]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * Resizable virtual memory filesystem for Linux. | |
3 | * | |
4 | * Copyright (C) 2000 Linus Torvalds. | |
5 | * 2000 Transmeta Corp. | |
6 | * 2000-2001 Christoph Rohland | |
7 | * 2000-2001 SAP AG | |
8 | * 2002 Red Hat Inc. | |
9 | * Copyright (C) 2002-2011 Hugh Dickins. | |
10 | * Copyright (C) 2011 Google Inc. | |
11 | * Copyright (C) 2002-2005 VERITAS Software Corporation. | |
12 | * Copyright (C) 2004 Andi Kleen, SuSE Labs | |
13 | * | |
14 | * Extended attribute support for tmpfs: | |
15 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> | |
16 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> | |
17 | * | |
18 | * tiny-shmem: | |
19 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> | |
20 | * | |
21 | * This file is released under the GPL. | |
22 | */ | |
23 | ||
24 | #include <linux/fs.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/vfs.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/ramfs.h> | |
29 | #include <linux/pagemap.h> | |
30 | #include <linux/file.h> | |
31 | #include <linux/mm.h> | |
32 | #include <linux/export.h> | |
33 | #include <linux/swap.h> | |
34 | #include <linux/uio.h> | |
35 | ||
36 | static struct vfsmount *shm_mnt; | |
37 | ||
38 | #ifdef CONFIG_SHMEM | |
39 | /* | |
40 | * This virtual memory filesystem is heavily based on the ramfs. It | |
41 | * extends ramfs by the ability to use swap and honor resource limits | |
42 | * which makes it a completely usable filesystem. | |
43 | */ | |
44 | ||
45 | #include <linux/xattr.h> | |
46 | #include <linux/exportfs.h> | |
47 | #include <linux/posix_acl.h> | |
48 | #include <linux/posix_acl_xattr.h> | |
49 | #include <linux/mman.h> | |
50 | #include <linux/string.h> | |
51 | #include <linux/slab.h> | |
52 | #include <linux/backing-dev.h> | |
53 | #include <linux/shmem_fs.h> | |
54 | #include <linux/writeback.h> | |
55 | #include <linux/blkdev.h> | |
56 | #include <linux/pagevec.h> | |
57 | #include <linux/percpu_counter.h> | |
58 | #include <linux/falloc.h> | |
59 | #include <linux/splice.h> | |
60 | #include <linux/security.h> | |
61 | #include <linux/swapops.h> | |
62 | #include <linux/mempolicy.h> | |
63 | #include <linux/namei.h> | |
64 | #include <linux/ctype.h> | |
65 | #include <linux/migrate.h> | |
66 | #include <linux/highmem.h> | |
67 | #include <linux/seq_file.h> | |
68 | #include <linux/magic.h> | |
69 | #include <linux/syscalls.h> | |
70 | #include <linux/fcntl.h> | |
71 | #include <uapi/linux/memfd.h> | |
72 | ||
73 | #include <asm/uaccess.h> | |
74 | #include <asm/pgtable.h> | |
75 | ||
76 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) | |
77 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) | |
78 | ||
79 | /* Pretend that each entry is of this size in directory's i_size */ | |
80 | #define BOGO_DIRENT_SIZE 20 | |
81 | ||
82 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ | |
83 | #define SHORT_SYMLINK_LEN 128 | |
84 | ||
85 | /* | |
86 | * shmem_fallocate communicates with shmem_fault or shmem_writepage via | |
87 | * inode->i_private (with i_mutex making sure that it has only one user at | |
88 | * a time): we would prefer not to enlarge the shmem inode just for that. | |
89 | */ | |
90 | struct shmem_falloc { | |
91 | wait_queue_head_t *waitq; /* faults into hole wait for punch to end */ | |
92 | pgoff_t start; /* start of range currently being fallocated */ | |
93 | pgoff_t next; /* the next page offset to be fallocated */ | |
94 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ | |
95 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ | |
96 | }; | |
97 | ||
98 | /* Flag allocation requirements to shmem_getpage */ | |
99 | enum sgp_type { | |
100 | SGP_READ, /* don't exceed i_size, don't allocate page */ | |
101 | SGP_CACHE, /* don't exceed i_size, may allocate page */ | |
102 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ | |
103 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ | |
104 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ | |
105 | }; | |
106 | ||
107 | #ifdef CONFIG_TMPFS | |
108 | static unsigned long shmem_default_max_blocks(void) | |
109 | { | |
110 | return totalram_pages / 2; | |
111 | } | |
112 | ||
113 | static unsigned long shmem_default_max_inodes(void) | |
114 | { | |
115 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); | |
116 | } | |
117 | #endif | |
118 | ||
119 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); | |
120 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
121 | struct shmem_inode_info *info, pgoff_t index); | |
122 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
123 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); | |
124 | ||
125 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, | |
126 | struct page **pagep, enum sgp_type sgp, int *fault_type) | |
127 | { | |
128 | return shmem_getpage_gfp(inode, index, pagep, sgp, | |
129 | mapping_gfp_mask(inode->i_mapping), fault_type); | |
130 | } | |
131 | ||
132 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) | |
133 | { | |
134 | return sb->s_fs_info; | |
135 | } | |
136 | ||
137 | /* | |
138 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, | |
139 | * for shared memory and for shared anonymous (/dev/zero) mappings | |
140 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), | |
141 | * consistent with the pre-accounting of private mappings ... | |
142 | */ | |
143 | static inline int shmem_acct_size(unsigned long flags, loff_t size) | |
144 | { | |
145 | return (flags & VM_NORESERVE) ? | |
146 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); | |
147 | } | |
148 | ||
149 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) | |
150 | { | |
151 | if (!(flags & VM_NORESERVE)) | |
152 | vm_unacct_memory(VM_ACCT(size)); | |
153 | } | |
154 | ||
155 | static inline int shmem_reacct_size(unsigned long flags, | |
156 | loff_t oldsize, loff_t newsize) | |
157 | { | |
158 | if (!(flags & VM_NORESERVE)) { | |
159 | if (VM_ACCT(newsize) > VM_ACCT(oldsize)) | |
160 | return security_vm_enough_memory_mm(current->mm, | |
161 | VM_ACCT(newsize) - VM_ACCT(oldsize)); | |
162 | else if (VM_ACCT(newsize) < VM_ACCT(oldsize)) | |
163 | vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize)); | |
164 | } | |
165 | return 0; | |
166 | } | |
167 | ||
168 | /* | |
169 | * ... whereas tmpfs objects are accounted incrementally as | |
170 | * pages are allocated, in order to allow huge sparse files. | |
171 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, | |
172 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. | |
173 | */ | |
174 | static inline int shmem_acct_block(unsigned long flags) | |
175 | { | |
176 | return (flags & VM_NORESERVE) ? | |
177 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; | |
178 | } | |
179 | ||
180 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) | |
181 | { | |
182 | if (flags & VM_NORESERVE) | |
183 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); | |
184 | } | |
185 | ||
186 | static const struct super_operations shmem_ops; | |
187 | static const struct address_space_operations shmem_aops; | |
188 | static const struct file_operations shmem_file_operations; | |
189 | static const struct inode_operations shmem_inode_operations; | |
190 | static const struct inode_operations shmem_dir_inode_operations; | |
191 | static const struct inode_operations shmem_special_inode_operations; | |
192 | static const struct vm_operations_struct shmem_vm_ops; | |
193 | ||
194 | static LIST_HEAD(shmem_swaplist); | |
195 | static DEFINE_MUTEX(shmem_swaplist_mutex); | |
196 | ||
197 | static int shmem_reserve_inode(struct super_block *sb) | |
198 | { | |
199 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
200 | if (sbinfo->max_inodes) { | |
201 | spin_lock(&sbinfo->stat_lock); | |
202 | if (!sbinfo->free_inodes) { | |
203 | spin_unlock(&sbinfo->stat_lock); | |
204 | return -ENOSPC; | |
205 | } | |
206 | sbinfo->free_inodes--; | |
207 | spin_unlock(&sbinfo->stat_lock); | |
208 | } | |
209 | return 0; | |
210 | } | |
211 | ||
212 | static void shmem_free_inode(struct super_block *sb) | |
213 | { | |
214 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
215 | if (sbinfo->max_inodes) { | |
216 | spin_lock(&sbinfo->stat_lock); | |
217 | sbinfo->free_inodes++; | |
218 | spin_unlock(&sbinfo->stat_lock); | |
219 | } | |
220 | } | |
221 | ||
222 | /** | |
223 | * shmem_recalc_inode - recalculate the block usage of an inode | |
224 | * @inode: inode to recalc | |
225 | * | |
226 | * We have to calculate the free blocks since the mm can drop | |
227 | * undirtied hole pages behind our back. | |
228 | * | |
229 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped | |
230 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) | |
231 | * | |
232 | * It has to be called with the spinlock held. | |
233 | */ | |
234 | static void shmem_recalc_inode(struct inode *inode) | |
235 | { | |
236 | struct shmem_inode_info *info = SHMEM_I(inode); | |
237 | long freed; | |
238 | ||
239 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; | |
240 | if (freed > 0) { | |
241 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
242 | if (sbinfo->max_blocks) | |
243 | percpu_counter_add(&sbinfo->used_blocks, -freed); | |
244 | info->alloced -= freed; | |
245 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; | |
246 | shmem_unacct_blocks(info->flags, freed); | |
247 | } | |
248 | } | |
249 | ||
250 | /* | |
251 | * Replace item expected in radix tree by a new item, while holding tree lock. | |
252 | */ | |
253 | static int shmem_radix_tree_replace(struct address_space *mapping, | |
254 | pgoff_t index, void *expected, void *replacement) | |
255 | { | |
256 | void **pslot; | |
257 | void *item; | |
258 | ||
259 | VM_BUG_ON(!expected); | |
260 | VM_BUG_ON(!replacement); | |
261 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); | |
262 | if (!pslot) | |
263 | return -ENOENT; | |
264 | item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock); | |
265 | if (item != expected) | |
266 | return -ENOENT; | |
267 | radix_tree_replace_slot(pslot, replacement); | |
268 | return 0; | |
269 | } | |
270 | ||
271 | /* | |
272 | * Sometimes, before we decide whether to proceed or to fail, we must check | |
273 | * that an entry was not already brought back from swap by a racing thread. | |
274 | * | |
275 | * Checking page is not enough: by the time a SwapCache page is locked, it | |
276 | * might be reused, and again be SwapCache, using the same swap as before. | |
277 | */ | |
278 | static bool shmem_confirm_swap(struct address_space *mapping, | |
279 | pgoff_t index, swp_entry_t swap) | |
280 | { | |
281 | void *item; | |
282 | ||
283 | rcu_read_lock(); | |
284 | item = radix_tree_lookup(&mapping->page_tree, index); | |
285 | rcu_read_unlock(); | |
286 | return item == swp_to_radix_entry(swap); | |
287 | } | |
288 | ||
289 | /* | |
290 | * Like add_to_page_cache_locked, but error if expected item has gone. | |
291 | */ | |
292 | static int shmem_add_to_page_cache(struct page *page, | |
293 | struct address_space *mapping, | |
294 | pgoff_t index, void *expected) | |
295 | { | |
296 | int error; | |
297 | ||
298 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
299 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
300 | ||
301 | page_cache_get(page); | |
302 | page->mapping = mapping; | |
303 | page->index = index; | |
304 | ||
305 | spin_lock_irq(&mapping->tree_lock); | |
306 | if (!expected) | |
307 | error = radix_tree_insert(&mapping->page_tree, index, page); | |
308 | else | |
309 | error = shmem_radix_tree_replace(mapping, index, expected, | |
310 | page); | |
311 | if (!error) { | |
312 | mapping->nrpages++; | |
313 | __inc_zone_page_state(page, NR_FILE_PAGES); | |
314 | __inc_zone_page_state(page, NR_SHMEM); | |
315 | spin_unlock_irq(&mapping->tree_lock); | |
316 | } else { | |
317 | page->mapping = NULL; | |
318 | spin_unlock_irq(&mapping->tree_lock); | |
319 | page_cache_release(page); | |
320 | } | |
321 | return error; | |
322 | } | |
323 | ||
324 | /* | |
325 | * Like delete_from_page_cache, but substitutes swap for page. | |
326 | */ | |
327 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) | |
328 | { | |
329 | struct address_space *mapping = page->mapping; | |
330 | int error; | |
331 | ||
332 | spin_lock_irq(&mapping->tree_lock); | |
333 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); | |
334 | page->mapping = NULL; | |
335 | mapping->nrpages--; | |
336 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
337 | __dec_zone_page_state(page, NR_SHMEM); | |
338 | spin_unlock_irq(&mapping->tree_lock); | |
339 | page_cache_release(page); | |
340 | BUG_ON(error); | |
341 | } | |
342 | ||
343 | /* | |
344 | * Remove swap entry from radix tree, free the swap and its page cache. | |
345 | */ | |
346 | static int shmem_free_swap(struct address_space *mapping, | |
347 | pgoff_t index, void *radswap) | |
348 | { | |
349 | void *old; | |
350 | ||
351 | spin_lock_irq(&mapping->tree_lock); | |
352 | old = radix_tree_delete_item(&mapping->page_tree, index, radswap); | |
353 | spin_unlock_irq(&mapping->tree_lock); | |
354 | if (old != radswap) | |
355 | return -ENOENT; | |
356 | free_swap_and_cache(radix_to_swp_entry(radswap)); | |
357 | return 0; | |
358 | } | |
359 | ||
360 | /* | |
361 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. | |
362 | */ | |
363 | void shmem_unlock_mapping(struct address_space *mapping) | |
364 | { | |
365 | struct pagevec pvec; | |
366 | pgoff_t indices[PAGEVEC_SIZE]; | |
367 | pgoff_t index = 0; | |
368 | ||
369 | pagevec_init(&pvec, 0); | |
370 | /* | |
371 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. | |
372 | */ | |
373 | while (!mapping_unevictable(mapping)) { | |
374 | /* | |
375 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it | |
376 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. | |
377 | */ | |
378 | pvec.nr = find_get_entries(mapping, index, | |
379 | PAGEVEC_SIZE, pvec.pages, indices); | |
380 | if (!pvec.nr) | |
381 | break; | |
382 | index = indices[pvec.nr - 1] + 1; | |
383 | pagevec_remove_exceptionals(&pvec); | |
384 | check_move_unevictable_pages(pvec.pages, pvec.nr); | |
385 | pagevec_release(&pvec); | |
386 | cond_resched(); | |
387 | } | |
388 | } | |
389 | ||
390 | /* | |
391 | * Remove range of pages and swap entries from radix tree, and free them. | |
392 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. | |
393 | */ | |
394 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, | |
395 | bool unfalloc) | |
396 | { | |
397 | struct address_space *mapping = inode->i_mapping; | |
398 | struct shmem_inode_info *info = SHMEM_I(inode); | |
399 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
400 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; | |
401 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); | |
402 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); | |
403 | struct pagevec pvec; | |
404 | pgoff_t indices[PAGEVEC_SIZE]; | |
405 | long nr_swaps_freed = 0; | |
406 | pgoff_t index; | |
407 | int i; | |
408 | ||
409 | if (lend == -1) | |
410 | end = -1; /* unsigned, so actually very big */ | |
411 | ||
412 | pagevec_init(&pvec, 0); | |
413 | index = start; | |
414 | while (index < end) { | |
415 | pvec.nr = find_get_entries(mapping, index, | |
416 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
417 | pvec.pages, indices); | |
418 | if (!pvec.nr) | |
419 | break; | |
420 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
421 | struct page *page = pvec.pages[i]; | |
422 | ||
423 | index = indices[i]; | |
424 | if (index >= end) | |
425 | break; | |
426 | ||
427 | if (radix_tree_exceptional_entry(page)) { | |
428 | if (unfalloc) | |
429 | continue; | |
430 | nr_swaps_freed += !shmem_free_swap(mapping, | |
431 | index, page); | |
432 | continue; | |
433 | } | |
434 | ||
435 | if (!trylock_page(page)) | |
436 | continue; | |
437 | if (!unfalloc || !PageUptodate(page)) { | |
438 | if (page->mapping == mapping) { | |
439 | VM_BUG_ON_PAGE(PageWriteback(page), page); | |
440 | truncate_inode_page(mapping, page); | |
441 | } | |
442 | } | |
443 | unlock_page(page); | |
444 | } | |
445 | pagevec_remove_exceptionals(&pvec); | |
446 | pagevec_release(&pvec); | |
447 | cond_resched(); | |
448 | index++; | |
449 | } | |
450 | ||
451 | if (partial_start) { | |
452 | struct page *page = NULL; | |
453 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); | |
454 | if (page) { | |
455 | unsigned int top = PAGE_CACHE_SIZE; | |
456 | if (start > end) { | |
457 | top = partial_end; | |
458 | partial_end = 0; | |
459 | } | |
460 | zero_user_segment(page, partial_start, top); | |
461 | set_page_dirty(page); | |
462 | unlock_page(page); | |
463 | page_cache_release(page); | |
464 | } | |
465 | } | |
466 | if (partial_end) { | |
467 | struct page *page = NULL; | |
468 | shmem_getpage(inode, end, &page, SGP_READ, NULL); | |
469 | if (page) { | |
470 | zero_user_segment(page, 0, partial_end); | |
471 | set_page_dirty(page); | |
472 | unlock_page(page); | |
473 | page_cache_release(page); | |
474 | } | |
475 | } | |
476 | if (start >= end) | |
477 | return; | |
478 | ||
479 | index = start; | |
480 | while (index < end) { | |
481 | cond_resched(); | |
482 | ||
483 | pvec.nr = find_get_entries(mapping, index, | |
484 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
485 | pvec.pages, indices); | |
486 | if (!pvec.nr) { | |
487 | /* If all gone or hole-punch or unfalloc, we're done */ | |
488 | if (index == start || end != -1) | |
489 | break; | |
490 | /* But if truncating, restart to make sure all gone */ | |
491 | index = start; | |
492 | continue; | |
493 | } | |
494 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
495 | struct page *page = pvec.pages[i]; | |
496 | ||
497 | index = indices[i]; | |
498 | if (index >= end) | |
499 | break; | |
500 | ||
501 | if (radix_tree_exceptional_entry(page)) { | |
502 | if (unfalloc) | |
503 | continue; | |
504 | if (shmem_free_swap(mapping, index, page)) { | |
505 | /* Swap was replaced by page: retry */ | |
506 | index--; | |
507 | break; | |
508 | } | |
509 | nr_swaps_freed++; | |
510 | continue; | |
511 | } | |
512 | ||
513 | lock_page(page); | |
514 | if (!unfalloc || !PageUptodate(page)) { | |
515 | if (page->mapping == mapping) { | |
516 | VM_BUG_ON_PAGE(PageWriteback(page), page); | |
517 | truncate_inode_page(mapping, page); | |
518 | } else { | |
519 | /* Page was replaced by swap: retry */ | |
520 | unlock_page(page); | |
521 | index--; | |
522 | break; | |
523 | } | |
524 | } | |
525 | unlock_page(page); | |
526 | } | |
527 | pagevec_remove_exceptionals(&pvec); | |
528 | pagevec_release(&pvec); | |
529 | index++; | |
530 | } | |
531 | ||
532 | spin_lock(&info->lock); | |
533 | info->swapped -= nr_swaps_freed; | |
534 | shmem_recalc_inode(inode); | |
535 | spin_unlock(&info->lock); | |
536 | } | |
537 | ||
538 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
539 | { | |
540 | shmem_undo_range(inode, lstart, lend, false); | |
541 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
542 | } | |
543 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
544 | ||
545 | static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
546 | struct kstat *stat) | |
547 | { | |
548 | struct inode *inode = dentry->d_inode; | |
549 | struct shmem_inode_info *info = SHMEM_I(inode); | |
550 | ||
551 | spin_lock(&info->lock); | |
552 | shmem_recalc_inode(inode); | |
553 | spin_unlock(&info->lock); | |
554 | ||
555 | generic_fillattr(inode, stat); | |
556 | ||
557 | return 0; | |
558 | } | |
559 | ||
560 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) | |
561 | { | |
562 | struct inode *inode = d_inode(dentry); | |
563 | struct shmem_inode_info *info = SHMEM_I(inode); | |
564 | int error; | |
565 | ||
566 | error = inode_change_ok(inode, attr); | |
567 | if (error) | |
568 | return error; | |
569 | ||
570 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { | |
571 | loff_t oldsize = inode->i_size; | |
572 | loff_t newsize = attr->ia_size; | |
573 | ||
574 | /* protected by i_mutex */ | |
575 | if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) || | |
576 | (newsize > oldsize && (info->seals & F_SEAL_GROW))) | |
577 | return -EPERM; | |
578 | ||
579 | if (newsize != oldsize) { | |
580 | error = shmem_reacct_size(SHMEM_I(inode)->flags, | |
581 | oldsize, newsize); | |
582 | if (error) | |
583 | return error; | |
584 | i_size_write(inode, newsize); | |
585 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
586 | } | |
587 | if (newsize <= oldsize) { | |
588 | loff_t holebegin = round_up(newsize, PAGE_SIZE); | |
589 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
590 | shmem_truncate_range(inode, newsize, (loff_t)-1); | |
591 | /* unmap again to remove racily COWed private pages */ | |
592 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); | |
593 | } | |
594 | } | |
595 | ||
596 | setattr_copy(inode, attr); | |
597 | if (attr->ia_valid & ATTR_MODE) | |
598 | error = posix_acl_chmod(inode, inode->i_mode); | |
599 | return error; | |
600 | } | |
601 | ||
602 | static void shmem_evict_inode(struct inode *inode) | |
603 | { | |
604 | struct shmem_inode_info *info = SHMEM_I(inode); | |
605 | ||
606 | if (inode->i_mapping->a_ops == &shmem_aops) { | |
607 | shmem_unacct_size(info->flags, inode->i_size); | |
608 | inode->i_size = 0; | |
609 | shmem_truncate_range(inode, 0, (loff_t)-1); | |
610 | if (!list_empty(&info->swaplist)) { | |
611 | mutex_lock(&shmem_swaplist_mutex); | |
612 | list_del_init(&info->swaplist); | |
613 | mutex_unlock(&shmem_swaplist_mutex); | |
614 | } | |
615 | } else | |
616 | kfree(info->symlink); | |
617 | ||
618 | simple_xattrs_free(&info->xattrs); | |
619 | WARN_ON(inode->i_blocks); | |
620 | shmem_free_inode(inode->i_sb); | |
621 | clear_inode(inode); | |
622 | } | |
623 | ||
624 | /* | |
625 | * If swap found in inode, free it and move page from swapcache to filecache. | |
626 | */ | |
627 | static int shmem_unuse_inode(struct shmem_inode_info *info, | |
628 | swp_entry_t swap, struct page **pagep) | |
629 | { | |
630 | struct address_space *mapping = info->vfs_inode.i_mapping; | |
631 | void *radswap; | |
632 | pgoff_t index; | |
633 | gfp_t gfp; | |
634 | int error = 0; | |
635 | ||
636 | radswap = swp_to_radix_entry(swap); | |
637 | index = radix_tree_locate_item(&mapping->page_tree, radswap); | |
638 | if (index == -1) | |
639 | return -EAGAIN; /* tell shmem_unuse we found nothing */ | |
640 | ||
641 | /* | |
642 | * Move _head_ to start search for next from here. | |
643 | * But be careful: shmem_evict_inode checks list_empty without taking | |
644 | * mutex, and there's an instant in list_move_tail when info->swaplist | |
645 | * would appear empty, if it were the only one on shmem_swaplist. | |
646 | */ | |
647 | if (shmem_swaplist.next != &info->swaplist) | |
648 | list_move_tail(&shmem_swaplist, &info->swaplist); | |
649 | ||
650 | gfp = mapping_gfp_mask(mapping); | |
651 | if (shmem_should_replace_page(*pagep, gfp)) { | |
652 | mutex_unlock(&shmem_swaplist_mutex); | |
653 | error = shmem_replace_page(pagep, gfp, info, index); | |
654 | mutex_lock(&shmem_swaplist_mutex); | |
655 | /* | |
656 | * We needed to drop mutex to make that restrictive page | |
657 | * allocation, but the inode might have been freed while we | |
658 | * dropped it: although a racing shmem_evict_inode() cannot | |
659 | * complete without emptying the radix_tree, our page lock | |
660 | * on this swapcache page is not enough to prevent that - | |
661 | * free_swap_and_cache() of our swap entry will only | |
662 | * trylock_page(), removing swap from radix_tree whatever. | |
663 | * | |
664 | * We must not proceed to shmem_add_to_page_cache() if the | |
665 | * inode has been freed, but of course we cannot rely on | |
666 | * inode or mapping or info to check that. However, we can | |
667 | * safely check if our swap entry is still in use (and here | |
668 | * it can't have got reused for another page): if it's still | |
669 | * in use, then the inode cannot have been freed yet, and we | |
670 | * can safely proceed (if it's no longer in use, that tells | |
671 | * nothing about the inode, but we don't need to unuse swap). | |
672 | */ | |
673 | if (!page_swapcount(*pagep)) | |
674 | error = -ENOENT; | |
675 | } | |
676 | ||
677 | /* | |
678 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, | |
679 | * but also to hold up shmem_evict_inode(): so inode cannot be freed | |
680 | * beneath us (pagelock doesn't help until the page is in pagecache). | |
681 | */ | |
682 | if (!error) | |
683 | error = shmem_add_to_page_cache(*pagep, mapping, index, | |
684 | radswap); | |
685 | if (error != -ENOMEM) { | |
686 | /* | |
687 | * Truncation and eviction use free_swap_and_cache(), which | |
688 | * only does trylock page: if we raced, best clean up here. | |
689 | */ | |
690 | delete_from_swap_cache(*pagep); | |
691 | set_page_dirty(*pagep); | |
692 | if (!error) { | |
693 | spin_lock(&info->lock); | |
694 | info->swapped--; | |
695 | spin_unlock(&info->lock); | |
696 | swap_free(swap); | |
697 | } | |
698 | } | |
699 | return error; | |
700 | } | |
701 | ||
702 | /* | |
703 | * Search through swapped inodes to find and replace swap by page. | |
704 | */ | |
705 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
706 | { | |
707 | struct list_head *this, *next; | |
708 | struct shmem_inode_info *info; | |
709 | struct mem_cgroup *memcg; | |
710 | int error = 0; | |
711 | ||
712 | /* | |
713 | * There's a faint possibility that swap page was replaced before | |
714 | * caller locked it: caller will come back later with the right page. | |
715 | */ | |
716 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) | |
717 | goto out; | |
718 | ||
719 | /* | |
720 | * Charge page using GFP_KERNEL while we can wait, before taking | |
721 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). | |
722 | * Charged back to the user (not to caller) when swap account is used. | |
723 | */ | |
724 | error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg); | |
725 | if (error) | |
726 | goto out; | |
727 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ | |
728 | error = -EAGAIN; | |
729 | ||
730 | mutex_lock(&shmem_swaplist_mutex); | |
731 | list_for_each_safe(this, next, &shmem_swaplist) { | |
732 | info = list_entry(this, struct shmem_inode_info, swaplist); | |
733 | if (info->swapped) | |
734 | error = shmem_unuse_inode(info, swap, &page); | |
735 | else | |
736 | list_del_init(&info->swaplist); | |
737 | cond_resched(); | |
738 | if (error != -EAGAIN) | |
739 | break; | |
740 | /* found nothing in this: move on to search the next */ | |
741 | } | |
742 | mutex_unlock(&shmem_swaplist_mutex); | |
743 | ||
744 | if (error) { | |
745 | if (error != -ENOMEM) | |
746 | error = 0; | |
747 | mem_cgroup_cancel_charge(page, memcg); | |
748 | } else | |
749 | mem_cgroup_commit_charge(page, memcg, true); | |
750 | out: | |
751 | unlock_page(page); | |
752 | page_cache_release(page); | |
753 | return error; | |
754 | } | |
755 | ||
756 | /* | |
757 | * Move the page from the page cache to the swap cache. | |
758 | */ | |
759 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) | |
760 | { | |
761 | struct shmem_inode_info *info; | |
762 | struct address_space *mapping; | |
763 | struct inode *inode; | |
764 | swp_entry_t swap; | |
765 | pgoff_t index; | |
766 | ||
767 | BUG_ON(!PageLocked(page)); | |
768 | mapping = page->mapping; | |
769 | index = page->index; | |
770 | inode = mapping->host; | |
771 | info = SHMEM_I(inode); | |
772 | if (info->flags & VM_LOCKED) | |
773 | goto redirty; | |
774 | if (!total_swap_pages) | |
775 | goto redirty; | |
776 | ||
777 | /* | |
778 | * Our capabilities prevent regular writeback or sync from ever calling | |
779 | * shmem_writepage; but a stacking filesystem might use ->writepage of | |
780 | * its underlying filesystem, in which case tmpfs should write out to | |
781 | * swap only in response to memory pressure, and not for the writeback | |
782 | * threads or sync. | |
783 | */ | |
784 | if (!wbc->for_reclaim) { | |
785 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ | |
786 | goto redirty; | |
787 | } | |
788 | ||
789 | /* | |
790 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC | |
791 | * value into swapfile.c, the only way we can correctly account for a | |
792 | * fallocated page arriving here is now to initialize it and write it. | |
793 | * | |
794 | * That's okay for a page already fallocated earlier, but if we have | |
795 | * not yet completed the fallocation, then (a) we want to keep track | |
796 | * of this page in case we have to undo it, and (b) it may not be a | |
797 | * good idea to continue anyway, once we're pushing into swap. So | |
798 | * reactivate the page, and let shmem_fallocate() quit when too many. | |
799 | */ | |
800 | if (!PageUptodate(page)) { | |
801 | if (inode->i_private) { | |
802 | struct shmem_falloc *shmem_falloc; | |
803 | spin_lock(&inode->i_lock); | |
804 | shmem_falloc = inode->i_private; | |
805 | if (shmem_falloc && | |
806 | !shmem_falloc->waitq && | |
807 | index >= shmem_falloc->start && | |
808 | index < shmem_falloc->next) | |
809 | shmem_falloc->nr_unswapped++; | |
810 | else | |
811 | shmem_falloc = NULL; | |
812 | spin_unlock(&inode->i_lock); | |
813 | if (shmem_falloc) | |
814 | goto redirty; | |
815 | } | |
816 | clear_highpage(page); | |
817 | flush_dcache_page(page); | |
818 | SetPageUptodate(page); | |
819 | } | |
820 | ||
821 | swap = get_swap_page(); | |
822 | if (!swap.val) | |
823 | goto redirty; | |
824 | ||
825 | /* | |
826 | * Add inode to shmem_unuse()'s list of swapped-out inodes, | |
827 | * if it's not already there. Do it now before the page is | |
828 | * moved to swap cache, when its pagelock no longer protects | |
829 | * the inode from eviction. But don't unlock the mutex until | |
830 | * we've incremented swapped, because shmem_unuse_inode() will | |
