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1 | /* |
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. |
9 | * Copyright (C) 2002-2011 Hugh Dickins. |
10 | * Copyright (C) 2011 Google Inc. |
11 | * Copyright (C) 2002-2005 VERITAS Software Corporation. |
12 | * Copyright (C) 2004 Andi Kleen, SuSE Labs |
13 | * |
14 | * Extended attribute support for tmpfs: |
15 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> |
16 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
17 | * |
18 | * tiny-shmem: |
19 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> |
20 | * |
21 | * This file is released under the GPL. |
22 | */ |
23 | |
24 | #include <linux/fs.h> |
25 | #include <linux/init.h> |
26 | #include <linux/vfs.h> |
27 | #include <linux/mount.h> |
28 | #include <linux/pagemap.h> |
29 | #include <linux/file.h> |
30 | #include <linux/mm.h> |
31 | #include <linux/export.h> |
32 | #include <linux/swap.h> |
33 | |
34 | static struct vfsmount *shm_mnt; |
35 | |
36 | #ifdef CONFIG_SHMEM |
37 | /* |
38 | * This virtual memory filesystem is heavily based on the ramfs. It |
39 | * extends ramfs by the ability to use swap and honor resource limits |
40 | * which makes it a completely usable filesystem. |
41 | */ |
42 | |
43 | #include <linux/xattr.h> |
44 | #include <linux/exportfs.h> |
45 | #include <linux/posix_acl.h> |
46 | #include <linux/generic_acl.h> |
47 | #include <linux/mman.h> |
48 | #include <linux/string.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/backing-dev.h> |
51 | #include <linux/shmem_fs.h> |
52 | #include <linux/writeback.h> |
53 | #include <linux/blkdev.h> |
54 | #include <linux/pagevec.h> |
55 | #include <linux/percpu_counter.h> |
56 | #include <linux/splice.h> |
57 | #include <linux/security.h> |
58 | #include <linux/swapops.h> |
59 | #include <linux/mempolicy.h> |
60 | #include <linux/namei.h> |
61 | #include <linux/ctype.h> |
62 | #include <linux/migrate.h> |
63 | #include <linux/highmem.h> |
64 | #include <linux/seq_file.h> |
65 | #include <linux/magic.h> |
66 | |
67 | #include <asm/uaccess.h> |
68 | #include <asm/pgtable.h> |
69 | |
70 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
71 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
72 | |
73 | /* Pretend that each entry is of this size in directory's i_size */ |
74 | #define BOGO_DIRENT_SIZE 20 |
75 | |
76 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ |
77 | #define SHORT_SYMLINK_LEN 128 |
78 | |
79 | struct shmem_xattr { |
80 | struct list_head list; /* anchored by shmem_inode_info->xattr_list */ |
81 | char *name; /* xattr name */ |
82 | size_t size; |
83 | char value[0]; |
84 | }; |
85 | |
86 | /* Flag allocation requirements to shmem_getpage */ |
87 | enum sgp_type { |
88 | SGP_READ, /* don't exceed i_size, don't allocate page */ |
89 | SGP_CACHE, /* don't exceed i_size, may allocate page */ |
90 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
91 | SGP_WRITE, /* may exceed i_size, may allocate page */ |
92 | }; |
93 | |
94 | #ifdef CONFIG_TMPFS |
95 | static unsigned long shmem_default_max_blocks(void) |
96 | { |
97 | return totalram_pages / 2; |
98 | } |
99 | |
100 | static unsigned long shmem_default_max_inodes(void) |
101 | { |
102 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
103 | } |
104 | #endif |
105 | |
106 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
107 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); |
108 | |
109 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, |
110 | struct page **pagep, enum sgp_type sgp, int *fault_type) |
111 | { |
112 | return shmem_getpage_gfp(inode, index, pagep, sgp, |
113 | mapping_gfp_mask(inode->i_mapping), fault_type); |
114 | } |
115 | |
116 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
117 | { |
118 | return sb->s_fs_info; |
119 | } |
120 | |
121 | /* |
122 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
123 | * for shared memory and for shared anonymous (/dev/zero) mappings |
124 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
125 | * consistent with the pre-accounting of private mappings ... |
126 | */ |
127 | static inline int shmem_acct_size(unsigned long flags, loff_t size) |
128 | { |
129 | return (flags & VM_NORESERVE) ? |
130 | 0 : security_vm_enough_memory_kern(VM_ACCT(size)); |
131 | } |
132 | |
133 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
134 | { |
135 | if (!(flags & VM_NORESERVE)) |
136 | vm_unacct_memory(VM_ACCT(size)); |
137 | } |
138 | |
139 | /* |
140 | * ... whereas tmpfs objects are accounted incrementally as |
141 | * pages are allocated, in order to allow huge sparse files. |
142 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
143 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
144 | */ |
145 | static inline int shmem_acct_block(unsigned long flags) |
146 | { |
147 | return (flags & VM_NORESERVE) ? |
148 | security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
149 | } |
150 | |
151 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
152 | { |
153 | if (flags & VM_NORESERVE) |
154 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
155 | } |
156 | |
157 | static const struct super_operations shmem_ops; |
158 | static const struct address_space_operations shmem_aops; |
159 | static const struct file_operations shmem_file_operations; |
160 | static const struct inode_operations shmem_inode_operations; |
161 | static const struct inode_operations shmem_dir_inode_operations; |
162 | static const struct inode_operations shmem_special_inode_operations; |
163 | static const struct vm_operations_struct shmem_vm_ops; |
164 | |
165 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
166 | .ra_pages = 0, /* No readahead */ |
167 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
168 | }; |
169 | |
170 | static LIST_HEAD(shmem_swaplist); |
171 | static DEFINE_MUTEX(shmem_swaplist_mutex); |
172 | |
173 | static int shmem_reserve_inode(struct super_block *sb) |
174 | { |
175 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
176 | if (sbinfo->max_inodes) { |
177 | spin_lock(&sbinfo->stat_lock); |
178 | if (!sbinfo->free_inodes) { |
179 | spin_unlock(&sbinfo->stat_lock); |
180 | return -ENOSPC; |
181 | } |
182 | sbinfo->free_inodes--; |
183 | spin_unlock(&sbinfo->stat_lock); |
184 | } |
185 | return 0; |
186 | } |
187 | |
188 | static void shmem_free_inode(struct super_block *sb) |
189 | { |
190 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
191 | if (sbinfo->max_inodes) { |
192 | spin_lock(&sbinfo->stat_lock); |
193 | sbinfo->free_inodes++; |
194 | spin_unlock(&sbinfo->stat_lock); |
195 | } |
196 | } |
197 | |
198 | /** |
199 | * shmem_recalc_inode - recalculate the block usage of an inode |
200 | * @inode: inode to recalc |
201 | * |
202 | * We have to calculate the free blocks since the mm can drop |
203 | * undirtied hole pages behind our back. |
204 | * |
205 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
206 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
207 | * |
208 | * It has to be called with the spinlock held. |
209 | */ |
210 | static void shmem_recalc_inode(struct inode *inode) |
211 | { |
212 | struct shmem_inode_info *info = SHMEM_I(inode); |
213 | long freed; |
214 | |
215 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
216 | if (freed > 0) { |
217 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
218 | if (sbinfo->max_blocks) |
219 | percpu_counter_add(&sbinfo->used_blocks, -freed); |
220 | info->alloced -= freed; |
221 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; |
222 | shmem_unacct_blocks(info->flags, freed); |
223 | } |
224 | } |
225 | |
226 | /* |
227 | * Replace item expected in radix tree by a new item, while holding tree lock. |
228 | */ |
229 | static int shmem_radix_tree_replace(struct address_space *mapping, |
230 | pgoff_t index, void *expected, void *replacement) |
231 | { |
232 | void **pslot; |
233 | void *item = NULL; |
234 | |
235 | VM_BUG_ON(!expected); |
236 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); |
237 | if (pslot) |
238 | item = radix_tree_deref_slot_protected(pslot, |
239 | &mapping->tree_lock); |
240 | if (item != expected) |
241 | return -ENOENT; |
242 | if (replacement) |
243 | radix_tree_replace_slot(pslot, replacement); |
244 | else |
245 | radix_tree_delete(&mapping->page_tree, index); |
246 | return 0; |
247 | } |
248 | |
249 | /* |
250 | * Like add_to_page_cache_locked, but error if expected item has gone. |
251 | */ |
252 | static int shmem_add_to_page_cache(struct page *page, |
253 | struct address_space *mapping, |
254 | pgoff_t index, gfp_t gfp, void *expected) |
255 | { |
256 | int error = 0; |
257 | |
258 | VM_BUG_ON(!PageLocked(page)); |
259 | VM_BUG_ON(!PageSwapBacked(page)); |
260 | |
261 | if (!expected) |
262 | error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); |
263 | if (!error) { |
264 | page_cache_get(page); |
265 | page->mapping = mapping; |
266 | page->index = index; |
267 | |
268 | spin_lock_irq(&mapping->tree_lock); |
269 | if (!expected) |
270 | error = radix_tree_insert(&mapping->page_tree, |
271 | index, page); |
272 | else |
273 | error = shmem_radix_tree_replace(mapping, index, |
274 | expected, page); |
275 | if (!error) { |
276 | mapping->nrpages++; |
277 | __inc_zone_page_state(page, NR_FILE_PAGES); |
278 | __inc_zone_page_state(page, NR_SHMEM); |
279 | spin_unlock_irq(&mapping->tree_lock); |
280 | } else { |
281 | page->mapping = NULL; |
282 | spin_unlock_irq(&mapping->tree_lock); |
283 | page_cache_release(page); |
284 | } |
285 | if (!expected) |
286 | radix_tree_preload_end(); |
287 | } |
288 | if (error) |
289 | mem_cgroup_uncharge_cache_page(page); |
290 | return error; |
291 | } |
292 | |
293 | /* |
294 | * Like delete_from_page_cache, but substitutes swap for page. |
295 | */ |
296 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) |
297 | { |
298 | struct address_space *mapping = page->mapping; |
299 | int error; |
300 | |
301 | spin_lock_irq(&mapping->tree_lock); |
302 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); |
303 | page->mapping = NULL; |
304 | mapping->nrpages--; |
305 | __dec_zone_page_state(page, NR_FILE_PAGES); |
306 | __dec_zone_page_state(page, NR_SHMEM); |
307 | spin_unlock_irq(&mapping->tree_lock); |
308 | page_cache_release(page); |
309 | BUG_ON(error); |
310 | } |
311 | |
312 | /* |
313 | * Like find_get_pages, but collecting swap entries as well as pages. |
314 | */ |
315 | static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, |
316 | pgoff_t start, unsigned int nr_pages, |
317 | struct page **pages, pgoff_t *indices) |
318 | { |
319 | unsigned int i; |
320 | unsigned int ret; |
321 | unsigned int nr_found; |
322 | |
323 | rcu_read_lock(); |
324 | restart: |
325 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, |
326 | (void ***)pages, indices, start, nr_pages); |
327 | ret = 0; |
328 | for (i = 0; i < nr_found; i++) { |
329 | struct page *page; |
330 | repeat: |
331 | page = radix_tree_deref_slot((void **)pages[i]); |
332 | if (unlikely(!page)) |
333 | continue; |
334 | if (radix_tree_exception(page)) { |
335 | if (radix_tree_deref_retry(page)) |
336 | goto restart; |
337 | /* |
338 | * Otherwise, we must be storing a swap entry |
339 | * here as an exceptional entry: so return it |
340 | * without attempting to raise page count. |
341 | */ |
342 | goto export; |
343 | } |
344 | if (!page_cache_get_speculative(page)) |
345 | goto repeat; |
346 | |
347 | /* Has the page moved? */ |
348 | if (unlikely(page != *((void **)pages[i]))) { |
349 | page_cache_release(page); |
350 | goto repeat; |
351 | } |
352 | export: |
353 | indices[ret] = indices[i]; |
354 | pages[ret] = page; |
355 | ret++; |
356 | } |
357 | if (unlikely(!ret && nr_found)) |
358 | goto restart; |
359 | rcu_read_unlock(); |
360 | return ret; |
361 | } |
362 | |
363 | /* |
364 | * Remove swap entry from radix tree, free the swap and its page cache. |
365 | */ |
366 | static int shmem_free_swap(struct address_space *mapping, |
367 | pgoff_t index, void *radswap) |
368 | { |
369 | int error; |
370 | |
371 | spin_lock_irq(&mapping->tree_lock); |
372 | error = shmem_radix_tree_replace(mapping, index, radswap, NULL); |
373 | spin_unlock_irq(&mapping->tree_lock); |
374 | if (!error) |
375 | free_swap_and_cache(radix_to_swp_entry(radswap)); |
376 | return error; |
377 | } |
378 | |
379 | /* |
380 | * Pagevec may contain swap entries, so shuffle up pages before releasing. |
381 | */ |
382 | static void shmem_deswap_pagevec(struct pagevec *pvec) |
383 | { |
384 | int i, j; |
385 | |
386 | for (i = 0, j = 0; i < pagevec_count(pvec); i++) { |
387 | struct page *page = pvec->pages[i]; |
388 | if (!radix_tree_exceptional_entry(page)) |
389 | pvec->pages[j++] = page; |
390 | } |
391 | pvec->nr = j; |
392 | } |
393 | |
394 | /* |
395 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. |
396 | */ |
397 | void shmem_unlock_mapping(struct address_space *mapping) |
398 | { |
399 | struct pagevec pvec; |
400 | pgoff_t indices[PAGEVEC_SIZE]; |
401 | pgoff_t index = 0; |
402 | |
403 | pagevec_init(&pvec, 0); |
404 | /* |
405 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. |
406 | */ |
407 | while (!mapping_unevictable(mapping)) { |
408 | /* |
409 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it |
410 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. |
411 | */ |
412 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
413 | PAGEVEC_SIZE, pvec.pages, indices); |
414 | if (!pvec.nr) |
415 | break; |
416 | index = indices[pvec.nr - 1] + 1; |
417 | shmem_deswap_pagevec(&pvec); |
418 | check_move_unevictable_pages(pvec.pages, pvec.nr); |
419 | pagevec_release(&pvec); |
420 | cond_resched(); |
421 | } |
422 | } |
423 | |
424 | /* |
425 | * Remove range of pages and swap entries from radix tree, and free them. |
426 | */ |
427 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
428 | { |
429 | struct address_space *mapping = inode->i_mapping; |
430 | struct shmem_inode_info *info = SHMEM_I(inode); |
431 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
432 | unsigned partial = lstart & (PAGE_CACHE_SIZE - 1); |
433 | pgoff_t end = (lend >> PAGE_CACHE_SHIFT); |
434 | struct pagevec pvec; |
435 | pgoff_t indices[PAGEVEC_SIZE]; |
436 | long nr_swaps_freed = 0; |
437 | pgoff_t index; |
438 | int i; |
439 | |
440 | BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1)); |
441 | |
442 | pagevec_init(&pvec, 0); |
443 | index = start; |
444 | while (index <= end) { |
445 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
446 | min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
447 | pvec.pages, indices); |
448 | if (!pvec.nr) |
449 | break; |
450 | mem_cgroup_uncharge_start(); |
451 | for (i = 0; i < pagevec_count(&pvec); i++) { |
452 | struct page *page = pvec.pages[i]; |
453 | |
454 | index = indices[i]; |
455 | if (index > end) |
456 | break; |
457 | |
458 | if (radix_tree_exceptional_entry(page)) { |
459 | nr_swaps_freed += !shmem_free_swap(mapping, |
460 | index, page); |
461 | continue; |
462 | } |
463 | |
464 | if (!trylock_page(page)) |
465 | continue; |
466 | if (page->mapping == mapping) { |
467 | VM_BUG_ON(PageWriteback(page)); |
468 | truncate_inode_page(mapping, page); |
469 | } |
470 | unlock_page(page); |
471 | } |
472 | shmem_deswap_pagevec(&pvec); |
473 | pagevec_release(&pvec); |
474 | mem_cgroup_uncharge_end(); |
475 | cond_resched(); |
476 | index++; |
477 | } |
478 | |
479 | if (partial) { |
480 | struct page *page = NULL; |
481 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); |
482 | if (page) { |
483 | zero_user_segment(page, partial, PAGE_CACHE_SIZE); |
484 | set_page_dirty(page); |
485 | unlock_page(page); |
486 | page_cache_release(page); |
487 | } |
488 | } |
489 | |
490 | index = start; |
491 | for ( ; ; ) { |
492 | cond_resched(); |
493 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
494 | min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
495 | pvec.pages, indices); |
496 | if (!pvec.nr) { |
497 | if (index == start) |
498 | break; |
499 | index = start; |
500 | continue; |
501 | } |
502 | if (index == start && indices[0] > end) { |
503 | shmem_deswap_pagevec(&pvec); |
504 | pagevec_release(&pvec); |
505 | break; |
506 | } |
507 | mem_cgroup_uncharge_start(); |
508 | for (i = 0; i < pagevec_count(&pvec); i++) { |
509 | struct page *page = pvec.pages[i]; |
510 | |
511 | index = indices[i]; |
512 | if (index > end) |
513 | break; |
514 | |
515 | if (radix_tree_exceptional_entry(page)) { |
516 | nr_swaps_freed += !shmem_free_swap(mapping, |
517 | index, page); |
518 | continue; |
519 | } |
520 | |
521 | lock_page(page); |
522 | if (page->mapping == mapping) { |
523 | VM_BUG_ON(PageWriteback(page)); |
524 | truncate_inode_page(mapping, page); |
525 | } |
526 | unlock_page(page); |
527 | } |
528 | shmem_deswap_pagevec(&pvec); |
529 | pagevec_release(&pvec); |
530 | mem_cgroup_uncharge_end(); |
531 | index++; |
532 | } |
533 | |
534 | spin_lock(&info->lock); |
535 | info->swapped -= nr_swaps_freed; |
536 | shmem_recalc_inode(inode); |
537 | spin_unlock(&info->lock); |
538 | |
539 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
540 | } |
541 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
542 | |
543 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) |
544 | { |
545 | struct inode *inode = dentry->d_inode; |
546 | int error; |
547 | |
548 | error = inode_change_ok(inode, attr); |
549 | if (error) |
550 | return error; |
551 | |
552 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
553 | loff_t oldsize = inode->i_size; |
554 | loff_t newsize = attr->ia_size; |
555 | |
556 | if (newsize != oldsize) { |
557 | i_size_write(inode, newsize); |
558 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
559 | } |
560 | if (newsize < oldsize) { |
561 | loff_t holebegin = round_up(newsize, PAGE_SIZE); |
562 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
563 | shmem_truncate_range(inode, newsize, (loff_t)-1); |
564 | /* unmap again to remove racily COWed private pages */ |
565 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
566 | } |
567 | } |
568 | |
569 | setattr_copy(inode, attr); |
570 | #ifdef CONFIG_TMPFS_POSIX_ACL |
571 | if (attr->ia_valid & ATTR_MODE) |
572 | error = generic_acl_chmod(inode); |
573 | #endif |
574 | return error; |
575 | } |
576 | |
577 | static void shmem_evict_inode(struct inode *inode) |
578 | { |
579 | struct shmem_inode_info *info = SHMEM_I(inode); |
580 | struct shmem_xattr *xattr, *nxattr; |
581 | |
582 | if (inode->i_mapping->a_ops == &shmem_aops) { |
583 | shmem_unacct_size(info->flags, inode->i_size); |
584 | inode->i_size = 0; |
585 | shmem_truncate_range(inode, 0, (loff_t)-1); |
586 | if (!list_empty(&info->swaplist)) { |
587 | mutex_lock(&shmem_swaplist_mutex); |
588 | list_del_init(&info->swaplist); |
589 | mutex_unlock(&shmem_swaplist_mutex); |
590 | } |
591 | } else |
592 | kfree(info->symlink); |
593 | |
594 | list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) { |
595 | kfree(xattr->name); |
596 | kfree(xattr); |
597 | } |
598 | BUG_ON(inode->i_blocks); |
599 | shmem_free_inode(inode->i_sb); |
600 | end_writeback(inode); |
601 | } |
602 | |
603 | /* |
604 | * If swap found in inode, free it and move page from swapcache to filecache. |
605 | */ |
606 | static int shmem_unuse_inode(struct shmem_inode_info *info, |
607 | swp_entry_t swap, struct page *page) |
608 | { |
609 | struct address_space *mapping = info->vfs_inode.i_mapping; |
610 | void *radswap; |
611 | pgoff_t index; |
612 | int error; |
613 | |
614 | radswap = swp_to_radix_entry(swap); |
615 | index = radix_tree_locate_item(&mapping->page_tree, radswap); |
616 | if (index == -1) |
617 | return 0; |
618 | |
619 | /* |
620 | * Move _head_ to start search for next from here. |
621 | * But be careful: shmem_evict_inode checks list_empty without taking |
622 | * mutex, and there's an instant in list_move_tail when info->swaplist |
623 | * would appear empty, if it were the only one on shmem_swaplist. |
624 | */ |
625 | if (shmem_swaplist.next != &info->swaplist) |
626 | list_move_tail(&shmem_swaplist, &info->swaplist); |
627 | |
628 | /* |
629 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, |
630 | * but also to hold up shmem_evict_inode(): so inode cannot be freed |
631 | * beneath us (pagelock doesn't help until the page is in pagecache). |
632 | */ |
633 | error = shmem_add_to_page_cache(page, mapping, index, |
634 | GFP_NOWAIT, radswap); |
635 | /* which does mem_cgroup_uncharge_cache_page on error */ |
636 | |
637 | if (error != -ENOMEM) { |
638 | /* |
639 | * Truncation and eviction use free_swap_and_cache(), which |
