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1 | /* |
2 | * Resizable virtual memory filesystem for Linux. |
3 | * |
4 | * Copyright (C) 2000 Linus Torvalds. |
5 | * 2000 Transmeta Corp. |
6 | * 2000-2001 Christoph Rohland |
7 | * 2000-2001 SAP AG |
8 | * 2002 Red Hat Inc. |
9 | * Copyright (C) 2002-2011 Hugh Dickins. |
10 | * Copyright (C) 2011 Google Inc. |
11 | * Copyright (C) 2002-2005 VERITAS Software Corporation. |
12 | * Copyright (C) 2004 Andi Kleen, SuSE Labs |
13 | * |
14 | * Extended attribute support for tmpfs: |
15 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> |
16 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
17 | * |
18 | * tiny-shmem: |
19 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> |
20 | * |
21 | * This file is released under the GPL. |
22 | */ |
23 | |
24 | #include <linux/fs.h> |
25 | #include <linux/init.h> |
26 | #include <linux/vfs.h> |
27 | #include <linux/mount.h> |
28 | #include <linux/ramfs.h> |
29 | #include <linux/pagemap.h> |
30 | #include <linux/file.h> |
31 | #include <linux/mm.h> |
32 | #include <linux/export.h> |
33 | #include <linux/swap.h> |
34 | #include <linux/aio.h> |
35 | |
36 | static struct vfsmount *shm_mnt; |
37 | |
38 | #ifdef CONFIG_SHMEM |
39 | /* |
40 | * This virtual memory filesystem is heavily based on the ramfs. It |
41 | * extends ramfs by the ability to use swap and honor resource limits |
42 | * which makes it a completely usable filesystem. |
43 | */ |
44 | |
45 | #include <linux/xattr.h> |
46 | #include <linux/exportfs.h> |
47 | #include <linux/posix_acl.h> |
48 | #include <linux/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 | |
70 | #include <asm/uaccess.h> |
71 | #include <asm/pgtable.h> |
72 | |
73 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
74 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
75 | |
76 | /* Pretend that each entry is of this size in directory's i_size */ |
77 | #define BOGO_DIRENT_SIZE 20 |
78 | |
79 | /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ |
80 | #define SHORT_SYMLINK_LEN 128 |
81 | |
82 | /* |
83 | * shmem_fallocate communicates with shmem_fault or shmem_writepage via |
84 | * inode->i_private (with i_mutex making sure that it has only one user at |
85 | * a time): we would prefer not to enlarge the shmem inode just for that. |
86 | */ |
87 | struct shmem_falloc { |
88 | wait_queue_head_t *waitq; /* faults into hole wait for punch to end */ |
89 | pgoff_t start; /* start of range currently being fallocated */ |
90 | pgoff_t next; /* the next page offset to be fallocated */ |
91 | pgoff_t nr_falloced; /* how many new pages have been fallocated */ |
92 | pgoff_t nr_unswapped; /* how often writepage refused to swap out */ |
93 | }; |
94 | |
95 | /* Flag allocation requirements to shmem_getpage */ |
96 | enum sgp_type { |
97 | SGP_READ, /* don't exceed i_size, don't allocate page */ |
98 | SGP_CACHE, /* don't exceed i_size, may allocate page */ |
99 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
100 | SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */ |
101 | SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */ |
102 | }; |
103 | |
104 | #ifdef CONFIG_TMPFS |
105 | static unsigned long shmem_default_max_blocks(void) |
106 | { |
107 | return totalram_pages / 2; |
108 | } |
109 | |
110 | static unsigned long shmem_default_max_inodes(void) |
111 | { |
112 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
113 | } |
114 | #endif |
115 | |
116 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp); |
117 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
118 | struct shmem_inode_info *info, pgoff_t index); |
119 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
120 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); |
121 | |
122 | static inline int shmem_getpage(struct inode *inode, pgoff_t index, |
123 | struct page **pagep, enum sgp_type sgp, int *fault_type) |
124 | { |
125 | return shmem_getpage_gfp(inode, index, pagep, sgp, |
126 | mapping_gfp_mask(inode->i_mapping), fault_type); |
127 | } |
128 | |
129 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
130 | { |
131 | return sb->s_fs_info; |
132 | } |
133 | |
134 | /* |
135 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
136 | * for shared memory and for shared anonymous (/dev/zero) mappings |
137 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
138 | * consistent with the pre-accounting of private mappings ... |
139 | */ |
140 | static inline int shmem_acct_size(unsigned long flags, loff_t size) |
141 | { |
142 | return (flags & VM_NORESERVE) ? |
143 | 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); |
144 | } |
145 | |
146 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
147 | { |
148 | if (!(flags & VM_NORESERVE)) |
149 | vm_unacct_memory(VM_ACCT(size)); |
150 | } |
151 | |
152 | /* |
153 | * ... whereas tmpfs objects are accounted incrementally as |
154 | * pages are allocated, in order to allow huge sparse files. |
155 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
156 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
157 | */ |
158 | static inline int shmem_acct_block(unsigned long flags) |
159 | { |
160 | return (flags & VM_NORESERVE) ? |
161 | security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
162 | } |
163 | |
164 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
165 | { |
166 | if (flags & VM_NORESERVE) |
167 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
168 | } |
169 | |
170 | static const struct super_operations shmem_ops; |
171 | static const struct address_space_operations shmem_aops; |
172 | static const struct file_operations shmem_file_operations; |
173 | static const struct inode_operations shmem_inode_operations; |
174 | static const struct inode_operations shmem_dir_inode_operations; |
175 | static const struct inode_operations shmem_special_inode_operations; |
176 | static const struct vm_operations_struct shmem_vm_ops; |
177 | |
178 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
179 | .ra_pages = 0, /* No readahead */ |
180 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
181 | }; |
182 | |
183 | static LIST_HEAD(shmem_swaplist); |
184 | static DEFINE_MUTEX(shmem_swaplist_mutex); |
185 | |
186 | static int shmem_reserve_inode(struct super_block *sb) |
187 | { |
188 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
189 | if (sbinfo->max_inodes) { |
190 | spin_lock(&sbinfo->stat_lock); |
191 | if (!sbinfo->free_inodes) { |
192 | spin_unlock(&sbinfo->stat_lock); |
193 | return -ENOSPC; |
194 | } |
195 | sbinfo->free_inodes--; |
196 | spin_unlock(&sbinfo->stat_lock); |
197 | } |
198 | return 0; |
199 | } |
200 | |
201 | static void shmem_free_inode(struct super_block *sb) |
202 | { |
203 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
204 | if (sbinfo->max_inodes) { |
205 | spin_lock(&sbinfo->stat_lock); |
206 | sbinfo->free_inodes++; |
207 | spin_unlock(&sbinfo->stat_lock); |
208 | } |
209 | } |
210 | |
211 | /** |
212 | * shmem_recalc_inode - recalculate the block usage of an inode |
213 | * @inode: inode to recalc |
214 | * |
215 | * We have to calculate the free blocks since the mm can drop |
216 | * undirtied hole pages behind our back. |
217 | * |
218 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
219 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
220 | * |
221 | * It has to be called with the spinlock held. |
222 | */ |
223 | static void shmem_recalc_inode(struct inode *inode) |
224 | { |
225 | struct shmem_inode_info *info = SHMEM_I(inode); |
226 | long freed; |
227 | |
228 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
229 | if (freed > 0) { |
230 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
231 | if (sbinfo->max_blocks) |
232 | percpu_counter_add(&sbinfo->used_blocks, -freed); |
233 | info->alloced -= freed; |
234 | inode->i_blocks -= freed * BLOCKS_PER_PAGE; |
235 | shmem_unacct_blocks(info->flags, freed); |
236 | } |
237 | } |
238 | |
239 | /* |
240 | * Replace item expected in radix tree by a new item, while holding tree lock. |
241 | */ |
242 | static int shmem_radix_tree_replace(struct address_space *mapping, |
243 | pgoff_t index, void *expected, void *replacement) |
244 | { |
245 | void **pslot; |
246 | void *item; |
247 | |
248 | VM_BUG_ON(!expected); |
249 | VM_BUG_ON(!replacement); |
250 | pslot = radix_tree_lookup_slot(&mapping->page_tree, index); |
251 | if (!pslot) |
252 | return -ENOENT; |
253 | item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock); |
254 | if (item != expected) |
255 | return -ENOENT; |
256 | radix_tree_replace_slot(pslot, replacement); |
257 | return 0; |
258 | } |
259 | |
260 | /* |
261 | * Sometimes, before we decide whether to proceed or to fail, we must check |
262 | * that an entry was not already brought back from swap by a racing thread. |
263 | * |
264 | * Checking page is not enough: by the time a SwapCache page is locked, it |
265 | * might be reused, and again be SwapCache, using the same swap as before. |
266 | */ |
267 | static bool shmem_confirm_swap(struct address_space *mapping, |
268 | pgoff_t index, swp_entry_t swap) |
269 | { |
270 | void *item; |
271 | |
272 | rcu_read_lock(); |
273 | item = radix_tree_lookup(&mapping->page_tree, index); |
274 | rcu_read_unlock(); |
275 | return item == swp_to_radix_entry(swap); |
276 | } |
277 | |
278 | /* |
279 | * Like add_to_page_cache_locked, but error if expected item has gone. |
280 | */ |
281 | static int shmem_add_to_page_cache(struct page *page, |
282 | struct address_space *mapping, |
283 | pgoff_t index, gfp_t gfp, void *expected) |
284 | { |
285 | int error; |
286 | |
287 | VM_BUG_ON_PAGE(!PageLocked(page), page); |
288 | VM_BUG_ON_PAGE(!PageSwapBacked(page), page); |
289 | |
290 | page_cache_get(page); |
291 | page->mapping = mapping; |
292 | page->index = index; |
293 | |
294 | spin_lock_irq(&mapping->tree_lock); |
295 | if (!expected) |
296 | error = radix_tree_insert(&mapping->page_tree, index, page); |
297 | else |
298 | error = shmem_radix_tree_replace(mapping, index, expected, |
299 | page); |
300 | if (!error) { |
301 | mapping->nrpages++; |
302 | __inc_zone_page_state(page, NR_FILE_PAGES); |
303 | __inc_zone_page_state(page, NR_SHMEM); |
304 | spin_unlock_irq(&mapping->tree_lock); |
305 | } else { |
306 | page->mapping = NULL; |
307 | spin_unlock_irq(&mapping->tree_lock); |
308 | page_cache_release(page); |
309 | } |
310 | return error; |
311 | } |
312 | |
313 | /* |
314 | * Like delete_from_page_cache, but substitutes swap for page. |
315 | */ |
316 | static void shmem_delete_from_page_cache(struct page *page, void *radswap) |
317 | { |
318 | struct address_space *mapping = page->mapping; |
319 | int error; |
320 | |
321 | spin_lock_irq(&mapping->tree_lock); |
322 | error = shmem_radix_tree_replace(mapping, page->index, page, radswap); |
323 | page->mapping = NULL; |
324 | mapping->nrpages--; |
325 | __dec_zone_page_state(page, NR_FILE_PAGES); |
326 | __dec_zone_page_state(page, NR_SHMEM); |
327 | spin_unlock_irq(&mapping->tree_lock); |
328 | page_cache_release(page); |
329 | BUG_ON(error); |
330 | } |
331 | |
332 | /* |
333 | * Remove swap entry from radix tree, free the swap and its page cache. |
334 | */ |
335 | static int shmem_free_swap(struct address_space *mapping, |
336 | pgoff_t index, void *radswap) |
337 | { |
338 | void *old; |
339 | |
340 | spin_lock_irq(&mapping->tree_lock); |
341 | old = radix_tree_delete_item(&mapping->page_tree, index, radswap); |
342 | spin_unlock_irq(&mapping->tree_lock); |
343 | if (old != radswap) |
344 | return -ENOENT; |
345 | free_swap_and_cache(radix_to_swp_entry(radswap)); |
346 | return 0; |
347 | } |
348 | |
349 | /* |
350 | * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. |
351 | */ |
352 | void shmem_unlock_mapping(struct address_space *mapping) |
353 | { |
354 | struct pagevec pvec; |
355 | pgoff_t indices[PAGEVEC_SIZE]; |
356 | pgoff_t index = 0; |
357 | |
358 | pagevec_init(&pvec, 0); |
359 | /* |
360 | * Minor point, but we might as well stop if someone else SHM_LOCKs it. |
361 | */ |
362 | while (!mapping_unevictable(mapping)) { |
363 | /* |
364 | * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it |
365 | * has finished, if it hits a row of PAGEVEC_SIZE swap entries. |
366 | */ |
367 | pvec.nr = find_get_entries(mapping, index, |
368 | PAGEVEC_SIZE, pvec.pages, indices); |
369 | if (!pvec.nr) |
370 | break; |
371 | index = indices[pvec.nr - 1] + 1; |
372 | pagevec_remove_exceptionals(&pvec); |
373 | check_move_unevictable_pages(pvec.pages, pvec.nr); |
374 | pagevec_release(&pvec); |
375 | cond_resched(); |
376 | } |
377 | } |
378 | |
379 | /* |
380 | * Remove range of pages and swap entries from radix tree, and free them. |
381 | * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. |
382 | */ |
383 | static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, |
384 | bool unfalloc) |
385 | { |
386 | struct address_space *mapping = inode->i_mapping; |
387 | struct shmem_inode_info *info = SHMEM_I(inode); |
388 | pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
389 | pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT; |
390 | unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1); |
391 | unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); |
392 | struct pagevec pvec; |
393 | pgoff_t indices[PAGEVEC_SIZE]; |
394 | long nr_swaps_freed = 0; |
395 | pgoff_t index; |
396 | int i; |
397 | |
398 | if (lend == -1) |
399 | end = -1; /* unsigned, so actually very big */ |
400 | |
401 | pagevec_init(&pvec, 0); |
402 | index = start; |
403 | while (index < end) { |
404 | pvec.nr = find_get_entries(mapping, index, |
405 | min(end - index, (pgoff_t)PAGEVEC_SIZE), |
406 | pvec.pages, indices); |
407 | if (!pvec.nr) |
408 | break; |
409 | mem_cgroup_uncharge_start(); |
410 | for (i = 0; i < pagevec_count(&pvec); i++) { |
411 | struct page *page = pvec.pages[i]; |
412 | |
413 | index = indices[i]; |
414 | if (index >= end) |
415 | break; |
416 | |
417 | if (radix_tree_exceptional_entry(page)) { |
418 | if (unfalloc) |
419 | continue; |
420 | nr_swaps_freed += !shmem_free_swap(mapping, |
421 | index, page); |
422 | continue; |
423 | } |
424 | |
425 | if (!trylock_page(page)) |
426 | continue; |
427 | if (!unfalloc || !PageUptodate(page)) { |
428 | if (page->mapping == mapping) { |
429 | VM_BUG_ON_PAGE(PageWriteback(page), page); |
430 | truncate_inode_page(mapping, page); |
431 | } |
432 | } |
433 | unlock_page(page); |
434 | } |
435 | pagevec_remove_exceptionals(&pvec); |
436 | pagevec_release(&pvec); |
437 | mem_cgroup_uncharge_end(); |
438 | cond_resched(); |
439 | index++; |
440 | } |
441 | |
442 | if (partial_start) { |
443 | struct page *page = NULL; |
444 | shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); |
445 | if (page) { |
446 | unsigned int top = PAGE_CACHE_SIZE; |
447 | if (start > end) { |
448 | top = partial_end; |
449 | partial_end = 0; |
450 | } |
451 | zero_user_segment(page, partial_start, top); |
452 | set_page_dirty(page); |
453 | unlock_page(page); |
454 | page_cache_release(page); |
455 | } |
456 | } |
457 | if (partial_end) { |
458 | struct page *page = NULL; |
459 | shmem_getpage(inode, end, &page, SGP_READ, NULL); |
460 | if (page) { |
461 | zero_user_segment(page, 0, partial_end); |
462 | set_page_dirty(page); |
463 | unlock_page(page); |
464 | page_cache_release(page); |
465 | } |
466 | } |
467 | if (start >= end) |
468 | return; |
469 | |
470 | index = start; |
471 | while (index < end) { |
472 | cond_resched(); |
473 | |
474 | pvec.nr = find_get_entries(mapping, index, |
475 | min(end - index, (pgoff_t)PAGEVEC_SIZE), |
476 | pvec.pages, indices); |
477 | if (!pvec.nr) { |
478 | /* If all gone or hole-punch or unfalloc, we're done */ |
479 | if (index == start || end != -1) |
480 | break; |
481 | /* But if truncating, restart to make sure all gone */ |
482 | index = start; |
483 | continue; |
484 | } |
485 | mem_cgroup_uncharge_start(); |
486 | for (i = 0; i < pagevec_count(&pvec); i++) { |
487 | struct page *page = pvec.pages[i]; |
488 | |
489 | index = indices[i]; |
490 | if (index >= end) |
491 | break; |
492 | |
493 | if (radix_tree_exceptional_entry(page)) { |
494 | if (unfalloc) |
495 | continue; |
496 | if (shmem_free_swap(mapping, index, page)) { |
497 | /* Swap was replaced by page: retry */ |
498 | index--; |
499 | break; |
500 | } |
501 | nr_swaps_freed++; |
502 | continue; |
503 | } |
504 | |
505 | lock_page(page); |
506 | if (!unfalloc || !PageUptodate(page)) { |
507 | if (page->mapping == mapping) { |
508 | VM_BUG_ON_PAGE(PageWriteback(page), page); |
509 | truncate_inode_page(mapping, page); |
510 | } else { |
511 | /* Page was replaced by swap: retry */ |
512 | unlock_page(page); |
513 | index--; |
514 | break; |
515 | } |
516 | } |
517 | unlock_page(page); |
518 | } |
519 | pagevec_remove_exceptionals(&pvec); |
520 | pagevec_release(&pvec); |
521 | mem_cgroup_uncharge_end(); |
522 | index++; |
523 | } |
524 | |
525 | spin_lock(&info->lock); |
526 | info->swapped -= nr_swaps_freed; |
527 | shmem_recalc_inode(inode); |
528 | spin_unlock(&info->lock); |
529 | } |
530 | |
531 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
532 | { |
533 | shmem_undo_range(inode, lstart, lend, false); |
534 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
535 | } |
536 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
537 | |
538 | static int shmem_setattr(struct dentry *dentry, struct iattr *attr) |
539 | { |
540 | struct inode *inode = dentry->d_inode; |
541 | int error; |
542 | |
543 | error = inode_change_ok(inode, attr); |
544 | if (error) |
545 | return error; |
546 | |
547 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
548 | loff_t oldsize = inode->i_size; |
549 | loff_t newsize = attr->ia_size; |
550 | |
551 | if (newsize != oldsize) { |
552 | i_size_write(inode, newsize); |
553 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
554 | } |
555 | if (newsize < oldsize) { |
556 | loff_t holebegin = round_up(newsize, PAGE_SIZE); |
557 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
558 | shmem_truncate_range(inode, newsize, (loff_t)-1); |
559 | /* unmap again to remove racily COWed private pages */ |
560 | unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); |
561 | } |
562 | } |
563 | |
564 | setattr_copy(inode, attr); |
565 | if (attr->ia_valid & ATTR_MODE) |
566 | error = posix_acl_chmod(inode, inode->i_mode); |
567 | return error; |
568 | } |
569 | |
570 | static void shmem_evict_inode(struct inode *inode) |
571 | { |
572 | struct shmem_inode_info *info = SHMEM_I(inode); |
573 | |
574 | if (inode->i_mapping->a_ops == &shmem_aops) { |
575 | shmem_unacct_size(info->flags, inode->i_size); |
576 | inode->i_size = 0; |
577 | shmem_truncate_range(inode, 0, (loff_t)-1); |
578 | if (!list_empty(&info->swaplist)) { |
579 | mutex_lock(&shmem_swaplist_mutex); |
580 | list_del_init(&info->swaplist); |
581 | mutex_unlock(&shmem_swaplist_mutex); |
582 | } |
583 | } else |
584 | kfree(info->symlink); |
585 | |
586 | simple_xattrs_free(&info->xattrs); |
587 | WARN_ON(inode->i_blocks); |
588 | shmem_free_inode(inode->i_sb); |
589 | clear_inode(inode); |
590 | } |
591 | |
592 | /* |
593 | * If swap found in inode, free it and move page from swapcache to filecache. |
594 | */ |
595 | static int shmem_unuse_inode(struct shmem_inode_info *info, |
596 | swp_entry_t swap, struct page **pagep) |
597 | { |
598 | struct address_space *mapping = info->vfs_inode.i_mapping; |
599 | void *radswap; |
600 | pgoff_t index; |
601 | gfp_t gfp; |
602 | int error = 0; |
603 | |
604 | radswap = swp_to_radix_entry(swap); |
605 | index = radix_tree_locate_item(&mapping->page_tree, radswap); |
606 | if (index == -1) |
607 | return 0; |
608 | |
609 | /* |
610 | * Move _head_ to start search for next from here. |
611 | * But be careful: shmem_evict_inode checks list_empty without taking |
612 | * mutex, and there's an instant in list_move_tail when info->swaplist |
613 | * would appear empty, if it were the only one on shmem_swaplist. |
614 | */ |
615 | if (shmem_swaplist.next != &info->swaplist) |
616 | list_move_tail(&shmem_swaplist, &info->swaplist); |
617 | |
618 | gfp = mapping_gfp_mask(mapping); |
619 | if (shmem_should_replace_page(*pagep, gfp)) { |
620 | mutex_unlock(&shmem_swaplist_mutex); |
621 | error = shmem_replace_page(pagep, gfp, info, index); |
622 | mutex_lock(&shmem_swaplist_mutex); |
623 | /* |
624 | * We needed to drop mutex to make that restrictive page |
625 | * allocation, but the inode might have been freed while we |
626 | * dropped it: although a racing shmem_evict_inode() cannot |
627 | * complete without emptying the radix_tree, our page lock |
628 | * on this swapcache page is not enough to prevent that - |
629 | * free_swap_and_cache() of our swap entry will only |
630 | * trylock_page(), removing swap from radix_tree whatever. |
631 | * |
632 | * We must not proceed to shmem_add_to_page_cache() if the |
633 | * inode has been freed, but of course we cannot rely on |
634 | * inode or mapping or info to check that. However, we can |
635 | * safely check if our swap entry is still in use (and here |
636 | * it can't have got reused for another page): if it's still |
637 | * in use, then the inode cannot have been freed yet, and we |
638 | * can safely proceed (if it's no longer in use, that tells |
639 | * nothing about the inode, but we don't need to unuse swap). |
640 | */ |
641 | if (!page_swapcount(*pagep)) |
642 | error = -ENOENT; |
643 | } |
644 | |
645 | /* |
646 | * We rely on shmem_swaplist_mutex, not only to protect the swaplist, |
647 | * but also to hold up shmem_evict_inode(): so inode cannot be freed |
648 | * beneath us (pagelock doesn't help until the page is in pagecache). |
649 | */ |
650 | if (!error) |
651 | error = shmem_add_to_page_cache(*pagep, mapping, index, |
652 | GFP_NOWAIT, radswap); |
653 | if (error != -ENOMEM) { |
654 | /* |
655 | * Truncation and eviction use free_swap_and_cache(), which |
656 | * only does trylock page: if we raced, best clean up here. |
657 | */ |
658 | delete_from_swap_cache(*pagep); |
659 | set_page_dirty(*pagep); |
660 | if (!error) { |
661 | spin_lock(&info->lock); |
662 | info->swapped--; |
663 | spin_unlock(&info->lock); |
664 | swap_free(swap); |
665 | } |
666 | error = 1; /* not an error, but entry was found */ |
667 | } |
668 | return error; |
669 | } |
670 | |
671 | /* |
672 | * Search through swapped inodes to find and replace swap by page. |
673 | */ |
674 | int shmem_unuse(swp_entry_t swap, struct page *page) |
675 | { |
676 | struct list_head *this, *next; |
677 | struct shmem_inode_info *info; |
678 | int found = 0; |
679 | int error = 0; |
680 | |
681 | /* |
682 | * There's a faint possibility that swap page was replaced before |
683 | * caller locked it: caller will come back later with the right page. |
684 | */ |
685 | if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val)) |
686 | goto out; |
687 | |
688 | /* |
689 | * Charge page using GFP_KERNEL while we can wait, before taking |
690 | * the shmem_swaplist_mutex which might hold up shmem_writepage(). |
691 | * Charged back to the user (not to caller) when swap account is used. |
692 | */ |
693 | error = mem_cgroup_charge_file(page, current->mm, GFP_KERNEL); |
694 | if (error) |
695 | goto out; |
696 | /* No radix_tree_preload: swap entry keeps a place for page in tree */ |
697 | |
698 | mutex_lock(&shmem_swaplist_mutex); |
699 | list_for_each_safe(this, next, &shmem_swaplist) { |
700 | info = list_entry(this, struct shmem_inode_info, swaplist); |
701 | if (info->swapped) |
702 | found = shmem_unuse_inode(info, swap, &page); |
703 | else |
704 | list_del_init(&info->swaplist); |
705 | cond_resched(); |
706 | if (found) |
707 | break; |
708 | } |
709 | mutex_unlock(&shmem_swaplist_mutex); |
710 | |
711 | if (found < 0) |
712 | error = found; |
713 | out: |
714 | unlock_page(page); |
715 | page_cache_release(page); |
716 | return error; |
717 | } |
718 | |
719 | /* |
720 | * Move the page from the page cache to the swap cache. |
721 | */ |
722 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
723 | { |
724 | struct shmem_inode_info *info; |
725 | struct address_space *mapping; |
726 | struct inode *inode; |
727 | swp_entry_t swap; |
728 | pgoff_t index; |
729 | |
730 | BUG_ON(!PageLocked(page)); |
731 | mapping = page->mapping; |
732 | index = page->index; |
733 | inode = mapping->host; |
734 | info = SHMEM_I(inode); |
735 | if (info->flags & VM_LOCKED) |
736 | goto redirty; |
737 | if (!total_swap_pages) |
738 | goto redirty; |
739 | |
740 | /* |
741 | * shmem_backing_dev_info's capabilities prevent regular writeback or |
742 | * sync from ever calling shmem_writepage; but a stacking filesystem |
743 | * might use ->writepage of its underlying filesystem, in which case |
744 | * tmpfs should write out to swap only in response to memory pressure, |
745 | * and not for the writeback threads or sync. |
746 | */ |
747 | if (!wbc->for_reclaim) { |
748 | WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ |
749 | goto redirty; |
750 | } |
751 | |
752 | /* |
753 | * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC |
754 | * value into swapfile.c, the only way we can correctly account for a |
755 | * fallocated page arriving here is now to initialize it and write it. |
756 | * |
757 | * That's okay for a page already fallocated earlier, but if we have |
758 | * not yet completed the fallocation, then (a) we want to keep track |
759 | * of this page in case we have to undo it, and (b) it may not be a |
760 | * good idea to continue anyway, once we're pushing into swap. So |
761 | * reactivate the page, and let shmem_fallocate() quit when too many. |
762 | */ |
763 | if (!PageUptodate(page)) { |
764 | if (inode->i_private) { |
765 | struct shmem_falloc *shmem_falloc; |
766 | spin_lock(&inode->i_lock); |
767 | shmem_falloc = inode->i_private; |
768 | if (shmem_falloc && |
769 | !shmem_falloc->waitq && |
770 | index >= shmem_falloc->start && |
771 | index < shmem_falloc->next) |
772 | shmem_falloc->nr_unswapped++; |
773 | else |
774 | shmem_falloc = NULL; |
775 | spin_unlock(&inode->i_lock); |
776 | if (shmem_falloc) |
777 | goto redirty; |
778 | } |
779 | clear_highpage(page); |
780 | flush_dcache_page(page); |
781 | SetPageUptodate(page); |
782 | } |
783 | |
784 | swap = get_swap_page(); |
785 | if (!swap.val) |
786 | goto redirty; |
787 | |
788 | /* |
789 | * Add inode to shmem_unuse()'s list of swapped-out inodes, |
790 | * if it's not already there. Do it now before the page is |
791 | * moved to swap cache, when its pagelock no longer protects |
792 | * the inode from eviction. But don't unlock the mutex until |
793 | * we've incremented swapped, because shmem_unuse_inode() will |
794 | * prune a !swapped inode from the swaplist under this mutex. |
795 | */ |
796 | mutex_lock(&shmem_swaplist_mutex); |
797 | if (list_empty(&info->swaplist)) |
798 | list_add_tail(&info->swaplist, &shmem_swaplist); |
799 | |
800 | if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
801 | swap_shmem_alloc(swap); |
802 | shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); |
803 | |
804 | spin_lock(&info->lock); |
805 | info->swapped++; |
806 | shmem_recalc_inode(inode); |
807 | spin_unlock(&info->lock); |
808 | |
809 | mutex_unlock(&shmem_swaplist_mutex); |
810 | BUG_ON(page_mapped(page)); |
811 | swap_writepage(page, wbc); |
812 | return 0; |
813 | } |
814 | |
815 | mutex_unlock(&shmem_swaplist_mutex); |
816 | swapcache_free(swap, NULL); |
817 | redirty: |
818 | set_page_dirty(page); |
819 | if (wbc->for_reclaim) |
820 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
821 | unlock_page(page); |
822 | return 0; |
823 | } |
824 | |
825 | #ifdef CONFIG_NUMA |
826 | #ifdef CONFIG_TMPFS |
827 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
828 | { |
829 | char buffer[64]; |
830 | |
831 | if (!mpol || mpol->mode == MPOL_DEFAULT) |
832 | return; /* show nothing */ |
833 | |
834 | mpol_to_str(buffer, sizeof(buffer), mpol); |
835 | |
836 | seq_printf(seq, ",mpol=%s", buffer); |
837 | } |
838 | |
839 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
840 | { |
841 | struct mempolicy *mpol = NULL; |
842 | if (sbinfo->mpol) { |
843 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
844 | mpol = sbinfo->mpol; |
845 | mpol_get(mpol); |
846 | spin_unlock(&sbinfo->stat_lock); |
847 | } |
848 | return mpol; |
849 | } |
850 | #endif /* CONFIG_TMPFS */ |
851 | |
852 | static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
853 | struct shmem_inode_info *info, pgoff_t index) |
854 | { |
855 | struct vm_area_struct pvma; |
856 | struct page *page; |
857 | |
858 | /* Create a pseudo vma that just contains the policy */ |
859 | pvma.vm_start = 0; |
860 | /* Bias interleave by inode number to distribute better across nodes */ |
861 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
862 | pvma.vm_ops = NULL; |
863 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
864 | |
865 | page = swapin_readahead(swap, gfp, &pvma, 0); |
866 | |
867 | /* Drop reference taken by mpol_shared_policy_lookup() */ |
868 | mpol_cond_put(pvma.vm_policy); |
869 | |
870 | return page; |
871 | } |
872 | |
873 | static struct page *shmem_alloc_page(gfp_t gfp, |
874 | struct shmem_inode_info *info, pgoff_t index) |
875 | { |
876 | struct vm_area_struct pvma; |
877 | struct page *page; |
878 | |
879 | /* Create a pseudo vma that just contains the policy */ |
880 | pvma.vm_start = 0; |
881 | /* Bias interleave by inode number to distribute better across nodes */ |
882 | pvma.vm_pgoff = index + info->vfs_inode.i_ino; |
883 | pvma.vm_ops = NULL; |
884 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
885 | |
886 | page = alloc_page_vma(gfp, &pvma, 0); |
887 | |
888 | /* Drop reference taken by mpol_shared_policy_lookup() */ |
889 | mpol_cond_put(pvma.vm_policy); |
890 | |
891 | return page; |
892 | } |
893 | #else /* !CONFIG_NUMA */ |
894 | #ifdef CONFIG_TMPFS |
895 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
896 | { |
897 | } |
898 | #endif /* CONFIG_TMPFS */ |
899 | |
900 | static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
901 | struct shmem_inode_info *info, pgoff_t index) |
902 | { |
903 | return swapin_readahead(swap, gfp, NULL, 0); |
904 | } |
905 | |
906 | static inline struct page *shmem_alloc_page(gfp_t gfp, |
907 | struct shmem_inode_info *info, pgoff_t index) |
908 | { |
909 | return alloc_page(gfp); |
910 | } |
911 | #endif /* CONFIG_NUMA */ |
912 | |
913 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
914 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
915 | { |
916 | return NULL; |
917 | } |
918 | #endif |
919 | |
920 | /* |
921 | * When a page is moved from swapcache to shmem filecache (either by the |
922 | * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of |
923 | * shmem_unuse_inode()), it may have been read in earlier from swap, in |
924 | * ignorance of the mapping it belongs to. If that mapping has special |
925 | * constraints (like the gma500 GEM driver, which requires RAM below 4GB), |
926 | * we may need to copy to a suitable page before moving to filecache. |
927 | * |
928 | * In a future release, this may well be extended to respect cpuset and |
929 | * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); |
930 | * but for now it is a simple matter of zone. |
931 | */ |
932 | static bool shmem_should_replace_page(struct page *page, gfp_t gfp) |
933 | { |
934 | return page_zonenum(page) > gfp_zone(gfp); |
935 | } |
936 | |
937 | static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
938 | struct shmem_inode_info *info, pgoff_t index) |
939 | { |
940 | struct page *oldpage, *newpage; |
941 | struct address_space *swap_mapping; |
942 | pgoff_t swap_index; |
943 | int error; |
944 | |
945 | oldpage = *pagep; |
946 | swap_index = page_private(oldpage); |
947 | swap_mapping = page_mapping(oldpage); |
948 | |
949 | /* |
950 | * We have arrived here because our zones are constrained, so don't |
951 | * limit chance of success by further cpuset and node constraints. |
952 | */ |
953 | gfp &= ~GFP_CONSTRAINT_MASK; |
954 | newpage = shmem_alloc_page(gfp, info, index); |
955 | if (!newpage) |
956 | return -ENOMEM; |
957 | |
958 | page_cache_get(newpage); |
959 | copy_highpage(newpage, oldpage); |
960 | flush_dcache_page(newpage); |
961 | |
962 | __set_page_locked(newpage); |
963 | SetPageUptodate(newpage); |
964 | SetPageSwapBacked(newpage); |
965 | set_page_private(newpage, swap_index); |
966 | SetPageSwapCache(newpage); |
967 | |
968 | /* |
969 | * Our caller will very soon move newpage out of swapcache, but it's |
970 | * a nice clean interface for us to replace oldpage by newpage there. |
971 | */ |
972 | spin_lock_irq(&swap_mapping->tree_lock); |
973 | error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage, |
974 | newpage); |
975 | if (!error) { |
976 | __inc_zone_page_state(newpage, NR_FILE_PAGES); |
977 | __dec_zone_page_state(oldpage, NR_FILE_PAGES); |
978 | } |
979 | spin_unlock_irq(&swap_mapping->tree_lock); |
980 | |
981 | if (unlikely(error)) { |
982 | /* |
983 | * Is this possible? I think not, now that our callers check |
984 | * both PageSwapCache and page_private after getting page lock; |
985 | * but be defensive. Reverse old to newpage for clear and free. |
986 | */ |
987 | oldpage = newpage; |
988 | } else { |
989 | mem_cgroup_replace_page_cache(oldpage, newpage); |
990 | lru_cache_add_anon(newpage); |
991 | *pagep = newpage; |
992 | } |
993 | |
994 | ClearPageSwapCache(oldpage); |
995 | set_page_private(oldpage, 0); |
996 | |
997 | unlock_page(oldpage); |
998 | page_cache_release(oldpage); |
999 | page_cache_release(oldpage); |
1000 | return error; |
1001 | } |
1002 | |
1003 | /* |
1004 | * shmem_getpage_gfp - find page in cache, or get from swap, or allocate |
1005 | * |
1006 | * If we allocate a new one we do not mark it dirty. That's up to the |
1007 | * vm. If we swap it in we mark it dirty since we also free the swap |
1008 | * entry since a page cannot live in both the swap and page cache |
1009 | */ |
1010 | static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
1011 | struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) |
1012 | { |
1013 | struct address_space *mapping = inode->i_mapping; |
1014 | struct shmem_inode_info *info; |
1015 | struct shmem_sb_info *sbinfo; |
1016 | struct page *page; |
1017 | swp_entry_t swap; |
1018 | int error; |
1019 | int once = 0; |
1020 | int alloced = 0; |
1021 | |
1022 | if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) |
1023 | return -EFBIG; |
1024 | repeat: |
1025 | swap.val = 0; |
1026 | page = find_lock_entry(mapping, index); |
1027 | if (radix_tree_exceptional_entry(page)) { |
1028 | swap = radix_to_swp_entry(page); |
1029 | page = NULL; |
1030 | } |
1031 | |
1032 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
1033 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
1034 | error = -EINVAL; |
1035 | goto failed; |
1036 | } |
1037 | |
1038 | if (page && sgp == SGP_WRITE) |
1039 | mark_page_accessed(page); |
1040 | |
1041 | /* fallocated page? */ |
1042 | if (page && !PageUptodate(page)) { |
1043 | if (sgp != SGP_READ) |
1044 | goto clear; |
1045 | unlock_page(page); |
1046 | page_cache_release(page); |
1047 | page = NULL; |
1048 | } |
1049 | if (page || (sgp == SGP_READ && !swap.val)) { |
1050 | *pagep = page; |
1051 | return 0; |
1052 | } |
1053 | |
1054 | /* |
1055 | * Fast cache lookup did not find it: |
1056 | * bring it back from swap or allocate. |
1057 | */ |
1058 | info = SHMEM_I(inode); |
1059 | sbinfo = SHMEM_SB(inode->i_sb); |
1060 | |
1061 | if (swap.val) { |
1062 | /* Look it up and read it in.. */ |
1063 | page = lookup_swap_cache(swap); |
1064 | if (!page) { |
1065 | /* here we actually do the io */ |
1066 | if (fault_type) |
1067 | *fault_type |= VM_FAULT_MAJOR; |
1068 | page = shmem_swapin(swap, gfp, info, index); |
1069 | if (!page) { |
1070 | error = -ENOMEM; |
1071 | goto failed; |
1072 | } |
1073 | } |
1074 | |
1075 | /* We have to do this with page locked to prevent races */ |
1076 | lock_page(page); |
1077 | if (!PageSwapCache(page) || page_private(page) != swap.val || |
1078 | !shmem_confirm_swap(mapping, index, swap)) { |
1079 | error = -EEXIST; /* try again */ |
1080 | goto unlock; |
1081 | } |
1082 | if (!PageUptodate(page)) { |
1083 | error = -EIO; |
1084 | goto failed; |
1085 | } |
1086 | wait_on_page_writeback(page); |
1087 | |
1088 | if (shmem_should_replace_page(page, gfp)) { |
1089 | error = shmem_replace_page(&page, gfp, info, index); |
1090 | if (error) |
1091 | goto failed; |
1092 | } |
1093 | |
1094 | error = mem_cgroup_charge_file(page, current->mm, |
1095 | gfp & GFP_RECLAIM_MASK); |
1096 | if (!error) { |
1097 | error = shmem_add_to_page_cache(page, mapping, index, |
1098 | gfp, swp_to_radix_entry(swap)); |
1099 | /* |
1100 | * We already confirmed swap under page lock, and make |
1101 | * no memory allocation here, so usually no possibility |
1102 | * of error; but free_swap_and_cache() only trylocks a |
1103 | * page, so it is just possible that the entry has been |
1104 | * truncated or holepunched since swap was confirmed. |
1105 | * shmem_undo_range() will have done some of the |
1106 | * unaccounting, now delete_from_swap_cache() will do |
1107 | * the rest (including mem_cgroup_uncharge_swapcache). |
1108 | * Reset swap.val? No, leave it so "failed" goes back to |
1109 | * "repeat": reading a hole and writing should succeed. |
1110 | */ |
1111 | if (error) |
1112 | delete_from_swap_cache(page); |
1113 | } |
1114 | if (error) |
1115 | goto failed; |
1116 | |
1117 | spin_lock(&info->lock); |
1118 | info->swapped--; |
1119 | shmem_recalc_inode(inode); |
1120 | spin_unlock(&info->lock); |
1121 | |
1122 | if (sgp == SGP_WRITE) |
1123 | mark_page_accessed(page); |
1124 | |
1125 | delete_from_swap_cache(page); |
1126 | set_page_dirty(page); |
1127 | swap_free(swap); |
1128 | |
1129 | } else { |
1130 | if (shmem_acct_block(info->flags)) { |
1131 | error = -ENOSPC; |
1132 | goto failed; |
1133 | } |
1134 | if (sbinfo->max_blocks) { |
1135 | if (percpu_counter_compare(&sbinfo->used_blocks, |
1136 | sbinfo->max_blocks) >= 0) { |
1137 | error = -ENOSPC; |
1138 | goto unacct; |
1139 | } |
1140 | percpu_counter_inc(&sbinfo->used_blocks); |
1141 | } |
1142 | |
1143 | page = shmem_alloc_page(gfp, info, index); |
1144 | if (!page) { |
1145 | error = -ENOMEM; |
1146 | goto decused; |
1147 | } |
1148 | |
1149 | __SetPageSwapBacked(page); |
1150 | __set_page_locked(page); |
1151 | if (sgp == SGP_WRITE) |
1152 | init_page_accessed(page); |
1153 | |
1154 | error = mem_cgroup_charge_file(page, current->mm, |
1155 | gfp & GFP_RECLAIM_MASK); |
1156 | if (error) |
1157 | goto decused; |
1158 | error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK); |
1159 | if (!error) { |
1160 | error = shmem_add_to_page_cache(page, mapping, index, |
1161 | gfp, NULL); |
1162 | radix_tree_preload_end(); |
1163 | } |
1164 | if (error) { |
1165 | mem_cgroup_uncharge_cache_page(page); |
1166 | goto decused; |
1167 | } |
1168 | lru_cache_add_anon(page); |
1169 | |
1170 | spin_lock(&info->lock); |
1171 | info->alloced++; |
1172 | inode->i_blocks += BLOCKS_PER_PAGE; |
1173 | shmem_recalc_inode(inode); |
1174 | spin_unlock(&info->lock); |
1175 | alloced = true; |
1176 | |
1177 | /* |
1178 | * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. |
1179 | */ |
1180 | if (sgp == SGP_FALLOC) |
1181 | sgp = SGP_WRITE; |
1182 | clear: |
1183 | /* |
1184 | * Let SGP_WRITE caller clear ends if write does not fill page; |
1185 | * but SGP_FALLOC on a page fallocated earlier must initialize |
1186 | * it now, lest undo on failure cancel our earlier guarantee. |
1187 | */ |
1188 | if (sgp != SGP_WRITE) { |
1189 | clear_highpage(page); |
1190 | flush_dcache_page(page); |
1191 | SetPageUptodate(page); |
1192 | } |
1193 | if (sgp == SGP_DIRTY) |
1194 | set_page_dirty(page); |
1195 | } |
1196 | |
1197 | /* Perhaps the file has been truncated since we checked */ |
1198 | if (sgp != SGP_WRITE && sgp != SGP_FALLOC && |
1199 | ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
1200 | error = -EINVAL; |
1201 | if (alloced) |
1202 | goto trunc; |
1203 | else |
1204 | goto failed; |
1205 | } |
1206 | *pagep = page; |
1207 | return 0; |
1208 | |
1209 | /* |
1210 | * Error recovery. |
1211 | */ |
1212 | trunc: |
1213 | info = SHMEM_I(inode); |
1214 | ClearPageDirty(page); |
1215 | delete_from_page_cache(page); |
1216 | spin_lock(&info->lock); |
1217 | info->alloced--; |
1218 | inode->i_blocks -= BLOCKS_PER_PAGE; |
1219 | spin_unlock(&info->lock); |
1220 | decused: |
1221 | sbinfo = SHMEM_SB(inode->i_sb); |
1222 | if (sbinfo->max_blocks) |
1223 | percpu_counter_add(&sbinfo->used_blocks, -1); |
1224 | unacct: |
1225 | shmem_unacct_blocks(info->flags, 1); |
1226 | failed: |
1227 | if (swap.val && error != -EINVAL && |
1228 | !shmem_confirm_swap(mapping, index, swap)) |
1229 | error = -EEXIST; |
1230 | unlock: |
1231 | if (page) { |
1232 | unlock_page(page); |
1233 | page_cache_release(page); |
1234 | } |
1235 | if (error == -ENOSPC && !once++) { |
1236 | info = SHMEM_I(inode); |
1237 | spin_lock(&info->lock); |
1238 | shmem_recalc_inode(inode); |
1239 | spin_unlock(&info->lock); |
1240 | goto repeat; |
1241 | } |
1242 | if (error == -EEXIST) /* from above or from radix_tree_insert */ |
1243 | goto repeat; |
1244 | return error; |
1245 | } |
1246 | |
1247 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1248 | { |
1249 | struct inode *inode = file_inode(vma->vm_file); |
1250 | int error; |
1251 | int ret = VM_FAULT_LOCKED; |
1252 | |
1253 | /* |
1254 | * Trinity finds that probing a hole which tmpfs is punching can |
1255 | * prevent the hole-punch from ever completing: which in turn |
1256 | * locks writers out with its hold on i_mutex. So refrain from |
1257 | * faulting pages into the hole while it's being punched. Although |
1258 | * shmem_undo_range() does remove the additions, it may be unable to |
1259 | * keep up, as each new page needs its own unmap_mapping_range() call, |
1260 | * and the i_mmap tree grows ever slower to scan if new vmas are added. |
1261 | * |
1262 | * It does not matter if we sometimes reach this check just before the |
1263 | * hole-punch begins, so that one fault then races with the punch: |
1264 | * we just need to make racing faults a rare case. |
1265 | * |
1266 | * The implementation below would be much simpler if we just used a |
1267 | * standard mutex or completion: but we cannot take i_mutex in fault, |
1268 | * and bloating every shmem inode for this unlikely case would be sad. |
1269 | */ |
1270 | if (unlikely(inode->i_private)) { |
1271 | struct shmem_falloc *shmem_falloc; |
1272 | |
1273 | spin_lock(&inode->i_lock); |
1274 | shmem_falloc = inode->i_private; |
1275 | if (shmem_falloc && |
1276 | shmem_falloc->waitq && |
1277 | vmf->pgoff >= shmem_falloc->start && |
1278 | vmf->pgoff < shmem_falloc->next) { |
1279 | wait_queue_head_t *shmem_falloc_waitq; |
1280 | DEFINE_WAIT(shmem_fault_wait); |
1281 | |
1282 | ret = VM_FAULT_NOPAGE; |
1283 | if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) && |
1284 | !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) { |
1285 | /* It's polite to up mmap_sem if we can */ |
1286 | up_read(&vma->vm_mm->mmap_sem); |
1287 | ret = VM_FAULT_RETRY; |
1288 | } |
1289 | |
1290 | shmem_falloc_waitq = shmem_falloc->waitq; |
1291 | prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait, |
1292 | TASK_UNINTERRUPTIBLE); |
1293 | spin_unlock(&inode->i_lock); |
1294 | schedule(); |
1295 | |
1296 | /* |
1297 | * shmem_falloc_waitq points into the shmem_fallocate() |
1298 | * stack of the hole-punching task: shmem_falloc_waitq |
1299 | * is usually invalid by the time we reach here, but |
1300 | * finish_wait() does not dereference it in that case; |
1301 | * though i_lock needed lest racing with wake_up_all(). |
1302 | */ |
1303 | spin_lock(&inode->i_lock); |
1304 | finish_wait(shmem_falloc_waitq, &shmem_fault_wait); |
1305 | spin_unlock(&inode->i_lock); |
1306 | return ret; |
1307 | } |
1308 | spin_unlock(&inode->i_lock); |
1309 | } |
1310 | |
1311 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
1312 | if (error) |
1313 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
1314 | |
1315 | if (ret & VM_FAULT_MAJOR) { |
1316 | count_vm_event(PGMAJFAULT); |
1317 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); |
1318 | } |
1319 | return ret; |
1320 | } |
1321 | |
1322 | #ifdef CONFIG_NUMA |
1323 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) |
1324 | { |
1325 | struct inode *inode = file_inode(vma->vm_file); |
1326 | return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); |
1327 | } |
1328 | |
1329 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
1330 | unsigned long addr) |
1331 | { |
1332 | struct inode *inode = file_inode(vma->vm_file); |
1333 | pgoff_t index; |
1334 | |
1335 | index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
1336 | return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); |
1337 | } |
1338 | #endif |
1339 | |
1340 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
1341 | { |
1342 | struct inode *inode = file_inode(file); |
1343 | struct shmem_inode_info *info = SHMEM_I(inode); |
1344 | int retval = -ENOMEM; |
1345 | |
1346 | spin_lock(&info->lock); |
1347 | if (lock && !(info->flags & VM_LOCKED)) { |
1348 | if (!user_shm_lock(inode->i_size, user)) |
1349 | goto out_nomem; |
1350 | info->flags |= VM_LOCKED; |
1351 | mapping_set_unevictable(file->f_mapping); |
1352 | } |
1353 | if (!lock && (info->flags & VM_LOCKED) && user) { |
1354 | user_shm_unlock(inode->i_size, user); |
1355 | info->flags &= ~VM_LOCKED; |
1356 | mapping_clear_unevictable(file->f_mapping); |
1357 | } |
1358 | retval = 0; |
1359 | |
1360 | out_nomem: |
1361 | spin_unlock(&info->lock); |
1362 | return retval; |
1363 | } |
1364 | |
1365 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
1366 | { |
1367 | file_accessed(file); |
1368 | vma->vm_ops = &shmem_vm_ops; |
1369 | return 0; |
1370 | } |
1371 | |
1372 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
1373 | umode_t mode, dev_t dev, unsigned long flags) |
1374 | { |
1375 | struct inode *inode; |
1376 | struct shmem_inode_info *info; |
1377 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
1378 | |
1379 | if (shmem_reserve_inode(sb)) |
1380 | return NULL; |
1381 | |
1382 | inode = new_inode(sb); |
1383 | if (inode) { |
1384 | inode->i_ino = get_next_ino(); |
1385 | inode_init_owner(inode, dir, mode); |
1386 | inode->i_blocks = 0; |
1387 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
1388 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1389 | inode->i_generation = get_seconds(); |
1390 | info = SHMEM_I(inode); |
1391 | memset(info, 0, (char *)inode - (char *)info); |
1392 | spin_lock_init(&info->lock); |
1393 | info->flags = flags & VM_NORESERVE; |
1394 | INIT_LIST_HEAD(&info->swaplist); |
1395 | simple_xattrs_init(&info->xattrs); |
1396 | cache_no_acl(inode); |
1397 | |
1398 | switch (mode & S_IFMT) { |
1399 | default: |
1400 | inode->i_op = &shmem_special_inode_operations; |
1401 | init_special_inode(inode, mode, dev); |
1402 | break; |
1403 | case S_IFREG: |
1404 | inode->i_mapping->a_ops = &shmem_aops; |
1405 | inode->i_op = &shmem_inode_operations; |
1406 | inode->i_fop = &shmem_file_operations; |
1407 | mpol_shared_policy_init(&info->policy, |
1408 | shmem_get_sbmpol(sbinfo)); |
1409 | break; |
1410 | case S_IFDIR: |
1411 | inc_nlink(inode); |
1412 | /* Some things misbehave if size == 0 on a directory */ |
1413 | inode->i_size = 2 * BOGO_DIRENT_SIZE; |
1414 | inode->i_op = &shmem_dir_inode_operations; |
1415 | inode->i_fop = &simple_dir_operations; |
1416 | break; |
1417 | case S_IFLNK: |
1418 | /* |
1419 | * Must not load anything in the rbtree, |
1420 | * mpol_free_shared_policy will not be called. |
1421 | */ |
1422 | mpol_shared_policy_init(&info->policy, NULL); |
1423 | break; |
1424 | } |
1425 | } else |
1426 | shmem_free_inode(sb); |
1427 | return inode; |
1428 | } |
1429 | |
1430 | bool shmem_mapping(struct address_space *mapping) |
1431 | { |
1432 | return mapping->backing_dev_info == &shmem_backing_dev_info; |
1433 | } |
1434 | |
1435 | #ifdef CONFIG_TMPFS |
1436 | static const struct inode_operations shmem_symlink_inode_operations; |
1437 | static const struct inode_operations shmem_short_symlink_operations; |
1438 | |
1439 | #ifdef CONFIG_TMPFS_XATTR |
1440 | static int shmem_initxattrs(struct inode *, const struct xattr *, void *); |
1441 | #else |
1442 | #define shmem_initxattrs NULL |
1443 | #endif |
1444 | |
1445 | static int |
1446 | shmem_write_begin(struct file *file, struct address_space *mapping, |
1447 | loff_t pos, unsigned len, unsigned flags, |
1448 | struct page **pagep, void **fsdata) |
1449 | { |
1450 | struct inode *inode = mapping->host; |
1451 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
1452 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
1453 | } |
1454 | |
1455 | static int |
1456 | shmem_write_end(struct file *file, struct address_space *mapping, |
1457 | loff_t pos, unsigned len, unsigned copied, |
1458 | struct page *page, void *fsdata) |
1459 | { |
1460 | struct inode *inode = mapping->host; |
1461 | |
1462 | if (pos + copied > inode->i_size) |
1463 | i_size_write(inode, pos + copied); |
1464 | |
1465 | if (!PageUptodate(page)) { |
1466 | if (copied < PAGE_CACHE_SIZE) { |
1467 | unsigned from = pos & (PAGE_CACHE_SIZE - 1); |
1468 | zero_user_segments(page, 0, from, |
1469 | from + copied, PAGE_CACHE_SIZE); |
1470 | } |
1471 | SetPageUptodate(page); |
1472 | } |
1473 | set_page_dirty(page); |
1474 | unlock_page(page); |
1475 | page_cache_release(page); |
1476 | |
1477 | return copied; |
1478 | } |
1479 | |
1480 | static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) |
1481 | { |
1482 | struct file *file = iocb->ki_filp; |
1483 | struct inode *inode = file_inode(file); |
1484 | struct address_space *mapping = inode->i_mapping; |
1485 | pgoff_t index; |
1486 | unsigned long offset; |
1487 | enum sgp_type sgp = SGP_READ; |
1488 | int error = 0; |
1489 | ssize_t retval = 0; |
1490 | loff_t *ppos = &iocb->ki_pos; |
1491 | |
1492 | /* |
1493 | * Might this read be for a stacking filesystem? Then when reading |
1494 | * holes of a sparse file, we actually need to allocate those pages, |
1495 | * and even mark them dirty, so it cannot exceed the max_blocks limit. |
1496 | */ |
1497 | if (segment_eq(get_fs(), KERNEL_DS)) |
1498 | sgp = SGP_DIRTY; |
1499 | |
1500 | index = *ppos >> PAGE_CACHE_SHIFT; |
1501 | offset = *ppos & ~PAGE_CACHE_MASK; |
1502 | |
1503 | for (;;) { |
1504 | struct page *page = NULL; |
1505 | pgoff_t end_index; |
1506 | unsigned long nr, ret; |
1507 | loff_t i_size = i_size_read(inode); |
1508 | |
1509 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1510 | if (index > end_index) |
1511 | break; |
1512 | if (index == end_index) { |
1513 | nr = i_size & ~PAGE_CACHE_MASK; |
1514 | if (nr <= offset) |
1515 | break; |
1516 | } |
1517 | |
1518 | error = shmem_getpage(inode, index, &page, sgp, NULL); |
1519 | if (error) { |
1520 | if (error == -EINVAL) |
1521 | error = 0; |
1522 | break; |
1523 | } |
1524 | if (page) |
1525 | unlock_page(page); |
1526 | |
1527 | /* |
1528 | * We must evaluate after, since reads (unlike writes) |
1529 | * are called without i_mutex protection against truncate |
1530 | */ |
1531 | nr = PAGE_CACHE_SIZE; |
1532 | i_size = i_size_read(inode); |
1533 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1534 | if (index == end_index) { |
1535 | nr = i_size & ~PAGE_CACHE_MASK; |
1536 | if (nr <= offset) { |
1537 | if (page) |
1538 | page_cache_release(page); |
1539 | break; |
1540 | } |
1541 | } |
1542 | nr -= offset; |
1543 | |
1544 | if (page) { |
1545 | /* |
1546 | * If users can be writing to this page using arbitrary |
1547 | * virtual addresses, take care about potential aliasing |
1548 | * before reading the page on the kernel side. |
1549 | */ |
1550 | if (mapping_writably_mapped(mapping)) |
1551 | flush_dcache_page(page); |
1552 | /* |
1553 | * Mark the page accessed if we read the beginning. |
1554 | */ |
1555 | if (!offset) |
1556 | mark_page_accessed(page); |
1557 | } else { |
1558 | page = ZERO_PAGE(0); |
1559 | page_cache_get(page); |
1560 | } |
1561 | |
1562 | /* |
1563 | * Ok, we have the page, and it's up-to-date, so |
1564 | * now we can copy it to user space... |
1565 | */ |
1566 | ret = copy_page_to_iter(page, offset, nr, to); |
1567 | retval += ret; |
1568 | offset += ret; |
1569 | index += offset >> PAGE_CACHE_SHIFT; |
1570 | offset &= ~PAGE_CACHE_MASK; |
1571 | |
1572 | page_cache_release(page); |
1573 | if (!iov_iter_count(to)) |
1574 | break; |
1575 | if (ret < nr) { |
1576 | error = -EFAULT; |
1577 | break; |
1578 | } |
1579 | cond_resched(); |
1580 | } |
1581 | |
1582 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
1583 | file_accessed(file); |
1584 | return retval ? retval : error; |
1585 | } |
1586 | |
1587 | static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, |
1588 | struct pipe_inode_info *pipe, size_t len, |
1589 | unsigned int flags) |
1590 | { |
1591 | struct address_space *mapping = in->f_mapping; |
1592 | struct inode *inode = mapping->host; |
1593 | unsigned int loff, nr_pages, req_pages; |
1594 | struct page *pages[PIPE_DEF_BUFFERS]; |
1595 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
1596 | struct page *page; |
1597 | pgoff_t index, end_index; |
1598 | loff_t isize, left; |
1599 | int error, page_nr; |
1600 | struct splice_pipe_desc spd = { |
1601 | .pages = pages, |
1602 | .partial = partial, |
1603 | .nr_pages_max = PIPE_DEF_BUFFERS, |
1604 | .flags = flags, |
1605 | .ops = &page_cache_pipe_buf_ops, |
1606 | .spd_release = spd_release_page, |
1607 | }; |
1608 | |
1609 | isize = i_size_read(inode); |
1610 | if (unlikely(*ppos >= isize)) |
1611 | return 0; |
1612 | |
1613 | left = isize - *ppos; |
1614 | if (unlikely(left < len)) |
1615 | len = left; |
1616 | |
1617 | if (splice_grow_spd(pipe, &spd)) |
1618 | return -ENOMEM; |
1619 | |
1620 | index = *ppos >> PAGE_CACHE_SHIFT; |
1621 | loff = *ppos & ~PAGE_CACHE_MASK; |
1622 | req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1623 | nr_pages = min(req_pages, spd.nr_pages_max); |
1624 | |
1625 | spd.nr_pages = find_get_pages_contig(mapping, index, |
1626 | nr_pages, spd.pages); |
1627 | index += spd.nr_pages; |
1628 | error = 0; |
1629 | |
1630 | while (spd.nr_pages < nr_pages) { |
1631 | error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); |
1632 | if (error) |
1633 | break; |
1634 | unlock_page(page); |
1635 | spd.pages[spd.nr_pages++] = page; |
1636 | index++; |
1637 | } |
1638 | |
1639 | index = *ppos >> PAGE_CACHE_SHIFT; |
1640 | nr_pages = spd.nr_pages; |
1641 | spd.nr_pages = 0; |
1642 | |
1643 | for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
1644 | unsigned int this_len; |
1645 | |
1646 | if (!len) |
1647 | break; |
1648 | |
1649 | this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
1650 | page = spd.pages[page_nr]; |
1651 | |
1652 | if (!PageUptodate(page) || page->mapping != mapping) { |
1653 | error = shmem_getpage(inode, index, &page, |
1654 | SGP_CACHE, NULL); |
1655 | if (error) |
1656 | break; |
1657 | unlock_page(page); |
1658 | page_cache_release(spd.pages[page_nr]); |
1659 | spd.pages[page_nr] = page; |
1660 | } |
1661 | |
1662 | isize = i_size_read(inode); |
1663 | end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
1664 | if (unlikely(!isize || index > end_index)) |
1665 | break; |
1666 | |
1667 | if (end_index == index) { |
1668 | unsigned int plen; |
1669 | |
1670 | plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
1671 | if (plen <= loff) |
1672 | break; |
1673 | |
1674 | this_len = min(this_len, plen - loff); |
1675 | len = this_len; |
1676 | } |
1677 | |
1678 | spd.partial[page_nr].offset = loff; |
1679 | spd.partial[page_nr].len = this_len; |
1680 | len -= this_len; |
1681 | loff = 0; |
1682 | spd.nr_pages++; |
1683 | index++; |
1684 | } |
1685 | |
1686 | while (page_nr < nr_pages) |
1687 | page_cache_release(spd.pages[page_nr++]); |
1688 | |
1689 | if (spd.nr_pages) |
1690 | error = splice_to_pipe(pipe, &spd); |
1691 | |
1692 | splice_shrink_spd(&spd); |
1693 | |
1694 | if (error > 0) { |
1695 | *ppos += error; |
1696 | file_accessed(in); |
1697 | } |
1698 | return error; |
1699 | } |
1700 | |
1701 | /* |
1702 | * llseek SEEK_DATA or SEEK_HOLE through the radix_tree. |
1703 | */ |
1704 | static pgoff_t shmem_seek_hole_data(struct address_space *mapping, |
1705 | pgoff_t index, pgoff_t end, int whence) |
1706 | { |
1707 | struct page *page; |
1708 | struct pagevec pvec; |
1709 | pgoff_t indices[PAGEVEC_SIZE]; |
1710 | bool done = false; |
1711 | int i; |
1712 | |
1713 | pagevec_init(&pvec, 0); |
1714 | pvec.nr = 1; /* start small: we may be there already */ |
1715 | while (!done) { |
1716 | pvec.nr = find_get_entries(mapping, index, |
1717 | pvec.nr, pvec.pages, indices); |
1718 | if (!pvec.nr) { |
1719 | if (whence == SEEK_DATA) |
1720 | index = end; |
1721 | break; |
1722 | } |
1723 | for (i = 0; i < pvec.nr; i++, index++) { |
1724 | if (index < indices[i]) { |
1725 | if (whence == SEEK_HOLE) { |
1726 | done = true; |
1727 | break; |
1728 | } |
1729 | index = indices[i]; |
1730 | } |
1731 | page = pvec.pages[i]; |
1732 | if (page && !radix_tree_exceptional_entry(page)) { |
1733 | if (!PageUptodate(page)) |
1734 | page = NULL; |
1735 | } |
1736 | if (index >= end || |
1737 | (page && whence == SEEK_DATA) || |
1738 | (!page && whence == SEEK_HOLE)) { |
1739 | done = true; |
1740 | break; |
1741 | } |
1742 | } |
1743 | pagevec_remove_exceptionals(&pvec); |
1744 | pagevec_release(&pvec); |
1745 | pvec.nr = PAGEVEC_SIZE; |
1746 | cond_resched(); |
1747 | } |
1748 | return index; |
1749 | } |
1750 | |
1751 | static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) |
1752 | { |
1753 | struct address_space *mapping = file->f_mapping; |
1754 | struct inode *inode = mapping->host; |
1755 | pgoff_t start, end; |
1756 | loff_t new_offset; |
1757 | |
1758 | if (whence != SEEK_DATA && whence != SEEK_HOLE) |
1759 | return generic_file_llseek_size(file, offset, whence, |
1760 | MAX_LFS_FILESIZE, i_size_read(inode)); |
1761 | mutex_lock(&inode->i_mutex); |
1762 | /* We're holding i_mutex so we can access i_size directly */ |
1763 | |
1764 | if (offset < 0) |
1765 | offset = -EINVAL; |
1766 | else if (offset >= inode->i_size) |
1767 | offset = -ENXIO; |
1768 | else { |
1769 | start = offset >> PAGE_CACHE_SHIFT; |
1770 | end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1771 | new_offset = shmem_seek_hole_data(mapping, start, end, whence); |
1772 | new_offset <<= PAGE_CACHE_SHIFT; |
1773 | if (new_offset > offset) { |
1774 | if (new_offset < inode->i_size) |
1775 | offset = new_offset; |
1776 | else if (whence == SEEK_DATA) |
1777 | offset = -ENXIO; |
1778 | else |
1779 | offset = inode->i_size; |
1780 | } |
1781 | } |
1782 | |
1783 | if (offset >= 0) |
1784 | offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); |
1785 | mutex_unlock(&inode->i_mutex); |
1786 | return offset; |
1787 | } |
1788 | |
1789 | static long shmem_fallocate(struct file *file, int mode, loff_t offset, |
1790 | loff_t len) |
1791 | { |
1792 | struct inode *inode = file_inode(file); |
1793 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
1794 | struct shmem_falloc shmem_falloc; |
1795 | pgoff_t start, index, end; |
1796 | int error; |
1797 | |
1798 | if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) |
1799 | return -EOPNOTSUPP; |
1800 | |
1801 | mutex_lock(&inode->i_mutex); |
1802 | |
1803 | if (mode & FALLOC_FL_PUNCH_HOLE) { |
1804 | struct address_space *mapping = file->f_mapping; |
1805 | loff_t unmap_start = round_up(offset, PAGE_SIZE); |
1806 | loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; |
1807 | DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq); |
1808 | |
1809 | shmem_falloc.waitq = &shmem_falloc_waitq; |
1810 | shmem_falloc.start = unmap_start >> PAGE_SHIFT; |
1811 | shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT; |
1812 | spin_lock(&inode->i_lock); |
1813 | inode->i_private = &shmem_falloc; |
1814 | spin_unlock(&inode->i_lock); |
1815 | |
1816 | if ((u64)unmap_end > (u64)unmap_start) |
1817 | unmap_mapping_range(mapping, unmap_start, |
1818 | 1 + unmap_end - unmap_start, 0); |
1819 | shmem_truncate_range(inode, offset, offset + len - 1); |
1820 | /* No need to unmap again: hole-punching leaves COWed pages */ |
1821 | |
1822 | spin_lock(&inode->i_lock); |
1823 | inode->i_private = NULL; |
1824 | wake_up_all(&shmem_falloc_waitq); |
1825 | spin_unlock(&inode->i_lock); |
1826 | error = 0; |
1827 | goto out; |
1828 | } |
1829 | |
1830 | /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ |
1831 | error = inode_newsize_ok(inode, offset + len); |
1832 | if (error) |
1833 | goto out; |
1834 | |
1835 | start = offset >> PAGE_CACHE_SHIFT; |
1836 | end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1837 | /* Try to avoid a swapstorm if len is impossible to satisfy */ |
1838 | if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { |
1839 | error = -ENOSPC; |
1840 | goto out; |
1841 | } |
1842 | |
1843 | shmem_falloc.waitq = NULL; |
1844 | shmem_falloc.start = start; |
1845 | shmem_falloc.next = start; |
1846 | shmem_falloc.nr_falloced = 0; |
1847 | shmem_falloc.nr_unswapped = 0; |
1848 | spin_lock(&inode->i_lock); |
1849 | inode->i_private = &shmem_falloc; |
1850 | spin_unlock(&inode->i_lock); |
1851 | |
1852 | for (index = start; index < end; index++) { |
1853 | struct page *page; |
1854 | |
1855 | /* |
1856 | * Good, the fallocate(2) manpage permits EINTR: we may have |
1857 | * been interrupted because we are using up too much memory. |
1858 | */ |
1859 | if (signal_pending(current)) |
1860 | error = -EINTR; |
1861 | else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) |
1862 | error = -ENOMEM; |
1863 | else |
1864 | error = shmem_getpage(inode, index, &page, SGP_FALLOC, |
1865 | NULL); |
1866 | if (error) { |
1867 | /* Remove the !PageUptodate pages we added */ |
1868 | shmem_undo_range(inode, |
1869 | (loff_t)start << PAGE_CACHE_SHIFT, |
1870 | (loff_t)index << PAGE_CACHE_SHIFT, true); |
1871 | goto undone; |
1872 | } |
1873 | |
1874 | /* |
1875 | * Inform shmem_writepage() how far we have reached. |
1876 | * No need for lock or barrier: we have the page lock. |
1877 | */ |
1878 | shmem_falloc.next++; |
1879 | if (!PageUptodate(page)) |
1880 | shmem_falloc.nr_falloced++; |
1881 | |
1882 | /* |
1883 | * If !PageUptodate, leave it that way so that freeable pages |
1884 | * can be recognized if we need to rollback on error later. |
1885 | * But set_page_dirty so that memory pressure will swap rather |
1886 | * than free the pages we are allocating (and SGP_CACHE pages |
1887 | * might still be clean: we now need to mark those dirty too). |
1888 | */ |
1889 | set_page_dirty(page); |
1890 | unlock_page(page); |
1891 | page_cache_release(page); |
1892 | cond_resched(); |
1893 | } |
1894 | |
1895 | if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) |
1896 | i_size_write(inode, offset + len); |
1897 | inode->i_ctime = CURRENT_TIME; |
1898 | undone: |
1899 | spin_lock(&inode->i_lock); |
1900 | inode->i_private = NULL; |
1901 | spin_unlock(&inode->i_lock); |
1902 | out: |
1903 | mutex_unlock(&inode->i_mutex); |
1904 | return error; |
1905 | } |
1906 | |
1907 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
1908 | { |
1909 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
1910 | |
1911 | buf->f_type = TMPFS_MAGIC; |
1912 | buf->f_bsize = PAGE_CACHE_SIZE; |
1913 | buf->f_namelen = NAME_MAX; |
1914 | if (sbinfo->max_blocks) { |
1915 | buf->f_blocks = sbinfo->max_blocks; |
1916 | buf->f_bavail = |
1917 | buf->f_bfree = sbinfo->max_blocks - |
1918 | percpu_counter_sum(&sbinfo->used_blocks); |
1919 | } |
1920 | if (sbinfo->max_inodes) { |
1921 | buf->f_files = sbinfo->max_inodes; |
1922 | buf->f_ffree = sbinfo->free_inodes; |
1923 | } |
1924 | /* else leave those fields 0 like simple_statfs */ |
1925 | return 0; |
1926 | } |
1927 | |
1928 | /* |
1929 | * File creation. Allocate an inode, and we're done.. |
1930 | */ |
1931 | static int |
1932 | shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) |
1933 | { |
1934 | struct inode *inode; |
1935 | int error = -ENOSPC; |
1936 | |
1937 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
1938 | if (inode) { |
1939 | error = simple_acl_create(dir, inode); |
1940 | if (error) |
1941 | goto out_iput; |
1942 | error = security_inode_init_security(inode, dir, |
1943 | &dentry->d_name, |
1944 | shmem_initxattrs, NULL); |
1945 | if (error && error != -EOPNOTSUPP) |
1946 | goto out_iput; |
1947 | |
1948 | error = 0; |
1949 | dir->i_size += BOGO_DIRENT_SIZE; |
1950 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1951 | d_instantiate(dentry, inode); |
1952 | dget(dentry); /* Extra count - pin the dentry in core */ |
1953 | } |
1954 | return error; |
1955 | out_iput: |
1956 | iput(inode); |
1957 | return error; |
1958 | } |
1959 | |
1960 | static int |
1961 | shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) |
1962 | { |
1963 | struct inode *inode; |
1964 | int error = -ENOSPC; |
1965 | |
1966 | inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); |
1967 | if (inode) { |
1968 | error = security_inode_init_security(inode, dir, |
1969 | NULL, |
1970 | shmem_initxattrs, NULL); |
1971 | if (error && error != -EOPNOTSUPP) |
1972 | goto out_iput; |
1973 | error = simple_acl_create(dir, inode); |
1974 | if (error) |
1975 | goto out_iput; |
1976 | d_tmpfile(dentry, inode); |
1977 | } |
1978 | return error; |
1979 | out_iput: |
1980 | iput(inode); |
1981 | return error; |
1982 | } |
1983 | |
1984 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) |
1985 | { |
1986 | int error; |
1987 | |
1988 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
1989 | return error; |
1990 | inc_nlink(dir); |
1991 | return 0; |
1992 | } |
1993 | |
1994 | static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode, |
1995 | bool excl) |
1996 | { |
1997 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
1998 | } |
1999 | |
2000 | /* |
2001 | * Link a file.. |
2002 | */ |
2003 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
2004 | { |
2005 | struct inode *inode = old_dentry->d_inode; |
2006 | int ret; |
2007 | |
2008 | /* |
2009 | * No ordinary (disk based) filesystem counts links as inodes; |
2010 | * but each new link needs a new dentry, pinning lowmem, and |
2011 | * tmpfs dentries cannot be pruned until they are unlinked. |
2012 | */ |
2013 | ret = shmem_reserve_inode(inode->i_sb); |
2014 | if (ret) |
2015 | goto out; |
2016 | |
2017 | dir->i_size += BOGO_DIRENT_SIZE; |
2018 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2019 | inc_nlink(inode); |
2020 | ihold(inode); /* New dentry reference */ |
2021 | dget(dentry); /* Extra pinning count for the created dentry */ |
2022 | d_instantiate(dentry, inode); |
2023 | out: |
2024 | return ret; |
2025 | } |
2026 | |
2027 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
2028 | { |
2029 | struct inode *inode = dentry->d_inode; |
2030 | |
2031 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
2032 | shmem_free_inode(inode->i_sb); |
2033 | |
2034 | dir->i_size -= BOGO_DIRENT_SIZE; |
2035 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2036 | drop_nlink(inode); |
2037 | dput(dentry); /* Undo the count from "create" - this does all the work */ |
2038 | return 0; |
2039 | } |
2040 | |
2041 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
2042 | { |
2043 | if (!simple_empty(dentry)) |
2044 | return -ENOTEMPTY; |
2045 | |
2046 | drop_nlink(dentry->d_inode); |
2047 | drop_nlink(dir); |
2048 | return shmem_unlink(dir, dentry); |
2049 | } |
2050 | |
2051 | /* |
2052 | * The VFS layer already does all the dentry stuff for rename, |
2053 | * we just have to decrement the usage count for the target if |
2054 | * it exists so that the VFS layer correctly free's it when it |
2055 | * gets overwritten. |
2056 | */ |
2057 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
2058 | { |
2059 | struct inode *inode = old_dentry->d_inode; |
2060 | int they_are_dirs = S_ISDIR(inode->i_mode); |
2061 | |
2062 | if (!simple_empty(new_dentry)) |
2063 | return -ENOTEMPTY; |
2064 | |
2065 | if (new_dentry->d_inode) { |
2066 | (void) shmem_unlink(new_dir, new_dentry); |
2067 | if (they_are_dirs) |
2068 | drop_nlink(old_dir); |
2069 | } else if (they_are_dirs) { |
2070 | drop_nlink(old_dir); |
2071 | inc_nlink(new_dir); |
2072 | } |
2073 | |
2074 | old_dir->i_size -= BOGO_DIRENT_SIZE; |
2075 | new_dir->i_size += BOGO_DIRENT_SIZE; |
2076 | old_dir->i_ctime = old_dir->i_mtime = |
2077 | new_dir->i_ctime = new_dir->i_mtime = |
2078 | inode->i_ctime = CURRENT_TIME; |
2079 | return 0; |
2080 | } |
2081 | |
2082 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
2083 | { |
2084 | int error; |
2085 | int len; |
2086 | struct inode *inode; |
2087 | struct page *page; |
2088 | char *kaddr; |
2089 | struct shmem_inode_info *info; |
2090 | |
2091 | len = strlen(symname) + 1; |
2092 | if (len > PAGE_CACHE_SIZE) |
2093 | return -ENAMETOOLONG; |
2094 | |
2095 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
2096 | if (!inode) |
2097 | return -ENOSPC; |
2098 | |
2099 | error = security_inode_init_security(inode, dir, &dentry->d_name, |
2100 | shmem_initxattrs, NULL); |
2101 | if (error) { |
2102 | if (error != -EOPNOTSUPP) { |
2103 | iput(inode); |
2104 | return error; |
2105 | } |
2106 | error = 0; |
2107 | } |
2108 | |
2109 | info = SHMEM_I(inode); |
2110 | inode->i_size = len-1; |
2111 | if (len <= SHORT_SYMLINK_LEN) { |
2112 | info->symlink = kmemdup(symname, len, GFP_KERNEL); |
2113 | if (!info->symlink) { |
2114 | iput(inode); |
2115 | return -ENOMEM; |
2116 | } |
2117 | inode->i_op = &shmem_short_symlink_operations; |
2118 | } else { |
2119 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
2120 | if (error) { |
2121 | iput(inode); |
2122 | return error; |
2123 | } |
2124 | inode->i_mapping->a_ops = &shmem_aops; |
2125 | inode->i_op = &shmem_symlink_inode_operations; |
2126 | kaddr = kmap_atomic(page); |
2127 | memcpy(kaddr, symname, len); |
2128 | kunmap_atomic(kaddr); |
2129 | SetPageUptodate(page); |
2130 | set_page_dirty(page); |
2131 | unlock_page(page); |
2132 | page_cache_release(page); |
2133 | } |
2134 | dir->i_size += BOGO_DIRENT_SIZE; |
2135 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2136 | d_instantiate(dentry, inode); |
2137 | dget(dentry); |
2138 | return 0; |
2139 | } |
2140 | |
2141 | static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) |
2142 | { |
2143 | nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); |
2144 | return NULL; |
2145 | } |
2146 | |
2147 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
2148 | { |
2149 | struct page *page = NULL; |
2150 | int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
2151 | nd_set_link(nd, error ? ERR_PTR(error) : kmap(page)); |
2152 | if (page) |
2153 | unlock_page(page); |
2154 | return page; |
2155 | } |
2156 | |
2157 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
2158 | { |
2159 | if (!IS_ERR(nd_get_link(nd))) { |
2160 | struct page *page = cookie; |
2161 | kunmap(page); |
2162 | mark_page_accessed(page); |
2163 | page_cache_release(page); |
2164 | } |
2165 | } |
2166 | |
2167 | #ifdef CONFIG_TMPFS_XATTR |
2168 | /* |
2169 | * Superblocks without xattr inode operations may get some security.* xattr |
2170 | * support from the LSM "for free". As soon as we have any other xattrs |
2171 | * like ACLs, we also need to implement the security.* handlers at |
2172 | * filesystem level, though. |
2173 | */ |
2174 | |
2175 | /* |
2176 | * Callback for security_inode_init_security() for acquiring xattrs. |
2177 | */ |
2178 | static int shmem_initxattrs(struct inode *inode, |
2179 | const struct xattr *xattr_array, |
2180 | void *fs_info) |
2181 | { |
2182 | struct shmem_inode_info *info = SHMEM_I(inode); |
2183 | const struct xattr *xattr; |
2184 | struct simple_xattr *new_xattr; |
2185 | size_t len; |
2186 | |
2187 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { |
2188 | new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len); |
2189 | if (!new_xattr) |
2190 | return -ENOMEM; |
2191 | |
2192 | len = strlen(xattr->name) + 1; |
2193 | new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len, |
2194 | GFP_KERNEL); |
2195 | if (!new_xattr->name) { |
2196 | kfree(new_xattr); |
2197 | return -ENOMEM; |
2198 | } |
2199 | |
2200 | memcpy(new_xattr->name, XATTR_SECURITY_PREFIX, |
2201 | XATTR_SECURITY_PREFIX_LEN); |
2202 | memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN, |
2203 | xattr->name, len); |
2204 | |
2205 | simple_xattr_list_add(&info->xattrs, new_xattr); |
2206 | } |
2207 | |
2208 | return 0; |
2209 | } |
2210 | |
2211 | static const struct xattr_handler *shmem_xattr_handlers[] = { |
2212 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2213 | &posix_acl_access_xattr_handler, |
2214 | &posix_acl_default_xattr_handler, |
2215 | #endif |
2216 | NULL |
2217 | }; |
2218 | |
2219 | static int shmem_xattr_validate(const char *name) |
2220 | { |
2221 | struct { const char *prefix; size_t len; } arr[] = { |
2222 | { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, |
2223 | { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } |
2224 | }; |
2225 | int i; |
2226 | |
2227 | for (i = 0; i < ARRAY_SIZE(arr); i++) { |
2228 | size_t preflen = arr[i].len; |
2229 | if (strncmp(name, arr[i].prefix, preflen) == 0) { |
2230 | if (!name[preflen]) |
2231 | return -EINVAL; |
2232 | return 0; |
2233 | } |
2234 | } |
2235 | return -EOPNOTSUPP; |
2236 | } |
2237 | |
2238 | static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, |
2239 | void *buffer, size_t size) |
2240 | { |
2241 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2242 | int err; |
2243 | |
2244 | /* |
2245 | * If this is a request for a synthetic attribute in the system.* |
2246 | * namespace use the generic infrastructure to resolve a handler |
2247 | * for it via sb->s_xattr. |
2248 | */ |
2249 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2250 | return generic_getxattr(dentry, name, buffer, size); |
2251 | |
2252 | err = shmem_xattr_validate(name); |
2253 | if (err) |
2254 | return err; |
2255 | |
2256 | return simple_xattr_get(&info->xattrs, name, buffer, size); |
2257 | } |
2258 | |
2259 | static int shmem_setxattr(struct dentry *dentry, const char *name, |
2260 | const void *value, size_t size, int flags) |
2261 | { |
2262 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2263 | int err; |
2264 | |
2265 | /* |
2266 | * If this is a request for a synthetic attribute in the system.* |
2267 | * namespace use the generic infrastructure to resolve a handler |
2268 | * for it via sb->s_xattr. |
2269 | */ |
2270 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2271 | return generic_setxattr(dentry, name, value, size, flags); |
2272 | |
2273 | err = shmem_xattr_validate(name); |
2274 | if (err) |
2275 | return err; |
2276 | |
2277 | return simple_xattr_set(&info->xattrs, name, value, size, flags); |
2278 | } |
2279 | |
2280 | static int shmem_removexattr(struct dentry *dentry, const char *name) |
2281 | { |
2282 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2283 | int err; |
2284 | |
2285 | /* |
2286 | * If this is a request for a synthetic attribute in the system.* |
2287 | * namespace use the generic infrastructure to resolve a handler |
2288 | * for it via sb->s_xattr. |
2289 | */ |
2290 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
2291 | return generic_removexattr(dentry, name); |
2292 | |
2293 | err = shmem_xattr_validate(name); |
2294 | if (err) |
2295 | return err; |
2296 | |
2297 | return simple_xattr_remove(&info->xattrs, name); |
2298 | } |
2299 | |
2300 | static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) |
2301 | { |
2302 | struct shmem_inode_info *info = SHMEM_I(dentry->d_inode); |
2303 | return simple_xattr_list(&info->xattrs, buffer, size); |
2304 | } |
2305 | #endif /* CONFIG_TMPFS_XATTR */ |
2306 | |
2307 | static const struct inode_operations shmem_short_symlink_operations = { |
2308 | .readlink = generic_readlink, |
2309 | .follow_link = shmem_follow_short_symlink, |
2310 | #ifdef CONFIG_TMPFS_XATTR |
2311 | .setxattr = shmem_setxattr, |
2312 | .getxattr = shmem_getxattr, |
2313 | .listxattr = shmem_listxattr, |
2314 | .removexattr = shmem_removexattr, |
2315 | #endif |
2316 | }; |
2317 | |
2318 | static const struct inode_operations shmem_symlink_inode_operations = { |
2319 | .readlink = generic_readlink, |
2320 | .follow_link = shmem_follow_link, |
2321 | .put_link = shmem_put_link, |
2322 | #ifdef CONFIG_TMPFS_XATTR |
2323 | .setxattr = shmem_setxattr, |
2324 | .getxattr = shmem_getxattr, |
2325 | .listxattr = shmem_listxattr, |
2326 | .removexattr = shmem_removexattr, |
2327 | #endif |
2328 | }; |
2329 | |
2330 | static struct dentry *shmem_get_parent(struct dentry *child) |
2331 | { |
2332 | return ERR_PTR(-ESTALE); |
2333 | } |
2334 | |
2335 | static int shmem_match(struct inode *ino, void *vfh) |
2336 | { |
2337 | __u32 *fh = vfh; |
2338 | __u64 inum = fh[2]; |
2339 | inum = (inum << 32) | fh[1]; |
2340 | return ino->i_ino == inum && fh[0] == ino->i_generation; |
2341 | } |
2342 | |
2343 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
2344 | struct fid *fid, int fh_len, int fh_type) |
2345 | { |
2346 | struct inode *inode; |
2347 | struct dentry *dentry = NULL; |
2348 | u64 inum; |
2349 | |
2350 | if (fh_len < 3) |
2351 | return NULL; |
2352 | |
2353 | inum = fid->raw[2]; |
2354 | inum = (inum << 32) | fid->raw[1]; |
2355 | |
2356 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
2357 | shmem_match, fid->raw); |
2358 | if (inode) { |
2359 | dentry = d_find_alias(inode); |
2360 | iput(inode); |
2361 | } |
2362 | |
2363 | return dentry; |
2364 | } |
2365 | |
2366 | static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len, |
2367 | struct inode *parent) |
2368 | { |
2369 | if (*len < 3) { |
2370 | *len = 3; |
2371 | return FILEID_INVALID; |
2372 | } |
2373 | |
2374 | if (inode_unhashed(inode)) { |
2375 | /* Unfortunately insert_inode_hash is not idempotent, |
2376 | * so as we hash inodes here rather than at creation |
2377 | * time, we need a lock to ensure we only try |
2378 | * to do it once |
2379 | */ |
2380 | static DEFINE_SPINLOCK(lock); |
2381 | spin_lock(&lock); |
2382 | if (inode_unhashed(inode)) |
2383 | __insert_inode_hash(inode, |
2384 | inode->i_ino + inode->i_generation); |
2385 | spin_unlock(&lock); |
2386 | } |
2387 | |
2388 | fh[0] = inode->i_generation; |
2389 | fh[1] = inode->i_ino; |
2390 | fh[2] = ((__u64)inode->i_ino) >> 32; |
2391 | |
2392 | *len = 3; |
2393 | return 1; |
2394 | } |
2395 | |
2396 | static const struct export_operations shmem_export_ops = { |
2397 | .get_parent = shmem_get_parent, |
2398 | .encode_fh = shmem_encode_fh, |
2399 | .fh_to_dentry = shmem_fh_to_dentry, |
2400 | }; |
2401 | |
2402 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
2403 | bool remount) |
2404 | { |
2405 | char *this_char, *value, *rest; |
2406 | struct mempolicy *mpol = NULL; |
2407 | uid_t uid; |
2408 | gid_t gid; |
2409 | |
2410 | while (options != NULL) { |
2411 | this_char = options; |
2412 | for (;;) { |
2413 | /* |
2414 | * NUL-terminate this option: unfortunately, |
2415 | * mount options form a comma-separated list, |
2416 | * but mpol's nodelist may also contain commas. |
2417 | */ |
2418 | options = strchr(options, ','); |
2419 | if (options == NULL) |
2420 | break; |
2421 | options++; |
2422 | if (!isdigit(*options)) { |
2423 | options[-1] = '\0'; |
2424 | break; |
2425 | } |
2426 | } |
2427 | if (!*this_char) |
2428 | continue; |
2429 | if ((value = strchr(this_char,'=')) != NULL) { |
2430 | *value++ = 0; |
2431 | } else { |
2432 | printk(KERN_ERR |
2433 | "tmpfs: No value for mount option '%s'\n", |
2434 | this_char); |
2435 | goto error; |
2436 | } |
2437 | |
2438 | if (!strcmp(this_char,"size")) { |
2439 | unsigned long long size; |
2440 | size = memparse(value,&rest); |
2441 | if (*rest == '%') { |
2442 | size <<= PAGE_SHIFT; |
2443 | size *= totalram_pages; |
2444 | do_div(size, 100); |
2445 | rest++; |
2446 | } |
2447 | if (*rest) |
2448 | goto bad_val; |
2449 | sbinfo->max_blocks = |
2450 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
2451 | } else if (!strcmp(this_char,"nr_blocks")) { |
2452 | sbinfo->max_blocks = memparse(value, &rest); |
2453 | if (*rest) |
2454 | goto bad_val; |
2455 | } else if (!strcmp(this_char,"nr_inodes")) { |
2456 | sbinfo->max_inodes = memparse(value, &rest); |
2457 | if (*rest) |
2458 | goto bad_val; |
2459 | } else if (!strcmp(this_char,"mode")) { |
2460 | if (remount) |
2461 | continue; |
2462 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
2463 | if (*rest) |
2464 | goto bad_val; |
2465 | } else if (!strcmp(this_char,"uid")) { |
2466 | if (remount) |
2467 | continue; |
2468 | uid = simple_strtoul(value, &rest, 0); |
2469 | if (*rest) |
2470 | goto bad_val; |
2471 | sbinfo->uid = make_kuid(current_user_ns(), uid); |
2472 | if (!uid_valid(sbinfo->uid)) |
2473 | goto bad_val; |
2474 | } else if (!strcmp(this_char,"gid")) { |
2475 | if (remount) |
2476 | continue; |
2477 | gid = simple_strtoul(value, &rest, 0); |
2478 | if (*rest) |
2479 | goto bad_val; |
2480 | sbinfo->gid = make_kgid(current_user_ns(), gid); |
2481 | if (!gid_valid(sbinfo->gid)) |
2482 | goto bad_val; |
2483 | } else if (!strcmp(this_char,"mpol")) { |
2484 | mpol_put(mpol); |
2485 | mpol = NULL; |
2486 | if (mpol_parse_str(value, &mpol)) |
2487 | goto bad_val; |
2488 | } else { |
2489 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
2490 | this_char); |
2491 | goto error; |
2492 | } |
2493 | } |
2494 | sbinfo->mpol = mpol; |
2495 | return 0; |
2496 | |
2497 | bad_val: |
2498 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
2499 | value, this_char); |
2500 | error: |
2501 | mpol_put(mpol); |
2502 | return 1; |
2503 | |
2504 | } |
2505 | |
2506 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
2507 | { |
2508 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2509 | struct shmem_sb_info config = *sbinfo; |
2510 | unsigned long inodes; |
2511 | int error = -EINVAL; |
2512 | |
2513 | config.mpol = NULL; |
2514 | if (shmem_parse_options(data, &config, true)) |
2515 | return error; |
2516 | |
2517 | spin_lock(&sbinfo->stat_lock); |
2518 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
2519 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) |
2520 | goto out; |
2521 | if (config.max_inodes < inodes) |
2522 | goto out; |
2523 | /* |
2524 | * Those tests disallow limited->unlimited while any are in use; |
2525 | * but we must separately disallow unlimited->limited, because |
2526 | * in that case we have no record of how much is already in use. |
2527 | */ |
2528 | if (config.max_blocks && !sbinfo->max_blocks) |
2529 | goto out; |
2530 | if (config.max_inodes && !sbinfo->max_inodes) |
2531 | goto out; |
2532 | |
2533 | error = 0; |
2534 | sbinfo->max_blocks = config.max_blocks; |
2535 | sbinfo->max_inodes = config.max_inodes; |
2536 | sbinfo->free_inodes = config.max_inodes - inodes; |
2537 | |
2538 | /* |
2539 | * Preserve previous mempolicy unless mpol remount option was specified. |
2540 | */ |
2541 | if (config.mpol) { |
2542 | mpol_put(sbinfo->mpol); |
2543 | sbinfo->mpol = config.mpol; /* transfers initial ref */ |
2544 | } |
2545 | out: |
2546 | spin_unlock(&sbinfo->stat_lock); |
2547 | return error; |
2548 | } |
2549 | |
2550 | static int shmem_show_options(struct seq_file *seq, struct dentry *root) |
2551 | { |
2552 | struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb); |
2553 | |
2554 | if (sbinfo->max_blocks != shmem_default_max_blocks()) |
2555 | seq_printf(seq, ",size=%luk", |
2556 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
2557 | if (sbinfo->max_inodes != shmem_default_max_inodes()) |
2558 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
2559 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
2560 | seq_printf(seq, ",mode=%03ho", sbinfo->mode); |
2561 | if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID)) |
2562 | seq_printf(seq, ",uid=%u", |
2563 | from_kuid_munged(&init_user_ns, sbinfo->uid)); |
2564 | if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID)) |
2565 | seq_printf(seq, ",gid=%u", |
2566 | from_kgid_munged(&init_user_ns, sbinfo->gid)); |
2567 | shmem_show_mpol(seq, sbinfo->mpol); |
2568 | return 0; |
2569 | } |
2570 | #endif /* CONFIG_TMPFS */ |
2571 | |
2572 | static void shmem_put_super(struct super_block *sb) |
2573 | { |
2574 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2575 | |
2576 | percpu_counter_destroy(&sbinfo->used_blocks); |
2577 | mpol_put(sbinfo->mpol); |
2578 | kfree(sbinfo); |
2579 | sb->s_fs_info = NULL; |
2580 | } |
2581 | |
2582 | int shmem_fill_super(struct super_block *sb, void *data, int silent) |
2583 | { |
2584 | struct inode *inode; |
2585 | struct shmem_sb_info *sbinfo; |
2586 | int err = -ENOMEM; |
2587 | |
2588 | /* Round up to L1_CACHE_BYTES to resist false sharing */ |
2589 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
2590 | L1_CACHE_BYTES), GFP_KERNEL); |
2591 | if (!sbinfo) |
2592 | return -ENOMEM; |
2593 | |
2594 | sbinfo->mode = S_IRWXUGO | S_ISVTX; |
2595 | sbinfo->uid = current_fsuid(); |
2596 | sbinfo->gid = current_fsgid(); |
2597 | sb->s_fs_info = sbinfo; |
2598 | |
2599 | #ifdef CONFIG_TMPFS |
2600 | /* |
2601 | * Per default we only allow half of the physical ram per |
2602 | * tmpfs instance, limiting inodes to one per page of lowmem; |
2603 | * but the internal instance is left unlimited. |
2604 | */ |
2605 | if (!(sb->s_flags & MS_KERNMOUNT)) { |
2606 | sbinfo->max_blocks = shmem_default_max_blocks(); |
2607 | sbinfo->max_inodes = shmem_default_max_inodes(); |
2608 | if (shmem_parse_options(data, sbinfo, false)) { |
2609 | err = -EINVAL; |
2610 | goto failed; |
2611 | } |
2612 | } else { |
2613 | sb->s_flags |= MS_NOUSER; |
2614 | } |
2615 | sb->s_export_op = &shmem_export_ops; |
2616 | sb->s_flags |= MS_NOSEC; |
2617 | #else |
2618 | sb->s_flags |= MS_NOUSER; |
2619 | #endif |
2620 | |
2621 | spin_lock_init(&sbinfo->stat_lock); |
2622 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) |
2623 | goto failed; |
2624 | sbinfo->free_inodes = sbinfo->max_inodes; |
2625 | |
2626 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
2627 | sb->s_blocksize = PAGE_CACHE_SIZE; |
2628 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
2629 | sb->s_magic = TMPFS_MAGIC; |
2630 | sb->s_op = &shmem_ops; |
2631 | sb->s_time_gran = 1; |
2632 | #ifdef CONFIG_TMPFS_XATTR |
2633 | sb->s_xattr = shmem_xattr_handlers; |
2634 | #endif |
2635 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2636 | sb->s_flags |= MS_POSIXACL; |
2637 | #endif |
2638 | |
2639 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
2640 | if (!inode) |
2641 | goto failed; |
2642 | inode->i_uid = sbinfo->uid; |
2643 | inode->i_gid = sbinfo->gid; |
2644 | sb->s_root = d_make_root(inode); |
2645 | if (!sb->s_root) |
2646 | goto failed; |
2647 | return 0; |
2648 | |
2649 | failed: |
2650 | shmem_put_super(sb); |
2651 | return err; |
2652 | } |
2653 | |
2654 | static struct kmem_cache *shmem_inode_cachep; |
2655 | |
2656 | static struct inode *shmem_alloc_inode(struct super_block *sb) |
2657 | { |
2658 | struct shmem_inode_info *info; |
2659 | info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
2660 | if (!info) |
2661 | return NULL; |
2662 | return &info->vfs_inode; |
2663 | } |
2664 | |
2665 | static void shmem_destroy_callback(struct rcu_head *head) |
2666 | { |
2667 | struct inode *inode = container_of(head, struct inode, i_rcu); |
2668 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
2669 | } |
2670 | |
2671 | static void shmem_destroy_inode(struct inode *inode) |
2672 | { |
2673 | if (S_ISREG(inode->i_mode)) |
2674 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
2675 | call_rcu(&inode->i_rcu, shmem_destroy_callback); |
2676 | } |
2677 | |
2678 | static void shmem_init_inode(void *foo) |
2679 | { |
2680 | struct shmem_inode_info *info = foo; |
2681 | inode_init_once(&info->vfs_inode); |
2682 | } |
2683 | |
2684 | static int shmem_init_inodecache(void) |
2685 | { |
2686 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
2687 | sizeof(struct shmem_inode_info), |
2688 | 0, SLAB_PANIC, shmem_init_inode); |
2689 | return 0; |
2690 | } |
2691 | |
2692 | static void shmem_destroy_inodecache(void) |
2693 | { |
2694 | kmem_cache_destroy(shmem_inode_cachep); |
2695 | } |
2696 | |
2697 | static const struct address_space_operations shmem_aops = { |
2698 | .writepage = shmem_writepage, |
2699 | .set_page_dirty = __set_page_dirty_no_writeback, |
2700 | #ifdef CONFIG_TMPFS |
2701 | .write_begin = shmem_write_begin, |
2702 | .write_end = shmem_write_end, |
2703 | #endif |
2704 | .migratepage = migrate_page, |
2705 | .error_remove_page = generic_error_remove_page, |
2706 | }; |
2707 | |
2708 | static const struct file_operations shmem_file_operations = { |
2709 | .mmap = shmem_mmap, |
2710 | #ifdef CONFIG_TMPFS |
2711 | .llseek = shmem_file_llseek, |
2712 | .read = new_sync_read, |
2713 | .write = new_sync_write, |
2714 | .read_iter = shmem_file_read_iter, |
2715 | .write_iter = generic_file_write_iter, |
2716 | .fsync = noop_fsync, |
2717 | .splice_read = shmem_file_splice_read, |
2718 | .splice_write = iter_file_splice_write, |
2719 | .fallocate = shmem_fallocate, |
2720 | #endif |
2721 | }; |
2722 | |
2723 | static const struct inode_operations shmem_inode_operations = { |
2724 | .setattr = shmem_setattr, |
2725 | #ifdef CONFIG_TMPFS_XATTR |
2726 | .setxattr = shmem_setxattr, |
2727 | .getxattr = shmem_getxattr, |
2728 | .listxattr = shmem_listxattr, |
2729 | .removexattr = shmem_removexattr, |
2730 | .set_acl = simple_set_acl, |
2731 | #endif |
2732 | }; |
2733 | |
2734 | static const struct inode_operations shmem_dir_inode_operations = { |
2735 | #ifdef CONFIG_TMPFS |
2736 | .create = shmem_create, |
2737 | .lookup = simple_lookup, |
2738 | .link = shmem_link, |
2739 | .unlink = shmem_unlink, |
2740 | .symlink = shmem_symlink, |
2741 | .mkdir = shmem_mkdir, |
2742 | .rmdir = shmem_rmdir, |
2743 | .mknod = shmem_mknod, |
2744 | .rename = shmem_rename, |
2745 | .tmpfile = shmem_tmpfile, |
2746 | #endif |
2747 | #ifdef CONFIG_TMPFS_XATTR |
2748 | .setxattr = shmem_setxattr, |
2749 | .getxattr = shmem_getxattr, |
2750 | .listxattr = shmem_listxattr, |
2751 | .removexattr = shmem_removexattr, |
2752 | #endif |
2753 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2754 | .setattr = shmem_setattr, |
2755 | .set_acl = simple_set_acl, |
2756 | #endif |
2757 | }; |
2758 | |
2759 | static const struct inode_operations shmem_special_inode_operations = { |
2760 | #ifdef CONFIG_TMPFS_XATTR |
2761 | .setxattr = shmem_setxattr, |
2762 | .getxattr = shmem_getxattr, |
2763 | .listxattr = shmem_listxattr, |
2764 | .removexattr = shmem_removexattr, |
2765 | #endif |
2766 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2767 | .setattr = shmem_setattr, |
2768 | .set_acl = simple_set_acl, |
2769 | #endif |
2770 | }; |
2771 | |
2772 | static const struct super_operations shmem_ops = { |
2773 | .alloc_inode = shmem_alloc_inode, |
2774 | .destroy_inode = shmem_destroy_inode, |
2775 | #ifdef CONFIG_TMPFS |
2776 | .statfs = shmem_statfs, |
2777 | .remount_fs = shmem_remount_fs, |
2778 | .show_options = shmem_show_options, |
2779 | #endif |
2780 | .evict_inode = shmem_evict_inode, |
2781 | .drop_inode = generic_delete_inode, |
2782 | .put_super = shmem_put_super, |
2783 | }; |
2784 | |
2785 | static const struct vm_operations_struct shmem_vm_ops = { |
2786 | .fault = shmem_fault, |
2787 | .map_pages = filemap_map_pages, |
2788 | #ifdef CONFIG_NUMA |
2789 | .set_policy = shmem_set_policy, |
2790 | .get_policy = shmem_get_policy, |
2791 | #endif |
2792 | .remap_pages = generic_file_remap_pages, |
2793 | }; |
2794 | |
2795 | static struct dentry *shmem_mount(struct file_system_type *fs_type, |
2796 | int flags, const char *dev_name, void *data) |
2797 | { |
2798 | return mount_nodev(fs_type, flags, data, shmem_fill_super); |
2799 | } |
2800 | |
2801 | static struct file_system_type shmem_fs_type = { |
2802 | .owner = THIS_MODULE, |
2803 | .name = "tmpfs", |
2804 | .mount = shmem_mount, |
2805 | .kill_sb = kill_litter_super, |
2806 | .fs_flags = FS_USERNS_MOUNT, |
2807 | }; |
2808 | |
2809 | int __init shmem_init(void) |
2810 | { |
2811 | int error; |
2812 | |
2813 | /* If rootfs called this, don't re-init */ |
2814 | if (shmem_inode_cachep) |
2815 | return 0; |
2816 | |
2817 | error = bdi_init(&shmem_backing_dev_info); |
2818 | if (error) |
2819 | goto out4; |
2820 | |
2821 | error = shmem_init_inodecache(); |
2822 | if (error) |
2823 | goto out3; |
2824 | |
2825 | error = register_filesystem(&shmem_fs_type); |
2826 | if (error) { |
2827 | printk(KERN_ERR "Could not register tmpfs\n"); |
2828 | goto out2; |
2829 | } |
2830 | |
2831 | shm_mnt = kern_mount(&shmem_fs_type); |
2832 | if (IS_ERR(shm_mnt)) { |
2833 | error = PTR_ERR(shm_mnt); |
2834 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
2835 | goto out1; |
2836 | } |
2837 | return 0; |
2838 | |
2839 | out1: |
2840 | unregister_filesystem(&shmem_fs_type); |
2841 | out2: |
2842 | shmem_destroy_inodecache(); |
2843 | out3: |
2844 | bdi_destroy(&shmem_backing_dev_info); |
2845 | out4: |
2846 | shm_mnt = ERR_PTR(error); |
2847 | return error; |
2848 | } |
2849 | |
2850 | #else /* !CONFIG_SHMEM */ |
2851 | |
2852 | /* |
2853 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
2854 | * |
2855 | * This is intended for small system where the benefits of the full |
2856 | * shmem code (swap-backed and resource-limited) are outweighed by |
2857 | * their complexity. On systems without swap this code should be |
2858 | * effectively equivalent, but much lighter weight. |
2859 | */ |
2860 | |
2861 | static struct file_system_type shmem_fs_type = { |
2862 | .name = "tmpfs", |
2863 | .mount = ramfs_mount, |
2864 | .kill_sb = kill_litter_super, |
2865 | .fs_flags = FS_USERNS_MOUNT, |
2866 | }; |
2867 | |
2868 | int __init shmem_init(void) |
2869 | { |
2870 | BUG_ON(register_filesystem(&shmem_fs_type) != 0); |
2871 | |
2872 | shm_mnt = kern_mount(&shmem_fs_type); |
2873 | BUG_ON(IS_ERR(shm_mnt)); |
2874 | |
2875 | return 0; |
2876 | } |
2877 | |
2878 | int shmem_unuse(swp_entry_t swap, struct page *page) |
2879 | { |
2880 | return 0; |
2881 | } |
2882 | |
2883 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
2884 | { |
2885 | return 0; |
2886 | } |
2887 | |
2888 | void shmem_unlock_mapping(struct address_space *mapping) |
2889 | { |
2890 | } |
2891 | |
2892 | void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
2893 | { |
2894 | truncate_inode_pages_range(inode->i_mapping, lstart, lend); |
2895 | } |
2896 | EXPORT_SYMBOL_GPL(shmem_truncate_range); |
2897 | |
2898 | #define shmem_vm_ops generic_file_vm_ops |
2899 | #define shmem_file_operations ramfs_file_operations |
2900 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) |
2901 | #define shmem_acct_size(flags, size) 0 |
2902 | #define shmem_unacct_size(flags, size) do {} while (0) |
2903 | |
2904 | #endif /* CONFIG_SHMEM */ |
2905 | |
2906 | /* common code */ |
2907 | |
2908 | static struct dentry_operations anon_ops = { |
2909 | .d_dname = simple_dname |
2910 | }; |
2911 | |
2912 | static struct file *__shmem_file_setup(const char *name, loff_t size, |
2913 | unsigned long flags, unsigned int i_flags) |
2914 | { |
2915 | struct file *res; |
2916 | struct inode *inode; |
2917 | struct path path; |
2918 | struct super_block *sb; |
2919 | struct qstr this; |
2920 | |
2921 | if (IS_ERR(shm_mnt)) |
2922 | return ERR_CAST(shm_mnt); |
2923 | |
2924 | if (size < 0 || size > MAX_LFS_FILESIZE) |
2925 | return ERR_PTR(-EINVAL); |
2926 | |
2927 | if (shmem_acct_size(flags, size)) |
2928 | return ERR_PTR(-ENOMEM); |
2929 | |
2930 | res = ERR_PTR(-ENOMEM); |
2931 | this.name = name; |
2932 | this.len = strlen(name); |
2933 | this.hash = 0; /* will go */ |
2934 | sb = shm_mnt->mnt_sb; |
2935 | path.dentry = d_alloc_pseudo(sb, &this); |
2936 | if (!path.dentry) |
2937 | goto put_memory; |
2938 | d_set_d_op(path.dentry, &anon_ops); |
2939 | path.mnt = mntget(shm_mnt); |
2940 | |
2941 | res = ERR_PTR(-ENOSPC); |
2942 | inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); |
2943 | if (!inode) |
2944 | goto put_dentry; |
2945 | |
2946 | inode->i_flags |= i_flags; |
2947 | d_instantiate(path.dentry, inode); |
2948 | inode->i_size = size; |
2949 | clear_nlink(inode); /* It is unlinked */ |
2950 | res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size)); |
2951 | if (IS_ERR(res)) |
2952 | goto put_dentry; |
2953 | |
2954 | res = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
2955 | &shmem_file_operations); |
2956 | if (IS_ERR(res)) |
2957 | goto put_dentry; |
2958 | |
2959 | return res; |
2960 | |
2961 | put_dentry: |
2962 | path_put(&path); |
2963 | put_memory: |
2964 | shmem_unacct_size(flags, size); |
2965 | return res; |
2966 | } |
2967 | |
2968 | /** |
2969 | * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be |
2970 | * kernel internal. There will be NO LSM permission checks against the |
2971 | * underlying inode. So users of this interface must do LSM checks at a |
2972 | * higher layer. The one user is the big_key implementation. LSM checks |
2973 | * are provided at the key level rather than the inode level. |
2974 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2975 | * @size: size to be set for the file |
2976 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2977 | */ |
2978 | struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags) |
2979 | { |
2980 | return __shmem_file_setup(name, size, flags, S_PRIVATE); |
2981 | } |
2982 | |
2983 | /** |
2984 | * shmem_file_setup - get an unlinked file living in tmpfs |
2985 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2986 | * @size: size to be set for the file |
2987 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2988 | */ |
2989 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
2990 | { |
2991 | return __shmem_file_setup(name, size, flags, 0); |
2992 | } |
2993 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
2994 | |
2995 | /** |
2996 | * shmem_zero_setup - setup a shared anonymous mapping |
2997 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
2998 | */ |
2999 | int shmem_zero_setup(struct vm_area_struct *vma) |
3000 | { |
3001 | struct file *file; |
3002 | loff_t size = vma->vm_end - vma->vm_start; |
3003 | |
3004 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
3005 | if (IS_ERR(file)) |
3006 | return PTR_ERR(file); |
3007 | |
3008 | if (vma->vm_file) |
3009 | fput(vma->vm_file); |
3010 | vma->vm_file = file; |
3011 | vma->vm_ops = &shmem_vm_ops; |
3012 | return 0; |
3013 | } |
3014 | |
3015 | /** |
3016 | * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. |
3017 | * @mapping: the page's address_space |
3018 | * @index: the page index |
3019 | * @gfp: the page allocator flags to use if allocating |
3020 | * |
3021 | * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", |
3022 | * with any new page allocations done using the specified allocation flags. |
3023 | * But read_cache_page_gfp() uses the ->readpage() method: which does not |
3024 | * suit tmpfs, since it may have pages in swapcache, and needs to find those |
3025 | * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. |
3026 | * |
3027 | * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in |
3028 | * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. |
3029 | */ |
3030 | struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, |
3031 | pgoff_t index, gfp_t gfp) |
3032 | { |
3033 | #ifdef CONFIG_SHMEM |
3034 | struct inode *inode = mapping->host; |
3035 | struct page *page; |
3036 | int error; |
3037 | |
3038 | BUG_ON(mapping->a_ops != &shmem_aops); |
3039 | error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); |
3040 | if (error) |
3041 | page = ERR_PTR(error); |
3042 | else |
3043 | unlock_page(page); |
3044 | return page; |
3045 | #else |
3046 | /* |
3047 | * The tiny !SHMEM case uses ramfs without swap |
3048 | */ |
3049 | return read_cache_page_gfp(mapping, index, gfp); |
3050 | #endif |
3051 | } |
3052 | EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp); |
3053 |
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Tags:
od-2011-09-04
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v2.6.34-rc5
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