2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2004 Hugh Dickins.
10 * Copyright (C) 2002-2004 VERITAS Software Corporation.
11 * Copyright (C) 2004 Andi Kleen, SuSE Labs
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>
17 * This file is released under the GPL.
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.
26 #include <linux/config.h>
27 #include <linux/module.h>
28 #include <linux/init.h>
29 #include <linux/devfs_fs_kernel.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 <linux/xattr.h>
49 #include <asm/uaccess.h>
50 #include <asm/div64.h>
51 #include <asm/pgtable.h>
53 /* This magic number is used in glibc for posix shared memory */
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)
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)
62 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
64 /* info->flags needs VM_flags to handle pagein/truncate races efficiently */
65 #define SHMEM_PAGEIN VM_READ
66 #define SHMEM_TRUNCATE VM_WRITE
68 /* Definition to limit shmem_truncate's steps between cond_rescheds */
69 #define LATENCY_LIMIT 64
71 /* Pretend that each entry is of this size in directory's i_size */
72 #define BOGO_DIRENT_SIZE 20
74 /* Keep swapped page count in private field of indirect struct page */
75 #define nr_swapped private
77 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
79 SGP_QUICK, /* don't try more than file page cache lookup */
80 SGP_READ, /* don't exceed i_size, don't allocate page */
81 SGP_CACHE, /* don't exceed i_size, may allocate page */
82 SGP_WRITE, /* may exceed i_size, may allocate page */
85 static int shmem_getpage(struct inode *inode, unsigned long idx,
86 struct page **pagep, enum sgp_type sgp, int *type);
88 static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
91 * The above definition of ENTRIES_PER_PAGE, and the use of
92 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
93 * might be reconsidered if it ever diverges from PAGE_SIZE.
95 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
98 static inline void shmem_dir_free(struct page *page)
100 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
103 static struct page **shmem_dir_map(struct page *page)
105 return (struct page **)kmap_atomic(page, KM_USER0);
108 static inline void shmem_dir_unmap(struct page **dir)
110 kunmap_atomic(dir, KM_USER0);
113 static swp_entry_t *shmem_swp_map(struct page *page)
115 return (swp_entry_t *)kmap_atomic(page, KM_USER1);
118 static inline void shmem_swp_balance_unmap(void)
121 * When passing a pointer to an i_direct entry, to code which
122 * also handles indirect entries and so will shmem_swp_unmap,
123 * we must arrange for the preempt count to remain in balance.
124 * What kmap_atomic of a lowmem page does depends on config
125 * and architecture, so pretend to kmap_atomic some lowmem page.
127 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
130 static inline void shmem_swp_unmap(swp_entry_t *entry)
132 kunmap_atomic(entry, KM_USER1);
135 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
137 return sb->s_fs_info;
141 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
142 * for shared memory and for shared anonymous (/dev/zero) mappings
143 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
144 * consistent with the pre-accounting of private mappings ...
146 static inline int shmem_acct_size(unsigned long flags, loff_t size)
148 return (flags & VM_ACCOUNT)?
149 security_vm_enough_memory(VM_ACCT(size)): 0;
152 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
154 if (flags & VM_ACCOUNT)
155 vm_unacct_memory(VM_ACCT(size));
159 * ... whereas tmpfs objects are accounted incrementally as
160 * pages are allocated, in order to allow huge sparse files.
161 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
162 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
164 static inline int shmem_acct_block(unsigned long flags)
166 return (flags & VM_ACCOUNT)?
167 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
170 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
172 if (!(flags & VM_ACCOUNT))
173 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
176 static struct super_operations shmem_ops;
177 static struct address_space_operations shmem_aops;
178 static struct file_operations shmem_file_operations;
179 static struct inode_operations shmem_inode_operations;
180 static struct inode_operations shmem_dir_inode_operations;
181 static struct inode_operations shmem_special_inode_operations;
182 static struct vm_operations_struct shmem_vm_ops;
184 static struct backing_dev_info shmem_backing_dev_info = {
185 .ra_pages = 0, /* No readahead */
186 .memory_backed = 1, /* Does not contribute to dirty memory */
187 .unplug_io_fn = default_unplug_io_fn,
190 static LIST_HEAD(shmem_swaplist);
191 static spinlock_t shmem_swaplist_lock = SPIN_LOCK_UNLOCKED;
193 static void shmem_free_blocks(struct inode *inode, long pages)
195 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
197 spin_lock(&sbinfo->stat_lock);
198 sbinfo->free_blocks += pages;
199 inode->i_blocks -= pages*BLOCKS_PER_PAGE;
200 spin_unlock(&sbinfo->stat_lock);
205 * shmem_recalc_inode - recalculate the size of an inode
207 * @inode: inode to recalc
209 * We have to calculate the free blocks since the mm can drop
210 * undirtied hole pages behind our back.
212 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
213 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
215 * It has to be called with the spinlock held.
217 static void shmem_recalc_inode(struct inode *inode)
219 struct shmem_inode_info *info = SHMEM_I(inode);
222 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
224 info->alloced -= freed;
225 shmem_unacct_blocks(info->flags, freed);
226 shmem_free_blocks(inode, freed);
231 * shmem_swp_entry - find the swap vector position in the info structure
233 * @info: info structure for the inode
234 * @index: index of the page to find
235 * @page: optional page to add to the structure. Has to be preset to
238 * If there is no space allocated yet it will return NULL when
239 * page is NULL, else it will use the page for the needed block,
240 * setting it to NULL on return to indicate that it has been used.
242 * The swap vector is organized the following way:
244 * There are SHMEM_NR_DIRECT entries directly stored in the
245 * shmem_inode_info structure. So small files do not need an addional
248 * For pages with index > SHMEM_NR_DIRECT there is the pointer
249 * i_indirect which points to a page which holds in the first half
250 * doubly indirect blocks, in the second half triple indirect blocks:
252 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
253 * following layout (for SHMEM_NR_DIRECT == 16):
255 * i_indirect -> dir --> 16-19
268 static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
270 unsigned long offset;
274 if (index < SHMEM_NR_DIRECT) {
275 shmem_swp_balance_unmap();
276 return info->i_direct+index;
278 if (!info->i_indirect) {
280 info->i_indirect = *page;
283 return NULL; /* need another page */
286 index -= SHMEM_NR_DIRECT;
287 offset = index % ENTRIES_PER_PAGE;
288 index /= ENTRIES_PER_PAGE;
289 dir = shmem_dir_map(info->i_indirect);
291 if (index >= ENTRIES_PER_PAGE/2) {
292 index -= ENTRIES_PER_PAGE/2;
293 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
294 index %= ENTRIES_PER_PAGE;
301 shmem_dir_unmap(dir);
302 return NULL; /* need another page */
304 shmem_dir_unmap(dir);
305 dir = shmem_dir_map(subdir);
311 if (!page || !(subdir = *page)) {
312 shmem_dir_unmap(dir);
313 return NULL; /* need a page */
318 shmem_dir_unmap(dir);
319 return shmem_swp_map(subdir) + offset;
322 static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
324 long incdec = value? 1: -1;
327 info->swapped += incdec;
328 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
329 kmap_atomic_to_page(entry)->nr_swapped += incdec;
333 * shmem_swp_alloc - get the position of the swap entry for the page.
334 * If it does not exist allocate the entry.
336 * @info: info structure for the inode
337 * @index: index of the page to find
338 * @sgp: check and recheck i_size? skip allocation?
340 static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
342 struct inode *inode = &info->vfs_inode;
343 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
344 struct page *page = NULL;
347 if (sgp != SGP_WRITE &&
348 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
349 return ERR_PTR(-EINVAL);
351 while (!(entry = shmem_swp_entry(info, index, &page))) {
353 return shmem_swp_map(ZERO_PAGE(0));
355 * Test free_blocks against 1 not 0, since we have 1 data
356 * page (and perhaps indirect index pages) yet to allocate:
357 * a waste to allocate index if we cannot allocate data.
360 spin_lock(&sbinfo->stat_lock);
361 if (sbinfo->free_blocks <= 1) {
362 spin_unlock(&sbinfo->stat_lock);
363 return ERR_PTR(-ENOSPC);
365 sbinfo->free_blocks--;
366 inode->i_blocks += BLOCKS_PER_PAGE;
367 spin_unlock(&sbinfo->stat_lock);
370 spin_unlock(&info->lock);
371 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
373 clear_highpage(page);
374 page->nr_swapped = 0;
376 spin_lock(&info->lock);
379 shmem_free_blocks(inode, 1);
380 return ERR_PTR(-ENOMEM);
382 if (sgp != SGP_WRITE &&
383 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
384 entry = ERR_PTR(-EINVAL);
387 if (info->next_index <= index)
388 info->next_index = index + 1;
391 /* another task gave its page, or truncated the file */
392 shmem_free_blocks(inode, 1);
393 shmem_dir_free(page);
395 if (info->next_index <= index && !IS_ERR(entry))
396 info->next_index = index + 1;
401 * shmem_free_swp - free some swap entries in a directory
403 * @dir: pointer to the directory
404 * @edir: pointer after last entry of the directory
406 static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
411 for (ptr = dir; ptr < edir; ptr++) {
413 free_swap_and_cache(*ptr);
414 *ptr = (swp_entry_t){0};
421 static int shmem_map_and_free_swp(struct page *subdir,
422 int offset, int limit, struct page ***dir)
427 ptr = shmem_swp_map(subdir);
428 for (; offset < limit; offset += LATENCY_LIMIT) {
429 int size = limit - offset;
430 if (size > LATENCY_LIMIT)
431 size = LATENCY_LIMIT;
432 freed += shmem_free_swp(ptr+offset, ptr+offset+size);
433 if (need_resched()) {
434 shmem_swp_unmap(ptr);
436 shmem_dir_unmap(*dir);
440 ptr = shmem_swp_map(subdir);
443 shmem_swp_unmap(ptr);
447 static void shmem_free_pages(struct list_head *next)
453 page = container_of(next, struct page, lru);
455 shmem_dir_free(page);
457 if (freed >= LATENCY_LIMIT) {
464 static void shmem_truncate(struct inode *inode)
466 struct shmem_inode_info *info = SHMEM_I(inode);
471 unsigned long diroff;
477 LIST_HEAD(pages_to_free);
478 long nr_pages_to_free = 0;
479 long nr_swaps_freed = 0;
483 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
484 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
485 if (idx >= info->next_index)
488 spin_lock(&info->lock);
489 info->flags |= SHMEM_TRUNCATE;
490 limit = info->next_index;
491 info->next_index = idx;
492 topdir = info->i_indirect;
493 if (topdir && idx <= SHMEM_NR_DIRECT) {
494 info->i_indirect = NULL;
496 list_add(&topdir->lru, &pages_to_free);
498 spin_unlock(&info->lock);
500 if (info->swapped && idx < SHMEM_NR_DIRECT) {
501 ptr = info->i_direct;
503 if (size > SHMEM_NR_DIRECT)
504 size = SHMEM_NR_DIRECT;
505 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
510 BUG_ON(limit <= SHMEM_NR_DIRECT);
511 limit -= SHMEM_NR_DIRECT;
512 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
513 offset = idx % ENTRIES_PER_PAGE;
516 dir = shmem_dir_map(topdir);
517 stage = ENTRIES_PER_PAGEPAGE/2;
518 if (idx < ENTRIES_PER_PAGEPAGE/2) {
520 diroff = idx/ENTRIES_PER_PAGE;
522 dir += ENTRIES_PER_PAGE/2;
523 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
525 stage += ENTRIES_PER_PAGEPAGE;
528 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
529 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
530 if (!diroff && !offset) {
533 list_add(&middir->lru, &pages_to_free);
535 shmem_dir_unmap(dir);
536 dir = shmem_dir_map(middir);
544 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
545 if (unlikely(idx == stage)) {
546 shmem_dir_unmap(dir);
547 dir = shmem_dir_map(topdir) +
548 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
551 idx += ENTRIES_PER_PAGEPAGE;
555 stage = idx + ENTRIES_PER_PAGEPAGE;
559 list_add(&middir->lru, &pages_to_free);
560 shmem_dir_unmap(dir);
562 dir = shmem_dir_map(middir);
565 subdir = dir[diroff];
566 if (subdir && subdir->nr_swapped) {
568 if (size > ENTRIES_PER_PAGE)
569 size = ENTRIES_PER_PAGE;
570 freed = shmem_map_and_free_swp(subdir,
573 dir = shmem_dir_map(middir);
574 nr_swaps_freed += freed;
576 spin_lock(&info->lock);
577 subdir->nr_swapped -= freed;
579 spin_unlock(&info->lock);
580 BUG_ON(subdir->nr_swapped > offset);
587 list_add(&subdir->lru, &pages_to_free);
591 shmem_dir_unmap(dir);
593 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
595 * Call truncate_inode_pages again: racing shmem_unuse_inode
596 * may have swizzled a page in from swap since vmtruncate or
597 * generic_delete_inode did it, before we lowered next_index.
598 * Also, though shmem_getpage checks i_size before adding to
599 * cache, no recheck after: so fix the narrow window there too.
601 truncate_inode_pages(inode->i_mapping, inode->i_size);
604 spin_lock(&info->lock);
605 info->flags &= ~SHMEM_TRUNCATE;
606 info->swapped -= nr_swaps_freed;
607 if (nr_pages_to_free)
608 shmem_free_blocks(inode, nr_pages_to_free);
609 shmem_recalc_inode(inode);
610 spin_unlock(&info->lock);
613 * Empty swap vector directory pages to be freed?
615 if (!list_empty(&pages_to_free)) {
616 pages_to_free.prev->next = NULL;
617 shmem_free_pages(pages_to_free.next);
621 static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
623 struct inode *inode = dentry->d_inode;
624 struct page *page = NULL;
627 if (attr->ia_valid & ATTR_SIZE) {
628 if (attr->ia_size < inode->i_size) {
630 * If truncating down to a partial page, then
631 * if that page is already allocated, hold it
632 * in memory until the truncation is over, so
633 * truncate_partial_page cannnot miss it were
634 * it assigned to swap.
636 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
637 (void) shmem_getpage(inode,
638 attr->ia_size>>PAGE_CACHE_SHIFT,
639 &page, SGP_READ, NULL);
642 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
643 * detect if any pages might have been added to cache
644 * after truncate_inode_pages. But we needn't bother
645 * if it's being fully truncated to zero-length: the
646 * nrpages check is efficient enough in that case.
649 struct shmem_inode_info *info = SHMEM_I(inode);
650 spin_lock(&info->lock);
651 info->flags &= ~SHMEM_PAGEIN;
652 spin_unlock(&info->lock);
657 error = inode_change_ok(inode, attr);
659 error = inode_setattr(inode, attr);
661 page_cache_release(page);
665 static void shmem_delete_inode(struct inode *inode)
667 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
668 struct shmem_inode_info *info = SHMEM_I(inode);
670 if (inode->i_op->truncate == shmem_truncate) {
671 shmem_unacct_size(info->flags, inode->i_size);
673 shmem_truncate(inode);
674 if (!list_empty(&info->swaplist)) {
675 spin_lock(&shmem_swaplist_lock);
676 list_del_init(&info->swaplist);
677 spin_unlock(&shmem_swaplist_lock);
681 BUG_ON(inode->i_blocks);
682 spin_lock(&sbinfo->stat_lock);
683 sbinfo->free_inodes++;
684 spin_unlock(&sbinfo->stat_lock);
689 static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
693 for (ptr = dir; ptr < edir; ptr++) {
694 if (ptr->val == entry.val)
700 static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
713 ptr = info->i_direct;
714 spin_lock(&info->lock);
715 limit = info->next_index;
717 if (size > SHMEM_NR_DIRECT)
718 size = SHMEM_NR_DIRECT;
719 offset = shmem_find_swp(entry, ptr, ptr+size);
721 shmem_swp_balance_unmap();
724 if (!info->i_indirect)
727 dir = shmem_dir_map(info->i_indirect);
728 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
730 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
731 if (unlikely(idx == stage)) {
732 shmem_dir_unmap(dir-1);
733 dir = shmem_dir_map(info->i_indirect) +
734 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
737 idx += ENTRIES_PER_PAGEPAGE;
741 stage = idx + ENTRIES_PER_PAGEPAGE;
743 shmem_dir_unmap(dir);
744 dir = shmem_dir_map(subdir);
747 if (subdir && subdir->nr_swapped) {
748 ptr = shmem_swp_map(subdir);
750 if (size > ENTRIES_PER_PAGE)
751 size = ENTRIES_PER_PAGE;
752 offset = shmem_find_swp(entry, ptr, ptr+size);
754 shmem_dir_unmap(dir);
757 shmem_swp_unmap(ptr);
761 shmem_dir_unmap(dir-1);
763 spin_unlock(&info->lock);
767 inode = &info->vfs_inode;
768 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
769 info->flags |= SHMEM_PAGEIN;
770 shmem_swp_set(info, ptr + offset, 0);
772 shmem_swp_unmap(ptr);
773 spin_unlock(&info->lock);
775 * Decrement swap count even when the entry is left behind:
776 * try_to_unuse will skip over mms, then reincrement count.
783 * shmem_unuse() search for an eventually swapped out shmem page.
785 int shmem_unuse(swp_entry_t entry, struct page *page)
787 struct list_head *p, *next;
788 struct shmem_inode_info *info;
791 spin_lock(&shmem_swaplist_lock);
792 list_for_each_safe(p, next, &shmem_swaplist) {
793 info = list_entry(p, struct shmem_inode_info, swaplist);
795 list_del_init(&info->swaplist);
796 else if (shmem_unuse_inode(info, entry, page)) {
797 /* move head to start search for next from here */
798 list_move_tail(&shmem_swaplist, &info->swaplist);
803 spin_unlock(&shmem_swaplist_lock);
808 * Move the page from the page cache to the swap cache.
810 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
812 struct shmem_inode_info *info;
813 swp_entry_t *entry, swap;
814 struct address_space *mapping;
818 BUG_ON(!PageLocked(page));
819 BUG_ON(page_mapped(page));
821 mapping = page->mapping;
823 inode = mapping->host;
824 info = SHMEM_I(inode);
825 if (info->flags & VM_LOCKED)
827 swap = get_swap_page();
831 spin_lock(&info->lock);
832 shmem_recalc_inode(inode);
833 if (index >= info->next_index) {
834 BUG_ON(!(info->flags & SHMEM_TRUNCATE));
837 entry = shmem_swp_entry(info, index, NULL);
841 if (move_to_swap_cache(page, swap) == 0) {
842 shmem_swp_set(info, entry, swap.val);
843 shmem_swp_unmap(entry);
844 spin_unlock(&info->lock);
845 if (list_empty(&info->swaplist)) {
846 spin_lock(&shmem_swaplist_lock);
847 /* move instead of add in case we're racing */
848 list_move_tail(&info->swaplist, &shmem_swaplist);
849 spin_unlock(&shmem_swaplist_lock);
855 shmem_swp_unmap(entry);
857 spin_unlock(&info->lock);
860 set_page_dirty(page);
861 return WRITEPAGE_ACTIVATE; /* Return with the page locked */
865 static struct page *shmem_swapin_async(struct shared_policy *p,
866 swp_entry_t entry, unsigned long idx)
869 struct vm_area_struct pvma;
871 /* Create a pseudo vma that just contains the policy */
872 memset(&pvma, 0, sizeof(struct vm_area_struct));
873 pvma.vm_end = PAGE_SIZE;
875 pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
876 page = read_swap_cache_async(entry, &pvma, 0);
877 mpol_free(pvma.vm_policy);
881 struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
884 struct shared_policy *p = &info->policy;
887 unsigned long offset;
889 num = valid_swaphandles(entry, &offset);
890 for (i = 0; i < num; offset++, i++) {
891 page = shmem_swapin_async(p,
892 swp_entry(swp_type(entry), offset), idx);
895 page_cache_release(page);
897 lru_add_drain(); /* Push any new pages onto the LRU now */
898 return shmem_swapin_async(p, entry, idx);
902 shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
905 struct vm_area_struct pvma;
908 memset(&pvma, 0, sizeof(struct vm_area_struct));
909 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
911 pvma.vm_end = PAGE_SIZE;
912 page = alloc_page_vma(gfp, &pvma, 0);
913 mpol_free(pvma.vm_policy);
917 static inline struct page *
918 shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
920 swapin_readahead(entry, 0, NULL);
921 return read_swap_cache_async(entry, NULL, 0);
924 static inline struct page *
925 shmem_alloc_page(unsigned long gfp,struct shmem_inode_info *info,
928 return alloc_page(gfp);
933 * shmem_getpage - either get the page from swap or allocate a new one
935 * If we allocate a new one we do not mark it dirty. That's up to the
936 * vm. If we swap it in we mark it dirty since we also free the swap
937 * entry since a page cannot live in both the swap and page cache
939 static int shmem_getpage(struct inode *inode, unsigned long idx,
940 struct page **pagep, enum sgp_type sgp, int *type)
942 struct address_space *mapping = inode->i_mapping;
943 struct shmem_inode_info *info = SHMEM_I(inode);
944 struct shmem_sb_info *sbinfo;
945 struct page *filepage = *pagep;
946 struct page *swappage;
951 if (idx >= SHMEM_MAX_INDEX)
954 * Normally, filepage is NULL on entry, and either found
955 * uptodate immediately, or allocated and zeroed, or read
956 * in under swappage, which is then assigned to filepage.
957 * But shmem_prepare_write passes in a locked filepage,
958 * which may be found not uptodate by other callers too,
959 * and may need to be copied from the swappage read in.
963 filepage = find_lock_page(mapping, idx);
964 if (filepage && PageUptodate(filepage))
967 if (sgp == SGP_QUICK)
970 spin_lock(&info->lock);
971 shmem_recalc_inode(inode);
972 entry = shmem_swp_alloc(info, idx, sgp);
974 spin_unlock(&info->lock);
975 error = PTR_ERR(entry);
981 /* Look it up and read it in.. */
982 swappage = lookup_swap_cache(swap);
984 shmem_swp_unmap(entry);
985 spin_unlock(&info->lock);
986 /* here we actually do the io */
987 if (type && *type == VM_FAULT_MINOR) {
988 inc_page_state(pgmajfault);
989 *type = VM_FAULT_MAJOR;
991 swappage = shmem_swapin(info, swap, idx);
993 spin_lock(&info->lock);
994 entry = shmem_swp_alloc(info, idx, sgp);
996 error = PTR_ERR(entry);
998 if (entry->val == swap.val)
1000 shmem_swp_unmap(entry);
1002 spin_unlock(&info->lock);
1007 wait_on_page_locked(swappage);
1008 page_cache_release(swappage);
1012 /* We have to do this with page locked to prevent races */
1013 if (TestSetPageLocked(swappage)) {
1014 shmem_swp_unmap(entry);
1015 spin_unlock(&info->lock);
1016 wait_on_page_locked(swappage);
1017 page_cache_release(swappage);
1020 if (PageWriteback(swappage)) {
1021 shmem_swp_unmap(entry);
1022 spin_unlock(&info->lock);
1023 wait_on_page_writeback(swappage);
1024 unlock_page(swappage);
1025 page_cache_release(swappage);
1028 if (!PageUptodate(swappage)) {
1029 shmem_swp_unmap(entry);
1030 spin_unlock(&info->lock);
1031 unlock_page(swappage);
1032 page_cache_release(swappage);
1038 shmem_swp_set(info, entry, 0);
1039 shmem_swp_unmap(entry);
1040 delete_from_swap_cache(swappage);
1041 spin_unlock(&info->lock);
1042 copy_highpage(filepage, swappage);
1043 unlock_page(swappage);
1044 page_cache_release(swappage);
1045 flush_dcache_page(filepage);
1046 SetPageUptodate(filepage);
1047 set_page_dirty(filepage);
1049 } else if (!(error = move_from_swap_cache(
1050 swappage, idx, mapping))) {
1051 info->flags |= SHMEM_PAGEIN;
1052 shmem_swp_set(info, entry, 0);
1053 shmem_swp_unmap(entry);
1054 spin_unlock(&info->lock);
1055 filepage = swappage;
1058 shmem_swp_unmap(entry);
1059 spin_unlock(&info->lock);
1060 unlock_page(swappage);
1061 page_cache_release(swappage);
1062 if (error == -ENOMEM) {
1063 /* let kswapd refresh zone for GFP_ATOMICs */
1064 blk_congestion_wait(WRITE, HZ/50);
1068 } else if (sgp == SGP_READ && !filepage) {
1069 shmem_swp_unmap(entry);
1070 filepage = find_get_page(mapping, idx);
1072 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
1073 spin_unlock(&info->lock);
1074 wait_on_page_locked(filepage);
1075 page_cache_release(filepage);
1079 spin_unlock(&info->lock);
1081 shmem_swp_unmap(entry);
1082 sbinfo = SHMEM_SB(inode->i_sb);
1084 spin_lock(&sbinfo->stat_lock);
1085 if (sbinfo->free_blocks == 0 ||
1086 shmem_acct_block(info->flags)) {
1087 spin_unlock(&sbinfo->stat_lock);
1088 spin_unlock(&info->lock);
1092 sbinfo->free_blocks--;
1093 inode->i_blocks += BLOCKS_PER_PAGE;
1094 spin_unlock(&sbinfo->stat_lock);
1095 } else if (shmem_acct_block(info->flags)) {
1096 spin_unlock(&info->lock);
1102 spin_unlock(&info->lock);
1103 filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
1107 shmem_unacct_blocks(info->flags, 1);
1108 shmem_free_blocks(inode, 1);
1113 spin_lock(&info->lock);
1114 entry = shmem_swp_alloc(info, idx, sgp);
1116 error = PTR_ERR(entry);
1119 shmem_swp_unmap(entry);
1121 if (error || swap.val || 0 != add_to_page_cache_lru(
1122 filepage, mapping, idx, GFP_ATOMIC)) {
1123 spin_unlock(&info->lock);
1124 page_cache_release(filepage);
1125 shmem_unacct_blocks(info->flags, 1);
1126 shmem_free_blocks(inode, 1);
1132 info->flags |= SHMEM_PAGEIN;
1136 spin_unlock(&info->lock);
1137 clear_highpage(filepage);
1138 flush_dcache_page(filepage);
1139 SetPageUptodate(filepage);
1142 if (*pagep != filepage) {
1143 unlock_page(filepage);
1149 if (*pagep != filepage) {
1150 unlock_page(filepage);
1151 page_cache_release(filepage);
1156 struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
1158 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1159 struct page *page = NULL;
1163 idx = (address - vma->vm_start) >> PAGE_SHIFT;
1164 idx += vma->vm_pgoff;
1165 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
1167 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
1169 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
1171 mark_page_accessed(page);
1175 static int shmem_populate(struct vm_area_struct *vma,
1176 unsigned long addr, unsigned long len,
1177 pgprot_t prot, unsigned long pgoff, int nonblock)
1179 struct inode *inode = vma->vm_file->f_dentry->d_inode;
1180 struct mm_struct *mm = vma->vm_mm;
1181 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
1184 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
1185 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
1188 while ((long) len > 0) {
1189 struct page *page = NULL;
1192 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
1194 err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
1198 mark_page_accessed(page);
1199 err = install_page(mm, vma, addr, page, prot);
1201 page_cache_release(page);
1204 } else if (nonblock) {
1205 err = install_file_pte(mm, vma, addr, pgoff, prot);
1218 int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
1220 struct inode *i = vma->vm_file->f_dentry->d_inode;
1221 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
1225 shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
1227 struct inode *i = vma->vm_file->f_dentry->d_inode;
1230 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1231 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
1235 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1237 struct inode *inode = file->f_dentry->d_inode;
1238 struct shmem_inode_info *info = SHMEM_I(inode);
1239 int retval = -ENOMEM;
1241 spin_lock(&info->lock);
1242 if (lock && !(info->flags & VM_LOCKED)) {
1243 if (!user_shm_lock(inode->i_size, user))
1245 info->flags |= VM_LOCKED;
1247 if (!lock && (info->flags & VM_LOCKED) && user) {
1248 user_shm_unlock(inode->i_size, user);
1249 info->flags &= ~VM_LOCKED;
1253 spin_unlock(&info->lock);
1257 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1259 file_accessed(file);
1260 vma->vm_ops = &shmem_vm_ops;
1264 static struct inode *
1265 shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
1267 struct inode *inode;
1268 struct shmem_inode_info *info;
1269 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1272 spin_lock(&sbinfo->stat_lock);
1273 if (!sbinfo->free_inodes) {
1274 spin_unlock(&sbinfo->stat_lock);
1277 sbinfo->free_inodes--;
1278 spin_unlock(&sbinfo->stat_lock);
1281 inode = new_inode(sb);
1283 inode->i_mode = mode;
1284 inode->i_uid = current->fsuid;
1285 inode->i_gid = current->fsgid;
1286 inode->i_blksize = PAGE_CACHE_SIZE;
1287 inode->i_blocks = 0;
1288 inode->i_mapping->a_ops = &shmem_aops;
1289 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1290 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1291 info = SHMEM_I(inode);
1292 memset(info, 0, (char *)inode - (char *)info);
1293 spin_lock_init(&info->lock);
1294 INIT_LIST_HEAD(&info->swaplist);
1296 switch (mode & S_IFMT) {
1298 inode->i_op = &shmem_special_inode_operations;
1299 init_special_inode(inode, mode, dev);
1302 inode->i_op = &shmem_inode_operations;
1303 inode->i_fop = &shmem_file_operations;
1304 mpol_shared_policy_init(&info->policy);
1308 /* Some things misbehave if size == 0 on a directory */
1309 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1310 inode->i_op = &shmem_dir_inode_operations;
1311 inode->i_fop = &simple_dir_operations;
1315 * Must not load anything in the rbtree,
1316 * mpol_free_shared_policy will not be called.
1318 mpol_shared_policy_init(&info->policy);
1321 } else if (sbinfo) {
1322 spin_lock(&sbinfo->stat_lock);
1323 sbinfo->free_inodes++;
1324 spin_unlock(&sbinfo->stat_lock);
1331 static int shmem_set_size(struct shmem_sb_info *sbinfo,
1332 unsigned long max_blocks, unsigned long max_inodes)
1335 unsigned long blocks, inodes;
1337 spin_lock(&sbinfo->stat_lock);
1338 blocks = sbinfo->max_blocks - sbinfo->free_blocks;
1339 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
1341 if (max_blocks < blocks)
1343 if (max_inodes < inodes)
1346 sbinfo->max_blocks = max_blocks;
1347 sbinfo->free_blocks = max_blocks - blocks;
1348 sbinfo->max_inodes = max_inodes;
1349 sbinfo->free_inodes = max_inodes - inodes;
1351 spin_unlock(&sbinfo->stat_lock);
1355 static struct inode_operations shmem_symlink_inode_operations;
1356 static struct inode_operations shmem_symlink_inline_operations;
1359 * Normally tmpfs makes no use of shmem_prepare_write, but it
1360 * lets a tmpfs file be used read-write below the loop driver.
1363 shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
1365 struct inode *inode = page->mapping->host;
1366 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
1370 shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
1372 struct inode *inode = file->f_dentry->d_inode;
1374 unsigned long written;
1377 if ((ssize_t) count < 0)
1380 if (!access_ok(VERIFY_READ, buf, count))
1383 down(&inode->i_sem);
1388 err = generic_write_checks(file, &pos, &count, 0);
1392 err = remove_suid(file->f_dentry);
1396 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
1399 struct page *page = NULL;
1400 unsigned long bytes, index, offset;
1404 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
1405 index = pos >> PAGE_CACHE_SHIFT;
1406 bytes = PAGE_CACHE_SIZE - offset;
1411 * We don't hold page lock across copy from user -
1412 * what would it guard against? - so no deadlock here.
1413 * But it still may be a good idea to prefault below.
1416 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
1421 if (PageHighMem(page)) {
1422 volatile unsigned char dummy;
1423 __get_user(dummy, buf);
1424 __get_user(dummy, buf + bytes - 1);
1426 kaddr = kmap_atomic(page, KM_USER0);
1427 left = __copy_from_user_inatomic(kaddr + offset,
1429 kunmap_atomic(kaddr, KM_USER0);
1433 left = __copy_from_user(kaddr + offset, buf, bytes);
1441 if (pos > inode->i_size)
1442 i_size_write(inode, pos);
1444 flush_dcache_page(page);
1445 set_page_dirty(page);
1446 mark_page_accessed(page);
1447 page_cache_release(page);
1457 * Our dirty pages are not counted in nr_dirty,
1458 * and we do not attempt to balance dirty pages.
1472 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1474 struct inode *inode = filp->f_dentry->d_inode;
1475 struct address_space *mapping = inode->i_mapping;
1476 unsigned long index, offset;
1478 index = *ppos >> PAGE_CACHE_SHIFT;
1479 offset = *ppos & ~PAGE_CACHE_MASK;
1482 struct page *page = NULL;
1483 unsigned long end_index, nr, ret;
1484 loff_t i_size = i_size_read(inode);
1486 end_index = i_size >> PAGE_CACHE_SHIFT;
1487 if (index > end_index)
1489 if (index == end_index) {
1490 nr = i_size & ~PAGE_CACHE_MASK;
1495 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
1497 if (desc->error == -EINVAL)
1503 * We must evaluate after, since reads (unlike writes)
1504 * are called without i_sem protection against truncate
1506 nr = PAGE_CACHE_SIZE;
1507 i_size = i_size_read(inode);
1508 end_index = i_size >> PAGE_CACHE_SHIFT;
1509 if (index == end_index) {
1510 nr = i_size & ~PAGE_CACHE_MASK;
1513 page_cache_release(page);
1521 * If users can be writing to this page using arbitrary
1522 * virtual addresses, take care about potential aliasing
1523 * before reading the page on the kernel side.
1525 if (mapping_writably_mapped(mapping))
1526 flush_dcache_page(page);
1528 * Mark the page accessed if we read the beginning.
1531 mark_page_accessed(page);
1533 page = ZERO_PAGE(0);
1536 * Ok, we have the page, and it's up-to-date, so
1537 * now we can copy it to user space...
1539 * The actor routine returns how many bytes were actually used..
1540 * NOTE! This may not be the same as how much of a user buffer
1541 * we filled up (we may be padding etc), so we can only update
1542 * "pos" here (the actor routine has to update the user buffer
1543 * pointers and the remaining count).
1545 ret = actor(desc, page, offset, nr);
1547 index += offset >> PAGE_CACHE_SHIFT;
1548 offset &= ~PAGE_CACHE_MASK;
1550 page_cache_release(page);
1551 if (ret != nr || !desc->count)
1557 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1558 file_accessed(filp);
1561 static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
1563 read_descriptor_t desc;
1565 if ((ssize_t) count < 0)
1567 if (!access_ok(VERIFY_WRITE, buf, count))
1577 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1579 return desc.written;
1583 static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
1584 size_t count, read_actor_t actor, void *target)
1586 read_descriptor_t desc;
1593 desc.arg.data = target;
1596 do_shmem_file_read(in_file, ppos, &desc, actor);
1598 return desc.written;
1602 static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
1604 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1606 buf->f_type = TMPFS_SUPER_MAGIC;
1607 buf->f_bsize = PAGE_CACHE_SIZE;
1608 buf->f_namelen = NAME_MAX;
1610 spin_lock(&sbinfo->stat_lock);
1611 buf->f_blocks = sbinfo->max_blocks;
1612 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1613 buf->f_files = sbinfo->max_inodes;
1614 buf->f_ffree = sbinfo->free_inodes;
1615 spin_unlock(&sbinfo->stat_lock);
1617 /* else leave those fields 0 like simple_statfs */
1622 * File creation. Allocate an inode, and we're done..
1625 shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1627 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
1628 int error = -ENOSPC;
1631 if (dir->i_mode & S_ISGID) {
1632 inode->i_gid = dir->i_gid;
1634 inode->i_mode |= S_ISGID;
1636 dir->i_size += BOGO_DIRENT_SIZE;
1637 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1638 d_instantiate(dentry, inode);
1639 dget(dentry); /* Extra count - pin the dentry in core */
1645 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1649 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1655 static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1656 struct nameidata *nd)
1658 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1664 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1666 struct inode *inode = old_dentry->d_inode;
1667 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1670 * No ordinary (disk based) filesystem counts links as inodes;
1671 * but each new link needs a new dentry, pinning lowmem, and
1672 * tmpfs dentries cannot be pruned until they are unlinked.
1675 spin_lock(&sbinfo->stat_lock);
1676 if (!sbinfo->free_inodes) {
1677 spin_unlock(&sbinfo->stat_lock);
1680 sbinfo->free_inodes--;
1681 spin_unlock(&sbinfo->stat_lock);
1684 dir->i_size += BOGO_DIRENT_SIZE;
1685 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1687 atomic_inc(&inode->i_count); /* New dentry reference */
1688 dget(dentry); /* Extra pinning count for the created dentry */
1689 d_instantiate(dentry, inode);
1693 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1695 struct inode *inode = dentry->d_inode;
1697 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
1698 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1700 spin_lock(&sbinfo->stat_lock);
1701 sbinfo->free_inodes++;
1702 spin_unlock(&sbinfo->stat_lock);
1706 dir->i_size -= BOGO_DIRENT_SIZE;
1707 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1709 dput(dentry); /* Undo the count from "create" - this does all the work */
1713 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1715 if (!simple_empty(dentry))
1719 return shmem_unlink(dir, dentry);
1723 * The VFS layer already does all the dentry stuff for rename,
1724 * we just have to decrement the usage count for the target if
1725 * it exists so that the VFS layer correctly free's it when it
1728 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1730 struct inode *inode = old_dentry->d_inode;
1731 int they_are_dirs = S_ISDIR(inode->i_mode);
1733 if (!simple_empty(new_dentry))
1736 if (new_dentry->d_inode) {
1737 (void) shmem_unlink(new_dir, new_dentry);
1740 } else if (they_are_dirs) {
1745 old_dir->i_size -= BOGO_DIRENT_SIZE;
1746 new_dir->i_size += BOGO_DIRENT_SIZE;
1747 old_dir->i_ctime = old_dir->i_mtime =
1748 new_dir->i_ctime = new_dir->i_mtime =
1749 inode->i_ctime = CURRENT_TIME;
1753 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1757 struct inode *inode;
1758 struct page *page = NULL;
1760 struct shmem_inode_info *info;
1762 len = strlen(symname) + 1;
1763 if (len > PAGE_CACHE_SIZE)
1764 return -ENAMETOOLONG;
1766 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
1770 info = SHMEM_I(inode);
1771 inode->i_size = len-1;
1772 if (len <= (char *)inode - (char *)info) {
1774 memcpy(info, symname, len);
1775 inode->i_op = &shmem_symlink_inline_operations;
1777 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
1782 inode->i_op = &shmem_symlink_inode_operations;
1783 kaddr = kmap_atomic(page, KM_USER0);
1784 memcpy(kaddr, symname, len);
1785 kunmap_atomic(kaddr, KM_USER0);
1786 set_page_dirty(page);
1787 page_cache_release(page);
1789 if (dir->i_mode & S_ISGID)
1790 inode->i_gid = dir->i_gid;
1791 dir->i_size += BOGO_DIRENT_SIZE;
1792 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1793 d_instantiate(dentry, inode);
1798 static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
1800 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1804 static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
1806 struct page *page = NULL;
1807 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1808 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
1812 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
1814 if (!IS_ERR(nd_get_link(nd))) {
1817 page = find_get_page(dentry->d_inode->i_mapping, 0);
1821 mark_page_accessed(page);
1822 page_cache_release(page);
1823 page_cache_release(page);
1827 static struct inode_operations shmem_symlink_inline_operations = {
1828 .readlink = generic_readlink,
1829 .follow_link = shmem_follow_link_inline,
1830 #ifdef CONFIG_TMPFS_XATTR
1831 .setxattr = generic_setxattr,
1832 .getxattr = generic_getxattr,
1833 .listxattr = generic_listxattr,
1834 .removexattr = generic_removexattr,
1838 static struct inode_operations shmem_symlink_inode_operations = {
1839 .truncate = shmem_truncate,
1840 .readlink = generic_readlink,
1841 .follow_link = shmem_follow_link,
1842 .put_link = shmem_put_link,
1843 #ifdef CONFIG_TMPFS_XATTR
1844 .setxattr = generic_setxattr,
1845 .getxattr = generic_getxattr,
1846 .listxattr = generic_listxattr,
1847 .removexattr = generic_removexattr,
1851 static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
1853 char *this_char, *value, *rest;
1855 while ((this_char = strsep(&options, ",")) != NULL) {
1858 if ((value = strchr(this_char,'=')) != NULL) {
1862 "tmpfs: No value for mount option '%s'\n",
1867 if (!strcmp(this_char,"size")) {
1868 unsigned long long size;
1869 size = memparse(value,&rest);
1871 size <<= PAGE_SHIFT;
1872 size *= totalram_pages;
1878 *blocks = size >> PAGE_CACHE_SHIFT;
1879 } else if (!strcmp(this_char,"nr_blocks")) {
1880 *blocks = memparse(value,&rest);
1883 } else if (!strcmp(this_char,"nr_inodes")) {
1884 *inodes = memparse(value,&rest);
1887 } else if (!strcmp(this_char,"mode")) {
1890 *mode = simple_strtoul(value,&rest,8);
1893 } else if (!strcmp(this_char,"uid")) {
1896 *uid = simple_strtoul(value,&rest,0);
1899 } else if (!strcmp(this_char,"gid")) {
1902 *gid = simple_strtoul(value,&rest,0);
1906 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
1914 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
1920 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
1922 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1923 unsigned long max_blocks = 0;
1924 unsigned long max_inodes = 0;
1927 max_blocks = sbinfo->max_blocks;
1928 max_inodes = sbinfo->max_inodes;
1930 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes))
1932 /* Keep it simple: disallow limited <-> unlimited remount */
1933 if ((max_blocks || max_inodes) == !sbinfo)
1935 /* But allow the pointless unlimited -> unlimited remount */
1938 return shmem_set_size(sbinfo, max_blocks, max_inodes);
1942 static void shmem_put_super(struct super_block *sb)
1944 kfree(sb->s_fs_info);
1945 sb->s_fs_info = NULL;
1948 #ifdef CONFIG_TMPFS_XATTR
1949 static struct xattr_handler *shmem_xattr_handlers[];
1951 #define shmem_xattr_handlers NULL
1954 static int shmem_fill_super(struct super_block *sb,
1955 void *data, int silent)
1957 struct inode *inode;
1958 struct dentry *root;
1959 int mode = S_IRWXUGO | S_ISVTX;
1960 uid_t uid = current->fsuid;
1961 gid_t gid = current->fsgid;
1965 unsigned long blocks = 0;
1966 unsigned long inodes = 0;
1969 * Per default we only allow half of the physical ram per
1970 * tmpfs instance, limiting inodes to one per page of lowmem;
1971 * but the internal instance is left unlimited.
1973 if (!(sb->s_flags & MS_NOUSER)) {
1974 blocks = totalram_pages / 2;
1975 inodes = totalram_pages - totalhigh_pages;
1976 if (inodes > blocks)
1979 if (shmem_parse_options(data, &mode,
1980 &uid, &gid, &blocks, &inodes))
1984 if (blocks || inodes) {
1985 struct shmem_sb_info *sbinfo;
1986 sbinfo = kmalloc(sizeof(struct shmem_sb_info), GFP_KERNEL);
1989 sb->s_fs_info = sbinfo;
1990 spin_lock_init(&sbinfo->stat_lock);
1991 sbinfo->max_blocks = blocks;
1992 sbinfo->free_blocks = blocks;
1993 sbinfo->max_inodes = inodes;
1994 sbinfo->free_inodes = inodes;
1996 sb->s_xattr = shmem_xattr_handlers;
1998 sb->s_flags |= MS_NOUSER;
2001 sb->s_maxbytes = SHMEM_MAX_BYTES;
2002 sb->s_blocksize = PAGE_CACHE_SIZE;
2003 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2004 sb->s_magic = TMPFS_SUPER_MAGIC;
2005 sb->s_op = &shmem_ops;
2006 inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
2011 root = d_alloc_root(inode);
2020 shmem_put_super(sb);
2024 static kmem_cache_t *shmem_inode_cachep;
2026 static struct inode *shmem_alloc_inode(struct super_block *sb)
2028 struct shmem_inode_info *p;
2029 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
2032 return &p->vfs_inode;
2035 static void shmem_destroy_inode(struct inode *inode)
2037 if ((inode->i_mode & S_IFMT) == S_IFREG) {
2038 /* only struct inode is valid if it's an inline symlink */
2039 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2041 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2044 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
2046 struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
2048 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
2049 SLAB_CTOR_CONSTRUCTOR) {
2050 inode_init_once(&p->vfs_inode);
2054 static int init_inodecache(void)
2056 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2057 sizeof(struct shmem_inode_info),
2058 0, 0, init_once, NULL);
2059 if (shmem_inode_cachep == NULL)
2064 static void destroy_inodecache(void)
2066 if (kmem_cache_destroy(shmem_inode_cachep))
2067 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
2070 static struct address_space_operations shmem_aops = {
2071 .writepage = shmem_writepage,
2072 .set_page_dirty = __set_page_dirty_nobuffers,
2074 .prepare_write = shmem_prepare_write,
2075 .commit_write = simple_commit_write,
2079 static struct file_operations shmem_file_operations = {
2082 .llseek = generic_file_llseek,
2083 .read = shmem_file_read,
2084 .write = shmem_file_write,
2085 .fsync = simple_sync_file,
2086 .sendfile = shmem_file_sendfile,
2090 static struct inode_operations shmem_inode_operations = {
2091 .truncate = shmem_truncate,
2092 .setattr = shmem_notify_change,
2093 #ifdef CONFIG_TMPFS_XATTR
2094 .setxattr = generic_setxattr,
2095 .getxattr = generic_getxattr,
2096 .listxattr = generic_listxattr,
2097 .removexattr = generic_removexattr,
2101 static struct inode_operations shmem_dir_inode_operations = {
2103 .create = shmem_create,
2104 .lookup = simple_lookup,
2106 .unlink = shmem_unlink,
2107 .symlink = shmem_symlink,
2108 .mkdir = shmem_mkdir,
2109 .rmdir = shmem_rmdir,
2110 .mknod = shmem_mknod,
2111 .rename = shmem_rename,
2112 #ifdef CONFIG_TMPFS_XATTR
2113 .setxattr = generic_setxattr,
2114 .getxattr = generic_getxattr,
2115 .listxattr = generic_listxattr,
2116 .removexattr = generic_removexattr,
2121 static struct inode_operations shmem_special_inode_operations = {
2122 #ifdef CONFIG_TMPFS_XATTR
2123 .setxattr = generic_setxattr,
2124 .getxattr = generic_getxattr,
2125 .listxattr = generic_listxattr,
2126 .removexattr = generic_removexattr,
2130 static struct super_operations shmem_ops = {
2131 .alloc_inode = shmem_alloc_inode,
2132 .destroy_inode = shmem_destroy_inode,
2134 .statfs = shmem_statfs,
2135 .remount_fs = shmem_remount_fs,
2137 .delete_inode = shmem_delete_inode,
2138 .drop_inode = generic_delete_inode,
2139 .put_super = shmem_put_super,
2142 static struct vm_operations_struct shmem_vm_ops = {
2143 .nopage = shmem_nopage,
2144 .populate = shmem_populate,
2146 .set_policy = shmem_set_policy,
2147 .get_policy = shmem_get_policy,
2152 #ifdef CONFIG_TMPFS_SECURITY
2154 static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len,
2155 const char *name, size_t name_len)
2157 return security_inode_listsecurity(inode, list, list_len);
2160 static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size)
2162 if (strcmp(name, "") == 0)
2164 return security_inode_getsecurity(inode, name, buffer, size);
2167 static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags)
2169 if (strcmp(name, "") == 0)
2171 return security_inode_setsecurity(inode, name, value, size, flags);
2174 struct xattr_handler shmem_xattr_security_handler = {
2175 .prefix = XATTR_SECURITY_PREFIX,
2176 .list = shmem_xattr_security_list,
2177 .get = shmem_xattr_security_get,
2178 .set = shmem_xattr_security_set,
2181 #endif /* CONFIG_TMPFS_SECURITY */
2183 #ifdef CONFIG_TMPFS_XATTR
2185 static struct xattr_handler *shmem_xattr_handlers[] = {
2186 #ifdef CONFIG_TMPFS_SECURITY
2187 &shmem_xattr_security_handler,
2192 #endif /* CONFIG_TMPFS_XATTR */
2194 static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
2195 int flags, const char *dev_name, void *data)
2197 return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
2200 static struct file_system_type tmpfs_fs_type = {
2201 .owner = THIS_MODULE,
2203 .get_sb = shmem_get_sb,
2204 .kill_sb = kill_litter_super,
2206 static struct vfsmount *shm_mnt;
2208 static int __init init_tmpfs(void)
2212 error = init_inodecache();
2216 error = register_filesystem(&tmpfs_fs_type);
2218 printk(KERN_ERR "Could not register tmpfs\n");
2222 devfs_mk_dir("shm");
2224 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
2225 tmpfs_fs_type.name, NULL);
2226 if (IS_ERR(shm_mnt)) {
2227 error = PTR_ERR(shm_mnt);
2228 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2234 unregister_filesystem(&tmpfs_fs_type);
2236 destroy_inodecache();
2238 shm_mnt = ERR_PTR(error);
2241 module_init(init_tmpfs)
2244 * shmem_file_setup - get an unlinked file living in tmpfs
2246 * @name: name for dentry (to be seen in /proc/<pid>/maps
2247 * @size: size to be set for the file
2250 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
2254 struct inode *inode;
2255 struct dentry *dentry, *root;
2258 if (IS_ERR(shm_mnt))
2259 return (void *)shm_mnt;
2261 if (size < 0 || size > SHMEM_MAX_BYTES)
2262 return ERR_PTR(-EINVAL);
2264 if (shmem_acct_size(flags, size))
2265 return ERR_PTR(-ENOMEM);
2269 this.len = strlen(name);
2270 this.hash = 0; /* will go */
2271 root = shm_mnt->mnt_root;
2272 dentry = d_alloc(root, &this);
2277 file = get_empty_filp();
2282 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
2286 SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2287 d_instantiate(dentry, inode);
2288 inode->i_size = size;
2289 inode->i_nlink = 0; /* It is unlinked */
2290 file->f_vfsmnt = mntget(shm_mnt);
2291 file->f_dentry = dentry;
2292 file->f_mapping = inode->i_mapping;
2293 file->f_op = &shmem_file_operations;
2294 file->f_mode = FMODE_WRITE | FMODE_READ;
2302 shmem_unacct_size(flags, size);
2303 return ERR_PTR(error);
2307 * shmem_zero_setup - setup a shared anonymous mapping
2309 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2311 int shmem_zero_setup(struct vm_area_struct *vma)
2314 loff_t size = vma->vm_end - vma->vm_start;
2316 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
2318 return PTR_ERR(file);
2322 vma->vm_file = file;
2323 vma->vm_ops = &shmem_vm_ops;