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Date: Thu, 04 Dec 2008 15:19:24 -0600
From: Matt Mackall <mpm@...enic.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hugh@...itas.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] shmem: unify regular and tiny shmem
tiny-shmem shares most of its 130 lines of code with shmem and tends
to break when particular bits of shmem get modified. Unifying saves
code and makes keeping these two in sync much easier.
before:
14367 392 24 14783 39bf mm/shmem.o
396 72 8 476 1dc mm/tiny-shmem.o
after:
14367 392 24 14783 39bf mm/shmem.o
412 72 8 492 1ec mm/shmem.o tiny
Signed-off-by: Matt Mackall <mpm@...enic.com>
diff -r 8a9f1e9c46e8 -r 3fd7e399e034 init/Kconfig
--- a/init/Kconfig Mon Oct 27 17:33:21 2008 -0500
+++ b/init/Kconfig Mon Oct 27 17:33:24 2008 -0500
@@ -830,10 +830,6 @@
boolean
select PLIST
-config TINY_SHMEM
- default !SHMEM
- bool
-
config BASE_SMALL
int
default 0 if BASE_FULL
diff -r 8a9f1e9c46e8 -r 3fd7e399e034 mm/Makefile
--- a/mm/Makefile Mon Oct 27 17:33:21 2008 -0500
+++ b/mm/Makefile Mon Oct 27 17:33:24 2008 -0500
@@ -9,7 +9,7 @@
obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o pdflush.o \
- readahead.o swap.o truncate.o vmscan.o \
+ readahead.o swap.o truncate.o vmscan.o shmem.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
page_isolation.o mm_init.o $(mmu-y)
@@ -21,9 +21,7 @@
obj-$(CONFIG_NUMA) += mempolicy.o
obj-$(CONFIG_SPARSEMEM) += sparse.o
obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
-obj-$(CONFIG_SHMEM) += shmem.o
obj-$(CONFIG_TMPFS_POSIX_ACL) += shmem_acl.o
-obj-$(CONFIG_TINY_SHMEM) += tiny-shmem.o
obj-$(CONFIG_SLOB) += slob.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
obj-$(CONFIG_SLAB) += slab.o
diff -r 8a9f1e9c46e8 -r 3fd7e399e034 mm/shmem.c
--- a/mm/shmem.c Mon Oct 27 17:33:21 2008 -0500
+++ b/mm/shmem.c Mon Oct 27 17:33:24 2008 -0500
@@ -14,31 +14,39 @@
* Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@...l.net>
* Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@...hat.com>
*
+ * tiny-shmem:
+ * Copyright (c) 2004, 2008 Matt Mackall <mpm@...enic.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/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/module.h>
-#include <linux/init.h>
-#include <linux/fs.h>
#include <linux/xattr.h>
#include <linux/exportfs.h>
#include <linux/generic_acl.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>
@@ -2486,7 +2494,6 @@
.get_sb = shmem_get_sb,
.kill_sb = kill_litter_super,
};
-static struct vfsmount *shm_mnt;
static int __init init_tmpfs(void)
{
@@ -2525,7 +2532,51 @@
shm_mnt = ERR_PTR(error);
return error;
}
-module_init(init_tmpfs)
+
+#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,
+};
+
+static 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;
+}
+
+#define shmem_file_operations ramfs_file_operations
+#define shmem_vm_ops generic_file_vm_ops
+#define shmem_get_inode ramfs_get_inode
+#define shmem_acct_size(a, b) 0
+#define shmem_unacct_size(a, b) do {} while (0)
+#define SHMEM_MAX_BYTES LLONG_MAX
+
+#endif /* CONFIG_SHMEM */
+
+/* common code */
/**
* shmem_file_setup - get an unlinked file living in tmpfs
@@ -2569,12 +2620,20 @@
if (!inode)
goto close_file;
+#ifdef CONFIG_SHMEM
SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
+#endif
d_instantiate(dentry, inode);
inode->i_size = size;
inode->i_nlink = 0; /* It is unlinked */
init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
- &shmem_file_operations);
+ &shmem_file_operations);
+
+#ifndef CONFIG_MMU
+ error = ramfs_nommu_expand_for_mapping(inode, size);
+ if (error)
+ goto close_file;
+#endif
return file;
close_file:
@@ -2606,3 +2665,5 @@
vma->vm_ops = &shmem_vm_ops;
return 0;
}
+
+module_init(init_tmpfs)
--
Mathematics is the supreme nostalgia of our time.
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