Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/mm/shmem.c b/mm/shmem.c
new file mode 100644
index 0000000..61574b8
--- /dev/null
+++ b/mm/shmem.c
@@ -0,0 +1,2326 @@
+/*
+ * 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) 2002-2004 Hugh Dickins.
+ * Copyright (C) 2002-2004 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>
+ *
+ * This file is released under the GPL.
+ */
+
+/*
+ * 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/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/file.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <linux/shmem_fs.h>
+#include <linux/mount.h>
+#include <linux/writeback.h>
+#include <linux/vfs.h>
+#include <linux/blkdev.h>
+#include <linux/security.h>
+#include <linux/swapops.h>
+#include <linux/mempolicy.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <asm/uaccess.h>
+#include <asm/div64.h>
+#include <asm/pgtable.h>
+
+/* This magic number is used in glibc for posix shared memory */
+#define TMPFS_MAGIC 0x01021994
+
+#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
+#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
+#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
+
+#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
+#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)
+
+#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
+
+/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
+#define SHMEM_PAGEIN VM_READ
+#define SHMEM_TRUNCATE VM_WRITE
+
+/* Definition to limit shmem_truncate's steps between cond_rescheds */
+#define LATENCY_LIMIT 64
+
+/* Pretend that each entry is of this size in directory's i_size */
+#define BOGO_DIRENT_SIZE 20
+
+/* Keep swapped page count in private field of indirect struct page */
+#define nr_swapped private
+
+/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
+enum sgp_type {
+ SGP_QUICK, /* don't try more than file page cache lookup */
+ SGP_READ, /* don't exceed i_size, don't allocate page */
+ SGP_CACHE, /* don't exceed i_size, may allocate page */
+ SGP_WRITE, /* may exceed i_size, may allocate page */
+};
+
+static int shmem_getpage(struct inode *inode, unsigned long idx,
+ struct page **pagep, enum sgp_type sgp, int *type);
+
+static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
+{
+ /*
+ * The above definition of ENTRIES_PER_PAGE, and the use of
+ * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
+ * might be reconsidered if it ever diverges from PAGE_SIZE.
+ */
+ return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
+}
+
+static inline void shmem_dir_free(struct page *page)
+{
+ __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
+}
+
+static struct page **shmem_dir_map(struct page *page)
+{
+ return (struct page **)kmap_atomic(page, KM_USER0);
+}
+
+static inline void shmem_dir_unmap(struct page **dir)
+{
+ kunmap_atomic(dir, KM_USER0);
+}
+
+static swp_entry_t *shmem_swp_map(struct page *page)
+{
+ return (swp_entry_t *)kmap_atomic(page, KM_USER1);
+}
+
+static inline void shmem_swp_balance_unmap(void)
+{
+ /*
+ * When passing a pointer to an i_direct entry, to code which
+ * also handles indirect entries and so will shmem_swp_unmap,
+ * we must arrange for the preempt count to remain in balance.
+ * What kmap_atomic of a lowmem page does depends on config
+ * and architecture, so pretend to kmap_atomic some lowmem page.
+ */
+ (void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
+}
+
+static inline void shmem_swp_unmap(swp_entry_t *entry)
+{
+ kunmap_atomic(entry, KM_USER1);
+}
+
+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_ACCOUNT)?
+ security_vm_enough_memory(VM_ACCT(size)): 0;
+}
+
+static inline void shmem_unacct_size(unsigned long flags, loff_t size)
+{
+ if (flags & VM_ACCOUNT)
+ vm_unacct_memory(VM_ACCT(size));
+}
+
+/*
+ * ... 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_ACCOUNT)?
+ 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
+}
+
+static inline void shmem_unacct_blocks(unsigned long flags, long pages)
+{
+ if (!(flags & VM_ACCOUNT))
+ vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
+}
+
+static struct super_operations shmem_ops;
+static struct address_space_operations shmem_aops;
+static struct file_operations shmem_file_operations;
+static struct inode_operations shmem_inode_operations;
+static struct inode_operations shmem_dir_inode_operations;
+static struct inode_operations shmem_special_inode_operations;
+static struct vm_operations_struct shmem_vm_ops;
+
+static struct backing_dev_info shmem_backing_dev_info = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+ .unplug_io_fn = default_unplug_io_fn,
+};
+
+static LIST_HEAD(shmem_swaplist);
+static DEFINE_SPINLOCK(shmem_swaplist_lock);
+
+static void shmem_free_blocks(struct inode *inode, long pages)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_blocks += pages;
+ inode->i_blocks -= pages*BLOCKS_PER_PAGE;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+}
+
+/*
+ * shmem_recalc_inode - recalculate the size 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) {
+ info->alloced -= freed;
+ shmem_unacct_blocks(info->flags, freed);
+ shmem_free_blocks(inode, freed);
+ }
+}
+
+/*
+ * shmem_swp_entry - find the swap vector position in the info structure
+ *
+ * @info: info structure for the inode
+ * @index: index of the page to find
+ * @page: optional page to add to the structure. Has to be preset to
+ * all zeros
+ *
+ * If there is no space allocated yet it will return NULL when
+ * page is NULL, else it will use the page for the needed block,
+ * setting it to NULL on return to indicate that it has been used.
+ *
+ * The swap vector is organized the following way:
+ *
+ * There are SHMEM_NR_DIRECT entries directly stored in the
+ * shmem_inode_info structure. So small files do not need an addional
+ * allocation.
+ *
+ * For pages with index > SHMEM_NR_DIRECT there is the pointer
+ * i_indirect which points to a page which holds in the first half
+ * doubly indirect blocks, in the second half triple indirect blocks:
+ *
+ * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
+ * following layout (for SHMEM_NR_DIRECT == 16):
+ *
+ * i_indirect -> dir --> 16-19
+ * | +-> 20-23
+ * |
+ * +-->dir2 --> 24-27
+ * | +-> 28-31
+ * | +-> 32-35
+ * | +-> 36-39
+ * |
+ * +-->dir3 --> 40-43
+ * +-> 44-47
+ * +-> 48-51
+ * +-> 52-55
+ */
+static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
+{
+ unsigned long offset;
+ struct page **dir;
+ struct page *subdir;
+
+ if (index < SHMEM_NR_DIRECT) {
+ shmem_swp_balance_unmap();
+ return info->i_direct+index;
+ }
+ if (!info->i_indirect) {
+ if (page) {
+ info->i_indirect = *page;
+ *page = NULL;
+ }
+ return NULL; /* need another page */
+ }
+
+ index -= SHMEM_NR_DIRECT;
+ offset = index % ENTRIES_PER_PAGE;
+ index /= ENTRIES_PER_PAGE;
+ dir = shmem_dir_map(info->i_indirect);
+
+ if (index >= ENTRIES_PER_PAGE/2) {
+ index -= ENTRIES_PER_PAGE/2;
+ dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
+ index %= ENTRIES_PER_PAGE;
+ subdir = *dir;
+ if (!subdir) {
+ if (page) {
+ *dir = *page;
+ *page = NULL;
+ }
+ shmem_dir_unmap(dir);
+ return NULL; /* need another page */
+ }
+ shmem_dir_unmap(dir);
+ dir = shmem_dir_map(subdir);
+ }
+
+ dir += index;
+ subdir = *dir;
+ if (!subdir) {
+ if (!page || !(subdir = *page)) {
+ shmem_dir_unmap(dir);
+ return NULL; /* need a page */
+ }
+ *dir = subdir;
+ *page = NULL;
+ }
+ shmem_dir_unmap(dir);
+ return shmem_swp_map(subdir) + offset;
+}
+
+static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
+{
+ long incdec = value? 1: -1;
+
+ entry->val = value;
+ info->swapped += incdec;
+ if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
+ kmap_atomic_to_page(entry)->nr_swapped += incdec;
+}
+
+/*
+ * shmem_swp_alloc - get the position of the swap entry for the page.
+ * If it does not exist allocate the entry.
+ *
+ * @info: info structure for the inode
+ * @index: index of the page to find
+ * @sgp: check and recheck i_size? skip allocation?
+ */
+static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
+{
+ struct inode *inode = &info->vfs_inode;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ struct page *page = NULL;
+ swp_entry_t *entry;
+
+ if (sgp != SGP_WRITE &&
+ ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ return ERR_PTR(-EINVAL);
+
+ while (!(entry = shmem_swp_entry(info, index, &page))) {
+ if (sgp == SGP_READ)
+ return shmem_swp_map(ZERO_PAGE(0));
+ /*
+ * Test free_blocks against 1 not 0, since we have 1 data
+ * page (and perhaps indirect index pages) yet to allocate:
+ * a waste to allocate index if we cannot allocate data.
+ */
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ if (sbinfo->free_blocks <= 1) {
+ spin_unlock(&sbinfo->stat_lock);
+ return ERR_PTR(-ENOSPC);
+ }
+ sbinfo->free_blocks--;
+ inode->i_blocks += BLOCKS_PER_PAGE;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+
+ spin_unlock(&info->lock);
+ page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
+ if (page) {
+ page->nr_swapped = 0;
+ }
+ spin_lock(&info->lock);
+
+ if (!page) {
+ shmem_free_blocks(inode, 1);
+ return ERR_PTR(-ENOMEM);
+ }
+ if (sgp != SGP_WRITE &&
+ ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
+ entry = ERR_PTR(-EINVAL);
+ break;
+ }
+ if (info->next_index <= index)
+ info->next_index = index + 1;
+ }
+ if (page) {
+ /* another task gave its page, or truncated the file */
+ shmem_free_blocks(inode, 1);
+ shmem_dir_free(page);
+ }
+ if (info->next_index <= index && !IS_ERR(entry))
+ info->next_index = index + 1;
+ return entry;
+}
+
+/*
+ * shmem_free_swp - free some swap entries in a directory
+ *
+ * @dir: pointer to the directory
+ * @edir: pointer after last entry of the directory
+ */
+static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
+{
+ swp_entry_t *ptr;
+ int freed = 0;
+
+ for (ptr = dir; ptr < edir; ptr++) {
+ if (ptr->val) {
+ free_swap_and_cache(*ptr);
+ *ptr = (swp_entry_t){0};
+ freed++;
+ }
+ }
+ return freed;
+}
+
+static int shmem_map_and_free_swp(struct page *subdir,
+ int offset, int limit, struct page ***dir)
+{
+ swp_entry_t *ptr;
+ int freed = 0;
+
+ ptr = shmem_swp_map(subdir);
+ for (; offset < limit; offset += LATENCY_LIMIT) {
+ int size = limit - offset;
+ if (size > LATENCY_LIMIT)
+ size = LATENCY_LIMIT;
+ freed += shmem_free_swp(ptr+offset, ptr+offset+size);
+ if (need_resched()) {
+ shmem_swp_unmap(ptr);
+ if (*dir) {
+ shmem_dir_unmap(*dir);
+ *dir = NULL;
+ }
+ cond_resched();
+ ptr = shmem_swp_map(subdir);
+ }
+ }
+ shmem_swp_unmap(ptr);
+ return freed;
+}
+
+static void shmem_free_pages(struct list_head *next)
+{
+ struct page *page;
+ int freed = 0;
+
+ do {
+ page = container_of(next, struct page, lru);
+ next = next->next;
+ shmem_dir_free(page);
+ freed++;
+ if (freed >= LATENCY_LIMIT) {
+ cond_resched();
+ freed = 0;
+ }
+ } while (next);
+}
+
+static void shmem_truncate(struct inode *inode)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ unsigned long idx;
+ unsigned long size;
+ unsigned long limit;
+ unsigned long stage;
+ unsigned long diroff;
+ struct page **dir;
+ struct page *topdir;
+ struct page *middir;
+ struct page *subdir;
+ swp_entry_t *ptr;
+ LIST_HEAD(pages_to_free);
+ long nr_pages_to_free = 0;
+ long nr_swaps_freed = 0;
+ int offset;
+ int freed;
+
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+ idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ if (idx >= info->next_index)
+ return;
+
+ spin_lock(&info->lock);
+ info->flags |= SHMEM_TRUNCATE;
+ limit = info->next_index;
+ info->next_index = idx;
+ topdir = info->i_indirect;
+ if (topdir && idx <= SHMEM_NR_DIRECT) {
+ info->i_indirect = NULL;
+ nr_pages_to_free++;
+ list_add(&topdir->lru, &pages_to_free);
+ }
+ spin_unlock(&info->lock);
+
+ if (info->swapped && idx < SHMEM_NR_DIRECT) {
+ ptr = info->i_direct;
+ size = limit;
+ if (size > SHMEM_NR_DIRECT)
+ size = SHMEM_NR_DIRECT;
+ nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
+ }
+ if (!topdir)
+ goto done2;
+
+ BUG_ON(limit <= SHMEM_NR_DIRECT);
+ limit -= SHMEM_NR_DIRECT;
+ idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
+ offset = idx % ENTRIES_PER_PAGE;
+ idx -= offset;
+
+ dir = shmem_dir_map(topdir);
+ stage = ENTRIES_PER_PAGEPAGE/2;
+ if (idx < ENTRIES_PER_PAGEPAGE/2) {
+ middir = topdir;
+ diroff = idx/ENTRIES_PER_PAGE;
+ } else {
+ dir += ENTRIES_PER_PAGE/2;
+ dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
+ while (stage <= idx)
+ stage += ENTRIES_PER_PAGEPAGE;
+ middir = *dir;
+ if (*dir) {
+ diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
+ ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
+ if (!diroff && !offset) {
+ *dir = NULL;
+ nr_pages_to_free++;
+ list_add(&middir->lru, &pages_to_free);
+ }
+ shmem_dir_unmap(dir);
+ dir = shmem_dir_map(middir);
+ } else {
+ diroff = 0;
+ offset = 0;
+ idx = stage;
+ }
+ }
+
+ for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
+ if (unlikely(idx == stage)) {
+ shmem_dir_unmap(dir);
+ dir = shmem_dir_map(topdir) +
+ ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
+ while (!*dir) {
+ dir++;
+ idx += ENTRIES_PER_PAGEPAGE;
+ if (idx >= limit)
+ goto done1;
+ }
+ stage = idx + ENTRIES_PER_PAGEPAGE;
+ middir = *dir;
+ *dir = NULL;
+ nr_pages_to_free++;
+ list_add(&middir->lru, &pages_to_free);
+ shmem_dir_unmap(dir);
+ cond_resched();
+ dir = shmem_dir_map(middir);
+ diroff = 0;
+ }
+ subdir = dir[diroff];
+ if (subdir && subdir->nr_swapped) {
+ size = limit - idx;
+ if (size > ENTRIES_PER_PAGE)
+ size = ENTRIES_PER_PAGE;
+ freed = shmem_map_and_free_swp(subdir,
+ offset, size, &dir);
+ if (!dir)
+ dir = shmem_dir_map(middir);
+ nr_swaps_freed += freed;
+ if (offset)
+ spin_lock(&info->lock);
+ subdir->nr_swapped -= freed;
+ if (offset)
+ spin_unlock(&info->lock);
+ BUG_ON(subdir->nr_swapped > offset);
+ }
+ if (offset)
+ offset = 0;
+ else if (subdir) {
+ dir[diroff] = NULL;
+ nr_pages_to_free++;
+ list_add(&subdir->lru, &pages_to_free);
+ }
+ }
+done1:
+ shmem_dir_unmap(dir);
+done2:
+ if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
+ /*
+ * Call truncate_inode_pages again: racing shmem_unuse_inode
+ * may have swizzled a page in from swap since vmtruncate or
+ * generic_delete_inode did it, before we lowered next_index.
