ia64/linux-2.6.18-xen.hg

view mm/tiny-shmem.c @ 563:3b3701ad4eec

pvSCSI frontend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:56 2008 +0100 (2008-06-02)
parents 831230e53067
children
line source
1 /*
2 * tiny-shmem.c: simple shmemfs and tmpfs using ramfs code
3 *
4 * Matt Mackall <mpm@selenic.com> January, 2004
5 * derived from mm/shmem.c and fs/ramfs/inode.c
6 *
7 * This is intended for small system where the benefits of the full
8 * shmem code (swap-backed and resource-limited) are outweighed by
9 * their complexity. On systems without swap this code should be
10 * effectively equivalent, but much lighter weight.
11 */
13 #include <linux/fs.h>
14 #include <linux/init.h>
15 #include <linux/vfs.h>
16 #include <linux/mount.h>
17 #include <linux/file.h>
18 #include <linux/mm.h>
19 #include <linux/module.h>
20 #include <linux/swap.h>
21 #include <linux/ramfs.h>
23 static struct file_system_type tmpfs_fs_type = {
24 .name = "tmpfs",
25 .get_sb = ramfs_get_sb,
26 .kill_sb = kill_litter_super,
27 };
29 static struct vfsmount *shm_mnt;
31 static int __init init_tmpfs(void)
32 {
33 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
35 shm_mnt = kern_mount(&tmpfs_fs_type);
36 BUG_ON(IS_ERR(shm_mnt));
38 return 0;
39 }
40 module_init(init_tmpfs)
42 /*
43 * shmem_file_setup - get an unlinked file living in tmpfs
44 *
45 * @name: name for dentry (to be seen in /proc/<pid>/maps
46 * @size: size to be set for the file
47 *
48 */
49 struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
50 {
51 int error;
52 struct file *file;
53 struct inode *inode;
54 struct dentry *dentry, *root;
55 struct qstr this;
57 if (IS_ERR(shm_mnt))
58 return (void *)shm_mnt;
60 error = -ENOMEM;
61 this.name = name;
62 this.len = strlen(name);
63 this.hash = 0; /* will go */
64 root = shm_mnt->mnt_root;
65 dentry = d_alloc(root, &this);
66 if (!dentry)
67 goto put_memory;
69 error = -ENFILE;
70 file = get_empty_filp();
71 if (!file)
72 goto put_dentry;
74 error = -ENOSPC;
75 inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
76 if (!inode)
77 goto close_file;
79 d_instantiate(dentry, inode);
80 inode->i_nlink = 0; /* It is unlinked */
82 file->f_vfsmnt = mntget(shm_mnt);
83 file->f_dentry = dentry;
84 file->f_mapping = inode->i_mapping;
85 file->f_op = &ramfs_file_operations;
86 file->f_mode = FMODE_WRITE | FMODE_READ;
88 /* notify everyone as to the change of file size */
89 error = do_truncate(dentry, size, 0, file);
90 if (error < 0)
91 goto close_file;
93 return file;
95 close_file:
96 put_filp(file);
97 put_dentry:
98 dput(dentry);
99 put_memory:
100 return ERR_PTR(error);
101 }
103 /*
104 * shmem_zero_setup - setup a shared anonymous mapping
105 *
106 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
107 */
108 int shmem_zero_setup(struct vm_area_struct *vma)
109 {
110 struct file *file;
111 loff_t size = vma->vm_end - vma->vm_start;
113 file = shmem_file_setup("dev/zero", size, vma->vm_flags);
114 if (IS_ERR(file))
115 return PTR_ERR(file);
117 if (vma->vm_file)
118 fput(vma->vm_file);
119 vma->vm_file = file;
120 vma->vm_ops = &generic_file_vm_ops;
121 return 0;
122 }
124 int shmem_unuse(swp_entry_t entry, struct page *page)
125 {
126 return 0;
127 }
129 int shmem_mmap(struct file *file, struct vm_area_struct *vma)
130 {
131 file_accessed(file);
132 #ifndef CONFIG_MMU
133 return ramfs_nommu_mmap(file, vma);
134 #else
135 return 0;
136 #endif
137 }
139 #ifndef CONFIG_MMU
140 unsigned long shmem_get_unmapped_area(struct file *file,
141 unsigned long addr,
142 unsigned long len,
143 unsigned long pgoff,
144 unsigned long flags)
145 {
146 return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags);
147 }
148 #endif