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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/percpu_counter.h> |
32 | #include <linux/swap.h> |
33 | |
34 | static struct vfsmount *shm_mnt; |
35 | |
36 | #ifdef CONFIG_SHMEM |
37 | /* |
38 | * This virtual memory filesystem is heavily based on the ramfs. It |
39 | * extends ramfs by the ability to use swap and honor resource limits |
40 | * which makes it a completely usable filesystem. |
41 | */ |
42 | |
43 | #include <linux/xattr.h> |
44 | #include <linux/exportfs.h> |
45 | #include <linux/posix_acl.h> |
46 | #include <linux/generic_acl.h> |
47 | #include <linux/mman.h> |
48 | #include <linux/string.h> |
49 | #include <linux/slab.h> |
50 | #include <linux/backing-dev.h> |
51 | #include <linux/shmem_fs.h> |
52 | #include <linux/writeback.h> |
53 | #include <linux/blkdev.h> |
54 | #include <linux/security.h> |
55 | #include <linux/swapops.h> |
56 | #include <linux/mempolicy.h> |
57 | #include <linux/namei.h> |
58 | #include <linux/ctype.h> |
59 | #include <linux/migrate.h> |
60 | #include <linux/highmem.h> |
61 | #include <linux/seq_file.h> |
62 | #include <linux/magic.h> |
63 | |
64 | #include <asm/uaccess.h> |
65 | #include <asm/div64.h> |
66 | #include <asm/pgtable.h> |
67 | |
68 | /* |
69 | * The maximum size of a shmem/tmpfs file is limited by the maximum size of |
70 | * its triple-indirect swap vector - see illustration at shmem_swp_entry(). |
71 | * |
72 | * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, |
73 | * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum |
74 | * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, |
75 | * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. |
76 | * |
77 | * We use / and * instead of shifts in the definitions below, so that the swap |
78 | * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. |
79 | */ |
80 | #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) |
81 | #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) |
82 | |
83 | #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) |
84 | #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) |
85 | |
86 | #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) |
87 | #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) |
88 | |
89 | #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) |
90 | #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) |
91 | |
92 | /* info->flags needs VM_flags to handle pagein/truncate races efficiently */ |
93 | #define SHMEM_PAGEIN VM_READ |
94 | #define SHMEM_TRUNCATE VM_WRITE |
95 | |
96 | /* Definition to limit shmem_truncate's steps between cond_rescheds */ |
97 | #define LATENCY_LIMIT 64 |
98 | |
99 | /* Pretend that each entry is of this size in directory's i_size */ |
100 | #define BOGO_DIRENT_SIZE 20 |
101 | |
102 | /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ |
103 | enum sgp_type { |
104 | SGP_READ, /* don't exceed i_size, don't allocate page */ |
105 | SGP_CACHE, /* don't exceed i_size, may allocate page */ |
106 | SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ |
107 | SGP_WRITE, /* may exceed i_size, may allocate page */ |
108 | }; |
109 | |
110 | #ifdef CONFIG_TMPFS |
111 | static unsigned long shmem_default_max_blocks(void) |
112 | { |
113 | return totalram_pages / 2; |
114 | } |
115 | |
116 | static unsigned long shmem_default_max_inodes(void) |
117 | { |
118 | return min(totalram_pages - totalhigh_pages, totalram_pages / 2); |
119 | } |
120 | #endif |
121 | |
122 | static int shmem_getpage(struct inode *inode, unsigned long idx, |
123 | struct page **pagep, enum sgp_type sgp, int *type); |
124 | |
125 | static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) |
126 | { |
127 | /* |
128 | * The above definition of ENTRIES_PER_PAGE, and the use of |
129 | * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: |
130 | * might be reconsidered if it ever diverges from PAGE_SIZE. |
131 | * |
132 | * Mobility flags are masked out as swap vectors cannot move |
133 | */ |
134 | return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, |
135 | PAGE_CACHE_SHIFT-PAGE_SHIFT); |
136 | } |
137 | |
138 | static inline void shmem_dir_free(struct page *page) |
139 | { |
140 | __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); |
141 | } |
142 | |
143 | static struct page **shmem_dir_map(struct page *page) |
144 | { |
145 | return (struct page **)kmap_atomic(page, KM_USER0); |
146 | } |
147 | |
148 | static inline void shmem_dir_unmap(struct page **dir) |
149 | { |
150 | kunmap_atomic(dir, KM_USER0); |
151 | } |
152 | |
153 | static swp_entry_t *shmem_swp_map(struct page *page) |
154 | { |
155 | return (swp_entry_t *)kmap_atomic(page, KM_USER1); |
156 | } |
157 | |
158 | static inline void shmem_swp_balance_unmap(void) |
159 | { |
160 | /* |
161 | * When passing a pointer to an i_direct entry, to code which |
162 | * also handles indirect entries and so will shmem_swp_unmap, |
163 | * we must arrange for the preempt count to remain in balance. |
164 | * What kmap_atomic of a lowmem page does depends on config |
165 | * and architecture, so pretend to kmap_atomic some lowmem page. |
166 | */ |
167 | (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); |
168 | } |
169 | |
170 | static inline void shmem_swp_unmap(swp_entry_t *entry) |
171 | { |
172 | kunmap_atomic(entry, KM_USER1); |
173 | } |
174 | |
175 | static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
176 | { |
177 | return sb->s_fs_info; |
178 | } |
179 | |
180 | /* |
181 | * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
182 | * for shared memory and for shared anonymous (/dev/zero) mappings |
183 | * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
184 | * consistent with the pre-accounting of private mappings ... |
185 | */ |
186 | static inline int shmem_acct_size(unsigned long flags, loff_t size) |
187 | { |
188 | return (flags & VM_NORESERVE) ? |
189 | 0 : security_vm_enough_memory_kern(VM_ACCT(size)); |
190 | } |
191 | |
192 | static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
193 | { |
194 | if (!(flags & VM_NORESERVE)) |
195 | vm_unacct_memory(VM_ACCT(size)); |
196 | } |
197 | |
198 | /* |
199 | * ... whereas tmpfs objects are accounted incrementally as |
200 | * pages are allocated, in order to allow huge sparse files. |
201 | * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
202 | * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
203 | */ |
204 | static inline int shmem_acct_block(unsigned long flags) |
205 | { |
206 | return (flags & VM_NORESERVE) ? |
207 | security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; |
208 | } |
209 | |
210 | static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
211 | { |
212 | if (flags & VM_NORESERVE) |
213 | vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); |
214 | } |
215 | |
216 | static const struct super_operations shmem_ops; |
217 | static const struct address_space_operations shmem_aops; |
218 | static const struct file_operations shmem_file_operations; |
219 | static const struct inode_operations shmem_inode_operations; |
220 | static const struct inode_operations shmem_dir_inode_operations; |
221 | static const struct inode_operations shmem_special_inode_operations; |
222 | static const struct vm_operations_struct shmem_vm_ops; |
223 | |
224 | static struct backing_dev_info shmem_backing_dev_info __read_mostly = { |
225 | .ra_pages = 0, /* No readahead */ |
226 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, |
227 | .unplug_io_fn = default_unplug_io_fn, |
228 | }; |
229 | |
230 | static LIST_HEAD(shmem_swaplist); |
231 | static DEFINE_MUTEX(shmem_swaplist_mutex); |
232 | |
233 | static void shmem_free_blocks(struct inode *inode, long pages) |
234 | { |
235 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
236 | if (sbinfo->max_blocks) { |
237 | percpu_counter_add(&sbinfo->used_blocks, -pages); |
238 | spin_lock(&inode->i_lock); |
239 | inode->i_blocks -= pages*BLOCKS_PER_PAGE; |
240 | spin_unlock(&inode->i_lock); |
241 | } |
242 | } |
243 | |
244 | static int shmem_reserve_inode(struct super_block *sb) |
245 | { |
246 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
247 | if (sbinfo->max_inodes) { |
248 | spin_lock(&sbinfo->stat_lock); |
249 | if (!sbinfo->free_inodes) { |
250 | spin_unlock(&sbinfo->stat_lock); |
251 | return -ENOSPC; |
252 | } |
253 | sbinfo->free_inodes--; |
254 | spin_unlock(&sbinfo->stat_lock); |
255 | } |
256 | return 0; |
257 | } |
258 | |
259 | static void shmem_free_inode(struct super_block *sb) |
260 | { |
261 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
262 | if (sbinfo->max_inodes) { |
263 | spin_lock(&sbinfo->stat_lock); |
264 | sbinfo->free_inodes++; |
265 | spin_unlock(&sbinfo->stat_lock); |
266 | } |
267 | } |
268 | |
269 | /** |
270 | * shmem_recalc_inode - recalculate the size of an inode |
271 | * @inode: inode to recalc |
272 | * |
273 | * We have to calculate the free blocks since the mm can drop |
274 | * undirtied hole pages behind our back. |
275 | * |
276 | * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
277 | * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
278 | * |
279 | * It has to be called with the spinlock held. |
280 | */ |
281 | static void shmem_recalc_inode(struct inode *inode) |
282 | { |
283 | struct shmem_inode_info *info = SHMEM_I(inode); |
284 | long freed; |
285 | |
286 | freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
287 | if (freed > 0) { |
288 | info->alloced -= freed; |
289 | shmem_unacct_blocks(info->flags, freed); |
290 | shmem_free_blocks(inode, freed); |
291 | } |
292 | } |
293 | |
294 | /** |
295 | * shmem_swp_entry - find the swap vector position in the info structure |
296 | * @info: info structure for the inode |
297 | * @index: index of the page to find |
298 | * @page: optional page to add to the structure. Has to be preset to |
299 | * all zeros |
300 | * |
301 | * If there is no space allocated yet it will return NULL when |
302 | * page is NULL, else it will use the page for the needed block, |
303 | * setting it to NULL on return to indicate that it has been used. |
304 | * |
305 | * The swap vector is organized the following way: |
306 | * |
307 | * There are SHMEM_NR_DIRECT entries directly stored in the |
308 | * shmem_inode_info structure. So small files do not need an addional |
309 | * allocation. |
310 | * |
311 | * For pages with index > SHMEM_NR_DIRECT there is the pointer |
312 | * i_indirect which points to a page which holds in the first half |
313 | * doubly indirect blocks, in the second half triple indirect blocks: |
314 | * |
315 | * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the |
316 | * following layout (for SHMEM_NR_DIRECT == 16): |
317 | * |
318 | * i_indirect -> dir --> 16-19 |
319 | * | +-> 20-23 |
320 | * | |
321 | * +-->dir2 --> 24-27 |
322 | * | +-> 28-31 |
323 | * | +-> 32-35 |
324 | * | +-> 36-39 |
325 | * | |
326 | * +-->dir3 --> 40-43 |
327 | * +-> 44-47 |
328 | * +-> 48-51 |
329 | * +-> 52-55 |
330 | */ |
331 | static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) |
332 | { |
333 | unsigned long offset; |
334 | struct page **dir; |
335 | struct page *subdir; |
336 | |
337 | if (index < SHMEM_NR_DIRECT) { |
338 | shmem_swp_balance_unmap(); |
339 | return info->i_direct+index; |
340 | } |
341 | if (!info->i_indirect) { |
342 | if (page) { |
343 | info->i_indirect = *page; |
344 | *page = NULL; |
345 | } |
346 | return NULL; /* need another page */ |
347 | } |
348 | |
349 | index -= SHMEM_NR_DIRECT; |
350 | offset = index % ENTRIES_PER_PAGE; |
351 | index /= ENTRIES_PER_PAGE; |
352 | dir = shmem_dir_map(info->i_indirect); |
353 | |
354 | if (index >= ENTRIES_PER_PAGE/2) { |
355 | index -= ENTRIES_PER_PAGE/2; |
356 | dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; |
357 | index %= ENTRIES_PER_PAGE; |
358 | subdir = *dir; |
359 | if (!subdir) { |
360 | if (page) { |
361 | *dir = *page; |
362 | *page = NULL; |
363 | } |
364 | shmem_dir_unmap(dir); |
365 | return NULL; /* need another page */ |
366 | } |
367 | shmem_dir_unmap(dir); |
368 | dir = shmem_dir_map(subdir); |
369 | } |
370 | |
371 | dir += index; |
372 | subdir = *dir; |
373 | if (!subdir) { |
374 | if (!page || !(subdir = *page)) { |
375 | shmem_dir_unmap(dir); |
376 | return NULL; /* need a page */ |
377 | } |
378 | *dir = subdir; |
379 | *page = NULL; |
380 | } |
381 | shmem_dir_unmap(dir); |
382 | return shmem_swp_map(subdir) + offset; |
383 | } |
384 | |
385 | static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) |
386 | { |
387 | long incdec = value? 1: -1; |
388 | |
389 | entry->val = value; |
390 | info->swapped += incdec; |
391 | if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { |
392 | struct page *page = kmap_atomic_to_page(entry); |
393 | set_page_private(page, page_private(page) + incdec); |
394 | } |
395 | } |
396 | |
397 | /** |
398 | * shmem_swp_alloc - get the position of the swap entry for the page. |
399 | * @info: info structure for the inode |
400 | * @index: index of the page to find |
401 | * @sgp: check and recheck i_size? skip allocation? |
402 | * |
403 | * If the entry does not exist, allocate it. |
404 | */ |
405 | static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) |
406 | { |
407 | struct inode *inode = &info->vfs_inode; |
408 | struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
409 | struct page *page = NULL; |
410 | swp_entry_t *entry; |
411 | |
412 | if (sgp != SGP_WRITE && |
413 | ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
414 | return ERR_PTR(-EINVAL); |
415 | |
416 | while (!(entry = shmem_swp_entry(info, index, &page))) { |
417 | if (sgp == SGP_READ) |
418 | return shmem_swp_map(ZERO_PAGE(0)); |
419 | /* |
420 | * Test used_blocks against 1 less max_blocks, since we have 1 data |
421 | * page (and perhaps indirect index pages) yet to allocate: |
422 | * a waste to allocate index if we cannot allocate data. |
423 | */ |
424 | if (sbinfo->max_blocks) { |
425 | if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0) |
426 | return ERR_PTR(-ENOSPC); |
427 | percpu_counter_inc(&sbinfo->used_blocks); |
428 | spin_lock(&inode->i_lock); |
429 | inode->i_blocks += BLOCKS_PER_PAGE; |
430 | spin_unlock(&inode->i_lock); |
431 | } |
432 | |
433 | spin_unlock(&info->lock); |
434 | page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); |
435 | spin_lock(&info->lock); |
436 | |
437 | if (!page) { |
438 | shmem_free_blocks(inode, 1); |
439 | return ERR_PTR(-ENOMEM); |
440 | } |
441 | if (sgp != SGP_WRITE && |
442 | ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { |
443 | entry = ERR_PTR(-EINVAL); |
444 | break; |
445 | } |
446 | if (info->next_index <= index) |
447 | info->next_index = index + 1; |
448 | } |
449 | if (page) { |
450 | /* another task gave its page, or truncated the file */ |
451 | shmem_free_blocks(inode, 1); |
452 | shmem_dir_free(page); |
453 | } |
454 | if (info->next_index <= index && !IS_ERR(entry)) |
455 | info->next_index = index + 1; |
456 | return entry; |
457 | } |
458 | |
459 | /** |
460 | * shmem_free_swp - free some swap entries in a directory |
461 | * @dir: pointer to the directory |
462 | * @edir: pointer after last entry of the directory |
463 | * @punch_lock: pointer to spinlock when needed for the holepunch case |
464 | */ |
465 | static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, |
466 | spinlock_t *punch_lock) |
467 | { |
468 | spinlock_t *punch_unlock = NULL; |
469 | swp_entry_t *ptr; |
470 | int freed = 0; |
471 | |
472 | for (ptr = dir; ptr < edir; ptr++) { |
473 | if (ptr->val) { |
474 | if (unlikely(punch_lock)) { |
475 | punch_unlock = punch_lock; |
476 | punch_lock = NULL; |
477 | spin_lock(punch_unlock); |
478 | if (!ptr->val) |
479 | continue; |
480 | } |
481 | free_swap_and_cache(*ptr); |
482 | *ptr = (swp_entry_t){0}; |
483 | freed++; |
484 | } |
485 | } |
486 | if (punch_unlock) |
487 | spin_unlock(punch_unlock); |
488 | return freed; |
489 | } |
490 | |
491 | static int shmem_map_and_free_swp(struct page *subdir, int offset, |
492 | int limit, struct page ***dir, spinlock_t *punch_lock) |
493 | { |
494 | swp_entry_t *ptr; |
495 | int freed = 0; |
496 | |
497 | ptr = shmem_swp_map(subdir); |
498 | for (; offset < limit; offset += LATENCY_LIMIT) { |
499 | int size = limit - offset; |
500 | if (size > LATENCY_LIMIT) |
501 | size = LATENCY_LIMIT; |
502 | freed += shmem_free_swp(ptr+offset, ptr+offset+size, |
503 | punch_lock); |
504 | if (need_resched()) { |
505 | shmem_swp_unmap(ptr); |
506 | if (*dir) { |
507 | shmem_dir_unmap(*dir); |
508 | *dir = NULL; |
509 | } |
510 | cond_resched(); |
511 | ptr = shmem_swp_map(subdir); |
512 | } |
513 | } |
514 | shmem_swp_unmap(ptr); |
515 | return freed; |
516 | } |
517 | |
518 | static void shmem_free_pages(struct list_head *next) |
519 | { |
520 | struct page *page; |
521 | int freed = 0; |
522 | |
523 | do { |
524 | page = container_of(next, struct page, lru); |
525 | next = next->next; |
526 | shmem_dir_free(page); |
527 | freed++; |
528 | if (freed >= LATENCY_LIMIT) { |
529 | cond_resched(); |
530 | freed = 0; |
531 | } |
532 | } while (next); |
533 | } |
534 | |
535 | static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) |
536 | { |
537 | struct shmem_inode_info *info = SHMEM_I(inode); |
538 | unsigned long idx; |
539 | unsigned long size; |
540 | unsigned long limit; |
541 | unsigned long stage; |
542 | unsigned long diroff; |
543 | struct page **dir; |
544 | struct page *topdir; |
545 | struct page *middir; |
546 | struct page *subdir; |
547 | swp_entry_t *ptr; |
548 | LIST_HEAD(pages_to_free); |
549 | long nr_pages_to_free = 0; |
550 | long nr_swaps_freed = 0; |
551 | int offset; |
552 | int freed; |
553 | int punch_hole; |
554 | spinlock_t *needs_lock; |
555 | spinlock_t *punch_lock; |
556 | unsigned long upper_limit; |
557 | |
558 | inode->i_ctime = inode->i_mtime = CURRENT_TIME; |
559 | idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
560 | if (idx >= info->next_index) |
561 | return; |
562 | |
563 | spin_lock(&info->lock); |
564 | info->flags |= SHMEM_TRUNCATE; |
565 | if (likely(end == (loff_t) -1)) { |
566 | limit = info->next_index; |
567 | upper_limit = SHMEM_MAX_INDEX; |
568 | info->next_index = idx; |
569 | needs_lock = NULL; |
570 | punch_hole = 0; |
571 | } else { |
572 | if (end + 1 >= inode->i_size) { /* we may free a little more */ |
573 | limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> |
574 | PAGE_CACHE_SHIFT; |
575 | upper_limit = SHMEM_MAX_INDEX; |
576 | } else { |
577 | limit = (end + 1) >> PAGE_CACHE_SHIFT; |
578 | upper_limit = limit; |
579 | } |
580 | needs_lock = &info->lock; |
581 | punch_hole = 1; |
582 | } |
583 | |
584 | topdir = info->i_indirect; |
585 | if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { |
586 | info->i_indirect = NULL; |
587 | nr_pages_to_free++; |
588 | list_add(&topdir->lru, &pages_to_free); |
589 | } |
590 | spin_unlock(&info->lock); |
591 | |
592 | if (info->swapped && idx < SHMEM_NR_DIRECT) { |
593 | ptr = info->i_direct; |
594 | size = limit; |
595 | if (size > SHMEM_NR_DIRECT) |
596 | size = SHMEM_NR_DIRECT; |
597 | nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); |
598 | } |
599 | |
600 | /* |
601 | * If there are no indirect blocks or we are punching a hole |
602 | * below indirect blocks, nothing to be done. |
603 | */ |
604 | if (!topdir || limit <= SHMEM_NR_DIRECT) |
605 | goto done2; |
606 | |
607 | /* |
608 | * The truncation case has already dropped info->lock, and we're safe |
609 | * because i_size and next_index have already been lowered, preventing |
610 | * access beyond. But in the punch_hole case, we still need to take |
611 | * the lock when updating the swap directory, because there might be |
612 | * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or |
613 | * shmem_writepage. However, whenever we find we can remove a whole |
614 | * directory page (not at the misaligned start or end of the range), |
615 | * we first NULLify its pointer in the level above, and then have no |
616 | * need to take the lock when updating its contents: needs_lock and |
617 | * punch_lock (either pointing to info->lock or NULL) manage this. |
618 | */ |
619 | |
620 | upper_limit -= SHMEM_NR_DIRECT; |
621 | limit -= SHMEM_NR_DIRECT; |
622 | idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; |
623 | offset = idx % ENTRIES_PER_PAGE; |
624 | idx -= offset; |
625 | |
626 | dir = shmem_dir_map(topdir); |
627 | stage = ENTRIES_PER_PAGEPAGE/2; |
628 | if (idx < ENTRIES_PER_PAGEPAGE/2) { |
629 | middir = topdir; |
630 | diroff = idx/ENTRIES_PER_PAGE; |
631 | } else { |
632 | dir += ENTRIES_PER_PAGE/2; |
633 | dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; |
634 | while (stage <= idx) |
635 | stage += ENTRIES_PER_PAGEPAGE; |
636 | middir = *dir; |
637 | if (*dir) { |
638 | diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % |
639 | ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; |
640 | if (!diroff && !offset && upper_limit >= stage) { |
641 | if (needs_lock) { |
642 | spin_lock(needs_lock); |
643 | *dir = NULL; |
644 | spin_unlock(needs_lock); |
645 | needs_lock = NULL; |
646 | } else |
647 | *dir = NULL; |
648 | nr_pages_to_free++; |
649 | list_add(&middir->lru, &pages_to_free); |
650 | } |
651 | shmem_dir_unmap(dir); |
652 | dir = shmem_dir_map(middir); |
653 | } else { |
654 | diroff = 0; |
655 | offset = 0; |
656 | idx = stage; |
657 | } |
658 | } |
659 | |
660 | for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { |
661 | if (unlikely(idx == stage)) { |
662 | shmem_dir_unmap(dir); |
663 | dir = shmem_dir_map(topdir) + |
664 | ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; |
665 | while (!*dir) { |
666 | dir++; |
667 | idx += ENTRIES_PER_PAGEPAGE; |
668 | if (idx >= limit) |
669 | goto done1; |
670 | } |
671 | stage = idx + ENTRIES_PER_PAGEPAGE; |
672 | middir = *dir; |
673 | if (punch_hole) |
674 | needs_lock = &info->lock; |
675 | if (upper_limit >= stage) { |
676 | if (needs_lock) { |
677 | spin_lock(needs_lock); |
678 | *dir = NULL; |
679 | spin_unlock(needs_lock); |
680 | needs_lock = NULL; |
681 | } else |
682 | *dir = NULL; |
683 | nr_pages_to_free++; |
684 | list_add(&middir->lru, &pages_to_free); |
685 | } |
686 | shmem_dir_unmap(dir); |
687 | cond_resched(); |
688 | dir = shmem_dir_map(middir); |
689 | diroff = 0; |
690 | } |
691 | punch_lock = needs_lock; |
692 | subdir = dir[diroff]; |
693 | if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { |
694 | if (needs_lock) { |
695 | spin_lock(needs_lock); |
696 | dir[diroff] = NULL; |
697 | spin_unlock(needs_lock); |
698 | punch_lock = NULL; |
699 | } else |
700 | dir[diroff] = NULL; |
701 | nr_pages_to_free++; |
702 | list_add(&subdir->lru, &pages_to_free); |
703 | } |
704 | if (subdir && page_private(subdir) /* has swap entries */) { |
705 | size = limit - idx; |
706 | if (size > ENTRIES_PER_PAGE) |
707 | size = ENTRIES_PER_PAGE; |
708 | freed = shmem_map_and_free_swp(subdir, |
709 | offset, size, &dir, punch_lock); |
710 | if (!dir) |
711 | dir = shmem_dir_map(middir); |
712 | nr_swaps_freed += freed; |
713 | if (offset || punch_lock) { |
714 | spin_lock(&info->lock); |
715 | set_page_private(subdir, |
716 | page_private(subdir) - freed); |
717 | spin_unlock(&info->lock); |
718 | } else |
719 | BUG_ON(page_private(subdir) != freed); |
720 | } |
721 | offset = 0; |
722 | } |
723 | done1: |
724 | shmem_dir_unmap(dir); |
725 | done2: |
726 | if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { |
727 | /* |
728 | * Call truncate_inode_pages again: racing shmem_unuse_inode |
729 | * may have swizzled a page in from swap since |
730 | * truncate_pagecache or generic_delete_inode did it, before we |
731 | * lowered next_index. Also, though shmem_getpage checks |
732 | * i_size before adding to cache, no recheck after: so fix the |
733 | * narrow window there too. |
734 | * |
735 | * Recalling truncate_inode_pages_range and unmap_mapping_range |
736 | * every time for punch_hole (which never got a chance to clear |
737 | * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, |
738 | * yet hardly ever necessary: try to optimize them out later. |
739 | */ |
740 | truncate_inode_pages_range(inode->i_mapping, start, end); |
741 | if (punch_hole) |
742 | unmap_mapping_range(inode->i_mapping, start, |
743 | end - start, 1); |
744 | } |
745 | |
746 | spin_lock(&info->lock); |
747 | info->flags &= ~SHMEM_TRUNCATE; |
748 | info->swapped -= nr_swaps_freed; |
749 | if (nr_pages_to_free) |
750 | shmem_free_blocks(inode, nr_pages_to_free); |
751 | shmem_recalc_inode(inode); |
752 | spin_unlock(&info->lock); |
753 | |
754 | /* |
755 | * Empty swap vector directory pages to be freed? |
756 | */ |
757 | if (!list_empty(&pages_to_free)) { |
758 | pages_to_free.prev->next = NULL; |
759 | shmem_free_pages(pages_to_free.next); |
760 | } |
761 | } |
762 | |
763 | static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) |
764 | { |
765 | struct inode *inode = dentry->d_inode; |
766 | loff_t newsize = attr->ia_size; |
767 | int error; |
768 | |
769 | error = inode_change_ok(inode, attr); |
770 | if (error) |
771 | return error; |
772 | |
773 | if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) |
774 | && newsize != inode->i_size) { |
775 | struct page *page = NULL; |
776 | |
777 | if (newsize < 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 (newsize & (PAGE_CACHE_SIZE-1)) { |
786 | (void) shmem_getpage(inode, |
787 | newsize >> 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 (newsize) { |
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 | /* XXX(truncate): truncate_setsize should be called last */ |
808 | truncate_setsize(inode, newsize); |
809 | if (page) |
810 | page_cache_release(page); |
811 | shmem_truncate_range(inode, newsize, (loff_t)-1); |
812 | } |
813 | |
814 | setattr_copy(inode, attr); |
815 | #ifdef CONFIG_TMPFS_POSIX_ACL |
816 | if (attr->ia_valid & ATTR_MODE) |
817 | error = generic_acl_chmod(inode); |
818 | #endif |
819 | return error; |
820 | } |
821 | |
822 | static void shmem_evict_inode(struct inode *inode) |
823 | { |
824 | struct shmem_inode_info *info = SHMEM_I(inode); |
825 | |
826 | if (inode->i_mapping->a_ops == &shmem_aops) { |
827 | truncate_inode_pages(inode->i_mapping, 0); |
828 | shmem_unacct_size(info->flags, inode->i_size); |
829 | inode->i_size = 0; |
830 | shmem_truncate_range(inode, 0, (loff_t)-1); |
831 | if (!list_empty(&info->swaplist)) { |
832 | mutex_lock(&shmem_swaplist_mutex); |
833 | list_del_init(&info->swaplist); |
834 | mutex_unlock(&shmem_swaplist_mutex); |
835 | } |
836 | } |
837 | BUG_ON(inode->i_blocks); |
838 | shmem_free_inode(inode->i_sb); |
839 | end_writeback(inode); |
840 | } |
841 | |
842 | static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) |
843 | { |
844 | swp_entry_t *ptr; |
845 | |
846 | for (ptr = dir; ptr < edir; ptr++) { |
847 | if (ptr->val == entry.val) |
848 | return ptr - dir; |
849 | } |
850 | return -1; |
851 | } |
852 | |
853 | static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) |
854 | { |
855 | struct inode *inode; |
856 | unsigned long idx; |
857 | unsigned long size; |
858 | unsigned long limit; |
859 | unsigned long stage; |
860 | struct page **dir; |
861 | struct page *subdir; |
862 | swp_entry_t *ptr; |
863 | int offset; |
864 | int error; |
865 | |
866 | idx = 0; |
867 | ptr = info->i_direct; |
868 | spin_lock(&info->lock); |
869 | if (!info->swapped) { |
870 | list_del_init(&info->swaplist); |
871 | goto lost2; |
872 | } |
873 | limit = info->next_index; |
874 | size = limit; |
875 | if (size > SHMEM_NR_DIRECT) |
876 | size = SHMEM_NR_DIRECT; |
877 | offset = shmem_find_swp(entry, ptr, ptr+size); |
878 | if (offset >= 0) |
879 | goto found; |
880 | if (!info->i_indirect) |
881 | goto lost2; |
882 | |
883 | dir = shmem_dir_map(info->i_indirect); |
884 | stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; |
885 | |
886 | for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { |
887 | if (unlikely(idx == stage)) { |
888 | shmem_dir_unmap(dir-1); |
889 | if (cond_resched_lock(&info->lock)) { |
890 | /* check it has not been truncated */ |
891 | if (limit > info->next_index) { |
892 | limit = info->next_index; |
893 | if (idx >= limit) |
894 | goto lost2; |
895 | } |
896 | } |
897 | dir = shmem_dir_map(info->i_indirect) + |
898 | ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; |
899 | while (!*dir) { |
900 | dir++; |
901 | idx += ENTRIES_PER_PAGEPAGE; |
902 | if (idx >= limit) |
903 | goto lost1; |
904 | } |
905 | stage = idx + ENTRIES_PER_PAGEPAGE; |
906 | subdir = *dir; |
907 | shmem_dir_unmap(dir); |
908 | dir = shmem_dir_map(subdir); |
909 | } |
910 | subdir = *dir; |
911 | if (subdir && page_private(subdir)) { |
912 | ptr = shmem_swp_map(subdir); |
913 | size = limit - idx; |
914 | if (size > ENTRIES_PER_PAGE) |
915 | size = ENTRIES_PER_PAGE; |
916 | offset = shmem_find_swp(entry, ptr, ptr+size); |
917 | shmem_swp_unmap(ptr); |
918 | if (offset >= 0) { |
919 | shmem_dir_unmap(dir); |
920 | goto found; |
921 | } |
922 | } |
923 | } |
924 | lost1: |
925 | shmem_dir_unmap(dir-1); |
926 | lost2: |
927 | spin_unlock(&info->lock); |
928 | return 0; |
929 | found: |
930 | idx += offset; |
931 | inode = igrab(&info->vfs_inode); |
932 | spin_unlock(&info->lock); |
933 | |
934 | /* |
935 | * Move _head_ to start search for next from here. |
936 | * But be careful: shmem_evict_inode checks list_empty without taking |
937 | * mutex, and there's an instant in list_move_tail when info->swaplist |
938 | * would appear empty, if it were the only one on shmem_swaplist. We |
939 | * could avoid doing it if inode NULL; or use this minor optimization. |
940 | */ |
941 | if (shmem_swaplist.next != &info->swaplist) |
942 | list_move_tail(&shmem_swaplist, &info->swaplist); |
943 | mutex_unlock(&shmem_swaplist_mutex); |
944 | |
945 | error = 1; |
946 | if (!inode) |
947 | goto out; |
948 | /* |
949 | * Charge page using GFP_KERNEL while we can wait. |
950 | * Charged back to the user(not to caller) when swap account is used. |
951 | * add_to_page_cache() will be called with GFP_NOWAIT. |
952 | */ |
953 | error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); |
954 | if (error) |
955 | goto out; |
956 | error = radix_tree_preload(GFP_KERNEL); |
957 | if (error) { |
958 | mem_cgroup_uncharge_cache_page(page); |
959 | goto out; |
960 | } |
961 | error = 1; |
962 | |
963 | spin_lock(&info->lock); |
964 | ptr = shmem_swp_entry(info, idx, NULL); |
965 | if (ptr && ptr->val == entry.val) { |
966 | error = add_to_page_cache_locked(page, inode->i_mapping, |
967 | idx, GFP_NOWAIT); |
968 | /* does mem_cgroup_uncharge_cache_page on error */ |
969 | } else /* we must compensate for our precharge above */ |
970 | mem_cgroup_uncharge_cache_page(page); |
971 | |
972 | if (error == -EEXIST) { |
973 | struct page *filepage = find_get_page(inode->i_mapping, idx); |
974 | error = 1; |
975 | if (filepage) { |
976 | /* |
977 | * There might be a more uptodate page coming down |
978 | * from a stacked writepage: forget our swappage if so. |
979 | */ |
980 | if (PageUptodate(filepage)) |
981 | error = 0; |
982 | page_cache_release(filepage); |
983 | } |
984 | } |
985 | if (!error) { |
986 | delete_from_swap_cache(page); |
987 | set_page_dirty(page); |
988 | info->flags |= SHMEM_PAGEIN; |
989 | shmem_swp_set(info, ptr, 0); |
990 | swap_free(entry); |
991 | error = 1; /* not an error, but entry was found */ |
992 | } |
993 | if (ptr) |
994 | shmem_swp_unmap(ptr); |
995 | spin_unlock(&info->lock); |
996 | radix_tree_preload_end(); |
997 | out: |
998 | unlock_page(page); |
999 | page_cache_release(page); |
1000 | iput(inode); /* allows for NULL */ |
1001 | return error; |
1002 | } |
1003 | |
1004 | /* |
1005 | * shmem_unuse() search for an eventually swapped out shmem page. |
1006 | */ |
1007 | int shmem_unuse(swp_entry_t entry, struct page *page) |
1008 | { |
1009 | struct list_head *p, *next; |
1010 | struct shmem_inode_info *info; |
1011 | int found = 0; |
1012 | |
1013 | mutex_lock(&shmem_swaplist_mutex); |
1014 | list_for_each_safe(p, next, &shmem_swaplist) { |
1015 | info = list_entry(p, struct shmem_inode_info, swaplist); |
1016 | found = shmem_unuse_inode(info, entry, page); |
1017 | cond_resched(); |
1018 | if (found) |
1019 | goto out; |
1020 | } |
1021 | mutex_unlock(&shmem_swaplist_mutex); |
1022 | /* |
1023 | * Can some race bring us here? We've been holding page lock, |
1024 | * so I think not; but would rather try again later than BUG() |
1025 | */ |
1026 | unlock_page(page); |
1027 | page_cache_release(page); |
1028 | out: |
1029 | return (found < 0) ? found : 0; |
1030 | } |
1031 | |
1032 | /* |
1033 | * Move the page from the page cache to the swap cache. |
1034 | */ |
1035 | static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
1036 | { |
1037 | struct shmem_inode_info *info; |
1038 | swp_entry_t *entry, swap; |
1039 | struct address_space *mapping; |
1040 | unsigned long index; |
1041 | struct inode *inode; |
1042 | |
1043 | BUG_ON(!PageLocked(page)); |
1044 | mapping = page->mapping; |
1045 | index = page->index; |
1046 | inode = mapping->host; |
1047 | info = SHMEM_I(inode); |
1048 | if (info->flags & VM_LOCKED) |
1049 | goto redirty; |
1050 | if (!total_swap_pages) |
1051 | goto redirty; |
1052 | |
1053 | /* |
1054 | * shmem_backing_dev_info's capabilities prevent regular writeback or |
1055 | * sync from ever calling shmem_writepage; but a stacking filesystem |
1056 | * may use the ->writepage of its underlying filesystem, in which case |
1057 | * tmpfs should write out to swap only in response to memory pressure, |
1058 | * and not for the writeback threads or sync. However, in those cases, |
1059 | * we do still want to check if there's a redundant swappage to be |
1060 | * discarded. |
1061 | */ |
1062 | if (wbc->for_reclaim) |
1063 | swap = get_swap_page(); |
1064 | else |
1065 | swap.val = 0; |
1066 | |
1067 | spin_lock(&info->lock); |
1068 | if (index >= info->next_index) { |
1069 | BUG_ON(!(info->flags & SHMEM_TRUNCATE)); |
1070 | goto unlock; |
1071 | } |
1072 | entry = shmem_swp_entry(info, index, NULL); |
1073 | if (entry->val) { |
1074 | /* |
1075 | * The more uptodate page coming down from a stacked |
1076 | * writepage should replace our old swappage. |
1077 | */ |
1078 | free_swap_and_cache(*entry); |
1079 | shmem_swp_set(info, entry, 0); |
1080 | } |
1081 | shmem_recalc_inode(inode); |
1082 | |
1083 | if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { |
1084 | remove_from_page_cache(page); |
1085 | shmem_swp_set(info, entry, swap.val); |
1086 | shmem_swp_unmap(entry); |
1087 | if (list_empty(&info->swaplist)) |
1088 | inode = igrab(inode); |
1089 | else |
1090 | inode = NULL; |
1091 | spin_unlock(&info->lock); |
1092 | swap_shmem_alloc(swap); |
1093 | BUG_ON(page_mapped(page)); |
1094 | page_cache_release(page); /* pagecache ref */ |
1095 | swap_writepage(page, wbc); |
1096 | if (inode) { |
1097 | mutex_lock(&shmem_swaplist_mutex); |
1098 | /* move instead of add in case we're racing */ |
1099 | list_move_tail(&info->swaplist, &shmem_swaplist); |
1100 | mutex_unlock(&shmem_swaplist_mutex); |
1101 | iput(inode); |
1102 | } |
1103 | return 0; |
1104 | } |
1105 | |
1106 | shmem_swp_unmap(entry); |
1107 | unlock: |
1108 | spin_unlock(&info->lock); |
1109 | /* |
1110 | * add_to_swap_cache() doesn't return -EEXIST, so we can safely |
1111 | * clear SWAP_HAS_CACHE flag. |
1112 | */ |
1113 | swapcache_free(swap, NULL); |
1114 | redirty: |
1115 | set_page_dirty(page); |
1116 | if (wbc->for_reclaim) |
1117 | return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
1118 | unlock_page(page); |
1119 | return 0; |
1120 | } |
1121 | |
1122 | #ifdef CONFIG_NUMA |
1123 | #ifdef CONFIG_TMPFS |
1124 | static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
1125 | { |
1126 | char buffer[64]; |
1127 | |
1128 | if (!mpol || mpol->mode == MPOL_DEFAULT) |
1129 | return; /* show nothing */ |
1130 | |
1131 | mpol_to_str(buffer, sizeof(buffer), mpol, 1); |
1132 | |
1133 | seq_printf(seq, ",mpol=%s", buffer); |
1134 | } |
1135 | |
1136 | static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
1137 | { |
1138 | struct mempolicy *mpol = NULL; |
1139 | if (sbinfo->mpol) { |
1140 | spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
1141 | mpol = sbinfo->mpol; |
1142 | mpol_get(mpol); |
1143 | spin_unlock(&sbinfo->stat_lock); |
1144 | } |
1145 | return mpol; |
1146 | } |
1147 | #endif /* CONFIG_TMPFS */ |
1148 | |
1149 | static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, |
1150 | struct shmem_inode_info *info, unsigned long idx) |
1151 | { |
1152 | struct mempolicy mpol, *spol; |
1153 | struct vm_area_struct pvma; |
1154 | struct page *page; |
1155 | |
1156 | spol = mpol_cond_copy(&mpol, |
1157 | mpol_shared_policy_lookup(&info->policy, idx)); |
1158 | |
1159 | /* Create a pseudo vma that just contains the policy */ |
1160 | pvma.vm_start = 0; |
1161 | pvma.vm_pgoff = idx; |
1162 | pvma.vm_ops = NULL; |
1163 | pvma.vm_policy = spol; |
1164 | page = swapin_readahead(entry, gfp, &pvma, 0); |
1165 | return page; |
1166 | } |
1167 | |
1168 | static struct page *shmem_alloc_page(gfp_t gfp, |
1169 | struct shmem_inode_info *info, unsigned long idx) |
1170 | { |
1171 | struct vm_area_struct pvma; |
1172 | |
1173 | /* Create a pseudo vma that just contains the policy */ |
1174 | pvma.vm_start = 0; |
1175 | pvma.vm_pgoff = idx; |
1176 | pvma.vm_ops = NULL; |
1177 | pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); |
1178 | |
1179 | /* |
1180 | * alloc_page_vma() will drop the shared policy reference |
1181 | */ |
1182 | return alloc_page_vma(gfp, &pvma, 0); |
1183 | } |
1184 | #else /* !CONFIG_NUMA */ |
1185 | #ifdef CONFIG_TMPFS |
1186 | static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) |
1187 | { |
1188 | } |
1189 | #endif /* CONFIG_TMPFS */ |
1190 | |
1191 | static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, |
1192 | struct shmem_inode_info *info, unsigned long idx) |
1193 | { |
1194 | return swapin_readahead(entry, gfp, NULL, 0); |
1195 | } |
1196 | |
1197 | static inline struct page *shmem_alloc_page(gfp_t gfp, |
1198 | struct shmem_inode_info *info, unsigned long idx) |
1199 | { |
1200 | return alloc_page(gfp); |
1201 | } |
1202 | #endif /* CONFIG_NUMA */ |
1203 | |
1204 | #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) |
1205 | static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
1206 | { |
1207 | return NULL; |
1208 | } |
1209 | #endif |
1210 | |
1211 | /* |
1212 | * shmem_getpage - either get the page from swap or allocate a new one |
1213 | * |
1214 | * If we allocate a new one we do not mark it dirty. That's up to the |
1215 | * vm. If we swap it in we mark it dirty since we also free the swap |
1216 | * entry since a page cannot live in both the swap and page cache |
1217 | */ |
1218 | static int shmem_getpage(struct inode *inode, unsigned long idx, |
1219 | struct page **pagep, enum sgp_type sgp, int *type) |
1220 | { |
1221 | struct address_space *mapping = inode->i_mapping; |
1222 | struct shmem_inode_info *info = SHMEM_I(inode); |
1223 | struct shmem_sb_info *sbinfo; |
1224 | struct page *filepage = *pagep; |
1225 | struct page *swappage; |
1226 | struct page *prealloc_page = NULL; |
1227 | swp_entry_t *entry; |
1228 | swp_entry_t swap; |
1229 | gfp_t gfp; |
1230 | int error; |
1231 | |
1232 | if (idx >= SHMEM_MAX_INDEX) |
1233 | return -EFBIG; |
1234 | |
1235 | if (type) |
1236 | *type = 0; |
1237 | |
1238 | /* |
1239 | * Normally, filepage is NULL on entry, and either found |
1240 | * uptodate immediately, or allocated and zeroed, or read |
1241 | * in under swappage, which is then assigned to filepage. |
1242 | * But shmem_readpage (required for splice) passes in a locked |
1243 | * filepage, which may be found not uptodate by other callers |
1244 | * too, and may need to be copied from the swappage read in. |
1245 | */ |
1246 | repeat: |
1247 | if (!filepage) |
1248 | filepage = find_lock_page(mapping, idx); |
1249 | if (filepage && PageUptodate(filepage)) |
1250 | goto done; |
1251 | gfp = mapping_gfp_mask(mapping); |
1252 | if (!filepage) { |
1253 | /* |
1254 | * Try to preload while we can wait, to not make a habit of |
1255 | * draining atomic reserves; but don't latch on to this cpu. |
1256 | */ |
1257 | error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); |
1258 | if (error) |
1259 | goto failed; |
1260 | radix_tree_preload_end(); |
1261 | if (sgp != SGP_READ && !prealloc_page) { |
1262 | /* We don't care if this fails */ |
1263 | prealloc_page = shmem_alloc_page(gfp, info, idx); |
1264 | if (prealloc_page) { |
1265 | if (mem_cgroup_cache_charge(prealloc_page, |
1266 | current->mm, GFP_KERNEL)) { |
1267 | page_cache_release(prealloc_page); |
1268 | prealloc_page = NULL; |
1269 | } |
1270 | } |
1271 | } |
1272 | } |
1273 | error = 0; |
1274 | |
1275 | spin_lock(&info->lock); |
1276 | shmem_recalc_inode(inode); |
1277 | entry = shmem_swp_alloc(info, idx, sgp); |
1278 | if (IS_ERR(entry)) { |
1279 | spin_unlock(&info->lock); |
1280 | error = PTR_ERR(entry); |
1281 | goto failed; |
1282 | } |
1283 | swap = *entry; |
1284 | |
1285 | if (swap.val) { |
1286 | /* Look it up and read it in.. */ |
1287 | swappage = lookup_swap_cache(swap); |
1288 | if (!swappage) { |
1289 | shmem_swp_unmap(entry); |
1290 | /* here we actually do the io */ |
1291 | if (type && !(*type & VM_FAULT_MAJOR)) { |
1292 | __count_vm_event(PGMAJFAULT); |
1293 | *type |= VM_FAULT_MAJOR; |
1294 | } |
1295 | spin_unlock(&info->lock); |
1296 | swappage = shmem_swapin(swap, gfp, info, idx); |
1297 | if (!swappage) { |
1298 | spin_lock(&info->lock); |
1299 | entry = shmem_swp_alloc(info, idx, sgp); |
1300 | if (IS_ERR(entry)) |
1301 | error = PTR_ERR(entry); |
1302 | else { |
1303 | if (entry->val == swap.val) |
1304 | error = -ENOMEM; |
1305 | shmem_swp_unmap(entry); |
1306 | } |
1307 | spin_unlock(&info->lock); |
1308 | if (error) |
1309 | goto failed; |
1310 | goto repeat; |
1311 | } |
1312 | wait_on_page_locked(swappage); |
1313 | page_cache_release(swappage); |
1314 | goto repeat; |
1315 | } |
1316 | |
1317 | /* We have to do this with page locked to prevent races */ |
1318 | if (!trylock_page(swappage)) { |
1319 | shmem_swp_unmap(entry); |
1320 | spin_unlock(&info->lock); |
1321 | wait_on_page_locked(swappage); |
1322 | page_cache_release(swappage); |
1323 | goto repeat; |
1324 | } |
1325 | if (PageWriteback(swappage)) { |
1326 | shmem_swp_unmap(entry); |
1327 | spin_unlock(&info->lock); |
1328 | wait_on_page_writeback(swappage); |
1329 | unlock_page(swappage); |
1330 | page_cache_release(swappage); |
1331 | goto repeat; |
1332 | } |
1333 | if (!PageUptodate(swappage)) { |
1334 | shmem_swp_unmap(entry); |
1335 | spin_unlock(&info->lock); |
1336 | unlock_page(swappage); |
1337 | page_cache_release(swappage); |
1338 | error = -EIO; |
1339 | goto failed; |
1340 | } |
1341 | |
1342 | if (filepage) { |
1343 | shmem_swp_set(info, entry, 0); |
1344 | shmem_swp_unmap(entry); |
1345 | delete_from_swap_cache(swappage); |
1346 | spin_unlock(&info->lock); |
1347 | copy_highpage(filepage, swappage); |
1348 | unlock_page(swappage); |
1349 | page_cache_release(swappage); |
1350 | flush_dcache_page(filepage); |
1351 | SetPageUptodate(filepage); |
1352 | set_page_dirty(filepage); |
1353 | swap_free(swap); |
1354 | } else if (!(error = add_to_page_cache_locked(swappage, mapping, |
1355 | idx, GFP_NOWAIT))) { |
1356 | info->flags |= SHMEM_PAGEIN; |
1357 | shmem_swp_set(info, entry, 0); |
1358 | shmem_swp_unmap(entry); |
1359 | delete_from_swap_cache(swappage); |
1360 | spin_unlock(&info->lock); |
1361 | filepage = swappage; |
1362 | set_page_dirty(filepage); |
1363 | swap_free(swap); |
1364 | } else { |
1365 | shmem_swp_unmap(entry); |
1366 | spin_unlock(&info->lock); |
1367 | if (error == -ENOMEM) { |
1368 | /* |
1369 | * reclaim from proper memory cgroup and |
1370 | * call memcg's OOM if needed. |
1371 | */ |
1372 | error = mem_cgroup_shmem_charge_fallback( |
1373 | swappage, |
1374 | current->mm, |
1375 | gfp); |
1376 | if (error) { |
1377 | unlock_page(swappage); |
1378 | page_cache_release(swappage); |
1379 | goto failed; |
1380 | } |
1381 | } |
1382 | unlock_page(swappage); |
1383 | page_cache_release(swappage); |
1384 | goto repeat; |
1385 | } |
1386 | } else if (sgp == SGP_READ && !filepage) { |
1387 | shmem_swp_unmap(entry); |
1388 | filepage = find_get_page(mapping, idx); |
1389 | if (filepage && |
1390 | (!PageUptodate(filepage) || !trylock_page(filepage))) { |
1391 | spin_unlock(&info->lock); |
1392 | wait_on_page_locked(filepage); |
1393 | page_cache_release(filepage); |
1394 | filepage = NULL; |
1395 | goto repeat; |
1396 | } |
1397 | spin_unlock(&info->lock); |
1398 | } else { |
1399 | shmem_swp_unmap(entry); |
1400 | sbinfo = SHMEM_SB(inode->i_sb); |
1401 | if (sbinfo->max_blocks) { |
1402 | if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) || |
1403 | shmem_acct_block(info->flags)) { |
1404 | spin_unlock(&info->lock); |
1405 | error = -ENOSPC; |
1406 | goto failed; |
1407 | } |
1408 | percpu_counter_inc(&sbinfo->used_blocks); |
1409 | spin_lock(&inode->i_lock); |
1410 | inode->i_blocks += BLOCKS_PER_PAGE; |
1411 | spin_unlock(&inode->i_lock); |
1412 | } else if (shmem_acct_block(info->flags)) { |
1413 | spin_unlock(&info->lock); |
1414 | error = -ENOSPC; |
1415 | goto failed; |
1416 | } |
1417 | |
1418 | if (!filepage) { |
1419 | int ret; |
1420 | |
1421 | if (!prealloc_page) { |
1422 | spin_unlock(&info->lock); |
1423 | filepage = shmem_alloc_page(gfp, info, idx); |
1424 | if (!filepage) { |
1425 | shmem_unacct_blocks(info->flags, 1); |
1426 | shmem_free_blocks(inode, 1); |
1427 | error = -ENOMEM; |
1428 | goto failed; |
1429 | } |
1430 | SetPageSwapBacked(filepage); |
1431 | |
1432 | /* |
1433 | * Precharge page while we can wait, compensate |
1434 | * after |
1435 | */ |
1436 | error = mem_cgroup_cache_charge(filepage, |
1437 | current->mm, GFP_KERNEL); |
1438 | if (error) { |
1439 | page_cache_release(filepage); |
1440 | shmem_unacct_blocks(info->flags, 1); |
1441 | shmem_free_blocks(inode, 1); |
1442 | filepage = NULL; |
1443 | goto failed; |
1444 | } |
1445 | |
1446 | spin_lock(&info->lock); |
1447 | } else { |
1448 | filepage = prealloc_page; |
1449 | prealloc_page = NULL; |
1450 | SetPageSwapBacked(filepage); |
1451 | } |
1452 | |
1453 | entry = shmem_swp_alloc(info, idx, sgp); |
1454 | if (IS_ERR(entry)) |
1455 | error = PTR_ERR(entry); |
1456 | else { |
1457 | swap = *entry; |
1458 | shmem_swp_unmap(entry); |
1459 | } |
1460 | ret = error || swap.val; |
1461 | if (ret) |
1462 | mem_cgroup_uncharge_cache_page(filepage); |
1463 | else |
1464 | ret = add_to_page_cache_lru(filepage, mapping, |
1465 | idx, GFP_NOWAIT); |
1466 | /* |
1467 | * At add_to_page_cache_lru() failure, uncharge will |
1468 | * be done automatically. |
1469 | */ |
1470 | if (ret) { |
1471 | spin_unlock(&info->lock); |
1472 | page_cache_release(filepage); |
1473 | shmem_unacct_blocks(info->flags, 1); |
1474 | shmem_free_blocks(inode, 1); |
1475 | filepage = NULL; |
1476 | if (error) |
1477 | goto failed; |
1478 | goto repeat; |
1479 | } |
1480 | info->flags |= SHMEM_PAGEIN; |
1481 | } |
1482 | |
1483 | info->alloced++; |
1484 | spin_unlock(&info->lock); |
1485 | clear_highpage(filepage); |
1486 | flush_dcache_page(filepage); |
1487 | SetPageUptodate(filepage); |
1488 | if (sgp == SGP_DIRTY) |
1489 | set_page_dirty(filepage); |
1490 | } |
1491 | done: |
1492 | *pagep = filepage; |
1493 | error = 0; |
1494 | goto out; |
1495 | |
1496 | failed: |
1497 | if (*pagep != filepage) { |
1498 | unlock_page(filepage); |
1499 | page_cache_release(filepage); |
1500 | } |
1501 | out: |
1502 | if (prealloc_page) { |
1503 | mem_cgroup_uncharge_cache_page(prealloc_page); |
1504 | page_cache_release(prealloc_page); |
1505 | } |
1506 | return error; |
1507 | } |
1508 | |
1509 | static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1510 | { |
1511 | struct inode *inode = vma->vm_file->f_path.dentry->d_inode; |
1512 | int error; |
1513 | int ret; |
1514 | |
1515 | if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
1516 | return VM_FAULT_SIGBUS; |
1517 | |
1518 | error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); |
1519 | if (error) |
1520 | return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); |
1521 | |
1522 | return ret | VM_FAULT_LOCKED; |
1523 | } |
1524 | |
1525 | #ifdef CONFIG_NUMA |
1526 | static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) |
1527 | { |
1528 | struct inode *i = vma->vm_file->f_path.dentry->d_inode; |
1529 | return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); |
1530 | } |
1531 | |
1532 | static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
1533 | unsigned long addr) |
1534 | { |
1535 | struct inode *i = vma->vm_file->f_path.dentry->d_inode; |
1536 | unsigned long idx; |
1537 | |
1538 | idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
1539 | return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); |
1540 | } |
1541 | #endif |
1542 | |
1543 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
1544 | { |
1545 | struct inode *inode = file->f_path.dentry->d_inode; |
1546 | struct shmem_inode_info *info = SHMEM_I(inode); |
1547 | int retval = -ENOMEM; |
1548 | |
1549 | spin_lock(&info->lock); |
1550 | if (lock && !(info->flags & VM_LOCKED)) { |
1551 | if (!user_shm_lock(inode->i_size, user)) |
1552 | goto out_nomem; |
1553 | info->flags |= VM_LOCKED; |
1554 | mapping_set_unevictable(file->f_mapping); |
1555 | } |
1556 | if (!lock && (info->flags & VM_LOCKED) && user) { |
1557 | user_shm_unlock(inode->i_size, user); |
1558 | info->flags &= ~VM_LOCKED; |
1559 | mapping_clear_unevictable(file->f_mapping); |
1560 | scan_mapping_unevictable_pages(file->f_mapping); |
1561 | } |
1562 | retval = 0; |
1563 | |
1564 | out_nomem: |
1565 | spin_unlock(&info->lock); |
1566 | return retval; |
1567 | } |
1568 | |
1569 | static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
1570 | { |
1571 | file_accessed(file); |
1572 | vma->vm_ops = &shmem_vm_ops; |
1573 | vma->vm_flags |= VM_CAN_NONLINEAR; |
1574 | return 0; |
1575 | } |
1576 | |
1577 | static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
1578 | int mode, dev_t dev, unsigned long flags) |
1579 | { |
1580 | struct inode *inode; |
1581 | struct shmem_inode_info *info; |
1582 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
1583 | |
1584 | if (shmem_reserve_inode(sb)) |
1585 | return NULL; |
1586 | |
1587 | inode = new_inode(sb); |
1588 | if (inode) { |
1589 | inode_init_owner(inode, dir, mode); |
1590 | inode->i_blocks = 0; |
1591 | inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; |
1592 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1593 | inode->i_generation = get_seconds(); |
1594 | info = SHMEM_I(inode); |
1595 | memset(info, 0, (char *)inode - (char *)info); |
1596 | spin_lock_init(&info->lock); |
1597 | info->flags = flags & VM_NORESERVE; |
1598 | INIT_LIST_HEAD(&info->swaplist); |
1599 | cache_no_acl(inode); |
1600 | |
1601 | switch (mode & S_IFMT) { |
1602 | default: |
1603 | inode->i_op = &shmem_special_inode_operations; |
1604 | init_special_inode(inode, mode, dev); |
1605 | break; |
1606 | case S_IFREG: |
1607 | inode->i_mapping->a_ops = &shmem_aops; |
1608 | inode->i_op = &shmem_inode_operations; |
1609 | inode->i_fop = &shmem_file_operations; |
1610 | mpol_shared_policy_init(&info->policy, |
1611 | shmem_get_sbmpol(sbinfo)); |
1612 | break; |
1613 | case S_IFDIR: |
1614 | inc_nlink(inode); |
1615 | /* Some things misbehave if size == 0 on a directory */ |
1616 | inode->i_size = 2 * BOGO_DIRENT_SIZE; |
1617 | inode->i_op = &shmem_dir_inode_operations; |
1618 | inode->i_fop = &simple_dir_operations; |
1619 | break; |
1620 | case S_IFLNK: |
1621 | /* |
1622 | * Must not load anything in the rbtree, |
1623 | * mpol_free_shared_policy will not be called. |
1624 | */ |
1625 | mpol_shared_policy_init(&info->policy, NULL); |
1626 | break; |
1627 | } |
1628 | } else |
1629 | shmem_free_inode(sb); |
1630 | return inode; |
1631 | } |
1632 | |
1633 | #ifdef CONFIG_TMPFS |
1634 | static const struct inode_operations shmem_symlink_inode_operations; |
1635 | static const struct inode_operations shmem_symlink_inline_operations; |
1636 | |
1637 | /* |
1638 | * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; |
1639 | * but providing them allows a tmpfs file to be used for splice, sendfile, and |
1640 | * below the loop driver, in the generic fashion that many filesystems support. |
1641 | */ |
1642 | static int shmem_readpage(struct file *file, struct page *page) |
1643 | { |
1644 | struct inode *inode = page->mapping->host; |
1645 | int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); |
1646 | unlock_page(page); |
1647 | return error; |
1648 | } |
1649 | |
1650 | static int |
1651 | shmem_write_begin(struct file *file, struct address_space *mapping, |
1652 | loff_t pos, unsigned len, unsigned flags, |
1653 | struct page **pagep, void **fsdata) |
1654 | { |
1655 | struct inode *inode = mapping->host; |
1656 | pgoff_t index = pos >> PAGE_CACHE_SHIFT; |
1657 | *pagep = NULL; |
1658 | return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); |
1659 | } |
1660 | |
1661 | static int |
1662 | shmem_write_end(struct file *file, struct address_space *mapping, |
1663 | loff_t pos, unsigned len, unsigned copied, |
1664 | struct page *page, void *fsdata) |
1665 | { |
1666 | struct inode *inode = mapping->host; |
1667 | |
1668 | if (pos + copied > inode->i_size) |
1669 | i_size_write(inode, pos + copied); |
1670 | |
1671 | set_page_dirty(page); |
1672 | unlock_page(page); |
1673 | page_cache_release(page); |
1674 | |
1675 | return copied; |
1676 | } |
1677 | |
1678 | static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) |
1679 | { |
1680 | struct inode *inode = filp->f_path.dentry->d_inode; |
1681 | struct address_space *mapping = inode->i_mapping; |
1682 | unsigned long index, offset; |
1683 | enum sgp_type sgp = SGP_READ; |
1684 | |
1685 | /* |
1686 | * Might this read be for a stacking filesystem? Then when reading |
1687 | * holes of a sparse file, we actually need to allocate those pages, |
1688 | * and even mark them dirty, so it cannot exceed the max_blocks limit. |
1689 | */ |
1690 | if (segment_eq(get_fs(), KERNEL_DS)) |
1691 | sgp = SGP_DIRTY; |
1692 | |
1693 | index = *ppos >> PAGE_CACHE_SHIFT; |
1694 | offset = *ppos & ~PAGE_CACHE_MASK; |
1695 | |
1696 | for (;;) { |
1697 | struct page *page = NULL; |
1698 | unsigned long end_index, nr, ret; |
1699 | loff_t i_size = i_size_read(inode); |
1700 | |
1701 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1702 | if (index > end_index) |
1703 | break; |
1704 | if (index == end_index) { |
1705 | nr = i_size & ~PAGE_CACHE_MASK; |
1706 | if (nr <= offset) |
1707 | break; |
1708 | } |
1709 | |
1710 | desc->error = shmem_getpage(inode, index, &page, sgp, NULL); |
1711 | if (desc->error) { |
1712 | if (desc->error == -EINVAL) |
1713 | desc->error = 0; |
1714 | break; |
1715 | } |
1716 | if (page) |
1717 | unlock_page(page); |
1718 | |
1719 | /* |
1720 | * We must evaluate after, since reads (unlike writes) |
1721 | * are called without i_mutex protection against truncate |
1722 | */ |
1723 | nr = PAGE_CACHE_SIZE; |
1724 | i_size = i_size_read(inode); |
1725 | end_index = i_size >> PAGE_CACHE_SHIFT; |
1726 | if (index == end_index) { |
1727 | nr = i_size & ~PAGE_CACHE_MASK; |
1728 | if (nr <= offset) { |
1729 | if (page) |
1730 | page_cache_release(page); |
1731 | break; |
1732 | } |
1733 | } |
1734 | nr -= offset; |
1735 | |
1736 | if (page) { |
1737 | /* |
1738 | * If users can be writing to this page using arbitrary |
1739 | * virtual addresses, take care about potential aliasing |
1740 | * before reading the page on the kernel side. |
1741 | */ |
1742 | if (mapping_writably_mapped(mapping)) |
1743 | flush_dcache_page(page); |
1744 | /* |
1745 | * Mark the page accessed if we read the beginning. |
1746 | */ |
1747 | if (!offset) |
1748 | mark_page_accessed(page); |
1749 | } else { |
1750 | page = ZERO_PAGE(0); |
1751 | page_cache_get(page); |
1752 | } |
1753 | |
1754 | /* |
1755 | * Ok, we have the page, and it's up-to-date, so |
1756 | * now we can copy it to user space... |
1757 | * |
1758 | * The actor routine returns how many bytes were actually used.. |
1759 | * NOTE! This may not be the same as how much of a user buffer |
1760 | * we filled up (we may be padding etc), so we can only update |
1761 | * "pos" here (the actor routine has to update the user buffer |
1762 | * pointers and the remaining count). |
1763 | */ |
1764 | ret = actor(desc, page, offset, nr); |
1765 | offset += ret; |
1766 | index += offset >> PAGE_CACHE_SHIFT; |
1767 | offset &= ~PAGE_CACHE_MASK; |
1768 | |
1769 | page_cache_release(page); |
1770 | if (ret != nr || !desc->count) |
1771 | break; |
1772 | |
1773 | cond_resched(); |
1774 | } |
1775 | |
1776 | *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; |
1777 | file_accessed(filp); |
1778 | } |
1779 | |
1780 | static ssize_t shmem_file_aio_read(struct kiocb *iocb, |
1781 | const struct iovec *iov, unsigned long nr_segs, loff_t pos) |
1782 | { |
1783 | struct file *filp = iocb->ki_filp; |
1784 | ssize_t retval; |
1785 | unsigned long seg; |
1786 | size_t count; |
1787 | loff_t *ppos = &iocb->ki_pos; |
1788 | |
1789 | retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); |
1790 | if (retval) |
1791 | return retval; |
1792 | |
1793 | for (seg = 0; seg < nr_segs; seg++) { |
1794 | read_descriptor_t desc; |
1795 | |
1796 | desc.written = 0; |
1797 | desc.arg.buf = iov[seg].iov_base; |
1798 | desc.count = iov[seg].iov_len; |
1799 | if (desc.count == 0) |
1800 | continue; |
1801 | desc.error = 0; |
1802 | do_shmem_file_read(filp, ppos, &desc, file_read_actor); |
1803 | retval += desc.written; |
1804 | if (desc.error) { |
1805 | retval = retval ?: desc.error; |
1806 | break; |
1807 | } |
1808 | if (desc.count > 0) |
1809 | break; |
1810 | } |
1811 | return retval; |
1812 | } |
1813 | |
1814 | static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
1815 | { |
1816 | struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
1817 | |
1818 | buf->f_type = TMPFS_MAGIC; |
1819 | buf->f_bsize = PAGE_CACHE_SIZE; |
1820 | buf->f_namelen = NAME_MAX; |
1821 | if (sbinfo->max_blocks) { |
1822 | buf->f_blocks = sbinfo->max_blocks; |
1823 | buf->f_bavail = buf->f_bfree = |
1824 | sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks); |
1825 | } |
1826 | if (sbinfo->max_inodes) { |
1827 | buf->f_files = sbinfo->max_inodes; |
1828 | buf->f_ffree = sbinfo->free_inodes; |
1829 | } |
1830 | /* else leave those fields 0 like simple_statfs */ |
1831 | return 0; |
1832 | } |
1833 | |
1834 | /* |
1835 | * File creation. Allocate an inode, and we're done.. |
1836 | */ |
1837 | static int |
1838 | shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) |
1839 | { |
1840 | struct inode *inode; |
1841 | int error = -ENOSPC; |
1842 | |
1843 | inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
1844 | if (inode) { |
1845 | error = security_inode_init_security(inode, dir, NULL, NULL, |
1846 | NULL); |
1847 | if (error) { |
1848 | if (error != -EOPNOTSUPP) { |
1849 | iput(inode); |
1850 | return error; |
1851 | } |
1852 | } |
1853 | #ifdef CONFIG_TMPFS_POSIX_ACL |
1854 | error = generic_acl_init(inode, dir); |
1855 | if (error) { |
1856 | iput(inode); |
1857 | return error; |
1858 | } |
1859 | #else |
1860 | error = 0; |
1861 | #endif |
1862 | dir->i_size += BOGO_DIRENT_SIZE; |
1863 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1864 | d_instantiate(dentry, inode); |
1865 | dget(dentry); /* Extra count - pin the dentry in core */ |
1866 | } |
1867 | return error; |
1868 | } |
1869 | |
1870 | static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) |
1871 | { |
1872 | int error; |
1873 | |
1874 | if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) |
1875 | return error; |
1876 | inc_nlink(dir); |
1877 | return 0; |
1878 | } |
1879 | |
1880 | static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, |
1881 | struct nameidata *nd) |
1882 | { |
1883 | return shmem_mknod(dir, dentry, mode | S_IFREG, 0); |
1884 | } |
1885 | |
1886 | /* |
1887 | * Link a file.. |
1888 | */ |
1889 | static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
1890 | { |
1891 | struct inode *inode = old_dentry->d_inode; |
1892 | int ret; |
1893 | |
1894 | /* |
1895 | * No ordinary (disk based) filesystem counts links as inodes; |
1896 | * but each new link needs a new dentry, pinning lowmem, and |
1897 | * tmpfs dentries cannot be pruned until they are unlinked. |
1898 | */ |
1899 | ret = shmem_reserve_inode(inode->i_sb); |
1900 | if (ret) |
1901 | goto out; |
1902 | |
1903 | dir->i_size += BOGO_DIRENT_SIZE; |
1904 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1905 | inc_nlink(inode); |
1906 | atomic_inc(&inode->i_count); /* New dentry reference */ |
1907 | dget(dentry); /* Extra pinning count for the created dentry */ |
1908 | d_instantiate(dentry, inode); |
1909 | out: |
1910 | return ret; |
1911 | } |
1912 | |
1913 | static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
1914 | { |
1915 | struct inode *inode = dentry->d_inode; |
1916 | |
1917 | if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
1918 | shmem_free_inode(inode->i_sb); |
1919 | |
1920 | dir->i_size -= BOGO_DIRENT_SIZE; |
1921 | inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
1922 | drop_nlink(inode); |
1923 | dput(dentry); /* Undo the count from "create" - this does all the work */ |
1924 | return 0; |
1925 | } |
1926 | |
1927 | static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
1928 | { |
1929 | if (!simple_empty(dentry)) |
1930 | return -ENOTEMPTY; |
1931 | |
1932 | drop_nlink(dentry->d_inode); |
1933 | drop_nlink(dir); |
1934 | return shmem_unlink(dir, dentry); |
1935 | } |
1936 | |
1937 | /* |
1938 | * The VFS layer already does all the dentry stuff for rename, |
1939 | * we just have to decrement the usage count for the target if |
1940 | * it exists so that the VFS layer correctly free's it when it |
1941 | * gets overwritten. |
1942 | */ |
1943 | static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
1944 | { |
1945 | struct inode *inode = old_dentry->d_inode; |
1946 | int they_are_dirs = S_ISDIR(inode->i_mode); |
1947 | |
1948 | if (!simple_empty(new_dentry)) |
1949 | return -ENOTEMPTY; |
1950 | |
1951 | if (new_dentry->d_inode) { |
1952 | (void) shmem_unlink(new_dir, new_dentry); |
1953 | if (they_are_dirs) |
1954 | drop_nlink(old_dir); |
1955 | } else if (they_are_dirs) { |
1956 | drop_nlink(old_dir); |
1957 | inc_nlink(new_dir); |
1958 | } |
1959 | |
1960 | old_dir->i_size -= BOGO_DIRENT_SIZE; |
1961 | new_dir->i_size += BOGO_DIRENT_SIZE; |
1962 | old_dir->i_ctime = old_dir->i_mtime = |
1963 | new_dir->i_ctime = new_dir->i_mtime = |
1964 | inode->i_ctime = CURRENT_TIME; |
1965 | return 0; |
1966 | } |
1967 | |
1968 | static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) |
1969 | { |
1970 | int error; |
1971 | int len; |
1972 | struct inode *inode; |
1973 | struct page *page = NULL; |
1974 | char *kaddr; |
1975 | struct shmem_inode_info *info; |
1976 | |
1977 | len = strlen(symname) + 1; |
1978 | if (len > PAGE_CACHE_SIZE) |
1979 | return -ENAMETOOLONG; |
1980 | |
1981 | inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); |
1982 | if (!inode) |
1983 | return -ENOSPC; |
1984 | |
1985 | error = security_inode_init_security(inode, dir, NULL, NULL, |
1986 | NULL); |
1987 | if (error) { |
1988 | if (error != -EOPNOTSUPP) { |
1989 | iput(inode); |
1990 | return error; |
1991 | } |
1992 | error = 0; |
1993 | } |
1994 | |
1995 | info = SHMEM_I(inode); |
1996 | inode->i_size = len-1; |
1997 | if (len <= (char *)inode - (char *)info) { |
1998 | /* do it inline */ |
1999 | memcpy(info, symname, len); |
2000 | inode->i_op = &shmem_symlink_inline_operations; |
2001 | } else { |
2002 | error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); |
2003 | if (error) { |
2004 | iput(inode); |
2005 | return error; |
2006 | } |
2007 | inode->i_mapping->a_ops = &shmem_aops; |
2008 | inode->i_op = &shmem_symlink_inode_operations; |
2009 | kaddr = kmap_atomic(page, KM_USER0); |
2010 | memcpy(kaddr, symname, len); |
2011 | kunmap_atomic(kaddr, KM_USER0); |
2012 | set_page_dirty(page); |
2013 | unlock_page(page); |
2014 | page_cache_release(page); |
2015 | } |
2016 | dir->i_size += BOGO_DIRENT_SIZE; |
2017 | dir->i_ctime = dir->i_mtime = CURRENT_TIME; |
2018 | d_instantiate(dentry, inode); |
2019 | dget(dentry); |
2020 | return 0; |
2021 | } |
2022 | |
2023 | static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) |
2024 | { |
2025 | nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); |
2026 | return NULL; |
2027 | } |
2028 | |
2029 | static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) |
2030 | { |
2031 | struct page *page = NULL; |
2032 | int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); |
2033 | nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); |
2034 | if (page) |
2035 | unlock_page(page); |
2036 | return page; |
2037 | } |
2038 | |
2039 | static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) |
2040 | { |
2041 | if (!IS_ERR(nd_get_link(nd))) { |
2042 | struct page *page = cookie; |
2043 | kunmap(page); |
2044 | mark_page_accessed(page); |
2045 | page_cache_release(page); |
2046 | } |
2047 | } |
2048 | |
2049 | static const struct inode_operations shmem_symlink_inline_operations = { |
2050 | .readlink = generic_readlink, |
2051 | .follow_link = shmem_follow_link_inline, |
2052 | }; |
2053 | |
2054 | static const struct inode_operations shmem_symlink_inode_operations = { |
2055 | .readlink = generic_readlink, |
2056 | .follow_link = shmem_follow_link, |
2057 | .put_link = shmem_put_link, |
2058 | }; |
2059 | |
2060 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2061 | /* |
2062 | * Superblocks without xattr inode operations will get security.* xattr |
2063 | * support from the VFS "for free". As soon as we have any other xattrs |
2064 | * like ACLs, we also need to implement the security.* handlers at |
2065 | * filesystem level, though. |
2066 | */ |
2067 | |
2068 | static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, |
2069 | size_t list_len, const char *name, |
2070 | size_t name_len, int handler_flags) |
2071 | { |
2072 | return security_inode_listsecurity(dentry->d_inode, list, list_len); |
2073 | } |
2074 | |
2075 | static int shmem_xattr_security_get(struct dentry *dentry, const char *name, |
2076 | void *buffer, size_t size, int handler_flags) |
2077 | { |
2078 | if (strcmp(name, "") == 0) |
2079 | return -EINVAL; |
2080 | return xattr_getsecurity(dentry->d_inode, name, buffer, size); |
2081 | } |
2082 | |
2083 | static int shmem_xattr_security_set(struct dentry *dentry, const char *name, |
2084 | const void *value, size_t size, int flags, int handler_flags) |
2085 | { |
2086 | if (strcmp(name, "") == 0) |
2087 | return -EINVAL; |
2088 | return security_inode_setsecurity(dentry->d_inode, name, value, |
2089 | size, flags); |
2090 | } |
2091 | |
2092 | static const struct xattr_handler shmem_xattr_security_handler = { |
2093 | .prefix = XATTR_SECURITY_PREFIX, |
2094 | .list = shmem_xattr_security_list, |
2095 | .get = shmem_xattr_security_get, |
2096 | .set = shmem_xattr_security_set, |
2097 | }; |
2098 | |
2099 | static const struct xattr_handler *shmem_xattr_handlers[] = { |
2100 | &generic_acl_access_handler, |
2101 | &generic_acl_default_handler, |
2102 | &shmem_xattr_security_handler, |
2103 | NULL |
2104 | }; |
2105 | #endif |
2106 | |
2107 | static struct dentry *shmem_get_parent(struct dentry *child) |
2108 | { |
2109 | return ERR_PTR(-ESTALE); |
2110 | } |
2111 | |
2112 | static int shmem_match(struct inode *ino, void *vfh) |
2113 | { |
2114 | __u32 *fh = vfh; |
2115 | __u64 inum = fh[2]; |
2116 | inum = (inum << 32) | fh[1]; |
2117 | return ino->i_ino == inum && fh[0] == ino->i_generation; |
2118 | } |
2119 | |
2120 | static struct dentry *shmem_fh_to_dentry(struct super_block *sb, |
2121 | struct fid *fid, int fh_len, int fh_type) |
2122 | { |
2123 | struct inode *inode; |
2124 | struct dentry *dentry = NULL; |
2125 | u64 inum = fid->raw[2]; |
2126 | inum = (inum << 32) | fid->raw[1]; |
2127 | |
2128 | if (fh_len < 3) |
2129 | return NULL; |
2130 | |
2131 | inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), |
2132 | shmem_match, fid->raw); |
2133 | if (inode) { |
2134 | dentry = d_find_alias(inode); |
2135 | iput(inode); |
2136 | } |
2137 | |
2138 | return dentry; |
2139 | } |
2140 | |
2141 | static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, |
2142 | int connectable) |
2143 | { |
2144 | struct inode *inode = dentry->d_inode; |
2145 | |
2146 | if (*len < 3) |
2147 | return 255; |
2148 | |
2149 | if (hlist_unhashed(&inode->i_hash)) { |
2150 | /* Unfortunately insert_inode_hash is not idempotent, |
2151 | * so as we hash inodes here rather than at creation |
2152 | * time, we need a lock to ensure we only try |
2153 | * to do it once |
2154 | */ |
2155 | static DEFINE_SPINLOCK(lock); |
2156 | spin_lock(&lock); |
2157 | if (hlist_unhashed(&inode->i_hash)) |
2158 | __insert_inode_hash(inode, |
2159 | inode->i_ino + inode->i_generation); |
2160 | spin_unlock(&lock); |
2161 | } |
2162 | |
2163 | fh[0] = inode->i_generation; |
2164 | fh[1] = inode->i_ino; |
2165 | fh[2] = ((__u64)inode->i_ino) >> 32; |
2166 | |
2167 | *len = 3; |
2168 | return 1; |
2169 | } |
2170 | |
2171 | static const struct export_operations shmem_export_ops = { |
2172 | .get_parent = shmem_get_parent, |
2173 | .encode_fh = shmem_encode_fh, |
2174 | .fh_to_dentry = shmem_fh_to_dentry, |
2175 | }; |
2176 | |
2177 | static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, |
2178 | bool remount) |
2179 | { |
2180 | char *this_char, *value, *rest; |
2181 | |
2182 | while (options != NULL) { |
2183 | this_char = options; |
2184 | for (;;) { |
2185 | /* |
2186 | * NUL-terminate this option: unfortunately, |
2187 | * mount options form a comma-separated list, |
2188 | * but mpol's nodelist may also contain commas. |
2189 | */ |
2190 | options = strchr(options, ','); |
2191 | if (options == NULL) |
2192 | break; |
2193 | options++; |
2194 | if (!isdigit(*options)) { |
2195 | options[-1] = '\0'; |
2196 | break; |
2197 | } |
2198 | } |
2199 | if (!*this_char) |
2200 | continue; |
2201 | if ((value = strchr(this_char,'=')) != NULL) { |
2202 | *value++ = 0; |
2203 | } else { |
2204 | printk(KERN_ERR |
2205 | "tmpfs: No value for mount option '%s'\n", |
2206 | this_char); |
2207 | return 1; |
2208 | } |
2209 | |
2210 | if (!strcmp(this_char,"size")) { |
2211 | unsigned long long size; |
2212 | size = memparse(value,&rest); |
2213 | if (*rest == '%') { |
2214 | size <<= PAGE_SHIFT; |
2215 | size *= totalram_pages; |
2216 | do_div(size, 100); |
2217 | rest++; |
2218 | } |
2219 | if (*rest) |
2220 | goto bad_val; |
2221 | sbinfo->max_blocks = |
2222 | DIV_ROUND_UP(size, PAGE_CACHE_SIZE); |
2223 | } else if (!strcmp(this_char,"nr_blocks")) { |
2224 | sbinfo->max_blocks = memparse(value, &rest); |
2225 | if (*rest) |
2226 | goto bad_val; |
2227 | } else if (!strcmp(this_char,"nr_inodes")) { |
2228 | sbinfo->max_inodes = memparse(value, &rest); |
2229 | if (*rest) |
2230 | goto bad_val; |
2231 | } else if (!strcmp(this_char,"mode")) { |
2232 | if (remount) |
2233 | continue; |
2234 | sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; |
2235 | if (*rest) |
2236 | goto bad_val; |
2237 | } else if (!strcmp(this_char,"uid")) { |
2238 | if (remount) |
2239 | continue; |
2240 | sbinfo->uid = simple_strtoul(value, &rest, 0); |
2241 | if (*rest) |
2242 | goto bad_val; |
2243 | } else if (!strcmp(this_char,"gid")) { |
2244 | if (remount) |
2245 | continue; |
2246 | sbinfo->gid = simple_strtoul(value, &rest, 0); |
2247 | if (*rest) |
2248 | goto bad_val; |
2249 | } else if (!strcmp(this_char,"mpol")) { |
2250 | if (mpol_parse_str(value, &sbinfo->mpol, 1)) |
2251 | goto bad_val; |
2252 | } else { |
2253 | printk(KERN_ERR "tmpfs: Bad mount option %s\n", |
2254 | this_char); |
2255 | return 1; |
2256 | } |
2257 | } |
2258 | return 0; |
2259 | |
2260 | bad_val: |
2261 | printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", |
2262 | value, this_char); |
2263 | return 1; |
2264 | |
2265 | } |
2266 | |
2267 | static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) |
2268 | { |
2269 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2270 | struct shmem_sb_info config = *sbinfo; |
2271 | unsigned long inodes; |
2272 | int error = -EINVAL; |
2273 | |
2274 | if (shmem_parse_options(data, &config, true)) |
2275 | return error; |
2276 | |
2277 | spin_lock(&sbinfo->stat_lock); |
2278 | inodes = sbinfo->max_inodes - sbinfo->free_inodes; |
2279 | if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) |
2280 | goto out; |
2281 | if (config.max_inodes < inodes) |
2282 | goto out; |
2283 | /* |
2284 | * Those tests also disallow limited->unlimited while any are in |
2285 | * use, so i_blocks will always be zero when max_blocks is zero; |
2286 | * but we must separately disallow unlimited->limited, because |
2287 | * in that case we have no record of how much is already in use. |
2288 | */ |
2289 | if (config.max_blocks && !sbinfo->max_blocks) |
2290 | goto out; |
2291 | if (config.max_inodes && !sbinfo->max_inodes) |
2292 | goto out; |
2293 | |
2294 | error = 0; |
2295 | sbinfo->max_blocks = config.max_blocks; |
2296 | sbinfo->max_inodes = config.max_inodes; |
2297 | sbinfo->free_inodes = config.max_inodes - inodes; |
2298 | |
2299 | mpol_put(sbinfo->mpol); |
2300 | sbinfo->mpol = config.mpol; /* transfers initial ref */ |
2301 | out: |
2302 | spin_unlock(&sbinfo->stat_lock); |
2303 | return error; |
2304 | } |
2305 | |
2306 | static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) |
2307 | { |
2308 | struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); |
2309 | |
2310 | if (sbinfo->max_blocks != shmem_default_max_blocks()) |
2311 | seq_printf(seq, ",size=%luk", |
2312 | sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); |
2313 | if (sbinfo->max_inodes != shmem_default_max_inodes()) |
2314 | seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); |
2315 | if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) |
2316 | seq_printf(seq, ",mode=%03o", sbinfo->mode); |
2317 | if (sbinfo->uid != 0) |
2318 | seq_printf(seq, ",uid=%u", sbinfo->uid); |
2319 | if (sbinfo->gid != 0) |
2320 | seq_printf(seq, ",gid=%u", sbinfo->gid); |
2321 | shmem_show_mpol(seq, sbinfo->mpol); |
2322 | return 0; |
2323 | } |
2324 | #endif /* CONFIG_TMPFS */ |
2325 | |
2326 | static void shmem_put_super(struct super_block *sb) |
2327 | { |
2328 | struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
2329 | |
2330 | percpu_counter_destroy(&sbinfo->used_blocks); |
2331 | kfree(sbinfo); |
2332 | sb->s_fs_info = NULL; |
2333 | } |
2334 | |
2335 | int shmem_fill_super(struct super_block *sb, void *data, int silent) |
2336 | { |
2337 | struct inode *inode; |
2338 | struct dentry *root; |
2339 | struct shmem_sb_info *sbinfo; |
2340 | int err = -ENOMEM; |
2341 | |
2342 | /* Round up to L1_CACHE_BYTES to resist false sharing */ |
2343 | sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), |
2344 | L1_CACHE_BYTES), GFP_KERNEL); |
2345 | if (!sbinfo) |
2346 | return -ENOMEM; |
2347 | |
2348 | sbinfo->mode = S_IRWXUGO | S_ISVTX; |
2349 | sbinfo->uid = current_fsuid(); |
2350 | sbinfo->gid = current_fsgid(); |
2351 | sb->s_fs_info = sbinfo; |
2352 | |
2353 | #ifdef CONFIG_TMPFS |
2354 | /* |
2355 | * Per default we only allow half of the physical ram per |
2356 | * tmpfs instance, limiting inodes to one per page of lowmem; |
2357 | * but the internal instance is left unlimited. |
2358 | */ |
2359 | if (!(sb->s_flags & MS_NOUSER)) { |
2360 | sbinfo->max_blocks = shmem_default_max_blocks(); |
2361 | sbinfo->max_inodes = shmem_default_max_inodes(); |
2362 | if (shmem_parse_options(data, sbinfo, false)) { |
2363 | err = -EINVAL; |
2364 | goto failed; |
2365 | } |
2366 | } |
2367 | sb->s_export_op = &shmem_export_ops; |
2368 | #else |
2369 | sb->s_flags |= MS_NOUSER; |
2370 | #endif |
2371 | |
2372 | spin_lock_init(&sbinfo->stat_lock); |
2373 | if (percpu_counter_init(&sbinfo->used_blocks, 0)) |
2374 | goto failed; |
2375 | sbinfo->free_inodes = sbinfo->max_inodes; |
2376 | |
2377 | sb->s_maxbytes = SHMEM_MAX_BYTES; |
2378 | sb->s_blocksize = PAGE_CACHE_SIZE; |
2379 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; |
2380 | sb->s_magic = TMPFS_MAGIC; |
2381 | sb->s_op = &shmem_ops; |
2382 | sb->s_time_gran = 1; |
2383 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2384 | sb->s_xattr = shmem_xattr_handlers; |
2385 | sb->s_flags |= MS_POSIXACL; |
2386 | #endif |
2387 | |
2388 | inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); |
2389 | if (!inode) |
2390 | goto failed; |
2391 | inode->i_uid = sbinfo->uid; |
2392 | inode->i_gid = sbinfo->gid; |
2393 | root = d_alloc_root(inode); |
2394 | if (!root) |
2395 | goto failed_iput; |
2396 | sb->s_root = root; |
2397 | return 0; |
2398 | |
2399 | failed_iput: |
2400 | iput(inode); |
2401 | failed: |
2402 | shmem_put_super(sb); |
2403 | return err; |
2404 | } |
2405 | |
2406 | static struct kmem_cache *shmem_inode_cachep; |
2407 | |
2408 | static struct inode *shmem_alloc_inode(struct super_block *sb) |
2409 | { |
2410 | struct shmem_inode_info *p; |
2411 | p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); |
2412 | if (!p) |
2413 | return NULL; |
2414 | return &p->vfs_inode; |
2415 | } |
2416 | |
2417 | static void shmem_destroy_inode(struct inode *inode) |
2418 | { |
2419 | if ((inode->i_mode & S_IFMT) == S_IFREG) { |
2420 | /* only struct inode is valid if it's an inline symlink */ |
2421 | mpol_free_shared_policy(&SHMEM_I(inode)->policy); |
2422 | } |
2423 | kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); |
2424 | } |
2425 | |
2426 | static void init_once(void *foo) |
2427 | { |
2428 | struct shmem_inode_info *p = (struct shmem_inode_info *) foo; |
2429 | |
2430 | inode_init_once(&p->vfs_inode); |
2431 | } |
2432 | |
2433 | static int init_inodecache(void) |
2434 | { |
2435 | shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", |
2436 | sizeof(struct shmem_inode_info), |
2437 | 0, SLAB_PANIC, init_once); |
2438 | return 0; |
2439 | } |
2440 | |
2441 | static void destroy_inodecache(void) |
2442 | { |
2443 | kmem_cache_destroy(shmem_inode_cachep); |
2444 | } |
2445 | |
2446 | static const struct address_space_operations shmem_aops = { |
2447 | .writepage = shmem_writepage, |
2448 | .set_page_dirty = __set_page_dirty_no_writeback, |
2449 | #ifdef CONFIG_TMPFS |
2450 | .readpage = shmem_readpage, |
2451 | .write_begin = shmem_write_begin, |
2452 | .write_end = shmem_write_end, |
2453 | #endif |
2454 | .migratepage = migrate_page, |
2455 | .error_remove_page = generic_error_remove_page, |
2456 | }; |
2457 | |
2458 | static const struct file_operations shmem_file_operations = { |
2459 | .mmap = shmem_mmap, |
2460 | #ifdef CONFIG_TMPFS |
2461 | .llseek = generic_file_llseek, |
2462 | .read = do_sync_read, |
2463 | .write = do_sync_write, |
2464 | .aio_read = shmem_file_aio_read, |
2465 | .aio_write = generic_file_aio_write, |
2466 | .fsync = noop_fsync, |
2467 | .splice_read = generic_file_splice_read, |
2468 | .splice_write = generic_file_splice_write, |
2469 | #endif |
2470 | }; |
2471 | |
2472 | static const struct inode_operations shmem_inode_operations = { |
2473 | .setattr = shmem_notify_change, |
2474 | .truncate_range = shmem_truncate_range, |
2475 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2476 | .setxattr = generic_setxattr, |
2477 | .getxattr = generic_getxattr, |
2478 | .listxattr = generic_listxattr, |
2479 | .removexattr = generic_removexattr, |
2480 | .check_acl = generic_check_acl, |
2481 | #endif |
2482 | |
2483 | }; |
2484 | |
2485 | static const struct inode_operations shmem_dir_inode_operations = { |
2486 | #ifdef CONFIG_TMPFS |
2487 | .create = shmem_create, |
2488 | .lookup = simple_lookup, |
2489 | .link = shmem_link, |
2490 | .unlink = shmem_unlink, |
2491 | .symlink = shmem_symlink, |
2492 | .mkdir = shmem_mkdir, |
2493 | .rmdir = shmem_rmdir, |
2494 | .mknod = shmem_mknod, |
2495 | .rename = shmem_rename, |
2496 | #endif |
2497 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2498 | .setattr = shmem_notify_change, |
2499 | .setxattr = generic_setxattr, |
2500 | .getxattr = generic_getxattr, |
2501 | .listxattr = generic_listxattr, |
2502 | .removexattr = generic_removexattr, |
2503 | .check_acl = generic_check_acl, |
2504 | #endif |
2505 | }; |
2506 | |
2507 | static const struct inode_operations shmem_special_inode_operations = { |
2508 | #ifdef CONFIG_TMPFS_POSIX_ACL |
2509 | .setattr = shmem_notify_change, |
2510 | .setxattr = generic_setxattr, |
2511 | .getxattr = generic_getxattr, |
2512 | .listxattr = generic_listxattr, |
2513 | .removexattr = generic_removexattr, |
2514 | .check_acl = generic_check_acl, |
2515 | #endif |
2516 | }; |
2517 | |
2518 | static const struct super_operations shmem_ops = { |
2519 | .alloc_inode = shmem_alloc_inode, |
2520 | .destroy_inode = shmem_destroy_inode, |
2521 | #ifdef CONFIG_TMPFS |
2522 | .statfs = shmem_statfs, |
2523 | .remount_fs = shmem_remount_fs, |
2524 | .show_options = shmem_show_options, |
2525 | #endif |
2526 | .evict_inode = shmem_evict_inode, |
2527 | .drop_inode = generic_delete_inode, |
2528 | .put_super = shmem_put_super, |
2529 | }; |
2530 | |
2531 | static const struct vm_operations_struct shmem_vm_ops = { |
2532 | .fault = shmem_fault, |
2533 | #ifdef CONFIG_NUMA |
2534 | .set_policy = shmem_set_policy, |
2535 | .get_policy = shmem_get_policy, |
2536 | #endif |
2537 | }; |
2538 | |
2539 | |
2540 | static int shmem_get_sb(struct file_system_type *fs_type, |
2541 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) |
2542 | { |
2543 | return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); |
2544 | } |
2545 | |
2546 | static struct file_system_type tmpfs_fs_type = { |
2547 | .owner = THIS_MODULE, |
2548 | .name = "tmpfs", |
2549 | .get_sb = shmem_get_sb, |
2550 | .kill_sb = kill_litter_super, |
2551 | }; |
2552 | |
2553 | int __init init_tmpfs(void) |
2554 | { |
2555 | int error; |
2556 | |
2557 | error = bdi_init(&shmem_backing_dev_info); |
2558 | if (error) |
2559 | goto out4; |
2560 | |
2561 | error = init_inodecache(); |
2562 | if (error) |
2563 | goto out3; |
2564 | |
2565 | error = register_filesystem(&tmpfs_fs_type); |
2566 | if (error) { |
2567 | printk(KERN_ERR "Could not register tmpfs\n"); |
2568 | goto out2; |
2569 | } |
2570 | |
2571 | shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, |
2572 | tmpfs_fs_type.name, NULL); |
2573 | if (IS_ERR(shm_mnt)) { |
2574 | error = PTR_ERR(shm_mnt); |
2575 | printk(KERN_ERR "Could not kern_mount tmpfs\n"); |
2576 | goto out1; |
2577 | } |
2578 | return 0; |
2579 | |
2580 | out1: |
2581 | unregister_filesystem(&tmpfs_fs_type); |
2582 | out2: |
2583 | destroy_inodecache(); |
2584 | out3: |
2585 | bdi_destroy(&shmem_backing_dev_info); |
2586 | out4: |
2587 | shm_mnt = ERR_PTR(error); |
2588 | return error; |
2589 | } |
2590 | |
2591 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
2592 | /** |
2593 | * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file |
2594 | * @inode: the inode to be searched |
2595 | * @pgoff: the offset to be searched |
2596 | * @pagep: the pointer for the found page to be stored |
2597 | * @ent: the pointer for the found swap entry to be stored |
2598 | * |
2599 | * If a page is found, refcount of it is incremented. Callers should handle |
2600 | * these refcount. |
2601 | */ |
2602 | void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, |
2603 | struct page **pagep, swp_entry_t *ent) |
2604 | { |
2605 | swp_entry_t entry = { .val = 0 }, *ptr; |
2606 | struct page *page = NULL; |
2607 | struct shmem_inode_info *info = SHMEM_I(inode); |
2608 | |
2609 | if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
2610 | goto out; |
2611 | |
2612 | spin_lock(&info->lock); |
2613 | ptr = shmem_swp_entry(info, pgoff, NULL); |
2614 | #ifdef CONFIG_SWAP |
2615 | if (ptr && ptr->val) { |
2616 | entry.val = ptr->val; |
2617 | page = find_get_page(&swapper_space, entry.val); |
2618 | } else |
2619 | #endif |
2620 | page = find_get_page(inode->i_mapping, pgoff); |
2621 | if (ptr) |
2622 | shmem_swp_unmap(ptr); |
2623 | spin_unlock(&info->lock); |
2624 | out: |
2625 | *pagep = page; |
2626 | *ent = entry; |
2627 | } |
2628 | #endif |
2629 | |
2630 | #else /* !CONFIG_SHMEM */ |
2631 | |
2632 | /* |
2633 | * tiny-shmem: simple shmemfs and tmpfs using ramfs code |
2634 | * |
2635 | * This is intended for small system where the benefits of the full |
2636 | * shmem code (swap-backed and resource-limited) are outweighed by |
2637 | * their complexity. On systems without swap this code should be |
2638 | * effectively equivalent, but much lighter weight. |
2639 | */ |
2640 | |
2641 | #include <linux/ramfs.h> |
2642 | |
2643 | static struct file_system_type tmpfs_fs_type = { |
2644 | .name = "tmpfs", |
2645 | .get_sb = ramfs_get_sb, |
2646 | .kill_sb = kill_litter_super, |
2647 | }; |
2648 | |
2649 | int __init init_tmpfs(void) |
2650 | { |
2651 | BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); |
2652 | |
2653 | shm_mnt = kern_mount(&tmpfs_fs_type); |
2654 | BUG_ON(IS_ERR(shm_mnt)); |
2655 | |
2656 | return 0; |
2657 | } |
2658 | |
2659 | int shmem_unuse(swp_entry_t entry, struct page *page) |
2660 | { |
2661 | return 0; |
2662 | } |
2663 | |
2664 | int shmem_lock(struct file *file, int lock, struct user_struct *user) |
2665 | { |
2666 | return 0; |
2667 | } |
2668 | |
2669 | #ifdef CONFIG_CGROUP_MEM_RES_CTLR |
2670 | /** |
2671 | * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file |
2672 | * @inode: the inode to be searched |
2673 | * @pgoff: the offset to be searched |
2674 | * @pagep: the pointer for the found page to be stored |
2675 | * @ent: the pointer for the found swap entry to be stored |
2676 | * |
2677 | * If a page is found, refcount of it is incremented. Callers should handle |
2678 | * these refcount. |
2679 | */ |
2680 | void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, |
2681 | struct page **pagep, swp_entry_t *ent) |
2682 | { |
2683 | struct page *page = NULL; |
2684 | |
2685 | if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) |
2686 | goto out; |
2687 | page = find_get_page(inode->i_mapping, pgoff); |
2688 | out: |
2689 | *pagep = page; |
2690 | *ent = (swp_entry_t){ .val = 0 }; |
2691 | } |
2692 | #endif |
2693 | |
2694 | #define shmem_vm_ops generic_file_vm_ops |
2695 | #define shmem_file_operations ramfs_file_operations |
2696 | #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) |
2697 | #define shmem_acct_size(flags, size) 0 |
2698 | #define shmem_unacct_size(flags, size) do {} while (0) |
2699 | #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE |
2700 | |
2701 | #endif /* CONFIG_SHMEM */ |
2702 | |
2703 | /* common code */ |
2704 | |
2705 | /** |
2706 | * shmem_file_setup - get an unlinked file living in tmpfs |
2707 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
2708 | * @size: size to be set for the file |
2709 | * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size |
2710 | */ |
2711 | struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) |
2712 | { |
2713 | int error; |
2714 | struct file *file; |
2715 | struct inode *inode; |
2716 | struct path path; |
2717 | struct dentry *root; |
2718 | struct qstr this; |
2719 | |
2720 | if (IS_ERR(shm_mnt)) |
2721 | return (void *)shm_mnt; |
2722 | |
2723 | if (size < 0 || size > SHMEM_MAX_BYTES) |
2724 | return ERR_PTR(-EINVAL); |
2725 | |
2726 | if (shmem_acct_size(flags, size)) |
2727 | return ERR_PTR(-ENOMEM); |
2728 | |
2729 | error = -ENOMEM; |
2730 | this.name = name; |
2731 | this.len = strlen(name); |
2732 | this.hash = 0; /* will go */ |
2733 | root = shm_mnt->mnt_root; |
2734 | path.dentry = d_alloc(root, &this); |
2735 | if (!path.dentry) |
2736 | goto put_memory; |
2737 | path.mnt = mntget(shm_mnt); |
2738 | |
2739 | error = -ENOSPC; |
2740 | inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); |
2741 | if (!inode) |
2742 | goto put_dentry; |
2743 | |
2744 | d_instantiate(path.dentry, inode); |
2745 | inode->i_size = size; |
2746 | inode->i_nlink = 0; /* It is unlinked */ |
2747 | #ifndef CONFIG_MMU |
2748 | error = ramfs_nommu_expand_for_mapping(inode, size); |
2749 | if (error) |
2750 | goto put_dentry; |
2751 | #endif |
2752 | |
2753 | error = -ENFILE; |
2754 | file = alloc_file(&path, FMODE_WRITE | FMODE_READ, |
2755 | &shmem_file_operations); |
2756 | if (!file) |
2757 | goto put_dentry; |
2758 | |
2759 | return file; |
2760 | |
2761 | put_dentry: |
2762 | path_put(&path); |
2763 | put_memory: |
2764 | shmem_unacct_size(flags, size); |
2765 | return ERR_PTR(error); |
2766 | } |
2767 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
2768 | |
2769 | /** |
2770 | * shmem_zero_setup - setup a shared anonymous mapping |
2771 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
2772 | */ |
2773 | int shmem_zero_setup(struct vm_area_struct *vma) |
2774 | { |
2775 | struct file *file; |
2776 | loff_t size = vma->vm_end - vma->vm_start; |
2777 | |
2778 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
2779 | if (IS_ERR(file)) |
2780 | return PTR_ERR(file); |
2781 | |
2782 | if (vma->vm_file) |
2783 | fput(vma->vm_file); |
2784 | vma->vm_file = file; |
2785 | vma->vm_ops = &shmem_vm_ops; |
2786 | return 0; |
2787 | } |
2788 |
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