2 * Resizable virtual memory filesystem for Linux.
4 * Copyright (C) 2000 Linus Torvalds.
6 * 2000-2001 Christoph Rohland
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
21 * This file is released under the GPL.
25 #include <linux/init.h>
26 #include <linux/vfs.h>
27 #include <linux/mount.h>
28 #include <linux/ramfs.h>
29 #include <linux/pagemap.h>
30 #include <linux/file.h>
32 #include <linux/export.h>
33 #include <linux/swap.h>
34 #include <linux/aio.h>
36 static struct vfsmount *shm_mnt;
40 * This virtual memory filesystem is heavily based on the ramfs. It
41 * extends ramfs by the ability to use swap and honor resource limits
42 * which makes it a completely usable filesystem.
45 #include <linux/xattr.h>
46 #include <linux/exportfs.h>
47 #include <linux/posix_acl.h>
48 #include <linux/posix_acl_xattr.h>
49 #include <linux/mman.h>
50 #include <linux/string.h>
51 #include <linux/slab.h>
52 #include <linux/backing-dev.h>
53 #include <linux/shmem_fs.h>
54 #include <linux/writeback.h>
55 #include <linux/blkdev.h>
56 #include <linux/pagevec.h>
57 #include <linux/percpu_counter.h>
58 #include <linux/falloc.h>
59 #include <linux/splice.h>
60 #include <linux/security.h>
61 #include <linux/swapops.h>
62 #include <linux/mempolicy.h>
63 #include <linux/namei.h>
64 #include <linux/ctype.h>
65 #include <linux/migrate.h>
66 #include <linux/highmem.h>
67 #include <linux/seq_file.h>
68 #include <linux/magic.h>
70 #include <asm/uaccess.h>
71 #include <asm/pgtable.h>
73 #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
74 #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
76 /* Pretend that each entry is of this size in directory's i_size */
77 #define BOGO_DIRENT_SIZE 20
79 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
80 #define SHORT_SYMLINK_LEN 128
83 * shmem_fallocate and shmem_writepage communicate via inode->i_private
84 * (with i_mutex making sure that it has only one user at a time):
85 * we would prefer not to enlarge the shmem inode just for that.
88 pgoff_t start; /* start of range currently being fallocated */
89 pgoff_t next; /* the next page offset to be fallocated */
90 pgoff_t nr_falloced; /* how many new pages have been fallocated */
91 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
94 /* Flag allocation requirements to shmem_getpage */
96 SGP_READ, /* don't exceed i_size, don't allocate page */
97 SGP_CACHE, /* don't exceed i_size, may allocate page */
98 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
99 SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
100 SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
104 static unsigned long shmem_default_max_blocks(void)
106 return totalram_pages / 2;
109 static unsigned long shmem_default_max_inodes(void)
111 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
115 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
116 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
117 struct shmem_inode_info *info, pgoff_t index);
118 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
119 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
121 static inline int shmem_getpage(struct inode *inode, pgoff_t index,
122 struct page **pagep, enum sgp_type sgp, int *fault_type)
124 return shmem_getpage_gfp(inode, index, pagep, sgp,
125 mapping_gfp_mask(inode->i_mapping), fault_type);
128 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
130 return sb->s_fs_info;
134 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
135 * for shared memory and for shared anonymous (/dev/zero) mappings
136 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
137 * consistent with the pre-accounting of private mappings ...
139 static inline int shmem_acct_size(unsigned long flags, loff_t size)
141 return (flags & VM_NORESERVE) ?
142 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
145 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
147 if (!(flags & VM_NORESERVE))
148 vm_unacct_memory(VM_ACCT(size));
152 * ... whereas tmpfs objects are accounted incrementally as
153 * pages are allocated, in order to allow huge sparse files.
154 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
155 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
157 static inline int shmem_acct_block(unsigned long flags)
159 return (flags & VM_NORESERVE) ?
160 security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
163 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
165 if (flags & VM_NORESERVE)
166 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
169 static const struct super_operations shmem_ops;
170 static const struct address_space_operations shmem_aops;
171 static const struct file_operations shmem_file_operations;
172 static const struct inode_operations shmem_inode_operations;
173 static const struct inode_operations shmem_dir_inode_operations;
174 static const struct inode_operations shmem_special_inode_operations;
175 static const struct vm_operations_struct shmem_vm_ops;
177 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
178 .ra_pages = 0, /* No readahead */
179 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
182 static LIST_HEAD(shmem_swaplist);
183 static DEFINE_MUTEX(shmem_swaplist_mutex);
185 static int shmem_reserve_inode(struct super_block *sb)
187 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
188 if (sbinfo->max_inodes) {
189 spin_lock(&sbinfo->stat_lock);
190 if (!sbinfo->free_inodes) {
191 spin_unlock(&sbinfo->stat_lock);
194 sbinfo->free_inodes--;
195 spin_unlock(&sbinfo->stat_lock);
200 static void shmem_free_inode(struct super_block *sb)
202 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
203 if (sbinfo->max_inodes) {
204 spin_lock(&sbinfo->stat_lock);
205 sbinfo->free_inodes++;
206 spin_unlock(&sbinfo->stat_lock);
211 * shmem_recalc_inode - recalculate the block usage of an inode
212 * @inode: inode to recalc
214 * We have to calculate the free blocks since the mm can drop
215 * undirtied hole pages behind our back.
217 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
218 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
220 * It has to be called with the spinlock held.
222 static void shmem_recalc_inode(struct inode *inode)
224 struct shmem_inode_info *info = SHMEM_I(inode);
227 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
229 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
230 if (sbinfo->max_blocks)
231 percpu_counter_add(&sbinfo->used_blocks, -freed);
232 info->alloced -= freed;
233 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
234 shmem_unacct_blocks(info->flags, freed);
239 * Replace item expected in radix tree by a new item, while holding tree lock.
241 static int shmem_radix_tree_replace(struct address_space *mapping,
242 pgoff_t index, void *expected, void *replacement)
247 VM_BUG_ON(!expected);
248 VM_BUG_ON(!replacement);
249 pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
252 item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
253 if (item != expected)
255 radix_tree_replace_slot(pslot, replacement);
260 * Sometimes, before we decide whether to proceed or to fail, we must check
261 * that an entry was not already brought back from swap by a racing thread.
263 * Checking page is not enough: by the time a SwapCache page is locked, it
264 * might be reused, and again be SwapCache, using the same swap as before.
266 static bool shmem_confirm_swap(struct address_space *mapping,
267 pgoff_t index, swp_entry_t swap)
272 item = radix_tree_lookup(&mapping->page_tree, index);
274 return item == swp_to_radix_entry(swap);
278 * Like add_to_page_cache_locked, but error if expected item has gone.
280 static int shmem_add_to_page_cache(struct page *page,
281 struct address_space *mapping,
282 pgoff_t index, gfp_t gfp, void *expected)
286 VM_BUG_ON_PAGE(!PageLocked(page), page);
287 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
289 page_cache_get(page);
290 page->mapping = mapping;
293 spin_lock_irq(&mapping->tree_lock);
295 error = radix_tree_insert(&mapping->page_tree, index, page);
297 error = shmem_radix_tree_replace(mapping, index, expected,
301 __inc_zone_page_state(page, NR_FILE_PAGES);
302 __inc_zone_page_state(page, NR_SHMEM);
303 spin_unlock_irq(&mapping->tree_lock);
305 page->mapping = NULL;
306 spin_unlock_irq(&mapping->tree_lock);
307 page_cache_release(page);
313 * Like delete_from_page_cache, but substitutes swap for page.
315 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
317 struct address_space *mapping = page->mapping;
320 spin_lock_irq(&mapping->tree_lock);
321 error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
322 page->mapping = NULL;
324 __dec_zone_page_state(page, NR_FILE_PAGES);
325 __dec_zone_page_state(page, NR_SHMEM);
326 spin_unlock_irq(&mapping->tree_lock);
327 page_cache_release(page);
332 * Like find_get_pages, but collecting swap entries as well as pages.
334 static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
335 pgoff_t start, unsigned int nr_pages,
336 struct page **pages, pgoff_t *indices)
339 unsigned int ret = 0;
340 struct radix_tree_iter iter;
347 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
350 page = radix_tree_deref_slot(slot);
353 if (radix_tree_exception(page)) {
354 if (radix_tree_deref_retry(page))
357 * Otherwise, we must be storing a swap entry
358 * here as an exceptional entry: so return it
359 * without attempting to raise page count.
363 if (!page_cache_get_speculative(page))
366 /* Has the page moved? */
367 if (unlikely(page != *slot)) {
368 page_cache_release(page);
372 indices[ret] = iter.index;
374 if (++ret == nr_pages)
382 * Remove swap entry from radix tree, free the swap and its page cache.
