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1 | /* | |
2 | * Resizable virtual memory filesystem for Linux. | |
3 | * | |
4 | * Copyright (C) 2000 Linus Torvalds. | |
5 | * 2000 Transmeta Corp. | |
6 | * 2000-2001 Christoph Rohland | |
7 | * 2000-2001 SAP AG | |
8 | * 2002 Red Hat Inc. | |
9 | * Copyright (C) 2002-2011 Hugh Dickins. | |
10 | * Copyright (C) 2011 Google Inc. | |
11 | * Copyright (C) 2002-2005 VERITAS Software Corporation. | |
12 | * Copyright (C) 2004 Andi Kleen, SuSE Labs | |
13 | * | |
14 | * Extended attribute support for tmpfs: | |
15 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> | |
16 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> | |
17 | * | |
18 | * tiny-shmem: | |
19 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> | |
20 | * | |
21 | * This file is released under the GPL. | |
22 | */ | |
23 | ||
24 | #include <linux/fs.h> | |
25 | #include <linux/init.h> | |
26 | #include <linux/vfs.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/ramfs.h> | |
29 | #include <linux/pagemap.h> | |
30 | #include <linux/file.h> | |
31 | #include <linux/mm.h> | |
32 | #include <linux/export.h> | |
33 | #include <linux/swap.h> | |
34 | #include <linux/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 | #include "internal.h" | |
77 | ||
78 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) | |
79 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) | |
80 | ||
81 | /* Pretend that each entry is of this size in directory's i_size */ | |
82 | #define BOGO_DIRENT_SIZE 20 | |
83 | ||
84 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ | |
85 | #define SHORT_SYMLINK_LEN 128 | |
86 | ||
87 | /* | |
88 | * shmem_fallocate communicates with shmem_fault or shmem_writepage via | |
89 | * inode->i_private (with i_mutex making sure that it has only one user at | |
90 | * a time): we would prefer not to enlarge the shmem inode just for that. | |
91 | */ | |
92 | struct shmem_falloc { | |
93 | wait_queue_head_t *waitq; /* faults into hole wait for punch to end */ | |
94 | pgoff_t start; /* start of range currently being fallocated */ | |
95 | pgoff_t next; /* the next page offset to be fallocated */ | |
96 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ | |
97 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ | |
98 | }; | |
99 | ||
100 | /* Flag allocation requirements to shmem_getpage */ | |
101 | enum sgp_type { | |
102 | SGP_READ, /* don't exceed i_size, don't allocate page */ | |
103 | SGP_CACHE, /* don't exceed i_size, may allocate page */ | |
104 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ | |
105 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ | |
106 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ | |
107 | }; | |
108 | ||
109 | #ifdef CONFIG_TMPFS | |
110 | static unsigned long shmem_default_max_blocks(void) | |
111 | { | |
112 | return totalram_pages / 2; | |
113 | } | |
114 | ||
115 | static unsigned long shmem_default_max_inodes(void) | |
116 | { | |
117 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); | |
118 | } | |
119 | #endif | |
120 | ||
121 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); | |
122 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
123 | struct shmem_inode_info *info, pgoff_t index); | |
124 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
125 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); | |
126 | ||
127 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, | |
128 | struct page **pagep, enum sgp_type sgp, int *fault_type) | |
129 | { | |
130 | return shmem_getpage_gfp(inode, index, pagep, sgp, | |
131 | mapping_gfp_mask(inode->i_mapping), fault_type); | |
132 | } | |
133 | ||
134 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) | |
135 | { | |
136 | return sb->s_fs_info; | |
137 | } | |
138 | ||
139 | /* | |
140 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, | |
141 | * for shared memory and for shared anonymous (/dev/zero) mappings | |
142 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), | |
143 | * consistent with the pre-accounting of private mappings ... | |
144 | */ | |
145 | static inline int shmem_acct_size(unsigned long flags, loff_t size) | |
146 | { | |
147 | return (flags & VM_NORESERVE) ? | |
148 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); | |
149 | } | |
150 | ||
151 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) | |
152 | { | |
153 | if (!(flags & VM_NORESERVE)) | |
154 | vm_unacct_memory(VM_ACCT(size)); | |
155 | } | |
156 | ||
157 | static inline int shmem_reacct_size(unsigned long flags, | |
158 | loff_t oldsize, loff_t newsize) | |
159 | { | |
160 | if (!(flags & VM_NORESERVE)) { | |
161 | if (VM_ACCT(newsize) > VM_ACCT(oldsize)) | |
162 | return security_vm_enough_memory_mm(current->mm, | |
163 | VM_ACCT(newsize) - VM_ACCT(oldsize)); | |
164 | else if (VM_ACCT(newsize) < VM_ACCT(oldsize)) | |
165 | vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize)); | |
166 | } | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* | |
171 | * ... whereas tmpfs objects are accounted incrementally as | |
172 | * pages are allocated, in order to allow huge sparse files. | |
173 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, | |
174 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. | |
175 | */ | |
176 | static inline int shmem_acct_block(unsigned long flags) | |
177 | { | |
178 | return (flags & VM_NORESERVE) ? | |
179 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; | |
180 | } | |
181 | ||
182 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) | |
183 | { | |
184 | if (flags & VM_NORESERVE) | |
185 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); | |
186 | } | |
187 | ||
188 | static const struct super_operations shmem_ops; | |
189 | static const struct address_space_operations shmem_aops; | |
190 | static const struct file_operations shmem_file_operations; | |
191 | static const struct inode_operations shmem_inode_operations; | |
192 | static const struct inode_operations shmem_dir_inode_operations; | |
193 | static const struct inode_operations shmem_special_inode_operations; | |
194 | static const struct vm_operations_struct shmem_vm_ops; | |
195 | ||
196 | static LIST_HEAD(shmem_swaplist); | |
197 | static DEFINE_MUTEX(shmem_swaplist_mutex); | |
198 | ||
199 | static int shmem_reserve_inode(struct super_block *sb) | |
200 | { | |
201 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
202 | if (sbinfo->max_inodes) { | |
203 | spin_lock(&sbinfo->stat_lock); | |
204 | if (!sbinfo->free_inodes) { | |
205 | spin_unlock(&sbinfo->stat_lock); | |
206 | return -ENOSPC; | |
207 | } | |
208 | sbinfo->free_inodes--; | |
209 | spin_unlock(&sbinfo->stat_lock); | |
210 | } | |
211 | return 0; | |
212 | } | |
213 | ||
214 | static void shmem_free_inode(struct super_block *sb) | |
215 | { | |
216 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
217 | if (sbinfo->max_inodes) { | |
218 | spin_lock(&sbinfo->stat_lock); | |
219 | sbinfo->free_inodes++; | |
220 | spin_unlock(&sbinfo->stat_lock); | |
221 | } | |
222 | } | |
223 | ||
224 | /** | |
225 | * shmem_recalc_inode - recalculate the block usage of an inode | |
226 | * @inode: inode to recalc | |
227 | * | |
228 | * We have to calculate the free blocks since the mm can drop | |
229 | * undirtied hole pages behind our back. | |
230 | * | |
231 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped | |
232 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) | |
233 | * | |
234 | * It has to be called with the spinlock held. | |
235 | */ | |
236 | static void shmem_recalc_inode(struct inode *inode) | |
237 | { | |
238 | struct shmem_inode_info *info = SHMEM_I(inode); | |
239 | long freed; | |
240 | ||
241 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; | |
242 | if (freed > 0) { | |
243 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
244 | if (sbinfo->max_blocks) | |
245 | percpu_counter_add(&sbinfo->used_blocks, -freed); | |
246 | info->alloced -= freed; | |
247 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; | |
248 | shmem_unacct_blocks(info->flags, freed); | |
249 | } | |
250 | } | |
251 | ||
252 | /* | |
253 | * Replace item expected in radix tree by a new item, while holding tree lock. | |
254 | */ | |
255 | static int shmem_radix_tree_replace(struct address_space *mapping, | |
256 | pgoff_t index, void *expected, void *replacement) | |
257 | { | |
258 | void **pslot; | |
259 | void *item; | |
260 | ||
261 | VM_BUG_ON(!expected); | |
262 | VM_BUG_ON(!replacement); | |
263 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); | |
264 | if (!pslot) | |
265 | return -ENOENT; | |
266 | item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock); | |
267 | if (item != expected) | |
268 | return -ENOENT; | |
269 | radix_tree_replace_slot(pslot, replacement); | |
270 | return 0; | |
271 | } | |
272 | ||
273 | /* | |
274 | * Sometimes, before we decide whether to proceed or to fail, we must check | |
275 | * that an entry was not already brought back from swap by a racing thread. | |
276 | * | |
277 | * Checking page is not enough: by the time a SwapCache page is locked, it | |
278 | * might be reused, and again be SwapCache, using the same swap as before. | |
279 | */ | |
280 | static bool shmem_confirm_swap(struct address_space *mapping, | |
281 | pgoff_t index, swp_entry_t swap) | |
282 | { | |
283 | void *item; | |
284 | ||
285 | rcu_read_lock(); | |
286 | item = radix_tree_lookup(&mapping->page_tree, index); | |
287 | rcu_read_unlock(); | |
288 | return item == swp_to_radix_entry(swap); | |
289 | } | |
290 | ||
291 | /* | |
292 | * Like add_to_page_cache_locked, but error if expected item has gone. | |
293 | */ | |
294 | static int shmem_add_to_page_cache(struct page *page, | |
295 | struct address_space *mapping, | |
296 | pgoff_t index, void *expected) | |
297 | { | |
298 | int error; | |
299 | ||
300 | VM_BUG_ON_PAGE(!PageLocked(page), page); | |
301 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); | |
302 | ||
303 | page_cache_get(page); | |
304 | page->mapping = mapping; | |
305 | page->index = index; | |
306 | ||
307 | spin_lock_irq(&mapping->tree_lock); | |
308 | if (!expected) | |
309 | error = radix_tree_insert(&mapping->page_tree, index, page); | |
310 | else | |
311 | error = shmem_radix_tree_replace(mapping, index, expected, | |
312 | page); | |
313 | if (!error) { | |
314 | mapping->nrpages++; | |
315 | __inc_zone_page_state(page, NR_FILE_PAGES); | |
316 | __inc_zone_page_state(page, NR_SHMEM); | |
317 | spin_unlock_irq(&mapping->tree_lock); | |
318 | } else { | |
319 | page->mapping = NULL; | |
320 | spin_unlock_irq(&mapping->tree_lock); | |
321 | page_cache_release(page); | |
322 | } | |
323 | return error; | |
324 | } | |
325 | ||
326 | /* | |
327 | * Like delete_from_page_cache, but substitutes swap for page. | |
328 | */ | |
329 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) | |
330 | { | |
331 | struct address_space *mapping = page->mapping; | |
332 | int error; | |
333 | ||
334 | spin_lock_irq(&mapping->tree_lock); | |
335 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); | |
336 | page->mapping = NULL; | |
337 | mapping->nrpages--; | |
338 | __dec_zone_page_state(page, NR_FILE_PAGES); | |
339 | __dec_zone_page_state(page, NR_SHMEM); | |
340 | spin_unlock_irq(&mapping->tree_lock); | |
341 | page_cache_release(page); | |
342 | BUG_ON(error); | |
343 | } | |
344 | ||
345 | /* | |
346 | * Remove swap entry from radix tree, free the swap and its page cache. | |
347 | */ | |
348 | static int shmem_free_swap(struct address_space *mapping, | |
349 | pgoff_t index, void *radswap) | |
350 | { | |
351 | void *old; | |
352 | ||
353 | spin_lock_irq(&mapping->tree_lock); | |
354 | old = radix_tree_delete_item(&mapping->page_tree, index, radswap); | |
355 | spin_unlock_irq(&mapping->tree_lock); | |
356 | if (old != radswap) | |
357 | return -ENOENT; | |
358 | free_swap_and_cache(radix_to_swp_entry(radswap)); | |
359 | return 0; | |
360 | } | |
361 | ||
362 | /* | |
363 | * Determine (in bytes) how many of the shmem object's pages mapped by the | |
364 | * given offsets are swapped out. | |
365 | * | |
366 | * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU, | |
367 | * as long as the inode doesn't go away and racy results are not a problem. | |
368 | */ | |
369 | unsigned long shmem_partial_swap_usage(struct address_space *mapping, | |
370 | pgoff_t start, pgoff_t end) | |
371 | { | |
372 | struct radix_tree_iter iter; | |
373 | void **slot; | |
374 | struct page *page; | |
375 | unsigned long swapped = 0; | |
376 | ||
377 | rcu_read_lock(); | |
378 | ||
379 | restart: | |
380 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
381 | if (iter.index >= end) | |
382 | break; | |
383 | ||
384 | page = radix_tree_deref_slot(slot); | |
385 | ||
386 | /* | |
387 | * This should only be possible to happen at index 0, so we | |
388 | * don't need to reset the counter, nor do we risk infinite | |
389 | * restarts. | |
390 | */ | |
391 | if (radix_tree_deref_retry(page)) | |
392 | goto restart; | |
393 | ||
394 | if (radix_tree_exceptional_entry(page)) | |
395 | swapped++; | |
396 | ||
397 | if (need_resched()) { | |
398 | cond_resched_rcu(); | |
399 | start = iter.index + 1; | |
400 | goto restart; | |
401 | } | |
402 | } | |
403 | ||
404 | rcu_read_unlock(); | |
405 | ||
406 | return swapped << PAGE_SHIFT; | |
407 | } | |
408 | ||
409 | /* | |
410 | * Determine (in bytes) how many of the shmem object's pages mapped by the | |
411 | * given vma is swapped out. | |
412 | * | |
413 | * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU, | |
414 | * as long as the inode doesn't go away and racy results are not a problem. | |
415 | */ | |
416 | unsigned long shmem_swap_usage(struct vm_area_struct *vma) | |
417 | { | |
418 | struct inode *inode = file_inode(vma->vm_file); | |
419 | struct shmem_inode_info *info = SHMEM_I(inode); | |
420 | struct address_space *mapping = inode->i_mapping; | |
421 | unsigned long swapped; | |
422 | ||
423 | /* Be careful as we don't hold info->lock */ | |
424 | swapped = READ_ONCE(info->swapped); | |
425 | ||
426 | /* | |
427 | * The easier cases are when the shmem object has nothing in swap, or | |
428 | * the vma maps it whole. Then we can simply use the stats that we | |
429 | * already track. | |
430 | */ | |
431 | if (!swapped) | |
432 | return 0; | |
433 | ||
434 | if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size) | |
435 | return swapped << PAGE_SHIFT; | |
436 | ||
437 | /* Here comes the more involved part */ | |
438 | return shmem_partial_swap_usage(mapping, | |
439 | linear_page_index(vma, vma->vm_start), | |
440 | linear_page_index(vma, vma->vm_end)); | |
441 | } | |
442 | ||
443 | /* | |
444 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. | |
445 | */ | |
446 | void shmem_unlock_mapping(struct address_space *mapping) | |
447 | { | |
448 | struct pagevec pvec; | |
449 | pgoff_t indices[PAGEVEC_SIZE]; | |
450 | pgoff_t index = 0; | |
451 | ||
452 | pagevec_init(&pvec, 0); | |
453 | /* | |
454 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. | |
455 | */ | |
