocks += BLOCKS_PER_PAGE;
375 spin_unlock(&sbinfo->stat_lock);
376 }
377
378 spin_unlock(&info->lock);
Mel Gorman769848c2007-07-17 04:03:05 -0700379 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700380 if (page)
381 set_page_private(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700382 spin_lock(&info->lock);
383
384 if (!page) {
385 shmem_free_blocks(inode, 1);
386 return ERR_PTR(-ENOMEM);
387 }
388 if (sgp != SGP_WRITE &&
389 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
390 entry = ERR_PTR(-EINVAL);
391 break;
392 }
393 if (info->next_index <= index)
394 info->next_index = index + 1;
395 }
396 if (page) {
397 /* another task gave its page, or truncated the file */
398 shmem_free_blocks(inode, 1);
399 shmem_dir_free(page);
400 }
401 if (info->next_index <= index && !IS_ERR(entry))
402 info->next_index = index + 1;
403 return entry;
404}
405
406/*
407 * shmem_free_swp - free some swap entries in a directory
408 *
Hugh Dickins1ae70002007-03-29 01:20:36 -0700409 * @dir: pointer to the directory
410 * @edir: pointer after last entry of the directory
411 * @punch_lock: pointer to spinlock when needed for the holepunch case
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 */
Hugh Dickins1ae70002007-03-29 01:20:36 -0700413static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
414 spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415{
Hugh Dickins1ae70002007-03-29 01:20:36 -0700416 spinlock_t *punch_unlock = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 swp_entry_t *ptr;
418 int freed = 0;
419
420 for (ptr = dir; ptr < edir; ptr++) {
421 if (ptr->val) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700422 if (unlikely(punch_lock)) {
423 punch_unlock = punch_lock;
424 punch_lock = NULL;
425 spin_lock(punch_unlock);
426 if (!ptr->val)
427 continue;
428 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 free_swap_and_cache(*ptr);
430 *ptr = (swp_entry_t){0};
431 freed++;
432 }
433 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700434 if (punch_unlock)
435 spin_unlock(punch_unlock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436 return freed;
437}
438
Hugh Dickins1ae70002007-03-29 01:20:36 -0700439static int shmem_map_and_free_swp(struct page *subdir, int offset,
440 int limit, struct page ***dir, spinlock_t *punch_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441{
442 swp_entry_t *ptr;
443 int freed = 0;
444
445 ptr = shmem_swp_map(subdir);
446 for (; offset < limit; offset += LATENCY_LIMIT) {
447 int size = limit - offset;
448 if (size > LATENCY_LIMIT)
449 size = LATENCY_LIMIT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700450 freed += shmem_free_swp(ptr+offset, ptr+offset+size,
451 punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 if (need_resched()) {
453 shmem_swp_unmap(ptr);
454 if (*dir) {
455 shmem_dir_unmap(*dir);
456 *dir = NULL;
457 }
458 cond_resched();
459 ptr = shmem_swp_map(subdir);
460 }
461 }
462 shmem_swp_unmap(ptr);
463 return freed;
464}
465
466static void shmem_free_pages(struct list_head *next)
467{
468 struct page *page;
469 int freed = 0;
470
471 do {
472 page = container_of(next, struct page, lru);
473 next = next->next;
474 shmem_dir_free(page);
475 freed++;
476 if (freed >= LATENCY_LIMIT) {
477 cond_resched();
478 freed = 0;
479 }
480 } while (next);
481}
482
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800483static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484{
485 struct shmem_inode_info *info = SHMEM_I(inode);
486 unsigned long idx;
487 unsigned long size;
488 unsigned long limit;
489 unsigned long stage;
490 unsigned long diroff;
491 struct page **dir;
492 struct page *topdir;
493 struct page *middir;
494 struct page *subdir;
495 swp_entry_t *ptr;
496 LIST_HEAD(pages_to_free);
497 long nr_pages_to_free = 0;
498 long nr_swaps_freed = 0;
499 int offset;
500 int freed;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700501 int punch_hole;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700502 spinlock_t *needs_lock;
503 spinlock_t *punch_lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700504 unsigned long upper_limit;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505
506 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800507 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508 if (idx >= info->next_index)
509 return;
510
511 spin_lock(&info->lock);
512 info->flags |= SHMEM_TRUNCATE;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800513 if (likely(end == (loff_t) -1)) {
514 limit = info->next_index;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700515 upper_limit = SHMEM_MAX_INDEX;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800516 info->next_index = idx;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700517 needs_lock = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700518 punch_hole = 0;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800519 } else {
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700520 if (end + 1 >= inode->i_size) { /* we may free a little more */
521 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
522 PAGE_CACHE_SHIFT;
523 upper_limit = SHMEM_MAX_INDEX;
524 } else {
525 limit = (end + 1) >> PAGE_CACHE_SHIFT;
526 upper_limit = limit;
527 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700528 needs_lock = &info->lock;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800529 punch_hole = 1;
530 }
531
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 topdir = info->i_indirect;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800533 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 info->i_indirect = NULL;
535 nr_pages_to_free++;
536 list_add(&topdir->lru, &pages_to_free);
537 }
538 spin_unlock(&info->lock);
539
540 if (info->swapped && idx < SHMEM_NR_DIRECT) {
541 ptr = info->i_direct;
542 size = limit;
543 if (size > SHMEM_NR_DIRECT)
544 size = SHMEM_NR_DIRECT;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700545 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700546 }
Badari Pulavarty92a3d032006-12-22 01:06:23 -0800547
548 /*
549 * If there are no indirect blocks or we are punching a hole
550 * below indirect blocks, nothing to be done.
551 */
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700552 if (!topdir || limit <= SHMEM_NR_DIRECT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700553 goto done2;
554
Hugh Dickins1ae70002007-03-29 01:20:36 -0700555 /*
556 * The truncation case has already dropped info->lock, and we're safe
557 * because i_size and next_index have already been lowered, preventing
558 * access beyond. But in the punch_hole case, we still need to take
559 * the lock when updating the swap directory, because there might be
560 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
561 * shmem_writepage. However, whenever we find we can remove a whole
562 * directory page (not at the misaligned start or end of the range),
563 * we first NULLify its pointer in the level above, and then have no
564 * need to take the lock when updating its contents: needs_lock and
565 * punch_lock (either pointing to info->lock or NULL) manage this.
566 */
567
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700568 upper_limit -= SHMEM_NR_DIRECT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569 limit -= SHMEM_NR_DIRECT;
570 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
571 offset = idx % ENTRIES_PER_PAGE;
572 idx -= offset;
573
574 dir = shmem_dir_map(topdir);
575 stage = ENTRIES_PER_PAGEPAGE/2;
576 if (idx < ENTRIES_PER_PAGEPAGE/2) {
577 middir = topdir;
578 diroff = idx/ENTRIES_PER_PAGE;
579 } else {
580 dir += ENTRIES_PER_PAGE/2;
581 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
582 while (stage <= idx)
583 stage += ENTRIES_PER_PAGEPAGE;
584 middir = *dir;
585 if (*dir) {
586 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
587 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700588 if (!diroff && !offset && upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700589 if (needs_lock) {
590 spin_lock(needs_lock);
591 *dir = NULL;
592 spin_unlock(needs_lock);
593 needs_lock = NULL;
594 } else
595 *dir = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596 nr_pages_to_free++;
597 list_add(&middir->lru, &pages_to_free);
598 }
599 shmem_dir_unmap(dir);
600 dir = shmem_dir_map(middir);
601 } else {
602 diroff = 0;
603 offset = 0;
604 idx = stage;
605 }
606 }
607
608 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
609 if (unlikely(idx == stage)) {
610 shmem_dir_unmap(dir);
611 dir = shmem_dir_map(topdir) +
612 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
613 while (!*dir) {
614 dir++;
615 idx += ENTRIES_PER_PAGEPAGE;
616 if (idx >= limit)
617 goto done1;
618 }
619 stage = idx + ENTRIES_PER_PAGEPAGE;
620 middir = *dir;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700621 if (punch_hole)
622 needs_lock = &info->lock;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700623 if (upper_limit >= stage) {
Hugh Dickins1ae70002007-03-29 01:20:36 -0700624 if (needs_lock) {
625 spin_lock(needs_lock);
626 *dir = NULL;
627 spin_unlock(needs_lock);
628 needs_lock = NULL;
629 } else
630 *dir = NULL;
Hugh Dickinsa2646d12007-03-29 01:20:35 -0700631 nr_pages_to_free++;
632 list_add(&middir->lru, &pages_to_free);
633 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700634 shmem_dir_unmap(dir);
635 cond_resched();
636 dir = shmem_dir_map(middir);
637 diroff = 0;
638 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700639 punch_lock = needs_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 subdir = dir[diroff];
Hugh Dickins1ae70002007-03-29 01:20:36 -0700641 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
642 if (needs_lock) {
643 spin_lock(needs_lock);
644 dir[diroff] = NULL;
645 spin_unlock(needs_lock);
646 punch_lock = NULL;
647 } else
648 dir[diroff] = NULL;
649 nr_pages_to_free++;
650 list_add(&subdir->lru, &pages_to_free);
651 }
652 if (subdir && page_private(subdir) /* has swap entries */) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700653 size = limit - idx;
654 if (size > ENTRIES_PER_PAGE)
655 size = ENTRIES_PER_PAGE;
656 freed = shmem_map_and_free_swp(subdir,
Hugh Dickins1ae70002007-03-29 01:20:36 -0700657 offset, size, &dir, punch_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658 if (!dir)
659 dir = shmem_dir_map(middir);
660 nr_swaps_freed += freed;
Hugh Dickins1ae70002007-03-29 01:20:36 -0700661 if (offset || punch_lock) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662 spin_lock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700663 set_page_private(subdir,
664 page_private(subdir) - freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700665 spin_unlock(&info->lock);
Hugh Dickins1ae70002007-03-29 01:20:36 -0700666 } else
667 BUG_ON(page_private(subdir) != freed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 }
Hugh Dickins1ae70002007-03-29 01:20:36 -0700669 offset = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 }
671done1:
672 shmem_dir_unmap(dir);
673done2:
674 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
675 /*
676 * Call truncate_inode_pages again: racing shmem_unuse_inode
677 * may have swizzled a page in from swap since vmtruncate or
678 * generic_delete_inode did it, before we lowered next_index.
679 * Also, though shmem_getpage checks i_size before adding to
680 * cache, no recheck after: so fix the narrow window there too.
Hugh Dickins16a10012007-03-29 01:20:37 -0700681 *
682 * Recalling truncate_inode_pages_range and unmap_mapping_range
683 * every time for punch_hole (which never got a chance to clear
684 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
685 * yet hardly ever necessary: try to optimize them out later.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700686 */
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800687 truncate_inode_pages_range(inode->i_mapping, start, end);
Hugh Dickins16a10012007-03-29 01:20:37 -0700688 if (punch_hole)
689 unmap_mapping_range(inode->i_mapping, start,
690 end - start, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 }
692
693 spin_lock(&info->lock);
694 info->flags &= ~SHMEM_TRUNCATE;
695 info->swapped -= nr_swaps_freed;
696 if (nr_pages_to_free)
697 shmem_free_blocks(inode, nr_pages_to_free);
698 shmem_recalc_inode(inode);
699 spin_unlock(&info->lock);
700
701 /*
702 * Empty swap vector directory pages to be freed?
703 */
704 if (!list_empty(&pages_to_free)) {
705 pages_to_free.prev->next = NULL;
706 shmem_free_pages(pages_to_free.next);
707 }
708}
709
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800710static void shmem_truncate(struct inode *inode)
711{
712 shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
713}
714
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
716{
717 struct inode *inode = dentry->d_inode;
718 struct page *page = NULL;
719 int error;
720
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700721 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 if (attr->ia_size < inode->i_size) {
723 /*
724 * If truncating down to a partial page, then
725 * if that page is already allocated, hold it
726 * in memory until the truncation is over, so
727 * truncate_partial_page cannnot miss it were
728 * it assigned to swap.
729 */
730 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
731 (void) shmem_getpage(inode,
732 attr->ia_size>>PAGE_CACHE_SHIFT,
733 &page, SGP_READ, NULL);
734 }
735 /*
736 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
737 * detect if any pages might have been added to cache
738 * after truncate_inode_pages. But we needn't bother
739 * if it's being fully truncated to zero-length: the
740 * nrpages check is efficient enough in that case.
741 */
742 if (attr->ia_size) {
743 struct shmem_inode_info *info = SHMEM_I(inode);
744 spin_lock(&info->lock);
745 info->flags &= ~SHMEM_PAGEIN;
746 spin_unlock(&info->lock);
747 }
748 }
749 }
750
751 error = inode_change_ok(inode, attr);
752 if (!error)
753 error = inode_setattr(inode, attr);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -0700754#ifdef CONFIG_TMPFS_POSIX_ACL
755 if (!error && (attr->ia_valid & ATTR_MODE))
756 error = generic_acl_chmod(inode, &shmem_acl_ops);
757#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 if (page)
759 page_cache_release(page);
760 return error;
761}
762
763static void shmem_delete_inode(struct inode *inode)
764{
765 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
766 struct shmem_inode_info *info = SHMEM_I(inode);
767
768 if (inode->i_op->truncate == shmem_truncate) {
Mark Fashehfef26652005-09-09 13:01:31 -0700769 truncate_inode_pages(inode->i_mapping, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 shmem_unacct_size(info->flags, inode->i_size);
771 inode->i_size = 0;
772 shmem_truncate(inode);
773 if (!list_empty(&info->swaplist)) {
774 spin_lock(&shmem_swaplist_lock);
775 list_del_init(&info->swaplist);
776 spin_unlock(&shmem_swaplist_lock);
777 }
778 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -0700779 BUG_ON(inode->i_blocks);
780 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 spin_lock(&sbinfo->stat_lock);
782 sbinfo->free_inodes++;
783 spin_unlock(&sbinfo->stat_lock);
784 }
785 clear_inode(inode);
786}
787
788static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
789{
790 swp_entry_t *ptr;
791
792 for (ptr = dir; ptr < edir; ptr++) {
793 if (ptr->val == entry.val)
794 return ptr - dir;
795 }
796 return -1;
797}
798
799static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
800{
801 struct inode *inode;
802 unsigned long idx;
803 unsigned long size;
804 unsigned long limit;
805 unsigned long stage;
806 struct page **dir;
807 struct page *subdir;
808 swp_entry_t *ptr;
809 int offset;
810
811 idx = 0;
812 ptr = info->i_direct;
813 spin_lock(&info->lock);
814 limit = info->next_index;
815 size = limit;
816 if (size > SHMEM_NR_DIRECT)
817 size = SHMEM_NR_DIRECT;
818 offset = shmem_find_swp(entry, ptr, ptr+size);
819 if (offset >= 0) {
820 shmem_swp_balance_unmap();
821 goto found;
822 }
823 if (!info->i_indirect)
824 goto lost2;
825
826 dir = shmem_dir_map(info->i_indirect);
827 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
828
829 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
830 if (unlikely(idx == stage)) {
831 shmem_dir_unmap(dir-1);
832 dir = shmem_dir_map(info->i_indirect) +
833 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
834 while (!*dir) {
835 dir++;
836 idx += ENTRIES_PER_PAGEPAGE;
837 if (idx >= limit)
838 goto lost1;
839 }
840 stage = idx + ENTRIES_PER_PAGEPAGE;
841 subdir = *dir;
842 shmem_dir_unmap(dir);
843 dir = shmem_dir_map(subdir);
844 }
845 subdir = *dir;
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700846 if (subdir && page_private(subdir)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700847 ptr = shmem_swp_map(subdir);
848 size = limit - idx;
849 if (size > ENTRIES_PER_PAGE)
850 size = ENTRIES_PER_PAGE;
851 offset = shmem_find_swp(entry, ptr, ptr+size);
852 if (offset >= 0) {
853 shmem_dir_unmap(dir);
854 goto found;
855 }
856 shmem_swp_unmap(ptr);
857 }
858 }
859lost1:
860 shmem_dir_unmap(dir-1);
861lost2:
862 spin_unlock(&info->lock);
863 return 0;
864found:
865 idx += offset;
866 inode = &info->vfs_inode;
867 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
868 info->flags |= SHMEM_PAGEIN;
869 shmem_swp_set(info, ptr + offset, 0);
870 }
871 shmem_swp_unmap(ptr);
872 spin_unlock(&info->lock);
873 /*
874 * Decrement swap count even when the entry is left behind:
875 * try_to_unuse will skip over mms, then reincrement count.
876 */
877 swap_free(entry);
878 return 1;
879}
880
881/*
882 * shmem_unuse() search for an eventually swapped out shmem page.
883 */
884int shmem_unuse(swp_entry_t entry, struct page *page)
885{
886 struct list_head *p, *next;
887 struct shmem_inode_info *info;
888 int found = 0;
889
890 spin_lock(&shmem_swaplist_lock);
891 list_for_each_safe(p, next, &shmem_swaplist) {
892 info = list_entry(p, struct shmem_inode_info, swaplist);
893 if (!info->swapped)
894 list_del_init(&info->swaplist);
895 else if (shmem_unuse_inode(info, entry, page)) {
896 /* move head to start search for next from here */
897 list_move_tail(&shmem_swaplist, &info->swaplist);
898 found = 1;
899 break;
900 }
901 }
902 spin_unlock(&shmem_swaplist_lock);
903 return found;
904}
905
906/*
907 * Move the page from the page cache to the swap cache.
908 */
909static int shmem_writepage(struct page *page, struct writeback_control *wbc)
910{
911 struct shmem_inode_info *info;
912 swp_entry_t *entry, swap;
913 struct address_space *mapping;
914 unsigned long index;
915 struct inode *inode;
916
917 BUG_ON(!PageLocked(page));
918 BUG_ON(page_mapped(page));
919
920 mapping = page->mapping;
921 index = page->index;
922 inode = mapping->host;
923 info = SHMEM_I(inode);
924 if (info->flags & VM_LOCKED)
925 goto redirty;
926 swap = get_swap_page();
927 if (!swap.val)
928 goto redirty;
929
930 spin_lock(&info->lock);
931 shmem_recalc_inode(inode);
932 if (index >= info->next_index) {
933 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
934 goto unlock;
935 }
936 entry = shmem_swp_entry(info, index, NULL);
937 BUG_ON(!entry);
938 BUG_ON(entry->val);
939
940 if (move_to_swap_cache(page, swap) == 0) {
941 shmem_swp_set(info, entry, swap.val);
942 shmem_swp_unmap(entry);
943 spin_unlock(&info->lock);
944 if (list_empty(&info->swaplist)) {
945 spin_lock(&shmem_swaplist_lock);
946 /* move instead of add in case we're racing */
947 list_move_tail(&info->swaplist, &shmem_swaplist);
948 spin_unlock(&shmem_swaplist_lock);
949 }
950 unlock_page(page);
951 return 0;
952 }
953
954 shmem_swp_unmap(entry);
955unlock:
956 spin_unlock(&info->lock);
957 swap_free(swap);
958redirty:
959 set_page_dirty(page);
Zach Brown994fc28c2005-12-15 14:28:17 -0800960 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961}
962
963#ifdef CONFIG_NUMA
Hugh Dickinsd15c0232006-03-22 00:08:46 -0800964static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +0000965{
966 char *nodelist = strchr(value, ':');
967 int err = 1;
968
969 if (nodelist) {
970 /* NUL-terminate policy string */
971 *nodelist++ = '\0';
972 if (nodelist_parse(nodelist, *policy_nodes))
973 goto out;
Hugh Dickinsa2109062007-06-08 13:46:46 -0700974 if (!nodes_subset(*policy_nodes, node_online_map))
975 goto out;
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +0000976 }
977 if (!strcmp(value, "default")) {
978 *policy = MPOL_DEFAULT;
979 /* Don't allow a nodelist */
980 if (!nodelist)
981 err = 0;
982 } else if (!strcmp(value, "prefer")) {
983 *policy = MPOL_PREFERRED;
984 /* Insist on a nodelist of one node only */
985 if (nodelist) {
986 char *rest = nodelist;
987 while (isdigit(*rest))
988 rest++;
989 if (!*rest)
990 err = 0;
991 }
992 } else if (!strcmp(value, "bind")) {
993 *policy = MPOL_BIND;
994 /* Insist on a nodelist */
995 if (nodelist)
996 err = 0;
997 } else if (!strcmp(value, "interleave")) {
998 *policy = MPOL_INTERLEAVE;
999 /* Default to nodes online if no nodelist */
1000 if (!nodelist)
1001 *policy_nodes = node_online_map;
1002 err = 0;
1003 }
1004out:
1005 /* Restore string for error message */
1006 if (nodelist)
1007 *--nodelist = ':';
1008 return err;
1009}
1010
Linus Torvalds1da177e2005-04-16 15:20:36 -07001011static struct page *shmem_swapin_async(struct shared_policy *p,
1012 swp_entry_t entry, unsigned long idx)
1013{
1014 struct page *page;
1015 struct vm_area_struct pvma;
1016
1017 /* Create a pseudo vma that just contains the policy */
1018 memset(&pvma, 0, sizeof(struct vm_area_struct));
1019 pvma.vm_end = PAGE_SIZE;
1020 pvma.vm_pgoff = idx;
1021 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
1022 page = read_swap_cache_async(entry, &pvma, 0);
1023 mpol_free(pvma.vm_policy);
1024 return page;
1025}
1026
1027struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
1028 unsigned long idx)
1029{
1030 struct shared_policy *p = &info->policy;
1031 int i, num;
1032 struct page *page;
1033 unsigned long offset;
1034
1035 num = valid_swaphandles(entry, &offset);
1036 for (i = 0; i < num; offset++, i++) {
1037 page = shmem_swapin_async(p,
1038 swp_entry(swp_type(entry), offset), idx);
1039 if (!page)
1040 break;
1041 page_cache_release(page);
1042 }
1043 lru_add_drain(); /* Push any new pages onto the LRU now */
1044 return shmem_swapin_async(p, entry, idx);
1045}
1046
1047static struct page *
Al Viro6daa0e22005-10-21 03:18:50 -04001048shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001049 unsigned long idx)
1050{
1051 struct vm_area_struct pvma;
1052 struct page *page;
1053
1054 memset(&pvma, 0, sizeof(struct vm_area_struct));
1055 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1056 pvma.vm_pgoff = idx;
1057 pvma.vm_end = PAGE_SIZE;
1058 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
1059 mpol_free(pvma.vm_policy);
1060 return page;
1061}
1062#else
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00001063static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes)
1064{
1065 return 1;
1066}
1067
Linus Torvalds1da177e2005-04-16 15:20:36 -07001068static inline struct page *
1069shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
1070{
1071 swapin_readahead(entry, 0, NULL);
1072 return read_swap_cache_async(entry, NULL, 0);
1073}
1074
1075static inline struct page *
Al Virodd0fc662005-10-07 07:46:04 +01001076shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001077{
1078 return alloc_page(gfp | __GFP_ZERO);
1079}
1080#endif
1081
1082/*
1083 * shmem_getpage - either get the page from swap or allocate a new one
1084 *
1085 * If we allocate a new one we do not mark it dirty. That's up to the
1086 * vm. If we swap it in we mark it dirty since we also free the swap
1087 * entry since a page cannot live in both the swap and page cache
1088 */
1089static int shmem_getpage(struct inode *inode, unsigned long idx,
1090 struct page **pagep, enum sgp_type sgp, int *type)
1091{
1092 struct address_space *mapping = inode->i_mapping;
1093 struct shmem_inode_info *info = SHMEM_I(inode);
1094 struct shmem_sb_info *sbinfo;
1095 struct page *filepage = *pagep;
1096 struct page *swappage;
1097 swp_entry_t *entry;
1098 swp_entry_t swap;
1099 int error;
1100
1101 if (idx >= SHMEM_MAX_INDEX)
1102 return -EFBIG;
1103 /*
1104 * Normally, filepage is NULL on entry, and either found
1105 * uptodate immediately, or allocated and zeroed, or read
1106 * in under swappage, which is then assigned to filepage.
Hugh Dickinsae976412007-06-04 10:00:39 +02001107 * But shmem_readpage and shmem_prepare_write pass in a locked
1108 * filepage, which may be found not uptodate by other callers
1109 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001110 */
1111repeat:
1112 if (!filepage)
1113 filepage = find_lock_page(mapping, idx);
1114 if (filepage && PageUptodate(filepage))
1115 goto done;
1116 error = 0;
1117 if (sgp == SGP_QUICK)
1118 goto failed;
1119
1120 spin_lock(&info->lock);
1121 shmem_recalc_inode(inode);
1122 entry = shmem_swp_alloc(info, idx, sgp);
1123 if (IS_ERR(entry)) {
1124 spin_unlock(&info->lock);
1125 error = PTR_ERR(entry);
1126 goto failed;
1127 }
1128 swap = *entry;
1129
1130 if (swap.val) {
1131 /* Look it up and read it in.. */
1132 swappage = lookup_swap_cache(swap);
1133 if (!swappage) {
1134 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135 /* here we actually do the io */
1136 if (type && *type == VM_FAULT_MINOR) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001137 __count_vm_event(PGMAJFAULT);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001138 *type = VM_FAULT_MAJOR;
1139 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001140 spin_unlock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001141 swappage = shmem_swapin(info, swap, idx);
1142 if (!swappage) {
1143 spin_lock(&info->lock);
1144 entry = shmem_swp_alloc(info, idx, sgp);
1145 if (IS_ERR(entry))
1146 error = PTR_ERR(entry);
1147 else {
1148 if (entry->val == swap.val)
1149 error = -ENOMEM;
1150 shmem_swp_unmap(entry);
1151 }
1152 spin_unlock(&info->lock);
1153 if (error)
1154 goto failed;
1155 goto repeat;
1156 }
1157 wait_on_page_locked(swappage);
1158 page_cache_release(swappage);
1159 goto repeat;
1160 }
1161
1162 /* We have to do this with page locked to prevent races */
1163 if (TestSetPageLocked(swappage)) {
1164 shmem_swp_unmap(entry);
1165 spin_unlock(&info->lock);
1166 wait_on_page_locked(swappage);
1167 page_cache_release(swappage);
1168 goto repeat;
1169 }
1170 if (PageWriteback(swappage)) {
1171 shmem_swp_unmap(entry);
1172 spin_unlock(&info->lock);
1173 wait_on_page_writeback(swappage);
1174 unlock_page(swappage);
1175 page_cache_release(swappage);
1176 goto repeat;
1177 }
1178 if (!PageUptodate(swappage)) {
1179 shmem_swp_unmap(entry);
1180 spin_unlock(&info->lock);
1181 unlock_page(swappage);
1182 page_cache_release(swappage);
1183 error = -EIO;
1184 goto failed;
1185 }
1186
1187 if (filepage) {
1188 shmem_swp_set(info, entry, 0);
1189 shmem_swp_unmap(entry);
1190 delete_from_swap_cache(swappage);
1191 spin_unlock(&info->lock);
1192 copy_highpage(filepage, swappage);
1193 unlock_page(swappage);
1194 page_cache_release(swappage);
1195 flush_dcache_page(filepage);
1196 SetPageUptodate(filepage);
1197 set_page_dirty(filepage);
1198 swap_free(swap);
1199 } else if (!(error = move_from_swap_cache(
1200 swappage, idx, mapping))) {
1201 info->flags |= SHMEM_PAGEIN;
1202 shmem_swp_set(info, entry, 0);
1203 shmem_swp_unmap(entry);
1204 spin_unlock(&info->lock);
1205 filepage = swappage;
1206 swap_free(swap);
1207 } else {
1208 shmem_swp_unmap(entry);
1209 spin_unlock(&info->lock);
1210 unlock_page(swappage);
1211 page_cache_release(swappage);
1212 if (error == -ENOMEM) {
1213 /* let kswapd refresh zone for GFP_ATOMICs */
Andrew Morton3fcfab12006-10-19 23:28:16 -07001214 congestion_wait(WRITE, HZ/50);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001215 }
1216 goto repeat;
1217 }
1218 } else if (sgp == SGP_READ && !filepage) {
1219 shmem_swp_unmap(entry);
1220 filepage = find_get_page(mapping, idx);
1221 if (filepage &&
1222 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1223 spin_unlock(&info->lock);
1224 wait_on_page_locked(filepage);
1225 page_cache_release(filepage);
1226 filepage = NULL;
1227 goto repeat;
1228 }
1229 spin_unlock(&info->lock);
1230 } else {
1231 shmem_swp_unmap(entry);
1232 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001233 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001234 spin_lock(&sbinfo->stat_lock);
1235 if (sbinfo->free_blocks == 0 ||
1236 shmem_acct_block(info->flags)) {
1237 spin_unlock(&sbinfo->stat_lock);
1238 spin_unlock(&info->lock);
1239 error = -ENOSPC;
1240 goto failed;
1241 }
1242 sbinfo->free_blocks--;
1243 inode->i_blocks += BLOCKS_PER_PAGE;
1244 spin_unlock(&sbinfo->stat_lock);
1245 } else if (shmem_acct_block(info->flags)) {
1246 spin_unlock(&info->lock);
1247 error = -ENOSPC;
1248 goto failed;
1249 }
1250
1251 if (!filepage) {
1252 spin_unlock(&info->lock);
1253 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1254 info,
1255 idx);
1256 if (!filepage) {
1257 shmem_unacct_blocks(info->flags, 1);
1258 shmem_free_blocks(inode, 1);
1259 error = -ENOMEM;
1260 goto failed;
1261 }
1262
1263 spin_lock(&info->lock);
1264 entry = shmem_swp_alloc(info, idx, sgp);
1265 if (IS_ERR(entry))
1266 error = PTR_ERR(entry);
1267 else {
1268 swap = *entry;
1269 shmem_swp_unmap(entry);
1270 }
1271 if (error || swap.val || 0 != add_to_page_cache_lru(
1272 filepage, mapping, idx, GFP_ATOMIC)) {
1273 spin_unlock(&info->lock);
1274 page_cache_release(filepage);
1275 shmem_unacct_blocks(info->flags, 1);
1276 shmem_free_blocks(inode, 1);
1277 filepage = NULL;
1278 if (error)
1279 goto failed;
1280 goto repeat;
1281 }
1282 info->flags |= SHMEM_PAGEIN;
1283 }
1284
1285 info->alloced++;
1286 spin_unlock(&info->lock);
1287 flush_dcache_page(filepage);
1288 SetPageUptodate(filepage);
1289 }
1290done:
1291 if (*pagep != filepage) {
1292 unlock_page(filepage);
1293 *pagep = filepage;
1294 }
1295 return 0;
1296
1297failed:
1298 if (*pagep != filepage) {
1299 unlock_page(filepage);
1300 page_cache_release(filepage);
1301 }
1302 return error;
1303}
1304
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001305static struct page *shmem_nopage(struct vm_area_struct *vma,
1306 unsigned long address, int *type)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001307{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001308 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309 struct page *page = NULL;
1310 unsigned long idx;
1311 int error;
1312
1313 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1314 idx += vma->vm_pgoff;
1315 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1316 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1317 return NOPAGE_SIGBUS;
1318
1319 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1320 if (error)
1321 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1322
1323 mark_page_accessed(page);
1324 return page;
1325}
1326
1327static int shmem_populate(struct vm_area_struct *vma,
1328 unsigned long addr, unsigned long len,
1329 pgprot_t prot, unsigned long pgoff, int nonblock)
1330{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001331 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 struct mm_struct *mm = vma->vm_mm;
1333 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1334 unsigned long size;
1335
1336 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1337 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1338 return -EINVAL;
1339
1340 while ((long) len > 0) {
1341 struct page *page = NULL;
1342 int err;
1343 /*
1344 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1345 */
1346 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1347 if (err)
1348 return err;
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001349 /* Page may still be null, but only if nonblock was set. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 if (page) {
1351 mark_page_accessed(page);
1352 err = install_page(mm, vma, addr, page, prot);
1353 if (err) {
1354 page_cache_release(page);
1355 return err;
1356 }
Hugh Dickins65500d22005-10-29 18:15:59 -07001357 } else if (vma->vm_flags & VM_NONLINEAR) {
Paolo 'Blaisorblade' Giarrussod44ed4f2005-09-03 15:54:55 -07001358 /* No page was found just because we can't read it in
1359 * now (being here implies nonblock != 0), but the page
1360 * may exist, so set the PTE to fault it in later. */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361 err = install_file_pte(mm, vma, addr, pgoff, prot);
1362 if (err)
1363 return err;
1364 }
1365
1366 len -= PAGE_SIZE;
1367 addr += PAGE_SIZE;
1368 pgoff++;
1369 }
1370 return 0;
1371}
1372
1373#ifdef CONFIG_NUMA
1374int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1375{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001376 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001377 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1378}
1379
1380struct mempolicy *
1381shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1382{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001383 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 unsigned long idx;
1385
1386 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1387 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1388}
1389#endif
1390
1391int shmem_lock(struct file *file, int lock, struct user_struct *user)
1392{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001393 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394 struct shmem_inode_info *info = SHMEM_I(inode);
1395 int retval = -ENOMEM;
1396
1397 spin_lock(&info->lock);
1398 if (lock && !(info->flags & VM_LOCKED)) {
1399 if (!user_shm_lock(inode->i_size, user))
1400 goto out_nomem;
1401 info->flags |= VM_LOCKED;
1402 }
1403 if (!lock && (info->flags & VM_LOCKED) && user) {
1404 user_shm_unlock(inode->i_size, user);
1405 info->flags &= ~VM_LOCKED;
1406 }
1407 retval = 0;
1408out_nomem:
1409 spin_unlock(&info->lock);
1410 return retval;
1411}
1412
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001413static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414{
1415 file_accessed(file);
1416 vma->vm_ops = &shmem_vm_ops;
1417 return 0;
1418}
1419
1420static struct inode *
1421shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1422{
1423 struct inode *inode;
1424 struct shmem_inode_info *info;
1425 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1426
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001427 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 spin_lock(&sbinfo->stat_lock);
1429 if (!sbinfo->free_inodes) {
1430 spin_unlock(&sbinfo->stat_lock);
1431 return NULL;
1432 }
1433 sbinfo->free_inodes--;
1434 spin_unlock(&sbinfo->stat_lock);
1435 }
1436
1437 inode = new_inode(sb);
1438 if (inode) {
1439 inode->i_mode = mode;
1440 inode->i_uid = current->fsuid;
1441 inode->i_gid = current->fsgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442 inode->i_blocks = 0;
1443 inode->i_mapping->a_ops = &shmem_aops;
1444 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1445 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001446 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447 info = SHMEM_I(inode);
1448 memset(info, 0, (char *)inode - (char *)info);
1449 spin_lock_init(&info->lock);
1450 INIT_LIST_HEAD(&info->swaplist);
1451
1452 switch (mode & S_IFMT) {
1453 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001454 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001455 init_special_inode(inode, mode, dev);
1456 break;
1457 case S_IFREG:
1458 inode->i_op = &shmem_inode_operations;
1459 inode->i_fop = &shmem_file_operations;
Robin Holt7339ff82006-01-14 13:20:48 -08001460 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1461 &sbinfo->policy_nodes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001462 break;
1463 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001464 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001465 /* Some things misbehave if size == 0 on a directory */
1466 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1467 inode->i_op = &shmem_dir_inode_operations;
1468 inode->i_fop = &simple_dir_operations;
1469 break;
1470 case S_IFLNK:
1471 /*
1472 * Must not load anything in the rbtree,
1473 * mpol_free_shared_policy will not be called.
1474 */
Robin Holt7339ff82006-01-14 13:20:48 -08001475 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1476 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 break;
1478 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001479 } else if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001480 spin_lock(&sbinfo->stat_lock);
1481 sbinfo->free_inodes++;
1482 spin_unlock(&sbinfo->stat_lock);
1483 }
1484 return inode;
1485}
1486
1487#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001488static const struct inode_operations shmem_symlink_inode_operations;
1489static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490
1491/*
Hugh Dickinsae976412007-06-04 10:00:39 +02001492 * Normally tmpfs avoids the use of shmem_readpage and shmem_prepare_write;
1493 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1494 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001495 */
Hugh Dickinsae976412007-06-04 10:00:39 +02001496static int shmem_readpage(struct file *file, struct page *page)
1497{
1498 struct inode *inode = page->mapping->host;
1499 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1500 unlock_page(page);
1501 return error;
1502}
1503
Linus Torvalds1da177e2005-04-16 15:20:36 -07001504static int
1505shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1506{
1507 struct inode *inode = page->mapping->host;
1508 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1509}
1510
1511static ssize_t
1512shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1513{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001514 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 loff_t pos;
1516 unsigned long written;
1517 ssize_t err;
1518
1519 if ((ssize_t) count < 0)
1520 return -EINVAL;
1521
1522 if (!access_ok(VERIFY_READ, buf, count))
1523 return -EFAULT;
1524
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001525 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001526
1527 pos = *ppos;
1528 written = 0;
1529
1530 err = generic_write_checks(file, &pos, &count, 0);
1531 if (err || !count)
1532 goto out;
1533
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001534 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001535 if (err)
1536 goto out;
1537
1538 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1539
1540 do {
1541 struct page *page = NULL;
1542 unsigned long bytes, index, offset;
1543 char *kaddr;
1544 int left;
1545
1546 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1547 index = pos >> PAGE_CACHE_SHIFT;
1548 bytes = PAGE_CACHE_SIZE - offset;
1549 if (bytes > count)
1550 bytes = count;
1551
1552 /*
1553 * We don't hold page lock across copy from user -
1554 * what would it guard against? - so no deadlock here.
1555 * But it still may be a good idea to prefault below.
1556 */
1557
1558 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1559 if (err)
1560 break;
1561
1562 left = bytes;
1563 if (PageHighMem(page)) {
1564 volatile unsigned char dummy;
1565 __get_user(dummy, buf);
1566 __get_user(dummy, buf + bytes - 1);
1567
1568 kaddr = kmap_atomic(page, KM_USER0);
1569 left = __copy_from_user_inatomic(kaddr + offset,
1570 buf, bytes);
1571 kunmap_atomic(kaddr, KM_USER0);
1572 }
1573 if (left) {
1574 kaddr = kmap(page);
1575 left = __copy_from_user(kaddr + offset, buf, bytes);
1576 kunmap(page);
1577 }
1578
1579 written += bytes;
1580 count -= bytes;
1581 pos += bytes;
1582 buf += bytes;
1583 if (pos > inode->i_size)
1584 i_size_write(inode, pos);
1585
1586 flush_dcache_page(page);
1587 set_page_dirty(page);
1588 mark_page_accessed(page);
1589 page_cache_release(page);
1590
1591 if (left) {
1592 pos -= left;
1593 written -= left;
1594 err = -EFAULT;
1595 break;
1596 }
1597
1598 /*
1599 * Our dirty pages are not counted in nr_dirty,
1600 * and we do not attempt to balance dirty pages.
1601 */
1602
1603 cond_resched();
1604 } while (count);
1605
1606 *ppos = pos;
1607 if (written)
1608 err = written;
1609out:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001610 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 return err;
1612}
1613
1614static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1615{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001616 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001617 struct address_space *mapping = inode->i_mapping;
1618 unsigned long index, offset;
1619
1620 index = *ppos >> PAGE_CACHE_SHIFT;
1621 offset = *ppos & ~PAGE_CACHE_MASK;
1622
1623 for (;;) {
1624 struct page *page = NULL;
1625 unsigned long end_index, nr, ret;
1626 loff_t i_size = i_size_read(inode);
1627
1628 end_index = i_size >> PAGE_CACHE_SHIFT;
1629 if (index > end_index)
1630 break;
1631 if (index == end_index) {
1632 nr = i_size & ~PAGE_CACHE_MASK;
1633 if (nr <= offset)
1634 break;
1635 }
1636
1637 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1638 if (desc->error) {
1639 if (desc->error == -EINVAL)
1640 desc->error = 0;
1641 break;
1642 }
1643
1644 /*
1645 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001646 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001647 */
1648 nr = PAGE_CACHE_SIZE;
1649 i_size = i_size_read(inode);
1650 end_index = i_size >> PAGE_CACHE_SHIFT;
1651 if (index == end_index) {
1652 nr = i_size & ~PAGE_CACHE_MASK;
1653 if (nr <= offset) {
1654 if (page)
1655 page_cache_release(page);
1656 break;
1657 }
1658 }
1659 nr -= offset;
1660
1661 if (page) {
1662 /*
1663 * If users can be writing to this page using arbitrary
1664 * virtual addresses, take care about potential aliasing
1665 * before reading the page on the kernel side.
1666 */
1667 if (mapping_writably_mapped(mapping))
1668 flush_dcache_page(page);
1669 /*
1670 * Mark the page accessed if we read the beginning.
1671 */
1672 if (!offset)
1673 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001674 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001676 page_cache_get(page);
1677 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678
1679 /*
1680 * Ok, we have the page, and it's up-to-date, so
1681 * now we can copy it to user space...
1682 *
1683 * The actor routine returns how many bytes were actually used..
1684 * NOTE! This may not be the same as how much of a user buffer
1685 * we filled up (we may be padding etc), so we can only update
1686 * "pos" here (the actor routine has to update the user buffer
1687 * pointers and the remaining count).
1688 */
1689 ret = actor(desc, page, offset, nr);
1690 offset += ret;
1691 index += offset >> PAGE_CACHE_SHIFT;
1692 offset &= ~PAGE_CACHE_MASK;
1693
1694 page_cache_release(page);
1695 if (ret != nr || !desc->count)
1696 break;
1697
1698 cond_resched();
1699 }
1700
1701 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1702 file_accessed(filp);
1703}
1704
1705static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1706{
1707 read_descriptor_t desc;
1708
1709 if ((ssize_t) count < 0)
1710 return -EINVAL;
1711 if (!access_ok(VERIFY_WRITE, buf, count))
1712 return -EFAULT;
1713 if (!count)
1714 return 0;
1715
1716 desc.written = 0;
1717 desc.count = count;
1718 desc.arg.buf = buf;
1719 desc.error = 0;
1720
1721 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1722 if (desc.written)
1723 return desc.written;
1724 return desc.error;
1725}
1726
David Howells726c3342006-06-23 02:02:58 -07001727static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728{
David Howells726c3342006-06-23 02:02:58 -07001729 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001730
1731 buf->f_type = TMPFS_MAGIC;
1732 buf->f_bsize = PAGE_CACHE_SIZE;
1733 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001734 spin_lock(&sbinfo->stat_lock);
1735 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 buf->f_blocks = sbinfo->max_blocks;
1737 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001738 }
1739 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001740 buf->f_files = sbinfo->max_inodes;
1741 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001742 }
1743 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001744 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001745 return 0;
1746}
1747
1748/*
1749 * File creation. Allocate an inode, and we're done..
1750 */
1751static int
1752shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1753{
1754 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1755 int error = -ENOSPC;
1756
1757 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001758 error = security_inode_init_security(inode, dir, NULL, NULL,
1759 NULL);
1760 if (error) {
1761 if (error != -EOPNOTSUPP) {
1762 iput(inode);
1763 return error;
1764 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001765 }
1766 error = shmem_acl_init(inode, dir);
1767 if (error) {
1768 iput(inode);
1769 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001770 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 if (dir->i_mode & S_ISGID) {
1772 inode->i_gid = dir->i_gid;
1773 if (S_ISDIR(mode))
1774 inode->i_mode |= S_ISGID;
1775 }
1776 dir->i_size += BOGO_DIRENT_SIZE;
1777 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1778 d_instantiate(dentry, inode);
1779 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780 }
1781 return error;
1782}
1783
1784static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1785{
1786 int error;
1787
1788 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1789 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001790 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001791 return 0;
1792}
1793
1794static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1795 struct nameidata *nd)
1796{
1797 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1798}
1799
1800/*
1801 * Link a file..
1802 */
1803static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1804{
1805 struct inode *inode = old_dentry->d_inode;
1806 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1807
1808 /*
1809 * No ordinary (disk based) filesystem counts links as inodes;
1810 * but each new link needs a new dentry, pinning lowmem, and
1811 * tmpfs dentries cannot be pruned until they are unlinked.
1812 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001813 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001814 spin_lock(&sbinfo->stat_lock);
1815 if (!sbinfo->free_inodes) {
1816 spin_unlock(&sbinfo->stat_lock);
1817 return -ENOSPC;
1818 }
1819 sbinfo->free_inodes--;
1820 spin_unlock(&sbinfo->stat_lock);
1821 }
1822
1823 dir->i_size += BOGO_DIRENT_SIZE;
1824 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001825 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001826 atomic_inc(&inode->i_count); /* New dentry reference */
1827 dget(dentry); /* Extra pinning count for the created dentry */
1828 d_instantiate(dentry, inode);
1829 return 0;
1830}
1831
1832static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1833{
1834 struct inode *inode = dentry->d_inode;
1835
1836 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1837 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001838 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 spin_lock(&sbinfo->stat_lock);
1840 sbinfo->free_inodes++;
1841 spin_unlock(&sbinfo->stat_lock);
1842 }
1843 }
1844
1845 dir->i_size -= BOGO_DIRENT_SIZE;
1846 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001847 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001848 dput(dentry); /* Undo the count from "create" - this does all the work */
1849 return 0;
1850}
1851
1852static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1853{
1854 if (!simple_empty(dentry))
1855 return -ENOTEMPTY;
1856
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001857 drop_nlink(dentry->d_inode);
1858 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859 return shmem_unlink(dir, dentry);
1860}
1861
1862/*
1863 * The VFS layer already does all the dentry stuff for rename,
1864 * we just have to decrement the usage count for the target if
1865 * it exists so that the VFS layer correctly free's it when it
1866 * gets overwritten.
1867 */
1868static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1869{
1870 struct inode *inode = old_dentry->d_inode;
1871 int they_are_dirs = S_ISDIR(inode->i_mode);
1872
1873 if (!simple_empty(new_dentry))
1874 return -ENOTEMPTY;
1875
1876 if (new_dentry->d_inode) {
1877 (void) shmem_unlink(new_dir, new_dentry);
1878 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001879 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001880 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001881 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001882 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001883 }
1884
1885 old_dir->i_size -= BOGO_DIRENT_SIZE;
1886 new_dir->i_size += BOGO_DIRENT_SIZE;
1887 old_dir->i_ctime = old_dir->i_mtime =
1888 new_dir->i_ctime = new_dir->i_mtime =
1889 inode->i_ctime = CURRENT_TIME;
1890 return 0;
1891}
1892
1893static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1894{
1895 int error;
1896 int len;
1897 struct inode *inode;
1898 struct page *page = NULL;
1899 char *kaddr;
1900 struct shmem_inode_info *info;
1901
1902 len = strlen(symname) + 1;
1903 if (len > PAGE_CACHE_SIZE)
1904 return -ENAMETOOLONG;
1905
1906 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1907 if (!inode)
1908 return -ENOSPC;
1909
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001910 error = security_inode_init_security(inode, dir, NULL, NULL,
1911 NULL);
1912 if (error) {
1913 if (error != -EOPNOTSUPP) {
1914 iput(inode);
1915 return error;
1916 }
1917 error = 0;
1918 }
1919
Linus Torvalds1da177e2005-04-16 15:20:36 -07001920 info = SHMEM_I(inode);
1921 inode->i_size = len-1;
1922 if (len <= (char *)inode - (char *)info) {
1923 /* do it inline */
1924 memcpy(info, symname, len);
1925 inode->i_op = &shmem_symlink_inline_operations;
1926 } else {
1927 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1928 if (error) {
1929 iput(inode);
1930 return error;
1931 }
1932 inode->i_op = &shmem_symlink_inode_operations;
1933 kaddr = kmap_atomic(page, KM_USER0);
1934 memcpy(kaddr, symname, len);
1935 kunmap_atomic(kaddr, KM_USER0);
1936 set_page_dirty(page);
1937 page_cache_release(page);
1938 }
1939 if (dir->i_mode & S_ISGID)
1940 inode->i_gid = dir->i_gid;
1941 dir->i_size += BOGO_DIRENT_SIZE;
1942 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1943 d_instantiate(dentry, inode);
1944 dget(dentry);
1945 return 0;
1946}
1947
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001948static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001949{
1950 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001951 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001952}
1953
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001954static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955{
1956 struct page *page = NULL;
1957 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1958 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001959 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001960}
1961
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001962static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001963{
1964 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001965 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966 kunmap(page);
1967 mark_page_accessed(page);
1968 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001969 }
1970}
1971
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001972static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001973 .readlink = generic_readlink,
1974 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001975};
1976
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001977static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978 .truncate = shmem_truncate,
1979 .readlink = generic_readlink,
1980 .follow_link = shmem_follow_link,
1981 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001982};
1983
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001984#ifdef CONFIG_TMPFS_POSIX_ACL
1985/**
1986 * Superblocks without xattr inode operations will get security.* xattr
1987 * support from the VFS "for free". As soon as we have any other xattrs
1988 * like ACLs, we also need to implement the security.* handlers at
1989 * filesystem level, though.
1990 */
1991
1992static size_t shmem_xattr_security_list(struct inode *inode, char *list,
1993 size_t list_len, const char *name,
1994 size_t name_len)
1995{
1996 return security_inode_listsecurity(inode, list, list_len);
1997}
1998
1999static int shmem_xattr_security_get(struct inode *inode, const char *name,
2000 void *buffer, size_t size)
2001{
2002 if (strcmp(name, "") == 0)
2003 return -EINVAL;
2004 return security_inode_getsecurity(inode, name, buffer, size,
2005 -EOPNOTSUPP);
2006}
2007
2008static int shmem_xattr_security_set(struct inode *inode, const char *name,
2009 const void *value, size_t size, int flags)
2010{
2011 if (strcmp(name, "") == 0)
2012 return -EINVAL;
2013 return security_inode_setsecurity(inode, name, value, size, flags);
2014}
2015
Adrian Bunk1f370a22006-12-06 20:38:21 -08002016static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002017 .prefix = XATTR_SECURITY_PREFIX,
2018 .list = shmem_xattr_security_list,
2019 .get = shmem_xattr_security_get,
2020 .set = shmem_xattr_security_set,
2021};
2022
2023static struct xattr_handler *shmem_xattr_handlers[] = {
2024 &shmem_xattr_acl_access_handler,
2025 &shmem_xattr_acl_default_handler,
2026 &shmem_xattr_security_handler,
2027 NULL
2028};
2029#endif
2030
David M. Grimes91828a42006-10-17 00:09:45 -07002031static struct dentry *shmem_get_parent(struct dentry *child)
2032{
2033 return ERR_PTR(-ESTALE);
2034}
2035
2036static int shmem_match(struct inode *ino, void *vfh)
2037{
2038 __u32 *fh = vfh;
2039 __u64 inum = fh[2];
2040 inum = (inum << 32) | fh[1];
2041 return ino->i_ino == inum && fh[0] == ino->i_generation;
2042}
2043
2044static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
2045{
2046 struct dentry *de = NULL;
2047 struct inode *inode;
2048 __u32 *fh = vfh;
2049 __u64 inum = fh[2];
2050 inum = (inum << 32) | fh[1];
2051
2052 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
2053 if (inode) {
2054 de = d_find_alias(inode);
2055 iput(inode);
2056 }
2057
2058 return de? de: ERR_PTR(-ESTALE);
2059}
2060
2061static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
2062 int len, int type,
2063 int (*acceptable)(void *context, struct dentry *de),
2064 void *context)
2065{
2066 if (len < 3)
2067 return ERR_PTR(-ESTALE);
2068
2069 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
2070 context);
2071}
2072
2073static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2074 int connectable)
2075{
2076 struct inode *inode = dentry->d_inode;
2077
2078 if (*len < 3)
2079 return 255;
2080
2081 if (hlist_unhashed(&inode->i_hash)) {
2082 /* Unfortunately insert_inode_hash is not idempotent,
2083 * so as we hash inodes here rather than at creation
2084 * time, we need a lock to ensure we only try
2085 * to do it once
2086 */
2087 static DEFINE_SPINLOCK(lock);
2088 spin_lock(&lock);
2089 if (hlist_unhashed(&inode->i_hash))
2090 __insert_inode_hash(inode,
2091 inode->i_ino + inode->i_generation);
2092 spin_unlock(&lock);
2093 }
2094
2095 fh[0] = inode->i_generation;
2096 fh[1] = inode->i_ino;
2097 fh[2] = ((__u64)inode->i_ino) >> 32;
2098
2099 *len = 3;
2100 return 1;
2101}
2102
2103static struct export_operations shmem_export_ops = {
2104 .get_parent = shmem_get_parent,
2105 .get_dentry = shmem_get_dentry,
2106 .encode_fh = shmem_encode_fh,
2107 .decode_fh = shmem_decode_fh,
2108};
2109
Robin Holt7339ff82006-01-14 13:20:48 -08002110static int shmem_parse_options(char *options, int *mode, uid_t *uid,
2111 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
2112 int *policy, nodemask_t *policy_nodes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113{
2114 char *this_char, *value, *rest;
2115
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002116 while (options != NULL) {
2117 this_char = options;
2118 for (;;) {
2119 /*
2120 * NUL-terminate this option: unfortunately,
2121 * mount options form a comma-separated list,
2122 * but mpol's nodelist may also contain commas.
2123 */
2124 options = strchr(options, ',');
2125 if (options == NULL)
2126 break;
2127 options++;
2128 if (!isdigit(*options)) {
2129 options[-1] = '\0';
2130 break;
2131 }
2132 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 if (!*this_char)
2134 continue;
2135 if ((value = strchr(this_char,'=')) != NULL) {
2136 *value++ = 0;
2137 } else {
2138 printk(KERN_ERR
2139 "tmpfs: No value for mount option '%s'\n",
2140 this_char);
2141 return 1;
2142 }
2143
2144 if (!strcmp(this_char,"size")) {
2145 unsigned long long size;
2146 size = memparse(value,&rest);
2147 if (*rest == '%') {
2148 size <<= PAGE_SHIFT;
2149 size *= totalram_pages;
2150 do_div(size, 100);
2151 rest++;
2152 }
2153 if (*rest)
2154 goto bad_val;
2155 *blocks = size >> PAGE_CACHE_SHIFT;
2156 } else if (!strcmp(this_char,"nr_blocks")) {
2157 *blocks = memparse(value,&rest);
2158 if (*rest)
2159 goto bad_val;
2160 } else if (!strcmp(this_char,"nr_inodes")) {
2161 *inodes = memparse(value,&rest);
2162 if (*rest)
2163 goto bad_val;
2164 } else if (!strcmp(this_char,"mode")) {
2165 if (!mode)
2166 continue;
2167 *mode = simple_strtoul(value,&rest,8);
2168 if (*rest)
2169 goto bad_val;
2170 } else if (!strcmp(this_char,"uid")) {
2171 if (!uid)
2172 continue;
2173 *uid = simple_strtoul(value,&rest,0);
2174 if (*rest)
2175 goto bad_val;
2176 } else if (!strcmp(this_char,"gid")) {
2177 if (!gid)
2178 continue;
2179 *gid = simple_strtoul(value,&rest,0);
2180 if (*rest)
2181 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002182 } else if (!strcmp(this_char,"mpol")) {
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002183 if (shmem_parse_mpol(value,policy,policy_nodes))
Robin Holt7339ff82006-01-14 13:20:48 -08002184 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002185 } else {
2186 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2187 this_char);
2188 return 1;
2189 }
2190 }
2191 return 0;
2192
2193bad_val:
2194 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2195 value, this_char);
2196 return 1;
2197
2198}
2199
2200static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2201{
2202 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002203 unsigned long max_blocks = sbinfo->max_blocks;
2204 unsigned long max_inodes = sbinfo->max_inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002205 int policy = sbinfo->policy;
2206 nodemask_t policy_nodes = sbinfo->policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002207 unsigned long blocks;
2208 unsigned long inodes;
2209 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002210
Robin Holt7339ff82006-01-14 13:20:48 -08002211 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2212 &max_inodes, &policy, &policy_nodes))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002213 return error;
2214
2215 spin_lock(&sbinfo->stat_lock);
2216 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2217 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2218 if (max_blocks < blocks)
2219 goto out;
2220 if (max_inodes < inodes)
2221 goto out;
2222 /*
2223 * Those tests also disallow limited->unlimited while any are in
2224 * use, so i_blocks will always be zero when max_blocks is zero;
2225 * but we must separately disallow unlimited->limited, because
2226 * in that case we have no record of how much is already in use.
2227 */
2228 if (max_blocks && !sbinfo->max_blocks)
2229 goto out;
2230 if (max_inodes && !sbinfo->max_inodes)
2231 goto out;
2232
2233 error = 0;
2234 sbinfo->max_blocks = max_blocks;
2235 sbinfo->free_blocks = max_blocks - blocks;
2236 sbinfo->max_inodes = max_inodes;
2237 sbinfo->free_inodes = max_inodes - inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002238 sbinfo->policy = policy;
2239 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002240out:
2241 spin_unlock(&sbinfo->stat_lock);
2242 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002243}
2244#endif
2245
2246static void shmem_put_super(struct super_block *sb)
2247{
2248 kfree(sb->s_fs_info);
2249 sb->s_fs_info = NULL;
2250}
2251
Linus Torvalds1da177e2005-04-16 15:20:36 -07002252static int shmem_fill_super(struct super_block *sb,
2253 void *data, int silent)
2254{
2255 struct inode *inode;
2256 struct dentry *root;
2257 int mode = S_IRWXUGO | S_ISVTX;
2258 uid_t uid = current->fsuid;
2259 gid_t gid = current->fsgid;
2260 int err = -ENOMEM;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002261 struct shmem_sb_info *sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002262 unsigned long blocks = 0;
2263 unsigned long inodes = 0;
Robin Holt7339ff82006-01-14 13:20:48 -08002264 int policy = MPOL_DEFAULT;
2265 nodemask_t policy_nodes = node_online_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002266
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002267#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002268 /*
2269 * Per default we only allow half of the physical ram per
2270 * tmpfs instance, limiting inodes to one per page of lowmem;
2271 * but the internal instance is left unlimited.
2272 */
2273 if (!(sb->s_flags & MS_NOUSER)) {
2274 blocks = totalram_pages / 2;
2275 inodes = totalram_pages - totalhigh_pages;
2276 if (inodes > blocks)
2277 inodes = blocks;
Robin Holt7339ff82006-01-14 13:20:48 -08002278 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2279 &inodes, &policy, &policy_nodes))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002280 return -EINVAL;
2281 }
David M. Grimes91828a42006-10-17 00:09:45 -07002282 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002283#else
2284 sb->s_flags |= MS_NOUSER;
2285#endif
2286
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002287 /* Round up to L1_CACHE_BYTES to resist false sharing */
2288 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2289 L1_CACHE_BYTES), GFP_KERNEL);
2290 if (!sbinfo)
2291 return -ENOMEM;
2292
2293 spin_lock_init(&sbinfo->stat_lock);
2294 sbinfo->max_blocks = blocks;
2295 sbinfo->free_blocks = blocks;
2296 sbinfo->max_inodes = inodes;
2297 sbinfo->free_inodes = inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002298 sbinfo->policy = policy;
2299 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002300
2301 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002302 sb->s_maxbytes = SHMEM_MAX_BYTES;
2303 sb->s_blocksize = PAGE_CACHE_SIZE;
2304 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2305 sb->s_magic = TMPFS_MAGIC;
2306 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002307 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002308#ifdef CONFIG_TMPFS_POSIX_ACL
2309 sb->s_xattr = shmem_xattr_handlers;
2310 sb->s_flags |= MS_POSIXACL;
2311#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002312
Linus Torvalds1da177e2005-04-16 15:20:36 -07002313 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2314 if (!inode)
2315 goto failed;
2316 inode->i_uid = uid;
2317 inode->i_gid = gid;
2318 root = d_alloc_root(inode);
2319 if (!root)
2320 goto failed_iput;
2321 sb->s_root = root;
2322 return 0;
2323
2324failed_iput:
2325 iput(inode);
2326failed:
2327 shmem_put_super(sb);
2328 return err;
2329}
2330
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002331static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002332
2333static struct inode *shmem_alloc_inode(struct super_block *sb)
2334{
2335 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002336 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002337 if (!p)
2338 return NULL;
2339 return &p->vfs_inode;
2340}
2341
2342static void shmem_destroy_inode(struct inode *inode)
2343{
2344 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2345 /* only struct inode is valid if it's an inline symlink */
2346 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2347 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002348 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002349 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2350}
2351
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002352static void init_once(void *foo, struct kmem_cache *cachep,
2353 unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002354{
2355 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2356
Christoph Lametera35afb82007-05-16 22:10:57 -07002357 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002358#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002359 p->i_acl = NULL;
2360 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002361#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002362}
2363
2364static int init_inodecache(void)
2365{
2366 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2367 sizeof(struct shmem_inode_info),
2368 0, 0, init_once, NULL);
2369 if (shmem_inode_cachep == NULL)
2370 return -ENOMEM;
2371 return 0;
2372}
2373
2374static void destroy_inodecache(void)
2375{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002376 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002377}
2378
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002379static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002380 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002381 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002382#ifdef CONFIG_TMPFS
Hugh Dickinsae976412007-06-04 10:00:39 +02002383 .readpage = shmem_readpage,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002384 .prepare_write = shmem_prepare_write,
2385 .commit_write = simple_commit_write,
2386#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002387 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002388};
2389
Helge Deller15ad7cd2006-12-06 20:40:36 -08002390static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002391 .mmap = shmem_mmap,
2392#ifdef CONFIG_TMPFS
2393 .llseek = generic_file_llseek,
2394 .read = shmem_file_read,
2395 .write = shmem_file_write,
2396 .fsync = simple_sync_file,
Hugh Dickinsae976412007-06-04 10:00:39 +02002397 .splice_read = generic_file_splice_read,
2398 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002399#endif
2400};
2401
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002402static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403 .truncate = shmem_truncate,
2404 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002405 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002406#ifdef CONFIG_TMPFS_POSIX_ACL
2407 .setxattr = generic_setxattr,
2408 .getxattr = generic_getxattr,
2409 .listxattr = generic_listxattr,
2410 .removexattr = generic_removexattr,
2411 .permission = shmem_permission,
2412#endif
2413
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414};
2415
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002416static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002417#ifdef CONFIG_TMPFS
2418 .create = shmem_create,
2419 .lookup = simple_lookup,
2420 .link = shmem_link,
2421 .unlink = shmem_unlink,
2422 .symlink = shmem_symlink,
2423 .mkdir = shmem_mkdir,
2424 .rmdir = shmem_rmdir,
2425 .mknod = shmem_mknod,
2426 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002427#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002428#ifdef CONFIG_TMPFS_POSIX_ACL
2429 .setattr = shmem_notify_change,
2430 .setxattr = generic_setxattr,
2431 .getxattr = generic_getxattr,
2432 .listxattr = generic_listxattr,
2433 .removexattr = generic_removexattr,
2434 .permission = shmem_permission,
2435#endif
2436};
2437
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002438static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002439#ifdef CONFIG_TMPFS_POSIX_ACL
2440 .setattr = shmem_notify_change,
2441 .setxattr = generic_setxattr,
2442 .getxattr = generic_getxattr,
2443 .listxattr = generic_listxattr,
2444 .removexattr = generic_removexattr,
2445 .permission = shmem_permission,
2446#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002447};
2448
Hugh Dickins759b9772007-03-05 00:30:28 -08002449static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002450 .alloc_inode = shmem_alloc_inode,
2451 .destroy_inode = shmem_destroy_inode,
2452#ifdef CONFIG_TMPFS
2453 .statfs = shmem_statfs,
2454 .remount_fs = shmem_remount_fs,
2455#endif
2456 .delete_inode = shmem_delete_inode,
2457 .drop_inode = generic_delete_inode,
2458 .put_super = shmem_put_super,
2459};
2460
2461static struct vm_operations_struct shmem_vm_ops = {
2462 .nopage = shmem_nopage,
2463 .populate = shmem_populate,
2464#ifdef CONFIG_NUMA
2465 .set_policy = shmem_set_policy,
2466 .get_policy = shmem_get_policy,
2467#endif
2468};
2469
2470
David Howells454e2392006-06-23 02:02:57 -07002471static int shmem_get_sb(struct file_system_type *fs_type,
2472 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002473{
David Howells454e2392006-06-23 02:02:57 -07002474 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002475}
2476
2477static struct file_system_type tmpfs_fs_type = {
2478 .owner = THIS_MODULE,
2479 .name = "tmpfs",
2480 .get_sb = shmem_get_sb,
2481 .kill_sb = kill_litter_super,
2482};
2483static struct vfsmount *shm_mnt;
2484
2485static int __init init_tmpfs(void)
2486{
2487 int error;
2488
2489 error = init_inodecache();
2490 if (error)
2491 goto out3;
2492
2493 error = register_filesystem(&tmpfs_fs_type);
2494 if (error) {
2495 printk(KERN_ERR "Could not register tmpfs\n");
2496 goto out2;
2497 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002498
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002499 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500 tmpfs_fs_type.name, NULL);
2501 if (IS_ERR(shm_mnt)) {
2502 error = PTR_ERR(shm_mnt);
2503 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2504 goto out1;
2505 }
2506 return 0;
2507
2508out1:
2509 unregister_filesystem(&tmpfs_fs_type);
2510out2:
2511 destroy_inodecache();
2512out3:
2513 shm_mnt = ERR_PTR(error);
2514 return error;
2515}
2516module_init(init_tmpfs)
2517
2518/*
2519 * shmem_file_setup - get an unlinked file living in tmpfs
2520 *
2521 * @name: name for dentry (to be seen in /proc/<pid>/maps
2522 * @size: size to be set for the file
2523 *
2524 */
2525struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2526{
2527 int error;
2528 struct file *file;
2529 struct inode *inode;
2530 struct dentry *dentry, *root;
2531 struct qstr this;
2532
2533 if (IS_ERR(shm_mnt))
2534 return (void *)shm_mnt;
2535
2536 if (size < 0 || size > SHMEM_MAX_BYTES)
2537 return ERR_PTR(-EINVAL);
2538
2539 if (shmem_acct_size(flags, size))
2540 return ERR_PTR(-ENOMEM);
2541
2542 error = -ENOMEM;
2543 this.name = name;
2544 this.len = strlen(name);
2545 this.hash = 0; /* will go */
2546 root = shm_mnt->mnt_root;
2547 dentry = d_alloc(root, &this);
2548 if (!dentry)
2549 goto put_memory;
2550
2551 error = -ENFILE;
2552 file = get_empty_filp();
2553 if (!file)
2554 goto put_dentry;
2555
2556 error = -ENOSPC;
2557 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2558 if (!inode)
2559 goto close_file;
2560
2561 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2562 d_instantiate(dentry, inode);
2563 inode->i_size = size;
2564 inode->i_nlink = 0; /* It is unlinked */
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002565 file->f_path.mnt = mntget(shm_mnt);
2566 file->f_path.dentry = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002567 file->f_mapping = inode->i_mapping;
2568 file->f_op = &shmem_file_operations;
2569 file->f_mode = FMODE_WRITE | FMODE_READ;
2570 return file;
2571
2572close_file:
2573 put_filp(file);
2574put_dentry:
2575 dput(dentry);
2576put_memory:
2577 shmem_unacct_size(flags, size);
2578 return ERR_PTR(error);
2579}
2580
2581/*
2582 * shmem_zero_setup - setup a shared anonymous mapping
2583 *
2584 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2585 */
2586int shmem_zero_setup(struct vm_area_struct *vma)
2587{
2588 struct file *file;
2589 loff_t size = vma->vm_end - vma->vm_start;
2590
2591 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2592 if (IS_ERR(file))
2593 return PTR_ERR(file);
2594
2595 if (vma->vm_file)
2596 fput(vma->vm_file);
2597 vma->vm_file = file;
2598 vma->vm_ops = &shmem_vm_ops;
2599 return 0;
2600}