blob: 2c39925fe073c837f9120712e00580bb00250e93 [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>
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -070052
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#include <asm/uaccess.h>
54#include <asm/div64.h>
55#include <asm/pgtable.h>
56
57/* This magic number is used in glibc for posix shared memory */
58#define TMPFS_MAGIC 0x01021994
59
60#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
61#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
62#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
63
64#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
65#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
66
67#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
68
69/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
70#define SHMEM_PAGEIN VM_READ
71#define SHMEM_TRUNCATE VM_WRITE
72
73/* Definition to limit shmem_truncate's steps between cond_rescheds */
74#define LATENCY_LIMIT 64
75
76/* Pretend that each entry is of this size in directory's i_size */
77#define BOGO_DIRENT_SIZE 20
78
Linus Torvalds1da177e2005-04-16 15:20:36 -070079/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
80enum sgp_type {
81 SGP_QUICK, /* don't try more than file page cache lookup */
82 SGP_READ, /* don't exceed i_size, don't allocate page */
83 SGP_CACHE, /* don't exceed i_size, may allocate page */
84 SGP_WRITE, /* may exceed i_size, may allocate page */
Nick Piggin54cb8822007-07-19 01:46:59 -070085 SGP_FAULT, /* same as SGP_CACHE, return with page locked */
Linus Torvalds1da177e2005-04-16 15:20:36 -070086};
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;
Nick Piggin54cb8822007-07-19 01:46:59 -07001103
1104 if (type)
Nick Piggin83c54072007-07-19 01:47:05 -07001105 *type = 0;
Nick Piggin54cb8822007-07-19 01:46:59 -07001106
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107 /*
1108 * Normally, filepage is NULL on entry, and either found
1109 * uptodate immediately, or allocated and zeroed, or read
1110 * in under swappage, which is then assigned to filepage.
Hugh Dickinsae9764162007-06-04 10:00:39 +02001111 * But shmem_readpage and shmem_prepare_write pass in a locked
1112 * filepage, which may be found not uptodate by other callers
1113 * too, and may need to be copied from the swappage read in.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 */
1115repeat:
1116 if (!filepage)
1117 filepage = find_lock_page(mapping, idx);
1118 if (filepage && PageUptodate(filepage))
1119 goto done;
1120 error = 0;
1121 if (sgp == SGP_QUICK)
1122 goto failed;
1123
1124 spin_lock(&info->lock);
1125 shmem_recalc_inode(inode);
1126 entry = shmem_swp_alloc(info, idx, sgp);
1127 if (IS_ERR(entry)) {
1128 spin_unlock(&info->lock);
1129 error = PTR_ERR(entry);
1130 goto failed;
1131 }
1132 swap = *entry;
1133
1134 if (swap.val) {
1135 /* Look it up and read it in.. */
1136 swappage = lookup_swap_cache(swap);
1137 if (!swappage) {
1138 shmem_swp_unmap(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139 /* here we actually do the io */
Nick Piggin83c54072007-07-19 01:47:05 -07001140 if (type && !(*type & VM_FAULT_MAJOR)) {
Christoph Lameterf8891e52006-06-30 01:55:45 -07001141 __count_vm_event(PGMAJFAULT);
Nick Piggin83c54072007-07-19 01:47:05 -07001142 *type |= VM_FAULT_MAJOR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001143 }
Christoph Lameterf8891e52006-06-30 01:55:45 -07001144 spin_unlock(&info->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001145 swappage = shmem_swapin(info, swap, idx);
1146 if (!swappage) {
1147 spin_lock(&info->lock);
1148 entry = shmem_swp_alloc(info, idx, sgp);
1149 if (IS_ERR(entry))
1150 error = PTR_ERR(entry);
1151 else {
1152 if (entry->val == swap.val)
1153 error = -ENOMEM;
1154 shmem_swp_unmap(entry);
1155 }
1156 spin_unlock(&info->lock);
1157 if (error)
1158 goto failed;
1159 goto repeat;
1160 }
1161 wait_on_page_locked(swappage);
1162 page_cache_release(swappage);
1163 goto repeat;
1164 }
1165
1166 /* We have to do this with page locked to prevent races */
1167 if (TestSetPageLocked(swappage)) {
1168 shmem_swp_unmap(entry);
1169 spin_unlock(&info->lock);
1170 wait_on_page_locked(swappage);
1171 page_cache_release(swappage);
1172 goto repeat;
1173 }
1174 if (PageWriteback(swappage)) {
1175 shmem_swp_unmap(entry);
1176 spin_unlock(&info->lock);
1177 wait_on_page_writeback(swappage);
1178 unlock_page(swappage);
1179 page_cache_release(swappage);
1180 goto repeat;
1181 }
1182 if (!PageUptodate(swappage)) {
1183 shmem_swp_unmap(entry);
1184 spin_unlock(&info->lock);
1185 unlock_page(swappage);
1186 page_cache_release(swappage);
1187 error = -EIO;
1188 goto failed;
1189 }
1190
1191 if (filepage) {
1192 shmem_swp_set(info, entry, 0);
1193 shmem_swp_unmap(entry);
1194 delete_from_swap_cache(swappage);
1195 spin_unlock(&info->lock);
1196 copy_highpage(filepage, swappage);
1197 unlock_page(swappage);
1198 page_cache_release(swappage);
1199 flush_dcache_page(filepage);
1200 SetPageUptodate(filepage);
1201 set_page_dirty(filepage);
1202 swap_free(swap);
1203 } else if (!(error = move_from_swap_cache(
1204 swappage, idx, mapping))) {
1205 info->flags |= SHMEM_PAGEIN;
1206 shmem_swp_set(info, entry, 0);
1207 shmem_swp_unmap(entry);
1208 spin_unlock(&info->lock);
1209 filepage = swappage;
1210 swap_free(swap);
1211 } else {
1212 shmem_swp_unmap(entry);
1213 spin_unlock(&info->lock);
1214 unlock_page(swappage);
1215 page_cache_release(swappage);
1216 if (error == -ENOMEM) {
1217 /* let kswapd refresh zone for GFP_ATOMICs */
Andrew Morton3fcfab12006-10-19 23:28:16 -07001218 congestion_wait(WRITE, HZ/50);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219 }
1220 goto repeat;
1221 }
1222 } else if (sgp == SGP_READ && !filepage) {
1223 shmem_swp_unmap(entry);
1224 filepage = find_get_page(mapping, idx);
1225 if (filepage &&
1226 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1227 spin_unlock(&info->lock);
1228 wait_on_page_locked(filepage);
1229 page_cache_release(filepage);
1230 filepage = NULL;
1231 goto repeat;
1232 }
1233 spin_unlock(&info->lock);
1234 } else {
1235 shmem_swp_unmap(entry);
1236 sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001237 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001238 spin_lock(&sbinfo->stat_lock);
1239 if (sbinfo->free_blocks == 0 ||
1240 shmem_acct_block(info->flags)) {
1241 spin_unlock(&sbinfo->stat_lock);
1242 spin_unlock(&info->lock);
1243 error = -ENOSPC;
1244 goto failed;
1245 }
1246 sbinfo->free_blocks--;