+ * Also, though shmem_getpage checks i_size before adding to
+ * cache, no recheck after: so fix the narrow window there too.
+ */
+ truncate_inode_pages(inode->i_mapping, inode->i_size);
+ }
+
+ spin_lock(&info->lock);
+ info->flags &= ~SHMEM_TRUNCATE;
+ info->swapped -= nr_swaps_freed;
+ if (nr_pages_to_free)
+ shmem_free_blocks(inode, nr_pages_to_free);
+ shmem_recalc_inode(inode);
+ spin_unlock(&info->lock);
+
+ /*
+ * Empty swap vector directory pages to be freed?
+ */
+ if (!list_empty(&pages_to_free)) {
+ pages_to_free.prev->next = NULL;
+ shmem_free_pages(pages_to_free.next);
+ }
+}
+
+static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
+{
+ struct inode *inode = dentry->d_inode;
+ struct page *page = NULL;
+ int error;
+
+ if (attr->ia_valid & ATTR_SIZE) {
+ if (attr->ia_size < inode->i_size) {
+ /*
+ * If truncating down to a partial page, then
+ * if that page is already allocated, hold it
+ * in memory until the truncation is over, so
+ * truncate_partial_page cannnot miss it were
+ * it assigned to swap.
+ */
+ if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
+ (void) shmem_getpage(inode,
+ attr->ia_size>>PAGE_CACHE_SHIFT,
+ &page, SGP_READ, NULL);
+ }
+ /*
+ * Reset SHMEM_PAGEIN flag so that shmem_truncate can
+ * detect if any pages might have been added to cache
+ * after truncate_inode_pages. But we needn't bother
+ * if it's being fully truncated to zero-length: the
+ * nrpages check is efficient enough in that case.
+ */
+ if (attr->ia_size) {
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ spin_lock(&info->lock);
+ info->flags &= ~SHMEM_PAGEIN;
+ spin_unlock(&info->lock);
+ }
+ }
+ }
+
+ error = inode_change_ok(inode, attr);
+ if (!error)
+ error = inode_setattr(inode, attr);
+ if (page)
+ page_cache_release(page);
+ return error;
+}
+
+static void shmem_delete_inode(struct inode *inode)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ if (inode->i_op->truncate == shmem_truncate) {
+ shmem_unacct_size(info->flags, inode->i_size);
+ inode->i_size = 0;
+ shmem_truncate(inode);
+ if (!list_empty(&info->swaplist)) {
+ spin_lock(&shmem_swaplist_lock);
+ list_del_init(&info->swaplist);
+ spin_unlock(&shmem_swaplist_lock);
+ }
+ }
+ if (sbinfo) {
+ BUG_ON(inode->i_blocks);
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_inodes++;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ clear_inode(inode);
+}
+
+static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
+{
+ swp_entry_t *ptr;
+
+ for (ptr = dir; ptr < edir; ptr++) {
+ if (ptr->val == entry.val)
+ return ptr - dir;
+ }
+ return -1;
+}
+
+static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
+{
+ struct inode *inode;
+ unsigned long idx;
+ unsigned long size;
+ unsigned long limit;
+ unsigned long stage;
+ struct page **dir;
+ struct page *subdir;
+ swp_entry_t *ptr;
+ int offset;
+
+ idx = 0;
+ ptr = info->i_direct;
+ spin_lock(&info->lock);
+ limit = info->next_index;
+ size = limit;
+ if (size > SHMEM_NR_DIRECT)
+ size = SHMEM_NR_DIRECT;
+ offset = shmem_find_swp(entry, ptr, ptr+size);
+ if (offset >= 0) {
+ shmem_swp_balance_unmap();
+ goto found;
+ }
+ if (!info->i_indirect)
+ goto lost2;
+
+ dir = shmem_dir_map(info->i_indirect);
+ stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;
+
+ for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
+ if (unlikely(idx == stage)) {
+ shmem_dir_unmap(dir-1);
+ dir = shmem_dir_map(info->i_indirect) +
+ ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
+ while (!*dir) {
+ dir++;
+ idx += ENTRIES_PER_PAGEPAGE;
+ if (idx >= limit)
+ goto lost1;
+ }
+ stage = idx + ENTRIES_PER_PAGEPAGE;
+ subdir = *dir;
+ shmem_dir_unmap(dir);
+ dir = shmem_dir_map(subdir);
+ }
+ subdir = *dir;
+ if (subdir && subdir->nr_swapped) {
+ ptr = shmem_swp_map(subdir);
+ size = limit - idx;
+ if (size > ENTRIES_PER_PAGE)
+ size = ENTRIES_PER_PAGE;
+ offset = shmem_find_swp(entry, ptr, ptr+size);
+ if (offset >= 0) {
+ shmem_dir_unmap(dir);
+ goto found;
+ }
+ shmem_swp_unmap(ptr);
+ }
+ }
+lost1:
+ shmem_dir_unmap(dir-1);
+lost2:
+ spin_unlock(&info->lock);
+ return 0;
+found:
+ idx += offset;
+ inode = &info->vfs_inode;
+ if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, ptr + offset, 0);
+ }
+ shmem_swp_unmap(ptr);
+ spin_unlock(&info->lock);
+ /*
+ * Decrement swap count even when the entry is left behind:
+ * try_to_unuse will skip over mms, then reincrement count.
+ */
+ swap_free(entry);
+ return 1;
+}
+
+/*
+ * shmem_unuse() search for an eventually swapped out shmem page.
+ */
+int shmem_unuse(swp_entry_t entry, struct page *page)
+{
+ struct list_head *p, *next;
+ struct shmem_inode_info *info;
+ int found = 0;
+
+ spin_lock(&shmem_swaplist_lock);
+ list_for_each_safe(p, next, &shmem_swaplist) {
+ info = list_entry(p, struct shmem_inode_info, swaplist);
+ if (!info->swapped)
+ list_del_init(&info->swaplist);
+ else if (shmem_unuse_inode(info, entry, page)) {
+ /* move head to start search for next from here */
+ list_move_tail(&shmem_swaplist, &info->swaplist);
+ found = 1;
+ break;
+ }
+ }
+ spin_unlock(&shmem_swaplist_lock);
+ return found;
+}
+
+/*
+ * 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;
+ swp_entry_t *entry, swap;
+ struct address_space *mapping;
+ unsigned long index;
+ struct inode *inode;
+
+ BUG_ON(!PageLocked(page));
+ BUG_ON(page_mapped(page));
+
+ mapping = page->mapping;
+ index = page->index;
+ inode = mapping->host;
+ info = SHMEM_I(inode);
+ if (info->flags & VM_LOCKED)
+ goto redirty;
+ swap = get_swap_page();
+ if (!swap.val)
+ goto redirty;
+
+ spin_lock(&info->lock);
+ shmem_recalc_inode(inode);
+ if (index >= info->next_index) {
+ BUG_ON(!(info->flags & SHMEM_TRUNCATE));
+ goto unlock;
+ }
+ entry = shmem_swp_entry(info, index, NULL);
+ BUG_ON(!entry);
+ BUG_ON(entry->val);
+
+ if (move_to_swap_cache(page, swap) == 0) {
+ shmem_swp_set(info, entry, swap.val);
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ if (list_empty(&info->swaplist)) {
+ spin_lock(&shmem_swaplist_lock);
+ /* move instead of add in case we're racing */
+ list_move_tail(&info->swaplist, &shmem_swaplist);
+ spin_unlock(&shmem_swaplist_lock);
+ }
+ unlock_page(page);
+ return 0;
+ }
+
+ shmem_swp_unmap(entry);
+unlock:
+ spin_unlock(&info->lock);
+ swap_free(swap);
+redirty:
+ set_page_dirty(page);
+ return WRITEPAGE_ACTIVATE; /* Return with the page locked */
+}
+
+#ifdef CONFIG_NUMA
+static struct page *shmem_swapin_async(struct shared_policy *p,
+ swp_entry_t entry, unsigned long idx)
+{
+ struct page *page;
+ struct vm_area_struct pvma;
+
+ /* Create a pseudo vma that just contains the policy */
+ memset(&pvma, 0, sizeof(struct vm_area_struct));
+ pvma.vm_end = PAGE_SIZE;
+ pvma.vm_pgoff = idx;
+ pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
+ page = read_swap_cache_async(entry, &pvma, 0);
+ mpol_free(pvma.vm_policy);
+ return page;
+}
+
+struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
+ unsigned long idx)
+{
+ struct shared_policy *p = &info->policy;
+ int i, num;
+ struct page *page;
+ unsigned long offset;
+
+ num = valid_swaphandles(entry, &offset);
+ for (i = 0; i < num; offset++, i++) {
+ page = shmem_swapin_async(p,
+ swp_entry(swp_type(entry), offset), idx);
+ if (!page)
+ break;
+ page_cache_release(page);
+ }
+ lru_add_drain(); /* Push any new pages onto the LRU now */
+ return shmem_swapin_async(p, entry, idx);
+}
+
+static struct page *
+shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
+ unsigned long idx)
+{
+ struct vm_area_struct pvma;
+ struct page *page;
+
+ memset(&pvma, 0, sizeof(struct vm_area_struct));
+ pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
+ pvma.vm_pgoff = idx;
+ pvma.vm_end = PAGE_SIZE;
+ page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
+ mpol_free(pvma.vm_policy);
+ return page;
+}
+#else
+static inline struct page *
+shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
+{
+ swapin_readahead(entry, 0, NULL);
+ return read_swap_cache_async(entry, NULL, 0);
+}
+
+static inline struct page *
+shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info,
+ unsigned long idx)
+{
+ return alloc_page(gfp | __GFP_ZERO);
+}
+#endif
+
+/*
+ * shmem_getpage - either get the page from swap or allocate a new one
+ *
+ * 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(struct inode *inode, unsigned long idx,
+ struct page **pagep, enum sgp_type sgp, int *type)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ struct shmem_sb_info *sbinfo;
+ struct page *filepage = *pagep;
+ struct page *swappage;
+ swp_entry_t *entry;
+ swp_entry_t swap;
+ int error;
+
+ if (idx >= SHMEM_MAX_INDEX)
+ return -EFBIG;
+ /*
+ * Normally, filepage is NULL on entry, and either found
+ * uptodate immediately, or allocated and zeroed, or read
+ * in under swappage, which is then assigned to filepage.
+ * But shmem_prepare_write passes in a locked filepage,
+ * which may be found not uptodate by other callers too,
+ * and may need to be copied from the swappage read in.
