Commit | Line | Data |
---|---|---|
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 | ||
ce8d2cdf | 68 | error = -ENFILE; |
db203d53 | 69 | file = get_empty_filp(); |
ce8d2cdf DH |
70 | if (!file) |
71 | goto put_dentry; | |
b0e15190 | 72 | |
db203d53 NP |
73 | error = -ENOSPC; |
74 | inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); | |
75 | if (!inode) | |
b0e15190 DH |
76 | goto close_file; |
77 | ||
db203d53 NP |
78 | d_instantiate(dentry, inode); |
79 | inode->i_size = size; | |
80 | inode->i_nlink = 0; /* It is unlinked */ | |
81 | init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ, | |
82 | &ramfs_file_operations); | |
4b19de6d NP |
83 | |
84 | #ifndef CONFIG_MMU | |
85 | error = ramfs_nommu_expand_for_mapping(inode, size); | |
86 | if (error) | |
87 | goto close_file; | |
88 | #endif | |
1da177e4 LT |
89 | return file; |
90 | ||
91 | close_file: | |
92 | put_filp(file); | |
93 | put_dentry: | |
94 | dput(dentry); | |
95 | put_memory: | |
96 | return ERR_PTR(error); | |
97 | } | |
e798ba57 | 98 | EXPORT_SYMBOL_GPL(shmem_file_setup); |
1da177e4 | 99 | |
46711810 | 100 | /** |
1da177e4 | 101 | * shmem_zero_setup - setup a shared anonymous mapping |
1da177e4 LT |
102 | * @vma: the vma to be mmapped is prepared by do_mmap_pgoff |
103 | */ | |
104 | int shmem_zero_setup(struct vm_area_struct *vma) | |
105 | { | |
106 | struct file *file; | |
107 | loff_t size = vma->vm_end - vma->vm_start; | |
108 | ||
109 | file = shmem_file_setup("dev/zero", size, vma->vm_flags); | |
110 | if (IS_ERR(file)) | |
111 | return PTR_ERR(file); | |
112 | ||
113 | if (vma->vm_file) | |
114 | fput(vma->vm_file); | |
115 | vma->vm_file = file; | |
116 | vma->vm_ops = &generic_file_vm_ops; | |
117 | return 0; | |
118 | } | |
119 | ||
120 | int shmem_unuse(swp_entry_t entry, struct page *page) | |
121 | { | |
122 | return 0; | |
123 | } | |
b0e15190 | 124 | |
b0e15190 DH |
125 | #ifndef CONFIG_MMU |
126 | unsigned long shmem_get_unmapped_area(struct file *file, | |
127 | unsigned long addr, | |
128 | unsigned long len, | |
129 | unsigned long pgoff, | |
130 | unsigned long flags) | |
131 | { | |
132 | return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags); | |
133 | } | |
134 | #endif |