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 communicates with shmem_fault or shmem_writepage via
84 * inode->i_private (with i_mutex making sure that it has only one user at
85 * a time): we would prefer not to enlarge the shmem inode just for that.
88 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
89 pgoff_t start; /* start of range currently being fallocated */
90 pgoff_t next; /* the next page offset to be fallocated */
91 pgoff_t nr_falloced; /* how many new pages have been fallocated */
92 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
95 /* Flag allocation requirements to shmem_getpage */
97 SGP_READ, /* don't exceed i_size, don't allocate page */
98 SGP_CACHE, /* don't exceed i_size, may allocate page */
99 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
100 SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
101 SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
105 static unsigned long shmem_default_max_blocks(void)
107 return totalram_pages / 2;
110 static unsigned long shmem_default_max_inodes(void)
112 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
116 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
117 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
118 struct shmem_inode_info *info, pgoff_t index);
119 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
120 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
122 static inline int shmem_getpage(struct inode *inode, pgoff_t index,
123 struct page **pagep, enum sgp_type sgp, int *fault_type)
125 return shmem_getpage_gfp(inode, index, pagep, sgp,
126 mapping_gfp_mask(inode->i_mapping), fault_type);
129 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
131 return sb->s_fs_info;
135 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
136 * for shared memory and for shared anonymous (/dev/zero) mappings
137 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
138 * consistent with the pre-accounting of private mappings ...
140 static inline int shmem_acct_size(unsigned long flags, loff_t size)
142 return (flags & VM_NORESERVE) ?
143 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
146 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
148 if (!(flags & VM_NORESERVE))
149 vm_unacct_memory(VM_ACCT(size));
152 static inline int shmem_reacct_size(unsigned long flags,
153 loff_t oldsize, loff_t newsize)
155 if (!(flags & VM_NORESERVE)) {
156 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
157 return security_vm_enough_memory_mm(current->mm,
158 VM_ACCT(newsize) - VM_ACCT(oldsize));
159 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
160 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
166 * ... whereas tmpfs objects are accounted incrementally as
167 * pages are allocated, in order to allow huge sparse files.
168 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
169 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
171 static inline int shmem_acct_block(unsigned long flags)
173 return (flags & VM_NORESERVE) ?
174 security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
177 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
179 if (flags & VM_NORESERVE)
180 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
183 static const struct super_operations shmem_ops;
184 static const struct address_space_operations shmem_aops;
185 static const struct file_operations shmem_file_operations;
186 static const struct inode_operations shmem_inode_operations;
187 static const struct inode_operations shmem_dir_inode_operations;
188 static const struct inode_operations shmem_special_inode_operations;
189 static const struct vm_operations_struct shmem_vm_ops;
191 static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
192 .ra_pages = 0, /* No readahead */
193 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
196 static LIST_HEAD(shmem_swaplist);
197 static DEFINE_MUTEX(shmem_swaplist_mutex);
199 static int shmem_reserve_inode(struct super_block *sb)
201 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
202 if (sbinfo->max_inodes) {
203 spin_lock(&sbinfo->stat_lock);
204 if (!sbinfo->free_inodes) {
205 spin_unlock(&sbinfo->stat_lock);
208 sbinfo->free_inodes--;
209 spin_unlock(&sbinfo->stat_lock);
214 static void shmem_free_inode(struct super_block *sb)
216 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
217 if (sbinfo->max_inodes) {
218 spin_lock(&sbinfo->stat_lock);
219 sbinfo->free_inodes++;
220 spin_unlock(&sbinfo->stat_lock);
225 * shmem_recalc_inode - recalculate the block usage of an inode
226 * @inode: inode to recalc
228 * We have to calculate the free blocks since the mm can drop
229 * undirtied hole pages behind our back.
231 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
232 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
234 * It has to be called with the spinlock held.
236 static void shmem_recalc_inode(struct inode *inode)
238 struct shmem_inode_info *info = SHMEM_I(inode);
241 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
243 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
244 if (sbinfo->max_blocks)
245 percpu_counter_add(&sbinfo->used_blocks, -freed);
246 info->alloced -= freed;
247 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
248 shmem_unacct_blocks(info->flags, freed);
253 * Replace item expected in radix tree by a new item, while holding tree lock.
255 static int shmem_radix_tree_replace(struct address_space *mapping,
256 pgoff_t index, void *expected, void *replacement)
261 VM_BUG_ON(!expected);
262 VM_BUG_ON(!replacement);
263 pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
266 item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
267 if (item != expected)
269 radix_tree_replace_slot(pslot, replacement);
274 * Sometimes, before we decide whether to proceed or to fail, we must check
275 * that an entry was not already brought back from swap by a racing thread.
277 * Checking page is not enough: by the time a SwapCache page is locked, it
278 * might be reused, and again be SwapCache, using the same swap as before.
280 static bool shmem_confirm_swap(struct address_space *mapping,
281 pgoff_t index, swp_entry_t swap)
286 item = radix_tree_lookup(&mapping->page_tree, index);
288 return item == swp_to_radix_entry(swap);
292 * Like add_to_page_cache_locked, but error if expected item has gone.
294 static int shmem_add_to_page_cache(struct page *page,
295 struct address_space *mapping,
296 pgoff_t index, void *expected)
300 VM_BUG_ON_PAGE(!PageLocked(page), page);
301 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
303 page_cache_get(page);
304 page->mapping = mapping;
307 spin_lock_irq(&mapping->tree_lock);
309 error = radix_tree_insert(&mapping->page_tree, index, page);
311 error = shmem_radix_tree_replace(mapping, index, expected,
315 __inc_zone_page_state(page, NR_FILE_PAGES);
316 __inc_zone_page_state(page, NR_SHMEM);
317 spin_unlock_irq(&mapping->tree_lock);
319 page->mapping = NULL;
320 spin_unlock_irq(&mapping->tree_lock);
321 page_cache_release(page);
327 * Like delete_from_page_cache, but substitutes swap for page.
329 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
331 struct address_space *mapping = page->mapping;
334 spin_lock_irq(&mapping->tree_lock);
335 error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
336 page->mapping = NULL;
338 __dec_zone_page_state(page, NR_FILE_PAGES);
339 __dec_zone_page_state(page, NR_SHMEM);
340 spin_unlock_irq(&mapping->tree_lock);
341 page_cache_release(page);
346 * Remove swap entry from radix tree, free the swap and its page cache.
348 static int shmem_free_swap(struct address_space *mapping,
349 pgoff_t index, void *radswap)
353 spin_lock_irq(&mapping->tree_lock);
354 old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
355 spin_unlock_irq(&mapping->tree_lock);
358 free_swap_and_cache(radix_to_swp_entry(radswap));
363 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
365 void shmem_unlock_mapping(struct address_space *mapping)
368 pgoff_t indices[PAGEVEC_SIZE];
371 pagevec_init(&pvec, 0);
373 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
375 while (!mapping_unevictable(mapping)) {
377 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
378 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
380 pvec.nr = find_get_entries(mapping, index,
381 PAGEVEC_SIZE, pvec.pages, indices);
384 index = indices[pvec.nr - 1] + 1;
385 pagevec_remove_exceptionals(&pvec);
386 check_move_unevictable_pages(pvec.pages, pvec.nr);
387 pagevec_release(&pvec);
393 * Remove range of pages and swap entries from radix tree, and free them.
394 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
396 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
399 struct address_space *mapping = inode->i_mapping;
400 struct shmem_inode_info *info = SHMEM_I(inode);
401 pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
402 pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
403 unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
404 unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
406 pgoff_t indices[PAGEVEC_SIZE];
407 long nr_swaps_freed = 0;
412 end = -1; /* unsigned, so actually very big */
414 pagevec_init(&pvec, 0);
416 while (index < end) {
417 pvec.nr = find_get_entries(mapping, index,
418 min(end - index, (pgoff_t)PAGEVEC_SIZE),
419 pvec.pages, indices);
422 mem_cgroup_uncharge_start();
423 for (i = 0; i < pagevec_count(&pvec); i++) {
424 struct page *page = pvec.pages[i];
430 if (radix_tree_exceptional_entry(page)) {
433 nr_swaps_freed += !shmem_free_swap(mapping,
438 if (!trylock_page(page))
440 if (!unfalloc || !PageUptodate(page)) {
441 if (page->mapping == mapping) {
442 VM_BUG_ON_PAGE(PageWriteback(page), page);
443 truncate_inode_page(mapping, page);
448 pagevec_remove_exceptionals(&pvec);
449 pagevec_release(&pvec);
450 mem_cgroup_uncharge_end();
456 struct page *page = NULL;
457 shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
459 unsigned int top = PAGE_CACHE_SIZE;
464 zero_user_segment(page, partial_start, top);
465 set_page_dirty(page);
467 page_cache_release(page);
471 struct page *page = NULL;
472 shmem_getpage(inode, end, &page, SGP_READ, NULL);
474 zero_user_segment(page, 0, partial_end);
475 set_page_dirty(page);
477 page_cache_release(page);
484 while (index < end) {
487 pvec.nr = find_get_entries(mapping, index,
488 min(end - index, (pgoff_t)PAGEVEC_SIZE),
489 pvec.pages, indices);
491 /* If all gone or hole-punch or unfalloc, we're done */
492 if (index == start || end != -1)
494 /* But if truncating, restart to make sure all gone */
498 mem_cgroup_uncharge_start();
499 for (i = 0; i < pagevec_count(&pvec); i++) {
500 struct page *page = pvec.pages[i];
506 if (radix_tree_exceptional_entry(page)) {
509 if (shmem_free_swap(mapping, index, page)) {
510 /* Swap was replaced by page: retry */
519 if (!unfalloc || !PageUptodate(page)) {
520 if (page->mapping == mapping) {
521 VM_BUG_ON_PAGE(PageWriteback(page), page);
522 truncate_inode_page(mapping, page);
524 /* Page was replaced by swap: retry */
532 pagevec_remove_exceptionals(&pvec);
533 pagevec_release(&pvec);
534 mem_cgroup_uncharge_end();
538 spin_lock(&info->lock);
539 info->swapped -= nr_swaps_freed;
540 shmem_recalc_inode(inode);
541 spin_unlock(&info->lock);
544 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
546 shmem_undo_range(inode, lstart, lend, false);
547 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
549 EXPORT_SYMBOL_GPL(shmem_truncate_range);
551 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
553 struct inode *inode = dentry->d_inode;
556 error = inode_change_ok(inode, attr);
560 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
561 loff_t oldsize = inode->i_size;
562 loff_t newsize = attr->ia_size;
564 if (newsize != oldsize) {
565 error = shmem_reacct_size(SHMEM_I(inode)->flags,
569 i_size_write(inode, newsize);
570 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
572 if (newsize < oldsize) {
573 loff_t holebegin = round_up(newsize, PAGE_SIZE);
574 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
575 shmem_truncate_range(inode, newsize, (loff_t)-1);
576 /* unmap again to remove racily COWed private pages */
577 unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
581 setattr_copy(inode, attr);
582 if (attr->ia_valid & ATTR_MODE)
583 error = posix_acl_chmod(inode, inode->i_mode);
587 static void shmem_evict_inode(struct inode *inode)
589 struct shmem_inode_info *info = SHMEM_I(inode);
591 if (inode->i_mapping->a_ops == &shmem_aops) {
592 shmem_unacct_size(info->flags, inode->i_size);
594 shmem_truncate_range(inode, 0, (loff_t)-1);
595 if (!list_empty(&info->swaplist)) {
596 mutex_lock(&shmem_swaplist_mutex);
597 list_del_init(&info->swaplist);
598 mutex_unlock(&shmem_swaplist_mutex);
601 kfree(info->symlink);
603 simple_xattrs_free(&info->xattrs);
604 WARN_ON(inode->i_blocks);
605 shmem_free_inode(inode->i_sb);
610 * If swap found in inode, free it and move page from swapcache to filecache.
612 static int shmem_unuse_inode(struct shmem_inode_info *info,
613 swp_entry_t swap, struct page **pagep)
615 struct address_space *mapping = info->vfs_inode.i_mapping;
621 radswap = swp_to_radix_entry(swap);
622 index = radix_tree_locate_item(&mapping->page_tree, radswap);
627 * Move _head_ to start search for next from here.
628 * But be careful: shmem_evict_inode checks list_empty without taking
629 * mutex, and there's an instant in list_move_tail when info->swaplist
630 * would appear empty, if it were the only one on shmem_swaplist.
632 if (shmem_swaplist.next != &info->swaplist)
633 list_move_tail(&shmem_swaplist, &info->swaplist);
635 gfp = mapping_gfp_mask(mapping);
636 if (shmem_should_replace_page(*pagep, gfp)) {
637 mutex_unlock(&shmem_swaplist_mutex);
638 error = shmem_replace_page(pagep, gfp, info, index);
639 mutex_lock(&shmem_swaplist_mutex);
641 * We needed to drop mutex to make that restrictive page
642 * allocation, but the inode might have been freed while we
643 * dropped it: although a racing shmem_evict_inode() cannot
644 * complete without emptying the radix_tree, our page lock
645 * on this swapcache page is not enough to prevent that -
646 * free_swap_and_cache() of our swap entry will only
647 * trylock_page(), removing swap from radix_tree whatever.
649 * We must not proceed to shmem_add_to_page_cache() if the
650 * inode has been freed, but of course we cannot rely on
651 * inode or mapping or info to check that. However, we can
652 * safely check if our swap entry is still in use (and here
653 * it can't have got reused for another page): if it's still
654 * in use, then the inode cannot have been freed yet, and we
655 * can safely proceed (if it's no longer in use, that tells
656 * nothing about the inode, but we don't need to unuse swap).
658 if (!page_swapcount(*pagep))
663 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
664 * but also to hold up shmem_evict_inode(): so inode cannot be freed
665 * beneath us (pagelock doesn't help until the page is in pagecache).
668 error = shmem_add_to_page_cache(*pagep, mapping, index,
670 if (error != -ENOMEM) {
672 * Truncation and eviction use free_swap_and_cache(), which
673 * only does trylock page: if we raced, best clean up here.
675 delete_from_swap_cache(*pagep);
676 set_page_dirty(*pagep);
678 spin_lock(&info->lock);
680 spin_unlock(&info->lock);
683 error = 1; /* not an error, but entry was found */
689 * Search through swapped inodes to find and replace swap by page.
691 int shmem_unuse(swp_entry_t swap, struct page *page)
693 struct list_head *this, *next;
694 struct shmem_inode_info *info;
699 * There's a faint possibility that swap page was replaced before
700 * caller locked it: caller will come back later with the right page.
702 if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
706 * Charge page using GFP_KERNEL while we can wait, before taking
707 * the shmem_swaplist_mutex which might hold up shmem_writepage().
708 * Charged back to the user (not to caller) when swap account is used.
710 error = mem_cgroup_charge_file(page, current->mm, GFP_KERNEL);
713 /* No radix_tree_preload: swap entry keeps a place for page in tree */
715 mutex_lock(&shmem_swaplist_mutex);
716 list_for_each_safe(this, next, &shmem_swaplist) {
717 info = list_entry(this, struct shmem_inode_info, swaplist);
719 found = shmem_unuse_inode(info, swap, &page);
721 list_del_init(&info->swaplist);
726 mutex_unlock(&shmem_swaplist_mutex);
732 page_cache_release(page);
737 * Move the page from the page cache to the swap cache.
739 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
741 struct shmem_inode_info *info;
742 struct address_space *mapping;
747 BUG_ON(!PageLocked(page));
748 mapping = page->mapping;
750 inode = mapping->host;
751 info = SHMEM_I(inode);
752 if (info->flags & VM_LOCKED)
754 if (!total_swap_pages)
758 * shmem_backing_dev_info's capabilities prevent regular writeback or
759 * sync from ever calling shmem_writepage; but a stacking filesystem
760 * might use ->writepage of its underlying filesystem, in which case
761 * tmpfs should write out to swap only in response to memory pressure,
762 * and not for the writeback threads or sync.
764 if (!wbc->for_reclaim) {
765 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
770 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
771 * value into swapfile.c, the only way we can correctly account for a
772 * fallocated page arriving here is now to initialize it and write it.
774 * That's okay for a page already fallocated earlier, but if we have
775 * not yet completed the fallocation, then (a) we want to keep track
776 * of this page in case we have to undo it, and (b) it may not be a
777 * good idea to continue anyway, once we're pushing into swap. So
778 * reactivate the page, and let shmem_fallocate() quit when too many.
780 if (!PageUptodate(page)) {
781 if (inode->i_private) {
782 struct shmem_falloc *shmem_falloc;
783 spin_lock(&inode->i_lock);
784 shmem_falloc = inode->i_private;
786 !shmem_falloc->waitq &&
787 index >= shmem_falloc->start &&
788 index < shmem_falloc->next)
789 shmem_falloc->nr_unswapped++;
792 spin_unlock(&inode->i_lock);
796 clear_highpage(page);
797 flush_dcache_page(page);
798 SetPageUptodate(page);
801 swap = get_swap_page();
806 * Add inode to shmem_unuse()'s list of swapped-out inodes,
807 * if it's not already there. Do it now before the page is
808 * moved to swap cache, when its pagelock no longer protects
809 * the inode from eviction. But don't unlock the mutex until
810 * we've incremented swapped, because shmem_unuse_inode() will
811 * prune a !swapped inode from the swaplist under this mutex.
813 mutex_lock(&shmem_swaplist_mutex);
814 if (list_empty(&info->swaplist))
815 list_add_tail(&info->swaplist, &shmem_swaplist);
817 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
818 swap_shmem_alloc(swap);
819 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
821 spin_lock(&info->lock);
823 shmem_recalc_inode(inode);
824 spin_unlock(&info->lock);
826 mutex_unlock(&shmem_swaplist_mutex);
827 BUG_ON(page_mapped(page));
828 swap_writepage(page, wbc);
832 mutex_unlock(&shmem_swaplist_mutex);
833 swapcache_free(swap, NULL);
835 set_page_dirty(page);
836 if (wbc->for_reclaim)
837 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
844 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
848 if (!mpol || mpol->mode == MPOL_DEFAULT)
849 return; /* show nothing */
851 mpol_to_str(buffer, sizeof(buffer), mpol);
853 seq_printf(seq, ",mpol=%s", buffer);
856 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
858 struct mempolicy *mpol = NULL;
860 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
863 spin_unlock(&sbinfo->stat_lock);
867 #endif /* CONFIG_TMPFS */
869 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
870 struct shmem_inode_info *info, pgoff_t index)
872 struct vm_area_struct pvma;
875 /* Create a pseudo vma that just contains the policy */
877 /* Bias interleave by inode number to distribute better across nodes */
878 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
880 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
882 page = swapin_readahead(swap, gfp, &pvma, 0);
884 /* Drop reference taken by mpol_shared_policy_lookup() */
885 mpol_cond_put(pvma.vm_policy);
890 static struct page *shmem_alloc_page(gfp_t gfp,
891 struct shmem_inode_info *info, pgoff_t index)
893 struct vm_area_struct pvma;
896 /* Create a pseudo vma that just contains the policy */
898 /* Bias interleave by inode number to distribute better across nodes */
899 pvma.vm_pgoff = index + info->vfs_inode.i_ino;
901 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
903 page = alloc_page_vma(gfp, &pvma, 0);
905 /* Drop reference taken by mpol_shared_policy_lookup() */
906 mpol_cond_put(pvma.vm_policy);
910 #else /* !CONFIG_NUMA */
912 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
915 #endif /* CONFIG_TMPFS */
917 static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
918 struct shmem_inode_info *info, pgoff_t index)
920 return swapin_readahead(swap, gfp, NULL, 0);
923 static inline struct page *shmem_alloc_page(gfp_t gfp,
924 struct shmem_inode_info *info, pgoff_t index)
926 return alloc_page(gfp);
928 #endif /* CONFIG_NUMA */
930 #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
931 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
938 * When a page is moved from swapcache to shmem filecache (either by the
939 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
940 * shmem_unuse_inode()), it may have been read in earlier from swap, in
941 * ignorance of the mapping it belongs to. If that mapping has special
942 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
943 * we may need to copy to a suitable page before moving to filecache.
945 * In a future release, this may well be extended to respect cpuset and
946 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
947 * but for now it is a simple matter of zone.
949 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
951 return page_zonenum(page) > gfp_zone(gfp);
954 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
955 struct shmem_inode_info *info, pgoff_t index)
957 struct page *oldpage, *newpage;
958 struct address_space *swap_mapping;
963 swap_index = page_private(oldpage);
964 swap_mapping = page_mapping(oldpage);
967 * We have arrived here because our zones are constrained, so don't
968 * limit chance of success by further cpuset and node constraints.
970 gfp &= ~GFP_CONSTRAINT_MASK;
971 newpage = shmem_alloc_page(gfp, info, index);
975 page_cache_get(newpage);
976 copy_highpage(newpage, oldpage);
977 flush_dcache_page(newpage);
979 __set_page_locked(newpage);
980 SetPageUptodate(newpage);
981 SetPageSwapBacked(newpage);
982 set_page_private(newpage, swap_index);
983 SetPageSwapCache(newpage);
986 * Our caller will very soon move newpage out of swapcache, but it's
987 * a nice clean interface for us to replace oldpage by newpage there.
989 spin_lock_irq(&swap_mapping->tree_lock);
990 error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
993 __inc_zone_page_state(newpage, NR_FILE_PAGES);
994 __dec_zone_page_state(oldpage, NR_FILE_PAGES);
996 spin_unlock_irq(&swap_mapping->tree_lock);
998 if (unlikely(error)) {
1000 * Is this possible? I think not, now that our callers check
1001 * both PageSwapCache and page_private after getting page lock;
1002 * but be defensive. Reverse old to newpage for clear and free.
1006 mem_cgroup_replace_page_cache(oldpage, newpage);
1007 lru_cache_add_anon(newpage);
1011 ClearPageSwapCache(oldpage);
1012 set_page_private(oldpage, 0);
1014 unlock_page(oldpage);
1015 page_cache_release(oldpage);
1016 page_cache_release(oldpage);
1021 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1023 * If we allocate a new one we do not mark it dirty. That's up to the
1024 * vm. If we swap it in we mark it dirty since we also free the swap
1025 * entry since a page cannot live in both the swap and page cache
1027 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1028 struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
1030 struct address_space *mapping = inode->i_mapping;
1031 struct shmem_inode_info *info;
1032 struct shmem_sb_info *sbinfo;
1039 if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
1043 page = find_lock_entry(mapping, index);
1044 if (radix_tree_exceptional_entry(page)) {
1045 swap = radix_to_swp_entry(page);
1049 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1050 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1055 if (page && sgp == SGP_WRITE)
1056 mark_page_accessed(page);
1058 /* fallocated page? */
1059 if (page && !PageUptodate(page)) {
1060 if (sgp != SGP_READ)
1063 page_cache_release(page);
1066 if (page || (sgp == SGP_READ && !swap.val)) {
1072 * Fast cache lookup did not find it:
1073 * bring it back from swap or allocate.
1075 info = SHMEM_I(inode);
1076 sbinfo = SHMEM_SB(inode->i_sb);
1079 /* Look it up and read it in.. */
1080 page = lookup_swap_cache(swap);
1082 /* here we actually do the io */
1084 *fault_type |= VM_FAULT_MAJOR;
1085 page = shmem_swapin(swap, gfp, info, index);
1092 /* We have to do this with page locked to prevent races */
1094 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1095 !shmem_confirm_swap(mapping, index, swap)) {
1096 error = -EEXIST; /* try again */
1099 if (!PageUptodate(page)) {
1103 wait_on_page_writeback(page);
1105 if (shmem_should_replace_page(page, gfp)) {
1106 error = shmem_replace_page(&page, gfp, info, index);
1111 error = mem_cgroup_charge_file(page, current->mm,
1112 gfp & GFP_RECLAIM_MASK);
1114 error = shmem_add_to_page_cache(page, mapping, index,
1115 swp_to_radix_entry(swap));
1117 * We already confirmed swap under page lock, and make
1118 * no memory allocation here, so usually no possibility
1119 * of error; but free_swap_and_cache() only trylocks a
1120 * page, so it is just possible that the entry has been
1121 * truncated or holepunched since swap was confirmed.
1122 * shmem_undo_range() will have done some of the
1123 * unaccounting, now delete_from_swap_cache() will do
1124 * the rest (including mem_cgroup_uncharge_swapcache).
1125 * Reset swap.val? No, leave it so "failed" goes back to
1126 * "repeat": reading a hole and writing should succeed.
1129 delete_from_swap_cache(page);
1134 spin_lock(&info->lock);
1136 shmem_recalc_inode(inode);
1137 spin_unlock(&info->lock);
1139 if (sgp == SGP_WRITE)
1140 mark_page_accessed(page);
1142 delete_from_swap_cache(page);
1143 set_page_dirty(page);
1147 if (shmem_acct_block(info->flags)) {
1151 if (sbinfo->max_blocks) {
1152 if (percpu_counter_compare(&sbinfo->used_blocks,
1153 sbinfo->max_blocks) >= 0) {
1157 percpu_counter_inc(&sbinfo->used_blocks);
1160 page = shmem_alloc_page(gfp, info, index);
1166 __SetPageSwapBacked(page);
1167 __set_page_locked(page);
1168 if (sgp == SGP_WRITE)
1169 __SetPageReferenced(page);
1171 error = mem_cgroup_charge_file(page, current->mm,
1172 gfp & GFP_RECLAIM_MASK);
1175 error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
1177 error = shmem_add_to_page_cache(page, mapping, index,
1179 radix_tree_preload_end();
1182 mem_cgroup_uncharge_cache_page(page);
1185 lru_cache_add_anon(page);
1187 spin_lock(&info->lock);
1189 inode->i_blocks += BLOCKS_PER_PAGE;
1190 shmem_recalc_inode(inode);
1191 spin_unlock(&info->lock);
1195 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1197 if (sgp == SGP_FALLOC)
1201 * Let SGP_WRITE caller clear ends if write does not fill page;
1202 * but SGP_FALLOC on a page fallocated earlier must initialize
1203 * it now, lest undo on failure cancel our earlier guarantee.
