Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/mm/tiny-shmem.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 2722 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | */ |
12 | |
13 | #include <linux/fs.h> |
14 | #include <linux/init.h> |
15 | #include <linux/devfs_fs_kernel.h> |
16 | #include <linux/vfs.h> |
17 | #include <linux/mount.h> |
18 | #include <linux/file.h> |
19 | #include <linux/mm.h> |
20 | #include <linux/module.h> |
21 | #include <linux/swap.h> |
22 | #include <linux/ramfs.h> |
23 | |
24 | static struct file_system_type tmpfs_fs_type = { |
25 | .name = "tmpfs", |
26 | .get_sb = ramfs_get_sb, |
27 | .kill_sb = kill_litter_super, |
28 | }; |
29 | |
30 | static struct vfsmount *shm_mnt; |
31 | |
32 | static int __init init_tmpfs(void) |
33 | { |
34 | register_filesystem(&tmpfs_fs_type); |
35 | #ifdef CONFIG_TMPFS |
36 | devfs_mk_dir("shm"); |
37 | #endif |
38 | shm_mnt = kern_mount(&tmpfs_fs_type); |
39 | return 0; |
40 | } |
41 | module_init(init_tmpfs) |
42 | |
43 | /* |
44 | * shmem_file_setup - get an unlinked file living in tmpfs |
45 | * |
46 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
47 | * @size: size to be set for the file |
48 | * |
49 | */ |
50 | struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) |
51 | { |
52 | int error; |
53 | struct file *file; |
54 | struct inode *inode; |
55 | struct dentry *dentry, *root; |
56 | struct qstr this; |
57 | |
58 | if (IS_ERR(shm_mnt)) |
59 | return (void *)shm_mnt; |
60 | |
61 | error = -ENOMEM; |
62 | this.name = name; |
63 | this.len = strlen(name); |
64 | this.hash = 0; /* will go */ |
65 | root = shm_mnt->mnt_root; |
66 | dentry = d_alloc(root, &this); |
67 | if (!dentry) |
68 | goto put_memory; |
69 | |
70 | error = -ENFILE; |
71 | file = get_empty_filp(); |
72 | if (!file) |
73 | goto put_dentry; |
74 | |
75 | error = -ENOSPC; |
76 | inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); |
77 | if (!inode) |
78 | goto close_file; |
79 | |
80 | d_instantiate(dentry, inode); |
81 | inode->i_size = size; |
82 | inode->i_nlink = 0; /* It is unlinked */ |
83 | file->f_vfsmnt = mntget(shm_mnt); |
84 | file->f_dentry = dentry; |
85 | file->f_mapping = inode->i_mapping; |
86 | file->f_op = &ramfs_file_operations; |
87 | file->f_mode = FMODE_WRITE | FMODE_READ; |
88 | return file; |
89 | |
90 | close_file: |
91 | put_filp(file); |
92 | put_dentry: |
93 | dput(dentry); |
94 | put_memory: |
95 | return ERR_PTR(error); |
96 | } |
97 | |
98 | /* |
99 | * shmem_zero_setup - setup a shared anonymous mapping |
100 | * |
101 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
102 | */ |
103 | int shmem_zero_setup(struct vm_area_struct *vma) |
104 | { |
105 | struct file *file; |
106 | loff_t size = vma->vm_end - vma->vm_start; |
107 | |
108 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); |
109 | if (IS_ERR(file)) |
110 | return PTR_ERR(file); |
111 | |
112 | if (vma->vm_file) |
113 | fput(vma->vm_file); |
114 | vma->vm_file = file; |
115 | vma->vm_ops = &generic_file_vm_ops; |
116 | return 0; |
117 | } |
118 | |
119 | int shmem_unuse(swp_entry_t entry, struct page *page) |
120 | { |
121 | return 0; |
122 | } |