--- /dev/null
+/*
+ * Resizable virtual memory filesystem for Linux.
+ *
+ * Copyright (C) 2000 Linus Torvalds.
+ * 2000 Transmeta Corp.
+ * 2000-2001 Christoph Rohland
+ * 2000-2001 SAP AG
+ * 2002 Red Hat Inc.
+ * Copyright (C) 2002-2011 Hugh Dickins.
+ * Copyright (C) 2011 Google Inc.
+ * Copyright (C) 2002-2005 VERITAS Software Corporation.
+ * Copyright (C) 2004 Andi Kleen, SuSE Labs
+ *
+ * Extended attribute support for tmpfs:
+ * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
+ * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ *
+ * tiny-shmem:
+ * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/vfs.h>
+#include <linux/mount.h>
+#include <linux/ramfs.h>
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/export.h>
+#include <linux/swap.h>
+#include <linux/uio.h>
+
+static struct vfsmount *shm_mnt;
+
+#ifdef CONFIG_SHMEM
+/*
+ * This virtual memory filesystem is heavily based on the ramfs. It
+ * extends ramfs by the ability to use swap and honor resource limits
+ * which makes it a completely usable filesystem.
+ */
+
+#include <linux/xattr.h>
+#include <linux/exportfs.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/mman.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/shmem_fs.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/pagevec.h>
+#include <linux/percpu_counter.h>
+#include <linux/falloc.h>
+#include <linux/splice.h>
+#include <linux/security.h>
+#include <linux/swapops.h>
+#include <linux/mempolicy.h>
+#include <linux/namei.h>
+#include <linux/ctype.h>
+#include <linux/migrate.h>
+#include <linux/highmem.h>
+#include <linux/seq_file.h>
+#include <linux/magic.h>
+#include <linux/syscalls.h>
+#include <linux/fcntl.h>
+#include <uapi/linux/memfd.h>
+
+#include <asm/uaccess.h>
+#include <asm/pgtable.h>
+
+#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
+#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
+
+/* Pretend that each entry is of this size in directory's i_size */
+#define BOGO_DIRENT_SIZE 20
+
+/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
+#define SHORT_SYMLINK_LEN 128
+
+/*
+ * shmem_fallocate communicates with shmem_fault or shmem_writepage via
+ * inode->i_private (with i_mutex making sure that it has only one user at
+ * a time): we would prefer not to enlarge the shmem inode just for that.
+ */
+struct shmem_falloc {
+ wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
+ pgoff_t start; /* start of range currently being fallocated */
+ pgoff_t next; /* the next page offset to be fallocated */
+ pgoff_t nr_falloced; /* how many new pages have been fallocated */
+ pgoff_t nr_unswapped; /* how often writepage refused to swap out */
+};
+
+/* Flag allocation requirements to shmem_getpage */
+enum sgp_type {
+ SGP_READ, /* don't exceed i_size, don't allocate page */
+ SGP_CACHE, /* don't exceed i_size, may allocate page */
+ SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
+ SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
+ SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
+};
+
+#ifdef CONFIG_TMPFS
+static unsigned long shmem_default_max_blocks(void)
+{
+ return totalram_pages / 2;
+}
+
+static unsigned long shmem_default_max_inodes(void)
+{
+ return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
+}
+#endif
+
+static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
+static int shmem_replace_page(struct page **pagep, gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index);
+static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
+ struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
+
+static inline int shmem_getpage(struct inode *inode, pgoff_t index,
+ struct page **pagep, enum sgp_type sgp, int *fault_type)
+{
+ return shmem_getpage_gfp(inode, index, pagep, sgp,
+ mapping_gfp_mask(inode->i_mapping), fault_type);
+}
+
+static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
+{
+ return sb->s_fs_info;
+}
+
+/*
+ * shmem_file_setup pre-accounts the whole fixed size of a VM object,
+ * for shared memory and for shared anonymous (/dev/zero) mappings
+ * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
+ * consistent with the pre-accounting of private mappings ...
+ */
+static inline int shmem_acct_size(unsigned long flags, loff_t size)
+{
+ return (flags & VM_NORESERVE) ?
+ 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
+}
+
+static inline void shmem_unacct_size(unsigned long flags, loff_t size)
+{
+ if (!(flags & VM_NORESERVE))
+ vm_unacct_memory(VM_ACCT(size));
+}
+
+static inline int shmem_reacct_size(unsigned long flags,
+ loff_t oldsize, loff_t newsize)
+{
+ if (!(flags & VM_NORESERVE)) {
+ if (VM_ACCT(newsize) > VM_ACCT(oldsize))
+ return security_vm_enough_memory_mm(current->mm,
+ VM_ACCT(newsize) - VM_ACCT(oldsize));
+ else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
+ vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
+ }
+ return 0;
+}
+
+/*
+ * ... whereas tmpfs objects are accounted incrementally as
+ * pages are allocated, in order to allow huge sparse files.
+ * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
+ * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
+ */
+static inline int shmem_acct_block(unsigned long flags)
+{
+ return (flags & VM_NORESERVE) ?
+ security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
+}
+
+static inline void shmem_unacct_blocks(unsigned long flags, long pages)
+{
+ if (flags & VM_NORESERVE)
+ vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
+}
+
+static const struct super_operations shmem_ops;
+static const struct address_space_operations shmem_aops;
+static const struct file_operations shmem_file_operations;
+static const struct inode_operations shmem_inode_operations;
+static const struct inode_operations shmem_dir_inode_operations;
+static const struct inode_operations shmem_special_inode_operations;
+static const struct vm_operations_struct shmem_vm_ops;
+
+static LIST_HEAD(shmem_swaplist);
+static DEFINE_MUTEX(shmem_swaplist_mutex);
+
+static int shmem_reserve_inode(struct super_block *sb)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+ if (sbinfo->max_inodes) {
+ spin_lock(&sbinfo->stat_lock);
+ if (!sbinfo->free_inodes) {
+ spin_unlock(&sbinfo->stat_lock);
+ return -ENOSPC;
+ }
+ sbinfo->free_inodes--;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ return 0;
+}
+
+static void shmem_free_inode(struct super_block *sb)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+ if (sbinfo->max_inodes) {
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_inodes++;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+}
+
+/**
+ * shmem_recalc_inode - recalculate the block usage of an inode
+ * @inode: inode to recalc
+ *
+ * We have to calculate the free blocks since the mm can drop
+ * undirtied hole pages behind our back.
+ *
+ * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
+ * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
+ *
+ * It has to be called with the spinlock held.
+ */
+static void shmem_recalc_inode(struct inode *inode)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ long freed;
+
+ freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
+ if (freed > 0) {
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo->max_blocks)
+ percpu_counter_add(&sbinfo->used_blocks, -freed);
+ info->alloced -= freed;
+ inode->i_blocks -= freed * BLOCKS_PER_PAGE;
+ shmem_unacct_blocks(info->flags, freed);
+ }
+}
+
+/*
+ * Replace item expected in radix tree by a new item, while holding tree lock.
+ */
+static int shmem_radix_tree_replace(struct address_space *mapping,
+ pgoff_t index, void *expected, void *replacement)
+{
+ void **pslot;
+ void *item;
+
+ VM_BUG_ON(!expected);
+ VM_BUG_ON(!replacement);
+ pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
+ if (!pslot)
+ return -ENOENT;
+ item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
+ if (item != expected)
+ return -ENOENT;
+ radix_tree_replace_slot(pslot, replacement);
+ return 0;
+}
+
+/*
+ * Sometimes, before we decide whether to proceed or to fail, we must check
+ * that an entry was not already brought back from swap by a racing thread.
+ *
+ * Checking page is not enough: by the time a SwapCache page is locked, it
+ * might be reused, and again be SwapCache, using the same swap as before.
+ */
+static bool shmem_confirm_swap(struct address_space *mapping,
+ pgoff_t index, swp_entry_t swap)
+{
+ void *item;
+
+ rcu_read_lock();
+ item = radix_tree_lookup(&mapping->page_tree, index);
+ rcu_read_unlock();
+ return item == swp_to_radix_entry(swap);
+}
+
+/*
+ * Like add_to_page_cache_locked, but error if expected item has gone.
+ */
+static int shmem_add_to_page_cache(struct page *page,
+ struct address_space *mapping,
+ pgoff_t index, void *expected)
+{
+ int error;
+
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
+
+ page_cache_get(page);
+ page->mapping = mapping;
+ page->index = index;
+
+ spin_lock_irq(&mapping->tree_lock);
+ if (!expected)
+ error = radix_tree_insert(&mapping->page_tree, index, page);
+ else
+ error = shmem_radix_tree_replace(mapping, index, expected,
+ page);
+ if (!error) {
+ mapping->nrpages++;
+ __inc_zone_page_state(page, NR_FILE_PAGES);
+ __inc_zone_page_state(page, NR_SHMEM);
+ spin_unlock_irq(&mapping->tree_lock);
+ } else {
+ page->mapping = NULL;
+ spin_unlock_irq(&mapping->tree_lock);
+ page_cache_release(page);
+ }
+ return error;
+}
+
+/*
+ * Like delete_from_page_cache, but substitutes swap for page.
+ */
+static void shmem_delete_from_page_cache(struct page *page, void *radswap)
+{
+ struct address_space *mapping = page->mapping;
+ int error;
+
+ spin_lock_irq(&mapping->tree_lock);
+ error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
+ page->mapping = NULL;
+ mapping->nrpages--;
+ __dec_zone_page_state(page, NR_FILE_PAGES);
+ __dec_zone_page_state(page, NR_SHMEM);
+ spin_unlock_irq(&mapping->tree_lock);
+ page_cache_release(page);
+ BUG_ON(error);
+}
+
+/*
+ * Remove swap entry from radix tree, free the swap and its page cache.
+ */
+static int shmem_free_swap(struct address_space *mapping,
+ pgoff_t index, void *radswap)
+{
+ void *old;
+
+ spin_lock_irq(&mapping->tree_lock);
+ old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
+ spin_unlock_irq(&mapping->tree_lock);
+ if (old != radswap)
+ return -ENOENT;
+ free_swap_and_cache(radix_to_swp_entry(radswap));
+ return 0;
+}
+
+/*
+ * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
+ */
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+ struct pagevec pvec;
+ pgoff_t indices[PAGEVEC_SIZE];
+ pgoff_t index = 0;
+
+ pagevec_init(&pvec, 0);
+ /*
+ * Minor point, but we might as well stop if someone else SHM_LOCKs it.
+ */
+ while (!mapping_unevictable(mapping)) {
+ /*
+ * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
+ * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
+ */
+ pvec.nr = find_get_entries(mapping, index,
+ PAGEVEC_SIZE, pvec.pages, indices);
+ if (!pvec.nr)
+ break;
+ index = indices[pvec.nr - 1] + 1;
+ pagevec_remove_exceptionals(&pvec);
+ check_move_unevictable_pages(pvec.pages, pvec.nr);
+ pagevec_release(&pvec);
+ cond_resched();
+ }
+}
+
+/*
+ * Remove range of pages and swap entries from radix tree, and free them.
+ * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
+ */
+static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
+ bool unfalloc)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
+ unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
+ unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
+ struct pagevec pvec;
+ pgoff_t indices[PAGEVEC_SIZE];
+ long nr_swaps_freed = 0;
+ pgoff_t index;
+ int i;
+
+ if (lend == -1)
+ end = -1; /* unsigned, so actually very big */
+
+ pagevec_init(&pvec, 0);
+ index = start;
+ while (index < end) {
+ pvec.nr = find_get_entries(mapping, index,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE),
+ pvec.pages, indices);
+ if (!pvec.nr)
+ break;
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ index = indices[i];
+ if (index >= end)
+ break;
+
+ if (radix_tree_exceptional_entry(page)) {
+ if (unfalloc)
+ continue;
+ nr_swaps_freed += !shmem_free_swap(mapping,
+ index, page);
+ continue;
+ }
+
+ if (!trylock_page(page))
+ continue;
+ if (!unfalloc || !PageUptodate(page)) {
+ if (page->mapping == mapping) {
+ VM_BUG_ON_PAGE(PageWriteback(page), page);
+ truncate_inode_page(mapping, page);
+ }
+ }
+ unlock_page(page);
+ }
+ pagevec_remove_exceptionals(&pvec);
+ pagevec_release(&pvec);
+ cond_resched();
+ index++;
+ }
+
+ if (partial_start) {
+ struct page *page = NULL;
+ shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
+ if (page) {
+ unsigned int top = PAGE_CACHE_SIZE;
+ if (start > end) {
+ top = partial_end;
+ partial_end = 0;
+ }
+ zero_user_segment(page, partial_start, top);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+ if (partial_end) {
+ struct page *page = NULL;
+ shmem_getpage(inode, end, &page, SGP_READ, NULL);
+ if (page) {
+ zero_user_segment(page, 0, partial_end);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ }
+ if (start >= end)
+ return;
+
+ index = start;
+ while (index < end) {
+ cond_resched();
+
+ pvec.nr = find_get_entries(mapping, index,
+ min(end - index, (pgoff_t)PAGEVEC_SIZE),
+ pvec.pages, indices);
+ if (!pvec.nr) {
+ /* If all gone or hole-punch or unfalloc, we're done */
+ if (index == start || end != -1)
+ break;
+ /* But if truncating, restart to make sure all gone */
+ index = start;
+ continue;
+ }
+ for (i = 0; i < pagevec_count(&pvec); i++) {
+ struct page *page = pvec.pages[i];
+
+ index = indices[i];
+ if (index >= end)
+ break;
+
+ if (radix_tree_exceptional_entry(page)) {
+ if (unfalloc)
+ continue;
+ if (shmem_free_swap(mapping, index, page)) {
+ /* Swap was replaced by page: retry */
+ index--;
+ break;
+ }
+ nr_swaps_freed++;
+ continue;
+ }
+
+ lock_page(page);
+ if (!unfalloc || !PageUptodate(page)) {
+ if (page->mapping == mapping) {
+ VM_BUG_ON_PAGE(PageWriteback(page), page);
+ truncate_inode_page(mapping, page);
+ } else {
+ /* Page was replaced by swap: retry */
+ unlock_page(page);
+ index--;
+ break;
+ }
+ }
+ unlock_page(page);
+ }
+ pagevec_remove_exceptionals(&pvec);
+ pagevec_release(&pvec);
+ index++;
+ }
+
+ spin_lock(&info->lock);
+ info->swapped -= nr_swaps_freed;
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+}
+
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+ shmem_undo_range(inode, lstart, lend, false);
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+}
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
+
+static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ struct inode *inode = d_inode(dentry);
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ int error;
+
+ error = inode_change_ok(inode, attr);
+ if (error)
+ return error;
+
+ if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
+ loff_t oldsize = inode->i_size;
+ loff_t newsize = attr->ia_size;
+
+ /* protected by i_mutex */
+ if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
+ (newsize > oldsize && (info->seals & F_SEAL_GROW)))
+ return -EPERM;
+
+ if (newsize != oldsize) {
+ error = shmem_reacct_size(SHMEM_I(inode)->flags,
+ oldsize, newsize);
+ if (error)
+ return error;
+ i_size_write(inode, newsize);
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+ }
+ if (newsize < oldsize) {
+ loff_t holebegin = round_up(newsize, PAGE_SIZE);
+ unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
+ shmem_truncate_range(inode, newsize, (loff_t)-1);
+ /* unmap again to remove racily COWed private pages */
+ unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
+ }
+ }
+
+ setattr_copy(inode, attr);
+ if (attr->ia_valid & ATTR_MODE)
+ error = posix_acl_chmod(inode, inode->i_mode);
+ return error;
+}
+
+static void shmem_evict_inode(struct inode *inode)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ if (inode->i_mapping->a_ops == &shmem_aops) {
+ shmem_unacct_size(info->flags, inode->i_size);
+ inode->i_size = 0;
+ shmem_truncate_range(inode, 0, (loff_t)-1);
+ if (!list_empty(&info->swaplist)) {
+ mutex_lock(&shmem_swaplist_mutex);
+ list_del_init(&info->swaplist);
+ mutex_unlock(&shmem_swaplist_mutex);
+ }
+ } else
+ kfree(info->symlink);
+
+ simple_xattrs_free(&info->xattrs);
+ WARN_ON(inode->i_blocks);
+ shmem_free_inode(inode->i_sb);
+ clear_inode(inode);
+}
+
+/*
+ * If swap found in inode, free it and move page from swapcache to filecache.
+ */
+static int shmem_unuse_inode(struct shmem_inode_info *info,
+ swp_entry_t swap, struct page **pagep)
+{
+ struct address_space *mapping = info->vfs_inode.i_mapping;
+ void *radswap;
+ pgoff_t index;
+ gfp_t gfp;
+ int error = 0;
+
+ radswap = swp_to_radix_entry(swap);
+ index = radix_tree_locate_item(&mapping->page_tree, radswap);
+ if (index == -1)
+ return -EAGAIN; /* tell shmem_unuse we found nothing */
+
+ /*
+ * Move _head_ to start search for next from here.
+ * But be careful: shmem_evict_inode checks list_empty without taking
+ * mutex, and there's an instant in list_move_tail when info->swaplist
+ * would appear empty, if it were the only one on shmem_swaplist.
+ */
+ if (shmem_swaplist.next != &info->swaplist)
+ list_move_tail(&shmem_swaplist, &info->swaplist);
+
+ gfp = mapping_gfp_mask(mapping);
+ if (shmem_should_replace_page(*pagep, gfp)) {
+ mutex_unlock(&shmem_swaplist_mutex);
+ error = shmem_replace_page(pagep, gfp, info, index);
+ mutex_lock(&shmem_swaplist_mutex);
+ /*
+ * We needed to drop mutex to make that restrictive page
+ * allocation, but the inode might have been freed while we
+ * dropped it: although a racing shmem_evict_inode() cannot
+ * complete without emptying the radix_tree, our page lock
+ * on this swapcache page is not enough to prevent that -
+ * free_swap_and_cache() of our swap entry will only
+ * trylock_page(), removing swap from radix_tree whatever.
+ *
+ * We must not proceed to shmem_add_to_page_cache() if the
+ * inode has been freed, but of course we cannot rely on
+ * inode or mapping or info to check that. However, we can
+ * safely check if our swap entry is still in use (and here
+ * it can't have got reused for another page): if it's still
+ * in use, then the inode cannot have been freed yet, and we
+ * can safely proceed (if it's no longer in use, that tells
+ * nothing about the inode, but we don't need to unuse swap).
+ */
+ if (!page_swapcount(*pagep))
+ error = -ENOENT;
+ }
+
+ /*
+ * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
+ * but also to hold up shmem_evict_inode(): so inode cannot be freed
+ * beneath us (pagelock doesn't help until the page is in pagecache).
+ */
+ if (!error)
+ error = shmem_add_to_page_cache(*pagep, mapping, index,
+ radswap);
+ if (error != -ENOMEM) {
+ /*
+ * Truncation and eviction use free_swap_and_cache(), which
+ * only does trylock page: if we raced, best clean up here.
+ */
+ delete_from_swap_cache(*pagep);
+ set_page_dirty(*pagep);
+ if (!error) {
+ spin_lock(&info->lock);
+ info->swapped--;
+ spin_unlock(&info->lock);
+ swap_free(swap);
+ }
+ }
+ return error;
+}
+
+/*
+ * Search through swapped inodes to find and replace swap by page.
+ */
+int shmem_unuse(swp_entry_t swap, struct page *page)
+{
+ struct list_head *this, *next;
+ struct shmem_inode_info *info;
+ struct mem_cgroup *memcg;
+ int error = 0;
+
+ /*
+ * There's a faint possibility that swap page was replaced before
+ * caller locked it: caller will come back later with the right page.
+ */
+ if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
+ goto out;
+
+ /*
+ * Charge page using GFP_KERNEL while we can wait, before taking
+ * the shmem_swaplist_mutex which might hold up shmem_writepage().
+ * Charged back to the user (not to caller) when swap account is used.
+ */
+ error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg);
+ if (error)
+ goto out;
+ /* No radix_tree_preload: swap entry keeps a place for page in tree */
+ error = -EAGAIN;
+
+ mutex_lock(&shmem_swaplist_mutex);
+ list_for_each_safe(this, next, &shmem_swaplist) {
+ info = list_entry(this, struct shmem_inode_info, swaplist);
+ if (info->swapped)
+ error = shmem_unuse_inode(info, swap, &page);
+ else
+ list_del_init(&info->swaplist);
+ cond_resched();
+ if (error != -EAGAIN)
+ break;
+ /* found nothing in this: move on to search the next */
+ }
+ mutex_unlock(&shmem_swaplist_mutex);
+
+ if (error) {
+ if (error != -ENOMEM)
+ error = 0;
+ mem_cgroup_cancel_charge(page, memcg);
+ } else
+ mem_cgroup_commit_charge(page, memcg, true);
+out:
+ unlock_page(page);
+ page_cache_release(page);
+ return error;
+}
+
+/*
+ * Move the page from the page cache to the swap cache.
+ */
+static int shmem_writepage(struct page *page, struct writeback_control *wbc)
+{
+ struct shmem_inode_info *info;
+ struct address_space *mapping;
+ struct inode *inode;
+ swp_entry_t swap;
+ pgoff_t index;
+
+ BUG_ON(!PageLocked(page));
+ mapping = page->mapping;
+ index = page->index;
+ inode = mapping->host;
+ info = SHMEM_I(inode);
+ if (info->flags & VM_LOCKED)
+ goto redirty;
+ if (!total_swap_pages)
+ goto redirty;
+
+ /*
+ * Our capabilities prevent regular writeback or sync from ever calling
+ * shmem_writepage; but a stacking filesystem might use ->writepage of
+ * its underlying filesystem, in which case tmpfs should write out to
+ * swap only in response to memory pressure, and not for the writeback
+ * threads or sync.
+ */
+ if (!wbc->for_reclaim) {
+ WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
+ goto redirty;
+ }
+
+ /*
+ * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
+ * value into swapfile.c, the only way we can correctly account for a
+ * fallocated page arriving here is now to initialize it and write it.
+ *
+ * That's okay for a page already fallocated earlier, but if we have
+ * not yet completed the fallocation, then (a) we want to keep track
+ * of this page in case we have to undo it, and (b) it may not be a
+ * good idea to continue anyway, once we're pushing into swap. So
+ * reactivate the page, and let shmem_fallocate() quit when too many.
+ */
+ if (!PageUptodate(page)) {
+ if (inode->i_private) {
+ struct shmem_falloc *shmem_falloc;
+ spin_lock(&inode->i_lock);
+ shmem_falloc = inode->i_private;
+ if (shmem_falloc &&
+ !shmem_falloc->waitq &&
+ index >= shmem_falloc->start &&
+ index < shmem_falloc->next)
+ shmem_falloc->nr_unswapped++;
+ else
+ shmem_falloc = NULL;
+ spin_unlock(&inode->i_lock);
+ if (shmem_falloc)
+ goto redirty;
+ }
+ clear_highpage(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+ }
+
+ swap = get_swap_page();
+ if (!swap.val)
+ goto redirty;
+
+ /*
+ * Add inode to shmem_unuse()'s list of swapped-out inodes,
+ * if it's not already there. Do it now before the page is
+ * moved to swap cache, when its pagelock no longer protects
+ * the inode from eviction. But don't unlock the mutex until
+ * we've incremented swapped, because shmem_unuse_inode() will
+ * prune a !swapped inode from the swaplist under this mutex.
