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!

1 files changed, 2326 insertions, 0 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
new file mode 100644
index 000000000000..61574b81d979
--- /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;