1205 if (sgp != SGP_WRITE) {
1206 clear_highpage(page);
1207 flush_dcache_page(page);
1208 SetPageUptodate(page);
1210 if (sgp == SGP_DIRTY)
1211 set_page_dirty(page);
1214 /* Perhaps the file has been truncated since we checked */
1215 if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
1216 ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
1230 info = SHMEM_I(inode);
1231 ClearPageDirty(page);
1232 delete_from_page_cache(page);
1233 spin_lock(&info->lock);
1235 inode->i_blocks -= BLOCKS_PER_PAGE;
1236 spin_unlock(&info->lock);
1238 sbinfo = SHMEM_SB(inode->i_sb);
1239 if (sbinfo->max_blocks)
1240 percpu_counter_add(&sbinfo->used_blocks, -1);
1242 shmem_unacct_blocks(info->flags, 1);
1244 if (swap.val && error != -EINVAL &&
1245 !shmem_confirm_swap(mapping, index, swap))
1250 page_cache_release(page);
1252 if (error == -ENOSPC && !once++) {
1253 info = SHMEM_I(inode);
1254 spin_lock(&info->lock);
1255 shmem_recalc_inode(inode);
1256 spin_unlock(&info->lock);
1259 if (error == -EEXIST) /* from above or from radix_tree_insert */
1264 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1266 struct inode *inode = file_inode(vma->vm_file);
1268 int ret = VM_FAULT_LOCKED;
1271 * Trinity finds that probing a hole which tmpfs is punching can
1272 * prevent the hole-punch from ever completing: which in turn
1273 * locks writers out with its hold on i_mutex. So refrain from
1274 * faulting pages into the hole while it's being punched. Although
1275 * shmem_undo_range() does remove the additions, it may be unable to
1276 * keep up, as each new page needs its own unmap_mapping_range() call,
1277 * and the i_mmap tree grows ever slower to scan if new vmas are added.
1279 * It does not matter if we sometimes reach this check just before the
1280 * hole-punch begins, so that one fault then races with the punch:
1281 * we just need to make racing faults a rare case.
1283 * The implementation below would be much simpler if we just used a
1284 * standard mutex or completion: but we cannot take i_mutex in fault,
1285 * and bloating every shmem inode for this unlikely case would be sad.
1287 if (unlikely(inode->i_private)) {
1288 struct shmem_falloc *shmem_falloc;
1290 spin_lock(&inode->i_lock);
1291 shmem_falloc = inode->i_private;
1293 shmem_falloc->waitq &&
1294 vmf->pgoff >= shmem_falloc->start &&
1295 vmf->pgoff < shmem_falloc->next) {
1296 wait_queue_head_t *shmem_falloc_waitq;
1297 DEFINE_WAIT(shmem_fault_wait);
1299 ret = VM_FAULT_NOPAGE;
1300 if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
1301 !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
1302 /* It's polite to up mmap_sem if we can */
1303 up_read(&vma->vm_mm->mmap_sem);
1304 ret = VM_FAULT_RETRY;
1307 shmem_falloc_waitq = shmem_falloc->waitq;
1308 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
1309 TASK_UNINTERRUPTIBLE);
1310 spin_unlock(&inode->i_lock);
1314 * shmem_falloc_waitq points into the shmem_fallocate()
1315 * stack of the hole-punching task: shmem_falloc_waitq
1316 * is usually invalid by the time we reach here, but
1317 * finish_wait() does not dereference it in that case;
1318 * though i_lock needed lest racing with wake_up_all().
1320 spin_lock(&inode->i_lock);
1321 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
1322 spin_unlock(&inode->i_lock);
1325 spin_unlock(&inode->i_lock);
1328 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
1330 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1332 if (ret & VM_FAULT_MAJOR) {
1333 count_vm_event(PGMAJFAULT);
1334 mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1340 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
1342 struct inode *inode = file_inode(vma->vm_file);
1343 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
1346 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1349 struct inode *inode = file_inode(vma->vm_file);
1352 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1353 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
1357 int shmem_lock(struct file *file, int lock, struct user_struct *user)
1359 struct inode *inode = file_inode(file);
1360 struct shmem_inode_info *info = SHMEM_I(inode);
1361 int retval = -ENOMEM;
1363 spin_lock(&info->lock);
1364 if (lock && !(info->flags & VM_LOCKED)) {
1365 if (!user_shm_lock(inode->i_size, user))
1367 info->flags |= VM_LOCKED;
1368 mapping_set_unevictable(file->f_mapping);
1370 if (!lock && (info->flags & VM_LOCKED) && user) {
1371 user_shm_unlock(inode->i_size, user);
1372 info->flags &= ~VM_LOCKED;
1373 mapping_clear_unevictable(file->f_mapping);
1378 spin_unlock(&info->lock);
1382 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1384 file_accessed(file);
1385 vma->vm_ops = &shmem_vm_ops;
1389 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1390 umode_t mode, dev_t dev, unsigned long flags)
1392 struct inode *inode;
1393 struct shmem_inode_info *info;
1394 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1396 if (shmem_reserve_inode(sb))
1399 inode = new_inode(sb);
1401 inode->i_ino = get_next_ino();
1402 inode_init_owner(inode, dir, mode);
1403 inode->i_blocks = 0;
1404 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1405 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1406 inode->i_generation = get_seconds();
1407 info = SHMEM_I(inode);
1408 memset(info, 0, (char *)inode - (char *)info);
1409 spin_lock_init(&info->lock);
1410 info->flags = flags & VM_NORESERVE;
1411 INIT_LIST_HEAD(&info->swaplist);
1412 simple_xattrs_init(&info->xattrs);
1413 cache_no_acl(inode);
1415 switch (mode & S_IFMT) {
1417 inode->i_op = &shmem_special_inode_operations;
1418 init_special_inode(inode, mode, dev);
1421 inode->i_mapping->a_ops = &shmem_aops;
1422 inode->i_op = &shmem_inode_operations;
1423 inode->i_fop = &shmem_file_operations;
1424 mpol_shared_policy_init(&info->policy,
1425 shmem_get_sbmpol(sbinfo));
1429 /* Some things misbehave if size == 0 on a directory */
1430 inode->i_size = 2 * BOGO_DIRENT_SIZE;
1431 inode->i_op = &shmem_dir_inode_operations;
1432 inode->i_fop = &simple_dir_operations;
1436 * Must not load anything in the rbtree,
1437 * mpol_free_shared_policy will not be called.
1439 mpol_shared_policy_init(&info->policy, NULL);
1443 shmem_free_inode(sb);
1447 bool shmem_mapping(struct address_space *mapping)
1449 return mapping->backing_dev_info == &shmem_backing_dev_info;
1453 static const struct inode_operations shmem_symlink_inode_operations;
1454 static const struct inode_operations shmem_short_symlink_operations;
1456 #ifdef CONFIG_TMPFS_XATTR
1457 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
1459 #define shmem_initxattrs NULL
1463 shmem_write_begin(struct file *file, struct address_space *mapping,
1464 loff_t pos, unsigned len, unsigned flags,
1465 struct page **pagep, void **fsdata)
1467 struct inode *inode = mapping->host;
1468 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1469 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
1473 shmem_write_end(struct file *file, struct address_space *mapping,
1474 loff_t pos, unsigned len, unsigned copied,
1475 struct page *page, void *fsdata)
1477 struct inode *inode = mapping->host;
1479 if (pos + copied > inode->i_size)
1480 i_size_write(inode, pos + copied);
1482 if (!PageUptodate(page)) {
1483 if (copied < PAGE_CACHE_SIZE) {
1484 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
1485 zero_user_segments(page, 0, from,
1486 from + copied, PAGE_CACHE_SIZE);
1488 SetPageUptodate(page);
1490 set_page_dirty(page);
1492 page_cache_release(page);
1497 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
1499 struct file *file = iocb->ki_filp;
1500 struct inode *inode = file_inode(file);
1501 struct address_space *mapping = inode->i_mapping;
1503 unsigned long offset;
1504 enum sgp_type sgp = SGP_READ;
1507 loff_t *ppos = &iocb->ki_pos;
1510 * Might this read be for a stacking filesystem? Then when reading
1511 * holes of a sparse file, we actually need to allocate those pages,
1512 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1514 if (segment_eq(get_fs(), KERNEL_DS))
1517 index = *ppos >> PAGE_CACHE_SHIFT;
1518 offset = *ppos & ~PAGE_CACHE_MASK;
1521 struct page *page = NULL;
1523 unsigned long nr, ret;
1524 loff_t i_size = i_size_read(inode);
1526 end_index = i_size >> PAGE_CACHE_SHIFT;
1527 if (index > end_index)
1529 if (index == end_index) {
1530 nr = i_size & ~PAGE_CACHE_MASK;
1535 error = shmem_getpage(inode, index, &page, sgp, NULL);
1537 if (error == -EINVAL)
1545 * We must evaluate after, since reads (unlike writes)
1546 * are called without i_mutex protection against truncate
1548 nr = PAGE_CACHE_SIZE;
1549 i_size = i_size_read(inode);
1550 end_index = i_size >> PAGE_CACHE_SHIFT;
1551 if (index == end_index) {
1552 nr = i_size & ~PAGE_CACHE_MASK;
1555 page_cache_release(page);
1563 * If users can be writing to this page using arbitrary
1564 * virtual addresses, take care about potential aliasing
1565 * before reading the page on the kernel side.
1567 if (mapping_writably_mapped(mapping))
1568 flush_dcache_page(page);
1570 * Mark the page accessed if we read the beginning.
1573 mark_page_accessed(page);
1575 page = ZERO_PAGE(0);
1576 page_cache_get(page);
1580 * Ok, we have the page, and it's up-to-date, so
1581 * now we can copy it to user space...
1583 ret = copy_page_to_iter(page, offset, nr, to);
1586 index += offset >> PAGE_CACHE_SHIFT;
1587 offset &= ~PAGE_CACHE_MASK;
1589 page_cache_release(page);
1590 if (!iov_iter_count(to))
1599 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1600 file_accessed(file);
1601 return retval ? retval : error;
1604 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
1605 struct pipe_inode_info *pipe, size_t len,
1608 struct address_space *mapping = in->f_mapping;
1609 struct inode *inode = mapping->host;
1610 unsigned int loff, nr_pages, req_pages;
1611 struct page *pages[PIPE_DEF_BUFFERS];
1612 struct partial_page partial[PIPE_DEF_BUFFERS];
1614 pgoff_t index, end_index;
1617 struct splice_pipe_desc spd = {
1620 .nr_pages_max = PIPE_DEF_BUFFERS,
1622 .ops = &page_cache_pipe_buf_ops,
1623 .spd_release = spd_release_page,
1626 isize = i_size_read(inode);
1627 if (unlikely(*ppos >= isize))
1630 left = isize - *ppos;
1631 if (unlikely(left < len))
1634 if (splice_grow_spd(pipe, &spd))
1637 index = *ppos >> PAGE_CACHE_SHIFT;
1638 loff = *ppos & ~PAGE_CACHE_MASK;
1639 req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1640 nr_pages = min(req_pages, spd.nr_pages_max);
1642 spd.nr_pages = find_get_pages_contig(mapping, index,
1643 nr_pages, spd.pages);
1644 index += spd.nr_pages;
1647 while (spd.nr_pages < nr_pages) {
1648 error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
1652 spd.pages[spd.nr_pages++] = page;
1656 index = *ppos >> PAGE_CACHE_SHIFT;
1657 nr_pages = spd.nr_pages;
1660 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
1661 unsigned int this_len;
1666 this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
1667 page = spd.pages[page_nr];
1669 if (!PageUptodate(page) || page->mapping != mapping) {
1670 error = shmem_getpage(inode, index, &page,
1675 page_cache_release(spd.pages[page_nr]);
1676 spd.pages[page_nr] = page;
1679 isize = i_size_read(inode);
1680 end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1681 if (unlikely(!isize || index > end_index))
1684 if (end_index == index) {
1687 plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1691 this_len = min(this_len, plen - loff);
1695 spd.partial[page_nr].offset = loff;
1696 spd.partial[page_nr].len = this_len;
1703 while (page_nr < nr_pages)
1704 page_cache_release(spd.pages[page_nr++]);
1707 error = splice_to_pipe(pipe, &spd);
1709 splice_shrink_spd(&spd);
1719 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
1721 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
1722 pgoff_t index, pgoff_t end, int whence)
1725 struct pagevec pvec;
1726 pgoff_t indices[PAGEVEC_SIZE];
1730 pagevec_init(&pvec, 0);
1731 pvec.nr = 1; /* start small: we may be there already */
1733 pvec.nr = find_get_entries(mapping, index,
1734 pvec.nr, pvec.pages, indices);
1736 if (whence == SEEK_DATA)
1740 for (i = 0; i < pvec.nr; i++, index++) {
1741 if (index < indices[i]) {
1742 if (whence == SEEK_HOLE) {
1748 page = pvec.pages[i];
1749 if (page && !radix_tree_exceptional_entry(page)) {
1750 if (!PageUptodate(page))
1754 (page && whence == SEEK_DATA) ||
1755 (!page && whence == SEEK_HOLE)) {
1760 pagevec_remove_exceptionals(&pvec);
1761 pagevec_release(&pvec);
1762 pvec.nr = PAGEVEC_SIZE;
1768 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
1770 struct address_space *mapping = file->f_mapping;
1771 struct inode *inode = mapping->host;
1775 if (whence != SEEK_DATA && whence != SEEK_HOLE)
1776 return generic_file_llseek_size(file, offset, whence,
1777 MAX_LFS_FILESIZE, i_size_read(inode));
1778 mutex_lock(&inode->i_mutex);
1779 /* We're holding i_mutex so we can access i_size directly */
1783 else if (offset >= inode->i_size)
1786 start = offset >> PAGE_CACHE_SHIFT;
1787 end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1788 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
1789 new_offset <<= PAGE_CACHE_SHIFT;
1790 if (new_offset > offset) {
1791 if (new_offset < inode->i_size)
1792 offset = new_offset;
1793 else if (whence == SEEK_DATA)
1796 offset = inode->i_size;
1801 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
1802 mutex_unlock(&inode->i_mutex);
1806 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
1809 struct inode *inode = file_inode(file);
1810 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1811 struct shmem_falloc shmem_falloc;
1812 pgoff_t start, index, end;
1815 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
1818 mutex_lock(&inode->i_mutex);
1820 if (mode & FALLOC_FL_PUNCH_HOLE) {
1821 struct address_space *mapping = file->f_mapping;
1822 loff_t unmap_start = round_up(offset, PAGE_SIZE);
1823 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
1824 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
1826 shmem_falloc.waitq = &shmem_falloc_waitq;
1827 shmem_falloc.start = unmap_start >> PAGE_SHIFT;
1828 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
1829 spin_lock(&inode->i_lock);
1830 inode->i_private = &shmem_falloc;
1831 spin_unlock(&inode->i_lock);
1833 if ((u64)unmap_end > (u64)unmap_start)
1834 unmap_mapping_range(mapping, unmap_start,
1835 1 + unmap_end - unmap_start, 0);
1836 shmem_truncate_range(inode, offset, offset + len - 1);
1837 /* No need to unmap again: hole-punching leaves COWed pages */
1839 spin_lock(&inode->i_lock);
1840 inode->i_private = NULL;
1841 wake_up_all(&shmem_falloc_waitq);
1842 spin_unlock(&inode->i_lock);
1847 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
1848 error = inode_newsize_ok(inode, offset + len);
1852 start = offset >> PAGE_CACHE_SHIFT;
1853 end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1854 /* Try to avoid a swapstorm if len is impossible to satisfy */
1855 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
1860 shmem_falloc.waitq = NULL;
1861 shmem_falloc.start = start;
1862 shmem_falloc.next = start;
1863 shmem_falloc.nr_falloced = 0;
1864 shmem_falloc.nr_unswapped = 0;
1865 spin_lock(&inode->i_lock);
1866 inode->i_private = &shmem_falloc;
1867 spin_unlock(&inode->i_lock);
1869 for (index = start; index < end; index++) {
1873 * Good, the fallocate(2) manpage permits EINTR: we may have
1874 * been interrupted because we are using up too much memory.
1876 if (signal_pending(current))
1878 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
1881 error = shmem_getpage(inode, index, &page, SGP_FALLOC,
1884 /* Remove the !PageUptodate pages we added */
1885 shmem_undo_range(inode,
1886 (loff_t)start << PAGE_CACHE_SHIFT,
1887 (loff_t)index << PAGE_CACHE_SHIFT, true);
1892 * Inform shmem_writepage() how far we have reached.
1893 * No need for lock or barrier: we have the page lock.
1895 shmem_falloc.next++;
1896 if (!PageUptodate(page))
1897 shmem_falloc.nr_falloced++;
1900 * If !PageUptodate, leave it that way so that freeable pages
1901 * can be recognized if we need to rollback on error later.
1902 * But set_page_dirty so that memory pressure will swap rather
1903 * than free the pages we are allocating (and SGP_CACHE pages
1904 * might still be clean: we now need to mark those dirty too).
1906 set_page_dirty(page);
1908 page_cache_release(page);
1912 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
1913 i_size_write(inode, offset + len);
1914 inode->i_ctime = CURRENT_TIME;
1916 spin_lock(&inode->i_lock);
1917 inode->i_private = NULL;
1918 spin_unlock(&inode->i_lock);
1920 mutex_unlock(&inode->i_mutex);
1924 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1926 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1928 buf->f_type = TMPFS_MAGIC;
1929 buf->f_bsize = PAGE_CACHE_SIZE;
1930 buf->f_namelen = NAME_MAX;
1931 if (sbinfo->max_blocks) {
1932 buf->f_blocks = sbinfo->max_blocks;
1934 buf->f_bfree = sbinfo->max_blocks -
1935 percpu_counter_sum(&sbinfo->used_blocks);
1937 if (sbinfo->max_inodes) {
1938 buf->f_files = sbinfo->max_inodes;
1939 buf->f_ffree = sbinfo->free_inodes;
1941 /* else leave those fields 0 like simple_statfs */
1946 * File creation. Allocate an inode, and we're done..
1949 shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
1951 struct inode *inode;
1952 int error = -ENOSPC;
1954 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1956 error = simple_acl_create(dir, inode);
1959 error = security_inode_init_security(inode, dir,
1961 shmem_initxattrs, NULL);
1962 if (error && error != -EOPNOTSUPP)
1966 dir->i_size += BOGO_DIRENT_SIZE;
1967 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1968 d_instantiate(dentry, inode);
1969 dget(dentry); /* Extra count - pin the dentry in core */
1978 shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
1980 struct inode *inode;
1981 int error = -ENOSPC;
1983 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
1985 error = security_inode_init_security(inode, dir,
1987 shmem_initxattrs, NULL);
1988 if (error && error != -EOPNOTSUPP)
1990 error = simple_acl_create(dir, inode);
1993 d_tmpfile(dentry, inode);
2001 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
2005 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
2011 static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
2014 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
2020 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2022 struct inode *inode = old_dentry->d_inode;
2026 * No ordinary (disk based) filesystem counts links as inodes;
2027 * but each new link needs a new dentry, pinning lowmem, and
2028 * tmpfs dentries cannot be pruned until they are unlinked.
2030 ret = shmem_reserve_inode(inode->i_sb);
2034 dir->i_size += BOGO_DIRENT_SIZE;
2035 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2037 ihold(inode); /* New dentry reference */
2038 dget(dentry); /* Extra pinning count for the created dentry */
2039 d_instantiate(dentry, inode);
2044 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2046 struct inode *inode = dentry->d_inode;
2048 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2049 shmem_free_inode(inode->i_sb);
2051 dir->i_size -= BOGO_DIRENT_SIZE;
2052 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2054 dput(dentry); /* Undo the count from "create" - this does all the work */
2058 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
2060 if (!simple_empty(dentry))
2063 drop_nlink(dentry->d_inode);
2065 return shmem_unlink(dir, dentry);
2069 * The VFS layer already does all the dentry stuff for rename,
2070 * we just have to decrement the usage count for the target if
2071 * it exists so that the VFS layer correctly free's it when it
2074 static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
2076 struct inode *inode = old_dentry->d_inode;
2077 int they_are_dirs = S_ISDIR(inode->i_mode);
2079 if (!simple_empty(new_dentry))
2082 if (new_dentry->d_inode) {
2083 (void) shmem_unlink(new_dir, new_dentry);
2085 drop_nlink(old_dir);
2086 } else if (they_are_dirs) {
2087 drop_nlink(old_dir);
2091 old_dir->i_size -= BOGO_DIRENT_SIZE;
2092 new_dir->i_size += BOGO_DIRENT_SIZE;
2093 old_dir->i_ctime = old_dir->i_mtime =
2094 new_dir->i_ctime = new_dir->i_mtime =
2095 inode->i_ctime = CURRENT_TIME;
2099 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
2103 struct inode *inode;
2106 struct shmem_inode_info *info;
2108 len = strlen(symname) + 1;
2109 if (len > PAGE_CACHE_SIZE)
2110 return -ENAMETOOLONG;
2112 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
2116 error = security_inode_init_security(inode, dir, &dentry->d_name,
2117 shmem_initxattrs, NULL);
2119 if (error != -EOPNOTSUPP) {
2126 info = SHMEM_I(inode);
2127 inode->i_size = len-1;
2128 if (len <= SHORT_SYMLINK_LEN) {
2129 info->symlink = kmemdup(symname, len, GFP_KERNEL);
2130 if (!info->symlink) {
2134 inode->i_op = &shmem_short_symlink_operations;
2136 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
2141 inode->i_mapping->a_ops = &shmem_aops;
2142 inode->i_op = &shmem_symlink_inode_operations;
2143 kaddr = kmap_atomic(page);
2144 memcpy(kaddr, symname, len);
2145 kunmap_atomic(kaddr);
2146 SetPageUptodate(page);
2147 set_page_dirty(page);
2149 page_cache_release(page);
2151 dir->i_size += BOGO_DIRENT_SIZE;
2152 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2153 d_instantiate(dentry, inode);
2158 static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
2160 nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
2164 static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
2166 struct page *page = NULL;
2167 int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
2168 nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
2174 static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
2176 if (!IS_ERR(nd_get_link(nd))) {
2177 struct page *page = cookie;
2179 mark_page_accessed(page);
2180 page_cache_release(page);
2184 #ifdef CONFIG_TMPFS_XATTR
2186 * Superblocks without xattr inode operations may get some security.* xattr
2187 * support from the LSM "for free". As soon as we have any other xattrs
2188 * like ACLs, we also need to implement the security.* handlers at
2189 * filesystem level, though.
2193 * Callback for security_inode_init_security() for acquiring xattrs.
2195 static int shmem_initxattrs(struct inode *inode,
2196 const struct xattr *xattr_array,
2199 struct shmem_inode_info *info = SHMEM_I(inode);
2200 const struct xattr *xattr;
2201 struct simple_xattr *new_xattr;
2204 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
2205 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
2209 len = strlen(xattr->name) + 1;
2210 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
2212 if (!new_xattr->name) {
2217 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
2218 XATTR_SECURITY_PREFIX_LEN);
2219 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
2222 simple_xattr_list_add(&info->xattrs, new_xattr);
2228 static const struct xattr_handler *shmem_xattr_handlers[] = {
2229 #ifdef CONFIG_TMPFS_POSIX_ACL
2230 &posix_acl_access_xattr_handler,
2231 &posix_acl_default_xattr_handler,
2236 static int shmem_xattr_validate(const char *name)
2238 struct { const char *prefix; size_t len; } arr[] = {
2239 { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
2240 { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
2244 for (i = 0; i < ARRAY_SIZE(arr); i++) {
2245 size_t preflen = arr[i].len;
2246 if (strncmp(name, arr[i].prefix, preflen) == 0) {
2255 static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
2256 void *buffer, size_t size)
2258 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2262 * If this is a request for a synthetic attribute in the system.*
2263 * namespace use the generic infrastructure to resolve a handler
2264 * for it via sb->s_xattr.
2266 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2267 return generic_getxattr(dentry, name, buffer, size);
2269 err = shmem_xattr_validate(name);
2273 return simple_xattr_get(&info->xattrs, name, buffer, size);
2276 static int shmem_setxattr(struct dentry *dentry, const char *name,
2277 const void *value, size_t size, int flags)
2279 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2283 * If this is a request for a synthetic attribute in the system.*
2284 * namespace use the generic infrastructure to resolve a handler
2285 * for it via sb->s_xattr.
2287 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2288 return generic_setxattr(dentry, name, value, size, flags);
2290 err = shmem_xattr_validate(name);
2294 return simple_xattr_set(&info->xattrs, name, value, size, flags);
2297 static int shmem_removexattr(struct dentry *dentry, const char *name)
2299 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2303 * If this is a request for a synthetic attribute in the system.*
2304 * namespace use the generic infrastructure to resolve a handler
2305 * for it via sb->s_xattr.
2307 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
2308 return generic_removexattr(dentry, name);
2310 err = shmem_xattr_validate(name);
2314 return simple_xattr_remove(&info->xattrs, name);
2317 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
2319 struct shmem_inode_info *info = SHMEM_I(dentry->d_inode);
2320 return simple_xattr_list(&info->xattrs, buffer, size);
2322 #endif /* CONFIG_TMPFS_XATTR */
2324 static const struct inode_operations shmem_short_symlink_operations = {
2325 .readlink = generic_readlink,
2326 .follow_link = shmem_follow_short_symlink,
2327 #ifdef CONFIG_TMPFS_XATTR
2328 .setxattr = shmem_setxattr,
2329 .getxattr = shmem_getxattr,
2330 .listxattr = shmem_listxattr,
2331 .removexattr = shmem_removexattr,
2335 static const struct inode_operations shmem_symlink_inode_operations = {
2336 .readlink = generic_readlink,
2337 .follow_link = shmem_follow_link,
2338 .put_link = shmem_put_link,
2339 #ifdef CONFIG_TMPFS_XATTR
2340 .setxattr = shmem_setxattr,
2341 .getxattr = shmem_getxattr,
2342 .listxattr = shmem_listxattr,
2343 .removexattr = shmem_removexattr,
2347 static struct dentry *shmem_get_parent(struct dentry *child)
2349 return ERR_PTR(-ESTALE);
2352 static int shmem_match(struct inode *ino, void *vfh)
2356 inum = (inum << 32) | fh[1];
2357 return ino->i_ino == inum && fh[0] == ino->i_generation;
2360 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
2361 struct fid *fid, int fh_len, int fh_type)
2363 struct inode *inode;
2364 struct dentry *dentry = NULL;
2371 inum = (inum << 32) | fid->raw[1];
2373 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
2374 shmem_match, fid->raw);
2376 dentry = d_find_alias(inode);
2383 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
2384 struct inode *parent)
2388 return FILEID_INVALID;
2391 if (inode_unhashed(inode)) {
2392 /* Unfortunately insert_inode_hash is not idempotent,
2393 * so as we hash inodes here rather than at creation
2394 * time, we need a lock to ensure we only try
2397 static DEFINE_SPINLOCK(lock);
2399 if (inode_unhashed(inode))
2400 __insert_inode_hash(inode,
2401 inode->i_ino + inode->i_generation);
2405 fh[0] = inode->i_generation;
2406 fh[1] = inode->i_ino;
2407 fh[2] = ((__u64)inode->i_ino) >> 32;
2413 static const struct export_operations shmem_export_ops = {
2414 .get_parent = shmem_get_parent,
2415 .encode_fh = shmem_encode_fh,
2416 .fh_to_dentry = shmem_fh_to_dentry,
2419 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
2422 char *this_char, *value, *rest;
2423 struct mempolicy *mpol = NULL;
2427 while (options != NULL) {
2428 this_char = options;
2431 * NUL-terminate this option: unfortunately,
2432 * mount options form a comma-separated list,
2433 * but mpol's nodelist may also contain commas.
2435 options = strchr(options, ',');
2436 if (options == NULL)
2439 if (!isdigit(*options)) {
2446 if ((value = strchr(this_char,'=')) != NULL) {
2450 "tmpfs: No value for mount option '%s'\n",
2455 if (!strcmp(this_char,"size")) {
2456 unsigned long long size;
2457 size = memparse(value,&rest);
2459 size <<= PAGE_SHIFT;
2460 size *= totalram_pages;
2466 sbinfo->max_blocks =
2467 DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2468 } else if (!strcmp(this_char,"nr_blocks")) {
2469 sbinfo->max_blocks = memparse(value, &rest);
2472 } else if (!strcmp(this_char,"nr_inodes")) {
2473 sbinfo->max_inodes = memparse(value, &rest);
2476 } else if (!strcmp(this_char,"mode")) {
2479 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2482 } else if (!strcmp(this_char,"uid")) {
2485 uid = simple_strtoul(value, &rest, 0);
2488 sbinfo->uid = make_kuid(current_user_ns(), uid);
2489 if (!uid_valid(sbinfo->uid))
2491 } else if (!strcmp(this_char,"gid")) {
2494 gid = simple_strtoul(value, &rest, 0);
2497 sbinfo->gid = make_kgid(current_user_ns(), gid);
2498 if (!gid_valid(sbinfo->gid))
2500 } else if (!strcmp(this_char,"mpol")) {
2503 if (mpol_parse_str(value, &mpol))
2506 printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2511 sbinfo->mpol = mpol;
2515 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2523 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2525 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2526 struct shmem_sb_info config = *sbinfo;
2527 unsigned long inodes;
2528 int error = -EINVAL;
2531 if (shmem_parse_options(data, &config, true))
2534 spin_lock(&sbinfo->stat_lock);
2535 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2536 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2538 if (config.max_inodes < inodes)
2541 * Those tests disallow limited->unlimited while any are in use;
2542 * but we must separately disallow unlimited->limited, because
2543 * in that case we have no record of how much is already in use.
2545 if (config.max_blocks && !sbinfo->max_blocks)
2547 if (config.max_inodes && !sbinfo->max_inodes)
2551 sbinfo->max_blocks = config.max_blocks;
2552 sbinfo->max_inodes = config.max_inodes;
2553 sbinfo->free_inodes = config.max_inodes - inodes;
2556 * Preserve previous mempolicy unless mpol remount option was specified.
2559 mpol_put(sbinfo->mpol);
2560 sbinfo->mpol = config.mpol; /* transfers initial ref */
2563 spin_unlock(&sbinfo->stat_lock);
2567 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
2569 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
2571 if (sbinfo->max_blocks != shmem_default_max_blocks())
2572 seq_printf(seq, ",size=%luk",
2573 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2574 if (sbinfo->max_inodes != shmem_default_max_inodes())
2575 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2576 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2577 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
2578 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
2579 seq_printf(seq, ",uid=%u",
2580 from_kuid_munged(&init_user_ns, sbinfo->uid));
2581 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
2582 seq_printf(seq, ",gid=%u",
2583 from_kgid_munged(&init_user_ns, sbinfo->gid));
2584 shmem_show_mpol(seq, sbinfo->mpol);
2587 #endif /* CONFIG_TMPFS */
2589 static void shmem_put_super(struct super_block *sb)
2591 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2593 percpu_counter_destroy(&sbinfo->used_blocks);
2594 mpol_put(sbinfo->mpol);
2596 sb->s_fs_info = NULL;
2599 int shmem_fill_super(struct super_block *sb, void *data, int silent)
2601 struct inode *inode;
2602 struct shmem_sb_info *sbinfo;
2605 /* Round up to L1_CACHE_BYTES to resist false sharing */
2606 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2607 L1_CACHE_BYTES), GFP_KERNEL);
2611 sbinfo->mode = S_IRWXUGO | S_ISVTX;
2612 sbinfo->uid = current_fsuid();
2613 sbinfo->gid = current_fsgid();
2614 sb->s_fs_info = sbinfo;
2618 * Per default we only allow half of the physical ram per
2619 * tmpfs instance, limiting inodes to one per page of lowmem;
2620 * but the internal instance is left unlimited.
2622 if (!(sb->s_flags & MS_KERNMOUNT)) {
2623 sbinfo->max_blocks = shmem_default_max_blocks();
2624 sbinfo->max_inodes = shmem_default_max_inodes();
2625 if (shmem_parse_options(data, sbinfo, false)) {
2630 sb->s_flags |= MS_NOUSER;
2632 sb->s_export_op = &shmem_export_ops;
2633 sb->s_flags |= MS_NOSEC;
2635 sb->s_flags |= MS_NOUSER;
2638 spin_lock_init(&sbinfo->stat_lock);
2639 if (percpu_counter_init(&sbinfo->used_blocks, 0))
2641 sbinfo->free_inodes = sbinfo->max_inodes;
2643 sb->s_maxbytes = MAX_LFS_FILESIZE;
2644 sb->s_blocksize = PAGE_CACHE_SIZE;
2645 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2646 sb->s_magic = TMPFS_MAGIC;
2647 sb->s_op = &shmem_ops;
2648 sb->s_time_gran = 1;
2649 #ifdef CONFIG_TMPFS_XATTR
2650 sb->s_xattr = shmem_xattr_handlers;
2652 #ifdef CONFIG_TMPFS_POSIX_ACL
2653 sb->s_flags |= MS_POSIXACL;
2656 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2659 inode->i_uid = sbinfo->uid;
2660 inode->i_gid = sbinfo->gid;
2661 sb->s_root = d_make_root(inode);
2667 shmem_put_super(sb);
2671 static struct kmem_cache *shmem_inode_cachep;
2673 static struct inode *shmem_alloc_inode(struct super_block *sb)
2675 struct shmem_inode_info *info;
2676 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2679 return &info->vfs_inode;
2682 static void shmem_destroy_callback(struct rcu_head *head)
2684 struct inode *inode = container_of(head, struct inode, i_rcu);
2685 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2688 static void shmem_destroy_inode(struct inode *inode)
2690 if (S_ISREG(inode->i_mode))
2691 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2692 call_rcu(&inode->i_rcu, shmem_destroy_callback);
2695 static void shmem_init_inode(void *foo)
2697 struct shmem_inode_info *info = foo;
2698 inode_init_once(&info->vfs_inode);
2701 static int shmem_init_inodecache(void)
2703 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2704 sizeof(struct shmem_inode_info),
2705 0, SLAB_PANIC, shmem_init_inode);
2709 static void shmem_destroy_inodecache(void)
2711 kmem_cache_destroy(shmem_inode_cachep);
2714 static const struct address_space_operations shmem_aops = {
2715 .writepage = shmem_writepage,
2716 .set_page_dirty = __set_page_dirty_no_writeback,
2718 .write_begin = shmem_write_begin,
2719 .write_end = shmem_write_end,
2721 .migratepage = migrate_page,
2722 .error_remove_page = generic_error_remove_page,
2725 static const struct file_operations shmem_file_operations = {
2728 .llseek = shmem_file_llseek,
2729 .read = new_sync_read,
2730 .write = new_sync_write,
2731 .read_iter = shmem_file_read_iter,
2732 .write_iter = generic_file_write_iter,
2733 .fsync = noop_fsync,
2734 .splice_read = shmem_file_splice_read,
2735 .splice_write = iter_file_splice_write,
2736 .fallocate = shmem_fallocate,
2740 static const struct inode_operations shmem_inode_operations = {
2741 .setattr = shmem_setattr,
2742 #ifdef CONFIG_TMPFS_XATTR
2743 .setxattr = shmem_setxattr,
2744 .getxattr = shmem_getxattr,
2745 .listxattr = shmem_listxattr,
2746 .removexattr = shmem_removexattr,
2747 .set_acl = simple_set_acl,
2751 static const struct inode_operations shmem_dir_inode_operations = {
2753 .create = shmem_create,
2754 .lookup = simple_lookup,
2756 .unlink = shmem_unlink,
2757 .symlink = shmem_symlink,
2758 .mkdir = shmem_mkdir,
2759 .rmdir = shmem_rmdir,
2760 .mknod = shmem_mknod,
2761 .rename = shmem_rename,
2762 .tmpfile = shmem_tmpfile,
2764 #ifdef CONFIG_TMPFS_XATTR
2765 .setxattr = shmem_setxattr,
2766 .getxattr = shmem_getxattr,
2767 .listxattr = shmem_listxattr,
2768 .removexattr = shmem_removexattr,
2770 #ifdef CONFIG_TMPFS_POSIX_ACL
2771 .setattr = shmem_setattr,
2772 .set_acl = simple_set_acl,
2776 static const struct inode_operations shmem_special_inode_operations = {
2777 #ifdef CONFIG_TMPFS_XATTR
2778 .setxattr = shmem_setxattr,
2779 .getxattr = shmem_getxattr,
2780 .listxattr = shmem_listxattr,
2781 .removexattr = shmem_removexattr,
2783 #ifdef CONFIG_TMPFS_POSIX_ACL
2784 .setattr = shmem_setattr,
2785 .set_acl = simple_set_acl,
2789 static const struct super_operations shmem_ops = {
2790 .alloc_inode = shmem_alloc_inode,
2791 .destroy_inode = shmem_destroy_inode,
2793 .statfs = shmem_statfs,
2794 .remount_fs = shmem_remount_fs,
2795 .show_options = shmem_show_options,
2797 .evict_inode = shmem_evict_inode,
2798 .drop_inode = generic_delete_inode,
2799 .put_super = shmem_put_super,
2802 static const struct vm_operations_struct shmem_vm_ops = {
2803 .fault = shmem_fault,
2804 .map_pages = filemap_map_pages,
2806 .set_policy = shmem_set_policy,
2807 .get_policy = shmem_get_policy,
2809 .remap_pages = generic_file_remap_pages,
2812 static struct dentry *shmem_mount(struct file_system_type *fs_type,
2813 int flags, const char *dev_name, void *data)
2815 return mount_nodev(fs_type, flags, data, shmem_fill_super);
2818 static struct file_system_type shmem_fs_type = {
2819 .owner = THIS_MODULE,
2821 .mount = shmem_mount,
2822 .kill_sb = kill_litter_super,
2823 .fs_flags = FS_USERNS_MOUNT,
2826 int __init shmem_init(void)
2830 /* If rootfs called this, don't re-init */
2831 if (shmem_inode_cachep)
2834 error = bdi_init(&shmem_backing_dev_info);
2838 error = shmem_init_inodecache();
2842 error = register_filesystem(&shmem_fs_type);
2844 printk(KERN_ERR "Could not register tmpfs\n");
2848 shm_mnt = kern_mount(&shmem_fs_type);
2849 if (IS_ERR(shm_mnt)) {
2850 error = PTR_ERR(shm_mnt);
2851 printk(KERN_ERR "Could not kern_mount tmpfs\n");
2857 unregister_filesystem(&shmem_fs_type);
2859 shmem_destroy_inodecache();
2861 bdi_destroy(&shmem_backing_dev_info);
2863 shm_mnt = ERR_PTR(error);
2867 #else /* !CONFIG_SHMEM */
2870 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2872 * This is intended for small system where the benefits of the full
2873 * shmem code (swap-backed and resource-limited) are outweighed by
2874 * their complexity. On systems without swap this code should be
2875 * effectively equivalent, but much lighter weight.
2878 static struct file_system_type shmem_fs_type = {
2880 .mount = ramfs_mount,
2881 .kill_sb = kill_litter_super,
2882 .fs_flags = FS_USERNS_MOUNT,
2885 int __init shmem_init(void)
2887 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
2889 shm_mnt = kern_mount(&shmem_fs_type);
2890 BUG_ON(IS_ERR(shm_mnt));
2895 int shmem_unuse(swp_entry_t swap, struct page *page)
2900 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2905 void shmem_unlock_mapping(struct address_space *mapping)
2909 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
2911 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
2913 EXPORT_SYMBOL_GPL(shmem_truncate_range);
2915 #define shmem_vm_ops generic_file_vm_ops
2916 #define shmem_file_operations ramfs_file_operations
2917 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
2918 #define shmem_acct_size(flags, size) 0
2919 #define shmem_unacct_size(flags, size) do {} while (0)
2921 #endif /* CONFIG_SHMEM */
2925 static struct dentry_operations anon_ops = {
2926 .d_dname = simple_dname
2929 static struct file *__shmem_file_setup(const char *name, loff_t size,
2930 unsigned long flags, unsigned int i_flags)
2933 struct inode *inode;
2935 struct super_block *sb;
2938 if (IS_ERR(shm_mnt))
2939 return ERR_CAST(shm_mnt);
2941 if (size < 0 || size > MAX_LFS_FILESIZE)
2942 return ERR_PTR(-EINVAL);
2944 if (shmem_acct_size(flags, size))
2945 return ERR_PTR(-ENOMEM);
2947 res = ERR_PTR(-ENOMEM);
2949 this.len = strlen(name);
2950 this.hash = 0; /* will go */
2951 sb = shm_mnt->mnt_sb;
2952 path.mnt = mntget(shm_mnt);
2953 path.dentry = d_alloc_pseudo(sb, &this);
2956 d_set_d_op(path.dentry, &anon_ops);
2958 res = ERR_PTR(-ENOSPC);
2959 inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2963 inode->i_flags |= i_flags;
2964 d_instantiate(path.dentry, inode);
2965 inode->i_size = size;
2966 clear_nlink(inode); /* It is unlinked */
2967 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
2971 res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2972 &shmem_file_operations);
2979 shmem_unacct_size(flags, size);
2986 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
2987 * kernel internal. There will be NO LSM permission checks against the
2988 * underlying inode. So users of this interface must do LSM checks at a
2989 * higher layer. The one user is the big_key implementation. LSM checks
2990 * are provided at the key level rather than the inode level.
2991 * @name: name for dentry (to be seen in /proc/<pid>/maps
2992 * @size: size to be set for the file
2993 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2995 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
2997 return __shmem_file_setup(name, size, flags, S_PRIVATE);
3001 * shmem_file_setup - get an unlinked file living in tmpfs
3002 * @name: name for dentry (to be seen in /proc/<pid>/maps
3003 * @size: size to be set for the file
3004 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
3006 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
3008 return __shmem_file_setup(name, size, flags, 0);
3010 EXPORT_SYMBOL_GPL(shmem_file_setup);
3013 * shmem_zero_setup - setup a shared anonymous mapping
3014 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
3016 int shmem_zero_setup(struct vm_area_struct *vma)
3019 loff_t size = vma->vm_end - vma->vm_start;
3021 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
3023 return PTR_ERR(file);
3027 vma->vm_file = file;
3028 vma->vm_ops = &shmem_vm_ops;
3033 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
3034 * @mapping: the page's address_space
3035 * @index: the page index
3036 * @gfp: the page allocator flags to use if allocating
3038 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
3039 * with any new page allocations done using the specified allocation flags.
3040 * But read_cache_page_gfp() uses the ->readpage() method: which does not
3041 * suit tmpfs, since it may have pages in swapcache, and needs to find those
3042 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
3044 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
3045 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
3047 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
3048 pgoff_t index, gfp_t gfp)
3051 struct inode *inode = mapping->host;
3055 BUG_ON(mapping->a_ops != &shmem_aops);
3056 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
3058 page = ERR_PTR(error);
3064 * The tiny !SHMEM case uses ramfs without swap
3066 return read_cache_page_gfp(mapping, index, gfp);
3069 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);