384 static int shmem_free_swap(struct address_space *mapping,
385 pgoff_t index, void *radswap)
389 spin_lock_irq(&mapping->tree_lock);
390 old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
391 spin_unlock_irq(&mapping->tree_lock);
394 free_swap_and_cache(radix_to_swp_entry(radswap));
399 * Pagevec may contain swap entries, so shuffle up pages before releasing.
401 static void shmem_deswap_pagevec(struct pagevec *pvec)
405 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
406 struct page *page = pvec->pages[i];
407 if (!radix_tree_exceptional_entry(page))
408 pvec->pages[j++] = page;
414 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
416 void shmem_unlock_mapping(struct address_space *mapping)
419 pgoff_t indices[PAGEVEC_SIZE];
422 pagevec_init(&pvec, 0);
424 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
426 while (!mapping_unevictable(mapping)) {
428 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
429 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
431 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
432 PAGEVEC_SIZE, pvec.pages, indices);
435 index = indices[pvec.nr - 1] + 1;
436 shmem_deswap_pagevec(&pvec);
437 check_move_unevictable_pages(pvec.pages, pvec.nr);
438 pagevec_release(&pvec);
444 * Remove range of pages and swap entries from radix tree, and free them.
445 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
447 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
450 struct address_space *mapping = inode->i_mapping;
451 struct shmem_inode_info *info = SHMEM_I(inode);
452 pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
453 pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
454 unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
455 unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
457 pgoff_t indices[PAGEVEC_SIZE];
458 long nr_swaps_freed = 0;
463 end = -1; /* unsigned, so actually very big */
465 pagevec_init(&pvec, 0);
467 while (index < end) {
468 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
469 min(end - index, (pgoff_t)PAGEVEC_SIZE),
470 pvec.pages, indices);
473 mem_cgroup_uncharge_start();
474 for (i = 0; i < pagevec_count(&pvec); i++) {
475 struct page *page = pvec.pages[i];
481 if (radix_tree_exceptional_entry(page)) {
484 nr_swaps_freed += !shmem_free_swap(mapping,
489 if (!trylock_page(page))
491 if (!unfalloc || !PageUptodate(page)) {
492 if (page->mapping == mapping) {
493 VM_BUG_ON_PAGE(PageWriteback(page), page);
494 truncate_inode_page(mapping, page);
499 shmem_deswap_pagevec(&pvec);
500 pagevec_release(&pvec);
501 mem_cgroup_uncharge_end();
507 struct page *page = NULL;
508 shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
510 unsigned int top = PAGE_CACHE_SIZE;
515 zero_user_segment(page, partial_start, top);
516 set_page_dirty(page);
518 page_cache_release(page);
522 struct page *page = NULL;
523 shmem_getpage(inode, end, &page, SGP_READ, NULL);
525 zero_user_segment(page, 0, partial_end);
526 set_page_dirty(page);
528 page_cache_release(page);
537 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
538 min(end - index, (pgoff_t)PAGEVEC_SIZE),
539 pvec.pages, indices);
541 if (index == start || unfalloc)
546 if ((index == start || unfalloc) && indices[0] >= end) {
547 shmem_deswap_pagevec(&pvec);
548 pagevec_release(&pvec);
551 mem_cgroup_uncharge_start();
552 for (i = 0; i < pagevec_count(&pvec); i++) {
553 struct page *page = pvec.pages[i];
559 if (radix_tree_exceptional_entry(page)) {
562 nr_swaps_freed += !shmem_free_swap(mapping,
568 if (!unfalloc || !PageUptodate(page)) {
569 if (page->mapping == mapping) {
570 VM_BUG_ON_PAGE(PageWriteback(page), page);
571 truncate_inode_page(mapping, page);
576 shmem_deswap_pagevec(&pvec);
577 pagevec_release(&pvec);
578 mem_cgroup_uncharge_end();
582 spin_lock(&info->lock);
583 info->swapped -= nr_swaps_freed;
584 shmem_recalc_inode(inode);
585 spin_unlock(&info->lock);
588 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
590 shmem_undo_range(inode, lstart, lend, false);
591 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
593 EXPORT_SYMBOL_GPL(shmem_truncate_range);
595 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
597 struct inode *inode = dentry->d_inode;
600 error = inode_change_ok(inode, attr);
604 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
605 loff_t oldsize = inode->i_size;
606 loff_t newsize = attr->ia_size;
608 if (newsize != oldsize) {
609 i_size_write(inode, newsize);
610 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
612 if (newsize < oldsize) {
613 loff_t holebegin = round_up(newsize, PAGE_SIZE);
614 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
615 shmem_truncate_range(inode, newsize, (loff_t)-1);
616 /* unmap again to remove racily COWed private pages */
617 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
621 setattr_copy(inode, attr);
622 if (attr->ia_valid & ATTR_MODE)
623 error = posix_acl_chmod(inode, inode->i_mode);
627 static void shmem_evict_inode(struct inode *inode)
629 struct shmem_inode_info *info = SHMEM_I(inode);
631 if (inode->i_mapping->a_ops == &shmem_aops) {
632 shmem_unacct_size(info->flags, inode->i_size);
634 shmem_truncate_range(inode, 0, (loff_t)-1);
635 if (!list_empty(&info->swaplist)) {
636 mutex_lock(&shmem_swaplist_mutex);
637 list_del_init(&info->swaplist);
638 mutex_unlock(&shmem_swaplist_mutex);
641 kfree(info->symlink);
643 simple_xattrs_free(&info->xattrs);
644 WARN_ON(inode->i_blocks);
645 shmem_free_inode(inode->i_sb);
650 * If swap found in inode, free it and move page from swapcache to filecache.
652 static int shmem_unuse_inode(struct shmem_inode_info *info,
653 swp_entry_t swap, struct page **pagep)
655 struct address_space *mapping = info->vfs_inode.i_mapping;
661 radswap = swp_to_radix_entry(swap);
662 index = radix_tree_locate_item(&mapping->page_tree, radswap);
667 * Move _head_ to start search for next from here.
668 * But be careful: shmem_evict_inode checks list_empty without taking
669 * mutex, and there's an instant in list_move_tail when info->swaplist
670 * would appear empty, if it were the only one on shmem_swaplist.
672 if (shmem_swaplist.next != &info->swaplist)
673 list_move_tail(&shmem_swaplist, &info->swaplist);
675 gfp = mapping_gfp_mask(mapping);
676 if (shmem_should_replace_page(*pagep, gfp)) {
677 mutex_unlock(&shmem_swaplist_mutex);
678 error = shmem_replace_page(pagep, gfp, info, index);
679 mutex_lock(&shmem_swaplist_mutex);
681 * We needed to drop mutex to make that restrictive page
682 * allocation, but the inode might have been freed while we
683 * dropped it: although a racing shmem_evict_inode() cannot
684 * complete without emptying the radix_tree, our page lock
685 * on this swapcache page is not enough to prevent that -
686 * free_swap_and_cache() of our swap entry will only
687 * trylock_page(), removing swap from radix_tree whatever.
689 * We must not proceed to shmem_add_to_page_cache() if the
690 * inode has been freed, but of course we cannot rely on
691 * inode or mapping or info to check that. However, we can
692 * safely check if our swap entry is still in use (and here
693 * it can't have got reused for another page): if it's still
694 * in use, then the inode cannot have been freed yet, and we
695 * can safely proceed (if it's no longer in use, that tells
696 * nothing about the inode, but we don't need to unuse swap).
698 if (!page_swapcount(*pagep))
703 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
704 * but also to hold up shmem_evict_inode(): so inode cannot be freed
705 * beneath us (pagelock doesn't help until the page is in pagecache).
708 error = shmem_add_to_page_cache(*pagep, mapping, index,
709 GFP_NOWAIT, radswap);
710 if (error != -ENOMEM) {
712 * Truncation and eviction use free_swap_and_cache(), which
713 * only does trylock page: if we raced, best clean up here.
715 delete_from_swap_cache(*pagep);
716 set_page_dirty(*pagep);
718 spin_lock(&info->lock);
720 spin_unlock(&info->lock);
723 error = 1; /* not an error, but entry was found */
729 * Search through swapped inodes to find and replace swap by page.
731 int shmem_unuse(swp_entry_t swap, struct page *page)
733 struct list_head *this, *next;
734 struct shmem_inode_info *info;
739 * There's a faint possibility that swap page was replaced before
740 * caller locked it: caller will come back later with the right page.
742 if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
746 * Charge page using GFP_KERNEL while we can wait, before taking
747 * the shmem_swaplist_mutex which might hold up shmem_writepage().
748 * Charged back to the user (not to caller) when swap account is used.