640 | * only does trylock page: if we raced, best clean up here. |
641 | */ |
642 | delete_from_swap_cache(page); |
643 | set_page_dirty(page); |
644 | if (!error) { |
645 | spin_lock(&info->lock); |
646 | info->swapped--; |
647 | spin_unlock(&info->lock); |
648 | swap_free(swap); |
649 | } |
650 | error = 1; /* not an error, but entry was found */ |
651 | } |
652 | return error; |
653 | } |
654 | |
655 | /* |
656 | * Search through swapped inodes to find and replace swap by page. |
657 | */ |
658 | int shmem_unuse(swp_entry_t swap, struct page *page) |
659 | { |
660 | struct list_head *this, *next; |
661 | struct shmem_inode_info *info; |
662 | int found = 0; |
663 | int error; |
664 | |
665 | /* |
666 | * Charge page using GFP_KERNEL while we can wait, before taking |
667 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). |
668 | * Charged back to the user (not to caller) when swap account is used. |
669 | */ |
670 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); |
671 | if (error) |
672 | goto out; |
673 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ |
674 | |
675 | mutex_lock(&shmem_swaplist_mutex); |
676 | list_for_each_safe(this, next, &shmem_swaplist) { |
677 | info = list_entry(this, struct shmem_inode_info, swaplist); |
678 | if (info->swapped) |
679 | found = shmem_unuse_inode(info, swap, page); |
680 | else |
681 | list_del_init(&info->swaplist); |
682 | cond_resched(); |
683 | if (found) |
684 | break; |
685 | } |
686 | mutex_unlock(&shmem_swaplist_mutex); |
687 | |
688 | if (!found) |
689 | mem_cgroup_uncharge_cache_page(page); |
690 | if (found < 0) |
691 | error = found; |
692 | out: |
693 | unlock_page(page); |
694 | page_cache_release(page); |
695 | return error; |
696 | } |
697 | |
698 | /* |
699 | * Move the page from the page cache to the swap cache. |
700 | */ |
701 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
702 | { |
703 | struct shmem_inode_info *info; |
704 | struct address_space *mapping; |
705 | struct inode *inode; |
706 | swp_entry_t swap; |
707 | pgoff_t index; |
708 | |
709 | BUG_ON(!PageLocked(page)); |
710 | mapping = page->mapping; |
711 | index = page->index; |
712 | inode = mapping->host; |
713 | info = SHMEM_I(inode); |
714 | if (info->flags & VM_LOCKED) |
715 | goto redirty; |
716 | if (!total_swap_pages) |
717 | goto redirty; |
718 | |
719 | /* |
720 | * shmem_backing_dev_info's capabilities prevent regular writeback or |
721 | * sync from ever calling shmem_writepage; but a stacking filesystem |
722 | * might use ->writepage of its underlying filesystem, in which case |
723 | * tmpfs should write out to swap only in response to memory pressure, |
724 | * and not for the writeback threads or sync. |
725 | */ |
726 | if (!wbc->for_reclaim) { |
727 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ |
728 | goto redirty; |
729 | } |
730 | swap = get_swap_page(); |
731 | if (!swap.val) |
732 | goto redirty; |
733 | |
734 | /* |
735 | * Add inode to shmem_unuse()'s list of swapped-out inodes, |
736 | * if it's not already there. Do it now before the page is |
737 | * moved to swap cache, when its pagelock no longer protects |
738 | * the inode from eviction. But don't unlock the mutex until |
739 | * we've incremented swapped, because shmem_unuse_inode() will |
740 | * prune a !swapped inode from the swaplist under this mutex. |
741 | */ |
742 | mutex_lock(&shmem_swaplist_mutex); |
743 | if (list_empty(&info->swaplist)) |
744 | list_add_tail(&info->swaplist, &shmem_swaplist); |
745 | |
746 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
747 | swap_shmem_alloc(swap); |
748 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); |
749 | |
750 | spin_lock(&info->lock); |
751 | info->swapped++; |
752 | shmem_recalc_inode(inode); |
753 | spin_unlock(&info->lock); |
754 | |
755 | mutex_unlock(&shmem_swaplist_mutex); |
756 | BUG_ON(page_mapped(page)); |
757 | swap_writepage(page, wbc); |
758 | return 0; |
759 | } |
760 | |
761 | mutex_unlock(&shmem_swaplist_mutex); |
762 | swapcache_free(swap, NULL); |
763 | redirty: |
764 | set_page_dirty(page); |
765 | if (wbc->for_reclaim) |
766 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
767 | unlock_page(page); |
768 | return 0; |
769 | } |
770 | |
771 | #ifdef CONFIG_NUMA |
772 | #ifdef CONFIG_TMPFS |
773 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
774 | { |
775 | char buffer[64]; |
776 | |
777 | if (!mpol || mpol->mode == MPOL_DEFAULT) |
778 | return; /* show nothing */ |
779 | |
780 | mpol_to_str(buffer, sizeof(buffer), mpol, 1); |
781 | |
782 | seq_printf(seq, ",mpol=%s", buffer); |
783 | } |
784 | |
785 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
786 | { |
787 | struct mempolicy *mpol = NULL; |
788 | if (sbinfo->mpol) { |
789 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
790 | mpol = sbinfo->mpol; |
791 | mpol_get(mpol); |
792 | spin_unlock(&sbinfo->stat_lock); |
793 | } |
794 | return mpol; |
795 | } |
796 | #endif /* CONFIG_TMPFS */ |
797 | |
798 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
799 | struct shmem_inode_info *info, pgoff_t index) |
800 | { |
801 | struct mempolicy mpol, *spol; |
802 | struct vm_area_struct pvma; |
803 | |
804 | spol = mpol_cond_copy(&mpol, |
805 | mpol_shared_policy_lookup(&info->policy, index)); |
806 | |
807 | /* Create a pseudo vma that just contains the policy */ |
808 | pvma.vm_start = 0; |
809 | pvma.vm_pgoff = index; |
810 | pvma.vm_ops = NULL; |
811 | pvma.vm_policy = spol; |
812 | return swapin_readahead(swap, gfp, &pvma, 0); |
813 | } |
814 | |
815 | static struct page *shmem_alloc_page(gfp_t gfp, |
816 | struct shmem_inode_info *info, pgoff_t index) |
817 | { |
818 | struct vm_area_struct pvma; |
819 | |
820 | /* Create a pseudo vma that just contains the policy */ |
821 | pvma.vm_start = 0; |
822 | pvma.vm_pgoff = index; |
823 | pvma.vm_ops = NULL; |
824 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
825 | |
826 | /* |
827 | * alloc_page_vma() will drop the shared policy reference |
828 | */ |
829 | return alloc_page_vma(gfp, &pvma, 0); |
830 | } |
831 | #else /* !CONFIG_NUMA */ |
832 | #ifdef CONFIG_TMPFS |
833 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
834 | { |
835 | } |
836 | #endif /* CONFIG_TMPFS */ |
837 | |
838 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
839 | struct shmem_inode_info *info, pgoff_t index) |
840 | { |
841 | return swapin_readahead(swap, gfp, NULL, 0); |
842 | } |
843 | |
844 | static inline struct page *shmem_alloc_page(gfp_t gfp, |
845 | struct shmem_inode_info *info, pgoff_t index) |
846 | { |
847 | return alloc_page(gfp); |
848 | } |
849 | #endif /* CONFIG_NUMA */ |
850 | |
851 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
852 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
853 | { |
854 | return NULL; |
855 | } |
856 | #endif |
857 | |
858 | /* |
859 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate |
860 | * |
861 | * If we allocate a new one we do not mark it dirty. That's up to the |
862 | * vm. If we swap it in we mark it dirty since we also free the swap |
863 | * entry since a page cannot live in both the swap and page cache |
864 | */ |
865 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
866 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) |
867 | { |
868 | struct address_space *mapping = inode->i_mapping; |
869 | struct shmem_inode_info *info; |
870 | struct shmem_sb_info *sbinfo; |
871 | struct page *page; |
872 | swp_entry_t swap; |
873 | int error; |
874 | int once = 0; |
875 | |
876 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) |
877 | return -EFBIG; |
878 | repeat: |
879 | swap.val = 0; |
880 | page = find_lock_page(mapping, index); |
881 | if (radix_tree_exceptional_entry(page)) { |
882 | swap = radix_to_swp_entry(page); |
883 | page = NULL; |
884 | } |
885 | |
886 | if (sgp != SGP_WRITE && |
887 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
888 | error = -EINVAL; |
889 | goto failed; |
890 | } |
891 | |
892 | if (page || (sgp == SGP_READ && !swap.val)) { |
893 | /* |
894 | * Once we can get the page lock, it must be uptodate: |
895 | * if there were an error in reading back from swap, |
896 | * the page would not be inserted into the filecache. |
897 | */ |
898 | BUG_ON(page && !PageUptodate(page)); |
899 | *pagep = page; |
900 | return 0; |
901 | } |
902 | |
903 | /* |
904 | * Fast cache lookup did not find it: |
905 | * bring it back from swap or allocate. |
906 | */ |
907 | info = SHMEM_I(inode); |
908 | sbinfo = SHMEM_SB(inode->i_sb); |
909 | |
910 | if (swap.val) { |
911 | /* Look it up and read it in.. */ |
912 | page = lookup_swap_cache(swap); |
913 | if (!page) { |
914 | /* here we actually do the io */ |
915 | if (fault_type) |
916 | *fault_type |= VM_FAULT_MAJOR; |
917 | page = shmem_swapin(swap, gfp, info, index); |
918 | if (!page) { |
919 | error = -ENOMEM; |
920 | goto failed; |
921 | } |
922 | } |
923 | |
924 | /* We have to do this with page locked to prevent races */ |
925 | lock_page(page); |
926 | if (!PageUptodate(page)) { |
927 | error = -EIO; |
928 | goto failed; |
929 | } |
930 | wait_on_page_writeback(page); |
931 | |
932 | /* Someone may have already done it for us */ |
933 | if (page->mapping) { |
934 | if (page->mapping == mapping && |
935 | page->index == index) |
936 | goto done; |
937 | error = -EEXIST; |
938 | goto failed; |
939 | } |
940 | |
941 | error = mem_cgroup_cache_charge(page, current->mm, |
942 | gfp & GFP_RECLAIM_MASK); |
943 | if (!error) |
944 | error = shmem_add_to_page_cache(page, mapping, index, |
945 | gfp, swp_to_radix_entry(swap)); |
946 | if (error) |
947 | goto failed; |
948 | |
949 | spin_lock(&info->lock); |
950 | info->swapped--; |
951 | shmem_recalc_inode(inode); |
952 | spin_unlock(&info->lock); |
953 | |
954 | delete_from_swap_cache(page); |
955 | set_page_dirty(page); |
956 | swap_free(swap); |
957 | |
958 | } else { |
959 | if (shmem_acct_block(info->flags)) { |
960 | error = -ENOSPC; |
961 | goto failed; |
962 | } |
963 | if (sbinfo->max_blocks) { |
964 | if (percpu_counter_compare(&sbinfo->used_blocks, |
965 | sbinfo->max_blocks) >= 0) { |
966 | error = -ENOSPC; |
967 | goto unacct; |
968 | } |
969 | percpu_counter_inc(&sbinfo->used_blocks); |
970 | } |
971 | |
972 | page = shmem_alloc_page(gfp, info, index); |
973 | if (!page) { |
974 | error = -ENOMEM; |
975 | goto decused; |
976 | } |
977 | |
978 | SetPageSwapBacked(page); |
979 | __set_page_locked(page); |
980 | error = mem_cgroup_cache_charge(page, current->mm, |
981 | gfp & GFP_RECLAIM_MASK); |
982 | if (!error) |
983 | error = shmem_add_to_page_cache(page, mapping, index, |
984 | gfp, NULL); |
985 | if (error) |
986 | goto decused; |
987 | lru_cache_add_anon(page); |
988 | |
989 | spin_lock(&info->lock); |
990 | info->alloced++; |
991 | inode->i_blocks += BLOCKS_PER_PAGE; |
992 | shmem_recalc_inode(inode); |
993 | spin_unlock(&info->lock); |
994 | |
995 | clear_highpage(page); |
996 | flush_dcache_page(page); |
997 | SetPageUptodate(page); |
998 | if (sgp == SGP_DIRTY) |
999 | set_page_dirty(page); |
1000 | } |
1001 | done: |
1002 | /* Perhaps the file has been truncated since we checked */ |
1003 | if (sgp != SGP_WRITE && |
1004 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
1005 | error = -EINVAL; |
1006 | goto trunc; |
1007 | } |
1008 | *pagep = page; |
1009 | return 0; |
1010 | |
1011 | /* |
1012 | * Error recovery. |
1013 | */ |
1014 | trunc: |
1015 | ClearPageDirty(page); |
1016 | delete_from_page_cache(page); |
1017 | spin_lock(&info->lock); |
1018 | info->alloced--; |
1019 | inode->i_blocks -= BLOCKS_PER_PAGE; |
1020 | spin_unlock(&info->lock); |
1021 | decused: |
1022 | if (sbinfo->max_blocks) |
1023 | percpu_counter_add(&sbinfo->used_blocks, -1); |
1024 | unacct: |
1025 | shmem_unacct_blocks(info->flags, 1); |
1026 | failed: |
1027 | if (swap.val && error != -EINVAL) { |
1028 | struct page *test = find_get_page(mapping, index); |
1029 | if (test && !radix_tree_exceptional_entry(test)) |
1030 | page_cache_release(test); |
1031 | /* Have another try if the entry has changed */ |
1032 | if (test != swp_to_radix_entry(swap)) |
1033 | error = -EEXIST; |
1034 | } |
1035 | if (page) { |
1036 | unlock_page(page); |
1037 | page_cache_release(page); |
1038 | } |
1039 | if (error == -ENOSPC && !once++) { |
1040 | info = SHMEM_I(inode); |
1041 | spin_lock(&info->lock); |
1042 | shmem_recalc_inode(inode); |
1043 | spin_unlock(&info->lock); |
1044 | goto repeat; |
1045 | } |
1046 | if (error == -EEXIST) |
1047 | goto repeat; |
1048 | return error; |
1049 | } |
1050 | |
1051 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1052 | { |
1053 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
1054 | int error; |
1055 | int ret = VM_FAULT_LOCKED; |
1056 | |
1057 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
1058 | if (error) |
1059 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
1060 | |
1061 | if (ret & VM_FAULT_MAJOR) { |
1062 | count_vm_event(PGMAJFAULT); |
1063 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
1064 | } |
1065 | return ret; |
1066 | } |
1067 | |
1068 | #ifdef CONFIG_NUMA |
1069 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) |
1070 | { |
1071 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
1072 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); |
1073 | } |
1074 | |
1075 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
1076 | unsigned long addr) |
1077 | { |
1078 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
1079 | pgoff_t index; |
1080 | |
1081 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
1082 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); |
1083 | } |
1084 | #endif |
1085 | |
1086 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
1087 | { |
1088 | struct inode *inode = file->f_path.dentry->d_inode; |
1089 | struct shmem_inode_info *info = SHMEM_I(inode); |
1090 | int retval = -ENOMEM; |
1091 | |
1092 | spin_lock(&info->lock); |
1093 | if (lock && !(info->flags & VM_LOCKED)) { |
1094 | if (!user_shm_lock(inode->i_size, user)) |
1095 | goto out_nomem; |
1096 | info->flags |= VM_LOCKED; |
1097 | mapping_set_unevictable(file->f_mapping); |
1098 | } |
1099 | if (!lock && (info->flags & VM_LOCKED) && user) { |
1100 | user_shm_unlock(inode->i_size, user); |
1101 | info->flags &= ~VM_LOCKED; |
1102 | mapping_clear_unevictable(file->f_mapping); |
1103 | } |
1104 | retval = 0; |
1105 | |
1106 | out_nomem: |
1107 | spin_unlock(&info->lock); |
1108 | return retval; |
1109 | } |
1110 | |
1111 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
1112 | { |
1113 | file_accessed(file); |
1114 | vma->vm_ops = &shmem_vm_ops; |
1115 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1116 | return 0; |
1117 | } |
1118 | |
1119 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
1120 | umode_t mode, dev_t dev, unsigned long flags) |
1121 | { |
1122 | struct inode *inode; |
1123 | struct shmem_inode_info *info; |
1124 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
1125 | |
1126 | if (shmem_reserve_inode(sb)) |
1127 | return NULL; |
1128 | |
1129 | inode = new_inode(sb); |
1130 | if (inode) { |
1131 | inode->i_ino = get_next_ino(); |
1132 | inode_init_owner(inode, dir, mode); |
1133 | inode->i_blocks = 0; |
1134 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
1135 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1136 | inode->i_generation = get_seconds(); |
1137 | info = SHMEM_I(inode); |
1138 | memset(info, 0, (char *)inode - (char *)info); |
1139 | spin_lock_init(&info->lock); |
1140 | info->flags = flags & VM_NORESERVE; |
1141 | INIT_LIST_HEAD(&info->swaplist); |
1142 | INIT_LIST_HEAD(&info->xattr_list); |
1143 | cache_no_acl(inode); |
1144 | |
1145 | switch (mode & S_IFMT) { |
1146 | default: |
1147 | inode->i_op = &shmem_special_inode_operations; |
1148 | init_special_inode(inode, mode, dev); |
1149 | break; |
1150 | case S_IFREG: |
1151 | inode->i_mapping->a_ops = &shmem_aops; |
1152 | inode->i_op = &shmem_inode_operations; |
1153 | inode->i_fop = &shmem_file_operations; |
1154 | mpol_shared_policy_init(&info->policy, |
1155 | shmem_get_sbmpol(sbinfo)); |
1156 | break; |
1157 | case S_IFDIR: |
1158 | inc_nlink(inode); |
1159 | /* Some things misbehave if size == 0 on a directory */ |
1160 | inode->i_size = 2 * BOGO_DIRENT_SIZE; |
1161 | inode->i_op = &shmem_dir_inode_operations; |
1162 | inode->i_fop = &simple_dir_operations; |
1163 | break; |
1164 | case S_IFLNK: |
1165 | /* |
1166 | * Must not load anything in the rbtree, |
1167 | * mpol_free_shared_policy will not be called. |
1168 | */ |
1169 | mpol_shared_policy_init(&info->policy, NULL); |
1170 | break; |
1171 | } |
1172 | } else |
1173 | shmem_free_inode(sb); |
1174 | return inode; |
1175 | } |
1176 | |
1177 | #ifdef CONFIG_TMPFS |
1178 | static const struct inode_operations shmem_symlink_inode_operations; |
1179 | static const struct inode_operations shmem_short_symlink_operations; |
1180 | |
1181 | static int |
1182 | shmem_write_begin(struct file *file, struct address_space *mapping, |
1183 | loff_t pos, unsigned len, unsigned flags, |
1184 | struct page **pagep, void **fsdata) |
1185 | { |
1186 | struct inode *inode = mapping->host; |
1187 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
1188 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
1189 | } |
1190 | |
1191 | static int |
1192 | shmem_write_end(struct file *file, struct address_space *mapping, |
1193 | loff_t pos, unsigned len, unsigned copied, |
1194 | struct page *page, void *fsdata) |
1195 | { |
1196 | struct inode *inode = mapping->host; |
1197 | |
1198 | if (pos + copied > inode->i_size) |
1199 | i_size_write(inode, pos + copied); |
1200 | |
1201 | set_page_dirty(page); |
1202 | unlock_page(page); |
1203 | page_cache_release(page); |
1204 | |
1205 | return copied; |
1206 | } |
1207 | |
1208 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) |
1209 | { |
1210 | struct inode *inode = filp->f_path.dentry->d_inode; |
1211 | struct address_space *mapping = inode->i_mapping; |
1212 | pgoff_t index; |
1213 | unsigned long offset; |
1214 | enum sgp_type sgp = SGP_READ; |
1215 | |
1216 | /* |
1217 | * Might this read be for a stacking filesystem? Then when reading |
1218 | * holes of a sparse file, we actually need to allocate those pages, |
1219 | * and even mark them dirty, so it cannot exceed the max_blocks limit. |
1220 | */ |
1221 | if (segment_eq(get_fs(), KERNEL_DS)) |
1222 | sgp = SGP_DIRTY; |
1223 | |
1224 | index = *ppos >> PAGE_CACHE_SHIFT; |
1225 | offset = *ppos & ~PAGE_CACHE_MASK; |
1226 | |
1227 | for (;;) { |
1228 | struct page *page = NULL; |
1229 | pgoff_t end_index; |
1230 | unsigned long nr, ret; |
1231 | loff_t i_size = i_size_read(inode); |
1232 | |
1233 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1234 | if (index > end_index) |
1235 | break; |
1236 | if (index == end_index) { |
1237 | nr = i_size & ~PAGE_CACHE_MASK; |
1238 | if (nr <= offset) |
1239 | break; |
1240 | } |
1241 | |
1242 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); |
1243 | if (desc->error) { |
1244 | if (desc->error == -EINVAL) |
1245 | desc->error = 0; |
1246 | break; |
1247 | } |
1248 | if (page) |
1249 | unlock_page(page); |
1250 | |
1251 | /* |
1252 | * We must evaluate after, since reads (unlike writes) |
1253 | * are called without i_mutex protection against truncate |
1254 | */ |
1255 | nr = PAGE_CACHE_SIZE; |
1256 | i_size = i_size_read(inode); |
1257 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1258 | if (index == end_index) { |
1259 | nr = i_size & ~PAGE_CACHE_MASK; |
1260 | if (nr <= offset) { |
1261 | if (page) |
1262 | page_cache_release(page); |
1263 | break; |
1264 | } |
1265 | } |
1266 | nr -= offset; |
1267 | |
1268 | if (page) { |
1269 | /* |
1270 | * If users can be writing to this page using arbitrary |
1271 | * virtual addresses, take care about potential aliasing |
1272 | * before reading the page on the kernel side. |
1273 | */ |
1274 | if (mapping_writably_mapped(mapping)) |
1275 | flush_dcache_page(page); |
1276 | /* |
1277 | * Mark the page accessed if we read the beginning. |
1278 | */ |
1279 | if (!offset) |
1280 | mark_page_accessed(page); |
1281 | } else { |
1282 | page = ZERO_PAGE(0); |
1283 | page_cache_get(page); |
1284 | } |
1285 | |
1286 | /* |
1287 | * Ok, we have the page, and it's up-to-date, so |
1288 | * now we can copy it to user space... |
1289 | * |
1290 | * The actor routine returns how many bytes were actually used.. |
1291 | * NOTE! This may not be the same as how much of a user buffer |
1292 | * we filled up (we may be padding etc), so we can only update |
1293 | * "pos" here (the actor routine has to update the user buffer |
1294 | * pointers and the remaining count). |
1295 | */ |
1296 | ret = actor(desc, page, offset, nr); |
1297 | offset += ret; |
1298 | index += offset >> PAGE_CACHE_SHIFT; |
1299 | offset &= ~PAGE_CACHE_MASK; |
1300 | |
1301 | page_cache_release(page); |
1302 | if (ret != nr || !desc->count) |
1303 | break; |
1304 | |
1305 | cond_resched(); |
1306 | } |
1307 | |
1308 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
1309 | file_accessed(filp); |
1310 | } |
1311 | |
1312 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, |
1313 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
1314 | { |
1315 | struct file *filp = iocb->ki_filp; |
1316 | ssize_t retval; |
1317 | unsigned long seg; |
1318 | size_t count; |
1319 | loff_t *ppos = &iocb->ki_pos; |
1320 | |
1321 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1322 | if (retval) |
1323 | return retval; |
1324 | |
1325 | for (seg = 0; seg < nr_segs; seg++) { |
1326 | read_descriptor_t desc; |
1327 | |
1328 | desc.written = 0; |
1329 | desc.arg.buf = iov[seg].iov_base; |
1330 | desc.count = iov[seg].iov_len; |
1331 | if (desc.count == 0) |
1332 | continue; |
1333 | desc.error = 0; |
1334 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); |
1335 | retval += desc.written; |
1336 | if (desc.error) { |
1337 | retval = retval ?: desc.error; |
1338 | break; |
1339 | } |
1340 | if (desc.count > 0) |
1341 | break; |
1342 | } |
1343 | return retval; |
1344 | } |
1345 | |
1346 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, |
1347 | struct pipe_inode_info *pipe, size_t len, |
1348 | unsigned int flags) |
1349 | { |
1350 | struct address_space *mapping = in->f_mapping; |
1351 | struct inode *inode = mapping->host; |
1352 | unsigned int loff, nr_pages, req_pages; |
1353 | struct page *pages[PIPE_DEF_BUFFERS]; |
1354 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1355 | struct page *page; |
1356 | pgoff_t index, end_index; |
1357 | loff_t isize, left; |
1358 | int error, page_nr; |
1359 | struct splice_pipe_desc spd = { |
1360 | .pages = pages, |
1361 | .partial = partial, |
1362 | .flags = flags, |
1363 | .ops = &page_cache_pipe_buf_ops, |
1364 | .spd_release = spd_release_page, |
1365 | }; |
1366 | |
1367 | isize = i_size_read(inode); |
1368 | if (unlikely(*ppos >= isize)) |
1369 | return 0; |
1370 | |
1371 | left = isize - *ppos; |
1372 | if (unlikely(left < len)) |
1373 | len = left; |
1374 | |
1375 | if (splice_grow_spd(pipe, &spd)) |
1376 | return -ENOMEM; |
1377 | |
1378 | index = *ppos >> PAGE_CACHE_SHIFT; |
1379 | loff = *ppos & ~PAGE_CACHE_MASK; |
1380 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1381 | nr_pages = min(req_pages, pipe->buffers); |
1382 | |
1383 | spd.nr_pages = find_get_pages_contig(mapping, index, |
1384 | nr_pages, spd.pages); |
1385 | index += spd.nr_pages; |
1386 | error = 0; |
1387 | |
1388 | while (spd.nr_pages < nr_pages) { |
1389 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); |
1390 | if (error) |
1391 | break; |
1392 | unlock_page(page); |
1393 | spd.pages[spd.nr_pages++] = page; |
1394 | index++; |
1395 | } |
1396 | |
1397 | index = *ppos >> PAGE_CACHE_SHIFT; |
1398 | nr_pages = spd.nr_pages; |
1399 | spd.nr_pages = 0; |
1400 | |
1401 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
1402 | unsigned int this_len; |
1403 | |
1404 | if (!len) |
1405 | break; |
1406 | |
1407 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
1408 | page = spd.pages[page_nr]; |
1409 | |
1410 | if (!PageUptodate(page) || page->mapping != mapping) { |
1411 | error = shmem_getpage(inode, index, &page, |
1412 | SGP_CACHE, NULL); |
1413 | if (error) |
1414 | break; |
1415 | unlock_page(page); |
1416 | page_cache_release(spd.pages[page_nr]); |
1417 | spd.pages[page_nr] = page; |
1418 | } |
1419 | |
1420 | isize = i_size_read(inode); |
1421 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
1422 | if (unlikely(!isize || index > end_index)) |
1423 | break; |
1424 | |
1425 | if (end_index == index) { |
1426 | unsigned int plen; |
1427 | |
1428 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
1429 | if (plen <= loff) |
1430 | break; |
1431 | |
1432 | this_len = min(this_len, plen - loff); |
1433 | len = this_len; |
1434 | } |
1435 | |
1436 | spd.partial[page_nr].offset = loff; |
1437 | spd.partial[page_nr].len = this_len; |
1438 | len -= this_len; |
1439 | loff = 0; |
1440 | spd.nr_pages++; |
1441 | index++; |
1442 | } |
1443 | |
1444 | while (page_nr < nr_pages) |
1445 | page_cache_release(spd.pages[page_nr++]); |
1446 | |
1447 | if (spd.nr_pages) |
1448 | error = splice_to_pipe(pipe, &spd); |
1449 | |
1450 | splice_shrink_spd(pipe, &spd); |
1451 | |
1452 | if (error > 0) { |
1453 | *ppos += error; |
1454 | file_accessed(in); |
1455 | } |
1456 | return error; |
1457 | } |
1458 | |
1459 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
1460 | { |
1461 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
1462 | |
1463 | buf->f_type = TMPFS_MAGIC; |
1464 | buf->f_bsize = PAGE_CACHE_SIZE; |
1465 | buf->f_namelen = NAME_MAX; |
1466 | if (sbinfo->max_blocks) { |
1467 | buf->f_blocks = sbinfo->max_blocks; |
1468 | buf->f_bavail = |
1469 | buf->f_bfree = sbinfo->max_blocks - |
1470 | percpu_counter_sum(&sbinfo->used_blocks); |
1471 | } |
1472 | if (sbinfo->max_inodes) { |
1473 | buf->f_files = sbinfo->max_inodes; |
1474 | buf->f_ffree = sbinfo->free_inodes; |
1475 | } |
1476 | /* else leave those fields 0 like simple_statfs */ |
1477 | return 0; |
1478 | } |
1479 | |
1480 | /* |
1481 | * File creation. Allocate an inode, and we're done.. |
1482 | */ |
1483 | static int |
1484 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1485 | { |
1486 | struct inode *inode; |
1487 | int error = -ENOSPC; |
1488 | |
1489 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
1490 | if (inode) { |
1491 | error = security_inode_init_security(inode, dir, |
1492 | &dentry->d_name, |
1493 | NULL, NULL); |
1494 | if (error) { |
1495 | if (error != -EOPNOTSUPP) { |
1496 | iput(inode); |
1497 | return error; |
1498 | } |
1499 | } |
1500 | #ifdef CONFIG_TMPFS_POSIX_ACL |
1501 | error = generic_acl_init(inode, dir); |
1502 | if (error) { |
1503 | iput(inode); |
1504 | return error; |
1505 | } |
1506 | #else |
1507 | error = 0; |
1508 | #endif |
1509 | dir->i_size += BOGO_DIRENT_SIZE; |
1510 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1511 | d_instantiate(dentry, inode); |
1512 | dget(dentry); /* Extra count - pin the dentry in core */ |
1513 | } |
1514 | return error; |
1515 | } |
1516 | |
1517 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1518 | { |
1519 | int error; |
1520 | |
1521 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
1522 | return error; |
1523 | inc_nlink(dir); |
1524 | return 0; |
1525 | } |
1526 | |
1527 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
1528 | struct nameidata *nd) |
1529 | { |
1530 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
1531 | } |
1532 | |
1533 | /* |
1534 | * Link a file.. |
1535 | */ |
1536 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
1537 | { |
1538 | struct inode *inode = old_dentry->d_inode; |
1539 | int ret; |
1540 | |
1541 | /* |
1542 | * No ordinary (disk based) filesystem counts links as inodes; |
1543 | * but each new link needs a new dentry, pinning lowmem, and |
1544 | * tmpfs dentries cannot be pruned until they are unlinked. |
1545 | */ |
1546 | ret = shmem_reserve_inode(inode->i_sb); |
1547 | if (ret) |
1548 | goto out; |
1549 | |
1550 | dir->i_size += BOGO_DIRENT_SIZE; |
1551 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1552 | inc_nlink(inode); |
1553 | ihold(inode); /* New dentry reference */ |
1554 | dget(dentry); /* Extra pinning count for the created dentry */ |
1555 | d_instantiate(dentry, inode); |
1556 | out: |
1557 | return ret; |
1558 | } |
1559 | |
1560 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
1561 | { |
1562 | struct inode *inode = dentry->d_inode; |
1563 | |
1564 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
1565 | shmem_free_inode(inode->i_sb); |
1566 | |
1567 | dir->i_size -= BOGO_DIRENT_SIZE; |
1568 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1569 | drop_nlink(inode); |
1570 | dput(dentry); /* Undo the count from "create" - this does all the work */ |
1571 | return 0; |
1572 | } |
1573 | |
1574 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
1575 | { |
1576 | if (!simple_empty(dentry)) |
1577 | return -ENOTEMPTY; |
1578 | |
1579 | drop_nlink(dentry->d_inode); |
1580 | drop_nlink(dir); |
1581 | return shmem_unlink(dir, dentry); |
1582 | } |
1583 | |
1584 | /* |
1585 | * The VFS layer already does all the dentry stuff for rename, |
1586 | * we just have to decrement the usage count for the target if |
1587 | * it exists so that the VFS layer correctly free's it when it |
1588 | * gets overwritten. |
1589 | */ |
1590 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
1591 | { |
1592 | struct inode *inode = old_dentry->d_inode; |
1593 | int they_are_dirs = S_ISDIR(inode->i_mode); |
1594 | |
1595 | if (!simple_empty(new_dentry)) |
1596 | return -ENOTEMPTY; |
1597 | |
1598 | if (new_dentry->d_inode) { |
1599 | (void) shmem_unlink(new_dir, new_dentry); |
1600 | if (they_are_dirs) |
1601 | drop_nlink(old_dir); |
1602 | } else if (they_are_dirs) { |
1603 | drop_nlink(old_dir); |
1604 | inc_nlink(new_dir); |
1605 | } |
1606 | |
1607 | old_dir->i_size -= BOGO_DIRENT_SIZE; |
1608 | new_dir->i_size += BOGO_DIRENT_SIZE; |
1609 | old_dir->i_ctime = old_dir->i_mtime = |
1610 | new_dir->i_ctime = new_dir->i_mtime = |
1611 | inode->i_ctime = CURRENT_TIME; |
1612 | return 0; |
1613 | } |
1614 | |
1615 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
1616 | { |
1617 | int error; |
1618 | int len; |
1619 | struct inode *inode; |
1620 | struct page *page; |
1621 | char *kaddr; |
1622 | struct shmem_inode_info *info; |
1623 | |
1624 | len = strlen(symname) + 1; |
1625 | if (len > PAGE_CACHE_SIZE) |
1626 | return -ENAMETOOLONG; |
1627 | |
1628 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
1629 | if (!inode) |
1630 | return -ENOSPC; |
1631 | |
1632 | error = security_inode_init_security(inode, dir, &dentry->d_name, |
1633 | NULL, NULL); |
1634 | if (error) { |
1635 | if (error != -EOPNOTSUPP) { |
1636 | iput(inode); |
1637 | return error; |
1638 | } |
1639 | error = 0; |
1640 | } |
1641 | |
1642 | info = SHMEM_I(inode); |
1643 | inode->i_size = len-1; |
1644 | if (len <= SHORT_SYMLINK_LEN) { |
1645 | info->symlink = kmemdup(symname, len, GFP_KERNEL); |
1646 | if (!info->symlink) { |
1647 | iput(inode); |
1648 | return -ENOMEM; |
1649 | } |
1650 | inode->i_op = &shmem_short_symlink_operations; |
1651 | } else { |
1652 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
1653 | if (error) { |
1654 | iput(inode); |
1655 | return error; |
1656 | } |
1657 | inode->i_mapping->a_ops = &shmem_aops; |
1658 | inode->i_op = &shmem_symlink_inode_operations; |
1659 | kaddr = kmap_atomic(page, KM_USER0); |
1660 | memcpy(kaddr, symname, len); |
1661 | kunmap_atomic(kaddr, KM_USER0); |
1662 | set_page_dirty(page); |
1663 | unlock_page(page); |
1664 | page_cache_release(page); |
1665 | } |
1666 | dir->i_size += BOGO_DIRENT_SIZE; |
1667 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1668 | d_instantiate(dentry, inode); |
1669 | dget(dentry); |
1670 | return 0; |
1671 | } |
1672 | |
1673 | static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) |
1674 | { |
1675 | nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); |
1676 | return NULL; |
1677 | } |
1678 | |
1679 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
1680 | { |
1681 | struct page *page = NULL; |
1682 | int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
1683 | nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); |
1684 | if (page) |
1685 | unlock_page(page); |
1686 | return page; |
1687 | } |
1688 | |
1689 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
1690 | { |
1691 | if (!IS_ERR(nd_get_link(nd))) { |
1692 | struct page *page = cookie; |
1693 | kunmap(page); |
1694 | mark_page_accessed(page); |
1695 | page_cache_release(page); |
1696 | } |
1697 | } |
1698 | |
1699 | #ifdef CONFIG_TMPFS_XATTR |
1700 | /* |
1701 | * Superblocks without xattr inode operations may get some security.* xattr |
1702 | * support from the LSM "for free". As soon as we have any other xattrs |
1703 | * like ACLs, we also need to implement the security.* handlers at |
1704 | * filesystem level, though. |
1705 | */ |
1706 | |
1707 | static int shmem_xattr_get(struct dentry *dentry, const char *name, |
1708 | void *buffer, size_t size) |
1709 | { |
1710 | struct shmem_inode_info *info; |
1711 | struct shmem_xattr *xattr; |
1712 | int ret = -ENODATA; |
1713 | |
1714 | info = SHMEM_I(dentry->d_inode); |
1715 | |
1716 | spin_lock(&info->lock); |
1717 | list_for_each_entry(xattr, &info->xattr_list, list) { |
1718 | if (strcmp(name, xattr->name)) |
1719 | continue; |
1720 | |
1721 | ret = xattr->size; |
1722 | if (buffer) { |
1723 | if (size < xattr->size) |
1724 | ret = -ERANGE; |
1725 | else |
1726 | memcpy(buffer, xattr->value, xattr->size); |
1727 | } |
1728 | break; |
1729 | } |
1730 | spin_unlock(&info->lock); |
1731 | return ret; |
1732 | } |
1733 | |
1734 | static int shmem_xattr_set(struct dentry *dentry, const char *name, |
1735 | const void *value, size_t size, int flags) |
1736 | { |
1737 | struct inode *inode = dentry->d_inode; |
1738 | struct shmem_inode_info *info = SHMEM_I(inode); |
1739 | struct shmem_xattr *xattr; |
1740 | struct shmem_xattr *new_xattr = NULL; |
1741 | size_t len; |
1742 | int err = 0; |
1743 | |
1744 | /* value == NULL means remove */ |
1745 | if (value) { |
1746 | /* wrap around? */ |
1747 | len = sizeof(*new_xattr) + size; |
1748 | if (len <= sizeof(*new_xattr)) |
1749 | return -ENOMEM; |
1750 | |
1751 | new_xattr = kmalloc(len, GFP_KERNEL); |
1752 | if (!new_xattr) |
1753 | return -ENOMEM; |
1754 | |
1755 | new_xattr->name = kstrdup(name, GFP_KERNEL); |
1756 | if (!new_xattr->name) { |
1757 | kfree(new_xattr); |
1758 | return -ENOMEM; |
1759 | } |
1760 | |
1761 | new_xattr->size = size; |
1762 | memcpy(new_xattr->value, value, size); |
1763 | } |
1764 | |
1765 | spin_lock(&info->lock); |
1766 | list_for_each_entry(xattr, &info->xattr_list, list) { |
1767 | if (!strcmp(name, xattr->name)) { |
1768 | if (flags & XATTR_CREATE) { |
1769 | xattr = new_xattr; |
1770 | err = -EEXIST; |
1771 | } else if (new_xattr) { |
1772 | list_replace(&xattr->list, &new_xattr->list); |
1773 | } else { |
1774 | list_del(&xattr->list); |
1775 | } |
1776 | goto out; |
1777 | } |
1778 | } |
1779 | if (flags & XATTR_REPLACE) { |
1780 | xattr = new_xattr; |
1781 | err = -ENODATA; |
1782 | } else { |
1783 | list_add(&new_xattr->list, &info->xattr_list); |
1784 | xattr = NULL; |
1785 | } |
1786 | out: |
1787 | spin_unlock(&info->lock); |
1788 | if (xattr) |
1789 | kfree(xattr->name); |
1790 | kfree(xattr); |
1791 | return err; |
1792 | } |
1793 | |
1794 | static const struct xattr_handler *shmem_xattr_handlers[] = { |
1795 | #ifdef CONFIG_TMPFS_POSIX_ACL |
1796 | &generic_acl_access_handler, |
1797 | &generic_acl_default_handler, |
1798 | #endif |
1799 | NULL |
1800 | }; |
1801 | |
1802 | static int shmem_xattr_validate(const char *name) |
1803 | { |
1804 | struct { const char *prefix; size_t len; } arr[] = { |
1805 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, |
1806 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } |
1807 | }; |
1808 | int i; |
1809 | |
1810 | for (i = 0; i < ARRAY_SIZE(arr); i++) { |
1811 | size_t preflen = arr[i].len; |
1812 | if (strncmp(name, arr[i].prefix, preflen) == 0) { |
1813 | if (!name[preflen]) |
1814 | return -EINVAL; |
1815 | return 0; |
1816 | } |
1817 | } |
1818 | return -EOPNOTSUPP; |
1819 | } |
1820 | |
1821 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, |
1822 | void *buffer, size_t size) |
1823 | { |
1824 | int err; |
1825 | |
1826 | /* |
1827 | * If this is a request for a synthetic attribute in the system.* |
1828 | * namespace use the generic infrastructure to resolve a handler |
1829 | * for it via sb->s_xattr. |
1830 | */ |
1831 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
1832 | return generic_getxattr(dentry, name, buffer, size); |
1833 | |
1834 | err = shmem_xattr_validate(name); |
1835 | if (err) |
1836 | return err; |
1837 | |
1838 | return shmem_xattr_get(dentry, name, buffer, size); |
1839 | } |
1840 | |
1841 | static int shmem_setxattr(struct dentry *dentry, const char *name, |
1842 | const void *value, size_t size, int flags) |
1843 | { |
1844 | int err; |
1845 | |
1846 | /* |
1847 | * If this is a request for a synthetic attribute in the system.* |
1848 | * namespace use the generic infrastructure to resolve a handler |
1849 | * for it via sb->s_xattr. |
1850 | */ |
1851 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
1852 | return generic_setxattr(dentry, name, value, size, flags); |
1853 | |
1854 | err = shmem_xattr_validate(name); |
1855 | if (err) |
1856 | return err; |
1857 | |
1858 | if (size == 0) |
1859 | value = ""; /* empty EA, do not remove */ |
1860 | |
1861 | return shmem_xattr_set(dentry, name, value, size, flags); |
1862 | |
1863 | } |
1864 | |
1865 | static int shmem_removexattr(struct dentry *dentry, const char *name) |
1866 | { |
1867 | int err; |
1868 | |
1869 | /* |
1870 | * If this is a request for a synthetic attribute in the system.* |
1871 | * namespace use the generic infrastructure to resolve a handler |
1872 | * for it via sb->s_xattr. |
1873 | */ |
1874 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
1875 | return generic_removexattr(dentry, name); |
1876 | |
1877 | err = shmem_xattr_validate(name); |
1878 | if (err) |
1879 | return err; |
1880 | |
1881 | return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE); |
1882 | } |
1883 | |
1884 | static bool xattr_is_trusted(const char *name) |
1885 | { |
1886 | return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); |
1887 | } |
1888 | |
1889 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) |
1890 | { |
1891 | bool trusted = capable(CAP_SYS_ADMIN); |
1892 | struct shmem_xattr *xattr; |
1893 | struct shmem_inode_info *info; |
1894 | size_t used = 0; |
1895 | |
1896 | info = SHMEM_I(dentry->d_inode); |
1897 | |
1898 | spin_lock(&info->lock); |
1899 | list_for_each_entry(xattr, &info->xattr_list, list) { |
1900 | size_t len; |
1901 | |
1902 | /* skip "trusted." attributes for unprivileged callers */ |
1903 | if (!trusted && xattr_is_trusted(xattr->name)) |
1904 | continue; |
1905 | |
1906 | len = strlen(xattr->name) + 1; |
1907 | used += len; |
1908 | if (buffer) { |
1909 | if (size < used) { |
1910 | used = -ERANGE; |
1911 | break; |
1912 | } |
1913 | memcpy(buffer, xattr->name, len); |
1914 | buffer += len; |
1915 | } |
1916 | } |
1917 | spin_unlock(&info->lock); |
1918 | |
1919 | return used; |
1920 | } |
1921 | #endif /* CONFIG_TMPFS_XATTR */ |
1922 | |
1923 | static const struct inode_operations shmem_short_symlink_operations = { |
1924 | .readlink = generic_readlink, |
1925 | .follow_link = shmem_follow_short_symlink, |
1926 | #ifdef CONFIG_TMPFS_XATTR |
1927 | .setxattr = shmem_setxattr, |
1928 | .getxattr = shmem_getxattr, |
1929 | .listxattr = shmem_listxattr, |
1930 | .removexattr = shmem_removexattr, |
1931 | #endif |
1932 | }; |
1933 | |
1934 | static const struct inode_operations shmem_symlink_inode_operations = { |
1935 | .readlink = generic_readlink, |
1936 | .follow_link = shmem_follow_link, |
1937 | .put_link = shmem_put_link, |
1938 | #ifdef CONFIG_TMPFS_XATTR |
1939 | .setxattr = shmem_setxattr, |
1940 | .getxattr = shmem_getxattr, |
1941 | .listxattr = shmem_listxattr, |
1942 | .removexattr = shmem_removexattr, |
1943 | #endif |
1944 | }; |
1945 | |
1946 | static struct dentry *shmem_get_parent(struct dentry *child) |
1947 | { |
1948 | return ERR_PTR(-ESTALE); |
1949 | } |
1950 | |
1951 | static int shmem_match(struct inode *ino, void *vfh) |
1952 | { |
1953 | __u32 *fh = vfh; |
1954 | __u64 inum = fh[2]; |
1955 | inum = (inum << 32) | fh[1]; |
1956 | return ino->i_ino == inum && fh[0] == ino->i_generation; |
1957 | } |
1958 | |
1959 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
1960 | struct fid *fid, int fh_len, int fh_type) |
1961 | { |
1962 | struct inode *inode; |
1963 | struct dentry *dentry = NULL; |
1964 | u64 inum = fid->raw[2]; |
1965 | inum = (inum << 32) | fid->raw[1]; |
1966 | |
1967 | if (fh_len < 3) |
1968 | return NULL; |
1969 | |
1970 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
1971 | shmem_match, fid->raw); |
1972 | if (inode) { |
1973 | dentry = d_find_alias(inode); |
1974 | iput(inode); |
1975 | } |
1976 | |
1977 | return dentry; |
1978 | } |
1979 | |
1980 | static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, |
1981 | int connectable) |
1982 | { |
1983 | struct inode *inode = dentry->d_inode; |
1984 | |
1985 | if (*len < 3) { |
1986 | *len = 3; |
1987 | return 255; |
1988 | } |
1989 | |
1990 | if (inode_unhashed(inode)) { |
1991 | /* Unfortunately insert_inode_hash is not idempotent, |
1992 | * so as we hash inodes here rather than at creation |
1993 | * time, we need a lock to ensure we only try |
1994 | * to do it once |
1995 | */ |
1996 | static DEFINE_SPINLOCK(lock); |
1997 | spin_lock(&lock); |
1998 | if (inode_unhashed(inode)) |
1999 | __insert_inode_hash(inode, |
2000 | inode->i_ino + inode->i_generation); |
2001 | spin_unlock(&lock); |
2002 | } |
2003 | |
2004 | fh[0] = inode->i_generation; |
2005 | fh[1] = inode->i_ino; |
2006 | fh[2] = ((__u64)inode->i_ino) >> 32; |
2007 | |
2008 | *len = 3; |
2009 | return 1; |
2010 | } |
2011 | |
2012 | static const struct export_operations shmem_export_ops = { |
2013 | .get_parent = shmem_get_parent, |
2014 | .encode_fh = shmem_encode_fh, |
2015 | .fh_to_dentry = shmem_fh_to_dentry, |
2016 | }; |
2017 | |
2018 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
2019 | bool remount) |
2020 | { |
2021 | char *this_char, *value, *rest; |
2022 | |
2023 | while (options != NULL) { |
2024 | this_char = options; |
2025 | for (;;) { |
2026 | /* |
2027 | * NUL-terminate this option: unfortunately, |
2028 | * mount options form a comma-separated list, |
2029 | * but mpol's nodelist may also contain commas. |
2030 | */ |
2031 | options = strchr(options, ','); |
2032 | if (options == NULL) |
2033 | break; |
2034 | options++; |
2035 | if (!isdigit(*options)) { |
2036 | options[-1] = '\0'; |
2037 | break; |
2038 | } |
2039 | } |
2040 | if (!*this_char) |
2041 | continue; |
2042 | if ((value = strchr(this_char,'=')) != NULL) { |
2043 | *value++ = 0; |
2044 | } else { |
2045 | printk(KERN_ERR |
2046 | "tmpfs: No value for mount option '%s'\n", |
2047 | this_char); |
2048 | return 1; |
2049 | } |
2050 | |
2051 | if (!strcmp(this_char,"size")) { |
2052 | unsigned long long size; |
2053 | size = memparse(value,&rest); |
2054 | if (*rest == '%') { |
2055 | size <<= PAGE_SHIFT; |
2056 | size *= totalram_pages; |
2057 | do_div(size, 100); |
2058 | rest++; |
2059 | } |
2060 | if (*rest) |
2061 | goto bad_val; |
2062 | sbinfo->max_blocks = |
2063 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
2064 | } else if (!strcmp(this_char,"nr_blocks")) { |
2065 | sbinfo->max_blocks = memparse(value, &rest); |
2066 | if (*rest) |
2067 | goto bad_val; |
2068 | } else if (!strcmp(this_char,"nr_inodes")) { |
2069 | sbinfo->max_inodes = memparse(value, &rest); |
2070 | if (*rest) |
2071 | goto bad_val; |
2072 | } else if (!strcmp(this_char,"mode")) { |
2073 | if (remount) |
2074 | continue; |
2075 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
2076 | if (*rest) |
2077 | goto bad_val; |
2078 | } else if (!strcmp(this_char,"uid")) { |
2079 | if (remount) |
2080 | continue; |
2081 | sbinfo->uid = simple_strtoul(value, &rest, 0); |
2082 | if (*rest) |
2083 | goto bad_val; |
2084 | } else if (!strcmp(this_char,"gid")) { |
2085 | if (remount) |
2086 | continue; |
2087 | sbinfo->gid = simple_strtoul(value, &rest, 0); |
2088 | if (*rest) |
2089 | goto bad_val; |
2090 | } else if (!strcmp(this_char,"mpol")) { |
2091 | if (mpol_parse_str(value, &sbinfo->mpol, 1)) |
2092 | goto bad_val; |
2093 | } else { |
2094 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
2095 | this_char); |
2096 | return 1; |
2097 | } |
2098 | } |
2099 | return 0; |
2100 | |
2101 | bad_val: |
2102 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
2103 | value, this_char); |
2104 | return 1; |
2105 | |
2106 | } |
2107 | |
2108 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
2109 | { |
2110 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2111 | struct shmem_sb_info config = *sbinfo; |
2112 | unsigned long inodes; |
2113 | int error = -EINVAL; |
2114 | |
2115 | if (shmem_parse_options(data, &config, true)) |
2116 | return error; |
2117 | |
2118 | spin_lock(&sbinfo->stat_lock); |
2119 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
2120 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) |
2121 | goto out; |
2122 | if (config.max_inodes < inodes) |
2123 | goto out; |
2124 | /* |
2125 | * Those tests disallow limited->unlimited while any are in use; |
2126 | * but we must separately disallow unlimited->limited, because |
2127 | * in that case we have no record of how much is already in use. |
2128 | */ |
2129 | if (config.max_blocks && !sbinfo->max_blocks) |
2130 | goto out; |
2131 | if (config.max_inodes && !sbinfo->max_inodes) |
2132 | goto out; |
2133 | |
2134 | error = 0; |
2135 | sbinfo->max_blocks = config.max_blocks; |
2136 | sbinfo->max_inodes = config.max_inodes; |
2137 | sbinfo->free_inodes = config.max_inodes - inodes; |
2138 | |
2139 | mpol_put(sbinfo->mpol); |
2140 | sbinfo->mpol = config.mpol; /* transfers initial ref */ |
2141 | out: |
2142 | spin_unlock(&sbinfo->stat_lock); |
2143 | return error; |
2144 | } |
2145 | |
2146 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) |
2147 | { |
2148 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); |
2149 | |
2150 | if (sbinfo->max_blocks != shmem_default_max_blocks()) |
2151 | seq_printf(seq, ",size=%luk", |
2152 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
2153 | if (sbinfo->max_inodes != shmem_default_max_inodes()) |
2154 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
2155 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
2156 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); |
2157 | if (sbinfo->uid != 0) |
2158 | seq_printf(seq, ",uid=%u", sbinfo->uid); |
2159 | if (sbinfo->gid != 0) |
2160 | seq_printf(seq, ",gid=%u", sbinfo->gid); |
2161 | shmem_show_mpol(seq, sbinfo->mpol); |
2162 | return 0; |
2163 | } |
2164 | #endif /* CONFIG_TMPFS */ |
2165 | |
2166 | static void shmem_put_super(struct super_block *sb) |
2167 | { |
2168 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2169 | |
2170 | percpu_counter_destroy(&sbinfo->used_blocks); |
2171 | kfree(sbinfo); |
2172 | sb->s_fs_info = NULL; |
2173 | } |
2174 | |
2175 | int shmem_fill_super(struct super_block *sb, void *data, int silent) |
2176 | { |
2177 | struct inode *inode; |
2178 | struct dentry *root; |
2179 | struct shmem_sb_info *sbinfo; |
2180 | int err = -ENOMEM; |
2181 | |
2182 | /* Round up to L1_CACHE_BYTES to resist false sharing */ |
2183 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
2184 | L1_CACHE_BYTES), GFP_KERNEL); |
2185 | if (!sbinfo) |
2186 | return -ENOMEM; |
2187 | |
2188 | sbinfo->mode = S_IRWXUGO | S_ISVTX; |
2189 | sbinfo->uid = current_fsuid(); |
2190 | sbinfo->gid = current_fsgid(); |
2191 | sb->s_fs_info = sbinfo; |
2192 | |
2193 | #ifdef CONFIG_TMPFS |
2194 | /* |
2195 | * Per default we only allow half of the physical ram per |
2196 | * tmpfs instance, limiting inodes to one per page of lowmem; |
2197 | * but the internal instance is left unlimited. |
2198 | */ |
2199 | if (!(sb->s_flags & MS_NOUSER)) { |
2200 | sbinfo->max_blocks = shmem_default_max_blocks(); |
2201 | sbinfo->max_inodes = shmem_default_max_inodes(); |
2202 | if (shmem_parse_options(data, sbinfo, false)) { |
2203 | err = -EINVAL; |
2204 | goto failed; |
2205 | } |
2206 | } |
2207 | sb->s_export_op = &shmem_export_ops; |
2208 | #else |
2209 | sb->s_flags |= MS_NOUSER; |
2210 | #endif |
2211 | |
2212 | spin_lock_init(&sbinfo->stat_lock); |
2213 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) |
2214 | goto failed; |
2215 | sbinfo->free_inodes = sbinfo->max_inodes; |
2216 | |
2217 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
2218 | sb->s_blocksize = PAGE_CACHE_SIZE; |
2219 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
2220 | sb->s_magic = TMPFS_MAGIC; |
2221 | sb->s_op = &shmem_ops; |
2222 | sb->s_time_gran = 1; |
2223 | #ifdef CONFIG_TMPFS_XATTR |
2224 | sb->s_xattr = shmem_xattr_handlers; |
2225 | #endif |
2226 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2227 | sb->s_flags |= MS_POSIXACL; |
2228 | #endif |
2229 | |
2230 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
2231 | if (!inode) |
2232 | goto failed; |
2233 | inode->i_uid = sbinfo->uid; |
2234 | inode->i_gid = sbinfo->gid; |
2235 | root = d_alloc_root(inode); |
2236 | if (!root) |
2237 | goto failed_iput; |
2238 | sb->s_root = root; |
2239 | return 0; |
2240 | |
2241 | failed_iput: |
2242 | iput(inode); |
2243 | failed: |
2244 | shmem_put_super(sb); |
2245 | return err; |
2246 | } |
2247 | |
2248 | static struct kmem_cache *shmem_inode_cachep; |
2249 | |
2250 | static struct inode *shmem_alloc_inode(struct super_block *sb) |
2251 | { |
2252 | struct shmem_inode_info *info; |
2253 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
2254 | if (!info) |
2255 | return NULL; |
2256 | return &info->vfs_inode; |
2257 | } |
2258 | |
2259 | static void shmem_destroy_callback(struct rcu_head *head) |
2260 | { |
2261 | struct inode *inode = container_of(head, struct inode, i_rcu); |
2262 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
2263 | } |
2264 | |
2265 | static void shmem_destroy_inode(struct inode *inode) |
2266 | { |
2267 | if (S_ISREG(inode->i_mode)) |
2268 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
2269 | call_rcu(&inode->i_rcu, shmem_destroy_callback); |
2270 | } |
2271 | |
2272 | static void shmem_init_inode(void *foo) |
2273 | { |
2274 | struct shmem_inode_info *info = foo; |
2275 | inode_init_once(&info->vfs_inode); |
2276 | } |
2277 | |
2278 | static int shmem_init_inodecache(void) |
2279 | { |
2280 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
2281 | sizeof(struct shmem_inode_info), |
2282 | 0, SLAB_PANIC, shmem_init_inode); |
2283 | return 0; |
2284 | } |
2285 | |
2286 | static void shmem_destroy_inodecache(void) |
2287 | { |
2288 | kmem_cache_destroy(shmem_inode_cachep); |
2289 | } |
2290 | |
2291 | static const struct address_space_operations shmem_aops = { |
2292 | .writepage = shmem_writepage, |
2293 | .set_page_dirty = __set_page_dirty_no_writeback, |