831 | * prune a !swapped inode from the swaplist under this mutex. | |
832 | */ | |
833 | mutex_lock(&shmem_swaplist_mutex); | |
834 | if (list_empty(&info->swaplist)) | |
835 | list_add_tail(&info->swaplist, &shmem_swaplist); | |
836 | ||
837 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { | |
838 | swap_shmem_alloc(swap); | |
839 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); | |
840 | ||
841 | spin_lock(&info->lock); | |
842 | info->swapped++; | |
843 | shmem_recalc_inode(inode); | |
844 | spin_unlock(&info->lock); | |
845 | ||
846 | mutex_unlock(&shmem_swaplist_mutex); | |
847 | BUG_ON(page_mapped(page)); | |
848 | swap_writepage(page, wbc); | |
849 | return 0; | |
850 | } | |
851 | ||
852 | mutex_unlock(&shmem_swaplist_mutex); | |
853 | swapcache_free(swap); | |
854 | redirty: | |
855 | set_page_dirty(page); | |
856 | if (wbc->for_reclaim) | |
857 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ | |
858 | unlock_page(page); | |
859 | return 0; | |
860 | } | |
861 | ||
862 | #ifdef CONFIG_NUMA | |
863 | #ifdef CONFIG_TMPFS | |
864 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
865 | { | |
866 | char buffer[64]; | |
867 | ||
868 | if (!mpol || mpol->mode == MPOL_DEFAULT) | |
869 | return; /* show nothing */ | |
870 | ||
871 | mpol_to_str(buffer, sizeof(buffer), mpol); | |
872 | ||
873 | seq_printf(seq, ",mpol=%s", buffer); | |
874 | } | |
875 | ||
876 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
877 | { | |
878 | struct mempolicy *mpol = NULL; | |
879 | if (sbinfo->mpol) { | |
880 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ | |
881 | mpol = sbinfo->mpol; | |
882 | mpol_get(mpol); | |
883 | spin_unlock(&sbinfo->stat_lock); | |
884 | } | |
885 | return mpol; | |
886 | } | |
887 | #endif /* CONFIG_TMPFS */ | |
888 | ||
889 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
890 | struct shmem_inode_info *info, pgoff_t index) | |
891 | { | |
892 | struct vm_area_struct pvma; | |
893 | struct page *page; | |
894 | ||
895 | /* Create a pseudo vma that just contains the policy */ | |
896 | pvma.vm_start = 0; | |
897 | /* Bias interleave by inode number to distribute better across nodes */ | |
898 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
899 | pvma.vm_ops = NULL; | |
900 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
901 | ||
902 | page = swapin_readahead(swap, gfp, &pvma, 0); | |
903 | ||
904 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
905 | mpol_cond_put(pvma.vm_policy); | |
906 | ||
907 | return page; | |
908 | } | |
909 | ||
910 | static struct page *shmem_alloc_page(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 = alloc_page_vma(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 | #else /* !CONFIG_NUMA */ | |
931 | #ifdef CONFIG_TMPFS | |
932 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
933 | { | |
934 | } | |
935 | #endif /* CONFIG_TMPFS */ | |
936 | ||
937 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
938 | struct shmem_inode_info *info, pgoff_t index) | |
939 | { | |
940 | return swapin_readahead(swap, gfp, NULL, 0); | |
941 | } | |
942 | ||
943 | static inline struct page *shmem_alloc_page(gfp_t gfp, | |
944 | struct shmem_inode_info *info, pgoff_t index) | |
945 | { | |
946 | return alloc_page(gfp); | |
947 | } | |
948 | #endif /* CONFIG_NUMA */ | |
949 | ||
950 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) | |
951 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
952 | { | |
953 | return NULL; | |
954 | } | |
955 | #endif | |
956 | ||
957 | /* | |
958 | * When a page is moved from swapcache to shmem filecache (either by the | |
959 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of | |
960 | * shmem_unuse_inode()), it may have been read in earlier from swap, in | |
961 | * ignorance of the mapping it belongs to. If that mapping has special | |
962 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), | |
963 | * we may need to copy to a suitable page before moving to filecache. | |
964 | * | |
965 | * In a future release, this may well be extended to respect cpuset and | |
966 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); | |
967 | * but for now it is a simple matter of zone. | |
968 | */ | |
969 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) | |
970 | { | |
971 | return page_zonenum(page) > gfp_zone(gfp); | |
972 | } | |
973 | ||
974 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
975 | struct shmem_inode_info *info, pgoff_t index) | |
976 | { | |
977 | struct page *oldpage, *newpage; | |
978 | struct address_space *swap_mapping; | |
979 | pgoff_t swap_index; | |
980 | int error; | |
981 | ||
982 | oldpage = *pagep; | |
983 | swap_index = page_private(oldpage); | |
984 | swap_mapping = page_mapping(oldpage); | |
985 | ||
986 | /* | |
987 | * We have arrived here because our zones are constrained, so don't | |
988 | * limit chance of success by further cpuset and node constraints. | |
989 | */ | |
990 | gfp &= ~GFP_CONSTRAINT_MASK; | |
991 | newpage = shmem_alloc_page(gfp, info, index); | |
992 | if (!newpage) | |
993 | return -ENOMEM; | |
994 | ||
995 | page_cache_get(newpage); | |
996 | copy_highpage(newpage, oldpage); | |
997 | flush_dcache_page(newpage); | |
998 | ||
999 | __set_page_locked(newpage); | |
1000 | SetPageUptodate(newpage); | |
1001 | SetPageSwapBacked(newpage); | |
1002 | set_page_private(newpage, swap_index); | |
1003 | SetPageSwapCache(newpage); | |
1004 | ||
1005 | /* | |
1006 | * Our caller will very soon move newpage out of swapcache, but it's | |
1007 | * a nice clean interface for us to replace oldpage by newpage there. | |
1008 | */ | |
1009 | spin_lock_irq(&swap_mapping->tree_lock); | |
1010 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, | |
1011 | newpage); | |
1012 | if (!error) { | |
1013 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
1014 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); | |
1015 | } | |
1016 | spin_unlock_irq(&swap_mapping->tree_lock); | |
1017 | ||
1018 | if (unlikely(error)) { | |
1019 | /* | |
1020 | * Is this possible? I think not, now that our callers check | |
1021 | * both PageSwapCache and page_private after getting page lock; | |
1022 | * but be defensive. Reverse old to newpage for clear and free. | |
1023 | */ | |
1024 | oldpage = newpage; | |
1025 | } else { | |
1026 | mem_cgroup_replace_page(oldpage, newpage); | |
1027 | lru_cache_add_anon(newpage); | |
1028 | *pagep = newpage; | |
1029 | } | |
1030 | ||
1031 | ClearPageSwapCache(oldpage); | |
1032 | set_page_private(oldpage, 0); | |
1033 | ||
1034 | unlock_page(oldpage); | |
1035 | page_cache_release(oldpage); | |
1036 | page_cache_release(oldpage); | |
1037 | return error; | |
1038 | } | |
1039 | ||
1040 | /* | |
1041 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate | |
1042 | * | |
1043 | * If we allocate a new one we do not mark it dirty. That's up to the | |
1044 | * vm. If we swap it in we mark it dirty since we also free the swap | |
1045 | * entry since a page cannot live in both the swap and page cache | |
1046 | */ | |
1047 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
1048 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) | |
1049 | { | |
1050 | struct address_space *mapping = inode->i_mapping; | |
1051 | struct shmem_inode_info *info; | |
1052 | struct shmem_sb_info *sbinfo; | |
1053 | struct mem_cgroup *memcg; | |
1054 | struct page *page; | |
1055 | swp_entry_t swap; | |
1056 | int error; | |
1057 | int once = 0; | |
1058 | int alloced = 0; | |
1059 | ||
1060 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) | |
1061 | return -EFBIG; | |
1062 | repeat: | |
1063 | swap.val = 0; | |
1064 | page = find_lock_entry(mapping, index); | |
1065 | if (radix_tree_exceptional_entry(page)) { | |
1066 | swap = radix_to_swp_entry(page); | |
1067 | page = NULL; | |
1068 | } | |
1069 | ||
1070 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1071 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1072 | error = -EINVAL; | |
1073 | goto failed; | |
1074 | } | |
1075 | ||
1076 | if (page && sgp == SGP_WRITE) | |
1077 | mark_page_accessed(page); | |
1078 | ||
1079 | /* fallocated page? */ | |
1080 | if (page && !PageUptodate(page)) { | |
1081 | if (sgp != SGP_READ) | |
1082 | goto clear; | |
1083 | unlock_page(page); | |
1084 | page_cache_release(page); | |
1085 | page = NULL; | |
1086 | } | |
1087 | if (page || (sgp == SGP_READ && !swap.val)) { | |
1088 | *pagep = page; | |
1089 | return 0; | |
1090 | } | |
1091 | ||
1092 | /* | |
1093 | * Fast cache lookup did not find it: | |
1094 | * bring it back from swap or allocate. | |
1095 | */ | |
1096 | info = SHMEM_I(inode); | |
1097 | sbinfo = SHMEM_SB(inode->i_sb); | |
1098 | ||
1099 | if (swap.val) { | |
1100 | /* Look it up and read it in.. */ | |
1101 | page = lookup_swap_cache(swap); | |
1102 | if (!page) { | |
1103 | /* here we actually do the io */ | |
1104 | if (fault_type) | |
1105 | *fault_type |= VM_FAULT_MAJOR; | |
1106 | page = shmem_swapin(swap, gfp, info, index); | |
1107 | if (!page) { | |
1108 | error = -ENOMEM; | |
1109 | goto failed; | |
1110 | } | |
1111 | } | |
1112 | ||
1113 | /* We have to do this with page locked to prevent races */ | |
1114 | lock_page(page); | |
1115 | if (!PageSwapCache(page) || page_private(page) != swap.val || | |
1116 | !shmem_confirm_swap(mapping, index, swap)) { | |
1117 | error = -EEXIST; /* try again */ | |
1118 | goto unlock; | |
1119 | } | |
1120 | if (!PageUptodate(page)) { | |
1121 | error = -EIO; | |
1122 | goto failed; | |
1123 | } | |
1124 | wait_on_page_writeback(page); | |
1125 | ||
1126 | if (shmem_should_replace_page(page, gfp)) { | |
1127 | error = shmem_replace_page(&page, gfp, info, index); | |
1128 | if (error) | |
1129 | goto failed; | |
1130 | } | |
1131 | ||
1132 | error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg); | |
1133 | if (!error) { | |
1134 | error = shmem_add_to_page_cache(page, mapping, index, | |
1135 | swp_to_radix_entry(swap)); | |
1136 | /* | |
1137 | * We already confirmed swap under page lock, and make | |
1138 | * no memory allocation here, so usually no possibility | |
1139 | * of error; but free_swap_and_cache() only trylocks a | |
1140 | * page, so it is just possible that the entry has been | |
1141 | * truncated or holepunched since swap was confirmed. | |
1142 | * shmem_undo_range() will have done some of the | |
1143 | * unaccounting, now delete_from_swap_cache() will do | |
1144 | * the rest. | |
1145 | * Reset swap.val? No, leave it so "failed" goes back to | |
1146 | * "repeat": reading a hole and writing should succeed. | |
1147 | */ | |
1148 | if (error) { | |
1149 | mem_cgroup_cancel_charge(page, memcg); | |
1150 | delete_from_swap_cache(page); | |
1151 | } | |
1152 | } | |
1153 | if (error) | |
1154 | goto failed; | |
1155 | ||
1156 | mem_cgroup_commit_charge(page, memcg, true); | |
1157 | ||
1158 | spin_lock(&info->lock); | |
1159 | info->swapped--; | |
1160 | shmem_recalc_inode(inode); | |
1161 | spin_unlock(&info->lock); | |
1162 | ||
1163 | if (sgp == SGP_WRITE) | |
1164 | mark_page_accessed(page); | |
1165 | ||
1166 | delete_from_swap_cache(page); | |
1167 | set_page_dirty(page); | |
1168 | swap_free(swap); | |
1169 | ||
1170 | } else { | |
1171 | if (shmem_acct_block(info->flags)) { | |
1172 | error = -ENOSPC; | |
1173 | goto failed; | |
1174 | } | |
1175 | if (sbinfo->max_blocks) { | |
1176 | if (percpu_counter_compare(&sbinfo->used_blocks, | |
1177 | sbinfo->max_blocks) >= 0) { | |
1178 | error = -ENOSPC; | |
1179 | goto unacct; | |
1180 | } | |
1181 | percpu_counter_inc(&sbinfo->used_blocks); | |
1182 | } | |
1183 | ||
1184 | page = shmem_alloc_page(gfp, info, index); | |
1185 | if (!page) { | |
1186 | error = -ENOMEM; | |
1187 | goto decused; | |
1188 | } | |
1189 | ||
1190 | __SetPageSwapBacked(page); | |
1191 | __set_page_locked(page); | |
1192 | if (sgp == SGP_WRITE) | |
1193 | __SetPageReferenced(page); | |
1194 | ||
1195 | error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg); | |
1196 | if (error) | |
1197 | goto decused; | |
1198 | error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK); | |
1199 | if (!error) { | |
1200 | error = shmem_add_to_page_cache(page, mapping, index, | |
1201 | NULL); | |
1202 | radix_tree_preload_end(); | |
1203 | } | |
1204 | if (error) { | |
1205 | mem_cgroup_cancel_charge(page, memcg); | |
1206 | goto decused; | |
1207 | } | |
1208 | mem_cgroup_commit_charge(page, memcg, false); | |
1209 | lru_cache_add_anon(page); | |
1210 | ||
1211 | spin_lock(&info->lock); | |
1212 | info->alloced++; | |
1213 | inode->i_blocks += BLOCKS_PER_PAGE; | |
1214 | shmem_recalc_inode(inode); | |
1215 | spin_unlock(&info->lock); | |
1216 | alloced = true; | |
1217 | ||
1218 | /* | |
1219 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. | |
1220 | */ | |
1221 | if (sgp == SGP_FALLOC) | |
1222 | sgp = SGP_WRITE; | |
1223 | clear: | |
1224 | /* | |
1225 | * Let SGP_WRITE caller clear ends if write does not fill page; | |
1226 | * but SGP_FALLOC on a page fallocated earlier must initialize | |
1227 | * it now, lest undo on failure cancel our earlier guarantee. | |
1228 | */ | |
1229 | if (sgp != SGP_WRITE) { | |
1230 | clear_highpage(page); | |
1231 | flush_dcache_page(page); | |
1232 | SetPageUptodate(page); | |
1233 | } | |
1234 | if (sgp == SGP_DIRTY) | |
1235 | set_page_dirty(page); | |
1236 | } | |
1237 | ||
1238 | /* Perhaps the file has been truncated since we checked */ | |
1239 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1240 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1241 | error = -EINVAL; | |
1242 | if (alloced) | |
1243 | goto trunc; | |
1244 | else | |
1245 | goto failed; | |
1246 | } | |
1247 | *pagep = page; | |
1248 | return 0; | |
1249 | ||
1250 | /* | |
1251 | * Error recovery. | |
1252 | */ | |
1253 | trunc: | |
1254 | info = SHMEM_I(inode); | |
1255 | ClearPageDirty(page); | |
1256 | delete_from_page_cache(page); | |
1257 | spin_lock(&info->lock); | |
1258 | info->alloced--; | |
1259 | inode->i_blocks -= BLOCKS_PER_PAGE; | |
1260 | spin_unlock(&info->lock); | |
1261 | decused: | |
1262 | sbinfo = SHMEM_SB(inode->i_sb); | |
1263 | if (sbinfo->max_blocks) | |
1264 | percpu_counter_add(&sbinfo->used_blocks, -1); | |
1265 | unacct: | |
1266 | shmem_unacct_blocks(info->flags, 1); | |
1267 | failed: | |
1268 | if (swap.val && error != -EINVAL && | |
1269 | !shmem_confirm_swap(mapping, index, swap)) | |
1270 | error = -EEXIST; | |
1271 | unlock: | |
1272 | if (page) { | |
1273 | unlock_page(page); | |
1274 | page_cache_release(page); | |
1275 | } | |
1276 | if (error == -ENOSPC && !once++) { | |
1277 | info = SHMEM_I(inode); | |
1278 | spin_lock(&info->lock); | |
1279 | shmem_recalc_inode(inode); | |
1280 | spin_unlock(&info->lock); | |
1281 | goto repeat; | |
1282 | } | |
1283 | if (error == -EEXIST) /* from above or from radix_tree_insert */ | |
1284 | goto repeat; | |
1285 | return error; | |
1286 | } | |
1287 | ||
1288 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
1289 | { | |
1290 | struct inode *inode = file_inode(vma->vm_file); | |
1291 | int error; | |
1292 | int ret = VM_FAULT_LOCKED; | |
1293 | ||
1294 | /* | |
1295 | * Trinity finds that probing a hole which tmpfs is punching can | |
1296 | * prevent the hole-punch from ever completing: which in turn | |
1297 | * locks writers out with its hold on i_mutex. So refrain from | |
1298 | * faulting pages into the hole while it's being punched. Although | |
1299 | * shmem_undo_range() does remove the additions, it may be unable to | |
1300 | * keep up, as each new page needs its own unmap_mapping_range() call, | |
1301 | * and the i_mmap tree grows ever slower to scan if new vmas are added. | |
1302 | * | |
1303 | * It does not matter if we sometimes reach this check just before the | |
1304 | * hole-punch begins, so that one fault then races with the punch: | |
1305 | * we just need to make racing faults a rare case. | |
1306 | * | |
1307 | * The implementation below would be much simpler if we just used a | |
1308 | * standard mutex or completion: but we cannot take i_mutex in fault, | |
1309 | * and bloating every shmem inode for this unlikely case would be sad. | |
1310 | */ | |
1311 | if (unlikely(inode->i_private)) { | |
1312 | struct shmem_falloc *shmem_falloc; | |
1313 | ||
1314 | spin_lock(&inode->i_lock); | |
1315 | shmem_falloc = inode->i_private; | |
1316 | if (shmem_falloc && | |
1317 | shmem_falloc->waitq && | |
1318 | vmf->pgoff >= shmem_falloc->start && | |
1319 | vmf->pgoff < shmem_falloc->next) { | |
1320 | wait_queue_head_t *shmem_falloc_waitq; | |
1321 | DEFINE_WAIT(shmem_fault_wait); | |
1322 | ||
1323 | ret = VM_FAULT_NOPAGE; | |
1324 | if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) && | |
1325 | !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
1326 | /* It's polite to up mmap_sem if we can */ | |
1327 | up_read(&vma->vm_mm->mmap_sem); | |
1328 | ret = VM_FAULT_RETRY; | |
1329 | } | |
1330 | ||
1331 | shmem_falloc_waitq = shmem_falloc->waitq; | |
1332 | prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait, | |
1333 | TASK_UNINTERRUPTIBLE); | |
1334 | spin_unlock(&inode->i_lock); | |
1335 | schedule(); | |
1336 | ||
1337 | /* | |
1338 | * shmem_falloc_waitq points into the shmem_fallocate() | |
1339 | * stack of the hole-punching task: shmem_falloc_waitq | |
1340 | * is usually invalid by the time we reach here, but | |
1341 | * finish_wait() does not dereference it in that case; | |
1342 | * though i_lock needed lest racing with wake_up_all(). | |
1343 | */ | |
1344 | spin_lock(&inode->i_lock); | |
1345 | finish_wait(shmem_falloc_waitq, &shmem_fault_wait); | |
1346 | spin_unlock(&inode->i_lock); | |
1347 | return ret; | |
1348 | } | |
1349 | spin_unlock(&inode->i_lock); | |
1350 | } | |
1351 | ||
1352 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); | |
1353 | if (error) | |
1354 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); | |
1355 | ||
1356 | if (ret & VM_FAULT_MAJOR) { | |
1357 | count_vm_event(PGMAJFAULT); | |
1358 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
1359 | } | |
1360 | return ret; | |
1361 | } | |
1362 | ||
1363 | #ifdef CONFIG_NUMA | |
1364 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) | |
1365 | { | |
1366 | struct inode *inode = file_inode(vma->vm_file); | |
1367 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); | |
1368 | } | |
1369 | ||
1370 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, | |
1371 | unsigned long addr) | |
1372 | { | |
1373 | struct inode *inode = file_inode(vma->vm_file); | |
1374 | pgoff_t index; | |
1375 | ||
1376 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
1377 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); | |
1378 | } | |
1379 | #endif | |
1380 | ||
1381 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
1382 | { | |
1383 | struct inode *inode = file_inode(file); | |
1384 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1385 | int retval = -ENOMEM; | |
1386 | ||
1387 | spin_lock(&info->lock); | |
1388 | if (lock && !(info->flags & VM_LOCKED)) { | |
1389 | if (!user_shm_lock(inode->i_size, user)) | |
1390 | goto out_nomem; | |
1391 | info->flags |= VM_LOCKED; | |
1392 | mapping_set_unevictable(file->f_mapping); | |
1393 | } | |
1394 | if (!lock && (info->flags & VM_LOCKED) && user) { | |
1395 | user_shm_unlock(inode->i_size, user); | |
1396 | info->flags &= ~VM_LOCKED; | |
1397 | mapping_clear_unevictable(file->f_mapping); | |
1398 | } | |
1399 | retval = 0; | |
1400 | ||
1401 | out_nomem: | |
1402 | spin_unlock(&info->lock); | |
1403 | return retval; | |
1404 | } | |
1405 | ||
1406 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) | |
1407 | { | |
1408 | file_accessed(file); | |
1409 | vma->vm_ops = &shmem_vm_ops; | |
1410 | return 0; | |
1411 | } | |
1412 | ||
1413 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, | |
1414 | umode_t mode, dev_t dev, unsigned long flags) | |
1415 | { | |
1416 | struct inode *inode; | |
1417 | struct shmem_inode_info *info; | |
1418 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
1419 | ||
1420 | if (shmem_reserve_inode(sb)) | |
1421 | return NULL; | |
1422 | ||
1423 | inode = new_inode(sb); | |
1424 | if (inode) { | |
1425 | inode->i_ino = get_next_ino(); | |
1426 | inode_init_owner(inode, dir, mode); | |
1427 | inode->i_blocks = 0; | |
1428 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
1429 | inode->i_generation = get_seconds(); | |
1430 | info = SHMEM_I(inode); | |
1431 | memset(info, 0, (char *)inode - (char *)info); | |
1432 | spin_lock_init(&info->lock); | |
1433 | info->seals = F_SEAL_SEAL; | |
1434 | info->flags = flags & VM_NORESERVE; | |
1435 | INIT_LIST_HEAD(&info->swaplist); | |
1436 | simple_xattrs_init(&info->xattrs); | |
1437 | cache_no_acl(inode); | |
1438 | ||
1439 | switch (mode & S_IFMT) { | |
1440 | default: | |
1441 | inode->i_op = &shmem_special_inode_operations; | |
1442 | init_special_inode(inode, mode, dev); | |
1443 | break; | |
1444 | case S_IFREG: | |
1445 | inode->i_mapping->a_ops = &shmem_aops; | |
1446 | inode->i_op = &shmem_inode_operations; | |
1447 | inode->i_fop = &shmem_file_operations; | |
1448 | mpol_shared_policy_init(&info->policy, | |
1449 | shmem_get_sbmpol(sbinfo)); | |
1450 | break; | |
1451 | case S_IFDIR: | |
1452 | inc_nlink(inode); | |
1453 | /* Some things misbehave if size == 0 on a directory */ | |
1454 | inode->i_size = 2 * BOGO_DIRENT_SIZE; | |
1455 | inode->i_op = &shmem_dir_inode_operations; | |
1456 | inode->i_fop = &simple_dir_operations; | |
1457 | break; | |
1458 | case S_IFLNK: | |
1459 | /* | |
1460 | * Must not load anything in the rbtree, | |
1461 | * mpol_free_shared_policy will not be called. | |
1462 | */ | |
1463 | mpol_shared_policy_init(&info->policy, NULL); | |
1464 | break; | |
1465 | } | |
1466 | } else | |
1467 | shmem_free_inode(sb); | |
1468 | return inode; | |
1469 | } | |
1470 | ||
1471 | bool shmem_mapping(struct address_space *mapping) | |
1472 | { | |
1473 | if (!mapping->host) | |
1474 | return false; | |
1475 | ||
1476 | return mapping->host->i_sb->s_op == &shmem_ops; | |
1477 | } | |
1478 | ||
1479 | #ifdef CONFIG_TMPFS | |
1480 | static const struct inode_operations shmem_symlink_inode_operations; | |
1481 | static const struct inode_operations shmem_short_symlink_operations; | |
1482 | ||
1483 | #ifdef CONFIG_TMPFS_XATTR | |
1484 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); | |
1485 | #else | |
1486 | #define shmem_initxattrs NULL | |
1487 | #endif | |
1488 | ||
1489 | static int | |
1490 | shmem_write_begin(struct file *file, struct address_space *mapping, | |
1491 | loff_t pos, unsigned len, unsigned flags, | |
1492 | struct page **pagep, void **fsdata) | |
1493 | { | |
1494 | struct inode *inode = mapping->host; | |
1495 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1496 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
1497 | ||
1498 | /* i_mutex is held by caller */ | |
1499 | if (unlikely(info->seals)) { | |
1500 | if (info->seals & F_SEAL_WRITE) | |
1501 | return -EPERM; | |
1502 | if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size) | |
1503 | return -EPERM; | |
1504 | } | |
1505 | ||
1506 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); | |
1507 | } | |
1508 | ||
1509 | static int | |
1510 | shmem_write_end(struct file *file, struct address_space *mapping, | |
1511 | loff_t pos, unsigned len, unsigned copied, | |
1512 | struct page *page, void *fsdata) | |
1513 | { | |
1514 | struct inode *inode = mapping->host; | |
1515 | ||
1516 | if (pos + copied > inode->i_size) | |
1517 | i_size_write(inode, pos + copied); | |
1518 | ||
1519 | if (!PageUptodate(page)) { | |
1520 | if (copied < PAGE_CACHE_SIZE) { | |
1521 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
1522 | zero_user_segments(page, 0, from, | |
1523 | from + copied, PAGE_CACHE_SIZE); | |
1524 | } | |
1525 | SetPageUptodate(page); | |
1526 | } | |
1527 | set_page_dirty(page); | |
1528 | unlock_page(page); | |
1529 | page_cache_release(page); | |
1530 | ||
1531 | return copied; | |
1532 | } | |
1533 | ||
1534 | static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) | |
1535 | { | |
1536 | struct file *file = iocb->ki_filp; | |
1537 | struct inode *inode = file_inode(file); | |
1538 | struct address_space *mapping = inode->i_mapping; | |
1539 | pgoff_t index; | |
1540 | unsigned long offset; | |
1541 | enum sgp_type sgp = SGP_READ; | |
1542 | int error = 0; | |
1543 | ssize_t retval = 0; | |
1544 | loff_t *ppos = &iocb->ki_pos; | |
1545 | ||
1546 | /* | |
1547 | * Might this read be for a stacking filesystem? Then when reading | |
1548 | * holes of a sparse file, we actually need to allocate those pages, | |
1549 | * and even mark them dirty, so it cannot exceed the max_blocks limit. | |
1550 | */ | |
1551 | if (!iter_is_iovec(to)) | |
1552 | sgp = SGP_DIRTY; | |
1553 | ||
1554 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1555 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1556 | ||
1557 | for (;;) { | |
1558 | struct page *page = NULL; | |
1559 | pgoff_t end_index; | |
1560 | unsigned long nr, ret; | |
1561 | loff_t i_size = i_size_read(inode); | |
1562 | ||
1563 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1564 | if (index > end_index) | |
1565 | break; | |
1566 | if (index == end_index) { | |
1567 | nr = i_size & ~PAGE_CACHE_MASK; | |
1568 | if (nr <= offset) | |
1569 | break; | |
1570 | } | |
1571 | ||
1572 | error = shmem_getpage(inode, index, &page, sgp, NULL); | |
1573 | if (error) { | |
1574 | if (error == -EINVAL) | |
1575 | error = 0; | |
1576 | break; | |
1577 | } | |
1578 | if (page) | |
1579 | unlock_page(page); | |
1580 | ||
1581 | /* | |
1582 | * We must evaluate after, since reads (unlike writes) | |
1583 | * are called without i_mutex protection against truncate | |
1584 | */ | |
1585 | nr = PAGE_CACHE_SIZE; | |
1586 | i_size = i_size_read(inode); | |
1587 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1588 | if (index == end_index) { | |
1589 | nr = i_size & ~PAGE_CACHE_MASK; | |
1590 | if (nr <= offset) { | |
1591 | if (page) | |
1592 | page_cache_release(page); | |
1593 | break; | |
1594 | } | |
1595 | } | |
1596 | nr -= offset; | |
1597 | ||
1598 | if (page) { | |
1599 | /* | |
1600 | * If users can be writing to this page using arbitrary | |
1601 | * virtual addresses, take care about potential aliasing | |
1602 | * before reading the page on the kernel side. | |
1603 | */ | |
1604 | if (mapping_writably_mapped(mapping)) | |
1605 | flush_dcache_page(page); | |
1606 | /* | |
1607 | * Mark the page accessed if we read the beginning. | |
1608 | */ | |
1609 | if (!offset) | |
1610 | mark_page_accessed(page); | |
1611 | } else { | |
1612 | page = ZERO_PAGE(0); | |
1613 | page_cache_get(page); | |
1614 | } | |
1615 | ||
1616 | /* | |
1617 | * Ok, we have the page, and it's up-to-date, so | |
1618 | * now we can copy it to user space... | |
1619 | */ | |
1620 | ret = copy_page_to_iter(page, offset, nr, to); | |
1621 | retval += ret; | |
1622 | offset += ret; | |
1623 | index += offset >> PAGE_CACHE_SHIFT; | |
1624 | offset &= ~PAGE_CACHE_MASK; | |
1625 | ||
1626 | page_cache_release(page); | |
1627 | if (!iov_iter_count(to)) | |
1628 | break; | |
1629 | if (ret < nr) { | |
1630 | error = -EFAULT; | |
1631 | break; | |
1632 | } | |
1633 | cond_resched(); | |
1634 | } | |
1635 | ||
1636 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
1637 | file_accessed(file); | |
1638 | return retval ? retval : error; | |
1639 | } | |
1640 | ||
1641 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, | |
1642 | struct pipe_inode_info *pipe, size_t len, | |
1643 | unsigned int flags) | |
1644 | { | |
1645 | struct address_space *mapping = in->f_mapping; | |
1646 | struct inode *inode = mapping->host; | |
1647 | unsigned int loff, nr_pages, req_pages; | |
1648 | struct page *pages[PIPE_DEF_BUFFERS]; | |
1649 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1650 | struct page *page; | |
1651 | pgoff_t index, end_index; | |
1652 | loff_t isize, left; | |
1653 | int error, page_nr; | |
1654 | struct splice_pipe_desc spd = { | |
1655 | .pages = pages, | |
1656 | .partial = partial, | |
1657 | .nr_pages_max = PIPE_DEF_BUFFERS, | |
1658 | .flags = flags, | |
1659 | .ops = &page_cache_pipe_buf_ops, | |
1660 | .spd_release = spd_release_page, | |
1661 | }; | |
1662 | ||
1663 | isize = i_size_read(inode); | |
1664 | if (unlikely(*ppos >= isize)) | |
1665 | return 0; | |
1666 | ||
1667 | left = isize - *ppos; | |
1668 | if (unlikely(left < len)) | |
1669 | len = left; | |
1670 | ||
1671 | if (splice_grow_spd(pipe, &spd)) | |
1672 | return -ENOMEM; | |
1673 | ||
1674 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1675 | loff = *ppos & ~PAGE_CACHE_MASK; | |
1676 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1677 | nr_pages = min(req_pages, spd.nr_pages_max); | |
1678 | ||
1679 | spd.nr_pages = find_get_pages_contig(mapping, index, | |
1680 | nr_pages, spd.pages); | |
1681 | index += spd.nr_pages; | |
1682 | error = 0; | |
1683 | ||
1684 | while (spd.nr_pages < nr_pages) { | |
1685 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); | |
1686 | if (error) | |
1687 | break; | |
1688 | unlock_page(page); | |
1689 | spd.pages[spd.nr_pages++] = page; | |
1690 | index++; | |
1691 | } | |
1692 | ||
1693 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1694 | nr_pages = spd.nr_pages; | |
1695 | spd.nr_pages = 0; | |
1696 | ||
1697 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
1698 | unsigned int this_len; | |
1699 | ||
1700 | if (!len) | |
1701 | break; | |
1702 | ||
1703 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
1704 | page = spd.pages[page_nr]; | |
1705 | ||
1706 | if (!PageUptodate(page) || page->mapping != mapping) { | |
1707 | error = shmem_getpage(inode, index, &page, | |
1708 | SGP_CACHE, NULL); | |
1709 | if (error) | |
1710 | break; | |
1711 | unlock_page(page); | |
1712 | page_cache_release(spd.pages[page_nr]); | |
1713 | spd.pages[page_nr] = page; | |
1714 | } | |
1715 | ||
1716 | isize = i_size_read(inode); | |
1717 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1718 | if (unlikely(!isize || index > end_index)) | |
1719 | break; | |
1720 | ||
1721 | if (end_index == index) { | |
1722 | unsigned int plen; | |
1723 | ||
1724 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1725 | if (plen <= loff) | |
1726 | break; | |
1727 | ||
1728 | this_len = min(this_len, plen - loff); | |
1729 | len = this_len; | |
1730 | } | |
1731 | ||
1732 | spd.partial[page_nr].offset = loff; | |
1733 | spd.partial[page_nr].len = this_len; | |
1734 | len -= this_len; | |
1735 | loff = 0; | |
1736 | spd.nr_pages++; | |
1737 | index++; | |
1738 | } | |
1739 | ||
1740 | while (page_nr < nr_pages) | |
1741 | page_cache_release(spd.pages[page_nr++]); | |
1742 | ||
1743 | if (spd.nr_pages) | |
1744 | error = splice_to_pipe(pipe, &spd); | |
1745 | ||
1746 | splice_shrink_spd(&spd); | |
1747 | ||
1748 | if (error > 0) { | |
1749 | *ppos += error; | |
1750 | file_accessed(in); | |
1751 | } | |
1752 | return error; | |
1753 | } | |
1754 | ||
1755 | /* | |
1756 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. | |
1757 | */ | |
1758 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, | |
1759 | pgoff_t index, pgoff_t end, int whence) | |
1760 | { | |
1761 | struct page *page; | |
1762 | struct pagevec pvec; | |
1763 | pgoff_t indices[PAGEVEC_SIZE]; | |
1764 | bool done = false; | |
1765 | int i; | |
1766 | ||
1767 | pagevec_init(&pvec, 0); | |
1768 | pvec.nr = 1; /* start small: we may be there already */ | |
1769 | while (!done) { | |
1770 | pvec.nr = find_get_entries(mapping, index, | |
1771 | pvec.nr, pvec.pages, indices); | |
1772 | if (!pvec.nr) { | |
1773 | if (whence == SEEK_DATA) | |
1774 | index = end; | |
1775 | break; | |
1776 | } | |
1777 | for (i = 0; i < pvec.nr; i++, index++) { | |
1778 | if (index < indices[i]) { | |
1779 | if (whence == SEEK_HOLE) { | |
1780 | done = true; | |
1781 | break; | |
1782 | } | |
1783 | index = indices[i]; | |
1784 | } | |
1785 | page = pvec.pages[i]; | |
1786 | if (page && !radix_tree_exceptional_entry(page)) { | |
1787 | if (!PageUptodate(page)) | |
1788 | page = NULL; | |
1789 | } | |
1790 | if (index >= end || | |
1791 | (page && whence == SEEK_DATA) || | |
1792 | (!page && whence == SEEK_HOLE)) { | |
1793 | done = true; | |
1794 | break; | |
1795 | } | |
1796 | } | |
1797 | pagevec_remove_exceptionals(&pvec); | |
1798 | pagevec_release(&pvec); | |
1799 | pvec.nr = PAGEVEC_SIZE; | |
1800 | cond_resched(); | |
1801 | } | |
1802 | return index; | |
1803 | } | |
1804 | ||
1805 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) | |
1806 | { | |
1807 | struct address_space *mapping = file->f_mapping; | |
1808 | struct inode *inode = mapping->host; | |
1809 | pgoff_t start, end; | |
1810 | loff_t new_offset; | |
1811 | ||
1812 | if (whence != SEEK_DATA && whence != SEEK_HOLE) | |
1813 | return generic_file_llseek_size(file, offset, whence, | |
1814 | MAX_LFS_FILESIZE, i_size_read(inode)); | |
1815 | mutex_lock(&inode->i_mutex); | |
1816 | /* We're holding i_mutex so we can access i_size directly */ | |
1817 | ||
1818 | if (offset < 0) | |
1819 | offset = -EINVAL; | |
1820 | else if (offset >= inode->i_size) | |
1821 | offset = -ENXIO; | |
1822 | else { | |
1823 | start = offset >> PAGE_CACHE_SHIFT; | |
1824 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1825 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); | |
1826 | new_offset <<= PAGE_CACHE_SHIFT; | |
1827 | if (new_offset > offset) { | |
1828 | if (new_offset < inode->i_size) | |
1829 | offset = new_offset; | |
1830 | else if (whence == SEEK_DATA) | |
1831 | offset = -ENXIO; | |
1832 | else | |
1833 | offset = inode->i_size; | |
1834 | } | |
1835 | } | |
1836 | ||
1837 | if (offset >= 0) | |
1838 | offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); | |
1839 | mutex_unlock(&inode->i_mutex); | |
1840 | return offset; | |
1841 | } | |
1842 | ||
1843 | /* | |
1844 | * We need a tag: a new tag would expand every radix_tree_node by 8 bytes, | |
1845 | * so reuse a tag which we firmly believe is never set or cleared on shmem. | |
1846 | */ | |
1847 | #define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE | |
1848 | #define LAST_SCAN 4 /* about 150ms max */ | |
1849 | ||
1850 | static void shmem_tag_pins(struct address_space *mapping) | |
1851 | { | |
1852 | struct radix_tree_iter iter; | |
1853 | void **slot; | |
1854 | pgoff_t start; | |
1855 | struct page *page; | |
1856 | ||
1857 | lru_add_drain(); | |
1858 | start = 0; | |
1859 | rcu_read_lock(); | |
1860 | ||
1861 | restart: | |
1862 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
1863 | page = radix_tree_deref_slot(slot); | |
1864 | if (!page || radix_tree_exception(page)) { | |
1865 | if (radix_tree_deref_retry(page)) | |
1866 | goto restart; | |
1867 | } else if (page_count(page) - page_mapcount(page) > 1) { | |
1868 | spin_lock_irq(&mapping->tree_lock); | |
1869 | radix_tree_tag_set(&mapping->page_tree, iter.index, | |
1870 | SHMEM_TAG_PINNED); | |
1871 | spin_unlock_irq(&mapping->tree_lock); | |
1872 | } | |
1873 | ||
1874 | if (need_resched()) { | |
1875 | cond_resched_rcu(); | |
1876 | start = iter.index + 1; | |
1877 | goto restart; | |
1878 | } | |
1879 | } | |
1880 | rcu_read_unlock(); | |
1881 | } | |
1882 | ||
1883 | /* | |
1884 | * Setting SEAL_WRITE requires us to verify there's no pending writer. However, | |
1885 | * via get_user_pages(), drivers might have some pending I/O without any active | |
1886 | * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages | |
1887 | * and see whether it has an elevated ref-count. If so, we tag them and wait for | |
1888 | * them to be dropped. | |
1889 | * The caller must guarantee that no new user will acquire writable references | |
1890 | * to those pages to avoid races. | |
1891 | */ | |
1892 | static int shmem_wait_for_pins(struct address_space *mapping) | |
1893 | { | |
1894 | struct radix_tree_iter iter; | |
1895 | void **slot; | |
1896 | pgoff_t start; | |
1897 | struct page *page; | |
1898 | int error, scan; | |
1899 | ||
1900 | shmem_tag_pins(mapping); | |
1901 | ||
1902 | error = 0; | |
1903 | for (scan = 0; scan <= LAST_SCAN; scan++) { | |
1904 | if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED)) | |
1905 | break; | |
1906 | ||
1907 | if (!scan) | |
1908 | lru_add_drain_all(); | |
1909 | else if (schedule_timeout_killable((HZ << scan) / 200)) | |
1910 | scan = LAST_SCAN; | |
1911 | ||
1912 | start = 0; | |
1913 | rcu_read_lock(); | |
1914 | restart: | |
1915 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, | |
1916 | start, SHMEM_TAG_PINNED) { | |
1917 | ||
1918 | page = radix_tree_deref_slot(slot); | |
1919 | if (radix_tree_exception(page)) { | |
1920 | if (radix_tree_deref_retry(page)) | |
1921 | goto restart; | |
1922 | ||
1923 | page = NULL; | |
1924 | } | |
1925 | ||
1926 | if (page && | |
1927 | page_count(page) - page_mapcount(page) != 1) { | |
1928 | if (scan < LAST_SCAN) | |
1929 | goto continue_resched; | |
1930 | ||
1931 | /* | |
1932 | * On the last scan, we clean up all those tags | |
1933 | * we inserted; but make a note that we still | |
1934 | * found pages pinned. | |
1935 | */ | |
1936 | error = -EBUSY; | |
1937 | } | |
1938 | ||
1939 | spin_lock_irq(&mapping->tree_lock); | |
1940 | radix_tree_tag_clear(&mapping->page_tree, | |
1941 | iter.index, SHMEM_TAG_PINNED); | |
1942 | spin_unlock_irq(&mapping->tree_lock); | |
1943 | continue_resched: | |
1944 | if (need_resched()) { | |
1945 | cond_resched_rcu(); | |
1946 | start = iter.index + 1; | |
1947 | goto restart; | |
1948 | } | |
1949 | } | |
1950 | rcu_read_unlock(); | |
1951 | } | |
1952 | ||
1953 | return error; | |
1954 | } | |
1955 | ||
1956 | #define F_ALL_SEALS (F_SEAL_SEAL | \ | |
1957 | F_SEAL_SHRINK | \ | |
1958 | F_SEAL_GROW | \ | |
1959 | F_SEAL_WRITE) | |
1960 | ||
1961 | int shmem_add_seals(struct file *file, unsigned int seals) | |
1962 | { | |
1963 | struct inode *inode = file_inode(file); | |
1964 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1965 | int error; | |
1966 | ||
1967 | /* | |
1968 | * SEALING | |
1969 | * Sealing allows multiple parties to share a shmem-file but restrict | |
1970 | * access to a specific subset of file operations. Seals can only be | |
1971 | * added, but never removed. This way, mutually untrusted parties can | |
1972 | * share common memory regions with a well-defined policy. A malicious | |
1973 | * peer can thus never perform unwanted operations on a shared object. | |
1974 | * | |
1975 | * Seals are only supported on special shmem-files and always affect | |
1976 | * the whole underlying inode. Once a seal is set, it may prevent some | |
1977 | * kinds of access to the file. Currently, the following seals are | |
1978 | * defined: | |
1979 | * SEAL_SEAL: Prevent further seals from being set on this file | |
1980 | * SEAL_SHRINK: Prevent the file from shrinking | |
1981 | * SEAL_GROW: Prevent the file from growing | |
1982 | * SEAL_WRITE: Prevent write access to the file | |
1983 | * | |
1984 | * As we don't require any trust relationship between two parties, we | |
1985 | * must prevent seals from being removed. Therefore, sealing a file | |
1986 | * only adds a given set of seals to the file, it never touches | |
1987 | * existing seals. Furthermore, the "setting seals"-operation can be | |
1988 | * sealed itself, which basically prevents any further seal from being | |
1989 | * added. | |
1990 | * | |
1991 | * Semantics of sealing are only defined on volatile files. Only | |
1992 | * anonymous shmem files support sealing. More importantly, seals are | |
1993 | * never written to disk. Therefore, there's no plan to support it on | |
1994 | * other file types. | |
1995 | */ | |
1996 | ||
1997 | if (file->f_op != &shmem_file_operations) | |
1998 | return -EINVAL; | |
1999 | if (!(file->f_mode & FMODE_WRITE)) | |
2000 | return -EPERM; | |
2001 | if (seals & ~(unsigned int)F_ALL_SEALS) | |
2002 | return -EINVAL; | |
2003 | ||
2004 | mutex_lock(&inode->i_mutex); | |
2005 | ||
2006 | if (info->seals & F_SEAL_SEAL) { | |
2007 | error = -EPERM; | |
2008 | goto unlock; | |
2009 | } | |
2010 | ||
2011 | if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) { | |
2012 | error = mapping_deny_writable(file->f_mapping); | |
2013 | if (error) | |
2014 | goto unlock; | |
2015 | ||
2016 | error = shmem_wait_for_pins(file->f_mapping); | |
2017 | if (error) { | |
2018 | mapping_allow_writable(file->f_mapping); | |
2019 | goto unlock; | |
2020 | } | |
2021 | } | |
2022 | ||
2023 | info->seals |= seals; | |
2024 | error = 0; | |
2025 | ||
2026 | unlock: | |
2027 | mutex_unlock(&inode->i_mutex); | |
2028 | return error; | |
2029 | } | |
2030 | EXPORT_SYMBOL_GPL(shmem_add_seals); | |
2031 | ||
2032 | int shmem_get_seals(struct file *file) | |
2033 | { | |
2034 | if (file->f_op != &shmem_file_operations) | |
2035 | return -EINVAL; | |
2036 | ||
2037 | return SHMEM_I(file_inode(file))->seals; | |
2038 | } | |
2039 | EXPORT_SYMBOL_GPL(shmem_get_seals); | |
2040 | ||
2041 | long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg) | |
2042 | { | |
2043 | long error; | |
2044 | ||
2045 | switch (cmd) { | |
2046 | case F_ADD_SEALS: | |
2047 | /* disallow upper 32bit */ | |
2048 | if (arg > UINT_MAX) | |
2049 | return -EINVAL; | |
2050 | ||
2051 | error = shmem_add_seals(file, arg); | |
2052 | break; | |
2053 | case F_GET_SEALS: | |
2054 | error = shmem_get_seals(file); | |
2055 | break; | |
2056 | default: | |
2057 | error = -EINVAL; | |
2058 | break; | |
2059 | } | |
2060 | ||
2061 | return error; | |
2062 | } | |
2063 | ||
2064 | static long shmem_fallocate(struct file *file, int mode, loff_t offset, | |
2065 | loff_t len) | |
2066 | { | |
2067 | struct inode *inode = file_inode(file); | |
2068 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
2069 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2070 | struct shmem_falloc shmem_falloc; | |
2071 | pgoff_t start, index, end; | |
2072 | int error; | |
2073 | ||
2074 | if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) | |
2075 | return -EOPNOTSUPP; | |
2076 | ||
2077 | mutex_lock(&inode->i_mutex); | |
2078 | ||
2079 | if (mode & FALLOC_FL_PUNCH_HOLE) { | |
2080 | struct address_space *mapping = file->f_mapping; | |
2081 | loff_t unmap_start = round_up(offset, PAGE_SIZE); | |
2082 | loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; | |
2083 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq); | |
2084 | ||
2085 | /* protected by i_mutex */ | |
2086 | if (info->seals & F_SEAL_WRITE) { | |
2087 | error = -EPERM; | |
2088 | goto out; | |
2089 | } | |
2090 | ||
2091 | shmem_falloc.waitq = &shmem_falloc_waitq; | |
2092 | shmem_falloc.start = unmap_start >> PAGE_SHIFT; | |
2093 | shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT; | |
2094 | spin_lock(&inode->i_lock); | |
2095 | inode->i_private = &shmem_falloc; | |
2096 | spin_unlock(&inode->i_lock); | |
2097 | ||
2098 | if ((u64)unmap_end > (u64)unmap_start) | |
2099 | unmap_mapping_range(mapping, unmap_start, | |
2100 | 1 + unmap_end - unmap_start, 0); | |
2101 | shmem_truncate_range(inode, offset, offset + len - 1); | |
2102 | /* No need to unmap again: hole-punching leaves COWed pages */ | |
2103 | ||
2104 | spin_lock(&inode->i_lock); | |
2105 | inode->i_private = NULL; | |
2106 | wake_up_all(&shmem_falloc_waitq); | |
2107 | spin_unlock(&inode->i_lock); | |
2108 | error = 0; | |
2109 | goto out; | |
2110 | } | |
2111 | ||
2112 | /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ | |
2113 | error = inode_newsize_ok(inode, offset + len); | |
2114 | if (error) | |
2115 | goto out; | |
2116 | ||
2117 | if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) { | |
2118 | error = -EPERM; | |
2119 | goto out; | |
2120 | } | |
2121 | ||
2122 | start = offset >> PAGE_CACHE_SHIFT; | |
2123 | end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
2124 | /* Try to avoid a swapstorm if len is impossible to satisfy */ | |
2125 | if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { | |
2126 | error = -ENOSPC; | |
2127 | goto out; | |
2128 | } | |
2129 | ||
2130 | shmem_falloc.waitq = NULL; | |
2131 | shmem_falloc.start = start; | |
2132 | shmem_falloc.next = start; | |
2133 | shmem_falloc.nr_falloced = 0; | |
2134 | shmem_falloc.nr_unswapped = 0; | |
2135 | spin_lock(&inode->i_lock); | |
2136 | inode->i_private = &shmem_falloc; | |
2137 | spin_unlock(&inode->i_lock); | |
2138 | ||
2139 | for (index = start; index < end; index++) { | |
2140 | struct page *page; | |
2141 | ||
2142 | /* | |
2143 | * Good, the fallocate(2) manpage permits EINTR: we may have | |
2144 | * been interrupted because we are using up too much memory. | |
2145 | */ | |
2146 | if (signal_pending(current)) | |
2147 | error = -EINTR; | |
2148 | else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) | |
2149 | error = -ENOMEM; | |
2150 | else | |
2151 | error = shmem_getpage(inode, index, &page, SGP_FALLOC, | |
2152 | NULL); | |
2153 | if (error) { | |
2154 | /* Remove the !PageUptodate pages we added */ | |
2155 | shmem_undo_range(inode, | |
2156 | (loff_t)start << PAGE_CACHE_SHIFT, | |
2157 | (loff_t)index << PAGE_CACHE_SHIFT, true); | |
2158 | goto undone; | |
2159 | } | |
2160 | ||
2161 | /* | |
2162 | * Inform shmem_writepage() how far we have reached. | |
2163 | * No need for lock or barrier: we have the page lock. | |
2164 | */ | |
2165 | shmem_falloc.next++; | |
2166 | if (!PageUptodate(page)) | |
2167 | shmem_falloc.nr_falloced++; | |
2168 | ||
2169 | /* | |
2170 | * If !PageUptodate, leave it that way so that freeable pages | |
2171 | * can be recognized if we need to rollback on error later. | |
2172 | * But set_page_dirty so that memory pressure will swap rather | |
2173 | * than free the pages we are allocating (and SGP_CACHE pages | |
2174 | * might still be clean: we now need to mark those dirty too). | |
2175 | */ | |
2176 | set_page_dirty(page); | |
2177 | unlock_page(page); | |
2178 | page_cache_release(page); | |
2179 | cond_resched(); | |
2180 | } | |
2181 | ||
2182 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) | |
2183 | i_size_write(inode, offset + len); | |
2184 | inode->i_ctime = CURRENT_TIME; | |
2185 | undone: | |
2186 | spin_lock(&inode->i_lock); | |
2187 | inode->i_private = NULL; | |
2188 | spin_unlock(&inode->i_lock); | |
2189 | out: | |
2190 | mutex_unlock(&inode->i_mutex); | |
2191 | return error; | |
2192 | } | |
2193 | ||
2194 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) | |
2195 | { | |
2196 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); | |
2197 | ||
2198 | buf->f_type = TMPFS_MAGIC; | |
2199 | buf->f_bsize = PAGE_CACHE_SIZE; | |
2200 | buf->f_namelen = NAME_MAX; | |
2201 | if (sbinfo->max_blocks) { | |
2202 | buf->f_blocks = sbinfo->max_blocks; | |
2203 | buf->f_bavail = | |
2204 | buf->f_bfree = sbinfo->max_blocks - | |
2205 | percpu_counter_sum(&sbinfo->used_blocks); | |
2206 | } | |
2207 | if (sbinfo->max_inodes) { | |
2208 | buf->f_files = sbinfo->max_inodes; | |
2209 | buf->f_ffree = sbinfo->free_inodes; | |
2210 | } | |
2211 | /* else leave those fields 0 like simple_statfs */ | |
2212 | return 0; | |
2213 | } | |
2214 | ||
2215 | /* | |
2216 | * File creation. Allocate an inode, and we're done.. | |
2217 | */ | |
2218 | static int | |
2219 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) | |
2220 | { | |
2221 | struct inode *inode; | |
2222 | int error = -ENOSPC; | |
2223 | ||
2224 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); | |
2225 | if (inode) { | |
2226 | error = simple_acl_create(dir, inode); | |
2227 | if (error) | |
2228 | goto out_iput; | |
2229 | error = security_inode_init_security(inode, dir, | |
2230 | &dentry->d_name, | |
2231 | shmem_initxattrs, NULL); | |
2232 | if (error && error != -EOPNOTSUPP) | |
2233 | goto out_iput; | |
2234 | ||
2235 | error = 0; | |
2236 | dir->i_size += BOGO_DIRENT_SIZE; | |
2237 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2238 | d_instantiate(dentry, inode); | |
2239 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2240 | } | |
2241 | return error; | |
2242 | out_iput: | |
2243 | iput(inode); | |
2244 | return error; | |
2245 | } | |
2246 | ||
2247 | static int | |
2248 | shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) | |
2249 | { | |
2250 | struct inode *inode; | |
2251 | int error = -ENOSPC; | |
2252 | ||
2253 | inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); | |
2254 | if (inode) { | |
2255 | error = security_inode_init_security(inode, dir, | |
2256 | NULL, | |
2257 | shmem_initxattrs, NULL); | |
2258 | if (error && error != -EOPNOTSUPP) | |
2259 | goto out_iput; | |
2260 | error = simple_acl_create(dir, inode); | |
2261 | if (error) | |
2262 | goto out_iput; | |
2263 | d_tmpfile(dentry, inode); | |
2264 | } | |
2265 | return error; | |
2266 | out_iput: | |
2267 | iput(inode); | |
2268 | return error; | |
2269 | } | |
2270 | ||
2271 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
2272 | { | |
2273 | int error; | |
2274 | ||
2275 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) | |
2276 | return error; | |
2277 | inc_nlink(dir); | |
2278 | return 0; | |
2279 | } | |
2280 | ||
2281 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
2282 | bool excl) | |
2283 | { | |
2284 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); | |
2285 | } | |
2286 | ||
2287 | /* | |
2288 | * Link a file.. | |
2289 | */ | |
2290 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
2291 | { | |
2292 | struct inode *inode = d_inode(old_dentry); | |
2293 | int ret; | |
2294 | ||
2295 | /* | |
2296 | * No ordinary (disk based) filesystem counts links as inodes; | |
2297 | * but each new link needs a new dentry, pinning lowmem, and | |
2298 | * tmpfs dentries cannot be pruned until they are unlinked. | |
2299 | */ | |
2300 | ret = shmem_reserve_inode(inode->i_sb); | |
2301 | if (ret) | |
2302 | goto out; | |
2303 | ||
2304 | dir->i_size += BOGO_DIRENT_SIZE; | |
2305 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2306 | inc_nlink(inode); | |
2307 | ihold(inode); /* New dentry reference */ | |
2308 | dget(dentry); /* Extra pinning count for the created dentry */ | |
2309 | d_instantiate(dentry, inode); | |
2310 | out: | |
2311 | return ret; | |
2312 | } | |
2313 | ||
2314 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) | |
2315 | { | |
2316 | struct inode *inode = d_inode(dentry); | |
2317 | ||
2318 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) | |
2319 | shmem_free_inode(inode->i_sb); | |
2320 | ||
2321 | dir->i_size -= BOGO_DIRENT_SIZE; | |
2322 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2323 | drop_nlink(inode); | |
2324 | dput(dentry); /* Undo the count from "create" - this does all the work */ | |
2325 | return 0; | |
2326 | } | |
2327 | ||
2328 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) | |
2329 | { | |
2330 | if (!simple_empty(dentry)) | |
2331 | return -ENOTEMPTY; | |
2332 | ||
2333 | drop_nlink(d_inode(dentry)); | |
2334 | drop_nlink(dir); | |
2335 | return shmem_unlink(dir, dentry); | |
2336 | } | |
2337 | ||
2338 | static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) | |
2339 | { | |
2340 | bool old_is_dir = d_is_dir(old_dentry); | |
2341 | bool new_is_dir = d_is_dir(new_dentry); | |
2342 | ||
2343 | if (old_dir != new_dir && old_is_dir != new_is_dir) { | |
2344 | if (old_is_dir) { | |
2345 | drop_nlink(old_dir); | |
2346 | inc_nlink(new_dir); | |
2347 | } else { | |
2348 | drop_nlink(new_dir); | |
2349 | inc_nlink(old_dir); | |
2350 | } | |
2351 | } | |
2352 | old_dir->i_ctime = old_dir->i_mtime = | |
2353 | new_dir->i_ctime = new_dir->i_mtime = | |
2354 | d_inode(old_dentry)->i_ctime = | |
2355 | d_inode(new_dentry)->i_ctime = CURRENT_TIME; | |
2356 | ||
2357 | return 0; | |
2358 | } | |
2359 | ||
2360 | static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry) | |
2361 | { | |
2362 | struct dentry *whiteout; | |
2363 | int error; | |
2364 | ||
2365 | whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name); | |
2366 | if (!whiteout) | |
2367 | return -ENOMEM; | |
2368 | ||
2369 | error = shmem_mknod(old_dir, whiteout, | |
2370 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
2371 | dput(whiteout); | |
2372 | if (error) | |
2373 | return error; | |
2374 | ||
2375 | /* | |
2376 | * Cheat and hash the whiteout while the old dentry is still in | |
2377 | * place, instead of playing games with FS_RENAME_DOES_D_MOVE. | |
2378 | * | |
2379 | * d_lookup() will consistently find one of them at this point, | |
2380 | * not sure which one, but that isn't even important. | |
2381 | */ | |
2382 | d_rehash(whiteout); | |
2383 | return 0; | |
2384 | } | |
2385 | ||
2386 | /* | |
2387 | * The VFS layer already does all the dentry stuff for rename, | |
2388 | * we just have to decrement the usage count for the target if | |
2389 | * it exists so that the VFS layer correctly free's it when it | |
2390 | * gets overwritten. | |
2391 | */ | |
2392 | static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) | |
2393 | { | |
2394 | struct inode *inode = d_inode(old_dentry); | |
2395 | int they_are_dirs = S_ISDIR(inode->i_mode); | |
2396 | ||
2397 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) | |
2398 | return -EINVAL; | |
2399 | ||
2400 | if (flags & RENAME_EXCHANGE) | |
2401 | return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry); | |
2402 | ||
2403 | if (!simple_empty(new_dentry)) | |
2404 | return -ENOTEMPTY; | |
2405 | ||
2406 | if (flags & RENAME_WHITEOUT) { | |
2407 | int error; | |
2408 | ||
2409 | error = shmem_whiteout(old_dir, old_dentry); | |
2410 | if (error) | |
2411 | return error; | |
2412 | } | |
2413 | ||
2414 | if (d_really_is_positive(new_dentry)) { | |
2415 | (void) shmem_unlink(new_dir, new_dentry); | |
2416 | if (they_are_dirs) { | |
2417 | drop_nlink(d_inode(new_dentry)); | |
2418 | drop_nlink(old_dir); | |
2419 | } | |
2420 | } else if (they_are_dirs) { | |
2421 | drop_nlink(old_dir); | |
2422 | inc_nlink(new_dir); | |
2423 | } | |
2424 | ||
2425 | old_dir->i_size -= BOGO_DIRENT_SIZE; | |
2426 | new_dir->i_size += BOGO_DIRENT_SIZE; | |
2427 | old_dir->i_ctime = old_dir->i_mtime = | |
2428 | new_dir->i_ctime = new_dir->i_mtime = | |
2429 | inode->i_ctime = CURRENT_TIME; | |
2430 | return 0; | |
2431 | } | |
2432 | ||
2433 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) | |
2434 | { | |
2435 | int error; | |
2436 | int len; | |
2437 | struct inode *inode; | |
2438 | struct page *page; | |
2439 | char *kaddr; | |
2440 | struct shmem_inode_info *info; | |
2441 | ||
2442 | len = strlen(symname) + 1; | |
2443 | if (len > PAGE_CACHE_SIZE) | |
2444 | return -ENAMETOOLONG; | |
2445 | ||
2446 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); | |
2447 | if (!inode) | |
2448 | return -ENOSPC; | |
2449 | ||
2450 | error = security_inode_init_security(inode, dir, &dentry->d_name, | |
2451 | shmem_initxattrs, NULL); | |
2452 | if (error) { | |
2453 | if (error != -EOPNOTSUPP) { | |
2454 | iput(inode); | |
2455 | return error; | |
2456 | } | |
2457 | error = 0; | |
2458 | } | |
2459 | ||
2460 | info = SHMEM_I(inode); | |
2461 | inode->i_size = len-1; | |
2462 | if (len <= SHORT_SYMLINK_LEN) { | |
2463 | info->symlink = kmemdup(symname, len, GFP_KERNEL); | |
2464 | if (!info->symlink) { | |
2465 | iput(inode); | |
2466 | return -ENOMEM; | |
2467 | } | |
2468 | inode->i_op = &shmem_short_symlink_operations; | |
2469 | inode->i_link = info->symlink; | |
2470 | } else { | |
2471 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); | |
2472 | if (error) { | |
2473 | iput(inode); | |
2474 | return error; | |
2475 | } | |
2476 | inode->i_mapping->a_ops = &shmem_aops; | |
2477 | inode->i_op = &shmem_symlink_inode_operations; | |
2478 | kaddr = kmap_atomic(page); | |
2479 | memcpy(kaddr, symname, len); | |
2480 | kunmap_atomic(kaddr); | |
2481 | SetPageUptodate(page); | |
2482 | set_page_dirty(page); | |
2483 | unlock_page(page); | |
2484 | page_cache_release(page); | |
2485 | } | |
2486 | dir->i_size += BOGO_DIRENT_SIZE; | |
2487 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2488 | d_instantiate(dentry, inode); | |
2489 | dget(dentry); | |
2490 | return 0; | |
2491 | } | |
2492 | ||
2493 | static const char *shmem_follow_link(struct dentry *dentry, void **cookie) | |
2494 | { | |
2495 | struct page *page = NULL; | |
2496 | int error = shmem_getpage(d_inode(dentry), 0, &page, SGP_READ, NULL); | |
2497 | if (error) | |
2498 | return ERR_PTR(error); | |
2499 | unlock_page(page); | |
2500 | *cookie = page; | |
2501 | return kmap(page); | |
2502 | } | |
2503 | ||
2504 | static void shmem_put_link(struct inode *unused, void *cookie) | |
2505 | { | |
2506 | struct page *page = cookie; | |
2507 | kunmap(page); | |
2508 | mark_page_accessed(page); | |
2509 | page_cache_release(page); | |
2510 | } | |
2511 | ||
2512 | #ifdef CONFIG_TMPFS_XATTR | |
2513 | /* | |
2514 | * Superblocks without xattr inode operations may get some security.* xattr | |
2515 | * support from the LSM "for free". As soon as we have any other xattrs | |
2516 | * like ACLs, we also need to implement the security.* handlers at | |
2517 | * filesystem level, though. | |
2518 | */ | |
2519 | ||
2520 | /* | |
2521 | * Callback for security_inode_init_security() for acquiring xattrs. | |
2522 | */ | |
2523 | static int shmem_initxattrs(struct inode *inode, | |
2524 | const struct xattr *xattr_array, | |
2525 | void *fs_info) | |
2526 | { | |
2527 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2528 | const struct xattr *xattr; | |
2529 | struct simple_xattr *new_xattr; | |
2530 | size_t len; | |
2531 | ||
2532 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { | |
2533 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); | |
2534 | if (!new_xattr) | |
2535 | return -ENOMEM; | |
2536 | ||
2537 | len = strlen(xattr->name) + 1; | |
2538 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, | |
2539 | GFP_KERNEL); | |
2540 | if (!new_xattr->name) { | |
2541 | kfree(new_xattr); | |
2542 | return -ENOMEM; | |
2543 | } | |
2544 | ||
2545 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, | |
2546 | XATTR_SECURITY_PREFIX_LEN); | |
2547 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, | |
2548 | xattr->name, len); | |
2549 | ||
2550 | simple_xattr_list_add(&info->xattrs, new_xattr); | |
2551 | } | |
2552 | ||
2553 | return 0; | |
2554 | } | |
2555 | ||
2556 | static const struct xattr_handler *shmem_xattr_handlers[] = { | |
2557 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2558 | &posix_acl_access_xattr_handler, | |
2559 | &posix_acl_default_xattr_handler, | |
2560 | #endif | |
2561 | NULL | |
2562 | }; | |
2563 | ||
2564 | static int shmem_xattr_validate(const char *name) | |
2565 | { | |
2566 | struct { const char *prefix; size_t len; } arr[] = { | |
2567 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, | |
2568 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } | |
2569 | }; | |
2570 | int i; | |
2571 | ||
2572 | for (i = 0; i < ARRAY_SIZE(arr); i++) { | |
2573 | size_t preflen = arr[i].len; | |
2574 | if (strncmp(name, arr[i].prefix, preflen) == 0) { | |
2575 | if (!name[preflen]) | |
2576 | return -EINVAL; | |
2577 | return 0; | |
2578 | } | |
2579 | } | |
2580 | return -EOPNOTSUPP; | |
2581 | } | |
2582 | ||
2583 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, | |
2584 | void *buffer, size_t size) | |
2585 | { | |
2586 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2587 | int err; | |
2588 | ||
2589 | /* | |
2590 | * If this is a request for a synthetic attribute in the system.* | |
2591 | * namespace use the generic infrastructure to resolve a handler | |
2592 | * for it via sb->s_xattr. | |
2593 | */ | |
2594 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2595 | return generic_getxattr(dentry, name, buffer, size); | |
2596 | ||
2597 | err = shmem_xattr_validate(name); | |
2598 | if (err) | |
2599 | return err; | |
2600 | ||
2601 | return simple_xattr_get(&info->xattrs, name, buffer, size); | |
2602 | } | |
2603 | ||
2604 | static int shmem_setxattr(struct dentry *dentry, const char *name, | |
2605 | const void *value, size_t size, int flags) | |
2606 | { | |
2607 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2608 | int err; | |
2609 | ||
2610 | /* | |
2611 | * If this is a request for a synthetic attribute in the system.* | |
2612 | * namespace use the generic infrastructure to resolve a handler | |
2613 | * for it via sb->s_xattr. | |
2614 | */ | |
2615 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2616 | return generic_setxattr(dentry, name, value, size, flags); | |
2617 | ||
2618 | err = shmem_xattr_validate(name); | |
2619 | if (err) | |
2620 | return err; | |
2621 | ||
2622 | return simple_xattr_set(&info->xattrs, name, value, size, flags); | |
2623 | } | |
2624 | ||
2625 | static int shmem_removexattr(struct dentry *dentry, const char *name) | |
2626 | { | |
2627 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2628 | int err; | |
2629 | ||
2630 | /* | |
2631 | * If this is a request for a synthetic attribute in the system.* | |
2632 | * namespace use the generic infrastructure to resolve a handler | |
2633 | * for it via sb->s_xattr. | |
2634 | */ | |
2635 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) | |
2636 | return generic_removexattr(dentry, name); | |
2637 | ||
2638 | err = shmem_xattr_validate(name); | |
2639 | if (err) | |
2640 | return err; | |
2641 | ||
2642 | return simple_xattr_remove(&info->xattrs, name); | |
2643 | } | |
2644 | ||
2645 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) | |
2646 | { | |
2647 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2648 | return simple_xattr_list(&info->xattrs, buffer, size); | |
2649 | } | |
2650 | #endif /* CONFIG_TMPFS_XATTR */ | |
2651 | ||
2652 | static const struct inode_operations shmem_short_symlink_operations = { | |
2653 | .readlink = generic_readlink, | |
2654 | .follow_link = simple_follow_link, | |
2655 | #ifdef CONFIG_TMPFS_XATTR | |
2656 | .setxattr = shmem_setxattr, | |
2657 | .getxattr = shmem_getxattr, | |
2658 | .listxattr = shmem_listxattr, | |
2659 | .removexattr = shmem_removexattr, | |
2660 | #endif | |
2661 | }; | |
2662 | ||
2663 | static const struct inode_operations shmem_symlink_inode_operations = { | |
2664 | .readlink = generic_readlink, | |
2665 | .follow_link = shmem_follow_link, | |
2666 | .put_link = shmem_put_link, | |
2667 | #ifdef CONFIG_TMPFS_XATTR | |
2668 | .setxattr = shmem_setxattr, | |
2669 | .getxattr = shmem_getxattr, | |
2670 | .listxattr = shmem_listxattr, | |
2671 | .removexattr = shmem_removexattr, | |
2672 | #endif | |
2673 | }; | |
2674 | ||
2675 | static struct dentry *shmem_get_parent(struct dentry *child) | |
2676 | { | |
2677 | return ERR_PTR(-ESTALE); | |
2678 | } | |
2679 | ||
2680 | static int shmem_match(struct inode *ino, void *vfh) | |
2681 | { | |
2682 | __u32 *fh = vfh; | |
2683 | __u64 inum = fh[2]; | |
2684 | inum = (inum << 32) | fh[1]; | |
2685 | return ino->i_ino == inum && fh[0] == ino->i_generation; | |
2686 | } | |
2687 | ||
2688 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, | |
2689 | struct fid *fid, int fh_len, int fh_type) | |
2690 | { | |
2691 | struct inode *inode; | |
2692 | struct dentry *dentry = NULL; | |
2693 | u64 inum; | |
2694 | ||
2695 | if (fh_len < 3) | |
2696 | return NULL; | |
2697 | ||
2698 | inum = fid->raw[2]; | |
2699 | inum = (inum << 32) | fid->raw[1]; | |
2700 | ||
2701 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), | |
2702 | shmem_match, fid->raw); | |
2703 | if (inode) { | |
2704 | dentry = d_find_alias(inode); | |
2705 | iput(inode); | |
2706 | } | |
2707 | ||
2708 | return dentry; | |
2709 | } | |
2710 | ||
2711 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, | |
2712 | struct inode *parent) | |
2713 | { | |
2714 | if (*len < 3) { | |
2715 | *len = 3; | |
2716 | return FILEID_INVALID; | |
2717 | } | |
2718 | ||
2719 | if (inode_unhashed(inode)) { | |
2720 | /* Unfortunately insert_inode_hash is not idempotent, | |
2721 | * so as we hash inodes here rather than at creation | |
2722 | * time, we need a lock to ensure we only try | |
2723 | * to do it once | |
2724 | */ | |
2725 | static DEFINE_SPINLOCK(lock); | |
2726 | spin_lock(&lock); | |
2727 | if (inode_unhashed(inode)) | |
2728 | __insert_inode_hash(inode, | |
2729 | inode->i_ino + inode->i_generation); | |
2730 | spin_unlock(&lock); | |
2731 | } | |
2732 | ||
2733 | fh[0] = inode->i_generation; | |
2734 | fh[1] = inode->i_ino; | |
2735 | fh[2] = ((__u64)inode->i_ino) >> 32; | |
2736 | ||
2737 | *len = 3; | |
2738 | return 1; | |
2739 | } | |
2740 | ||
2741 | static const struct export_operations shmem_export_ops = { | |
2742 | .get_parent = shmem_get_parent, | |
2743 | .encode_fh = shmem_encode_fh, | |
2744 | .fh_to_dentry = shmem_fh_to_dentry, | |
2745 | }; | |
2746 | ||
2747 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, | |
2748 | bool remount) | |
2749 | { | |
2750 | char *this_char, *value, *rest; | |
2751 | struct mempolicy *mpol = NULL; | |
2752 | uid_t uid; | |
2753 | gid_t gid; | |
2754 | ||
2755 | while (options != NULL) { | |
2756 | this_char = options; | |
2757 | for (;;) { | |
2758 | /* | |
2759 | * NUL-terminate this option: unfortunately, | |
2760 | * mount options form a comma-separated list, | |
2761 | * but mpol's nodelist may also contain commas. | |
2762 | */ | |
2763 | options = strchr(options, ','); | |
2764 | if (options == NULL) | |
2765 | break; | |
2766 | options++; | |
2767 | if (!isdigit(*options)) { | |
2768 | options[-1] = '\0'; | |
2769 | break; | |
2770 | } | |
2771 | } | |
2772 | if (!*this_char) | |
2773 | continue; | |
2774 | if ((value = strchr(this_char,'=')) != NULL) { | |
2775 | *value++ = 0; | |
2776 | } else { | |
2777 | printk(KERN_ERR | |
2778 | "tmpfs: No value for mount option '%s'\n", | |
2779 | this_char); | |
2780 | goto error; | |
2781 | } | |
2782 | ||
2783 | if (!strcmp(this_char,"size")) { | |
2784 | unsigned long long size; | |
2785 | size = memparse(value,&rest); | |
2786 | if (*rest == '%') { | |
2787 | size <<= PAGE_SHIFT; | |
2788 | size *= totalram_pages; | |
2789 | do_div(size, 100); | |
2790 | rest++; | |
2791 | } | |
2792 | if (*rest) | |
2793 | goto bad_val; | |
2794 | sbinfo->max_blocks = | |
2795 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); | |
2796 | } else if (!strcmp(this_char,"nr_blocks")) { | |
2797 | sbinfo->max_blocks = memparse(value, &rest); | |
2798 | if (*rest) | |
2799 | goto bad_val; | |
2800 | } else if (!strcmp(this_char,"nr_inodes")) { | |
2801 | sbinfo->max_inodes = memparse(value, &rest); | |
2802 | if (*rest) | |
2803 | goto bad_val; | |
2804 | } else if (!strcmp(this_char,"mode")) { | |
2805 | if (remount) | |
2806 | continue; | |
2807 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; | |
2808 | if (*rest) | |
2809 | goto bad_val; | |
2810 | } else if (!strcmp(this_char,"uid")) { | |
2811 | if (remount) | |
2812 | continue; | |
2813 | uid = simple_strtoul(value, &rest, 0); | |
2814 | if (*rest) | |
2815 | goto bad_val; | |
2816 | sbinfo->uid = make_kuid(current_user_ns(), uid); | |
2817 | if (!uid_valid(sbinfo->uid)) | |
2818 | goto bad_val; | |
2819 | } else if (!strcmp(this_char,"gid")) { | |
2820 | if (remount) | |
2821 | continue; | |
2822 | gid = simple_strtoul(value, &rest, 0); | |
2823 | if (*rest) | |
2824 | goto bad_val; | |
2825 | sbinfo->gid = make_kgid(current_user_ns(), gid); | |
2826 | if (!gid_valid(sbinfo->gid)) | |
2827 | goto bad_val; | |
2828 | } else if (!strcmp(this_char,"mpol")) { | |
2829 | mpol_put(mpol); | |
2830 | mpol = NULL; | |
2831 | if (mpol_parse_str(value, &mpol)) | |
2832 | goto bad_val; | |
2833 | } else { | |
2834 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", | |
2835 | this_char); | |
2836 | goto error; | |
2837 | } | |
2838 | } | |
2839 | sbinfo->mpol = mpol; | |
2840 | return 0; | |
2841 | ||
2842 | bad_val: | |
2843 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", | |
2844 | value, this_char); | |
2845 | error: | |
2846 | mpol_put(mpol); | |
2847 | return 1; | |
2848 | ||
2849 | } | |
2850 | ||
2851 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) | |
2852 | { | |
2853 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2854 | struct shmem_sb_info config = *sbinfo; | |
2855 | unsigned long inodes; | |
2856 | int error = -EINVAL; | |
2857 | ||
2858 | config.mpol = NULL; | |
2859 | if (shmem_parse_options(data, &config, true)) | |
2860 | return error; | |
2861 | ||
2862 | spin_lock(&sbinfo->stat_lock); | |
2863 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; | |
2864 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) | |
2865 | goto out; | |
2866 | if (config.max_inodes < inodes) | |
2867 | goto out; | |
2868 | /* | |
2869 | * Those tests disallow limited->unlimited while any are in use; | |
2870 | * but we must separately disallow unlimited->limited, because | |
2871 | * in that case we have no record of how much is already in use. | |
2872 | */ | |
2873 | if (config.max_blocks && !sbinfo->max_blocks) | |
2874 | goto out; | |
2875 | if (config.max_inodes && !sbinfo->max_inodes) | |
2876 | goto out; | |
2877 | ||
2878 | error = 0; | |
2879 | sbinfo->max_blocks = config.max_blocks; | |
2880 | sbinfo->max_inodes = config.max_inodes; | |
2881 | sbinfo->free_inodes = config.max_inodes - inodes; | |
2882 | ||
2883 | /* | |
2884 | * Preserve previous mempolicy unless mpol remount option was specified. | |
2885 | */ | |
2886 | if (config.mpol) { | |
2887 | mpol_put(sbinfo->mpol); | |
2888 | sbinfo->mpol = config.mpol; /* transfers initial ref */ | |
2889 | } | |
2890 | out: | |
2891 | spin_unlock(&sbinfo->stat_lock); | |
2892 | return error; | |
2893 | } | |
2894 | ||
2895 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) | |
2896 | { | |
2897 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); | |
2898 | ||
2899 | if (sbinfo->max_blocks != shmem_default_max_blocks()) | |
2900 | seq_printf(seq, ",size=%luk", | |
2901 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); | |
2902 | if (sbinfo->max_inodes != shmem_default_max_inodes()) | |
2903 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); | |
2904 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) | |
2905 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); | |
2906 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) | |
2907 | seq_printf(seq, ",uid=%u", | |
2908 | from_kuid_munged(&init_user_ns, sbinfo->uid)); | |
2909 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) | |
2910 | seq_printf(seq, ",gid=%u", | |
2911 | from_kgid_munged(&init_user_ns, sbinfo->gid)); | |
2912 | shmem_show_mpol(seq, sbinfo->mpol); | |
2913 | return 0; | |
2914 | } | |
2915 | ||
2916 | #define MFD_NAME_PREFIX "memfd:" | |
2917 | #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1) | |
2918 | #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN) | |
2919 | ||
2920 | #define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING) | |
2921 | ||
2922 | SYSCALL_DEFINE2(memfd_create, | |
2923 | const char __user *, uname, | |
2924 | unsigned int, flags) | |
2925 | { | |
2926 | struct shmem_inode_info *info; | |
2927 | struct file *file; | |
2928 | int fd, error; | |
2929 | char *name; | |
2930 | long len; | |
2931 | ||
2932 | if (flags & ~(unsigned int)MFD_ALL_FLAGS) | |
2933 | return -EINVAL; | |
2934 | ||
2935 | /* length includes terminating zero */ | |
2936 | len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1); | |
2937 | if (len <= 0) | |
2938 | return -EFAULT; | |
2939 | if (len > MFD_NAME_MAX_LEN + 1) | |
2940 | return -EINVAL; | |
2941 | ||
2942 | name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY); | |
2943 | if (!name) | |
2944 | return -ENOMEM; | |
2945 | ||
2946 | strcpy(name, MFD_NAME_PREFIX); | |
2947 | if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) { | |
2948 | error = -EFAULT; | |
2949 | goto err_name; | |
2950 | } | |
2951 | ||
2952 | /* terminating-zero may have changed after strnlen_user() returned */ | |
2953 | if (name[len + MFD_NAME_PREFIX_LEN - 1]) { | |
2954 | error = -EFAULT; | |
2955 | goto err_name; | |
2956 | } | |
2957 | ||
2958 | fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0); | |
2959 | if (fd < 0) { | |
2960 | error = fd; | |
2961 | goto err_name; | |
2962 | } | |
2963 | ||
2964 | file = shmem_file_setup(name, 0, VM_NORESERVE); | |
2965 | if (IS_ERR(file)) { | |
2966 | error = PTR_ERR(file); | |
2967 | goto err_fd; | |
2968 | } | |
2969 | info = SHMEM_I(file_inode(file)); | |
2970 | file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; | |
2971 | file->f_flags |= O_RDWR | O_LARGEFILE; | |
2972 | if (flags & MFD_ALLOW_SEALING) | |
2973 | info->seals &= ~F_SEAL_SEAL; | |
2974 | ||
2975 | fd_install(fd, file); | |
2976 | kfree(name); | |
2977 | return fd; | |
2978 | ||
2979 | err_fd: | |
2980 | put_unused_fd(fd); | |
2981 | err_name: | |
2982 | kfree(name); | |
2983 | return error; | |
2984 | } | |
2985 | ||
2986 | #endif /* CONFIG_TMPFS */ | |
2987 | ||
2988 | static void shmem_put_super(struct super_block *sb) | |
2989 | { | |
2990 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2991 | ||
2992 | percpu_counter_destroy(&sbinfo->used_blocks); | |
2993 | mpol_put(sbinfo->mpol); | |
2994 | kfree(sbinfo); | |
2995 | sb->s_fs_info = NULL; | |
2996 | } | |
2997 | ||
2998 | int shmem_fill_super(struct super_block *sb, void *data, int silent) | |
2999 | { | |
3000 | struct inode *inode; | |
3001 | struct shmem_sb_info *sbinfo; | |
3002 | int err = -ENOMEM; | |
3003 | ||
3004 | /* Round up to L1_CACHE_BYTES to resist false sharing */ | |
3005 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), | |
3006 | L1_CACHE_BYTES), GFP_KERNEL); | |
3007 | if (!sbinfo) | |
3008 | return -ENOMEM; | |
3009 | ||
3010 | sbinfo->mode = S_IRWXUGO | S_ISVTX; | |
3011 | sbinfo->uid = current_fsuid(); | |
3012 | sbinfo->gid = current_fsgid(); | |
3013 | sb->s_fs_info = sbinfo; | |
3014 | ||
3015 | #ifdef CONFIG_TMPFS | |
3016 | /* | |
3017 | * Per default we only allow half of the physical ram per | |
3018 | * tmpfs instance, limiting inodes to one per page of lowmem; | |
3019 | * but the internal instance is left unlimited. | |
3020 | */ | |
3021 | if (!(sb->s_flags & MS_KERNMOUNT)) { | |
3022 | sbinfo->max_blocks = shmem_default_max_blocks(); | |
3023 | sbinfo->max_inodes = shmem_default_max_inodes(); | |
3024 | if (shmem_parse_options(data, sbinfo, false)) { | |
3025 | err = -EINVAL; | |
3026 | goto failed; | |
3027 | } | |
3028 | } else { | |
3029 | sb->s_flags |= MS_NOUSER; | |
3030 | } | |
3031 | sb->s_export_op = &shmem_export_ops; | |
3032 | sb->s_flags |= MS_NOSEC; | |
3033 | #else | |
3034 | sb->s_flags |= MS_NOUSER; | |
3035 | #endif | |
3036 | ||
3037 | spin_lock_init(&sbinfo->stat_lock); | |
3038 | if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL)) | |
3039 | goto failed; | |
3040 | sbinfo->free_inodes = sbinfo->max_inodes; | |
3041 | ||
3042 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
3043 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
3044 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
3045 | sb->s_magic = TMPFS_MAGIC; | |
3046 | sb->s_op = &shmem_ops; | |
3047 | sb->s_time_gran = 1; | |
3048 | #ifdef CONFIG_TMPFS_XATTR | |
3049 | sb->s_xattr = shmem_xattr_handlers; | |
3050 | #endif | |
3051 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3052 | sb->s_flags |= MS_POSIXACL; | |
3053 | #endif | |
3054 | ||
3055 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); | |
3056 | if (!inode) | |
3057 | goto failed; | |
3058 | inode->i_uid = sbinfo->uid; | |
3059 | inode->i_gid = sbinfo->gid; | |
3060 | sb->s_root = d_make_root(inode); | |
3061 | if (!sb->s_root) | |
3062 | goto failed; | |
3063 | return 0; | |
3064 | ||
3065 | failed: | |
3066 | shmem_put_super(sb); | |
3067 | return err; | |
3068 | } | |
3069 | ||
3070 | static struct kmem_cache *shmem_inode_cachep; | |
3071 | ||
3072 | static struct inode *shmem_alloc_inode(struct super_block *sb) | |
3073 | { | |
3074 | struct shmem_inode_info *info; | |
3075 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); | |
3076 | if (!info) | |
3077 | return NULL; | |
3078 | return &info->vfs_inode; | |
3079 | } | |
3080 | ||
3081 | static void shmem_destroy_callback(struct rcu_head *head) | |
3082 | { | |
3083 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
3084 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); | |
3085 | } | |
3086 | ||
3087 | static void shmem_destroy_inode(struct inode *inode) | |
3088 | { | |
3089 | if (S_ISREG(inode->i_mode)) | |
3090 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); | |
3091 | call_rcu(&inode->i_rcu, shmem_destroy_callback); | |
3092 | } | |
3093 | ||
3094 | static void shmem_init_inode(void *foo) | |
3095 | { | |
3096 | struct shmem_inode_info *info = foo; | |
3097 | inode_init_once(&info->vfs_inode); | |
3098 | } | |
3099 | ||
3100 | static int shmem_init_inodecache(void) | |
3101 | { | |
3102 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", | |
3103 | sizeof(struct shmem_inode_info), | |
3104 | 0, SLAB_PANIC, shmem_init_inode); | |
3105 | return 0; | |
3106 | } | |
3107 | ||
3108 | static void shmem_destroy_inodecache(void) | |
3109 | { | |
3110 | kmem_cache_destroy(shmem_inode_cachep); | |
3111 | } | |
3112 | ||
3113 | static const struct address_space_operations shmem_aops = { | |
3114 | .writepage = shmem_writepage, | |
3115 | .set_page_dirty = __set_page_dirty_no_writeback, | |
3116 | #ifdef CONFIG_TMPFS | |
3117 | .write_begin = shmem_write_begin, | |
3118 | .write_end = shmem_write_end, | |
3119 | #endif | |
3120 | #ifdef CONFIG_MIGRATION | |
3121 | .migratepage = migrate_page, | |
3122 | #endif | |
3123 | .error_remove_page = generic_error_remove_page, | |
3124 | }; | |
3125 | ||
3126 | static const struct file_operations shmem_file_operations = { | |
3127 | .mmap = shmem_mmap, | |
3128 | #ifdef CONFIG_TMPFS | |
3129 | .llseek = shmem_file_llseek, | |
3130 | .read_iter = shmem_file_read_iter, | |
3131 | .write_iter = generic_file_write_iter, | |
3132 | .fsync = noop_fsync, | |
3133 | .splice_read = shmem_file_splice_read, | |
3134 | .splice_write = iter_file_splice_write, | |
3135 | .fallocate = shmem_fallocate, | |
3136 | #endif | |
3137 | }; | |
3138 | ||
3139 | static const struct inode_operations shmem_inode_operations = { | |
3140 | .getattr = shmem_getattr, | |
3141 | .setattr = shmem_setattr, | |
3142 | #ifdef CONFIG_TMPFS_XATTR | |
3143 | .setxattr = shmem_setxattr, | |
3144 | .getxattr = shmem_getxattr, | |
3145 | .listxattr = shmem_listxattr, | |
3146 | .removexattr = shmem_removexattr, | |
3147 | .set_acl = simple_set_acl, | |
3148 | #endif | |
3149 | }; | |
3150 | ||
3151 | static const struct inode_operations shmem_dir_inode_operations = { | |
3152 | #ifdef CONFIG_TMPFS | |
3153 | .create = shmem_create, | |
3154 | .lookup = simple_lookup, | |
3155 | .link = shmem_link, | |
3156 | .unlink = shmem_unlink, | |
3157 | .symlink = shmem_symlink, | |
3158 | .mkdir = shmem_mkdir, | |
3159 | .rmdir = shmem_rmdir, | |
3160 | .mknod = shmem_mknod, | |
3161 | .rename2 = shmem_rename2, | |
3162 | .tmpfile = shmem_tmpfile, | |
3163 | #endif | |
3164 | #ifdef CONFIG_TMPFS_XATTR | |
3165 | .setxattr = shmem_setxattr, | |
3166 | .getxattr = shmem_getxattr, | |
3167 | .listxattr = shmem_listxattr, | |
3168 | .removexattr = shmem_removexattr, | |
3169 | #endif | |
3170 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3171 | .setattr = shmem_setattr, | |
3172 | .set_acl = simple_set_acl, | |
3173 | #endif | |
3174 | }; | |
3175 | ||
3176 | static const struct inode_operations shmem_special_inode_operations = { | |
3177 | #ifdef CONFIG_TMPFS_XATTR | |
3178 | .setxattr = shmem_setxattr, | |
3179 | .getxattr = shmem_getxattr, | |
3180 | .listxattr = shmem_listxattr, | |
3181 | .removexattr = shmem_removexattr, | |
3182 | #endif | |
3183 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3184 | .setattr = shmem_setattr, | |
3185 | .set_acl = simple_set_acl, | |
3186 | #endif | |
3187 | }; | |
3188 | ||
3189 | static const struct super_operations shmem_ops = { | |
3190 | .alloc_inode = shmem_alloc_inode, | |
3191 | .destroy_inode = shmem_destroy_inode, | |
3192 | #ifdef CONFIG_TMPFS | |
3193 | .statfs = shmem_statfs, | |
3194 | .remount_fs = shmem_remount_fs, | |
3195 | .show_options = shmem_show_options, | |
3196 | #endif | |
3197 | .evict_inode = shmem_evict_inode, | |
3198 | .drop_inode = generic_delete_inode, | |
3199 | .put_super = shmem_put_super, | |
3200 | }; | |
3201 | ||
3202 | static const struct vm_operations_struct shmem_vm_ops = { | |
3203 | .fault = shmem_fault, | |
3204 | .map_pages = filemap_map_pages, | |
3205 | #ifdef CONFIG_NUMA | |
3206 | .set_policy = shmem_set_policy, | |
3207 | .get_policy = shmem_get_policy, | |
3208 | #endif | |
3209 | }; | |
3210 | ||
3211 | static struct dentry *shmem_mount(struct file_system_type *fs_type, | |
3212 | int flags, const char *dev_name, void *data) | |
3213 | { | |
3214 | return mount_nodev(fs_type, flags, data, shmem_fill_super); | |
3215 | } | |
3216 | ||
3217 | static struct file_system_type shmem_fs_type = { | |
3218 | .owner = THIS_MODULE, | |
3219 | .name = "tmpfs", | |
3220 | .mount = shmem_mount, | |
3221 | .kill_sb = kill_litter_super, | |
3222 | .fs_flags = FS_USERNS_MOUNT, | |
3223 | }; | |
3224 | ||
3225 | int __init shmem_init(void) | |
3226 | { | |
3227 | int error; | |
3228 | ||
3229 | /* If rootfs called this, don't re-init */ | |
3230 | if (shmem_inode_cachep) | |
3231 | return 0; | |
3232 | ||
3233 | error = shmem_init_inodecache(); | |
3234 | if (error) | |
3235 | goto out3; | |
3236 | ||
3237 | error = register_filesystem(&shmem_fs_type); | |
3238 | if (error) { | |
3239 | printk(KERN_ERR "Could not register tmpfs\n"); | |
3240 | goto out2; | |
3241 | } | |
3242 | ||
3243 | shm_mnt = kern_mount(&shmem_fs_type); | |
3244 | if (IS_ERR(shm_mnt)) { | |
3245 | error = PTR_ERR(shm_mnt); | |
3246 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); | |
3247 | goto out1; | |
3248 | } | |
3249 | return 0; | |
3250 | ||
3251 | out1: | |
3252 | unregister_filesystem(&shmem_fs_type); | |
3253 | out2: | |
3254 | shmem_destroy_inodecache(); | |
3255 | out3: | |
3256 | shm_mnt = ERR_PTR(error); | |
3257 | return error; | |
3258 | } | |
3259 | ||
3260 | #else /* !CONFIG_SHMEM */ | |
3261 | ||
3262 | /* | |
3263 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code | |
3264 | * | |
3265 | * This is intended for small system where the benefits of the full | |
3266 | * shmem code (swap-backed and resource-limited) are outweighed by | |
3267 | * their complexity. On systems without swap this code should be | |
3268 | * effectively equivalent, but much lighter weight. | |
3269 | */ | |
3270 | ||
3271 | static struct file_system_type shmem_fs_type = { | |
3272 | .name = "tmpfs", | |
3273 | .mount = ramfs_mount, | |
3274 | .kill_sb = kill_litter_super, | |
3275 | .fs_flags = FS_USERNS_MOUNT, | |
3276 | }; | |
3277 | ||
3278 | int __init shmem_init(void) | |
3279 | { | |
3280 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); | |
3281 | ||
3282 | shm_mnt = kern_mount(&shmem_fs_type); | |
3283 | BUG_ON(IS_ERR(shm_mnt)); | |
3284 | ||
3285 | return 0; | |
3286 | } | |
3287 | ||
3288 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
3289 | { | |
3290 | return 0; | |
3291 | } | |
3292 | ||
3293 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
3294 | { | |
3295 | return 0; | |
3296 | } | |
3297 | ||
3298 | void shmem_unlock_mapping(struct address_space *mapping) | |
3299 | { | |
3300 | } | |
3301 | ||
3302 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
3303 | { | |
3304 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); | |
3305 | } | |
3306 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
3307 | ||
3308 | #define shmem_vm_ops generic_file_vm_ops | |
3309 | #define shmem_file_operations ramfs_file_operations | |
3310 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) | |
3311 | #define shmem_acct_size(flags, size) 0 | |
3312 | #define shmem_unacct_size(flags, size) do {} while (0) | |
3313 | ||
3314 | #endif /* CONFIG_SHMEM */ | |
3315 | ||
3316 | /* common code */ | |
3317 | ||
3318 | static struct dentry_operations anon_ops = { | |
3319 | .d_dname = simple_dname | |
3320 | }; | |
3321 | ||
3322 | static struct file *__shmem_file_setup(const char *name, loff_t size, | |
3323 | unsigned long flags, unsigned int i_flags) | |
3324 | { | |
3325 | struct file *res; | |
3326 | struct inode *inode; | |
3327 | struct path path; | |
3328 | struct super_block *sb; | |
3329 | struct qstr this; | |
3330 | ||
3331 | if (IS_ERR(shm_mnt)) | |
3332 | return ERR_CAST(shm_mnt); | |
3333 | ||
3334 | if (size < 0 || size > MAX_LFS_FILESIZE) | |
3335 | return ERR_PTR(-EINVAL); | |
3336 | ||
3337 | if (shmem_acct_size(flags, size)) | |
3338 | return ERR_PTR(-ENOMEM); | |
3339 | ||
3340 | res = ERR_PTR(-ENOMEM); | |
3341 | this.name = name; | |
3342 | this.len = strlen(name); | |
3343 | this.hash = 0; /* will go */ | |
3344 | sb = shm_mnt->mnt_sb; | |
3345 | path.mnt = mntget(shm_mnt); | |
3346 | path.dentry = d_alloc_pseudo(sb, &this); | |
3347 | if (!path.dentry) | |
3348 | goto put_memory; | |
3349 | d_set_d_op(path.dentry, &anon_ops); | |
3350 | ||
3351 | res = ERR_PTR(-ENOSPC); | |
3352 | inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); | |
3353 | if (!inode) | |
3354 | goto put_memory; | |
3355 | ||
3356 | inode->i_flags |= i_flags; | |
3357 | d_instantiate(path.dentry, inode); | |
3358 | inode->i_size = size; | |
3359 | clear_nlink(inode); /* It is unlinked */ | |
3360 | res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); | |
3361 | if (IS_ERR(res)) | |
3362 | goto put_path; | |
3363 | ||
3364 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, | |
3365 | &shmem_file_operations); | |
3366 | if (IS_ERR(res)) | |
3367 | goto put_path; | |
3368 | ||
3369 | return res; | |
3370 | ||
3371 | put_memory: | |
3372 | shmem_unacct_size(flags, size); | |
3373 | put_path: | |
3374 | path_put(&path); | |
3375 | return res; | |
3376 | } | |
3377 | ||
3378 | /** | |
3379 | * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be | |
3380 | * kernel internal. There will be NO LSM permission checks against the | |
3381 | * underlying inode. So users of this interface must do LSM checks at a | |
3382 | * higher layer. The users are the big_key and shm implementations. LSM | |
3383 | * checks are provided at the key or shm level rather than the inode. | |
3384 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
3385 | * @size: size to be set for the file | |
3386 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
3387 | */ | |
3388 | struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags) | |
3389 | { | |
3390 | return __shmem_file_setup(name, size, flags, S_PRIVATE); | |
3391 | } | |
3392 | ||
3393 | /** | |
3394 | * shmem_file_setup - get an unlinked file living in tmpfs | |
3395 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
3396 | * @size: size to be set for the file | |
3397 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
3398 | */ | |
3399 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) | |
3400 | { | |
3401 | return __shmem_file_setup(name, size, flags, 0); | |
3402 | } | |
3403 | EXPORT_SYMBOL_GPL(shmem_file_setup); | |
3404 | ||
3405 | /** | |
3406 | * shmem_zero_setup - setup a shared anonymous mapping | |
3407 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff | |
3408 | */ | |
3409 | int shmem_zero_setup(struct vm_area_struct *vma) | |
3410 | { | |
3411 | struct file *file; | |
3412 | loff_t size = vma->vm_end - vma->vm_start; | |
3413 | ||
3414 | /* | |
3415 | * Cloning a new file under mmap_sem leads to a lock ordering conflict | |
3416 | * between XFS directory reading and selinux: since this file is only | |
3417 | * accessible to the user through its mapping, use S_PRIVATE flag to | |
3418 | * bypass file security, in the same way as shmem_kernel_file_setup(). | |
3419 | */ | |
3420 | file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE); | |
3421 | if (IS_ERR(file)) | |
3422 | return PTR_ERR(file); | |
3423 | ||
3424 | if (vma->vm_file) | |
3425 | fput(vma->vm_file); | |
3426 | vma->vm_file = file; | |
3427 | vma->vm_ops = &shmem_vm_ops; | |
3428 | return 0; | |
3429 | } | |
3430 | ||
3431 | /** | |
3432 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. | |
3433 | * @mapping: the page's address_space | |
3434 | * @index: the page index | |
3435 | * @gfp: the page allocator flags to use if allocating | |
3436 | * | |
3437 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", | |
3438 | * with any new page allocations done using the specified allocation flags. | |
3439 | * But read_cache_page_gfp() uses the ->readpage() method: which does not | |
3440 | * suit tmpfs, since it may have pages in swapcache, and needs to find those | |
3441 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. | |
3442 | * | |
3443 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in | |
3444 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. | |
3445 | */ | |
3446 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, | |
3447 | pgoff_t index, gfp_t gfp) | |
3448 | { | |
3449 | #ifdef CONFIG_SHMEM | |
3450 | struct inode *inode = mapping->host; | |
3451 | struct page *page; | |
3452 | int error; | |
3453 | ||
3454 | BUG_ON(mapping->a_ops != &shmem_aops); | |
3455 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); | |
3456 | if (error) | |
3457 | page = ERR_PTR(error); | |
3458 | else | |
3459 | unlock_page(page); | |
3460 | return page; | |
3461 | #else | |
3462 | /* | |
3463 | * The tiny !SHMEM case uses ramfs without swap | |
3464 | */ | |
3465 | return read_cache_page_gfp(mapping, index, gfp); | |
3466 | #endif | |
3467 | } | |
3468 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |