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1 | /* | |
2 | * Resizable virtual memory filesystem for Linux. | |
3 | * | |
4 | * Copyright (C) 2000 Linus Torvalds. | |
5 | * 2000 Transmeta Corp. | |
6 | * 2000-2001 Christoph Rohland | |
7 | * 2000-2001 SAP AG | |
8 | * 2002 Red Hat Inc. | |
9 | * Copyright (C) 2002-2011 Hugh Dickins. | |
10 | * Copyright (C) 2011 Google Inc. | |
11 | * Copyright (C) 2002-2005 VERITAS Software Corporation. | |
12 | * Copyright (C) 2004 Andi Kleen, SuSE Labs | |
13 | * | |
14 | * Extended attribute support for tmpfs: | |
15 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> | |
16 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> | |
17 | * | |
18 | * tiny-shmem: | |
19 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> | |
20 | * | |
21 | * This file is released under the GPL. | |
22 | */ | |
23 | ||
24 | #include <linux/fs.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/vfs.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/pagemap.h> | |
29 | #include <linux/file.h> | |
30 | #include <linux/mm.h> | |
31 | #include <linux/export.h> | |
32 | #include <linux/swap.h> | |
33 | ||
34 | static struct vfsmount *shm_mnt; | |
35 | ||
36 | #ifdef CONFIG_SHMEM | |
37 | /* | |
38 | * This virtual memory filesystem is heavily based on the ramfs. It | |
39 | * extends ramfs by the ability to use swap and honor resource limits | |
40 | * which makes it a completely usable filesystem. | |
41 | */ | |
42 | ||
43 | #include <linux/xattr.h> | |
44 | #include <linux/exportfs.h> | |
45 | #include <linux/posix_acl.h> | |
46 | #include <linux/generic_acl.h> | |
47 | #include <linux/mman.h> | |
48 | #include <linux/string.h> | |
49 | #include <linux/slab.h> | |
50 | #include <linux/backing-dev.h> | |
51 | #include <linux/shmem_fs.h> | |
52 | #include <linux/writeback.h> | |
53 | #include <linux/blkdev.h> | |
54 | #include <linux/pagevec.h> | |
55 | #include <linux/percpu_counter.h> | |
56 | #include <linux/falloc.h> | |
57 | #include <linux/splice.h> | |
58 | #include <linux/security.h> | |
59 | #include <linux/swapops.h> | |
60 | #include <linux/mempolicy.h> | |
61 | #include <linux/namei.h> | |
62 | #include <linux/ctype.h> | |
63 | #include <linux/migrate.h> | |
64 | #include <linux/highmem.h> | |
65 | #include <linux/seq_file.h> | |
66 | #include <linux/magic.h> | |
67 | ||
68 | #include <asm/uaccess.h> | |
69 | #include <asm/pgtable.h> | |
70 | ||
71 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) | |
72 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) | |
73 | ||
74 | /* Pretend that each entry is of this size in directory's i_size */ | |
75 | #define BOGO_DIRENT_SIZE 20 | |
76 | ||
77 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ | |
78 | #define SHORT_SYMLINK_LEN 128 | |
79 | ||
80 | /* | |
81 | * shmem_fallocate and shmem_writepage communicate via inode->i_private | |
82 | * (with i_mutex making sure that it has only one user at a time): | |
83 | * we would prefer not to enlarge the shmem inode just for that. | |
84 | */ | |
85 | struct shmem_falloc { | |
86 | pgoff_t start; /* start of range currently being fallocated */ | |
87 | pgoff_t next; /* the next page offset to be fallocated */ | |
88 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ | |
89 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ | |
90 | }; | |
91 | ||
92 | /* Flag allocation requirements to shmem_getpage */ | |
93 | enum sgp_type { | |
94 | SGP_READ, /* don't exceed i_size, don't allocate page */ | |
95 | SGP_CACHE, /* don't exceed i_size, may allocate page */ | |
96 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ | |
97 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ | |
98 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ | |
99 | }; | |
100 | ||
101 | #ifdef CONFIG_TMPFS | |
102 | static unsigned long shmem_default_max_blocks(void) | |
103 | { | |
104 | return totalram_pages / 2; | |
105 | } | |
106 | ||
107 | static unsigned long shmem_default_max_inodes(void) | |
108 | { | |
109 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); | |
110 | } | |
111 | #endif | |
112 | ||
113 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); | |
114 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
115 | struct shmem_inode_info *info, pgoff_t index); | |
116 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
117 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); | |
118 | ||
119 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, | |
120 | struct page **pagep, enum sgp_type sgp, int *fault_type) | |
121 | { | |
122 | return shmem_getpage_gfp(inode, index, pagep, sgp, | |
123 | mapping_gfp_mask(inode->i_mapping), fault_type); | |
124 | } | |
125 | ||
126 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) | |
127 | { | |
128 | return sb->s_fs_info; | |
129 | } | |
130 | ||
131 | /* | |
132 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, | |
133 | * for shared memory and for shared anonymous (/dev/zero) mappings | |
134 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), | |
135 | * consistent with the pre-accounting of private mappings ... | |
136 | */ | |
137 | static inline int shmem_acct_size(unsigned long flags, loff_t size) | |
138 | { | |
139 | return (flags & VM_NORESERVE) ? | |
140 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); | |
141 | } | |
142 | ||
143 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) | |
144 | { | |
145 | if (!(flags & VM_NORESERVE)) | |
146 | vm_unacct_memory(VM_ACCT(size)); | |
147 | } | |
148 | ||
149 | /* | |
150 | * ... whereas tmpfs objects are accounted incrementally as | |
151 | * pages are allocated, in order to allow huge sparse files. | |
152 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, | |
153 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. | |
154 | */ | |
155 | static inline int shmem_acct_block(unsigned long flags) | |
156 | { | |
157 | return (flags & VM_NORESERVE) ? | |
158 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; | |
159 | } | |
160 | ||
161 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) | |
162 | { | |
163 | if (flags & VM_NORESERVE) | |
164 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); | |
165 | } | |
166 | ||
167 | static const struct super_operations shmem_ops; | |
168 | static const struct address_space_operations shmem_aops; | |
169 | static const struct file_operations shmem_file_operations; | |
170 | static const struct inode_operations shmem_inode_operations; | |
171 | static const struct inode_operations shmem_dir_inode_operations; | |
172 | static const struct inode_operations shmem_special_inode_operations; | |
173 | static const struct vm_operations_struct shmem_vm_ops; | |
174 | ||
175 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { | |
176 | .ra_pages = 0, /* No readahead */ | |
177 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, | |
178 | }; | |
179 | ||
180 | static LIST_HEAD(shmem_swaplist); | |
181 | static DEFINE_MUTEX(shmem_swaplist_mutex); | |
182 | ||
183 | static int shmem_reserve_inode(struct super_block *sb) | |
184 | { | |
185 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
186 | if (sbinfo->max_inodes) { | |
187 | spin_lock(&sbinfo->stat_lock); | |
188 | if (!sbinfo->free_inodes) { | |
189 | spin_unlock(&sbinfo->stat_lock); | |
190 | return -ENOSPC; | |
191 | } | |
192 | sbinfo->free_inodes--; | |
193 | spin_unlock(&sbinfo->stat_lock); | |
194 | } | |
195 | return 0; | |
196 | } | |
197 | ||
198 | static void shmem_free_inode(struct super_block *sb) | |
199 | { | |
200 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
201 | if (sbinfo->max_inodes) { | |
202 | spin_lock(&sbinfo->stat_lock); | |
203 | sbinfo->free_inodes++; | |
204 | spin_unlock(&sbinfo->stat_lock); | |
205 | } | |
206 | } | |
207 | ||
208 | /** | |
209 | * shmem_recalc_inode - recalculate the block usage of an inode | |
210 | * @inode: inode to recalc | |
211 | * | |
212 | * We have to calculate the free blocks since the mm can drop | |
213 | * undirtied hole pages behind our back. | |
214 | * | |
215 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped | |
216 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) | |
217 | * | |
218 | * It has to be called with the spinlock held. | |
219 | */ | |
220 | static void shmem_recalc_inode(struct inode *inode) | |
221 | { | |
222 | struct shmem_inode_info *info = SHMEM_I(inode); | |
223 | long freed; | |
224 | ||
225 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; | |
226 | if (freed > 0) { | |
227 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
228 | if (sbinfo->max_blocks) | |
229 | percpu_counter_add(&sbinfo->used_blocks, -freed); | |
230 | info->alloced -= freed; | |
231 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; | |
232 | shmem_unacct_blocks(info->flags, freed); | |
233 | } | |
234 | } | |
235 | ||
236 | /* | |
237 | * Replace item expected in radix tree by a new item, while holding tree lock. | |
238 | */ | |
239 | static int shmem_radix_tree_replace(struct address_space *mapping, | |
240 | pgoff_t index, void *expected, void *replacement) | |
241 | { | |
242 | void **pslot; | |
243 | void *item = NULL; | |
244 | ||
245 | VM_BUG_ON(!expected); | |
246 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); | |
247 | if (pslot) | |
248 | item = radix_tree_deref_slot_protected(pslot, | |
249 | &mapping->tree_lock); | |
250 | if (item != expected) | |
251 | return -ENOENT; | |
252 | if (replacement) | |
253 | radix_tree_replace_slot(pslot, replacement); | |
254 | else | |
255 | radix_tree_delete(&mapping->page_tree, index); | |
256 | return 0; | |
257 | } | |
258 | ||
259 | /* | |
260 | * Sometimes, before we decide whether to proceed or to fail, we must check | |
261 | * that an entry was not already brought back from swap by a racing thread. | |
262 | * | |
263 | * Checking page is not enough: by the time a SwapCache page is locked, it | |
264 | * might be reused, and again be SwapCache, using the same swap as before. | |
265 | */ | |
266 | static bool shmem_confirm_swap(struct address_space *mapping, | |
267 | pgoff_t index, swp_entry_t swap) | |
268 | { | |
269 | void *item; | |
270 | ||
271 | rcu_read_lock(); | |
272 | item = radix_tree_lookup(&mapping->page_tree, index); | |
273 | rcu_read_unlock(); | |
274 | return item == swp_to_radix_entry(swap); | |
275 | } | |
276 | ||
277 | /* | |
278 | * Like add_to_page_cache_locked, but error if expected item has gone. | |
279 | */ | |
280 | static int shmem_add_to_page_cache(struct page *page, | |
281 | struct address_space *mapping, | |
282 | pgoff_t index, gfp_t gfp, void *expected) | |
283 | { | |
284 | int error; | |
285 | ||
286 | VM_BUG_ON(!PageLocked(page)); | |
287 | VM_BUG_ON(!PageSwapBacked(page)); | |
288 | ||
289 | page_cache_get(page); | |
290 | page->mapping = mapping; | |
291 | page->index = index; | |
292 | ||
293 | spin_lock_irq(&mapping->tree_lock); | |
294 | if (!expected) | |
295 | error = radix_tree_insert(&mapping->page_tree, index, page); | |
296 | else | |
297 | error = shmem_radix_tree_replace(mapping, index, expected, | |
298 | page); | |
299 | if (!error) { | |
300 | mapping->nrpages++; | |
301 | __inc_zone_page_state(page, NR_FILE_PAGES); | |
302 | __inc_zone_page_state(page, NR_SHMEM); | |
303 | spin_unlock_irq(&mapping->tree_lock); | |
304 | } else { | |
305 | page->mapping = NULL; | |
306 | spin_unlock_irq(&mapping->tree_lock); | |
307 | page_cache_release(page); | |
308 | } | |
309 | return error; | |
310 | } | |
311 | ||
312 | /* | |
313 | * Like delete_from_page_cache, but substitutes swap for page. | |
314 | */ | |
315 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) | |
316 | { | |
317 | struct address_space *mapping = page->mapping; | |
318 | int error; | |
319 | ||
320 | spin_lock_irq(&mapping->tree_lock); | |
321 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); | |
322 | page->mapping = NULL; | |
323 | mapping->nrpages--; | |
324 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
325 | __dec_zone_page_state(page, NR_SHMEM); | |
326 | spin_unlock_irq(&mapping->tree_lock); | |
327 | page_cache_release(page); | |
328 | BUG_ON(error); | |
329 | } | |
330 | ||
331 | /* | |
332 | * Like find_get_pages, but collecting swap entries as well as pages. | |
333 | */ | |
334 | static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, | |
335 | pgoff_t start, unsigned int nr_pages, | |
336 | struct page **pages, pgoff_t *indices) | |
337 | { | |
338 | unsigned int i; | |
339 | unsigned int ret; | |
340 | unsigned int nr_found; | |
341 | ||
342 | rcu_read_lock(); | |
343 | restart: | |
344 | nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, | |
345 | (void ***)pages, indices, start, nr_pages); | |
346 | ret = 0; | |
347 | for (i = 0; i < nr_found; i++) { | |
348 | struct page *page; | |
349 | repeat: | |
350 | page = radix_tree_deref_slot((void **)pages[i]); | |
351 | if (unlikely(!page)) | |
352 | continue; | |
353 | if (radix_tree_exception(page)) { | |
354 | if (radix_tree_deref_retry(page)) | |
355 | goto restart; | |
356 | /* | |
357 | * Otherwise, we must be storing a swap entry | |
358 | * here as an exceptional entry: so return it | |
359 | * without attempting to raise page count. | |
360 | */ | |
361 | goto export; | |
362 | } | |
363 | if (!page_cache_get_speculative(page)) | |
364 | goto repeat; | |
365 | ||
366 | /* Has the page moved? */ | |
367 | if (unlikely(page != *((void **)pages[i]))) { | |
368 | page_cache_release(page); | |
369 | goto repeat; | |
370 | } | |
371 | export: | |
372 | indices[ret] = indices[i]; | |
373 | pages[ret] = page; | |
374 | ret++; | |
375 | } | |
376 | if (unlikely(!ret && nr_found)) | |
377 | goto restart; | |
378 | rcu_read_unlock(); | |
379 | return ret; | |
380 | } | |
381 | ||
382 | /* | |
383 | * Remove swap entry from radix tree, free the swap and its page cache. | |
384 | */ | |
385 | static int shmem_free_swap(struct address_space *mapping, | |
386 | pgoff_t index, void *radswap) | |
387 | { | |
388 | int error; | |
389 | ||
390 | spin_lock_irq(&mapping->tree_lock); | |
391 | error = shmem_radix_tree_replace(mapping, index, radswap, NULL); | |
392 | spin_unlock_irq(&mapping->tree_lock); | |
393 | if (!error) | |
394 | free_swap_and_cache(radix_to_swp_entry(radswap)); | |
395 | return error; | |
396 | } | |
397 | ||
398 | /* | |
399 | * Pagevec may contain swap entries, so shuffle up pages before releasing. | |
400 | */ | |
401 | static void shmem_deswap_pagevec(struct pagevec *pvec) | |
402 | { | |
403 | int i, j; | |
404 | ||
405 | for (i = 0, j = 0; i < pagevec_count(pvec); i++) { | |
406 | struct page *page = pvec->pages[i]; | |
407 | if (!radix_tree_exceptional_entry(page)) | |
408 | pvec->pages[j++] = page; | |
409 | } | |
410 | pvec->nr = j; | |
411 | } | |
412 | ||
413 | /* | |
414 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. | |
415 | */ | |
416 | void shmem_unlock_mapping(struct address_space *mapping) | |
417 | { | |
418 | struct pagevec pvec; | |
419 | pgoff_t indices[PAGEVEC_SIZE]; | |
420 | pgoff_t index = 0; | |
421 | ||
422 | pagevec_init(&pvec, 0); | |
423 | /* | |
424 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. | |
425 | */ | |
426 | while (!mapping_unevictable(mapping)) { | |
427 | /* | |
428 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it | |
429 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. | |
430 | */ | |
431 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
432 | PAGEVEC_SIZE, pvec.pages, indices); | |
433 | if (!pvec.nr) | |
434 | break; | |
435 | index = indices[pvec.nr - 1] + 1; | |
436 | shmem_deswap_pagevec(&pvec); | |
437 | check_move_unevictable_pages(pvec.pages, pvec.nr); | |
438 | pagevec_release(&pvec); | |
439 | cond_resched(); | |
440 | } | |
441 | } | |
442 | ||
443 | /* | |
444 | * Remove range of pages and swap entries from radix tree, and free them. | |
445 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. | |
446 | */ | |
447 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, | |
448 | bool unfalloc) | |
449 | { | |
450 | struct address_space *mapping = inode->i_mapping; | |
451 | struct shmem_inode_info *info = SHMEM_I(inode); | |
452 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
453 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; | |
454 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); | |
455 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); | |
456 | struct pagevec pvec; | |
457 | pgoff_t indices[PAGEVEC_SIZE]; | |
458 | long nr_swaps_freed = 0; | |
459 | pgoff_t index; | |
460 | int i; | |
461 | ||
462 | if (lend == -1) | |
463 | end = -1; /* unsigned, so actually very big */ | |
464 | ||
465 | pagevec_init(&pvec, 0); | |
466 | index = start; | |
467 | while (index < end) { | |
468 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
469 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
470 | pvec.pages, indices); | |
471 | if (!pvec.nr) | |
472 | break; | |
473 | mem_cgroup_uncharge_start(); | |
474 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
475 | struct page *page = pvec.pages[i]; | |
476 | ||
477 | index = indices[i]; | |
478 | if (index >= end) | |
479 | break; | |
480 | ||
481 | if (radix_tree_exceptional_entry(page)) { | |
482 | if (unfalloc) | |
483 | continue; | |
484 | nr_swaps_freed += !shmem_free_swap(mapping, | |
485 | index, page); | |
486 | continue; | |
487 | } | |
488 | ||
489 | if (!trylock_page(page)) | |
490 | continue; | |
491 | if (!unfalloc || !PageUptodate(page)) { | |
492 | if (page->mapping == mapping) { | |
493 | VM_BUG_ON(PageWriteback(page)); | |
494 | truncate_inode_page(mapping, page); | |
495 | } | |
496 | } | |
497 | unlock_page(page); | |
498 | } | |
499 | shmem_deswap_pagevec(&pvec); | |
500 | pagevec_release(&pvec); | |
501 | mem_cgroup_uncharge_end(); | |
502 | cond_resched(); | |
503 | index++; | |
504 | } | |
505 | ||
506 | if (partial_start) { | |
507 | struct page *page = NULL; | |
508 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); | |
509 | if (page) { | |
510 | unsigned int top = PAGE_CACHE_SIZE; | |
511 | if (start > end) { | |
512 | top = partial_end; | |
513 | partial_end = 0; | |
514 | } | |
515 | zero_user_segment(page, partial_start, top); | |
516 | set_page_dirty(page); | |
517 | unlock_page(page); | |
518 | page_cache_release(page); | |
519 | } | |
520 | } | |
521 | if (partial_end) { | |
522 | struct page *page = NULL; | |
523 | shmem_getpage(inode, end, &page, SGP_READ, NULL); | |
524 | if (page) { | |
525 | zero_user_segment(page, 0, partial_end); | |
526 | set_page_dirty(page); | |
527 | unlock_page(page); | |
528 | page_cache_release(page); | |
529 | } | |
530 | } | |
531 | if (start >= end) | |
532 | return; | |
533 | ||
534 | index = start; | |
535 | for ( ; ; ) { | |
536 | cond_resched(); | |
537 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
538 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
539 | pvec.pages, indices); | |
540 | if (!pvec.nr) { | |
541 | if (index == start || unfalloc) | |
542 | break; | |
543 | index = start; | |
544 | continue; | |
545 | } | |
546 | if ((index == start || unfalloc) && indices[0] >= end) { | |
547 | shmem_deswap_pagevec(&pvec); | |
548 | pagevec_release(&pvec); | |
549 | break; | |
550 | } | |
551 | mem_cgroup_uncharge_start(); | |
552 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
553 | struct page *page = pvec.pages[i]; | |
554 | ||
555 | index = indices[i]; | |
556 | if (index >= end) | |
557 | break; | |
558 | ||
559 | if (radix_tree_exceptional_entry(page)) { | |
560 | if (unfalloc) | |
561 | continue; | |
562 | nr_swaps_freed += !shmem_free_swap(mapping, | |
563 | index, page); | |
564 | continue; | |
565 | } | |
566 | ||
567 | lock_page(page); | |
568 | if (!unfalloc || !PageUptodate(page)) { | |
569 | if (page->mapping == mapping) { | |
570 | VM_BUG_ON(PageWriteback(page)); | |
571 | truncate_inode_page(mapping, page); | |
572 | } | |
573 | } | |
574 | unlock_page(page); | |
575 | } | |
576 | shmem_deswap_pagevec(&pvec); | |
577 | pagevec_release(&pvec); | |
578 | mem_cgroup_uncharge_end(); | |
579 | index++; | |
580 | } | |
581 | ||
582 | spin_lock(&info->lock); | |
583 | info->swapped -= nr_swaps_freed; | |
584 | shmem_recalc_inode(inode); | |
585 | spin_unlock(&info->lock); | |
586 | } | |
587 | ||
588 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
589 | { | |
590 | shmem_undo_range(inode, lstart, lend, false); | |
591 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
592 | } | |
593 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
594 | ||
595 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) | |
596 | { | |
597 | struct inode *inode = dentry->d_inode; | |
598 | int error; | |
599 | ||
600 | error = inode_change_ok(inode, attr); | |
601 | if (error) | |
602 | return error; | |
603 | ||
604 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { | |
605 | loff_t oldsize = inode->i_size; | |
606 | loff_t newsize = attr->ia_size; | |
607 | ||
608 | if (newsize != oldsize) { | |
609 | i_size_write(inode, newsize); | |
610 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
611 | } | |
612 | if (newsize < oldsize) { | |
613 | loff_t holebegin = round_up(newsize, PAGE_SIZE); | |
614 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
615 | shmem_truncate_range(inode, newsize, (loff_t)-1); | |
616 | /* unmap again to remove racily COWed private pages */ | |
617 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
618 | } | |
619 | } | |
620 | ||
621 | setattr_copy(inode, attr); | |
622 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
623 | if (attr->ia_valid & ATTR_MODE) | |
624 | error = generic_acl_chmod(inode); | |
625 | #endif | |
626 | return error; | |
627 | } | |
628 | ||
629 | static void shmem_evict_inode(struct inode *inode) | |
630 | { | |
631 | struct shmem_inode_info *info = SHMEM_I(inode); | |
632 | ||
633 | if (inode->i_mapping->a_ops == &shmem_aops) { | |
634 | shmem_unacct_size(info->flags, inode->i_size); | |
635 | inode->i_size = 0; | |
636 | shmem_truncate_range(inode, 0, (loff_t)-1); | |
637 | if (!list_empty(&info->swaplist)) { | |
638 | mutex_lock(&shmem_swaplist_mutex); | |
639 | list_del_init(&info->swaplist); | |
640 | mutex_unlock(&shmem_swaplist_mutex); | |
641 | } | |
642 | } else | |
643 | kfree(info->symlink); | |
644 | ||
645 | simple_xattrs_free(&info->xattrs); | |
646 | WARN_ON(inode->i_blocks); | |
647 | shmem_free_inode(inode->i_sb); | |
648 | clear_inode(inode); | |
649 | } | |
650 | ||
651 | /* | |
652 | * If swap found in inode, free it and move page from swapcache to filecache. | |
653 | */ | |
654 | static int shmem_unuse_inode(struct shmem_inode_info *info, | |
655 | swp_entry_t swap, struct page **pagep) | |
656 | { | |
657 | struct address_space *mapping = info->vfs_inode.i_mapping; | |
658 | void *radswap; | |
659 | pgoff_t index; | |
660 | gfp_t gfp; | |
661 | int error = 0; | |
662 | ||
663 | radswap = swp_to_radix_entry(swap); | |
664 | index = radix_tree_locate_item(&mapping->page_tree, radswap); | |
665 | if (index == -1) | |
666 | return 0; | |
667 | ||
668 | /* | |
669 | * Move _head_ to start search for next from here. | |
670 | * But be careful: shmem_evict_inode checks list_empty without taking | |
671 | * mutex, and there's an instant in list_move_tail when info->swaplist | |
672 | * would appear empty, if it were the only one on shmem_swaplist. | |
673 | */ | |
674 | if (shmem_swaplist.next != &info->swaplist) | |
675 | list_move_tail(&shmem_swaplist, &info->swaplist); | |
676 | ||
677 | gfp = mapping_gfp_mask(mapping); | |
678 | if (shmem_should_replace_page(*pagep, gfp)) { | |
679 | mutex_unlock(&shmem_swaplist_mutex); | |
680 | error = shmem_replace_page(pagep, gfp, info, index); | |
681 | mutex_lock(&shmem_swaplist_mutex); | |
682 | /* | |
683 | * We needed to drop mutex to make that restrictive page | |
684 | * allocation, but the inode might have been freed while we | |
685 | * dropped it: although a racing shmem_evict_inode() cannot | |
686 | * complete without emptying the radix_tree, our page lock | |
687 | * on this swapcache page is not enough to prevent that - | |
688 | * free_swap_and_cache() of our swap entry will only | |
689 | * trylock_page(), removing swap from radix_tree whatever. | |
690 | * | |
691 | * We must not proceed to shmem_add_to_page_cache() if the | |
692 | * inode has been freed, but of course we cannot rely on | |
693 | * inode or mapping or info to check that. However, we can | |
694 | * safely check if our swap entry is still in use (and here | |
695 | * it can't have got reused for another page): if it's still | |
696 | * in use, then the inode cannot have been freed yet, and we | |
697 | * can safely proceed (if it's no longer in use, that tells | |
698 | * nothing about the inode, but we don't need to unuse swap). | |
699 | */ | |
700 | if (!page_swapcount(*pagep)) | |
701 | error = -ENOENT; | |
702 | } | |
703 | ||
704 | /* | |
705 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, | |
706 | * but also to hold up shmem_evict_inode(): so inode cannot be freed | |
707 | * beneath us (pagelock doesn't help until the page is in pagecache). | |
708 | */ | |
709 | if (!error) | |
710 | error = shmem_add_to_page_cache(*pagep, mapping, index, | |
711 | GFP_NOWAIT, radswap); | |
712 | if (error != -ENOMEM) { | |
713 | /* | |
714 | * Truncation and eviction use free_swap_and_cache(), which | |
715 | * only does trylock page: if we raced, best clean up here. | |
716 | */ | |
717 | delete_from_swap_cache(*pagep); | |
718 | set_page_dirty(*pagep); | |
719 | if (!error) { | |
720 | spin_lock(&info->lock); | |
721 | info->swapped--; | |
722 | spin_unlock(&info->lock); | |
723 | swap_free(swap); | |
724 | } | |
725 | error = 1; /* not an error, but entry was found */ | |
726 | } | |
727 | return error; | |
728 | } | |
729 | ||
730 | /* | |
731 | * Search through swapped inodes to find and replace swap by page. | |
732 | */ | |
733 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
734 | { | |
735 | struct list_head *this, *next; | |
736 | struct shmem_inode_info *info; | |
737 | int found = 0; | |
738 | int error = 0; | |
739 | ||
740 | /* | |
741 | * There's a faint possibility that swap page was replaced before | |
742 | * caller locked it: caller will come back later with the right page. | |
743 | */ | |
744 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) | |
745 | goto out; | |
746 | ||
747 | /* | |
748 | * Charge page using GFP_KERNEL while we can wait, before taking | |
749 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). | |
750 | * Charged back to the user (not to caller) when swap account is used. | |
751 | */ | |
752 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); | |
753 | if (error) | |
754 | goto out; | |
755 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ | |
756 | ||
757 | mutex_lock(&shmem_swaplist_mutex); | |
758 | list_for_each_safe(this, next, &shmem_swaplist) { | |
759 | info = list_entry(this, struct shmem_inode_info, swaplist); | |
760 | if (info->swapped) | |
761 | found = shmem_unuse_inode(info, swap, &page); | |
762 | else | |
763 | list_del_init(&info->swaplist); | |
764 | cond_resched(); | |
765 | if (found) | |
766 | break; | |
767 | } | |
768 | mutex_unlock(&shmem_swaplist_mutex); | |
769 | ||
770 | if (found < 0) | |
771 | error = found; | |
772 | out: | |
773 | unlock_page(page); | |
774 | page_cache_release(page); | |
775 | return error; | |
776 | } | |
777 | ||
778 | /* | |
779 | * Move the page from the page cache to the swap cache. | |
780 | */ | |
781 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) | |
782 | { | |
783 | struct shmem_inode_info *info; | |
784 | struct address_space *mapping; | |
785 | struct inode *inode; | |
786 | swp_entry_t swap; | |
787 | pgoff_t index; | |
788 | ||
789 | BUG_ON(!PageLocked(page)); | |
790 | mapping = page->mapping; | |
791 | index = page->index; | |
792 | inode = mapping->host; | |
793 | info = SHMEM_I(inode); | |
794 | if (info->flags & VM_LOCKED) | |
795 | goto redirty; | |
796 | if (!total_swap_pages) | |
797 | goto redirty; | |
798 | ||
799 | /* | |
800 | * shmem_backing_dev_info's capabilities prevent regular writeback or | |
801 | * sync from ever calling shmem_writepage; but a stacking filesystem | |
802 | * might use ->writepage of its underlying filesystem, in which case | |
803 | * tmpfs should write out to swap only in response to memory pressure, | |
804 | * and not for the writeback threads or sync. | |
805 | */ | |
806 | if (!wbc->for_reclaim) { | |
807 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ | |
808 | goto redirty; | |
809 | } | |
810 | ||
811 | /* | |
812 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC | |
813 | * value into swapfile.c, the only way we can correctly account for a | |
814 | * fallocated page arriving here is now to initialize it and write it. | |
815 | * | |
816 | * That's okay for a page already fallocated earlier, but if we have | |
817 | * not yet completed the fallocation, then (a) we want to keep track | |
818 | * of this page in case we have to undo it, and (b) it may not be a | |
819 | * good idea to continue anyway, once we're pushing into swap. So | |
820 | * reactivate the page, and let shmem_fallocate() quit when too many. | |
821 | */ | |
822 | if (!PageUptodate(page)) { | |
823 | if (inode->i_private) { | |
824 | struct shmem_falloc *shmem_falloc; | |
825 | spin_lock(&inode->i_lock); | |
826 | shmem_falloc = inode->i_private; | |
827 | if (shmem_falloc && | |
828 | index >= shmem_falloc->start && | |
829 | index < shmem_falloc->next) | |
830 | shmem_falloc->nr_unswapped++; | |
831 | else | |
832 | shmem_falloc = NULL; | |
833 | spin_unlock(&inode->i_lock); | |
834 | if (shmem_falloc) | |
835 | goto redirty; | |
836 | } | |
837 | clear_highpage(page); | |
838 | flush_dcache_page(page); | |
839 | SetPageUptodate(page); | |
840 | } | |
841 | ||
842 | swap = get_swap_page(); | |
843 | if (!swap.val) | |
844 | goto redirty; | |
845 | ||
846 | /* | |
847 | * Add inode to shmem_unuse()'s list of swapped-out inodes, | |
848 | * if it's not already there. Do it now before the page is | |
849 | * moved to swap cache, when its pagelock no longer protects | |
850 | * the inode from eviction. But don't unlock the mutex until | |
851 | * we've incremented swapped, because shmem_unuse_inode() will | |
852 | * prune a !swapped inode from the swaplist under this mutex. | |
853 | */ | |
854 | mutex_lock(&shmem_swaplist_mutex); | |
855 | if (list_empty(&info->swaplist)) | |
856 | list_add_tail(&info->swaplist, &shmem_swaplist); | |
857 | ||
858 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { | |
859 | swap_shmem_alloc(swap); | |
860 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); | |
861 | ||
862 | spin_lock(&info->lock); | |
863 | info->swapped++; | |
864 | shmem_recalc_inode(inode); | |
865 | spin_unlock(&info->lock); | |
866 | ||
867 | mutex_unlock(&shmem_swaplist_mutex); | |
868 | BUG_ON(page_mapped(page)); | |
869 | swap_writepage(page, wbc); | |
870 | return 0; | |
871 | } | |
872 | ||
873 | mutex_unlock(&shmem_swaplist_mutex); | |
874 | swapcache_free(swap, NULL); | |
875 | redirty: | |
876 | set_page_dirty(page); | |
877 | if (wbc->for_reclaim) | |
878 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ | |
879 | unlock_page(page); | |
880 | return 0; | |
881 | } | |
882 | ||
883 | #ifdef CONFIG_NUMA | |
884 | #ifdef CONFIG_TMPFS | |
885 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
886 | { | |
887 | char buffer[64]; | |
888 | ||
889 | if (!mpol || mpol->mode == MPOL_DEFAULT) | |
890 | return; /* show nothing */ | |
891 | ||
892 | mpol_to_str(buffer, sizeof(buffer), mpol); | |
893 | ||
894 | seq_printf(seq, ",mpol=%s", buffer); | |
895 | } | |
896 | ||
897 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
898 | { | |
899 | struct mempolicy *mpol = NULL; | |
900 | if (sbinfo->mpol) { | |
901 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ | |
902 | mpol = sbinfo->mpol; | |
903 | mpol_get(mpol); | |
904 | spin_unlock(&sbinfo->stat_lock); | |
905 | } | |
906 | return mpol; | |
907 | } | |
908 | #endif /* CONFIG_TMPFS */ | |
909 | ||
910 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
911 | struct shmem_inode_info *info, pgoff_t index) | |
912 | { | |
913 | struct vm_area_struct pvma; | |
914 | struct page *page; | |
915 | ||
916 | /* Create a pseudo vma that just contains the policy */ | |
917 | pvma.vm_start = 0; | |
918 | /* Bias interleave by inode number to distribute better across nodes */ | |
919 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
920 | pvma.vm_ops = NULL; | |
921 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
922 | ||
923 | page = swapin_readahead(swap, gfp, &pvma, 0); | |
924 | ||
925 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
926 | mpol_cond_put(pvma.vm_policy); | |
927 | ||
928 | return page; | |
929 | } | |
930 | ||
931 | static struct page *shmem_alloc_page(gfp_t gfp, | |
932 | struct shmem_inode_info *info, pgoff_t index) | |
933 | { | |
934 | struct vm_area_struct pvma; | |
935 | struct page *page; | |
936 | ||
937 | /* Create a pseudo vma that just contains the policy */ | |
938 | pvma.vm_start = 0; | |
939 | /* Bias interleave by inode number to distribute better across nodes */ | |
940 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
941 | pvma.vm_ops = NULL; | |
942 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
943 | ||
944 | page = alloc_page_vma(gfp, &pvma, 0); | |
945 | ||
946 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
947 | mpol_cond_put(pvma.vm_policy); | |
948 | ||
949 | return page; | |
950 | } | |
951 | #else /* !CONFIG_NUMA */ | |
952 | #ifdef CONFIG_TMPFS | |
953 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
954 | { | |
955 | } | |
956 | #endif /* CONFIG_TMPFS */ | |
957 | ||
958 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
959 | struct shmem_inode_info *info, pgoff_t index) | |
960 | { | |
961 | return swapin_readahead(swap, gfp, NULL, 0); | |
962 | } | |
963 | ||
964 | static inline struct page *shmem_alloc_page(gfp_t gfp, | |
965 | struct shmem_inode_info *info, pgoff_t index) | |
966 | { | |
967 | return alloc_page(gfp); | |
968 | } | |
969 | #endif /* CONFIG_NUMA */ | |
970 | ||
971 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) | |
972 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
973 | { | |
974 | return NULL; | |
975 | } | |
976 | #endif | |
977 | ||
978 | /* | |
979 | * When a page is moved from swapcache to shmem filecache (either by the | |
980 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of | |
981 | * shmem_unuse_inode()), it may have been read in earlier from swap, in | |
982 | * ignorance of the mapping it belongs to. If that mapping has special | |
983 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), | |
984 | * we may need to copy to a suitable page before moving to filecache. | |
985 | * | |
986 | * In a future release, this may well be extended to respect cpuset and | |
987 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); | |
988 | * but for now it is a simple matter of zone. | |
989 | */ | |
990 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) | |
991 | { | |
992 | return page_zonenum(page) > gfp_zone(gfp); | |
993 | } | |
994 | ||
995 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
996 | struct shmem_inode_info *info, pgoff_t index) | |
997 | { | |
998 | struct page *oldpage, *newpage; | |
999 | struct address_space *swap_mapping; | |
1000 | pgoff_t swap_index; | |
1001 | int error; | |
1002 | ||
1003 | oldpage = *pagep; | |
1004 | swap_index = page_private(oldpage); | |
1005 | swap_mapping = page_mapping(oldpage); | |
1006 | ||
1007 | /* | |
1008 | * We have arrived here because our zones are constrained, so don't | |
1009 | * limit chance of success by further cpuset and node constraints. | |
1010 | */ | |
1011 | gfp &= ~GFP_CONSTRAINT_MASK; | |
1012 | newpage = shmem_alloc_page(gfp, info, index); | |
1013 | if (!newpage) | |
1014 | return -ENOMEM; | |
1015 | ||
1016 | page_cache_get(newpage); | |
1017 | copy_highpage(newpage, oldpage); | |
1018 | flush_dcache_page(newpage); | |
1019 | ||
1020 | __set_page_locked(newpage); | |
1021 | SetPageUptodate(newpage); | |
1022 | SetPageSwapBacked(newpage); | |
1023 | set_page_private(newpage, swap_index); | |
1024 | SetPageSwapCache(newpage); | |
1025 | ||
1026 | /* | |
1027 | * Our caller will very soon move newpage out of swapcache, but it's | |
1028 | * a nice clean interface for us to replace oldpage by newpage there. | |
1029 | */ | |
1030 | spin_lock_irq(&swap_mapping->tree_lock); | |
1031 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, | |
1032 | newpage); | |
1033 | if (!error) { | |
1034 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
1035 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); | |
1036 | } | |
1037 | spin_unlock_irq(&swap_mapping->tree_lock); | |
1038 | ||
1039 | if (unlikely(error)) { | |
1040 | /* | |
1041 | * Is this possible? I think not, now that our callers check | |
1042 | * both PageSwapCache and page_private after getting page lock; | |
1043 | * but be defensive. Reverse old to newpage for clear and free. | |
1044 | */ | |
1045 | oldpage = newpage; | |
1046 | } else { | |
1047 | mem_cgroup_replace_page_cache(oldpage, newpage); | |
1048 | lru_cache_add_anon(newpage); | |
1049 | *pagep = newpage; | |
1050 | } | |
1051 | ||
1052 | ClearPageSwapCache(oldpage); | |
1053 | set_page_private(oldpage, 0); | |
1054 | ||
1055 | unlock_page(oldpage); | |
1056 | page_cache_release(oldpage); | |
1057 | page_cache_release(oldpage); | |
1058 | return error; | |
1059 | } | |
1060 | ||
1061 | /* | |
1062 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate | |
1063 | * | |
1064 | * If we allocate a new one we do not mark it dirty. That's up to the | |
1065 | * vm. If we swap it in we mark it dirty since we also free the swap | |
1066 | * entry since a page cannot live in both the swap and page cache | |
1067 | */ | |
1068 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
1069 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) | |
1070 | { | |
1071 | struct address_space *mapping = inode->i_mapping; | |
1072 | struct shmem_inode_info *info; | |
1073 | struct shmem_sb_info *sbinfo; | |
1074 | struct page *page; | |
1075 | swp_entry_t swap; | |
1076 | int error; | |
1077 | int once = 0; | |
1078 | int alloced = 0; | |
1079 | ||
1080 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) | |
1081 | return -EFBIG; | |
1082 | repeat: | |
1083 | swap.val = 0; | |
1084 | page = find_lock_page(mapping, index); | |
1085 | if (radix_tree_exceptional_entry(page)) { | |
1086 | swap = radix_to_swp_entry(page); | |
1087 | page = NULL; | |
1088 | } | |
1089 | ||
1090 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1091 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1092 | error = -EINVAL; | |
1093 | goto failed; | |
1094 | } | |
1095 | ||
1096 | /* fallocated page? */ | |
1097 | if (page && !PageUptodate(page)) { | |
1098 | if (sgp != SGP_READ) | |
1099 | goto clear; | |
1100 | unlock_page(page); | |
1101 | page_cache_release(page); | |
1102 | page = NULL; | |
1103 | } | |
1104 | if (page || (sgp == SGP_READ && !swap.val)) { | |
1105 | *pagep = page; | |
1106 | return 0; | |
1107 | } | |
1108 | ||
1109 | /* | |
1110 | * Fast cache lookup did not find it: | |
1111 | * bring it back from swap or allocate. | |
1112 | */ | |
1113 | info = SHMEM_I(inode); | |
1114 | sbinfo = SHMEM_SB(inode->i_sb); | |
1115 | ||
1116 | if (swap.val) { | |
1117 | /* Look it up and read it in.. */ | |
1118 | page = lookup_swap_cache(swap); | |
1119 | if (!page) { | |
1120 | /* here we actually do the io */ | |
1121 | if (fault_type) | |
1122 | *fault_type |= VM_FAULT_MAJOR; | |
1123 | page = shmem_swapin(swap, gfp, info, index); | |
1124 | if (!page) { | |
1125 | error = -ENOMEM; | |
1126 | goto failed; | |
1127 | } | |
1128 | } | |
1129 | ||
1130 | /* We have to do this with page locked to prevent races */ | |
1131 | lock_page(page); | |
1132 | if (!PageSwapCache(page) || page_private(page) != swap.val || | |
1133 | !shmem_confirm_swap(mapping, index, swap)) { | |
1134 | error = -EEXIST; /* try again */ | |
1135 | goto unlock; | |
1136 | } | |
1137 | if (!PageUptodate(page)) { | |
1138 | error = -EIO; | |
1139 | goto failed; | |
1140 | } | |
1141 | wait_on_page_writeback(page); | |
1142 | ||
1143 | if (shmem_should_replace_page(page, gfp)) { | |
1144 | error = shmem_replace_page(&page, gfp, info, index); | |
1145 | if (error) | |
1146 | goto failed; | |
1147 | } | |
1148 | ||
1149 | error = mem_cgroup_cache_charge(page, current->mm, | |
1150 | gfp & GFP_RECLAIM_MASK); | |
1151 | if (!error) { | |
1152 | error = shmem_add_to_page_cache(page, mapping, index, | |
1153 | gfp, swp_to_radix_entry(swap)); | |
1154 | /* | |
1155 | * We already confirmed swap under page lock, and make | |
1156 | * no memory allocation here, so usually no possibility | |
1157 | * of error; but free_swap_and_cache() only trylocks a | |
1158 | * page, so it is just possible that the entry has been | |
1159 | * truncated or holepunched since swap was confirmed. | |
1160 | * shmem_undo_range() will have done some of the | |
1161 | * unaccounting, now delete_from_swap_cache() will do | |
1162 | * the rest (including mem_cgroup_uncharge_swapcache). | |
1163 | * Reset swap.val? No, leave it so "failed" goes back to | |
1164 | * "repeat": reading a hole and writing should succeed. | |
1165 | */ | |
1166 | if (error) | |
1167 | delete_from_swap_cache(page); | |
1168 | } | |
1169 | if (error) | |
1170 | goto failed; | |
1171 | ||
1172 | spin_lock(&info->lock); | |
1173 | info->swapped--; | |
1174 | shmem_recalc_inode(inode); | |
1175 | spin_unlock(&info->lock); | |
1176 | ||
1177 | delete_from_swap_cache(page); | |
1178 | set_page_dirty(page); | |
1179 | swap_free(swap); | |
1180 | ||
1181 | } else { | |
1182 | if (shmem_acct_block(info->flags)) { | |
1183 | error = -ENOSPC; | |
1184 | goto failed; | |
1185 | } | |
1186 | if (sbinfo->max_blocks) { | |
1187 | if (percpu_counter_compare(&sbinfo->used_blocks, | |
1188 | sbinfo->max_blocks) >= 0) { | |
1189 | error = -ENOSPC; | |
1190 | goto unacct; | |
1191 | } | |
1192 | percpu_counter_inc(&sbinfo->used_blocks); | |
1193 | } | |
1194 | ||
1195 | page = shmem_alloc_page(gfp, info, index); | |
1196 | if (!page) { | |
1197 | error = -ENOMEM; | |
1198 | goto decused; | |
1199 | } | |
1200 | ||
1201 | SetPageSwapBacked(page); | |
1202 | __set_page_locked(page); | |
1203 | error = mem_cgroup_cache_charge(page, current->mm, | |
1204 | gfp & GFP_RECLAIM_MASK); | |
1205 | if (error) | |
1206 | goto decused; | |
1207 | error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); | |
1208 | if (!error) { | |
1209 | error = shmem_add_to_page_cache(page, mapping, index, | |
1210 | gfp, NULL); | |
1211 | radix_tree_preload_end(); | |
1212 | } | |
1213 | if (error) { | |
1214 | mem_cgroup_uncharge_cache_page(page); | |
1215 | goto decused; | |
1216 | } | |
1217 | lru_cache_add_anon(page); | |
1218 | ||
1219 | spin_lock(&info->lock); | |
1220 | info->alloced++; | |
1221 | inode->i_blocks += BLOCKS_PER_PAGE; | |
1222 | shmem_recalc_inode(inode); | |
1223 | spin_unlock(&info->lock); | |
1224 | alloced = true; | |
1225 | ||
1226 | /* | |
1227 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. | |
1228 | */ | |
1229 | if (sgp == SGP_FALLOC) | |
1230 | sgp = SGP_WRITE; | |
1231 | clear: | |
1232 | /* | |
1233 | * Let SGP_WRITE caller clear ends if write does not fill page; | |
1234 | * but SGP_FALLOC on a page fallocated earlier must initialize | |
1235 | * it now, lest undo on failure cancel our earlier guarantee. | |
1236 | */ | |
1237 | if (sgp != SGP_WRITE) { | |
1238 | clear_highpage(page); | |
1239 | flush_dcache_page(page); | |
1240 | SetPageUptodate(page); | |
1241 | } | |
1242 | if (sgp == SGP_DIRTY) | |
1243 | set_page_dirty(page); | |
1244 | } | |
1245 | ||
1246 | /* Perhaps the file has been truncated since we checked */ | |
1247 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1248 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1249 | error = -EINVAL; | |
1250 | if (alloced) | |
1251 | goto trunc; | |
1252 | else | |
1253 | goto failed; | |
1254 | } | |
1255 | *pagep = page; | |
1256 | return 0; | |
1257 | ||
1258 | /* | |
1259 | * Error recovery. | |
1260 | */ | |
1261 | trunc: | |
1262 | info = SHMEM_I(inode); | |
1263 | ClearPageDirty(page); | |
1264 | delete_from_page_cache(page); | |
1265 | spin_lock(&info->lock); | |
1266 | info->alloced--; | |
1267 | inode->i_blocks -= BLOCKS_PER_PAGE; | |
1268 | spin_unlock(&info->lock); | |
1269 | decused: | |
1270 | sbinfo = SHMEM_SB(inode->i_sb); | |
1271 | if (sbinfo->max_blocks) | |
1272 | percpu_counter_add(&sbinfo->used_blocks, -1); | |
1273 | unacct: | |
1274 | shmem_unacct_blocks(info->flags, 1); | |
1275 | failed: | |
1276 | if (swap.val && error != -EINVAL && | |
1277 | !shmem_confirm_swap(mapping, index, swap)) | |
1278 | error = -EEXIST; | |
1279 | unlock: | |
1280 | if (page) { | |
1281 | unlock_page(page); | |
1282 | page_cache_release(page); | |
1283 | } | |
1284 | if (error == -ENOSPC && !once++) { | |
1285 | info = SHMEM_I(inode); | |
1286 | spin_lock(&info->lock); | |
1287 | shmem_recalc_inode(inode); | |
1288 | spin_unlock(&info->lock); | |
1289 | goto repeat; | |
1290 | } | |
1291 | if (error == -EEXIST) /* from above or from radix_tree_insert */ | |
1292 | goto repeat; | |
1293 | return error; | |
1294 | } | |
1295 | ||
1296 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
1297 | { | |
1298 | struct inode *inode = file_inode(vma->vm_file); | |
1299 | int error; | |
1300 | int ret = VM_FAULT_LOCKED; | |
1301 | ||
1302 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); | |
1303 | if (error) | |
1304 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); | |
1305 | ||
1306 | if (ret & VM_FAULT_MAJOR) { | |
1307 | count_vm_event(PGMAJFAULT); | |
1308 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
1309 | } | |
1310 | return ret; | |
1311 | } | |
1312 | ||
1313 | #ifdef CONFIG_NUMA | |
1314 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) | |
1315 | { | |
1316 | struct inode *inode = file_inode(vma->vm_file); | |
1317 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); | |
1318 | } | |
1319 | ||
1320 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, | |
1321 | unsigned long addr) | |
1322 | { | |
1323 | struct inode *inode = file_inode(vma->vm_file); | |
1324 | pgoff_t index; | |
1325 | ||
1326 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
1327 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); | |
1328 | } | |
1329 | #endif | |
1330 | ||
1331 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
1332 | { | |
1333 | struct inode *inode = file_inode(file); | |
1334 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1335 | int retval = -ENOMEM; | |
1336 | ||
1337 | spin_lock(&info->lock); | |
1338 | if (lock && !(info->flags & VM_LOCKED)) { | |
1339 | if (!user_shm_lock(inode->i_size, user)) | |
1340 | goto out_nomem; | |
1341 | info->flags |= VM_LOCKED; | |
1342 | mapping_set_unevictable(file->f_mapping); | |
1343 | } | |
1344 | if (!lock && (info->flags & VM_LOCKED) && user) { | |
1345 | user_shm_unlock(inode->i_size, user); | |
1346 | info->flags &= ~VM_LOCKED; | |
1347 | mapping_clear_unevictable(file->f_mapping); | |
1348 | } | |
1349 | retval = 0; | |
1350 | ||
1351 | out_nomem: | |
1352 | spin_unlock(&info->lock); | |
1353 | return retval; | |
1354 | } | |
1355 | ||
1356 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) | |
1357 | { | |
1358 | file_accessed(file); | |
1359 | vma->vm_ops = &shmem_vm_ops; | |
1360 | return 0; | |
1361 | } | |
1362 | ||
1363 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, | |
1364 | umode_t mode, dev_t dev, unsigned long flags) | |
1365 | { | |
1366 | struct inode *inode; | |
1367 | struct shmem_inode_info *info; | |
1368 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
1369 | ||
1370 | if (shmem_reserve_inode(sb)) | |
1371 | return NULL; | |
1372 | ||
1373 | inode = new_inode(sb); | |
1374 | if (inode) { | |
1375 | inode->i_ino = get_next_ino(); | |
1376 | inode_init_owner(inode, dir, mode); | |
1377 | inode->i_blocks = 0; | |
1378 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; | |
1379 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
1380 | inode->i_generation = get_seconds(); | |
1381 | info = SHMEM_I(inode); | |
1382 | memset(info, 0, (char *)inode - (char *)info); | |
1383 | spin_lock_init(&info->lock); | |
1384 | info->flags = flags & VM_NORESERVE; | |
1385 | INIT_LIST_HEAD(&info->swaplist); | |
1386 | simple_xattrs_init(&info->xattrs); | |
1387 | cache_no_acl(inode); | |
1388 | ||
1389 | switch (mode & S_IFMT) { | |
1390 | default: | |
1391 | inode->i_op = &shmem_special_inode_operations; | |
1392 | init_special_inode(inode, mode, dev); | |
1393 | break; | |
1394 | case S_IFREG: | |
1395 | inode->i_mapping->a_ops = &shmem_aops; | |
1396 | inode->i_op = &shmem_inode_operations; | |
1397 | inode->i_fop = &shmem_file_operations; | |
1398 | mpol_shared_policy_init(&info->policy, | |
1399 | shmem_get_sbmpol(sbinfo)); | |
1400 | break; | |
1401 | case S_IFDIR: | |
1402 | inc_nlink(inode); | |
1403 | /* Some things misbehave if size == 0 on a directory */ | |
1404 | inode->i_size = 2 * BOGO_DIRENT_SIZE; | |
1405 | inode->i_op = &shmem_dir_inode_operations; | |
1406 | inode->i_fop = &simple_dir_operations; | |
1407 | break; | |
1408 | case S_IFLNK: | |
1409 | /* | |
1410 | * Must not load anything in the rbtree, | |
1411 | * mpol_free_shared_policy will not be called. | |
1412 | */ | |
1413 | mpol_shared_policy_init(&info->policy, NULL); | |
1414 | break; | |
1415 | } | |
1416 | } else | |
1417 | shmem_free_inode(sb); | |
1418 | return inode; | |
1419 | } | |
1420 | ||
1421 | #ifdef CONFIG_TMPFS | |
1422 | static const struct inode_operations shmem_symlink_inode_operations; | |
1423 | static const struct inode_operations shmem_short_symlink_operations; | |
1424 | ||
1425 | #ifdef CONFIG_TMPFS_XATTR | |
1426 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); | |
1427 | #else | |
1428 | #define shmem_initxattrs NULL | |
1429 | #endif | |
1430 | ||
1431 | static int | |
1432 | shmem_write_begin(struct file *file, struct address_space *mapping, | |
1433 | loff_t pos, unsigned len, unsigned flags, | |
1434 | struct page **pagep, void **fsdata) | |
1435 | { | |
1436 | struct inode *inode = mapping->host; | |
1437 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
1438 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); | |
1439 | } | |
1440 | ||
1441 | static int | |
1442 | shmem_write_end(struct file *file, struct address_space *mapping, | |
1443 | loff_t pos, unsigned len, unsigned copied, | |
1444 | struct page *page, void *fsdata) | |
1445 | { | |
1446 | struct inode *inode = mapping->host; | |
1447 | ||
1448 | if (pos + copied > inode->i_size) | |
1449 | i_size_write(inode, pos + copied); | |
1450 | ||
1451 | if (!PageUptodate(page)) { | |
1452 | if (copied < PAGE_CACHE_SIZE) { | |
1453 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
1454 | zero_user_segments(page, 0, from, | |
1455 | from + copied, PAGE_CACHE_SIZE); | |
1456 | } | |
1457 | SetPageUptodate(page); | |
1458 | } | |
1459 | set_page_dirty(page); | |
1460 | unlock_page(page); | |
1461 | page_cache_release(page); | |
1462 | ||
1463 | return copied; | |
1464 | } | |
1465 | ||
1466 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) | |
1467 | { | |
1468 | struct inode *inode = file_inode(filp); | |
1469 | struct address_space *mapping = inode->i_mapping; | |
1470 | pgoff_t index; | |
1471 | unsigned long offset; | |
1472 | enum sgp_type sgp = SGP_READ; | |
1473 | ||
1474 | /* | |
1475 | * Might this read be for a stacking filesystem? Then when reading | |
1476 | * holes of a sparse file, we actually need to allocate those pages, | |
1477 | * and even mark them dirty, so it cannot exceed the max_blocks limit. | |
1478 | */ | |
1479 | if (segment_eq(get_fs(), KERNEL_DS)) | |
1480 | sgp = SGP_DIRTY; | |
1481 | ||
1482 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1483 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1484 | ||
1485 | for (;;) { | |
1486 | struct page *page = NULL; | |
1487 | pgoff_t end_index; | |
1488 | unsigned long nr, ret; | |
1489 | loff_t i_size = i_size_read(inode); | |
1490 | ||
1491 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1492 | if (index > end_index) | |
1493 | break; | |
1494 | if (index == end_index) { | |
1495 | nr = i_size & ~PAGE_CACHE_MASK; | |
1496 | if (nr <= offset) | |
1497 | break; | |
1498 | } | |
1499 | ||
1500 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); | |
1501 | if (desc->error) { | |
1502 | if (desc->error == -EINVAL) | |
1503 | desc->error = 0; | |
1504 | break; | |
1505 | } | |
1506 | if (page) | |
1507 | unlock_page(page); | |
1508 | ||
1509 | /* | |
1510 | * We must evaluate after, since reads (unlike writes) | |
1511 | * are called without i_mutex protection against truncate | |
1512 | */ | |
1513 | nr = PAGE_CACHE_SIZE; | |
1514 | i_size = i_size_read(inode); | |
1515 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1516 | if (index == end_index) { | |
1517 | nr = i_size & ~PAGE_CACHE_MASK; | |
1518 | if (nr <= offset) { | |
1519 | if (page) | |
1520 | page_cache_release(page); | |
1521 | break; | |
1522 | } | |
1523 | } | |
1524 | nr -= offset; | |
1525 | ||
1526 | if (page) { | |
1527 | /* | |
1528 | * If users can be writing to this page using arbitrary | |
1529 | * virtual addresses, take care about potential aliasing | |
1530 | * before reading the page on the kernel side. | |
1531 | */ | |
1532 | if (mapping_writably_mapped(mapping)) | |
1533 | flush_dcache_page(page); | |
1534 | /* | |
1535 | * Mark the page accessed if we read the beginning. | |
1536 | */ | |
1537 | if (!offset) | |
1538 | mark_page_accessed(page); | |
1539 | } else { | |
1540 | page = ZERO_PAGE(0); | |
1541 | page_cache_get(page); | |
1542 | } | |
1543 | ||
1544 | /* | |
1545 | * Ok, we have the page, and it's up-to-date, so | |
1546 | * now we can copy it to user space... | |
1547 | * | |
1548 | * The actor routine returns how many bytes were actually used.. | |
1549 | * NOTE! This may not be the same as how much of a user buffer | |
1550 | * we filled up (we may be padding etc), so we can only update | |
1551 | * "pos" here (the actor routine has to update the user buffer | |
1552 | * pointers and the remaining count). | |
1553 | */ | |
1554 | ret = actor(desc, page, offset, nr); | |
1555 | offset += ret; | |
1556 | index += offset >> PAGE_CACHE_SHIFT; | |
1557 | offset &= ~PAGE_CACHE_MASK; | |
1558 | ||
1559 | page_cache_release(page); | |
1560 | if (ret != nr || !desc->count) | |
1561 | break; | |
1562 | ||
1563 | cond_resched(); | |
1564 | } | |
1565 | ||
1566 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
1567 | file_accessed(filp); | |
1568 | } | |
1569 | ||
1570 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, | |
1571 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) | |
1572 | { | |
1573 | struct file *filp = iocb->ki_filp; | |
1574 | ssize_t retval; | |
1575 | unsigned long seg; | |
1576 | size_t count; | |
1577 | loff_t *ppos = &iocb->ki_pos; | |
1578 | ||
1579 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); | |
1580 | if (retval) | |
1581 | return retval; | |
1582 | ||
1583 | for (seg = 0; seg < nr_segs; seg++) { | |
1584 | read_descriptor_t desc; | |
1585 | ||
1586 | desc.written = 0; | |
1587 | desc.arg.buf = iov[seg].iov_base; | |
1588 | desc.count = iov[seg].iov_len; | |
1589 | if (desc.count == 0) | |
1590 | continue; | |
1591 | desc.error = 0; | |
1592 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); | |
1593 | retval += desc.written; | |
1594 | if (desc.error) { | |
1595 | retval = retval ?: desc.error; | |
1596 | break; | |
1597 | } | |
1598 | if (desc.count > 0) | |
1599 | break; | |
1600 | } | |
1601 | return retval; | |
1602 | } | |
1603 | ||
1604 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, | |
1605 | struct pipe_inode_info *pipe, size_t len, | |
1606 | unsigned int flags) | |
1607 | { | |
1608 | struct address_space *mapping = in->f_mapping; | |
1609 | struct inode *inode = mapping->host; | |
1610 | unsigned int loff, nr_pages, req_pages; | |
1611 | struct page *pages[PIPE_DEF_BUFFERS]; | |
1612 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1613 | struct page *page; | |
1614 | pgoff_t index, end_index; | |
1615 | loff_t isize, left; | |
1616 | int error, page_nr; | |
1617 | struct splice_pipe_desc spd = { | |
1618 | .pages = pages, | |
1619 | .partial = partial, | |
1620 | .nr_pages_max = PIPE_DEF_BUFFERS, | |
1621 | .flags = flags, | |
1622 | .ops = &page_cache_pipe_buf_ops, | |
1623 | .spd_release = spd_release_page, | |
1624 | }; | |
1625 | ||
1626 | isize = i_size_read(inode); | |
1627 | if (unlikely(*ppos >= isize)) | |
1628 | return 0; | |
1629 | ||
1630 | left = isize - *ppos; | |
1631 | if (unlikely(left < len)) | |
1632 | len = left; | |
1633 | ||
1634 | if (splice_grow_spd(pipe, &spd)) | |
1635 | return -ENOMEM; | |
1636 | ||
1637 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1638 | loff = *ppos & ~PAGE_CACHE_MASK; | |
1639 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1640 | nr_pages = min(req_pages, pipe->buffers); | |
1641 | ||
1642 | spd.nr_pages = find_get_pages_contig(mapping, index, | |
1643 | nr_pages, spd.pages); | |
1644 | index += spd.nr_pages; | |
1645 | error = 0; | |
1646 | ||
1647 | while (spd.nr_pages < nr_pages) { | |
1648 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); | |
1649 | if (error) | |
1650 | break; | |
1651 | unlock_page(page); | |
1652 | spd.pages[spd.nr_pages++] = page; | |
1653 | index++; | |
1654 | } | |
1655 | ||
1656 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1657 | nr_pages = spd.nr_pages; | |
1658 | spd.nr_pages = 0; | |
1659 | ||
1660 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
1661 | unsigned int this_len; | |
1662 | ||
1663 | if (!len) | |
1664 | break; | |
1665 | ||
1666 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
1667 | page = spd.pages[page_nr]; | |
1668 | ||
1669 | if (!PageUptodate(page) || page->mapping != mapping) { | |
1670 | error = shmem_getpage(inode, index, &page, | |
1671 | SGP_CACHE, NULL); | |
1672 | if (error) | |
1673 | break; | |
1674 | unlock_page(page); | |
1675 | page_cache_release(spd.pages[page_nr]); | |
1676 | spd.pages[page_nr] = page; | |
1677 | } | |
1678 | ||
1679 | isize = i_size_read(inode); | |
1680 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1681 | if (unlikely(!isize || index > end_index)) | |
1682 | break; | |
1683 | ||
1684 | if (end_index == index) { | |
1685 | unsigned int plen; | |
1686 | ||
1687 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1688 | if (plen <= loff) | |
1689 | break; | |
1690 | ||
1691 | this_len = min(this_len, plen - loff); | |
1692 | len = this_len; | |
1693 | } | |
1694 | ||
1695 | spd.partial[page_nr].offset = loff; | |
1696 | spd.partial[page_nr].len = this_len; | |
1697 | len -= this_len; | |
1698 | loff = 0; | |
1699 | spd.nr_pages++; | |
1700 | index++; | |
1701 | } | |
1702 | ||
1703 | while (page_nr < nr_pages) | |
1704 | page_cache_release(spd.pages[page_nr++]); | |
1705 | ||
1706 | if (spd.nr_pages) | |
1707 | error = splice_to_pipe(pipe, &spd); | |
1708 | ||
1709 | splice_shrink_spd(&spd); | |
1710 | ||
1711 | if (error > 0) { | |
1712 | *ppos += error; | |
1713 | file_accessed(in); | |
1714 | } | |
1715 | return error; | |
1716 | } | |
1717 | ||
1718 | /* | |
1719 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. | |
1720 | */ | |
1721 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, | |
1722 | pgoff_t index, pgoff_t end, int whence) | |
1723 | { | |
1724 | struct page *page; | |
1725 | struct pagevec pvec; | |
1726 | pgoff_t indices[PAGEVEC_SIZE]; | |
1727 | bool done = false; | |
1728 | int i; | |
1729 | ||
1730 | pagevec_init(&pvec, 0); | |
1731 | pvec.nr = 1; /* start small: we may be there already */ | |
1732 | while (!done) { | |
1733 | pvec.nr = shmem_find_get_pages_and_swap(mapping, index, | |
1734 | pvec.nr, pvec.pages, indices); | |
1735 | if (!pvec.nr) { | |
1736 | if (whence == SEEK_DATA) | |
1737 | index = end; | |
1738 | break; | |
1739 | } | |
1740 | for (i = 0; i < pvec.nr; i++, index++) { | |
1741 | if (index < indices[i]) { | |
1742 | if (whence == SEEK_HOLE) { | |
1743 | done = true; | |
1744 | break; | |
1745 | } | |
1746 | index = indices[i]; | |
1747 | } | |
1748 | page = pvec.pages[i]; | |
1749 | if (page && !radix_tree_exceptional_entry(page)) { | |
1750 | if (!PageUptodate(page)) | |
1751 | page = NULL; | |
1752 | } | |
1753 | if (index >= end || | |
1754 | (page && whence == SEEK_DATA) || | |
1755 | (!page && whence == SEEK_HOLE)) { | |
1756 | done = true; | |
1757 | break; | |
1758 | } | |
1759 | } | |
1760 | shmem_deswap_pagevec(&pvec); | |
1761 | pagevec_release(&pvec); | |
1762 | pvec.nr = PAGEVEC_SIZE; | |
1763 | cond_resched(); | |
1764 | } | |
1765 | return index; | |
1766 | } | |
1767 | ||
1768 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) | |
1769 | { | |
1770 | struct address_space *mapping = file->f_mapping; | |
1771 | struct inode *inode = mapping->host; | |
1772 | pgoff_t start, end; | |
1773 | loff_t new_offset; | |
1774 | ||
1775 | if (whence != SEEK_DATA && whence != SEEK_HOLE) | |
1776 | return generic_file_llseek_size(file, offset, whence, | |
1777 | MAX_LFS_FILESIZE, i_size_read(inode)); | |
1778 | mutex_lock(&inode->i_mutex); | |
1779 | /* We're holding i_mutex so we can access i_size directly */ | |
1780 | ||
1781 | if (offset < 0) | |
1782 | offset = -EINVAL; | |
1783 | else if (offset >= inode->i_size) | |
1784 | offset = -ENXIO; | |
1785 | else { | |
1786 | start = offset >> PAGE_CACHE_SHIFT; | |
1787 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1788 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); | |
1789 | new_offset <<= PAGE_CACHE_SHIFT; | |
1790 | if (new_offset > offset) { | |
1791 | if (new_offset < inode->i_size) | |
1792 | offset = new_offset; | |
1793 | else if (whence == SEEK_DATA) | |
1794 | offset = -ENXIO; | |
1795 | else | |
1796 | offset = inode->i_size; | |
1797 | } | |
1798 | } | |
1799 | ||
1800 | if (offset >= 0 && offset != file->f_pos) { | |
1801 | file->f_pos = offset; | |
1802 | file->f_version = 0; | |
1803 | } | |
1804 | mutex_unlock(&inode->i_mutex); | |
1805 | return offset; | |
1806 | } | |
1807 | ||
1808 | static long shmem_fallocate(struct file *file, int mode, loff_t offset, | |
1809 | loff_t len) | |
1810 | { | |
1811 | struct inode *inode = file_inode(file); | |
1812 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
1813 | struct shmem_falloc shmem_falloc; | |
1814 | pgoff_t start, index, end; | |
1815 | int error; | |
1816 | ||
1817 | mutex_lock(&inode->i_mutex); | |
1818 | ||
1819 | if (mode & FALLOC_FL_PUNCH_HOLE) { | |
1820 | struct address_space *mapping = file->f_mapping; | |
1821 | loff_t unmap_start = round_up(offset, PAGE_SIZE); | |
1822 | loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; | |
1823 | ||
1824 | if ((u64)unmap_end > (u64)unmap_start) | |
1825 | unmap_mapping_range(mapping, unmap_start, | |
1826 | 1 + unmap_end - unmap_start, 0); | |
1827 | shmem_truncate_range(inode, offset, offset + len - 1); | |
1828 | /* No need to unmap again: hole-punching leaves COWed pages */ | |
1829 | error = 0; | |
1830 | goto out; | |
1831 | } | |
1832 | ||
1833 | /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ | |
1834 | error = inode_newsize_ok(inode, offset + len); | |
1835 | if (error) | |
1836 | goto out; | |
1837 | ||
1838 | start = offset >> PAGE_CACHE_SHIFT; | |
1839 | end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1840 | /* Try to avoid a swapstorm if len is impossible to satisfy */ | |
1841 | if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { | |
1842 | error = -ENOSPC; | |
1843 | goto out; | |
1844 | } | |
1845 | ||
1846 | shmem_falloc.start = start; | |
1847 | shmem_falloc.next = start; | |
1848 | shmem_falloc.nr_falloced = 0; | |
1849 | shmem_falloc.nr_unswapped = 0; | |
1850 | spin_lock(&inode->i_lock); | |
1851 | inode->i_private = &shmem_falloc; | |
1852 | spin_unlock(&inode->i_lock); | |
1853 | ||
1854 | for (index = start; index < end; index++) { | |
1855 | struct page *page; | |
1856 | ||
1857 | /* | |
1858 | * Good, the fallocate(2) manpage permits EINTR: we may have | |
1859 | * been interrupted because we are using up too much memory. | |
1860 | */ | |
1861 | if (signal_pending(current)) | |
1862 | error = -EINTR; | |
1863 | else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) | |
1864 | error = -ENOMEM; | |
1865 | else | |
1866 | error = shmem_getpage(inode, index, &page, SGP_FALLOC, | |
1867 | NULL); | |
1868 | if (error) { | |
1869 | /* Remove the !PageUptodate pages we added */ | |
1870 | shmem_undo_range(inode, | |
1871 | (loff_t)start << PAGE_CACHE_SHIFT, | |
1872 | (loff_t)index << PAGE_CACHE_SHIFT, true); | |
1873 | goto undone; | |
1874 | } | |
1875 | ||
1876 | /* | |
1877 | * Inform shmem_writepage() how far we have reached. | |
1878 | * No need for lock or barrier: we have the page lock. | |
1879 | */ | |
1880 | shmem_falloc.next++; | |
1881 | if (!PageUptodate(page)) | |
1882 | shmem_falloc.nr_falloced++; | |
1883 | ||
1884 | /* | |
1885 | * If !PageUptodate, leave it that way so that freeable pages | |
1886 | * can be recognized if we need to rollback on error later. | |
1887 | * But set_page_dirty so that memory pressure will swap rather | |
1888 | * than free the pages we are allocating (and SGP_CACHE pages | |
1889 | * might still be clean: we now need to mark those dirty too). | |
1890 | */ | |
1891 | set_page_dirty(page); | |
1892 | unlock_page(page); | |
1893 | page_cache_release(page); | |
1894 | cond_resched(); | |
1895 | } | |
1896 | ||
1897 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) | |
1898 | i_size_write(inode, offset + len); | |
1899 | inode->i_ctime = CURRENT_TIME; | |
1900 | undone: | |
1901 | spin_lock(&inode->i_lock); | |
1902 | inode->i_private = NULL; | |
1903 | spin_unlock(&inode->i_lock); | |
1904 | out: | |
1905 | mutex_unlock(&inode->i_mutex); | |
1906 | return error; | |
1907 | } | |
1908 | ||
1909 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) | |
1910 | { | |
1911 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); | |
1912 | ||
1913 | buf->f_type = TMPFS_MAGIC; | |
1914 | buf->f_bsize = PAGE_CACHE_SIZE; | |
1915 | buf->f_namelen = NAME_MAX; | |
1916 | if (sbinfo->max_blocks) { | |
1917 | buf->f_blocks = sbinfo->max_blocks; | |
1918 | buf->f_bavail = | |
1919 | buf->f_bfree = sbinfo->max_blocks - | |
1920 | percpu_counter_sum(&sbinfo->used_blocks); | |
1921 | } | |
1922 | if (sbinfo->max_inodes) { | |
1923 | buf->f_files = sbinfo->max_inodes; | |
1924 | buf->f_ffree = sbinfo->free_inodes; | |
1925 | } | |
1926 | /* else leave those fields 0 like simple_statfs */ | |
1927 | return 0; | |
1928 | } | |
1929 | ||
1930 | /* | |
1931 | * File creation. Allocate an inode, and we're done.. | |
1932 | */ | |
1933 | static int | |
1934 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) | |
1935 | { | |
1936 | struct inode *inode; | |
1937 | int error = -ENOSPC; | |
1938 | ||
1939 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); | |
1940 | if (inode) { | |
1941 | error = security_inode_init_security(inode, dir, | |
1942 | &dentry->d_name, | |
1943 | shmem_initxattrs, NULL); | |
1944 | if (error) { | |
1945 | if (error != -EOPNOTSUPP) { | |
1946 | iput(inode); | |
1947 | return error; | |
1948 | } | |
1949 | } | |
1950 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
1951 | error = generic_acl_init(inode, dir); | |
1952 | if (error) { | |
1953 | iput(inode); | |
1954 | return error; | |
1955 | } | |
1956 | #else | |
1957 | error = 0; | |
1958 | #endif | |
1959 | dir->i_size += BOGO_DIRENT_SIZE; | |
1960 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
1961 | d_instantiate(dentry, inode); | |
1962 | dget(dentry); /* Extra count - pin the dentry in core */ | |
1963 | } | |
1964 | return error; | |
1965 | } | |
1966 | ||
1967 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
1968 | { | |
1969 | int error; | |
1970 | ||
1971 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) | |
1972 | return error; | |
1973 | inc_nlink(dir); | |
1974 | return 0; | |
1975 | } | |
1976 | ||
1977 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
1978 | bool excl) | |
1979 | { | |
1980 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); | |
1981 | } | |
1982 | ||
1983 | /* | |
1984 | * Link a file.. | |
1985 | */ | |
1986 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
1987 | { | |
1988 | struct inode *inode = old_dentry->d_inode; | |
1989 | int ret; | |
1990 | ||
1991 | /* | |
1992 | * No ordinary (disk based) filesystem counts links as inodes; | |
1993 | * but each new link needs a new dentry, pinning lowmem, and | |
1994 | * tmpfs dentries cannot be pruned until they are unlinked. | |
1995 | */ | |
1996 | ret = shmem_reserve_inode(inode->i_sb); | |
1997 | if (ret) | |
1998 | goto out; | |
1999 | ||
2000 | dir->i_size += BOGO_DIRENT_SIZE; | |
2001 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2002 | inc_nlink(inode); | |
2003 | ihold(inode); /* New dentry reference */ | |
2004 | dget(dentry); /* Extra pinning count for the created dentry */ | |
2005 | d_instantiate(dentry, inode); | |
2006 | out: | |
2007 | return ret; | |
2008 | } | |
2009 | ||
2010 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) | |
2011 | { | |
2012 | struct inode *inode = dentry->d_inode; | |
2013 | ||
2014 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) | |
2015 | shmem_free_inode(inode->i_sb); | |
2016 | ||
2017 | dir->i_size -= BOGO_DIRENT_SIZE; | |
2018 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2019 | drop_nlink(inode); | |
2020 | dput(dentry); /* Undo the count from "create" - this does all the work */ | |
2021 | return 0; | |
2022 | } | |
2023 | ||
2024 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) | |
2025 | { | |
2026 | if (!simple_empty(dentry)) | |
2027 | return -ENOTEMPTY; | |
2028 | ||
2029 | drop_nlink(dentry->d_inode); | |
2030 | drop_nlink(dir); | |
2031 | return shmem_unlink(dir, dentry); | |
2032 | } | |
2033 | ||
2034 | /* | |
2035 | * The VFS layer already does all the dentry stuff for rename, | |
2036 | * we just have to decrement the usage count for the target if | |
2037 | * it exists so that the VFS layer correctly free's it when it | |
2038 | * gets overwritten. | |
2039 | */ | |
2040 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) | |
2041 | { | |
2042 | struct inode *inode = old_dentry->d_inode; | |
2043 | int they_are_dirs = S_ISDIR(inode->i_mode); | |
2044 | ||
2045 | if (!simple_empty(new_dentry)) | |
2046 | return -ENOTEMPTY; | |
2047 | ||
2048 | if (new_dentry->d_inode) { | |
2049 | (void) shmem_unlink(new_dir, new_dentry); | |
2050 | if (they_are_dirs) | |
2051 | drop_nlink(old_dir); | |
2052 | } else if (they_are_dirs) { | |
2053 | drop_nlink(old_dir); | |
2054 | inc_nlink(new_dir); | |
2055 | } | |
2056 | ||
2057 | old_dir->i_size -= BOGO_DIRENT_SIZE; | |
2058 | new_dir->i_size += BOGO_DIRENT_SIZE; | |
2059 | old_dir->i_ctime = old_dir->i_mtime = | |
2060 | new_dir->i_ctime = new_dir->i_mtime = | |
2061 | inode->i_ctime = CURRENT_TIME; | |
2062 | return 0; | |
2063 | } | |
2064 | ||
2065 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) | |
2066 | { | |
2067 | int error; | |
2068 | int len; | |
2069 | struct inode *inode; | |
2070 | struct page *page; | |
2071 | char *kaddr; | |
2072 | struct shmem_inode_info *info; | |
2073 | ||
2074 | len = strlen(symname) + 1; | |
2075 | if (len > PAGE_CACHE_SIZE) | |
2076 | return -ENAMETOOLONG; | |
2077 | ||
2078 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); | |
2079 | if (!inode) | |
2080 | return -ENOSPC; | |
2081 | ||
2082 | error = security_inode_init_security(inode, dir, &dentry->d_name, | |
2083 | shmem_initxattrs, NULL); | |
2084 | if (error) { | |
2085 | if (error != -EOPNOTSUPP) { | |
2086 | iput(inode); | |
2087 | return error; | |
2088 | } | |
2089 | error = 0; | |
2090 | } | |
2091 | ||
2092 | info = SHMEM_I(inode); | |
2093 | inode->i_size = len-1; | |
2094 | if (len <= SHORT_SYMLINK_LEN) { | |
2095 | info->symlink = kmemdup(symname, len, GFP_KERNEL); | |
2096 | if (!info->symlink) { | |
2097 | iput(inode); | |
2098 | return -ENOMEM; | |
2099 | } | |
2100 | inode->i_op = &shmem_short_symlink_operations; | |
2101 | } else { | |
2102 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); | |
2103 | if (error) { | |
2104 | iput(inode); | |
2105 | return error; | |
2106 | } | |
2107 | inode->i_mapping->a_ops = &shmem_aops; | |
2108 | inode->i_op = &shmem_symlink_inode_operations; | |
2109 | kaddr = kmap_atomic(page); | |
2110 | memcpy(kaddr, symname, len); | |
2111 | kunmap_atomic(kaddr); | |
2112 | SetPageUptodate(page); | |
2113 | set_page_dirty(page); | |
2114 | unlock_page(page); | |
2115 | page_cache_release(page); | |
2116 | } | |
2117 | dir->i_size += BOGO_DIRENT_SIZE; | |
2118 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2119 | d_instantiate(dentry, inode); | |
2120 | dget(dentry); | |
2121 | return 0; | |
2122 | } | |
2123 | ||
2124 | static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) | |
2125 | { | |
2126 | nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); | |
2127 | return NULL; | |
2128 | } | |
2129 | ||
2130 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) | |
2131 | { | |
2132 | struct page *page = NULL; | |
2133 | int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); | |
2134 | nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); | |
2135 | if (page) | |
2136 | unlock_page(page); | |
2137 | return page; | |
2138 | } | |
2139 | ||
2140 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) | |
2141 | { | |
2142 | if (!IS_ERR(nd_get_link(nd))) { | |
2143 | struct page *page = cookie; | |
2144 | kunmap(page); | |
2145 | mark_page_accessed(page); | |
2146 | page_cache_release(page); | |
2147 | } | |
2148 | } | |
2149 | ||
2150 | #ifdef CONFIG_TMPFS_XATTR | |
2151 | /* | |
2152 | * Superblocks without xattr inode operations may get some security.* xattr | |
2153 | * support from the LSM "for free". As soon as we have any other xattrs | |
2154 | * like ACLs, we also need to implement the security.* handlers at | |
2155 | * filesystem level, though. | |
2156 | */ | |
2157 | ||
2158 | /* | |
2159 | * Callback for security_inode_init_security() for acquiring xattrs. | |
2160 | */ | |
2161 | static int shmem_initxattrs(struct inode *inode, | |
2162 | const struct xattr *xattr_array, | |
2163 | void *fs_info) | |
2164 | { | |
2165 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2166 | const struct xattr *xattr; | |
2167 | struct simple_xattr *new_xattr; | |
2168 | size_t len; | |
2169 | ||
2170 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { | |
2171 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); | |
2172 | if (!new_xattr) | |
2173 | return -ENOMEM; | |
2174 | ||
2175 | len = strlen(xattr->name) + 1; | |
2176 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, | |
2177 | GFP_KERNEL); | |
2178 | if (!new_xattr->name) { | |
2179 | kfree(new_xattr); | |
2180 | return -ENOMEM; | |
2181 | } | |
2182 | ||
2183 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, | |
2184 | XATTR_SECURITY_PREFIX_LEN); | |
2185 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, | |
2186 | xattr->name, len); | |
2187 | ||
2188 | simple_xattr_list_add(&info->xattrs, new_xattr); | |
2189 | } | |
2190 | ||
2191 | return 0; | |
2192 | } | |
2193 | ||
2194 | static const struct xattr_handler *shmem_xattr_handlers[] = { | |
2195 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2196 | &generic_acl_access_handler, | |
2197 | &generic_acl_default_handler, | |
2198 | #endif | |
2199 | NULL | |
2200 | }; | |
2201 | ||
2202 | static int shmem_xattr_validate(const char *name) | |
2203 | { | |
2204 | struct { const char *prefix; size_t len; } arr[] = { | |
2205 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, | |
2206 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } | |
2207 | }; | |
2208 | int i; | |
2209 | ||
2210 | for (i = 0; i < ARRAY_SIZE(arr); i++) { | |
2211 | size_t preflen = arr[i].len; | |
2212 | if (strncmp(name, arr[i].prefix, preflen) == 0) { | |
2213 | if (!name[preflen]) | |
2214 | return -EINVAL; | |
2215 | return 0; | |
2216 | } | |
2217 | } | |
2218 | return -EOPNOTSUPP; | |
2219 | } | |
2220 | ||
2221 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, | |
2222 | void *buffer, size_t size) | |
2223 | { | |
2224 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2225 | int err; | |
2226 | ||
2227 | /* | |
2228 | * If this is a request for a synthetic attribute in the system.* | |
2229 | * namespace use the generic infrastructure to resolve a handler | |
2230 | * for it via sb->s_xattr. | |
2231 | */ | |
2232 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2233 | return generic_getxattr(dentry, name, buffer, size); | |
2234 | ||
2235 | err = shmem_xattr_validate(name); | |
2236 | if (err) | |
2237 | return err; | |
2238 | ||
2239 | return simple_xattr_get(&info->xattrs, name, buffer, size); | |
2240 | } | |
2241 | ||
2242 | static int shmem_setxattr(struct dentry *dentry, const char *name, | |
2243 | const void *value, size_t size, int flags) | |
2244 | { | |
2245 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2246 | int err; | |
2247 | ||
2248 | /* | |
2249 | * If this is a request for a synthetic attribute in the system.* | |
2250 | * namespace use the generic infrastructure to resolve a handler | |
2251 | * for it via sb->s_xattr. | |
2252 | */ | |
2253 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2254 | return generic_setxattr(dentry, name, value, size, flags); | |
2255 | ||
2256 | err = shmem_xattr_validate(name); | |
2257 | if (err) | |
2258 | return err; | |
2259 | ||
2260 | return simple_xattr_set(&info->xattrs, name, value, size, flags); | |
2261 | } | |
2262 | ||
2263 | static int shmem_removexattr(struct dentry *dentry, const char *name) | |
2264 | { | |
2265 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2266 | int err; | |
2267 | ||
2268 | /* | |
2269 | * If this is a request for a synthetic attribute in the system.* | |
2270 | * namespace use the generic infrastructure to resolve a handler | |
2271 | * for it via sb->s_xattr. | |
2272 | */ | |
2273 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2274 | return generic_removexattr(dentry, name); | |
2275 | ||
2276 | err = shmem_xattr_validate(name); | |
2277 | if (err) | |
2278 | return err; | |
2279 | ||
2280 | return simple_xattr_remove(&info->xattrs, name); | |
2281 | } | |
2282 | ||
2283 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) | |
2284 | { | |
2285 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); | |
2286 | return simple_xattr_list(&info->xattrs, buffer, size); | |
2287 | } | |
2288 | #endif /* CONFIG_TMPFS_XATTR */ | |
2289 | ||
2290 | static const struct inode_operations shmem_short_symlink_operations = { | |
2291 | .readlink = generic_readlink, | |
2292 | .follow_link = shmem_follow_short_symlink, | |
2293 | #ifdef CONFIG_TMPFS_XATTR | |
2294 | .setxattr = shmem_setxattr, | |
2295 | .getxattr = shmem_getxattr, | |
2296 | .listxattr = shmem_listxattr, | |
2297 | .removexattr = shmem_removexattr, | |
2298 | #endif | |
2299 | }; | |
2300 | ||
2301 | static const struct inode_operations shmem_symlink_inode_operations = { | |
2302 | .readlink = generic_readlink, | |
2303 | .follow_link = shmem_follow_link, | |
2304 | .put_link = shmem_put_link, | |
2305 | #ifdef CONFIG_TMPFS_XATTR | |
2306 | .setxattr = shmem_setxattr, | |
2307 | .getxattr = shmem_getxattr, | |
2308 | .listxattr = shmem_listxattr, | |
2309 | .removexattr = shmem_removexattr, | |
2310 | #endif | |
2311 | }; | |
2312 | ||
2313 | static struct dentry *shmem_get_parent(struct dentry *child) | |
2314 | { | |
2315 | return ERR_PTR(-ESTALE); | |
2316 | } | |
2317 | ||
2318 | static int shmem_match(struct inode *ino, void *vfh) | |
2319 | { | |
2320 | __u32 *fh = vfh; | |
2321 | __u64 inum = fh[2]; | |
2322 | inum = (inum << 32) | fh[1]; | |
2323 | return ino->i_ino == inum && fh[0] == ino->i_generation; | |
2324 | } | |
2325 | ||
2326 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, | |
2327 | struct fid *fid, int fh_len, int fh_type) | |
2328 | { | |
2329 | struct inode *inode; | |
2330 | struct dentry *dentry = NULL; | |
2331 | u64 inum; | |
2332 | ||
2333 | if (fh_len < 3) | |
2334 | return NULL; | |
2335 | ||
2336 | inum = fid->raw[2]; | |
2337 | inum = (inum << 32) | fid->raw[1]; | |
2338 | ||
2339 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), | |
2340 | shmem_match, fid->raw); | |
2341 | if (inode) { | |
2342 | dentry = d_find_alias(inode); | |
2343 | iput(inode); | |
2344 | } | |
2345 | ||
2346 | return dentry; | |
2347 | } | |
2348 | ||
2349 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, | |
2350 | struct inode *parent) | |
2351 | { | |
2352 | if (*len < 3) { | |
2353 | *len = 3; | |
2354 | return 255; | |
2355 | } | |
2356 | ||
2357 | if (inode_unhashed(inode)) { | |
2358 | /* Unfortunately insert_inode_hash is not idempotent, | |
2359 | * so as we hash inodes here rather than at creation | |
2360 | * time, we need a lock to ensure we only try | |
2361 | * to do it once | |
2362 | */ | |
2363 | static DEFINE_SPINLOCK(lock); | |
2364 | spin_lock(&lock); | |
2365 | if (inode_unhashed(inode)) | |
2366 | __insert_inode_hash(inode, | |
2367 | inode->i_ino + inode->i_generation); | |
2368 | spin_unlock(&lock); | |
2369 | } | |
2370 | ||
2371 | fh[0] = inode->i_generation; | |
2372 | fh[1] = inode->i_ino; | |
2373 | fh[2] = ((__u64)inode->i_ino) >> 32; | |
2374 | ||
2375 | *len = 3; | |
2376 | return 1; | |
2377 | } | |
2378 | ||
2379 | static const struct export_operations shmem_export_ops = { | |
2380 | .get_parent = shmem_get_parent, | |
2381 | .encode_fh = shmem_encode_fh, | |
2382 | .fh_to_dentry = shmem_fh_to_dentry, | |
2383 | }; | |
2384 | ||
2385 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, | |
2386 | bool remount) | |
2387 | { | |
2388 | char *this_char, *value, *rest; | |
2389 | uid_t uid; | |
2390 | gid_t gid; | |
2391 | ||
2392 | while (options != NULL) { | |
2393 | this_char = options; | |
2394 | for (;;) { | |
2395 | /* | |
2396 | * NUL-terminate this option: unfortunately, | |
2397 | * mount options form a comma-separated list, | |
2398 | * but mpol's nodelist may also contain commas. | |
2399 | */ | |
2400 | options = strchr(options, ','); | |
2401 | if (options == NULL) | |
2402 | break; | |
2403 | options++; | |
2404 | if (!isdigit(*options)) { | |
2405 | options[-1] = '\0'; | |
2406 | break; | |
2407 | } | |
2408 | } | |
2409 | if (!*this_char) | |
2410 | continue; | |
2411 | if ((value = strchr(this_char,'=')) != NULL) { | |
2412 | *value++ = 0; | |
2413 | } else { | |
2414 | printk(KERN_ERR | |
2415 | "tmpfs: No value for mount option '%s'\n", | |
2416 | this_char); | |
2417 | return 1; | |
2418 | } | |
2419 | ||
2420 | if (!strcmp(this_char,"size")) { | |
2421 | unsigned long long size; | |
2422 | size = memparse(value,&rest); | |
2423 | if (*rest == '%') { | |
2424 | size <<= PAGE_SHIFT; | |
2425 | size *= totalram_pages; | |
2426 | do_div(size, 100); | |
2427 | rest++; | |
2428 | } | |
2429 | if (*rest) | |
2430 | goto bad_val; | |
2431 | sbinfo->max_blocks = | |
2432 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); | |
2433 | } else if (!strcmp(this_char,"nr_blocks")) { | |
2434 | sbinfo->max_blocks = memparse(value, &rest); | |
2435 | if (*rest) | |
2436 | goto bad_val; | |
2437 | } else if (!strcmp(this_char,"nr_inodes")) { | |
2438 | sbinfo->max_inodes = memparse(value, &rest); | |
2439 | if (*rest) | |
2440 | goto bad_val; | |
2441 | } else if (!strcmp(this_char,"mode")) { | |
2442 | if (remount) | |
2443 | continue; | |
2444 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; | |
2445 | if (*rest) | |
2446 | goto bad_val; | |
2447 | } else if (!strcmp(this_char,"uid")) { | |
2448 | if (remount) | |
2449 | continue; | |
2450 | uid = simple_strtoul(value, &rest, 0); | |
2451 | if (*rest) | |
2452 | goto bad_val; | |
2453 | sbinfo->uid = make_kuid(current_user_ns(), uid); | |
2454 | if (!uid_valid(sbinfo->uid)) | |
2455 | goto bad_val; | |
2456 | } else if (!strcmp(this_char,"gid")) { | |
2457 | if (remount) | |
2458 | continue; | |
2459 | gid = simple_strtoul(value, &rest, 0); | |
2460 | if (*rest) | |
2461 | goto bad_val; | |
2462 | sbinfo->gid = make_kgid(current_user_ns(), gid); | |
2463 | if (!gid_valid(sbinfo->gid)) | |
2464 | goto bad_val; | |
2465 | } else if (!strcmp(this_char,"mpol")) { | |
2466 | if (mpol_parse_str(value, &sbinfo->mpol)) | |
2467 | goto bad_val; | |
2468 | } else { | |
2469 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", | |
2470 | this_char); | |
2471 | return 1; | |
2472 | } | |
2473 | } | |
2474 | return 0; | |
2475 | ||
2476 | bad_val: | |
2477 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", | |
2478 | value, this_char); | |
2479 | return 1; | |
2480 | ||
2481 | } | |
2482 | ||
2483 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) | |
2484 | { | |
2485 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2486 | struct shmem_sb_info config = *sbinfo; | |
2487 | unsigned long inodes; | |
2488 | int error = -EINVAL; | |
2489 | ||
2490 | if (shmem_parse_options(data, &config, true)) | |
2491 | return error; | |
2492 | ||
2493 | spin_lock(&sbinfo->stat_lock); | |
2494 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; | |
2495 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) | |
2496 | goto out; | |
2497 | if (config.max_inodes < inodes) | |
2498 | goto out; | |
2499 | /* | |
2500 | * Those tests disallow limited->unlimited while any are in use; | |
2501 | * but we must separately disallow unlimited->limited, because | |
2502 | * in that case we have no record of how much is already in use. | |
2503 | */ | |
2504 | if (config.max_blocks && !sbinfo->max_blocks) | |
2505 | goto out; | |
2506 | if (config.max_inodes && !sbinfo->max_inodes) | |
2507 | goto out; | |
2508 | ||
2509 | error = 0; | |
2510 | sbinfo->max_blocks = config.max_blocks; | |
2511 | sbinfo->max_inodes = config.max_inodes; | |
2512 | sbinfo->free_inodes = config.max_inodes - inodes; | |
2513 | ||
2514 | mpol_put(sbinfo->mpol); | |
2515 | sbinfo->mpol = config.mpol; /* transfers initial ref */ | |
2516 | out: | |
2517 | spin_unlock(&sbinfo->stat_lock); | |
2518 | return error; | |
2519 | } | |
2520 | ||
2521 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) | |
2522 | { | |
2523 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); | |
2524 | ||
2525 | if (sbinfo->max_blocks != shmem_default_max_blocks()) | |
2526 | seq_printf(seq, ",size=%luk", | |
2527 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); | |
2528 | if (sbinfo->max_inodes != shmem_default_max_inodes()) | |
2529 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); | |
2530 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) | |
2531 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); | |
2532 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) | |
2533 | seq_printf(seq, ",uid=%u", | |
2534 | from_kuid_munged(&init_user_ns, sbinfo->uid)); | |
2535 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) | |
2536 | seq_printf(seq, ",gid=%u", | |
2537 | from_kgid_munged(&init_user_ns, sbinfo->gid)); | |
2538 | shmem_show_mpol(seq, sbinfo->mpol); | |
2539 | return 0; | |
2540 | } | |
2541 | #endif /* CONFIG_TMPFS */ | |
2542 | ||
2543 | static void shmem_put_super(struct super_block *sb) | |
2544 | { | |
2545 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2546 | ||
2547 | percpu_counter_destroy(&sbinfo->used_blocks); | |
2548 | kfree(sbinfo); | |
2549 | sb->s_fs_info = NULL; | |
2550 | } | |
2551 | ||
2552 | int shmem_fill_super(struct super_block *sb, void *data, int silent) | |
2553 | { | |
2554 | struct inode *inode; | |
2555 | struct shmem_sb_info *sbinfo; | |
2556 | int err = -ENOMEM; | |
2557 | ||
2558 | /* Round up to L1_CACHE_BYTES to resist false sharing */ | |
2559 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), | |
2560 | L1_CACHE_BYTES), GFP_KERNEL); | |
2561 | if (!sbinfo) | |
2562 | return -ENOMEM; | |
2563 | ||
2564 | sbinfo->mode = S_IRWXUGO | S_ISVTX; | |
2565 | sbinfo->uid = current_fsuid(); | |
2566 | sbinfo->gid = current_fsgid(); | |
2567 | sb->s_fs_info = sbinfo; | |
2568 | ||
2569 | #ifdef CONFIG_TMPFS | |
2570 | /* | |
2571 | * Per default we only allow half of the physical ram per | |
2572 | * tmpfs instance, limiting inodes to one per page of lowmem; | |
2573 | * but the internal instance is left unlimited. | |
2574 | */ | |
2575 | if (!(sb->s_flags & MS_NOUSER)) { | |
2576 | sbinfo->max_blocks = shmem_default_max_blocks(); | |
2577 | sbinfo->max_inodes = shmem_default_max_inodes(); | |
2578 | if (shmem_parse_options(data, sbinfo, false)) { | |
2579 | err = -EINVAL; | |
2580 | goto failed; | |
2581 | } | |
2582 | } | |
2583 | sb->s_export_op = &shmem_export_ops; | |
2584 | sb->s_flags |= MS_NOSEC; | |
2585 | #else | |
2586 | sb->s_flags |= MS_NOUSER; | |
2587 | #endif | |
2588 | ||
2589 | spin_lock_init(&sbinfo->stat_lock); | |
2590 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) | |
2591 | goto failed; | |
2592 | sbinfo->free_inodes = sbinfo->max_inodes; | |
2593 | ||
2594 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
2595 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
2596 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
2597 | sb->s_magic = TMPFS_MAGIC; | |
2598 | sb->s_op = &shmem_ops; | |
2599 | sb->s_time_gran = 1; | |
2600 | #ifdef CONFIG_TMPFS_XATTR | |
2601 | sb->s_xattr = shmem_xattr_handlers; | |
2602 | #endif | |
2603 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2604 | sb->s_flags |= MS_POSIXACL; | |
2605 | #endif | |
2606 | ||
2607 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); | |
2608 | if (!inode) | |
2609 | goto failed; | |
2610 | inode->i_uid = sbinfo->uid; | |
2611 | inode->i_gid = sbinfo->gid; | |
2612 | sb->s_root = d_make_root(inode); | |
2613 | if (!sb->s_root) | |
2614 | goto failed; | |
2615 | return 0; | |
2616 | ||
2617 | failed: | |
2618 | shmem_put_super(sb); | |
2619 | return err; | |
2620 | } | |
2621 | ||
2622 | static struct kmem_cache *shmem_inode_cachep; | |
2623 | ||
2624 | static struct inode *shmem_alloc_inode(struct super_block *sb) | |
2625 | { | |
2626 | struct shmem_inode_info *info; | |
2627 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); | |
2628 | if (!info) | |
2629 | return NULL; | |
2630 | return &info->vfs_inode; | |
2631 | } | |
2632 | ||
2633 | static void shmem_destroy_callback(struct rcu_head *head) | |
2634 | { | |
2635 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
2636 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); | |
2637 | } | |
2638 | ||
2639 | static void shmem_destroy_inode(struct inode *inode) | |
2640 | { | |
2641 | if (S_ISREG(inode->i_mode)) | |
2642 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); | |
2643 | call_rcu(&inode->i_rcu, shmem_destroy_callback); | |
2644 | } | |
2645 | ||
2646 | static void shmem_init_inode(void *foo) | |
2647 | { | |
2648 | struct shmem_inode_info *info = foo; | |
2649 | inode_init_once(&info->vfs_inode); | |
2650 | } | |
2651 | ||
2652 | static int shmem_init_inodecache(void) | |
2653 | { | |
2654 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", | |
2655 | sizeof(struct shmem_inode_info), | |
2656 | 0, SLAB_PANIC, shmem_init_inode); | |
2657 | return 0; | |
2658 | } | |
2659 | ||
2660 | static void shmem_destroy_inodecache(void) | |
2661 | { | |
2662 | kmem_cache_destroy(shmem_inode_cachep); | |
2663 | } | |
2664 | ||
2665 | static const struct address_space_operations shmem_aops = { | |
2666 | .writepage = shmem_writepage, | |
2667 | .set_page_dirty = __set_page_dirty_no_writeback, | |
2668 | #ifdef CONFIG_TMPFS | |
2669 | .write_begin = shmem_write_begin, | |
2670 | .write_end = shmem_write_end, | |
2671 | #endif | |
2672 | .migratepage = migrate_page, | |
2673 | .error_remove_page = generic_error_remove_page, | |
2674 | }; | |
2675 | ||
2676 | static const struct file_operations shmem_file_operations = { | |
2677 | .mmap = shmem_mmap, | |
2678 | #ifdef CONFIG_TMPFS | |
2679 | .llseek = shmem_file_llseek, | |
2680 | .read = do_sync_read, | |
2681 | .write = do_sync_write, | |
2682 | .aio_read = shmem_file_aio_read, | |
2683 | .aio_write = generic_file_aio_write, | |
2684 | .fsync = noop_fsync, | |
2685 | .splice_read = shmem_file_splice_read, | |
2686 | .splice_write = generic_file_splice_write, | |
2687 | .fallocate = shmem_fallocate, | |
2688 | #endif | |
2689 | }; | |
2690 | ||
2691 | static const struct inode_operations shmem_inode_operations = { | |
2692 | .setattr = shmem_setattr, | |
2693 | #ifdef CONFIG_TMPFS_XATTR | |
2694 | .setxattr = shmem_setxattr, | |
2695 | .getxattr = shmem_getxattr, | |
2696 | .listxattr = shmem_listxattr, | |
2697 | .removexattr = shmem_removexattr, | |
2698 | #endif | |
2699 | }; | |
2700 | ||
2701 | static const struct inode_operations shmem_dir_inode_operations = { | |
2702 | #ifdef CONFIG_TMPFS | |
2703 | .create = shmem_create, | |
2704 | .lookup = simple_lookup, | |
2705 | .link = shmem_link, | |
2706 | .unlink = shmem_unlink, | |
2707 | .symlink = shmem_symlink, | |
2708 | .mkdir = shmem_mkdir, | |
2709 | .rmdir = shmem_rmdir, | |
2710 | .mknod = shmem_mknod, | |
2711 | .rename = shmem_rename, | |
2712 | #endif | |
2713 | #ifdef CONFIG_TMPFS_XATTR | |
2714 | .setxattr = shmem_setxattr, | |
2715 | .getxattr = shmem_getxattr, | |
2716 | .listxattr = shmem_listxattr, | |
2717 | .removexattr = shmem_removexattr, | |
2718 | #endif | |
2719 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2720 | .setattr = shmem_setattr, | |
2721 | #endif | |
2722 | }; | |
2723 | ||
2724 | static const struct inode_operations shmem_special_inode_operations = { | |
2725 | #ifdef CONFIG_TMPFS_XATTR | |
2726 | .setxattr = shmem_setxattr, | |
2727 | .getxattr = shmem_getxattr, | |
2728 | .listxattr = shmem_listxattr, | |
2729 | .removexattr = shmem_removexattr, | |
2730 | #endif | |
2731 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2732 | .setattr = shmem_setattr, | |
2733 | #endif | |
2734 | }; | |
2735 | ||
2736 | static const struct super_operations shmem_ops = { | |
2737 | .alloc_inode = shmem_alloc_inode, | |
2738 | .destroy_inode = shmem_destroy_inode, | |
2739 | #ifdef CONFIG_TMPFS | |
2740 | .statfs = shmem_statfs, | |
2741 | .remount_fs = shmem_remount_fs, | |
2742 | .show_options = shmem_show_options, | |
2743 | #endif | |
2744 | .evict_inode = shmem_evict_inode, | |
2745 | .drop_inode = generic_delete_inode, | |
2746 | .put_super = shmem_put_super, | |
2747 | }; | |
2748 | ||
2749 | static const struct vm_operations_struct shmem_vm_ops = { | |
2750 | .fault = shmem_fault, | |
2751 | #ifdef CONFIG_NUMA | |
2752 | .set_policy = shmem_set_policy, | |
2753 | .get_policy = shmem_get_policy, | |
2754 | #endif | |
2755 | .remap_pages = generic_file_remap_pages, | |
2756 | }; | |
2757 | ||
2758 | static struct dentry *shmem_mount(struct file_system_type *fs_type, | |
2759 | int flags, const char *dev_name, void *data) | |
2760 | { | |
2761 | return mount_nodev(fs_type, flags, data, shmem_fill_super); | |
2762 | } | |
2763 | ||
2764 | static struct file_system_type shmem_fs_type = { | |
2765 | .owner = THIS_MODULE, | |
2766 | .name = "tmpfs", | |
2767 | .mount = shmem_mount, | |
2768 | .kill_sb = kill_litter_super, | |
2769 | }; | |
2770 | ||
2771 | int __init shmem_init(void) | |
2772 | { | |
2773 | int error; | |
2774 | ||
2775 | error = bdi_init(&shmem_backing_dev_info); | |
2776 | if (error) | |
2777 | goto out4; | |
2778 | ||
2779 | error = shmem_init_inodecache(); | |
2780 | if (error) | |
2781 | goto out3; | |
2782 | ||
2783 | error = register_filesystem(&shmem_fs_type); | |
2784 | if (error) { | |
2785 | printk(KERN_ERR "Could not register tmpfs\n"); | |
2786 | goto out2; | |
2787 | } | |
2788 | ||
2789 | shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER, | |
2790 | shmem_fs_type.name, NULL); | |
2791 | if (IS_ERR(shm_mnt)) { | |
2792 | error = PTR_ERR(shm_mnt); | |
2793 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); | |
2794 | goto out1; | |
2795 | } | |
2796 | return 0; | |
2797 | ||
2798 | out1: | |
2799 | unregister_filesystem(&shmem_fs_type); | |
2800 | out2: | |
2801 | shmem_destroy_inodecache(); | |
2802 | out3: | |
2803 | bdi_destroy(&shmem_backing_dev_info); | |
2804 | out4: | |
2805 | shm_mnt = ERR_PTR(error); | |
2806 | return error; | |
2807 | } | |
2808 | ||
2809 | #else /* !CONFIG_SHMEM */ | |
2810 | ||
2811 | /* | |
2812 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code | |
2813 | * | |
2814 | * This is intended for small system where the benefits of the full | |
2815 | * shmem code (swap-backed and resource-limited) are outweighed by | |
2816 | * their complexity. On systems without swap this code should be | |
2817 | * effectively equivalent, but much lighter weight. | |
2818 | */ | |
2819 | ||
2820 | #include <linux/ramfs.h> | |
2821 | ||
2822 | static struct file_system_type shmem_fs_type = { | |
2823 | .name = "tmpfs", | |
2824 | .mount = ramfs_mount, | |
2825 | .kill_sb = kill_litter_super, | |
2826 | }; | |
2827 | ||
2828 | int __init shmem_init(void) | |
2829 | { | |
2830 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); | |
2831 | ||
2832 | shm_mnt = kern_mount(&shmem_fs_type); | |
2833 | BUG_ON(IS_ERR(shm_mnt)); | |
2834 | ||
2835 | return 0; | |
2836 | } | |
2837 | ||
2838 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
2839 | { | |
2840 | return 0; | |
2841 | } | |
2842 | ||
2843 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
2844 | { | |
2845 | return 0; | |
2846 | } | |
2847 | ||
2848 | void shmem_unlock_mapping(struct address_space *mapping) | |
2849 | { | |
2850 | } | |
2851 | ||
2852 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
2853 | { | |
2854 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); | |
2855 | } | |
2856 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
2857 | ||
2858 | #define shmem_vm_ops generic_file_vm_ops | |
2859 | #define shmem_file_operations ramfs_file_operations | |
2860 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) | |
2861 | #define shmem_acct_size(flags, size) 0 | |
2862 | #define shmem_unacct_size(flags, size) do {} while (0) | |
2863 | ||
2864 | #endif /* CONFIG_SHMEM */ | |
2865 | ||
2866 | /* common code */ | |
2867 | ||
2868 | /** | |
2869 | * shmem_file_setup - get an unlinked file living in tmpfs | |
2870 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
2871 | * @size: size to be set for the file | |
2872 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
2873 | */ | |
2874 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) | |
2875 | { | |
2876 | struct file *res; | |
2877 | struct inode *inode; | |
2878 | struct path path; | |
2879 | struct dentry *root; | |
2880 | struct qstr this; | |
2881 | ||
2882 | if (IS_ERR(shm_mnt)) | |
2883 | return ERR_CAST(shm_mnt); | |
2884 | ||
2885 | if (size < 0 || size > MAX_LFS_FILESIZE) | |
2886 | return ERR_PTR(-EINVAL); | |
2887 | ||
2888 | if (shmem_acct_size(flags, size)) | |
2889 | return ERR_PTR(-ENOMEM); | |
2890 | ||
2891 | res = ERR_PTR(-ENOMEM); | |
2892 | this.name = name; | |
2893 | this.len = strlen(name); | |
2894 | this.hash = 0; /* will go */ | |
2895 | root = shm_mnt->mnt_root; | |
2896 | path.dentry = d_alloc(root, &this); | |
2897 | if (!path.dentry) | |
2898 | goto put_memory; | |
2899 | path.mnt = mntget(shm_mnt); | |
2900 | ||
2901 | res = ERR_PTR(-ENOSPC); | |
2902 | inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); | |
2903 | if (!inode) | |
2904 | goto put_dentry; | |
2905 | ||
2906 | d_instantiate(path.dentry, inode); | |
2907 | inode->i_size = size; | |
2908 | clear_nlink(inode); /* It is unlinked */ | |
2909 | #ifndef CONFIG_MMU | |
2910 | error = ramfs_nommu_expand_for_mapping(inode, size); | |
2911 | res = ERR_PTR(error); | |
2912 | if (error) | |
2913 | goto put_dentry; | |
2914 | #endif | |
2915 | ||
2916 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, | |
2917 | &shmem_file_operations); | |
2918 | if (IS_ERR(res)) | |
2919 | goto put_dentry; | |
2920 | ||
2921 | return res; | |
2922 | ||
2923 | put_dentry: | |
2924 | path_put(&path); | |
2925 | put_memory: | |
2926 | shmem_unacct_size(flags, size); | |
2927 | return res; | |
2928 | } | |
2929 | EXPORT_SYMBOL_GPL(shmem_file_setup); | |
2930 | ||
2931 | /** | |
2932 | * shmem_zero_setup - setup a shared anonymous mapping | |
2933 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff | |
2934 | */ | |
2935 | int shmem_zero_setup(struct vm_area_struct *vma) | |
2936 | { | |
2937 | struct file *file; | |
2938 | loff_t size = vma->vm_end - vma->vm_start; | |
2939 | ||
2940 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); | |
2941 | if (IS_ERR(file)) | |
2942 | return PTR_ERR(file); | |
2943 | ||
2944 | if (vma->vm_file) | |
2945 | fput(vma->vm_file); | |
2946 | vma->vm_file = file; | |
2947 | vma->vm_ops = &shmem_vm_ops; | |
2948 | return 0; | |
2949 | } | |
2950 | ||
2951 | /** | |
2952 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. | |
2953 | * @mapping: the page's address_space | |
2954 | * @index: the page index | |
2955 | * @gfp: the page allocator flags to use if allocating | |
2956 | * | |
2957 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", | |
2958 | * with any new page allocations done using the specified allocation flags. | |
2959 | * But read_cache_page_gfp() uses the ->readpage() method: which does not | |
2960 | * suit tmpfs, since it may have pages in swapcache, and needs to find those | |
2961 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. | |
2962 | * | |
2963 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in | |
2964 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. | |
2965 | */ | |
2966 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, | |
2967 | pgoff_t index, gfp_t gfp) | |
2968 | { | |
2969 | #ifdef CONFIG_SHMEM | |
2970 | struct inode *inode = mapping->host; | |
2971 | struct page *page; | |
2972 | int error; | |
2973 | ||
2974 | BUG_ON(mapping->a_ops != &shmem_aops); | |
2975 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); | |
2976 | if (error) | |
2977 | page = ERR_PTR(error); | |
2978 | else | |
2979 | unlock_page(page); | |
2980 | return page; | |
2981 | #else | |
2982 | /* | |
2983 | * The tiny !SHMEM case uses ramfs without swap | |
2984 | */ | |
2985 | return read_cache_page_gfp(mapping, index, gfp); | |
2986 | #endif | |
2987 | } | |
2988 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |