diff options
Diffstat (limited to 'fs/hostfs/hostfs_kern.c')
| -rw-r--r-- | fs/hostfs/hostfs_kern.c | 1006 |
1 files changed, 1006 insertions, 0 deletions
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c new file mode 100644 index 000000000..444c7b170 --- /dev/null +++ b/fs/hostfs/hostfs_kern.c @@ -0,0 +1,1006 @@ +/* + * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + * Licensed under the GPL + * + * Ported the filesystem routines to 2.5. + * 2003-02-10 Petr Baudis <pasky@ucw.cz> + */ + +#include <linux/fs.h> +#include <linux/magic.h> +#include <linux/module.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/statfs.h> +#include <linux/slab.h> +#include <linux/seq_file.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include "hostfs.h" +#include <init.h> +#include <kern.h> + +struct hostfs_inode_info { + int fd; + fmode_t mode; + struct inode vfs_inode; + struct mutex open_mutex; +}; + +static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) +{ + return list_entry(inode, struct hostfs_inode_info, vfs_inode); +} + +#define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) + +/* Changed in hostfs_args before the kernel starts running */ +static char *root_ino = ""; +static int append = 0; + +static const struct inode_operations hostfs_iops; +static const struct inode_operations hostfs_dir_iops; +static const struct inode_operations hostfs_link_iops; + +#ifndef MODULE +static int __init hostfs_args(char *options, int *add) +{ + char *ptr; + + ptr = strchr(options, ','); + if (ptr != NULL) + *ptr++ = '\0'; + if (*options != '\0') + root_ino = options; + + options = ptr; + while (options) { + ptr = strchr(options, ','); + if (ptr != NULL) + *ptr++ = '\0'; + if (*options != '\0') { + if (!strcmp(options, "append")) + append = 1; + else printf("hostfs_args - unsupported option - %s\n", + options); + } + options = ptr; + } + return 0; +} + +__uml_setup("hostfs=", hostfs_args, +"hostfs=<root dir>,<flags>,...\n" +" This is used to set hostfs parameters. The root directory argument\n" +" is used to confine all hostfs mounts to within the specified directory\n" +" tree on the host. If this isn't specified, then a user inside UML can\n" +" mount anything on the host that's accessible to the user that's running\n" +" it.\n" +" The only flag currently supported is 'append', which specifies that all\n" +" files opened by hostfs will be opened in append mode.\n\n" +); +#endif + +static char *__dentry_name(struct dentry *dentry, char *name) +{ + char *p = dentry_path_raw(dentry, name, PATH_MAX); + char *root; + size_t len; + + root = dentry->d_sb->s_fs_info; + len = strlen(root); + if (IS_ERR(p)) { + __putname(name); + return NULL; + } + + /* + * This function relies on the fact that dentry_path_raw() will place + * the path name at the end of the provided buffer. + */ + BUG_ON(p + strlen(p) + 1 != name + PATH_MAX); + + strlcpy(name, root, PATH_MAX); + if (len > p - name) { + __putname(name); + return NULL; + } + + if (p > name + len) + strcpy(name + len, p); + + return name; +} + +static char *dentry_name(struct dentry *dentry) +{ + char *name = __getname(); + if (!name) + return NULL; + + return __dentry_name(dentry, name); +} + +static char *inode_name(struct inode *ino) +{ + struct dentry *dentry; + char *name; + + dentry = d_find_alias(ino); + if (!dentry) + return NULL; + + name = dentry_name(dentry); + + dput(dentry); + + return name; +} + +static char *follow_link(char *link) +{ + int len, n; + char *name, *resolved, *end; + + name = __getname(); + if (!name) { + n = -ENOMEM; + goto out_free; + } + + n = hostfs_do_readlink(link, name, PATH_MAX); + if (n < 0) + goto out_free; + else if (n == PATH_MAX) { + n = -E2BIG; + goto out_free; + } + + if (*name == '/') + return name; + + end = strrchr(link, '/'); + if (end == NULL) + return name; + + *(end + 1) = '\0'; + len = strlen(link) + strlen(name) + 1; + + resolved = kmalloc(len, GFP_KERNEL); + if (resolved == NULL) { + n = -ENOMEM; + goto out_free; + } + + sprintf(resolved, "%s%s", link, name); + __putname(name); + kfree(link); + return resolved; + + out_free: + __putname(name); + return ERR_PTR(n); +} + +static struct inode *hostfs_iget(struct super_block *sb) +{ + struct inode *inode = new_inode(sb); + if (!inode) + return ERR_PTR(-ENOMEM); + return inode; +} + +static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) +{ + /* + * do_statfs uses struct statfs64 internally, but the linux kernel + * struct statfs still has 32-bit versions for most of these fields, + * so we convert them here + */ + int err; + long long f_blocks; + long long f_bfree; + long long f_bavail; + long long f_files; + long long f_ffree; + + err = do_statfs(dentry->d_sb->s_fs_info, + &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, + &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), + &sf->f_namelen); + if (err) + return err; + sf->f_blocks = f_blocks; + sf->f_bfree = f_bfree; + sf->f_bavail = f_bavail; + sf->f_files = f_files; + sf->f_ffree = f_ffree; + sf->f_type = HOSTFS_SUPER_MAGIC; + return 0; +} + +static struct inode *hostfs_alloc_inode(struct super_block *sb) +{ + struct hostfs_inode_info *hi; + + hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT); + if (hi == NULL) + return NULL; + hi->fd = -1; + hi->mode = 0; + inode_init_once(&hi->vfs_inode); + mutex_init(&hi->open_mutex); + return &hi->vfs_inode; +} + +static void hostfs_evict_inode(struct inode *inode) +{ + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + if (HOSTFS_I(inode)->fd != -1) { + close_file(&HOSTFS_I(inode)->fd); + HOSTFS_I(inode)->fd = -1; + } +} + +static void hostfs_i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + kfree(HOSTFS_I(inode)); +} + +static void hostfs_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, hostfs_i_callback); +} + +static int hostfs_show_options(struct seq_file *seq, struct dentry *root) +{ + const char *root_path = root->d_sb->s_fs_info; + size_t offset = strlen(root_ino) + 1; + + if (strlen(root_path) > offset) + seq_show_option(seq, root_path + offset, NULL); + + if (append) + seq_puts(seq, ",append"); + + return 0; +} + +static const struct super_operations hostfs_sbops = { + .alloc_inode = hostfs_alloc_inode, + .destroy_inode = hostfs_destroy_inode, + .evict_inode = hostfs_evict_inode, + .statfs = hostfs_statfs, + .show_options = hostfs_show_options, +}; + +static int hostfs_readdir(struct file *file, struct dir_context *ctx) +{ + void *dir; + char *name; + unsigned long long next, ino; + int error, len; + unsigned int type; + + name = dentry_name(file->f_path.dentry); + if (name == NULL) + return -ENOMEM; + dir = open_dir(name, &error); + __putname(name); + if (dir == NULL) + return -error; + next = ctx->pos; + seek_dir(dir, next); + while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { + if (!dir_emit(ctx, name, len, ino, type)) + break; + ctx->pos = next; + } + close_dir(dir); + return 0; +} + +static int hostfs_open(struct inode *ino, struct file *file) +{ + char *name; + fmode_t mode; + int err; + int r, w, fd; + + mode = file->f_mode & (FMODE_READ | FMODE_WRITE); + if ((mode & HOSTFS_I(ino)->mode) == mode) + return 0; + + mode |= HOSTFS_I(ino)->mode; + +retry: + r = w = 0; + + if (mode & FMODE_READ) + r = 1; + if (mode & FMODE_WRITE) + r = w = 1; + + name = dentry_name(file->f_path.dentry); + if (name == NULL) + return -ENOMEM; + + fd = open_file(name, r, w, append); + __putname(name); + if (fd < 0) + return fd; + + mutex_lock(&HOSTFS_I(ino)->open_mutex); + /* somebody else had handled it first? */ + if ((mode & HOSTFS_I(ino)->mode) == mode) { + mutex_unlock(&HOSTFS_I(ino)->open_mutex); + close_file(&fd); + return 0; + } + if ((mode | HOSTFS_I(ino)->mode) != mode) { + mode |= HOSTFS_I(ino)->mode; + mutex_unlock(&HOSTFS_I(ino)->open_mutex); + close_file(&fd); + goto retry; + } + if (HOSTFS_I(ino)->fd == -1) { + HOSTFS_I(ino)->fd = fd; + } else { + err = replace_file(fd, HOSTFS_I(ino)->fd); + close_file(&fd); + if (err < 0) { + mutex_unlock(&HOSTFS_I(ino)->open_mutex); + return err; + } + } + HOSTFS_I(ino)->mode = mode; + mutex_unlock(&HOSTFS_I(ino)->open_mutex); + + return 0; +} + +static int hostfs_file_release(struct inode *inode, struct file *file) +{ + filemap_write_and_wait(inode->i_mapping); + + return 0; +} + +static int hostfs_fsync(struct file *file, loff_t start, loff_t end, + int datasync) +{ + struct inode *inode = file->f_mapping->host; + int ret; + + ret = file_write_and_wait_range(file, start, end); + if (ret) + return ret; + + inode_lock(inode); + ret = fsync_file(HOSTFS_I(inode)->fd, datasync); + inode_unlock(inode); + + return ret; +} + +static const struct file_operations hostfs_file_fops = { + .llseek = generic_file_llseek, + .splice_read = generic_file_splice_read, + .read_iter = generic_file_read_iter, + .write_iter = generic_file_write_iter, + .mmap = generic_file_mmap, + .open = hostfs_open, + .release = hostfs_file_release, + .fsync = hostfs_fsync, +}; + +static const struct file_operations hostfs_dir_fops = { + .llseek = generic_file_llseek, + .iterate_shared = hostfs_readdir, + .read = generic_read_dir, + .open = hostfs_open, + .fsync = hostfs_fsync, +}; + +static int hostfs_writepage(struct page *page, struct writeback_control *wbc) +{ + struct address_space *mapping = page->mapping; + struct inode *inode = mapping->host; + char *buffer; + loff_t base = page_offset(page); + int count = PAGE_SIZE; + int end_index = inode->i_size >> PAGE_SHIFT; + int err; + + if (page->index >= end_index) + count = inode->i_size & (PAGE_SIZE-1); + + buffer = kmap(page); + + err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); + if (err != count) { + ClearPageUptodate(page); + goto out; + } + + if (base > inode->i_size) + inode->i_size = base; + + if (PageError(page)) + ClearPageError(page); + err = 0; + + out: + kunmap(page); + + unlock_page(page); + return err; +} + +static int hostfs_readpage(struct file *file, struct page *page) +{ + char *buffer; + loff_t start = page_offset(page); + int bytes_read, ret = 0; + + buffer = kmap(page); + bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, + PAGE_SIZE); + if (bytes_read < 0) { + ClearPageUptodate(page); + SetPageError(page); + ret = bytes_read; + goto out; + } + + memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); + + ClearPageError(page); + SetPageUptodate(page); + + out: + flush_dcache_page(page); + kunmap(page); + unlock_page(page); + return ret; +} + +static int hostfs_write_begin(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata) +{ + pgoff_t index = pos >> PAGE_SHIFT; + + *pagep = grab_cache_page_write_begin(mapping, index, flags); + if (!*pagep) + return -ENOMEM; + return 0; +} + +static int hostfs_write_end(struct file *file, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct page *page, void *fsdata) +{ + struct inode *inode = mapping->host; + void *buffer; + unsigned from = pos & (PAGE_SIZE - 1); + int err; + + buffer = kmap(page); + err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); + kunmap(page); + + if (!PageUptodate(page) && err == PAGE_SIZE) + SetPageUptodate(page); + + /* + * If err > 0, write_file has added err to pos, so we are comparing + * i_size against the last byte written. + */ + if (err > 0 && (pos > inode->i_size)) + inode->i_size = pos; + unlock_page(page); + put_page(page); + + return err; +} + +static const struct address_space_operations hostfs_aops = { + .writepage = hostfs_writepage, + .readpage = hostfs_readpage, + .set_page_dirty = __set_page_dirty_nobuffers, + .write_begin = hostfs_write_begin, + .write_end = hostfs_write_end, +}; + +static int read_name(struct inode *ino, char *name) +{ + dev_t rdev; + struct hostfs_stat st; + int err = stat_file(name, &st, -1); + if (err) + return err; + + /* Reencode maj and min with the kernel encoding.*/ + rdev = MKDEV(st.maj, st.min); + + switch (st.mode & S_IFMT) { + case S_IFLNK: + ino->i_op = &hostfs_link_iops; + break; + case S_IFDIR: + ino->i_op = &hostfs_dir_iops; + ino->i_fop = &hostfs_dir_fops; + break; + case S_IFCHR: + case S_IFBLK: + case S_IFIFO: + case S_IFSOCK: + init_special_inode(ino, st.mode & S_IFMT, rdev); + ino->i_op = &hostfs_iops; + break; + case S_IFREG: + ino->i_op = &hostfs_iops; + ino->i_fop = &hostfs_file_fops; + ino->i_mapping->a_ops = &hostfs_aops; + break; + default: + return -EIO; + } + + ino->i_ino = st.ino; + ino->i_mode = st.mode; + set_nlink(ino, st.nlink); + i_uid_write(ino, st.uid); + i_gid_write(ino, st.gid); + ino->i_atime = timespec_to_timespec64(st.atime); + ino->i_mtime = timespec_to_timespec64(st.mtime); + ino->i_ctime = timespec_to_timespec64(st.ctime); + ino->i_size = st.size; + ino->i_blocks = st.blocks; + return 0; +} + +static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, + bool excl) +{ + struct inode *inode; + char *name; + int error, fd; + + inode = hostfs_iget(dir->i_sb); + if (IS_ERR(inode)) { + error = PTR_ERR(inode); + goto out; + } + + error = -ENOMEM; + name = dentry_name(dentry); + if (name == NULL) + goto out_put; + + fd = file_create(name, mode & 0777); + if (fd < 0) + error = fd; + else + error = read_name(inode, name); + + __putname(name); + if (error) + goto out_put; + + HOSTFS_I(inode)->fd = fd; + HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; + d_instantiate(dentry, inode); + return 0; + + out_put: + iput(inode); + out: + return error; +} + +static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, + unsigned int flags) +{ + struct inode *inode; + char *name; + int err; + + inode = hostfs_iget(ino->i_sb); + if (IS_ERR(inode)) + goto out; + + err = -ENOMEM; + name = dentry_name(dentry); + if (name) { + err = read_name(inode, name); + __putname(name); + } + if (err) { + iput(inode); + inode = (err == -ENOENT) ? NULL : ERR_PTR(err); + } + out: + return d_splice_alias(inode, dentry); +} + +static int hostfs_link(struct dentry *to, struct inode *ino, + struct dentry *from) +{ + char *from_name, *to_name; + int err; + + if ((from_name = dentry_name(from)) == NULL) + return -ENOMEM; + to_name = dentry_name(to); + if (to_name == NULL) { + __putname(from_name); + return -ENOMEM; + } + err = link_file(to_name, from_name); + __putname(from_name); + __putname(to_name); + return err; +} + +static int hostfs_unlink(struct inode *ino, struct dentry *dentry) +{ + char *file; + int err; + + if (append) + return -EPERM; + + if ((file = dentry_name(dentry)) == NULL) + return -ENOMEM; + + err = unlink_file(file); + __putname(file); + return err; +} + +static int hostfs_symlink(struct inode *ino, struct dentry *dentry, + const char *to) +{ + char *file; + int err; + + if ((file = dentry_name(dentry)) == NULL) + return -ENOMEM; + err = make_symlink(file, to); + __putname(file); + return err; +} + +static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) +{ + char *file; + int err; + + if ((file = dentry_name(dentry)) == NULL) + return -ENOMEM; + err = do_mkdir(file, mode); + __putname(file); + return err; +} + +static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) +{ + char *file; + int err; + + if ((file = dentry_name(dentry)) == NULL) + return -ENOMEM; + err = hostfs_do_rmdir(file); + __putname(file); + return err; +} + +static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) +{ + struct inode *inode; + char *name; + int err; + + inode = hostfs_iget(dir->i_sb); + if (IS_ERR(inode)) { + err = PTR_ERR(inode); + goto out; + } + + err = -ENOMEM; + name = dentry_name(dentry); + if (name == NULL) + goto out_put; + + init_special_inode(inode, mode, dev); + err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); + if (err) + goto out_free; + + err = read_name(inode, name); + __putname(name); + if (err) + goto out_put; + + d_instantiate(dentry, inode); + return 0; + + out_free: + __putname(name); + out_put: + iput(inode); + out: + return err; +} + +static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry, + unsigned int flags) +{ + char *old_name, *new_name; + int err; + + if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) + return -EINVAL; + + old_name = dentry_name(old_dentry); + if (old_name == NULL) + return -ENOMEM; + new_name = dentry_name(new_dentry); + if (new_name == NULL) { + __putname(old_name); + return -ENOMEM; + } + if (!flags) + err = rename_file(old_name, new_name); + else + err = rename2_file(old_name, new_name, flags); + + __putname(old_name); + __putname(new_name); + return err; +} + +static int hostfs_permission(struct inode *ino, int desired) +{ + char *name; + int r = 0, w = 0, x = 0, err; + + if (desired & MAY_NOT_BLOCK) + return -ECHILD; + + if (desired & MAY_READ) r = 1; + if (desired & MAY_WRITE) w = 1; + if (desired & MAY_EXEC) x = 1; + name = inode_name(ino); + if (name == NULL) + return -ENOMEM; + + if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || + S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) + err = 0; + else + err = access_file(name, r, w, x); + __putname(name); + if (!err) + err = generic_permission(ino, desired); + return err; +} + +static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) +{ + struct inode *inode = d_inode(dentry); + struct hostfs_iattr attrs; + char *name; + int err; + + int fd = HOSTFS_I(inode)->fd; + + err = setattr_prepare(dentry, attr); + if (err) + return err; + + if (append) + attr->ia_valid &= ~ATTR_SIZE; + + attrs.ia_valid = 0; + if (attr->ia_valid & ATTR_MODE) { + attrs.ia_valid |= HOSTFS_ATTR_MODE; + attrs.ia_mode = attr->ia_mode; + } + if (attr->ia_valid & ATTR_UID) { + attrs.ia_valid |= HOSTFS_ATTR_UID; + attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); + } + if (attr->ia_valid & ATTR_GID) { + attrs.ia_valid |= HOSTFS_ATTR_GID; + attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); + } + if (attr->ia_valid & ATTR_SIZE) { + attrs.ia_valid |= HOSTFS_ATTR_SIZE; + attrs.ia_size = attr->ia_size; + } + if (attr->ia_valid & ATTR_ATIME) { + attrs.ia_valid |= HOSTFS_ATTR_ATIME; + attrs.ia_atime = timespec64_to_timespec(attr->ia_atime); + } + if (attr->ia_valid & ATTR_MTIME) { + attrs.ia_valid |= HOSTFS_ATTR_MTIME; + attrs.ia_mtime = timespec64_to_timespec(attr->ia_mtime); + } + if (attr->ia_valid & ATTR_CTIME) { + attrs.ia_valid |= HOSTFS_ATTR_CTIME; + attrs.ia_ctime = timespec64_to_timespec(attr->ia_ctime); + } + if (attr->ia_valid & ATTR_ATIME_SET) { + attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; + } + if (attr->ia_valid & ATTR_MTIME_SET) { + attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; + } + name = dentry_name(dentry); + if (name == NULL) + return -ENOMEM; + err = set_attr(name, &attrs, fd); + __putname(name); + if (err) + return err; + + if ((attr->ia_valid & ATTR_SIZE) && + attr->ia_size != i_size_read(inode)) + truncate_setsize(inode, attr->ia_size); + + setattr_copy(inode, attr); + mark_inode_dirty(inode); + return 0; +} + +static const struct inode_operations hostfs_iops = { + .permission = hostfs_permission, + .setattr = hostfs_setattr, +}; + +static const struct inode_operations hostfs_dir_iops = { + .create = hostfs_create, + .lookup = hostfs_lookup, + .link = hostfs_link, + .unlink = hostfs_unlink, + .symlink = hostfs_symlink, + .mkdir = hostfs_mkdir, + .rmdir = hostfs_rmdir, + .mknod = hostfs_mknod, + .rename = hostfs_rename2, + .permission = hostfs_permission, + .setattr = hostfs_setattr, +}; + +static const char *hostfs_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + char *link; + if (!dentry) + return ERR_PTR(-ECHILD); + link = kmalloc(PATH_MAX, GFP_KERNEL); + if (link) { + char *path = dentry_name(dentry); + int err = -ENOMEM; + if (path) { + err = hostfs_do_readlink(path, link, PATH_MAX); + if (err == PATH_MAX) + err = -E2BIG; + __putname(path); + } + if (err < 0) { + kfree(link); + return ERR_PTR(err); + } + } else { + return ERR_PTR(-ENOMEM); + } + + set_delayed_call(done, kfree_link, link); + return link; +} + +static const struct inode_operations hostfs_link_iops = { + .get_link = hostfs_get_link, +}; + +static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) +{ + struct inode *root_inode; + char *host_root_path, *req_root = d; + int err; + + sb->s_blocksize = 1024; + sb->s_blocksize_bits = 10; + sb->s_magic = HOSTFS_SUPER_MAGIC; + sb->s_op = &hostfs_sbops; + sb->s_d_op = &simple_dentry_operations; + sb->s_maxbytes = MAX_LFS_FILESIZE; + + /* NULL is printed as <NULL> by sprintf: avoid that. */ + if (req_root == NULL) + req_root = ""; + + err = -ENOMEM; + sb->s_fs_info = host_root_path = + kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); + if (host_root_path == NULL) + goto out; + + sprintf(host_root_path, "%s/%s", root_ino, req_root); + + root_inode = new_inode(sb); + if (!root_inode) + goto out; + + err = read_name(root_inode, host_root_path); + if (err) + goto out_put; + + if (S_ISLNK(root_inode->i_mode)) { + char *name = follow_link(host_root_path); + if (IS_ERR(name)) { + err = PTR_ERR(name); + goto out_put; + } + err = read_name(root_inode, name); + kfree(name); + if (err) + goto out_put; + } + + err = -ENOMEM; + sb->s_root = d_make_root(root_inode); + if (sb->s_root == NULL) + goto out; + + return 0; + +out_put: + iput(root_inode); +out: + return err; +} + +static struct dentry *hostfs_read_sb(struct file_system_type *type, + int flags, const char *dev_name, + void *data) +{ + return mount_nodev(type, flags, data, hostfs_fill_sb_common); +} + +static void hostfs_kill_sb(struct super_block *s) +{ + kill_anon_super(s); + kfree(s->s_fs_info); +} + +static struct file_system_type hostfs_type = { + .owner = THIS_MODULE, + .name = "hostfs", + .mount = hostfs_read_sb, + .kill_sb = hostfs_kill_sb, + .fs_flags = 0, +}; +MODULE_ALIAS_FS("hostfs"); + +static int __init init_hostfs(void) +{ + return register_filesystem(&hostfs_type); +} + +static void __exit exit_hostfs(void) +{ + unregister_filesystem(&hostfs_type); +} + +module_init(init_hostfs) +module_exit(exit_hostfs) +MODULE_LICENSE("GPL"); |