1247 inode->i_blocks += BLOCKS_PER_PAGE;
1248 spin_unlock(&sbinfo->stat_lock);
1249 } else if (shmem_acct_block(info->flags)) {
1250 spin_unlock(&info->lock);
1251 error = -ENOSPC;
1252 goto failed;
1253 }
1254
1255 if (!filepage) {
1256 spin_unlock(&info->lock);
1257 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1258 info,
1259 idx);
1260 if (!filepage) {
1261 shmem_unacct_blocks(info->flags, 1);
1262 shmem_free_blocks(inode, 1);
1263 error = -ENOMEM;
1264 goto failed;
1265 }
1266
1267 spin_lock(&info->lock);
1268 entry = shmem_swp_alloc(info, idx, sgp);
1269 if (IS_ERR(entry))
1270 error = PTR_ERR(entry);
1271 else {
1272 swap = *entry;
1273 shmem_swp_unmap(entry);
1274 }
1275 if (error || swap.val || 0 != add_to_page_cache_lru(
1276 filepage, mapping, idx, GFP_ATOMIC)) {
1277 spin_unlock(&info->lock);
1278 page_cache_release(filepage);
1279 shmem_unacct_blocks(info->flags, 1);
1280 shmem_free_blocks(inode, 1);
1281 filepage = NULL;
1282 if (error)
1283 goto failed;
1284 goto repeat;
1285 }
1286 info->flags |= SHMEM_PAGEIN;
1287 }
1288
1289 info->alloced++;
1290 spin_unlock(&info->lock);
1291 flush_dcache_page(filepage);
1292 SetPageUptodate(filepage);
1293 }
1294done:
1295 if (*pagep != filepage) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296 *pagep = filepage;
Nick Piggin54cb8822007-07-19 01:46:59 -07001297 if (sgp != SGP_FAULT)
Nick Piggind00806b2007-07-19 01:46:57 -07001298 unlock_page(filepage);
1299
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300 }
1301 return 0;
1302
1303failed:
1304 if (*pagep != filepage) {
1305 unlock_page(filepage);
1306 page_cache_release(filepage);
1307 }
1308 return error;
1309}
1310
Nick Piggind0217ac2007-07-19 01:47:03 -07001311static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001312{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001313 struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001314 int error;
Nick Piggind0217ac2007-07-19 01:47:03 -07001315 int ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001316
Nick Piggind0217ac2007-07-19 01:47:03 -07001317 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1318 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07001319
Nick Piggind0217ac2007-07-19 01:47:03 -07001320 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_FAULT, &ret);
1321 if (error)
1322 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001323
Nick Piggind0217ac2007-07-19 01:47:03 -07001324 mark_page_accessed(vmf->page);
Nick Piggin83c54072007-07-19 01:47:05 -07001325 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001326}
1327
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328#ifdef CONFIG_NUMA
1329int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1330{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001331 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1333}
1334
1335struct mempolicy *
1336shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1337{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001338 struct inode *i = vma->vm_file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001339 unsigned long idx;
1340
1341 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1342 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1343}
1344#endif
1345
1346int shmem_lock(struct file *file, int lock, struct user_struct *user)
1347{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001348 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001349 struct shmem_inode_info *info = SHMEM_I(inode);
1350 int retval = -ENOMEM;
1351
1352 spin_lock(&info->lock);
1353 if (lock && !(info->flags & VM_LOCKED)) {
1354 if (!user_shm_lock(inode->i_size, user))
1355 goto out_nomem;
1356 info->flags |= VM_LOCKED;
1357 }
1358 if (!lock && (info->flags & VM_LOCKED) && user) {
1359 user_shm_unlock(inode->i_size, user);
1360 info->flags &= ~VM_LOCKED;
1361 }
1362 retval = 0;
1363out_nomem:
1364 spin_unlock(&info->lock);
1365 return retval;
1366}
1367
Adrian Bunk9b83a6a2007-02-28 20:11:03 -08001368static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369{
1370 file_accessed(file);
1371 vma->vm_ops = &shmem_vm_ops;
Nick Piggind0217ac2007-07-19 01:47:03 -07001372 vma->vm_flags |= VM_CAN_NONLINEAR;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373 return 0;
1374}
1375
1376static struct inode *
1377shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1378{
1379 struct inode *inode;
1380 struct shmem_inode_info *info;
1381 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1382
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001383 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001384 spin_lock(&sbinfo->stat_lock);
1385 if (!sbinfo->free_inodes) {
1386 spin_unlock(&sbinfo->stat_lock);
1387 return NULL;
1388 }
1389 sbinfo->free_inodes--;
1390 spin_unlock(&sbinfo->stat_lock);
1391 }
1392
1393 inode = new_inode(sb);
1394 if (inode) {
1395 inode->i_mode = mode;
1396 inode->i_uid = current->fsuid;
1397 inode->i_gid = current->fsgid;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 inode->i_blocks = 0;
1399 inode->i_mapping->a_ops = &shmem_aops;
1400 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1401 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
David M. Grimes91828a42006-10-17 00:09:45 -07001402 inode->i_generation = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403 info = SHMEM_I(inode);
1404 memset(info, 0, (char *)inode - (char *)info);
1405 spin_lock_init(&info->lock);
1406 INIT_LIST_HEAD(&info->swaplist);
1407
1408 switch (mode & S_IFMT) {
1409 default:
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001410 inode->i_op = &shmem_special_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411 init_special_inode(inode, mode, dev);
1412 break;
1413 case S_IFREG:
1414 inode->i_op = &shmem_inode_operations;
1415 inode->i_fop = &shmem_file_operations;
Robin Holt7339ff82006-01-14 13:20:48 -08001416 mpol_shared_policy_init(&info->policy, sbinfo->policy,
1417 &sbinfo->policy_nodes);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 break;
1419 case S_IFDIR:
Dave Hansend8c76e62006-09-30 23:29:04 -07001420 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421 /* Some things misbehave if size == 0 on a directory */
1422 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1423 inode->i_op = &shmem_dir_inode_operations;
1424 inode->i_fop = &simple_dir_operations;
1425 break;
1426 case S_IFLNK:
1427 /*
1428 * Must not load anything in the rbtree,
1429 * mpol_free_shared_policy will not be called.
1430 */
Robin Holt7339ff82006-01-14 13:20:48 -08001431 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT,
1432 NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001433 break;
1434 }
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001435 } else if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001436 spin_lock(&sbinfo->stat_lock);
1437 sbinfo->free_inodes++;
1438 spin_unlock(&sbinfo->stat_lock);
1439 }
1440 return inode;
1441}
1442
1443#ifdef CONFIG_TMPFS
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001444static const struct inode_operations shmem_symlink_inode_operations;
1445static const struct inode_operations shmem_symlink_inline_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001446
1447/*
Hugh Dickinsae9764162007-06-04 10:00:39 +02001448 * Normally tmpfs avoids the use of shmem_readpage and shmem_prepare_write;
1449 * but providing them allows a tmpfs file to be used for splice, sendfile, and
1450 * below the loop driver, in the generic fashion that many filesystems support.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001451 */
Hugh Dickinsae9764162007-06-04 10:00:39 +02001452static int shmem_readpage(struct file *file, struct page *page)
1453{
1454 struct inode *inode = page->mapping->host;
1455 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
1456 unlock_page(page);
1457 return error;
1458}
1459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460static int
1461shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1462{
1463 struct inode *inode = page->mapping->host;
1464 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1465}
1466
1467static ssize_t
1468shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1469{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001470 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471 loff_t pos;
1472 unsigned long written;
1473 ssize_t err;
1474
1475 if ((ssize_t) count < 0)
1476 return -EINVAL;
1477
1478 if (!access_ok(VERIFY_READ, buf, count))
1479 return -EFAULT;
1480
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001481 mutex_lock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001482
1483 pos = *ppos;
1484 written = 0;
1485
1486 err = generic_write_checks(file, &pos, &count, 0);
1487 if (err || !count)
1488 goto out;
1489
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001490 err = remove_suid(file->f_path.dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001491 if (err)
1492 goto out;
1493
1494 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1495
1496 do {
1497 struct page *page = NULL;
1498 unsigned long bytes, index, offset;
1499 char *kaddr;
1500 int left;
1501
1502 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1503 index = pos >> PAGE_CACHE_SHIFT;
1504 bytes = PAGE_CACHE_SIZE - offset;
1505 if (bytes > count)
1506 bytes = count;
1507
1508 /*
1509 * We don't hold page lock across copy from user -
1510 * what would it guard against? - so no deadlock here.
1511 * But it still may be a good idea to prefault below.
1512 */
1513
1514 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1515 if (err)
1516 break;
1517
1518 left = bytes;
1519 if (PageHighMem(page)) {
1520 volatile unsigned char dummy;
1521 __get_user(dummy, buf);
1522 __get_user(dummy, buf + bytes - 1);
1523
1524 kaddr = kmap_atomic(page, KM_USER0);
1525 left = __copy_from_user_inatomic(kaddr + offset,
1526 buf, bytes);
1527 kunmap_atomic(kaddr, KM_USER0);
1528 }
1529 if (left) {
1530 kaddr = kmap(page);
1531 left = __copy_from_user(kaddr + offset, buf, bytes);
1532 kunmap(page);
1533 }
1534
1535 written += bytes;
1536 count -= bytes;
1537 pos += bytes;
1538 buf += bytes;
1539 if (pos > inode->i_size)
1540 i_size_write(inode, pos);
1541
1542 flush_dcache_page(page);
1543 set_page_dirty(page);
1544 mark_page_accessed(page);
1545 page_cache_release(page);
1546
1547 if (left) {
1548 pos -= left;
1549 written -= left;
1550 err = -EFAULT;
1551 break;
1552 }
1553
1554 /*
1555 * Our dirty pages are not counted in nr_dirty,
1556 * and we do not attempt to balance dirty pages.
1557 */
1558
1559 cond_resched();
1560 } while (count);
1561
1562 *ppos = pos;
1563 if (written)
1564 err = written;
1565out:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001566 mutex_unlock(&inode->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 return err;
1568}
1569
1570static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1571{
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08001572 struct inode *inode = filp->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001573 struct address_space *mapping = inode->i_mapping;
1574 unsigned long index, offset;
1575
1576 index = *ppos >> PAGE_CACHE_SHIFT;
1577 offset = *ppos & ~PAGE_CACHE_MASK;
1578
1579 for (;;) {
1580 struct page *page = NULL;
1581 unsigned long end_index, nr, ret;
1582 loff_t i_size = i_size_read(inode);
1583
1584 end_index = i_size >> PAGE_CACHE_SHIFT;
1585 if (index > end_index)
1586 break;
1587 if (index == end_index) {
1588 nr = i_size & ~PAGE_CACHE_MASK;
1589 if (nr <= offset)
1590 break;
1591 }
1592
1593 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1594 if (desc->error) {
1595 if (desc->error == -EINVAL)
1596 desc->error = 0;
1597 break;
1598 }
1599
1600 /*
1601 * We must evaluate after, since reads (unlike writes)
Jes Sorensen1b1dcc12006-01-09 15:59:24 -08001602 * are called without i_mutex protection against truncate
Linus Torvalds1da177e2005-04-16 15:20:36 -07001603 */
1604 nr = PAGE_CACHE_SIZE;
1605 i_size = i_size_read(inode);
1606 end_index = i_size >> PAGE_CACHE_SHIFT;
1607 if (index == end_index) {
1608 nr = i_size & ~PAGE_CACHE_MASK;
1609 if (nr <= offset) {
1610 if (page)
1611 page_cache_release(page);
1612 break;
1613 }
1614 }
1615 nr -= offset;
1616
1617 if (page) {
1618 /*
1619 * If users can be writing to this page using arbitrary
1620 * virtual addresses, take care about potential aliasing
1621 * before reading the page on the kernel side.
1622 */
1623 if (mapping_writably_mapped(mapping))
1624 flush_dcache_page(page);
1625 /*
1626 * Mark the page accessed if we read the beginning.
