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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/falloc.h> |
57 | #include <linux/splice.h> |
58 | #include <linux/security.h> |
59 | #include <linux/swapops.h> |
60 | #include <linux/mempolicy.h> |
61 | #include <linux/namei.h> |
62 | #include <linux/ctype.h> |
63 | #include <linux/migrate.h> |
64 | #include <linux/highmem.h> |
65 | #include <linux/seq_file.h> |
66 | #include <linux/magic.h> |
67 | |
68 | #include <asm/uaccess.h> |
69 | #include <asm/pgtable.h> |
70 | |
71 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
72 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
73 | |
74 | /* Pretend that each entry is of this size in directory's i_size */ |
75 | #define BOGO_DIRENT_SIZE 20 |
76 | |
77 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ |
78 | #define SHORT_SYMLINK_LEN 128 |
79 | |
80 | /* |
81 | * shmem_fallocate and shmem_writepage communicate via inode->i_private |
82 | * (with i_mutex making sure that it has only one user at a time): |
83 | * we would prefer not to enlarge the shmem inode just for that. |
84 | */ |
85 | struct shmem_falloc { |
86 | pgoff_t start; /* start of range currently being fallocated */ |
87 | pgoff_t next; /* the next page offset to be fallocated */ |
88 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ |
89 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ |
90 | }; |
91 | |
92 | /* Flag allocation requirements to shmem_getpage */ |
93 | enum sgp_type { |
94 | SGP_READ, /* don't exceed i_size, don't allocate page */ |
95 | SGP_CACHE, /* don't exceed i_size, may allocate page */ |
96 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
97 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ |
98 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ |
99 | }; |
100 | |
101 | #ifdef CONFIG_TMPFS |
102 | static unsigned long shmem_default_max_blocks(void) |
103 | { |
104 | return totalram_pages / 2; |
105 | } |
106 | |
107 | static unsigned long shmem_default_max_inodes(void) |
108 | { |
109 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
110 | } |
111 | #endif |
112 | |
113 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); |
114 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
115 | struct shmem_inode_info *info, pgoff_t index); |
116 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
117 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); |
118 | |
119 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, |
120 | struct page **pagep, enum sgp_type sgp, int *fault_type) |
121 | { |
122 | return shmem_getpage_gfp(inode, index, pagep, sgp, |
123 | mapping_gfp_mask(inode->i_mapping), fault_type); |
124 | } |
125 | |
126 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
127 | { |
128 | return sb->s_fs_info; |
129 | } |
130 | |
131 | /* |
132 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
133 | * for shared memory and for shared anonymous (/dev/zero) mappings |
134 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
135 | * consistent with the pre-accounting of private mappings ... |
136 | */ |
137 | static inline int shmem_acct_size(unsigned long flags, loff_t size) |
138 | { |
139 | return (flags & VM_NORESERVE) ? |
140 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); |
141 | } |
142 | |
143 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
144 | { |
145 | if (!(flags & VM_NORESERVE)) |
146 | vm_unacct_memory(VM_ACCT(size)); |
147 | } |
148 | |
149 | /* |
150 | * ... whereas tmpfs objects are accounted incrementally as |
151 | * pages are allocated, in order to allow huge sparse files. |
152 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
153 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
154 | */ |
155 | static inline int shmem_acct_block(unsigned long flags) |
156 | { |
157 | return (flags & VM_NORESERVE) ? |
158 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
159 | } |
160 | |
161 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
162 | { |
163 | if (flags & VM_NORESERVE) |
164 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
165 | } |
166 | |
167 | static const struct super_operations shmem_ops; |
168 | static const struct address_space_operations shmem_aops; |
169 | static const struct file_operations shmem_file_operations; |
170 | static const struct inode_operations shmem_inode_operations; |
171 | static const struct inode_operations shmem_dir_inode_operations; |
172 | static const struct inode_operations shmem_special_inode_operations; |
173 | static const struct vm_operations_struct shmem_vm_ops; |
174 | |
175 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
176 | .ra_pages = 0, /* No readahead */ |
177 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
178 | }; |
179 | |
180 | static LIST_HEAD(shmem_swaplist); |
181 | static DEFINE_MUTEX(shmem_swaplist_mutex); |
182 | |
183 | static int shmem_reserve_inode(struct super_block *sb) |
184 | { |
185 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
186 | if (sbinfo->max_inodes) { |
187 | spin_lock(&sbinfo->stat_lock); |
188 | if (!sbinfo->free_inodes) { |
189 | spin_unlock(&sbinfo->stat_lock); |
190 | return -ENOSPC; |
191 | } |
192 | sbinfo->free_inodes--; |
193 | spin_unlock(&sbinfo->stat_lock); |
194 | } |
195 | return 0; |
196 | } |
197 | |
198 | static void shmem_free_inode(struct super_block *sb) |
199 | { |
200 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
201 | if (sbinfo->max_inodes) { |
202 | spin_lock(&sbinfo->stat_lock); |
203 | sbinfo->free_inodes++; |
204 | spin_unlock(&sbinfo->stat_lock); |
205 | } |
206 | } |
207 | |
208 | /** |
209 | * shmem_recalc_inode - recalculate the block usage of an inode |
210 | * @inode: inode to recalc |
211 | * |
212 | * We have to calculate the free blocks since the mm can drop |
213 | * undirtied hole pages behind our back. |
214 | * |
215 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
216 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
217 | * |
218 | * It has to be called with the spinlock held. |
219 | */ |
220 | static void shmem_recalc_inode(struct inode *inode) |
221 | { |
222 | struct shmem_inode_info *info = SHMEM_I(inode); |
223 | long freed; |
224 | |
225 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
226 | if (freed > 0) { |
227 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
228 | if (sbinfo->max_blocks) |
229 | percpu_counter_add(&sbinfo->used_blocks, -freed); |
230 | info->alloced -= freed; |
231 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; |
232 | shmem_unacct_blocks(info->flags, freed); |
233 | } |
234 | } |
235 | |
236 | /* |
237 | * Replace item expected in radix tree by a new item, while holding tree lock. |
238 | */ |
239 | static int shmem_radix_tree_replace(struct address_space *mapping, |
240 | pgoff_t index, void *expected, void *replacement) |
241 | { |
242 | void **pslot; |
243 | void *item = NULL; |
244 | |
245 | VM_BUG_ON(!expected); |
246 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); |
247 | if (pslot) |
248 | item = radix_tree_deref_slot_protected(pslot, |
249 | &mapping->tree_lock); |
250 | if (item != expected) |
251 | return -ENOENT; |
252 | if (replacement) |
253 | radix_tree_replace_slot(pslot, replacement); |
254 | else |
255 | radix_tree_delete(&mapping->page_tree, index); |
256 | return 0; |
257 | } |
258 | |
259 | /* |
260 | * Sometimes, before we decide whether to proceed or to fail, we must check |
261 | * that an entry was not already brought back from swap by a racing thread. |
262 | * |
263 | * Checking page is not enough: by the time a SwapCache page is locked, it |
264 | * might be reused, and again be SwapCache, using the same swap as before. |
265 | */ |
266 | static bool shmem_confirm_swap(struct address_space *mapping, |
267 | pgoff_t index, swp_entry_t swap) |
268 | { |
269 | void *item; |
270 | |
271 | rcu_read_lock(); |
272 | item = radix_tree_lookup(&mapping->page_tree, index); |
273 | rcu_read_unlock(); |
274 | return item == swp_to_radix_entry(swap); |
275 | } |
276 | |
277 | /* |
278 | * Like add_to_page_cache_locked, but error if expected item has gone. |
279 | */ |
280 | static int shmem_add_to_page_cache(struct page *page, |
281 | struct address_space *mapping, |
282 | pgoff_t index, gfp_t gfp, void *expected) |
283 | { |
284 | int error; |
285 | |
286 | VM_BUG_ON(!PageLocked(page)); |
287 | VM_BUG_ON(!PageSwapBacked(page)); |
288 | |
289 | page_cache_get(page); |
290 | page->mapping = mapping; |
291 | page->index = index; |
292 | |
293 | spin_lock_irq(&mapping->tree_lock); |
294 | if (!expected) |
295 | error = radix_tree_insert(&mapping->page_tree, index, page); |
296 | else |
297 | error = shmem_radix_tree_replace(mapping, index, expected, |
298 | page); |
299 | if (!error) { |
300 | mapping->nrpages++; |
301 | __inc_zone_page_state(page, NR_FILE_PAGES); |
302 | __inc_zone_page_state(page, NR_SHMEM); |
303 | spin_unlock_irq(&mapping->tree_lock); |
304 | } else { |
305 | page->mapping = NULL; |
306 | spin_unlock_irq(&mapping->tree_lock); |
307 | page_cache_release(page); |
308 | } |
309 | return error; |
310 | } |
311 | |
312 | /* |
313 | * Like delete_from_page_cache, but substitutes swap for page. |
314 | */ |
315 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) |
316 | { |
317 | struct address_space *mapping = page->mapping; |
318 | int error; |
319 | |
320 | spin_lock_irq(&mapping->tree_lock); |
321 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); |
322 | page->mapping = NULL; |
323 | mapping->nrpages--; |
324 | __dec_zone_page_state(page, NR_FILE_PAGES); |
325 | __dec_zone_page_state(page, NR_SHMEM); |
326 | spin_unlock_irq(&mapping->tree_lock); |
327 | page_cache_release(page); |
328 | BUG_ON(error); |
329 | } |
330 | |
331 | /* |
332 | * Like find_get_pages, but collecting swap entries as well as pages. |
333 | */ |
334 | static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, |
335 | pgoff_t start, unsigned int nr_pages, |
336 | struct page **pages, pgoff_t *indices) |
337 | { |
338 | void **slot; |
339 | unsigned int ret = 0; |
340 | struct radix_tree_iter iter; |
341 | |
342 | if (!nr_pages) |
343 | return 0; |
344 | |
345 | rcu_read_lock(); |
346 | restart: |
347 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { |
348 | struct page *page; |
349 | repeat: |
350 | page = radix_tree_deref_slot(slot); |
351 | if (unlikely(!page)) |
352 | continue; |
353 | if (radix_tree_exception(page)) { |
354 | if (radix_tree_deref_retry(page)) |
355 | goto restart; |
356 | /* |
357 | * Otherwise, we must be storing a swap entry |
358 | * here as an exceptional entry: so return it |
359 | * without attempting to raise page count. |
360 | */ |
361 | goto export; |
362 | } |
363 | if (!page_cache_get_speculative(page)) |
364 | goto repeat; |
365 | |
366 | /* Has the page moved? */ |
367 | if (unlikely(page != *slot)) { |
368 | page_cache_release(page); |
369 | goto repeat; |
370 | } |
371 | export: |
372 | indices[ret] = iter.index; |
373 | pages[ret] = page; |
374 | if (++ret == nr_pages) |
375 | break; |
376 | } |
377 | rcu_read_unlock(); |
378 | return ret; |
379 | } |
380 | |
381 | /* |
382 | * Remove swap entry from radix tree, free the swap and its page cache. |
383 | */ |
384 | static int shmem_free_swap(struct address_space *mapping, |
385 | pgoff_t index, void *radswap) |
386 | { |
387 | int error; |
388 | |
389 | spin_lock_irq(&mapping->tree_lock); |
390 | error = shmem_radix_tree_replace(mapping, index, radswap, NULL); |
391 | spin_unlock_irq(&mapping->tree_lock); |
392 | if (!error) |
393 | free_swap_and_cache(radix_to_swp_entry(radswap)); |
394 | return error; |
395 | } |
396 | |
397 | /* |
398 | * Pagevec may contain swap entries, so shuffle up pages before releasing. |
399 | */ |
400 | static void shmem_deswap_pagevec(struct pagevec *pvec) |
401 | { |
402 | int i, j; |
403 | |
404 | for (i = 0, j = 0; i < pagevec_count(pvec); i++) { |
405 | struct page *page = pvec->pages[i]; |
406 | if (!radix_tree_exceptional_entry(page)) |