+ */
+repeat:
+ if (!filepage)
+ filepage = find_lock_page(mapping, idx);
+ if (filepage && PageUptodate(filepage))
+ goto done;
+ error = 0;
+ if (sgp == SGP_QUICK)
+ goto failed;
+
+ spin_lock(&info->lock);
+ shmem_recalc_inode(inode);
+ entry = shmem_swp_alloc(info, idx, sgp);
+ if (IS_ERR(entry)) {
+ spin_unlock(&info->lock);
+ error = PTR_ERR(entry);
+ goto failed;
+ }
+ swap = *entry;
+
+ if (swap.val) {
+ /* Look it up and read it in.. */
+ swappage = lookup_swap_cache(swap);
+ if (!swappage) {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ /* here we actually do the io */
+ if (type && *type == VM_FAULT_MINOR) {
+ inc_page_state(pgmajfault);
+ *type = VM_FAULT_MAJOR;
+ }
+ swappage = shmem_swapin(info, swap, idx);
+ if (!swappage) {
+ spin_lock(&info->lock);
+ entry = shmem_swp_alloc(info, idx, sgp);
+ if (IS_ERR(entry))
+ error = PTR_ERR(entry);
+ else {
+ if (entry->val == swap.val)
+ error = -ENOMEM;
+ shmem_swp_unmap(entry);
+ }
+ spin_unlock(&info->lock);
+ if (error)
+ goto failed;
+ goto repeat;
+ }
+ wait_on_page_locked(swappage);
+ page_cache_release(swappage);
+ goto repeat;
+ }
+
+ /* We have to do this with page locked to prevent races */
+ if (TestSetPageLocked(swappage)) {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ wait_on_page_locked(swappage);
+ page_cache_release(swappage);
+ goto repeat;
+ }
+ if (PageWriteback(swappage)) {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ wait_on_page_writeback(swappage);
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ goto repeat;
+ }
+ if (!PageUptodate(swappage)) {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ error = -EIO;
+ goto failed;
+ }
+
+ if (filepage) {
+ shmem_swp_set(info, entry, 0);
+ shmem_swp_unmap(entry);
+ delete_from_swap_cache(swappage);
+ spin_unlock(&info->lock);
+ copy_highpage(filepage, swappage);
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ flush_dcache_page(filepage);
+ SetPageUptodate(filepage);
+ set_page_dirty(filepage);
+ swap_free(swap);
+ } else if (!(error = move_from_swap_cache(
+ swappage, idx, mapping))) {
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, entry, 0);
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ filepage = swappage;
+ swap_free(swap);
+ } else {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ if (error == -ENOMEM) {
+ /* let kswapd refresh zone for GFP_ATOMICs */
+ blk_congestion_wait(WRITE, HZ/50);
+ }
+ goto repeat;
+ }
+ } else if (sgp == SGP_READ && !filepage) {
+ shmem_swp_unmap(entry);
+ filepage = find_get_page(mapping, idx);
+ if (filepage &&
+ (!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
+ spin_unlock(&info->lock);
+ wait_on_page_locked(filepage);
+ page_cache_release(filepage);
+ filepage = NULL;
+ goto repeat;
+ }
+ spin_unlock(&info->lock);
+ } else {
+ shmem_swp_unmap(entry);
+ sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ if (sbinfo->free_blocks == 0 ||
+ shmem_acct_block(info->flags)) {
+ spin_unlock(&sbinfo->stat_lock);
+ spin_unlock(&info->lock);
+ error = -ENOSPC;
+ goto failed;
+ }
+ sbinfo->free_blocks--;
+ inode->i_blocks += BLOCKS_PER_PAGE;
+ spin_unlock(&sbinfo->stat_lock);
+ } else if (shmem_acct_block(info->flags)) {
+ spin_unlock(&info->lock);
+ error = -ENOSPC;
+ goto failed;
+ }
+
+ if (!filepage) {
+ spin_unlock(&info->lock);
+ filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
+ info,
+ idx);
+ if (!filepage) {
+ shmem_unacct_blocks(info->flags, 1);
+ shmem_free_blocks(inode, 1);
+ error = -ENOMEM;
+ goto failed;
+ }
+
+ spin_lock(&info->lock);
+ entry = shmem_swp_alloc(info, idx, sgp);
+ if (IS_ERR(entry))
+ error = PTR_ERR(entry);
+ else {
+ swap = *entry;
+ shmem_swp_unmap(entry);
+ }
+ if (error || swap.val || 0 != add_to_page_cache_lru(
+ filepage, mapping, idx, GFP_ATOMIC)) {
+ spin_unlock(&info->lock);
+ page_cache_release(filepage);
+ shmem_unacct_blocks(info->flags, 1);
+ shmem_free_blocks(inode, 1);
+ filepage = NULL;
+ if (error)
+ goto failed;
+ goto repeat;
+ }
+ info->flags |= SHMEM_PAGEIN;
+ }
+
+ info->alloced++;
+ spin_unlock(&info->lock);
+ flush_dcache_page(filepage);
+ SetPageUptodate(filepage);
+ }
+done:
+ if (*pagep != filepage) {
+ unlock_page(filepage);
+ *pagep = filepage;
+ }
+ return 0;
+
+failed:
+ if (*pagep != filepage) {
+ unlock_page(filepage);
+ page_cache_release(filepage);
+ }
+ return error;
+}
+
+struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
+{
+ struct inode *inode = vma->vm_file->f_dentry->d_inode;
+ struct page *page = NULL;
+ unsigned long idx;
+ int error;
+
+ idx = (address - vma->vm_start) >> PAGE_SHIFT;
+ idx += vma->vm_pgoff;
+ idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
+ if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ return NOPAGE_SIGBUS;
+
+ error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
+ if (error)
+ return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
+
+ mark_page_accessed(page);
+ return page;
+}
+
+static int shmem_populate(struct vm_area_struct *vma,
+ unsigned long addr, unsigned long len,
+ pgprot_t prot, unsigned long pgoff, int nonblock)
+{
+ struct inode *inode = vma->vm_file->f_dentry->d_inode;
+ struct mm_struct *mm = vma->vm_mm;
+ enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
+ unsigned long size;
+
+ size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
+ return -EINVAL;
+
+ while ((long) len > 0) {
+ struct page *page = NULL;
+ int err;
+ /*
+ * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
+ */
+ err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
+ if (err)
+ return err;
+ if (page) {
+ mark_page_accessed(page);
+ err = install_page(mm, vma, addr, page, prot);
+ if (err) {
+ page_cache_release(page);
+ return err;
+ }
+ } else if (nonblock) {
+ err = install_file_pte(mm, vma, addr, pgoff, prot);
+ if (err)
+ return err;
+ }
+
+ len -= PAGE_SIZE;
+ addr += PAGE_SIZE;
+ pgoff++;
+ }
+ return 0;
+}
+
+#ifdef CONFIG_NUMA
+int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
+{
+ struct inode *i = vma->vm_file->f_dentry->d_inode;
+ return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
+}
+
+struct mempolicy *
+shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
+{
+ struct inode *i = vma->vm_file->f_dentry->d_inode;
+ unsigned long idx;
+
+ idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
+}
+#endif
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ 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;
+ }
+ if (!lock && (info->flags & VM_LOCKED) && user) {
+ user_shm_unlock(inode->i_size, user);
+ info->flags &= ~VM_LOCKED;
+ }
+ 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, int mode, dev_t dev)
+{
+ struct inode *inode;
+ struct shmem_inode_info *info;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ if (!sbinfo->free_inodes) {
+ spin_unlock(&sbinfo->stat_lock);
+ return NULL;
+ }
+ sbinfo->free_inodes--;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+
+ inode = new_inode(sb);
+ if (inode) {
+ inode->i_mode = mode;
+ inode->i_uid = current->fsuid;
+ inode->i_gid = current->fsgid;
+ inode->i_blksize = PAGE_CACHE_SIZE;
+ inode->i_blocks = 0;
+ inode->i_mapping->a_ops = &shmem_aops;
+ inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
+ inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+ info = SHMEM_I(inode);
+ memset(info, 0, (char *)inode - (char *)info);
+ spin_lock_init(&info->lock);
+ INIT_LIST_HEAD(&info->swaplist);
+
+ switch (mode & S_IFMT) {
+ default:
+ inode->i_op = &shmem_special_inode_operations;
+ init_special_inode(inode, mode, dev);
+ break;
+ case S_IFREG:
+ inode->i_op = &shmem_inode_operations;
+ inode->i_fop = &shmem_file_operations;
+ mpol_shared_policy_init(&info->policy);
+ break;
+ case S_IFDIR:
+ inode->i_nlink++;
+ /* 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);
+ break;
+ }
+ } else if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_inodes++;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ return inode;
+}
+
+#ifdef CONFIG_TMPFS
+
+static int shmem_set_size(struct shmem_sb_info *sbinfo,
+ unsigned long max_blocks, unsigned long max_inodes)
+{
+ int error;
+ unsigned long blocks, inodes;
+
+ spin_lock(&sbinfo->stat_lock);
+ blocks = sbinfo->max_blocks - sbinfo->free_blocks;
+ inodes = sbinfo->max_inodes - sbinfo->free_inodes;
+ error = -EINVAL;
+ if (max_blocks < blocks)
+ goto out;
+ if (max_inodes < inodes)
+ goto out;
+ error = 0;
+ sbinfo->max_blocks = max_blocks;
+ sbinfo->free_blocks = max_blocks - blocks;
+ sbinfo->max_inodes = max_inodes;
+ sbinfo->free_inodes = max_inodes - inodes;
+out:
+ spin_unlock(&sbinfo->stat_lock);
+ return error;
+}
+
+static struct inode_operations shmem_symlink_inode_operations;
+static struct inode_operations shmem_symlink_inline_operations;
+
+/*
+ * Normally tmpfs makes no use of shmem_prepare_write, but it
+ * lets a tmpfs file be used read-write below the loop driver.
+ */
+static int
+shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
+{
+ struct inode *inode = page->mapping->host;
+ return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
+}
+
+static ssize_t
+shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+ struct inode *inode = file->f_dentry->d_inode;
+ loff_t pos;
+ unsigned long written;
+ ssize_t err;
+
+ if ((ssize_t) count < 0)
+ return -EINVAL;
+
+ if (!access_ok(VERIFY_READ, buf, count))
+ return -EFAULT;
+
+ down(&inode->i_sem);
+
+ pos = *ppos;
+ written = 0;
+
+ err = generic_write_checks(file, &pos, &count, 0);
+ if (err || !count)
+ goto out;
+
+ err = remove_suid(file->f_dentry);
+ if (err)
+ goto out;
+
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+
+ do {
+ struct page *page = NULL;
+ unsigned long bytes, index, offset;
+ char *kaddr;
+ int left;
+
+ offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
+ index = pos >> PAGE_CACHE_SHIFT;
+ bytes = PAGE_CACHE_SIZE - offset;
+ if (bytes > count)
+ bytes = count;
+
+ /*
+ * We don't hold page lock across copy from user -
+ * what would it guard against? - so no deadlock here.
+ * But it still may be a good idea to prefault below.
+ */
+
+ err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
+ if (err)
+ break;
+
+ left = bytes;
+ if (PageHighMem(page)) {
+ volatile unsigned char dummy;
+ __get_user(dummy, buf);
+ __get_user(dummy, buf + bytes - 1);
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ left = __copy_from_user_inatomic(kaddr + offset,
+ buf, bytes);
+ kunmap_atomic(kaddr, KM_USER0);
+ }
+ if (left) {
+ kaddr = kmap(page);
+ left = __copy_from_user(kaddr + offset, buf, bytes);
+ kunmap(page);
+ }
+
+ written += bytes;
+ count -= bytes;
+ pos += bytes;
+ buf += bytes;
+ if (pos > inode->i_size)
+ i_size_write(inode, pos);
+
+ flush_dcache_page(page);
+ set_page_dirty(page);
+ mark_page_accessed(page);
+ page_cache_release(page);
+
+ if (left) {
+ pos -= left;
+ written -= left;
+ err = -EFAULT;
+ break;
+ }
+
+ /*
+ * Our dirty pages are not counted in nr_dirty,
+ * and we do not attempt to balance dirty pages.
+ */
+
+ cond_resched();
+ } while (count);
+
+ *ppos = pos;
+ if (written)
+ err = written;
+out:
+ up(&inode->i_sem);
+ return err;
+}
+
+static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
+{
+ struct inode *inode = filp->f_dentry->d_inode;
+ struct address_space *mapping = inode->i_mapping;
+ unsigned long index, offset;
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ offset = *ppos & ~PAGE_CACHE_MASK;
+
+ for (;;) {
+ struct page *page = NULL;
+ unsigned long end_index, 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;
+ }
+
+ desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
+ if (desc->error) {
+ if (desc->error == -EINVAL)
+ desc->error = 0;
+ break;
+ }
+
+ /*
+ * We must evaluate after, since reads (unlike writes)
+ * are called without i_sem 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);
+
+ /*
+ * Ok, we have the page, and it's up-to-date, so
+ * now we can copy it to user space...
+ *
+ * The actor routine returns how many bytes were actually used..
+ * NOTE! This may not be the same as how much of a user buffer
+ * we filled up (we may be padding etc), so we can only update
+ * "pos" here (the actor routine has to update the user buffer
+ * pointers and the remaining count).
+ */
+ ret = actor(desc, page, offset, nr);
+ offset += ret;
+ index += offset >> PAGE_CACHE_SHIFT;
+ offset &= ~PAGE_CACHE_MASK;
+
+ page_cache_release(page);
+ if (ret != nr || !desc->count)
+ break;
+
+ cond_resched();
+ }
+
+ *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
+ file_accessed(filp);
+}
+
+static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
+{
+ read_descriptor_t desc;
+
+ if ((ssize_t) count < 0)
+ return -EINVAL;
+ if (!access_ok(VERIFY_WRITE, buf, count))
+ return -EFAULT;
+ if (!count)
+ return 0;
+
+ desc.written = 0;
+ desc.count = count;
+ desc.arg.buf = buf;
+ desc.error = 0;
+
+ do_shmem_file_read(filp, ppos, &desc, file_read_actor);
+ if (desc.written)
+ return desc.written;
+ return desc.error;
+}
+
+static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
+ size_t count, read_actor_t actor, void *target)
+{
+ read_descriptor_t desc;
+
+ if (!count)
+ return 0;
+
+ desc.written = 0;
+ desc.count = count;
+ desc.arg.data = target;
+ desc.error = 0;
+
+ do_shmem_file_read(in_file, ppos, &desc, actor);
+ if (desc.written)
+ return desc.written;
+ return desc.error;
+}
+
+static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+
+ buf->f_type = TMPFS_MAGIC;
+ buf->f_bsize = PAGE_CACHE_SIZE;
+ buf->f_namelen = NAME_MAX;
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ buf->f_blocks = sbinfo->max_blocks;
+ buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
+ buf->f_files = sbinfo->max_inodes;
+ buf->f_ffree = sbinfo->free_inodes;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ /* 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, int mode, dev_t dev)
+{
+ struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
+ int error = -ENOSPC;
+
+ if (inode) {
+ if (dir->i_mode & S_ISGID) {
+ inode->i_gid = dir->i_gid;
+ if (S_ISDIR(mode))
+ inode->i_mode |= S_ISGID;
+ }
+ 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 */
+ error = 0;
+ }
+ return error;
+}
+
+static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int error;
+
+ if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
+ return error;
+ dir->i_nlink++;
+ return 0;
+}
+
+static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
+ struct nameidata *nd)
+{
+ 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 = old_dentry->d_inode;
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+
+ /*
+ * 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.
+ */
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ if (!sbinfo->free_inodes) {
+ spin_unlock(&sbinfo->stat_lock);
+ return -ENOSPC;
+ }
+ sbinfo->free_inodes--;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+
+ dir->i_size += BOGO_DIRENT_SIZE;
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ inode->i_nlink++;
+ atomic_inc(&inode->i_count); /* New dentry reference */
+ dget(dentry); /* Extra pinning count for the created dentry */
+ d_instantiate(dentry, inode);
+ return 0;
+}
+
+static int shmem_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = dentry->d_inode;
+
+ if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo) {
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_inodes++;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+ }
+
+ dir->i_size -= BOGO_DIRENT_SIZE;
+ inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ inode->i_nlink--;
+ 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;
+
+ dir->i_nlink--;
+ return shmem_unlink(dir, dentry);
+}
+
+/*
+ * 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_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *inode = old_dentry->d_inode;
+ int they_are_dirs = S_ISDIR(inode->i_mode);
+
+ if (!simple_empty(new_dentry))
+ return -ENOTEMPTY;
+
+ if (new_dentry->d_inode) {
+ (void) shmem_unlink(new_dir, new_dentry);
+ if (they_are_dirs)
+ old_dir->i_nlink--;
+ } else if (they_are_dirs) {
+ old_dir->i_nlink--;
+ new_dir->i_nlink++;
+ }
+
+ 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 = NULL;
+ 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, S_IFLNK|S_IRWXUGO, 0);
+ if (!inode)
+ return -ENOSPC;
+
+ info = SHMEM_I(inode);
+ inode->i_size = len-1;
+ if (len <= (char *)inode - (char *)info) {
+ /* do it inline */
+ memcpy(info, symname, len);
+ inode->i_op = &shmem_symlink_inline_operations;
+ } else {
+ error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
+ if (error) {
+ iput(inode);
+ return error;
+ }
+ inode->i_op = &shmem_symlink_inode_operations;
+ kaddr = kmap_atomic(page, KM_USER0);
+ memcpy(kaddr, symname, len);
+ kunmap_atomic(kaddr, KM_USER0);
+ set_page_dirty(page);
+ page_cache_release(page);
+ }
+ if (dir->i_mode & S_ISGID)
+ inode->i_gid = dir->i_gid;
+ dir->i_size += BOGO_DIRENT_SIZE;
+ dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+ d_instantiate(dentry, inode);
+ dget(dentry);
+ return 0;
+}
+
+static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
+{
+ nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
+ return 0;
+}
+
+static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct page *page = NULL;
+ int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
+ nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
+ return 0;
+}
+
+static void shmem_put_link(struct dentry *dentry, struct nameidata *nd)
+{
+ if (!IS_ERR(nd_get_link(nd))) {
+ struct page *page;
+
+ page = find_get_page(dentry->d_inode->i_mapping, 0);
+ if (!page)
+ BUG();
+ kunmap(page);
+ mark_page_accessed(page);
+ page_cache_release(page);
+ page_cache_release(page);
+ }
+}
+
+static struct inode_operations shmem_symlink_inline_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link_inline,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+#endif
+};
+
+static struct inode_operations shmem_symlink_inode_operations = {
+ .truncate = shmem_truncate,
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link,
+ .put_link = shmem_put_link,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+#endif
+};
+
+static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
+{
+ char *this_char, *value, *rest;
+
+ while ((this_char = strsep(&options, ",")) != NULL) {
+ 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);
+ return 1;
+ }
+
+ 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;
+ *blocks = size >> PAGE_CACHE_SHIFT;
+ } else if (!strcmp(this_char,"nr_blocks")) {
+ *blocks = memparse(value,&rest);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"nr_inodes")) {
+ *inodes = memparse(value,&rest);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"mode")) {
+ if (!mode)
+ continue;
+ *mode = simple_strtoul(value,&rest,8);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"uid")) {
+ if (!uid)
+ continue;
+ *uid = simple_strtoul(value,&rest,0);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"gid")) {
+ if (!gid)
+ continue;
+ *gid = simple_strtoul(value,&rest,0);
+ if (*rest)
+ goto bad_val;
+ } else {
+ printk(KERN_ERR "tmpfs: Bad mount option %s\n",
+ this_char);
+ return 1;
+ }
+ }
+ return 0;
+
+bad_val:
+ printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
+ value, this_char);
+ return 1;
+
+}
+
+static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
+ unsigned long max_blocks = 0;
+ unsigned long max_inodes = 0;
+
+ if (sbinfo) {
+ max_blocks = sbinfo->max_blocks;
+ max_inodes = sbinfo->max_inodes;
+ }
+ if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes))
+ return -EINVAL;
+ /* Keep it simple: disallow limited <-> unlimited remount */
+ if ((max_blocks || max_inodes) == !sbinfo)
+ return -EINVAL;
+ /* But allow the pointless unlimited -> unlimited remount */
+ if (!sbinfo)
+ return 0;
+ return shmem_set_size(sbinfo, max_blocks, max_inodes);
+}
+#endif
+
+static void shmem_put_super(struct super_block *sb)
+{
+ kfree(sb->s_fs_info);
+ sb->s_fs_info = NULL;
+}
+
+#ifdef CONFIG_TMPFS_XATTR
+static struct xattr_handler *shmem_xattr_handlers[];
+#else
+#define shmem_xattr_handlers NULL
+#endif
+
+static int shmem_fill_super(struct super_block *sb,
+ void *data, int silent)
+{
+ struct inode *inode;
+ struct dentry *root;
+ int mode = S_IRWXUGO | S_ISVTX;
+ uid_t uid = current->fsuid;
+ gid_t gid = current->fsgid;
+ int err = -ENOMEM;
+
+#ifdef CONFIG_TMPFS
+ unsigned long blocks = 0;
+ unsigned long inodes = 0;
+
+ /*
+ * 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_NOUSER)) {
+ blocks = totalram_pages / 2;
+ inodes = totalram_pages - totalhigh_pages;
+ if (inodes > blocks)
+ inodes = blocks;
+
+ if (shmem_parse_options(data, &mode,
+ &uid, &gid, &blocks, &inodes))
+ return -EINVAL;
+ }
+
+ if (blocks || inodes) {
+ struct shmem_sb_info *sbinfo;
+ sbinfo = kmalloc(sizeof(struct shmem_sb_info), GFP_KERNEL);
+ if (!sbinfo)
+ return -ENOMEM;
+ sb->s_fs_info = sbinfo;
+ spin_lock_init(&sbinfo->stat_lock);
+ sbinfo->max_blocks = blocks;
+ sbinfo->free_blocks = blocks;
+ sbinfo->max_inodes = inodes;
+ sbinfo->free_inodes = inodes;
+ }
+ sb->s_xattr = shmem_xattr_handlers;
+#else
+ sb->s_flags |= MS_NOUSER;
+#endif
+
+ sb->s_maxbytes = SHMEM_MAX_BYTES;
+ sb->s_blocksize = PAGE_CACHE_SIZE;
+ sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+ sb->s_magic = TMPFS_MAGIC;
+ sb->s_op = &shmem_ops;
+ inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
+ if (!inode)
+ goto failed;
+ inode->i_uid = uid;
+ inode->i_gid = gid;
+ root = d_alloc_root(inode);
+ if (!root)
+ goto failed_iput;
+ sb->s_root = root;
+ return 0;
+
+failed_iput:
+ iput(inode);
+failed:
+ shmem_put_super(sb);
+ return err;
+}
+
+static kmem_cache_t *shmem_inode_cachep;
+
+static struct inode *shmem_alloc_inode(struct super_block *sb)
+{
+ struct shmem_inode_info *p;
+ p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
+ if (!p)
+ return NULL;
+ return &p->vfs_inode;
+}
+
+static void shmem_destroy_inode(struct inode *inode)
+{
+ if ((inode->i_mode & S_IFMT) == S_IFREG) {
+ /* only struct inode is valid if it's an inline symlink */
+ mpol_free_shared_policy(&SHMEM_I(inode)->policy);
+ }
+ kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
+}
+
+static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
+{
+ struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
+
+ if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
+ SLAB_CTOR_CONSTRUCTOR) {
+ inode_init_once(&p->vfs_inode);
+ }
+}
+
+static int init_inodecache(void)
+{
+ shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
+ sizeof(struct shmem_inode_info),
+ 0, 0, init_once, NULL);
+ if (shmem_inode_cachep == NULL)
+ return -ENOMEM;
+ return 0;
+}
+
+static void destroy_inodecache(void)
+{
+ if (kmem_cache_destroy(shmem_inode_cachep))
+ printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
+}
+
+static struct address_space_operations shmem_aops = {
+ .writepage = shmem_writepage,
+ .set_page_dirty = __set_page_dirty_nobuffers,
+#ifdef CONFIG_TMPFS
+ .prepare_write = shmem_prepare_write,
+ .commit_write = simple_commit_write,
+#endif
+};
+
+static struct file_operations shmem_file_operations = {
+ .mmap = shmem_mmap,
+#ifdef CONFIG_TMPFS
+ .llseek = generic_file_llseek,
+ .read = shmem_file_read,
+ .write = shmem_file_write,
+ .fsync = simple_sync_file,
+ .sendfile = shmem_file_sendfile,
+#endif
+};
+
+static struct inode_operations shmem_inode_operations = {
+ .truncate = shmem_truncate,
+ .setattr = shmem_notify_change,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+#endif
+};
+
+static 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,
+ .rename = shmem_rename,
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+#endif
+#endif
+};
+
+static struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_XATTR
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+#endif
+};
+
+static 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,
+#endif
+ .delete_inode = shmem_delete_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = shmem_put_super,
+};
+
+static struct vm_operations_struct shmem_vm_ops = {
+ .nopage = shmem_nopage,
+ .populate = shmem_populate,
+#ifdef CONFIG_NUMA
+ .set_policy = shmem_set_policy,
+ .get_policy = shmem_get_policy,
+#endif
+};
+
+
+#ifdef CONFIG_TMPFS_SECURITY
+
+static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len,
+ const char *name, size_t name_len)
+{
+ return security_inode_listsecurity(inode, list, list_len);
+}
+
+static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return security_inode_getsecurity(inode, name, buffer, size);
+}
+
+static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return security_inode_setsecurity(inode, name, value, size, flags);
+}
+
+static struct xattr_handler shmem_xattr_security_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .list = shmem_xattr_security_list,
+ .get = shmem_xattr_security_get,
+ .set = shmem_xattr_security_set,
+};
+
+#endif /* CONFIG_TMPFS_SECURITY */
+
+#ifdef CONFIG_TMPFS_XATTR
+
+static struct xattr_handler *shmem_xattr_handlers[] = {
+#ifdef CONFIG_TMPFS_SECURITY
+ &shmem_xattr_security_handler,
+#endif
+ NULL
+};
+
+#endif /* CONFIG_TMPFS_XATTR */
+
+static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
+}
+
+static struct file_system_type tmpfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "tmpfs",
+ .get_sb = shmem_get_sb,
+ .kill_sb = kill_litter_super,
+};
+static struct vfsmount *shm_mnt;
+
+static int __init init_tmpfs(void)
+{
+ int error;
+
+ error = init_inodecache();
+ if (error)
+ goto out3;
+
+ error = register_filesystem(&tmpfs_fs_type);
+ if (error) {
+ printk(KERN_ERR "Could not register tmpfs\n");
+ goto out2;
+ }
+#ifdef CONFIG_TMPFS
+ devfs_mk_dir("shm");
+#endif
+ shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
+ tmpfs_fs_type.name, NULL);
+ 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(&tmpfs_fs_type);
+out2:
+ destroy_inodecache();
+out3:
+ shm_mnt = ERR_PTR(error);
+ return error;
+}
+module_init(init_tmpfs)
+
+/*
+ * 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
+ *
+ */
+struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
+{
+ int error;
+ struct file *file;
+ struct inode *inode;
+ struct dentry *dentry, *root;
+ struct qstr this;
+
+ if (IS_ERR(shm_mnt))
+ return (void *)shm_mnt;
+
+ if (size < 0 || size > SHMEM_MAX_BYTES)
+ return ERR_PTR(-EINVAL);
+
+ if (shmem_acct_size(flags, size))
+ return ERR_PTR(-ENOMEM);
+
+ error = -ENOMEM;
+ this.name = name;
+ this.len = strlen(name);
+ this.hash = 0; /* will go */
+ root = shm_mnt->mnt_root;
+ dentry = d_alloc(root, &this);
+ if (!dentry)
+ goto put_memory;
+
+ error = -ENFILE;
+ file = get_empty_filp();
+ if (!file)
+ goto put_dentry;
+
+ error = -ENOSPC;
+ inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
+ if (!inode)
+ goto close_file;
+
+ SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
+ d_instantiate(dentry, inode);
+ inode->i_size = size;
+ inode->i_nlink = 0; /* It is unlinked */
+ file->f_vfsmnt = mntget(shm_mnt);
+ file->f_dentry = dentry;
+ file->f_mapping = inode->i_mapping;
+ file->f_op = &shmem_file_operations;
+ file->f_mode = FMODE_WRITE | FMODE_READ;
+ return file;
+
+close_file:
+ put_filp(file);
+put_dentry:
+ dput(dentry);
+put_memory:
+ shmem_unacct_size(flags, size);
+ return ERR_PTR(error);
+}
+
+/*
+ * 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;
+
+ file = shmem_file_setup("dev/zero", size, vma->vm_flags);
+ 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;
+}