[PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store
[linux-2.6.git] / mm / shmem.c
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  * This file is released under the GPL.
18  */
19
20 /*
21  * This virtual memory filesystem is heavily based on the ramfs. It
22  * extends ramfs by the ability to use swap and honor resource limits
23  * which makes it a completely usable filesystem.
24  */
25
26 #include <linux/config.h>
27 #include <linux/module.h>
28 #include <linux/init.h>
29 #include <linux/devfs_fs_kernel.h>
30 #include <linux/fs.h>
31 #include <linux/mm.h>
32 #include <linux/mman.h>
33 #include <linux/file.h>
34 #include <linux/swap.h>
35 #include <linux/pagemap.h>
36 #include <linux/string.h>
37 #include <linux/slab.h>
38 #include <linux/backing-dev.h>
39 #include <linux/shmem_fs.h>
40 #include <linux/mount.h>
41 #include <linux/writeback.h>
42 #include <linux/vfs.h>
43 #include <linux/blkdev.h>
44 #include <linux/security.h>
45 #include <linux/swapops.h>
46 #include <linux/mempolicy.h>
47 #include <linux/namei.h>
48 #include <asm/uaccess.h>
49 #include <asm/div64.h>
50 #include <asm/pgtable.h>
51
52 /* This magic number is used in glibc for posix shared memory */
53 #define TMPFS_MAGIC     0x01021994
54
55 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
56 #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
57 #define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
58
59 #define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
60 #define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
61
62 #define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
63
64 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
65 #define SHMEM_PAGEIN     VM_READ
66 #define SHMEM_TRUNCATE   VM_WRITE
67
68 /* Definition to limit shmem_truncate's steps between cond_rescheds */
69 #define LATENCY_LIMIT    64
70
71 /* Pretend that each entry is of this size in directory's i_size */
72 #define BOGO_DIRENT_SIZE 20
73
74 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
75 enum sgp_type {
76         SGP_QUICK,      /* don't try more than file page cache lookup */
77         SGP_READ,       /* don't exceed i_size, don't allocate page */
78         SGP_CACHE,      /* don't exceed i_size, may allocate page */
79         SGP_WRITE,      /* may exceed i_size, may allocate page */
80 };
81
82 static int shmem_getpage(struct inode *inode, unsigned long idx,
83                          struct page **pagep, enum sgp_type sgp, int *type);
84
85 static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
86 {
87         /*
88          * The above definition of ENTRIES_PER_PAGE, and the use of
89          * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
90          * might be reconsidered if it ever diverges from PAGE_SIZE.
91          */
92         return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
93 }
94
95 static inline void shmem_dir_free(struct page *page)
96 {
97         __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
98 }
99
100 static struct page **shmem_dir_map(struct page *page)
101 {
102         return (struct page **)kmap_atomic(page, KM_USER0);
103 }
104
105 static inline void shmem_dir_unmap(struct page **dir)
106 {
107         kunmap_atomic(dir, KM_USER0);
108 }
109
110 static swp_entry_t *shmem_swp_map(struct page *page)
111 {
112         return (swp_entry_t *)kmap_atomic(page, KM_USER1);
113 }
114
115 static inline void shmem_swp_balance_unmap(void)
116 {
117         /*
118          * When passing a pointer to an i_direct entry, to code which
119          * also handles indirect entries and so will shmem_swp_unmap,
120          * we must arrange for the preempt count to remain in balance.
121          * What kmap_atomic of a lowmem page does depends on config
122          * and architecture, so pretend to kmap_atomic some lowmem page.
123          */
124         (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
125 }
126
127 static inline void shmem_swp_unmap(swp_entry_t *entry)
128 {
129         kunmap_atomic(entry, KM_USER1);
130 }
131
132 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
133 {
134         return sb->s_fs_info;
135 }
136
137 /*
138  * shmem_file_setup pre-accounts the whole fixed size of a VM object,
139  * for shared memory and for shared anonymous (/dev/zero) mappings
140  * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
141  * consistent with the pre-accounting of private mappings ...
142  */
143 static inline int shmem_acct_size(unsigned long flags, loff_t size)
144 {
145         return (flags & VM_ACCOUNT)?
146                 security_vm_enough_memory(VM_ACCT(size)): 0;
147 }
148
149 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
150 {
151         if (flags & VM_ACCOUNT)
152                 vm_unacct_memory(VM_ACCT(size));
153 }
154
155 /*
156  * ... whereas tmpfs objects are accounted incrementally as
157  * pages are allocated, in order to allow huge sparse files.
158  * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
159  * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
160  */
161 static inline int shmem_acct_block(unsigned long flags)
162 {
163         return (flags & VM_ACCOUNT)?
164                 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
165 }
166
167 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
168 {
169         if (!(flags & VM_ACCOUNT))
170                 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
171 }
172
173 static struct super_operations shmem_ops;
174 static struct address_space_operations shmem_aops;
175 static struct file_operations shmem_file_operations;
176 static struct inode_operations shmem_inode_operations;
177 static struct inode_operations shmem_dir_inode_operations;
178 static struct vm_operations_struct shmem_vm_ops;
179
180 static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
181         .ra_pages       = 0,    /* No readahead */
182         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
183         .unplug_io_fn   = default_unplug_io_fn,
184 };
185
186 static LIST_HEAD(shmem_swaplist);
187 static DEFINE_SPINLOCK(shmem_swaplist_lock);
188
189 static void shmem_free_blocks(struct inode *inode, long pages)
190 {
191         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
192         if (sbinfo->max_blocks) {
193                 spin_lock(&sbinfo->stat_lock);
194                 sbinfo->free_blocks += pages;
195                 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
196                 spin_unlock(&sbinfo->stat_lock);
197         }
198 }
199
200 /*
201  * shmem_recalc_inode - recalculate the size of an inode
202  *
203  * @inode: inode to recalc
204  *
205  * We have to calculate the free blocks since the mm can drop
206  * undirtied hole pages behind our back.
207  *
208  * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
209  * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
210  *
211  * It has to be called with the spinlock held.
212  */
213 static void shmem_recalc_inode(struct inode *inode)
214 {
215         struct shmem_inode_info *info = SHMEM_I(inode);
216         long freed;
217
218         freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
219         if (freed > 0) {
220                 info->alloced -= freed;
221                 shmem_unacct_blocks(info->flags, freed);
222                 shmem_free_blocks(inode, freed);
223         }
224 }
225
226 /*
227  * shmem_swp_entry - find the swap vector position in the info structure
228  *
229  * @info:  info structure for the inode
230  * @index: index of the page to find
231  * @page:  optional page to add to the structure. Has to be preset to
232  *         all zeros
233  *
234  * If there is no space allocated yet it will return NULL when
235  * page is NULL, else it will use the page for the needed block,
236  * setting it to NULL on return to indicate that it has been used.
237  *
238  * The swap vector is organized the following way:
239  *
240  * There are SHMEM_NR_DIRECT entries directly stored in the
241  * shmem_inode_info structure. So small files do not need an addional
242  * allocation.
243  *
244  * For pages with index > SHMEM_NR_DIRECT there is the pointer
245  * i_indirect which points to a page which holds in the first half
246  * doubly indirect blocks, in the second half triple indirect blocks:
247  *
248  * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
249  * following layout (for SHMEM_NR_DIRECT == 16):
250  *
251  * i_indirect -> dir --> 16-19
252  *            |      +-> 20-23
253  *            |
254  *            +-->dir2 --> 24-27
255  *            |        +-> 28-31
256  *            |        +-> 32-35
257  *            |        +-> 36-39
258  *            |
259  *            +-->dir3 --> 40-43
260  *                     +-> 44-47
261  *                     +-> 48-51
262  *                     +-> 52-55
263  */
264 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
265 {
266         unsigned long offset;
267         struct page **dir;
268         struct page *subdir;
269
270         if (index < SHMEM_NR_DIRECT) {
271                 shmem_swp_balance_unmap();
272                 return info->i_direct+index;
273         }
274         if (!info->i_indirect) {
275                 if (page) {
276                         info->i_indirect = *page;
277                         *page = NULL;
278                 }
279                 return NULL;                    /* need another page */
280         }
281
282         index -= SHMEM_NR_DIRECT;
283         offset = index % ENTRIES_PER_PAGE;
284         index /= ENTRIES_PER_PAGE;
285         dir = shmem_dir_map(info->i_indirect);
286
287         if (index >= ENTRIES_PER_PAGE/2) {
288                 index -= ENTRIES_PER_PAGE/2;
289                 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
290                 index %= ENTRIES_PER_PAGE;
291                 subdir = *dir;
292                 if (!subdir) {
293                         if (page) {
294                                 *dir = *page;
295                                 *page = NULL;
296                         }
297                         shmem_dir_unmap(dir);
298                         return NULL;            /* need another page */
299                 }
300                 shmem_dir_unmap(dir);
301                 dir = shmem_dir_map(subdir);
302         }
303
304         dir += index;
305         subdir = *dir;
306         if (!subdir) {
307                 if (!page || !(subdir = *page)) {
308                         shmem_dir_unmap(dir);
309                         return NULL;            /* need a page */
310                 }
311                 *dir = subdir;
312                 *page = NULL;
313         }
314         shmem_dir_unmap(dir);
315         return shmem_swp_map(subdir) + offset;
316 }
317
318 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
319 {
320         long incdec = value? 1: -1;
321
322         entry->val = value;
323         info->swapped += incdec;
324         if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
325                 struct page *page = kmap_atomic_to_page(entry);
326                 set_page_private(page, page_private(page) + incdec);
327         }
328 }
329
330 /*
331  * shmem_swp_alloc - get the position of the swap entry for the page.