407 | pvec->pages[j++] = page; |
408 | } |
409 | pvec->nr = j; |
410 | } |
411 | |
412 | /* |
413 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. |
414 | */ |
415 | void shmem_unlock_mapping(struct address_space *mapping) |
416 | { |
417 | struct pagevec pvec; |
418 | pgoff_t indices[PAGEVEC_SIZE]; |
419 | pgoff_t index = 0; |
420 | |
421 | pagevec_init(&pvec, 0); |
422 | /* |
423 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. |
424 | */ |
425 | while (!mapping_unevictable(mapping)) { |
426 | /* |
427 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it |
428 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. |
429 | */ |
430 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
431 | PAGEVEC_SIZE, pvec.pages, indices); |
432 | if (!pvec.nr) |
433 | break; |
434 | index = indices[pvec.nr - 1] + 1; |
435 | shmem_deswap_pagevec(&pvec); |
436 | check_move_unevictable_pages(pvec.pages, pvec.nr); |
437 | pagevec_release(&pvec); |
438 | cond_resched(); |
439 | } |
440 | } |
441 | |
442 | /* |
443 | * Remove range of pages and swap entries from radix tree, and free them. |
444 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. |
445 | */ |
446 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, |
447 | bool unfalloc) |
448 | { |
449 | struct address_space *mapping = inode->i_mapping; |
450 | struct shmem_inode_info *info = SHMEM_I(inode); |
451 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
452 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; |
453 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); |
454 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); |
455 | struct pagevec pvec; |
456 | pgoff_t indices[PAGEVEC_SIZE]; |
457 | long nr_swaps_freed = 0; |
458 | pgoff_t index; |
459 | int i; |
460 | |
461 | if (lend == -1) |
462 | end = -1; /* unsigned, so actually very big */ |
463 | |
464 | pagevec_init(&pvec, 0); |
465 | index = start; |
466 | while (index < end) { |
467 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
468 | min(end - index, (pgoff_t)PAGEVEC_SIZE), |
469 | pvec.pages, indices); |
470 | if (!pvec.nr) |
471 | break; |
472 | mem_cgroup_uncharge_start(); |
473 | for (i = 0; i < pagevec_count(&pvec); i++) { |
474 | struct page *page = pvec.pages[i]; |
475 | |
476 | index = indices[i]; |
477 | if (index >= end) |
478 | break; |
479 | |
480 | if (radix_tree_exceptional_entry(page)) { |
481 | if (unfalloc) |
482 | continue; |
483 | nr_swaps_freed += !shmem_free_swap(mapping, |
484 | index, page); |
485 | continue; |
486 | } |
487 | |
488 | if (!trylock_page(page)) |
489 | continue; |
490 | if (!unfalloc || !PageUptodate(page)) { |
491 | if (page->mapping == mapping) { |
492 | VM_BUG_ON(PageWriteback(page)); |
493 | truncate_inode_page(mapping, page); |
494 | } |
495 | } |
496 | unlock_page(page); |
497 | } |
498 | shmem_deswap_pagevec(&pvec); |
499 | pagevec_release(&pvec); |
500 | mem_cgroup_uncharge_end(); |
501 | cond_resched(); |
502 | index++; |
503 | } |
504 | |
505 | if (partial_start) { |
506 | struct page *page = NULL; |
507 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); |
508 | if (page) { |
509 | unsigned int top = PAGE_CACHE_SIZE; |
510 | if (start > end) { |
511 | top = partial_end; |
512 | partial_end = 0; |
513 | } |
514 | zero_user_segment(page, partial_start, top); |
515 | set_page_dirty(page); |
516 | unlock_page(page); |
517 | page_cache_release(page); |
518 | } |
519 | } |
520 | if (partial_end) { |
521 | struct page *page = NULL; |
522 | shmem_getpage(inode, end, &page, SGP_READ, NULL); |
523 | if (page) { |
524 | zero_user_segment(page, 0, partial_end); |
525 | set_page_dirty(page); |
526 | unlock_page(page); |
527 | page_cache_release(page); |
528 | } |
529 | } |
530 | if (start >= end) |
531 | return; |
532 | |
533 | index = start; |
534 | for ( ; ; ) { |
535 | cond_resched(); |
536 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
537 | min(end - index, (pgoff_t)PAGEVEC_SIZE), |
538 | pvec.pages, indices); |
539 | if (!pvec.nr) { |
540 | if (index == start || unfalloc) |
541 | break; |
542 | index = start; |
543 | continue; |
544 | } |
545 | if ((index == start || unfalloc) && indices[0] >= end) { |
546 | shmem_deswap_pagevec(&pvec); |
547 | pagevec_release(&pvec); |
548 | break; |
549 | } |
550 | mem_cgroup_uncharge_start(); |
551 | for (i = 0; i < pagevec_count(&pvec); i++) { |
552 | struct page *page = pvec.pages[i]; |
553 | |
554 | index = indices[i]; |
555 | if (index >= end) |
556 | break; |
557 | |
558 | if (radix_tree_exceptional_entry(page)) { |
559 | if (unfalloc) |
560 | continue; |
561 | nr_swaps_freed += !shmem_free_swap(mapping, |
562 | index, page); |
563 | continue; |
564 | } |
565 | |
566 | lock_page(page); |
567 | if (!unfalloc || !PageUptodate(page)) { |
568 | if (page->mapping == mapping) { |
569 | VM_BUG_ON(PageWriteback(page)); |
570 | truncate_inode_page(mapping, page); |
571 | } |
572 | } |
573 | unlock_page(page); |
574 | } |
575 | shmem_deswap_pagevec(&pvec); |
576 | pagevec_release(&pvec); |
577 | mem_cgroup_uncharge_end(); |
578 | index++; |
579 | } |
580 | |
581 | spin_lock(&info->lock); |
582 | info->swapped -= nr_swaps_freed; |
583 | shmem_recalc_inode(inode); |
584 | spin_unlock(&info->lock); |
585 | } |
586 | |
587 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
588 | { |
589 | shmem_undo_range(inode, lstart, lend, false); |
590 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
591 | } |
592 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
593 | |
594 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) |
595 | { |
596 | struct inode *inode = dentry->d_inode; |
597 | int error; |
598 | |
599 | error = inode_change_ok(inode, attr); |
600 | if (error) |
601 | return error; |
602 | |
603 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
604 | loff_t oldsize = inode->i_size; |
605 | loff_t newsize = attr->ia_size; |
606 | |
607 | if (newsize != oldsize) { |
608 | i_size_write(inode, newsize); |
609 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
610 | } |
611 | if (newsize < oldsize) { |
612 | loff_t holebegin = round_up(newsize, PAGE_SIZE); |
613 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
614 | shmem_truncate_range(inode, newsize, (loff_t)-1); |
615 | /* unmap again to remove racily COWed private pages */ |
616 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
617 | } |
618 | } |
619 | |
620 | setattr_copy(inode, attr); |
621 | #ifdef CONFIG_TMPFS_POSIX_ACL |
622 | if (attr->ia_valid & ATTR_MODE) |
623 | error = generic_acl_chmod(inode); |
624 | #endif |
625 | return error; |
626 | } |
627 | |
628 | static void shmem_evict_inode(struct inode *inode) |
629 | { |
630 | struct shmem_inode_info *info = SHMEM_I(inode); |
631 | |
632 | if (inode->i_mapping->a_ops == &shmem_aops) { |
633 | shmem_unacct_size(info->flags, inode->i_size); |
634 | inode->i_size = 0; |
635 | shmem_truncate_range(inode, 0, (loff_t)-1); |
636 | if (!list_empty(&info->swaplist)) { |
637 | mutex_lock(&shmem_swaplist_mutex); |
638 | list_del_init(&info->swaplist); |
639 | mutex_unlock(&shmem_swaplist_mutex); |
640 | } |
641 | } else |
642 | kfree(info->symlink); |
643 | |
644 | simple_xattrs_free(&info->xattrs); |
645 | WARN_ON(inode->i_blocks); |
646 | shmem_free_inode(inode->i_sb); |
647 | clear_inode(inode); |
648 | } |
649 | |
650 | /* |
651 | * If swap found in inode, free it and move page from swapcache to filecache. |
652 | */ |
653 | static int shmem_unuse_inode(struct shmem_inode_info *info, |
654 | swp_entry_t swap, struct page **pagep) |
655 | { |
656 | struct address_space *mapping = info->vfs_inode.i_mapping; |
657 | void *radswap; |
658 | pgoff_t index; |
659 | gfp_t gfp; |
660 | int error = 0; |
661 | |
662 | radswap = swp_to_radix_entry(swap); |
663 | index = radix_tree_locate_item(&mapping->page_tree, radswap); |
664 | if (index == -1) |
665 | return 0; |
666 | |
667 | /* |
668 | * Move _head_ to start search for next from here. |
669 | * But be careful: shmem_evict_inode checks list_empty without taking |
670 | * mutex, and there's an instant in list_move_tail when info->swaplist |
671 | * would appear empty, if it were the only one on shmem_swaplist. |
672 | */ |
673 | if (shmem_swaplist.next != &info->swaplist) |
674 | list_move_tail(&shmem_swaplist, &info->swaplist); |
675 | |
676 | gfp = mapping_gfp_mask(mapping); |
677 | if (shmem_should_replace_page(*pagep, gfp)) { |
678 | mutex_unlock(&shmem_swaplist_mutex); |
679 | error = shmem_replace_page(pagep, gfp, info, index); |
680 | mutex_lock(&shmem_swaplist_mutex); |
681 | /* |
682 | * We needed to drop mutex to make that restrictive page |
683 | * allocation, but the inode might have been freed while we |
684 | * dropped it: although a racing shmem_evict_inode() cannot |
685 | * complete without emptying the radix_tree, our page lock |
686 | * on this swapcache page is not enough to prevent that - |
687 | * free_swap_and_cache() of our swap entry will only |
688 | * trylock_page(), removing swap from radix_tree whatever. |
689 | * |
690 | * We must not proceed to shmem_add_to_page_cache() if the |
691 | * inode has been freed, but of course we cannot rely on |
692 | * inode or mapping or info to check that. However, we can |
693 | * safely check if our swap entry is still in use (and here |
694 | * it can't have got reused for another page): if it's still |
695 | * in use, then the inode cannot have been freed yet, and we |
696 | * can safely proceed (if it's no longer in use, that tells |
697 | * nothing about the inode, but we don't need to unuse swap). |
698 | */ |
699 | if (!page_swapcount(*pagep)) |
700 | error = -ENOENT; |
701 | } |
702 | |
703 | /* |
704 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, |
705 | * but also to hold up shmem_evict_inode(): so inode cannot be freed |
706 | * beneath us (pagelock doesn't help until the page is in pagecache). |
707 | */ |
708 | if (!error) |
709 | error = shmem_add_to_page_cache(*pagep, mapping, index, |
710 | GFP_NOWAIT, radswap); |
711 | if (error != -ENOMEM) { |
712 | /* |
713 | * Truncation and eviction use free_swap_and_cache(), which |
714 | * only does trylock page: if we raced, best clean up here. |
715 | */ |
716 | delete_from_swap_cache(*pagep); |
717 | set_page_dirty(*pagep); |
718 | if (!error) { |
719 | spin_lock(&info->lock); |
720 | info->swapped--; |
721 | spin_unlock(&info->lock); |
722 | swap_free(swap); |
723 | } |
724 | error = 1; /* not an error, but entry was found */ |
725 | } |
726 | return error; |
727 | } |
728 | |
729 | /* |
730 | * Search through swapped inodes to find and replace swap by page. |
731 | */ |
732 | int shmem_unuse(swp_entry_t swap, struct page *page) |
733 | { |
734 | struct list_head *this, *next; |
735 | struct shmem_inode_info *info; |
736 | int found = 0; |
737 | int error = 0; |
738 | |
739 | /* |
740 | * There's a faint possibility that swap page was replaced before |
741 | * caller locked it: caller will come back later with the right page. |
742 | */ |
743 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) |
744 | goto out; |
745 | |
746 | /* |
747 | * Charge page using GFP_KERNEL while we can wait, before taking |
748 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). |
749 | * Charged back to the user (not to caller) when swap account is used. |
750 | */ |
751 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); |
752 | if (error) |
753 | goto out; |
754 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ |
755 | |
756 | mutex_lock(&shmem_swaplist_mutex); |
757 | list_for_each_safe(this, next, &shmem_swaplist) { |
758 | info = list_entry(this, struct shmem_inode_info, swaplist); |
759 | if (info->swapped) |
760 | found = shmem_unuse_inode(info, swap, &page); |
761 | else |
762 | list_del_init(&info->swaplist); |
763 | cond_resched(); |
764 | if (found) |
765 | break; |
766 | } |
767 | mutex_unlock(&shmem_swaplist_mutex); |
768 | |
769 | if (found < 0) |
770 | error = found; |
771 | out: |
772 | unlock_page(page); |
773 | page_cache_release(page); |
774 | return error; |
775 | } |
776 | |
777 | /* |
778 | * Move the page from the page cache to the swap cache. |
779 | */ |
780 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
781 | { |
782 | struct shmem_inode_info *info; |
783 | struct address_space *mapping; |
784 | struct inode *inode; |
785 | swp_entry_t swap; |
786 | pgoff_t index; |
787 | |
788 | BUG_ON(!PageLocked(page)); |
789 | mapping = page->mapping; |
790 | index = page->index; |
791 | inode = mapping->host; |
792 | info = SHMEM_I(inode); |
793 | if (info->flags & VM_LOCKED) |
794 | goto redirty; |
795 | if (!total_swap_pages) |
796 | goto redirty; |
797 | |
798 | /* |
799 | * shmem_backing_dev_info's capabilities prevent regular writeback or |
800 | * sync from ever calling shmem_writepage; but a stacking filesystem |
801 | * might use ->writepage of its underlying filesystem, in which case |
802 | * tmpfs should write out to swap only in response to memory pressure, |
803 | * and not for the writeback threads or sync. |
804 | */ |
805 | if (!wbc->for_reclaim) { |
806 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ |
807 | goto redirty; |
808 | } |
809 | |
810 | /* |
811 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC |
812 | * value into swapfile.c, the only way we can correctly account for a |
813 | * fallocated page arriving here is now to initialize it and write it. |
814 | * |
815 | * That's okay for a page already fallocated earlier, but if we have |
816 | * not yet completed the fallocation, then (a) we want to keep track |
817 | * of this page in case we have to undo it, and (b) it may not be a |
818 | * good idea to continue anyway, once we're pushing into swap. So |
819 | * reactivate the page, and let shmem_fallocate() quit when too many. |
820 | */ |
821 | if (!PageUptodate(page)) { |
822 | if (inode->i_private) { |
823 | struct shmem_falloc *shmem_falloc; |
824 | spin_lock(&inode->i_lock); |
825 | shmem_falloc = inode->i_private; |
826 | if (shmem_falloc && |
827 | index >= shmem_falloc->start && |
828 | index < shmem_falloc->next) |
829 | shmem_falloc->nr_unswapped++; |
830 | else |
831 | shmem_falloc = NULL; |
832 | spin_unlock(&inode->i_lock); |
833 | if (shmem_falloc) |
834 | goto redirty; |
835 | } |
836 | clear_highpage(page); |
837 | flush_dcache_page(page); |
838 | SetPageUptodate(page); |
839 | } |
840 | |
841 | swap = get_swap_page(); |
842 | if (!swap.val) |
843 | goto redirty; |
844 | |
845 | /* |
846 | * Add inode to shmem_unuse()'s list of swapped-out inodes, |
847 | * if it's not already there. Do it now before the page is |
848 | * moved to swap cache, when its pagelock no longer protects |
849 | * the inode from eviction. But don't unlock the mutex until |
850 | * we've incremented swapped, because shmem_unuse_inode() will |
851 | * prune a !swapped inode from the swaplist under this mutex. |
852 | */ |
853 | mutex_lock(&shmem_swaplist_mutex); |
854 | if (list_empty(&info->swaplist)) |
855 | list_add_tail(&info->swaplist, &shmem_swaplist); |
856 | |
857 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
858 | swap_shmem_alloc(swap); |
859 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); |
860 | |
861 | spin_lock(&info->lock); |
862 | info->swapped++; |
863 | shmem_recalc_inode(inode); |
864 | spin_unlock(&info->lock); |
865 | |
866 | mutex_unlock(&shmem_swaplist_mutex); |
867 | BUG_ON(page_mapped(page)); |
868 | swap_writepage(page, wbc); |
869 | return 0; |
870 | } |
871 | |
872 | mutex_unlock(&shmem_swaplist_mutex); |
873 | swapcache_free(swap, NULL); |
874 | redirty: |
875 | set_page_dirty(page); |
876 | if (wbc->for_reclaim) |
877 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
878 | unlock_page(page); |
879 | return 0; |
880 | } |
881 | |
882 | #ifdef CONFIG_NUMA |
883 | #ifdef CONFIG_TMPFS |
884 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
885 | { |
886 | char buffer[64]; |
887 | |
888 | if (!mpol || mpol->mode == MPOL_DEFAULT) |
889 | return; /* show nothing */ |
890 | |
891 | mpol_to_str(buffer, sizeof(buffer), mpol); |
892 | |
893 | seq_printf(seq, ",mpol=%s", buffer); |
894 | } |
895 | |
896 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
897 | { |
898 | struct mempolicy *mpol = NULL; |
899 | if (sbinfo->mpol) { |
900 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
901 | mpol = sbinfo->mpol; |
902 | mpol_get(mpol); |
903 | spin_unlock(&sbinfo->stat_lock); |
904 | } |
905 | return mpol; |
906 | } |
907 | #endif /* CONFIG_TMPFS */ |
908 | |
909 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
910 | struct shmem_inode_info *info, pgoff_t index) |
911 | { |
912 | struct vm_area_struct pvma; |
913 | struct page *page; |
914 | |
915 | /* Create a pseudo vma that just contains the policy */ |
916 | pvma.vm_start = 0; |
917 | /* Bias interleave by inode number to distribute better across nodes */ |
918 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
919 | pvma.vm_ops = NULL; |
920 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
921 | |
922 | page = swapin_readahead(swap, gfp, &pvma, 0); |
923 | |
924 | /* Drop reference taken by mpol_shared_policy_lookup() */ |
925 | mpol_cond_put(pvma.vm_policy); |
926 | |
927 | return page; |
928 | } |
929 | |
930 | static struct page *shmem_alloc_page(gfp_t gfp, |
931 | struct shmem_inode_info *info, pgoff_t index) |
932 | { |
933 | struct vm_area_struct pvma; |
934 | struct page *page; |
935 | |
936 | /* Create a pseudo vma that just contains the policy */ |
937 | pvma.vm_start = 0; |
938 | /* Bias interleave by inode number to distribute better across nodes */ |
939 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
940 | pvma.vm_ops = NULL; |
941 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
942 | |
943 | page = alloc_page_vma(gfp, &pvma, 0); |
944 | |
945 | /* Drop reference taken by mpol_shared_policy_lookup() */ |
946 | mpol_cond_put(pvma.vm_policy); |
947 | |
948 | return page; |
949 | } |
950 | #else /* !CONFIG_NUMA */ |
951 | #ifdef CONFIG_TMPFS |
952 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
953 | { |
954 | } |
955 | #endif /* CONFIG_TMPFS */ |
956 | |
957 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
958 | struct shmem_inode_info *info, pgoff_t index) |
959 | { |
960 | return swapin_readahead(swap, gfp, NULL, 0); |
961 | } |
962 | |
963 | static inline struct page *shmem_alloc_page(gfp_t gfp, |
964 | struct shmem_inode_info *info, pgoff_t index) |
965 | { |
966 | return alloc_page(gfp); |
967 | } |
968 | #endif /* CONFIG_NUMA */ |
969 | |
970 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
971 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
972 | { |
973 | return NULL; |
974 | } |
975 | #endif |
976 | |
977 | /* |
978 | * When a page is moved from swapcache to shmem filecache (either by the |
979 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of |
980 | * shmem_unuse_inode()), it may have been read in earlier from swap, in |
981 | * ignorance of the mapping it belongs to. If that mapping has special |
982 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), |
983 | * we may need to copy to a suitable page before moving to filecache. |
984 | * |
985 | * In a future release, this may well be extended to respect cpuset and |
986 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); |
987 | * but for now it is a simple matter of zone. |
988 | */ |
989 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) |
990 | { |
991 | return page_zonenum(page) > gfp_zone(gfp); |
992 | } |
993 | |
994 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
995 | struct shmem_inode_info *info, pgoff_t index) |
996 | { |
997 | struct page *oldpage, *newpage; |
998 | struct address_space *swap_mapping; |
999 | pgoff_t swap_index; |
1000 | int error; |
1001 | |
1002 | oldpage = *pagep; |
1003 | swap_index = page_private(oldpage); |
1004 | swap_mapping = page_mapping(oldpage); |
1005 | |
1006 | /* |
1007 | * We have arrived here because our zones are constrained, so don't |
1008 | * limit chance of success by further cpuset and node constraints. |
1009 | */ |
1010 | gfp &= ~GFP_CONSTRAINT_MASK; |
1011 | newpage = shmem_alloc_page(gfp, info, index); |
1012 | if (!newpage) |
1013 | return -ENOMEM; |
1014 | |
1015 | page_cache_get(newpage); |
1016 | copy_highpage(newpage, oldpage); |
1017 | flush_dcache_page(newpage); |
1018 | |
1019 | __set_page_locked(newpage); |
1020 | SetPageUptodate(newpage); |
1021 | SetPageSwapBacked(newpage); |
1022 | set_page_private(newpage, swap_index); |
1023 | SetPageSwapCache(newpage); |
1024 | |
1025 | /* |
1026 | * Our caller will very soon move newpage out of swapcache, but it's |
1027 | * a nice clean interface for us to replace oldpage by newpage there. |
1028 | */ |
1029 | spin_lock_irq(&swap_mapping->tree_lock); |
1030 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, |
1031 | newpage); |
1032 | if (!error) { |
1033 | __inc_zone_page_state(newpage, NR_FILE_PAGES); |
1034 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); |
1035 | } |
1036 | spin_unlock_irq(&swap_mapping->tree_lock); |
1037 | |
1038 | if (unlikely(error)) { |
1039 | /* |
1040 | * Is this possible? I think not, now that our callers check |
1041 | * both PageSwapCache and page_private after getting page lock; |
1042 | * but be defensive. Reverse old to newpage for clear and free. |
1043 | */ |
1044 | oldpage = newpage; |
1045 | } else { |
1046 | mem_cgroup_replace_page_cache(oldpage, newpage); |
1047 | lru_cache_add_anon(newpage); |
1048 | *pagep = newpage; |
1049 | } |
1050 | |
1051 | ClearPageSwapCache(oldpage); |
1052 | set_page_private(oldpage, 0); |
1053 | |
1054 | unlock_page(oldpage); |
1055 | page_cache_release(oldpage); |
1056 | page_cache_release(oldpage); |
1057 | return error; |
1058 | } |
1059 | |
1060 | /* |
1061 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate |
1062 | * |
1063 | * If we allocate a new one we do not mark it dirty. That's up to the |
1064 | * vm. If we swap it in we mark it dirty since we also free the swap |
1065 | * entry since a page cannot live in both the swap and page cache |
1066 | */ |
1067 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
1068 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) |
1069 | { |
1070 | struct address_space *mapping = inode->i_mapping; |
1071 | struct shmem_inode_info *info; |
1072 | struct shmem_sb_info *sbinfo; |
1073 | struct page *page; |
1074 | swp_entry_t swap; |
1075 | int error; |
1076 | int once = 0; |
1077 | int alloced = 0; |
1078 | |
1079 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) |
1080 | return -EFBIG; |
1081 | repeat: |
1082 | swap.val = 0; |
1083 | page = find_lock_page(mapping, index); |
1084 | if (radix_tree_exceptional_entry(page)) { |
1085 | swap = radix_to_swp_entry(page); |
1086 | page = NULL; |
1087 | } |
1088 | |
1089 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
1090 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
1091 | error = -EINVAL; |
1092 | goto failed; |
1093 | } |
1094 | |
1095 | /* fallocated page? */ |
1096 | if (page && !PageUptodate(page)) { |
1097 | if (sgp != SGP_READ) |
1098 | goto clear; |
1099 | unlock_page(page); |
1100 | page_cache_release(page); |
1101 | page = NULL; |
1102 | } |
1103 | if (page || (sgp == SGP_READ && !swap.val)) { |
1104 | *pagep = page; |
1105 | return 0; |
1106 | } |
1107 | |
1108 | /* |
1109 | * Fast cache lookup did not find it: |
1110 | * bring it back from swap or allocate. |
1111 | */ |
1112 | info = SHMEM_I(inode); |
1113 | sbinfo = SHMEM_SB(inode->i_sb); |
1114 | |
1115 | if (swap.val) { |
1116 | /* Look it up and read it in.. */ |
1117 | page = lookup_swap_cache(swap); |
1118 | if (!page) { |
1119 | /* here we actually do the io */ |
1120 | if (fault_type) |
1121 | *fault_type |= VM_FAULT_MAJOR; |
1122 | page = shmem_swapin(swap, gfp, info, index); |
1123 | if (!page) { |
1124 | error = -ENOMEM; |
1125 | goto failed; |
1126 | } |
1127 | } |
1128 | |
1129 | /* We have to do this with page locked to prevent races */ |
1130 | lock_page(page); |
1131 | if (!PageSwapCache(page) || page_private(page) != swap.val || |
1132 | !shmem_confirm_swap(mapping, index, swap)) { |
1133 | error = -EEXIST; /* try again */ |
1134 | goto unlock; |
1135 | } |
1136 | if (!PageUptodate(page)) { |
1137 | error = -EIO; |
1138 | goto failed; |
1139 | } |
1140 | wait_on_page_writeback(page); |
1141 | |
1142 | if (shmem_should_replace_page(page, gfp)) { |
1143 | error = shmem_replace_page(&page, gfp, info, index); |
1144 | if (error) |
1145 | goto failed; |
1146 | } |
1147 | |
1148 | error = mem_cgroup_cache_charge(page, current->mm, |
1149 | gfp & GFP_RECLAIM_MASK); |
1150 | if (!error) { |
1151 | error = shmem_add_to_page_cache(page, mapping, index, |
1152 | gfp, swp_to_radix_entry(swap)); |
1153 | /* |
1154 | * We already confirmed swap under page lock, and make |
1155 | * no memory allocation here, so usually no possibility |
1156 | * of error; but free_swap_and_cache() only trylocks a |
1157 | * page, so it is just possible that the entry has been |
1158 | * truncated or holepunched since swap was confirmed. |
1159 | * shmem_undo_range() will have done some of the |
1160 | * unaccounting, now delete_from_swap_cache() will do |
1161 | * the rest (including mem_cgroup_uncharge_swapcache). |
1162 | * Reset swap.val? No, leave it so "failed" goes back to |
1163 | * "repeat": reading a hole and writing should succeed. |
1164 | */ |
1165 | if (error) |
1166 | delete_from_swap_cache(page); |
1167 | } |
1168 | if (error) |
1169 | goto failed; |
1170 | |
1171 | spin_lock(&info->lock); |
1172 | info->swapped--; |
1173 | shmem_recalc_inode(inode); |
1174 | spin_unlock(&info->lock); |
1175 | |
1176 | delete_from_swap_cache(page); |
1177 | set_page_dirty(page); |
1178 | swap_free(swap); |
1179 | |
1180 | } else { |
1181 | if (shmem_acct_block(info->flags)) { |
1182 | error = -ENOSPC; |
1183 | goto failed; |
1184 | } |
1185 | if (sbinfo->max_blocks) { |
1186 | if (percpu_counter_compare(&sbinfo->used_blocks, |
1187 | sbinfo->max_blocks) >= 0) { |
1188 | error = -ENOSPC; |
1189 | goto unacct; |
1190 | } |
1191 | percpu_counter_inc(&sbinfo->used_blocks); |
1192 | } |
1193 | |
1194 | page = shmem_alloc_page(gfp, info, index); |
1195 | if (!page) { |
1196 | error = -ENOMEM; |
1197 | goto decused; |
1198 | } |
1199 | |
1200 | SetPageSwapBacked(page); |
1201 | __set_page_locked(page); |
1202 | error = mem_cgroup_cache_charge(page, current->mm, |
1203 | gfp & GFP_RECLAIM_MASK); |
1204 | if (error) |
1205 | goto decused; |
1206 | error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); |
1207 | if (!error) { |
1208 | error = shmem_add_to_page_cache(page, mapping, index, |
1209 | gfp, NULL); |
1210 | radix_tree_preload_end(); |
1211 | } |
1212 | if (error) { |
1213 | mem_cgroup_uncharge_cache_page(page); |
1214 | goto decused; |
1215 | } |
1216 | lru_cache_add_anon(page); |
1217 | |
1218 | spin_lock(&info->lock); |
1219 | info->alloced++; |
1220 | inode->i_blocks += BLOCKS_PER_PAGE; |
1221 | shmem_recalc_inode(inode); |
1222 | spin_unlock(&info->lock); |
1223 | alloced = true; |
1224 | |
1225 | /* |
1226 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. |
1227 | */ |
1228 | if (sgp == SGP_FALLOC) |
1229 | sgp = SGP_WRITE; |
1230 | clear: |
1231 | /* |
1232 | * Let SGP_WRITE caller clear ends if write does not fill page; |
1233 | * but SGP_FALLOC on a page fallocated earlier must initialize |
1234 | * it now, lest undo on failure cancel our earlier guarantee. |
1235 | */ |
1236 | if (sgp != SGP_WRITE) { |
1237 | clear_highpage(page); |
1238 | flush_dcache_page(page); |
1239 | SetPageUptodate(page); |
1240 | } |
1241 | if (sgp == SGP_DIRTY) |
1242 | set_page_dirty(page); |
1243 | } |
1244 | |
1245 | /* Perhaps the file has been truncated since we checked */ |
1246 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
1247 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
1248 | error = -EINVAL; |
1249 | if (alloced) |
1250 | goto trunc; |
1251 | else |
1252 | goto failed; |
1253 | } |
1254 | *pagep = page; |
1255 | return 0; |
1256 | |
1257 | /* |
1258 | * Error recovery. |
1259 | */ |
1260 | trunc: |
1261 | info = SHMEM_I(inode); |
1262 | ClearPageDirty(page); |
1263 | delete_from_page_cache(page); |
1264 | spin_lock(&info->lock); |
1265 | info->alloced--; |
1266 | inode->i_blocks -= BLOCKS_PER_PAGE; |
1267 | spin_unlock(&info->lock); |
1268 | decused: |
1269 | sbinfo = SHMEM_SB(inode->i_sb); |
1270 | if (sbinfo->max_blocks) |
1271 | percpu_counter_add(&sbinfo->used_blocks, -1); |
1272 | unacct: |
1273 | shmem_unacct_blocks(info->flags, 1); |
1274 | failed: |
1275 | if (swap.val && error != -EINVAL && |
1276 | !shmem_confirm_swap(mapping, index, swap)) |
1277 | error = -EEXIST; |
1278 | unlock: |
1279 | if (page) { |
1280 | unlock_page(page); |
1281 | page_cache_release(page); |
1282 | } |
1283 | if (error == -ENOSPC && !once++) { |
1284 | info = SHMEM_I(inode); |
1285 | spin_lock(&info->lock); |
1286 | shmem_recalc_inode(inode); |
1287 | spin_unlock(&info->lock); |
1288 | goto repeat; |
1289 | } |
1290 | if (error == -EEXIST) /* from above or from radix_tree_insert */ |
1291 | goto repeat; |
1292 | return error; |
1293 | } |
1294 | |
1295 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1296 | { |
1297 | struct inode *inode = file_inode(vma->vm_file); |
1298 | int error; |
1299 | int ret = VM_FAULT_LOCKED; |
1300 | |
1301 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
1302 | if (error) |
1303 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
1304 | |
1305 | if (ret & VM_FAULT_MAJOR) { |
1306 | count_vm_event(PGMAJFAULT); |
1307 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
1308 | } |
1309 | return ret; |
1310 | } |
1311 | |
1312 | #ifdef CONFIG_NUMA |
1313 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) |
1314 | { |
1315 | struct inode *inode = file_inode(vma->vm_file); |
1316 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); |
1317 | } |
1318 | |
1319 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
1320 | unsigned long addr) |
1321 | { |
1322 | struct inode *inode = file_inode(vma->vm_file); |
1323 | pgoff_t index; |
1324 | |
1325 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
1326 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); |
1327 | } |
1328 | #endif |
1329 | |
1330 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
1331 | { |
1332 | struct inode *inode = file_inode(file); |
1333 | struct shmem_inode_info *info = SHMEM_I(inode); |
1334 | int retval = -ENOMEM; |
1335 | |
1336 | spin_lock(&info->lock); |
1337 | if (lock && !(info->flags & VM_LOCKED)) { |
1338 | if (!user_shm_lock(inode->i_size, user)) |
1339 | goto out_nomem; |
1340 | info->flags |= VM_LOCKED; |
1341 | mapping_set_unevictable(file->f_mapping); |
1342 | } |
1343 | if (!lock && (info->flags & VM_LOCKED) && user) { |
1344 | user_shm_unlock(inode->i_size, user); |
1345 | info->flags &= ~VM_LOCKED; |
1346 | mapping_clear_unevictable(file->f_mapping); |
1347 | } |
1348 | retval = 0; |
1349 | |
1350 | out_nomem: |
1351 | spin_unlock(&info->lock); |
1352 | return retval; |
1353 | } |
1354 | |
1355 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
1356 | { |
1357 | file_accessed(file); |
1358 | vma->vm_ops = &shmem_vm_ops; |
1359 | return 0; |
1360 | } |
1361 | |
1362 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
1363 | umode_t mode, dev_t dev, unsigned long flags) |
1364 | { |
1365 | struct inode *inode; |
1366 | struct shmem_inode_info *info; |
1367 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
1368 | |
1369 | if (shmem_reserve_inode(sb)) |
1370 | return NULL; |
1371 | |
1372 | inode = new_inode(sb); |
1373 | if (inode) { |
1374 | inode->i_ino = get_next_ino(); |
1375 | inode_init_owner(inode, dir, mode); |
1376 | inode->i_blocks = 0; |
1377 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
1378 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1379 | inode->i_generation = get_seconds(); |
1380 | info = SHMEM_I(inode); |
1381 | memset(info, 0, (char *)inode - (char *)info); |
1382 | spin_lock_init(&info->lock); |
1383 | info->flags = flags & VM_NORESERVE; |
1384 | INIT_LIST_HEAD(&info->swaplist); |
1385 | simple_xattrs_init(&info->xattrs); |
1386 | cache_no_acl(inode); |
1387 | |
1388 | switch (mode & S_IFMT) { |
1389 | default: |
1390 | inode->i_op = &shmem_special_inode_operations; |
1391 | init_special_inode(inode, mode, dev); |
1392 | break; |
1393 | case S_IFREG: |
1394 | inode->i_mapping->a_ops = &shmem_aops; |
1395 | inode->i_op = &shmem_inode_operations; |
1396 | inode->i_fop = &shmem_file_operations; |
1397 | mpol_shared_policy_init(&info->policy, |
1398 | shmem_get_sbmpol(sbinfo)); |
1399 | break; |
1400 | case S_IFDIR: |
1401 | inc_nlink(inode); |
1402 | /* Some things misbehave if size == 0 on a directory */ |
1403 | inode->i_size = 2 * BOGO_DIRENT_SIZE; |
1404 | inode->i_op = &shmem_dir_inode_operations; |
1405 | inode->i_fop = &simple_dir_operations; |
1406 | break; |
1407 | case S_IFLNK: |
1408 | /* |
1409 | * Must not load anything in the rbtree, |
1410 | * mpol_free_shared_policy will not be called. |
1411 | */ |
1412 | mpol_shared_policy_init(&info->policy, NULL); |
1413 | break; |
1414 | } |
1415 | } else |
1416 | shmem_free_inode(sb); |
1417 | return inode; |
1418 | } |
1419 | |
1420 | #ifdef CONFIG_TMPFS |
1421 | static const struct inode_operations shmem_symlink_inode_operations; |
1422 | static const struct inode_operations shmem_short_symlink_operations; |
1423 | |
1424 | #ifdef CONFIG_TMPFS_XATTR |
1425 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); |
1426 | #else |
1427 | #define shmem_initxattrs NULL |
1428 | #endif |
1429 | |
1430 | static int |
1431 | shmem_write_begin(struct file *file, struct address_space *mapping, |
1432 | loff_t pos, unsigned len, unsigned flags, |
1433 | struct page **pagep, void **fsdata) |
1434 | { |
1435 | struct inode *inode = mapping->host; |
1436 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
1437 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
1438 | } |
1439 | |
1440 | static int |
1441 | shmem_write_end(struct file *file, struct address_space *mapping, |
1442 | loff_t pos, unsigned len, unsigned copied, |
1443 | struct page *page, void *fsdata) |
1444 | { |
1445 | struct inode *inode = mapping->host; |
1446 | |
1447 | if (pos + copied > inode->i_size) |
1448 | i_size_write(inode, pos + copied); |
1449 | |
1450 | if (!PageUptodate(page)) { |
1451 | if (copied < PAGE_CACHE_SIZE) { |
1452 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
1453 | zero_user_segments(page, 0, from, |
1454 | from + copied, PAGE_CACHE_SIZE); |
1455 | } |
1456 | SetPageUptodate(page); |
1457 | } |
1458 | set_page_dirty(page); |
1459 | unlock_page(page); |
1460 | page_cache_release(page); |
1461 | |
1462 | return copied; |
1463 | } |
1464 | |
1465 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) |
1466 | { |
1467 | struct inode *inode = file_inode(filp); |
1468 | struct address_space *mapping = inode->i_mapping; |
1469 | pgoff_t index; |
1470 | unsigned long offset; |
1471 | enum sgp_type sgp = SGP_READ; |
1472 | |
1473 | /* |
1474 | * Might this read be for a stacking filesystem? Then when reading |
1475 | * holes of a sparse file, we actually need to allocate those pages, |
1476 | * and even mark them dirty, so it cannot exceed the max_blocks limit. |
1477 | */ |
1478 | if (segment_eq(get_fs(), KERNEL_DS)) |
1479 | sgp = SGP_DIRTY; |
1480 | |
1481 | index = *ppos >> PAGE_CACHE_SHIFT; |
1482 | offset = *ppos & ~PAGE_CACHE_MASK; |
1483 | |
1484 | for (;;) { |
1485 | struct page *page = NULL; |
1486 | pgoff_t end_index; |
1487 | unsigned long nr, ret; |
1488 | loff_t i_size = i_size_read(inode); |
1489 | |
1490 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1491 | if (index > end_index) |
1492 | break; |
1493 | if (index == end_index) { |
1494 | nr = i_size & ~PAGE_CACHE_MASK; |
1495 | if (nr <= offset) |
1496 | break; |
1497 | } |
1498 | |
1499 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); |
1500 | if (desc->error) { |
1501 | if (desc->error == -EINVAL) |
1502 | desc->error = 0; |
1503 | break; |
1504 | } |
1505 | if (page) |
1506 | unlock_page(page); |
1507 | |
1508 | /* |
1509 | * We must evaluate after, since reads (unlike writes) |
1510 | * are called without i_mutex protection against truncate |
1511 | */ |
1512 | nr = PAGE_CACHE_SIZE; |
1513 | i_size = i_size_read(inode); |
1514 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1515 | if (index == end_index) { |
1516 | nr = i_size & ~PAGE_CACHE_MASK; |
1517 | if (nr <= offset) { |
1518 | if (page) |
1519 | page_cache_release(page); |
1520 | break; |
1521 | } |
1522 | } |
1523 | nr -= offset; |
1524 | |
1525 | if (page) { |
1526 | /* |
1527 | * If users can be writing to this page using arbitrary |
1528 | * virtual addresses, take care about potential aliasing |
1529 | * before reading the page on the kernel side. |
1530 | */ |
1531 | if (mapping_writably_mapped(mapping)) |
1532 | flush_dcache_page(page); |
1533 | /* |
1534 | * Mark the page accessed if we read the beginning. |
1535 | */ |
1536 | if (!offset) |
1537 | mark_page_accessed(page); |
1538 | } else { |
1539 | page = ZERO_PAGE(0); |
1540 | page_cache_get(page); |
1541 | } |
1542 | |
1543 | /* |
1544 | * Ok, we have the page, and it's up-to-date, so |
1545 | * now we can copy it to user space... |
1546 | * |
1547 | * The actor routine returns how many bytes were actually used.. |
1548 | * NOTE! This may not be the same as how much of a user buffer |
1549 | * we filled up (we may be padding etc), so we can only update |
1550 | * "pos" here (the actor routine has to update the user buffer |
1551 | * pointers and the remaining count). |
1552 | */ |
1553 | ret = actor(desc, page, offset, nr); |
1554 | offset += ret; |
1555 | index += offset >> PAGE_CACHE_SHIFT; |
1556 | offset &= ~PAGE_CACHE_MASK; |
1557 | |
1558 | page_cache_release(page); |
1559 | if (ret != nr || !desc->count) |
1560 | break; |
1561 | |
1562 | cond_resched(); |
1563 | } |
1564 | |
1565 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
1566 | file_accessed(filp); |
1567 | } |
1568 | |
1569 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, |
1570 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
1571 | { |
1572 | struct file *filp = iocb->ki_filp; |
1573 | ssize_t retval; |
1574 | unsigned long seg; |
1575 | size_t count; |
1576 | loff_t *ppos = &iocb->ki_pos; |
1577 | |
1578 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1579 | if (retval) |
1580 | return retval; |
1581 | |
1582 | for (seg = 0; seg < nr_segs; seg++) { |
1583 | read_descriptor_t desc; |
1584 | |
1585 | desc.written = 0; |
1586 | desc.arg.buf = iov[seg].iov_base; |
1587 | desc.count = iov[seg].iov_len; |
1588 | if (desc.count == 0) |
1589 | continue; |
1590 | desc.error = 0; |
1591 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); |
1592 | retval += desc.written; |
1593 | if (desc.error) { |
1594 | retval = retval ?: desc.error; |
1595 | break; |
1596 | } |
1597 | if (desc.count > 0) |
1598 | break; |
1599 | } |
1600 | return retval; |
1601 | } |
1602 | |
1603 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, |
1604 | struct pipe_inode_info *pipe, size_t len, |
1605 | unsigned int flags) |
1606 | { |
1607 | struct address_space *mapping = in->f_mapping; |
1608 | struct inode *inode = mapping->host; |
1609 | unsigned int loff, nr_pages, req_pages; |
1610 | struct page *pages[PIPE_DEF_BUFFERS]; |
1611 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1612 | struct page *page; |
1613 | pgoff_t index, end_index; |
1614 | loff_t isize, left; |
1615 | int error, page_nr; |
1616 | struct splice_pipe_desc spd = { |
1617 | .pages = pages, |
1618 | .partial = partial, |
1619 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1620 | .flags = flags, |
1621 | .ops = &page_cache_pipe_buf_ops, |
1622 | .spd_release = spd_release_page, |
1623 | }; |
1624 | |
1625 | isize = i_size_read(inode); |
1626 | if (unlikely(*ppos >= isize)) |
1627 | return 0; |
1628 | |
1629 | left = isize - *ppos; |
1630 | if (unlikely(left < len)) |
1631 | len = left; |
1632 | |
1633 | if (splice_grow_spd(pipe, &spd)) |
1634 | return -ENOMEM; |
1635 | |
1636 | index = *ppos >> PAGE_CACHE_SHIFT; |
1637 | loff = *ppos & ~PAGE_CACHE_MASK; |
1638 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1639 | nr_pages = min(req_pages, pipe->buffers); |
1640 | |
1641 | spd.nr_pages = find_get_pages_contig(mapping, index, |
1642 | nr_pages, spd.pages); |
1643 | index += spd.nr_pages; |
1644 | error = 0; |
1645 | |
1646 | while (spd.nr_pages < nr_pages) { |
1647 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); |
1648 | if (error) |
1649 | break; |
1650 | unlock_page(page); |
1651 | spd.pages[spd.nr_pages++] = page; |
1652 | index++; |
1653 | } |
1654 | |
1655 | index = *ppos >> PAGE_CACHE_SHIFT; |
1656 | nr_pages = spd.nr_pages; |
1657 | spd.nr_pages = 0; |
1658 | |
1659 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
1660 | unsigned int this_len; |
1661 | |
1662 | if (!len) |
1663 | break; |
1664 | |
1665 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
1666 | page = spd.pages[page_nr]; |
1667 | |
1668 | if (!PageUptodate(page) || page->mapping != mapping) { |
1669 | error = shmem_getpage(inode, index, &page, |
1670 | SGP_CACHE, NULL); |
1671 | if (error) |
1672 | break; |
1673 | unlock_page(page); |
1674 | page_cache_release(spd.pages[page_nr]); |
1675 | spd.pages[page_nr] = page; |
1676 | } |
1677 | |
1678 | isize = i_size_read(inode); |
1679 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
1680 | if (unlikely(!isize || index > end_index)) |
1681 | break; |
1682 | |
1683 | if (end_index == index) { |
1684 | unsigned int plen; |
1685 | |
1686 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
1687 | if (plen <= loff) |
1688 | break; |
1689 | |
1690 | this_len = min(this_len, plen - loff); |
1691 | len = this_len; |
1692 | } |
1693 | |
1694 | spd.partial[page_nr].offset = loff; |
1695 | spd.partial[page_nr].len = this_len; |
1696 | len -= this_len; |
1697 | loff = 0; |
1698 | spd.nr_pages++; |
1699 | index++; |
1700 | } |
1701 | |
1702 | while (page_nr < nr_pages) |
1703 | page_cache_release(spd.pages[page_nr++]); |
1704 | |
1705 | if (spd.nr_pages) |
1706 | error = splice_to_pipe(pipe, &spd); |
1707 | |
1708 | splice_shrink_spd(&spd); |
1709 | |
1710 | if (error > 0) { |
1711 | *ppos += error; |
1712 | file_accessed(in); |
1713 | } |
1714 | return error; |
1715 | } |
1716 | |
1717 | /* |
1718 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. |
1719 | */ |
1720 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, |
1721 | pgoff_t index, pgoff_t end, int whence) |
1722 | { |
1723 | struct page *page; |
1724 | struct pagevec pvec; |
1725 | pgoff_t indices[PAGEVEC_SIZE]; |
1726 | bool done = false; |
1727 | int i; |
1728 | |
1729 | pagevec_init(&pvec, 0); |
1730 | pvec.nr = 1; /* start small: we may be there already */ |
1731 | while (!done) { |
1732 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, |
1733 | pvec.nr, pvec.pages, indices); |
1734 | if (!pvec.nr) { |
1735 | if (whence == SEEK_DATA) |
1736 | index = end; |
1737 | break; |
1738 | } |
1739 | for (i = 0; i < pvec.nr; i++, index++) { |
1740 | if (index < indices[i]) { |
1741 | if (whence == SEEK_HOLE) { |
1742 | done = true; |
1743 | break; |
1744 | } |
1745 | index = indices[i]; |
1746 | } |
1747 | page = pvec.pages[i]; |
1748 | if (page && !radix_tree_exceptional_entry(page)) { |
1749 | if (!PageUptodate(page)) |
1750 | page = NULL; |
1751 | } |
1752 | if (index >= end || |
1753 | (page && whence == SEEK_DATA) || |
1754 | (!page && whence == SEEK_HOLE)) { |
1755 | done = true; |
1756 | break; |
1757 | } |
1758 | } |
1759 | shmem_deswap_pagevec(&pvec); |
1760 | pagevec_release(&pvec); |
1761 | pvec.nr = PAGEVEC_SIZE; |
1762 | cond_resched(); |
1763 | } |
1764 | return index; |
1765 | } |
1766 | |
1767 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) |
1768 | { |
1769 | struct address_space *mapping = file->f_mapping; |
1770 | struct inode *inode = mapping->host; |
1771 | pgoff_t start, end; |
1772 | loff_t new_offset; |
1773 | |
1774 | if (whence != SEEK_DATA && whence != SEEK_HOLE) |
1775 | return generic_file_llseek_size(file, offset, whence, |
1776 | MAX_LFS_FILESIZE, i_size_read(inode)); |
1777 | mutex_lock(&inode->i_mutex); |
1778 | /* We're holding i_mutex so we can access i_size directly */ |
1779 | |
1780 | if (offset < 0) |
1781 | offset = -EINVAL; |
1782 | else if (offset >= inode->i_size) |
1783 | offset = -ENXIO; |
1784 | else { |
1785 | start = offset >> PAGE_CACHE_SHIFT; |
1786 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1787 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); |
1788 | new_offset <<= PAGE_CACHE_SHIFT; |
1789 | if (new_offset > offset) { |
1790 | if (new_offset < inode->i_size) |
1791 | offset = new_offset; |
1792 | else if (whence == SEEK_DATA) |
1793 | offset = -ENXIO; |
1794 | else |
1795 | offset = inode->i_size; |
1796 | } |
1797 | } |
1798 | |
1799 | if (offset >= 0 && offset != file->f_pos) { |
1800 | file->f_pos = offset; |
1801 | file->f_version = 0; |
1802 | } |
1803 | mutex_unlock(&inode->i_mutex); |
1804 | return offset; |
1805 | } |
1806 | |
1807 | static long shmem_fallocate(struct file *file, int mode, loff_t offset, |
1808 | loff_t len) |
1809 | { |
1810 | struct inode *inode = file_inode(file); |
1811 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
1812 | struct shmem_falloc shmem_falloc; |
1813 | pgoff_t start, index, end; |
1814 | int error; |
1815 | |
1816 | mutex_lock(&inode->i_mutex); |
1817 | |
1818 | if (mode & FALLOC_FL_PUNCH_HOLE) { |
1819 | struct address_space *mapping = file->f_mapping; |
1820 | loff_t unmap_start = round_up(offset, PAGE_SIZE); |
1821 | loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; |
1822 | |
1823 | if ((u64)unmap_end > (u64)unmap_start) |
1824 | unmap_mapping_range(mapping, unmap_start, |
1825 | 1 + unmap_end - unmap_start, 0); |
1826 | shmem_truncate_range(inode, offset, offset + len - 1); |
1827 | /* No need to unmap again: hole-punching leaves COWed pages */ |
1828 | error = 0; |
1829 | goto out; |
1830 | } |
1831 | |
1832 | /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ |
1833 | error = inode_newsize_ok(inode, offset + len); |
1834 | if (error) |
1835 | goto out; |
1836 | |
1837 | start = offset >> PAGE_CACHE_SHIFT; |
1838 | end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1839 | /* Try to avoid a swapstorm if len is impossible to satisfy */ |
1840 | if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { |
1841 | error = -ENOSPC; |
1842 | goto out; |
1843 | } |
1844 | |
1845 | shmem_falloc.start = start; |
1846 | shmem_falloc.next = start; |
1847 | shmem_falloc.nr_falloced = 0; |
1848 | shmem_falloc.nr_unswapped = 0; |
1849 | spin_lock(&inode->i_lock); |
1850 | inode->i_private = &shmem_falloc; |
1851 | spin_unlock(&inode->i_lock); |
1852 | |
1853 | for (index = start; index < end; index++) { |
1854 | struct page *page; |
1855 | |
1856 | /* |
1857 | * Good, the fallocate(2) manpage permits EINTR: we may have |
1858 | * been interrupted because we are using up too much memory. |
1859 | */ |
1860 | if (signal_pending(current)) |
1861 | error = -EINTR; |
1862 | else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) |
1863 | error = -ENOMEM; |
1864 | else |
1865 | error = shmem_getpage(inode, index, &page, SGP_FALLOC, |
1866 | NULL); |
1867 | if (error) { |
1868 | /* Remove the !PageUptodate pages we added */ |
1869 | shmem_undo_range(inode, |
1870 | (loff_t)start << PAGE_CACHE_SHIFT, |
1871 | (loff_t)index << PAGE_CACHE_SHIFT, true); |
1872 | goto undone; |
1873 | } |
1874 | |
1875 | /* |
1876 | * Inform shmem_writepage() how far we have reached. |
1877 | * No need for lock or barrier: we have the page lock. |
1878 | */ |
1879 | shmem_falloc.next++; |
1880 | if (!PageUptodate(page)) |
1881 | shmem_falloc.nr_falloced++; |
1882 | |
1883 | /* |
1884 | * If !PageUptodate, leave it that way so that freeable pages |
1885 | * can be recognized if we need to rollback on error later. |
1886 | * But set_page_dirty so that memory pressure will swap rather |
1887 | * than free the pages we are allocating (and SGP_CACHE pages |
1888 | * might still be clean: we now need to mark those dirty too). |
1889 | */ |
1890 | set_page_dirty(page); |
1891 | unlock_page(page); |
1892 | page_cache_release(page); |
1893 | cond_resched(); |
1894 | } |
1895 | |
1896 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) |
1897 | i_size_write(inode, offset + len); |
1898 | inode->i_ctime = CURRENT_TIME; |
1899 | undone: |
1900 | spin_lock(&inode->i_lock); |
1901 | inode->i_private = NULL; |
1902 | spin_unlock(&inode->i_lock); |
1903 | out: |
1904 | mutex_unlock(&inode->i_mutex); |
1905 | return error; |
1906 | } |
1907 | |
1908 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
1909 | { |
1910 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
1911 | |
1912 | buf->f_type = TMPFS_MAGIC; |
1913 | buf->f_bsize = PAGE_CACHE_SIZE; |
1914 | buf->f_namelen = NAME_MAX; |
1915 | if (sbinfo->max_blocks) { |
1916 | buf->f_blocks = sbinfo->max_blocks; |
1917 | buf->f_bavail = |
1918 | buf->f_bfree = sbinfo->max_blocks - |
1919 | percpu_counter_sum(&sbinfo->used_blocks); |
1920 | } |
1921 | if (sbinfo->max_inodes) { |
1922 | buf->f_files = sbinfo->max_inodes; |
1923 | buf->f_ffree = sbinfo->free_inodes; |
1924 | } |
1925 | /* else leave those fields 0 like simple_statfs */ |
1926 | return 0; |
1927 | } |
1928 | |
1929 | /* |
1930 | * File creation. Allocate an inode, and we're done.. |
1931 | */ |
1932 | static int |
1933 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1934 | { |
1935 | struct inode *inode; |
1936 | int error = -ENOSPC; |
1937 | |
1938 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
1939 | if (inode) { |
1940 | error = security_inode_init_security(inode, dir, |
1941 | &dentry->d_name, |
1942 | shmem_initxattrs, NULL); |
1943 | if (error) { |
1944 | if (error != -EOPNOTSUPP) { |
1945 | iput(inode); |
1946 | return error; |
1947 | } |
1948 | } |
1949 | #ifdef CONFIG_TMPFS_POSIX_ACL |
1950 | error = generic_acl_init(inode, dir); |
1951 | if (error) { |
1952 | iput(inode); |
1953 | return error; |
1954 | } |
1955 | #else |
1956 | error = 0; |
1957 | #endif |
1958 | dir->i_size += BOGO_DIRENT_SIZE; |
1959 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1960 | d_instantiate(dentry, inode); |
1961 | dget(dentry); /* Extra count - pin the dentry in core */ |
1962 | } |
1963 | return error; |
1964 | } |
1965 | |
1966 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1967 | { |
1968 | int error; |
1969 | |
1970 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
1971 | return error; |
1972 | inc_nlink(dir); |
1973 | return 0; |
1974 | } |
1975 | |
1976 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
1977 | bool excl) |
1978 | { |
1979 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
1980 | } |
1981 | |
1982 | /* |
1983 | * Link a file.. |
1984 | */ |
1985 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
1986 | { |
1987 | struct inode *inode = old_dentry->d_inode; |
1988 | int ret; |
1989 | |
1990 | /* |
1991 | * No ordinary (disk based) filesystem counts links as inodes; |
1992 | * but each new link needs a new dentry, pinning lowmem, and |
1993 | * tmpfs dentries cannot be pruned until they are unlinked. |
1994 | */ |
1995 | ret = shmem_reserve_inode(inode->i_sb); |
1996 | if (ret) |
1997 | goto out; |
1998 | |
1999 | dir->i_size += BOGO_DIRENT_SIZE; |
2000 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2001 | inc_nlink(inode); |
2002 | ihold(inode); /* New dentry reference */ |
2003 | dget(dentry); /* Extra pinning count for the created dentry */ |
2004 | d_instantiate(dentry, inode); |
2005 | out: |
2006 | return ret; |
2007 | } |
2008 | |
2009 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
2010 | { |
2011 | struct inode *inode = dentry->d_inode; |
2012 | |
2013 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
2014 | shmem_free_inode(inode->i_sb); |
2015 | |
2016 | dir->i_size -= BOGO_DIRENT_SIZE; |
2017 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2018 | drop_nlink(inode); |
2019 | dput(dentry); /* Undo the count from "create" - this does all the work */ |
2020 | return 0; |
2021 | } |
2022 | |
2023 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
2024 | { |
2025 | if (!simple_empty(dentry)) |
2026 | return -ENOTEMPTY; |
2027 | |
2028 | drop_nlink(dentry->d_inode); |
2029 | drop_nlink(dir); |
2030 | return shmem_unlink(dir, dentry); |
2031 | } |
2032 | |
2033 | /* |
2034 | * The VFS layer already does all the dentry stuff for rename, |
2035 | * we just have to decrement the usage count for the target if |
2036 | * it exists so that the VFS layer correctly free's it when it |
2037 | * gets overwritten. |
2038 | */ |
2039 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
2040 | { |
2041 | struct inode *inode = old_dentry->d_inode; |
2042 | int they_are_dirs = S_ISDIR(inode->i_mode); |
2043 | |
2044 | if (!simple_empty(new_dentry)) |
2045 | return -ENOTEMPTY; |
2046 | |
2047 | if (new_dentry->d_inode) { |
2048 | (void) shmem_unlink(new_dir, new_dentry); |
2049 | if (they_are_dirs) |
2050 | drop_nlink(old_dir); |
2051 | } else if (they_are_dirs) { |
2052 | drop_nlink(old_dir); |
2053 | inc_nlink(new_dir); |
2054 | } |
2055 | |
2056 | old_dir->i_size -= BOGO_DIRENT_SIZE; |
2057 | new_dir->i_size += BOGO_DIRENT_SIZE; |
2058 | old_dir->i_ctime = old_dir->i_mtime = |
2059 | new_dir->i_ctime = new_dir->i_mtime = |
2060 | inode->i_ctime = CURRENT_TIME; |
2061 | return 0; |
2062 | } |
2063 | |
2064 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
2065 | { |
2066 | int error; |
2067 | int len; |
2068 | struct inode *inode; |
2069 | struct page *page; |
2070 | char *kaddr; |
2071 | struct shmem_inode_info *info; |
2072 | |
2073 | len = strlen(symname) + 1; |
2074 | if (len > PAGE_CACHE_SIZE) |
2075 | return -ENAMETOOLONG; |
2076 | |
2077 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
2078 | if (!inode) |
2079 | return -ENOSPC; |
2080 | |
2081 | error = security_inode_init_security(inode, dir, &dentry->d_name, |
2082 | shmem_initxattrs, NULL); |
2083 | if (error) { |
2084 | if (error != -EOPNOTSUPP) { |
2085 | iput(inode); |
2086 | return error; |
2087 | } |
2088 | error = 0; |
2089 | } |
2090 | |
2091 | info = SHMEM_I(inode); |
2092 | inode->i_size = len-1; |
2093 | if (len <= SHORT_SYMLINK_LEN) { |
2094 | info->symlink = kmemdup(symname, len, GFP_KERNEL); |
2095 | if (!info->symlink) { |
2096 | iput(inode); |
2097 | return -ENOMEM; |
2098 | } |
2099 | inode->i_op = &shmem_short_symlink_operations; |
2100 | } else { |
2101 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
2102 | if (error) { |
2103 | iput(inode); |
2104 | return error; |
2105 | } |
2106 | inode->i_mapping->a_ops = &shmem_aops; |
2107 | inode->i_op = &shmem_symlink_inode_operations; |
2108 | kaddr = kmap_atomic(page); |
2109 | memcpy(kaddr, symname, len); |
2110 | kunmap_atomic(kaddr); |
2111 | SetPageUptodate(page); |
2112 | set_page_dirty(page); |
2113 | unlock_page(page); |
2114 | page_cache_release(page); |
2115 | } |
2116 | dir->i_size += BOGO_DIRENT_SIZE; |
2117 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2118 | d_instantiate(dentry, inode); |
2119 | dget(dentry); |
2120 | return 0; |
2121 | } |
2122 | |
2123 | static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) |
2124 | { |
2125 | nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); |
2126 | return NULL; |
2127 | } |
2128 | |
2129 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
2130 | { |
2131 | struct page *page = NULL; |
2132 | int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
2133 | nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); |
2134 | if (page) |
2135 | unlock_page(page); |
2136 | return page; |
2137 | } |
2138 | |
2139 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
2140 | { |
2141 | if (!IS_ERR(nd_get_link(nd))) { |
2142 | struct page *page = cookie; |
2143 | kunmap(page); |
2144 | mark_page_accessed(page); |
2145 | page_cache_release(page); |
2146 | } |
2147 | } |
2148 | |
2149 | #ifdef CONFIG_TMPFS_XATTR |
2150 | /* |
2151 | * Superblocks without xattr inode operations may get some security.* xattr |
2152 | * support from the LSM "for free". As soon as we have any other xattrs |
2153 | * like ACLs, we also need to implement the security.* handlers at |
2154 | * filesystem level, though. |
2155 | */ |
2156 | |
2157 | /* |
2158 | * Callback for security_inode_init_security() for acquiring xattrs. |
2159 | */ |
2160 | static int shmem_initxattrs(struct inode *inode, |
2161 | const struct xattr *xattr_array, |
2162 | void *fs_info) |
2163 | { |
2164 | struct shmem_inode_info *info = SHMEM_I(inode); |
2165 | const struct xattr *xattr; |
2166 | struct simple_xattr *new_xattr; |
2167 | size_t len; |
2168 | |
2169 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { |
2170 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); |
2171 | if (!new_xattr) |
2172 | return -ENOMEM; |
2173 | |
2174 | len = strlen(xattr->name) + 1; |
2175 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, |
2176 | GFP_KERNEL); |
2177 | if (!new_xattr->name) { |
2178 | kfree(new_xattr); |
2179 | return -ENOMEM; |
2180 | } |
2181 | |
2182 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, |
2183 | XATTR_SECURITY_PREFIX_LEN); |
2184 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, |
2185 | xattr->name, len); |
2186 | |
2187 | simple_xattr_list_add(&info->xattrs, new_xattr); |
2188 | } |
2189 | |
2190 | return 0; |
2191 | } |
2192 | |
2193 | static const struct xattr_handler *shmem_xattr_handlers[] = { |
2194 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2195 | &generic_acl_access_handler, |
2196 | &generic_acl_default_handler, |
2197 | #endif |
2198 | NULL |
2199 | }; |
2200 | |
2201 | static int shmem_xattr_validate(const char *name) |
2202 | { |
2203 | struct { const char *prefix; size_t len; } arr[] = { |
2204 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, |
2205 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } |
2206 | }; |
2207 | int i; |
2208 | |
2209 | for (i = 0; i < ARRAY_SIZE(arr); i++) { |
2210 | size_t preflen = arr[i].len; |
2211 | if (strncmp(name, arr[i].prefix, preflen) == 0) { |
2212 | if (!name[preflen]) |
2213 | return -EINVAL; |
2214 | return 0; |
2215 | } |
2216 | } |
2217 | return -EOPNOTSUPP; |
2218 | } |
2219 | |
2220 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, |
2221 | void *buffer, size_t size) |
2222 | { |
2223 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2224 | int err; |
2225 | |
2226 | /* |
2227 | * If this is a request for a synthetic attribute in the system.* |
2228 | * namespace use the generic infrastructure to resolve a handler |
2229 | * for it via sb->s_xattr. |
2230 | */ |
2231 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2232 | return generic_getxattr(dentry, name, buffer, size); |
2233 | |
2234 | err = shmem_xattr_validate(name); |
2235 | if (err) |
2236 | return err; |
2237 | |
2238 | return simple_xattr_get(&info->xattrs, name, buffer, size); |
2239 | } |
2240 | |
2241 | static int shmem_setxattr(struct dentry *dentry, const char *name, |
2242 | const void *value, size_t size, int flags) |
2243 | { |
2244 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2245 | int err; |
2246 | |
2247 | /* |
2248 | * If this is a request for a synthetic attribute in the system.* |
2249 | * namespace use the generic infrastructure to resolve a handler |
2250 | * for it via sb->s_xattr. |
2251 | */ |
2252 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2253 | return generic_setxattr(dentry, name, value, size, flags); |
2254 | |
2255 | err = shmem_xattr_validate(name); |
2256 | if (err) |
2257 | return err; |
2258 | |
2259 | return simple_xattr_set(&info->xattrs, name, value, size, flags); |
2260 | } |
2261 | |
2262 | static int shmem_removexattr(struct dentry *dentry, const char *name) |
2263 | { |
2264 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2265 | int err; |
2266 | |
2267 | /* |
2268 | * If this is a request for a synthetic attribute in the system.* |
2269 | * namespace use the generic infrastructure to resolve a handler |
2270 | * for it via sb->s_xattr. |
2271 | */ |
2272 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2273 | return generic_removexattr(dentry, name); |
2274 | |
2275 | err = shmem_xattr_validate(name); |
2276 | if (err) |
2277 | return err; |
2278 | |
2279 | return simple_xattr_remove(&info->xattrs, name); |
2280 | } |
2281 | |
2282 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) |
2283 | { |
2284 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2285 | return simple_xattr_list(&info->xattrs, buffer, size); |
2286 | } |
2287 | #endif /* CONFIG_TMPFS_XATTR */ |
2288 | |
2289 | static const struct inode_operations shmem_short_symlink_operations = { |
2290 | .readlink = generic_readlink, |
2291 | .follow_link = shmem_follow_short_symlink, |
2292 | #ifdef CONFIG_TMPFS_XATTR |
2293 | .setxattr = shmem_setxattr, |
2294 | .getxattr = shmem_getxattr, |
2295 | .listxattr = shmem_listxattr, |
2296 | .removexattr = shmem_removexattr, |
2297 | #endif |
2298 | }; |
2299 | |
2300 | static const struct inode_operations shmem_symlink_inode_operations = { |
2301 | .readlink = generic_readlink, |
2302 | .follow_link = shmem_follow_link, |
2303 | .put_link = shmem_put_link, |
2304 | #ifdef CONFIG_TMPFS_XATTR |
2305 | .setxattr = shmem_setxattr, |
2306 | .getxattr = shmem_getxattr, |
2307 | .listxattr = shmem_listxattr, |
2308 | .removexattr = shmem_removexattr, |
2309 | #endif |
2310 | }; |
2311 | |
2312 | static struct dentry *shmem_get_parent(struct dentry *child) |
2313 | { |
2314 | return ERR_PTR(-ESTALE); |
2315 | } |
2316 | |
2317 | static int shmem_match(struct inode *ino, void *vfh) |
2318 | { |
2319 | __u32 *fh = vfh; |
2320 | __u64 inum = fh[2]; |
2321 | inum = (inum << 32) | fh[1]; |
2322 | return ino->i_ino == inum && fh[0] == ino->i_generation; |
2323 | } |
2324 | |
2325 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
2326 | struct fid *fid, int fh_len, int fh_type) |
2327 | { |
2328 | struct inode *inode; |
2329 | struct dentry *dentry = NULL; |
2330 | u64 inum; |
2331 | |
2332 | if (fh_len < 3) |
2333 | return NULL; |
2334 | |
2335 | inum = fid->raw[2]; |
2336 | inum = (inum << 32) | fid->raw[1]; |
2337 | |
2338 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
2339 | shmem_match, fid->raw); |
2340 | if (inode) { |
2341 | dentry = d_find_alias(inode); |
2342 | iput(inode); |
2343 | } |
2344 | |
2345 | return dentry; |
2346 | } |
2347 | |
2348 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, |
2349 | struct inode *parent) |
2350 | { |
2351 | if (*len < 3) { |
2352 | *len = 3; |
2353 | return FILEID_INVALID; |
2354 | } |
2355 | |
2356 | if (inode_unhashed(inode)) { |
2357 | /* Unfortunately insert_inode_hash is not idempotent, |
2358 | * so as we hash inodes here rather than at creation |
2359 | * time, we need a lock to ensure we only try |
2360 | * to do it once |
2361 | */ |
2362 | static DEFINE_SPINLOCK(lock); |
2363 | spin_lock(&lock); |
2364 | if (inode_unhashed(inode)) |
2365 | __insert_inode_hash(inode, |
2366 | inode->i_ino + inode->i_generation); |
2367 | spin_unlock(&lock); |
2368 | } |
2369 | |
2370 | fh[0] = inode->i_generation; |
2371 | fh[1] = inode->i_ino; |
2372 | fh[2] = ((__u64)inode->i_ino) >> 32; |
2373 | |
2374 | *len = 3; |
2375 | return 1; |
2376 | } |
2377 | |
2378 | static const struct export_operations shmem_export_ops = { |
2379 | .get_parent = shmem_get_parent, |
2380 | .encode_fh = shmem_encode_fh, |
2381 | .fh_to_dentry = shmem_fh_to_dentry, |
2382 | }; |
2383 | |
2384 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
2385 | bool remount) |
2386 | { |
2387 | char *this_char, *value, *rest; |
2388 | struct mempolicy *mpol = NULL; |
2389 | uid_t uid; |
2390 | gid_t gid; |
2391 | |
2392 | while (options != NULL) { |
2393 | this_char = options; |
2394 | for (;;) { |
2395 | /* |
2396 | * NUL-terminate this option: unfortunately, |
2397 | * mount options form a comma-separated list, |
2398 | * but mpol's nodelist may also contain commas. |
2399 | */ |
2400 | options = strchr(options, ','); |
2401 | if (options == NULL) |
2402 | break; |
2403 | options++; |
2404 | if (!isdigit(*options)) { |
2405 | options[-1] = '\0'; |
2406 | break; |
2407 | } |
2408 | } |
2409 | if (!*this_char) |
2410 | continue; |
2411 | if ((value = strchr(this_char,'=')) != NULL) { |
2412 | *value++ = 0; |
2413 | } else { |
2414 | printk(KERN_ERR |
2415 | "tmpfs: No value for mount option '%s'\n", |
2416 | this_char); |
2417 | goto error; |
2418 | } |
2419 | |
2420 | if (!strcmp(this_char,"size")) { |
2421 | unsigned long long size; |
2422 | size = memparse(value,&rest); |
2423 | if (*rest == '%') { |
2424 | size <<= PAGE_SHIFT; |
2425 | size *= totalram_pages; |
2426 | do_div(size, 100); |
2427 | rest++; |
2428 | } |
2429 | if (*rest) |
2430 | goto bad_val; |
2431 | sbinfo->max_blocks = |
2432 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
2433 | } else if (!strcmp(this_char,"nr_blocks")) { |
2434 | sbinfo->max_blocks = memparse(value, &rest); |
2435 | if (*rest) |
2436 | goto bad_val; |
2437 | } else if (!strcmp(this_char,"nr_inodes")) { |
2438 | sbinfo->max_inodes = memparse(value, &rest); |
2439 | if (*rest) |
2440 | goto bad_val; |
2441 | } else if (!strcmp(this_char,"mode")) { |
2442 | if (remount) |
2443 | continue; |
2444 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
2445 | if (*rest) |
2446 | goto bad_val; |
2447 | } else if (!strcmp(this_char,"uid")) { |
2448 | if (remount) |
2449 | continue; |
2450 | uid = simple_strtoul(value, &rest, 0); |
2451 | if (*rest) |
2452 | goto bad_val; |
2453 | sbinfo->uid = make_kuid(current_user_ns(), uid); |
2454 | if (!uid_valid(sbinfo->uid)) |
2455 | goto bad_val; |
2456 | } else if (!strcmp(this_char,"gid")) { |
2457 | if (remount) |
2458 | continue; |
2459 | gid = simple_strtoul(value, &rest, 0); |
2460 | if (*rest) |
2461 | goto bad_val; |
2462 | sbinfo->gid = make_kgid(current_user_ns(), gid); |
2463 | if (!gid_valid(sbinfo->gid)) |
2464 | goto bad_val; |
2465 | } else if (!strcmp(this_char,"mpol")) { |
2466 | mpol_put(mpol); |
2467 | mpol = NULL; |
2468 | if (mpol_parse_str(value, &mpol)) |
2469 | goto bad_val; |
2470 | } else { |
2471 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
2472 | this_char); |
2473 | goto error; |
2474 | } |
2475 | } |
2476 | sbinfo->mpol = mpol; |
2477 | return 0; |
2478 | |
2479 | bad_val: |
2480 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
2481 | value, this_char); |
2482 | error: |
2483 | mpol_put(mpol); |
2484 | return 1; |
2485 | |
2486 | } |
2487 | |
2488 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
2489 | { |
2490 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2491 | struct shmem_sb_info config = *sbinfo; |
2492 | unsigned long inodes; |
2493 | int error = -EINVAL; |
2494 | |
2495 | config.mpol = NULL; |
2496 | if (shmem_parse_options(data, &config, true)) |
2497 | return error; |
2498 | |
2499 | spin_lock(&sbinfo->stat_lock); |
2500 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
2501 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) |
2502 | goto out; |
2503 | if (config.max_inodes < inodes) |
2504 | goto out; |
2505 | /* |
2506 | * Those tests disallow limited->unlimited while any are in use; |
2507 | * but we must separately disallow unlimited->limited, because |
2508 | * in that case we have no record of how much is already in use. |
2509 | */ |
2510 | if (config.max_blocks && !sbinfo->max_blocks) |
2511 | goto out; |
2512 | if (config.max_inodes && !sbinfo->max_inodes) |
2513 | goto out; |
2514 | |
2515 | error = 0; |
2516 | sbinfo->max_blocks = config.max_blocks; |
2517 | sbinfo->max_inodes = config.max_inodes; |
2518 | sbinfo->free_inodes = config.max_inodes - inodes; |
2519 | |
2520 | /* |
2521 | * Preserve previous mempolicy unless mpol remount option was specified. |
2522 | */ |
2523 | if (config.mpol) { |
2524 | mpol_put(sbinfo->mpol); |
2525 | sbinfo->mpol = config.mpol; /* transfers initial ref */ |
2526 | } |
2527 | out: |
2528 | spin_unlock(&sbinfo->stat_lock); |
2529 | return error; |
2530 | } |
2531 | |
2532 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) |
2533 | { |
2534 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); |
2535 | |
2536 | if (sbinfo->max_blocks != shmem_default_max_blocks()) |
2537 | seq_printf(seq, ",size=%luk", |
2538 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
2539 | if (sbinfo->max_inodes != shmem_default_max_inodes()) |
2540 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
2541 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
2542 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); |
2543 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) |
2544 | seq_printf(seq, ",uid=%u", |
2545 | from_kuid_munged(&init_user_ns, sbinfo->uid)); |
2546 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) |
2547 | seq_printf(seq, ",gid=%u", |
2548 | from_kgid_munged(&init_user_ns, sbinfo->gid)); |
2549 | shmem_show_mpol(seq, sbinfo->mpol); |
2550 | return 0; |
2551 | } |
2552 | #endif /* CONFIG_TMPFS */ |
2553 | |
2554 | static void shmem_put_super(struct super_block *sb) |
2555 | { |
2556 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2557 | |
2558 | percpu_counter_destroy(&sbinfo->used_blocks); |
2559 | mpol_put(sbinfo->mpol); |
2560 | kfree(sbinfo); |
2561 | sb->s_fs_info = NULL; |
2562 | } |
2563 | |
2564 | int shmem_fill_super(struct super_block *sb, void *data, int silent) |
2565 | { |
2566 | struct inode *inode; |
2567 | struct shmem_sb_info *sbinfo; |
2568 | int err = -ENOMEM; |
2569 | |
2570 | /* Round up to L1_CACHE_BYTES to resist false sharing */ |
2571 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
2572 | L1_CACHE_BYTES), GFP_KERNEL); |
2573 | if (!sbinfo) |
2574 | return -ENOMEM; |
2575 | |
2576 | sbinfo->mode = S_IRWXUGO | S_ISVTX; |
2577 | sbinfo->uid = current_fsuid(); |
2578 | sbinfo->gid = current_fsgid(); |
2579 | sb->s_fs_info = sbinfo; |
2580 | |
2581 | #ifdef CONFIG_TMPFS |
2582 | /* |
2583 | * Per default we only allow half of the physical ram per |
2584 | * tmpfs instance, limiting inodes to one per page of lowmem; |
2585 | * but the internal instance is left unlimited. |
2586 | */ |
2587 | if (!(sb->s_flags & MS_NOUSER)) { |
2588 | sbinfo->max_blocks = shmem_default_max_blocks(); |
2589 | sbinfo->max_inodes = shmem_default_max_inodes(); |
2590 | if (shmem_parse_options(data, sbinfo, false)) { |
2591 | err = -EINVAL; |
2592 | goto failed; |
2593 | } |
2594 | } |
2595 | sb->s_export_op = &shmem_export_ops; |
2596 | sb->s_flags |= MS_NOSEC; |
2597 | #else |
2598 | sb->s_flags |= MS_NOUSER; |
2599 | #endif |
2600 | |
2601 | spin_lock_init(&sbinfo->stat_lock); |
2602 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) |
2603 | goto failed; |
2604 | sbinfo->free_inodes = sbinfo->max_inodes; |
2605 | |
2606 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
2607 | sb->s_blocksize = PAGE_CACHE_SIZE; |
2608 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
2609 | sb->s_magic = TMPFS_MAGIC; |
2610 | sb->s_op = &shmem_ops; |
2611 | sb->s_time_gran = 1; |
2612 | #ifdef CONFIG_TMPFS_XATTR |
2613 | sb->s_xattr = shmem_xattr_handlers; |
2614 | #endif |
2615 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2616 | sb->s_flags |= MS_POSIXACL; |
2617 | #endif |
2618 | |
2619 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
2620 | if (!inode) |
2621 | goto failed; |
2622 | inode->i_uid = sbinfo->uid; |
2623 | inode->i_gid = sbinfo->gid; |
2624 | sb->s_root = d_make_root(inode); |
2625 | if (!sb->s_root) |
2626 | goto failed; |
2627 | return 0; |
2628 | |
2629 | failed: |
2630 | shmem_put_super(sb); |
2631 | return err; |
2632 | } |
2633 | |
2634 | static struct kmem_cache *shmem_inode_cachep; |
2635 | |
2636 | static struct inode *shmem_alloc_inode(struct super_block *sb) |
2637 | { |
2638 | struct shmem_inode_info *info; |
2639 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
2640 | if (!info) |
2641 | return NULL; |
2642 | return &info->vfs_inode; |
2643 | } |
2644 | |
2645 | static void shmem_destroy_callback(struct rcu_head *head) |
2646 | { |
2647 | struct inode *inode = container_of(head, struct inode, i_rcu); |
2648 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
2649 | } |
2650 | |
2651 | static void shmem_destroy_inode(struct inode *inode) |
2652 | { |
2653 | if (S_ISREG(inode->i_mode)) |
2654 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
2655 | call_rcu(&inode->i_rcu, shmem_destroy_callback); |
2656 | } |
2657 | |
2658 | static void shmem_init_inode(void *foo) |
2659 | { |
2660 | struct shmem_inode_info *info = foo; |
2661 | inode_init_once(&info->vfs_inode); |
2662 | } |
2663 | |
2664 | static int shmem_init_inodecache(void) |
2665 | { |
2666 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
2667 | sizeof(struct shmem_inode_info), |
2668 | 0, SLAB_PANIC, shmem_init_inode); |
2669 | return 0; |
2670 | } |
2671 | |
2672 | static void shmem_destroy_inodecache(void) |
2673 | { |
2674 | kmem_cache_destroy(shmem_inode_cachep); |
2675 | } |
2676 | |
2677 | static const struct address_space_operations shmem_aops = { |
2678 | .writepage = shmem_writepage, |
2679 | .set_page_dirty = __set_page_dirty_no_writeback, |
2680 | #ifdef CONFIG_TMPFS |
2681 | .write_begin = shmem_write_begin, |
2682 | .write_end = shmem_write_end, |
2683 | #endif |
2684 | .migratepage = migrate_page, |
2685 | .error_remove_page = generic_error_remove_page, |
2686 | }; |
2687 | |
2688 | static const struct file_operations shmem_file_operations = { |
2689 | .mmap = shmem_mmap, |
2690 | #ifdef CONFIG_TMPFS |
2691 | .llseek = shmem_file_llseek, |
2692 | .read = do_sync_read, |
2693 | .write = do_sync_write, |
2694 | .aio_read = shmem_file_aio_read, |
2695 | .aio_write = generic_file_aio_write, |
2696 | .fsync = noop_fsync, |
2697 | .splice_read = shmem_file_splice_read, |
2698 | .splice_write = generic_file_splice_write, |
2699 | .fallocate = shmem_fallocate, |
2700 | #endif |
2701 | }; |
2702 | |
2703 | static const struct inode_operations shmem_inode_operations = { |
2704 | .setattr = shmem_setattr, |
2705 | #ifdef CONFIG_TMPFS_XATTR |
2706 | .setxattr = shmem_setxattr, |
2707 | .getxattr = shmem_getxattr, |
2708 | .listxattr = shmem_listxattr, |
2709 | .removexattr = shmem_removexattr, |
2710 | #endif |
2711 | }; |
2712 | |
2713 | static const struct inode_operations shmem_dir_inode_operations = { |
2714 | #ifdef CONFIG_TMPFS |
2715 | .create = shmem_create, |
2716 | .lookup = simple_lookup, |
2717 | .link = shmem_link, |
2718 | .unlink = shmem_unlink, |
2719 | .symlink = shmem_symlink, |
2720 | .mkdir = shmem_mkdir, |
2721 | .rmdir = shmem_rmdir, |
2722 | .mknod = shmem_mknod, |
2723 | .rename = shmem_rename, |
2724 | #endif |
2725 | #ifdef CONFIG_TMPFS_XATTR |
2726 | .setxattr = shmem_setxattr, |
2727 | .getxattr = shmem_getxattr, |
2728 | .listxattr = shmem_listxattr, |
2729 | .removexattr = shmem_removexattr, |
2730 | #endif |
2731 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2732 | .setattr = shmem_setattr, |
2733 | #endif |
2734 | }; |
2735 | |
2736 | static const struct inode_operations shmem_special_inode_operations = { |
2737 | #ifdef CONFIG_TMPFS_XATTR |
2738 | .setxattr = shmem_setxattr, |
2739 | .getxattr = shmem_getxattr, |
2740 | .listxattr = shmem_listxattr, |
2741 | .removexattr = shmem_removexattr, |
2742 | #endif |
2743 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2744 | .setattr = shmem_setattr, |
2745 | #endif |
2746 | }; |
2747 | |
2748 | static const struct super_operations shmem_ops = { |
2749 | .alloc_inode = shmem_alloc_inode, |
2750 | .destroy_inode = shmem_destroy_inode, |
2751 | #ifdef CONFIG_TMPFS |
2752 | .statfs = shmem_statfs, |
2753 | .remount_fs = shmem_remount_fs, |
2754 | .show_options = shmem_show_options, |
2755 | #endif |
2756 | .evict_inode = shmem_evict_inode, |
2757 | .drop_inode = generic_delete_inode, |
2758 | .put_super = shmem_put_super, |
2759 | }; |
2760 | |
2761 | static const struct vm_operations_struct shmem_vm_ops = { |
2762 | .fault = shmem_fault, |
2763 | #ifdef CONFIG_NUMA |
2764 | .set_policy = shmem_set_policy, |
2765 | .get_policy = shmem_get_policy, |
2766 | #endif |
2767 | .remap_pages = generic_file_remap_pages, |
2768 | }; |
2769 | |
2770 | static struct dentry *shmem_mount(struct file_system_type *fs_type, |
2771 | int flags, const char *dev_name, void *data) |
2772 | { |
2773 | return mount_nodev(fs_type, flags, data, shmem_fill_super); |
2774 | } |
2775 | |
2776 | static struct file_system_type shmem_fs_type = { |
2777 | .owner = THIS_MODULE, |
2778 | .name = "tmpfs", |
2779 | .mount = shmem_mount, |
2780 | .kill_sb = kill_litter_super, |
2781 | .fs_flags = FS_USERNS_MOUNT, |
2782 | }; |
2783 | |
2784 | int __init shmem_init(void) |
2785 | { |
2786 | int error; |
2787 | |
2788 | error = bdi_init(&shmem_backing_dev_info); |
2789 | if (error) |
2790 | goto out4; |
2791 | |
2792 | error = shmem_init_inodecache(); |
2793 | if (error) |
2794 | goto out3; |
2795 | |
2796 | error = register_filesystem(&shmem_fs_type); |
2797 | if (error) { |
2798 | printk(KERN_ERR "Could not register tmpfs\n"); |
2799 | goto out2; |
2800 | } |
2801 | |
2802 | shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER, |
2803 | shmem_fs_type.name, NULL); |
2804 | if (IS_ERR(shm_mnt)) { |
2805 | error = PTR_ERR(shm_mnt); |
2806 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
2807 | goto out1; |
2808 | } |
2809 | return 0; |
2810 | |
2811 | out1: |
2812 | unregister_filesystem(&shmem_fs_type); |
2813 | out2: |
2814 | shmem_destroy_inodecache(); |
2815 | out3: |
2816 | bdi_destroy(&shmem_backing_dev_info); |
2817 | out4: |
2818 | shm_mnt = ERR_PTR(error); |
2819 | return error; |
2820 | } |
2821 | |
2822 | #else /* !CONFIG_SHMEM */ |
2823 | |
2824 | /* |
2825 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
2826 | * |
2827 | * This is intended for small system where the benefits of the full |
2828 | * shmem code (swap-backed and resource-limited) are outweighed by |
2829 | * their complexity. On systems without swap this code should be |
2830 | * effectively equivalent, but much lighter weight. |
2831 | */ |
2832 | |
2833 | #include <linux/ramfs.h> |
2834 | |
2835 | static struct file_system_type shmem_fs_type = { |
2836 | .name = "tmpfs", |
2837 | .mount = ramfs_mount, |
2838 | .kill_sb = kill_litter_super, |
2839 | .fs_flags = FS_USERNS_MOUNT, |
2840 | }; |
2841 | |
2842 | int __init shmem_init(void) |
2843 | { |
2844 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); |
2845 | |
2846 | shm_mnt = kern_mount(&shmem_fs_type); |
2847 | BUG_ON(IS_ERR(shm_mnt)); |
2848 | |
2849 | return 0; |
2850 | } |
2851 | |
2852 | int shmem_unuse(swp_entry_t swap, struct page *page) |
2853 | { |
2854 | return 0; |
2855 | } |
2856 | |
2857 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
2858 | { |
2859 | return 0; |
2860 | } |
2861 | |
2862 | void shmem_unlock_mapping(struct address_space *mapping) |
2863 | { |
2864 | } |
2865 | |
2866 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
2867 | { |
2868 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); |
2869 | } |
2870 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
2871 | |
2872 | #define shmem_vm_ops generic_file_vm_ops |
2873 | #define shmem_file_operations ramfs_file_operations |
2874 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) |
2875 | #define shmem_acct_size(flags, size) 0 |
2876 | #define shmem_unacct_size(flags, size) do {} while (0) |
2877 | |
2878 | #endif /* CONFIG_SHMEM */ |
2879 | |
2880 | /* common code */ |
2881 | |
2882 | static char *shmem_dname(struct dentry *dentry, char *buffer, int buflen) |
2883 | { |
2884 | return dynamic_dname(dentry, buffer, buflen, "/%s (deleted)", |
2885 | dentry->d_name.name); |
2886 | } |
2887 | |
2888 | static struct dentry_operations anon_ops = { |
2889 | .d_dname = shmem_dname |
2890 | }; |
2891 | |
2892 | /** |
2893 | * shmem_file_setup - get an unlinked file living in tmpfs |
2894 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2895 | * @size: size to be set for the file |
2896 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2897 | */ |
2898 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
2899 | { |
2900 | struct file *res; |
2901 | struct inode *inode; |
2902 | struct path path; |
2903 | struct super_block *sb; |
2904 | struct qstr this; |
2905 | |
2906 | if (IS_ERR(shm_mnt)) |
2907 | return ERR_CAST(shm_mnt); |
2908 | |
2909 | if (size < 0 || size > MAX_LFS_FILESIZE) |
2910 | return ERR_PTR(-EINVAL); |
2911 | |
2912 | if (shmem_acct_size(flags, size)) |
2913 | return ERR_PTR(-ENOMEM); |
2914 | |
2915 | res = ERR_PTR(-ENOMEM); |
2916 | this.name = name; |
2917 | this.len = strlen(name); |
2918 | this.hash = 0; /* will go */ |
2919 | sb = shm_mnt->mnt_sb; |
2920 | path.dentry = d_alloc_pseudo(sb, &this); |
2921 | if (!path.dentry) |
2922 | goto put_memory; |
2923 | d_set_d_op(path.dentry, &anon_ops); |
2924 | path.mnt = mntget(shm_mnt); |
2925 | |
2926 | res = ERR_PTR(-ENOSPC); |
2927 | inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); |
2928 | if (!inode) |
2929 | goto put_dentry; |
2930 | |
2931 | d_instantiate(path.dentry, inode); |
2932 | inode->i_size = size; |
2933 | clear_nlink(inode); /* It is unlinked */ |
2934 | #ifndef CONFIG_MMU |
2935 | res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); |
2936 | if (IS_ERR(res)) |
2937 | goto put_dentry; |
2938 | #endif |
2939 | |
2940 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
2941 | &shmem_file_operations); |
2942 | if (IS_ERR(res)) |
2943 | goto put_dentry; |
2944 | |
2945 | return res; |
2946 | |
2947 | put_dentry: |
2948 | path_put(&path); |
2949 | put_memory: |
2950 | shmem_unacct_size(flags, size); |
2951 | return res; |
2952 | } |
2953 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
2954 | |
2955 | /** |
2956 | * shmem_zero_setup - setup a shared anonymous mapping |
2957 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
2958 | */ |
2959 | int shmem_zero_setup(struct vm_area_struct *vma) |
2960 | { |
2961 | struct file *file; |
2962 | loff_t size = vma->vm_end - vma->vm_start; |
2963 | |
2964 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
2965 | if (IS_ERR(file)) |
2966 | return PTR_ERR(file); |
2967 | |
2968 | if (vma->vm_file) |
2969 | fput(vma->vm_file); |
2970 | vma->vm_file = file; |
2971 | vma->vm_ops = &shmem_vm_ops; |
2972 | return 0; |
2973 | } |
2974 | |
2975 | /** |
2976 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. |
2977 | * @mapping: the page's address_space |
2978 | * @index: the page index |
2979 | * @gfp: the page allocator flags to use if allocating |
2980 | * |
2981 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", |
2982 | * with any new page allocations done using the specified allocation flags. |
2983 | * But read_cache_page_gfp() uses the ->readpage() method: which does not |
2984 | * suit tmpfs, since it may have pages in swapcache, and needs to find those |
2985 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. |
2986 | * |
2987 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in |
2988 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. |
2989 | */ |
2990 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, |
2991 | pgoff_t index, gfp_t gfp) |
2992 | { |
2993 | #ifdef CONFIG_SHMEM |
2994 | struct inode *inode = mapping->host; |
2995 | struct page *page; |
2996 | int error; |
2997 | |
2998 | BUG_ON(mapping->a_ops != &shmem_aops); |
2999 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); |
3000 | if (error) |
3001 | page = ERR_PTR(error); |
3002 | else |
3003 | unlock_page(page); |
3004 | return page; |
3005 | #else |
3006 | /* |
3007 | * The tiny !SHMEM case uses ramfs without swap |
3008 | */ |
3009 | return read_cache_page_gfp(mapping, index, gfp); |
3010 | #endif |
3011 | } |
3012 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |
3013 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9