2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
5 * Ported the filesystem routines to 2.5.
6 * 2003-02-10 Petr Baudis <pasky@ucw.cz>
10 #include <linux/magic.h>
11 #include <linux/module.h>
13 #include <linux/pagemap.h>
14 #include <linux/statfs.h>
15 #include <linux/slab.h>
16 #include <linux/seq_file.h>
17 #include <linux/mount.h>
18 #include <linux/namei.h>
23 struct hostfs_inode_info {
26 struct inode vfs_inode;
27 struct mutex open_mutex;
30 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
32 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
35 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
37 /* Changed in hostfs_args before the kernel starts running */
38 static char *root_ino = "";
39 static int append = 0;
41 static const struct inode_operations hostfs_iops;
42 static const struct inode_operations hostfs_dir_iops;
43 static const struct inode_operations hostfs_link_iops;
46 static int __init hostfs_args(char *options, int *add)
50 ptr = strchr(options, ',');
58 ptr = strchr(options, ',');
61 if (*options != '\0') {
62 if (!strcmp(options, "append"))
64 else printf("hostfs_args - unsupported option - %s\n",
72 __uml_setup("hostfs=", hostfs_args,
73 "hostfs=<root dir>,<flags>,...\n"
74 " This is used to set hostfs parameters. The root directory argument\n"
75 " is used to confine all hostfs mounts to within the specified directory\n"
76 " tree on the host. If this isn't specified, then a user inside UML can\n"
77 " mount anything on the host that's accessible to the user that's running\n"
79 " The only flag currently supported is 'append', which specifies that all\n"
80 " files opened by hostfs will be opened in append mode.\n\n"
84 static char *__dentry_name(struct dentry *dentry, char *name)
86 char *p = dentry_path_raw(dentry, name, PATH_MAX);
90 root = dentry->d_sb->s_fs_info;
98 * This function relies on the fact that dentry_path_raw() will place
99 * the path name at the end of the provided buffer.
101 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX);
103 strlcpy(name, root, PATH_MAX);
104 if (len > p - name) {
110 strcpy(name + len, p);
115 static char *dentry_name(struct dentry *dentry)
117 char *name = __getname();
121 return __dentry_name(dentry, name);
124 static char *inode_name(struct inode *ino)
126 struct dentry *dentry;
129 dentry = d_find_alias(ino);
133 name = dentry_name(dentry);
140 static char *follow_link(char *link)
142 char *name, *resolved, *end;
145 name = kmalloc(PATH_MAX, GFP_KERNEL);
151 n = hostfs_do_readlink(link, name, PATH_MAX);
154 else if (n == PATH_MAX) {
162 end = strrchr(link, '/');
168 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name);
169 if (resolved == NULL) {
182 static struct inode *hostfs_iget(struct super_block *sb)
184 struct inode *inode = new_inode(sb);
186 return ERR_PTR(-ENOMEM);
190 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
193 * do_statfs uses struct statfs64 internally, but the linux kernel
194 * struct statfs still has 32-bit versions for most of these fields,
195 * so we convert them here
204 err = do_statfs(dentry->d_sb->s_fs_info,
205 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
206 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
210 sf->f_blocks = f_blocks;
211 sf->f_bfree = f_bfree;
212 sf->f_bavail = f_bavail;
213 sf->f_files = f_files;
214 sf->f_ffree = f_ffree;
215 sf->f_type = HOSTFS_SUPER_MAGIC;
219 static struct inode *hostfs_alloc_inode(struct super_block *sb)
221 struct hostfs_inode_info *hi;
223 hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT);
228 inode_init_once(&hi->vfs_inode);
229 mutex_init(&hi->open_mutex);
230 return &hi->vfs_inode;
233 static void hostfs_evict_inode(struct inode *inode)
235 truncate_inode_pages_final(&inode->i_data);
237 if (HOSTFS_I(inode)->fd != -1) {
238 close_file(&HOSTFS_I(inode)->fd);
239 HOSTFS_I(inode)->fd = -1;
243 static void hostfs_free_inode(struct inode *inode)
245 kfree(HOSTFS_I(inode));
248 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
250 const char *root_path = root->d_sb->s_fs_info;
251 size_t offset = strlen(root_ino) + 1;
253 if (strlen(root_path) > offset)
254 seq_show_option(seq, root_path + offset, NULL);
257 seq_puts(seq, ",append");
262 static const struct super_operations hostfs_sbops = {
263 .alloc_inode = hostfs_alloc_inode,
264 .free_inode = hostfs_free_inode,
265 .evict_inode = hostfs_evict_inode,
266 .statfs = hostfs_statfs,
267 .show_options = hostfs_show_options,
270 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
274 unsigned long long next, ino;
278 name = dentry_name(file->f_path.dentry);
281 dir = open_dir(name, &error);
287 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
288 if (!dir_emit(ctx, name, len, ino, type))
296 static int hostfs_open(struct inode *ino, struct file *file)
303 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
304 if ((mode & HOSTFS_I(ino)->mode) == mode)
