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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /fs/ramfs/inode.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'fs/ramfs/inode.c')
-rw-r--r-- | fs/ramfs/inode.c | 299 |
1 files changed, 299 insertions, 0 deletions
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c new file mode 100644 index 000000000..f368a1690 --- /dev/null +++ b/fs/ramfs/inode.c @@ -0,0 +1,299 @@ +/* + * Resizable simple ram filesystem for Linux. + * + * Copyright (C) 2000 Linus Torvalds. + * 2000 Transmeta Corp. + * + * Usage limits added by David Gibson, Linuxcare Australia. + * This file is released under the GPL. + */ + +/* + * NOTE! This filesystem is probably most useful + * not as a real filesystem, but as an example of + * how virtual filesystems can be written. + * + * It doesn't get much simpler than this. Consider + * that this file implements the full semantics of + * a POSIX-compliant read-write filesystem. + * + * Note in particular how the filesystem does not + * need to implement any data structures of its own + * to keep track of the virtual data: using the VFS + * caches is sufficient. + */ + +#include <linux/fs.h> +#include <linux/pagemap.h> +#include <linux/highmem.h> +#include <linux/time.h> +#include <linux/init.h> +#include <linux/string.h> +#include <linux/backing-dev.h> +#include <linux/ramfs.h> +#include <linux/sched.h> +#include <linux/parser.h> +#include <linux/magic.h> +#include <linux/slab.h> +#include <linux/uaccess.h> +#include <linux/fs_context.h> +#include <linux/fs_parser.h> +#include <linux/seq_file.h> +#include "internal.h" + +struct ramfs_mount_opts { + umode_t mode; +}; + +struct ramfs_fs_info { + struct ramfs_mount_opts mount_opts; +}; + +#define RAMFS_DEFAULT_MODE 0755 + +static const struct super_operations ramfs_ops; +static const struct inode_operations ramfs_dir_inode_operations; + +struct inode *ramfs_get_inode(struct super_block *sb, + const struct inode *dir, umode_t mode, dev_t dev) +{ + struct inode * inode = new_inode(sb); + + if (inode) { + inode->i_ino = get_next_ino(); + inode_init_owner(&init_user_ns, inode, dir, mode); + inode->i_mapping->a_ops = &ram_aops; + mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); + mapping_set_unevictable(inode->i_mapping); + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); + switch (mode & S_IFMT) { + default: + init_special_inode(inode, mode, dev); + break; + case S_IFREG: + inode->i_op = &ramfs_file_inode_operations; + inode->i_fop = &ramfs_file_operations; + break; + case S_IFDIR: + inode->i_op = &ramfs_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + break; + case S_IFLNK: + inode->i_op = &page_symlink_inode_operations; + inode_nohighmem(inode); + break; + } + } + return inode; +} + +/* + * File creation. Allocate an inode, and we're done.. + */ +/* SMP-safe */ +static int +ramfs_mknod(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, dev_t dev) +{ + struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev); + int error = -ENOSPC; + + if (inode) { + d_instantiate(dentry, inode); + dget(dentry); /* Extra count - pin the dentry in core */ + error = 0; + dir->i_mtime = dir->i_ctime = current_time(dir); + } + return error; +} + +static int ramfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode) +{ + int retval = ramfs_mknod(&init_user_ns, dir, dentry, mode | S_IFDIR, 0); + if (!retval) + inc_nlink(dir); + return retval; +} + +static int ramfs_create(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) +{ + return ramfs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); +} + +static int ramfs_symlink(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, const char *symname) +{ + struct inode *inode; + int error = -ENOSPC; + + inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0); + if (inode) { + int l = strlen(symname)+1; + error = page_symlink(inode, symname, l); + if (!error) { + d_instantiate(dentry, inode); + dget(dentry); + dir->i_mtime = dir->i_ctime = current_time(dir); + } else + iput(inode); + } + return error; +} + +static int ramfs_tmpfile(struct user_namespace *mnt_userns, + struct inode *dir, struct file *file, umode_t mode) +{ + struct inode *inode; + + inode = ramfs_get_inode(dir->i_sb, dir, mode, 0); + if (!inode) + return -ENOSPC; + d_tmpfile(file, inode); + return finish_open_simple(file, 0); +} + +static const struct inode_operations ramfs_dir_inode_operations = { + .create = ramfs_create, + .lookup = simple_lookup, + .link = simple_link, + .unlink = simple_unlink, + .symlink = ramfs_symlink, + .mkdir = ramfs_mkdir, + .rmdir = simple_rmdir, + .mknod = ramfs_mknod, + .rename = simple_rename, + .tmpfile = ramfs_tmpfile, +}; + +/* + * Display the mount options in /proc/mounts. + */ +static int ramfs_show_options(struct seq_file *m, struct dentry *root) +{ + struct ramfs_fs_info *fsi = root->d_sb->s_fs_info; + + if (fsi->mount_opts.mode != RAMFS_DEFAULT_MODE) + seq_printf(m, ",mode=%o", fsi->mount_opts.mode); + return 0; +} + +static const struct super_operations ramfs_ops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, + .show_options = ramfs_show_options, +}; + +enum ramfs_param { + Opt_mode, +}; + +const struct fs_parameter_spec ramfs_fs_parameters[] = { + fsparam_u32oct("mode", Opt_mode), + {} +}; + +static int ramfs_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + struct fs_parse_result result; + struct ramfs_fs_info *fsi = fc->s_fs_info; + int opt; + + opt = fs_parse(fc, ramfs_fs_parameters, param, &result); + if (opt == -ENOPARAM) { + opt = vfs_parse_fs_param_source(fc, param); + if (opt != -ENOPARAM) + return opt; + /* + * We might like to report bad mount options here; + * but traditionally ramfs has ignored all mount options, + * and as it is used as a !CONFIG_SHMEM simple substitute + * for tmpfs, better continue to ignore other mount options. + */ + return 0; + } + if (opt < 0) + return opt; + + switch (opt) { + case Opt_mode: + fsi->mount_opts.mode = result.uint_32 & S_IALLUGO; + break; + } + + return 0; +} + +static int ramfs_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct ramfs_fs_info *fsi = sb->s_fs_info; + struct inode *inode; + + sb->s_maxbytes = MAX_LFS_FILESIZE; + sb->s_blocksize = PAGE_SIZE; + sb->s_blocksize_bits = PAGE_SHIFT; + sb->s_magic = RAMFS_MAGIC; + sb->s_op = &ramfs_ops; + sb->s_time_gran = 1; + + inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0); + sb->s_root = d_make_root(inode); + if (!sb->s_root) + return -ENOMEM; + + return 0; +} + +static int ramfs_get_tree(struct fs_context *fc) +{ + return get_tree_nodev(fc, ramfs_fill_super); +} + +static void ramfs_free_fc(struct fs_context *fc) +{ + kfree(fc->s_fs_info); +} + +static const struct fs_context_operations ramfs_context_ops = { + .free = ramfs_free_fc, + .parse_param = ramfs_parse_param, + .get_tree = ramfs_get_tree, +}; + +int ramfs_init_fs_context(struct fs_context *fc) +{ + struct ramfs_fs_info *fsi; + + fsi = kzalloc(sizeof(*fsi), GFP_KERNEL); + if (!fsi) + return -ENOMEM; + + fsi->mount_opts.mode = RAMFS_DEFAULT_MODE; + fc->s_fs_info = fsi; + fc->ops = &ramfs_context_ops; + return 0; +} + +void ramfs_kill_sb(struct super_block *sb) +{ + kfree(sb->s_fs_info); + kill_litter_super(sb); +} + +static struct file_system_type ramfs_fs_type = { + .name = "ramfs", + .init_fs_context = ramfs_init_fs_context, + .parameters = ramfs_fs_parameters, + .kill_sb = ramfs_kill_sb, + .fs_flags = FS_USERNS_MOUNT, +}; + +static int __init init_ramfs_fs(void) +{ + return register_filesystem(&ramfs_fs_type); +} +fs_initcall(init_ramfs_fs); |