750 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
753 /* No radix_tree_preload: swap entry keeps a place for page in tree */
755 mutex_lock(&shmem_swaplist_mutex);
756 list_for_each_safe(this, next, &shmem_swaplist) {
757 info = list_entry(this, struct shmem_inode_info, swaplist);
759 found = shmem_unuse_inode(info, swap, &page);
761 list_del_init(&info->swaplist);
766 mutex_unlock(&shmem_swaplist_mutex);
772 page_cache_release(page);
777 * Move the page from the page cache to the swap cache.
779 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
781 struct shmem_inode_info *info;
782 struct address_space *mapping;
787 BUG_ON(!PageLocked(page));
788 mapping = page->mapping;
790 inode = mapping->host;
791 info = SHMEM_I(inode);
792 if (info->flags & VM_LOCKED)
794 if (!total_swap_pages)
798 * shmem_backing_dev_info's capabilities prevent regular writeback or
799 * sync from ever calling shmem_writepage; but a stacking filesystem
800 * might use ->writepage of its underlying filesystem, in which case
801 * tmpfs should write out to swap only in response to memory pressure,
802 * and not for the writeback threads or sync.
804 if (!wbc->for_reclaim) {
805 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
810 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
811 * value into swapfile.c, the only way we can correctly account for a
812 * fallocated page arriving here is now to initialize it and write it.
814 * That's okay for a page already fallocated earlier, but if we have
815 * not yet completed the fallocation, then (a) we want to keep track
816 * of this page in case we have to undo it, and (b) it may not be a
817 * good idea to continue anyway, once we're pushing into swap. So
818 * reactivate the page, and let shmem_fallocate() quit when too many.
820 if (!PageUptodate(page)) {
821 if (inode->i_private) {
822 struct shmem_falloc *shmem_falloc;
823 spin_lock(&inode->i_lock);
824 shmem_falloc = inode->i_private;
826 index >= shmem_falloc->start &&
827 index < shmem_falloc->next)
828 shmem_falloc->nr_unswapped++;
831 spin_unlock(&inode->i_lock);
835 clear_highpage(page);
836 flush_dcache_page(page);
837 SetPageUptodate(page);
840 swap = get_swap_page();
845 * Add inode to shmem_unuse()'s list of swapped-out inodes,
846 * if it's not already there. Do it now before the page is
847 * moved to swap cache, when its pagelock no longer protects
848 * the inode from eviction. But don't unlock the mutex until
849 * we've incremented swapped, because shmem_unuse_inode() will
850 * prune a !swapped inode from the swaplist under this mutex.
852 mutex_lock(&shmem_swaplist_mutex);
853 if (list_empty(&info->swaplist))
854 list_add_tail(&info->swaplist, &shmem_swaplist);
856 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
857 swap_shmem_alloc(swap);
858 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
860 spin_lock(&info->lock);
862 shmem_recalc_inode(inode);
863 spin_unlock(&info->lock);
865 mutex_unlock(&shmem_swaplist_mutex);
866 BUG_ON(page_mapped(page));
867 swap_writepage(page, wbc);
871 mutex_unlock(&shmem_swaplist_mutex);
872 swapcache_free(swap, NULL);
874 set_page_dirty(page);
875 if (wbc->for_reclaim)
876 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
883 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
887 if (!mpol || mpol->mode == MPOL_DEFAULT)
888 return; /* show nothing */
890 mpol_to_str(buffer, sizeof(buffer), mpol);
892 seq_printf(seq, ",mpol=%s", buffer);
895 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
897 struct mempolicy *mpol = NULL;
899 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
902 spin_unlock(&sbinfo->stat_lock);
906 #endif /* CONFIG_TMPFS */
908 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
909 struct shmem_inode_info *info, pgoff_t index)
911 struct vm_area_struct pvma;
914 /* Create a pseudo vma that just contains the policy */
916 /* Bias interleave by inode number to distribute better across nodes */
917 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
919 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
921 page = swapin_readahead(swap, gfp, &pvma, 0);
923 /* Drop reference taken by mpol_shared_policy_lookup() */
924 mpol_cond_put(pvma.vm_policy);
929 static struct page *shmem_alloc_page(gfp_t gfp,
930 struct shmem_inode_info *info, pgoff_t index)
932 struct vm_area_struct pvma;
935 /* Create a pseudo vma that just contains the policy */
937 /* Bias interleave by inode number to distribute better across nodes */
938 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
940 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
942 page = alloc_page_vma(gfp, &pvma, 0);
944 /* Drop reference taken by mpol_shared_policy_lookup() */
945 mpol_cond_put(pvma.vm_policy);
949 #else /* !CONFIG_NUMA */
951 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
954 #endif /* CONFIG_TMPFS */
956 static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
957 struct shmem_inode_info *info, pgoff_t index)
959 return swapin_readahead(swap, gfp, NULL, 0);
962 static inline struct page *shmem_alloc_page(gfp_t gfp,
963 struct shmem_inode_info *info, pgoff_t index)
965 return alloc_page(gfp);
967 #endif /* CONFIG_NUMA */
969 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
970 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
977 * When a page is moved from swapcache to shmem filecache (either by the
978 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
979 * shmem_unuse_inode()), it may have been read in earlier from swap, in
980 * ignorance of the mapping it belongs to. If that mapping has special
981 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
982 * we may need to copy to a suitable page before moving to filecache.
984 * In a future release, this may well be extended to respect cpuset and
985 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
986 * but for now it is a simple matter of zone.
988 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
990 return page_zonenum(page) > gfp_zone(gfp);
993 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
994 struct shmem_inode_info *info, pgoff_t index)
996 struct page *oldpage, *newpage;
997 struct address_space *swap_mapping;
1002 swap_index = page_private(oldpage);
1003 swap_mapping = page_mapping(oldpage);
1006 * We have arrived here because our zones are constrained, so don't
1007 * limit chance of success by further cpuset and node constraints.
1009 gfp &= ~GFP_CONSTRAINT_MASK;
1010 newpage = shmem_alloc_page(gfp, info, index);
1014 page_cache_get(newpage);
1015 copy_highpage(newpage, oldpage);
1016 flush_dcache_page(newpage);
1018 __set_page_locked(newpage);
1019 SetPageUptodate(newpage);
1020 SetPageSwapBacked(newpage);
1021 set_page_private(newpage, swap_index);
1022 SetPageSwapCache(newpage);
1025 * Our caller will very soon move newpage out of swapcache, but it's
1026 * a nice clean interface for us to replace oldpage by newpage there.
1028 spin_lock_irq(&swap_mapping->tree_lock);
1029 error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
1032 __inc_zone_page_state(newpage, NR_FILE_PAGES);
1033 __dec_zone_page_state(oldpage, NR_FILE_PAGES);
1035 spin_unlock_irq(&swap_mapping->tree_lock);
1037 if (unlikely(error)) {
1039 * Is this possible? I think not, now that our callers check
1040 * both PageSwapCache and page_private after getting page lock;
1041 * but be defensive. Reverse old to newpage for clear and free.
1045 mem_cgroup_replace_page_cache(oldpage, newpage);
1046 lru_cache_add_anon(newpage);
1050 ClearPageSwapCache(oldpage);
1051 set_page_private(oldpage, 0);
1053 unlock_page(oldpage);
1054 page_cache_release(oldpage);
1055 page_cache_release(oldpage);
1060 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1062 * If we allocate a new one we do not mark it dirty. That's up to the
1063 * vm. If we swap it in we mark it dirty since we also free the swap
1064 * entry since a page cannot live in both the swap and page cache
1066 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1067 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
1069 struct address_space *mapping = inode->i_mapping;
1070 struct shmem_inode_info *info;
1071 struct shmem_sb_info *sbinfo;
1078 if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
1082 page = find_lock_page(mapping, index);
1083 if (radix_tree_exceptional_entry(page)) {
1084 swap = radix_to_swp_entry(page);
1088 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1089 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1094 /* fallocated page? */
1095 if (page && !PageUptodate(page)) {
1096 if (sgp != SGP_READ)
1099 page_cache_release(page);
1102 if (page || (sgp == SGP_READ && !swap.val)) {
1108 * Fast cache lookup did not find it:
1109 * bring it back from swap or allocate.
1111 info = SHMEM_I(inode);
1112 sbinfo = SHMEM_SB(inode->i_sb);
1115 /* Look it up and read it in.. */
1116 page = lookup_swap_cache(swap);
1118 /* here we actually do the io */
1120 *fault_type |= VM_FAULT_MAJOR;
1121 page = shmem_swapin(swap, gfp, info, index);
1128 /* We have to do this with page locked to prevent races */
1130 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1131 !shmem_confirm_swap(mapping, index, swap)) {
1132 error = -EEXIST; /* try again */
1135 if (!PageUptodate(page)) {
1139 wait_on_page_writeback(page);
1141 if (shmem_should_replace_page(page, gfp)) {
1142 error = shmem_replace_page(&page, gfp, info, index);
1147 error = mem_cgroup_cache_charge(page, current->mm,
1148 gfp & GFP_RECLAIM_MASK);
1150 error = shmem_add_to_page_cache(page, mapping, index,
1151 gfp, swp_to_radix_entry(swap));
1153 * We already confirmed swap under page lock, and make
1154 * no memory allocation here, so usually no possibility
1155 * of error; but free_swap_and_cache() only trylocks a
1156 * page, so it is just possible that the entry has been
1157 * truncated or holepunched since swap was confirmed.
1158 * shmem_undo_range() will have done some of the
1159 * unaccounting, now delete_from_swap_cache() will do
1160 * the rest (including mem_cgroup_uncharge_swapcache).
1161 * Reset swap.val? No, leave it so "failed" goes back to
1162 * "repeat": reading a hole and writing should succeed.
1165 delete_from_swap_cache(page);
1170 spin_lock(&info->lock);
1172 shmem_recalc_inode(inode);
1173 spin_unlock(&info->lock);
1175 delete_from_swap_cache(page);
1176 set_page_dirty(page);
1180 if (shmem_acct_block(info->flags)) {
1184 if (sbinfo->max_blocks) {
1185 if (percpu_counter_compare(&sbinfo->used_blocks,
1186 sbinfo->max_blocks) >= 0) {
1190 percpu_counter_inc(&sbinfo->used_blocks);
1193 page = shmem_alloc_page(gfp, info, index);
1199 SetPageSwapBacked(page);
1200 __set_page_locked(page);
1201 error = mem_cgroup_cache_charge(page, current->mm,
1202 gfp & GFP_RECLAIM_MASK);
1205 error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
1207 error = shmem_add_to_page_cache(page, mapping, index,
1209 radix_tree_preload_end();
1212 mem_cgroup_uncharge_cache_page(page);
1215 lru_cache_add_anon(page);
1217 spin_lock(&info->lock);
1219 inode->i_blocks += BLOCKS_PER_PAGE;
1220 shmem_recalc_inode(inode);
1221 spin_unlock(&info->lock);
1225 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1227 if (sgp == SGP_FALLOC)
1231 * Let SGP_WRITE caller clear ends if write does not fill page;
1232 * but SGP_FALLOC on a page fallocated earlier must initialize
1233 * it now, lest undo on failure cancel our earlier guarantee.
1235 if (sgp != SGP_WRITE) {
1236 clear_highpage(page);
1237 flush_dcache_page(page);
1238 SetPageUptodate(page);
1240 if (sgp == SGP_DIRTY)
1241 set_page_dirty(page);
1244 /* Perhaps the file has been truncated since we checked */
1245 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1246 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1260 info = SHMEM_I(inode);
1261 ClearPageDirty(page);
1262 delete_from_page_cache(page);
1263 spin_lock(&info->lock);
1265 inode->i_blocks -= BLOCKS_PER_PAGE;
1266 spin_unlock(&info->lock);
1268 sbinfo = SHMEM_SB(inode->i_sb);
1269 if (sbinfo->max_blocks)
1270 percpu_counter_add(&sbinfo->used_blocks, -1);
1272 shmem_unacct_blocks(info->flags, 1);
1274 if (swap.val && error != -EINVAL &&
1275 !shmem_confirm_swap(mapping, index, swap))
1280 page_cache_release(page);
1282 if (error == -ENOSPC && !once++) {
1283 info = SHMEM_I(inode);
1284 spin_lock(&info->lock);
1285 shmem_recalc_inode(inode);
1286 spin_unlock(&info->lock);
1289 if (error == -EEXIST) /* from above or from radix_tree_insert */
1294 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1296 struct inode *inode = file_inode(vma->vm_file);
1298 int ret = VM_FAULT_LOCKED;
1300 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1302 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1304 if (ret & VM_FAULT_MAJOR) {
1305 count_vm_event(PGMAJFAULT);
1306 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1312 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
1314 struct inode *inode = file_inode(vma->vm_file);
1315 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
1318 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1321 struct inode *inode = file_inode(vma->vm_file);
1324 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1325 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
1329 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1331 struct inode *inode = file_inode(file);
1332 struct shmem_inode_info *info = SHMEM_I(inode);
1333 int retval = -ENOMEM;
1335 spin_lock(&info->lock);
1336 if (lock && !(info->flags & VM_LOCKED)) {
1337 if (!user_shm_lock(inode->i_size, user))
1339 info->flags |= VM_LOCKED;
1340 mapping_set_unevictable(file->f_mapping);
1342 if (!lock && (info->flags & VM_LOCKED) && user) {
1343 user_shm_unlock(inode->i_size, user);
1344 info->flags &= ~VM_LOCKED;
1345 mapping_clear_unevictable(file->f_mapping);
1350 spin_unlock(&info->lock);
1354 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1356 file_accessed(file);
1357 vma->vm_ops = &shmem_vm_ops;
1361 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1362 umode_t mode, dev_t dev, unsigned long flags)
1364 struct inode *inode;
1365 struct shmem_inode_info *info;
1366 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1368 if (shmem_reserve_inode(sb))
1371 inode = new_inode(sb);
1373 inode->i_ino = get_next_ino();
1374 inode_init_owner(inode, dir, mode);
1375 inode->i_blocks = 0;
1376 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1377 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1378 inode->i_generation = get_seconds();
1379 info = SHMEM_I(inode);
1380 memset(info, 0, (char *)inode - (char *)info);
1381 spin_lock_init(&info->lock);
1382 info->flags = flags & VM_NORESERVE;
1383 INIT_LIST_HEAD(&info->swaplist);
1384 simple_xattrs_init(&info->xattrs);
1385 cache_no_acl(inode);
1387 switch (mode & S_IFMT) {
1389 inode->i_op = &shmem_special_inode_operations;
1390 init_special_inode(inode, mode, dev);
1393 inode->i_mapping->a_ops = &shmem_aops;
1394 inode->i_op = &shmem_inode_operations;
1395 inode->i_fop = &shmem_file_operations;
1396 mpol_shared_policy_init(&info->policy,
1397 shmem_get_sbmpol(sbinfo));
1401 /* Some things misbehave if size == 0 on a directory */
1402 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1403 inode->i_op = &shmem_dir_inode_operations;
1404 inode->i_fop = &simple_dir_operations;
1408 * Must not load anything in the rbtree,
1409 * mpol_free_shared_policy will not be called.
1411 mpol_shared_policy_init(&info->policy, NULL);
1415 shmem_free_inode(sb);
1420 static const struct inode_operations shmem_symlink_inode_operations;
1421 static const struct inode_operations shmem_short_symlink_operations;
1423 #ifdef CONFIG_TMPFS_XATTR
1424 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
1426 #define shmem_initxattrs NULL
1430 shmem_write_begin(struct file *file, struct address_space *mapping,
1431 loff_t pos, unsigned len, unsigned flags,
1432 struct page **pagep, void **fsdata)
1434 struct inode *inode = mapping->host;
1435 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1436 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1440 shmem_write_end(struct file *file, struct address_space *mapping,
1441 loff_t pos, unsigned len, unsigned copied,
1442 struct page *page, void *fsdata)
1444 struct inode *inode = mapping->host;
1446 if (pos + copied > inode->i_size)
1447 i_size_write(inode, pos + copied);
1449 if (!PageUptodate(page)) {
1450 if (copied < PAGE_CACHE_SIZE) {
1451 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1452 zero_user_segments(page, 0, from,
1453 from + copied, PAGE_CACHE_SIZE);
1455 SetPageUptodate(page);
1457 set_page_dirty(page);
1459 page_cache_release(page);
1464 static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1466 struct inode *inode = file_inode(filp);
1467 struct address_space *mapping = inode->i_mapping;
1469 unsigned long offset;
1470 enum sgp_type sgp = SGP_READ;
1473 * Might this read be for a stacking filesystem? Then when reading
1474 * holes of a sparse file, we actually need to allocate those pages,
1475 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1477 if (segment_eq(get_fs(), KERNEL_DS))
1480 index = *ppos >> PAGE_CACHE_SHIFT;
1481 offset = *ppos & ~PAGE_CACHE_MASK;
1484 struct page *page = NULL;
1486 unsigned long nr, ret;
1487 loff_t i_size = i_size_read(inode);
1489 end_index = i_size >> PAGE_CACHE_SHIFT;
1490 if (index > end_index)
1492 if (index == end_index) {
1493 nr = i_size & ~PAGE_CACHE_MASK;
1498 desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1500 if (desc->error == -EINVAL)
1508 * We must evaluate after, since reads (unlike writes)
1509 * are called without i_mutex protection against truncate
1511 nr = PAGE_CACHE_SIZE;
1512 i_size = i_size_read(inode);
1513 end_index = i_size >> PAGE_CACHE_SHIFT;
1514 if (index == end_index) {
1515 nr = i_size & ~PAGE_CACHE_MASK;
1518 page_cache_release(page);
1526 * If users can be writing to this page using arbitrary
1527 * virtual addresses, take care about potential aliasing
1528 * before reading the page on the kernel side.
1530 if (mapping_writably_mapped(mapping))
1531 flush_dcache_page(page);
1533 * Mark the page accessed if we read the beginning.
1536 mark_page_accessed(page);
1538 page = ZERO_PAGE(0);
1539 page_cache_get(page);
1543 * Ok, we have the page, and it's up-to-date, so
1544 * now we can copy it to user space...
1546 * The actor routine returns how many bytes were actually used..
1547 * NOTE! This may not be the same as how much of a user buffer
1548 * we filled up (we may be padding etc), so we can only update
1549 * "pos" here (the actor routine has to update the user buffer
1550 * pointers and the remaining count).
1552 ret = actor(desc, page, offset, nr);
1554 index += offset >> PAGE_CACHE_SHIFT;
1555 offset &= ~PAGE_CACHE_MASK;
1557 page_cache_release(page);
1558 if (ret != nr || !desc->count)
1564 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1565 file_accessed(filp);
1568 static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1569 const struct iovec *iov, unsigned long nr_segs, loff_t pos)
1571 struct file *filp = iocb->ki_filp;
1575 loff_t *ppos = &iocb->ki_pos;
1577 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1581 for (seg = 0; seg < nr_segs; seg++) {
1582 read_descriptor_t desc;
1585 desc.arg.buf = iov[seg].iov_base;
1586 desc.count = iov[seg].iov_len;
1587 if (desc.count == 0)
1590 do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1591 retval += desc.written;
1593 retval = retval ?: desc.error;
1602 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
1603 struct pipe_inode_info *pipe, size_t len,
1606 struct address_space *mapping = in->f_mapping;
1607 struct inode *inode = mapping->host;
1608 unsigned int loff, nr_pages, req_pages;
1609 struct page *pages[PIPE_DEF_BUFFERS];
1610 struct partial_page partial[PIPE_DEF_BUFFERS];
1612 pgoff_t index, end_index;
1615 struct splice_pipe_desc spd = {
1618 .nr_pages_max = PIPE_DEF_BUFFERS,
1620 .ops = &page_cache_pipe_buf_ops,
1621 .spd_release = spd_release_page,
1624 isize = i_size_read(inode);
1625 if (unlikely(*ppos >= isize))
1628 left = isize - *ppos;
1629 if (unlikely(left < len))
1632 if (splice_grow_spd(pipe, &spd))
1635 index = *ppos >> PAGE_CACHE_SHIFT;
1636 loff = *ppos & ~PAGE_CACHE_MASK;
1637 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1638 nr_pages = min(req_pages, pipe->buffers);
1640 spd.nr_pages = find_get_pages_contig(mapping, index,
1641 nr_pages, spd.pages);
1642 index += spd.nr_pages;
1645 while (spd.nr_pages < nr_pages) {
1646 error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
1650 spd.pages[spd.nr_pages++] = page;
1654 index = *ppos >> PAGE_CACHE_SHIFT;
1655 nr_pages = spd.nr_pages;
1658 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
1659 unsigned int this_len;
1664 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
1665 page = spd.pages[page_nr];
1667 if (!PageUptodate(page) || page->mapping != mapping) {
1668 error = shmem_getpage(inode, index, &page,
1673 page_cache_release(spd.pages[page_nr]);
1674 spd.pages[page_nr] = page;
1677 isize = i_size_read(inode);
1678 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1679 if (unlikely(!isize || index > end_index))
1682 if (end_index == index) {
1685 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1689 this_len = min(this_len, plen - loff);
1693 spd.partial[page_nr].offset = loff;
1694 spd.partial[page_nr].len = this_len;
1701 while (page_nr < nr_pages)
1702 page_cache_release(spd.pages[page_nr++]);
1705 error = splice_to_pipe(pipe, &spd);
1707 splice_shrink_spd(&spd);
1717 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1719 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
1720 pgoff_t index, pgoff_t end, int whence)
1723 struct pagevec pvec;
1724 pgoff_t indices[PAGEVEC_SIZE];
1728 pagevec_init(&pvec, 0);
1729 pvec.nr = 1; /* start small: we may be there already */
1731 pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
1732 pvec.nr, pvec.pages, indices);
1734 if (whence == SEEK_DATA)
1738 for (i = 0; i < pvec.nr; i++, index++) {
1739 if (index < indices[i]) {
1740 if (whence == SEEK_HOLE) {
1746 page = pvec.pages[i];
1747 if (page && !radix_tree_exceptional_entry(page)) {
1748 if (!PageUptodate(page))
1752 (page && whence == SEEK_DATA) ||
1753 (!page && whence == SEEK_HOLE)) {
1758 shmem_deswap_pagevec(&pvec);
1759 pagevec_release(&pvec);
1760 pvec.nr = PAGEVEC_SIZE;
1766 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
1768 struct address_space *mapping = file->f_mapping;
1769 struct inode *inode = mapping->host;
1773 if (whence != SEEK_DATA && whence != SEEK_HOLE)
1774 return generic_file_llseek_size(file, offset, whence,
1775 MAX_LFS_FILESIZE, i_size_read(inode));
1776 mutex_lock(&inode->i_mutex);
1777 /* We're holding i_mutex so we can access i_size directly */
1781 else if (offset >= inode->i_size)
1784 start = offset >> PAGE_CACHE_SHIFT;
1785 end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1786 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
1787 new_offset <<= PAGE_CACHE_SHIFT;
1788 if (new_offset > offset) {
1789 if (new_offset < inode->i_size)
1790 offset = new_offset;
1791 else if (whence == SEEK_DATA)
1794 offset = inode->i_size;
1799 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
1800 mutex_unlock(&inode->i_mutex);
1804 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
1807 struct inode *inode = file_inode(file);
1808 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1809 struct shmem_falloc shmem_falloc;
1810 pgoff_t start, index, end;
1813 mutex_lock(&inode->i_mutex);
1815 if (mode & FALLOC_FL_PUNCH_HOLE) {
1816 struct address_space *mapping = file->f_mapping;
1817 loff_t unmap_start = round_up(offset, PAGE_SIZE);
1818 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
1820 if ((u64)unmap_end > (u64)unmap_start)
1821 unmap_mapping_range(mapping, unmap_start,
1822 1 + unmap_end - unmap_start, 0);
1823 shmem_truncate_range(inode, offset, offset + len - 1);
1824 /* No need to unmap again: hole-punching leaves COWed pages */
1829 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1830 error = inode_newsize_ok(inode, offset + len);
1834 start = offset >> PAGE_CACHE_SHIFT;
1835 end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1836 /* Try to avoid a swapstorm if len is impossible to satisfy */
1837 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
1842 shmem_falloc.start = start;
1843 shmem_falloc.next = start;
1844 shmem_falloc.nr_falloced = 0;
1845 shmem_falloc.nr_unswapped = 0;
1846 spin_lock(&inode->i_lock);
1847 inode->i_private = &shmem_falloc;
1848 spin_unlock(&inode->i_lock);
1850 for (index = start; index < end; index++) {
1854 * Good, the fallocate(2) manpage permits EINTR: we may have
1855 * been interrupted because we are using up too much memory.
1857 if (signal_pending(current))
1859 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
1862 error = shmem_getpage(inode, index, &page, SGP_FALLOC,
1865 /* Remove the !PageUptodate pages we added */
1866 shmem_undo_range(inode,
1867 (loff_t)start << PAGE_CACHE_SHIFT,
1868 (loff_t)index << PAGE_CACHE_SHIFT, true);
1873 * Inform shmem_writepage() how far we have reached.
1874 * No need for lock or barrier: we have the page lock.
1876 shmem_falloc.next++;
1877 if (!PageUptodate(page))
1878 shmem_falloc.nr_falloced++;
1881 * If !PageUptodate, leave it that way so that freeable pages
1882 * can be recognized if we need to rollback on error later.
1883 * But set_page_dirty so that memory pressure will swap rather
1884 * than free the pages we are allocating (and SGP_CACHE pages
1885 * might still be clean: we now need to mark those dirty too).