332  *                   If it does not exist allocate the entry.
333  *
334  * @info:       info structure for the inode
335  * @index:      index of the page to find
336  * @sgp:        check and recheck i_size? skip allocation?
337  */
338 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
339 {
340         struct inode *inode = &info->vfs_inode;
341         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
342         struct page *page = NULL;
343         swp_entry_t *entry;
344
345         if (sgp != SGP_WRITE &&
346             ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
347                 return ERR_PTR(-EINVAL);
348
349         while (!(entry = shmem_swp_entry(info, index, &page))) {
350                 if (sgp == SGP_READ)
351                         return shmem_swp_map(ZERO_PAGE(0));
352                 /*
353                  * Test free_blocks against 1 not 0, since we have 1 data
354                  * page (and perhaps indirect index pages) yet to allocate:
355                  * a waste to allocate index if we cannot allocate data.
356                  */
357                 if (sbinfo->max_blocks) {
358                         spin_lock(&sbinfo->stat_lock);
359                         if (sbinfo->free_blocks <= 1) {
360                                 spin_unlock(&sbinfo->stat_lock);
361                                 return ERR_PTR(-ENOSPC);
362                         }
363                         sbinfo->free_blocks--;
364                         inode->i_blocks += BLOCKS_PER_PAGE;
365                         spin_unlock(&sbinfo->stat_lock);
366                 }
367
368                 spin_unlock(&info->lock);
369                 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
370                 if (page)
371                         set_page_private(page, 0);
372                 spin_lock(&info->lock);
373
374                 if (!page) {
375                         shmem_free_blocks(inode, 1);
376                         return ERR_PTR(-ENOMEM);
377                 }
378                 if (sgp != SGP_WRITE &&
379                     ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
380                         entry = ERR_PTR(-EINVAL);
381                         break;
382                 }
383                 if (info->next_index <= index)
384                         info->next_index = index + 1;
385         }
386         if (page) {
387                 /* another task gave its page, or truncated the file */
388                 shmem_free_blocks(inode, 1);
389                 shmem_dir_free(page);
390         }
391         if (info->next_index <= index && !IS_ERR(entry))
392                 info->next_index = index + 1;
393         return entry;
394 }
395
396 /*
397  * shmem_free_swp - free some swap entries in a directory
398  *
399  * @dir:   pointer to the directory
400  * @edir:  pointer after last entry of the directory
401  */
402 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
403 {
404         swp_entry_t *ptr;
405         int freed = 0;
406
407         for (ptr = dir; ptr < edir; ptr++) {
408                 if (ptr->val) {
409                         free_swap_and_cache(*ptr);
410                         *ptr = (swp_entry_t){0};
411                         freed++;
412                 }
413         }
414         return freed;
415 }
416
417 static int shmem_map_and_free_swp(struct page *subdir,
418                 int offset, int limit, struct page ***dir)
419 {
420         swp_entry_t *ptr;
421         int freed = 0;
422
423         ptr = shmem_swp_map(subdir);
424         for (; offset < limit; offset += LATENCY_LIMIT) {
425                 int size = limit - offset;
426                 if (size > LATENCY_LIMIT)
427                         size = LATENCY_LIMIT;
428                 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
429                 if (need_resched()) {
430                         shmem_swp_unmap(ptr);
431                         if (*dir) {
432                                 shmem_dir_unmap(*dir);
433                                 *dir = NULL;
434                         }
435                         cond_resched();
436                         ptr = shmem_swp_map(subdir);
437                 }
438         }
439         shmem_swp_unmap(ptr);
440         return freed;
441 }
442
443 static void shmem_free_pages(struct list_head *next)
444 {
445         struct page *page;
446         int freed = 0;
447
448         do {
449                 page = container_of(next, struct page, lru);
450                 next = next->next;
451                 shmem_dir_free(page);
452                 freed++;
453                 if (freed >= LATENCY_LIMIT) {
454                         cond_resched();
455                         freed = 0;
456                 }
457         } while (next);
458 }
459
460 static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
461 {
462         struct shmem_inode_info *info = SHMEM_I(inode);
463         unsigned long idx;
464         unsigned long size;
465         unsigned long limit;
466         unsigned long stage;
467         unsigned long diroff;
468         struct page **dir;
469         struct page *topdir;
470         struct page *middir;
471         struct page *subdir;
472         swp_entry_t *ptr;
473         LIST_HEAD(pages_to_free);
474         long nr_pages_to_free = 0;
475         long nr_swaps_freed = 0;
476         int offset;
477         int freed;
478         int punch_hole = 0;
479
480         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
481         idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
482         if (idx >= info->next_index)
483                 return;
484
485         spin_lock(&info->lock);
486         info->flags |= SHMEM_TRUNCATE;
487         if (likely(end == (loff_t) -1)) {
488                 limit = info->next_index;
489                 info->next_index = idx;
490         } else {
491                 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
492                 if (limit > info->next_index)
493                         limit = info->next_index;
494                 punch_hole = 1;
495         }
496
497         topdir = info->i_indirect;
498         if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
499                 info->i_indirect = NULL;
500                 nr_pages_to_free++;
501                 list_add(&topdir->lru, &pages_to_free);
502         }
503         spin_unlock(&info->lock);
504
505         if (info->swapped && idx < SHMEM_NR_DIRECT) {
506                 ptr = info->i_direct;
507                 size = limit;
508                 if (size > SHMEM_NR_DIRECT)
509                         size = SHMEM_NR_DIRECT;
510                 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
511         }
512         if (!topdir)
513                 goto done2;
514
515         BUG_ON(limit <= SHMEM_NR_DIRECT);
516         limit -= SHMEM_NR_DIRECT;
517         idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
518         offset = idx % ENTRIES_PER_PAGE;
519         idx -= offset;
520
521         dir = shmem_dir_map(topdir);
522         stage = ENTRIES_PER_PAGEPAGE/2;
523         if (idx < ENTRIES_PER_PAGEPAGE/2) {
524                 middir = topdir;
525                 diroff = idx/ENTRIES_PER_PAGE;
526         } else {
527                 dir += ENTRIES_PER_PAGE/2;
528                 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
529                 while (stage <= idx)
530                         stage += ENTRIES_PER_PAGEPAGE;
531                 middir = *dir;
532                 if (*dir) {
533                         diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
534                                 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
535                         if (!diroff && !offset) {
536                                 *dir = NULL;
537                                 nr_pages_to_free++;
538                                 list_add(&middir->lru, &pages_to_free);
539                         }
540                         shmem_dir_unmap(dir);
541                         dir = shmem_dir_map(middir);
542                 } else {
543                         diroff = 0;
544                         offset = 0;
545                         idx = stage;
546                 }
547         }
548
549         for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
550                 if (unlikely(idx == stage)) {
551                         shmem_dir_unmap(dir);
552                         dir = shmem_dir_map(topdir) +
553                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
554                         while (!*dir) {
555                                 dir++;
556                                 idx += ENTRIES_PER_PAGEPAGE;
557                                 if (idx >= limit)
558                                         goto done1;
559                         }
560                         stage = idx + ENTRIES_PER_PAGEPAGE;
561                         middir = *dir;
562                         *dir = NULL;
563                         nr_pages_to_free++;
564                         list_add(&middir->lru, &pages_to_free);
565                         shmem_dir_unmap(dir);
566                         cond_resched();
567                         dir = shmem_dir_map(middir);
568                         diroff = 0;
569                 }
570                 subdir = dir[diroff];
571                 if (subdir && page_private(subdir)) {
572                         size = limit - idx;
573                         if (size > ENTRIES_PER_PAGE)
574                                 size = ENTRIES_PER_PAGE;
575                         freed = shmem_map_and_free_swp(subdir,
576                                                 offset, size, &dir);
577                         if (!dir)
578                                 dir = shmem_dir_map(middir);
579                         nr_swaps_freed += freed;
580                         if (offset)
581                                 spin_lock(&info->lock);
582                         set_page_private(subdir, page_private(subdir) - freed);
583                         if (offset)
584                                 spin_unlock(&info->lock);
585                         if (!punch_hole)
586                                 BUG_ON(page_private(subdir) > offset);
587                 }
588                 if (offset)
589                         offset = 0;
590                 else if (subdir && !page_private(subdir)) {
591                         dir[diroff] = NULL;
592                         nr_pages_to_free++;
593                         list_add(&subdir->lru, &pages_to_free);
594                 }
595         }
596 done1:
597         shmem_dir_unmap(dir);
598 done2:
599         if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
600                 /*
601                  * Call truncate_inode_pages again: racing shmem_unuse_inode
602                  * may have swizzled a page in from swap since vmtruncate or
603                  * generic_delete_inode did it, before we lowered next_index.
604                  * Also, though shmem_getpage checks i_size before adding to
605                  * cache, no recheck after: so fix the narrow window there too.
606                  */
607                 truncate_inode_pages_range(inode->i_mapping, start, end);
608         }
609
610         spin_lock(&info->lock);
611         info->flags &= ~SHMEM_TRUNCATE;
612         info->swapped -= nr_swaps_freed;
613         if (nr_pages_to_free)
614                 shmem_free_blocks(inode, nr_pages_to_free);
615         shmem_recalc_inode(inode);
616         spin_unlock(&info->lock);
617
618         /*
619          * Empty swap vector directory pages to be freed?
620          */
621         if (!list_empty(&pages_to_free)) {
622                 pages_to_free.prev->next = NULL;
623                 shmem_free_pages(pages_to_free.next);
624         }
625 }
626
627 static void shmem_truncate(struct inode *inode)
628 {
629         shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
630 }
631
632 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
633 {
634         struct inode *inode = dentry->d_inode;
635         struct page *page = NULL;
636         int error;
637
638         if (attr->ia_valid & ATTR_SIZE) {
639                 if (attr->ia_size < inode->i_size) {
640                         /*
641                          * If truncating down to a partial page, then
642                          * if that page is already allocated, hold it
643                          * in memory until the truncation is over, so
644                          * truncate_partial_page cannnot miss it were
645                          * it assigned to swap.
646                          */
647                         if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
648                                 (void) shmem_getpage(inode,
649                                         attr->ia_size>>PAGE_CACHE_SHIFT,
650                                                 &page, SGP_READ, NULL);
651                         }
652                         /*
653                          * Reset SHMEM_PAGEIN flag so that shmem_truncate can
654                          * detect if any pages might have been added to cache
655                          * after truncate_inode_pages.  But we needn't bother
656                          * if it's being fully truncated to zero-length: the
657                          * nrpages check is efficient enough in that case.
658                          */
659                         if (attr->ia_size) {
660                                 struct shmem_inode_info *info = SHMEM_I(inode);
661                                 spin_lock(&info->lock);
662                                 info->flags &= ~SHMEM_PAGEIN;
663                                 spin_unlock(&info->lock);
664                         }
665                 }
666         }
667
668         error = inode_change_ok(inode, attr);
669         if (!error)
670                 error = inode_setattr(inode, attr);
671         if (page)
672                 page_cache_release(page);
673         return error;
674 }
675
676 static void shmem_delete_inode(struct inode *inode)
677 {
678         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
679         struct shmem_inode_info *info = SHMEM_I(inode);
680
681         if (inode->i_op->truncate == shmem_truncate) {
682                 truncate_inode_pages(inode->i_mapping, 0);
683                 shmem_unacct_size(info->flags, inode->i_size);
684                 inode->i_size = 0;
685                 shmem_truncate(inode);
686                 if (!list_empty(&info->swaplist)) {
687                         spin_lock(&shmem_swaplist_lock);
688                         list_del_init(&info->swaplist);
689                         spin_unlock(&shmem_swaplist_lock);
690                 }
691         }
692         BUG_ON(inode->i_blocks);
693         if (sbinfo->max_inodes) {
694                 spin_lock(&sbinfo->stat_lock);
695                 sbinfo->free_inodes++;
696                 spin_unlock(&sbinfo->stat_lock);
697         }
698         clear_inode(inode);
699 }
700
701 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
702 {
703         swp_entry_t *ptr;
704
705         for (ptr = dir; ptr < edir; ptr++) {
706                 if (ptr->val == entry.val)
707                         return ptr - dir;
708         }
709         return -1;
710 }
711
712 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
713 {
714         struct inode *inode;
715         unsigned long idx;
716         unsigned long size;
717         unsigned long limit;
718         unsigned long stage;
719         struct page **dir;
720         struct page *subdir;
721         swp_entry_t *ptr;
722         int offset;
723
724         idx = 0;
725         ptr = info->i_direct;
726         spin_lock(&info->lock);
727         limit = info->next_index;
728         size = limit;
729         if (size > SHMEM_NR_DIRECT)
730                 size = SHMEM_NR_DIRECT;
731         offset = shmem_find_swp(entry, ptr, ptr+size);
732         if (offset >= 0) {
733                 shmem_swp_balance_unmap();
734                 goto found;
735         }
736         if (!info->i_indirect)
737                 goto lost2;
738
739         dir = shmem_dir_map(info->i_indirect);
740         stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
741
742         for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
743                 if (unlikely(idx == stage)) {
744                         shmem_dir_unmap(dir-1);
745                         dir = shmem_dir_map(info->i_indirect) +
746                             ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
747                         while (!*dir) {
748                                 dir++;
749                                 idx += ENTRIES_PER_PAGEPAGE;
750                                 if (idx >= limit)
751                                         goto lost1;
752                         }
753                         stage = idx + ENTRIES_PER_PAGEPAGE;
754                         subdir = *dir;
755                         shmem_dir_unmap(dir);
756                         dir = shmem_dir_map(subdir);
757                 }
758                 subdir = *dir;
759                 if (subdir && page_private(subdir)) {
760                         ptr = shmem_swp_map(subdir);
761                         size = limit - idx;
762                         if (size > ENTRIES_PER_PAGE)
763                                 size = ENTRIES_PER_PAGE;
764                         offset = shmem_find_swp(entry, ptr, ptr+size);
765                         if (offset >= 0) {
766                                 shmem_dir_unmap(dir);
767                                 goto found;
768                         }
769                         shmem_swp_unmap(ptr);
770                 }
771         }
772 lost1:
773         shmem_dir_unmap(dir-1);
774 lost2:
775         spin_unlock(&info->lock);
776         return 0;
777 found:
778         idx += offset;
779         inode = &info->vfs_inode;
780         if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
781                 info->flags |= SHMEM_PAGEIN;
782                 shmem_swp_set(info, ptr + offset, 0);
783         }
784         shmem_swp_unmap(ptr);
785         spin_unlock(&info->lock);
786         /*
787          * Decrement swap count even when the entry is left behind:
788          * try_to_unuse will skip over mms, then reincrement count.
789          */
790         swap_free(entry);
791         return 1;
792 }
793
794 /*
795  * shmem_unuse() search for an eventually swapped out shmem page.
796  */
797 int shmem_unuse(swp_entry_t entry, struct page *page)
798 {
799         struct list_head *p, *next;
800         struct shmem_inode_info *info;
801         int found = 0;
802
803         spin_lock(&shmem_swaplist_lock);
804         list_for_each_safe(p, next, &shmem_swaplist) {
805                 info = list_entry(p, struct shmem_inode_info, swaplist);
806                 if (!info->swapped)
807                         list_del_init(&info->swaplist);
808                 else if (shmem_unuse_inode(info, entry, page)) {
809                         /* move head to start search for next from here */
810                         list_move_tail(&shmem_swaplist, &info->swaplist);
811                         found = 1;
812                         break;
813                 }
814         }
815         spin_unlock(&shmem_swaplist_lock);
816         return found;
817 }
818
819 /*
820  * Move the page from the page cache to the swap cache.
821  */
822 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
823 {
824         struct shmem_inode_info *info;
825         swp_entry_t *entry, swap;
826         struct address_space *mapping;
827         unsigned long index;
828         struct inode *inode;
829
830         BUG_ON(!PageLocked(page));
831         BUG_ON(page_mapped(page));
832
833         mapping = page->mapping;
834         index = page->index;
835         inode = mapping->host;
836         info = SHMEM_I(inode);
837         if (info->flags & VM_LOCKED)
838                 goto redirty;
839         swap = get_swap_page();
840         if (!swap.val)
841                 goto redirty;
842
843         spin_lock(&info->lock);
844         shmem_recalc_inode(inode);
845         if (index >= info->next_index) {
846                 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
847                 goto unlock;
848         }
849         entry = shmem_swp_entry(info, index, NULL);
850         BUG_ON(!entry);
851         BUG_ON(entry->val);
852
853         if (move_to_swap_cache(page, swap) == 0) {
854                 shmem_swp_set(info, entry, swap.val);
855                 shmem_swp_unmap(entry);
856                 spin_unlock(&info->lock);
857                 if (list_empty(&info->swaplist)) {
858                         spin_lock(&shmem_swaplist_lock);
859                         /* move instead of add in case we're racing */
860                         list_move_tail(&info->swaplist, &shmem_swaplist);
861                         spin_unlock(&shmem_swaplist_lock);
862                 }
863                 unlock_page(page);
864                 return 0;
865         }
866
867         shmem_swp_unmap(entry);
868 unlock:
869         spin_unlock(&info->lock);
870         swap_free(swap);
871 redirty:
872         set_page_dirty(page);
873         return AOP_WRITEPAGE_ACTIVATE;  /* Return with the page locked */
874 }
875
876 #ifdef CONFIG_NUMA
877 static struct page *shmem_swapin_async(struct shared_policy *p,
878                                        swp_entry_t entry, unsigned long idx)
879 {
880         struct page *page;
881         struct vm_area_struct pvma;
882
883         /* Create a pseudo vma that just contains the policy */
884         memset(&pvma, 0, sizeof(struct vm_area_struct));
885         pvma.vm_end = PAGE_SIZE;
886         pvma.vm_pgoff = idx;
887         pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
888         page = read_swap_cache_async(entry, &pvma, 0);
889         mpol_free(pvma.vm_policy);
890         return page;
891 }
892
893 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
894                           unsigned long idx)
895 {
896         struct shared_policy *p = &info->policy;
897         int i, num;
898         struct page *page;
899         unsigned long offset;
900
901         num = valid_swaphandles(entry, &offset);
902         for (i = 0; i < num; offset++, i++) {
903                 page = shmem_swapin_async(p,
904                                 swp_entry(swp_type(entry), offset), idx);
905                 if (!page)
906                         break;
907                 page_cache_release(page);
908         }
909         lru_add_drain();        /* Push any new pages onto the LRU now */
910         return shmem_swapin_async(p, entry, idx);
911 }
912
913 static struct page *
914 shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info,
915                  unsigned long idx)
916 {
917         struct vm_area_struct pvma;
918         struct page *page;
919
920         memset(&pvma, 0, sizeof(struct vm_area_struct));
921         pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
922         pvma.vm_pgoff = idx;
923         pvma.vm_end = PAGE_SIZE;
924         page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
925         mpol_free(pvma.vm_policy);
926         return page;
927 }
928 #else
929 static inline struct page *
930 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
931 {
932         swapin_readahead(entry, 0, NULL);
933         return read_swap_cache_async(entry, NULL, 0);
934 }
935
936 static inline struct page *
937 shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx)
938 {
939         return alloc_page(gfp | __GFP_ZERO);
940 }
941 #endif
942
943 /*
944  * shmem_getpage - either get the page from swap or allocate a new one
945  *
946  * If we allocate a new one we do not mark it dirty. That's up to the
947  * vm. If we swap it in we mark it dirty since we also free the swap
948  * entry since a page cannot live in both the swap and page cache
949  */
950 static int shmem_getpage(struct inode *inode, unsigned long idx,
951                         struct page **pagep, enum sgp_type sgp, int *type)
952 {
953         struct address_space *mapping = inode->i_mapping;
954         struct shmem_inode_info *info = SHMEM_I(inode);
955         struct shmem_sb_info *sbinfo;
956         struct page *filepage = *pagep;
957         struct page *swappage;
958         swp_entry_t *entry;
959         swp_entry_t swap;
960         int error;
961
962         if (idx >= SHMEM_MAX_INDEX)
963                 return -EFBIG;
964         /*
965          * Normally, filepage is NULL on entry, and either found
966          * uptodate immediately, or allocated and zeroed, or read
967          * in under swappage, which is then assigned to filepage.
968          * But shmem_prepare_write passes in a locked filepage,
969          * which may be found not uptodate by other callers too,
970          * and may need to be copied from the swappage read in.
971          */
972 repeat:
973         if (!filepage)
974                 filepage = find_lock_page(mapping, idx);
975         if (filepage && PageUptodate(filepage))
976                 goto done;
977         error = 0;
978         if (sgp == SGP_QUICK)
979                 goto failed;
980
981         spin_lock(&info->lock);
982         shmem_recalc_inode(inode);
983         entry = shmem_swp_alloc(info, idx, sgp);
984         if (IS_ERR(entry)) {
985                 spin_unlock(&info->lock);
986                 error = PTR_ERR(entry);
987                 goto failed;
988         }
989         swap = *entry;
990
991         if (swap.val) {
992                 /* Look it up and read it in.. */
993                 swappage = lookup_swap_cache(swap);
994                 if (!swappage) {
995                         shmem_swp_unmap(entry);
996                         spin_unlock(&info->lock);
997                         /* here we actually do the io */
998                         if (type && *type == VM_FAULT_MINOR) {
999                                 inc_page_state(pgmajfault);
1000                                 *type = VM_FAULT_MAJOR;
1001                         }
1002                         swappage = shmem_swapin(info, swap, idx);
1003                         if (!swappage) {
1004                                 spin_lock(&info->lock);
1005                                 entry = shmem_swp_alloc(info, idx, sgp);
1006                                 if (IS_ERR(entry))
1007                                         error = PTR_ERR(entry);
1008                                 else {
1009                                         if (entry->val == swap.val)
1010                                                 error = -ENOMEM;
1011                                         shmem_swp_unmap(entry);
1012                                 }
1013                                 spin_unlock(&info->lock);
1014                                 if (error)
1015                                         goto failed;
1016                                 goto repeat;
1017                         }
1018                         wait_on_page_locked(swappage);
1019                         page_cache_release(swappage);
1020                         goto repeat;
1021                 }
1022
1023                 /* We have to do this with page locked to prevent races */
1024                 if (TestSetPageLocked(swappage)) {
1025                         shmem_swp_unmap(entry);
1026                         spin_unlock(&info->lock);
1027                         wait_on_page_locked(swappage);
1028                         page_cache_release(swappage);
1029                         goto repeat;
1030                 }
1031                 if (PageWriteback(swappage)) {
1032                         shmem_swp_unmap(entry);
1033                         spin_unlock(&info->lock);
1034                         wait_on_page_writeback(swappage);
1035                         unlock_page(swappage);
1036                         page_cache_release(swappage);
1037                         goto repeat;
1038                 }
1039                 if (!PageUptodate(swappage)) {
1040                         shmem_swp_unmap(entry);
1041                         spin_unlock(&info->lock);
1042                         unlock_page(swappage);
1043                         page_cache_release(swappage);
1044                         error = -EIO;
1045                         goto failed;
1046                 }
1047
1048                 if (filepage) {
1049                         shmem_swp_set(info, entry, 0);
1050                         shmem_swp_unmap(entry);
1051                         delete_from_swap_cache(swappage);
1052                         spin_unlock(&info->lock);
1053                         copy_highpage(filepage, swappage);
1054                         unlock_page(swappage);
1055                         page_cache_release(swappage);
1056                         flush_dcache_page(filepage);
1057                         SetPageUptodate(filepage);
1058                         set_page_dirty(filepage);
1059                         swap_free(swap);
1060                 } else if (!(error = move_from_swap_cache(
1061                                 swappage, idx, mapping))) {
1062                         info->flags |= SHMEM_PAGEIN;
1063                         shmem_swp_set(info, entry, 0);
1064                         shmem_swp_unmap(entry);
1065                         spin_unlock(&info->lock);
1066                         filepage = swappage;
1067                         swap_free(swap);
1068                 } else {
1069                         shmem_swp_unmap(entry);
1070                         spin_unlock(&info->lock);
1071                         unlock_page(swappage);
1072                         page_cache_release(swappage);
1073                         if (error == -ENOMEM) {
1074                                 /* let kswapd refresh zone for GFP_ATOMICs */
1075                                 blk_congestion_wait(WRITE, HZ/50);
1076                         }
1077                         goto repeat;
1078                 }
1079         } else if (sgp == SGP_READ && !filepage) {
1080                 shmem_swp_unmap(entry);
1081                 filepage = find_get_page(mapping, idx);
1082                 if (filepage &&
1083                     (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1084                         spin_unlock(&info->lock);
1085                         wait_on_page_locked(filepage);
1086                         page_cache_release(filepage);
1087                         filepage = NULL;
1088                         goto repeat;
1089                 }
1090                 spin_unlock(&info->lock);
1091         } else {
1092                 shmem_swp_unmap(entry);
1093                 sbinfo = SHMEM_SB(inode->i_sb);
1094                 if (sbinfo->max_blocks) {
1095                         spin_lock(&sbinfo->stat_lock);
1096                         if (sbinfo->free_blocks == 0 ||
1097                             shmem_acct_block(info->flags)) {
1098                                 spin_unlock(&sbinfo->stat_lock);
1099                                 spin_unlock(&info->lock);
1100                                 error = -ENOSPC;
1101                                 goto failed;
1102                         }
1103                         sbinfo->free_blocks--;
1104                         inode->i_blocks += BLOCKS_PER_PAGE;
1105                         spin_unlock(&sbinfo->stat_lock);
1106                 } else if (shmem_acct_block(info->flags)) {
1107                         spin_unlock(&info->lock);
1108                         error = -ENOSPC;
1109                         goto failed;
1110                 }
1111
1112                 if (!filepage) {
1113                         spin_unlock(&info->lock);
1114                         filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1115                                                     info,
1116                                                     idx);
1117                         if (!filepage) {
1118                                 shmem_unacct_blocks(info->flags, 1);
1119                                 shmem_free_blocks(inode, 1);
1120                                 error = -ENOMEM;
1121                                 goto failed;
1122                         }
1123
1124                         spin_lock(&info->lock);
1125                         entry = shmem_swp_alloc(info, idx, sgp);
1126                         if (IS_ERR(entry))
1127                                 error = PTR_ERR(entry);
1128                         else {
1129                                 swap = *entry;
1130                                 shmem_swp_unmap(entry);
1131                         }
1132                         if (error || swap.val || 0 != add_to_page_cache_lru(
1133                                         filepage, mapping, idx, GFP_ATOMIC)) {
1134                                 spin_unlock(&info->lock);
1135                                 page_cache_release(filepage);
1136                                 shmem_unacct_blocks(info->flags, 1);
1137                                 shmem_free_blocks(inode, 1);
1138                                 filepage = NULL;
1139                                 if (error)
1140                                         goto failed;
1141                                 goto repeat;
1142                         }
1143                         info->flags |= SHMEM_PAGEIN;
1144                 }
1145
1146                 info->alloced++;
1147                 spin_unlock(&info->lock);
1148                 flush_dcache_page(filepage);
1149                 SetPageUptodate(filepage);
1150         }
1151 done:
1152         if (*pagep != filepage) {
1153                 unlock_page(filepage);
1154                 *pagep = filepage;
1155         }
1156         return 0;
1157
1158 failed:
1159         if (*pagep != filepage) {
1160                 unlock_page(filepage);
1161                 page_cache_release(filepage);
1162         }
1163         return error;
1164 }
1165
1166 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1167 {
1168         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1169         struct page *page = NULL;
1170         unsigned long idx;
1171         int error;
1172
1173         idx = (address - vma->vm_start) >> PAGE_SHIFT;
1174         idx += vma->vm_pgoff;
1175         idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1176         if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
1177                 return NOPAGE_SIGBUS;
1178
1179         error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1180         if (error)
1181                 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1182
1183         mark_page_accessed(page);
1184         return page;
1185 }
1186
1187 static int shmem_populate(struct vm_area_struct *vma,
1188         unsigned long addr, unsigned long len,
1189         pgprot_t prot, unsigned long pgoff, int nonblock)
1190 {
1191         struct inode *inode = vma->vm_file->f_dentry->d_inode;
1192         struct mm_struct *mm = vma->vm_mm;
1193         enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1194         unsigned long size;
1195
1196         size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1197         if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1198                 return -EINVAL;
1199
1200         while ((long) len > 0) {
1201                 struct page *page = NULL;
1202                 int err;
1203                 /*
1204                  * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1205                  */
1206                 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1207                 if (err)
1208                         return err;
1209                 /* Page may still be null, but only if nonblock was set. */
1210                 if (page) {
1211                         mark_page_accessed(page);
1212                         err = install_page(mm, vma, addr, page, prot);
1213                         if (err) {
1214                                 page_cache_release(page);
1215                                 return err;
1216                         }
1217                 } else if (vma->vm_flags & VM_NONLINEAR) {
1218                         /* No page was found just because we can't read it in
1219                          * now (being here implies nonblock != 0), but the page
1220                          * may exist, so set the PTE to fault it in later. */
1221                         err = install_file_pte(mm, vma, addr, pgoff, prot);
1222                         if (err)
1223                                 return err;
1224                 }
1225
1226                 len -= PAGE_SIZE;
1227                 addr += PAGE_SIZE;
1228                 pgoff++;
1229         }
1230         return 0;
1231 }
1232
1233 #ifdef CONFIG_NUMA
1234 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1235 {
1236         struct inode *i = vma->vm_file->f_dentry->d_inode;
1237         return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1238 }
1239
1240 struct mempolicy *
1241 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1242 {
1243         struct inode *i = vma->vm_file->f_dentry->d_inode;
1244         unsigned long idx;
1245
1246         idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1247         return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1248 }
1249 #endif
1250
1251 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1252 {
1253         struct inode *inode = file->f_dentry->d_inode;
1254         struct shmem_inode_info *info = SHMEM_I(inode);
1255         int retval = -ENOMEM;
1256
1257         spin_lock(&info->lock);
1258         if (lock && !(info->flags & VM_LOCKED)) {
1259                 if (!user_shm_lock(inode->i_size, user))
1260                         goto out_nomem;
1261                 info->flags |= VM_LOCKED;
1262         }
1263         if (!lock && (info->flags & VM_LOCKED) && user) {
1264                 user_shm_unlock(inode->i_size, user);
1265                 info->flags &= ~VM_LOCKED;
1266         }
1267         retval = 0;
1268 out_nomem:
1269         spin_unlock(&info->lock);
1270         return retval;
1271 }
1272
1273 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1274 {
1275         file_accessed(file);
1276         vma->vm_ops = &shmem_vm_ops;
1277         return 0;
1278 }
1279
1280 static struct inode *
1281 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1282 {
1283         struct inode *inode;
1284         struct shmem_inode_info *info;
1285         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1286
1287         if (sbinfo->max_inodes) {
1288                 spin_lock(&sbinfo->stat_lock);
1289                 if (!sbinfo->free_inodes) {
1290                         spin_unlock(&sbinfo->stat_lock);
1291                         return NULL;
1292                 }
1293                 sbinfo->free_inodes--;
1294                 spin_unlock(&sbinfo->stat_lock);
1295         }
1296
1297         inode = new_inode(sb);
1298         if (inode) {
1299                 inode->i_mode = mode;
1300                 inode->i_uid = current->fsuid;
1301                 inode->i_gid = current->fsgid;
1302                 inode->i_blksize = PAGE_CACHE_SIZE;
1303                 inode->i_blocks = 0;
1304                 inode->i_mapping->a_ops = &shmem_aops;
1305                 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1306                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1307                 info = SHMEM_I(inode);
1308                 memset(info, 0, (char *)inode - (char *)info);
1309                 spin_lock_init(&info->lock);
1310                 INIT_LIST_HEAD(&info->swaplist);
1311
1312                 switch (mode & S_IFMT) {
1313                 default:
1314                         init_special_inode(inode, mode, dev);
1315                         break;
1316                 case S_IFREG:
1317                         inode->i_op = &shmem_inode_operations;
1318                         inode->i_fop = &shmem_file_operations;
1319                         mpol_shared_policy_init(&info->policy);
1320                         break;
1321                 case S_IFDIR:
1322                         inode->i_nlink++;
1323                         /* Some things misbehave if size == 0 on a directory */
1324                         inode->i_size = 2 * BOGO_DIRENT_SIZE;
1325                         inode->i_op = &shmem_dir_inode_operations;
1326                         inode->i_fop = &simple_dir_operations;
1327                         break;
1328                 case S_IFLNK:
1329                         /*
1330                          * Must not load anything in the rbtree,
1331                          * mpol_free_shared_policy will not be called.
1332                          */
1333                         mpol_shared_policy_init(&info->policy);
1334                         break;
1335                 }
1336         } else if (sbinfo->max_inodes) {
1337                 spin_lock(&sbinfo->stat_lock);
1338                 sbinfo->free_inodes++;
1339                 spin_unlock(&sbinfo->stat_lock);
1340         }
1341         return inode;
1342 }
1343
1344 #ifdef CONFIG_TMPFS
1345 static struct inode_operations shmem_symlink_inode_operations;
1346 static struct inode_operations shmem_symlink_inline_operations;
1347
1348 /*
1349  * Normally tmpfs makes no use of shmem_prepare_write, but it
1350  * lets a tmpfs file be used read-write below the loop driver.
1351  */
1352 static int
1353 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1354 {
1355         struct inode *inode = page->mapping->host;
1356         return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1357 }
1358
1359 static ssize_t
1360 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1361 {
1362         struct inode    *inode = file->f_dentry->d_inode;
1363         loff_t          pos;
1364         unsigned long   written;
1365         ssize_t         err;
1366
1367         if ((ssize_t) count < 0)
1368                 return -EINVAL;
1369
1370         if (!access_ok(VERIFY_READ, buf, count))
1371                 return -EFAULT;
1372
1373         down(&inode->i_sem);
1374
1375         pos = *ppos;
1376         written = 0;
1377
1378         err = generic_write_checks(file, &pos, &count, 0);
1379         if (err || !count)
1380                 goto out;
1381
1382         err = remove_suid(file->f_dentry);
1383         if (err)
1384                 goto out;
1385
1386         inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1387
1388         do {
1389                 struct page *page = NULL;
1390                 unsigned long bytes, index, offset;
1391                 char *kaddr;
1392                 int left;
1393
1394                 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1395                 index = pos >> PAGE_CACHE_SHIFT;
1396                 bytes = PAGE_CACHE_SIZE - offset;
1397                 if (bytes > count)
1398                         bytes = count;
1399
1400                 /*
1401                  * We don't hold page lock across copy from user -
1402                  * what would it guard against? - so no deadlock here.
1403                  * But it still may be a good idea to prefault below.
1404                  */
1405
1406                 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1407                 if (err)
1408                         break;
1409
1410                 left = bytes;
1411                 if (PageHighMem(page)) {
1412                         volatile unsigned char dummy;
1413                         __get_user(dummy, buf);
1414                         __get_user(dummy, buf + bytes - 1);
1415
1416                         kaddr = kmap_atomic(page, KM_USER0);
1417                         left = __copy_from_user_inatomic(kaddr + offset,
1418                                                         buf, bytes);
1419                         kunmap_atomic(kaddr, KM_USER0);
1420                 }
1421                 if (left) {
1422                         kaddr = kmap(page);
1423                         left = __copy_from_user(kaddr + offset, buf, bytes);
1424                         kunmap(page);
1425                 }
1426
1427                 written += bytes;
1428                 count -= bytes;
1429                 pos += bytes;
1430                 buf += bytes;
1431                 if (pos > inode->i_size)
1432                         i_size_write(inode, pos);
1433
1434                 flush_dcache_page(page);
1435                 set_page_dirty(page);
1436                 mark_page_accessed(page);
1437                 page_cache_release(page);
1438
1439                 if (left) {
1440                         pos -= left;
1441                         written -= left;
1442                         err = -EFAULT;
1443                         break;
1444                 }
1445
1446                 /*
1447                  * Our dirty pages are not counted in nr_dirty,
1448                  * and we do not attempt to balance dirty pages.
1449                  */
1450
1451                 cond_resched();
1452         } while (count);
1453
1454         *ppos = pos;
1455         if (written)
1456                 err = written;
1457 out:
1458         up(&inode->i_sem);
1459         return err;
1460 }
1461
1462 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1463 {
1464         struct inode *inode = filp->f_dentry->d_inode;
1465         struct address_space *mapping = inode->i_mapping;
1466         unsigned long index, offset;
1467
1468         index = *ppos >> PAGE_CACHE_SHIFT;
1469         offset = *ppos & ~PAGE_CACHE_MASK;
1470
1471         for (;;) {
1472                 struct page *page = NULL;
1473                 unsigned long end_index, nr, ret;
1474                 loff_t i_size = i_size_read(inode);
1475
1476                 end_index = i_size >> PAGE_CACHE_SHIFT;
1477                 if (index > end_index)
1478                         break;
1479                 if (index == end_index) {
1480                         nr = i_size & ~PAGE_CACHE_MASK;
1481                         if (nr <= offset)
1482                                 break;
1483                 }
1484
1485                 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1486                 if (desc->error) {
1487                         if (desc->error == -EINVAL)
1488                                 desc->error = 0;
1489                         break;
1490                 }
1491
1492                 /*
1493                  * We must evaluate after, since reads (unlike writes)
1494                  * are called without i_sem protection against truncate
1495                  */
1496                 nr = PAGE_CACHE_SIZE;
1497                 i_size = i_size_read(inode);
1498                 end_index = i_size >> PAGE_CACHE_SHIFT;
1499                 if (index == end_index) {
1500                         nr = i_size & ~PAGE_CACHE_MASK;
1501                         if (nr <= offset) {
1502                                 if (page)
1503                                         page_cache_release(page);
1504                                 break;
1505                         }
1506                 }
1507                 nr -= offset;
1508
1509                 if (page) {
1510                         /*
1511                          * If users can be writing to this page using arbitrary
1512                          * virtual addresses, take care about potential aliasing
1513                          * before reading the page on the kernel side.
1514                          */
1515                         if (mapping_writably_mapped(mapping))
1516                                 flush_dcache_page(page);
1517                         /*
1518                          * Mark the page accessed if we read the beginning.
1519                          */
1520                         if (!offset)
1521                                 mark_page_accessed(page);
1522                 } else {
1523                         page = ZERO_PAGE(0);
1524                         page_cache_get(page);
1525                 }
1526
1527                 /*
1528                  * Ok, we have the page, and it's up-to-date, so
1529                  * now we can copy it to user space...
1530                  *
1531                  * The actor routine returns how many bytes were actually used..
1532                  * NOTE! This may not be the same as how much of a user buffer
1533                  * we filled up (we may be padding etc), so we can only update
1534                  * "pos" here (the actor routine has to update the user buffer
1535                  * pointers and the remaining count).
1536                  */
1537                 ret = actor(desc, page, offset, nr);
1538                 offset += ret;
1539                 index += offset >> PAGE_CACHE_SHIFT;
1540                 offset &= ~PAGE_CACHE_MASK;
1541
1542                 page_cache_release(page);
1543                 if (ret != nr || !desc->count)
1544                         break;
1545
1546                 cond_resched();
1547         }
1548
1549         *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1550         file_accessed(filp);
1551 }
1552
1553 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1554 {
1555         read_descriptor_t desc;
1556
1557         if ((ssize_t) count < 0)
1558                 return -EINVAL;
1559         if (!access_ok(VERIFY_WRITE, buf, count))
1560                 return -EFAULT;
1561         if (!count)
1562                 return 0;
1563
1564         desc.written = 0;
1565         desc.count = count;
1566         desc.arg.buf = buf;
1567         desc.error = 0;
1568
1569         do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1570         if (desc.written)
1571                 return desc.written;
1572         return desc.error;
1573 }
1574
1575 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1576                          size_t count, read_actor_t actor, void *target)
1577 {
1578         read_descriptor_t desc;
1579
1580         if (!count)
1581                 return 0;
1582
1583         desc.written = 0;
1584         desc.count = count;
1585         desc.arg.data = target;
1586         desc.error = 0;
1587
1588         do_shmem_file_read(in_file, ppos, &desc, actor);
1589         if (desc.written)
1590                 return desc.written;
1591         return desc.error;
1592 }
1593
1594 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1595 {
1596         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1597
1598         buf->f_type = TMPFS_MAGIC;
1599         buf->f_bsize = PAGE_CACHE_SIZE;
1600         buf->f_namelen = NAME_MAX;
1601         spin_lock(&sbinfo->stat_lock);
1602         if (sbinfo->max_blocks) {
1603                 buf->f_blocks = sbinfo->max_blocks;
1604                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1605         }
1606         if (sbinfo->max_inodes) {
1607                 buf->f_files = sbinfo->max_inodes;
1608                 buf->f_ffree = sbinfo->free_inodes;
1609         }
1610         /* else leave those fields 0 like simple_statfs */
1611         spin_unlock(&sbinfo->stat_lock);
1612         return 0;
1613 }
1614
1615 /*
1616  * File creation. Allocate an inode, and we're done..
1617  */
1618 static int
1619 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1620 {
1621         struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1622         int error = -ENOSPC;
1623
1624         if (inode) {
1625                 error = security_inode_init_security(inode, dir, NULL, NULL,
1626                                                      NULL);
1627                 if (error) {
1628                         if (error != -EOPNOTSUPP) {
1629                                 iput(inode);
1630                                 return error;
1631                         }
1632                         error = 0;
1633                 }
1634                 if (dir->i_mode & S_ISGID) {
1635                         inode->i_gid = dir->i_gid;
1636                         if (S_ISDIR(mode))
1637                                 inode->i_mode |= S_ISGID;
1638                 }
1639                 dir->i_size += BOGO_DIRENT_SIZE;
1640                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1641                 d_instantiate(dentry, inode);
1642                 dget(dentry); /* Extra count - pin the dentry in core */
1643         }
1644         return error;
1645 }
1646
1647 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1648 {
1649         int error;
1650
1651         if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1652                 return error;
1653         dir->i_nlink++;
1654         return 0;
1655 }
1656
1657 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1658                 struct nameidata *nd)
1659 {
1660         return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1661 }
1662
1663 /*
1664  * Link a file..
1665  */
1666 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1667 {
1668         struct inode *inode = old_dentry->d_inode;
1669         struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1670
1671         /*
1672          * No ordinary (disk based) filesystem counts links as inodes;
1673          * but each new link needs a new dentry, pinning lowmem, and
1674          * tmpfs dentries cannot be pruned until they are unlinked.
1675          */
1676         if (sbinfo->max_inodes) {
1677                 spin_lock(&sbinfo->stat_lock);
1678                 if (!sbinfo->free_inodes) {
1679                         spin_unlock(&sbinfo->stat_lock);
1680                         return -ENOSPC;
1681                 }
1682                 sbinfo->free_inodes--;
1683                 spin_unlock(&sbinfo->stat_lock);
1684         }
1685
1686         dir->i_size += BOGO_DIRENT_SIZE;
1687         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1688         inode->i_nlink++;
1689         atomic_inc(&inode->i_count);    /* New dentry reference */
1690         dget(dentry);           /* Extra pinning count for the created dentry */
1691         d_instantiate(dentry, inode);
1692         return 0;
1693 }
1694
1695 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1696 {
1697         struct inode *inode = dentry->d_inode;
1698
1699         if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1700                 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1701                 if (sbinfo->max_inodes) {
1702                         spin_lock(&sbinfo->stat_lock);
1703                         sbinfo->free_inodes++;
1704                         spin_unlock(&sbinfo->stat_lock);
1705                 }
1706         }
1707
1708         dir->i_size -= BOGO_DIRENT_SIZE;
1709         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1710         inode->i_nlink--;
1711         dput(dentry);   /* Undo the count from "create" - this does all the work */
1712         return 0;
1713 }
1714
1715 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1716 {
1717         if (!simple_empty(dentry))
1718                 return -ENOTEMPTY;
1719
1720         dir->i_nlink--;
1721         return shmem_unlink(dir, dentry);
1722 }
1723
1724 /*
1725  * The VFS layer already does all the dentry stuff for rename,
1726  * we just have to decrement the usage count for the target if
1727  * it exists so that the VFS layer correctly free's it when it
1728  * gets overwritten.
1729  */
1730 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1731 {
1732         struct inode *inode = old_dentry->d_inode;
1733         int they_are_dirs = S_ISDIR(inode->i_mode);
1734
1735         if (!simple_empty(new_dentry))
1736                 return -ENOTEMPTY;
1737
1738         if (new_dentry->d_inode) {
1739                 (void) shmem_unlink(new_dir, new_dentry);
1740                 if (they_are_dirs)
1741                         old_dir->i_nlink--;
1742         } else if (they_are_dirs) {
1743                 old_dir->i_nlink--;
1744                 new_dir->i_nlink++;
1745         }
1746
1747         old_dir->i_size -= BOGO_DIRENT_SIZE;
1748         new_dir->i_size += BOGO_DIRENT_SIZE;
1749         old_dir->i_ctime = old_dir->i_mtime =
1750         new_dir->i_ctime = new_dir->i_mtime =
1751         inode->i_ctime = CURRENT_TIME;
1752         return 0;
1753 }
1754
1755 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1756 {
1757         int error;
1758         int len;
1759         struct inode *inode;
1760         struct page *page = NULL;
1761         char *kaddr;
1762         struct shmem_inode_info *info;
1763
1764         len = strlen(symname) + 1;
1765         if (len > PAGE_CACHE_SIZE)
1766                 return -ENAMETOOLONG;
1767
1768         inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1769         if (!inode)
1770                 return -ENOSPC;
1771
1772         error = security_inode_init_security(inode, dir, NULL, NULL,
1773                                              NULL);
1774         if (error) {
1775                 if (error != -EOPNOTSUPP) {
1776                         iput(inode);
1777                         return error;
1778                 }
1779                 error = 0;
1780         }
1781
1782         info = SHMEM_I(inode);
1783         inode->i_size = len-1;
1784         if (len <= (char *)inode - (char *)info) {
1785                 /* do it inline */
1786                 memcpy(info, symname, len);
1787                 inode->i_op = &shmem_symlink_inline_operations;
1788         } else {
1789                 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1790                 if (error) {
1791                         iput(inode);
1792                         return error;
1793                 }
1794                 inode->i_op = &shmem_symlink_inode_operations;
1795                 kaddr = kmap_atomic(page, KM_USER0);
1796                 memcpy(kaddr, symname, len);
1797                 kunmap_atomic(kaddr, KM_USER0);
1798                 set_page_dirty(page);
1799                 page_cache_release(page);
1800         }
1801         if (dir->i_mode & S_ISGID)
1802                 inode->i_gid = dir->i_gid;
1803         dir->i_size += BOGO_DIRENT_SIZE;
1804         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1805         d_instantiate(dentry, inode);
1806         dget(dentry);
1807         return 0;
1808 }
1809
1810 static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1811 {
1812         nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1813         return NULL;
1814 }
1815
1816 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1817 {
1818         struct page *page = NULL;
1819         int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1820         nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1821         return page;
1822 }
1823
1824 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1825 {
1826         if (!IS_ERR(nd_get_link(nd))) {
1827                 struct page *page = cookie;
1828                 kunmap(page);
1829                 mark_page_accessed(page);
1830                 page_cache_release(page);
1831         }
1832 }
1833
1834 static struct inode_operations shmem_symlink_inline_operations = {
1835         .readlink       = generic_readlink,
1836         .follow_link    = shmem_follow_link_inline,
1837 };
1838
1839 static struct inode_operations shmem_symlink_inode_operations = {
1840         .truncate       = shmem_truncate,
1841         .readlink       = generic_readlink,
1842         .follow_link    = shmem_follow_link,
1843         .put_link       = shmem_put_link,
1844 };
1845
1846 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
1847 {
1848         char *this_char, *value, *rest;
1849
1850         while ((this_char = strsep(&options, ",")) != NULL) {
1851                 if (!*this_char)
1852                         continue;
1853                 if ((value = strchr(this_char,'=')) != NULL) {
1854                         *value++ = 0;
1855                 } else {
1856                         printk(KERN_ERR
1857                             "tmpfs: No value for mount option '%s'\n",
1858                             this_char);
1859                         return 1;
1860                 }
1861
1862                 if (!strcmp(this_char,"size")) {
1863                         unsigned long long size;
1864                         size = memparse(value,&rest);
1865                         if (*rest == '%') {
1866                                 size <<= PAGE_SHIFT;
1867                                 size *= totalram_pages;
1868                                 do_div(size, 100);
1869                                 rest++;
1870                         }
1871                         if (*rest)
1872                                 goto bad_val;
1873                         *blocks = size >> PAGE_CACHE_SHIFT;
1874                 } else if (!strcmp(this_char,"nr_blocks")) {
1875                         *blocks = memparse(value,&rest);
1876                         if (*rest)
1877                                 goto bad_val;
1878                 } else if (!strcmp(this_char,"nr_inodes")) {
1879                         *inodes = memparse(value,&rest);
1880                         if (*rest)
1881                                 goto bad_val;
1882                 } else if (!strcmp(this_char,"mode")) {
1883                         if (!mode)
1884                                 continue;
1885                         *mode = simple_strtoul(value,&rest,8);
1886                         if (*rest)
1887                                 goto bad_val;
1888                 } else if (!strcmp(this_char,"uid")) {
1889                         if (!uid)
1890                                 continue;
1891                         *uid = simple_strtoul(value,&rest,0);
1892                         if (*rest)
1893                                 goto bad_val;
1894                 } else if (!strcmp(this_char,"gid")) {
1895                         if (!gid)
1896                                 continue;
1897                         *gid = simple_strtoul(value,&rest,0);
1898                         if (*rest)
1899                                 goto bad_val;
1900                 } else {
1901                         printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1902                                this_char);
1903                         return 1;
1904                 }
1905         }
1906         return 0;
1907
1908 bad_val:
1909         printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1910                value, this_char);
1911         return 1;
1912
1913 }
1914
1915 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1916 {
1917         struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1918         unsigned long max_blocks = sbinfo->max_blocks;
1919         unsigned long max_inodes = sbinfo->max_inodes;
1920         unsigned long blocks;
1921         unsigned long inodes;
1922         int error = -EINVAL;
1923
1924         if (shmem_parse_options(data, NULL, NULL, NULL,
1925                                 &max_blocks, &max_inodes))
1926                 return error;
1927
1928         spin_lock(&sbinfo->stat_lock);
1929         blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1930         inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1931         if (max_blocks < blocks)
1932                 goto out;
1933         if (max_inodes < inodes)
1934                 goto out;
1935         /*
1936          * Those tests also disallow limited->unlimited while any are in
1937          * use, so i_blocks will always be zero when max_blocks is zero;
1938          * but we must separately disallow unlimited->limited, because
1939          * in that case we have no record of how much is already in use.
1940          */
1941         if (max_blocks && !sbinfo->max_blocks)
1942                 goto out;
1943         if (max_inodes && !sbinfo->max_inodes)
1944                 goto out;
1945
1946         error = 0;
1947         sbinfo->max_blocks  = max_blocks;
1948         sbinfo->free_blocks = max_blocks - blocks;
1949         sbinfo->max_inodes  = max_inodes;
1950         sbinfo->free_inodes = max_inodes - inodes;
1951 out:
1952         spin_unlock(&sbinfo->stat_lock);
1953         return error;
1954 }
1955 #endif
1956
1957 static void shmem_put_super(struct super_block *sb)
1958 {
1959         kfree(sb->s_fs_info);
1960         sb->s_fs_info = NULL;
1961 }
1962
1963 static int shmem_fill_super(struct super_block *sb,
1964                             void *data, int silent)
1965 {
1966         struct inode *inode;
1967         struct dentry *root;
1968         int mode   = S_IRWXUGO | S_ISVTX;
1969         uid_t uid = current->fsuid;
1970         gid_t gid = current->fsgid;
1971         int err = -ENOMEM;
1972         struct shmem_sb_info *sbinfo;
1973         unsigned long blocks = 0;
1974         unsigned long inodes = 0;
1975
1976 #ifdef CONFIG_TMPFS
1977         /*
1978          * Per default we only allow half of the physical ram per
1979          * tmpfs instance, limiting inodes to one per page of lowmem;
1980          * but the internal instance is left unlimited.
1981          */
1982         if (!(sb->s_flags & MS_NOUSER)) {
1983                 blocks = totalram_pages / 2;
1984                 inodes = totalram_pages - totalhigh_pages;
1985                 if (inodes > blocks)
1986                         inodes = blocks;
1987                 if (shmem_parse_options(data, &mode, &uid, &gid,
1988                                         &blocks, &inodes))
1989                         return -EINVAL;
1990         }
1991 #else
1992         sb->s_flags |= MS_NOUSER;
1993 #endif
1994
1995         /* Round up to L1_CACHE_BYTES to resist false sharing */
1996         sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
1997                                 L1_CACHE_BYTES), GFP_KERNEL);
1998         if (!sbinfo)
1999                 return -ENOMEM;
2000
2001         spin_lock_init(&sbinfo->stat_lock);
2002         sbinfo->max_blocks = blocks;
2003         sbinfo->free_blocks = blocks;
2004         sbinfo->max_inodes = inodes;
2005         sbinfo->free_inodes = inodes;
2006
2007         sb->s_fs_info = sbinfo;
2008         sb->s_maxbytes = SHMEM_MAX_BYTES;
2009         sb->s_blocksize = PAGE_CACHE_SIZE;
2010         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2011         sb->s_magic = TMPFS_MAGIC;
2012         sb->s_op = &shmem_ops;
2013
2014         inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2015         if (!inode)
2016                 goto failed;
2017         inode->i_uid = uid;
2018         inode->i_gid = gid;
2019         root = d_alloc_root(inode);
2020         if (!root)
2021                 goto failed_iput;
2022         sb->s_root = root;
2023         return 0;
2024
2025 failed_iput:
2026         iput(inode);
2027 failed:
2028         shmem_put_super(sb);
2029         return err;
2030 }
2031
2032 static kmem_cache_t *shmem_inode_cachep;
2033
2034 static struct inode *shmem_alloc_inode(struct super_block *sb)
2035 {
2036         struct shmem_inode_info *p;
2037         p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2038         if (!p)
2039                 return NULL;
2040         return &p->vfs_inode;
2041 }
2042
2043 static void shmem_destroy_inode(struct inode *inode)
2044 {
2045         if ((inode->i_mode & S_IFMT) == S_IFREG) {
2046                 /* only struct inode is valid if it's an inline symlink */
2047                 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2048         }
2049         kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2050 }
2051
2052 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2053 {
2054         struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2055
2056         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2057             SLAB_CTOR_CONSTRUCTOR) {
2058                 inode_init_once(&p->vfs_inode);
2059         }
2060 }
2061
2062 static int init_inodecache(void)
2063 {
2064         shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2065                                 sizeof(struct shmem_inode_info),
2066                                 0, 0, init_once, NULL);
2067         if (shmem_inode_cachep == NULL)
2068                 return -ENOMEM;
2069         return 0;
2070 }
2071
2072 static void destroy_inodecache(void)
2073 {
2074         if (kmem_cache_destroy(shmem_inode_cachep))
2075                 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2076 }
2077
2078 static struct address_space_operations shmem_aops = {
2079         .writepage      = shmem_writepage,
2080         .set_page_dirty = __set_page_dirty_nobuffers,
2081 #ifdef CONFIG_TMPFS
2082         .prepare_write  = shmem_prepare_write,
2083         .commit_write   = simple_commit_write,
2084 #endif
2085 };
2086
2087 static struct file_operations shmem_file_operations = {
2088         .mmap           = shmem_mmap,
2089 #ifdef CONFIG_TMPFS
2090         .llseek         = generic_file_llseek,
2091         .read           = shmem_file_read,
2092         .write          = shmem_file_write,
2093         .fsync          = simple_sync_file,
2094         .sendfile       = shmem_file_sendfile,
2095 #endif
2096 };
2097
2098 static struct inode_operations shmem_inode_operations = {
2099         .truncate       = shmem_truncate,
2100         .setattr        = shmem_notify_change,
2101         .truncate_range = shmem_truncate_range,
2102 };
2103
2104 static struct inode_operations shmem_dir_inode_operations = {
2105 #ifdef CONFIG_TMPFS
2106         .create         = shmem_create,
2107         .lookup         = simple_lookup,
2108         .link           = shmem_link,
2109         .unlink         = shmem_unlink,
2110         .symlink        = shmem_symlink,
2111         .mkdir          = shmem_mkdir,
2112         .rmdir          = shmem_rmdir,
2113         .mknod          = shmem_mknod,
2114         .rename         = shmem_rename,
2115 #endif
2116 };
2117
2118 static struct super_operations shmem_ops = {
2119         .alloc_inode    = shmem_alloc_inode,
2120         .destroy_inode  = shmem_destroy_inode,
2121 #ifdef CONFIG_TMPFS
2122         .statfs         = shmem_statfs,
2123         .remount_fs     = shmem_remount_fs,
2124 #endif
2125         .delete_inode   = shmem_delete_inode,
2126         .drop_inode     = generic_delete_inode,
2127         .put_super      = shmem_put_super,
2128 };
2129
2130 static struct vm_operations_struct shmem_vm_ops = {
2131         .nopage         = shmem_nopage,
2132         .populate       = shmem_populate,
2133 #ifdef CONFIG_NUMA
2134         .set_policy     = shmem_set_policy,
2135         .get_policy     = shmem_get_policy,
2136 #endif
2137 };
2138
2139
2140 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2141         int flags, const char *dev_name, void *data)
2142 {
2143         return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2144 }
2145
2146 static struct file_system_type tmpfs_fs_type = {
2147         .owner          = THIS_MODULE,
2148         .name           = "tmpfs",
2149         .get_sb         = shmem_get_sb,
2150         .kill_sb        = kill_litter_super,
2151 };
2152 static struct vfsmount *shm_mnt;
2153
2154 static int __init init_tmpfs(void)
2155 {
2156         int error;
2157
2158         error = init_inodecache();
2159         if (error)
2160                 goto out3;
2161
2162         error = register_filesystem(&tmpfs_fs_type);
2163         if (error) {
2164                 printk(KERN_ERR "Could not register tmpfs\n");
2165                 goto out2;
2166         }
2167 #ifdef CONFIG_TMPFS
2168         devfs_mk_dir("shm");
2169 #endif
2170         shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2171                                 tmpfs_fs_type.name, NULL);
2172         if (IS_ERR(shm_mnt)) {
2173                 error = PTR_ERR(shm_mnt);
2174                 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2175                 goto out1;
2176         }
2177         return 0;
2178
2179 out1:
2180         unregister_filesystem(&tmpfs_fs_type);
2181 out2:
2182         destroy_inodecache();
2183 out3:
2184         shm_mnt = ERR_PTR(error);
2185         return error;
2186 }
2187 module_init(init_tmpfs)
2188
2189 /*
2190  * shmem_file_setup - get an unlinked file living in tmpfs
2191  *
2192  * @name: name for dentry (to be seen in /proc/<pid>/maps
2193  * @size: size to be set for the file
2194  *
2195  */
2196 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2197 {
2198         int error;
2199         struct file *file;
2200         struct inode *inode;
2201         struct dentry *dentry, *root;
2202         struct qstr this;
2203
2204         if (IS_ERR(shm_mnt))
2205                 return (void *)shm_mnt;
2206
2207         if (size < 0 || size > SHMEM_MAX_BYTES)
2208                 return ERR_PTR(-EINVAL);
2209
2210         if (shmem_acct_size(flags, size))
2211                 return ERR_PTR(-ENOMEM);
2212
2213         error = -ENOMEM;
2214         this.name = name;
2215         this.len = strlen(name);
2216         this.hash = 0; /* will go */
2217         root = shm_mnt->mnt_root;
2218         dentry = d_alloc(root, &this);
2219         if (!dentry)
2220                 goto put_memory;
2221
2222         error = -ENFILE;
2223         file = get_empty_filp();
2224         if (!file)
2225                 goto put_dentry;
2226
2227         error = -ENOSPC;
2228         inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2229         if (!inode)
2230                 goto close_file;
2231
2232         SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2233         d_instantiate(dentry, inode);
2234         inode->i_size = size;
2235         inode->i_nlink = 0;     /* It is unlinked */
2236         file->f_vfsmnt = mntget(shm_mnt);
2237         file->f_dentry = dentry;
2238         file->f_mapping = inode->i_mapping;
2239         file->f_op = &shmem_file_operations;
2240         file->f_mode = FMODE_WRITE | FMODE_READ;
2241         return file;
2242
2243 close_file:
2244         put_filp(file);
2245 put_dentry:
2246         dput(dentry);
2247 put_memory:
2248         shmem_unacct_size(flags, size);
2249         return ERR_PTR(error);
2250 }
2251
2252 /*
2253  * shmem_zero_setup - setup a shared anonymous mapping
2254  *
2255  * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2256  */
2257 int shmem_zero_setup(struct vm_area_struct *vma)
2258 {
2259         struct file *file;
2260         loff_t size = vma->vm_end - vma->vm_start;
2261
2262         file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2263         if (IS_ERR(file))
2264                 return PTR_ERR(file);
2265
2266         if (vma->vm_file)
2267                 fput(vma->vm_file);
2268         vma->vm_file = file;
2269         vma->vm_ops = &shmem_vm_ops;
2270         return 0;
2271 }