Commit | Line | Data |
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1da177e4 LT |
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> | |
1da177e4 LT |
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> | |
22 | ||
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 | }; | |
28 | ||
29 | static struct vfsmount *shm_mnt; | |
30 | ||
31 | static int __init init_tmpfs(void) | |
32 | { | |
5d57bd39 MM |
33 | BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); |
34 | ||
1da177e4 | 35 | shm_mnt = kern_mount(&tmpfs_fs_type); |
5d57bd39 MM |
36 | BUG_ON(IS_ERR(shm_mnt)); |
37 | ||
1da177e4 LT |
38 | return 0; |
39 | } | |
40 | module_init(init_tmpfs) | |
41 | ||
46711810 | 42 | /** |
1da177e4 | 43 | * shmem_file_setup - get an unlinked file living in tmpfs |
1da177e4 LT |
44 | * @name: name for dentry (to be seen in /proc/<pid>/maps |
45 | * @size: size to be set for the file | |
46711810 | 46 | * @flags: vm_flags |
1da177e4 LT |
47 | */ |
48 | struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) | |
49 | { | |
50 | int error; | |
51 | struct file *file; | |
52 | struct inode *inode; | |
53 | struct dentry *dentry, *root; | |
54 | struct qstr this; | |
55 | ||
56 | if (IS_ERR(shm_mnt)) | |
57 | return (void *)shm_mnt; | |
58 | ||
59 | error = -ENOMEM; | |
60 | this.name = name; | |
61 | this.len = strlen(name); | |
62 | this.hash = 0; /* will go */ | |
63 | root = shm_mnt->mnt_root; | |
64 | dentry = d_alloc(root, &this); | |
65 | if (!dentry) | |
66 | goto put_memory; | |
67 | ||
1da177e4 LT |
68 | error = -ENOSPC; |
69 | inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); | |
70 | if (!inode) | |
ce8d2cdf | 71 | goto put_dentry; |
1da177e4 LT |
72 | |
73 | d_instantiate(dentry, inode); | |
ce8d2cdf DH |
74 | error = -ENFILE; |
75 | file = alloc_file(shm_mnt, dentry, FMODE_WRITE | FMODE_READ, | |
76 | &ramfs_file_operations); | |
77 | if (!file) | |
78 | goto put_dentry; | |
b0e15190 | 79 | |
ce8d2cdf | 80 | inode->i_nlink = 0; /* It is unlinked */ |
b0e15190 DH |
81 | |
82 | /* notify everyone as to the change of file size */ | |
2a7e2f7d | 83 | error = do_truncate(dentry, size, 0, file); |
b0e15190 DH |
84 | if (error < 0) |
85 | goto close_file; | |
86 | ||
1da177e4 LT |
87 | return file; |
88 | ||
89 | close_file: | |
90 | put_filp(file); | |
8a03feab AV |
91 | return ERR_PTR(error); |
92 | ||
1da177e4 LT |
93 | put_dentry: |
94 | dput(dentry); | |
95 | put_memory: | |
96 | return ERR_PTR(error); | |
97 | } | |
98 | ||
46711810 | 99 | /** |
1da177e4 | 100 | * shmem_zero_setup - setup a shared anonymous mapping |
1da177e4 LT |
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 | } | |
b0e15190 | 123 | |
b0e15190 DH |
124 | #ifndef CONFIG_MMU |
125 | unsigned long shmem_get_unmapped_area(struct file *file, | |
126 | unsigned long addr, | |
127 | unsigned long len, | |
128 | unsigned long pgoff, | |
129 | unsigned long flags) | |
130 | { | |
131 | return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags); | |
132 | } | |
133 | #endif |