1887 set_page_dirty(page);
1889 page_cache_release(page);
1893 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
1894 i_size_write(inode, offset + len);
1895 inode->i_ctime = CURRENT_TIME;
1897 spin_lock(&inode->i_lock);
1898 inode->i_private = NULL;
1899 spin_unlock(&inode->i_lock);
1901 mutex_unlock(&inode->i_mutex);
1905 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1907 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1909 buf->f_type = TMPFS_MAGIC;
1910 buf->f_bsize = PAGE_CACHE_SIZE;
1911 buf->f_namelen = NAME_MAX;
1912 if (sbinfo->max_blocks) {
1913 buf->f_blocks = sbinfo->max_blocks;
1915 buf->f_bfree = sbinfo->max_blocks -
1916 percpu_counter_sum(&sbinfo->used_blocks);
1918 if (sbinfo->max_inodes) {
1919 buf->f_files = sbinfo->max_inodes;
1920 buf->f_ffree = sbinfo->free_inodes;
1922 /* else leave those fields 0 like simple_statfs */
1927 * File creation. Allocate an inode, and we're done..
1930 shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1932 struct inode *inode;
1933 int error = -ENOSPC;
1935 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1937 error = simple_acl_create(dir, inode);
1940 error = security_inode_init_security(inode, dir,
1942 shmem_initxattrs, NULL);
1943 if (error && error != -EOPNOTSUPP)
1947 dir->i_size += BOGO_DIRENT_SIZE;
1948 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1949 d_instantiate(dentry, inode);
1950 dget(dentry); /* Extra count - pin the dentry in core */
1959 shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
1961 struct inode *inode;
1962 int error = -ENOSPC;
1964 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
1966 error = security_inode_init_security(inode, dir,
1968 shmem_initxattrs, NULL);
1969 if (error && error != -EOPNOTSUPP)
1971 error = simple_acl_create(dir, inode);
1974 d_tmpfile(dentry, inode);
1982 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
1986 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1992 static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
1995 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
2001 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2003 struct inode *inode = old_dentry->d_inode;
2007 * No ordinary (disk based) filesystem counts links as inodes;
2008 * but each new link needs a new dentry, pinning lowmem, and
2009 * tmpfs dentries cannot be pruned until they are unlinked.
2011 ret = shmem_reserve_inode(inode->i_sb);
2015 dir->i_size += BOGO_DIRENT_SIZE;
2016 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2018 ihold(inode); /* New dentry reference */
2019 dget(dentry); /* Extra pinning count for the created dentry */
2020 d_instantiate(dentry, inode);
2025 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2027 struct inode *inode = dentry->d_inode;
2029 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2030 shmem_free_inode(inode->i_sb);
2032 dir->i_size -= BOGO_DIRENT_SIZE;
2033 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2035 dput(dentry); /* Undo the count from "create" - this does all the work */
2039 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2041 if (!simple_empty(dentry))
2044 drop_nlink(dentry->d_inode);
2046 return shmem_unlink(dir, dentry);
2050 * The VFS layer already does all the dentry stuff for rename,
2051 * we just have to decrement the usage count for the target if
2052 * it exists so that the VFS layer correctly free's it when it
2055 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2057 struct inode *inode = old_dentry->d_inode;
2058 int they_are_dirs = S_ISDIR(inode->i_mode);
2060 if (!simple_empty(new_dentry))
2063 if (new_dentry->d_inode) {
2064 (void) shmem_unlink(new_dir, new_dentry);
2066 drop_nlink(old_dir);
2067 } else if (they_are_dirs) {
2068 drop_nlink(old_dir);
2072 old_dir->i_size -= BOGO_DIRENT_SIZE;
2073 new_dir->i_size += BOGO_DIRENT_SIZE;
2074 old_dir->i_ctime = old_dir->i_mtime =
2075 new_dir->i_ctime = new_dir->i_mtime =
2076 inode->i_ctime = CURRENT_TIME;
2080 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
2084 struct inode *inode;
2087 struct shmem_inode_info *info;
2089 len = strlen(symname) + 1;
2090 if (len > PAGE_CACHE_SIZE)
2091 return -ENAMETOOLONG;
2093 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
2097 error = security_inode_init_security(inode, dir, &dentry->d_name,
2098 shmem_initxattrs, NULL);
2100 if (error != -EOPNOTSUPP) {
2107 info = SHMEM_I(inode);
2108 inode->i_size = len-1;
2109 if (len <= SHORT_SYMLINK_LEN) {
2110 info->symlink = kmemdup(symname, len, GFP_KERNEL);
2111 if (!info->symlink) {
2115 inode->i_op = &shmem_short_symlink_operations;
2117 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2122 inode->i_mapping->a_ops = &shmem_aops;
2123 inode->i_op = &shmem_symlink_inode_operations;
2124 kaddr = kmap_atomic(page);
2125 memcpy(kaddr, symname, len);
2126 kunmap_atomic(kaddr);
2127 SetPageUptodate(page);
2128 set_page_dirty(page);
2130 page_cache_release(page);
2132 dir->i_size += BOGO_DIRENT_SIZE;
2133 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2134 d_instantiate(dentry, inode);
2139 static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
2141 nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
2145 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2147 struct page *page = NULL;
2148 int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2149 nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
2155 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2157 if (!IS_ERR(nd_get_link(nd))) {
2158 struct page *page = cookie;
2160 mark_page_accessed(page);
2161 page_cache_release(page);
2165 #ifdef CONFIG_TMPFS_XATTR
2167 * Superblocks without xattr inode operations may get some security.* xattr
2168 * support from the LSM "for free". As soon as we have any other xattrs
2169 * like ACLs, we also need to implement the security.* handlers at
2170 * filesystem level, though.
2174 * Callback for security_inode_init_security() for acquiring xattrs.
2176 static int shmem_initxattrs(struct inode *inode,
2177 const struct xattr *xattr_array,
2180 struct shmem_inode_info *info = SHMEM_I(inode);
2181 const struct xattr *xattr;
2182 struct simple_xattr *new_xattr;
2185 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
2186 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
2190 len = strlen(xattr->name) + 1;
2191 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
2193 if (!new_xattr->name) {
2198 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
2199 XATTR_SECURITY_PREFIX_LEN);
2200 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
2203 simple_xattr_list_add(&info->xattrs, new_xattr);
2209 static const struct xattr_handler *shmem_xattr_handlers[] = {
2210 #ifdef CONFIG_TMPFS_POSIX_ACL
2211 &posix_acl_access_xattr_handler,
2212 &posix_acl_default_xattr_handler,
2217 static int shmem_xattr_validate(const char *name)
2219 struct { const char *prefix; size_t len; } arr[] = {
2220 { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
2221 { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
2225 for (i = 0; i < ARRAY_SIZE(arr); i++) {
2226 size_t preflen = arr[i].len;
2227 if (strncmp(name, arr[i].prefix, preflen) == 0) {
2236 static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
2237 void *buffer, size_t size)
2239 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2243 * If this is a request for a synthetic attribute in the system.*
2244 * namespace use the generic infrastructure to resolve a handler
2245 * for it via sb->s_xattr.
2247 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2248 return generic_getxattr(dentry, name, buffer, size);
2250 err = shmem_xattr_validate(name);
2254 return simple_xattr_get(&info->xattrs, name, buffer, size);
2257 static int shmem_setxattr(struct dentry *dentry, const char *name,
2258 const void *value, size_t size, int flags)
2260 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2264 * If this is a request for a synthetic attribute in the system.*
2265 * namespace use the generic infrastructure to resolve a handler
2266 * for it via sb->s_xattr.
2268 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2269 return generic_setxattr(dentry, name, value, size, flags);
2271 err = shmem_xattr_validate(name);
2275 return simple_xattr_set(&info->xattrs, name, value, size, flags);
2278 static int shmem_removexattr(struct dentry *dentry, const char *name)
2280 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2284 * If this is a request for a synthetic attribute in the system.*
2285 * namespace use the generic infrastructure to resolve a handler
2286 * for it via sb->s_xattr.
2288 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2289 return generic_removexattr(dentry, name);
2291 err = shmem_xattr_validate(name);
2295 return simple_xattr_remove(&info->xattrs, name);
2298 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
2300 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2301 return simple_xattr_list(&info->xattrs, buffer, size);
2303 #endif /* CONFIG_TMPFS_XATTR */
2305 static const struct inode_operations shmem_short_symlink_operations = {
2306 .readlink = generic_readlink,
2307 .follow_link = shmem_follow_short_symlink,
2308 #ifdef CONFIG_TMPFS_XATTR
2309 .setxattr = shmem_setxattr,
2310 .getxattr = shmem_getxattr,
2311 .listxattr = shmem_listxattr,
2312 .removexattr = shmem_removexattr,
2316 static const struct inode_operations shmem_symlink_inode_operations = {
2317 .readlink = generic_readlink,
2318 .follow_link = shmem_follow_link,
2319 .put_link = shmem_put_link,
2320 #ifdef CONFIG_TMPFS_XATTR
2321 .setxattr = shmem_setxattr,
2322 .getxattr = shmem_getxattr,
2323 .listxattr = shmem_listxattr,
2324 .removexattr = shmem_removexattr,
2328 static struct dentry *shmem_get_parent(struct dentry *child)
2330 return ERR_PTR(-ESTALE);
2333 static int shmem_match(struct inode *ino, void *vfh)
2337 inum = (inum << 32) | fh[1];
2338 return ino->i_ino == inum && fh[0] == ino->i_generation;
2341 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2342 struct fid *fid, int fh_len, int fh_type)
2344 struct inode *inode;
2345 struct dentry *dentry = NULL;
2352 inum = (inum << 32) | fid->raw[1];
2354 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2355 shmem_match, fid->raw);
2357 dentry = d_find_alias(inode);
2364 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
2365 struct inode *parent)
2369 return FILEID_INVALID;
2372 if (inode_unhashed(inode)) {
2373 /* Unfortunately insert_inode_hash is not idempotent,
2374 * so as we hash inodes here rather than at creation
2375 * time, we need a lock to ensure we only try
2378 static DEFINE_SPINLOCK(lock);
2380 if (inode_unhashed(inode))
2381 __insert_inode_hash(inode,
2382 inode->i_ino + inode->i_generation);
2386 fh[0] = inode->i_generation;
2387 fh[1] = inode->i_ino;
2388 fh[2] = ((__u64)inode->i_ino) >> 32;
2394 static const struct export_operations shmem_export_ops = {
2395 .get_parent = shmem_get_parent,
2396 .encode_fh = shmem_encode_fh,
2397 .fh_to_dentry = shmem_fh_to_dentry,
2400 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2403 char *this_char, *value, *rest;
2404 struct mempolicy *mpol = NULL;
2408 while (options != NULL) {
2409 this_char = options;
2412 * NUL-terminate this option: unfortunately,
2413 * mount options form a comma-separated list,
2414 * but mpol's nodelist may also contain commas.
2416 options = strchr(options, ',');
2417 if (options == NULL)
2420 if (!isdigit(*options)) {
2427 if ((value = strchr(this_char,'=')) != NULL) {
2431 "tmpfs: No value for mount option '%s'\n",
2436 if (!strcmp(this_char,"size")) {
2437 unsigned long long size;
2438 size = memparse(value,&rest);
2440 size <<= PAGE_SHIFT;
2441 size *= totalram_pages;
2447 sbinfo->max_blocks =
2448 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2449 } else if (!strcmp(this_char,"nr_blocks")) {
2450 sbinfo->max_blocks = memparse(value, &rest);
2453 } else if (!strcmp(this_char,"nr_inodes")) {
2454 sbinfo->max_inodes = memparse(value, &rest);
2457 } else if (!strcmp(this_char,"mode")) {
2460 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2463 } else if (!strcmp(this_char,"uid")) {
2466 uid = simple_strtoul(value, &rest, 0);
2469 sbinfo->uid = make_kuid(current_user_ns(), uid);
2470 if (!uid_valid(sbinfo->uid))
2472 } else if (!strcmp(this_char,"gid")) {
2475 gid = simple_strtoul(value, &rest, 0);
2478 sbinfo->gid = make_kgid(current_user_ns(), gid);
2479 if (!gid_valid(sbinfo->gid))
2481 } else if (!strcmp(this_char,"mpol")) {
2484 if (mpol_parse_str(value, &mpol))
2487 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2492 sbinfo->mpol = mpol;
2496 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2504 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2506 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2507 struct shmem_sb_info config = *sbinfo;
2508 unsigned long inodes;
2509 int error = -EINVAL;
2512 if (shmem_parse_options(data, &config, true))
2515 spin_lock(&sbinfo->stat_lock);
2516 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2517 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2519 if (config.max_inodes < inodes)
2522 * Those tests disallow limited->unlimited while any are in use;
2523 * but we must separately disallow unlimited->limited, because
2524 * in that case we have no record of how much is already in use.
2526 if (config.max_blocks && !sbinfo->max_blocks)
2528 if (config.max_inodes && !sbinfo->max_inodes)
2532 sbinfo->max_blocks = config.max_blocks;
2533 sbinfo->max_inodes = config.max_inodes;
2534 sbinfo->free_inodes = config.max_inodes - inodes;
2537 * Preserve previous mempolicy unless mpol remount option was specified.
2540 mpol_put(sbinfo->mpol);
2541 sbinfo->mpol = config.mpol; /* transfers initial ref */
2544 spin_unlock(&sbinfo->stat_lock);
2548 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
2550 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
2552 if (sbinfo->max_blocks != shmem_default_max_blocks())
2553 seq_printf(seq, ",size=%luk",
2554 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2555 if (sbinfo->max_inodes != shmem_default_max_inodes())
2556 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2557 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2558 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
2559 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
2560 seq_printf(seq, ",uid=%u",
2561 from_kuid_munged(&init_user_ns, sbinfo->uid));
2562 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
2563 seq_printf(seq, ",gid=%u",
2564 from_kgid_munged(&init_user_ns, sbinfo->gid));
2565 shmem_show_mpol(seq, sbinfo->mpol);
2568 #endif /* CONFIG_TMPFS */
2570 static void shmem_put_super(struct super_block *sb)
2572 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2574 percpu_counter_destroy(&sbinfo->used_blocks);
2575 mpol_put(sbinfo->mpol);
2577 sb->s_fs_info = NULL;
2580 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2582 struct inode *inode;
2583 struct shmem_sb_info *sbinfo;
2586 /* Round up to L1_CACHE_BYTES to resist false sharing */
2587 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2588 L1_CACHE_BYTES), GFP_KERNEL);
2592 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2593 sbinfo->uid = current_fsuid();
2594 sbinfo->gid = current_fsgid();
2595 sb->s_fs_info = sbinfo;
2599 * Per default we only allow half of the physical ram per
2600 * tmpfs instance, limiting inodes to one per page of lowmem;
2601 * but the internal instance is left unlimited.
