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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/ramfs.h> | |
29 | #include <linux/pagemap.h> | |
30 | #include <linux/file.h> | |
31 | #include <linux/mm.h> | |
32 | #include <linux/export.h> | |
33 | #include <linux/swap.h> | |
34 | #include <linux/aio.h> | |
35 | ||
36 | static struct vfsmount *shm_mnt; | |
37 | ||
38 | #ifdef CONFIG_SHMEM | |
39 | /* | |
40 | * This virtual memory filesystem is heavily based on the ramfs. It | |
41 | * extends ramfs by the ability to use swap and honor resource limits | |
42 | * which makes it a completely usable filesystem. | |
43 | */ | |
44 | ||
45 | #include <linux/xattr.h> | |
46 | #include <linux/exportfs.h> | |
47 | #include <linux/posix_acl.h> | |
48 | #include <linux/generic_acl.h> | |
49 | #include <linux/mman.h> | |
50 | #include <linux/string.h> | |
51 | #include <linux/slab.h> | |
52 | #include <linux/backing-dev.h> | |
53 | #include <linux/shmem_fs.h> | |
54 | #include <linux/writeback.h> | |
55 | #include <linux/blkdev.h> | |
56 | #include <linux/pagevec.h> | |
57 | #include <linux/percpu_counter.h> | |
58 | #include <linux/falloc.h> | |
59 | #include <linux/splice.h> | |
60 | #include <linux/security.h> | |
61 | #include <linux/swapops.h> | |
62 | #include <linux/mempolicy.h> | |
63 | #include <linux/namei.h> | |
64 | #include <linux/ctype.h> | |
65 | #include <linux/migrate.h> | |
66 | #include <linux/highmem.h> | |
67 | #include <linux/seq_file.h> | |
68 | #include <linux/magic.h> | |
69 | ||
70 | #include <asm/uaccess.h> | |
71 | #include <asm/pgtable.h> | |
72 | ||
73 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) | |
74 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) | |
75 | ||
76 | /* Pretend that each entry is of this size in directory's i_size */ | |
77 | #define BOGO_DIRENT_SIZE 20 | |
78 | ||
79 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ | |
80 | #define SHORT_SYMLINK_LEN 128 | |
81 | ||
82 | /* | |
83 | * shmem_fallocate and shmem_writepage communicate via inode->i_private | |
84 | * (with i_mutex making sure that it has only one user at a time): | |
85 | * we would prefer not to enlarge the shmem inode just for that. | |
86 | */ | |
87 | struct shmem_falloc { | |
88 | pgoff_t start; /* start of range currently being fallocated */ | |
89 | pgoff_t next; /* the next page offset to be fallocated */ | |
90 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ | |
91 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ | |
92 | }; | |
93 | ||
94 | /* Flag allocation requirements to shmem_getpage */ | |
95 | enum sgp_type { | |
96 | SGP_READ, /* don't exceed i_size, don't allocate page */ | |
97 | SGP_CACHE, /* don't exceed i_size, may allocate page */ | |
98 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ | |
99 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ | |
100 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ | |
101 | }; | |
102 | ||
103 | #ifdef CONFIG_TMPFS | |
104 | static unsigned long shmem_default_max_blocks(void) | |
105 | { | |
106 | return totalram_pages / 2; | |
107 | } | |
108 | ||
109 | static unsigned long shmem_default_max_inodes(void) | |
110 | { | |
111 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); | |
112 | } | |
113 | #endif | |
114 | ||
115 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); | |
116 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
117 | struct shmem_inode_info *info, pgoff_t index); | |
118 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
119 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); | |
120 | ||
121 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, | |
122 | struct page **pagep, enum sgp_type sgp, int *fault_type) | |
123 | { | |
124 | return shmem_getpage_gfp(inode, index, pagep, sgp, | |
125 | mapping_gfp_mask(inode->i_mapping), fault_type); | |
126 | } | |
127 | ||
128 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) | |
129 | { | |
130 | return sb->s_fs_info; | |
131 | } | |
132 | ||
133 | /* | |
134 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, | |
135 | * for shared memory and for shared anonymous (/dev/zero) mappings | |
136 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), | |
137 | * consistent with the pre-accounting of private mappings ... | |
138 | */ | |
139 | static inline int shmem_acct_size(unsigned long flags, loff_t size) | |
140 | { | |
141 | return (flags & VM_NORESERVE) ? | |
142 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); | |
143 | } | |
144 | ||
145 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) | |
146 | { | |
147 | if (!(flags & VM_NORESERVE)) | |
148 | vm_unacct_memory(VM_ACCT(size)); | |
149 | } | |
150 | ||
151 | /* | |
152 | * ... whereas tmpfs objects are accounted incrementally as | |
153 | * pages are allocated, in order to allow huge sparse files. | |
154 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, | |
155 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. | |
156 | */ | |
157 | static inline int shmem_acct_block(unsigned long flags) | |
158 | { | |
159 | return (flags & VM_NORESERVE) ? | |
160 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; | |
161 | } | |
162 | ||
163 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) | |
164 | { | |
165 | if (flags & VM_NORESERVE) | |
166 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); | |
167 | } | |
168 | ||
169 | static const struct super_operations shmem_ops; | |
170 | static const struct address_space_operations shmem_aops; | |
171 | static const struct file_operations shmem_file_operations; | |
172 | static const struct inode_operations shmem_inode_operations; | |
173 | static const struct inode_operations shmem_dir_inode_operations; | |
174 | static const struct inode_operations shmem_special_inode_operations; | |
175 | static const struct vm_operations_struct shmem_vm_ops; | |
176 | ||
177 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { | |
178 | .ra_pages = 0, /* No readahead */ | |
179 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, | |
180 | }; | |
181 | ||
182 | static LIST_HEAD(shmem_swaplist); | |
183 | static DEFINE_MUTEX(shmem_swaplist_mutex); | |
184 | ||
185 | static int shmem_reserve_inode(struct super_block *sb) | |
186 | { | |
187 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
188 | if (sbinfo->max_inodes) { | |
189 | spin_lock(&sbinfo->stat_lock); | |
190 | if (!sbinfo->free_inodes) { | |
191 | spin_unlock(&sbinfo->stat_lock); | |
192 | return -ENOSPC; | |
193 | } | |
194 | sbinfo->free_inodes--; | |
195 | spin_unlock(&sbinfo->stat_lock); | |
196 | } | |
197 | return 0; | |
198 | } | |
199 | ||
200 | static void shmem_free_inode(struct super_block *sb) | |
201 | { | |
202 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
203 | if (sbinfo->max_inodes) { | |
204 | spin_lock(&sbinfo->stat_lock); | |
205 | sbinfo->free_inodes++; | |
206 | spin_unlock(&sbinfo->stat_lock); | |
207 | } | |
208 | } | |
209 | ||
210 | /** | |
211 | * shmem_recalc_inode - recalculate the block usage of an inode | |
212 | * @inode: inode to recalc | |
213 | * | |
214 | * We have to calculate the free blocks since the mm can drop | |
215 | * undirtied hole pages behind our back. | |
216 | * | |
217 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped | |
218 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) | |
219 | * | |
220 | * It has to be called with the spinlock held. | |
221 | */ | |
222 | static void shmem_recalc_inode(struct inode *inode) | |
223 | { | |
224 | struct shmem_inode_info *info = SHMEM_I(inode); | |
225 | long freed; | |
226 | ||
227 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; | |
228 | if (freed > 0) { | |
229 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
230 | if (sbinfo->max_blocks) | |
231 | percpu_counter_add(&sbinfo->used_blocks, -freed); | |
232 | info->alloced -= freed; | |
233 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; | |
234 | shmem_unacct_blocks(info->flags, freed); | |
235 | } | |
236 | } | |
237 | ||
238 | /* | |
239 | * Replace item expected in radix tree by a new item, while holding tree lock. | |
240 | */ | |
241 | static int shmem_radix_tree_replace(struct address_space *mapping, | |
242 | pgoff_t index, void *expected, void *replacement) | |
243 | { | |
244 | void **pslot; | |
245 | void *item = NULL; | |
246 | ||
247 | VM_BUG_ON(!expected); | |
248 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); | |
249 | if (pslot) | |
250 | item = radix_tree_deref_slot_protected(pslot, | |
251 | &mapping->tree_lock); | |
252 | if (item != expected) | |
253 | return -ENOENT; | |
254 | if (replacement) | |
255 | radix_tree_replace_slot(pslot, replacement); | |
256 | else | |
257 | radix_tree_delete(&mapping->page_tree, index); | |
258 | return 0; | |
259 | } | |
260 | ||
261 | /* | |
262 | * Sometimes, before we decide whether to proceed or to fail, we must check | |
263 | * that an entry was not already brought back from swap by a racing thread. | |
264 | * | |
265 | * Checking page is not enough: by the time a SwapCache page is locked, it | |
266 | * might be reused, and again be SwapCache, using the same swap as before. | |
267 | */ | |
268 | static bool shmem_confirm_swap(struct address_space *mapping, | |
269 | pgoff_t index, swp_entry_t swap) | |
270 | { | |
271 | void *item; | |
272 | ||
273 | rcu_read_lock(); | |
274 | item = radix_tree_lookup(&mapping->page_tree, index); | |
275 | rcu_read_unlock(); | |
276 | return item == swp_to_radix_entry(swap); | |
277 | } | |
278 | ||
279 | /* | |
280 | * Like add_to_page_cache_locked, but error if expected item has gone. | |
281 | */ | |
282 | static int shmem_add_to_page_cache(struct page *page, | |
283 | struct address_space *mapping, | |
284 | pgoff_t index, gfp_t gfp, void *expected) | |
285 | { | |
286 | int error; | |
287 | ||
288 | VM_BUG_ON(!PageLocked(page)); | |
289 | VM_BUG_ON(!PageSwapBacked(page)); | |
290 | ||
291 | page_cache_get(page); | |
292 | page->mapping = mapping; | |
293 | page->index = index; | |
294 | ||
295 | spin_lock_irq(&mapping->tree_lock); | |
296 | if (!expected) | |
297 | error = radix_tree_insert(&mapping->page_tree, index, page); | |
298 | else | |
299 | error = shmem_radix_tree_replace(mapping, index, expected, | |
300 | page); | |
301 | if (!error) { | |
302 | mapping->nrpages++; | |
303 | __inc_zone_page_state(page, NR_FILE_PAGES); | |
304 | __inc_zone_page_state(page, NR_SHMEM); | |
305 | spin_unlock_irq(&mapping->tree_lock); | |
306 | } else { | |
307 | page->mapping = NULL; | |
308 | spin_unlock_irq(&mapping->tree_lock); | |
309 | page_cache_release(page); | |
310 | } | |
311 | return error; | |
312 | } | |
313 | ||
314 | /* | |
315 | * Like delete_from_page_cache, but substitutes swap for page. | |
316 | */ | |
317 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) | |
318 | { | |
319 | struct address_space *mapping = page->mapping; | |
320 | int error; | |
321 | ||
322 | spin_lock_irq(&mapping->tree_lock); | |
323 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); | |
324 | page->mapping = NULL; | |
325 | mapping->nrpages--; | |
326 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
327 | __dec_zone_page_state(page, NR_SHMEM); | |
328 | spin_unlock_irq(&mapping->tree_lock); | |
329 | page_cache_release(page); | |
330 | BUG_ON(error); | |
331 | } | |
332 | ||
333 | /* | |
334 | * Like find_get_pages, but collecting swap entries as well as pages. | |
335 | */ | |
336 | static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, | |
337 | pgoff_t start, unsigned int nr_pages, | |
338 | struct page **pages, pgoff_t *indices) | |
339 | { | |
340 | void **slot; | |
341 | unsigned int ret = 0; | |
342 | struct radix_tree_iter iter; | |
343 | ||
344 | if (!nr_pages) | |
345 | return 0; | |
346 | ||
347 | rcu_read_lock(); | |
348 | restart: | |
349 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
350 | struct page *page; | |
351 | repeat: | |
352 | page = radix_tree_deref_slot(slot); | |
353 | if (unlikely(!page)) | |
354 | continue; | |
355 | if (radix_tree_exception(page)) { | |
356 | if (radix_tree_deref_retry(page)) | |
357 | goto restart; | |
358 | /* | |
359 | * Otherwise, we must be storing a swap entry | |
360 | * here as an exceptional entry: so return it | |
361 | * without attempting to raise page count. | |
362 | */ | |
363 | goto export; | |
364 | } | |
365 | if (!page_cache_get_speculative(page)) | |
366 | goto repeat; | |
367 | ||
368 | /* Has the page moved? */ | |
369 | if (unlikely(page != *slot)) { | |
370 | page_cache_release(page); | |
371 | goto repeat; | |
372 | } | |
373 | export: | |
374 | indices[ret] = iter.index; | |
375 | pages[ret] = page; | |
376 | if (++ret == nr_pages) | |
377 | break; | |
378 | } | |
379 | rcu_read_unlock(); | |
380 | return ret; | |
381 | } | |
382 | ||
383 | /* | |
384 | * Remove swap entry from radix tree, free the swap and its page cache. | |
385 | */ | |
386 | static int shmem_free_swap(struct address_space *mapping, | |
387 | pgoff_t index, void *radswap) | |
388 | { | |
389 | int error; | |
390 | ||
391 | spin_lock_irq(&mapping->tree_lock); | |
392 | error = shmem_radix_tree_replace(mapping, index, radswap, NULL); | |
393 | spin_unlock_irq(&mapping->tree_lock); | |
394 | if (!error) | |
395 | free_swap_and_cache(radix_to_swp_entry(radswap)); | |
396 | return error; | |
397 | } | |
398 | ||
399 | /* | |
400 | * Pagevec may contain swap entries, so shuffle up pages before releasing. | |
401 | */ | |
402 | static void shmem_deswap_pagevec(struct pagevec *pvec) | |
403 | { | |
404 | int i, j; | |
405 | ||
406 | for (i = 0, j = 0; i < pagevec_count(pvec); i++) { | |
407 | struct page *page = pvec->pages[i]; | |
408 | if (!radix_tree_exceptional_entry(page)) | |
409 | pvec->pages[j++] = page; | |
410 | } | |
411 | pvec->nr = j; | |
412 | } | |
413 | ||
414 | /* | |
415 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. | |
416 | */ | |
417 | void shmem_unlock_mapping(struct address_space *mapping) | |
418 | { | |
419 | struct pagevec pvec; | |
420 | pgoff_t indices[PAGEVEC_SIZE]; | |
421 | pgoff_t index = 0; | |
422 | ||
423 | pagevec_init(&pvec, 0); | |
424 | /* | |
425 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. | |
426 | */ | |
427 | while (!mapping_unevictable(mapping)) { | |
428 | /* | |
429 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it | |
430 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. | |
431 | */ | |
432 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
433 | PAGEVEC_SIZE, pvec.pages, indices); | |
434 | if (!pvec.nr) | |
435 | break; | |
436 | index = indices[pvec.nr - 1] + 1; | |
437 | shmem_deswap_pagevec(&pvec); | |
438 | check_move_unevictable_pages(pvec.pages, pvec.nr); | |
439 | pagevec_release(&pvec); | |
440 | cond_resched(); | |
441 | } | |
442 | } | |
443 | ||
444 | /* | |
445 | * Remove range of pages and swap entries from radix tree, and free them. | |
446 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. | |
447 | */ | |
448 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, | |
449 | bool unfalloc) | |
450 | { | |
451 | struct address_space *mapping = inode->i_mapping; | |
452 | struct shmem_inode_info *info = SHMEM_I(inode); | |
453 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
454 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; | |
455 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); | |
456 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); | |
457 | struct pagevec pvec; | |
458 | pgoff_t indices[PAGEVEC_SIZE]; | |
459 | long nr_swaps_freed = 0; | |
460 | pgoff_t index; | |
461 | int i; | |
462 | ||
463 | if (lend == -1) | |
464 | end = -1; /* unsigned, so actually very big */ | |
465 | ||
466 | pagevec_init(&pvec, 0); | |
467 | index = start; | |
468 | while (index < end) { | |
469 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
470 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
471 | pvec.pages, indices); | |
472 | if (!pvec.nr) | |
473 | break; | |
474 | mem_cgroup_uncharge_start(); | |
475 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
476 | struct page *page = pvec.pages[i]; | |
477 | ||
478 | index = indices[i]; | |
479 | if (index >= end) | |
480 | break; | |
481 | ||
482 | if (radix_tree_exceptional_entry(page)) { | |
483 | if (unfalloc) | |
484 | continue; | |
485 | nr_swaps_freed += !shmem_free_swap(mapping, | |
486 | index, page); | |
487 | continue; | |
488 | } | |
489 | ||
490 | if (!trylock_page(page)) | |
491 | continue; | |
492 | if (!unfalloc || !PageUptodate(page)) { | |
493 | if (page->mapping == mapping) { | |
494 | VM_BUG_ON(PageWriteback(page)); | |
495 | truncate_inode_page(mapping, page); | |
496 | } | |
497 | } | |
498 | unlock_page(page); | |
499 | } | |
500 | shmem_deswap_pagevec(&pvec); | |
501 | pagevec_release(&pvec); | |
502 | mem_cgroup_uncharge_end(); | |
503 | cond_resched(); | |
504 | index++; | |
505 | } | |
506 | ||
507 | if (partial_start) { | |
508 | struct page *page = NULL; | |
509 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); | |
510 | if (page) { | |
511 | unsigned int top = PAGE_CACHE_SIZE; | |
512 | if (start > end) { | |
513 | top = partial_end; | |
514 | partial_end = 0; | |
515 | } | |
516 | zero_user_segment(page, partial_start, top); | |
517 | set_page_dirty(page); | |
518 | unlock_page(page); | |
519 | page_cache_release(page); | |
520 | } | |
521 | } | |
522 | if (partial_end) { | |
523 | struct page *page = NULL; | |
524 | shmem_getpage(inode, end, &page, SGP_READ, NULL); | |
525 | if (page) { | |
526 | zero_user_segment(page, 0, partial_end); | |
527 | set_page_dirty(page); | |
528 | unlock_page(page); | |
529 | page_cache_release(page); | |
530 | } | |
531 | } | |
532 | if (start >= end) | |
533 | return; | |
534 | ||
535 | index = start; | |
536 | for ( ; ; ) { | |
537 | cond_resched(); | |
538 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
539 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
540 | pvec.pages, indices); | |
541 | if (!pvec.nr) { | |
542 | if (index == start || unfalloc) | |
543 | break; | |
544 | index = start; | |
545 | continue; | |
546 | } | |
547 | if ((index == start || unfalloc) && indices[0] >= end) { | |
548 | shmem_deswap_pagevec(&pvec); | |
549 | pagevec_release(&pvec); | |
550 | break; | |
551 | } | |
552 | mem_cgroup_uncharge_start(); | |
553 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
554 | struct page *page = pvec.pages[i]; | |
555 | ||
556 | index = indices[i]; | |
557 | if (index >= end) | |
558 | break; | |
559 | ||
560 | if (radix_tree_exceptional_entry(page)) { | |
561 | if (unfalloc) | |
562 | continue; | |
563 | nr_swaps_freed += !shmem_free_swap(mapping, | |
564 | index, page); | |
565 | continue; | |
566 | } | |
567 | ||
568 | lock_page(page); | |
569 | if (!unfalloc || !PageUptodate(page)) { | |
570 | if (page->mapping == mapping) { | |
571 | VM_BUG_ON(PageWriteback(page)); | |
572 | truncate_inode_page(mapping, page); | |
573 | } | |
574 | } | |
575 | unlock_page(page); | |
576 | } | |
577 | shmem_deswap_pagevec(&pvec); | |
578 | pagevec_release(&pvec); | |
579 | mem_cgroup_uncharge_end(); | |
580 | index++; | |
581 | } | |
582 | ||
583 | spin_lock(&info->lock); | |
584 | info->swapped -= nr_swaps_freed; | |
585 | shmem_recalc_inode(inode); | |
586 | spin_unlock(&info->lock); | |
587 | } | |
588 | ||
589 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
590 | { | |
591 | shmem_undo_range(inode, lstart, lend, false); | |
592 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
593 | } | |
594 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
595 | ||
596 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) | |
597 | { | |
598 | struct inode *inode = dentry->d_inode; | |
599 | int error; | |
600 | ||
601 | error = inode_change_ok(inode, attr); | |
602 | if (error) | |
603 | return error; | |
604 | ||
605 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { | |
606 | loff_t oldsize = inode->i_size; | |
607 | loff_t newsize = attr->ia_size; | |
608 | ||
609 | if (newsize != oldsize) { | |
610 | i_size_write(inode, newsize); | |
611 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
612 | } | |
613 | if (newsize < oldsize) { | |
614 | loff_t holebegin = round_up(newsize, PAGE_SIZE); | |
615 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
616 | shmem_truncate_range(inode, newsize, (loff_t)-1); | |
617 | /* unmap again to remove racily COWed private pages */ | |
618 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
619 | } | |
620 | } | |
621 | ||
622 | setattr_copy(inode, attr); | |
623 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
624 | if (attr->ia_valid & ATTR_MODE) | |
625 | error = generic_acl_chmod(inode); | |
626 | #endif | |
627 | return error; | |
628 | } | |
629 | ||
630 | static void shmem_evict_inode(struct inode *inode) | |
631 | { | |
632 | struct shmem_inode_info *info = SHMEM_I(inode); | |
633 | ||
634 | if (inode->i_mapping->a_ops == &shmem_aops) { | |
635 | shmem_unacct_size(info->flags, inode->i_size); | |
636 | inode->i_size = 0; | |
637 | shmem_truncate_range(inode, 0, (loff_t)-1); | |
638 | if (!list_empty(&info->swaplist)) { | |
639 | mutex_lock(&shmem_swaplist_mutex); | |
640 | list_del_init(&info->swaplist); | |
641 | mutex_unlock(&shmem_swaplist_mutex); | |
642 | } | |
643 | } else | |
644 | kfree(info->symlink); | |
645 | ||
646 | simple_xattrs_free(&info->xattrs); | |
647 | WARN_ON(inode->i_blocks); | |
648 | shmem_free_inode(inode->i_sb); | |
649 | clear_inode(inode); | |
650 | } | |
651 | ||
652 | /* | |
653 | * If swap found in inode, free it and move page from swapcache to filecache. | |
654 | */ | |
655 | static int shmem_unuse_inode(struct shmem_inode_info *info, | |
656 | swp_entry_t swap, struct page **pagep) | |
657 | { | |
658 | struct address_space *mapping = info->vfs_inode.i_mapping; | |
659 | void *radswap; | |
660 | pgoff_t index; | |
661 | gfp_t gfp; | |
662 | int error = 0; | |
663 | ||
664 | radswap = swp_to_radix_entry(swap); | |
665 | index = radix_tree_locate_item(&mapping->page_tree, radswap); | |
666 | if (index == -1) | |
667 | return 0; | |
668 | ||
669 | /* | |
670 | * Move _head_ to start search for next from here. | |
671 | * But be careful: shmem_evict_inode checks list_empty without taking | |
672 | * mutex, and there's an instant in list_move_tail when info->swaplist | |
673 | * would appear empty, if it were the only one on shmem_swaplist. | |
674 | */ | |
675 | if (shmem_swaplist.next != &info->swaplist) | |
676 | list_move_tail(&shmem_swaplist, &info->swaplist); | |
677 | ||
678 | gfp = mapping_gfp_mask(mapping); | |
679 | if (shmem_should_replace_page(*pagep, gfp)) { | |
680 | mutex_unlock(&shmem_swaplist_mutex); | |
681 | error = shmem_replace_page(pagep, gfp, info, index); | |
682 | mutex_lock(&shmem_swaplist_mutex); | |
683 | /* | |
684 | * We needed to drop mutex to make that restrictive page | |
685 | * allocation, but the inode might have been freed while we | |
686 | * dropped it: although a racing shmem_evict_inode() cannot | |
687 | * complete without emptying the radix_tree, our page lock | |
688 | * on this swapcache page is not enough to prevent that - | |
689 | * free_swap_and_cache() of our swap entry will only | |
690 | * trylock_page(), removing swap from radix_tree whatever. | |
691 | * | |
692 | * We must not proceed to shmem_add_to_page_cache() if the | |
693 | * inode has been freed, but of course we cannot rely on | |
694 | * inode or mapping or info to check that. However, we can | |
695 | * safely check if our swap entry is still in use (and here | |
696 | * it can't have got reused for another page): if it's still | |
697 | * in use, then the inode cannot have been freed yet, and we | |
698 | * can safely proceed (if it's no longer in use, that tells | |
699 | * nothing about the inode, but we don't need to unuse swap). | |
700 | */ | |
701 | if (!page_swapcount(*pagep)) | |
702 | error = -ENOENT; | |
703 | } | |
704 | ||
705 | /* | |
706 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, | |
707 | * but also to hold up shmem_evict_inode(): so inode cannot be freed | |
708 | * beneath us (pagelock doesn't help until the page is in pagecache). | |
709 | */ | |
710 | if (!error) | |
711 | error = shmem_add_to_page_cache(*pagep, mapping, index, | |
712 | GFP_NOWAIT, radswap); | |
713 | if (error != -ENOMEM) { | |
714 | /* | |
715 | * Truncation and eviction use free_swap_and_cache(), which | |
716 | * only does trylock page: if we raced, best clean up here. | |
717 | */ | |
718 | delete_from_swap_cache(*pagep); | |
719 | set_page_dirty(*pagep); | |
720 | if (!error) { | |
721 | spin_lock(&info->lock); | |
722 | info->swapped--; | |
723 | spin_unlock(&info->lock); | |
724 | swap_free(swap); | |
725 | } | |
726 | error = 1; /* not an error, but entry was found */ | |
727 | } | |
728 | return error; | |
729 | } | |
730 | ||
731 | /* | |
732 | * Search through swapped inodes to find and replace swap by page. | |
733 | */ | |
734 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
735 | { | |
736 | struct list_head *this, *next; | |
737 | struct shmem_inode_info *info; | |
738 | int found = 0; | |
739 | int error = 0; | |
740 | ||
741 | /* | |
742 | * There's a faint possibility that swap page was replaced before | |
743 | * caller locked it: caller will come back later with the right page. | |
744 | */ | |
745 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) | |
746 | goto out; | |
747 | ||
748 | /* | |
749 | * Charge page using GFP_KERNEL while we can wait, before taking | |
750 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). | |
751 | * Charged back to the user (not to caller) when swap account is used. | |
752 | */ | |
753 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); | |
754 | if (error) | |
755 | goto out; | |
756 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ | |
757 | ||
758 | mutex_lock(&shmem_swaplist_mutex); | |
759 | list_for_each_safe(this, next, &shmem_swaplist) { | |
760 | info = list_entry(this, struct shmem_inode_info, swaplist); | |
761 | if (info->swapped) | |
762 | found = shmem_unuse_inode(info, swap, &page); | |
763 | else | |
764 | list_del_init(&info->swaplist); | |
765 | cond_resched(); | |
766 | if (found) | |
767 | break; | |
768 | } | |
769 | mutex_unlock(&shmem_swaplist_mutex); | |
770 | ||
771 | if (found < 0) | |
772 | error = found; | |
773 | out: | |
774 | unlock_page(page); | |
775 | page_cache_release(page); | |
776 | return error; | |
777 | } | |
778 | ||
779 | /* | |
780 | * Move the page from the page cache to the swap cache. | |
781 | */ | |
782 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) | |
783 | { | |
784 | struct shmem_inode_info *info; | |
785 | struct address_space *mapping; | |
786 | struct inode *inode; | |
787 | swp_entry_t swap; | |
788 | pgoff_t index; | |
789 | ||
790 | BUG_ON(!PageLocked(page)); | |
791 | mapping = page->mapping; | |
792 | index = page->index; | |
793 | inode = mapping->host; | |
794 | info = SHMEM_I(inode); | |
795 | if (info->flags & VM_LOCKED) | |
796 | goto redirty; | |
797 | if (!total_swap_pages) | |
798 | goto redirty; | |
799 | ||
800 | /* | |
801 | * shmem_backing_dev_info's capabilities prevent regular writeback or | |
802 | * sync from ever calling shmem_writepage; but a stacking filesystem | |
803 | * might use ->writepage of its underlying filesystem, in which case | |
804 | * tmpfs should write out to swap only in response to memory pressure, | |
805 | * and not for the writeback threads or sync. | |
806 | */ | |
807 | if (!wbc->for_reclaim) { | |
808 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ | |
809 | goto redirty; | |
810 | } | |
811 | ||
812 | /* | |
813 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC | |
814 | * value into swapfile.c, the only way we can correctly account for a | |
815 | * fallocated page arriving here is now to initialize it and write it. | |
816 | * | |
817 | * That's okay for a page already fallocated earlier, but if we have | |
818 | * not yet completed the fallocation, then (a) we want to keep track | |
819 | * of this page in case we have to undo it, and (b) it may not be a | |
820 | * good idea to continue anyway, once we're pushing into swap. So | |
821 | * reactivate the page, and let shmem_fallocate() quit when too many. | |
822 | */ | |
823 | if (!PageUptodate(page)) { | |
824 | if (inode->i_private) { | |
825 | struct shmem_falloc *shmem_falloc; | |
826 | spin_lock(&inode->i_lock); | |
827 | shmem_falloc = inode->i_private; | |
828 | if (shmem_falloc && | |
829 | index >= shmem_falloc->start && | |
830 | index < shmem_falloc->next) | |
831 | shmem_falloc->nr_unswapped++; | |
832 | else | |
833 | shmem_falloc = NULL; | |
834 | spin_unlock(&inode->i_lock); | |
835 | if (shmem_falloc) | |
836 | goto redirty; | |
837 | } | |
838 | clear_highpage(page); | |
839 | flush_dcache_page(page); | |
840 | SetPageUptodate(page); | |
841 | } | |
842 | ||
843 | swap = get_swap_page(); | |
844 | if (!swap.val) | |
845 | goto redirty; | |
846 | ||
847 | /* | |
848 | * Add inode to shmem_unuse()'s list of swapped-out inodes, | |
849 | * if it's not already there. Do it now before the page is | |
850 | * moved to swap cache, when its pagelock no longer protects | |
851 | * the inode from eviction. But don't unlock the mutex until | |
852 | * we've incremented swapped, because shmem_unuse_inode() will | |
853 | * prune a !swapped inode from the swaplist under this mutex. | |
854 | */ | |
855 | mutex_lock(&shmem_swaplist_mutex); | |
856 | if (list_empty(&info->swaplist)) | |
857 | list_add_tail(&info->swaplist, &shmem_swaplist); | |
858 | ||
859 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { | |
860 | swap_shmem_alloc(swap); | |
861 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); | |
862 | ||
863 | spin_lock(&info->lock); | |
864 | info->swapped++; | |
865 | shmem_recalc_inode(inode); | |
866 | spin_unlock(&info->lock); | |
867 | ||
868 | mutex_unlock(&shmem_swaplist_mutex); | |
869 | BUG_ON(page_mapped(page)); | |
870 | swap_writepage(page, wbc); | |
871 | return 0; | |
872 | } | |
873 | ||
874 | mutex_unlock(&shmem_swaplist_mutex); | |
875 | swapcache_free(swap, NULL); | |
876 | redirty: | |
877 | set_page_dirty(page); | |
878 | if (wbc->for_reclaim) | |
879 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ | |
880 | unlock_page(page); | |
881 | return 0; | |
882 | } | |
883 | ||
884 | #ifdef CONFIG_NUMA | |
885 | #ifdef CONFIG_TMPFS | |
886 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
887 | { | |
888 | char buffer[64]; | |
889 | ||
890 | if (!mpol || mpol->mode == MPOL_DEFAULT) | |
891 | return; /* show nothing */ | |
892 | ||
893 | mpol_to_str(buffer, sizeof(buffer), mpol); | |
894 | ||
895 | seq_printf(seq, ",mpol=%s", buffer); | |
896 | } | |
897 | ||
898 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
899 | { | |
900 | struct mempolicy *mpol = NULL; | |
901 | if (sbinfo->mpol) { | |
902 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ | |
903 | mpol = sbinfo->mpol; | |
904 | mpol_get(mpol); | |
905 | spin_unlock(&sbinfo->stat_lock); | |
906 | } | |
907 | return mpol; | |
908 | } | |
909 | #endif /* CONFIG_TMPFS */ | |
910 | ||
911 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
912 | struct shmem_inode_info *info, pgoff_t index) | |
913 | { | |
914 | struct vm_area_struct pvma; | |
915 | struct page *page; | |
916 | ||
917 | /* Create a pseudo vma that just contains the policy */ | |
918 | pvma.vm_start = 0; | |
919 | /* Bias interleave by inode number to distribute better across nodes */ | |
920 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
921 | pvma.vm_ops = NULL; | |
922 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
923 | ||
924 | page = swapin_readahead(swap, gfp, &pvma, 0); | |
925 | ||
926 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
927 | mpol_cond_put(pvma.vm_policy); | |
928 | ||
929 | return page; | |
930 | } | |
931 | ||
932 | static struct page *shmem_alloc_page(gfp_t gfp, | |
933 | struct shmem_inode_info *info, pgoff_t index) | |
934 | { | |
935 | struct vm_area_struct pvma; | |
936 | struct page *page; | |
937 | ||
938 | /* Create a pseudo vma that just contains the policy */ | |
939 | pvma.vm_start = 0; | |
940 | /* Bias interleave by inode number to distribute better across nodes */ | |
941 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
942 | pvma.vm_ops = NULL; | |
943 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
944 | ||
945 | page = alloc_page_vma(gfp, &pvma, 0); | |
946 | ||
947 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
948 | mpol_cond_put(pvma.vm_policy); | |
949 | ||
950 | return page; | |
951 | } | |
952 | #else /* !CONFIG_NUMA */ | |
953 | #ifdef CONFIG_TMPFS | |
954 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
955 | { | |
956 | } | |
957 | #endif /* CONFIG_TMPFS */ | |
958 | ||
959 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
960 | struct shmem_inode_info *info, pgoff_t index) | |
961 | { | |
962 | return swapin_readahead(swap, gfp, NULL, 0); | |
963 | } | |
964 | ||
965 | static inline struct page *shmem_alloc_page(gfp_t gfp, | |
966 | struct shmem_inode_info *info, pgoff_t index) | |
967 | { | |
968 | return alloc_page(gfp); | |
969 | } | |
970 | #endif /* CONFIG_NUMA */ | |
971 | ||
972 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) | |
973 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
974 | { | |
975 | return NULL; | |
976 | } | |
977 | #endif | |
978 | ||
979 | /* | |
980 | * When a page is moved from swapcache to shmem filecache (either by the | |
981 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of | |
982 | * shmem_unuse_inode()), it may have been read in earlier from swap, in | |
983 | * ignorance of the mapping it belongs to. If that mapping has special | |
984 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), | |
985 | * we may need to copy to a suitable page before moving to filecache. | |
986 | * | |
987 | * In a future release, this may well be extended to respect cpuset and | |
988 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); | |
989 | * but for now it is a simple matter of zone. | |
990 | */ | |
991 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) | |
992 | { | |
993 | return page_zonenum(page) > gfp_zone(gfp); | |
994 | } | |
995 | ||
996 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
997 | struct shmem_inode_info *info, pgoff_t index) | |
998 | { | |
999 | struct page *oldpage, *newpage; | |
1000 | struct address_space *swap_mapping; | |
1001 | pgoff_t swap_index; | |
1002 | int error; | |
1003 | ||
1004 | oldpage = *pagep; | |
1005 | swap_index = page_private(oldpage); | |
1006 | swap_mapping = page_mapping(oldpage); | |
1007 | ||
1008 | /* | |
1009 | * We have arrived here because our zones are constrained, so don't | |
1010 | * limit chance of success by further cpuset and node constraints. | |
1011 | */ | |
1012 | gfp &= ~GFP_CONSTRAINT_MASK; | |
1013 | newpage = shmem_alloc_page(gfp, info, index); | |
1014 | if (!newpage) | |
1015 | return -ENOMEM; | |
1016 | ||
1017 | page_cache_get(newpage); | |
1018 | copy_highpage(newpage, oldpage); | |
1019 | flush_dcache_page(newpage); | |
1020 | ||
1021 | __set_page_locked(newpage); | |
1022 | SetPageUptodate(newpage); | |
1023 | SetPageSwapBacked(newpage); | |
1024 | set_page_private(newpage, swap_index); | |
1025 | SetPageSwapCache(newpage); | |
1026 | ||
1027 | /* | |
1028 | * Our caller will very soon move newpage out of swapcache, but it's | |
1029 | * a nice clean interface for us to replace oldpage by newpage there. | |
1030 | */ | |
1031 | spin_lock_irq(&swap_mapping->tree_lock); | |
1032 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, | |
1033 | newpage); | |
1034 | if (!error) { | |
1035 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
1036 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); | |
1037 | } | |
1038 | spin_unlock_irq(&swap_mapping->tree_lock); | |
1039 | ||
1040 | if (unlikely(error)) { | |
1041 | /* | |
1042 | * Is this possible? I think not, now that our callers check | |
1043 | * both PageSwapCache and page_private after getting page lock; | |
1044 | * but be defensive. Reverse old to newpage for clear and free. | |
1045 | */ | |
1046 | oldpage = newpage; | |
1047 | } else { | |
1048 | mem_cgroup_replace_page_cache(oldpage, newpage); | |
1049 | lru_cache_add_anon(newpage); | |
1050 | *pagep = newpage; | |
1051 | } | |
1052 | ||
1053 | ClearPageSwapCache(oldpage); | |
1054 | set_page_private(oldpage, 0); | |
1055 | ||
1056 | unlock_page(oldpage); | |
1057 | page_cache_release(oldpage); | |
1058 | page_cache_release(oldpage); | |
1059 | return error; | |
1060 | } | |
1061 | ||
1062 | /* | |
1063 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate | |
1064 | * | |
1065 | * If we allocate a new one we do not mark it dirty. That's up to the | |
1066 | * vm. If we swap it in we mark it dirty since we also free the swap | |
1067 | * entry since a page cannot live in both the swap and page cache | |
1068 | */ | |
1069 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
1070 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) | |
1071 | { | |
1072 | struct address_space *mapping = inode->i_mapping; | |
1073 | struct shmem_inode_info *info; | |
1074 | struct shmem_sb_info *sbinfo; | |
1075 | struct page *page; | |
1076 | swp_entry_t swap; | |
1077 | int error; | |
1078 | int once = 0; | |
1079 | int alloced = 0; | |
1080 | ||
1081 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) | |
1082 | return -EFBIG; | |
1083 | repeat: | |
1084 | swap.val = 0; | |
1085 | page = find_lock_page(mapping, index); | |
1086 | if (radix_tree_exceptional_entry(page)) { | |
1087 | swap = radix_to_swp_entry(page); | |
1088 | page = NULL; | |
1089 | } | |
1090 | ||
1091 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1092 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1093 | error = -EINVAL; | |
1094 | goto failed; | |
1095 | } | |
1096 | ||
1097 | /* fallocated page? */ | |
1098 | if (page && !PageUptodate(page)) { | |
1099 | if (sgp != SGP_READ) | |
1100 | goto clear; | |
1101 | unlock_page(page); | |
1102 | page_cache_release(page); | |
1103 | page = NULL; | |
1104 | } | |
1105 | if (page || (sgp == SGP_READ && !swap.val)) { | |
1106 | *pagep = page; | |
1107 | return 0; | |
1108 | } | |
1109 | ||
1110 | /* | |
1111 | * Fast cache lookup did not find it: | |
1112 | * bring it back from swap or allocate. | |
1113 | */ | |
1114 | info = SHMEM_I(inode); | |
1115 | sbinfo = SHMEM_SB(inode->i_sb); | |
1116 | ||
1117 | if (swap.val) { | |
1118 | /* Look it up and read it in.. */ | |
1119 | page = lookup_swap_cache(swap); | |
1120 | if (!page) { | |
1121 | /* here we actually do the io */ | |
1122 | if (fault_type) | |
1123 | *fault_type |= VM_FAULT_MAJOR; | |
1124 | page = shmem_swapin(swap, gfp, info, index); | |
1125 | if (!page) { | |
1126 | error = -ENOMEM; | |
1127 | goto failed; | |
1128 | } | |
1129 | } | |
1130 | ||
1131 | /* We have to do this with page locked to prevent races */ | |
1132 | lock_page(page); | |
1133 | if (!PageSwapCache(page) || page_private(page) != swap.val || | |
1134 | !shmem_confirm_swap(mapping, index, swap)) { | |
1135 | error = -EEXIST; /* try again */ | |
1136 | goto unlock; | |
1137 | } | |
1138 | if (!PageUptodate(page)) { | |
1139 | error = -EIO; | |
1140 | goto failed; | |
1141 | } | |
1142 | wait_on_page_writeback(page); | |
1143 | ||
1144 | if (shmem_should_replace_page(page, gfp)) { | |
1145 | error = shmem_replace_page(&page, gfp, info, index); | |
1146 | if (error) | |
1147 | goto failed; | |
1148 | } | |
1149 | ||
1150 | error = mem_cgroup_cache_charge(page, current->mm, | |
1151 | gfp & GFP_RECLAIM_MASK); | |
1152 | if (!error) { | |
1153 | error = shmem_add_to_page_cache(page, mapping, index, | |
1154 | gfp, swp_to_radix_entry(swap)); | |
1155 | /* | |
1156 | * We already confirmed swap under page lock, and make | |
1157 | * no memory allocation here, so usually no possibility | |
1158 | * of error; but free_swap_and_cache() only trylocks a | |
1159 | * page, so it is just possible that the entry has been | |
1160 | * truncated or holepunched since swap was confirmed. | |
1161 | * shmem_undo_range() will have done some of the | |
1162 | * unaccounting, now delete_from_swap_cache() will do | |
1163 | * the rest (including mem_cgroup_uncharge_swapcache). | |
1164 | * Reset swap.val? No, leave it so "failed" goes back to | |
1165 | * "repeat": reading a hole and writing should succeed. | |
1166 | */ | |
1167 | if (error) | |
1168 | delete_from_swap_cache(page); | |
1169 | } | |
1170 | if (error) | |
1171 | goto failed; | |
1172 | ||
1173 | spin_lock(&info->lock); | |
1174 | info->swapped--; | |
1175 | shmem_recalc_inode(inode); | |
1176 | spin_unlock(&info->lock); | |
1177 | ||
1178 | delete_from_swap_cache(page); | |
1179 | set_page_dirty(page); | |
1180 | swap_free(swap); | |
1181 | ||
1182 | } else { | |
1183 | if (shmem_acct_block(info->flags)) { | |
1184 | error = -ENOSPC; | |
1185 | goto failed; | |
1186 | } | |
1187 | if (sbinfo->max_blocks) { | |
1188 | if (percpu_counter_compare(&sbinfo->used_blocks, | |
1189 | sbinfo->max_blocks) >= 0) { | |
1190 | error = -ENOSPC; | |
1191 | goto unacct; | |
1192 | } | |
1193 | percpu_counter_inc(&sbinfo->used_blocks); | |
1194 | } | |
1195 | ||
1196 | page = shmem_alloc_page(gfp, info, index); | |
1197 | if (!page) { | |
1198 | error = -ENOMEM; | |
1199 | goto decused; | |
1200 | } | |
1201 | ||
1202 | SetPageSwapBacked(page); | |
1203 | __set_page_locked(page); | |
1204 | error = mem_cgroup_cache_charge(page, current->mm, | |
1205 | gfp & GFP_RECLAIM_MASK); | |
1206 | if (error) | |
1207 | goto decused; | |
1208 | error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK); | |
1209 | if (!error) { | |
1210 | error = shmem_add_to_page_cache(page, mapping, index, | |
1211 | gfp, NULL); | |
1212 | radix_tree_preload_end(); | |
1213 | } | |
1214 | if (error) { | |
1215 | mem_cgroup_uncharge_cache_page(page); | |
1216 | goto decused; | |
1217 | } | |
1218 | lru_cache_add_anon(page); | |
1219 | ||
1220 | spin_lock(&info->lock); | |
1221 | info->alloced++; | |
1222 | inode->i_blocks += BLOCKS_PER_PAGE; | |
1223 | shmem_recalc_inode(inode); | |
1224 | spin_unlock(&info->lock); | |
1225 | alloced = true; | |
1226 | ||
1227 | /* | |
1228 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. | |
1229 | */ | |
1230 | if (sgp == SGP_FALLOC) | |
1231 | sgp = SGP_WRITE; | |
1232 | clear: | |
1233 | /* | |
1234 | * Let SGP_WRITE caller clear ends if write does not fill page; | |
1235 | * but SGP_FALLOC on a page fallocated earlier must initialize | |
1236 | * it now, lest undo on failure cancel our earlier guarantee. | |
1237 | */ | |
1238 | if (sgp != SGP_WRITE) { | |
1239 | clear_highpage(page); | |
1240 | flush_dcache_page(page); | |
1241 | SetPageUptodate(page); | |
1242 | } | |
1243 | if (sgp == SGP_DIRTY) | |
1244 | set_page_dirty(page); | |
1245 | } | |
1246 | ||
1247 | /* Perhaps the file has been truncated since we checked */ | |
1248 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1249 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1250 | error = -EINVAL; | |
1251 | if (alloced) | |
1252 | goto trunc; | |
1253 | else | |
1254 | goto failed; | |
1255 | } | |
1256 | *pagep = page; | |
1257 | return 0; | |
1258 | ||
1259 | /* | |
1260 | * Error recovery. | |
1261 | */ | |
1262 | trunc: | |
1263 | info = SHMEM_I(inode); | |
1264 | ClearPageDirty(page); | |
1265 | delete_from_page_cache(page); | |
1266 | spin_lock(&info->lock); | |
1267 | info->alloced--; | |
1268 | inode->i_blocks -= BLOCKS_PER_PAGE; | |
1269 | spin_unlock(&info->lock); | |
1270 | decused: | |
1271 | sbinfo = SHMEM_SB(inode->i_sb); | |
1272 | if (sbinfo->max_blocks) | |
1273 | percpu_counter_add(&sbinfo->used_blocks, -1); | |
1274 | unacct: | |
1275 | shmem_unacct_blocks(info->flags, 1); | |
1276 | failed: | |
1277 | if (swap.val && error != -EINVAL && | |
1278 | !shmem_confirm_swap(mapping, index, swap)) | |
1279 | error = -EEXIST; | |
1280 | unlock: | |
1281 | if (page) { | |
1282 | unlock_page(page); | |
1283 | page_cache_release(page); | |
1284 | } | |
1285 | if (error == -ENOSPC && !once++) { | |
1286 | info = SHMEM_I(inode); | |
1287 | spin_lock(&info->lock); | |
1288 | shmem_recalc_inode(inode); | |
1289 | spin_unlock(&info->lock); | |
1290 | goto repeat; | |
1291 | } | |
1292 | if (error == -EEXIST) /* from above or from radix_tree_insert */ | |
1293 | goto repeat; | |
1294 | return error; | |
1295 | } | |
1296 | ||
1297 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
1298 | { | |
1299 | struct inode *inode = file_inode(vma->vm_file); | |
1300 | int error; | |
1301 | int ret = VM_FAULT_LOCKED; | |
1302 | ||
1303 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); | |
1304 | if (error) | |
1305 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); | |
1306 | ||
1307 | if (ret & VM_FAULT_MAJOR) { | |
1308 | count_vm_event(PGMAJFAULT); | |
1309 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
1310 | } | |
1311 | return ret; | |
1312 | } | |
1313 | ||
1314 | #ifdef CONFIG_NUMA | |
1315 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) | |
1316 | { | |
1317 | struct inode *inode = file_inode(vma->vm_file); | |
1318 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); | |
1319 | } | |
1320 | ||
1321 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, | |
1322 | unsigned long addr) | |
1323 | { | |
1324 | struct inode *inode = file_inode(vma->vm_file); | |
1325 | pgoff_t index; | |
1326 | ||
1327 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
1328 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); | |
1329 | } | |
1330 | #endif | |
1331 | ||
1332 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
1333 | { | |
1334 | struct inode *inode = file_inode(file); | |
1335 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1336 | int retval = -ENOMEM; | |
1337 | ||
1338 | spin_lock(&info->lock); | |
1339 | if (lock && !(info->flags & VM_LOCKED)) { | |
1340 | if (!user_shm_lock(inode->i_size, user)) | |
1341 | goto out_nomem; | |
1342 | info->flags |= VM_LOCKED; | |
1343 | mapping_set_unevictable(file->f_mapping); | |
1344 | } | |
1345 | if (!lock && (info->flags & VM_LOCKED) && user) { | |
1346 | user_shm_unlock(inode->i_size, user); | |
1347 | info->flags &= ~VM_LOCKED; | |
1348 | mapping_clear_unevictable(file->f_mapping); | |
1349 | } | |
1350 | retval = 0; | |
1351 | ||
1352 | out_nomem: | |
1353 | spin_unlock(&info->lock); | |
1354 | return retval; | |
1355 | } | |
1356 | ||
1357 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) | |
1358 | { | |
1359 | file_accessed(file); | |
1360 | vma->vm_ops = &shmem_vm_ops; | |
1361 | return 0; | |
1362 | } | |
1363 | ||
1364 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, | |
1365 | umode_t mode, dev_t dev, unsigned long flags) | |
1366 | { | |
1367 | struct inode *inode; | |
1368 | struct shmem_inode_info *info; | |
1369 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
1370 | ||
1371 | if (shmem_reserve_inode(sb)) | |
1372 | return NULL; | |
1373 | ||
1374 | inode = new_inode(sb); | |
1375 | if (inode) { | |
1376 | inode->i_ino = get_next_ino(); | |
1377 | inode_init_owner(inode, dir, mode); | |
1378 | inode->i_blocks = 0; | |
1379 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; | |
1380 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
1381 | inode->i_generation = get_seconds(); | |
1382 | info = SHMEM_I(inode); | |
1383 | memset(info, 0, (char *)inode - (char *)info); | |
1384 | spin_lock_init(&info->lock); | |
1385 | info->flags = flags & VM_NORESERVE; | |
1386 | INIT_LIST_HEAD(&info->swaplist); | |
1387 | simple_xattrs_init(&info->xattrs); | |
1388 | cache_no_acl(inode); | |
1389 | ||
1390 | switch (mode & S_IFMT) { | |
1391 | default: | |
1392 | inode->i_op = &shmem_special_inode_operations; | |
1393 | init_special_inode(inode, mode, dev); | |
1394 | break; | |
1395 | case S_IFREG: | |
1396 | inode->i_mapping->a_ops = &shmem_aops; | |
1397 | inode->i_op = &shmem_inode_operations; | |
1398 | inode->i_fop = &shmem_file_operations; | |
1399 | mpol_shared_policy_init(&info->policy, | |
1400 | shmem_get_sbmpol(sbinfo)); | |
1401 | break; | |
1402 | case S_IFDIR: | |
1403 | inc_nlink(inode); | |
1404 | /* Some things misbehave if size == 0 on a directory */ | |
1405 | inode->i_size = 2 * BOGO_DIRENT_SIZE; | |
1406 | inode->i_op = &shmem_dir_inode_operations; | |
1407 | inode->i_fop = &simple_dir_operations; | |
1408 | break; | |
1409 | case S_IFLNK: | |
1410 | /* | |
1411 | * Must not load anything in the rbtree, | |
1412 | * mpol_free_shared_policy will not be called. | |
1413 | */ | |
1414 | mpol_shared_policy_init(&info->policy, NULL); | |
1415 | break; | |
1416 | } | |
1417 | } else | |
1418 | shmem_free_inode(sb); | |
1419 | return inode; | |
1420 | } | |
1421 | ||
1422 | #ifdef CONFIG_TMPFS | |
1423 | static const struct inode_operations shmem_symlink_inode_operations; | |
1424 | static const struct inode_operations shmem_short_symlink_operations; | |
1425 | ||
1426 | #ifdef CONFIG_TMPFS_XATTR | |
1427 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); | |
1428 | #else | |
1429 | #define shmem_initxattrs NULL | |
1430 | #endif | |
1431 | ||
1432 | static int | |
1433 | shmem_write_begin(struct file *file, struct address_space *mapping, | |
1434 | loff_t pos, unsigned len, unsigned flags, | |
1435 | struct page **pagep, void **fsdata) | |
1436 | { | |
1437 | struct inode *inode = mapping->host; | |
1438 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
1439 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); | |
1440 | } | |
1441 | ||
1442 | static int | |
1443 | shmem_write_end(struct file *file, struct address_space *mapping, | |
1444 | loff_t pos, unsigned len, unsigned copied, | |
1445 | struct page *page, void *fsdata) | |
1446 | { | |
1447 | struct inode *inode = mapping->host; | |
1448 | ||
1449 | if (pos + copied > inode->i_size) | |
1450 | i_size_write(inode, pos + copied); | |
1451 | ||
1452 | if (!PageUptodate(page)) { | |
1453 | if (copied < PAGE_CACHE_SIZE) { | |
1454 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
1455 | zero_user_segments(page, 0, from, | |
1456 | from + copied, PAGE_CACHE_SIZE); | |
1457 | } | |
1458 | SetPageUptodate(page); | |
1459 | } | |
1460 | set_page_dirty(page); | |
1461 | unlock_page(page); | |
1462 | page_cache_release(page); | |
1463 | ||
1464 | return copied; | |
1465 | } | |
1466 | ||
1467 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) | |
1468 | { | |
1469 | struct inode *inode = file_inode(filp); | |
1470 | struct address_space *mapping = inode->i_mapping; | |
1471 | pgoff_t index; | |
1472 | unsigned long offset; | |
1473 | enum sgp_type sgp = SGP_READ; | |
1474 | ||
1475 | /* | |
1476 | * Might this read be for a stacking filesystem? Then when reading | |
1477 | * holes of a sparse file, we actually need to allocate those pages, | |
1478 | * and even mark them dirty, so it cannot exceed the max_blocks limit. | |
1479 | */ | |
1480 | if (segment_eq(get_fs(), KERNEL_DS)) | |
1481 | sgp = SGP_DIRTY; | |
1482 | ||
1483 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1484 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1485 | ||
1486 | for (;;) { | |
1487 | struct page *page = NULL; | |
1488 | pgoff_t end_index; | |
1489 | unsigned long nr, ret; | |
1490 | loff_t i_size = i_size_read(inode); | |
1491 | ||
1492 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1493 | if (index > end_index) | |
1494 | break; | |
1495 | if (index == end_index) { | |
1496 | nr = i_size & ~PAGE_CACHE_MASK; | |
1497 | if (nr <= offset) | |
1498 | break; | |
1499 | } | |
1500 | ||
1501 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); | |
1502 | if (desc->error) { | |
1503 | if (desc->error == -EINVAL) | |
1504 | desc->error = 0; | |
1505 | break; | |
1506 | } | |
1507 | if (page) | |
1508 | unlock_page(page); | |
1509 | ||
1510 | /* | |
1511 | * We must evaluate after, since reads (unlike writes) | |
1512 | * are called without i_mutex protection against truncate | |
1513 | */ | |
1514 | nr = PAGE_CACHE_SIZE; | |
1515 | i_size = i_size_read(inode); | |
1516 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1517 | if (index == end_index) { | |
1518 | nr = i_size & ~PAGE_CACHE_MASK; | |
1519 | if (nr <= offset) { | |
1520 | if (page) | |
1521 | page_cache_release(page); | |
1522 | break; | |
1523 | } | |
1524 | } | |
1525 | nr -= offset; | |
1526 | ||
1527 | if (page) { | |
1528 | /* | |
1529 | * If users can be writing to this page using arbitrary | |
1530 | * virtual addresses, take care about potential aliasing | |
1531 | * before reading the page on the kernel side. | |
1532 | */ | |
1533 | if (mapping_writably_mapped(mapping)) | |
1534 | flush_dcache_page(page); | |
1535 | /* | |
1536 | * Mark the page accessed if we read the beginning. | |
1537 | */ | |
1538 | if (!offset) | |
1539 | mark_page_accessed(page); | |
1540 | } else { | |
1541 | page = ZERO_PAGE(0); | |
1542 | page_cache_get(page); | |
1543 | } | |
1544 | ||
1545 | /* | |
1546 | * Ok, we have the page, and it's up-to-date, so | |
1547 | * now we can copy it to user space... | |
1548 | * | |
1549 | * The actor routine returns how many bytes were actually used.. | |
1550 | * NOTE! This may not be the same as how much of a user buffer | |
1551 | * we filled up (we may be padding etc), so we can only update | |
1552 | * "pos" here (the actor routine has to update the user buffer | |
1553 | * pointers and the remaining count). | |
1554 | */ | |
1555 | ret = actor(desc, page, offset, nr); | |
1556 | offset += ret; | |
1557 | index += offset >> PAGE_CACHE_SHIFT; | |
1558 | offset &= ~PAGE_CACHE_MASK; | |
1559 | ||
1560 | page_cache_release(page); | |
1561 | if (ret != nr || !desc->count) | |
1562 | break; | |
1563 | ||
1564 | cond_resched(); | |
1565 | } | |
1566 | ||
1567 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
1568 | file_accessed(filp); | |
1569 | } | |
1570 | ||
1571 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, | |
1572 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1573 | { | |
1574 | struct file *filp = iocb->ki_filp; | |
1575 | ssize_t retval; | |
1576 | unsigned long seg; | |
1577 | size_t count; | |
1578 | loff_t *ppos = &iocb->ki_pos; | |
1579 | ||
1580 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); | |
1581 | if (retval) | |
1582 | return retval; | |
1583 | ||
1584 | for (seg = 0; seg < nr_segs; seg++) { | |
1585 | read_descriptor_t desc; | |
1586 | ||
1587 | desc.written = 0; | |
1588 | desc.arg.buf = iov[seg].iov_base; | |
1589 | desc.count = iov[seg].iov_len; | |
1590 | if (desc.count == 0) | |
1591 | continue; | |
1592 | desc.error = 0; | |
1593 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); | |
1594 | retval += desc.written; | |
1595 | if (desc.error) { | |
1596 | retval = retval ?: desc.error; | |
1597 | break; | |
1598 | } | |
1599 | if (desc.count > 0) | |
1600 | break; | |
1601 | } | |
1602 | return retval; | |
1603 | } | |
1604 | ||
1605 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, | |
1606 | struct pipe_inode_info *pipe, size_t len, | |
1607 | unsigned int flags) | |
1608 | { | |
1609 | struct address_space *mapping = in->f_mapping; | |
1610 | struct inode *inode = mapping->host; | |
1611 | unsigned int loff, nr_pages, req_pages; | |
1612 | struct page *pages[PIPE_DEF_BUFFERS]; | |
1613 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1614 | struct page *page; | |
1615 | pgoff_t index, end_index; | |
1616 | loff_t isize, left; | |
1617 | int error, page_nr; | |
1618 | struct splice_pipe_desc spd = { | |
1619 | .pages = pages, | |
1620 | .partial = partial, | |
1621 | .nr_pages_max = PIPE_DEF_BUFFERS, | |
1622 | .flags = flags, | |
1623 | .ops = &page_cache_pipe_buf_ops, | |
1624 | .spd_release = spd_release_page, | |
1625 | }; | |
1626 | ||
1627 | isize = i_size_read(inode); | |
1628 | if (unlikely(*ppos >= isize)) | |
1629 | return 0; | |
1630 | ||
1631 | left = isize - *ppos; | |
1632 | if (unlikely(left < len)) | |
1633 | len = left; | |
1634 | ||
1635 | if (splice_grow_spd(pipe, &spd)) | |
1636 | return -ENOMEM; | |
1637 | ||
1638 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1639 | loff = *ppos & ~PAGE_CACHE_MASK; | |
1640 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1641 | nr_pages = min(req_pages, pipe->buffers); | |
1642 | ||
1643 | spd.nr_pages = find_get_pages_contig(mapping, index, | |
1644 | nr_pages, spd.pages); | |
1645 | index += spd.nr_pages; | |
1646 | error = 0; | |
1647 | ||
1648 | while (spd.nr_pages < nr_pages) { | |
1649 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); | |
1650 | if (error) | |
1651 | break; | |
1652 | unlock_page(page); | |
1653 | spd.pages[spd.nr_pages++] = page; | |
1654 | index++; | |
1655 | } | |
1656 | ||
1657 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1658 | nr_pages = spd.nr_pages; | |
1659 | spd.nr_pages = 0; | |
1660 | ||
1661 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
1662 | unsigned int this_len; | |
1663 | ||
1664 | if (!len) | |
1665 | break; | |
1666 | ||
1667 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
1668 | page = spd.pages[page_nr]; | |
1669 | ||
1670 | if (!PageUptodate(page) || page->mapping != mapping) { | |
1671 | error = shmem_getpage(inode, index, &page, | |
1672 | SGP_CACHE, NULL); | |
1673 | if (error) | |
1674 | break; | |
1675 | unlock_page(page); | |
1676 | page_cache_release(spd.pages[page_nr]); | |
1677 | spd.pages[page_nr] = page; | |
1678 | } | |
1679 | ||
1680 | isize = i_size_read(inode); | |
1681 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1682 | if (unlikely(!isize || index > end_index)) | |
1683 | break; | |
1684 | ||
1685 | if (end_index == index) { | |
1686 | unsigned int plen; | |
1687 | ||
1688 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1689 | if (plen <= loff) | |
1690 | break; | |
1691 | ||
1692 | this_len = min(this_len, plen - loff); | |
1693 | len = this_len; | |
1694 | } | |
1695 | ||
1696 | spd.partial[page_nr].offset = loff; | |
1697 | spd.partial[page_nr].len = this_len; | |
1698 | len -= this_len; | |
1699 | loff = 0; | |
1700 | spd.nr_pages++; | |
1701 | index++; | |
1702 | } | |
1703 | ||
1704 | while (page_nr < nr_pages) | |
1705 | page_cache_release(spd.pages[page_nr++]); | |
1706 | ||
1707 | if (spd.nr_pages) | |
1708 | error = splice_to_pipe(pipe, &spd); | |
1709 | ||
1710 | splice_shrink_spd(&spd); | |
1711 | ||
1712 | if (error > 0) { | |
1713 | *ppos += error; | |
1714 | file_accessed(in); | |
1715 | } | |
1716 | return error; | |
1717 | } | |
1718 | ||
1719 | /* | |
1720 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. | |
1721 | */ | |
1722 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, | |
1723 | pgoff_t index, pgoff_t end, int whence) | |
1724 | { | |
1725 | struct page *page; | |
1726 | struct pagevec pvec; | |
1727 | pgoff_t indices[PAGEVEC_SIZE]; | |
1728 | bool done = false; | |
1729 | int i; | |
1730 | ||
1731 | pagevec_init(&pvec, 0); | |
1732 | pvec.nr = 1; /* start small: we may be there already */ | |
1733 | while (!done) { | |
1734 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
1735 | pvec.nr, pvec.pages, indices); | |
1736 | if (!pvec.nr) { | |
1737 | if (whence == SEEK_DATA) | |
1738 | index = end; | |
1739 | break; | |
1740 | } | |
1741 | for (i = 0; i < pvec.nr; i++, index++) { | |
1742 | if (index < indices[i]) { | |
1743 | if (whence == SEEK_HOLE) { | |
1744 | done = true; | |
1745 | break; | |
1746 | } | |
1747 | index = indices[i]; | |
1748 | } | |
1749 | page = pvec.pages[i]; | |
1750 | if (page && !radix_tree_exceptional_entry(page)) { | |
1751 | if (!PageUptodate(page)) | |
1752 | page = NULL; | |
1753 | } | |
1754 | if (index >= end || | |
1755 | (page && whence == SEEK_DATA) || | |
1756 | (!page && whence == SEEK_HOLE)) { | |
1757 | done = true; | |
1758 | break; | |
1759 | } | |
1760 | } | |
1761 | shmem_deswap_pagevec(&pvec); | |
1762 | pagevec_release(&pvec); | |
1763 | pvec.nr = PAGEVEC_SIZE; | |
1764 | cond_resched(); | |
1765 | } | |
1766 | return index; | |
1767 | } | |
1768 | ||
1769 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) | |
1770 | { | |
1771 | struct address_space *mapping = file->f_mapping; | |
1772 | struct inode *inode = mapping->host; | |
1773 | pgoff_t start, end; | |
1774 | loff_t new_offset; | |
1775 | ||
1776 | if (whence != SEEK_DATA && whence != SEEK_HOLE) | |
1777 | return generic_file_llseek_size(file, offset, whence, | |
1778 | MAX_LFS_FILESIZE, i_size_read(inode)); | |
1779 | mutex_lock(&inode->i_mutex); | |
1780 | /* We're holding i_mutex so we can access i_size directly */ | |
1781 | ||
1782 | if (offset < 0) | |
1783 | offset = -EINVAL; | |
1784 | else if (offset >= inode->i_size) | |
1785 | offset = -ENXIO; | |
1786 | else { | |
1787 | start = offset >> PAGE_CACHE_SHIFT; | |
1788 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1789 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); | |
1790 | new_offset <<= PAGE_CACHE_SHIFT; | |
1791 | if (new_offset > offset) { | |
1792 | if (new_offset < inode->i_size) | |
1793 | offset = new_offset; | |
1794 | else if (whence == SEEK_DATA) | |
1795 | offset = -ENXIO; | |
1796 | else | |
1797 | offset = inode->i_size; | |
1798 | } | |
1799 | } | |
1800 | ||
1801 | if (offset >= 0) | |
1802 | offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); | |
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 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
1941 | error = generic_acl_init(inode, dir); | |
1942 | if (error) { | |
1943 | iput(inode); | |
1944 | return error; | |
1945 | } | |
1946 | #endif | |
1947 | error = security_inode_init_security(inode, dir, | |
1948 | &dentry->d_name, | |
1949 | shmem_initxattrs, NULL); | |
1950 | if (error) { | |
1951 | if (error != -EOPNOTSUPP) { | |
1952 | iput(inode); | |
1953 | return error; | |
1954 | } | |
1955 | } | |
1956 | ||
1957 | error = 0; | |
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 | |
1967 | shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) | |
1968 | { | |
1969 | struct inode *inode; | |
1970 | int error = -ENOSPC; | |
1971 | ||
1972 | inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); | |
1973 | if (inode) { | |
1974 | error = security_inode_init_security(inode, dir, | |
1975 | NULL, | |
1976 | shmem_initxattrs, NULL); | |
1977 | if (error) { | |
1978 | if (error != -EOPNOTSUPP) { | |
1979 | iput(inode); | |
1980 | return error; | |
1981 | } | |
1982 | } | |
1983 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
1984 | error = generic_acl_init(inode, dir); | |
1985 | if (error) { | |
1986 | iput(inode); | |
1987 | return error; | |
1988 | } | |
1989 | #else | |
1990 | error = 0; | |
1991 | #endif | |
1992 | d_tmpfile(dentry, inode); | |
1993 | } | |
1994 | return error; | |
1995 | } | |
1996 | ||
1997 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
1998 | { | |
1999 | int error; | |
2000 | ||
2001 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) | |
2002 | return error; | |
2003 | inc_nlink(dir); | |
2004 | return 0; | |
2005 | } | |
2006 | ||
2007 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
2008 | bool excl) | |
2009 | { | |
2010 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); | |
2011 | } | |
2012 | ||
2013 | /* | |
2014 | * Link a file.. | |
2015 | */ | |
2016 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
2017 | { | |
2018 | struct inode *inode = old_dentry->d_inode; | |
2019 | int ret; | |
2020 | ||
2021 | /* | |
2022 | * No ordinary (disk based) filesystem counts links as inodes; | |
2023 | * but each new link needs a new dentry, pinning lowmem, and | |
2024 | * tmpfs dentries cannot be pruned until they are unlinked. | |
2025 | */ | |
2026 | ret = shmem_reserve_inode(inode->i_sb); | |
2027 | if (ret) | |
2028 | goto out; | |
2029 | ||
2030 | dir->i_size += BOGO_DIRENT_SIZE; | |
2031 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2032 | inc_nlink(inode); | |
2033 | ihold(inode); /* New dentry reference */ | |
2034 | dget(dentry); /* Extra pinning count for the created dentry */ | |
2035 | d_instantiate(dentry, inode); | |
2036 | out: | |
2037 | return ret; | |
2038 | } | |
2039 | ||
2040 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) | |
2041 | { | |
2042 | struct inode *inode = dentry->d_inode; | |
2043 | ||
2044 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) | |
2045 | shmem_free_inode(inode->i_sb); | |
2046 | ||
2047 | dir->i_size -= BOGO_DIRENT_SIZE; | |
2048 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2049 | drop_nlink(inode); | |
2050 | dput(dentry); /* Undo the count from "create" - this does all the work */ | |
2051 | return 0; | |
2052 | } | |
2053 | ||
2054 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) | |
2055 | { | |
2056 | if (!simple_empty(dentry)) | |
2057 | return -ENOTEMPTY; | |
2058 | ||
2059 | drop_nlink(dentry->d_inode); | |
2060 | drop_nlink(dir); | |
2061 | return shmem_unlink(dir, dentry); | |
2062 | } | |
2063 | ||
2064 | /* | |
2065 | * The VFS layer already does all the dentry stuff for rename, | |
2066 | * we just have to decrement the usage count for the target if | |
2067 | * it exists so that the VFS layer correctly free's it when it | |
2068 | * gets overwritten. | |
2069 | */ | |
2070 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) | |
2071 | { | |
2072 | struct inode *inode = old_dentry->d_inode; | |
2073 | int they_are_dirs = S_ISDIR(inode->i_mode); | |
2074 | ||
2075 | if (!simple_empty(new_dentry)) | |
2076 | return -ENOTEMPTY; | |
2077 | ||
2078 | if (new_dentry->d_inode) { | |
2079 | (void) shmem_unlink(new_dir, new_dentry); | |
2080 | if (they_are_dirs) | |
2081 | drop_nlink(old_dir); | |
2082 | } else if (they_are_dirs) { | |
2083 | drop_nlink(old_dir); | |
2084 | inc_nlink(new_dir); | |
2085 | } | |
2086 | ||
2087 | old_dir->i_size -= BOGO_DIRENT_SIZE; | |
2088 | new_dir->i_size += BOGO_DIRENT_SIZE; | |
2089 | old_dir->i_ctime = old_dir->i_mtime = | |
2090 | new_dir->i_ctime = new_dir->i_mtime = | |
2091 | inode->i_ctime = CURRENT_TIME; | |
2092 | return 0; | |
2093 | } | |
2094 | ||
2095 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) | |
2096 | { | |
2097 | int error; | |
2098 | int len; | |
2099 | struct inode *inode; | |
2100 | struct page *page; | |
2101 | char *kaddr; | |
2102 | struct shmem_inode_info *info; | |
2103 | ||
2104 | len = strlen(symname) + 1; | |
2105 | if (len > PAGE_CACHE_SIZE) | |
2106 | return -ENAMETOOLONG; | |
2107 | ||
2108 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); | |
2109 | if (!inode) | |
2110 | return -ENOSPC; | |
2111 | ||
2112 | error = security_inode_init_security(inode, dir, &dentry->d_name, | |
2113 | shmem_initxattrs, NULL); | |
2114 | if (error) { | |
2115 | if (error != -EOPNOTSUPP) { | |
2116 | iput(inode); | |
2117 | return error; | |
2118 | } | |
2119 | error = 0; | |
2120 | } | |
2121 | ||
2122 | info = SHMEM_I(inode); | |
2123 | inode->i_size = len-1; | |
2124 | if (len <= SHORT_SYMLINK_LEN) { | |
2125 | info->symlink = kmemdup(symname, len, GFP_KERNEL); | |
2126 | if (!info->symlink) { | |
2127 | iput(inode); | |
2128 | return -ENOMEM; | |
2129 | } | |
2130 | inode->i_op = &shmem_short_symlink_operations; | |
2131 | } else { | |
2132 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); | |
2133 | if (error) { | |
2134 | iput(inode); | |
2135 | return error; | |
2136 | } | |
2137 | inode->i_mapping->a_ops = &shmem_aops; | |
2138 | inode->i_op = &shmem_symlink_inode_operations; | |
2139 | kaddr = kmap_atomic(page); | |
2140 | memcpy(kaddr, symname, len); | |
2141 | kunmap_atomic(kaddr); | |
2142 | SetPageUptodate(page); | |
2143 | set_page_dirty(page); | |
2144 | unlock_page(page); | |
2145 | page_cache_release(page); | |
2146 | } | |
2147 | dir->i_size += BOGO_DIRENT_SIZE; | |
2148 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2149 | d_instantiate(dentry, inode); | |
2150 | dget(dentry); | |
2151 | return 0; | |
2152 | } | |
2153 | ||
2154 | static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) | |
2155 | { | |
2156 | nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); | |
2157 | return NULL; | |
2158 | } | |
2159 | ||
2160 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) | |
2161 | { | |
2162 | struct page *page = NULL; | |
2163 | int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); | |
2164 | nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); | |
2165 | if (page) | |
2166 | unlock_page(page); | |
2167 | return page; | |
2168 | } | |
2169 | ||
2170 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) | |
2171 | { | |
2172 | if (!IS_ERR(nd_get_link(nd))) { | |
2173 | struct page *page = cookie; | |
2174 | kunmap(page); | |
2175 | mark_page_accessed(page); | |
2176 | page_cache_release(page); | |
2177 | } | |
2178 | } | |
2179 | ||
2180 | #ifdef CONFIG_TMPFS_XATTR | |
2181 | /* | |
2182 | * Superblocks without xattr inode operations may get some security.* xattr | |
2183 | * support from the LSM "for free". As soon as we have any other xattrs | |
2184 | * like ACLs, we also need to implement the security.* handlers at | |
2185 | * filesystem level, though. | |
2186 | */ | |
2187 | ||
2188 | /* | |
2189 | * Callback for security_inode_init_security() for acquiring xattrs. | |
2190 | */ | |
2191 | static int shmem_initxattrs(struct inode *inode, | |
2192 | const struct xattr *xattr_array, | |
2193 | void *fs_info) | |
2194 | { | |
2195 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2196 | const struct xattr *xattr; | |
2197 | struct simple_xattr *new_xattr; | |
2198 | size_t len; | |
2199 | ||
2200 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { | |
2201 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); | |
2202 | if (!new_xattr) | |
2203 | return -ENOMEM; | |
2204 | ||
2205 | len = strlen(xattr->name) + 1; | |
2206 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, | |
2207 | GFP_KERNEL); | |
2208 | if (!new_xattr->name) { | |
2209 | kfree(new_xattr); | |
2210 | return -ENOMEM; | |
2211 | } | |
2212 | ||
2213 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, | |
2214 | XATTR_SECURITY_PREFIX_LEN); | |
2215 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, | |
2216 | xattr->name, len); | |
2217 | ||
2218 | simple_xattr_list_add(&info->xattrs, new_xattr); | |
2219 | } | |
2220 | ||
2221 | return 0; | |
2222 | } | |
2223 | ||
2224 | static const struct xattr_handler *shmem_xattr_handlers[] = { | |
2225 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2226 | &generic_acl_access_handler, | |
2227 | &generic_acl_default_handler, | |
2228 | #endif | |
2229 | NULL | |
2230 | }; | |
2231 | ||
2232 | static int shmem_xattr_validate(const char *name) | |
2233 | { | |
2234 | struct { const char *prefix; size_t len; } arr[] = { | |
2235 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, | |
2236 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } | |
2237 | }; | |
2238 | int i; | |
2239 | ||
2240 | for (i = 0; i < ARRAY_SIZE(arr); i++) { | |
2241 | size_t preflen = arr[i].len; | |
2242 | if (strncmp(name, arr[i].prefix, preflen) == 0) { | |
2243 | if (!name[preflen]) | |
2244 | return -EINVAL; | |
2245 | return 0; | |
2246 | } | |
2247 | } | |
2248 | return -EOPNOTSUPP; | |
2249 | } | |
2250 | ||
2251 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, | |
2252 | void *buffer, size_t size) | |
2253 | { | |
2254 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2255 | int err; | |
2256 | ||
2257 | /* | |
2258 | * If this is a request for a synthetic attribute in the system.* | |
2259 | * namespace use the generic infrastructure to resolve a handler | |
2260 | * for it via sb->s_xattr. | |
2261 | */ | |
2262 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2263 | return generic_getxattr(dentry, name, buffer, size); | |
2264 | ||
2265 | err = shmem_xattr_validate(name); | |
2266 | if (err) | |
2267 | return err; | |
2268 | ||
2269 | return simple_xattr_get(&info->xattrs, name, buffer, size); | |
2270 | } | |
2271 | ||
2272 | static int shmem_setxattr(struct dentry *dentry, const char *name, | |
2273 | const void *value, size_t size, int flags) | |
2274 | { | |
2275 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2276 | int err; | |
2277 | ||
2278 | /* | |
2279 | * If this is a request for a synthetic attribute in the system.* | |
2280 | * namespace use the generic infrastructure to resolve a handler | |
2281 | * for it via sb->s_xattr. | |
2282 | */ | |
2283 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2284 | return generic_setxattr(dentry, name, value, size, flags); | |
2285 | ||
2286 | err = shmem_xattr_validate(name); | |
2287 | if (err) | |
2288 | return err; | |
2289 | ||
2290 | return simple_xattr_set(&info->xattrs, name, value, size, flags); | |
2291 | } | |
2292 | ||
2293 | static int shmem_removexattr(struct dentry *dentry, const char *name) | |
2294 | { | |
2295 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2296 | int err; | |
2297 | ||
2298 | /* | |
2299 | * If this is a request for a synthetic attribute in the system.* | |
2300 | * namespace use the generic infrastructure to resolve a handler | |
2301 | * for it via sb->s_xattr. | |
2302 | */ | |
2303 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2304 | return generic_removexattr(dentry, name); | |
2305 | ||
2306 | err = shmem_xattr_validate(name); | |
2307 | if (err) | |
2308 | return err; | |
2309 | ||
2310 | return simple_xattr_remove(&info->xattrs, name); | |
2311 | } | |
2312 | ||
2313 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) | |
2314 | { | |
2315 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2316 | return simple_xattr_list(&info->xattrs, buffer, size); | |
2317 | } | |
2318 | #endif /* CONFIG_TMPFS_XATTR */ | |
2319 | ||
2320 | static const struct inode_operations shmem_short_symlink_operations = { | |
2321 | .readlink = generic_readlink, | |
2322 | .follow_link = shmem_follow_short_symlink, | |
2323 | #ifdef CONFIG_TMPFS_XATTR | |
2324 | .setxattr = shmem_setxattr, | |
2325 | .getxattr = shmem_getxattr, | |
2326 | .listxattr = shmem_listxattr, | |
2327 | .removexattr = shmem_removexattr, | |
2328 | #endif | |
2329 | }; | |
2330 | ||
2331 | static const struct inode_operations shmem_symlink_inode_operations = { | |
2332 | .readlink = generic_readlink, | |
2333 | .follow_link = shmem_follow_link, | |
2334 | .put_link = shmem_put_link, | |
2335 | #ifdef CONFIG_TMPFS_XATTR | |
2336 | .setxattr = shmem_setxattr, | |
2337 | .getxattr = shmem_getxattr, | |
2338 | .listxattr = shmem_listxattr, | |
2339 | .removexattr = shmem_removexattr, | |
2340 | #endif | |
2341 | }; | |
2342 | ||
2343 | static struct dentry *shmem_get_parent(struct dentry *child) | |
2344 | { | |
2345 | return ERR_PTR(-ESTALE); | |
2346 | } | |
2347 | ||
2348 | static int shmem_match(struct inode *ino, void *vfh) | |
2349 | { | |
2350 | __u32 *fh = vfh; | |
2351 | __u64 inum = fh[2]; | |
2352 | inum = (inum << 32) | fh[1]; | |
2353 | return ino->i_ino == inum && fh[0] == ino->i_generation; | |
2354 | } | |
2355 | ||
2356 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, | |
2357 | struct fid *fid, int fh_len, int fh_type) | |
2358 | { | |
2359 | struct inode *inode; | |
2360 | struct dentry *dentry = NULL; | |
2361 | u64 inum; | |
2362 | ||
2363 | if (fh_len < 3) | |
2364 | return NULL; | |
2365 | ||
2366 | inum = fid->raw[2]; | |
2367 | inum = (inum << 32) | fid->raw[1]; | |
2368 | ||
2369 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), | |
2370 | shmem_match, fid->raw); | |
2371 | if (inode) { | |
2372 | dentry = d_find_alias(inode); | |
2373 | iput(inode); | |
2374 | } | |
2375 | ||
2376 | return dentry; | |
2377 | } | |
2378 | ||
2379 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, | |
2380 | struct inode *parent) | |
2381 | { | |
2382 | if (*len < 3) { | |
2383 | *len = 3; | |
2384 | return FILEID_INVALID; | |
2385 | } | |
2386 | ||
2387 | if (inode_unhashed(inode)) { | |
2388 | /* Unfortunately insert_inode_hash is not idempotent, | |
2389 | * so as we hash inodes here rather than at creation | |
2390 | * time, we need a lock to ensure we only try | |
2391 | * to do it once | |
2392 | */ | |
2393 | static DEFINE_SPINLOCK(lock); | |
2394 | spin_lock(&lock); | |
2395 | if (inode_unhashed(inode)) | |
2396 | __insert_inode_hash(inode, | |
2397 | inode->i_ino + inode->i_generation); | |
2398 | spin_unlock(&lock); | |
2399 | } | |
2400 | ||
2401 | fh[0] = inode->i_generation; | |
2402 | fh[1] = inode->i_ino; | |
2403 | fh[2] = ((__u64)inode->i_ino) >> 32; | |
2404 | ||
2405 | *len = 3; | |
2406 | return 1; | |
2407 | } | |
2408 | ||
2409 | static const struct export_operations shmem_export_ops = { | |
2410 | .get_parent = shmem_get_parent, | |
2411 | .encode_fh = shmem_encode_fh, | |
2412 | .fh_to_dentry = shmem_fh_to_dentry, | |
2413 | }; | |
2414 | ||
2415 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, | |
2416 | bool remount) | |
2417 | { | |
2418 | char *this_char, *value, *rest; | |
2419 | struct mempolicy *mpol = NULL; | |
2420 | uid_t uid; | |
2421 | gid_t gid; | |
2422 | ||
2423 | while (options != NULL) { | |
2424 | this_char = options; | |
2425 | for (;;) { | |
2426 | /* | |
2427 | * NUL-terminate this option: unfortunately, | |
2428 | * mount options form a comma-separated list, | |
2429 | * but mpol's nodelist may also contain commas. | |
2430 | */ | |
2431 | options = strchr(options, ','); | |
2432 | if (options == NULL) | |
2433 | break; | |
2434 | options++; | |
2435 | if (!isdigit(*options)) { | |
2436 | options[-1] = '\0'; | |
2437 | break; | |
2438 | } | |
2439 | } | |
2440 | if (!*this_char) | |
2441 | continue; | |
2442 | if ((value = strchr(this_char,'=')) != NULL) { | |
2443 | *value++ = 0; | |
2444 | } else { | |
2445 | printk(KERN_ERR | |
2446 | "tmpfs: No value for mount option '%s'\n", | |
2447 | this_char); | |
2448 | goto error; | |
2449 | } | |
2450 | ||
2451 | if (!strcmp(this_char,"size")) { | |
2452 | unsigned long long size; | |
2453 | size = memparse(value,&rest); | |
2454 | if (*rest == '%') { | |
2455 | size <<= PAGE_SHIFT; | |
2456 | size *= totalram_pages; | |
2457 | do_div(size, 100); | |
2458 | rest++; | |
2459 | } | |
2460 | if (*rest) | |
2461 | goto bad_val; | |
2462 | sbinfo->max_blocks = | |
2463 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); | |
2464 | } else if (!strcmp(this_char,"nr_blocks")) { | |
2465 | sbinfo->max_blocks = memparse(value, &rest); | |
2466 | if (*rest) | |
2467 | goto bad_val; | |
2468 | } else if (!strcmp(this_char,"nr_inodes")) { | |
2469 | sbinfo->max_inodes = memparse(value, &rest); | |
2470 | if (*rest) | |
2471 | goto bad_val; | |
2472 | } else if (!strcmp(this_char,"mode")) { | |
2473 | if (remount) | |
2474 | continue; | |
2475 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; | |
2476 | if (*rest) | |
2477 | goto bad_val; | |
2478 | } else if (!strcmp(this_char,"uid")) { | |
2479 | if (remount) | |
2480 | continue; | |
2481 | uid = simple_strtoul(value, &rest, 0); | |
2482 | if (*rest) | |
2483 | goto bad_val; | |
2484 | sbinfo->uid = make_kuid(current_user_ns(), uid); | |
2485 | if (!uid_valid(sbinfo->uid)) | |
2486 | goto bad_val; | |
2487 | } else if (!strcmp(this_char,"gid")) { | |
2488 | if (remount) | |
2489 | continue; | |
2490 | gid = simple_strtoul(value, &rest, 0); | |
2491 | if (*rest) | |
2492 | goto bad_val; | |
2493 | sbinfo->gid = make_kgid(current_user_ns(), gid); | |
2494 | if (!gid_valid(sbinfo->gid)) | |
2495 | goto bad_val; | |
2496 | } else if (!strcmp(this_char,"mpol")) { | |
2497 | mpol_put(mpol); | |
2498 | mpol = NULL; | |
2499 | if (mpol_parse_str(value, &mpol)) | |
2500 | goto bad_val; | |
2501 | } else { | |
2502 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", | |
2503 | this_char); | |
2504 | goto error; | |
2505 | } | |
2506 | } | |
2507 | sbinfo->mpol = mpol; | |
2508 | return 0; | |
2509 | ||
2510 | bad_val: | |
2511 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", | |
2512 | value, this_char); | |
2513 | error: | |
2514 | mpol_put(mpol); | |
2515 | return 1; | |
2516 | ||
2517 | } | |
2518 | ||
2519 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) | |
2520 | { | |
2521 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2522 | struct shmem_sb_info config = *sbinfo; | |
2523 | unsigned long inodes; | |
2524 | int error = -EINVAL; | |
2525 | ||
2526 | config.mpol = NULL; | |
2527 | if (shmem_parse_options(data, &config, true)) | |
2528 | return error; | |
2529 | ||
2530 | spin_lock(&sbinfo->stat_lock); | |
2531 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; | |
2532 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) | |
2533 | goto out; | |
2534 | if (config.max_inodes < inodes) | |
2535 | goto out; | |
2536 | /* | |
2537 | * Those tests disallow limited->unlimited while any are in use; | |
2538 | * but we must separately disallow unlimited->limited, because | |
2539 | * in that case we have no record of how much is already in use. | |
2540 | */ | |
2541 | if (config.max_blocks && !sbinfo->max_blocks) | |
2542 | goto out; | |
2543 | if (config.max_inodes && !sbinfo->max_inodes) | |
2544 | goto out; | |
2545 | ||
2546 | error = 0; | |
2547 | sbinfo->max_blocks = config.max_blocks; | |
2548 | sbinfo->max_inodes = config.max_inodes; | |
2549 | sbinfo->free_inodes = config.max_inodes - inodes; | |
2550 | ||
2551 | /* | |
2552 | * Preserve previous mempolicy unless mpol remount option was specified. | |
2553 | */ | |
2554 | if (config.mpol) { | |
2555 | mpol_put(sbinfo->mpol); | |
2556 | sbinfo->mpol = config.mpol; /* transfers initial ref */ | |
2557 | } | |
2558 | out: | |
2559 | spin_unlock(&sbinfo->stat_lock); | |
2560 | return error; | |
2561 | } | |
2562 | ||
2563 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) | |
2564 | { | |
2565 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); | |
2566 | ||
2567 | if (sbinfo->max_blocks != shmem_default_max_blocks()) | |
2568 | seq_printf(seq, ",size=%luk", | |
2569 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); | |
2570 | if (sbinfo->max_inodes != shmem_default_max_inodes()) | |
2571 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); | |
2572 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) | |
2573 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); | |
2574 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) | |
2575 | seq_printf(seq, ",uid=%u", | |
2576 | from_kuid_munged(&init_user_ns, sbinfo->uid)); | |
2577 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) | |
2578 | seq_printf(seq, ",gid=%u", | |
2579 | from_kgid_munged(&init_user_ns, sbinfo->gid)); | |
2580 | shmem_show_mpol(seq, sbinfo->mpol); | |
2581 | return 0; | |
2582 | } | |
2583 | #endif /* CONFIG_TMPFS */ | |
2584 | ||
2585 | static void shmem_put_super(struct super_block *sb) | |
2586 | { | |
2587 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2588 | ||
2589 | percpu_counter_destroy(&sbinfo->used_blocks); | |
2590 | mpol_put(sbinfo->mpol); | |
2591 | kfree(sbinfo); | |
2592 | sb->s_fs_info = NULL; | |
2593 | } | |
2594 | ||
2595 | int shmem_fill_super(struct super_block *sb, void *data, int silent) | |
2596 | { | |
2597 | struct inode *inode; | |
2598 | struct shmem_sb_info *sbinfo; | |
2599 | int err = -ENOMEM; | |
2600 | ||
2601 | /* Round up to L1_CACHE_BYTES to resist false sharing */ | |
2602 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), | |
2603 | L1_CACHE_BYTES), GFP_KERNEL); | |
2604 | if (!sbinfo) | |
2605 | return -ENOMEM; | |
2606 | ||
2607 | sbinfo->mode = S_IRWXUGO | S_ISVTX; | |
2608 | sbinfo->uid = current_fsuid(); | |
2609 | sbinfo->gid = current_fsgid(); | |
2610 | sb->s_fs_info = sbinfo; | |
2611 | ||
2612 | #ifdef CONFIG_TMPFS | |
2613 | /* | |
2614 | * Per default we only allow half of the physical ram per | |
2615 | * tmpfs instance, limiting inodes to one per page of lowmem; | |
2616 | * but the internal instance is left unlimited. | |
2617 | */ | |
2618 | if (!(sb->s_flags & MS_KERNMOUNT)) { | |
2619 | sbinfo->max_blocks = shmem_default_max_blocks(); | |
2620 | sbinfo->max_inodes = shmem_default_max_inodes(); | |
2621 | if (shmem_parse_options(data, sbinfo, false)) { | |
2622 | err = -EINVAL; | |
2623 | goto failed; | |
2624 | } | |
2625 | } else { | |
2626 | sb->s_flags |= MS_NOUSER; | |
2627 | } | |
2628 | sb->s_export_op = &shmem_export_ops; | |
2629 | sb->s_flags |= MS_NOSEC; | |
2630 | #else | |
2631 | sb->s_flags |= MS_NOUSER; | |
2632 | #endif | |
2633 | ||
2634 | spin_lock_init(&sbinfo->stat_lock); | |
2635 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) | |
2636 | goto failed; | |
2637 | sbinfo->free_inodes = sbinfo->max_inodes; | |
2638 | ||
2639 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
2640 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
2641 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
2642 | sb->s_magic = TMPFS_MAGIC; | |
2643 | sb->s_op = &shmem_ops; | |
2644 | sb->s_time_gran = 1; | |
2645 | #ifdef CONFIG_TMPFS_XATTR | |
2646 | sb->s_xattr = shmem_xattr_handlers; | |
2647 | #endif | |
2648 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2649 | sb->s_flags |= MS_POSIXACL; | |
2650 | #endif | |
2651 | ||
2652 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); | |
2653 | if (!inode) | |
2654 | goto failed; | |
2655 | inode->i_uid = sbinfo->uid; | |
2656 | inode->i_gid = sbinfo->gid; | |
2657 | sb->s_root = d_make_root(inode); | |
2658 | if (!sb->s_root) | |
2659 | goto failed; | |
2660 | return 0; | |
2661 | ||
2662 | failed: | |
2663 | shmem_put_super(sb); | |
2664 | return err; | |
2665 | } | |
2666 | ||
2667 | static struct kmem_cache *shmem_inode_cachep; | |
2668 | ||
2669 | static struct inode *shmem_alloc_inode(struct super_block *sb) | |
2670 | { | |
2671 | struct shmem_inode_info *info; | |
2672 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); | |
2673 | if (!info) | |
2674 | return NULL; | |
2675 | return &info->vfs_inode; | |
2676 | } | |
2677 | ||
2678 | static void shmem_destroy_callback(struct rcu_head *head) | |
2679 | { | |
2680 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
2681 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); | |
2682 | } | |
2683 | ||
2684 | static void shmem_destroy_inode(struct inode *inode) | |
2685 | { | |
2686 | if (S_ISREG(inode->i_mode)) | |
2687 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); | |
2688 | call_rcu(&inode->i_rcu, shmem_destroy_callback); | |
2689 | } | |
2690 | ||
2691 | static void shmem_init_inode(void *foo) | |
2692 | { | |
2693 | struct shmem_inode_info *info = foo; | |
2694 | inode_init_once(&info->vfs_inode); | |
2695 | } | |
2696 | ||
2697 | static int shmem_init_inodecache(void) | |
2698 | { | |
2699 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", | |
2700 | sizeof(struct shmem_inode_info), | |
2701 | 0, SLAB_PANIC, shmem_init_inode); | |
2702 | return 0; | |
2703 | } | |
2704 | ||
2705 | static void shmem_destroy_inodecache(void) | |
2706 | { | |
2707 | kmem_cache_destroy(shmem_inode_cachep); | |
2708 | } | |
2709 | ||
2710 | static const struct address_space_operations shmem_aops = { | |
2711 | .writepage = shmem_writepage, | |
2712 | .set_page_dirty = __set_page_dirty_no_writeback, | |
2713 | #ifdef CONFIG_TMPFS | |
2714 | .write_begin = shmem_write_begin, | |
2715 | .write_end = shmem_write_end, | |
2716 | #endif | |
2717 | .migratepage = migrate_page, | |
2718 | .error_remove_page = generic_error_remove_page, | |
2719 | }; | |
2720 | ||
2721 | static const struct file_operations shmem_file_operations = { | |
2722 | .mmap = shmem_mmap, | |
2723 | #ifdef CONFIG_TMPFS | |
2724 | .llseek = shmem_file_llseek, | |
2725 | .read = do_sync_read, | |
2726 | .write = do_sync_write, | |
2727 | .aio_read = shmem_file_aio_read, | |
2728 | .aio_write = generic_file_aio_write, | |
2729 | .fsync = noop_fsync, | |
2730 | .splice_read = shmem_file_splice_read, | |
2731 | .splice_write = generic_file_splice_write, | |
2732 | .fallocate = shmem_fallocate, | |
2733 | #endif | |
2734 | }; | |
2735 | ||
2736 | static const struct inode_operations shmem_inode_operations = { | |
2737 | .setattr = shmem_setattr, | |
2738 | #ifdef CONFIG_TMPFS_XATTR | |
2739 | .setxattr = shmem_setxattr, | |
2740 | .getxattr = shmem_getxattr, | |
2741 | .listxattr = shmem_listxattr, | |
2742 | .removexattr = shmem_removexattr, | |
2743 | #endif | |
2744 | }; | |
2745 | ||
2746 | static const struct inode_operations shmem_dir_inode_operations = { | |
2747 | #ifdef CONFIG_TMPFS | |
2748 | .create = shmem_create, | |
2749 | .lookup = simple_lookup, | |
2750 | .link = shmem_link, | |
2751 | .unlink = shmem_unlink, | |
2752 | .symlink = shmem_symlink, | |
2753 | .mkdir = shmem_mkdir, | |
2754 | .rmdir = shmem_rmdir, | |
2755 | .mknod = shmem_mknod, | |
2756 | .rename = shmem_rename, | |
2757 | .tmpfile = shmem_tmpfile, | |
2758 | #endif | |
2759 | #ifdef CONFIG_TMPFS_XATTR | |
2760 | .setxattr = shmem_setxattr, | |
2761 | .getxattr = shmem_getxattr, | |
2762 | .listxattr = shmem_listxattr, | |
2763 | .removexattr = shmem_removexattr, | |
2764 | #endif | |
2765 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2766 | .setattr = shmem_setattr, | |
2767 | #endif | |
2768 | }; | |
2769 | ||
2770 | static const struct inode_operations shmem_special_inode_operations = { | |
2771 | #ifdef CONFIG_TMPFS_XATTR | |
2772 | .setxattr = shmem_setxattr, | |
2773 | .getxattr = shmem_getxattr, | |
2774 | .listxattr = shmem_listxattr, | |
2775 | .removexattr = shmem_removexattr, | |
2776 | #endif | |
2777 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2778 | .setattr = shmem_setattr, | |
2779 | #endif | |
2780 | }; | |
2781 | ||
2782 | static const struct super_operations shmem_ops = { | |
2783 | .alloc_inode = shmem_alloc_inode, | |
2784 | .destroy_inode = shmem_destroy_inode, | |
2785 | #ifdef CONFIG_TMPFS | |
2786 | .statfs = shmem_statfs, | |
2787 | .remount_fs = shmem_remount_fs, | |
2788 | .show_options = shmem_show_options, | |
2789 | #endif | |
2790 | .evict_inode = shmem_evict_inode, | |
2791 | .drop_inode = generic_delete_inode, | |
2792 | .put_super = shmem_put_super, | |
2793 | }; | |
2794 | ||
2795 | static const struct vm_operations_struct shmem_vm_ops = { | |
2796 | .fault = shmem_fault, | |
2797 | #ifdef CONFIG_NUMA | |
2798 | .set_policy = shmem_set_policy, | |
2799 | .get_policy = shmem_get_policy, | |
2800 | #endif | |
2801 | .remap_pages = generic_file_remap_pages, | |
2802 | }; | |
2803 | ||
2804 | static struct dentry *shmem_mount(struct file_system_type *fs_type, | |
2805 | int flags, const char *dev_name, void *data) | |
2806 | { | |
2807 | return mount_nodev(fs_type, flags, data, shmem_fill_super); | |
2808 | } | |
2809 | ||
2810 | static struct file_system_type shmem_fs_type = { | |
2811 | .owner = THIS_MODULE, | |
2812 | .name = "tmpfs", | |
2813 | .mount = shmem_mount, | |
2814 | .kill_sb = kill_litter_super, | |
2815 | .fs_flags = FS_USERNS_MOUNT, | |
2816 | }; | |
2817 | ||
2818 | int __init shmem_init(void) | |
2819 | { | |
2820 | int error; | |
2821 | ||
2822 | /* If rootfs called this, don't re-init */ | |
2823 | if (shmem_inode_cachep) | |
2824 | return 0; | |
2825 | ||
2826 | error = bdi_init(&shmem_backing_dev_info); | |
2827 | if (error) | |
2828 | goto out4; | |
2829 | ||
2830 | error = shmem_init_inodecache(); | |
2831 | if (error) | |
2832 | goto out3; | |
2833 | ||
2834 | error = register_filesystem(&shmem_fs_type); | |
2835 | if (error) { | |
2836 | printk(KERN_ERR "Could not register tmpfs\n"); | |
2837 | goto out2; | |
2838 | } | |
2839 | ||
2840 | shm_mnt = kern_mount(&shmem_fs_type); | |
2841 | if (IS_ERR(shm_mnt)) { | |
2842 | error = PTR_ERR(shm_mnt); | |
2843 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); | |
2844 | goto out1; | |
2845 | } | |
2846 | return 0; | |
2847 | ||
2848 | out1: | |
2849 | unregister_filesystem(&shmem_fs_type); | |
2850 | out2: | |
2851 | shmem_destroy_inodecache(); | |
2852 | out3: | |
2853 | bdi_destroy(&shmem_backing_dev_info); | |
2854 | out4: | |
2855 | shm_mnt = ERR_PTR(error); | |
2856 | return error; | |
2857 | } | |
2858 | ||
2859 | #else /* !CONFIG_SHMEM */ | |
2860 | ||
2861 | /* | |
2862 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code | |
2863 | * | |
2864 | * This is intended for small system where the benefits of the full | |
2865 | * shmem code (swap-backed and resource-limited) are outweighed by | |
2866 | * their complexity. On systems without swap this code should be | |
2867 | * effectively equivalent, but much lighter weight. | |
2868 | */ | |
2869 | ||
2870 | static struct file_system_type shmem_fs_type = { | |
2871 | .name = "tmpfs", | |
2872 | .mount = ramfs_mount, | |
2873 | .kill_sb = kill_litter_super, | |
2874 | .fs_flags = FS_USERNS_MOUNT, | |
2875 | }; | |
2876 | ||
2877 | int __init shmem_init(void) | |
2878 | { | |
2879 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); | |
2880 | ||
2881 | shm_mnt = kern_mount(&shmem_fs_type); | |
2882 | BUG_ON(IS_ERR(shm_mnt)); | |
2883 | ||
2884 | return 0; | |
2885 | } | |
2886 | ||
2887 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
2888 | { | |
2889 | return 0; | |
2890 | } | |
2891 | ||
2892 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
2893 | { | |
2894 | return 0; | |
2895 | } | |
2896 | ||
2897 | void shmem_unlock_mapping(struct address_space *mapping) | |
2898 | { | |
2899 | } | |
2900 | ||
2901 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
2902 | { | |
2903 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); | |
2904 | } | |
2905 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
2906 | ||
2907 | #define shmem_vm_ops generic_file_vm_ops | |
2908 | #define shmem_file_operations ramfs_file_operations | |
2909 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) | |
2910 | #define shmem_acct_size(flags, size) 0 | |
2911 | #define shmem_unacct_size(flags, size) do {} while (0) | |
2912 | ||
2913 | #endif /* CONFIG_SHMEM */ | |
2914 | ||
2915 | /* common code */ | |
2916 | ||
2917 | static struct dentry_operations anon_ops = { | |
2918 | .d_dname = simple_dname | |
2919 | }; | |
2920 | ||
2921 | /** | |
2922 | * shmem_file_setup - get an unlinked file living in tmpfs | |
2923 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
2924 | * @size: size to be set for the file | |
2925 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
2926 | */ | |
2927 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) | |
2928 | { | |
2929 | struct file *res; | |
2930 | struct inode *inode; | |
2931 | struct path path; | |
2932 | struct super_block *sb; | |
2933 | struct qstr this; | |
2934 | ||
2935 | if (IS_ERR(shm_mnt)) | |
2936 | return ERR_CAST(shm_mnt); | |
2937 | ||
2938 | if (size < 0 || size > MAX_LFS_FILESIZE) | |
2939 | return ERR_PTR(-EINVAL); | |
2940 | ||
2941 | if (shmem_acct_size(flags, size)) | |
2942 | return ERR_PTR(-ENOMEM); | |
2943 | ||
2944 | res = ERR_PTR(-ENOMEM); | |
2945 | this.name = name; | |
2946 | this.len = strlen(name); | |
2947 | this.hash = 0; /* will go */ | |
2948 | sb = shm_mnt->mnt_sb; | |
2949 | path.dentry = d_alloc_pseudo(sb, &this); | |
2950 | if (!path.dentry) | |
2951 | goto put_memory; | |
2952 | d_set_d_op(path.dentry, &anon_ops); | |
2953 | path.mnt = mntget(shm_mnt); | |
2954 | ||
2955 | res = ERR_PTR(-ENOSPC); | |
2956 | inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); | |
2957 | if (!inode) | |
2958 | goto put_dentry; | |
2959 | ||
2960 | d_instantiate(path.dentry, inode); | |
2961 | inode->i_size = size; | |
2962 | clear_nlink(inode); /* It is unlinked */ | |
2963 | res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); | |
2964 | if (IS_ERR(res)) | |
2965 | goto put_dentry; | |
2966 | ||
2967 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, | |
2968 | &shmem_file_operations); | |
2969 | if (IS_ERR(res)) | |
2970 | goto put_dentry; | |
2971 | ||
2972 | return res; | |
2973 | ||
2974 | put_dentry: | |
2975 | path_put(&path); | |
2976 | put_memory: | |
2977 | shmem_unacct_size(flags, size); | |
2978 | return res; | |
2979 | } | |
2980 | EXPORT_SYMBOL_GPL(shmem_file_setup); | |
2981 | ||
2982 | /** | |
2983 | * shmem_zero_setup - setup a shared anonymous mapping | |
2984 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff | |
2985 | */ | |
2986 | int shmem_zero_setup(struct vm_area_struct *vma) | |
2987 | { | |
2988 | struct file *file; | |
2989 | loff_t size = vma->vm_end - vma->vm_start; | |
2990 | ||
2991 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); | |
2992 | if (IS_ERR(file)) | |
2993 | return PTR_ERR(file); | |
2994 | ||
2995 | if (vma->vm_file) | |
2996 | fput(vma->vm_file); | |
2997 | vma->vm_file = file; | |
2998 | vma->vm_ops = &shmem_vm_ops; | |
2999 | return 0; | |
3000 | } | |
3001 | ||
3002 | /** | |
3003 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. | |
3004 | * @mapping: the page's address_space | |
3005 | * @index: the page index | |
3006 | * @gfp: the page allocator flags to use if allocating | |
3007 | * | |
3008 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", | |
3009 | * with any new page allocations done using the specified allocation flags. | |
3010 | * But read_cache_page_gfp() uses the ->readpage() method: which does not | |
3011 | * suit tmpfs, since it may have pages in swapcache, and needs to find those | |
3012 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. | |
3013 | * | |
3014 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in | |
3015 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. | |
3016 | */ | |
3017 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, | |
3018 | pgoff_t index, gfp_t gfp) | |
3019 | { | |
3020 | #ifdef CONFIG_SHMEM | |
3021 | struct inode *inode = mapping->host; | |
3022 | struct page *page; | |
3023 | int error; | |
3024 | ||
3025 | BUG_ON(mapping->a_ops != &shmem_aops); | |
3026 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); | |
3027 | if (error) | |
3028 | page = ERR_PTR(error); | |
3029 | else | |
3030 | unlock_page(page); | |
3031 | return page; | |
3032 | #else | |
3033 | /* | |
3034 | * The tiny !SHMEM case uses ramfs without swap | |
3035 | */ | |
3036 | return read_cache_page_gfp(mapping, index, gfp); | |
3037 | #endif | |
3038 | } | |
3039 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |