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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) 2002-2005 Hugh Dickins. |
10 | * Copyright (C) 2002-2005 VERITAS Software Corporation. |
11 | * Copyright (C) 2004 Andi Kleen, SuSE Labs |
12 | * |
13 | * Extended attribute support for tmpfs: |
14 | * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> |
15 | * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
16 | * |
17 | * tiny-shmem: |
18 | * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> |
19 | * |
20 | * This file is released under the GPL. |
21 | */ |
22 | |
23 | #include <linux/fs.h> |
24 | #include <linux/init.h> |
25 | #include <linux/vfs.h> |
26 | #include <linux/mount.h> |
27 | #include <linux/pagemap.h> |
28 | #include <linux/file.h> |
29 | #include <linux/mm.h> |
30 | #include <linux/module.h> |
31 | #include <linux/swap.h> |
32 | |
33 | static struct vfsmount *shm_mnt; |
34 | |
35 | #ifdef CONFIG_SHMEM |
36 | /* |
37 | * This virtual memory filesystem is heavily based on the ramfs. It |
38 | * extends ramfs by the ability to use swap and honor resource limits |
39 | * which makes it a completely usable filesystem. |
40 | */ |
41 | |
42 | #include <linux/xattr.h> |
43 | #include <linux/exportfs.h> |
44 | #include <linux/posix_acl.h> |
45 | #include <linux/generic_acl.h> |
46 | #include <linux/mman.h> |
47 | #include <linux/string.h> |
48 | #include <linux/slab.h> |
49 | #include <linux/backing-dev.h> |
50 | #include <linux/shmem_fs.h> |
51 | #include <linux/writeback.h> |
52 | #include <linux/blkdev.h> |
53 | #include <linux/security.h> |
54 | #include <linux/swapops.h> |
55 | #include <linux/mempolicy.h> |
56 | #include <linux/namei.h> |
57 | #include <linux/ctype.h> |
58 | #include <linux/migrate.h> |
59 | #include <linux/highmem.h> |
60 | #include <linux/seq_file.h> |
61 | #include <linux/magic.h> |
62 | |
63 | #include <asm/uaccess.h> |
64 | #include <asm/div64.h> |
65 | #include <asm/pgtable.h> |
66 | |
67 | /* |
68 | * The maximum size of a shmem/tmpfs file is limited by the maximum size of |
69 | * its triple-indirect swap vector - see illustration at shmem_swp_entry(). |
70 | * |
71 | * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, |
72 | * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum |
73 | * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, |
74 | * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. |
75 | * |
76 | * We use / and * instead of shifts in the definitions below, so that the swap |
77 | * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. |
78 | */ |
79 | #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) |
80 | #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) |
81 | |
82 | #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) |
83 | #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) |
84 | |
85 | #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) |
86 | #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) |
87 | |
88 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
89 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
90 | |
91 | /* info->flags needs VM_flags to handle pagein/truncate races efficiently */ |
92 | #define SHMEM_PAGEIN VM_READ |
93 | #define SHMEM_TRUNCATE VM_WRITE |
94 | |
95 | /* Definition to limit shmem_truncate's steps between cond_rescheds */ |
96 | #define LATENCY_LIMIT 64 |
97 | |
98 | /* Pretend that each entry is of this size in directory's i_size */ |
99 | #define BOGO_DIRENT_SIZE 20 |
100 | |
101 | /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ |
102 | enum sgp_type { |
103 | SGP_READ, /* don't exceed i_size, don't allocate page */ |
104 | SGP_CACHE, /* don't exceed i_size, may allocate page */ |
105 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
106 | SGP_WRITE, /* may exceed i_size, may allocate page */ |
107 | }; |
108 | |
109 | #ifdef CONFIG_TMPFS |
110 | static unsigned long shmem_default_max_blocks(void) |
111 | { |
112 | return totalram_pages / 2; |
113 | } |
114 | |
115 | static unsigned long shmem_default_max_inodes(void) |
116 | { |
117 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
118 | } |
119 | #endif |
120 | |
121 | static int shmem_getpage(struct inode *inode, unsigned long idx, |
122 | struct page **pagep, enum sgp_type sgp, int *type); |
123 | |
124 | static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) |
125 | { |
126 | /* |
127 | * The above definition of ENTRIES_PER_PAGE, and the use of |
128 | * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: |
129 | * might be reconsidered if it ever diverges from PAGE_SIZE. |
130 | * |
131 | * Mobility flags are masked out as swap vectors cannot move |
132 | */ |
133 | return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, |
134 | PAGE_CACHE_SHIFT-PAGE_SHIFT); |
135 | } |
136 | |
137 | static inline void shmem_dir_free(struct page *page) |
138 | { |
139 | __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); |
140 | } |
141 | |
142 | static struct page **shmem_dir_map(struct page *page) |
143 | { |
144 | return (struct page **)kmap_atomic(page, KM_USER0); |
145 | } |
146 | |
147 | static inline void shmem_dir_unmap(struct page **dir) |
148 | { |
149 | kunmap_atomic(dir, KM_USER0); |
150 | } |
151 | |
152 | static swp_entry_t *shmem_swp_map(struct page *page) |
153 | { |
154 | return (swp_entry_t *)kmap_atomic(page, KM_USER1); |
155 | } |
156 | |
157 | static inline void shmem_swp_balance_unmap(void) |
158 | { |
159 | /* |
160 | * When passing a pointer to an i_direct entry, to code which |
161 | * also handles indirect entries and so will shmem_swp_unmap, |
162 | * we must arrange for the preempt count to remain in balance. |
163 | * What kmap_atomic of a lowmem page does depends on config |
164 | * and architecture, so pretend to kmap_atomic some lowmem page. |
165 | */ |
166 | (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); |
167 | } |
168 | |
169 | static inline void shmem_swp_unmap(swp_entry_t *entry) |
170 | { |
171 | kunmap_atomic(entry, KM_USER1); |
172 | } |
173 | |
174 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
175 | { |
176 | return sb->s_fs_info; |
177 | } |
178 | |
179 | /* |
180 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
181 | * for shared memory and for shared anonymous (/dev/zero) mappings |
182 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
183 | * consistent with the pre-accounting of private mappings ... |
184 | */ |
185 | static inline int shmem_acct_size(unsigned long flags, loff_t size) |
186 | { |
187 | return (flags & VM_NORESERVE) ? |
188 | 0 : security_vm_enough_memory_kern(VM_ACCT(size)); |
189 | } |
190 | |
191 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
192 | { |
193 | if (!(flags & VM_NORESERVE)) |
194 | vm_unacct_memory(VM_ACCT(size)); |
195 | } |
196 | |
197 | /* |
198 | * ... whereas tmpfs objects are accounted incrementally as |
199 | * pages are allocated, in order to allow huge sparse files. |
200 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
201 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
202 | */ |
203 | static inline int shmem_acct_block(unsigned long flags) |
204 | { |
205 | return (flags & VM_NORESERVE) ? |
206 | security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
207 | } |
208 | |
209 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
210 | { |
211 | if (flags & VM_NORESERVE) |
212 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
213 | } |
214 | |
215 | static const struct super_operations shmem_ops; |
216 | static const struct address_space_operations shmem_aops; |
217 | static const struct file_operations shmem_file_operations; |
218 | static const struct inode_operations shmem_inode_operations; |
219 | static const struct inode_operations shmem_dir_inode_operations; |
220 | static const struct inode_operations shmem_special_inode_operations; |
221 | static const struct vm_operations_struct shmem_vm_ops; |
222 | |
223 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
224 | .ra_pages = 0, /* No readahead */ |
225 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
226 | .unplug_io_fn = default_unplug_io_fn, |
227 | }; |
228 | |
229 | static LIST_HEAD(shmem_swaplist); |
230 | static DEFINE_MUTEX(shmem_swaplist_mutex); |
231 | |
232 | static void shmem_free_blocks(struct inode *inode, long pages) |
233 | { |
234 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
235 | if (sbinfo->max_blocks) { |
236 | spin_lock(&sbinfo->stat_lock); |
237 | sbinfo->free_blocks += pages; |
238 | inode->i_blocks -= pages*BLOCKS_PER_PAGE; |
239 | spin_unlock(&sbinfo->stat_lock); |
240 | } |
241 | } |
242 | |
243 | static int shmem_reserve_inode(struct super_block *sb) |
244 | { |
245 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
246 | if (sbinfo->max_inodes) { |
247 | spin_lock(&sbinfo->stat_lock); |
248 | if (!sbinfo->free_inodes) { |
249 | spin_unlock(&sbinfo->stat_lock); |
250 | return -ENOSPC; |
251 | } |
252 | sbinfo->free_inodes--; |
253 | spin_unlock(&sbinfo->stat_lock); |
254 | } |
255 | return 0; |
256 | } |
257 | |
258 | static void shmem_free_inode(struct super_block *sb) |
259 | { |
260 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
261 | if (sbinfo->max_inodes) { |
262 | spin_lock(&sbinfo->stat_lock); |
263 | sbinfo->free_inodes++; |
264 | spin_unlock(&sbinfo->stat_lock); |
265 | } |
266 | } |
267 | |
268 | /** |
269 | * shmem_recalc_inode - recalculate the size of an inode |
270 | * @inode: inode to recalc |
271 | * |
272 | * We have to calculate the free blocks since the mm can drop |
273 | * undirtied hole pages behind our back. |
274 | * |
275 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
276 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
277 | * |
278 | * It has to be called with the spinlock held. |
279 | */ |
280 | static void shmem_recalc_inode(struct inode *inode) |
281 | { |
282 | struct shmem_inode_info *info = SHMEM_I(inode); |
283 | long freed; |
284 | |
285 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
286 | if (freed > 0) { |
287 | info->alloced -= freed; |
288 | shmem_unacct_blocks(info->flags, freed); |
289 | shmem_free_blocks(inode, freed); |
290 | } |
291 | } |
292 | |
293 | /** |
294 | * shmem_swp_entry - find the swap vector position in the info structure |
295 | * @info: info structure for the inode |
296 | * @index: index of the page to find |
297 | * @page: optional page to add to the structure. Has to be preset to |
298 | * all zeros |
299 | * |
300 | * If there is no space allocated yet it will return NULL when |
301 | * page is NULL, else it will use the page for the needed block, |
302 | * setting it to NULL on return to indicate that it has been used. |
303 | * |
304 | * The swap vector is organized the following way: |
305 | * |
306 | * There are SHMEM_NR_DIRECT entries directly stored in the |
307 | * shmem_inode_info structure. So small files do not need an addional |
308 | * allocation. |
309 | * |
310 | * For pages with index > SHMEM_NR_DIRECT there is the pointer |
311 | * i_indirect which points to a page which holds in the first half |
312 | * doubly indirect blocks, in the second half triple indirect blocks: |
313 | * |
314 | * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the |
315 | * following layout (for SHMEM_NR_DIRECT == 16): |
316 | * |
317 | * i_indirect -> dir --> 16-19 |
318 | * | +-> 20-23 |
319 | * | |
320 | * +-->dir2 --> 24-27 |
321 | * | +-> 28-31 |
322 | * | +-> 32-35 |
323 | * | +-> 36-39 |
324 | * | |
325 | * +-->dir3 --> 40-43 |
326 | * +-> 44-47 |
327 | * +-> 48-51 |
328 | * +-> 52-55 |
329 | */ |
330 | static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) |
331 | { |
332 | unsigned long offset; |
333 | struct page **dir; |
334 | struct page *subdir; |
335 | |
336 | if (index < SHMEM_NR_DIRECT) { |
337 | shmem_swp_balance_unmap(); |
338 | return info->i_direct+index; |
339 | } |
340 | if (!info->i_indirect) { |
341 | if (page) { |
342 | info->i_indirect = *page; |
343 | *page = NULL; |
344 | } |
345 | return NULL; /* need another page */ |
346 | } |
347 | |
348 | index -= SHMEM_NR_DIRECT; |
349 | offset = index % ENTRIES_PER_PAGE; |
350 | index /= ENTRIES_PER_PAGE; |
351 | dir = shmem_dir_map(info->i_indirect); |
352 | |
353 | if (index >= ENTRIES_PER_PAGE/2) { |
354 | index -= ENTRIES_PER_PAGE/2; |
355 | dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; |
356 | index %= ENTRIES_PER_PAGE; |
357 | subdir = *dir; |
358 | if (!subdir) { |
359 | if (page) { |
360 | *dir = *page; |
361 | *page = NULL; |
362 | } |
363 | shmem_dir_unmap(dir); |
364 | return NULL; /* need another page */ |
365 | } |
366 | shmem_dir_unmap(dir); |
367 | dir = shmem_dir_map(subdir); |
368 | } |
369 | |
370 | dir += index; |
371 | subdir = *dir; |
372 | if (!subdir) { |
373 | if (!page || !(subdir = *page)) { |
374 | shmem_dir_unmap(dir); |
375 | return NULL; /* need a page */ |
376 | } |
377 | *dir = subdir; |
378 | *page = NULL; |
379 | } |
380 | shmem_dir_unmap(dir); |
381 | return shmem_swp_map(subdir) + offset; |
382 | } |
383 | |
384 | static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) |
385 | { |
386 | long incdec = value? 1: -1; |
387 | |
388 | entry->val = value; |
389 | info->swapped += incdec; |
390 | if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { |
391 | struct page *page = kmap_atomic_to_page(entry); |
392 | set_page_private(page, page_private(page) + incdec); |
393 | } |
394 | } |
395 | |
396 | /** |
397 | * shmem_swp_alloc - get the position of the swap entry for the page. |
398 | * @info: info structure for the inode |
399 | * @index: index of the page to find |
400 | * @sgp: check and recheck i_size? skip allocation? |
401 | * |
402 | * If the entry does not exist, allocate it. |
403 | */ |
404 | static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) |
405 | { |
406 | struct inode *inode = &info->vfs_inode; |
407 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
408 | struct page *page = NULL; |
409 | swp_entry_t *entry; |
410 | |
411 | if (sgp != SGP_WRITE && |
412 | ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
413 | return ERR_PTR(-EINVAL); |
414 | |
415 | while (!(entry = shmem_swp_entry(info, index, &page))) { |
416 | if (sgp == SGP_READ) |
417 | return shmem_swp_map(ZERO_PAGE(0)); |
418 | /* |
419 | * Test free_blocks against 1 not 0, since we have 1 data |
420 | * page (and perhaps indirect index pages) yet to allocate: |
421 | * a waste to allocate index if we cannot allocate data. |
422 | */ |
423 | if (sbinfo->max_blocks) { |
424 | spin_lock(&sbinfo->stat_lock); |
425 | if (sbinfo->free_blocks <= 1) { |
426 | spin_unlock(&sbinfo->stat_lock); |
427 | return ERR_PTR(-ENOSPC); |
428 | } |
429 | sbinfo->free_blocks--; |
430 | inode->i_blocks += BLOCKS_PER_PAGE; |
431 | spin_unlock(&sbinfo->stat_lock); |
432 | } |
433 | |
434 | spin_unlock(&info->lock); |
435 | page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); |
436 | if (page) |
437 | set_page_private(page, 0); |
438 | spin_lock(&info->lock); |
439 | |
440 | if (!page) { |
441 | shmem_free_blocks(inode, 1); |
442 | return ERR_PTR(-ENOMEM); |
443 | } |
444 | if (sgp != SGP_WRITE && |
445 | ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
446 | entry = ERR_PTR(-EINVAL); |
447 | break; |
448 | } |
449 | if (info->next_index <= index) |
450 | info->next_index = index + 1; |
451 | } |
452 | if (page) { |
453 | /* another task gave its page, or truncated the file */ |
454 | shmem_free_blocks(inode, 1); |
455 | shmem_dir_free(page); |
456 | } |
457 | if (info->next_index <= index && !IS_ERR(entry)) |
458 | info->next_index = index + 1; |
459 | return entry; |
460 | } |
461 | |
462 | /** |
463 | * shmem_free_swp - free some swap entries in a directory |
464 | * @dir: pointer to the directory |
465 | * @edir: pointer after last entry of the directory |
466 | * @punch_lock: pointer to spinlock when needed for the holepunch case |
467 | */ |
468 | static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, |
469 | spinlock_t *punch_lock) |
470 | { |
471 | spinlock_t *punch_unlock = NULL; |
472 | swp_entry_t *ptr; |
473 | int freed = 0; |
474 | |
475 | for (ptr = dir; ptr < edir; ptr++) { |
476 | if (ptr->val) { |
477 | if (unlikely(punch_lock)) { |
478 | punch_unlock = punch_lock; |
479 | punch_lock = NULL; |
480 | spin_lock(punch_unlock); |
481 | if (!ptr->val) |
482 | continue; |
483 | } |
484 | free_swap_and_cache(*ptr); |
485 | *ptr = (swp_entry_t){0}; |
486 | freed++; |
487 | } |
488 | } |
489 | if (punch_unlock) |
490 | spin_unlock(punch_unlock); |
491 | return freed; |
492 | } |
493 | |
494 | static int shmem_map_and_free_swp(struct page *subdir, int offset, |
495 | int limit, struct page ***dir, spinlock_t *punch_lock) |
496 | { |
497 | swp_entry_t *ptr; |
498 | int freed = 0; |
499 | |
500 | ptr = shmem_swp_map(subdir); |
501 | for (; offset < limit; offset += LATENCY_LIMIT) { |
502 | int size = limit - offset; |
503 | if (size > LATENCY_LIMIT) |
504 | size = LATENCY_LIMIT; |
505 | freed += shmem_free_swp(ptr+offset, ptr+offset+size, |
506 | punch_lock); |
507 | if (need_resched()) { |
508 | shmem_swp_unmap(ptr); |
509 | if (*dir) { |
510 | shmem_dir_unmap(*dir); |
511 | *dir = NULL; |
512 | } |
513 | cond_resched(); |
514 | ptr = shmem_swp_map(subdir); |
515 | } |
516 | } |
517 | shmem_swp_unmap(ptr); |
518 | return freed; |
519 | } |
520 | |
521 | static void shmem_free_pages(struct list_head *next) |
522 | { |
523 | struct page *page; |
524 | int freed = 0; |
525 | |
526 | do { |
527 | page = container_of(next, struct page, lru); |
528 | next = next->next; |
529 | shmem_dir_free(page); |
530 | freed++; |
531 | if (freed >= LATENCY_LIMIT) { |
532 | cond_resched(); |
533 | freed = 0; |
534 | } |
535 | } while (next); |
536 | } |
537 | |
538 | static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) |
539 | { |
540 | struct shmem_inode_info *info = SHMEM_I(inode); |
541 | unsigned long idx; |
542 | unsigned long size; |
543 | unsigned long limit; |
544 | unsigned long stage; |
545 | unsigned long diroff; |
546 | struct page **dir; |
547 | struct page *topdir; |
548 | struct page *middir; |
549 | struct page *subdir; |
550 | swp_entry_t *ptr; |
551 | LIST_HEAD(pages_to_free); |
552 | long nr_pages_to_free = 0; |
553 | long nr_swaps_freed = 0; |
554 | int offset; |
555 | int freed; |
556 | int punch_hole; |
557 | spinlock_t *needs_lock; |
558 | spinlock_t *punch_lock; |
559 | unsigned long upper_limit; |
560 | |
561 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
562 | idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
563 | if (idx >= info->next_index) |
564 | return; |
565 | |
566 | spin_lock(&info->lock); |
567 | info->flags |= SHMEM_TRUNCATE; |
568 | if (likely(end == (loff_t) -1)) { |
569 | limit = info->next_index; |
570 | upper_limit = SHMEM_MAX_INDEX; |
571 | info->next_index = idx; |
572 | needs_lock = NULL; |
573 | punch_hole = 0; |
574 | } else { |
575 | if (end + 1 >= inode->i_size) { /* we may free a little more */ |
576 | limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> |
577 | PAGE_CACHE_SHIFT; |
578 | upper_limit = SHMEM_MAX_INDEX; |
579 | } else { |
580 | limit = (end + 1) >> PAGE_CACHE_SHIFT; |
581 | upper_limit = limit; |
582 | } |
583 | needs_lock = &info->lock; |
584 | punch_hole = 1; |
585 | } |
586 | |
587 | topdir = info->i_indirect; |
588 | if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { |
589 | info->i_indirect = NULL; |
590 | nr_pages_to_free++; |
591 | list_add(&topdir->lru, &pages_to_free); |
592 | } |
593 | spin_unlock(&info->lock); |
594 | |
595 | if (info->swapped && idx < SHMEM_NR_DIRECT) { |
596 | ptr = info->i_direct; |
597 | size = limit; |
598 | if (size > SHMEM_NR_DIRECT) |
599 | size = SHMEM_NR_DIRECT; |
600 | nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); |
601 | } |
602 | |
603 | /* |
604 | * If there are no indirect blocks or we are punching a hole |
605 | * below indirect blocks, nothing to be done. |
606 | */ |
607 | if (!topdir || limit <= SHMEM_NR_DIRECT) |
608 | goto done2; |
609 | |
610 | /* |
611 | * The truncation case has already dropped info->lock, and we're safe |
612 | * because i_size and next_index have already been lowered, preventing |
613 | * access beyond. But in the punch_hole case, we still need to take |
614 | * the lock when updating the swap directory, because there might be |
615 | * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or |
616 | * shmem_writepage. However, whenever we find we can remove a whole |
617 | * directory page (not at the misaligned start or end of the range), |
618 | * we first NULLify its pointer in the level above, and then have no |
619 | * need to take the lock when updating its contents: needs_lock and |
620 | * punch_lock (either pointing to info->lock or NULL) manage this. |
621 | */ |
622 | |
623 | upper_limit -= SHMEM_NR_DIRECT; |
624 | limit -= SHMEM_NR_DIRECT; |
625 | idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; |
626 | offset = idx % ENTRIES_PER_PAGE; |
627 | idx -= offset; |
628 | |
629 | dir = shmem_dir_map(topdir); |
630 | stage = ENTRIES_PER_PAGEPAGE/2; |
631 | if (idx < ENTRIES_PER_PAGEPAGE/2) { |
632 | middir = topdir; |
633 | diroff = idx/ENTRIES_PER_PAGE; |
634 | } else { |
635 | dir += ENTRIES_PER_PAGE/2; |
636 | dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; |
637 | while (stage <= idx) |
638 | stage += ENTRIES_PER_PAGEPAGE; |
639 | middir = *dir; |
640 | if (*dir) { |
641 | diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % |
642 | ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; |
643 | if (!diroff && !offset && upper_limit >= stage) { |
644 | if (needs_lock) { |
645 | spin_lock(needs_lock); |
646 | *dir = NULL; |
647 | spin_unlock(needs_lock); |
648 | needs_lock = NULL; |
649 | } else |
650 | *dir = NULL; |
651 | nr_pages_to_free++; |
652 | list_add(&middir->lru, &pages_to_free); |
653 | } |
654 | shmem_dir_unmap(dir); |
655 | dir = shmem_dir_map(middir); |
656 | } else { |
657 | diroff = 0; |
658 | offset = 0; |
659 | idx = stage; |
660 | } |
661 | } |
662 | |
663 | for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { |
664 | if (unlikely(idx == stage)) { |
665 | shmem_dir_unmap(dir); |
666 | dir = shmem_dir_map(topdir) + |
667 | ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; |
668 | while (!*dir) { |
669 | dir++; |
670 | idx += ENTRIES_PER_PAGEPAGE; |
671 | if (idx >= limit) |
672 | goto done1; |
673 | } |
674 | stage = idx + ENTRIES_PER_PAGEPAGE; |
675 | middir = *dir; |
676 | if (punch_hole) |
677 | needs_lock = &info->lock; |
678 | if (upper_limit >= stage) { |
679 | if (needs_lock) { |
680 | spin_lock(needs_lock); |
681 | *dir = NULL; |
682 | spin_unlock(needs_lock); |
683 | needs_lock = NULL; |
684 | } else |
685 | *dir = NULL; |
686 | nr_pages_to_free++; |
687 | list_add(&middir->lru, &pages_to_free); |
688 | } |
689 | shmem_dir_unmap(dir); |
690 | cond_resched(); |
691 | dir = shmem_dir_map(middir); |
692 | diroff = 0; |
693 | } |
694 | punch_lock = needs_lock; |
695 | subdir = dir[diroff]; |
696 | if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { |
697 | if (needs_lock) { |
698 | spin_lock(needs_lock); |
699 | dir[diroff] = NULL; |
700 | spin_unlock(needs_lock); |
701 | punch_lock = NULL; |
702 | } else |
703 | dir[diroff] = NULL; |
704 | nr_pages_to_free++; |
705 | list_add(&subdir->lru, &pages_to_free); |
706 | } |
707 | if (subdir && page_private(subdir) /* has swap entries */) { |
708 | size = limit - idx; |
709 | if (size > ENTRIES_PER_PAGE) |
710 | size = ENTRIES_PER_PAGE; |
711 | freed = shmem_map_and_free_swp(subdir, |
712 | offset, size, &dir, punch_lock); |
713 | if (!dir) |
714 | dir = shmem_dir_map(middir); |
715 | nr_swaps_freed += freed; |
716 | if (offset || punch_lock) { |
717 | spin_lock(&info->lock); |
718 | set_page_private(subdir, |
719 | page_private(subdir) - freed); |
720 | spin_unlock(&info->lock); |
721 | } else |
722 | BUG_ON(page_private(subdir) != freed); |
723 | } |
724 | offset = 0; |
725 | } |
726 | done1: |
727 | shmem_dir_unmap(dir); |
728 | done2: |
729 | if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { |
730 | /* |
731 | * Call truncate_inode_pages again: racing shmem_unuse_inode |
732 | * may have swizzled a page in from swap since vmtruncate or |
733 | * generic_delete_inode did it, before we lowered next_index. |
734 | * Also, though shmem_getpage checks i_size before adding to |
735 | * cache, no recheck after: so fix the narrow window there too. |
736 | * |
737 | * Recalling truncate_inode_pages_range and unmap_mapping_range |
738 | * every time for punch_hole (which never got a chance to clear |
739 | * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, |
740 | * yet hardly ever necessary: try to optimize them out later. |
741 | */ |
742 | truncate_inode_pages_range(inode->i_mapping, start, end); |
743 | if (punch_hole) |
744 | unmap_mapping_range(inode->i_mapping, start, |
745 | end - start, 1); |
746 | } |
747 | |
748 | spin_lock(&info->lock); |
749 | info->flags &= ~SHMEM_TRUNCATE; |
750 | info->swapped -= nr_swaps_freed; |
751 | if (nr_pages_to_free) |
752 | shmem_free_blocks(inode, nr_pages_to_free); |
753 | shmem_recalc_inode(inode); |
754 | spin_unlock(&info->lock); |
755 | |
756 | /* |
757 | * Empty swap vector directory pages to be freed? |
758 | */ |
759 | if (!list_empty(&pages_to_free)) { |
760 | pages_to_free.prev->next = NULL; |
761 | shmem_free_pages(pages_to_free.next); |
762 | } |
763 | } |
764 | |
765 | static void shmem_truncate(struct inode *inode) |
766 | { |
767 | shmem_truncate_range(inode, inode->i_size, (loff_t)-1); |
768 | } |
769 | |
770 | static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) |
771 | { |
772 | struct inode *inode = dentry->d_inode; |
773 | struct page *page = NULL; |
774 | int error; |
775 | |
776 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
777 | if (attr->ia_size < inode->i_size) { |
778 | /* |
779 | * If truncating down to a partial page, then |
780 | * if that page is already allocated, hold it |
781 | * in memory until the truncation is over, so |
782 | * truncate_partial_page cannnot miss it were |
783 | * it assigned to swap. |
784 | */ |
785 | if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { |
786 | (void) shmem_getpage(inode, |
787 | attr->ia_size>>PAGE_CACHE_SHIFT, |
788 | &page, SGP_READ, NULL); |
789 | if (page) |
790 | unlock_page(page); |
791 | } |
792 | /* |
793 | * Reset SHMEM_PAGEIN flag so that shmem_truncate can |
794 | * detect if any pages might have been added to cache |
795 | * after truncate_inode_pages. But we needn't bother |
796 | * if it's being fully truncated to zero-length: the |
797 | * nrpages check is efficient enough in that case. |
798 | */ |
799 | if (attr->ia_size) { |
800 | struct shmem_inode_info *info = SHMEM_I(inode); |
801 | spin_lock(&info->lock); |
802 | info->flags &= ~SHMEM_PAGEIN; |
803 | spin_unlock(&info->lock); |
804 | } |
805 | } |
806 | } |
807 | |
808 | error = inode_change_ok(inode, attr); |
809 | if (!error) |
810 | error = inode_setattr(inode, attr); |
811 | #ifdef CONFIG_TMPFS_POSIX_ACL |
812 | if (!error && (attr->ia_valid & ATTR_MODE)) |
813 | error = generic_acl_chmod(inode); |
814 | #endif |
815 | if (page) |
816 | page_cache_release(page); |
817 | return error; |
818 | } |
819 | |
820 | static void shmem_delete_inode(struct inode *inode) |
821 | { |
822 | struct shmem_inode_info *info = SHMEM_I(inode); |
823 | |
824 | if (inode->i_op->truncate == shmem_truncate) { |
825 | truncate_inode_pages(inode->i_mapping, 0); |
826 | shmem_unacct_size(info->flags, inode->i_size); |
827 | inode->i_size = 0; |
828 | shmem_truncate(inode); |
829 | if (!list_empty(&info->swaplist)) { |
830 | mutex_lock(&shmem_swaplist_mutex); |
831 | list_del_init(&info->swaplist); |
832 | mutex_unlock(&shmem_swaplist_mutex); |
833 | } |
834 | } |
835 | BUG_ON(inode->i_blocks); |
836 | shmem_free_inode(inode->i_sb); |
837 | clear_inode(inode); |
838 | } |
839 | |
840 | static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) |
841 | { |
842 | swp_entry_t *ptr; |
843 | |
844 | for (ptr = dir; ptr < edir; ptr++) { |
845 | if (ptr->val == entry.val) |
846 | return ptr - dir; |
847 | } |
848 | return -1; |
849 | } |
850 | |
851 | static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) |
852 | { |
853 | struct inode *inode; |
854 | unsigned long idx; |
855 | unsigned long size; |
856 | unsigned long limit; |
857 | unsigned long stage; |
858 | struct page **dir; |
859 | struct page *subdir; |
860 | swp_entry_t *ptr; |
861 | int offset; |
862 | int error; |
863 | |
864 | idx = 0; |
865 | ptr = info->i_direct; |
866 | spin_lock(&info->lock); |
867 | if (!info->swapped) { |
868 | list_del_init(&info->swaplist); |
869 | goto lost2; |
870 | } |
871 | limit = info->next_index; |
872 | size = limit; |
873 | if (size > SHMEM_NR_DIRECT) |
874 | size = SHMEM_NR_DIRECT; |
875 | offset = shmem_find_swp(entry, ptr, ptr+size); |
876 | if (offset >= 0) |
877 | goto found; |
878 | if (!info->i_indirect) |
879 | goto lost2; |
880 | |
881 | dir = shmem_dir_map(info->i_indirect); |
882 | stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; |
883 | |
884 | for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { |
885 | if (unlikely(idx == stage)) { |
886 | shmem_dir_unmap(dir-1); |
887 | if (cond_resched_lock(&info->lock)) { |
888 | /* check it has not been truncated */ |
889 | if (limit > info->next_index) { |
890 | limit = info->next_index; |
891 | if (idx >= limit) |
892 | goto lost2; |
893 | } |
894 | } |
895 | dir = shmem_dir_map(info->i_indirect) + |
896 | ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; |
897 | while (!*dir) { |
898 | dir++; |
899 | idx += ENTRIES_PER_PAGEPAGE; |
900 | if (idx >= limit) |
901 | goto lost1; |
902 | } |
903 | stage = idx + ENTRIES_PER_PAGEPAGE; |
904 | subdir = *dir; |
905 | shmem_dir_unmap(dir); |
906 | dir = shmem_dir_map(subdir); |
907 | } |
908 | subdir = *dir; |
909 | if (subdir && page_private(subdir)) { |
910 | ptr = shmem_swp_map(subdir); |
911 | size = limit - idx; |
912 | if (size > ENTRIES_PER_PAGE) |
913 | size = ENTRIES_PER_PAGE; |
914 | offset = shmem_find_swp(entry, ptr, ptr+size); |
915 | shmem_swp_unmap(ptr); |
916 | if (offset >= 0) { |
917 | shmem_dir_unmap(dir); |
918 | goto found; |
919 | } |
920 | } |
921 | } |
922 | lost1: |
923 | shmem_dir_unmap(dir-1); |
924 | lost2: |
925 | spin_unlock(&info->lock); |
926 | return 0; |
927 | found: |
928 | idx += offset; |
929 | inode = igrab(&info->vfs_inode); |
930 | spin_unlock(&info->lock); |
931 | |
932 | /* |
933 | * Move _head_ to start search for next from here. |
934 | * But be careful: shmem_delete_inode checks list_empty without taking |
935 | * mutex, and there's an instant in list_move_tail when info->swaplist |
936 | * would appear empty, if it were the only one on shmem_swaplist. We |
937 | * could avoid doing it if inode NULL; or use this minor optimization. |
938 | */ |
939 | if (shmem_swaplist.next != &info->swaplist) |
940 | list_move_tail(&shmem_swaplist, &info->swaplist); |
941 | mutex_unlock(&shmem_swaplist_mutex); |
942 | |
943 | error = 1; |
944 | if (!inode) |
945 | goto out; |
946 | /* |
947 | * Charge page using GFP_KERNEL while we can wait. |
948 | * Charged back to the user(not to caller) when swap account is used. |
949 | * add_to_page_cache() will be called with GFP_NOWAIT. |
950 | */ |
951 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); |
952 | if (error) |
953 | goto out; |
954 | error = radix_tree_preload(GFP_KERNEL); |
955 | if (error) { |
956 | mem_cgroup_uncharge_cache_page(page); |
957 | goto out; |
958 | } |
959 | error = 1; |
960 | |
961 | spin_lock(&info->lock); |
962 | ptr = shmem_swp_entry(info, idx, NULL); |
963 | if (ptr && ptr->val == entry.val) { |
964 | error = add_to_page_cache_locked(page, inode->i_mapping, |
965 | idx, GFP_NOWAIT); |
966 | /* does mem_cgroup_uncharge_cache_page on error */ |
967 | } else /* we must compensate for our precharge above */ |
968 | mem_cgroup_uncharge_cache_page(page); |
969 | |
970 | if (error == -EEXIST) { |
971 | struct page *filepage = find_get_page(inode->i_mapping, idx); |
972 | error = 1; |
973 | if (filepage) { |
974 | /* |
975 | * There might be a more uptodate page coming down |
976 | * from a stacked writepage: forget our swappage if so. |
977 | */ |
978 | if (PageUptodate(filepage)) |
979 | error = 0; |
980 | page_cache_release(filepage); |
981 | } |
982 | } |
983 | if (!error) { |
984 | delete_from_swap_cache(page); |
985 | set_page_dirty(page); |
986 | info->flags |= SHMEM_PAGEIN; |
987 | shmem_swp_set(info, ptr, 0); |
988 | swap_free(entry); |
989 | error = 1; /* not an error, but entry was found */ |
990 | } |
991 | if (ptr) |
992 | shmem_swp_unmap(ptr); |
993 | spin_unlock(&info->lock); |
994 | radix_tree_preload_end(); |
995 | out: |
996 | unlock_page(page); |
997 | page_cache_release(page); |
998 | iput(inode); /* allows for NULL */ |
999 | return error; |
1000 | } |
1001 | |
1002 | /* |
1003 | * shmem_unuse() search for an eventually swapped out shmem page. |
1004 | */ |
1005 | int shmem_unuse(swp_entry_t entry, struct page *page) |
1006 | { |
1007 | struct list_head *p, *next; |
1008 | struct shmem_inode_info *info; |
1009 | int found = 0; |
1010 | |
1011 | mutex_lock(&shmem_swaplist_mutex); |
1012 | list_for_each_safe(p, next, &shmem_swaplist) { |
1013 | info = list_entry(p, struct shmem_inode_info, swaplist); |
1014 | found = shmem_unuse_inode(info, entry, page); |
1015 | cond_resched(); |
1016 | if (found) |
1017 | goto out; |
1018 | } |
1019 | mutex_unlock(&shmem_swaplist_mutex); |
1020 | /* |
1021 | * Can some race bring us here? We've been holding page lock, |
1022 | * so I think not; but would rather try again later than BUG() |
1023 | */ |
1024 | unlock_page(page); |
1025 | page_cache_release(page); |
1026 | out: |
1027 | return (found < 0) ? found : 0; |
1028 | } |
1029 | |
1030 | /* |
1031 | * Move the page from the page cache to the swap cache. |
1032 | */ |
1033 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
1034 | { |
1035 | struct shmem_inode_info *info; |
1036 | swp_entry_t *entry, swap; |
1037 | struct address_space *mapping; |
1038 | unsigned long index; |
1039 | struct inode *inode; |
1040 | |
1041 | BUG_ON(!PageLocked(page)); |
1042 | mapping = page->mapping; |
1043 | index = page->index; |
1044 | inode = mapping->host; |
1045 | info = SHMEM_I(inode); |
1046 | if (info->flags & VM_LOCKED) |
1047 | goto redirty; |
1048 | if (!total_swap_pages) |
1049 | goto redirty; |
1050 | |
1051 | /* |
1052 | * shmem_backing_dev_info's capabilities prevent regular writeback or |
1053 | * sync from ever calling shmem_writepage; but a stacking filesystem |
1054 | * may use the ->writepage of its underlying filesystem, in which case |
1055 | * tmpfs should write out to swap only in response to memory pressure, |
1056 | * and not for the writeback threads or sync. However, in those cases, |
1057 | * we do still want to check if there's a redundant swappage to be |
1058 | * discarded. |
1059 | */ |
1060 | if (wbc->for_reclaim) |
1061 | swap = get_swap_page(); |
1062 | else |
1063 | swap.val = 0; |
1064 | |
1065 | spin_lock(&info->lock); |
1066 | if (index >= info->next_index) { |
1067 | BUG_ON(!(info->flags & SHMEM_TRUNCATE)); |
1068 | goto unlock; |
1069 | } |
1070 | entry = shmem_swp_entry(info, index, NULL); |
1071 | if (entry->val) { |
1072 | /* |
1073 | * The more uptodate page coming down from a stacked |
1074 | * writepage should replace our old swappage. |
1075 | */ |
1076 | free_swap_and_cache(*entry); |
1077 | shmem_swp_set(info, entry, 0); |
1078 | } |
1079 | shmem_recalc_inode(inode); |
1080 | |
1081 | if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
1082 | remove_from_page_cache(page); |
1083 | shmem_swp_set(info, entry, swap.val); |
1084 | shmem_swp_unmap(entry); |
1085 | if (list_empty(&info->swaplist)) |
1086 | inode = igrab(inode); |
1087 | else |
1088 | inode = NULL; |
1089 | spin_unlock(&info->lock); |
1090 | swap_shmem_alloc(swap); |
1091 | BUG_ON(page_mapped(page)); |
1092 | page_cache_release(page); /* pagecache ref */ |
1093 | swap_writepage(page, wbc); |
1094 | if (inode) { |
1095 | mutex_lock(&shmem_swaplist_mutex); |
1096 | /* move instead of add in case we're racing */ |
1097 | list_move_tail(&info->swaplist, &shmem_swaplist); |
1098 | mutex_unlock(&shmem_swaplist_mutex); |
1099 | iput(inode); |
1100 | } |
1101 | return 0; |
1102 | } |
1103 | |
1104 | shmem_swp_unmap(entry); |
1105 | unlock: |
1106 | spin_unlock(&info->lock); |
1107 | /* |
1108 | * add_to_swap_cache() doesn't return -EEXIST, so we can safely |
1109 | * clear SWAP_HAS_CACHE flag. |
1110 | */ |
1111 | swapcache_free(swap, NULL); |
1112 | redirty: |
1113 | set_page_dirty(page); |
1114 | if (wbc->for_reclaim) |
1115 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
1116 | unlock_page(page); |
1117 | return 0; |
1118 | } |
1119 | |
1120 | #ifdef CONFIG_NUMA |
1121 | #ifdef CONFIG_TMPFS |
1122 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
1123 | { |
1124 | char buffer[64]; |
1125 | |
1126 | if (!mpol || mpol->mode == MPOL_DEFAULT) |
1127 | return; /* show nothing */ |
1128 | |
1129 | mpol_to_str(buffer, sizeof(buffer), mpol, 1); |
1130 | |
1131 | seq_printf(seq, ",mpol=%s", buffer); |
1132 | } |
1133 | |
1134 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
1135 | { |
1136 | struct mempolicy *mpol = NULL; |
1137 | if (sbinfo->mpol) { |
1138 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
1139 | mpol = sbinfo->mpol; |
1140 | mpol_get(mpol); |
1141 | spin_unlock(&sbinfo->stat_lock); |
1142 | } |
1143 | return mpol; |
1144 | } |
1145 | #endif /* CONFIG_TMPFS */ |
1146 | |
1147 | static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, |
1148 | struct shmem_inode_info *info, unsigned long idx) |
1149 | { |
1150 | struct mempolicy mpol, *spol; |
1151 | struct vm_area_struct pvma; |
1152 | struct page *page; |
1153 | |
1154 | spol = mpol_cond_copy(&mpol, |
1155 | mpol_shared_policy_lookup(&info->policy, idx)); |
1156 | |
1157 | /* Create a pseudo vma that just contains the policy */ |
1158 | pvma.vm_start = 0; |
1159 | pvma.vm_pgoff = idx; |
1160 | pvma.vm_ops = NULL; |
1161 | pvma.vm_policy = spol; |
1162 | page = swapin_readahead(entry, gfp, &pvma, 0); |
1163 | return page; |
1164 | } |
1165 | |
1166 | static struct page *shmem_alloc_page(gfp_t gfp, |
1167 | struct shmem_inode_info *info, unsigned long idx) |
1168 | { |
1169 | struct vm_area_struct pvma; |
1170 | |
1171 | /* Create a pseudo vma that just contains the policy */ |
1172 | pvma.vm_start = 0; |
1173 | pvma.vm_pgoff = idx; |
1174 | pvma.vm_ops = NULL; |
1175 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); |
1176 | |
1177 | /* |
1178 | * alloc_page_vma() will drop the shared policy reference |
1179 | */ |
1180 | return alloc_page_vma(gfp, &pvma, 0); |
1181 | } |
1182 | #else /* !CONFIG_NUMA */ |
1183 | #ifdef CONFIG_TMPFS |
1184 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) |
1185 | { |
1186 | } |
1187 | #endif /* CONFIG_TMPFS */ |
1188 | |
1189 | static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, |
1190 | struct shmem_inode_info *info, unsigned long idx) |
1191 | { |
1192 | return swapin_readahead(entry, gfp, NULL, 0); |
1193 | } |
1194 | |
1195 | static inline struct page *shmem_alloc_page(gfp_t gfp, |
1196 | struct shmem_inode_info *info, unsigned long idx) |
1197 | { |
1198 | return alloc_page(gfp); |
1199 | } |
1200 | #endif /* CONFIG_NUMA */ |
1201 | |
1202 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
1203 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
1204 | { |
1205 | return NULL; |
1206 | } |
1207 | #endif |
1208 | |
1209 | /* |
1210 | * shmem_getpage - either get the page from swap or allocate a new one |
1211 | * |
1212 | * If we allocate a new one we do not mark it dirty. That's up to the |
1213 | * vm. If we swap it in we mark it dirty since we also free the swap |
1214 | * entry since a page cannot live in both the swap and page cache |
1215 | */ |
1216 | static int shmem_getpage(struct inode *inode, unsigned long idx, |
1217 | struct page **pagep, enum sgp_type sgp, int *type) |
1218 | { |
1219 | struct address_space *mapping = inode->i_mapping; |
1220 | struct shmem_inode_info *info = SHMEM_I(inode); |
1221 | struct shmem_sb_info *sbinfo; |
1222 | struct page *filepage = *pagep; |
1223 | struct page *swappage; |
1224 | swp_entry_t *entry; |
1225 | swp_entry_t swap; |
1226 | gfp_t gfp; |
1227 | int error; |
1228 | |
1229 | if (idx >= SHMEM_MAX_INDEX) |
1230 | return -EFBIG; |
1231 | |
1232 | if (type) |
1233 | *type = 0; |
1234 | |
1235 | /* |
1236 | * Normally, filepage is NULL on entry, and either found |
1237 | * uptodate immediately, or allocated and zeroed, or read |
1238 | * in under swappage, which is then assigned to filepage. |
1239 | * But shmem_readpage (required for splice) passes in a locked |
1240 | * filepage, which may be found not uptodate by other callers |
1241 | * too, and may need to be copied from the swappage read in. |
1242 | */ |
1243 | repeat: |
1244 | if (!filepage) |
1245 | filepage = find_lock_page(mapping, idx); |
1246 | if (filepage && PageUptodate(filepage)) |
1247 | goto done; |
1248 | error = 0; |
1249 | gfp = mapping_gfp_mask(mapping); |
1250 | if (!filepage) { |
1251 | /* |
1252 | * Try to preload while we can wait, to not make a habit of |
1253 | * draining atomic reserves; but don't latch on to this cpu. |
1254 | */ |
1255 | error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); |
1256 | if (error) |
1257 | goto failed; |
1258 | radix_tree_preload_end(); |
1259 | } |
1260 | |
1261 | spin_lock(&info->lock); |
1262 | shmem_recalc_inode(inode); |
1263 | entry = shmem_swp_alloc(info, idx, sgp); |
1264 | if (IS_ERR(entry)) { |
1265 | spin_unlock(&info->lock); |
1266 | error = PTR_ERR(entry); |
1267 | goto failed; |
1268 | } |
1269 | swap = *entry; |
1270 | |
1271 | if (swap.val) { |
1272 | /* Look it up and read it in.. */ |
1273 | swappage = lookup_swap_cache(swap); |
1274 | if (!swappage) { |
1275 | shmem_swp_unmap(entry); |
1276 | /* here we actually do the io */ |
1277 | if (type && !(*type & VM_FAULT_MAJOR)) { |
1278 | __count_vm_event(PGMAJFAULT); |
1279 | *type |= VM_FAULT_MAJOR; |
1280 | } |
1281 | spin_unlock(&info->lock); |
1282 | swappage = shmem_swapin(swap, gfp, info, idx); |
1283 | if (!swappage) { |
1284 | spin_lock(&info->lock); |
1285 | entry = shmem_swp_alloc(info, idx, sgp); |
1286 | if (IS_ERR(entry)) |
1287 | error = PTR_ERR(entry); |
1288 | else { |
1289 | if (entry->val == swap.val) |
1290 | error = -ENOMEM; |
1291 | shmem_swp_unmap(entry); |
1292 | } |
1293 | spin_unlock(&info->lock); |
1294 | if (error) |
1295 | goto failed; |
1296 | goto repeat; |
1297 | } |
1298 | wait_on_page_locked(swappage); |
1299 | page_cache_release(swappage); |
1300 | goto repeat; |
1301 | } |
1302 | |
1303 | /* We have to do this with page locked to prevent races */ |
1304 | if (!trylock_page(swappage)) { |
1305 | shmem_swp_unmap(entry); |
1306 | spin_unlock(&info->lock); |
1307 | wait_on_page_locked(swappage); |
1308 | page_cache_release(swappage); |
1309 | goto repeat; |
1310 | } |
1311 | if (PageWriteback(swappage)) { |
1312 | shmem_swp_unmap(entry); |
1313 | spin_unlock(&info->lock); |
1314 | wait_on_page_writeback(swappage); |
1315 | unlock_page(swappage); |
1316 | page_cache_release(swappage); |
1317 | goto repeat; |
1318 | } |
1319 | if (!PageUptodate(swappage)) { |
1320 | shmem_swp_unmap(entry); |
1321 | spin_unlock(&info->lock); |
1322 | unlock_page(swappage); |
1323 | page_cache_release(swappage); |
1324 | error = -EIO; |
1325 | goto failed; |
1326 | } |
1327 | |
1328 | if (filepage) { |
1329 | shmem_swp_set(info, entry, 0); |
1330 | shmem_swp_unmap(entry); |
1331 | delete_from_swap_cache(swappage); |
1332 | spin_unlock(&info->lock); |
1333 | copy_highpage(filepage, swappage); |
1334 | unlock_page(swappage); |
1335 | page_cache_release(swappage); |
1336 | flush_dcache_page(filepage); |
1337 | SetPageUptodate(filepage); |
1338 | set_page_dirty(filepage); |
1339 | swap_free(swap); |
1340 | } else if (!(error = add_to_page_cache_locked(swappage, mapping, |
1341 | idx, GFP_NOWAIT))) { |
1342 | info->flags |= SHMEM_PAGEIN; |
1343 | shmem_swp_set(info, entry, 0); |
1344 | shmem_swp_unmap(entry); |
1345 | delete_from_swap_cache(swappage); |
1346 | spin_unlock(&info->lock); |
1347 | filepage = swappage; |
1348 | set_page_dirty(filepage); |
1349 | swap_free(swap); |
1350 | } else { |
1351 | shmem_swp_unmap(entry); |
1352 | spin_unlock(&info->lock); |
1353 | if (error == -ENOMEM) { |
1354 | /* |
1355 | * reclaim from proper memory cgroup and |
1356 | * call memcg's OOM if needed. |
1357 | */ |
1358 | error = mem_cgroup_shmem_charge_fallback( |
1359 | swappage, |
1360 | current->mm, |
1361 | gfp); |
1362 | if (error) { |
1363 | unlock_page(swappage); |
1364 | page_cache_release(swappage); |
1365 | goto failed; |
1366 | } |
1367 | } |
1368 | unlock_page(swappage); |
1369 | page_cache_release(swappage); |
1370 | goto repeat; |
1371 | } |
1372 | } else if (sgp == SGP_READ && !filepage) { |
1373 | shmem_swp_unmap(entry); |
1374 | filepage = find_get_page(mapping, idx); |
1375 | if (filepage && |
1376 | (!PageUptodate(filepage) || !trylock_page(filepage))) { |
1377 | spin_unlock(&info->lock); |
1378 | wait_on_page_locked(filepage); |
1379 | page_cache_release(filepage); |
1380 | filepage = NULL; |
1381 | goto repeat; |
1382 | } |
1383 | spin_unlock(&info->lock); |
1384 | } else { |
1385 | shmem_swp_unmap(entry); |
1386 | sbinfo = SHMEM_SB(inode->i_sb); |
1387 | if (sbinfo->max_blocks) { |
1388 | spin_lock(&sbinfo->stat_lock); |
1389 | if (sbinfo->free_blocks == 0 || |
1390 | shmem_acct_block(info->flags)) { |
1391 | spin_unlock(&sbinfo->stat_lock); |
1392 | spin_unlock(&info->lock); |
1393 | error = -ENOSPC; |
1394 | goto failed; |
1395 | } |
1396 | sbinfo->free_blocks--; |
1397 | inode->i_blocks += BLOCKS_PER_PAGE; |
1398 | spin_unlock(&sbinfo->stat_lock); |
1399 | } else if (shmem_acct_block(info->flags)) { |
1400 | spin_unlock(&info->lock); |
1401 | error = -ENOSPC; |
1402 | goto failed; |
1403 | } |
1404 | |
1405 | if (!filepage) { |
1406 | int ret; |
1407 | |
1408 | spin_unlock(&info->lock); |
1409 | filepage = shmem_alloc_page(gfp, info, idx); |
1410 | if (!filepage) { |
1411 | shmem_unacct_blocks(info->flags, 1); |
1412 | shmem_free_blocks(inode, 1); |
1413 | error = -ENOMEM; |
1414 | goto failed; |
1415 | } |
1416 | SetPageSwapBacked(filepage); |
1417 | |
1418 | /* Precharge page while we can wait, compensate after */ |
1419 | error = mem_cgroup_cache_charge(filepage, current->mm, |
1420 | GFP_KERNEL); |
1421 | if (error) { |
1422 | page_cache_release(filepage); |
1423 | shmem_unacct_blocks(info->flags, 1); |
1424 | shmem_free_blocks(inode, 1); |
1425 | filepage = NULL; |
1426 | goto failed; |
1427 | } |
1428 | |
1429 | spin_lock(&info->lock); |
1430 | entry = shmem_swp_alloc(info, idx, sgp); |
1431 | if (IS_ERR(entry)) |
1432 | error = PTR_ERR(entry); |
1433 | else { |
1434 | swap = *entry; |
1435 | shmem_swp_unmap(entry); |
1436 | } |
1437 | ret = error || swap.val; |
1438 | if (ret) |
1439 | mem_cgroup_uncharge_cache_page(filepage); |
1440 | else |
1441 | ret = add_to_page_cache_lru(filepage, mapping, |
1442 | idx, GFP_NOWAIT); |
1443 | /* |
1444 | * At add_to_page_cache_lru() failure, uncharge will |
1445 | * be done automatically. |
1446 | */ |
1447 | if (ret) { |
1448 | spin_unlock(&info->lock); |
1449 | page_cache_release(filepage); |
1450 | shmem_unacct_blocks(info->flags, 1); |
1451 | shmem_free_blocks(inode, 1); |
1452 | filepage = NULL; |
1453 | if (error) |
1454 | goto failed; |
1455 | goto repeat; |
1456 | } |
1457 | info->flags |= SHMEM_PAGEIN; |
1458 | } |
1459 | |
1460 | info->alloced++; |
1461 | spin_unlock(&info->lock); |
1462 | clear_highpage(filepage); |
1463 | flush_dcache_page(filepage); |
1464 | SetPageUptodate(filepage); |
1465 | if (sgp == SGP_DIRTY) |
1466 | set_page_dirty(filepage); |
1467 | } |
1468 | done: |
1469 | *pagep = filepage; |
1470 | return 0; |
1471 | |
1472 | failed: |
1473 | if (*pagep != filepage) { |
1474 | unlock_page(filepage); |
1475 | page_cache_release(filepage); |
1476 | } |
1477 | return error; |
1478 | } |
1479 | |
1480 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1481 | { |
1482 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
1483 | int error; |
1484 | int ret; |
1485 | |
1486 | if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
1487 | return VM_FAULT_SIGBUS; |
1488 | |
1489 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
1490 | if (error) |
1491 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
1492 | |
1493 | return ret | VM_FAULT_LOCKED; |
1494 | } |
1495 | |
1496 | #ifdef CONFIG_NUMA |
1497 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) |
1498 | { |
1499 | struct inode *i = vma->vm_file->f_path.dentry->d_inode; |
1500 | return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); |
1501 | } |
1502 | |
1503 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
1504 | unsigned long addr) |
1505 | { |
1506 | struct inode *i = vma->vm_file->f_path.dentry->d_inode; |
1507 | unsigned long idx; |
1508 | |
1509 | idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
1510 | return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); |
1511 | } |
1512 | #endif |
1513 | |
1514 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
1515 | { |
1516 | struct inode *inode = file->f_path.dentry->d_inode; |
1517 | struct shmem_inode_info *info = SHMEM_I(inode); |
1518 | int retval = -ENOMEM; |
1519 | |
1520 | spin_lock(&info->lock); |
1521 | if (lock && !(info->flags & VM_LOCKED)) { |
1522 | if (!user_shm_lock(inode->i_size, user)) |
1523 | goto out_nomem; |
1524 | info->flags |= VM_LOCKED; |
1525 | mapping_set_unevictable(file->f_mapping); |
1526 | } |
1527 | if (!lock && (info->flags & VM_LOCKED) && user) { |
1528 | user_shm_unlock(inode->i_size, user); |
1529 | info->flags &= ~VM_LOCKED; |
1530 | mapping_clear_unevictable(file->f_mapping); |
1531 | scan_mapping_unevictable_pages(file->f_mapping); |
1532 | } |
1533 | retval = 0; |
1534 | |
1535 | out_nomem: |
1536 | spin_unlock(&info->lock); |
1537 | return retval; |
1538 | } |
1539 | |
1540 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
1541 | { |
1542 | file_accessed(file); |
1543 | vma->vm_ops = &shmem_vm_ops; |
1544 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1545 | return 0; |
1546 | } |
1547 | |
1548 | static struct inode *shmem_get_inode(struct super_block *sb, int mode, |
1549 | dev_t dev, unsigned long flags) |
1550 | { |
1551 | struct inode *inode; |
1552 | struct shmem_inode_info *info; |
1553 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
1554 | |
1555 | if (shmem_reserve_inode(sb)) |
1556 | return NULL; |
1557 | |
1558 | inode = new_inode(sb); |
1559 | if (inode) { |
1560 | inode->i_mode = mode; |
1561 | inode->i_uid = current_fsuid(); |
1562 | inode->i_gid = current_fsgid(); |
1563 | inode->i_blocks = 0; |
1564 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
1565 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1566 | inode->i_generation = get_seconds(); |
1567 | info = SHMEM_I(inode); |
1568 | memset(info, 0, (char *)inode - (char *)info); |
1569 | spin_lock_init(&info->lock); |
1570 | info->flags = flags & VM_NORESERVE; |
1571 | INIT_LIST_HEAD(&info->swaplist); |
1572 | cache_no_acl(inode); |
1573 | |
1574 | switch (mode & S_IFMT) { |
1575 | default: |
1576 | inode->i_op = &shmem_special_inode_operations; |
1577 | init_special_inode(inode, mode, dev); |
1578 | break; |
1579 | case S_IFREG: |
1580 | inode->i_mapping->a_ops = &shmem_aops; |
1581 | inode->i_op = &shmem_inode_operations; |
1582 | inode->i_fop = &shmem_file_operations; |
1583 | mpol_shared_policy_init(&info->policy, |
1584 | shmem_get_sbmpol(sbinfo)); |
1585 | break; |
1586 | case S_IFDIR: |
1587 | inc_nlink(inode); |
1588 | /* Some things misbehave if size == 0 on a directory */ |
1589 | inode->i_size = 2 * BOGO_DIRENT_SIZE; |
1590 | inode->i_op = &shmem_dir_inode_operations; |
1591 | inode->i_fop = &simple_dir_operations; |
1592 | break; |
1593 | case S_IFLNK: |
1594 | /* |
1595 | * Must not load anything in the rbtree, |
1596 | * mpol_free_shared_policy will not be called. |
1597 | */ |
1598 | mpol_shared_policy_init(&info->policy, NULL); |
1599 | break; |
1600 | } |
1601 | } else |
1602 | shmem_free_inode(sb); |
1603 | return inode; |
1604 | } |
1605 | |
1606 | #ifdef CONFIG_TMPFS |
1607 | static const struct inode_operations shmem_symlink_inode_operations; |
1608 | static const struct inode_operations shmem_symlink_inline_operations; |
1609 | |
1610 | /* |
1611 | * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; |
1612 | * but providing them allows a tmpfs file to be used for splice, sendfile, and |
1613 | * below the loop driver, in the generic fashion that many filesystems support. |
1614 | */ |
1615 | static int shmem_readpage(struct file *file, struct page *page) |
1616 | { |
1617 | struct inode *inode = page->mapping->host; |
1618 | int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); |
1619 | unlock_page(page); |
1620 | return error; |
1621 | } |
1622 | |
1623 | static int |
1624 | shmem_write_begin(struct file *file, struct address_space *mapping, |
1625 | loff_t pos, unsigned len, unsigned flags, |
1626 | struct page **pagep, void **fsdata) |
1627 | { |
1628 | struct inode *inode = mapping->host; |
1629 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
1630 | *pagep = NULL; |
1631 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
1632 | } |
1633 | |
1634 | static int |
1635 | shmem_write_end(struct file *file, struct address_space *mapping, |
1636 | loff_t pos, unsigned len, unsigned copied, |
1637 | struct page *page, void *fsdata) |
1638 | { |
1639 | struct inode *inode = mapping->host; |
1640 | |
1641 | if (pos + copied > inode->i_size) |
1642 | i_size_write(inode, pos + copied); |
1643 | |
1644 | set_page_dirty(page); |
1645 | unlock_page(page); |
1646 | page_cache_release(page); |
1647 | |
1648 | return copied; |
1649 | } |
1650 | |
1651 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) |
1652 | { |
1653 | struct inode *inode = filp->f_path.dentry->d_inode; |
1654 | struct address_space *mapping = inode->i_mapping; |
1655 | unsigned long index, offset; |
1656 | enum sgp_type sgp = SGP_READ; |
1657 | |
1658 | /* |
1659 | * Might this read be for a stacking filesystem? Then when reading |
1660 | * holes of a sparse file, we actually need to allocate those pages, |
1661 | * and even mark them dirty, so it cannot exceed the max_blocks limit. |
1662 | */ |
1663 | if (segment_eq(get_fs(), KERNEL_DS)) |
1664 | sgp = SGP_DIRTY; |
1665 | |
1666 | index = *ppos >> PAGE_CACHE_SHIFT; |
1667 | offset = *ppos & ~PAGE_CACHE_MASK; |
1668 | |
1669 | for (;;) { |
1670 | struct page *page = NULL; |
1671 | unsigned long end_index, nr, ret; |
1672 | loff_t i_size = i_size_read(inode); |
1673 | |
1674 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1675 | if (index > end_index) |
1676 | break; |
1677 | if (index == end_index) { |
1678 | nr = i_size & ~PAGE_CACHE_MASK; |
1679 | if (nr <= offset) |
1680 | break; |
1681 | } |
1682 | |
1683 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); |
1684 | if (desc->error) { |
1685 | if (desc->error == -EINVAL) |
1686 | desc->error = 0; |
1687 | break; |
1688 | } |
1689 | if (page) |
1690 | unlock_page(page); |
1691 | |
1692 | /* |
1693 | * We must evaluate after, since reads (unlike writes) |
1694 | * are called without i_mutex protection against truncate |
1695 | */ |
1696 | nr = PAGE_CACHE_SIZE; |
1697 | i_size = i_size_read(inode); |
1698 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1699 | if (index == end_index) { |
1700 | nr = i_size & ~PAGE_CACHE_MASK; |
1701 | if (nr <= offset) { |
1702 | if (page) |
1703 | page_cache_release(page); |
1704 | break; |
1705 | } |
1706 | } |
1707 | nr -= offset; |
1708 | |
1709 | if (page) { |
1710 | /* |
1711 | * If users can be writing to this page using arbitrary |
1712 | * virtual addresses, take care about potential aliasing |
1713 | * before reading the page on the kernel side. |
1714 | */ |
1715 | if (mapping_writably_mapped(mapping)) |
1716 | flush_dcache_page(page); |
1717 | /* |
1718 | * Mark the page accessed if we read the beginning. |
1719 | */ |
1720 | if (!offset) |
1721 | mark_page_accessed(page); |
1722 | } else { |
1723 | page = ZERO_PAGE(0); |
1724 | page_cache_get(page); |
1725 | } |
1726 | |
1727 | /* |
1728 | * Ok, we have the page, and it's up-to-date, so |
1729 | * now we can copy it to user space... |
1730 | * |
1731 | * The actor routine returns how many bytes were actually used.. |
1732 | * NOTE! This may not be the same as how much of a user buffer |
1733 | * we filled up (we may be padding etc), so we can only update |
1734 | * "pos" here (the actor routine has to update the user buffer |
1735 | * pointers and the remaining count). |
1736 | */ |
1737 | ret = actor(desc, page, offset, nr); |
1738 | offset += ret; |
1739 | index += offset >> PAGE_CACHE_SHIFT; |
1740 | offset &= ~PAGE_CACHE_MASK; |
1741 | |
1742 | page_cache_release(page); |
1743 | if (ret != nr || !desc->count) |
1744 | break; |
1745 | |
1746 | cond_resched(); |
1747 | } |
1748 | |
1749 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
1750 | file_accessed(filp); |
1751 | } |
1752 | |
1753 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, |
1754 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
1755 | { |
1756 | struct file *filp = iocb->ki_filp; |
1757 | ssize_t retval; |
1758 | unsigned long seg; |
1759 | size_t count; |
1760 | loff_t *ppos = &iocb->ki_pos; |
1761 | |
1762 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1763 | if (retval) |
1764 | return retval; |
1765 | |
1766 | for (seg = 0; seg < nr_segs; seg++) { |
1767 | read_descriptor_t desc; |
1768 | |
1769 | desc.written = 0; |
1770 | desc.arg.buf = iov[seg].iov_base; |
1771 | desc.count = iov[seg].iov_len; |
1772 | if (desc.count == 0) |
1773 | continue; |
1774 | desc.error = 0; |
1775 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); |
1776 | retval += desc.written; |
1777 | if (desc.error) { |
1778 | retval = retval ?: desc.error; |
1779 | break; |
1780 | } |
1781 | if (desc.count > 0) |
1782 | break; |
1783 | } |
1784 | return retval; |
1785 | } |
1786 | |
1787 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
1788 | { |
1789 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
1790 | |
1791 | buf->f_type = TMPFS_MAGIC; |
1792 | buf->f_bsize = PAGE_CACHE_SIZE; |
1793 | buf->f_namelen = NAME_MAX; |
1794 | spin_lock(&sbinfo->stat_lock); |
1795 | if (sbinfo->max_blocks) { |
1796 | buf->f_blocks = sbinfo->max_blocks; |
1797 | buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; |
1798 | } |
1799 | if (sbinfo->max_inodes) { |
1800 | buf->f_files = sbinfo->max_inodes; |
1801 | buf->f_ffree = sbinfo->free_inodes; |
1802 | } |
1803 | /* else leave those fields 0 like simple_statfs */ |
1804 | spin_unlock(&sbinfo->stat_lock); |
1805 | return 0; |
1806 | } |
1807 | |
1808 | /* |
1809 | * File creation. Allocate an inode, and we're done.. |
1810 | */ |
1811 | static int |
1812 | shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
1813 | { |
1814 | struct inode *inode; |
1815 | int error = -ENOSPC; |
1816 | |
1817 | inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE); |
1818 | if (inode) { |
1819 | error = security_inode_init_security(inode, dir, NULL, NULL, |
1820 | NULL); |
1821 | if (error) { |
1822 | if (error != -EOPNOTSUPP) { |
1823 | iput(inode); |
1824 | return error; |
1825 | } |
1826 | } |
1827 | #ifdef CONFIG_TMPFS_POSIX_ACL |
1828 | error = generic_acl_init(inode, dir); |
1829 | if (error) { |
1830 | iput(inode); |
1831 | return error; |
1832 | } |
1833 | #else |
1834 | error = 0; |
1835 | #endif |
1836 | if (dir->i_mode & S_ISGID) { |
1837 | inode->i_gid = dir->i_gid; |
1838 | if (S_ISDIR(mode)) |
1839 | inode->i_mode |= S_ISGID; |
1840 | } |
1841 | dir->i_size += BOGO_DIRENT_SIZE; |
1842 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1843 | d_instantiate(dentry, inode); |
1844 | dget(dentry); /* Extra count - pin the dentry in core */ |
1845 | } |
1846 | return error; |
1847 | } |
1848 | |
1849 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
1850 | { |
1851 | int error; |
1852 | |
1853 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
1854 | return error; |
1855 | inc_nlink(dir); |
1856 | return 0; |
1857 | } |
1858 | |
1859 | static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, |
1860 | struct nameidata *nd) |
1861 | { |
1862 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
1863 | } |
1864 | |
1865 | /* |
1866 | * Link a file.. |
1867 | */ |
1868 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
1869 | { |
1870 | struct inode *inode = old_dentry->d_inode; |
1871 | int ret; |
1872 | |
1873 | /* |
1874 | * No ordinary (disk based) filesystem counts links as inodes; |
1875 | * but each new link needs a new dentry, pinning lowmem, and |
1876 | * tmpfs dentries cannot be pruned until they are unlinked. |
1877 | */ |
1878 | ret = shmem_reserve_inode(inode->i_sb); |
1879 | if (ret) |
1880 | goto out; |
1881 | |
1882 | dir->i_size += BOGO_DIRENT_SIZE; |
1883 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1884 | inc_nlink(inode); |
1885 | atomic_inc(&inode->i_count); /* New dentry reference */ |
1886 | dget(dentry); /* Extra pinning count for the created dentry */ |
1887 | d_instantiate(dentry, inode); |
1888 | out: |
1889 | return ret; |
1890 | } |
1891 | |
1892 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
1893 | { |
1894 | struct inode *inode = dentry->d_inode; |
1895 | |
1896 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
1897 | shmem_free_inode(inode->i_sb); |
1898 | |
1899 | dir->i_size -= BOGO_DIRENT_SIZE; |
1900 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1901 | drop_nlink(inode); |
1902 | dput(dentry); /* Undo the count from "create" - this does all the work */ |
1903 | return 0; |
1904 | } |
1905 | |
1906 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
1907 | { |
1908 | if (!simple_empty(dentry)) |
1909 | return -ENOTEMPTY; |
1910 | |
1911 | drop_nlink(dentry->d_inode); |
1912 | drop_nlink(dir); |
1913 | return shmem_unlink(dir, dentry); |
1914 | } |
1915 | |
1916 | /* |
1917 | * The VFS layer already does all the dentry stuff for rename, |
1918 | * we just have to decrement the usage count for the target if |
1919 | * it exists so that the VFS layer correctly free's it when it |
1920 | * gets overwritten. |
1921 | */ |
1922 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
1923 | { |
1924 | struct inode *inode = old_dentry->d_inode; |
1925 | int they_are_dirs = S_ISDIR(inode->i_mode); |
1926 | |
1927 | if (!simple_empty(new_dentry)) |
1928 | return -ENOTEMPTY; |
1929 | |
1930 | if (new_dentry->d_inode) { |
1931 | (void) shmem_unlink(new_dir, new_dentry); |
1932 | if (they_are_dirs) |
1933 | drop_nlink(old_dir); |
1934 | } else if (they_are_dirs) { |
1935 | drop_nlink(old_dir); |
1936 | inc_nlink(new_dir); |
1937 | } |
1938 | |
1939 | old_dir->i_size -= BOGO_DIRENT_SIZE; |
1940 | new_dir->i_size += BOGO_DIRENT_SIZE; |
1941 | old_dir->i_ctime = old_dir->i_mtime = |
1942 | new_dir->i_ctime = new_dir->i_mtime = |
1943 | inode->i_ctime = CURRENT_TIME; |
1944 | return 0; |
1945 | } |
1946 | |
1947 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
1948 | { |
1949 | int error; |
1950 | int len; |
1951 | struct inode *inode; |
1952 | struct page *page = NULL; |
1953 | char *kaddr; |
1954 | struct shmem_inode_info *info; |
1955 | |
1956 | len = strlen(symname) + 1; |
1957 | if (len > PAGE_CACHE_SIZE) |
1958 | return -ENAMETOOLONG; |
1959 | |
1960 | inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
1961 | if (!inode) |
1962 | return -ENOSPC; |
1963 | |
1964 | error = security_inode_init_security(inode, dir, NULL, NULL, |
1965 | NULL); |
1966 | if (error) { |
1967 | if (error != -EOPNOTSUPP) { |
1968 | iput(inode); |
1969 | return error; |
1970 | } |
1971 | error = 0; |
1972 | } |
1973 | |
1974 | info = SHMEM_I(inode); |
1975 | inode->i_size = len-1; |
1976 | if (len <= (char *)inode - (char *)info) { |
1977 | /* do it inline */ |
1978 | memcpy(info, symname, len); |
1979 | inode->i_op = &shmem_symlink_inline_operations; |
1980 | } else { |
1981 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
1982 | if (error) { |
1983 | iput(inode); |
1984 | return error; |
1985 | } |
1986 | inode->i_mapping->a_ops = &shmem_aops; |
1987 | inode->i_op = &shmem_symlink_inode_operations; |
1988 | kaddr = kmap_atomic(page, KM_USER0); |
1989 | memcpy(kaddr, symname, len); |
1990 | kunmap_atomic(kaddr, KM_USER0); |
1991 | set_page_dirty(page); |
1992 | unlock_page(page); |
1993 | page_cache_release(page); |
1994 | } |
1995 | if (dir->i_mode & S_ISGID) |
1996 | inode->i_gid = dir->i_gid; |
1997 | dir->i_size += BOGO_DIRENT_SIZE; |
1998 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1999 | d_instantiate(dentry, inode); |
2000 | dget(dentry); |
2001 | return 0; |
2002 | } |
2003 | |
2004 | static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) |
2005 | { |
2006 | nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); |
2007 | return NULL; |
2008 | } |
2009 | |
2010 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
2011 | { |
2012 | struct page *page = NULL; |
2013 | int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
2014 | nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); |
2015 | if (page) |
2016 | unlock_page(page); |
2017 | return page; |
2018 | } |
2019 | |
2020 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
2021 | { |
2022 | if (!IS_ERR(nd_get_link(nd))) { |
2023 | struct page *page = cookie; |
2024 | kunmap(page); |
2025 | mark_page_accessed(page); |
2026 | page_cache_release(page); |
2027 | } |
2028 | } |
2029 | |
2030 | static const struct inode_operations shmem_symlink_inline_operations = { |
2031 | .readlink = generic_readlink, |
2032 | .follow_link = shmem_follow_link_inline, |
2033 | }; |
2034 | |
2035 | static const struct inode_operations shmem_symlink_inode_operations = { |
2036 | .truncate = shmem_truncate, |
2037 | .readlink = generic_readlink, |
2038 | .follow_link = shmem_follow_link, |
2039 | .put_link = shmem_put_link, |
2040 | }; |
2041 | |
2042 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2043 | /* |
2044 | * Superblocks without xattr inode operations will get security.* xattr |
2045 | * support from the VFS "for free". As soon as we have any other xattrs |
2046 | * like ACLs, we also need to implement the security.* handlers at |
2047 | * filesystem level, though. |
2048 | */ |
2049 | |
2050 | static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, |
2051 | size_t list_len, const char *name, |
2052 | size_t name_len, int handler_flags) |
2053 | { |
2054 | return security_inode_listsecurity(dentry->d_inode, list, list_len); |
2055 | } |
2056 | |
2057 | static int shmem_xattr_security_get(struct dentry *dentry, const char *name, |
2058 | void *buffer, size_t size, int handler_flags) |
2059 | { |
2060 | if (strcmp(name, "") == 0) |
2061 | return -EINVAL; |
2062 | return xattr_getsecurity(dentry->d_inode, name, buffer, size); |
2063 | } |
2064 | |
2065 | static int shmem_xattr_security_set(struct dentry *dentry, const char *name, |
2066 | const void *value, size_t size, int flags, int handler_flags) |
2067 | { |
2068 | if (strcmp(name, "") == 0) |
2069 | return -EINVAL; |
2070 | return security_inode_setsecurity(dentry->d_inode, name, value, |
2071 | size, flags); |
2072 | } |
2073 | |
2074 | static struct xattr_handler shmem_xattr_security_handler = { |
2075 | .prefix = XATTR_SECURITY_PREFIX, |
2076 | .list = shmem_xattr_security_list, |
2077 | .get = shmem_xattr_security_get, |
2078 | .set = shmem_xattr_security_set, |
2079 | }; |
2080 | |
2081 | static struct xattr_handler *shmem_xattr_handlers[] = { |
2082 | &generic_acl_access_handler, |
2083 | &generic_acl_default_handler, |
2084 | &shmem_xattr_security_handler, |
2085 | NULL |
2086 | }; |
2087 | #endif |
2088 | |
2089 | static struct dentry *shmem_get_parent(struct dentry *child) |
2090 | { |
2091 | return ERR_PTR(-ESTALE); |
2092 | } |
2093 | |
2094 | static int shmem_match(struct inode *ino, void *vfh) |
2095 | { |
2096 | __u32 *fh = vfh; |
2097 | __u64 inum = fh[2]; |
2098 | inum = (inum << 32) | fh[1]; |
2099 | return ino->i_ino == inum && fh[0] == ino->i_generation; |
2100 | } |
2101 | |
2102 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
2103 | struct fid *fid, int fh_len, int fh_type) |
2104 | { |
2105 | struct inode *inode; |
2106 | struct dentry *dentry = NULL; |
2107 | u64 inum = fid->raw[2]; |
2108 | inum = (inum << 32) | fid->raw[1]; |
2109 | |
2110 | if (fh_len < 3) |
2111 | return NULL; |
2112 | |
2113 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
2114 | shmem_match, fid->raw); |
2115 | if (inode) { |
2116 | dentry = d_find_alias(inode); |
2117 | iput(inode); |
2118 | } |
2119 | |
2120 | return dentry; |
2121 | } |
2122 | |
2123 | static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, |
2124 | int connectable) |
2125 | { |
2126 | struct inode *inode = dentry->d_inode; |
2127 | |
2128 | if (*len < 3) |
2129 | return 255; |
2130 | |
2131 | if (hlist_unhashed(&inode->i_hash)) { |
2132 | /* Unfortunately insert_inode_hash is not idempotent, |
2133 | * so as we hash inodes here rather than at creation |
2134 | * time, we need a lock to ensure we only try |
2135 | * to do it once |
2136 | */ |
2137 | static DEFINE_SPINLOCK(lock); |
2138 | spin_lock(&lock); |
2139 | if (hlist_unhashed(&inode->i_hash)) |
2140 | __insert_inode_hash(inode, |
2141 | inode->i_ino + inode->i_generation); |
2142 | spin_unlock(&lock); |
2143 | } |
2144 | |
2145 | fh[0] = inode->i_generation; |
2146 | fh[1] = inode->i_ino; |
2147 | fh[2] = ((__u64)inode->i_ino) >> 32; |
2148 | |
2149 | *len = 3; |
2150 | return 1; |
2151 | } |
2152 | |
2153 | static const struct export_operations shmem_export_ops = { |
2154 | .get_parent = shmem_get_parent, |
2155 | .encode_fh = shmem_encode_fh, |
2156 | .fh_to_dentry = shmem_fh_to_dentry, |
2157 | }; |
2158 | |
2159 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
2160 | bool remount) |
2161 | { |
2162 | char *this_char, *value, *rest; |
2163 | |
2164 | while (options != NULL) { |
2165 | this_char = options; |
2166 | for (;;) { |
2167 | /* |
2168 | * NUL-terminate this option: unfortunately, |
2169 | * mount options form a comma-separated list, |
2170 | * but mpol's nodelist may also contain commas. |
2171 | */ |
2172 | options = strchr(options, ','); |
2173 | if (options == NULL) |
2174 | break; |
2175 | options++; |
2176 | if (!isdigit(*options)) { |
2177 | options[-1] = '\0'; |
2178 | break; |
2179 | } |
2180 | } |
2181 | if (!*this_char) |
2182 | continue; |
2183 | if ((value = strchr(this_char,'=')) != NULL) { |
2184 | *value++ = 0; |
2185 | } else { |
2186 | printk(KERN_ERR |
2187 | "tmpfs: No value for mount option '%s'\n", |
2188 | this_char); |
2189 | return 1; |
2190 | } |
2191 | |
2192 | if (!strcmp(this_char,"size")) { |
2193 | unsigned long long size; |
2194 | size = memparse(value,&rest); |
2195 | if (*rest == '%') { |
2196 | size <<= PAGE_SHIFT; |
2197 | size *= totalram_pages; |
2198 | do_div(size, 100); |
2199 | rest++; |
2200 | } |
2201 | if (*rest) |
2202 | goto bad_val; |
2203 | sbinfo->max_blocks = |
2204 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
2205 | } else if (!strcmp(this_char,"nr_blocks")) { |
2206 | sbinfo->max_blocks = memparse(value, &rest); |
2207 | if (*rest) |
2208 | goto bad_val; |
2209 | } else if (!strcmp(this_char,"nr_inodes")) { |
2210 | sbinfo->max_inodes = memparse(value, &rest); |
2211 | if (*rest) |
2212 | goto bad_val; |
2213 | } else if (!strcmp(this_char,"mode")) { |
2214 | if (remount) |
2215 | continue; |
2216 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
2217 | if (*rest) |
2218 | goto bad_val; |
2219 | } else if (!strcmp(this_char,"uid")) { |
2220 | if (remount) |
2221 | continue; |
2222 | sbinfo->uid = simple_strtoul(value, &rest, 0); |
2223 | if (*rest) |
2224 | goto bad_val; |
2225 | } else if (!strcmp(this_char,"gid")) { |
2226 | if (remount) |
2227 | continue; |
2228 | sbinfo->gid = simple_strtoul(value, &rest, 0); |
2229 | if (*rest) |
2230 | goto bad_val; |
2231 | } else if (!strcmp(this_char,"mpol")) { |
2232 | if (mpol_parse_str(value, &sbinfo->mpol, 1)) |
2233 | goto bad_val; |
2234 | } else { |
2235 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
2236 | this_char); |
2237 | return 1; |
2238 | } |
2239 | } |
2240 | return 0; |
2241 | |
2242 | bad_val: |
2243 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
2244 | value, this_char); |
2245 | return 1; |
2246 | |
2247 | } |
2248 | |
2249 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
2250 | { |
2251 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2252 | struct shmem_sb_info config = *sbinfo; |
2253 | unsigned long blocks; |
2254 | unsigned long inodes; |
2255 | int error = -EINVAL; |
2256 | |
2257 | if (shmem_parse_options(data, &config, true)) |
2258 | return error; |
2259 | |
2260 | spin_lock(&sbinfo->stat_lock); |
2261 | blocks = sbinfo->max_blocks - sbinfo->free_blocks; |
2262 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
2263 | if (config.max_blocks < blocks) |
2264 | goto out; |
2265 | if (config.max_inodes < inodes) |
2266 | goto out; |
2267 | /* |
2268 | * Those tests also disallow limited->unlimited while any are in |
2269 | * use, so i_blocks will always be zero when max_blocks is zero; |
2270 | * but we must separately disallow unlimited->limited, because |
2271 | * in that case we have no record of how much is already in use. |
2272 | */ |
2273 | if (config.max_blocks && !sbinfo->max_blocks) |
2274 | goto out; |
2275 | if (config.max_inodes && !sbinfo->max_inodes) |
2276 | goto out; |
2277 | |
2278 | error = 0; |
2279 | sbinfo->max_blocks = config.max_blocks; |
2280 | sbinfo->free_blocks = config.max_blocks - blocks; |
2281 | sbinfo->max_inodes = config.max_inodes; |
2282 | sbinfo->free_inodes = config.max_inodes - inodes; |
2283 | |
2284 | mpol_put(sbinfo->mpol); |
2285 | sbinfo->mpol = config.mpol; /* transfers initial ref */ |
2286 | out: |
2287 | spin_unlock(&sbinfo->stat_lock); |
2288 | return error; |
2289 | } |
2290 | |
2291 | static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) |
2292 | { |
2293 | struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); |
2294 | |
2295 | if (sbinfo->max_blocks != shmem_default_max_blocks()) |
2296 | seq_printf(seq, ",size=%luk", |
2297 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
2298 | if (sbinfo->max_inodes != shmem_default_max_inodes()) |
2299 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
2300 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
2301 | seq_printf(seq, ",mode=%03o", sbinfo->mode); |
2302 | if (sbinfo->uid != 0) |
2303 | seq_printf(seq, ",uid=%u", sbinfo->uid); |
2304 | if (sbinfo->gid != 0) |
2305 | seq_printf(seq, ",gid=%u", sbinfo->gid); |
2306 | shmem_show_mpol(seq, sbinfo->mpol); |
2307 | return 0; |
2308 | } |
2309 | #endif /* CONFIG_TMPFS */ |
2310 | |
2311 | static void shmem_put_super(struct super_block *sb) |
2312 | { |
2313 | kfree(sb->s_fs_info); |
2314 | sb->s_fs_info = NULL; |
2315 | } |
2316 | |
2317 | int shmem_fill_super(struct super_block *sb, void *data, int silent) |
2318 | { |
2319 | struct inode *inode; |
2320 | struct dentry *root; |
2321 | struct shmem_sb_info *sbinfo; |
2322 | int err = -ENOMEM; |
2323 | |
2324 | /* Round up to L1_CACHE_BYTES to resist false sharing */ |
2325 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
2326 | L1_CACHE_BYTES), GFP_KERNEL); |
2327 | if (!sbinfo) |
2328 | return -ENOMEM; |
2329 | |
2330 | sbinfo->mode = S_IRWXUGO | S_ISVTX; |
2331 | sbinfo->uid = current_fsuid(); |
2332 | sbinfo->gid = current_fsgid(); |
2333 | sb->s_fs_info = sbinfo; |
2334 | |
2335 | #ifdef CONFIG_TMPFS |
2336 | /* |
2337 | * Per default we only allow half of the physical ram per |
2338 | * tmpfs instance, limiting inodes to one per page of lowmem; |
2339 | * but the internal instance is left unlimited. |
2340 | */ |
2341 | if (!(sb->s_flags & MS_NOUSER)) { |
2342 | sbinfo->max_blocks = shmem_default_max_blocks(); |
2343 | sbinfo->max_inodes = shmem_default_max_inodes(); |
2344 | if (shmem_parse_options(data, sbinfo, false)) { |
2345 | err = -EINVAL; |
2346 | goto failed; |
2347 | } |
2348 | } |
2349 | sb->s_export_op = &shmem_export_ops; |
2350 | #else |
2351 | sb->s_flags |= MS_NOUSER; |
2352 | #endif |
2353 | |
2354 | spin_lock_init(&sbinfo->stat_lock); |
2355 | sbinfo->free_blocks = sbinfo->max_blocks; |
2356 | sbinfo->free_inodes = sbinfo->max_inodes; |
2357 | |
2358 | sb->s_maxbytes = SHMEM_MAX_BYTES; |
2359 | sb->s_blocksize = PAGE_CACHE_SIZE; |
2360 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
2361 | sb->s_magic = TMPFS_MAGIC; |
2362 | sb->s_op = &shmem_ops; |
2363 | sb->s_time_gran = 1; |
2364 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2365 | sb->s_xattr = shmem_xattr_handlers; |
2366 | sb->s_flags |= MS_POSIXACL; |
2367 | #endif |
2368 | |
2369 | inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
2370 | if (!inode) |
2371 | goto failed; |
2372 | inode->i_uid = sbinfo->uid; |
2373 | inode->i_gid = sbinfo->gid; |
2374 | root = d_alloc_root(inode); |
2375 | if (!root) |
2376 | goto failed_iput; |
2377 | sb->s_root = root; |
2378 | return 0; |
2379 | |
2380 | failed_iput: |
2381 | iput(inode); |
2382 | failed: |
2383 | shmem_put_super(sb); |
2384 | return err; |
2385 | } |
2386 | |
2387 | static struct kmem_cache *shmem_inode_cachep; |
2388 | |
2389 | static struct inode *shmem_alloc_inode(struct super_block *sb) |
2390 | { |
2391 | struct shmem_inode_info *p; |
2392 | p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
2393 | if (!p) |
2394 | return NULL; |
2395 | return &p->vfs_inode; |
2396 | } |
2397 | |
2398 | static void shmem_destroy_inode(struct inode *inode) |
2399 | { |
2400 | if ((inode->i_mode & S_IFMT) == S_IFREG) { |
2401 | /* only struct inode is valid if it's an inline symlink */ |
2402 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
2403 | } |
2404 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
2405 | } |
2406 | |
2407 | static void init_once(void *foo) |
2408 | { |
2409 | struct shmem_inode_info *p = (struct shmem_inode_info *) foo; |
2410 | |
2411 | inode_init_once(&p->vfs_inode); |
2412 | } |
2413 | |
2414 | static int init_inodecache(void) |
2415 | { |
2416 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
2417 | sizeof(struct shmem_inode_info), |
2418 | 0, SLAB_PANIC, init_once); |
2419 | return 0; |
2420 | } |
2421 | |
2422 | static void destroy_inodecache(void) |
2423 | { |
2424 | kmem_cache_destroy(shmem_inode_cachep); |
2425 | } |
2426 | |
2427 | static const struct address_space_operations shmem_aops = { |
2428 | .writepage = shmem_writepage, |
2429 | .set_page_dirty = __set_page_dirty_no_writeback, |
2430 | #ifdef CONFIG_TMPFS |
2431 | .readpage = shmem_readpage, |
2432 | .write_begin = shmem_write_begin, |
2433 | .write_end = shmem_write_end, |
2434 | #endif |
2435 | .migratepage = migrate_page, |
2436 | .error_remove_page = generic_error_remove_page, |
2437 | }; |
2438 | |
2439 | static const struct file_operations shmem_file_operations = { |
2440 | .mmap = shmem_mmap, |
2441 | #ifdef CONFIG_TMPFS |
2442 | .llseek = generic_file_llseek, |
2443 | .read = do_sync_read, |
2444 | .write = do_sync_write, |
2445 | .aio_read = shmem_file_aio_read, |
2446 | .aio_write = generic_file_aio_write, |
2447 | .fsync = simple_sync_file, |
2448 | .splice_read = generic_file_splice_read, |
2449 | .splice_write = generic_file_splice_write, |
2450 | #endif |
2451 | }; |
2452 | |
2453 | static const struct inode_operations shmem_inode_operations = { |
2454 | .truncate = shmem_truncate, |
2455 | .setattr = shmem_notify_change, |
2456 | .truncate_range = shmem_truncate_range, |
2457 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2458 | .setxattr = generic_setxattr, |
2459 | .getxattr = generic_getxattr, |
2460 | .listxattr = generic_listxattr, |
2461 | .removexattr = generic_removexattr, |
2462 | .check_acl = generic_check_acl, |
2463 | #endif |
2464 | |
2465 | }; |
2466 | |
2467 | static const struct inode_operations shmem_dir_inode_operations = { |
2468 | #ifdef CONFIG_TMPFS |
2469 | .create = shmem_create, |
2470 | .lookup = simple_lookup, |
2471 | .link = shmem_link, |
2472 | .unlink = shmem_unlink, |
2473 | .symlink = shmem_symlink, |
2474 | .mkdir = shmem_mkdir, |
2475 | .rmdir = shmem_rmdir, |
2476 | .mknod = shmem_mknod, |
2477 | .rename = shmem_rename, |
2478 | #endif |
2479 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2480 | .setattr = shmem_notify_change, |
2481 | .setxattr = generic_setxattr, |
2482 | .getxattr = generic_getxattr, |
2483 | .listxattr = generic_listxattr, |
2484 | .removexattr = generic_removexattr, |
2485 | .check_acl = generic_check_acl, |
2486 | #endif |
2487 | }; |
2488 | |
2489 | static const struct inode_operations shmem_special_inode_operations = { |
2490 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2491 | .setattr = shmem_notify_change, |
2492 | .setxattr = generic_setxattr, |
2493 | .getxattr = generic_getxattr, |
2494 | .listxattr = generic_listxattr, |
2495 | .removexattr = generic_removexattr, |
2496 | .check_acl = generic_check_acl, |
2497 | #endif |
2498 | }; |
2499 | |
2500 | static const struct super_operations shmem_ops = { |
2501 | .alloc_inode = shmem_alloc_inode, |
2502 | .destroy_inode = shmem_destroy_inode, |
2503 | #ifdef CONFIG_TMPFS |
2504 | .statfs = shmem_statfs, |
2505 | .remount_fs = shmem_remount_fs, |
2506 | .show_options = shmem_show_options, |
2507 | #endif |
2508 | .delete_inode = shmem_delete_inode, |
2509 | .drop_inode = generic_delete_inode, |
2510 | .put_super = shmem_put_super, |
2511 | }; |
2512 | |
2513 | static const struct vm_operations_struct shmem_vm_ops = { |
2514 | .fault = shmem_fault, |
2515 | #ifdef CONFIG_NUMA |
2516 | .set_policy = shmem_set_policy, |
2517 | .get_policy = shmem_get_policy, |
2518 | #endif |
2519 | }; |
2520 | |
2521 | |
2522 | static int shmem_get_sb(struct file_system_type *fs_type, |
2523 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) |
2524 | { |
2525 | return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); |
2526 | } |
2527 | |
2528 | static struct file_system_type tmpfs_fs_type = { |
2529 | .owner = THIS_MODULE, |
2530 | .name = "tmpfs", |
2531 | .get_sb = shmem_get_sb, |
2532 | .kill_sb = kill_litter_super, |
2533 | }; |
2534 | |
2535 | int __init init_tmpfs(void) |
2536 | { |
2537 | int error; |
2538 | |
2539 | error = bdi_init(&shmem_backing_dev_info); |
2540 | if (error) |
2541 | goto out4; |
2542 | |
2543 | error = init_inodecache(); |
2544 | if (error) |
2545 | goto out3; |
2546 | |
2547 | error = register_filesystem(&tmpfs_fs_type); |
2548 | if (error) { |
2549 | printk(KERN_ERR "Could not register tmpfs\n"); |
2550 | goto out2; |
2551 | } |
2552 | |
2553 | shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, |
2554 | tmpfs_fs_type.name, NULL); |
2555 | if (IS_ERR(shm_mnt)) { |
2556 | error = PTR_ERR(shm_mnt); |
2557 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
2558 | goto out1; |
2559 | } |
2560 | return 0; |
2561 | |
2562 | out1: |
2563 | unregister_filesystem(&tmpfs_fs_type); |
2564 | out2: |
2565 | destroy_inodecache(); |
2566 | out3: |
2567 | bdi_destroy(&shmem_backing_dev_info); |
2568 | out4: |
2569 | shm_mnt = ERR_PTR(error); |
2570 | return error; |
2571 | } |
2572 | |
2573 | #else /* !CONFIG_SHMEM */ |
2574 | |
2575 | /* |
2576 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
2577 | * |
2578 | * This is intended for small system where the benefits of the full |
2579 | * shmem code (swap-backed and resource-limited) are outweighed by |
2580 | * their complexity. On systems without swap this code should be |
2581 | * effectively equivalent, but much lighter weight. |
2582 | */ |
2583 | |
2584 | #include <linux/ramfs.h> |
2585 | |
2586 | static struct file_system_type tmpfs_fs_type = { |
2587 | .name = "tmpfs", |
2588 | .get_sb = ramfs_get_sb, |
2589 | .kill_sb = kill_litter_super, |
2590 | }; |
2591 | |
2592 | int __init init_tmpfs(void) |
2593 | { |
2594 | BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); |
2595 | |
2596 | shm_mnt = kern_mount(&tmpfs_fs_type); |
2597 | BUG_ON(IS_ERR(shm_mnt)); |
2598 | |
2599 | return 0; |
2600 | } |
2601 | |
2602 | int shmem_unuse(swp_entry_t entry, struct page *page) |
2603 | { |
2604 | return 0; |
2605 | } |
2606 | |
2607 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
2608 | { |
2609 | return 0; |
2610 | } |
2611 | |
2612 | #define shmem_vm_ops generic_file_vm_ops |
2613 | #define shmem_file_operations ramfs_file_operations |
2614 | #define shmem_get_inode(sb, mode, dev, flags) ramfs_get_inode(sb, mode, dev) |
2615 | #define shmem_acct_size(flags, size) 0 |
2616 | #define shmem_unacct_size(flags, size) do {} while (0) |
2617 | #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE |
2618 | |
2619 | #endif /* CONFIG_SHMEM */ |
2620 | |
2621 | /* common code */ |
2622 | |
2623 | /** |
2624 | * shmem_file_setup - get an unlinked file living in tmpfs |
2625 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2626 | * @size: size to be set for the file |
2627 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2628 | */ |
2629 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
2630 | { |
2631 | int error; |
2632 | struct file *file; |
2633 | struct inode *inode; |
2634 | struct path path; |
2635 | struct dentry *root; |
2636 | struct qstr this; |
2637 | |
2638 | if (IS_ERR(shm_mnt)) |
2639 | return (void *)shm_mnt; |
2640 | |
2641 | if (size < 0 || size > SHMEM_MAX_BYTES) |
2642 | return ERR_PTR(-EINVAL); |
2643 | |
2644 | if (shmem_acct_size(flags, size)) |
2645 | return ERR_PTR(-ENOMEM); |
2646 | |
2647 | error = -ENOMEM; |
2648 | this.name = name; |
2649 | this.len = strlen(name); |
2650 | this.hash = 0; /* will go */ |
2651 | root = shm_mnt->mnt_root; |
2652 | path.dentry = d_alloc(root, &this); |
2653 | if (!path.dentry) |
2654 | goto put_memory; |
2655 | path.mnt = mntget(shm_mnt); |
2656 | |
2657 | error = -ENOSPC; |
2658 | inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags); |
2659 | if (!inode) |
2660 | goto put_dentry; |
2661 | |
2662 | d_instantiate(path.dentry, inode); |
2663 | inode->i_size = size; |
2664 | inode->i_nlink = 0; /* It is unlinked */ |
2665 | #ifndef CONFIG_MMU |
2666 | error = ramfs_nommu_expand_for_mapping(inode, size); |
2667 | if (error) |
2668 | goto put_dentry; |
2669 | #endif |
2670 | |
2671 | error = -ENFILE; |
2672 | file = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
2673 | &shmem_file_operations); |
2674 | if (!file) |
2675 | goto put_dentry; |
2676 | |
2677 | return file; |
2678 | |
2679 | put_dentry: |
2680 | path_put(&path); |
2681 | put_memory: |
2682 | shmem_unacct_size(flags, size); |
2683 | return ERR_PTR(error); |
2684 | } |
2685 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
2686 | |
2687 | /** |
2688 | * shmem_zero_setup - setup a shared anonymous mapping |
2689 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
2690 | */ |
2691 | int shmem_zero_setup(struct vm_area_struct *vma) |
2692 | { |
2693 | struct file *file; |
2694 | loff_t size = vma->vm_end - vma->vm_start; |
2695 | |
2696 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
2697 | if (IS_ERR(file)) |
2698 | return PTR_ERR(file); |
2699 | |
2700 | if (vma->vm_file) |
2701 | fput(vma->vm_file); |
2702 | vma->vm_file = file; |
2703 | vma->vm_ops = &shmem_vm_ops; |
2704 | return 0; |
2705 | } |
2706 |
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