456 | while (!mapping_unevictable(mapping)) { | |
457 | /* | |
458 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it | |
459 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. | |
460 | */ | |
461 | pvec.nr = find_get_entries(mapping, index, | |
462 | PAGEVEC_SIZE, pvec.pages, indices); | |
463 | if (!pvec.nr) | |
464 | break; | |
465 | index = indices[pvec.nr - 1] + 1; | |
466 | pagevec_remove_exceptionals(&pvec); | |
467 | check_move_unevictable_pages(pvec.pages, pvec.nr); | |
468 | pagevec_release(&pvec); | |
469 | cond_resched(); | |
470 | } | |
471 | } | |
472 | ||
473 | /* | |
474 | * Remove range of pages and swap entries from radix tree, and free them. | |
475 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. | |
476 | */ | |
477 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, | |
478 | bool unfalloc) | |
479 | { | |
480 | struct address_space *mapping = inode->i_mapping; | |
481 | struct shmem_inode_info *info = SHMEM_I(inode); | |
482 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
483 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; | |
484 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); | |
485 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); | |
486 | struct pagevec pvec; | |
487 | pgoff_t indices[PAGEVEC_SIZE]; | |
488 | long nr_swaps_freed = 0; | |
489 | pgoff_t index; | |
490 | int i; | |
491 | ||
492 | if (lend == -1) | |
493 | end = -1; /* unsigned, so actually very big */ | |
494 | ||
495 | pagevec_init(&pvec, 0); | |
496 | index = start; | |
497 | while (index < end) { | |
498 | pvec.nr = find_get_entries(mapping, index, | |
499 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
500 | pvec.pages, indices); | |
501 | if (!pvec.nr) | |
502 | break; | |
503 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
504 | struct page *page = pvec.pages[i]; | |
505 | ||
506 | index = indices[i]; | |
507 | if (index >= end) | |
508 | break; | |
509 | ||
510 | if (radix_tree_exceptional_entry(page)) { | |
511 | if (unfalloc) | |
512 | continue; | |
513 | nr_swaps_freed += !shmem_free_swap(mapping, | |
514 | index, page); | |
515 | continue; | |
516 | } | |
517 | ||
518 | if (!trylock_page(page)) | |
519 | continue; | |
520 | if (!unfalloc || !PageUptodate(page)) { | |
521 | if (page->mapping == mapping) { | |
522 | VM_BUG_ON_PAGE(PageWriteback(page), page); | |
523 | truncate_inode_page(mapping, page); | |
524 | } | |
525 | } | |
526 | unlock_page(page); | |
527 | } | |
528 | pagevec_remove_exceptionals(&pvec); | |
529 | pagevec_release(&pvec); | |
530 | cond_resched(); | |
531 | index++; | |
532 | } | |
533 | ||
534 | if (partial_start) { | |
535 | struct page *page = NULL; | |
536 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); | |
537 | if (page) { | |
538 | unsigned int top = PAGE_CACHE_SIZE; | |
539 | if (start > end) { | |
540 | top = partial_end; | |
541 | partial_end = 0; | |
542 | } | |
543 | zero_user_segment(page, partial_start, top); | |
544 | set_page_dirty(page); | |
545 | unlock_page(page); | |
546 | page_cache_release(page); | |
547 | } | |
548 | } | |
549 | if (partial_end) { | |
550 | struct page *page = NULL; | |
551 | shmem_getpage(inode, end, &page, SGP_READ, NULL); | |
552 | if (page) { | |
553 | zero_user_segment(page, 0, partial_end); | |
554 | set_page_dirty(page); | |
555 | unlock_page(page); | |
556 | page_cache_release(page); | |
557 | } | |
558 | } | |
559 | if (start >= end) | |
560 | return; | |
561 | ||
562 | index = start; | |
563 | while (index < end) { | |
564 | cond_resched(); | |
565 | ||
566 | pvec.nr = find_get_entries(mapping, index, | |
567 | min(end - index, (pgoff_t)PAGEVEC_SIZE), | |
568 | pvec.pages, indices); | |
569 | if (!pvec.nr) { | |
570 | /* If all gone or hole-punch or unfalloc, we're done */ | |
571 | if (index == start || end != -1) | |
572 | break; | |
573 | /* But if truncating, restart to make sure all gone */ | |
574 | index = start; | |
575 | continue; | |
576 | } | |
577 | for (i = 0; i < pagevec_count(&pvec); i++) { | |
578 | struct page *page = pvec.pages[i]; | |
579 | ||
580 | index = indices[i]; | |
581 | if (index >= end) | |
582 | break; | |
583 | ||
584 | if (radix_tree_exceptional_entry(page)) { | |
585 | if (unfalloc) | |
586 | continue; | |
587 | if (shmem_free_swap(mapping, index, page)) { | |
588 | /* Swap was replaced by page: retry */ | |
589 | index--; | |
590 | break; | |
591 | } | |
592 | nr_swaps_freed++; | |
593 | continue; | |
594 | } | |
595 | ||
596 | lock_page(page); | |
597 | if (!unfalloc || !PageUptodate(page)) { | |
598 | if (page->mapping == mapping) { | |
599 | VM_BUG_ON_PAGE(PageWriteback(page), page); | |
600 | truncate_inode_page(mapping, page); | |
601 | } else { | |
602 | /* Page was replaced by swap: retry */ | |
603 | unlock_page(page); | |
604 | index--; | |
605 | break; | |
606 | } | |
607 | } | |
608 | unlock_page(page); | |
609 | } | |
610 | pagevec_remove_exceptionals(&pvec); | |
611 | pagevec_release(&pvec); | |
612 | index++; | |
613 | } | |
614 | ||
615 | spin_lock(&info->lock); | |
616 | info->swapped -= nr_swaps_freed; | |
617 | shmem_recalc_inode(inode); | |
618 | spin_unlock(&info->lock); | |
619 | } | |
620 | ||
621 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
622 | { | |
623 | shmem_undo_range(inode, lstart, lend, false); | |
624 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
625 | } | |
626 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
627 | ||
628 | static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry, | |
629 | struct kstat *stat) | |
630 | { | |
631 | struct inode *inode = dentry->d_inode; | |
632 | struct shmem_inode_info *info = SHMEM_I(inode); | |
633 | ||
634 | if (info->alloced - info->swapped != inode->i_mapping->nrpages) { | |
635 | spin_lock(&info->lock); | |
636 | shmem_recalc_inode(inode); | |
637 | spin_unlock(&info->lock); | |
638 | } | |
639 | generic_fillattr(inode, stat); | |
640 | return 0; | |
641 | } | |
642 | ||
643 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) | |
644 | { | |
645 | struct inode *inode = d_inode(dentry); | |
646 | struct shmem_inode_info *info = SHMEM_I(inode); | |
647 | int error; | |
648 | ||
649 | error = inode_change_ok(inode, attr); | |
650 | if (error) | |
651 | return error; | |
652 | ||
653 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { | |
654 | loff_t oldsize = inode->i_size; | |
655 | loff_t newsize = attr->ia_size; | |
656 | ||
657 | /* protected by i_mutex */ | |
658 | if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) || | |
659 | (newsize > oldsize && (info->seals & F_SEAL_GROW))) | |
660 | return -EPERM; | |
661 | ||
662 | if (newsize != oldsize) { | |
663 | error = shmem_reacct_size(SHMEM_I(inode)->flags, | |
664 | oldsize, newsize); | |
665 | if (error) | |
666 | return error; | |
667 | i_size_write(inode, newsize); | |
668 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; | |
669 | } | |
670 | if (newsize <= oldsize) { | |
671 | loff_t holebegin = round_up(newsize, PAGE_SIZE); | |
672 | if (oldsize > holebegin) | |
673 | unmap_mapping_range(inode->i_mapping, | |
674 | holebegin, 0, 1); | |
675 | if (info->alloced) | |
676 | shmem_truncate_range(inode, | |
677 | newsize, (loff_t)-1); | |
678 | /* unmap again to remove racily COWed private pages */ | |
679 | if (oldsize > holebegin) | |
680 | unmap_mapping_range(inode->i_mapping, | |
681 | holebegin, 0, 1); | |
682 | } | |
683 | } | |
684 | ||
685 | setattr_copy(inode, attr); | |
686 | if (attr->ia_valid & ATTR_MODE) | |
687 | error = posix_acl_chmod(inode, inode->i_mode); | |
688 | return error; | |
689 | } | |
690 | ||
691 | static void shmem_evict_inode(struct inode *inode) | |
692 | { | |
693 | struct shmem_inode_info *info = SHMEM_I(inode); | |
694 | ||
695 | if (inode->i_mapping->a_ops == &shmem_aops) { | |
696 | shmem_unacct_size(info->flags, inode->i_size); | |
697 | inode->i_size = 0; | |
698 | shmem_truncate_range(inode, 0, (loff_t)-1); | |
699 | if (!list_empty(&info->swaplist)) { | |
700 | mutex_lock(&shmem_swaplist_mutex); | |
701 | list_del_init(&info->swaplist); | |
702 | mutex_unlock(&shmem_swaplist_mutex); | |
703 | } | |
704 | } | |
705 | ||
706 | simple_xattrs_free(&info->xattrs); | |
707 | WARN_ON(inode->i_blocks); | |
708 | shmem_free_inode(inode->i_sb); | |
709 | clear_inode(inode); | |
710 | } | |
711 | ||
712 | /* | |
713 | * If swap found in inode, free it and move page from swapcache to filecache. | |
714 | */ | |
715 | static int shmem_unuse_inode(struct shmem_inode_info *info, | |
716 | swp_entry_t swap, struct page **pagep) | |
717 | { | |
718 | struct address_space *mapping = info->vfs_inode.i_mapping; | |
719 | void *radswap; | |
720 | pgoff_t index; | |
721 | gfp_t gfp; | |
722 | int error = 0; | |
723 | ||
724 | radswap = swp_to_radix_entry(swap); | |
725 | index = radix_tree_locate_item(&mapping->page_tree, radswap); | |
726 | if (index == -1) | |
727 | return -EAGAIN; /* tell shmem_unuse we found nothing */ | |
728 | ||
729 | /* | |
730 | * Move _head_ to start search for next from here. | |
731 | * But be careful: shmem_evict_inode checks list_empty without taking | |
732 | * mutex, and there's an instant in list_move_tail when info->swaplist | |
733 | * would appear empty, if it were the only one on shmem_swaplist. | |
734 | */ | |
735 | if (shmem_swaplist.next != &info->swaplist) | |
736 | list_move_tail(&shmem_swaplist, &info->swaplist); | |
737 | ||
738 | gfp = mapping_gfp_mask(mapping); | |
739 | if (shmem_should_replace_page(*pagep, gfp)) { | |
740 | mutex_unlock(&shmem_swaplist_mutex); | |
741 | error = shmem_replace_page(pagep, gfp, info, index); | |
742 | mutex_lock(&shmem_swaplist_mutex); | |
743 | /* | |
744 | * We needed to drop mutex to make that restrictive page | |
745 | * allocation, but the inode might have been freed while we | |
746 | * dropped it: although a racing shmem_evict_inode() cannot | |
747 | * complete without emptying the radix_tree, our page lock | |
748 | * on this swapcache page is not enough to prevent that - | |
749 | * free_swap_and_cache() of our swap entry will only | |
750 | * trylock_page(), removing swap from radix_tree whatever. | |
751 | * | |
752 | * We must not proceed to shmem_add_to_page_cache() if the | |
753 | * inode has been freed, but of course we cannot rely on | |
754 | * inode or mapping or info to check that. However, we can | |
755 | * safely check if our swap entry is still in use (and here | |
756 | * it can't have got reused for another page): if it's still | |
757 | * in use, then the inode cannot have been freed yet, and we | |
758 | * can safely proceed (if it's no longer in use, that tells | |
759 | * nothing about the inode, but we don't need to unuse swap). | |
760 | */ | |
761 | if (!page_swapcount(*pagep)) | |
762 | error = -ENOENT; | |
763 | } | |
764 | ||
765 | /* | |
766 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, | |
767 | * but also to hold up shmem_evict_inode(): so inode cannot be freed | |
768 | * beneath us (pagelock doesn't help until the page is in pagecache). | |
769 | */ | |
770 | if (!error) | |
771 | error = shmem_add_to_page_cache(*pagep, mapping, index, | |
772 | radswap); | |
773 | if (error != -ENOMEM) { | |
774 | /* | |
775 | * Truncation and eviction use free_swap_and_cache(), which | |
776 | * only does trylock page: if we raced, best clean up here. | |
777 | */ | |
778 | delete_from_swap_cache(*pagep); | |
779 | set_page_dirty(*pagep); | |
780 | if (!error) { | |
781 | spin_lock(&info->lock); | |
782 | info->swapped--; | |
783 | spin_unlock(&info->lock); | |
784 | swap_free(swap); | |
785 | } | |
786 | } | |
787 | return error; | |
788 | } | |
789 | ||
790 | /* | |
791 | * Search through swapped inodes to find and replace swap by page. | |
792 | */ | |
793 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
794 | { | |
795 | struct list_head *this, *next; | |
796 | struct shmem_inode_info *info; | |
797 | struct mem_cgroup *memcg; | |
798 | int error = 0; | |
799 | ||
800 | /* | |
801 | * There's a faint possibility that swap page was replaced before | |
802 | * caller locked it: caller will come back later with the right page. | |
803 | */ | |
804 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) | |
805 | goto out; | |
806 | ||
807 | /* | |
808 | * Charge page using GFP_KERNEL while we can wait, before taking | |
809 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). | |
810 | * Charged back to the user (not to caller) when swap account is used. | |
811 | */ | |
812 | error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg, | |
813 | false); | |
814 | if (error) | |
815 | goto out; | |
816 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ | |
817 | error = -EAGAIN; | |
818 | ||
819 | mutex_lock(&shmem_swaplist_mutex); | |
820 | list_for_each_safe(this, next, &shmem_swaplist) { | |
821 | info = list_entry(this, struct shmem_inode_info, swaplist); | |
822 | if (info->swapped) | |
823 | error = shmem_unuse_inode(info, swap, &page); | |
824 | else | |
825 | list_del_init(&info->swaplist); | |
826 | cond_resched(); | |
827 | if (error != -EAGAIN) | |
828 | break; | |
829 | /* found nothing in this: move on to search the next */ | |
830 | } | |
831 | mutex_unlock(&shmem_swaplist_mutex); | |
832 | ||
833 | if (error) { | |
834 | if (error != -ENOMEM) | |
835 | error = 0; | |
836 | mem_cgroup_cancel_charge(page, memcg, false); | |
837 | } else | |
838 | mem_cgroup_commit_charge(page, memcg, true, false); | |
839 | out: | |
840 | unlock_page(page); | |
841 | page_cache_release(page); | |
842 | return error; | |
843 | } | |
844 | ||
845 | /* | |
846 | * Move the page from the page cache to the swap cache. | |
847 | */ | |
848 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) | |
849 | { | |
850 | struct shmem_inode_info *info; | |
851 | struct address_space *mapping; | |
852 | struct inode *inode; | |
853 | swp_entry_t swap; | |
854 | pgoff_t index; | |
855 | ||
856 | BUG_ON(!PageLocked(page)); | |
857 | mapping = page->mapping; | |
858 | index = page->index; | |
859 | inode = mapping->host; | |
860 | info = SHMEM_I(inode); | |
861 | if (info->flags & VM_LOCKED) | |
862 | goto redirty; | |
863 | if (!total_swap_pages) | |
864 | goto redirty; | |
865 | ||
866 | /* | |
867 | * Our capabilities prevent regular writeback or sync from ever calling | |
868 | * shmem_writepage; but a stacking filesystem might use ->writepage of | |
869 | * its underlying filesystem, in which case tmpfs should write out to | |
870 | * swap only in response to memory pressure, and not for the writeback | |
871 | * threads or sync. | |
872 | */ | |
873 | if (!wbc->for_reclaim) { | |
874 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ | |
875 | goto redirty; | |
876 | } | |
877 | ||
878 | /* | |
879 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC | |
880 | * value into swapfile.c, the only way we can correctly account for a | |
881 | * fallocated page arriving here is now to initialize it and write it. | |
882 | * | |
883 | * That's okay for a page already fallocated earlier, but if we have | |
884 | * not yet completed the fallocation, then (a) we want to keep track | |
885 | * of this page in case we have to undo it, and (b) it may not be a | |
886 | * good idea to continue anyway, once we're pushing into swap. So | |
887 | * reactivate the page, and let shmem_fallocate() quit when too many. | |
888 | */ | |
889 | if (!PageUptodate(page)) { | |
890 | if (inode->i_private) { | |
891 | struct shmem_falloc *shmem_falloc; | |
892 | spin_lock(&inode->i_lock); | |
893 | shmem_falloc = inode->i_private; | |
894 | if (shmem_falloc && | |
895 | !shmem_falloc->waitq && | |
896 | index >= shmem_falloc->start && | |
897 | index < shmem_falloc->next) | |
898 | shmem_falloc->nr_unswapped++; | |
899 | else | |
900 | shmem_falloc = NULL; | |
901 | spin_unlock(&inode->i_lock); | |
902 | if (shmem_falloc) | |
903 | goto redirty; | |
904 | } | |
905 | clear_highpage(page); | |
906 | flush_dcache_page(page); | |
907 | SetPageUptodate(page); | |
908 | } | |
909 | ||
910 | swap = get_swap_page(); | |
911 | if (!swap.val) | |
912 | goto redirty; | |
913 | ||
914 | if (mem_cgroup_try_charge_swap(page, swap)) | |
915 | goto free_swap; | |
916 | ||
917 | /* | |
918 | * Add inode to shmem_unuse()'s list of swapped-out inodes, | |
919 | * if it's not already there. Do it now before the page is | |
920 | * moved to swap cache, when its pagelock no longer protects | |
921 | * the inode from eviction. But don't unlock the mutex until | |
922 | * we've incremented swapped, because shmem_unuse_inode() will | |
923 | * prune a !swapped inode from the swaplist under this mutex. | |
924 | */ | |
925 | mutex_lock(&shmem_swaplist_mutex); | |
926 | if (list_empty(&info->swaplist)) | |
927 | list_add_tail(&info->swaplist, &shmem_swaplist); | |
928 | ||
929 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { | |
930 | spin_lock(&info->lock); | |
931 | shmem_recalc_inode(inode); | |
932 | info->swapped++; | |
933 | spin_unlock(&info->lock); | |
934 | ||
935 | swap_shmem_alloc(swap); | |
936 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); | |
937 | ||
938 | mutex_unlock(&shmem_swaplist_mutex); | |
939 | BUG_ON(page_mapped(page)); | |
940 | swap_writepage(page, wbc); | |
941 | return 0; | |
942 | } | |
943 | ||
944 | mutex_unlock(&shmem_swaplist_mutex); | |
945 | free_swap: | |
946 | swapcache_free(swap); | |
947 | redirty: | |
948 | set_page_dirty(page); | |
949 | if (wbc->for_reclaim) | |
950 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ | |
951 | unlock_page(page); | |
952 | return 0; | |
953 | } | |
954 | ||
955 | #ifdef CONFIG_NUMA | |
956 | #ifdef CONFIG_TMPFS | |
957 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
958 | { | |
959 | char buffer[64]; | |
960 | ||
961 | if (!mpol || mpol->mode == MPOL_DEFAULT) | |
962 | return; /* show nothing */ | |
963 | ||
964 | mpol_to_str(buffer, sizeof(buffer), mpol); | |
965 | ||
966 | seq_printf(seq, ",mpol=%s", buffer); | |
967 | } | |
968 | ||
969 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
970 | { | |
971 | struct mempolicy *mpol = NULL; | |
972 | if (sbinfo->mpol) { | |
973 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ | |
974 | mpol = sbinfo->mpol; | |
975 | mpol_get(mpol); | |
976 | spin_unlock(&sbinfo->stat_lock); | |
977 | } | |
978 | return mpol; | |
979 | } | |
980 | #endif /* CONFIG_TMPFS */ | |
981 | ||
982 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
983 | struct shmem_inode_info *info, pgoff_t index) | |
984 | { | |
985 | struct vm_area_struct pvma; | |
986 | struct page *page; | |
987 | ||
988 | /* Create a pseudo vma that just contains the policy */ | |
989 | pvma.vm_start = 0; | |
990 | /* Bias interleave by inode number to distribute better across nodes */ | |
991 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
992 | pvma.vm_ops = NULL; | |
993 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
994 | ||
995 | page = swapin_readahead(swap, gfp, &pvma, 0); | |
996 | ||
997 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
998 | mpol_cond_put(pvma.vm_policy); | |
999 | ||
1000 | return page; | |
1001 | } | |
1002 | ||
1003 | static struct page *shmem_alloc_page(gfp_t gfp, | |
1004 | struct shmem_inode_info *info, pgoff_t index) | |
1005 | { | |
1006 | struct vm_area_struct pvma; | |
1007 | struct page *page; | |
1008 | ||
1009 | /* Create a pseudo vma that just contains the policy */ | |
1010 | pvma.vm_start = 0; | |
1011 | /* Bias interleave by inode number to distribute better across nodes */ | |
1012 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; | |
1013 | pvma.vm_ops = NULL; | |
1014 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); | |
1015 | ||
1016 | page = alloc_page_vma(gfp, &pvma, 0); | |
1017 | ||
1018 | /* Drop reference taken by mpol_shared_policy_lookup() */ | |
1019 | mpol_cond_put(pvma.vm_policy); | |
1020 | ||
1021 | return page; | |
1022 | } | |
1023 | #else /* !CONFIG_NUMA */ | |
1024 | #ifdef CONFIG_TMPFS | |
1025 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) | |
1026 | { | |
1027 | } | |
1028 | #endif /* CONFIG_TMPFS */ | |
1029 | ||
1030 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, | |
1031 | struct shmem_inode_info *info, pgoff_t index) | |
1032 | { | |
1033 | return swapin_readahead(swap, gfp, NULL, 0); | |
1034 | } | |
1035 | ||
1036 | static inline struct page *shmem_alloc_page(gfp_t gfp, | |
1037 | struct shmem_inode_info *info, pgoff_t index) | |
1038 | { | |
1039 | return alloc_page(gfp); | |
1040 | } | |
1041 | #endif /* CONFIG_NUMA */ | |
1042 | ||
1043 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) | |
1044 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) | |
1045 | { | |
1046 | return NULL; | |
1047 | } | |
1048 | #endif | |
1049 | ||
1050 | /* | |
1051 | * When a page is moved from swapcache to shmem filecache (either by the | |
1052 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of | |
1053 | * shmem_unuse_inode()), it may have been read in earlier from swap, in | |
1054 | * ignorance of the mapping it belongs to. If that mapping has special | |
1055 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), | |
1056 | * we may need to copy to a suitable page before moving to filecache. | |
1057 | * | |
1058 | * In a future release, this may well be extended to respect cpuset and | |
1059 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); | |
1060 | * but for now it is a simple matter of zone. | |
1061 | */ | |
1062 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) | |
1063 | { | |
1064 | return page_zonenum(page) > gfp_zone(gfp); | |
1065 | } | |
1066 | ||
1067 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, | |
1068 | struct shmem_inode_info *info, pgoff_t index) | |
1069 | { | |
1070 | struct page *oldpage, *newpage; | |
1071 | struct address_space *swap_mapping; | |
1072 | pgoff_t swap_index; | |
1073 | int error; | |
1074 | ||
1075 | oldpage = *pagep; | |
1076 | swap_index = page_private(oldpage); | |
1077 | swap_mapping = page_mapping(oldpage); | |
1078 | ||
1079 | /* | |
1080 | * We have arrived here because our zones are constrained, so don't | |
1081 | * limit chance of success by further cpuset and node constraints. | |
1082 | */ | |
1083 | gfp &= ~GFP_CONSTRAINT_MASK; | |
1084 | newpage = shmem_alloc_page(gfp, info, index); | |
1085 | if (!newpage) | |
1086 | return -ENOMEM; | |
1087 | ||
1088 | page_cache_get(newpage); | |
1089 | copy_highpage(newpage, oldpage); | |
1090 | flush_dcache_page(newpage); | |
1091 | ||
1092 | __SetPageLocked(newpage); | |
1093 | SetPageUptodate(newpage); | |
1094 | SetPageSwapBacked(newpage); | |
1095 | set_page_private(newpage, swap_index); | |
1096 | SetPageSwapCache(newpage); | |
1097 | ||
1098 | /* | |
1099 | * Our caller will very soon move newpage out of swapcache, but it's | |
1100 | * a nice clean interface for us to replace oldpage by newpage there. | |
1101 | */ | |
1102 | spin_lock_irq(&swap_mapping->tree_lock); | |
1103 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, | |
1104 | newpage); | |
1105 | if (!error) { | |
1106 | __inc_zone_page_state(newpage, NR_FILE_PAGES); | |
1107 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); | |
1108 | } | |
1109 | spin_unlock_irq(&swap_mapping->tree_lock); | |
1110 | ||
1111 | if (unlikely(error)) { | |
1112 | /* | |
1113 | * Is this possible? I think not, now that our callers check | |
1114 | * both PageSwapCache and page_private after getting page lock; | |
1115 | * but be defensive. Reverse old to newpage for clear and free. | |
1116 | */ | |
1117 | oldpage = newpage; | |
1118 | } else { | |
1119 | mem_cgroup_migrate(oldpage, newpage); | |
1120 | lru_cache_add_anon(newpage); | |
1121 | *pagep = newpage; | |
1122 | } | |
1123 | ||
1124 | ClearPageSwapCache(oldpage); | |
1125 | set_page_private(oldpage, 0); | |
1126 | ||
1127 | unlock_page(oldpage); | |
1128 | page_cache_release(oldpage); | |
1129 | page_cache_release(oldpage); | |
1130 | return error; | |
1131 | } | |
1132 | ||
1133 | /* | |
1134 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate | |
1135 | * | |
1136 | * If we allocate a new one we do not mark it dirty. That's up to the | |
1137 | * vm. If we swap it in we mark it dirty since we also free the swap | |
1138 | * entry since a page cannot live in both the swap and page cache | |
1139 | */ | |
1140 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, | |
1141 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) | |
1142 | { | |
1143 | struct address_space *mapping = inode->i_mapping; | |
1144 | struct shmem_inode_info *info; | |
1145 | struct shmem_sb_info *sbinfo; | |
1146 | struct mem_cgroup *memcg; | |
1147 | struct page *page; | |
1148 | swp_entry_t swap; | |
1149 | int error; | |
1150 | int once = 0; | |
1151 | int alloced = 0; | |
1152 | ||
1153 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) | |
1154 | return -EFBIG; | |
1155 | repeat: | |
1156 | swap.val = 0; | |
1157 | page = find_lock_entry(mapping, index); | |
1158 | if (radix_tree_exceptional_entry(page)) { | |
1159 | swap = radix_to_swp_entry(page); | |
1160 | page = NULL; | |
1161 | } | |
1162 | ||
1163 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1164 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1165 | error = -EINVAL; | |
1166 | goto unlock; | |
1167 | } | |
1168 | ||
1169 | if (page && sgp == SGP_WRITE) | |
1170 | mark_page_accessed(page); | |
1171 | ||
1172 | /* fallocated page? */ | |
1173 | if (page && !PageUptodate(page)) { | |
1174 | if (sgp != SGP_READ) | |
1175 | goto clear; | |
1176 | unlock_page(page); | |
1177 | page_cache_release(page); | |
1178 | page = NULL; | |
1179 | } | |
1180 | if (page || (sgp == SGP_READ && !swap.val)) { | |
1181 | *pagep = page; | |
1182 | return 0; | |
1183 | } | |
1184 | ||
1185 | /* | |
1186 | * Fast cache lookup did not find it: | |
1187 | * bring it back from swap or allocate. | |
1188 | */ | |
1189 | info = SHMEM_I(inode); | |
1190 | sbinfo = SHMEM_SB(inode->i_sb); | |
1191 | ||
1192 | if (swap.val) { | |
1193 | /* Look it up and read it in.. */ | |
1194 | page = lookup_swap_cache(swap); | |
1195 | if (!page) { | |
1196 | /* here we actually do the io */ | |
1197 | if (fault_type) | |
1198 | *fault_type |= VM_FAULT_MAJOR; | |
1199 | page = shmem_swapin(swap, gfp, info, index); | |
1200 | if (!page) { | |
1201 | error = -ENOMEM; | |
1202 | goto failed; | |
1203 | } | |
1204 | } | |
1205 | ||
1206 | /* We have to do this with page locked to prevent races */ | |
1207 | lock_page(page); | |
1208 | if (!PageSwapCache(page) || page_private(page) != swap.val || | |
1209 | !shmem_confirm_swap(mapping, index, swap)) { | |
1210 | error = -EEXIST; /* try again */ | |
1211 | goto unlock; | |
1212 | } | |
1213 | if (!PageUptodate(page)) { | |
1214 | error = -EIO; | |
1215 | goto failed; | |
1216 | } | |
1217 | wait_on_page_writeback(page); | |
1218 | ||
1219 | if (shmem_should_replace_page(page, gfp)) { | |
1220 | error = shmem_replace_page(&page, gfp, info, index); | |
1221 | if (error) | |
1222 | goto failed; | |
1223 | } | |
1224 | ||
1225 | error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg, | |
1226 | false); | |
1227 | if (!error) { | |
1228 | error = shmem_add_to_page_cache(page, mapping, index, | |
1229 | swp_to_radix_entry(swap)); | |
1230 | /* | |
1231 | * We already confirmed swap under page lock, and make | |
1232 | * no memory allocation here, so usually no possibility | |
1233 | * of error; but free_swap_and_cache() only trylocks a | |
1234 | * page, so it is just possible that the entry has been | |
1235 | * truncated or holepunched since swap was confirmed. | |
1236 | * shmem_undo_range() will have done some of the | |
1237 | * unaccounting, now delete_from_swap_cache() will do | |
1238 | * the rest. | |
1239 | * Reset swap.val? No, leave it so "failed" goes back to | |
1240 | * "repeat": reading a hole and writing should succeed. | |
1241 | */ | |
1242 | if (error) { | |
1243 | mem_cgroup_cancel_charge(page, memcg, false); | |
1244 | delete_from_swap_cache(page); | |
1245 | } | |
1246 | } | |
1247 | if (error) | |
1248 | goto failed; | |
1249 | ||
1250 | mem_cgroup_commit_charge(page, memcg, true, false); | |
1251 | ||
1252 | spin_lock(&info->lock); | |
1253 | info->swapped--; | |
1254 | shmem_recalc_inode(inode); | |
1255 | spin_unlock(&info->lock); | |
1256 | ||
1257 | if (sgp == SGP_WRITE) | |
1258 | mark_page_accessed(page); | |
1259 | ||
1260 | delete_from_swap_cache(page); | |
1261 | set_page_dirty(page); | |
1262 | swap_free(swap); | |
1263 | ||
1264 | } else { | |
1265 | if (shmem_acct_block(info->flags)) { | |
1266 | error = -ENOSPC; | |
1267 | goto failed; | |
1268 | } | |
1269 | if (sbinfo->max_blocks) { | |
1270 | if (percpu_counter_compare(&sbinfo->used_blocks, | |
1271 | sbinfo->max_blocks) >= 0) { | |
1272 | error = -ENOSPC; | |
1273 | goto unacct; | |
1274 | } | |
1275 | percpu_counter_inc(&sbinfo->used_blocks); | |
1276 | } | |
1277 | ||
1278 | page = shmem_alloc_page(gfp, info, index); | |
1279 | if (!page) { | |
1280 | error = -ENOMEM; | |
1281 | goto decused; | |
1282 | } | |
1283 | ||
1284 | __SetPageSwapBacked(page); | |
1285 | __SetPageLocked(page); | |
1286 | if (sgp == SGP_WRITE) | |
1287 | __SetPageReferenced(page); | |
1288 | ||
1289 | error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg, | |
1290 | false); | |
1291 | if (error) | |
1292 | goto decused; | |
1293 | error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK); | |
1294 | if (!error) { | |
1295 | error = shmem_add_to_page_cache(page, mapping, index, | |
1296 | NULL); | |
1297 | radix_tree_preload_end(); | |
1298 | } | |
1299 | if (error) { | |
1300 | mem_cgroup_cancel_charge(page, memcg, false); | |
1301 | goto decused; | |
1302 | } | |
1303 | mem_cgroup_commit_charge(page, memcg, false, false); | |
1304 | lru_cache_add_anon(page); | |
1305 | ||
1306 | spin_lock(&info->lock); | |
1307 | info->alloced++; | |
1308 | inode->i_blocks += BLOCKS_PER_PAGE; | |
1309 | shmem_recalc_inode(inode); | |
1310 | spin_unlock(&info->lock); | |
1311 | alloced = true; | |
1312 | ||
1313 | /* | |
1314 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. | |
1315 | */ | |
1316 | if (sgp == SGP_FALLOC) | |
1317 | sgp = SGP_WRITE; | |
1318 | clear: | |