1627 */
1628 if (!offset)
1629 mark_page_accessed(page);
Nick Pigginb5810032005-10-29 18:16:12 -07001630 } else {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631 page = ZERO_PAGE(0);
Nick Pigginb5810032005-10-29 18:16:12 -07001632 page_cache_get(page);
1633 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634
1635 /*
1636 * Ok, we have the page, and it's up-to-date, so
1637 * now we can copy it to user space...
1638 *
1639 * The actor routine returns how many bytes were actually used..
1640 * NOTE! This may not be the same as how much of a user buffer
1641 * we filled up (we may be padding etc), so we can only update
1642 * "pos" here (the actor routine has to update the user buffer
1643 * pointers and the remaining count).
1644 */
1645 ret = actor(desc, page, offset, nr);
1646 offset += ret;
1647 index += offset >> PAGE_CACHE_SHIFT;
1648 offset &= ~PAGE_CACHE_MASK;
1649
1650 page_cache_release(page);
1651 if (ret != nr || !desc->count)
1652 break;
1653
1654 cond_resched();
1655 }
1656
1657 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1658 file_accessed(filp);
1659}
1660
1661static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1662{
1663 read_descriptor_t desc;
1664
1665 if ((ssize_t) count < 0)
1666 return -EINVAL;
1667 if (!access_ok(VERIFY_WRITE, buf, count))
1668 return -EFAULT;
1669 if (!count)
1670 return 0;
1671
1672 desc.written = 0;
1673 desc.count = count;
1674 desc.arg.buf = buf;
1675 desc.error = 0;
1676
1677 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1678 if (desc.written)
1679 return desc.written;
1680 return desc.error;
1681}
1682
David Howells726c3342006-06-23 02:02:58 -07001683static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001684{
David Howells726c3342006-06-23 02:02:58 -07001685 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001686
1687 buf->f_type = TMPFS_MAGIC;
1688 buf->f_bsize = PAGE_CACHE_SIZE;
1689 buf->f_namelen = NAME_MAX;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001690 spin_lock(&sbinfo->stat_lock);
1691 if (sbinfo->max_blocks) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001692 buf->f_blocks = sbinfo->max_blocks;
1693 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001694 }
1695 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001696 buf->f_files = sbinfo->max_inodes;
1697 buf->f_ffree = sbinfo->free_inodes;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001698 }
1699 /* else leave those fields 0 like simple_statfs */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001700 spin_unlock(&sbinfo->stat_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001701 return 0;
1702}
1703
1704/*
1705 * File creation. Allocate an inode, and we're done..
1706 */
1707static int
1708shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1709{
1710 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1711 int error = -ENOSPC;
1712
1713 if (inode) {
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001714 error = security_inode_init_security(inode, dir, NULL, NULL,
1715 NULL);
1716 if (error) {
1717 if (error != -EOPNOTSUPP) {
1718 iput(inode);
1719 return error;
1720 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001721 }
1722 error = shmem_acl_init(inode, dir);
1723 if (error) {
1724 iput(inode);
1725 return error;
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001726 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727 if (dir->i_mode & S_ISGID) {
1728 inode->i_gid = dir->i_gid;
1729 if (S_ISDIR(mode))
1730 inode->i_mode |= S_ISGID;
1731 }
1732 dir->i_size += BOGO_DIRENT_SIZE;
1733 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1734 d_instantiate(dentry, inode);
1735 dget(dentry); /* Extra count - pin the dentry in core */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001736 }
1737 return error;
1738}
1739
1740static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1741{
1742 int error;
1743
1744 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1745 return error;
Dave Hansend8c76e62006-09-30 23:29:04 -07001746 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001747 return 0;
1748}
1749
1750static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1751 struct nameidata *nd)
1752{
1753 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1754}
1755
1756/*
1757 * Link a file..
1758 */
1759static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1760{
1761 struct inode *inode = old_dentry->d_inode;
1762 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1763
1764 /*
1765 * No ordinary (disk based) filesystem counts links as inodes;
1766 * but each new link needs a new dentry, pinning lowmem, and
1767 * tmpfs dentries cannot be pruned until they are unlinked.
1768 */
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001769 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001770 spin_lock(&sbinfo->stat_lock);
1771 if (!sbinfo->free_inodes) {
1772 spin_unlock(&sbinfo->stat_lock);
1773 return -ENOSPC;
1774 }
1775 sbinfo->free_inodes--;
1776 spin_unlock(&sbinfo->stat_lock);
1777 }
1778
1779 dir->i_size += BOGO_DIRENT_SIZE;
1780 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansend8c76e62006-09-30 23:29:04 -07001781 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001782 atomic_inc(&inode->i_count); /* New dentry reference */
1783 dget(dentry); /* Extra pinning count for the created dentry */
1784 d_instantiate(dentry, inode);
1785 return 0;
1786}
1787
1788static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1789{
1790 struct inode *inode = dentry->d_inode;
1791
1792 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1793 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07001794 if (sbinfo->max_inodes) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001795 spin_lock(&sbinfo->stat_lock);
1796 sbinfo->free_inodes++;
1797 spin_unlock(&sbinfo->stat_lock);
1798 }
1799 }
1800
1801 dir->i_size -= BOGO_DIRENT_SIZE;
1802 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001803 drop_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001804 dput(dentry); /* Undo the count from "create" - this does all the work */
1805 return 0;
1806}
1807
1808static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1809{
1810 if (!simple_empty(dentry))
1811 return -ENOTEMPTY;
1812
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001813 drop_nlink(dentry->d_inode);
1814 drop_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001815 return shmem_unlink(dir, dentry);
1816}
1817
1818/*
1819 * The VFS layer already does all the dentry stuff for rename,
1820 * we just have to decrement the usage count for the target if
1821 * it exists so that the VFS layer correctly free's it when it
1822 * gets overwritten.
1823 */
1824static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1825{
1826 struct inode *inode = old_dentry->d_inode;
1827 int they_are_dirs = S_ISDIR(inode->i_mode);
1828
1829 if (!simple_empty(new_dentry))
1830 return -ENOTEMPTY;
1831
1832 if (new_dentry->d_inode) {
1833 (void) shmem_unlink(new_dir, new_dentry);
1834 if (they_are_dirs)
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001835 drop_nlink(old_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001836 } else if (they_are_dirs) {
Dave Hansen9a53c3a2006-09-30 23:29:03 -07001837 drop_nlink(old_dir);
Dave Hansend8c76e62006-09-30 23:29:04 -07001838 inc_nlink(new_dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001839 }
1840
1841 old_dir->i_size -= BOGO_DIRENT_SIZE;
1842 new_dir->i_size += BOGO_DIRENT_SIZE;
1843 old_dir->i_ctime = old_dir->i_mtime =
1844 new_dir->i_ctime = new_dir->i_mtime =
1845 inode->i_ctime = CURRENT_TIME;
1846 return 0;
1847}
1848
1849static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1850{
1851 int error;
1852 int len;
1853 struct inode *inode;
1854 struct page *page = NULL;
1855 char *kaddr;
1856 struct shmem_inode_info *info;
1857
1858 len = strlen(symname) + 1;
1859 if (len > PAGE_CACHE_SIZE)
1860 return -ENAMETOOLONG;
1861
1862 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1863 if (!inode)
1864 return -ENOSPC;
1865
Stephen Smalley570bc1c2005-09-09 13:01:43 -07001866 error = security_inode_init_security(inode, dir, NULL, NULL,
1867 NULL);
1868 if (error) {
1869 if (error != -EOPNOTSUPP) {
1870 iput(inode);
1871 return error;
1872 }
1873 error = 0;
1874 }
1875
Linus Torvalds1da177e2005-04-16 15:20:36 -07001876 info = SHMEM_I(inode);
1877 inode->i_size = len-1;
1878 if (len <= (char *)inode - (char *)info) {
1879 /* do it inline */
1880 memcpy(info, symname, len);
1881 inode->i_op = &shmem_symlink_inline_operations;
1882 } else {
1883 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1884 if (error) {
1885 iput(inode);
1886 return error;
1887 }
1888 inode->i_op = &shmem_symlink_inode_operations;
1889 kaddr = kmap_atomic(page, KM_USER0);
1890 memcpy(kaddr, symname, len);
1891 kunmap_atomic(kaddr, KM_USER0);
1892 set_page_dirty(page);
1893 page_cache_release(page);
1894 }
1895 if (dir->i_mode & S_ISGID)
1896 inode->i_gid = dir->i_gid;
1897 dir->i_size += BOGO_DIRENT_SIZE;
1898 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1899 d_instantiate(dentry, inode);
1900 dget(dentry);
1901 return 0;
1902}
1903
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001904static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001905{
1906 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001907 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001908}
1909
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001910static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001911{
1912 struct page *page = NULL;
1913 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1914 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001915 return page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001916}
1917
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001918static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001919{
1920 if (!IS_ERR(nd_get_link(nd))) {
Linus Torvaldscc314ee2005-08-19 18:02:56 -07001921 struct page *page = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001922 kunmap(page);
1923 mark_page_accessed(page);
1924 page_cache_release(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001925 }
1926}
1927
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001928static const struct inode_operations shmem_symlink_inline_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001929 .readlink = generic_readlink,
1930 .follow_link = shmem_follow_link_inline,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001931};
1932
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08001933static const struct inode_operations shmem_symlink_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001934 .truncate = shmem_truncate,
1935 .readlink = generic_readlink,
1936 .follow_link = shmem_follow_link,
1937 .put_link = shmem_put_link,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938};
1939
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001940#ifdef CONFIG_TMPFS_POSIX_ACL
1941/**
1942 * Superblocks without xattr inode operations will get security.* xattr
1943 * support from the VFS "for free". As soon as we have any other xattrs
1944 * like ACLs, we also need to implement the security.* handlers at
1945 * filesystem level, though.
1946 */
1947
1948static size_t shmem_xattr_security_list(struct inode *inode, char *list,
1949 size_t list_len, const char *name,
1950 size_t name_len)
1951{
1952 return security_inode_listsecurity(inode, list, list_len);
1953}
1954
1955static int shmem_xattr_security_get(struct inode *inode, const char *name,
1956 void *buffer, size_t size)
1957{
1958 if (strcmp(name, "") == 0)
1959 return -EINVAL;
1960 return security_inode_getsecurity(inode, name, buffer, size,
1961 -EOPNOTSUPP);
1962}
1963
1964static int shmem_xattr_security_set(struct inode *inode, const char *name,
1965 const void *value, size_t size, int flags)
1966{
1967 if (strcmp(name, "") == 0)
1968 return -EINVAL;
1969 return security_inode_setsecurity(inode, name, value, size, flags);
1970}
1971
Adrian Bunk1f370a22006-12-06 20:38:21 -08001972static struct xattr_handler shmem_xattr_security_handler = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07001973 .prefix = XATTR_SECURITY_PREFIX,
1974 .list = shmem_xattr_security_list,
1975 .get = shmem_xattr_security_get,
1976 .set = shmem_xattr_security_set,
1977};
1978
1979static struct xattr_handler *shmem_xattr_handlers[] = {
1980 &shmem_xattr_acl_access_handler,
1981 &shmem_xattr_acl_default_handler,
1982 &shmem_xattr_security_handler,
1983 NULL
1984};
1985#endif
1986
David M. Grimes91828a42006-10-17 00:09:45 -07001987static struct dentry *shmem_get_parent(struct dentry *child)
1988{
1989 return ERR_PTR(-ESTALE);
1990}
1991
1992static int shmem_match(struct inode *ino, void *vfh)
1993{
1994 __u32 *fh = vfh;
1995 __u64 inum = fh[2];
1996 inum = (inum << 32) | fh[1];
1997 return ino->i_ino == inum && fh[0] == ino->i_generation;
1998}
1999
2000static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh)
2001{
2002 struct dentry *de = NULL;
2003 struct inode *inode;
2004 __u32 *fh = vfh;
2005 __u64 inum = fh[2];
2006 inum = (inum << 32) | fh[1];
2007
2008 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh);
2009 if (inode) {
2010 de = d_find_alias(inode);
2011 iput(inode);
2012 }
2013
2014 return de? de: ERR_PTR(-ESTALE);
2015}
2016
2017static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh,
2018 int len, int type,
2019 int (*acceptable)(void *context, struct dentry *de),
2020 void *context)
2021{
2022 if (len < 3)
2023 return ERR_PTR(-ESTALE);
2024
2025 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable,
2026 context);
2027}
2028
2029static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
2030 int connectable)
2031{
2032 struct inode *inode = dentry->d_inode;
2033
2034 if (*len < 3)
2035 return 255;
2036
2037 if (hlist_unhashed(&inode->i_hash)) {
2038 /* Unfortunately insert_inode_hash is not idempotent,
2039 * so as we hash inodes here rather than at creation
2040 * time, we need a lock to ensure we only try
2041 * to do it once
2042 */
2043 static DEFINE_SPINLOCK(lock);
2044 spin_lock(&lock);
2045 if (hlist_unhashed(&inode->i_hash))
2046 __insert_inode_hash(inode,
2047 inode->i_ino + inode->i_generation);
2048 spin_unlock(&lock);
2049 }
2050
2051 fh[0] = inode->i_generation;
2052 fh[1] = inode->i_ino;
2053 fh[2] = ((__u64)inode->i_ino) >> 32;
2054
2055 *len = 3;
2056 return 1;
2057}
2058
2059static struct export_operations shmem_export_ops = {
2060 .get_parent = shmem_get_parent,
2061 .get_dentry = shmem_get_dentry,
2062 .encode_fh = shmem_encode_fh,
2063 .decode_fh = shmem_decode_fh,
2064};
2065
Robin Holt7339ff82006-01-14 13:20:48 -08002066static int shmem_parse_options(char *options, int *mode, uid_t *uid,
2067 gid_t *gid, unsigned long *blocks, unsigned long *inodes,
2068 int *policy, nodemask_t *policy_nodes)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002069{
2070 char *this_char, *value, *rest;
2071
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002072 while (options != NULL) {
2073 this_char = options;
2074 for (;;) {
2075 /*
2076 * NUL-terminate this option: unfortunately,
2077 * mount options form a comma-separated list,
2078 * but mpol's nodelist may also contain commas.
2079 */
2080 options = strchr(options, ',');
2081 if (options == NULL)
2082 break;
2083 options++;
2084 if (!isdigit(*options)) {
2085 options[-1] = '\0';
2086 break;
2087 }
2088 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002089 if (!*this_char)
2090 continue;
2091 if ((value = strchr(this_char,'=')) != NULL) {
2092 *value++ = 0;
2093 } else {
2094 printk(KERN_ERR
2095 "tmpfs: No value for mount option '%s'\n",
2096 this_char);
2097 return 1;
2098 }
2099
2100 if (!strcmp(this_char,"size")) {
2101 unsigned long long size;
2102 size = memparse(value,&rest);
2103 if (*rest == '%') {
2104 size <<= PAGE_SHIFT;
2105 size *= totalram_pages;
2106 do_div(size, 100);
2107 rest++;
2108 }
2109 if (*rest)
2110 goto bad_val;
2111 *blocks = size >> PAGE_CACHE_SHIFT;
2112 } else if (!strcmp(this_char,"nr_blocks")) {
2113 *blocks = memparse(value,&rest);
2114 if (*rest)
2115 goto bad_val;
2116 } else if (!strcmp(this_char,"nr_inodes")) {
2117 *inodes = memparse(value,&rest);
2118 if (*rest)
2119 goto bad_val;
2120 } else if (!strcmp(this_char,"mode")) {
2121 if (!mode)
2122 continue;
2123 *mode = simple_strtoul(value,&rest,8);
2124 if (*rest)
2125 goto bad_val;
2126 } else if (!strcmp(this_char,"uid")) {
2127 if (!uid)
2128 continue;
2129 *uid = simple_strtoul(value,&rest,0);
2130 if (*rest)
2131 goto bad_val;
2132 } else if (!strcmp(this_char,"gid")) {
2133 if (!gid)
2134 continue;
2135 *gid = simple_strtoul(value,&rest,0);
2136 if (*rest)
2137 goto bad_val;
Robin Holt7339ff82006-01-14 13:20:48 -08002138 } else if (!strcmp(this_char,"mpol")) {
Hugh Dickinsb00dc3a2006-02-21 23:49:47 +00002139 if (shmem_parse_mpol(value,policy,policy_nodes))
Robin Holt7339ff82006-01-14 13:20:48 -08002140 goto bad_val;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002141 } else {
2142 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2143 this_char);
2144 return 1;
2145 }
2146 }
2147 return 0;
2148
2149bad_val:
2150 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2151 value, this_char);
2152 return 1;
2153
2154}
2155
2156static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2157{
2158 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002159 unsigned long max_blocks = sbinfo->max_blocks;
2160 unsigned long max_inodes = sbinfo->max_inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002161 int policy = sbinfo->policy;
2162 nodemask_t policy_nodes = sbinfo->policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002163 unsigned long blocks;
2164 unsigned long inodes;
2165 int error = -EINVAL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002166
Robin Holt7339ff82006-01-14 13:20:48 -08002167 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks,
2168 &max_inodes, &policy, &policy_nodes))
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002169 return error;
2170
2171 spin_lock(&sbinfo->stat_lock);
2172 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
2173 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2174 if (max_blocks < blocks)
2175 goto out;
2176 if (max_inodes < inodes)
2177 goto out;
2178 /*
2179 * Those tests also disallow limited->unlimited while any are in
2180 * use, so i_blocks will always be zero when max_blocks is zero;
2181 * but we must separately disallow unlimited->limited, because
2182 * in that case we have no record of how much is already in use.
2183 */
2184 if (max_blocks && !sbinfo->max_blocks)
2185 goto out;
2186 if (max_inodes && !sbinfo->max_inodes)
2187 goto out;
2188
2189 error = 0;
2190 sbinfo->max_blocks = max_blocks;
2191 sbinfo->free_blocks = max_blocks - blocks;
2192 sbinfo->max_inodes = max_inodes;
2193 sbinfo->free_inodes = max_inodes - inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002194 sbinfo->policy = policy;
2195 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002196out:
2197 spin_unlock(&sbinfo->stat_lock);
2198 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002199}
2200#endif
2201
2202static void shmem_put_super(struct super_block *sb)
2203{
2204 kfree(sb->s_fs_info);
2205 sb->s_fs_info = NULL;
2206}
2207
Linus Torvalds1da177e2005-04-16 15:20:36 -07002208static int shmem_fill_super(struct super_block *sb,
2209 void *data, int silent)
2210{
2211 struct inode *inode;
2212 struct dentry *root;
2213 int mode = S_IRWXUGO | S_ISVTX;
2214 uid_t uid = current->fsuid;
2215 gid_t gid = current->fsgid;
2216 int err = -ENOMEM;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002217 struct shmem_sb_info *sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002218 unsigned long blocks = 0;
2219 unsigned long inodes = 0;
Robin Holt7339ff82006-01-14 13:20:48 -08002220 int policy = MPOL_DEFAULT;
2221 nodemask_t policy_nodes = node_online_map;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002222
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002223#ifdef CONFIG_TMPFS
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224 /*
2225 * Per default we only allow half of the physical ram per
2226 * tmpfs instance, limiting inodes to one per page of lowmem;
2227 * but the internal instance is left unlimited.
2228 */
2229 if (!(sb->s_flags & MS_NOUSER)) {
2230 blocks = totalram_pages / 2;
2231 inodes = totalram_pages - totalhigh_pages;
2232 if (inodes > blocks)
2233 inodes = blocks;
Robin Holt7339ff82006-01-14 13:20:48 -08002234 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks,
2235 &inodes, &policy, &policy_nodes))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002236 return -EINVAL;
2237 }
David M. Grimes91828a42006-10-17 00:09:45 -07002238 sb->s_export_op = &shmem_export_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002239#else
2240 sb->s_flags |= MS_NOUSER;
2241#endif
2242
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002243 /* Round up to L1_CACHE_BYTES to resist false sharing */
2244 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
2245 L1_CACHE_BYTES), GFP_KERNEL);
2246 if (!sbinfo)
2247 return -ENOMEM;
2248
2249 spin_lock_init(&sbinfo->stat_lock);
2250 sbinfo->max_blocks = blocks;
2251 sbinfo->free_blocks = blocks;
2252 sbinfo->max_inodes = inodes;
2253 sbinfo->free_inodes = inodes;
Robin Holt7339ff82006-01-14 13:20:48 -08002254 sbinfo->policy = policy;
2255 sbinfo->policy_nodes = policy_nodes;
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002256
2257 sb->s_fs_info = sbinfo;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002258 sb->s_maxbytes = SHMEM_MAX_BYTES;
2259 sb->s_blocksize = PAGE_CACHE_SIZE;
2260 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2261 sb->s_magic = TMPFS_MAGIC;
2262 sb->s_op = &shmem_ops;
Robin H. Johnsoncfd95a92006-06-12 21:50:25 +01002263 sb->s_time_gran = 1;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002264#ifdef CONFIG_TMPFS_POSIX_ACL
2265 sb->s_xattr = shmem_xattr_handlers;
2266 sb->s_flags |= MS_POSIXACL;
2267#endif
Hugh Dickins0edd73b2005-06-21 17:15:04 -07002268
Linus Torvalds1da177e2005-04-16 15:20:36 -07002269 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2270 if (!inode)
2271 goto failed;
2272 inode->i_uid = uid;
2273 inode->i_gid = gid;
2274 root = d_alloc_root(inode);
2275 if (!root)
2276 goto failed_iput;
2277 sb->s_root = root;
2278 return 0;
2279
2280failed_iput:
2281 iput(inode);
2282failed:
2283 shmem_put_super(sb);
2284 return err;
2285}
2286
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002287static struct kmem_cache *shmem_inode_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002288
2289static struct inode *shmem_alloc_inode(struct super_block *sb)
2290{
2291 struct shmem_inode_info *p;
Christoph Lametere94b1762006-12-06 20:33:17 -08002292 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002293 if (!p)
2294 return NULL;
2295 return &p->vfs_inode;
2296}
2297
2298static void shmem_destroy_inode(struct inode *inode)
2299{
2300 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2301 /* only struct inode is valid if it's an inline symlink */
2302 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2303 }
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002304 shmem_acl_destroy_inode(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002305 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2306}
2307
Pekka Enbergfcc234f2006-03-22 00:08:13 -08002308static void init_once(void *foo, struct kmem_cache *cachep,
2309 unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002310{
2311 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2312
Christoph Lametera35afb82007-05-16 22:10:57 -07002313 inode_init_once(&p->vfs_inode);
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002314#ifdef CONFIG_TMPFS_POSIX_ACL
Christoph Lametera35afb82007-05-16 22:10:57 -07002315 p->i_acl = NULL;
2316 p->i_default_acl = NULL;
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002317#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002318}
2319
2320static int init_inodecache(void)
2321{
2322 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2323 sizeof(struct shmem_inode_info),
Paul Mundt20c2df82007-07-20 10:11:58 +09002324 0, 0, init_once);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002325 if (shmem_inode_cachep == NULL)
2326 return -ENOMEM;
2327 return 0;
2328}
2329
2330static void destroy_inodecache(void)
2331{
Alexey Dobriyan1a1d92c2006-09-27 01:49:40 -07002332 kmem_cache_destroy(shmem_inode_cachep);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002333}
2334
Christoph Hellwigf5e54d62006-06-28 04:26:44 -07002335static const struct address_space_operations shmem_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002336 .writepage = shmem_writepage,
Ken Chen76719322007-02-10 01:43:15 -08002337 .set_page_dirty = __set_page_dirty_no_writeback,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002338#ifdef CONFIG_TMPFS
Hugh Dickinsae9764162007-06-04 10:00:39 +02002339 .readpage = shmem_readpage,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002340 .prepare_write = shmem_prepare_write,
2341 .commit_write = simple_commit_write,
2342#endif
Lee Schermerhorn304dbdb2006-04-22 02:35:48 -07002343 .migratepage = migrate_page,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002344};
2345
Helge Deller15ad7cd2006-12-06 20:40:36 -08002346static const struct file_operations shmem_file_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002347 .mmap = shmem_mmap,
2348#ifdef CONFIG_TMPFS
2349 .llseek = generic_file_llseek,
2350 .read = shmem_file_read,
2351 .write = shmem_file_write,
2352 .fsync = simple_sync_file,
Hugh Dickinsae9764162007-06-04 10:00:39 +02002353 .splice_read = generic_file_splice_read,
2354 .splice_write = generic_file_splice_write,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002355#endif
2356};
2357
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002358static const struct inode_operations shmem_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002359 .truncate = shmem_truncate,
2360 .setattr = shmem_notify_change,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -08002361 .truncate_range = shmem_truncate_range,
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002362#ifdef CONFIG_TMPFS_POSIX_ACL
2363 .setxattr = generic_setxattr,
2364 .getxattr = generic_getxattr,
2365 .listxattr = generic_listxattr,
2366 .removexattr = generic_removexattr,
2367 .permission = shmem_permission,
2368#endif
2369
Linus Torvalds1da177e2005-04-16 15:20:36 -07002370};
2371
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002372static const struct inode_operations shmem_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002373#ifdef CONFIG_TMPFS
2374 .create = shmem_create,
2375 .lookup = simple_lookup,
2376 .link = shmem_link,
2377 .unlink = shmem_unlink,
2378 .symlink = shmem_symlink,
2379 .mkdir = shmem_mkdir,
2380 .rmdir = shmem_rmdir,
2381 .mknod = shmem_mknod,
2382 .rename = shmem_rename,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002383#endif
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002384#ifdef CONFIG_TMPFS_POSIX_ACL
2385 .setattr = shmem_notify_change,
2386 .setxattr = generic_setxattr,
2387 .getxattr = generic_getxattr,
2388 .listxattr = generic_listxattr,
2389 .removexattr = generic_removexattr,
2390 .permission = shmem_permission,
2391#endif
2392};
2393
Arjan van de Ven92e1d5b2007-02-12 00:55:39 -08002394static const struct inode_operations shmem_special_inode_operations = {
Andreas Gruenbacher39f02472006-09-29 02:01:35 -07002395#ifdef CONFIG_TMPFS_POSIX_ACL
2396 .setattr = shmem_notify_change,
2397 .setxattr = generic_setxattr,
2398 .getxattr = generic_getxattr,
2399 .listxattr = generic_listxattr,
2400 .removexattr = generic_removexattr,
2401 .permission = shmem_permission,
2402#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -07002403};
2404
Hugh Dickins759b9772007-03-05 00:30:28 -08002405static const struct super_operations shmem_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002406 .alloc_inode = shmem_alloc_inode,
2407 .destroy_inode = shmem_destroy_inode,
2408#ifdef CONFIG_TMPFS
2409 .statfs = shmem_statfs,
2410 .remount_fs = shmem_remount_fs,
2411#endif
2412 .delete_inode = shmem_delete_inode,
2413 .drop_inode = generic_delete_inode,
2414 .put_super = shmem_put_super,
2415};
2416
2417static struct vm_operations_struct shmem_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07002418 .fault = shmem_fault,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419#ifdef CONFIG_NUMA
2420 .set_policy = shmem_set_policy,
2421 .get_policy = shmem_get_policy,
2422#endif
2423};
2424
2425
David Howells454e2392006-06-23 02:02:57 -07002426static int shmem_get_sb(struct file_system_type *fs_type,
2427 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002428{
David Howells454e2392006-06-23 02:02:57 -07002429 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002430}
2431
2432static struct file_system_type tmpfs_fs_type = {
2433 .owner = THIS_MODULE,
2434 .name = "tmpfs",
2435 .get_sb = shmem_get_sb,
2436 .kill_sb = kill_litter_super,
2437};
2438static struct vfsmount *shm_mnt;
2439
2440static int __init init_tmpfs(void)
2441{
2442 int error;
2443
2444 error = init_inodecache();
2445 if (error)
2446 goto out3;
2447
2448 error = register_filesystem(&tmpfs_fs_type);
2449 if (error) {
2450 printk(KERN_ERR "Could not register tmpfs\n");
2451 goto out2;
2452 }
Greg Kroah-Hartman95dc1122005-06-20 21:15:16 -07002453
Trond Myklebust1f5ce9e2006-06-09 09:34:16 -04002454 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002455 tmpfs_fs_type.name, NULL);
2456 if (IS_ERR(shm_mnt)) {
2457 error = PTR_ERR(shm_mnt);
2458 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2459 goto out1;
2460 }
2461 return 0;
2462
2463out1:
2464 unregister_filesystem(&tmpfs_fs_type);
2465out2:
2466 destroy_inodecache();
2467out3:
2468 shm_mnt = ERR_PTR(error);
2469 return error;
2470}
2471module_init(init_tmpfs)
2472
2473/*
2474 * shmem_file_setup - get an unlinked file living in tmpfs
2475 *
2476 * @name: name for dentry (to be seen in /proc/<pid>/maps
2477 * @size: size to be set for the file
2478 *
2479 */
2480struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2481{
2482 int error;
2483 struct file *file;
2484 struct inode *inode;
2485 struct dentry *dentry, *root;
2486 struct qstr this;
2487
2488 if (IS_ERR(shm_mnt))
2489 return (void *)shm_mnt;
2490
2491 if (size < 0 || size > SHMEM_MAX_BYTES)
2492 return ERR_PTR(-EINVAL);
2493
2494 if (shmem_acct_size(flags, size))
2495 return ERR_PTR(-ENOMEM);
2496
2497 error = -ENOMEM;
2498 this.name = name;
2499 this.len = strlen(name);
2500 this.hash = 0; /* will go */
2501 root = shm_mnt->mnt_root;
2502 dentry = d_alloc(root, &this);
2503 if (!dentry)
2504 goto put_memory;
2505
2506 error = -ENFILE;
2507 file = get_empty_filp();
2508 if (!file)
2509 goto put_dentry;
2510
2511 error = -ENOSPC;
2512 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2513 if (!inode)
2514 goto close_file;
2515
2516 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2517 d_instantiate(dentry, inode);
2518 inode->i_size = size;
2519 inode->i_nlink = 0; /* It is unlinked */
Josef "Jeff" Sipekd3ac7f82006-12-08 02:36:44 -08002520 file->f_path.mnt = mntget(shm_mnt);
2521 file->f_path.dentry = dentry;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002522 file->f_mapping = inode->i_mapping;
2523 file->f_op = &shmem_file_operations;
2524 file->f_mode = FMODE_WRITE | FMODE_READ;
2525 return file;
2526
2527close_file:
2528 put_filp(file);
2529put_dentry:
2530 dput(dentry);
2531put_memory:
2532 shmem_unacct_size(flags, size);
2533 return ERR_PTR(error);
2534}
2535
2536/*
2537 * shmem_zero_setup - setup a shared anonymous mapping
2538 *
2539 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2540 */
2541int shmem_zero_setup(struct vm_area_struct *vma)
2542{
2543 struct file *file;
2544 loff_t size = vma->vm_end - vma->vm_start;
2545
2546 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2547 if (IS_ERR(file))
2548 return PTR_ERR(file);
2549
2550 if (vma->vm_file)
2551 fput(vma->vm_file);
2552 vma->vm_file = file;
2553 vma->vm_ops = &shmem_vm_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002554 return 0;
2555}