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-rw-r--r--mm/shmem.c2705
1 files changed, 2705 insertions, 0 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
new file mode 100644
index 00000000000..eef4ebea515
--- /dev/null
+++ b/mm/shmem.c
@@ -0,0 +1,2705 @@
+/*
+ * 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) 2002-2005 Hugh Dickins.
+ * 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/pagemap.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/swap.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/generic_acl.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/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 <asm/uaccess.h>
+#include <asm/div64.h>
+#include <asm/pgtable.h>
+
+/*
+ * The maximum size of a shmem/tmpfs file is limited by the maximum size of
+ * its triple-indirect swap vector - see illustration at shmem_swp_entry().
+ *
+ * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
+ * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum
+ * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
+ * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
+ *
+ * We use / and * instead of shifts in the definitions below, so that the swap
+ * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
+ */
+#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
+#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
+
+#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
+#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
+
+#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
+#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))
+
+#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
+#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
+
+/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
+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 page */
+};
+
+#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 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(gfp_t 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.
+ *
+ * Mobility flags are masked out as swap vectors cannot move
+ */
+ return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
+ 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_NORESERVE) ?
+ 0 : security_vm_enough_memory_kern(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));
+}
+
+/*
+ * ... 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_kern(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 struct backing_dev_info shmem_backing_dev_info __read_mostly = {
+ .ra_pages = 0, /* No readahead */
+ .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
+ .unplug_io_fn = default_unplug_io_fn,
+};
+
+static LIST_HEAD(shmem_swaplist);
+static DEFINE_MUTEX(shmem_swaplist_mutex);
+
+static void shmem_free_blocks(struct inode *inode, long pages)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
+ if (sbinfo->max_blocks) {
+ spin_lock(&sbinfo->stat_lock);
+ sbinfo->free_blocks += pages;
+ inode->i_blocks -= pages*BLOCKS_PER_PAGE;
+ spin_unlock(&sbinfo->stat_lock);
+ }
+}
+
+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 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) {
+ struct page *page = kmap_atomic_to_page(entry);
+ set_page_private(page, page_private(page) + incdec);
+ }
+}
+
+/**
+ * shmem_swp_alloc - get the position of the swap entry for the page.
+ * @info: info structure for the inode
+ * @index: index of the page to find
+ * @sgp: check and recheck i_size? skip allocation?
+ *
+ * If the entry does not exist, allocate it.
+ */
+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->max_blocks) {
+ 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));
+ if (page)
+ set_page_private(page, 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
+ * @punch_lock: pointer to spinlock when needed for the holepunch case
+ */
+static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
+ spinlock_t *punch_lock)
+{
+ spinlock_t *punch_unlock = NULL;
+ swp_entry_t *ptr;
+ int freed = 0;
+
+ for (ptr = dir; ptr < edir; ptr++) {
+ if (ptr->val) {
+ if (unlikely(punch_lock)) {
+ punch_unlock = punch_lock;
+ punch_lock = NULL;
+ spin_lock(punch_unlock);
+ if (!ptr->val)
+ continue;
+ }
+ free_swap_and_cache(*ptr);
+ *ptr = (swp_entry_t){0};
+ freed++;
+ }
+ }
+ if (punch_unlock)
+ spin_unlock(punch_unlock);
+ return freed;
+}
+
+static int shmem_map_and_free_swp(struct page *subdir, int offset,
+ int limit, struct page ***dir, spinlock_t *punch_lock)
+{
+ 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,
+ punch_lock);
+ 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_range(struct inode *inode, loff_t start, loff_t end)
+{
+ 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;
+ int punch_hole;
+ spinlock_t *needs_lock;
+ spinlock_t *punch_lock;
+ unsigned long upper_limit;
+
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+ idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ if (idx >= info->next_index)
+ return;
+
+ spin_lock(&info->lock);
+ info->flags |= SHMEM_TRUNCATE;
+ if (likely(end == (loff_t) -1)) {
+ limit = info->next_index;
+ upper_limit = SHMEM_MAX_INDEX;
+ info->next_index = idx;
+ needs_lock = NULL;
+ punch_hole = 0;
+ } else {
+ if (end + 1 >= inode->i_size) { /* we may free a little more */
+ limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
+ PAGE_CACHE_SHIFT;
+ upper_limit = SHMEM_MAX_INDEX;
+ } else {
+ limit = (end + 1) >> PAGE_CACHE_SHIFT;
+ upper_limit = limit;
+ }
+ needs_lock = &info->lock;
+ punch_hole = 1;
+ }
+
+ topdir = info->i_indirect;
+ if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
+ 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, needs_lock);
+ }
+
+ /*
+ * If there are no indirect blocks or we are punching a hole
+ * below indirect blocks, nothing to be done.
+ */
+ if (!topdir || limit <= SHMEM_NR_DIRECT)
+ goto done2;
+
+ /*
+ * The truncation case has already dropped info->lock, and we're safe
+ * because i_size and next_index have already been lowered, preventing
+ * access beyond. But in the punch_hole case, we still need to take
+ * the lock when updating the swap directory, because there might be
+ * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
+ * shmem_writepage. However, whenever we find we can remove a whole
+ * directory page (not at the misaligned start or end of the range),
+ * we first NULLify its pointer in the level above, and then have no
+ * need to take the lock when updating its contents: needs_lock and
+ * punch_lock (either pointing to info->lock or NULL) manage this.
+ */
+
+ upper_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 && upper_limit >= stage) {
+ if (needs_lock) {
+ spin_lock(needs_lock);
+ *dir = NULL;
+ spin_unlock(needs_lock);
+ needs_lock = NULL;
+ } else
+ *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;
+ if (punch_hole)
+ needs_lock = &info->lock;
+ if (upper_limit >= stage) {
+ if (needs_lock) {
+ spin_lock(needs_lock);
+ *dir = NULL;
+ spin_unlock(needs_lock);
+ needs_lock = NULL;
+ } else
+ *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;
+ }
+ punch_lock = needs_lock;
+ subdir = dir[diroff];
+ if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
+ if (needs_lock) {
+ spin_lock(needs_lock);
+ dir[diroff] = NULL;
+ spin_unlock(needs_lock);
+ punch_lock = NULL;
+ } else
+ dir[diroff] = NULL;
+ nr_pages_to_free++;
+ list_add(&subdir->lru, &pages_to_free);
+ }
+ if (subdir && page_private(subdir) /* has swap entries */) {
+ size = limit - idx;
+ if (size > ENTRIES_PER_PAGE)
+ size = ENTRIES_PER_PAGE;
+ freed = shmem_map_and_free_swp(subdir,
+ offset, size, &dir, punch_lock);
+ if (!dir)
+ dir = shmem_dir_map(middir);
+ nr_swaps_freed += freed;
+ if (offset || punch_lock) {
+ spin_lock(&info->lock);
+ set_page_private(subdir,
+ page_private(subdir) - freed);
+ spin_unlock(&info->lock);
+ } else
+ BUG_ON(page_private(subdir) != freed);
+ }
+ offset = 0;
+ }
+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.
+ *
+ * Recalling truncate_inode_pages_range and unmap_mapping_range
+ * every time for punch_hole (which never got a chance to clear
+ * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
+ * yet hardly ever necessary: try to optimize them out later.
+ */
+ truncate_inode_pages_range(inode->i_mapping, start, end);
+ if (punch_hole)
+ unmap_mapping_range(inode->i_mapping, start,
+ end - start, 1);
+ }
+
+ 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 void shmem_truncate(struct inode *inode)
+{
+ shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
+}
+
+static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
+{
+ struct inode *inode = dentry->d_inode;
+ struct page *page = NULL;
+ int error;
+
+ if (S_ISREG(inode->i_mode) && (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);
+ if (page)
+ unlock_page(page);
+ }
+ /*
+ * 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);
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ if (!error && (attr->ia_valid & ATTR_MODE))
+ error = generic_acl_chmod(inode);
+#endif
+ if (page)
+ page_cache_release(page);
+ return error;
+}
+
+static void shmem_delete_inode(struct inode *inode)
+{
+ struct shmem_inode_info *info = SHMEM_I(inode);
+
+ if (inode->i_op->truncate == shmem_truncate) {
+ truncate_inode_pages(inode->i_mapping, 0);
+ shmem_unacct_size(info->flags, inode->i_size);
+ inode->i_size = 0;
+ shmem_truncate(inode);
+ if (!list_empty(&info->swaplist)) {
+ mutex_lock(&shmem_swaplist_mutex);
+ list_del_init(&info->swaplist);
+ mutex_unlock(&shmem_swaplist_mutex);
+ }
+ }
+ BUG_ON(inode->i_blocks);
+ shmem_free_inode(inode->i_sb);
+ 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;
+ int error;
+
+ idx = 0;
+ ptr = info->i_direct;
+ spin_lock(&info->lock);
+ if (!info->swapped) {
+ list_del_init(&info->swaplist);
+ goto lost2;
+ }
+ 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)
+ 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);
+ if (cond_resched_lock(&info->lock)) {
+ /* check it has not been truncated */
+ if (limit > info->next_index) {
+ limit = info->next_index;
+ if (idx >= limit)
+ goto lost2;
+ }
+ }
+ 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 && page_private(subdir)) {
+ 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);
+ shmem_swp_unmap(ptr);
+ if (offset >= 0) {
+ shmem_dir_unmap(dir);
+ goto found;
+ }
+ }
+ }
+lost1:
+ shmem_dir_unmap(dir-1);
+lost2:
+ spin_unlock(&info->lock);
+ return 0;
+found:
+ idx += offset;
+ inode = igrab(&info->vfs_inode);
+ spin_unlock(&info->lock);
+
+ /*
+ * Move _head_ to start search for next from here.
+ * But be careful: shmem_delete_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. We
+ * could avoid doing it if inode NULL; or use this minor optimization.
+ */
+ if (shmem_swaplist.next != &info->swaplist)
+ list_move_tail(&shmem_swaplist, &info->swaplist);
+ mutex_unlock(&shmem_swaplist_mutex);
+
+ error = 1;
+ if (!inode)
+ goto out;
+ /*
+ * Charge page using GFP_KERNEL while we can wait.
+ * Charged back to the user(not to caller) when swap account is used.
+ * add_to_page_cache() will be called with GFP_NOWAIT.
+ */
+ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
+ if (error)
+ goto out;
+ error = radix_tree_preload(GFP_KERNEL);
+ if (error) {
+ mem_cgroup_uncharge_cache_page(page);
+ goto out;
+ }
+ error = 1;
+
+ spin_lock(&info->lock);
+ ptr = shmem_swp_entry(info, idx, NULL);
+ if (ptr && ptr->val == entry.val) {
+ error = add_to_page_cache_locked(page, inode->i_mapping,
+ idx, GFP_NOWAIT);
+ /* does mem_cgroup_uncharge_cache_page on error */
+ } else /* we must compensate for our precharge above */
+ mem_cgroup_uncharge_cache_page(page);
+
+ if (error == -EEXIST) {
+ struct page *filepage = find_get_page(inode->i_mapping, idx);
+ error = 1;
+ if (filepage) {
+ /*
+ * There might be a more uptodate page coming down
+ * from a stacked writepage: forget our swappage if so.
+ */
+ if (PageUptodate(filepage))
+ error = 0;
+ page_cache_release(filepage);
+ }
+ }
+ if (!error) {
+ delete_from_swap_cache(page);
+ set_page_dirty(page);
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, ptr, 0);
+ swap_free(entry);
+ error = 1; /* not an error, but entry was found */
+ }
+ if (ptr)
+ shmem_swp_unmap(ptr);
+ spin_unlock(&info->lock);
+ radix_tree_preload_end();
+out:
+ unlock_page(page);
+ page_cache_release(page);
+ iput(inode); /* allows for NULL */
+ return error;
+}
+
+/*
+ * 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;
+
+ mutex_lock(&shmem_swaplist_mutex);
+ list_for_each_safe(p, next, &shmem_swaplist) {
+ info = list_entry(p, struct shmem_inode_info, swaplist);
+ found = shmem_unuse_inode(info, entry, page);
+ cond_resched();
+ if (found)
+ goto out;
+ }
+ mutex_unlock(&shmem_swaplist_mutex);
+ /*
+ * Can some race bring us here? We've been holding page lock,
+ * so I think not; but would rather try again later than BUG()
+ */
+ unlock_page(page);
+ page_cache_release(page);
+out:
+ return (found < 0) ? found : 0;
+}
+
+/*
+ * 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));
+ 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;
+
+ /*
+ * shmem_backing_dev_info's capabilities prevent regular writeback or
+ * sync from ever calling shmem_writepage; but a stacking filesystem
+ * may use the ->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. However, in those cases,
+ * we do still want to check if there's a redundant swappage to be
+ * discarded.
+ */
+ if (wbc->for_reclaim)
+ swap = get_swap_page();
+ else
+ swap.val = 0;
+
+ spin_lock(&info->lock);
+ if (index >= info->next_index) {
+ BUG_ON(!(info->flags & SHMEM_TRUNCATE));
+ goto unlock;
+ }
+ entry = shmem_swp_entry(info, index, NULL);
+ if (entry->val) {
+ /*
+ * The more uptodate page coming down from a stacked
+ * writepage should replace our old swappage.
+ */
+ free_swap_and_cache(*entry);
+ shmem_swp_set(info, entry, 0);
+ }
+ shmem_recalc_inode(inode);
+
+ if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
+ remove_from_page_cache(page);
+ shmem_swp_set(info, entry, swap.val);
+ shmem_swp_unmap(entry);
+ if (list_empty(&info->swaplist))
+ inode = igrab(inode);
+ else
+ inode = NULL;
+ spin_unlock(&info->lock);
+ swap_shmem_alloc(swap);
+ BUG_ON(page_mapped(page));
+ page_cache_release(page); /* pagecache ref */
+ swap_writepage(page, wbc);
+ if (inode) {
+ mutex_lock(&shmem_swaplist_mutex);
+ /* move instead of add in case we're racing */
+ list_move_tail(&info->swaplist, &shmem_swaplist);
+ mutex_unlock(&shmem_swaplist_mutex);
+ iput(inode);
+ }
+ return 0;
+ }
+
+ shmem_swp_unmap(entry);
+unlock:
+ spin_unlock(&info->lock);
+ /*
+ * add_to_swap_cache() doesn't return -EEXIST, so we can safely
+ * clear SWAP_HAS_CACHE flag.
+ */
+ swapcache_free(swap, NULL);
+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, 1);
+
+ 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 entry, gfp_t gfp,
+ struct shmem_inode_info *info, unsigned long idx)
+{
+ struct mempolicy mpol, *spol;
+ struct vm_area_struct pvma;
+ struct page *page;
+
+ spol = mpol_cond_copy(&mpol,
+ mpol_shared_policy_lookup(&info->policy, idx));
+
+ /* Create a pseudo vma that just contains the policy */
+ pvma.vm_start = 0;
+ pvma.vm_pgoff = idx;
+ pvma.vm_ops = NULL;
+ pvma.vm_policy = spol;
+ page = swapin_readahead(entry, gfp, &pvma, 0);
+ return page;
+}
+
+static struct page *shmem_alloc_page(gfp_t gfp,
+ struct shmem_inode_info *info, unsigned long idx)
+{
+ struct vm_area_struct pvma;
+
+ /* Create a pseudo vma that just contains the policy */
+ pvma.vm_start = 0;
+ pvma.vm_pgoff = idx;
+ pvma.vm_ops = NULL;
+ pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
+
+ /*
+ * alloc_page_vma() will drop the shared policy reference
+ */
+ return alloc_page_vma(gfp, &pvma, 0);
+}
+#else /* !CONFIG_NUMA */
+#ifdef CONFIG_TMPFS
+static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
+{
+}
+#endif /* CONFIG_TMPFS */
+
+static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
+ struct shmem_inode_info *info, unsigned long idx)
+{
+ return swapin_readahead(entry, gfp, NULL, 0);
+}
+
+static inline struct page *shmem_alloc_page(gfp_t gfp,
+ struct shmem_inode_info *info, unsigned long idx)
+{
+ 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
+
+/*
+ * 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;
+ gfp_t gfp;
+ int error;
+
+ if (idx >= SHMEM_MAX_INDEX)
+ return -EFBIG;
+
+ if (type)
+ *type = 0;
+
+ /*
+ * 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_readpage (required for splice) 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;
+ gfp = mapping_gfp_mask(mapping);
+ if (!filepage) {
+ /*
+ * Try to preload while we can wait, to not make a habit of
+ * draining atomic reserves; but don't latch on to this cpu.
+ */
+ error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
+ if (error)
+ goto failed;
+ radix_tree_preload_end();
+ }
+
+ 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);
+ /* here we actually do the io */
+ if (type && !(*type & VM_FAULT_MAJOR)) {
+ __count_vm_event(PGMAJFAULT);
+ *type |= VM_FAULT_MAJOR;
+ }
+ spin_unlock(&info->lock);
+ swappage = shmem_swapin(swap, gfp, info, 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 (!trylock_page(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 = add_to_page_cache_locked(swappage, mapping,
+ idx, GFP_NOWAIT))) {
+ info->flags |= SHMEM_PAGEIN;
+ shmem_swp_set(info, entry, 0);
+ shmem_swp_unmap(entry);
+ delete_from_swap_cache(swappage);
+ spin_unlock(&info->lock);
+ filepage = swappage;
+ set_page_dirty(filepage);
+ swap_free(swap);
+ } else {
+ shmem_swp_unmap(entry);
+ spin_unlock(&info->lock);
+ if (error == -ENOMEM) {
+ /*
+ * reclaim from proper memory cgroup and
+ * call memcg's OOM if needed.
+ */
+ error = mem_cgroup_shmem_charge_fallback(
+ swappage,
+ current->mm,
+ gfp);
+ if (error) {
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ goto failed;
+ }
+ }
+ unlock_page(swappage);
+ page_cache_release(swappage);
+ goto repeat;
+ }
+ } else if (sgp == SGP_READ && !filepage) {
+ shmem_swp_unmap(entry);
+ filepage = find_get_page(mapping, idx);
+ if (filepage &&
+ (!PageUptodate(filepage) || !trylock_page(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->max_blocks) {
+ 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) {
+ int ret;
+
+ spin_unlock(&info->lock);
+ filepage = shmem_alloc_page(gfp, info, idx);
+ if (!filepage) {
+ shmem_unacct_blocks(info->flags, 1);
+ shmem_free_blocks(inode, 1);
+ error = -ENOMEM;
+ goto failed;
+ }
+ SetPageSwapBacked(filepage);
+
+ /* Precharge page while we can wait, compensate after */
+ error = mem_cgroup_cache_charge(filepage, current->mm,
+ GFP_KERNEL);
+ if (error) {
+ page_cache_release(filepage);
+ shmem_unacct_blocks(info->flags, 1);
+ shmem_free_blocks(inode, 1);
+ filepage = NULL;
+ 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);
+ }
+ ret = error || swap.val;
+ if (ret)
+ mem_cgroup_uncharge_cache_page(filepage);
+ else
+ ret = add_to_page_cache_lru(filepage, mapping,
+ idx, GFP_NOWAIT);
+ /*
+ * At add_to_page_cache_lru() failure, uncharge will
+ * be done automatically.
+ */
+ if (ret) {
+ 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);
+ clear_highpage(filepage);
+ flush_dcache_page(filepage);
+ SetPageUptodate(filepage);
+ if (sgp == SGP_DIRTY)
+ set_page_dirty(filepage);
+ }
+done:
+ *pagep = filepage;
+ return 0;
+
+failed:
+ if (*pagep != filepage) {
+ unlock_page(filepage);
+ page_cache_release(filepage);
+ }
+ return error;
+}
+
+static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
+ int error;
+ int ret;
+
+ if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
+ return VM_FAULT_SIGBUS;
+
+ error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
+ if (error)
+ return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
+
+ return ret | VM_FAULT_LOCKED;
+}
+
+#ifdef CONFIG_NUMA
+static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
+{
+ struct inode *i = vma->vm_file->f_path.dentry->d_inode;
+ return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
+}
+
+static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
+ unsigned long addr)
+{
+ struct inode *i = vma->vm_file->f_path.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_path.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;
+ 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);
+ scan_mapping_unevictable_pages(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;
+ vma->vm_flags |= VM_CAN_NONLINEAR;
+ return 0;
+}
+
+static struct inode *shmem_get_inode(struct super_block *sb, int 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_mode = mode;
+ inode->i_uid = current_fsuid();
+ inode->i_gid = current_fsgid();
+ inode->i_blocks = 0;
+ inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
+ 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->flags = flags & VM_NORESERVE;
+ INIT_LIST_HEAD(&info->swaplist);
+ 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;
+}
+
+#ifdef CONFIG_TMPFS
+static const struct inode_operations shmem_symlink_inode_operations;
+static const struct inode_operations shmem_symlink_inline_operations;
+
+/*
+ * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
+ * but providing them allows a tmpfs file to be used for splice, sendfile, and
+ * below the loop driver, in the generic fashion that many filesystems support.
+ */
+static int shmem_readpage(struct file *file, struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
+ unlock_page(page);
+ return error;
+}
+
+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;
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+ *pagep = NULL;
+ 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);
+
+ set_page_dirty(page);
+ unlock_page(page);
+ page_cache_release(page);
+
+ return copied;
+}
+
+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_path.dentry->d_inode;
+ struct address_space *mapping = inode->i_mapping;
+ unsigned long index, offset;
+ enum sgp_type sgp = SGP_READ;
+
+ /*
+ * 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 (segment_eq(get_fs(), KERNEL_DS))
+ sgp = SGP_DIRTY;
+
+ 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, NULL);
+ if (desc->error) {
+ if (desc->error == -EINVAL)
+ desc->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...
+ *
+ * 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_aio_read(struct kiocb *iocb,
+ const struct iovec *iov, unsigned long nr_segs, loff_t pos)
+{
+ struct file *filp = iocb->ki_filp;
+ ssize_t retval;
+ unsigned long seg;
+ size_t count;
+ loff_t *ppos = &iocb->ki_pos;
+
+ retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
+ if (retval)
+ return retval;
+
+ for (seg = 0; seg < nr_segs; seg++) {
+ read_descriptor_t desc;
+
+ desc.written = 0;
+ desc.arg.buf = iov[seg].iov_base;
+ desc.count = iov[seg].iov_len;
+ if (desc.count == 0)
+ continue;
+ desc.error = 0;
+ do_shmem_file_read(filp, ppos, &desc, file_read_actor);
+ retval += desc.written;
+ if (desc.error) {
+ retval = retval ?: desc.error;
+ break;
+ }
+ if (desc.count > 0)
+ break;
+ }
+ return retval;
+}
+
+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;
+ spin_lock(&sbinfo->stat_lock);
+ if (sbinfo->max_blocks) {
+ buf->f_blocks = sbinfo->max_blocks;
+ buf->f_bavail = buf->f_bfree = sbinfo->free_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 */
+ spin_unlock(&sbinfo->stat_lock);
+ 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;
+ int error = -ENOSPC;
+
+ inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE);
+ if (inode) {
+ error = security_inode_init_security(inode, dir, NULL, NULL,
+ NULL);
+ if (error) {
+ if (error != -EOPNOTSUPP) {
+ iput(inode);
+ return error;
+ }
+ }
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ error = generic_acl_init(inode, dir);
+ if (error) {
+ iput(inode);
+ return error;
+ }
+#else
+ error = 0;
+#endif
+ 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 */
+ }
+ 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;
+ inc_nlink(dir);
+ 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;
+ 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);
+ atomic_inc(&inode->i_count); /* 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 = dentry->d_inode;
+
+ 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(dentry->d_inode);
+ drop_nlink(dir);
+ 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)
+ 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 = 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, VM_NORESERVE);
+ if (!inode)
+ return -ENOSPC;
+
+ error = security_inode_init_security(inode, dir, NULL, NULL,
+ NULL);
+ if (error) {
+ if (error != -EOPNOTSUPP) {
+ iput(inode);
+ return error;
+ }
+ error = 0;
+ }
+
+ 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_mapping->a_ops = &shmem_aops;
+ 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);
+ unlock_page(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 void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
+{
+ nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
+ return NULL;
+}
+
+static void *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));
+ 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);
+ }
+}
+
+static const struct inode_operations shmem_symlink_inline_operations = {
+ .readlink = generic_readlink,
+ .follow_link = shmem_follow_link_inline,
+};
+
+static const 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_POSIX_ACL
+/*
+ * Superblocks without xattr inode operations will get security.* xattr
+ * support from the VFS "for free". As soon as we have any other xattrs
+ * like ACLs, we also need to implement the security.* handlers at
+ * filesystem level, though.
+ */
+
+static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
+ size_t list_len, const char *name,
+ size_t name_len, int handler_flags)
+{
+ return security_inode_listsecurity(dentry->d_inode, list, list_len);
+}
+
+static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
+ void *buffer, size_t size, int handler_flags)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return xattr_getsecurity(dentry->d_inode, name, buffer, size);
+}
+
+static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags, int handler_flags)
+{
+ if (strcmp(name, "") == 0)
+ return -EINVAL;
+ return security_inode_setsecurity(dentry->d_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,
+};
+
+static struct xattr_handler *shmem_xattr_handlers[] = {
+ &generic_acl_access_handler,
+ &generic_acl_default_handler,
+ &shmem_xattr_security_handler,
+ NULL
+};
+#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 = fid->raw[2];
+ inum = (inum << 32) | fid->raw[1];
+
+ if (fh_len < 3)
+ return NULL;
+
+ 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 dentry *dentry, __u32 *fh, int *len,
+ int connectable)
+{
+ struct inode *inode = dentry->d_inode;
+
+ if (*len < 3)
+ return 255;
+
+ if (hlist_unhashed(&inode->i_hash)) {
+ /* 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 (hlist_unhashed(&inode->i_hash))
+ __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;
+
+ 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);
+ 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;
+ 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;
+ sbinfo->uid = simple_strtoul(value, &rest, 0);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"gid")) {
+ if (remount)
+ continue;
+ sbinfo->gid = simple_strtoul(value, &rest, 0);
+ if (*rest)
+ goto bad_val;
+ } else if (!strcmp(this_char,"mpol")) {
+ if (mpol_parse_str(value, &sbinfo->mpol, 1))
+ 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);
+ struct shmem_sb_info config = *sbinfo;
+ unsigned long blocks;
+ unsigned long inodes;
+ int error = -EINVAL;
+
+ if (shmem_parse_options(data, &config, true))
+ return error;
+
+ spin_lock(&sbinfo->stat_lock);
+ blocks = sbinfo->max_blocks - sbinfo->free_blocks;
+ inodes = sbinfo->max_inodes - sbinfo->free_inodes;
+ if (config.max_blocks < blocks)
+ goto out;
+ if (config.max_inodes < inodes)
+ goto out;
+ /*
+ * Those tests also disallow limited->unlimited while any are in
+ * use, so i_blocks will always be zero when max_blocks is zero;
+ * 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->free_blocks = config.max_blocks - blocks;
+ sbinfo->max_inodes = config.max_inodes;
+ sbinfo->free_inodes = config.max_inodes - inodes;
+
+ 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 vfsmount *vfs)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_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=%03o", sbinfo->mode);
+ if (sbinfo->uid != 0)
+ seq_printf(seq, ",uid=%u", sbinfo->uid);
+ if (sbinfo->gid != 0)
+ seq_printf(seq, ",gid=%u", sbinfo->gid);
+ shmem_show_mpol(seq, sbinfo->mpol);
+ return 0;
+}
+#endif /* CONFIG_TMPFS */
+
+static void shmem_put_super(struct super_block *sb)
+{
+ kfree(sb->s_fs_info);
+ sb->s_fs_info = NULL;
+}
+
+int shmem_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct inode *inode;
+ struct dentry *root;
+ 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_NOUSER)) {
+ 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;
+ }
+ }
+ sb->s_export_op = &shmem_export_ops;
+#else
+ sb->s_flags |= MS_NOUSER;
+#endif
+
+ spin_lock_init(&sbinfo->stat_lock);
+ sbinfo->free_blocks = sbinfo->max_blocks;
+ sbinfo->free_inodes = sbinfo->max_inodes;
+
+ 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;
+ sb->s_time_gran = 1;
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ sb->s_xattr = shmem_xattr_handlers;
+ sb->s_flags |= MS_POSIXACL;
+#endif
+
+ inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
+ if (!inode)
+ goto failed;
+ inode->i_uid = sbinfo->uid;
+ inode->i_gid = sbinfo->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 struct kmem_cache *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, GFP_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)
+{
+ struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
+
+ 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, SLAB_PANIC, init_once);
+ return 0;
+}
+
+static void 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
+ .readpage = shmem_readpage,
+ .write_begin = shmem_write_begin,
+ .write_end = shmem_write_end,
+#endif
+ .migratepage = migrate_page,
+ .error_remove_page = generic_error_remove_page,
+};
+
+static const struct file_operations shmem_file_operations = {
+ .mmap = shmem_mmap,
+#ifdef CONFIG_TMPFS
+ .llseek = generic_file_llseek,
+ .read = do_sync_read,
+ .write = do_sync_write,
+ .aio_read = shmem_file_aio_read,
+ .aio_write = generic_file_aio_write,
+ .fsync = simple_sync_file,
+ .splice_read = generic_file_splice_read,
+ .splice_write = generic_file_splice_write,
+#endif
+};
+
+static const struct inode_operations shmem_inode_operations = {
+ .truncate = shmem_truncate,
+ .setattr = shmem_notify_change,
+ .truncate_range = shmem_truncate_range,
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+ .check_acl = generic_check_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,
+ .rename = shmem_rename,
+#endif
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ .setattr = shmem_notify_change,
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+ .check_acl = generic_check_acl,
+#endif
+};
+
+static const struct inode_operations shmem_special_inode_operations = {
+#ifdef CONFIG_TMPFS_POSIX_ACL
+ .setattr = shmem_notify_change,
+ .setxattr = generic_setxattr,
+ .getxattr = generic_getxattr,
+ .listxattr = generic_listxattr,
+ .removexattr = generic_removexattr,
+ .check_acl = generic_check_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
+ .delete_inode = shmem_delete_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = shmem_put_super,
+};
+
+static const struct vm_operations_struct shmem_vm_ops = {
+ .fault = shmem_fault,
+#ifdef CONFIG_NUMA
+ .set_policy = shmem_set_policy,
+ .get_policy = shmem_get_policy,
+#endif
+};
+
+
+static int shmem_get_sb(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data, struct vfsmount *mnt)
+{
+ return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
+}
+
+static struct file_system_type tmpfs_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "tmpfs",
+ .get_sb = shmem_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+int __init init_tmpfs(void)
+{
+ int error;
+
+ error = bdi_init(&shmem_backing_dev_info);
+ if (error)
+ goto out4;
+
+ 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;
+ }
+
+ shm_mnt = vfs_kern_mount(&tmpfs_fs_type, 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:
+ bdi_destroy(&shmem_backing_dev_info);
+out4:
+ 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.
+ */
+
+#include <linux/ramfs.h>
+
+static struct file_system_type tmpfs_fs_type = {
+ .name = "tmpfs",
+ .get_sb = ramfs_get_sb,
+ .kill_sb = kill_litter_super,
+};
+
+int __init init_tmpfs(void)
+{
+ BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
+
+ shm_mnt = kern_mount(&tmpfs_fs_type);
+ BUG_ON(IS_ERR(shm_mnt));
+
+ return 0;
+}
+
+int shmem_unuse(swp_entry_t entry, struct page *page)
+{
+ return 0;
+}
+
+int shmem_lock(struct file *file, int lock, struct user_struct *user)
+{
+ return 0;
+}
+
+#define shmem_vm_ops generic_file_vm_ops
+#define shmem_file_operations ramfs_file_operations
+#define shmem_get_inode(sb, mode, dev, flags) ramfs_get_inode(sb, mode, dev)
+#define shmem_acct_size(flags, size) 0
+#define shmem_unacct_size(flags, size) do {} while (0)
+#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE
+
+#endif /* CONFIG_SHMEM */
+
+/* common code */
+
+/**
+ * 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)
+{
+ int error;
+ struct file *file;
+ struct inode *inode;
+ struct path path;
+ struct 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;
+ path.dentry = d_alloc(root, &this);
+ if (!path.dentry)
+ goto put_memory;
+ path.mnt = mntget(shm_mnt);
+
+ error = -ENOSPC;
+ inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
+ if (!inode)
+ goto put_dentry;
+
+ d_instantiate(path.dentry, inode);
+ inode->i_size = size;
+ inode->i_nlink = 0; /* It is unlinked */
+#ifndef CONFIG_MMU
+ error = ramfs_nommu_expand_for_mapping(inode, size);
+ if (error)
+ goto put_dentry;
+#endif
+
+ error = -ENFILE;
+ file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
+ &shmem_file_operations);
+ if (!file)
+ goto put_dentry;
+
+ return file;
+
+put_dentry:
+ path_put(&path);
+put_memory:
+ shmem_unacct_size(flags, size);
+ return ERR_PTR(error);
+}
+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;
+
+ 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;
+}
generated by cgit (git 2.34.1) at 2025-08-30 00:38:48 +0000