1319 | /* | |
1320 | * Let SGP_WRITE caller clear ends if write does not fill page; | |
1321 | * but SGP_FALLOC on a page fallocated earlier must initialize | |
1322 | * it now, lest undo on failure cancel our earlier guarantee. | |
1323 | */ | |
1324 | if (sgp != SGP_WRITE) { | |
1325 | clear_highpage(page); | |
1326 | flush_dcache_page(page); | |
1327 | SetPageUptodate(page); | |
1328 | } | |
1329 | if (sgp == SGP_DIRTY) | |
1330 | set_page_dirty(page); | |
1331 | } | |
1332 | ||
1333 | /* Perhaps the file has been truncated since we checked */ | |
1334 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && | |
1335 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { | |
1336 | if (alloced) { | |
1337 | ClearPageDirty(page); | |
1338 | delete_from_page_cache(page); | |
1339 | spin_lock(&info->lock); | |
1340 | shmem_recalc_inode(inode); | |
1341 | spin_unlock(&info->lock); | |
1342 | } | |
1343 | error = -EINVAL; | |
1344 | goto unlock; | |
1345 | } | |
1346 | *pagep = page; | |
1347 | return 0; | |
1348 | ||
1349 | /* | |
1350 | * Error recovery. | |
1351 | */ | |
1352 | decused: | |
1353 | if (sbinfo->max_blocks) | |
1354 | percpu_counter_add(&sbinfo->used_blocks, -1); | |
1355 | unacct: | |
1356 | shmem_unacct_blocks(info->flags, 1); | |
1357 | failed: | |
1358 | if (swap.val && !shmem_confirm_swap(mapping, index, swap)) | |
1359 | error = -EEXIST; | |
1360 | unlock: | |
1361 | if (page) { | |
1362 | unlock_page(page); | |
1363 | page_cache_release(page); | |
1364 | } | |
1365 | if (error == -ENOSPC && !once++) { | |
1366 | info = SHMEM_I(inode); | |
1367 | spin_lock(&info->lock); | |
1368 | shmem_recalc_inode(inode); | |
1369 | spin_unlock(&info->lock); | |
1370 | goto repeat; | |
1371 | } | |
1372 | if (error == -EEXIST) /* from above or from radix_tree_insert */ | |
1373 | goto repeat; | |
1374 | return error; | |
1375 | } | |
1376 | ||
1377 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) | |
1378 | { | |
1379 | struct inode *inode = file_inode(vma->vm_file); | |
1380 | int error; | |
1381 | int ret = VM_FAULT_LOCKED; | |
1382 | ||
1383 | /* | |
1384 | * Trinity finds that probing a hole which tmpfs is punching can | |
1385 | * prevent the hole-punch from ever completing: which in turn | |
1386 | * locks writers out with its hold on i_mutex. So refrain from | |
1387 | * faulting pages into the hole while it's being punched. Although | |
1388 | * shmem_undo_range() does remove the additions, it may be unable to | |
1389 | * keep up, as each new page needs its own unmap_mapping_range() call, | |
1390 | * and the i_mmap tree grows ever slower to scan if new vmas are added. | |
1391 | * | |
1392 | * It does not matter if we sometimes reach this check just before the | |
1393 | * hole-punch begins, so that one fault then races with the punch: | |
1394 | * we just need to make racing faults a rare case. | |
1395 | * | |
1396 | * The implementation below would be much simpler if we just used a | |
1397 | * standard mutex or completion: but we cannot take i_mutex in fault, | |
1398 | * and bloating every shmem inode for this unlikely case would be sad. | |
1399 | */ | |
1400 | if (unlikely(inode->i_private)) { | |
1401 | struct shmem_falloc *shmem_falloc; | |
1402 | ||
1403 | spin_lock(&inode->i_lock); | |
1404 | shmem_falloc = inode->i_private; | |
1405 | if (shmem_falloc && | |
1406 | shmem_falloc->waitq && | |
1407 | vmf->pgoff >= shmem_falloc->start && | |
1408 | vmf->pgoff < shmem_falloc->next) { | |
1409 | wait_queue_head_t *shmem_falloc_waitq; | |
1410 | DEFINE_WAIT(shmem_fault_wait); | |
1411 | ||
1412 | ret = VM_FAULT_NOPAGE; | |
1413 | if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) && | |
1414 | !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) { | |
1415 | /* It's polite to up mmap_sem if we can */ | |
1416 | up_read(&vma->vm_mm->mmap_sem); | |
1417 | ret = VM_FAULT_RETRY; | |
1418 | } | |
1419 | ||
1420 | shmem_falloc_waitq = shmem_falloc->waitq; | |
1421 | prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait, | |
1422 | TASK_UNINTERRUPTIBLE); | |
1423 | spin_unlock(&inode->i_lock); | |
1424 | schedule(); | |
1425 | ||
1426 | /* | |
1427 | * shmem_falloc_waitq points into the shmem_fallocate() | |
1428 | * stack of the hole-punching task: shmem_falloc_waitq | |
1429 | * is usually invalid by the time we reach here, but | |
1430 | * finish_wait() does not dereference it in that case; | |
1431 | * though i_lock needed lest racing with wake_up_all(). | |
1432 | */ | |
1433 | spin_lock(&inode->i_lock); | |
1434 | finish_wait(shmem_falloc_waitq, &shmem_fault_wait); | |
1435 | spin_unlock(&inode->i_lock); | |
1436 | return ret; | |
1437 | } | |
1438 | spin_unlock(&inode->i_lock); | |
1439 | } | |
1440 | ||
1441 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); | |
1442 | if (error) | |
1443 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); | |
1444 | ||
1445 | if (ret & VM_FAULT_MAJOR) { | |
1446 | count_vm_event(PGMAJFAULT); | |
1447 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); | |
1448 | } | |
1449 | return ret; | |
1450 | } | |
1451 | ||
1452 | #ifdef CONFIG_NUMA | |
1453 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) | |
1454 | { | |
1455 | struct inode *inode = file_inode(vma->vm_file); | |
1456 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); | |
1457 | } | |
1458 | ||
1459 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, | |
1460 | unsigned long addr) | |
1461 | { | |
1462 | struct inode *inode = file_inode(vma->vm_file); | |
1463 | pgoff_t index; | |
1464 | ||
1465 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
1466 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); | |
1467 | } | |
1468 | #endif | |
1469 | ||
1470 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
1471 | { | |
1472 | struct inode *inode = file_inode(file); | |
1473 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1474 | int retval = -ENOMEM; | |
1475 | ||
1476 | spin_lock(&info->lock); | |
1477 | if (lock && !(info->flags & VM_LOCKED)) { | |
1478 | if (!user_shm_lock(inode->i_size, user)) | |
1479 | goto out_nomem; | |
1480 | info->flags |= VM_LOCKED; | |
1481 | mapping_set_unevictable(file->f_mapping); | |
1482 | } | |
1483 | if (!lock && (info->flags & VM_LOCKED) && user) { | |
1484 | user_shm_unlock(inode->i_size, user); | |
1485 | info->flags &= ~VM_LOCKED; | |
1486 | mapping_clear_unevictable(file->f_mapping); | |
1487 | } | |
1488 | retval = 0; | |
1489 | ||
1490 | out_nomem: | |
1491 | spin_unlock(&info->lock); | |
1492 | return retval; | |
1493 | } | |
1494 | ||
1495 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) | |
1496 | { | |
1497 | file_accessed(file); | |
1498 | vma->vm_ops = &shmem_vm_ops; | |
1499 | return 0; | |
1500 | } | |
1501 | ||
1502 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, | |
1503 | umode_t mode, dev_t dev, unsigned long flags) | |
1504 | { | |
1505 | struct inode *inode; | |
1506 | struct shmem_inode_info *info; | |
1507 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
1508 | ||
1509 | if (shmem_reserve_inode(sb)) | |
1510 | return NULL; | |
1511 | ||
1512 | inode = new_inode(sb); | |
1513 | if (inode) { | |
1514 | inode->i_ino = get_next_ino(); | |
1515 | inode_init_owner(inode, dir, mode); | |
1516 | inode->i_blocks = 0; | |
1517 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
1518 | inode->i_generation = get_seconds(); | |
1519 | info = SHMEM_I(inode); | |
1520 | memset(info, 0, (char *)inode - (char *)info); | |
1521 | spin_lock_init(&info->lock); | |
1522 | info->seals = F_SEAL_SEAL; | |
1523 | info->flags = flags & VM_NORESERVE; | |
1524 | INIT_LIST_HEAD(&info->swaplist); | |
1525 | simple_xattrs_init(&info->xattrs); | |
1526 | cache_no_acl(inode); | |
1527 | ||
1528 | switch (mode & S_IFMT) { | |
1529 | default: | |
1530 | inode->i_op = &shmem_special_inode_operations; | |
1531 | init_special_inode(inode, mode, dev); | |
1532 | break; | |
1533 | case S_IFREG: | |
1534 | inode->i_mapping->a_ops = &shmem_aops; | |
1535 | inode->i_op = &shmem_inode_operations; | |
1536 | inode->i_fop = &shmem_file_operations; | |
1537 | mpol_shared_policy_init(&info->policy, | |
1538 | shmem_get_sbmpol(sbinfo)); | |
1539 | break; | |
1540 | case S_IFDIR: | |
1541 | inc_nlink(inode); | |
1542 | /* Some things misbehave if size == 0 on a directory */ | |
1543 | inode->i_size = 2 * BOGO_DIRENT_SIZE; | |
1544 | inode->i_op = &shmem_dir_inode_operations; | |
1545 | inode->i_fop = &simple_dir_operations; | |
1546 | break; | |
1547 | case S_IFLNK: | |
1548 | /* | |
1549 | * Must not load anything in the rbtree, | |
1550 | * mpol_free_shared_policy will not be called. | |
1551 | */ | |
1552 | mpol_shared_policy_init(&info->policy, NULL); | |
1553 | break; | |
1554 | } | |
1555 | } else | |
1556 | shmem_free_inode(sb); | |
1557 | return inode; | |
1558 | } | |
1559 | ||
1560 | bool shmem_mapping(struct address_space *mapping) | |
1561 | { | |
1562 | if (!mapping->host) | |
1563 | return false; | |
1564 | ||
1565 | return mapping->host->i_sb->s_op == &shmem_ops; | |
1566 | } | |
1567 | ||
1568 | #ifdef CONFIG_TMPFS | |
1569 | static const struct inode_operations shmem_symlink_inode_operations; | |
1570 | static const struct inode_operations shmem_short_symlink_operations; | |
1571 | ||
1572 | #ifdef CONFIG_TMPFS_XATTR | |
1573 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); | |
1574 | #else | |
1575 | #define shmem_initxattrs NULL | |
1576 | #endif | |
1577 | ||
1578 | static int | |
1579 | shmem_write_begin(struct file *file, struct address_space *mapping, | |
1580 | loff_t pos, unsigned len, unsigned flags, | |
1581 | struct page **pagep, void **fsdata) | |
1582 | { | |
1583 | struct inode *inode = mapping->host; | |
1584 | struct shmem_inode_info *info = SHMEM_I(inode); | |
1585 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; | |
1586 | ||
1587 | /* i_mutex is held by caller */ | |
1588 | if (unlikely(info->seals)) { | |
1589 | if (info->seals & F_SEAL_WRITE) | |
1590 | return -EPERM; | |
1591 | if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size) | |
1592 | return -EPERM; | |
1593 | } | |
1594 | ||
1595 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); | |
1596 | } | |
1597 | ||
1598 | static int | |
1599 | shmem_write_end(struct file *file, struct address_space *mapping, | |
1600 | loff_t pos, unsigned len, unsigned copied, | |
1601 | struct page *page, void *fsdata) | |
1602 | { | |
1603 | struct inode *inode = mapping->host; | |
1604 | ||
1605 | if (pos + copied > inode->i_size) | |
1606 | i_size_write(inode, pos + copied); | |
1607 | ||
1608 | if (!PageUptodate(page)) { | |
1609 | if (copied < PAGE_CACHE_SIZE) { | |
1610 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); | |
1611 | zero_user_segments(page, 0, from, | |
1612 | from + copied, PAGE_CACHE_SIZE); | |
1613 | } | |
1614 | SetPageUptodate(page); | |
1615 | } | |
1616 | set_page_dirty(page); | |
1617 | unlock_page(page); | |
1618 | page_cache_release(page); | |
1619 | ||
1620 | return copied; | |
1621 | } | |
1622 | ||
1623 | static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) | |
1624 | { | |
1625 | struct file *file = iocb->ki_filp; | |
1626 | struct inode *inode = file_inode(file); | |
1627 | struct address_space *mapping = inode->i_mapping; | |
1628 | pgoff_t index; | |
1629 | unsigned long offset; | |
1630 | enum sgp_type sgp = SGP_READ; | |
1631 | int error = 0; | |
1632 | ssize_t retval = 0; | |
1633 | loff_t *ppos = &iocb->ki_pos; | |
1634 | ||
1635 | /* | |
1636 | * Might this read be for a stacking filesystem? Then when reading | |
1637 | * holes of a sparse file, we actually need to allocate those pages, | |
1638 | * and even mark them dirty, so it cannot exceed the max_blocks limit. | |
1639 | */ | |
1640 | if (!iter_is_iovec(to)) | |
1641 | sgp = SGP_DIRTY; | |
1642 | ||
1643 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1644 | offset = *ppos & ~PAGE_CACHE_MASK; | |
1645 | ||
1646 | for (;;) { | |
1647 | struct page *page = NULL; | |
1648 | pgoff_t end_index; | |
1649 | unsigned long nr, ret; | |
1650 | loff_t i_size = i_size_read(inode); | |
1651 | ||
1652 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1653 | if (index > end_index) | |
1654 | break; | |
1655 | if (index == end_index) { | |
1656 | nr = i_size & ~PAGE_CACHE_MASK; | |
1657 | if (nr <= offset) | |
1658 | break; | |
1659 | } | |
1660 | ||
1661 | error = shmem_getpage(inode, index, &page, sgp, NULL); | |
1662 | if (error) { | |
1663 | if (error == -EINVAL) | |
1664 | error = 0; | |
1665 | break; | |
1666 | } | |
1667 | if (page) | |
1668 | unlock_page(page); | |
1669 | ||
1670 | /* | |
1671 | * We must evaluate after, since reads (unlike writes) | |
1672 | * are called without i_mutex protection against truncate | |
1673 | */ | |
1674 | nr = PAGE_CACHE_SIZE; | |
1675 | i_size = i_size_read(inode); | |
1676 | end_index = i_size >> PAGE_CACHE_SHIFT; | |
1677 | if (index == end_index) { | |
1678 | nr = i_size & ~PAGE_CACHE_MASK; | |
1679 | if (nr <= offset) { | |
1680 | if (page) | |
1681 | page_cache_release(page); | |
1682 | break; | |
1683 | } | |
1684 | } | |
1685 | nr -= offset; | |
1686 | ||
1687 | if (page) { | |
1688 | /* | |
1689 | * If users can be writing to this page using arbitrary | |
1690 | * virtual addresses, take care about potential aliasing | |
1691 | * before reading the page on the kernel side. | |
1692 | */ | |
1693 | if (mapping_writably_mapped(mapping)) | |
1694 | flush_dcache_page(page); | |
1695 | /* | |
1696 | * Mark the page accessed if we read the beginning. | |
1697 | */ | |
1698 | if (!offset) | |
1699 | mark_page_accessed(page); | |
1700 | } else { | |
1701 | page = ZERO_PAGE(0); | |
1702 | page_cache_get(page); | |
1703 | } | |
1704 | ||
1705 | /* | |
1706 | * Ok, we have the page, and it's up-to-date, so | |
1707 | * now we can copy it to user space... | |
1708 | */ | |
1709 | ret = copy_page_to_iter(page, offset, nr, to); | |
1710 | retval += ret; | |
1711 | offset += ret; | |
1712 | index += offset >> PAGE_CACHE_SHIFT; | |
1713 | offset &= ~PAGE_CACHE_MASK; | |
1714 | ||
1715 | page_cache_release(page); | |
1716 | if (!iov_iter_count(to)) | |
1717 | break; | |
1718 | if (ret < nr) { | |
1719 | error = -EFAULT; | |
1720 | break; | |
1721 | } | |
1722 | cond_resched(); | |
1723 | } | |
1724 | ||
1725 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; | |
1726 | file_accessed(file); | |
1727 | return retval ? retval : error; | |
1728 | } | |
1729 | ||
1730 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, | |
1731 | struct pipe_inode_info *pipe, size_t len, | |
1732 | unsigned int flags) | |
1733 | { | |
1734 | struct address_space *mapping = in->f_mapping; | |
1735 | struct inode *inode = mapping->host; | |
1736 | unsigned int loff, nr_pages, req_pages; | |
1737 | struct page *pages[PIPE_DEF_BUFFERS]; | |
1738 | struct partial_page partial[PIPE_DEF_BUFFERS]; | |
1739 | struct page *page; | |
1740 | pgoff_t index, end_index; | |
1741 | loff_t isize, left; | |
1742 | int error, page_nr; | |
1743 | struct splice_pipe_desc spd = { | |
1744 | .pages = pages, | |
1745 | .partial = partial, | |
1746 | .nr_pages_max = PIPE_DEF_BUFFERS, | |
1747 | .flags = flags, | |
1748 | .ops = &page_cache_pipe_buf_ops, | |
1749 | .spd_release = spd_release_page, | |
1750 | }; | |
1751 | ||
1752 | isize = i_size_read(inode); | |
1753 | if (unlikely(*ppos >= isize)) | |
1754 | return 0; | |
1755 | ||
1756 | left = isize - *ppos; | |
1757 | if (unlikely(left < len)) | |
1758 | len = left; | |
1759 | ||
1760 | if (splice_grow_spd(pipe, &spd)) | |
1761 | return -ENOMEM; | |
1762 | ||
1763 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1764 | loff = *ppos & ~PAGE_CACHE_MASK; | |
1765 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1766 | nr_pages = min(req_pages, spd.nr_pages_max); | |
1767 | ||
1768 | spd.nr_pages = find_get_pages_contig(mapping, index, | |
1769 | nr_pages, spd.pages); | |
1770 | index += spd.nr_pages; | |
1771 | error = 0; | |
1772 | ||
1773 | while (spd.nr_pages < nr_pages) { | |
1774 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); | |
1775 | if (error) | |
1776 | break; | |
1777 | unlock_page(page); | |
1778 | spd.pages[spd.nr_pages++] = page; | |
1779 | index++; | |
1780 | } | |
1781 | ||
1782 | index = *ppos >> PAGE_CACHE_SHIFT; | |
1783 | nr_pages = spd.nr_pages; | |
1784 | spd.nr_pages = 0; | |
1785 | ||
1786 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { | |
1787 | unsigned int this_len; | |
1788 | ||
1789 | if (!len) | |
1790 | break; | |
1791 | ||
1792 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); | |
1793 | page = spd.pages[page_nr]; | |
1794 | ||
1795 | if (!PageUptodate(page) || page->mapping != mapping) { | |
1796 | error = shmem_getpage(inode, index, &page, | |
1797 | SGP_CACHE, NULL); | |
1798 | if (error) | |
1799 | break; | |
1800 | unlock_page(page); | |
1801 | page_cache_release(spd.pages[page_nr]); | |
1802 | spd.pages[page_nr] = page; | |
1803 | } | |
1804 | ||
1805 | isize = i_size_read(inode); | |
1806 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; | |
1807 | if (unlikely(!isize || index > end_index)) | |
1808 | break; | |
1809 | ||
1810 | if (end_index == index) { | |
1811 | unsigned int plen; | |
1812 | ||
1813 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; | |
1814 | if (plen <= loff) | |
1815 | break; | |
1816 | ||
1817 | this_len = min(this_len, plen - loff); | |
1818 | len = this_len; | |
1819 | } | |
1820 | ||
1821 | spd.partial[page_nr].offset = loff; | |
1822 | spd.partial[page_nr].len = this_len; | |
1823 | len -= this_len; | |
1824 | loff = 0; | |
1825 | spd.nr_pages++; | |
1826 | index++; | |
1827 | } | |
1828 | ||
1829 | while (page_nr < nr_pages) | |
1830 | page_cache_release(spd.pages[page_nr++]); | |
1831 | ||
1832 | if (spd.nr_pages) | |
1833 | error = splice_to_pipe(pipe, &spd); | |
1834 | ||
1835 | splice_shrink_spd(&spd); | |
1836 | ||
1837 | if (error > 0) { | |
1838 | *ppos += error; | |
1839 | file_accessed(in); | |
1840 | } | |
1841 | return error; | |
1842 | } | |
1843 | ||
1844 | /* | |
1845 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. | |
1846 | */ | |
1847 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, | |
1848 | pgoff_t index, pgoff_t end, int whence) | |
1849 | { | |
1850 | struct page *page; | |
1851 | struct pagevec pvec; | |
1852 | pgoff_t indices[PAGEVEC_SIZE]; | |
1853 | bool done = false; | |
1854 | int i; | |
1855 | ||
1856 | pagevec_init(&pvec, 0); | |
1857 | pvec.nr = 1; /* start small: we may be there already */ | |
1858 | while (!done) { | |
1859 | pvec.nr = find_get_entries(mapping, index, | |
1860 | pvec.nr, pvec.pages, indices); | |
1861 | if (!pvec.nr) { | |
1862 | if (whence == SEEK_DATA) | |
1863 | index = end; | |
1864 | break; | |
1865 | } | |
1866 | for (i = 0; i < pvec.nr; i++, index++) { | |
1867 | if (index < indices[i]) { | |
1868 | if (whence == SEEK_HOLE) { | |
1869 | done = true; | |
1870 | break; | |
1871 | } | |
1872 | index = indices[i]; | |
1873 | } | |
1874 | page = pvec.pages[i]; | |
1875 | if (page && !radix_tree_exceptional_entry(page)) { | |
1876 | if (!PageUptodate(page)) | |
1877 | page = NULL; | |
1878 | } | |
1879 | if (index >= end || | |
1880 | (page && whence == SEEK_DATA) || | |
1881 | (!page && whence == SEEK_HOLE)) { | |
1882 | done = true; | |
1883 | break; | |
1884 | } | |
1885 | } | |
1886 | pagevec_remove_exceptionals(&pvec); | |
1887 | pagevec_release(&pvec); | |
1888 | pvec.nr = PAGEVEC_SIZE; | |
1889 | cond_resched(); | |
1890 | } | |
1891 | return index; | |
1892 | } | |
1893 | ||
1894 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) | |
1895 | { | |
1896 | struct address_space *mapping = file->f_mapping; | |
1897 | struct inode *inode = mapping->host; | |
1898 | pgoff_t start, end; | |
1899 | loff_t new_offset; | |
1900 | ||
1901 | if (whence != SEEK_DATA && whence != SEEK_HOLE) | |
1902 | return generic_file_llseek_size(file, offset, whence, | |
1903 | MAX_LFS_FILESIZE, i_size_read(inode)); | |
1904 | inode_lock(inode); | |
1905 | /* We're holding i_mutex so we can access i_size directly */ | |
1906 | ||
1907 | if (offset < 0) | |
1908 | offset = -EINVAL; | |
1909 | else if (offset >= inode->i_size) | |
1910 | offset = -ENXIO; | |
1911 | else { | |
1912 | start = offset >> PAGE_CACHE_SHIFT; | |
1913 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
1914 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); | |
1915 | new_offset <<= PAGE_CACHE_SHIFT; | |
1916 | if (new_offset > offset) { | |
1917 | if (new_offset < inode->i_size) | |
1918 | offset = new_offset; | |
1919 | else if (whence == SEEK_DATA) | |
1920 | offset = -ENXIO; | |
1921 | else | |
1922 | offset = inode->i_size; | |
1923 | } | |
1924 | } | |
1925 | ||
1926 | if (offset >= 0) | |
1927 | offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); | |
1928 | inode_unlock(inode); | |
1929 | return offset; | |
1930 | } | |
1931 | ||
1932 | /* | |
1933 | * We need a tag: a new tag would expand every radix_tree_node by 8 bytes, | |
1934 | * so reuse a tag which we firmly believe is never set or cleared on shmem. | |
1935 | */ | |
1936 | #define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE | |
1937 | #define LAST_SCAN 4 /* about 150ms max */ | |
1938 | ||
1939 | static void shmem_tag_pins(struct address_space *mapping) | |
1940 | { | |
1941 | struct radix_tree_iter iter; | |
1942 | void **slot; | |
1943 | pgoff_t start; | |
1944 | struct page *page; | |
1945 | ||
1946 | lru_add_drain(); | |
1947 | start = 0; | |
1948 | rcu_read_lock(); | |
1949 | ||
1950 | restart: | |
1951 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { | |
1952 | page = radix_tree_deref_slot(slot); | |
1953 | if (!page || radix_tree_exception(page)) { | |
1954 | if (radix_tree_deref_retry(page)) | |
1955 | goto restart; | |
1956 | } else if (page_count(page) - page_mapcount(page) > 1) { | |
1957 | spin_lock_irq(&mapping->tree_lock); | |
1958 | radix_tree_tag_set(&mapping->page_tree, iter.index, | |
1959 | SHMEM_TAG_PINNED); | |
1960 | spin_unlock_irq(&mapping->tree_lock); | |
1961 | } | |
1962 | ||
1963 | if (need_resched()) { | |
1964 | cond_resched_rcu(); | |
1965 | start = iter.index + 1; | |
1966 | goto restart; | |
1967 | } | |
1968 | } | |
1969 | rcu_read_unlock(); | |
1970 | } | |
1971 | ||
1972 | /* | |
1973 | * Setting SEAL_WRITE requires us to verify there's no pending writer. However, | |
1974 | * via get_user_pages(), drivers might have some pending I/O without any active | |
1975 | * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages | |
1976 | * and see whether it has an elevated ref-count. If so, we tag them and wait for | |
1977 | * them to be dropped. | |
1978 | * The caller must guarantee that no new user will acquire writable references | |
1979 | * to those pages to avoid races. | |
1980 | */ | |
1981 | static int shmem_wait_for_pins(struct address_space *mapping) | |
1982 | { | |
1983 | struct radix_tree_iter iter; | |
1984 | void **slot; | |
1985 | pgoff_t start; | |
1986 | struct page *page; | |
1987 | int error, scan; | |
1988 | ||
1989 | shmem_tag_pins(mapping); | |
1990 | ||
1991 | error = 0; | |
1992 | for (scan = 0; scan <= LAST_SCAN; scan++) { | |
1993 | if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED)) | |
1994 | break; | |
1995 | ||
1996 | if (!scan) | |
1997 | lru_add_drain_all(); | |
1998 | else if (schedule_timeout_killable((HZ << scan) / 200)) | |
1999 | scan = LAST_SCAN; | |
2000 | ||
2001 | start = 0; | |
2002 | rcu_read_lock(); | |
2003 | restart: | |
2004 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, | |
2005 | start, SHMEM_TAG_PINNED) { | |
2006 | ||
2007 | page = radix_tree_deref_slot(slot); | |
2008 | if (radix_tree_exception(page)) { | |
2009 | if (radix_tree_deref_retry(page)) | |
2010 | goto restart; | |
2011 | ||
2012 | page = NULL; | |
2013 | } | |
2014 | ||
2015 | if (page && | |
2016 | page_count(page) - page_mapcount(page) != 1) { | |
2017 | if (scan < LAST_SCAN) | |
2018 | goto continue_resched; | |
2019 | ||
2020 | /* | |
2021 | * On the last scan, we clean up all those tags | |
2022 | * we inserted; but make a note that we still | |
2023 | * found pages pinned. | |
2024 | */ | |
2025 | error = -EBUSY; | |
2026 | } | |
2027 | ||
2028 | spin_lock_irq(&mapping->tree_lock); | |
2029 | radix_tree_tag_clear(&mapping->page_tree, | |
2030 | iter.index, SHMEM_TAG_PINNED); | |
2031 | spin_unlock_irq(&mapping->tree_lock); | |
2032 | continue_resched: | |
2033 | if (need_resched()) { | |
2034 | cond_resched_rcu(); | |
2035 | start = iter.index + 1; | |
2036 | goto restart; | |
2037 | } | |
2038 | } | |
2039 | rcu_read_unlock(); | |
2040 | } | |
2041 | ||
2042 | return error; | |
2043 | } | |
2044 | ||
2045 | #define F_ALL_SEALS (F_SEAL_SEAL | \ | |
2046 | F_SEAL_SHRINK | \ | |
2047 | F_SEAL_GROW | \ | |
2048 | F_SEAL_WRITE) | |
2049 | ||
2050 | int shmem_add_seals(struct file *file, unsigned int seals) | |
2051 | { | |
2052 | struct inode *inode = file_inode(file); | |
2053 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2054 | int error; | |
2055 | ||
2056 | /* | |
2057 | * SEALING | |
2058 | * Sealing allows multiple parties to share a shmem-file but restrict | |
2059 | * access to a specific subset of file operations. Seals can only be | |
2060 | * added, but never removed. This way, mutually untrusted parties can | |
2061 | * share common memory regions with a well-defined policy. A malicious | |
2062 | * peer can thus never perform unwanted operations on a shared object. | |
2063 | * | |
2064 | * Seals are only supported on special shmem-files and always affect | |
2065 | * the whole underlying inode. Once a seal is set, it may prevent some | |
2066 | * kinds of access to the file. Currently, the following seals are | |
2067 | * defined: | |
2068 | * SEAL_SEAL: Prevent further seals from being set on this file | |
2069 | * SEAL_SHRINK: Prevent the file from shrinking | |
2070 | * SEAL_GROW: Prevent the file from growing | |
2071 | * SEAL_WRITE: Prevent write access to the file | |
2072 | * | |
2073 | * As we don't require any trust relationship between two parties, we | |
2074 | * must prevent seals from being removed. Therefore, sealing a file | |
2075 | * only adds a given set of seals to the file, it never touches | |
2076 | * existing seals. Furthermore, the "setting seals"-operation can be | |
2077 | * sealed itself, which basically prevents any further seal from being | |
2078 | * added. | |
2079 | * | |
2080 | * Semantics of sealing are only defined on volatile files. Only | |
2081 | * anonymous shmem files support sealing. More importantly, seals are | |
2082 | * never written to disk. Therefore, there's no plan to support it on | |
2083 | * other file types. | |
2084 | */ | |
2085 | ||
2086 | if (file->f_op != &shmem_file_operations) | |
2087 | return -EINVAL; | |
2088 | if (!(file->f_mode & FMODE_WRITE)) | |
2089 | return -EPERM; | |
2090 | if (seals & ~(unsigned int)F_ALL_SEALS) | |
2091 | return -EINVAL; | |
2092 | ||
2093 | inode_lock(inode); | |
2094 | ||
2095 | if (info->seals & F_SEAL_SEAL) { | |
2096 | error = -EPERM; | |
2097 | goto unlock; | |
2098 | } | |
2099 | ||
2100 | if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) { | |
2101 | error = mapping_deny_writable(file->f_mapping); | |
2102 | if (error) | |
2103 | goto unlock; | |
2104 | ||
2105 | error = shmem_wait_for_pins(file->f_mapping); | |
2106 | if (error) { | |
2107 | mapping_allow_writable(file->f_mapping); | |
2108 | goto unlock; | |
2109 | } | |
2110 | } | |
2111 | ||
2112 | info->seals |= seals; | |
2113 | error = 0; | |
2114 | ||
2115 | unlock: | |
2116 | inode_unlock(inode); | |
2117 | return error; | |
2118 | } | |
2119 | EXPORT_SYMBOL_GPL(shmem_add_seals); | |
2120 | ||
2121 | int shmem_get_seals(struct file *file) | |
2122 | { | |
2123 | if (file->f_op != &shmem_file_operations) | |
2124 | return -EINVAL; | |
2125 | ||
2126 | return SHMEM_I(file_inode(file))->seals; | |
2127 | } | |
2128 | EXPORT_SYMBOL_GPL(shmem_get_seals); | |
2129 | ||
2130 | long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg) | |
2131 | { | |
2132 | long error; | |
2133 | ||
2134 | switch (cmd) { | |
2135 | case F_ADD_SEALS: | |
2136 | /* disallow upper 32bit */ | |
2137 | if (arg > UINT_MAX) | |
2138 | return -EINVAL; | |
2139 | ||
2140 | error = shmem_add_seals(file, arg); | |
2141 | break; | |
2142 | case F_GET_SEALS: | |
2143 | error = shmem_get_seals(file); | |
2144 | break; | |
2145 | default: | |
2146 | error = -EINVAL; | |
2147 | break; | |
2148 | } | |
2149 | ||
2150 | return error; | |
2151 | } | |
2152 | ||
2153 | static long shmem_fallocate(struct file *file, int mode, loff_t offset, | |
2154 | loff_t len) | |
2155 | { | |
2156 | struct inode *inode = file_inode(file); | |
2157 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); | |
2158 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2159 | struct shmem_falloc shmem_falloc; | |
2160 | pgoff_t start, index, end; | |
2161 | int error; | |
2162 | ||
2163 | if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) | |
2164 | return -EOPNOTSUPP; | |
2165 | ||
2166 | inode_lock(inode); | |
2167 | ||
2168 | if (mode & FALLOC_FL_PUNCH_HOLE) { | |
2169 | struct address_space *mapping = file->f_mapping; | |
2170 | loff_t unmap_start = round_up(offset, PAGE_SIZE); | |
2171 | loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; | |
2172 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq); | |
2173 | ||
2174 | /* protected by i_mutex */ | |
2175 | if (info->seals & F_SEAL_WRITE) { | |
2176 | error = -EPERM; | |
2177 | goto out; | |
2178 | } | |
2179 | ||
2180 | shmem_falloc.waitq = &shmem_falloc_waitq; | |
2181 | shmem_falloc.start = unmap_start >> PAGE_SHIFT; | |
2182 | shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT; | |
2183 | spin_lock(&inode->i_lock); | |
2184 | inode->i_private = &shmem_falloc; | |
2185 | spin_unlock(&inode->i_lock); | |
2186 | ||
2187 | if ((u64)unmap_end > (u64)unmap_start) | |
2188 | unmap_mapping_range(mapping, unmap_start, | |
2189 | 1 + unmap_end - unmap_start, 0); | |
2190 | shmem_truncate_range(inode, offset, offset + len - 1); | |
2191 | /* No need to unmap again: hole-punching leaves COWed pages */ | |
2192 | ||
2193 | spin_lock(&inode->i_lock); | |
2194 | inode->i_private = NULL; | |
2195 | wake_up_all(&shmem_falloc_waitq); | |
2196 | spin_unlock(&inode->i_lock); | |
2197 | error = 0; | |
2198 | goto out; | |
2199 | } | |
2200 | ||
2201 | /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ | |
2202 | error = inode_newsize_ok(inode, offset + len); | |
2203 | if (error) | |
2204 | goto out; | |
2205 | ||
2206 | if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) { | |
2207 | error = -EPERM; | |
2208 | goto out; | |
2209 | } | |
2210 | ||
2211 | start = offset >> PAGE_CACHE_SHIFT; | |
2212 | end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
2213 | /* Try to avoid a swapstorm if len is impossible to satisfy */ | |
2214 | if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { | |
2215 | error = -ENOSPC; | |
2216 | goto out; | |
2217 | } | |
2218 | ||
2219 | shmem_falloc.waitq = NULL; | |
2220 | shmem_falloc.start = start; | |
2221 | shmem_falloc.next = start; | |
2222 | shmem_falloc.nr_falloced = 0; | |
2223 | shmem_falloc.nr_unswapped = 0; | |
2224 | spin_lock(&inode->i_lock); | |
2225 | inode->i_private = &shmem_falloc; | |
2226 | spin_unlock(&inode->i_lock); | |
2227 | ||
2228 | for (index = start; index < end; index++) { | |
2229 | struct page *page; | |
2230 | ||
2231 | /* | |
2232 | * Good, the fallocate(2) manpage permits EINTR: we may have | |
2233 | * been interrupted because we are using up too much memory. | |
2234 | */ | |
2235 | if (signal_pending(current)) | |
2236 | error = -EINTR; | |
2237 | else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) | |
2238 | error = -ENOMEM; | |
2239 | else | |
2240 | error = shmem_getpage(inode, index, &page, SGP_FALLOC, | |
2241 | NULL); | |
2242 | if (error) { | |
2243 | /* Remove the !PageUptodate pages we added */ | |
2244 | shmem_undo_range(inode, | |
2245 | (loff_t)start << PAGE_CACHE_SHIFT, | |
2246 | (loff_t)index << PAGE_CACHE_SHIFT, true); | |
2247 | goto undone; | |
2248 | } | |
2249 | ||
2250 | /* | |
2251 | * Inform shmem_writepage() how far we have reached. | |
2252 | * No need for lock or barrier: we have the page lock. | |
2253 | */ | |
2254 | shmem_falloc.next++; | |
2255 | if (!PageUptodate(page)) | |
2256 | shmem_falloc.nr_falloced++; | |
2257 | ||
2258 | /* | |
2259 | * If !PageUptodate, leave it that way so that freeable pages | |
2260 | * can be recognized if we need to rollback on error later. | |
2261 | * But set_page_dirty so that memory pressure will swap rather | |
2262 | * than free the pages we are allocating (and SGP_CACHE pages | |
2263 | * might still be clean: we now need to mark those dirty too). | |
2264 | */ | |
2265 | set_page_dirty(page); | |
2266 | unlock_page(page); | |
2267 | page_cache_release(page); | |
2268 | cond_resched(); | |
2269 | } | |
2270 | ||
2271 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) | |
2272 | i_size_write(inode, offset + len); | |
2273 | inode->i_ctime = CURRENT_TIME; | |
2274 | undone: | |
2275 | spin_lock(&inode->i_lock); | |
2276 | inode->i_private = NULL; | |
2277 | spin_unlock(&inode->i_lock); | |
2278 | out: | |
2279 | inode_unlock(inode); | |
2280 | return error; | |
2281 | } | |
2282 | ||
2283 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) | |
2284 | { | |
2285 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); | |
2286 | ||
2287 | buf->f_type = TMPFS_MAGIC; | |
2288 | buf->f_bsize = PAGE_CACHE_SIZE; | |
2289 | buf->f_namelen = NAME_MAX; | |
2290 | if (sbinfo->max_blocks) { | |
2291 | buf->f_blocks = sbinfo->max_blocks; | |
2292 | buf->f_bavail = | |
2293 | buf->f_bfree = sbinfo->max_blocks - | |
2294 | percpu_counter_sum(&sbinfo->used_blocks); | |
2295 | } | |
2296 | if (sbinfo->max_inodes) { | |
2297 | buf->f_files = sbinfo->max_inodes; | |
2298 | buf->f_ffree = sbinfo->free_inodes; | |
2299 | } | |
2300 | /* else leave those fields 0 like simple_statfs */ | |
2301 | return 0; | |
2302 | } | |
2303 | ||
2304 | /* | |
2305 | * File creation. Allocate an inode, and we're done.. | |
2306 | */ | |
2307 | static int | |
2308 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) | |
2309 | { | |
2310 | struct inode *inode; | |
2311 | int error = -ENOSPC; | |
2312 | ||
2313 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); | |
2314 | if (inode) { | |
2315 | error = simple_acl_create(dir, inode); | |
2316 | if (error) | |
2317 | goto out_iput; | |
2318 | error = security_inode_init_security(inode, dir, | |
2319 | &dentry->d_name, | |
2320 | shmem_initxattrs, NULL); | |
2321 | if (error && error != -EOPNOTSUPP) | |
2322 | goto out_iput; | |
2323 | ||
2324 | error = 0; | |
2325 | dir->i_size += BOGO_DIRENT_SIZE; | |
2326 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2327 | d_instantiate(dentry, inode); | |
2328 | dget(dentry); /* Extra count - pin the dentry in core */ | |
2329 | } | |
2330 | return error; | |
2331 | out_iput: | |
2332 | iput(inode); | |
2333 | return error; | |
2334 | } | |
2335 | ||
2336 | static int | |
2337 | shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) | |
2338 | { | |
2339 | struct inode *inode; | |
2340 | int error = -ENOSPC; | |
2341 | ||
2342 | inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); | |
2343 | if (inode) { | |
2344 | error = security_inode_init_security(inode, dir, | |
2345 | NULL, | |
2346 | shmem_initxattrs, NULL); | |
2347 | if (error && error != -EOPNOTSUPP) | |
2348 | goto out_iput; | |
2349 | error = simple_acl_create(dir, inode); | |
2350 | if (error) | |
2351 | goto out_iput; | |
2352 | d_tmpfile(dentry, inode); | |
2353 | } | |
2354 | return error; | |
2355 | out_iput: | |
2356 | iput(inode); | |
2357 | return error; | |
2358 | } | |
2359 | ||
2360 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) | |
2361 | { | |
2362 | int error; | |
2363 | ||
2364 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) | |
2365 | return error; | |
2366 | inc_nlink(dir); | |
2367 | return 0; | |
2368 | } | |
2369 | ||
2370 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, | |
2371 | bool excl) | |
2372 | { | |
2373 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); | |
2374 | } | |
2375 | ||
2376 | /* | |
2377 | * Link a file.. | |
2378 | */ | |
2379 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) | |
2380 | { | |
2381 | struct inode *inode = d_inode(old_dentry); | |
2382 | int ret; | |
2383 | ||
2384 | /* | |
2385 | * No ordinary (disk based) filesystem counts links as inodes; | |
2386 | * but each new link needs a new dentry, pinning lowmem, and | |
2387 | * tmpfs dentries cannot be pruned until they are unlinked. | |
2388 | */ | |
2389 | ret = shmem_reserve_inode(inode->i_sb); | |
2390 | if (ret) | |
2391 | goto out; | |
2392 | ||
2393 | dir->i_size += BOGO_DIRENT_SIZE; | |
2394 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2395 | inc_nlink(inode); | |
2396 | ihold(inode); /* New dentry reference */ | |
2397 | dget(dentry); /* Extra pinning count for the created dentry */ | |
2398 | d_instantiate(dentry, inode); | |
2399 | out: | |
2400 | return ret; | |
2401 | } | |
2402 | ||
2403 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) | |
2404 | { | |
2405 | struct inode *inode = d_inode(dentry); | |
2406 | ||
2407 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) | |
2408 | shmem_free_inode(inode->i_sb); | |
2409 | ||
2410 | dir->i_size -= BOGO_DIRENT_SIZE; | |
2411 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2412 | drop_nlink(inode); | |
2413 | dput(dentry); /* Undo the count from "create" - this does all the work */ | |
2414 | return 0; | |
2415 | } | |
2416 | ||
2417 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) | |
2418 | { | |
2419 | if (!simple_empty(dentry)) | |
2420 | return -ENOTEMPTY; | |
2421 | ||
2422 | drop_nlink(d_inode(dentry)); | |
2423 | drop_nlink(dir); | |
2424 | return shmem_unlink(dir, dentry); | |
2425 | } | |
2426 | ||
2427 | static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) | |
2428 | { | |
2429 | bool old_is_dir = d_is_dir(old_dentry); | |
2430 | bool new_is_dir = d_is_dir(new_dentry); | |
2431 | ||
2432 | if (old_dir != new_dir && old_is_dir != new_is_dir) { | |
2433 | if (old_is_dir) { | |
2434 | drop_nlink(old_dir); | |
2435 | inc_nlink(new_dir); | |
2436 | } else { | |
2437 | drop_nlink(new_dir); | |
2438 | inc_nlink(old_dir); | |
2439 | } | |
2440 | } | |
2441 | old_dir->i_ctime = old_dir->i_mtime = | |
2442 | new_dir->i_ctime = new_dir->i_mtime = | |
2443 | d_inode(old_dentry)->i_ctime = | |
2444 | d_inode(new_dentry)->i_ctime = CURRENT_TIME; | |
2445 | ||
2446 | return 0; | |
2447 | } | |
2448 | ||
2449 | static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry) | |
2450 | { | |
2451 | struct dentry *whiteout; | |
2452 | int error; | |
2453 | ||
2454 | whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name); | |
2455 | if (!whiteout) | |
2456 | return -ENOMEM; | |
2457 | ||
2458 | error = shmem_mknod(old_dir, whiteout, | |
2459 | S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); | |
2460 | dput(whiteout); | |
2461 | if (error) | |
2462 | return error; | |
2463 | ||
2464 | /* | |
2465 | * Cheat and hash the whiteout while the old dentry is still in | |
2466 | * place, instead of playing games with FS_RENAME_DOES_D_MOVE. | |
2467 | * | |
2468 | * d_lookup() will consistently find one of them at this point, | |
2469 | * not sure which one, but that isn't even important. | |
2470 | */ | |
2471 | d_rehash(whiteout); | |
2472 | return 0; | |
2473 | } | |
2474 | ||
2475 | /* | |
2476 | * The VFS layer already does all the dentry stuff for rename, | |
2477 | * we just have to decrement the usage count for the target if | |
2478 | * it exists so that the VFS layer correctly free's it when it | |
2479 | * gets overwritten. | |
2480 | */ | |
2481 | static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags) | |
2482 | { | |
2483 | struct inode *inode = d_inode(old_dentry); | |
2484 | int they_are_dirs = S_ISDIR(inode->i_mode); | |
2485 | ||
2486 | if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) | |
2487 | return -EINVAL; | |
2488 | ||
2489 | if (flags & RENAME_EXCHANGE) | |
2490 | return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry); | |
2491 | ||
2492 | if (!simple_empty(new_dentry)) | |
2493 | return -ENOTEMPTY; | |
2494 | ||
2495 | if (flags & RENAME_WHITEOUT) { | |
2496 | int error; | |
2497 | ||
2498 | error = shmem_whiteout(old_dir, old_dentry); | |
2499 | if (error) | |
2500 | return error; | |
2501 | } | |
2502 | ||
2503 | if (d_really_is_positive(new_dentry)) { | |
2504 | (void) shmem_unlink(new_dir, new_dentry); | |
2505 | if (they_are_dirs) { | |
2506 | drop_nlink(d_inode(new_dentry)); | |
2507 | drop_nlink(old_dir); | |
2508 | } | |
2509 | } else if (they_are_dirs) { | |
2510 | drop_nlink(old_dir); | |
2511 | inc_nlink(new_dir); | |
2512 | } | |
2513 | ||
2514 | old_dir->i_size -= BOGO_DIRENT_SIZE; | |
2515 | new_dir->i_size += BOGO_DIRENT_SIZE; | |
2516 | old_dir->i_ctime = old_dir->i_mtime = | |
2517 | new_dir->i_ctime = new_dir->i_mtime = | |
2518 | inode->i_ctime = CURRENT_TIME; | |
2519 | return 0; | |
2520 | } | |
2521 | ||
2522 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) | |
2523 | { | |
2524 | int error; | |
2525 | int len; | |
2526 | struct inode *inode; | |
2527 | struct page *page; | |
2528 | struct shmem_inode_info *info; | |
2529 | ||
2530 | len = strlen(symname) + 1; | |
2531 | if (len > PAGE_CACHE_SIZE) | |
2532 | return -ENAMETOOLONG; | |
2533 | ||
2534 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); | |
2535 | if (!inode) | |
2536 | return -ENOSPC; | |
2537 | ||
2538 | error = security_inode_init_security(inode, dir, &dentry->d_name, | |
2539 | shmem_initxattrs, NULL); | |
2540 | if (error) { | |
2541 | if (error != -EOPNOTSUPP) { | |
2542 | iput(inode); | |
2543 | return error; | |
2544 | } | |
2545 | error = 0; | |
2546 | } | |
2547 | ||
2548 | info = SHMEM_I(inode); | |
2549 | inode->i_size = len-1; | |
2550 | if (len <= SHORT_SYMLINK_LEN) { | |
2551 | inode->i_link = kmemdup(symname, len, GFP_KERNEL); | |
2552 | if (!inode->i_link) { | |
2553 | iput(inode); | |
2554 | return -ENOMEM; | |
2555 | } | |
2556 | inode->i_op = &shmem_short_symlink_operations; | |
2557 | } else { | |
2558 | inode_nohighmem(inode); | |
2559 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); | |
2560 | if (error) { | |
2561 | iput(inode); | |
2562 | return error; | |
2563 | } | |
2564 | inode->i_mapping->a_ops = &shmem_aops; | |
2565 | inode->i_op = &shmem_symlink_inode_operations; | |
2566 | memcpy(page_address(page), symname, len); | |
2567 | SetPageUptodate(page); | |
2568 | set_page_dirty(page); | |
2569 | unlock_page(page); | |
2570 | page_cache_release(page); | |
2571 | } | |
2572 | dir->i_size += BOGO_DIRENT_SIZE; | |
2573 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; | |
2574 | d_instantiate(dentry, inode); | |
2575 | dget(dentry); | |
2576 | return 0; | |
2577 | } | |
2578 | ||
2579 | static void shmem_put_link(void *arg) | |
2580 | { | |
2581 | mark_page_accessed(arg); | |
2582 | put_page(arg); | |
2583 | } | |
2584 | ||
2585 | static const char *shmem_get_link(struct dentry *dentry, | |
2586 | struct inode *inode, | |
2587 | struct delayed_call *done) | |
2588 | { | |
2589 | struct page *page = NULL; | |
2590 | int error; | |
2591 | if (!dentry) { | |
2592 | page = find_get_page(inode->i_mapping, 0); | |
2593 | if (!page) | |
2594 | return ERR_PTR(-ECHILD); | |
2595 | if (!PageUptodate(page)) { | |
2596 | put_page(page); | |
2597 | return ERR_PTR(-ECHILD); | |
2598 | } | |
2599 | } else { | |
2600 | error = shmem_getpage(inode, 0, &page, SGP_READ, NULL); | |
2601 | if (error) | |
2602 | return ERR_PTR(error); | |
2603 | unlock_page(page); | |
2604 | } | |
2605 | set_delayed_call(done, shmem_put_link, page); | |
2606 | return page_address(page); | |
2607 | } | |
2608 | ||
2609 | #ifdef CONFIG_TMPFS_XATTR | |
2610 | /* | |
2611 | * Superblocks without xattr inode operations may get some security.* xattr | |
2612 | * support from the LSM "for free". As soon as we have any other xattrs | |
2613 | * like ACLs, we also need to implement the security.* handlers at | |
2614 | * filesystem level, though. | |
2615 | */ | |
2616 | ||
2617 | /* | |
2618 | * Callback for security_inode_init_security() for acquiring xattrs. | |
2619 | */ | |
2620 | static int shmem_initxattrs(struct inode *inode, | |
2621 | const struct xattr *xattr_array, | |
2622 | void *fs_info) | |
2623 | { | |
2624 | struct shmem_inode_info *info = SHMEM_I(inode); | |
2625 | const struct xattr *xattr; | |
2626 | struct simple_xattr *new_xattr; | |
2627 | size_t len; | |
2628 | ||
2629 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { | |
2630 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); | |
2631 | if (!new_xattr) | |
2632 | return -ENOMEM; | |
2633 | ||
2634 | len = strlen(xattr->name) + 1; | |
2635 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, | |
2636 | GFP_KERNEL); | |
2637 | if (!new_xattr->name) { | |
2638 | kfree(new_xattr); | |
2639 | return -ENOMEM; | |
2640 | } | |
2641 | ||
2642 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, | |
2643 | XATTR_SECURITY_PREFIX_LEN); | |
2644 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, | |
2645 | xattr->name, len); | |
2646 | ||
2647 | simple_xattr_list_add(&info->xattrs, new_xattr); | |
2648 | } | |
2649 | ||
2650 | return 0; | |
2651 | } | |
2652 | ||
2653 | static int shmem_xattr_handler_get(const struct xattr_handler *handler, | |
2654 | struct dentry *dentry, const char *name, | |
2655 | void *buffer, size_t size) | |
2656 | { | |
2657 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2658 | ||
2659 | name = xattr_full_name(handler, name); | |
2660 | return simple_xattr_get(&info->xattrs, name, buffer, size); | |
2661 | } | |
2662 | ||
2663 | static int shmem_xattr_handler_set(const struct xattr_handler *handler, | |
2664 | struct dentry *dentry, const char *name, | |
2665 | const void *value, size_t size, int flags) | |
2666 | { | |
2667 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2668 | ||
2669 | name = xattr_full_name(handler, name); | |
2670 | return simple_xattr_set(&info->xattrs, name, value, size, flags); | |
2671 | } | |
2672 | ||
2673 | static const struct xattr_handler shmem_security_xattr_handler = { | |
2674 | .prefix = XATTR_SECURITY_PREFIX, | |
2675 | .get = shmem_xattr_handler_get, | |
2676 | .set = shmem_xattr_handler_set, | |
2677 | }; | |
2678 | ||
2679 | static const struct xattr_handler shmem_trusted_xattr_handler = { | |
2680 | .prefix = XATTR_TRUSTED_PREFIX, | |
2681 | .get = shmem_xattr_handler_get, | |
2682 | .set = shmem_xattr_handler_set, | |
2683 | }; | |
2684 | ||
2685 | static const struct xattr_handler *shmem_xattr_handlers[] = { | |
2686 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
2687 | &posix_acl_access_xattr_handler, | |
2688 | &posix_acl_default_xattr_handler, | |
2689 | #endif | |
2690 | &shmem_security_xattr_handler, | |
2691 | &shmem_trusted_xattr_handler, | |
2692 | NULL | |
2693 | }; | |
2694 | ||
2695 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) | |
2696 | { | |
2697 | struct shmem_inode_info *info = SHMEM_I(d_inode(dentry)); | |
2698 | return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size); | |
2699 | } | |
2700 | #endif /* CONFIG_TMPFS_XATTR */ | |
2701 | ||
2702 | static const struct inode_operations shmem_short_symlink_operations = { | |
2703 | .readlink = generic_readlink, | |
2704 | .get_link = simple_get_link, | |
2705 | #ifdef CONFIG_TMPFS_XATTR | |
2706 | .setxattr = generic_setxattr, | |
2707 | .getxattr = generic_getxattr, | |
2708 | .listxattr = shmem_listxattr, | |
2709 | .removexattr = generic_removexattr, | |
2710 | #endif | |
2711 | }; | |
2712 | ||
2713 | static const struct inode_operations shmem_symlink_inode_operations = { | |
2714 | .readlink = generic_readlink, | |
2715 | .get_link = shmem_get_link, | |
2716 | #ifdef CONFIG_TMPFS_XATTR | |
2717 | .setxattr = generic_setxattr, | |
2718 | .getxattr = generic_getxattr, | |
2719 | .listxattr = shmem_listxattr, | |
2720 | .removexattr = generic_removexattr, | |
2721 | #endif | |
2722 | }; | |
2723 | ||
2724 | static struct dentry *shmem_get_parent(struct dentry *child) | |
2725 | { | |
2726 | return ERR_PTR(-ESTALE); | |
2727 | } | |
2728 | ||
2729 | static int shmem_match(struct inode *ino, void *vfh) | |
2730 | { | |
2731 | __u32 *fh = vfh; | |
2732 | __u64 inum = fh[2]; | |
2733 | inum = (inum << 32) | fh[1]; | |
2734 | return ino->i_ino == inum && fh[0] == ino->i_generation; | |
2735 | } | |
2736 | ||
2737 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, | |
2738 | struct fid *fid, int fh_len, int fh_type) | |
2739 | { | |
2740 | struct inode *inode; | |
2741 | struct dentry *dentry = NULL; | |
2742 | u64 inum; | |
2743 | ||
2744 | if (fh_len < 3) | |
2745 | return NULL; | |
2746 | ||
2747 | inum = fid->raw[2]; | |
2748 | inum = (inum << 32) | fid->raw[1]; | |
2749 | ||
2750 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), | |
2751 | shmem_match, fid->raw); | |
2752 | if (inode) { | |
2753 | dentry = d_find_alias(inode); | |
2754 | iput(inode); | |
2755 | } | |
2756 | ||
2757 | return dentry; | |
2758 | } | |
2759 | ||
2760 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, | |
2761 | struct inode *parent) | |
2762 | { | |
2763 | if (*len < 3) { | |
2764 | *len = 3; | |
2765 | return FILEID_INVALID; | |
2766 | } | |
2767 | ||
2768 | if (inode_unhashed(inode)) { | |
2769 | /* Unfortunately insert_inode_hash is not idempotent, | |
2770 | * so as we hash inodes here rather than at creation | |
2771 | * time, we need a lock to ensure we only try | |
2772 | * to do it once | |
2773 | */ | |
2774 | static DEFINE_SPINLOCK(lock); | |
2775 | spin_lock(&lock); | |
2776 | if (inode_unhashed(inode)) | |
2777 | __insert_inode_hash(inode, | |
2778 | inode->i_ino + inode->i_generation); | |
2779 | spin_unlock(&lock); | |
2780 | } | |
2781 | ||
2782 | fh[0] = inode->i_generation; | |
2783 | fh[1] = inode->i_ino; | |
2784 | fh[2] = ((__u64)inode->i_ino) >> 32; | |
2785 | ||
2786 | *len = 3; | |
2787 | return 1; | |
2788 | } | |
2789 | ||
2790 | static const struct export_operations shmem_export_ops = { | |
2791 | .get_parent = shmem_get_parent, | |
2792 | .encode_fh = shmem_encode_fh, | |
2793 | .fh_to_dentry = shmem_fh_to_dentry, | |
2794 | }; | |
2795 | ||
2796 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, | |
2797 | bool remount) | |
2798 | { | |
2799 | char *this_char, *value, *rest; | |
2800 | struct mempolicy *mpol = NULL; | |
2801 | uid_t uid; | |
2802 | gid_t gid; | |
2803 | ||
2804 | while (options != NULL) { | |
2805 | this_char = options; | |
2806 | for (;;) { | |
2807 | /* | |
2808 | * NUL-terminate this option: unfortunately, | |
2809 | * mount options form a comma-separated list, | |
2810 | * but mpol's nodelist may also contain commas. | |
2811 | */ | |
2812 | options = strchr(options, ','); | |
2813 | if (options == NULL) | |
2814 | break; | |
2815 | options++; | |
2816 | if (!isdigit(*options)) { | |
2817 | options[-1] = '\0'; | |
2818 | break; | |
2819 | } | |
2820 | } | |
2821 | if (!*this_char) | |
2822 | continue; | |
2823 | if ((value = strchr(this_char,'=')) != NULL) { | |
2824 | *value++ = 0; | |
2825 | } else { | |
2826 | printk(KERN_ERR | |
2827 | "tmpfs: No value for mount option '%s'\n", | |
2828 | this_char); | |
2829 | goto error; | |
2830 | } | |
2831 | ||
2832 | if (!strcmp(this_char,"size")) { | |
2833 | unsigned long long size; | |
2834 | size = memparse(value,&rest); | |
2835 | if (*rest == '%') { | |
2836 | size <<= PAGE_SHIFT; | |
2837 | size *= totalram_pages; | |
2838 | do_div(size, 100); | |
2839 | rest++; | |
2840 | } | |
2841 | if (*rest) | |
2842 | goto bad_val; | |
2843 | sbinfo->max_blocks = | |
2844 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); | |
2845 | } else if (!strcmp(this_char,"nr_blocks")) { | |
2846 | sbinfo->max_blocks = memparse(value, &rest); | |
2847 | if (*rest) | |
2848 | goto bad_val; | |
2849 | } else if (!strcmp(this_char,"nr_inodes")) { | |
2850 | sbinfo->max_inodes = memparse(value, &rest); | |
2851 | if (*rest) | |
2852 | goto bad_val; | |
2853 | } else if (!strcmp(this_char,"mode")) { | |
2854 | if (remount) | |
2855 | continue; | |
2856 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; | |
2857 | if (*rest) | |
2858 | goto bad_val; | |
2859 | } else if (!strcmp(this_char,"uid")) { | |
2860 | if (remount) | |
2861 | continue; | |
2862 | uid = simple_strtoul(value, &rest, 0); | |
2863 | if (*rest) | |
2864 | goto bad_val; | |
2865 | sbinfo->uid = make_kuid(current_user_ns(), uid); | |
2866 | if (!uid_valid(sbinfo->uid)) | |
2867 | goto bad_val; | |
2868 | } else if (!strcmp(this_char,"gid")) { | |
2869 | if (remount) | |
2870 | continue; | |
2871 | gid = simple_strtoul(value, &rest, 0); | |
2872 | if (*rest) | |
2873 | goto bad_val; | |
2874 | sbinfo->gid = make_kgid(current_user_ns(), gid); | |
2875 | if (!gid_valid(sbinfo->gid)) | |
2876 | goto bad_val; | |
2877 | } else if (!strcmp(this_char,"mpol")) { | |
2878 | mpol_put(mpol); | |
2879 | mpol = NULL; | |
2880 | if (mpol_parse_str(value, &mpol)) | |
2881 | goto bad_val; | |
2882 | } else { | |
2883 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", | |
2884 | this_char); | |
2885 | goto error; | |
2886 | } | |
2887 | } | |
2888 | sbinfo->mpol = mpol; | |
2889 | return 0; | |
2890 | ||
2891 | bad_val: | |
2892 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", | |
2893 | value, this_char); | |
2894 | error: | |
2895 | mpol_put(mpol); | |
2896 | return 1; | |
2897 | ||
2898 | } | |
2899 | ||
2900 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) | |
2901 | { | |
2902 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
2903 | struct shmem_sb_info config = *sbinfo; | |
2904 | unsigned long inodes; | |
2905 | int error = -EINVAL; | |
2906 | ||
2907 | config.mpol = NULL; | |
2908 | if (shmem_parse_options(data, &config, true)) | |
2909 | return error; | |
2910 | ||
2911 | spin_lock(&sbinfo->stat_lock); | |
2912 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; | |
2913 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) | |
2914 | goto out; | |
2915 | if (config.max_inodes < inodes) | |
2916 | goto out; | |
2917 | /* | |
2918 | * Those tests disallow limited->unlimited while any are in use; | |
2919 | * but we must separately disallow unlimited->limited, because | |
2920 | * in that case we have no record of how much is already in use. | |
2921 | */ | |
2922 | if (config.max_blocks && !sbinfo->max_blocks) | |
2923 | goto out; | |
2924 | if (config.max_inodes && !sbinfo->max_inodes) | |
2925 | goto out; | |
2926 | ||
2927 | error = 0; | |
2928 | sbinfo->max_blocks = config.max_blocks; | |
2929 | sbinfo->max_inodes = config.max_inodes; | |
2930 | sbinfo->free_inodes = config.max_inodes - inodes; | |
2931 | ||
2932 | /* | |
2933 | * Preserve previous mempolicy unless mpol remount option was specified. | |
2934 | */ | |
2935 | if (config.mpol) { | |
2936 | mpol_put(sbinfo->mpol); | |
2937 | sbinfo->mpol = config.mpol; /* transfers initial ref */ | |
2938 | } | |
2939 | out: | |
2940 | spin_unlock(&sbinfo->stat_lock); | |
2941 | return error; | |
2942 | } | |
2943 | ||
2944 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) | |
2945 | { | |
2946 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); | |
2947 | ||
2948 | if (sbinfo->max_blocks != shmem_default_max_blocks()) | |
2949 | seq_printf(seq, ",size=%luk", | |
2950 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); | |
2951 | if (sbinfo->max_inodes != shmem_default_max_inodes()) | |
2952 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); | |
2953 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) | |
2954 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); | |
2955 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) | |
2956 | seq_printf(seq, ",uid=%u", | |
2957 | from_kuid_munged(&init_user_ns, sbinfo->uid)); | |
2958 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) | |
2959 | seq_printf(seq, ",gid=%u", | |
2960 | from_kgid_munged(&init_user_ns, sbinfo->gid)); | |
2961 | shmem_show_mpol(seq, sbinfo->mpol); | |
2962 | return 0; | |
2963 | } | |
2964 | ||
2965 | #define MFD_NAME_PREFIX "memfd:" | |
2966 | #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1) | |
2967 | #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN) | |
2968 | ||
2969 | #define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING) | |
2970 | ||
2971 | SYSCALL_DEFINE2(memfd_create, | |
2972 | const char __user *, uname, | |
2973 | unsigned int, flags) | |
2974 | { | |
2975 | struct shmem_inode_info *info; | |
2976 | struct file *file; | |
2977 | int fd, error; | |
2978 | char *name; | |
2979 | long len; | |
2980 | ||
2981 | if (flags & ~(unsigned int)MFD_ALL_FLAGS) | |
2982 | return -EINVAL; | |
2983 | ||
2984 | /* length includes terminating zero */ | |
2985 | len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1); | |
2986 | if (len <= 0) | |
2987 | return -EFAULT; | |
2988 | if (len > MFD_NAME_MAX_LEN + 1) | |
2989 | return -EINVAL; | |
2990 | ||
2991 | name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY); | |
2992 | if (!name) | |
2993 | return -ENOMEM; | |
2994 | ||
2995 | strcpy(name, MFD_NAME_PREFIX); | |
2996 | if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) { | |
2997 | error = -EFAULT; | |
2998 | goto err_name; | |
2999 | } | |
3000 | ||
3001 | /* terminating-zero may have changed after strnlen_user() returned */ | |
3002 | if (name[len + MFD_NAME_PREFIX_LEN - 1]) { | |
3003 | error = -EFAULT; | |
3004 | goto err_name; | |
3005 | } | |
3006 | ||
3007 | fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0); | |
3008 | if (fd < 0) { | |
3009 | error = fd; | |
3010 | goto err_name; | |
3011 | } | |
3012 | ||
3013 | file = shmem_file_setup(name, 0, VM_NORESERVE); | |
3014 | if (IS_ERR(file)) { | |
3015 | error = PTR_ERR(file); | |
3016 | goto err_fd; | |
3017 | } | |
3018 | info = SHMEM_I(file_inode(file)); | |
3019 | file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE; | |
3020 | file->f_flags |= O_RDWR | O_LARGEFILE; | |
3021 | if (flags & MFD_ALLOW_SEALING) | |
3022 | info->seals &= ~F_SEAL_SEAL; | |
3023 | ||
3024 | fd_install(fd, file); | |
3025 | kfree(name); | |
3026 | return fd; | |
3027 | ||
3028 | err_fd: | |
3029 | put_unused_fd(fd); | |
3030 | err_name: | |
3031 | kfree(name); | |
3032 | return error; | |
3033 | } | |
3034 | ||
3035 | #endif /* CONFIG_TMPFS */ | |
3036 | ||
3037 | static void shmem_put_super(struct super_block *sb) | |
3038 | { | |
3039 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); | |
3040 | ||
3041 | percpu_counter_destroy(&sbinfo->used_blocks); | |
3042 | mpol_put(sbinfo->mpol); | |
3043 | kfree(sbinfo); | |
3044 | sb->s_fs_info = NULL; | |
3045 | } | |
3046 | ||
3047 | int shmem_fill_super(struct super_block *sb, void *data, int silent) | |
3048 | { | |
3049 | struct inode *inode; | |
3050 | struct shmem_sb_info *sbinfo; | |
3051 | int err = -ENOMEM; | |
3052 | ||
3053 | /* Round up to L1_CACHE_BYTES to resist false sharing */ | |
3054 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), | |
3055 | L1_CACHE_BYTES), GFP_KERNEL); | |
3056 | if (!sbinfo) | |
3057 | return -ENOMEM; | |
3058 | ||
3059 | sbinfo->mode = S_IRWXUGO | S_ISVTX; | |
3060 | sbinfo->uid = current_fsuid(); | |
3061 | sbinfo->gid = current_fsgid(); | |
3062 | sb->s_fs_info = sbinfo; | |
3063 | ||
3064 | #ifdef CONFIG_TMPFS | |
3065 | /* | |
3066 | * Per default we only allow half of the physical ram per | |
3067 | * tmpfs instance, limiting inodes to one per page of lowmem; | |
3068 | * but the internal instance is left unlimited. | |
3069 | */ | |
3070 | if (!(sb->s_flags & MS_KERNMOUNT)) { | |
3071 | sbinfo->max_blocks = shmem_default_max_blocks(); | |
3072 | sbinfo->max_inodes = shmem_default_max_inodes(); | |
3073 | if (shmem_parse_options(data, sbinfo, false)) { | |
3074 | err = -EINVAL; | |
3075 | goto failed; | |
3076 | } | |
3077 | } else { | |
3078 | sb->s_flags |= MS_NOUSER; | |
3079 | } | |
3080 | sb->s_export_op = &shmem_export_ops; | |
3081 | sb->s_flags |= MS_NOSEC; | |
3082 | #else | |
3083 | sb->s_flags |= MS_NOUSER; | |
3084 | #endif | |
3085 | ||
3086 | spin_lock_init(&sbinfo->stat_lock); | |
3087 | if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL)) | |
3088 | goto failed; | |
3089 | sbinfo->free_inodes = sbinfo->max_inodes; | |
3090 | ||
3091 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
3092 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
3093 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
3094 | sb->s_magic = TMPFS_MAGIC; | |
3095 | sb->s_op = &shmem_ops; | |
3096 | sb->s_time_gran = 1; | |
3097 | #ifdef CONFIG_TMPFS_XATTR | |
3098 | sb->s_xattr = shmem_xattr_handlers; | |
3099 | #endif | |
3100 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3101 | sb->s_flags |= MS_POSIXACL; | |
3102 | #endif | |
3103 | ||
3104 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); | |
3105 | if (!inode) | |
3106 | goto failed; | |
3107 | inode->i_uid = sbinfo->uid; | |
3108 | inode->i_gid = sbinfo->gid; | |
3109 | sb->s_root = d_make_root(inode); | |
3110 | if (!sb->s_root) | |
3111 | goto failed; | |
3112 | return 0; | |
3113 | ||
3114 | failed: | |
3115 | shmem_put_super(sb); | |
3116 | return err; | |
3117 | } | |
3118 | ||
3119 | static struct kmem_cache *shmem_inode_cachep; | |
3120 | ||
3121 | static struct inode *shmem_alloc_inode(struct super_block *sb) | |
3122 | { | |
3123 | struct shmem_inode_info *info; | |
3124 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); | |
3125 | if (!info) | |
3126 | return NULL; | |
3127 | return &info->vfs_inode; | |
3128 | } | |
3129 | ||
3130 | static void shmem_destroy_callback(struct rcu_head *head) | |
3131 | { | |
3132 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
3133 | kfree(inode->i_link); | |
3134 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); | |
3135 | } | |
3136 | ||
3137 | static void shmem_destroy_inode(struct inode *inode) | |
3138 | { | |
3139 | if (S_ISREG(inode->i_mode)) | |
3140 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); | |
3141 | call_rcu(&inode->i_rcu, shmem_destroy_callback); | |
3142 | } | |
3143 | ||
3144 | static void shmem_init_inode(void *foo) | |
3145 | { | |
3146 | struct shmem_inode_info *info = foo; | |
3147 | inode_init_once(&info->vfs_inode); | |
3148 | } | |
3149 | ||
3150 | static int shmem_init_inodecache(void) | |
3151 | { | |
3152 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", | |
3153 | sizeof(struct shmem_inode_info), | |
3154 | 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode); | |
3155 | return 0; | |
3156 | } | |
3157 | ||
3158 | static void shmem_destroy_inodecache(void) | |
3159 | { | |
3160 | kmem_cache_destroy(shmem_inode_cachep); | |
3161 | } | |
3162 | ||
3163 | static const struct address_space_operations shmem_aops = { | |
3164 | .writepage = shmem_writepage, | |
3165 | .set_page_dirty = __set_page_dirty_no_writeback, | |
3166 | #ifdef CONFIG_TMPFS | |
3167 | .write_begin = shmem_write_begin, | |
3168 | .write_end = shmem_write_end, | |
3169 | #endif | |
3170 | #ifdef CONFIG_MIGRATION | |
3171 | .migratepage = migrate_page, | |
3172 | #endif | |
3173 | .error_remove_page = generic_error_remove_page, | |
3174 | }; | |
3175 | ||
3176 | static const struct file_operations shmem_file_operations = { | |
3177 | .mmap = shmem_mmap, | |
3178 | #ifdef CONFIG_TMPFS | |
3179 | .llseek = shmem_file_llseek, | |
3180 | .read_iter = shmem_file_read_iter, | |
3181 | .write_iter = generic_file_write_iter, | |
3182 | .fsync = noop_fsync, | |
3183 | .splice_read = shmem_file_splice_read, | |
3184 | .splice_write = iter_file_splice_write, | |
3185 | .fallocate = shmem_fallocate, | |
3186 | #endif | |
3187 | }; | |
3188 | ||
3189 | static const struct inode_operations shmem_inode_operations = { | |
3190 | .getattr = shmem_getattr, | |
3191 | .setattr = shmem_setattr, | |
3192 | #ifdef CONFIG_TMPFS_XATTR | |
3193 | .setxattr = generic_setxattr, | |
3194 | .getxattr = generic_getxattr, | |
3195 | .listxattr = shmem_listxattr, | |
3196 | .removexattr = generic_removexattr, | |
3197 | .set_acl = simple_set_acl, | |
3198 | #endif | |
3199 | }; | |
3200 | ||
3201 | static const struct inode_operations shmem_dir_inode_operations = { | |
3202 | #ifdef CONFIG_TMPFS | |
3203 | .create = shmem_create, | |
3204 | .lookup = simple_lookup, | |
3205 | .link = shmem_link, | |
3206 | .unlink = shmem_unlink, | |
3207 | .symlink = shmem_symlink, | |
3208 | .mkdir = shmem_mkdir, | |
3209 | .rmdir = shmem_rmdir, | |
3210 | .mknod = shmem_mknod, | |
3211 | .rename2 = shmem_rename2, | |
3212 | .tmpfile = shmem_tmpfile, | |
3213 | #endif | |
3214 | #ifdef CONFIG_TMPFS_XATTR | |
3215 | .setxattr = generic_setxattr, | |
3216 | .getxattr = generic_getxattr, | |
3217 | .listxattr = shmem_listxattr, | |
3218 | .removexattr = generic_removexattr, | |
3219 | #endif | |
3220 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3221 | .setattr = shmem_setattr, | |
3222 | .set_acl = simple_set_acl, | |
3223 | #endif | |
3224 | }; | |
3225 | ||
3226 | static const struct inode_operations shmem_special_inode_operations = { | |
3227 | #ifdef CONFIG_TMPFS_XATTR | |
3228 | .setxattr = generic_setxattr, | |
3229 | .getxattr = generic_getxattr, | |
3230 | .listxattr = shmem_listxattr, | |
3231 | .removexattr = generic_removexattr, | |
3232 | #endif | |
3233 | #ifdef CONFIG_TMPFS_POSIX_ACL | |
3234 | .setattr = shmem_setattr, | |
3235 | .set_acl = simple_set_acl, | |
3236 | #endif | |
3237 | }; | |
3238 | ||
3239 | static const struct super_operations shmem_ops = { | |
3240 | .alloc_inode = shmem_alloc_inode, | |
3241 | .destroy_inode = shmem_destroy_inode, | |
3242 | #ifdef CONFIG_TMPFS | |
3243 | .statfs = shmem_statfs, | |
3244 | .remount_fs = shmem_remount_fs, | |
3245 | .show_options = shmem_show_options, | |
3246 | #endif | |
3247 | .evict_inode = shmem_evict_inode, | |
3248 | .drop_inode = generic_delete_inode, | |
3249 | .put_super = shmem_put_super, | |
3250 | }; | |
3251 | ||
3252 | static const struct vm_operations_struct shmem_vm_ops = { | |
3253 | .fault = shmem_fault, | |
3254 | .map_pages = filemap_map_pages, | |
3255 | #ifdef CONFIG_NUMA | |
3256 | .set_policy = shmem_set_policy, | |
3257 | .get_policy = shmem_get_policy, | |
3258 | #endif | |
3259 | }; | |
3260 | ||
3261 | static struct dentry *shmem_mount(struct file_system_type *fs_type, | |
3262 | int flags, const char *dev_name, void *data) | |
3263 | { | |
3264 | return mount_nodev(fs_type, flags, data, shmem_fill_super); | |
3265 | } | |
3266 | ||
3267 | static struct file_system_type shmem_fs_type = { | |
3268 | .owner = THIS_MODULE, | |
3269 | .name = "tmpfs", | |
3270 | .mount = shmem_mount, | |
3271 | .kill_sb = kill_litter_super, | |
3272 | .fs_flags = FS_USERNS_MOUNT, | |
3273 | }; | |
3274 | ||
3275 | int __init shmem_init(void) | |
3276 | { | |
3277 | int error; | |
3278 | ||
3279 | /* If rootfs called this, don't re-init */ | |
3280 | if (shmem_inode_cachep) | |
3281 | return 0; | |
3282 | ||
3283 | error = shmem_init_inodecache(); | |
3284 | if (error) | |
3285 | goto out3; | |
3286 | ||
3287 | error = register_filesystem(&shmem_fs_type); | |
3288 | if (error) { | |
3289 | printk(KERN_ERR "Could not register tmpfs\n"); | |
3290 | goto out2; | |
3291 | } | |
3292 | ||
3293 | shm_mnt = kern_mount(&shmem_fs_type); | |
3294 | if (IS_ERR(shm_mnt)) { | |
3295 | error = PTR_ERR(shm_mnt); | |
3296 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); | |
3297 | goto out1; | |
3298 | } | |
3299 | return 0; | |
3300 | ||
3301 | out1: | |
3302 | unregister_filesystem(&shmem_fs_type); | |
3303 | out2: | |
3304 | shmem_destroy_inodecache(); | |
3305 | out3: | |
3306 | shm_mnt = ERR_PTR(error); | |
3307 | return error; | |
3308 | } | |
3309 | ||
3310 | #else /* !CONFIG_SHMEM */ | |
3311 | ||
3312 | /* | |
3313 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code | |
3314 | * | |
3315 | * This is intended for small system where the benefits of the full | |
3316 | * shmem code (swap-backed and resource-limited) are outweighed by | |
3317 | * their complexity. On systems without swap this code should be | |
3318 | * effectively equivalent, but much lighter weight. | |
3319 | */ | |
3320 | ||
3321 | static struct file_system_type shmem_fs_type = { | |
3322 | .name = "tmpfs", | |
3323 | .mount = ramfs_mount, | |
3324 | .kill_sb = kill_litter_super, | |
3325 | .fs_flags = FS_USERNS_MOUNT, | |
3326 | }; | |
3327 | ||
3328 | int __init shmem_init(void) | |
3329 | { | |
3330 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); | |
3331 | ||
3332 | shm_mnt = kern_mount(&shmem_fs_type); | |
3333 | BUG_ON(IS_ERR(shm_mnt)); | |
3334 | ||
3335 | return 0; | |
3336 | } | |
3337 | ||
3338 | int shmem_unuse(swp_entry_t swap, struct page *page) | |
3339 | { | |
3340 | return 0; | |
3341 | } | |
3342 | ||
3343 | int shmem_lock(struct file *file, int lock, struct user_struct *user) | |
3344 | { | |
3345 | return 0; | |
3346 | } | |
3347 | ||
3348 | void shmem_unlock_mapping(struct address_space *mapping) | |
3349 | { | |
3350 | } | |
3351 | ||
3352 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) | |
3353 | { | |
3354 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); | |
3355 | } | |
3356 | EXPORT_SYMBOL_GPL(shmem_truncate_range); | |
3357 | ||
3358 | #define shmem_vm_ops generic_file_vm_ops | |
3359 | #define shmem_file_operations ramfs_file_operations | |
3360 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) | |
3361 | #define shmem_acct_size(flags, size) 0 | |
3362 | #define shmem_unacct_size(flags, size) do {} while (0) | |
3363 | ||
3364 | #endif /* CONFIG_SHMEM */ | |
3365 | ||
3366 | /* common code */ | |
3367 | ||
3368 | static struct dentry_operations anon_ops = { | |
3369 | .d_dname = simple_dname | |
3370 | }; | |
3371 | ||
3372 | static struct file *__shmem_file_setup(const char *name, loff_t size, | |
3373 | unsigned long flags, unsigned int i_flags) | |
3374 | { | |
3375 | struct file *res; | |
3376 | struct inode *inode; | |
3377 | struct path path; | |
3378 | struct super_block *sb; | |
3379 | struct qstr this; | |
3380 | ||
3381 | if (IS_ERR(shm_mnt)) | |
3382 | return ERR_CAST(shm_mnt); | |
3383 | ||
3384 | if (size < 0 || size > MAX_LFS_FILESIZE) | |
3385 | return ERR_PTR(-EINVAL); | |
3386 | ||
3387 | if (shmem_acct_size(flags, size)) | |
3388 | return ERR_PTR(-ENOMEM); | |
3389 | ||
3390 | res = ERR_PTR(-ENOMEM); | |
3391 | this.name = name; | |
3392 | this.len = strlen(name); | |
3393 | this.hash = 0; /* will go */ | |
3394 | sb = shm_mnt->mnt_sb; | |
3395 | path.mnt = mntget(shm_mnt); | |
3396 | path.dentry = d_alloc_pseudo(sb, &this); | |
3397 | if (!path.dentry) | |
3398 | goto put_memory; | |
3399 | d_set_d_op(path.dentry, &anon_ops); | |
3400 | ||
3401 | res = ERR_PTR(-ENOSPC); | |
3402 | inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); | |
3403 | if (!inode) | |
3404 | goto put_memory; | |
3405 | ||
3406 | inode->i_flags |= i_flags; | |
3407 | d_instantiate(path.dentry, inode); | |
3408 | inode->i_size = size; | |
3409 | clear_nlink(inode); /* It is unlinked */ | |
3410 | res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); | |
3411 | if (IS_ERR(res)) | |
3412 | goto put_path; | |
3413 | ||
3414 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, | |
3415 | &shmem_file_operations); | |
3416 | if (IS_ERR(res)) | |
3417 | goto put_path; | |
3418 | ||
3419 | return res; | |
3420 | ||
3421 | put_memory: | |
3422 | shmem_unacct_size(flags, size); | |
3423 | put_path: | |
3424 | path_put(&path); | |
3425 | return res; | |
3426 | } | |
3427 | ||
3428 | /** | |
3429 | * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be | |
3430 | * kernel internal. There will be NO LSM permission checks against the | |
3431 | * underlying inode. So users of this interface must do LSM checks at a | |
3432 | * higher layer. The users are the big_key and shm implementations. LSM | |
3433 | * checks are provided at the key or shm level rather than the inode. | |
3434 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
3435 | * @size: size to be set for the file | |
3436 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
3437 | */ | |
3438 | struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags) | |
3439 | { | |
3440 | return __shmem_file_setup(name, size, flags, S_PRIVATE); | |
3441 | } | |
3442 | ||
3443 | /** | |
3444 | * shmem_file_setup - get an unlinked file living in tmpfs | |
3445 | * @name: name for dentry (to be seen in /proc/<pid>/maps | |
3446 | * @size: size to be set for the file | |
3447 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size | |
3448 | */ | |
3449 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) | |
3450 | { | |
3451 | return __shmem_file_setup(name, size, flags, 0); | |
3452 | } | |
3453 | EXPORT_SYMBOL_GPL(shmem_file_setup); | |
3454 | ||
3455 | /** | |
3456 | * shmem_zero_setup - setup a shared anonymous mapping | |
3457 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff | |
3458 | */ | |
3459 | int shmem_zero_setup(struct vm_area_struct *vma) | |
3460 | { | |
3461 | struct file *file; | |
3462 | loff_t size = vma->vm_end - vma->vm_start; | |
3463 | ||
3464 | /* | |
3465 | * Cloning a new file under mmap_sem leads to a lock ordering conflict | |
3466 | * between XFS directory reading and selinux: since this file is only | |
3467 | * accessible to the user through its mapping, use S_PRIVATE flag to | |
3468 | * bypass file security, in the same way as shmem_kernel_file_setup(). | |
3469 | */ | |
3470 | file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE); | |
3471 | if (IS_ERR(file)) | |
3472 | return PTR_ERR(file); | |
3473 | ||
3474 | if (vma->vm_file) | |
3475 | fput(vma->vm_file); | |
3476 | vma->vm_file = file; | |
3477 | vma->vm_ops = &shmem_vm_ops; | |
3478 | return 0; | |
3479 | } | |
3480 | ||
3481 | /** | |
3482 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. | |
3483 | * @mapping: the page's address_space | |
3484 | * @index: the page index | |
3485 | * @gfp: the page allocator flags to use if allocating | |
3486 | * | |
3487 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", | |
3488 | * with any new page allocations done using the specified allocation flags. | |
3489 | * But read_cache_page_gfp() uses the ->readpage() method: which does not | |
3490 | * suit tmpfs, since it may have pages in swapcache, and needs to find those | |
3491 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. | |
3492 | * | |
3493 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in | |
3494 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. | |
3495 | */ | |
3496 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, | |
3497 | pgoff_t index, gfp_t gfp) | |
3498 | { | |
3499 | #ifdef CONFIG_SHMEM | |
3500 | struct inode *inode = mapping->host; | |
3501 | struct page *page; | |
3502 | int error; | |
3503 | ||
3504 | BUG_ON(mapping->a_ops != &shmem_aops); | |
3505 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); | |
3506 | if (error) | |
3507 | page = ERR_PTR(error); | |
3508 | else | |
3509 | unlock_page(page); | |
3510 | return page; | |
3511 | #else | |
3512 | /* | |
3513 | * The tiny !SHMEM case uses ramfs without swap | |
3514 | */ | |
3515 | return read_cache_page_gfp(mapping, index, gfp); | |
3516 | #endif | |
3517 | } | |
3518 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |