1 files changed, 86 insertions, 18 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index dd5588f5d939..75199888a6bd 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -14,31 +14,39 @@
  * 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/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>
@@ -921,7 +929,11 @@ found:
         error = 1;
         if (!inode)
                 goto out;
-        /* Precharge page using GFP_KERNEL while we can wait */
+        /*
+         * 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;
@@ -1313,15 +1325,19 @@ repeat:
                 } else {
                         shmem_swp_unmap(entry);
                         spin_unlock(&info->lock);
-                        unlock_page(swappage);
-                        page_cache_release(swappage);
                         if (error == -ENOMEM) {
                                 /* allow reclaim from this memory cgroup */
-                                error = mem_cgroup_shrink_usage(current->mm,
+                                error = mem_cgroup_shrink_usage(swappage,
+                                                                current->mm,
                                                                 gfp);
-                                if (error)
+                                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) {
@@ -1372,7 +1388,7 @@ repeat:
 
                         /* Precharge page while we can wait, compensate after */
                         error = mem_cgroup_cache_charge(filepage, current->mm,
-                                                        gfp & ~__GFP_HIGHMEM);
+                                        GFP_KERNEL);
                         if (error) {
                                 page_cache_release(filepage);
                                 shmem_unacct_blocks(info->flags, 1);
@@ -1445,7 +1461,6 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
         if (error)
                 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
 
-        mark_page_accessed(vmf->page);
         return ret | VM_FAULT_LOCKED;
 }
 
@@ -2487,7 +2502,6 @@ static struct file_system_type tmpfs_fs_type = {
         .get_sb         = shmem_get_sb,
         .kill_sb        = kill_litter_super,
 };
-static struct vfsmount *shm_mnt;
 
 static int __init init_tmpfs(void)
 {
@@ -2526,7 +2540,51 @@ out4:
         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
@@ -2570,12 +2628,20 @@ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
         if (!inode)
                 goto close_file;
 
-        SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
+#ifdef CONFIG_SHMEM
+        SHMEM_I(inode)->flags = (flags & VM_NORESERVE) ? 0 : 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:
@@ -2608,3 +2674,5 @@ int shmem_zero_setup(struct vm_area_struct *vma)
         vma->vm_ops = &shmem_vm_ops;
         return 0;
 }
+
+module_init(init_tmpfs)