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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 | /* * tiny-shmem.c: simple shmemfs and tmpfs using ramfs code * * Matt Mackall <mpm@selenic.com> January, 2004 * derived from mm/shmem.c and fs/ramfs/inode.c * * 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/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> #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 struct vfsmount *shm_mnt; 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; } module_init(init_tmpfs) /** * shmem_file_setup - get an unlinked file living in tmpfs * @name: name for dentry (to be seen in /proc/<pid>/maps * @size: size to be set for the file * @flags: vm_flags */ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) { int error; struct file *file; struct inode *inode; struct dentry *dentry, *root; struct qstr this; if (IS_ERR(shm_mnt)) return (void *)shm_mnt; error = -ENOMEM; this.name = name; this.len = strlen(name); this.hash = 0; /* will go */ root = shm_mnt->mnt_root; dentry = d_alloc(root, &this); if (!dentry) goto put_memory; error = -ENFILE; file = get_empty_filp(); if (!file) goto put_dentry; error = -ENOSPC; inode = ramfs_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); if (!inode) goto close_file; 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, &ramfs_file_operations); #ifndef CONFIG_MMU error = ramfs_nommu_expand_for_mapping(inode, size); if (error) goto close_file; #endif return file; close_file: put_filp(file); put_dentry: dput(dentry); put_memory: return ERR_PTR(error); } /** * shmem_zero_setup - setup a shared anonymous mapping * @vma: the vma to be mmapped is prepared by do_mmap_pgoff */ int shmem_zero_setup(struct vm_area_struct *vma) { struct file *file; loff_t size = vma->vm_end - vma->vm_start; file = shmem_file_setup("dev/zero", size, vma->vm_flags); if (IS_ERR(file)) return PTR_ERR(file); if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; vma->vm_ops = &generic_file_vm_ops; return 0; } int shmem_unuse(swp_entry_t entry, struct page *page) { return 0; } #ifndef CONFIG_MMU unsigned long shmem_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { return ramfs_nommu_get_unmapped_area(file, addr, len, pgoff, flags); } #endif |