2294 | #ifdef CONFIG_TMPFS |
2295 | .write_begin = shmem_write_begin, |
2296 | .write_end = shmem_write_end, |
2297 | #endif |
2298 | .migratepage = migrate_page, |
2299 | .error_remove_page = generic_error_remove_page, |
2300 | }; |
2301 | |
2302 | static const struct file_operations shmem_file_operations = { |
2303 | .mmap = shmem_mmap, |
2304 | #ifdef CONFIG_TMPFS |
2305 | .llseek = generic_file_llseek, |
2306 | .read = do_sync_read, |
2307 | .write = do_sync_write, |
2308 | .aio_read = shmem_file_aio_read, |
2309 | .aio_write = generic_file_aio_write, |
2310 | .fsync = noop_fsync, |
2311 | .splice_read = shmem_file_splice_read, |
2312 | .splice_write = generic_file_splice_write, |
2313 | #endif |
2314 | }; |
2315 | |
2316 | static const struct inode_operations shmem_inode_operations = { |
2317 | .setattr = shmem_setattr, |
2318 | .truncate_range = shmem_truncate_range, |
2319 | #ifdef CONFIG_TMPFS_XATTR |
2320 | .setxattr = shmem_setxattr, |
2321 | .getxattr = shmem_getxattr, |
2322 | .listxattr = shmem_listxattr, |
2323 | .removexattr = shmem_removexattr, |
2324 | #endif |
2325 | }; |
2326 | |
2327 | static const struct inode_operations shmem_dir_inode_operations = { |
2328 | #ifdef CONFIG_TMPFS |
2329 | .create = shmem_create, |
2330 | .lookup = simple_lookup, |
2331 | .link = shmem_link, |
2332 | .unlink = shmem_unlink, |
2333 | .symlink = shmem_symlink, |
2334 | .mkdir = shmem_mkdir, |
2335 | .rmdir = shmem_rmdir, |
2336 | .mknod = shmem_mknod, |
2337 | .rename = shmem_rename, |
2338 | #endif |
2339 | #ifdef CONFIG_TMPFS_XATTR |
2340 | .setxattr = shmem_setxattr, |
2341 | .getxattr = shmem_getxattr, |
2342 | .listxattr = shmem_listxattr, |
2343 | .removexattr = shmem_removexattr, |
2344 | #endif |
2345 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2346 | .setattr = shmem_setattr, |
2347 | #endif |
2348 | }; |
2349 | |
2350 | static const struct inode_operations shmem_special_inode_operations = { |
2351 | #ifdef CONFIG_TMPFS_XATTR |
2352 | .setxattr = shmem_setxattr, |
2353 | .getxattr = shmem_getxattr, |
2354 | .listxattr = shmem_listxattr, |
2355 | .removexattr = shmem_removexattr, |
2356 | #endif |
2357 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2358 | .setattr = shmem_setattr, |
2359 | #endif |
2360 | }; |
2361 | |
2362 | static const struct super_operations shmem_ops = { |
2363 | .alloc_inode = shmem_alloc_inode, |
2364 | .destroy_inode = shmem_destroy_inode, |
2365 | #ifdef CONFIG_TMPFS |
2366 | .statfs = shmem_statfs, |
2367 | .remount_fs = shmem_remount_fs, |
2368 | .show_options = shmem_show_options, |
2369 | #endif |
2370 | .evict_inode = shmem_evict_inode, |
2371 | .drop_inode = generic_delete_inode, |
2372 | .put_super = shmem_put_super, |
2373 | }; |
2374 | |
2375 | static const struct vm_operations_struct shmem_vm_ops = { |
2376 | .fault = shmem_fault, |
2377 | #ifdef CONFIG_NUMA |
2378 | .set_policy = shmem_set_policy, |
2379 | .get_policy = shmem_get_policy, |
2380 | #endif |
2381 | }; |
2382 | |
2383 | static struct dentry *shmem_mount(struct file_system_type *fs_type, |
2384 | int flags, const char *dev_name, void *data) |
2385 | { |
2386 | return mount_nodev(fs_type, flags, data, shmem_fill_super); |
2387 | } |
2388 | |
2389 | static struct file_system_type shmem_fs_type = { |
2390 | .owner = THIS_MODULE, |
2391 | .name = "tmpfs", |
2392 | .mount = shmem_mount, |
2393 | .kill_sb = kill_litter_super, |
2394 | }; |
2395 | |
2396 | int __init shmem_init(void) |
2397 | { |
2398 | int error; |
2399 | |
2400 | error = bdi_init(&shmem_backing_dev_info); |
2401 | if (error) |
2402 | goto out4; |
2403 | |
2404 | error = shmem_init_inodecache(); |
2405 | if (error) |
2406 | goto out3; |
2407 | |
2408 | error = register_filesystem(&shmem_fs_type); |
2409 | if (error) { |
2410 | printk(KERN_ERR "Could not register tmpfs\n"); |
2411 | goto out2; |
2412 | } |
2413 | |
2414 | shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER, |
2415 | shmem_fs_type.name, NULL); |
2416 | if (IS_ERR(shm_mnt)) { |
2417 | error = PTR_ERR(shm_mnt); |
2418 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
2419 | goto out1; |
2420 | } |
2421 | return 0; |
2422 | |
2423 | out1: |
2424 | unregister_filesystem(&shmem_fs_type); |
2425 | out2: |
2426 | shmem_destroy_inodecache(); |
2427 | out3: |
2428 | bdi_destroy(&shmem_backing_dev_info); |
2429 | out4: |
2430 | shm_mnt = ERR_PTR(error); |
2431 | return error; |
2432 | } |
2433 | |
2434 | #else /* !CONFIG_SHMEM */ |
2435 | |
2436 | /* |
2437 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
2438 | * |
2439 | * This is intended for small system where the benefits of the full |
2440 | * shmem code (swap-backed and resource-limited) are outweighed by |
2441 | * their complexity. On systems without swap this code should be |
2442 | * effectively equivalent, but much lighter weight. |
2443 | */ |
2444 | |
2445 | #include <linux/ramfs.h> |
2446 | |
2447 | static struct file_system_type shmem_fs_type = { |
2448 | .name = "tmpfs", |
2449 | .mount = ramfs_mount, |
2450 | .kill_sb = kill_litter_super, |
2451 | }; |
2452 | |
2453 | int __init shmem_init(void) |
2454 | { |
2455 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); |
2456 | |
2457 | shm_mnt = kern_mount(&shmem_fs_type); |
2458 | BUG_ON(IS_ERR(shm_mnt)); |
2459 | |
2460 | return 0; |
2461 | } |
2462 | |
2463 | int shmem_unuse(swp_entry_t swap, struct page *page) |
2464 | { |
2465 | return 0; |
2466 | } |
2467 | |
2468 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
2469 | { |
2470 | return 0; |
2471 | } |
2472 | |
2473 | void shmem_unlock_mapping(struct address_space *mapping) |
2474 | { |
2475 | } |
2476 | |
2477 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
2478 | { |
2479 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); |
2480 | } |
2481 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
2482 | |
2483 | #define shmem_vm_ops generic_file_vm_ops |
2484 | #define shmem_file_operations ramfs_file_operations |
2485 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) |
2486 | #define shmem_acct_size(flags, size) 0 |
2487 | #define shmem_unacct_size(flags, size) do {} while (0) |
2488 | |
2489 | #endif /* CONFIG_SHMEM */ |
2490 | |
2491 | /* common code */ |
2492 | |
2493 | /** |
2494 | * shmem_file_setup - get an unlinked file living in tmpfs |
2495 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2496 | * @size: size to be set for the file |
2497 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2498 | */ |
2499 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
2500 | { |
2501 | int error; |
2502 | struct file *file; |
2503 | struct inode *inode; |
2504 | struct path path; |
2505 | struct dentry *root; |
2506 | struct qstr this; |
2507 | |
2508 | if (IS_ERR(shm_mnt)) |
2509 | return (void *)shm_mnt; |
2510 | |
2511 | if (size < 0 || size > MAX_LFS_FILESIZE) |
2512 | return ERR_PTR(-EINVAL); |
2513 | |
2514 | if (shmem_acct_size(flags, size)) |
2515 | return ERR_PTR(-ENOMEM); |
2516 | |
2517 | error = -ENOMEM; |
2518 | this.name = name; |
2519 | this.len = strlen(name); |
2520 | this.hash = 0; /* will go */ |
2521 | root = shm_mnt->mnt_root; |
2522 | path.dentry = d_alloc(root, &this); |
2523 | if (!path.dentry) |
2524 | goto put_memory; |
2525 | path.mnt = mntget(shm_mnt); |
2526 | |
2527 | error = -ENOSPC; |
2528 | inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); |
2529 | if (!inode) |
2530 | goto put_dentry; |
2531 | |
2532 | d_instantiate(path.dentry, inode); |
2533 | inode->i_size = size; |
2534 | clear_nlink(inode); /* It is unlinked */ |
2535 | #ifndef CONFIG_MMU |
2536 | error = ramfs_nommu_expand_for_mapping(inode, size); |
2537 | if (error) |
2538 | goto put_dentry; |
2539 | #endif |
2540 | |
2541 | error = -ENFILE; |
2542 | file = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
2543 | &shmem_file_operations); |
2544 | if (!file) |
2545 | goto put_dentry; |
2546 | |
2547 | return file; |
2548 | |
2549 | put_dentry: |
2550 | path_put(&path); |
2551 | put_memory: |
2552 | shmem_unacct_size(flags, size); |
2553 | return ERR_PTR(error); |
2554 | } |
2555 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
2556 | |
2557 | /** |
2558 | * shmem_zero_setup - setup a shared anonymous mapping |
2559 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
2560 | */ |
2561 | int shmem_zero_setup(struct vm_area_struct *vma) |
2562 | { |
2563 | struct file *file; |
2564 | loff_t size = vma->vm_end - vma->vm_start; |
2565 | |
2566 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
2567 | if (IS_ERR(file)) |
2568 | return PTR_ERR(file); |
2569 | |
2570 | if (vma->vm_file) |
2571 | fput(vma->vm_file); |
2572 | vma->vm_file = file; |
2573 | vma->vm_ops = &shmem_vm_ops; |
2574 | vma->vm_flags |= VM_CAN_NONLINEAR; |
2575 | return 0; |
2576 | } |
2577 | |
2578 | /** |
2579 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. |
2580 | * @mapping: the page's address_space |
2581 | * @index: the page index |
2582 | * @gfp: the page allocator flags to use if allocating |
2583 | * |
2584 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", |
2585 | * with any new page allocations done using the specified allocation flags. |
2586 | * But read_cache_page_gfp() uses the ->readpage() method: which does not |
2587 | * suit tmpfs, since it may have pages in swapcache, and needs to find those |
2588 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. |
2589 | * |
2590 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in |
2591 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. |
2592 | */ |
2593 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, |
2594 | pgoff_t index, gfp_t gfp) |
2595 | { |
2596 | #ifdef CONFIG_SHMEM |
2597 | struct inode *inode = mapping->host; |
2598 | struct page *page; |
2599 | int error; |
2600 | |
2601 | BUG_ON(mapping->a_ops != &shmem_aops); |
2602 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); |
2603 | if (error) |
2604 | page = ERR_PTR(error); |
2605 | else |
2606 | unlock_page(page); |
2607 | return page; |
2608 | #else |
2609 | /* |
2610 | * The tiny !SHMEM case uses ramfs without swap |
2611 | */ |
2612 | return read_cache_page_gfp(mapping, index, gfp); |
2613 | #endif |
2614 | } |
2615 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |
2616 |
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