+ */
+ mutex_lock(&shmem_swaplist_mutex);
+ if (list_empty(&info->swaplist))
+ list_add_tail(&info->swaplist, &shmem_swaplist);
+
+ if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
+ swap_shmem_alloc(swap);
+ shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
+
+ spin_lock(&info->lock);
+ info->swapped++;
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+
+ mutex_unlock(&shmem_swaplist_mutex);
+ BUG_ON(page_mapped(page));
+ swap_writepage(page, wbc);
+ return 0;
+ }
+
+ mutex_unlock(&shmem_swaplist_mutex);
+ swapcache_free(swap);
+redirty:
+ set_page_dirty(page);
+ if (wbc->for_reclaim)
+ return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
+ unlock_page(page);
+ return 0;
+}
+
+#ifdef CONFIG_NUMA
+#ifdef CONFIG_TMPFS
+static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
+{
+ char buffer[64];
+
+ if (!mpol || mpol->mode == MPOL_DEFAULT)
+ return; /* show nothing */
+
+ mpol_to_str(buffer, sizeof(buffer), mpol);
+
+ seq_printf(seq, ",mpol=%s", buffer);
+}
+
+static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
+{
+ struct mempolicy *mpol = NULL;
+ if (sbinfo->mpol) {
+ spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
+ mpol = sbinfo->mpol;
+ mpol_get(mpol);
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ return mpol;
+}
+#endif /* CONFIG_TMPFS */
+
+static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ struct vm_area_struct pvma;
+ struct page *page;
+
+ /* Create a pseudo vma that just contains the policy */
+ pvma.vm_start = 0;
+ /* Bias interleave by inode number to distribute better across nodes */
+ pvma.vm_pgoff = index + info->vfs_inode.i_ino;
+ pvma.vm_ops = NULL;
+ pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+
+ page = swapin_readahead(swap, gfp, &pvma, 0);
+
+ /* Drop reference taken by mpol_shared_policy_lookup() */
+ mpol_cond_put(pvma.vm_policy);
+
+ return page;
+}
+
+static struct page *shmem_alloc_page(gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ struct vm_area_struct pvma;
+ struct page *page;
+
+ /* Create a pseudo vma that just contains the policy */
+ pvma.vm_start = 0;
+ /* Bias interleave by inode number to distribute better across nodes */
+ pvma.vm_pgoff = index + info->vfs_inode.i_ino;
+ pvma.vm_ops = NULL;
+ pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+
+ page = alloc_page_vma(gfp, &pvma, 0);
+
+ /* Drop reference taken by mpol_shared_policy_lookup() */
+ mpol_cond_put(pvma.vm_policy);
+
+ return page;
+}
+#else /* !CONFIG_NUMA */
+#ifdef CONFIG_TMPFS
+static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
+{
+}
+#endif /* CONFIG_TMPFS */
+
+static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ return swapin_readahead(swap, gfp, NULL, 0);
+}
+
+static inline struct page *shmem_alloc_page(gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ return alloc_page(gfp);
+}
+#endif /* CONFIG_NUMA */
+
+#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
+static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
+{
+ return NULL;
+}
+#endif
+
+/*
+ * When a page is moved from swapcache to shmem filecache (either by the
+ * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
+ * shmem_unuse_inode()), it may have been read in earlier from swap, in
+ * ignorance of the mapping it belongs to. If that mapping has special
+ * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
+ * we may need to copy to a suitable page before moving to filecache.
+ *
+ * In a future release, this may well be extended to respect cpuset and
+ * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
+ * but for now it is a simple matter of zone.
+ */
+static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
+{
+ return page_zonenum(page) > gfp_zone(gfp);
+}
+
+static int shmem_replace_page(struct page **pagep, gfp_t gfp,
+ struct shmem_inode_info *info, pgoff_t index)
+{
+ struct page *oldpage, *newpage;
+ struct address_space *swap_mapping;
+ pgoff_t swap_index;
+ int error;
+
+ oldpage = *pagep;
+ swap_index = page_private(oldpage);
+ swap_mapping = page_mapping(oldpage);
+
+ /*
+ * We have arrived here because our zones are constrained, so don't
+ * limit chance of success by further cpuset and node constraints.
+ */
+ gfp &= ~GFP_CONSTRAINT_MASK;
+ newpage = shmem_alloc_page(gfp, info, index);
+ if (!newpage)
+ return -ENOMEM;
+
+ page_cache_get(newpage);
+ copy_highpage(newpage, oldpage);
+ flush_dcache_page(newpage);
+
+ __set_page_locked(newpage);
+ SetPageUptodate(newpage);
+ SetPageSwapBacked(newpage);
+ set_page_private(newpage, swap_index);
+ SetPageSwapCache(newpage);
+
+ /*
+ * Our caller will very soon move newpage out of swapcache, but it's
+ * a nice clean interface for us to replace oldpage by newpage there.
+ */
+ spin_lock_irq(&swap_mapping->tree_lock);
+ error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
+ newpage);
+ if (!error) {
+ __inc_zone_page_state(newpage, NR_FILE_PAGES);
+ __dec_zone_page_state(oldpage, NR_FILE_PAGES);
+ }
+ spin_unlock_irq(&swap_mapping->tree_lock);
+
+ if (unlikely(error)) {
+ /*
+ * Is this possible? I think not, now that our callers check
+ * both PageSwapCache and page_private after getting page lock;
+ * but be defensive. Reverse old to newpage for clear and free.
+ */
+ oldpage = newpage;
+ } else {
+ mem_cgroup_migrate(oldpage, newpage, true);
+ lru_cache_add_anon(newpage);
+ *pagep = newpage;
+ }
+
+ ClearPageSwapCache(oldpage);
+ set_page_private(oldpage, 0);
+
+ unlock_page(oldpage);
+ page_cache_release(oldpage);
+ page_cache_release(oldpage);
+ return error;
+}
+
+/*
+ * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
+ *
+ * If we allocate a new one we do not mark it dirty. That's up to the
+ * vm. If we swap it in we mark it dirty since we also free the swap
+ * entry since a page cannot live in both the swap and page cache
+ */
+static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
+ struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct shmem_inode_info *info;
+ struct shmem_sb_info *sbinfo;
+ struct mem_cgroup *memcg;
+ struct page *page;
+ swp_entry_t swap;
+ int error;
+ int once = 0;
+ int alloced = 0;
+
+ if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
+ return -EFBIG;
+repeat:
+ swap.val = 0;
+ page = find_lock_entry(mapping, index);
+ if (radix_tree_exceptional_entry(page)) {
+ swap = radix_to_swp_entry(page);
+ page = NULL;
+ }
+
+ if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
+ ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
+ error = -EINVAL;
+ goto failed;
+ }
+
+ if (page && sgp == SGP_WRITE)
+ mark_page_accessed(page);
+
+ /* fallocated page? */
+ if (page && !PageUptodate(page)) {
+ if (sgp != SGP_READ)
+ goto clear;
+ unlock_page(page);
+ page_cache_release(page);
+ page = NULL;
+ }
+ if (page || (sgp == SGP_READ && !swap.val)) {
+ *pagep = page;
+ return 0;
+ }
+
+ /*
+ * Fast cache lookup did not find it:
+ * bring it back from swap or allocate.
+ */
+ info = SHMEM_I(inode);
+ sbinfo = SHMEM_SB(inode->i_sb);
+
+ if (swap.val) {
+ /* Look it up and read it in.. */
+ page = lookup_swap_cache(swap);
+ if (!page) {
+ /* here we actually do the io */
+ if (fault_type)
+ *fault_type |= VM_FAULT_MAJOR;
+ page = shmem_swapin(swap, gfp, info, index);
+ if (!page) {
+ error = -ENOMEM;
+ goto failed;
+ }
+ }
+
+ /* We have to do this with page locked to prevent races */
+ lock_page(page);
+ if (!PageSwapCache(page) || page_private(page) != swap.val ||
+ !shmem_confirm_swap(mapping, index, swap)) {
+ error = -EEXIST; /* try again */
+ goto unlock;
+ }
+ if (!PageUptodate(page)) {
+ error = -EIO;
+ goto failed;
+ }
+ wait_on_page_writeback(page);
+
+ if (shmem_should_replace_page(page, gfp)) {
+ error = shmem_replace_page(&page, gfp, info, index);
+ if (error)
+ goto failed;
+ }
+
+ error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
+ if (!error) {
+ error = shmem_add_to_page_cache(page, mapping, index,
+ swp_to_radix_entry(swap));
+ /*
+ * We already confirmed swap under page lock, and make
+ * no memory allocation here, so usually no possibility
+ * of error; but free_swap_and_cache() only trylocks a
+ * page, so it is just possible that the entry has been
+ * truncated or holepunched since swap was confirmed.
+ * shmem_undo_range() will have done some of the
+ * unaccounting, now delete_from_swap_cache() will do
+ * the rest.
+ * Reset swap.val? No, leave it so "failed" goes back to
+ * "repeat": reading a hole and writing should succeed.
+ */
+ if (error) {
+ mem_cgroup_cancel_charge(page, memcg);
+ delete_from_swap_cache(page);
+ }
+ }
+ if (error)
+ goto failed;
+
+ mem_cgroup_commit_charge(page, memcg, true);
+
+ spin_lock(&info->lock);
+ info->swapped--;
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+
+ if (sgp == SGP_WRITE)
+ mark_page_accessed(page);
+
+ delete_from_swap_cache(page);
+ set_page_dirty(page);
+ swap_free(swap);
+
+ } else {
+ if (shmem_acct_block(info->flags)) {
+ error = -ENOSPC;
+ goto failed;
+ }
+ if (sbinfo->max_blocks) {
+ if (percpu_counter_compare(&sbinfo->used_blocks,
+ sbinfo->max_blocks) >= 0) {
+ error = -ENOSPC;
+ goto unacct;
+ }
+ percpu_counter_inc(&sbinfo->used_blocks);
+ }
+
+ page = shmem_alloc_page(gfp, info, index);
+ if (!page) {
+ error = -ENOMEM;
+ goto decused;
+ }
+
+ __SetPageSwapBacked(page);
+ __set_page_locked(page);
+ if (sgp == SGP_WRITE)
+ __SetPageReferenced(page);
+
+ error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
+ if (error)
+ goto decused;
+ error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
+ if (!error) {
+ error = shmem_add_to_page_cache(page, mapping, index,
+ NULL);
+ radix_tree_preload_end();
+ }
+ if (error) {
+ mem_cgroup_cancel_charge(page, memcg);
+ goto decused;
+ }
+ mem_cgroup_commit_charge(page, memcg, false);
+ lru_cache_add_anon(page);
+
+ spin_lock(&info->lock);
+ info->alloced++;
+ inode->i_blocks += BLOCKS_PER_PAGE;
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+ alloced = true;
+
+ /*
+ * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
+ */
+ if (sgp == SGP_FALLOC)
+ sgp = SGP_WRITE;
+clear:
+ /*
+ * Let SGP_WRITE caller clear ends if write does not fill page;
+ * but SGP_FALLOC on a page fallocated earlier must initialize
+ * it now, lest undo on failure cancel our earlier guarantee.
+ */
+ if (sgp != SGP_WRITE) {
+ clear_highpage(page);
+ flush_dcache_page(page);
+ SetPageUptodate(page);
+ }
+ if (sgp == SGP_DIRTY)
+ set_page_dirty(page);
+ }
+
+ /* Perhaps the file has been truncated since we checked */
+ if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
+ ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
+ error = -EINVAL;
+ if (alloced)
+ goto trunc;
+ else
+ goto failed;
+ }
+ *pagep = page;
+ return 0;
+
+ /*
+ * Error recovery.
+ */
+trunc:
+ info = SHMEM_I(inode);
+ ClearPageDirty(page);
+ delete_from_page_cache(page);
+ spin_lock(&info->lock);
+ info->alloced--;
+ inode->i_blocks -= BLOCKS_PER_PAGE;
+ spin_unlock(&info->lock);
+decused:
+ sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo->max_blocks)
+ percpu_counter_add(&sbinfo->used_blocks, -1);
+unacct:
+ shmem_unacct_blocks(info->flags, 1);
+failed:
+ if (swap.val && error != -EINVAL &&
+ !shmem_confirm_swap(mapping, index, swap))
+ error = -EEXIST;
+unlock:
+ if (page) {
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ if (error == -ENOSPC && !once++) {
+ info = SHMEM_I(inode);
+ spin_lock(&info->lock);
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+ goto repeat;
+ }
+ if (error == -EEXIST) /* from above or from radix_tree_insert */
+ goto repeat;
+ return error;
+}
+
+static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct inode *inode = file_inode(vma->vm_file);
+ int error;
+ int ret = VM_FAULT_LOCKED;
+
+ /*
+ * Trinity finds that probing a hole which tmpfs is punching can
+ * prevent the hole-punch from ever completing: which in turn
+ * locks writers out with its hold on i_mutex. So refrain from
+ * faulting pages into the hole while it's being punched. Although
+ * shmem_undo_range() does remove the additions, it may be unable to
+ * keep up, as each new page needs its own unmap_mapping_range() call,
+ * and the i_mmap tree grows ever slower to scan if new vmas are added.
+ *
+ * It does not matter if we sometimes reach this check just before the
+ * hole-punch begins, so that one fault then races with the punch:
+ * we just need to make racing faults a rare case.
+ *
+ * The implementation below would be much simpler if we just used a
+ * standard mutex or completion: but we cannot take i_mutex in fault,
+ * and bloating every shmem inode for this unlikely case would be sad.
+ */
+ if (unlikely(inode->i_private)) {
+ struct shmem_falloc *shmem_falloc;
+
+ spin_lock(&inode->i_lock);
+ shmem_falloc = inode->i_private;
+ if (shmem_falloc &&
+ shmem_falloc->waitq &&
+ vmf->pgoff >= shmem_falloc->start &&
+ vmf->pgoff < shmem_falloc->next) {
+ wait_queue_head_t *shmem_falloc_waitq;
+ DEFINE_WAIT(shmem_fault_wait);
+
+ ret = VM_FAULT_NOPAGE;
+ if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
+ !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
+ /* It's polite to up mmap_sem if we can */
+ up_read(&vma->vm_mm->mmap_sem);
+ ret = VM_FAULT_RETRY;
+ }
+
+ shmem_falloc_waitq = shmem_falloc->waitq;
+ prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
+ TASK_UNINTERRUPTIBLE);
+ spin_unlock(&inode->i_lock);
+ schedule();
+
+ /*
+ * shmem_falloc_waitq points into the shmem_fallocate()
+ * stack of the hole-punching task: shmem_falloc_waitq
+ * is usually invalid by the time we reach here, but
+ * finish_wait() does not dereference it in that case;
+ * though i_lock needed lest racing with wake_up_all().
+ */
+ spin_lock(&inode->i_lock);
+ finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
+ spin_unlock(&inode->i_lock);
+ return ret;
+ }
+ spin_unlock(&inode->i_lock);
+ }
+
+ error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
+ if (error)
+ return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
+
+ if (ret & VM_FAULT_MAJOR) {
+ count_vm_event(PGMAJFAULT);
+ mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
+ }
+ return ret;
+}
+
+#ifdef CONFIG_NUMA
+static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
+{
+ struct inode *inode = file_inode(vma->vm_file);
+ return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
+}
+
+static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct inode *inode = file_inode(vma->vm_file);
+ pgoff_t index;
+
+ index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
+}
+#endif
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+ struct inode *inode = file_inode(file);
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ int retval = -ENOMEM;
+
+ spin_lock(&info->lock);
+ if (lock && !(info->flags & VM_LOCKED)) {
+ if (!user_shm_lock(inode->i_size, user))
+ goto out_nomem;
+ info->flags |= VM_LOCKED;
+ mapping_set_unevictable(file->f_mapping);
+ }
+ if (!lock && (info->flags & VM_LOCKED) && user) {
+ user_shm_unlock(inode->i_size, user);
+ info->flags &= ~VM_LOCKED;
+ mapping_clear_unevictable(file->f_mapping);
+ }
+ retval = 0;
+
+out_nomem:
+ spin_unlock(&info->lock);
+ return retval;
+}
+
+static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ file_accessed(file);
+ vma->vm_ops = &shmem_vm_ops;
+ return 0;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
+ umode_t mode, dev_t dev, unsigned long flags)
+{
+ struct inode *inode;
+ struct shmem_inode_info *info;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ if (shmem_reserve_inode(sb))
+ return NULL;
+
+ inode = new_inode(sb);
+ if (inode) {
+ inode->i_ino = get_next_ino();
+ inode_init_owner(inode, dir, mode);
+ inode->i_blocks = 0;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ inode->i_generation = get_seconds();
+ info = SHMEM_I(inode);
+ memset(info, 0, (char *)inode - (char *)info);
+ spin_lock_init(&info->lock);
+ info->seals = F_SEAL_SEAL;
+ info->flags = flags & VM_NORESERVE;
+ INIT_LIST_HEAD(&info->swaplist);
+ simple_xattrs_init(&info->xattrs);
+ cache_no_acl(inode);
+
+ switch (mode & S_IFMT) {
+ default:
+ inode->i_op = &shmem_special_inode_operations;
+ init_special_inode(inode, mode, dev);
+ break;
+ case S_IFREG:
+ inode->i_mapping->a_ops = &shmem_aops;
+ inode->i_op = &shmem_inode_operations;
+ inode->i_fop = &shmem_file_operations;
+ mpol_shared_policy_init(&info->policy,
+ shmem_get_sbmpol(sbinfo));
+ break;
+ case S_IFDIR:
+ inc_nlink(inode);
+ /* Some things misbehave if size == 0 on a directory */
+ inode->i_size = 2 * BOGO_DIRENT_SIZE;
+ inode->i_op = &shmem_dir_inode_operations;
+ inode->i_fop = &simple_dir_operations;
+ break;
+ case S_IFLNK:
+ /*
+ * Must not load anything in the rbtree,
+ * mpol_free_shared_policy will not be called.
+ */
+ mpol_shared_policy_init(&info->policy, NULL);
+ break;
+ }
+ } else
+ shmem_free_inode(sb);
+ return inode;
+}
+
+bool shmem_mapping(struct address_space *mapping)
+{
+ if (!mapping->host)
+ return false;
+
+ return mapping->host->i_sb->s_op == &shmem_ops;
+}
+
+#ifdef CONFIG_TMPFS
+static const struct inode_operations shmem_symlink_inode_operations;
+static const struct inode_operations shmem_short_symlink_operations;
+
+#ifdef CONFIG_TMPFS_XATTR
+static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
+#else
+#define shmem_initxattrs NULL
+#endif
+
+static int
+shmem_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata)
+{
+ struct inode *inode = mapping->host;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+
+ /* i_mutex is held by caller */
+ if (unlikely(info->seals)) {
+ if (info->seals & F_SEAL_WRITE)
+ return -EPERM;
+ if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
+ return -EPERM;
+ }
+
+ return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
+}
+
+static int
+shmem_write_end(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned copied,
+ struct page *page, void *fsdata)
+{
+ struct inode *inode = mapping->host;
+
+ if (pos + copied > inode->i_size)
+ i_size_write(inode, pos + copied);
+
+ if (!PageUptodate(page)) {
+ if (copied < PAGE_CACHE_SIZE) {
+ unsigned from = pos & (PAGE_CACHE_SIZE - 1);
+ zero_user_segments(page, 0, from,
+ from + copied, PAGE_CACHE_SIZE);
+ }
+ SetPageUptodate(page);
+ }
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+
+ return copied;
+}
+
+static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ struct address_space *mapping = inode->i_mapping;
+ pgoff_t index;
+ unsigned long offset;
+ enum sgp_type sgp = SGP_READ;
+ int error = 0;
+ ssize_t retval = 0;
+ loff_t *ppos = &iocb->ki_pos;
+
+ /*
+ * Might this read be for a stacking filesystem? Then when reading
+ * holes of a sparse file, we actually need to allocate those pages,
+ * and even mark them dirty, so it cannot exceed the max_blocks limit.
+ */
+ if (!iter_is_iovec(to))
+ sgp = SGP_DIRTY;
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ offset = *ppos & ~PAGE_CACHE_MASK;
+
+ for (;;) {
+ struct page *page = NULL;
+ pgoff_t end_index;
+ unsigned long nr, ret;
+ loff_t i_size = i_size_read(inode);
+
+ end_index = i_size >> PAGE_CACHE_SHIFT;
+ if (index > end_index)
+ break;
+ if (index == end_index) {
+ nr = i_size & ~PAGE_CACHE_MASK;
+ if (nr <= offset)
+ break;
+ }
+
+ error = shmem_getpage(inode, index, &page, sgp, NULL);
+ if (error) {
+ if (error == -EINVAL)
+ error = 0;
+ break;
+ }
+ if (page)
+ unlock_page(page);
+
+ /*
+ * We must evaluate after, since reads (unlike writes)
+ * are called without i_mutex protection against truncate
+ */
+ nr = PAGE_CACHE_SIZE;
+ i_size = i_size_read(inode);
+ end_index = i_size >> PAGE_CACHE_SHIFT;
+ if (index == end_index) {
+ nr = i_size & ~PAGE_CACHE_MASK;
+ if (nr <= offset) {
+ if (page)
+ page_cache_release(page);
+ break;
+ }
+ }
+ nr -= offset;
+
+ if (page) {
+ /*
+ * If users can be writing to this page using arbitrary
+ * virtual addresses, take care about potential aliasing
+ * before reading the page on the kernel side.
+ */
+ if (mapping_writably_mapped(mapping))
+ flush_dcache_page(page);
+ /*
+ * Mark the page accessed if we read the beginning.
+ */
+ if (!offset)
+ mark_page_accessed(page);
+ } else {
+ page = ZERO_PAGE(0);
+ page_cache_get(page);
+ }
+
+ /*
+ * Ok, we have the page, and it's up-to-date, so
+ * now we can copy it to user space...
+ */
+ ret = copy_page_to_iter(page, offset, nr, to);
+ retval += ret;
+ offset += ret;
+ index += offset >> PAGE_CACHE_SHIFT;
+ offset &= ~PAGE_CACHE_MASK;
+
+ page_cache_release(page);
+ if (!iov_iter_count(to))
+ break;
+ if (ret < nr) {
+ error = -EFAULT;
+ break;
+ }
+ cond_resched();
+ }
+
+ *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+ file_accessed(file);
+ return retval ? retval : error;
+}
+
+static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ struct address_space *mapping = in->f_mapping;
+ struct inode *inode = mapping->host;
+ unsigned int loff, nr_pages, req_pages;
+ struct page *pages[PIPE_DEF_BUFFERS];
+ struct partial_page partial[PIPE_DEF_BUFFERS];
+ struct page *page;
+ pgoff_t index, end_index;
+ loff_t isize, left;
+ int error, page_nr;
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .nr_pages_max = PIPE_DEF_BUFFERS,
+ .flags = flags,
+ .ops = &page_cache_pipe_buf_ops,
+ .spd_release = spd_release_page,
+ };
+
+ isize = i_size_read(inode);
+ if (unlikely(*ppos >= isize))
+ return 0;
+
+ left = isize - *ppos;
+ if (unlikely(left < len))
+ len = left;
+
+ if (splice_grow_spd(pipe, &spd))
+ return -ENOMEM;
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ loff = *ppos & ~PAGE_CACHE_MASK;
+ req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ nr_pages = min(req_pages, spd.nr_pages_max);
+
+ spd.nr_pages = find_get_pages_contig(mapping, index,
+ nr_pages, spd.pages);
+ index += spd.nr_pages;
+ error = 0;
+
+ while (spd.nr_pages < nr_pages) {
+ error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
+ if (error)
+ break;
+ unlock_page(page);
+ spd.pages[spd.nr_pages++] = page;
+ index++;
+ }
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ nr_pages = spd.nr_pages;
+ spd.nr_pages = 0;
+
+ for (page_nr = 0; page_nr < nr_pages; page_nr++) {
+ unsigned int this_len;
+
+ if (!len)
+ break;
+
+ this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
+ page = spd.pages[page_nr];
+
+ if (!PageUptodate(page) || page->mapping != mapping) {
+ error = shmem_getpage(inode, index, &page,
+ SGP_CACHE, NULL);
+ if (error)
+ break;
+ unlock_page(page);
+ page_cache_release(spd.pages[page_nr]);
+ spd.pages[page_nr] = page;
+ }
+
+ isize = i_size_read(inode);
+ end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+ if (unlikely(!isize || index > end_index))
+ break;
+
+ if (end_index == index) {
+ unsigned int plen;
+
+ plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
+ if (plen <= loff)
+ break;
+
+ this_len = min(this_len, plen - loff);
+ len = this_len;
+ }
+
+ spd.partial[page_nr].offset = loff;
+ spd.partial[page_nr].len = this_len;
+ len -= this_len;
+ loff = 0;
+ spd.nr_pages++;
+ index++;
+ }
+
+ while (page_nr < nr_pages)
+ page_cache_release(spd.pages[page_nr++]);
+
+ if (spd.nr_pages)
+ error = splice_to_pipe(pipe, &spd);
+
+ splice_shrink_spd(&spd);
+
+ if (error > 0) {
+ *ppos += error;
+ file_accessed(in);
+ }
+ return error;
+}
+
+/*
+ * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
+ */
+static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
+ pgoff_t index, pgoff_t end, int whence)
+{
+ struct page *page;
+ struct pagevec pvec;
+ pgoff_t indices[PAGEVEC_SIZE];
+ bool done = false;
+ int i;
+
+ pagevec_init(&pvec, 0);
+ pvec.nr = 1; /* start small: we may be there already */
+ while (!done) {
+ pvec.nr = find_get_entries(mapping, index,
+ pvec.nr, pvec.pages, indices);
+ if (!pvec.nr) {
+ if (whence == SEEK_DATA)
+ index = end;
+ break;
+ }
+ for (i = 0; i < pvec.nr; i++, index++) {
+ if (index < indices[i]) {
+ if (whence == SEEK_HOLE) {
+ done = true;
+ break;
+ }
+ index = indices[i];
+ }
+ page = pvec.pages[i];
+ if (page && !radix_tree_exceptional_entry(page)) {
+ if (!PageUptodate(page))
+ page = NULL;
+ }
+ if (index >= end ||
+ (page && whence == SEEK_DATA) ||
+ (!page && whence == SEEK_HOLE)) {
+ done = true;
+ break;
+ }
+ }
+ pagevec_remove_exceptionals(&pvec);
+ pagevec_release(&pvec);
+ pvec.nr = PAGEVEC_SIZE;
+ cond_resched();
+ }
+ return index;
+}
+
+static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ pgoff_t start, end;
+ loff_t new_offset;
+
+ if (whence != SEEK_DATA && whence != SEEK_HOLE)
+ return generic_file_llseek_size(file, offset, whence,
+ MAX_LFS_FILESIZE, i_size_read(inode));
+ mutex_lock(&inode->i_mutex);
+ /* We're holding i_mutex so we can access i_size directly */
+
+ if (offset < 0)
+ offset = -EINVAL;
+ else if (offset >= inode->i_size)
+ offset = -ENXIO;
+ else {
+ start = offset >> PAGE_CACHE_SHIFT;
+ end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ new_offset = shmem_seek_hole_data(mapping, start, end, whence);
+ new_offset <<= PAGE_CACHE_SHIFT;
+ if (new_offset > offset) {
+ if (new_offset < inode->i_size)
+ offset = new_offset;
+ else if (whence == SEEK_DATA)
+ offset = -ENXIO;
+ else
+ offset = inode->i_size;
+ }
+ }
+
+ if (offset >= 0)
+ offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
+ mutex_unlock(&inode->i_mutex);
+ return offset;
+}
+
+/*
+ * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
+ * so reuse a tag which we firmly believe is never set or cleared on shmem.
+ */
+#define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE
+#define LAST_SCAN 4 /* about 150ms max */
+
+static void shmem_tag_pins(struct address_space *mapping)
+{
+ struct radix_tree_iter iter;
+ void **slot;
+ pgoff_t start;
+ struct page *page;
+
+ lru_add_drain();
+ start = 0;
+ rcu_read_lock();
+
+restart:
+ radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+ page = radix_tree_deref_slot(slot);
+ if (!page || radix_tree_exception(page)) {
+ if (radix_tree_deref_retry(page))
+ goto restart;
+ } else if (page_count(page) - page_mapcount(page) > 1) {
+ spin_lock_irq(&mapping->tree_lock);
+ radix_tree_tag_set(&mapping->page_tree, iter.index,
+ SHMEM_TAG_PINNED);
+ spin_unlock_irq(&mapping->tree_lock);
+ }
+
+ if (need_resched()) {
+ cond_resched_rcu();
+ start = iter.index + 1;
+ goto restart;
+ }
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Setting SEAL_WRITE requires us to verify there's no pending writer. However,
+ * via get_user_pages(), drivers might have some pending I/O without any active
+ * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
+ * and see whether it has an elevated ref-count. If so, we tag them and wait for
+ * them to be dropped.
+ * The caller must guarantee that no new user will acquire writable references
+ * to those pages to avoid races.
+ */
+static int shmem_wait_for_pins(struct address_space *mapping)
+{
+ struct radix_tree_iter iter;
+ void **slot;
+ pgoff_t start;
+ struct page *page;
+ int error, scan;
+
+ shmem_tag_pins(mapping);
+
+ error = 0;
+ for (scan = 0; scan <= LAST_SCAN; scan++) {
+ if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
+ break;
+
+ if (!scan)
+ lru_add_drain_all();
+ else if (schedule_timeout_killable((HZ << scan) / 200))
+ scan = LAST_SCAN;
+
+ start = 0;
+ rcu_read_lock();
+restart:
+ radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
+ start, SHMEM_TAG_PINNED) {
+
+ page = radix_tree_deref_slot(slot);
+ if (radix_tree_exception(page)) {
+ if (radix_tree_deref_retry(page))
+ goto restart;
+
+ page = NULL;
+ }
+
+ if (page &&
+ page_count(page) - page_mapcount(page) != 1) {
+ if (scan < LAST_SCAN)
+ goto continue_resched;
+
+ /*
+ * On the last scan, we clean up all those tags
+ * we inserted; but make a note that we still
+ * found pages pinned.
+ */
+ error = -EBUSY;
+ }
+
+ spin_lock_irq(&mapping->tree_lock);
+ radix_tree_tag_clear(&mapping->page_tree,
+ iter.index, SHMEM_TAG_PINNED);
+ spin_unlock_irq(&mapping->tree_lock);
+continue_resched:
+ if (need_resched()) {
+ cond_resched_rcu();
+ start = iter.index + 1;
+ goto restart;
+ }
+ }
+ rcu_read_unlock();
+ }
+
+ return error;
+}
+
+#define F_ALL_SEALS (F_SEAL_SEAL | \
+ F_SEAL_SHRINK | \
+ F_SEAL_GROW | \
+ F_SEAL_WRITE)
+
+int shmem_add_seals(struct file *file, unsigned int seals)
+{
+ struct inode *inode = file_inode(file);
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ int error;
+
+ /*
+ * SEALING
+ * Sealing allows multiple parties to share a shmem-file but restrict
+ * access to a specific subset of file operations. Seals can only be
+ * added, but never removed. This way, mutually untrusted parties can
+ * share common memory regions with a well-defined policy. A malicious
+ * peer can thus never perform unwanted operations on a shared object.
+ *
+ * Seals are only supported on special shmem-files and always affect
+ * the whole underlying inode. Once a seal is set, it may prevent some
+ * kinds of access to the file. Currently, the following seals are
+ * defined:
+ * SEAL_SEAL: Prevent further seals from being set on this file
+ * SEAL_SHRINK: Prevent the file from shrinking
+ * SEAL_GROW: Prevent the file from growing
+ * SEAL_WRITE: Prevent write access to the file
+ *
+ * As we don't require any trust relationship between two parties, we
+ * must prevent seals from being removed. Therefore, sealing a file
+ * only adds a given set of seals to the file, it never touches
+ * existing seals. Furthermore, the "setting seals"-operation can be
+ * sealed itself, which basically prevents any further seal from being
+ * added.
+ *
+ * Semantics of sealing are only defined on volatile files. Only
+ * anonymous shmem files support sealing. More importantly, seals are
+ * never written to disk. Therefore, there's no plan to support it on
+ * other file types.
+ */
+
+ if (file->f_op != &shmem_file_operations)
+ return -EINVAL;
+ if (!(file->f_mode & FMODE_WRITE))
+ return -EPERM;
+ if (seals & ~(unsigned int)F_ALL_SEALS)
+ return -EINVAL;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (info->seals & F_SEAL_SEAL) {
+ error = -EPERM;
+ goto unlock;
+ }
+
+ if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
+ error = mapping_deny_writable(file->f_mapping);
+ if (error)
+ goto unlock;
+
+ error = shmem_wait_for_pins(file->f_mapping);
+ if (error) {
+ mapping_allow_writable(file->f_mapping);
+ goto unlock;
+ }
+ }
+
+ info->seals |= seals;
+ error = 0;
+
+unlock:
+ mutex_unlock(&inode->i_mutex);
+ return error;
+}
+EXPORT_SYMBOL_GPL(shmem_add_seals);
+
+int shmem_get_seals(struct file *file)
+{
+ if (file->f_op != &shmem_file_operations)
+ return -EINVAL;
+
+ return SHMEM_I(file_inode(file))->seals;
+}
+EXPORT_SYMBOL_GPL(shmem_get_seals);
+
+long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ long error;
+
+ switch (cmd) {
+ case F_ADD_SEALS:
+ /* disallow upper 32bit */
+ if (arg > UINT_MAX)
+ return -EINVAL;
+
+ error = shmem_add_seals(file, arg);
+ break;
+ case F_GET_SEALS:
+ error = shmem_get_seals(file);
+ break;
+ default:
+ error = -EINVAL;
+ break;
+ }
+
+ return error;
+}
+
+static long shmem_fallocate(struct file *file, int mode, loff_t offset,
+ loff_t len)
+{
+ struct inode *inode = file_inode(file);
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ struct shmem_falloc shmem_falloc;
+ pgoff_t start, index, end;
+ int error;
+
+ if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
+ return -EOPNOTSUPP;
+
+ mutex_lock(&inode->i_mutex);
+
+ if (mode & FALLOC_FL_PUNCH_HOLE) {
+ struct address_space *mapping = file->f_mapping;
+ loff_t unmap_start = round_up(offset, PAGE_SIZE);
+ loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
+
+ /* protected by i_mutex */
+ if (info->seals & F_SEAL_WRITE) {
+ error = -EPERM;
+ goto out;
+ }
+
+ shmem_falloc.waitq = &shmem_falloc_waitq;
+ shmem_falloc.start = unmap_start >> PAGE_SHIFT;
+ shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
+ spin_lock(&inode->i_lock);
+ inode->i_private = &shmem_falloc;
+ spin_unlock(&inode->i_lock);
+
+ if ((u64)unmap_end > (u64)unmap_start)
+ unmap_mapping_range(mapping, unmap_start,
+ 1 + unmap_end - unmap_start, 0);
+ shmem_truncate_range(inode, offset, offset + len - 1);
+ /* No need to unmap again: hole-punching leaves COWed pages */
+
+ spin_lock(&inode->i_lock);
+ inode->i_private = NULL;
+ wake_up_all(&shmem_falloc_waitq);
+ spin_unlock(&inode->i_lock);
+ error = 0;
+ goto out;
+ }
+
+ /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
+ error = inode_newsize_ok(inode, offset + len);
+ if (error)
+ goto out;
+
+ if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
+ error = -EPERM;
+ goto out;
+ }
+
+ start = offset >> PAGE_CACHE_SHIFT;
+ end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ /* Try to avoid a swapstorm if len is impossible to satisfy */
+ if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
+ error = -ENOSPC;
+ goto out;
+ }
+
+ shmem_falloc.waitq = NULL;
+ shmem_falloc.start = start;
+ shmem_falloc.next = start;
+ shmem_falloc.nr_falloced = 0;
+ shmem_falloc.nr_unswapped = 0;
+ spin_lock(&inode->i_lock);
+ inode->i_private = &shmem_falloc;
+ spin_unlock(&inode->i_lock);
+
+ for (index = start; index < end; index++) {
+ struct page *page;
+
+ /*
+ * Good, the fallocate(2) manpage permits EINTR: we may have
+ * been interrupted because we are using up too much memory.
+ */
+ if (signal_pending(current))
+ error = -EINTR;
+ else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
+ error = -ENOMEM;
+ else
+ error = shmem_getpage(inode, index, &page, SGP_FALLOC,
+ NULL);
+ if (error) {
+ /* Remove the !PageUptodate pages we added */
+ shmem_undo_range(inode,
+ (loff_t)start << PAGE_CACHE_SHIFT,
+ (loff_t)index << PAGE_CACHE_SHIFT, true);
+ goto undone;
+ }
+
+ /*
+ * Inform shmem_writepage() how far we have reached.
+ * No need for lock or barrier: we have the page lock.
+ */
+ shmem_falloc.next++;
+ if (!PageUptodate(page))
+ shmem_falloc.nr_falloced++;
+
+ /*
+ * If !PageUptodate, leave it that way so that freeable pages
+ * can be recognized if we need to rollback on error later.
+ * But set_page_dirty so that memory pressure will swap rather
+ * than free the pages we are allocating (and SGP_CACHE pages
+ * might still be clean: we now need to mark those dirty too).
+ */
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ cond_resched();
+ }
+
+ if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
+ i_size_write(inode, offset + len);
+ inode->i_ctime = CURRENT_TIME;
+undone:
+ spin_lock(&inode->i_lock);
+ inode->i_private = NULL;
+ spin_unlock(&inode->i_lock);
+out:
+ mutex_unlock(&inode->i_mutex);
+ return error;
+}
+
+static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
+
+ buf->f_type = TMPFS_MAGIC;
+ buf->f_bsize = PAGE_CACHE_SIZE;
+ buf->f_namelen = NAME_MAX;
+ if (sbinfo->max_blocks) {
+ buf->f_blocks = sbinfo->max_blocks;
+ buf->f_bavail =
+ buf->f_bfree = sbinfo->max_blocks -
+ percpu_counter_sum(&sbinfo->used_blocks);
+ }
+ if (sbinfo->max_inodes) {
+ buf->f_files = sbinfo->max_inodes;
+ buf->f_ffree = sbinfo->free_inodes;
+ }
+ /* else leave those fields 0 like simple_statfs */
+ return 0;
+}
+
+/*
+ * File creation. Allocate an inode, and we're done..
+ */
+static int
+shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
+{
+ struct inode *inode;
+ int error = -ENOSPC;
+
+ inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
+ if (inode) {
+ error = simple_acl_create(dir, inode);
+ if (error)
+ goto out_iput;
+ error = security_inode_init_security(inode, dir,
+ &dentry->d_name,
+ shmem_initxattrs, NULL);
+ if (error && error != -EOPNOTSUPP)
+ goto out_iput;
+
+ error = 0;
+ dir->i_size += BOGO_DIRENT_SIZE;
+ dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ d_instantiate(dentry, inode);
+ dget(dentry); /* Extra count - pin the dentry in core */
+ }
+ return error;
+out_iput:
+ iput(inode);
+ return error;
+}
+
+static int
+shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ struct inode *inode;
+ int error = -ENOSPC;
+
+ inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
+ if (inode) {
+ error = security_inode_init_security(inode, dir,
+ NULL,
+ shmem_initxattrs, NULL);
+ if (error && error != -EOPNOTSUPP)
+ goto out_iput;
+ error = simple_acl_create(dir, inode);
+ if (error)
+ goto out_iput;
+ d_tmpfile(dentry, inode);
+ }
+ return error;
+out_iput:
+ iput(inode);
+ return error;
+}
+
+static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ int error;
+
+ if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
+ return error;
+ inc_nlink(dir);
+ return 0;
+}
+
+static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ bool excl)
+{
+ return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
+}
+
+/*
+ * Link a file..
+ */
+static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = d_inode(old_dentry);
+ int ret;
+
+ /*
+ * No ordinary (disk based) filesystem counts links as inodes;
+ * but each new link needs a new dentry, pinning lowmem, and
+ * tmpfs dentries cannot be pruned until they are unlinked.
+ */
+ ret = shmem_reserve_inode(inode->i_sb);
+ if (ret)
+ goto out;
+
+ dir->i_size += BOGO_DIRENT_SIZE;
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ inc_nlink(inode);
+ ihold(inode); /* New dentry reference */
+ dget(dentry); /* Extra pinning count for the created dentry */
+ d_instantiate(dentry, inode);
+out:
+ return ret;
+}
+
+static int shmem_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = d_inode(dentry);
+
+ if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
+ shmem_free_inode(inode->i_sb);
+
+ dir->i_size -= BOGO_DIRENT_SIZE;
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ drop_nlink(inode);
+ dput(dentry); /* Undo the count from "create" - this does all the work */
+ return 0;
+}
+
+static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ if (!simple_empty(dentry))
+ return -ENOTEMPTY;
+
+ drop_nlink(d_inode(dentry));
+ drop_nlink(dir);
+ return shmem_unlink(dir, dentry);
+}
+
+static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
+{
+ bool old_is_dir = d_is_dir(old_dentry);
+ bool new_is_dir = d_is_dir(new_dentry);
+
+ if (old_dir != new_dir && old_is_dir != new_is_dir) {
+ if (old_is_dir) {
+ drop_nlink(old_dir);
+ inc_nlink(new_dir);
+ } else {
+ drop_nlink(new_dir);
+ inc_nlink(old_dir);
+ }
+ }
+ old_dir->i_ctime = old_dir->i_mtime =
+ new_dir->i_ctime = new_dir->i_mtime =
+ d_inode(old_dentry)->i_ctime =
+ d_inode(new_dentry)->i_ctime = CURRENT_TIME;
+
+ return 0;
+}
+
+static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
+{
+ struct dentry *whiteout;
+ int error;
+
+ whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
+ if (!whiteout)
+ return -ENOMEM;
+
+ error = shmem_mknod(old_dir, whiteout,
+ S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+ dput(whiteout);
+ if (error)
+ return error;
+
+ /*
+ * Cheat and hash the whiteout while the old dentry is still in
+ * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
+ *
+ * d_lookup() will consistently find one of them at this point,
+ * not sure which one, but that isn't even important.
+ */
+ d_rehash(whiteout);
+ return 0;
+}
+
+/*
+ * The VFS layer already does all the dentry stuff for rename,
+ * we just have to decrement the usage count for the target if
+ * it exists so that the VFS layer correctly free's it when it
+ * gets overwritten.
+ */
+static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
+{
+ struct inode *inode = d_inode(old_dentry);
+ int they_are_dirs = S_ISDIR(inode->i_mode);
+
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+ return -EINVAL;
+
+ if (flags & RENAME_EXCHANGE)
+ return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
+
+ if (!simple_empty(new_dentry))
+ return -ENOTEMPTY;
+
+ if (flags & RENAME_WHITEOUT) {
+ int error;
+
+ error = shmem_whiteout(old_dir, old_dentry);
+ if (error)
+ return error;
+ }
+
+ if (d_really_is_positive(new_dentry)) {
+ (void) shmem_unlink(new_dir, new_dentry);
+ if (they_are_dirs) {
+ drop_nlink(d_inode(new_dentry));
+ drop_nlink(old_dir);
+ }
+ } else if (they_are_dirs) {
+ drop_nlink(old_dir);
+ inc_nlink(new_dir);
+ }
+
+ old_dir->i_size -= BOGO_DIRENT_SIZE;
+ new_dir->i_size += BOGO_DIRENT_SIZE;
+ old_dir->i_ctime = old_dir->i_mtime =
+ new_dir->i_ctime = new_dir->i_mtime =
+ inode->i_ctime = CURRENT_TIME;
+ return 0;
+}
+
+static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+ int error;
+ int len;
+ struct inode *inode;
+ struct page *page;
+ char *kaddr;
+ struct shmem_inode_info *info;
+
+ len = strlen(symname) + 1;
+ if (len > PAGE_CACHE_SIZE)
+ return -ENAMETOOLONG;
+
+ inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
+ if (!inode)
+ return -ENOSPC;
+
+ error = security_inode_init_security(inode, dir, &dentry->d_name,
+ shmem_initxattrs, NULL);
+ if (error) {
+ if (error != -EOPNOTSUPP) {
+ iput(inode);
+ return error;
+ }
+ error = 0;
+ }
+
+ info = SHMEM_I(inode);
+ inode->i_size = len-1;
+ if (len <= SHORT_SYMLINK_LEN) {
+ info->symlink = kmemdup(symname, len, GFP_KERNEL);
+ if (!info->symlink) {
+ iput(inode);
+ return -ENOMEM;
+ }
+ inode->i_op = &shmem_short_symlink_operations;
+ } else {
+ error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
+ if (error) {
+ iput(inode);
+ return error;
+ }
+ inode->i_mapping->a_ops = &shmem_aops;
+ inode->i_op = &shmem_symlink_inode_operations;
+ kaddr = kmap_atomic(page);
+ memcpy(kaddr, symname, len);
+ kunmap_atomic(kaddr);
+ SetPageUptodate(page);
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ dir->i_size += BOGO_DIRENT_SIZE;
+ dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ d_instantiate(dentry, inode);
+ dget(dentry);
+ return 0;
+}
+
+static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
+{
+ nd_set_link(nd, SHMEM_I(d_inode(dentry))->symlink);
+ return NULL;
+}
+
+static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct page *page = NULL;
+ int error = shmem_getpage(d_inode(dentry), 0, &page, SGP_READ, NULL);
+ nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
+ if (page)
+ unlock_page(page);
+ return page;
+}
+
+static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+{
+ if (!IS_ERR(nd_get_link(nd))) {
+ struct page *page = cookie;
+ kunmap(page);
+ mark_page_accessed(page);
+ page_cache_release(page);
+ }
+}
+
+#ifdef CONFIG_TMPFS_XATTR
+/*
+ * Superblocks without xattr inode operations may get some security.* xattr
+ * support from the LSM "for free". As soon as we have any other xattrs
+ * like ACLs, we also need to implement the security.* handlers at
+ * filesystem level, though.
+ */
+
+/*
+ * Callback for security_inode_init_security() for acquiring xattrs.
+ */
+static int shmem_initxattrs(struct inode *inode,
+ const struct xattr *xattr_array,
+ void *fs_info)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ const struct xattr *xattr;
+ struct simple_xattr *new_xattr;
+ size_t len;
+
+ for (xattr = xattr_array; xattr->name != NULL; xattr++) {
+ new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
+ if (!new_xattr)
+ return -ENOMEM;
+
+ len = strlen(xattr->name) + 1;
+ new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
+ GFP_KERNEL);
+ if (!new_xattr->name) {
+ kfree(new_xattr);
+ return -ENOMEM;
+ }
+
+ memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
+ XATTR_SECURITY_PREFIX_LEN);
+ memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
+ xattr->name, len);
+
+ simple_xattr_list_add(&info->xattrs, new_xattr);
+ }
+
+ return 0;
+}
+
+static const struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ &posix_acl_access_xattr_handler,
+ &posix_acl_default_xattr_handler,
+#endif
+ NULL
+};
+
+static int shmem_xattr_validate(const char *name)
+{
+ struct { const char *prefix; size_t len; } arr[] = {
+ { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
+ { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
+ };
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(arr); i++) {
+ size_t preflen = arr[i].len;
+ if (strncmp(name, arr[i].prefix, preflen) == 0) {
+ if (!name[preflen])
+ return -EINVAL;
+ return 0;
+ }
+ }
+ return -EOPNOTSUPP;
+}
+
+static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
+ void *buffer, size_t size)
+{
+ struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_getxattr(dentry, name, buffer, size);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ return simple_xattr_get(&info->xattrs, name, buffer, size);
+}
+
+static int shmem_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_setxattr(dentry, name, value, size, flags);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ return simple_xattr_set(&info->xattrs, name, value, size, flags);
+}
+
+static int shmem_removexattr(struct dentry *dentry, const char *name)
+{
+ struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+ int err;
+
+ /*
+ * If this is a request for a synthetic attribute in the system.*
+ * namespace use the generic infrastructure to resolve a handler
+ * for it via sb->s_xattr.
+ */
+ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
+ return generic_removexattr(dentry, name);
+
+ err = shmem_xattr_validate(name);
+ if (err)
+ return err;
+
+ return simple_xattr_remove(&info->xattrs, name);
+}
+
+static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
+{
+ struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
+ return simple_xattr_list(&info->xattrs, buffer, size);
+}
+#endif /* CONFIG_TMPFS_XATTR */
+
+static const struct inode_operations shmem_short_symlink_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_short_symlink,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
+};
+
+static const struct inode_operations shmem_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link,
+ .put_link = shmem_put_link,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
+};
+
+static struct dentry *shmem_get_parent(struct dentry *child)
+{
+ return ERR_PTR(-ESTALE);
+}
+
+static int shmem_match(struct inode *ino, void *vfh)
+{
+ __u32 *fh = vfh;
+ __u64 inum = fh[2];
+ inum = (inum << 32) | fh[1];
+ return ino->i_ino == inum && fh[0] == ino->i_generation;
+}
+
+static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
+ struct fid *fid, int fh_len, int fh_type)
+{
+ struct inode *inode;
+ struct dentry *dentry = NULL;
+ u64 inum;
+
+ if (fh_len < 3)
+ return NULL;
+
+ inum = fid->raw[2];
+ inum = (inum << 32) | fid->raw[1];
+
+ inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
+ shmem_match, fid->raw);
+ if (inode) {
+ dentry = d_find_alias(inode);
+ iput(inode);
+ }
+
+ return dentry;
+}
+
+static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
+ struct inode *parent)
+{
+ if (*len < 3) {
+ *len = 3;
+ return FILEID_INVALID;
+ }
+
+ if (inode_unhashed(inode)) {
+ /* Unfortunately insert_inode_hash is not idempotent,
+ * so as we hash inodes here rather than at creation
+ * time, we need a lock to ensure we only try
+ * to do it once
+ */
+ static DEFINE_SPINLOCK(lock);
+ spin_lock(&lock);
+ if (inode_unhashed(inode))
+ __insert_inode_hash(inode,
+ inode->i_ino + inode->i_generation);
+ spin_unlock(&lock);
+ }
+
+ fh[0] = inode->i_generation;
+ fh[1] = inode->i_ino;
+ fh[2] = ((__u64)inode->i_ino) >> 32;
+
+ *len = 3;
+ return 1;
+}
+
+static const struct export_operations shmem_export_ops = {
+ .get_parent = shmem_get_parent,
+ .encode_fh = shmem_encode_fh,
+ .fh_to_dentry = shmem_fh_to_dentry,
+};
+
+static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
+ bool remount)
+{
+ char *this_char, *value, *rest;
+ struct mempolicy *mpol = NULL;
+ uid_t uid;
+ gid_t gid;
+
+ while (options != NULL) {
+ this_char = options;
+ for (;;) {
+ /*
+ * NUL-terminate this option: unfortunately,
+ * mount options form a comma-separated list,
+ * but mpol's nodelist may also contain commas.
+ */
+ options = strchr(options, ',');
+ if (options == NULL)
+ break;
+ options++;
+ if (!isdigit(*options)) {
+ options[-1] = '\0';
+ break;
+ }
+ }
+ if (!*this_char)
+ continue;
+ if ((value = strchr(this_char,'=')) != NULL) {
+ *value++ = 0;
+ } else {
+ printk(KERN_ERR
+ "tmpfs: No value for mount option '%s'\n",
+ this_char);
+ goto error;
+ }
+
+ if (!strcmp(this_char,"size")) {
+ unsigned long long size;
+ size = memparse(value,&rest);
+ if (*rest == '%') {
+ size <<= PAGE_SHIFT;
+ size *= totalram_pages;
+ do_div(size, 100);
+ rest++;
+ }
+ if (*rest)
+ goto bad_val;
+ sbinfo->max_blocks =
+ DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
+ } else if (!strcmp(this_char,"nr_blocks")) {
+ sbinfo->max_blocks = memparse(value, &rest);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"nr_inodes")) {
+ sbinfo->max_inodes = memparse(value, &rest);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"mode")) {
+ if (remount)
+ continue;
+ sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"uid")) {
+ if (remount)
+ continue;
+ uid = simple_strtoul(value, &rest, 0);
+ if (*rest)
+ goto bad_val;
+ sbinfo->uid = make_kuid(current_user_ns(), uid);
+ if (!uid_valid(sbinfo->uid))
+ goto bad_val;
+ } else if (!strcmp(this_char,"gid")) {
+ if (remount)
+ continue;
+ gid = simple_strtoul(value, &rest, 0);
+ if (*rest)
+ goto bad_val;
+ sbinfo->gid = make_kgid(current_user_ns(), gid);
+ if (!gid_valid(sbinfo->gid))
+ goto bad_val;
+ } else if (!strcmp(this_char,"mpol")) {
+ mpol_put(mpol);
+ mpol = NULL;
+ if (mpol_parse_str(value, &mpol))
+ goto bad_val;
+ } else {
+ printk(KERN_ERR "tmpfs: Bad mount option %s\n",
+ this_char);
+ goto error;
+ }
+ }
+ sbinfo->mpol = mpol;
+ return 0;
+
+bad_val:
+ printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
+ value, this_char);
+error:
+ mpol_put(mpol);
+ return 1;
+
+}
+
+static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+ struct shmem_sb_info config = *sbinfo;
+ unsigned long inodes;
+ int error = -EINVAL;
+
+ config.mpol = NULL;
+ if (shmem_parse_options(data, &config, true))
+ return error;
+
+ spin_lock(&sbinfo->stat_lock);
+ inodes = sbinfo->max_inodes - sbinfo->free_inodes;
+ if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
+ goto out;
+ if (config.max_inodes < inodes)
+ goto out;
+ /*
+ * Those tests disallow limited->unlimited while any are in use;
+ * but we must separately disallow unlimited->limited, because
+ * in that case we have no record of how much is already in use.
+ */
+ if (config.max_blocks && !sbinfo->max_blocks)
+ goto out;
+ if (config.max_inodes && !sbinfo->max_inodes)
+ goto out;
+
+ error = 0;
+ sbinfo->max_blocks = config.max_blocks;
+ sbinfo->max_inodes = config.max_inodes;
+ sbinfo->free_inodes = config.max_inodes - inodes;
+
+ /*
+ * Preserve previous mempolicy unless mpol remount option was specified.
+ */
+ if (config.mpol) {
+ mpol_put(sbinfo->mpol);
+ sbinfo->mpol = config.mpol; /* transfers initial ref */
+ }
+out:
+ spin_unlock(&sbinfo->stat_lock);
+ return error;
+}
+
+static int shmem_show_options(struct seq_file *seq, struct dentry *root)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
+
+ if (sbinfo->max_blocks != shmem_default_max_blocks())
+ seq_printf(seq, ",size=%luk",
+ sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
+ if (sbinfo->max_inodes != shmem_default_max_inodes())
+ seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
+ if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
+ seq_printf(seq, ",mode=%03ho", sbinfo->mode);
+ if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
+ seq_printf(seq, ",uid=%u",
+ from_kuid_munged(&init_user_ns, sbinfo->uid));
+ if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
+ seq_printf(seq, ",gid=%u",
+ from_kgid_munged(&init_user_ns, sbinfo->gid));
+ shmem_show_mpol(seq, sbinfo->mpol);
+ return 0;
+}
+
+#define MFD_NAME_PREFIX "memfd:"
+#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
+#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
+
+#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
+
+SYSCALL_DEFINE2(memfd_create,
+ const char __user *, uname,
+ unsigned int, flags)
+{
+ struct shmem_inode_info *info;
+ struct file *file;
+ int fd, error;
+ char *name;
+ long len;
+
+ if (flags & ~(unsigned int)MFD_ALL_FLAGS)
+ return -EINVAL;
+
+ /* length includes terminating zero */
+ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
+ if (len <= 0)
+ return -EFAULT;
+ if (len > MFD_NAME_MAX_LEN + 1)
+ return -EINVAL;
+
+ name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
+ if (!name)
+ return -ENOMEM;
+
+ strcpy(name, MFD_NAME_PREFIX);
+ if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ /* terminating-zero may have changed after strnlen_user() returned */
+ if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
+ error = -EFAULT;
+ goto err_name;
+ }
+
+ fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
+ if (fd < 0) {
+ error = fd;
+ goto err_name;
+ }
+
+ file = shmem_file_setup(name, 0, VM_NORESERVE);
+ if (IS_ERR(file)) {
+ error = PTR_ERR(file);
+ goto err_fd;
+ }
+ info = SHMEM_I(file_inode(file));
+ file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
+ file->f_flags |= O_RDWR | O_LARGEFILE;
+ if (flags & MFD_ALLOW_SEALING)
+ info->seals &= ~F_SEAL_SEAL;
+
+ fd_install(fd, file);
+ kfree(name);
+ return fd;
+
+err_fd:
+ put_unused_fd(fd);
+err_name:
+ kfree(name);
+ return error;
+}
+
+#endif /* CONFIG_TMPFS */
+
+static void shmem_put_super(struct super_block *sb)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ percpu_counter_destroy(&sbinfo->used_blocks);
+ mpol_put(sbinfo->mpol);
+ kfree(sbinfo);
+ sb->s_fs_info = NULL;
+}
+
+int shmem_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct inode *inode;
+ struct shmem_sb_info *sbinfo;
+ int err = -ENOMEM;
+
+ /* Round up to L1_CACHE_BYTES to resist false sharing */
+ sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
+ L1_CACHE_BYTES), GFP_KERNEL);
+ if (!sbinfo)
+ return -ENOMEM;
+
+ sbinfo->mode = S_IRWXUGO | S_ISVTX;
+ sbinfo->uid = current_fsuid();
+ sbinfo->gid = current_fsgid();
+ sb->s_fs_info = sbinfo;
+
+#ifdef CONFIG_TMPFS
+ /*
+ * Per default we only allow half of the physical ram per
+ * tmpfs instance, limiting inodes to one per page of lowmem;
+ * but the internal instance is left unlimited.
+ */
+ if (!(sb->s_flags & MS_KERNMOUNT)) {
+ sbinfo->max_blocks = shmem_default_max_blocks();
+ sbinfo->max_inodes = shmem_default_max_inodes();
+ if (shmem_parse_options(data, sbinfo, false)) {
+ err = -EINVAL;
+ goto failed;
+ }
+ } else {
+ sb->s_flags |= MS_NOUSER;
+ }
+ sb->s_export_op = &shmem_export_ops;
+ sb->s_flags |= MS_NOSEC;
+#else
+ sb->s_flags |= MS_NOUSER;
+#endif
+
+ spin_lock_init(&sbinfo->stat_lock);
+ if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
+ goto failed;
+ sbinfo->free_inodes = sbinfo->max_inodes;
+
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
+ sb->s_blocksize = PAGE_CACHE_SIZE;
+ sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ sb->s_magic = TMPFS_MAGIC;
+ sb->s_op = &shmem_ops;
+ sb->s_time_gran = 1;
+#ifdef CONFIG_TMPFS_XATTR
+ sb->s_xattr = shmem_xattr_handlers;
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ sb->s_flags |= MS_POSIXACL;
+#endif
+
+ inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
+ if (!inode)
+ goto failed;
+ inode->i_uid = sbinfo->uid;
+ inode->i_gid = sbinfo->gid;
+ sb->s_root = d_make_root(inode);
+ if (!sb->s_root)
+ goto failed;
+ return 0;
+
+failed:
+ shmem_put_super(sb);
+ return err;
+}
+
+static struct kmem_cache *shmem_inode_cachep;
+
+static struct inode *shmem_alloc_inode(struct super_block *sb)
+{
+ struct shmem_inode_info *info;
+ info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
+ if (!info)
+ return NULL;
+ return &info->vfs_inode;
+}
+
+static void shmem_destroy_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+ kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
+}
+
+static void shmem_destroy_inode(struct inode *inode)
+{
+ if (S_ISREG(inode->i_mode))
+ mpol_free_shared_policy(&SHMEM_I(inode)->policy);
+ call_rcu(&inode->i_rcu, shmem_destroy_callback);
+}
+
+static void shmem_init_inode(void *foo)
+{
+ struct shmem_inode_info *info = foo;
+ inode_init_once(&info->vfs_inode);
+}
+
+static int shmem_init_inodecache(void)
+{
+ shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
+ sizeof(struct shmem_inode_info),
+ 0, SLAB_PANIC, shmem_init_inode);
+ return 0;
+}
+
+static void shmem_destroy_inodecache(void)
+{
+ kmem_cache_destroy(shmem_inode_cachep);
+}
+
+static const struct address_space_operations shmem_aops = {
+ .writepage = shmem_writepage,
+ .set_page_dirty = __set_page_dirty_no_writeback,
+#ifdef CONFIG_TMPFS
+ .write_begin = shmem_write_begin,
+ .write_end = shmem_write_end,
+#endif
+#ifdef CONFIG_MIGRATION
+ .migratepage = migrate_page,
+#endif
+ .error_remove_page = generic_error_remove_page,
+};
+
+static const struct file_operations shmem_file_operations = {
+ .mmap = shmem_mmap,
+#ifdef CONFIG_TMPFS
+ .llseek = shmem_file_llseek,
+ .read_iter = shmem_file_read_iter,
+ .write_iter = generic_file_write_iter,
+ .fsync = noop_fsync,
+ .splice_read = shmem_file_splice_read,
+ .splice_write = iter_file_splice_write,
+ .fallocate = shmem_fallocate,
+#endif
+};
+
+static const struct inode_operations shmem_inode_operations = {
+ .setattr = shmem_setattr,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+ .set_acl = simple_set_acl,
+#endif
+};
+
+static const struct inode_operations shmem_dir_inode_operations = {
+#ifdef CONFIG_TMPFS
+ .create = shmem_create,
+ .lookup = simple_lookup,
+ .link = shmem_link,
+ .unlink = shmem_unlink,
+ .symlink = shmem_symlink,
+ .mkdir = shmem_mkdir,
+ .rmdir = shmem_rmdir,
+ .mknod = shmem_mknod,
+ .rename2 = shmem_rename2,
+ .tmpfile = shmem_tmpfile,
+#endif
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ .setattr = shmem_setattr,
+ .set_acl = simple_set_acl,
+#endif
+};
+
+static const struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = shmem_setxattr,
+ .getxattr = shmem_getxattr,
+ .listxattr = shmem_listxattr,
+ .removexattr = shmem_removexattr,
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ .setattr = shmem_setattr,
+ .set_acl = simple_set_acl,
+#endif
+};
+
+static const struct super_operations shmem_ops = {
+ .alloc_inode = shmem_alloc_inode,
+ .destroy_inode = shmem_destroy_inode,
+#ifdef CONFIG_TMPFS
+ .statfs = shmem_statfs,
+ .remount_fs = shmem_remount_fs,
+ .show_options = shmem_show_options,
+#endif
+ .evict_inode = shmem_evict_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = shmem_put_super,
+};
+
+static const struct vm_operations_struct shmem_vm_ops = {
+ .fault = shmem_fault,
+ .map_pages = filemap_map_pages,
+#ifdef CONFIG_NUMA
+ .set_policy = shmem_set_policy,
+ .get_policy = shmem_get_policy,
+#endif
+};
+
+static struct dentry *shmem_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return mount_nodev(fs_type, flags, data, shmem_fill_super);
+}
+
+static struct file_system_type shmem_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "tmpfs",
+ .mount = shmem_mount,
+ .kill_sb = kill_litter_super,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+int __init shmem_init(void)
+{
+ int error;
+
+ /* If rootfs called this, don't re-init */
+ if (shmem_inode_cachep)
+ return 0;
+
+ error = shmem_init_inodecache();
+ if (error)
+ goto out3;
+
+ error = register_filesystem(&shmem_fs_type);
+ if (error) {
+ printk(KERN_ERR "Could not register tmpfs\n");
+ goto out2;
+ }
+
+ shm_mnt = kern_mount(&shmem_fs_type);
+ if (IS_ERR(shm_mnt)) {
+ error = PTR_ERR(shm_mnt);
+ printk(KERN_ERR "Could not kern_mount tmpfs\n");
+ goto out1;
+ }
+ return 0;
+
+out1:
+ unregister_filesystem(&shmem_fs_type);
+out2:
+ shmem_destroy_inodecache();
+out3:
+ shm_mnt = ERR_PTR(error);
+ return error;
+}
+
+#else /* !CONFIG_SHMEM */
+
+/*
+ * tiny-shmem: simple shmemfs and tmpfs using ramfs code
+ *
+ * This is intended for small system where the benefits of the full
+ * shmem code (swap-backed and resource-limited) are outweighed by
+ * their complexity. On systems without swap this code should be
+ * effectively equivalent, but much lighter weight.
+ */
+
+static struct file_system_type shmem_fs_type = {
+ .name = "tmpfs",
+ .mount = ramfs_mount,
+ .kill_sb = kill_litter_super,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+int __init shmem_init(void)
+{
+ BUG_ON(register_filesystem(&shmem_fs_type) != 0);
+
+ shm_mnt = kern_mount(&shmem_fs_type);
+ BUG_ON(IS_ERR(shm_mnt));
+
+ return 0;
+}
+
+int shmem_unuse(swp_entry_t swap, struct page *page)
+{
+ return 0;
+}
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+ return 0;
+}
+
+void shmem_unlock_mapping(struct address_space *mapping)
+{
+}
+
+void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
+{
+ truncate_inode_pages_range(inode->i_mapping, lstart, lend);
+}
+EXPORT_SYMBOL_GPL(shmem_truncate_range);
+
+#define shmem_vm_ops generic_file_vm_ops
+#define shmem_file_operations ramfs_file_operations
+#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
+#define shmem_acct_size(flags, size) 0
+#define shmem_unacct_size(flags, size) do {} while (0)
+
+#endif /* CONFIG_SHMEM */
+
+/* common code */
+
+static struct dentry_operations anon_ops = {
+ .d_dname = simple_dname
+};
+
+static struct file *__shmem_file_setup(const char *name, loff_t size,
+ unsigned long flags, unsigned int i_flags)
+{
+ struct file *res;
+ struct inode *inode;
+ struct path path;
+ struct super_block *sb;
+ struct qstr this;
+
+ if (IS_ERR(shm_mnt))
+ return ERR_CAST(shm_mnt);
+
+ if (size < 0 || size > MAX_LFS_FILESIZE)
+ return ERR_PTR(-EINVAL);
+
+ if (shmem_acct_size(flags, size))
+ return ERR_PTR(-ENOMEM);
+
+ res = ERR_PTR(-ENOMEM);
+ this.name = name;
+ this.len = strlen(name);
+ this.hash = 0; /* will go */
+ sb = shm_mnt->mnt_sb;
+ path.mnt = mntget(shm_mnt);
+ path.dentry = d_alloc_pseudo(sb, &this);
+ if (!path.dentry)
+ goto put_memory;
+ d_set_d_op(path.dentry, &anon_ops);
+
+ res = ERR_PTR(-ENOSPC);
+ inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
+ if (!inode)
+ goto put_memory;
+
+ inode->i_flags |= i_flags;
+ d_instantiate(path.dentry, inode);
+ inode->i_size = size;
+ clear_nlink(inode); /* It is unlinked */
+ res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
+ if (IS_ERR(res))
+ goto put_path;
+
+ res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
+ &shmem_file_operations);
+ if (IS_ERR(res))
+ goto put_path;
+
+ return res;
+
+put_memory:
+ shmem_unacct_size(flags, size);
+put_path:
+ path_put(&path);
+ return res;
+}
+
+/**
+ * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
+ * kernel internal. There will be NO LSM permission checks against the
+ * underlying inode. So users of this interface must do LSM checks at a
+ * higher layer. The one user is the big_key implementation. LSM checks
+ * are provided at the key level rather than the inode level.
+ * @name: name for dentry (to be seen in /proc/<pid>/maps
+ * @size: size to be set for the file
+ * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
+ */
+struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
+{
+ return __shmem_file_setup(name, size, flags, S_PRIVATE);
+}
+
+/**
+ * shmem_file_setup - get an unlinked file living in tmpfs
+ * @name: name for dentry (to be seen in /proc/<pid>/maps
+ * @size: size to be set for the file
+ * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
+ */
+struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
+{
+ return __shmem_file_setup(name, size, flags, 0);
+}
+EXPORT_SYMBOL_GPL(shmem_file_setup);
+
+/**
+ * shmem_zero_setup - setup a shared anonymous mapping
+ * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
+ */
+int shmem_zero_setup(struct vm_area_struct *vma)
+{
+ struct file *file;
+ loff_t size = vma->vm_end - vma->vm_start;
+
+ /*
+ * Cloning a new file under mmap_sem leads to a lock ordering conflict
+ * between XFS directory reading and selinux: since this file is only
+ * accessible to the user through its mapping, use S_PRIVATE flag to
+ * bypass file security, in the same way as shmem_kernel_file_setup().
+ */
+ file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
+ if (IS_ERR(file))
+ return PTR_ERR(file);
+
+ if (vma->vm_file)
+ fput(vma->vm_file);
+ vma->vm_file = file;
+ vma->vm_ops = &shmem_vm_ops;
+ return 0;
+}
+
+/**
+ * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
+ * @mapping: the page's address_space
+ * @index: the page index
+ * @gfp: the page allocator flags to use if allocating
+ *
+ * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
+ * with any new page allocations done using the specified allocation flags.
+ * But read_cache_page_gfp() uses the ->readpage() method: which does not
+ * suit tmpfs, since it may have pages in swapcache, and needs to find those
+ * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
+ *
+ * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
+ * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
+ */
+struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
+ pgoff_t index, gfp_t gfp)
+{
+#ifdef CONFIG_SHMEM
+ struct inode *inode = mapping->host;
+ struct page *page;
+ int error;
+
+ BUG_ON(mapping->a_ops != &shmem_aops);
+ error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
+ if (error)
+ page = ERR_PTR(error);
+ else
+ unlock_page(page);
+ return page;
+#else
+ /*
+ * The tiny !SHMEM case uses ramfs without swap
+ */
+ return read_cache_page_gfp(mapping, index, gfp);
+#endif
+}
+EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
Code Review / kvmfornfv.git / blobdiff