2603 if (!(sb->s_flags & MS_KERNMOUNT)) {
2604 sbinfo->max_blocks = shmem_default_max_blocks();
2605 sbinfo->max_inodes = shmem_default_max_inodes();
2606 if (shmem_parse_options(data, sbinfo, false)) {
2611 sb->s_flags |= MS_NOUSER;
2613 sb->s_export_op = &shmem_export_ops;
2614 sb->s_flags |= MS_NOSEC;
2616 sb->s_flags |= MS_NOUSER;
2619 spin_lock_init(&sbinfo->stat_lock);
2620 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2622 sbinfo->free_inodes = sbinfo->max_inodes;
2624 sb->s_maxbytes = MAX_LFS_FILESIZE;
2625 sb->s_blocksize = PAGE_CACHE_SIZE;
2626 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2627 sb->s_magic = TMPFS_MAGIC;
2628 sb->s_op = &shmem_ops;
2629 sb->s_time_gran = 1;
2630 #ifdef CONFIG_TMPFS_XATTR
2631 sb->s_xattr = shmem_xattr_handlers;
2633 #ifdef CONFIG_TMPFS_POSIX_ACL
2634 sb->s_flags |= MS_POSIXACL;
2637 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2640 inode->i_uid = sbinfo->uid;
2641 inode->i_gid = sbinfo->gid;
2642 sb->s_root = d_make_root(inode);
2648 shmem_put_super(sb);
2652 static struct kmem_cache *shmem_inode_cachep;
2654 static struct inode *shmem_alloc_inode(struct super_block *sb)
2656 struct shmem_inode_info *info;
2657 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2660 return &info->vfs_inode;
2663 static void shmem_destroy_callback(struct rcu_head *head)
2665 struct inode *inode = container_of(head, struct inode, i_rcu);
2666 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2669 static void shmem_destroy_inode(struct inode *inode)
2671 if (S_ISREG(inode->i_mode))
2672 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2673 call_rcu(&inode->i_rcu, shmem_destroy_callback);
2676 static void shmem_init_inode(void *foo)
2678 struct shmem_inode_info *info = foo;
2679 inode_init_once(&info->vfs_inode);
2682 static int shmem_init_inodecache(void)
2684 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2685 sizeof(struct shmem_inode_info),
2686 0, SLAB_PANIC, shmem_init_inode);
2690 static void shmem_destroy_inodecache(void)
2692 kmem_cache_destroy(shmem_inode_cachep);
2695 static const struct address_space_operations shmem_aops = {
2696 .writepage = shmem_writepage,
2697 .set_page_dirty = __set_page_dirty_no_writeback,
2699 .write_begin = shmem_write_begin,
2700 .write_end = shmem_write_end,
2702 .migratepage = migrate_page,
2703 .error_remove_page = generic_error_remove_page,
2706 static const struct file_operations shmem_file_operations = {
2709 .llseek = shmem_file_llseek,
2710 .read = do_sync_read,
2711 .write = do_sync_write,
2712 .aio_read = shmem_file_aio_read,
2713 .aio_write = generic_file_aio_write,
2714 .fsync = noop_fsync,
2715 .splice_read = shmem_file_splice_read,
2716 .splice_write = generic_file_splice_write,
2717 .fallocate = shmem_fallocate,
2721 static const struct inode_operations shmem_inode_operations = {
2722 .setattr = shmem_setattr,
2723 #ifdef CONFIG_TMPFS_XATTR
2724 .setxattr = shmem_setxattr,
2725 .getxattr = shmem_getxattr,
2726 .listxattr = shmem_listxattr,
2727 .removexattr = shmem_removexattr,
2728 .set_acl = simple_set_acl,
2732 static const struct inode_operations shmem_dir_inode_operations = {
2734 .create = shmem_create,
2735 .lookup = simple_lookup,
2737 .unlink = shmem_unlink,
2738 .symlink = shmem_symlink,
2739 .mkdir = shmem_mkdir,
2740 .rmdir = shmem_rmdir,
2741 .mknod = shmem_mknod,
2742 .rename = shmem_rename,
2743 .tmpfile = shmem_tmpfile,
2745 #ifdef CONFIG_TMPFS_XATTR
2746 .setxattr = shmem_setxattr,
2747 .getxattr = shmem_getxattr,
2748 .listxattr = shmem_listxattr,
2749 .removexattr = shmem_removexattr,
2751 #ifdef CONFIG_TMPFS_POSIX_ACL
2752 .setattr = shmem_setattr,
2753 .set_acl = simple_set_acl,
2757 static const struct inode_operations shmem_special_inode_operations = {
2758 #ifdef CONFIG_TMPFS_XATTR
2759 .setxattr = shmem_setxattr,
2760 .getxattr = shmem_getxattr,
2761 .listxattr = shmem_listxattr,
2762 .removexattr = shmem_removexattr,
2764 #ifdef CONFIG_TMPFS_POSIX_ACL
2765 .setattr = shmem_setattr,
2766 .set_acl = simple_set_acl,
2770 static const struct super_operations shmem_ops = {
2771 .alloc_inode = shmem_alloc_inode,
2772 .destroy_inode = shmem_destroy_inode,
2774 .statfs = shmem_statfs,
2775 .remount_fs = shmem_remount_fs,
2776 .show_options = shmem_show_options,
2778 .evict_inode = shmem_evict_inode,
2779 .drop_inode = generic_delete_inode,
2780 .put_super = shmem_put_super,
2783 static const struct vm_operations_struct shmem_vm_ops = {
2784 .fault = shmem_fault,
2786 .set_policy = shmem_set_policy,
2787 .get_policy = shmem_get_policy,
2789 .remap_pages = generic_file_remap_pages,
2792 static struct dentry *shmem_mount(struct file_system_type *fs_type,
2793 int flags, const char *dev_name, void *data)
2795 return mount_nodev(fs_type, flags, data, shmem_fill_super);
2798 static struct file_system_type shmem_fs_type = {
2799 .owner = THIS_MODULE,
2801 .mount = shmem_mount,
2802 .kill_sb = kill_litter_super,
2803 .fs_flags = FS_USERNS_MOUNT,
2806 int __init shmem_init(void)
2810 /* If rootfs called this, don't re-init */
2811 if (shmem_inode_cachep)
2814 error = bdi_init(&shmem_backing_dev_info);
2818 error = shmem_init_inodecache();
2822 error = register_filesystem(&shmem_fs_type);
2824 printk(KERN_ERR "Could not register tmpfs\n");
2828 shm_mnt = kern_mount(&shmem_fs_type);
2829 if (IS_ERR(shm_mnt)) {
2830 error = PTR_ERR(shm_mnt);
2831 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2837 unregister_filesystem(&shmem_fs_type);
2839 shmem_destroy_inodecache();
2841 bdi_destroy(&shmem_backing_dev_info);
2843 shm_mnt = ERR_PTR(error);
2847 #else /* !CONFIG_SHMEM */
2850 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2852 * This is intended for small system where the benefits of the full
2853 * shmem code (swap-backed and resource-limited) are outweighed by
2854 * their complexity. On systems without swap this code should be
2855 * effectively equivalent, but much lighter weight.
2858 static struct file_system_type shmem_fs_type = {
2860 .mount = ramfs_mount,
2861 .kill_sb = kill_litter_super,
2862 .fs_flags = FS_USERNS_MOUNT,
2865 int __init shmem_init(void)
2867 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
2869 shm_mnt = kern_mount(&shmem_fs_type);
2870 BUG_ON(IS_ERR(shm_mnt));
2875 int shmem_unuse(swp_entry_t swap, struct page *page)
2880 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2885 void shmem_unlock_mapping(struct address_space *mapping)
2889 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
2891 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
2893 EXPORT_SYMBOL_GPL(shmem_truncate_range);
2895 #define shmem_vm_ops generic_file_vm_ops
2896 #define shmem_file_operations ramfs_file_operations
2897 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2898 #define shmem_acct_size(flags, size) 0
2899 #define shmem_unacct_size(flags, size) do {} while (0)
2901 #endif /* CONFIG_SHMEM */
2905 static struct dentry_operations anon_ops = {
2906 .d_dname = simple_dname
2909 static struct file *__shmem_file_setup(const char *name, loff_t size,
2910 unsigned long flags, unsigned int i_flags)
2913 struct inode *inode;
2915 struct super_block *sb;
2918 if (IS_ERR(shm_mnt))
2919 return ERR_CAST(shm_mnt);
2921 if (size < 0 || size > MAX_LFS_FILESIZE)
2922 return ERR_PTR(-EINVAL);
2924 if (shmem_acct_size(flags, size))
2925 return ERR_PTR(-ENOMEM);
2927 res = ERR_PTR(-ENOMEM);
2929 this.len = strlen(name);
2930 this.hash = 0; /* will go */
2931 sb = shm_mnt->mnt_sb;
2932 path.dentry = d_alloc_pseudo(sb, &this);
2935 d_set_d_op(path.dentry, &anon_ops);
2936 path.mnt = mntget(shm_mnt);
2938 res = ERR_PTR(-ENOSPC);
2939 inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2943 inode->i_flags |= i_flags;
2944 d_instantiate(path.dentry, inode);
2945 inode->i_size = size;
2946 clear_nlink(inode); /* It is unlinked */
2947 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
2951 res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2952 &shmem_file_operations);
2961 shmem_unacct_size(flags, size);
2966 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
2967 * kernel internal. There will be NO LSM permission checks against the
2968 * underlying inode. So users of this interface must do LSM checks at a
2969 * higher layer. The one user is the big_key implementation. LSM checks
2970 * are provided at the key level rather than the inode level.
2971 * @name: name for dentry (to be seen in /proc/<pid>/maps
2972 * @size: size to be set for the file
2973 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2975 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
2977 return __shmem_file_setup(name, size, flags, S_PRIVATE);
2981 * shmem_file_setup - get an unlinked file living in tmpfs
2982 * @name: name for dentry (to be seen in /proc/<pid>/maps
2983 * @size: size to be set for the file
2984 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2986 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2988 return __shmem_file_setup(name, size, flags, 0);
2990 EXPORT_SYMBOL_GPL(shmem_file_setup);
2993 * shmem_zero_setup - setup a shared anonymous mapping
2994 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2996 int shmem_zero_setup(struct vm_area_struct *vma)
2999 loff_t size = vma->vm_end - vma->vm_start;
3001 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
3003 return PTR_ERR(file);
3007 vma->vm_file = file;
3008 vma->vm_ops = &shmem_vm_ops;
3013 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
3014 * @mapping: the page's address_space
3015 * @index: the page index
3016 * @gfp: the page allocator flags to use if allocating
3018 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
3019 * with any new page allocations done using the specified allocation flags.
3020 * But read_cache_page_gfp() uses the ->readpage() method: which does not
3021 * suit tmpfs, since it may have pages in swapcache, and needs to find those
3022 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
3024 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
3025 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
3027 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
3028 pgoff_t index, gfp_t gfp)
3031 struct inode *inode = mapping->host;
3035 BUG_ON(mapping->a_ops != &shmem_aops);
3036 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
3038 page = ERR_PTR(error);
3044 * The tiny !SHMEM case uses ramfs without swap
3046 return read_cache_page_gfp(mapping, index, gfp);
3049 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);