307 mode |= HOSTFS_I(ino)->mode;
312 if (mode & FMODE_READ)
314 if (mode & FMODE_WRITE)
317 name = dentry_name(file->f_path.dentry);
321 fd = open_file(name, r, w, append);
326 mutex_lock(&HOSTFS_I(ino)->open_mutex);
327 /* somebody else had handled it first? */
328 if ((mode & HOSTFS_I(ino)->mode) == mode) {
329 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
333 if ((mode | HOSTFS_I(ino)->mode) != mode) {
334 mode |= HOSTFS_I(ino)->mode;
335 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
339 if (HOSTFS_I(ino)->fd == -1) {
340 HOSTFS_I(ino)->fd = fd;
342 err = replace_file(fd, HOSTFS_I(ino)->fd);
345 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
349 HOSTFS_I(ino)->mode = mode;
350 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
355 static int hostfs_file_release(struct inode *inode, struct file *file)
357 filemap_write_and_wait(inode->i_mapping);
362 static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
365 struct inode *inode = file->f_mapping->host;
368 ret = file_write_and_wait_range(file, start, end);
373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
379 static const struct file_operations hostfs_file_fops = {
380 .llseek = generic_file_llseek,
381 .splice_read = generic_file_splice_read,
382 .read_iter = generic_file_read_iter,
383 .write_iter = generic_file_write_iter,
384 .mmap = generic_file_mmap,
386 .release = hostfs_file_release,
387 .fsync = hostfs_fsync,
390 static const struct file_operations hostfs_dir_fops = {
391 .llseek = generic_file_llseek,
392 .iterate_shared = hostfs_readdir,
393 .read = generic_read_dir,
395 .fsync = hostfs_fsync,
398 static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
400 struct address_space *mapping = page->mapping;
401 struct inode *inode = mapping->host;
403 loff_t base = page_offset(page);
404 int count = PAGE_SIZE;
405 int end_index = inode->i_size >> PAGE_SHIFT;
408 if (page->index >= end_index)
409 count = inode->i_size & (PAGE_SIZE-1);
413 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
415 ClearPageUptodate(page);
419 if (base > inode->i_size)
420 inode->i_size = base;
423 ClearPageError(page);
433 static int hostfs_readpage(struct file *file, struct page *page)
436 loff_t start = page_offset(page);
437 int bytes_read, ret = 0;
440 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
442 if (bytes_read < 0) {
443 ClearPageUptodate(page);
449 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read);
451 ClearPageError(page);
452 SetPageUptodate(page);
455 flush_dcache_page(page);
461 static int hostfs_write_begin(struct file *file, struct address_space *mapping,
462 loff_t pos, unsigned len, unsigned flags,
463 struct page **pagep, void **fsdata)
465 pgoff_t index = pos >> PAGE_SHIFT;
467 *pagep = grab_cache_page_write_begin(mapping, index, flags);
473 static int hostfs_write_end(struct file *file, struct address_space *mapping,
474 loff_t pos, unsigned len, unsigned copied,
475 struct page *page, void *fsdata)
477 struct inode *inode = mapping->host;
479 unsigned from = pos & (PAGE_SIZE - 1);
483 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
486 if (!PageUptodate(page) && err == PAGE_SIZE)
487 SetPageUptodate(page);
490 * If err > 0, write_file has added err to pos, so we are comparing
491 * i_size against the last byte written.
493 if (err > 0 && (pos > inode->i_size))
501 static const struct address_space_operations hostfs_aops = {
502 .writepage = hostfs_writepage,
503 .readpage = hostfs_readpage,
504 .set_page_dirty = __set_page_dirty_nobuffers,
505 .write_begin = hostfs_write_begin,
506 .write_end = hostfs_write_end,
509 static int read_name(struct inode *ino, char *name)
512 struct hostfs_stat st;
513 int err = stat_file(name, &st, -1);
517 /* Reencode maj and min with the kernel encoding.*/
518 rdev = MKDEV(st.maj, st.min);
520 switch (st.mode & S_IFMT) {
522 ino->i_op = &hostfs_link_iops;
525 ino->i_op = &hostfs_dir_iops;
526 ino->i_fop = &hostfs_dir_fops;
532 init_special_inode(ino, st.mode & S_IFMT, rdev);
533 ino->i_op = &hostfs_iops;
536 ino->i_op = &hostfs_iops;
537 ino->i_fop = &hostfs_file_fops;
538 ino->i_mapping->a_ops = &hostfs_aops;
545 ino->i_mode = st.mode;
546 set_nlink(ino, st.nlink);
547 i_uid_write(ino, st.uid);
548 i_gid_write(ino, st.gid);
549 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec };
550 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec };
551 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec };
552 ino->i_size = st.size;
553 ino->i_blocks = st.blocks;
557 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
564 inode = hostfs_iget(dir->i_sb);
566 error = PTR_ERR(inode);
571 name = dentry_name(dentry);
575 fd = file_create(name, mode & 0777);
579 error = read_name(inode, name);
585 HOSTFS_I(inode)->fd = fd;
586 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
587 d_instantiate(dentry, inode);
596 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
603 inode = hostfs_iget(ino->i_sb);
608 name = dentry_name(dentry);
610 err = read_name(inode, name);
615 inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
618 return d_splice_alias(inode, dentry);
621 static int hostfs_link(struct dentry *to, struct inode *ino,
624 char *from_name, *to_name;
627 if ((from_name = dentry_name(from)) == NULL)
629 to_name = dentry_name(to);
630 if (to_name == NULL) {
631 __putname(from_name);
634 err = link_file(to_name, from_name);
635 __putname(from_name);
640 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
648 if ((file = dentry_name(dentry)) == NULL)
651 err = unlink_file(file);
656 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
662 if ((file = dentry_name(dentry)) == NULL)
664 err = make_symlink(file, to);
669 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
674 if ((file = dentry_name(dentry)) == NULL)
676 err = do_mkdir(file, mode);
681 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
686 if ((file = dentry_name(dentry)) == NULL)
688 err = hostfs_do_rmdir(file);
693 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
699 inode = hostfs_iget(dir->i_sb);
701 err = PTR_ERR(inode);
706 name = dentry_name(dentry);
710 init_special_inode(inode, mode, dev);
711 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
715 err = read_name(inode, name);
720 d_instantiate(dentry, inode);
731 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
732 struct inode *new_dir, struct dentry *new_dentry,
735 char *old_name, *new_name;
738 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
741 old_name = dentry_name(old_dentry);
742 if (old_name == NULL)
744 new_name = dentry_name(new_dentry);
745 if (new_name == NULL) {
750 err = rename_file(old_name, new_name);
752 err = rename2_file(old_name, new_name, flags);
759 static int hostfs_permission(struct inode *ino, int desired)
762 int r = 0, w = 0, x = 0, err;
764 if (desired & MAY_NOT_BLOCK)
767 if (desired & MAY_READ) r = 1;
768 if (desired & MAY_WRITE) w = 1;
769 if (desired & MAY_EXEC) x = 1;
770 name = inode_name(ino);
774 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
775 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
778 err = access_file(name, r, w, x);
781 err = generic_permission(ino, desired);
785 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
787 struct inode *inode = d_inode(dentry);
788 struct hostfs_iattr attrs;
792 int fd = HOSTFS_I(inode)->fd;
794 err = setattr_prepare(dentry, attr);
799 attr->ia_valid &= ~ATTR_SIZE;
802 if (attr->ia_valid & ATTR_MODE) {
803 attrs.ia_valid |= HOSTFS_ATTR_MODE;
804 attrs.ia_mode = attr->ia_mode;
806 if (attr->ia_valid & ATTR_UID) {
807 attrs.ia_valid |= HOSTFS_ATTR_UID;
808 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
810 if (attr->ia_valid & ATTR_GID) {
811 attrs.ia_valid |= HOSTFS_ATTR_GID;
812 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
814 if (attr->ia_valid & ATTR_SIZE) {
815 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
816 attrs.ia_size = attr->ia_size;
818 if (attr->ia_valid & ATTR_ATIME) {
819 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
820 attrs.ia_atime = (struct hostfs_timespec)
821 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec };
823 if (attr->ia_valid & ATTR_MTIME) {
824 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
825 attrs.ia_mtime = (struct hostfs_timespec)
826 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec };
828 if (attr->ia_valid & ATTR_CTIME) {
829 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
830 attrs.ia_ctime = (struct hostfs_timespec)
831 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec };
833 if (attr->ia_valid & ATTR_ATIME_SET) {
834 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
836 if (attr->ia_valid & ATTR_MTIME_SET) {
837 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
839 name = dentry_name(dentry);
842 err = set_attr(name, &attrs, fd);
847 if ((attr->ia_valid & ATTR_SIZE) &&
848 attr->ia_size != i_size_read(inode))
849 truncate_setsize(inode, attr->ia_size);
851 setattr_copy(inode, attr);
852 mark_inode_dirty(inode);
856 static const struct inode_operations hostfs_iops = {
857 .permission = hostfs_permission,
858 .setattr = hostfs_setattr,
861 static const struct inode_operations hostfs_dir_iops = {
862 .create = hostfs_create,
863 .lookup = hostfs_lookup,
865 .unlink = hostfs_unlink,
866 .symlink = hostfs_symlink,
867 .mkdir = hostfs_mkdir,
868 .rmdir = hostfs_rmdir,
869 .mknod = hostfs_mknod,
870 .rename = hostfs_rename2,
871 .permission = hostfs_permission,
872 .setattr = hostfs_setattr,
875 static const char *hostfs_get_link(struct dentry *dentry,
877 struct delayed_call *done)
881 return ERR_PTR(-ECHILD);
882 link = kmalloc(PATH_MAX, GFP_KERNEL);
884 char *path = dentry_name(dentry);
887 err = hostfs_do_readlink(path, link, PATH_MAX);
897 return ERR_PTR(-ENOMEM);
900 set_delayed_call(done, kfree_link, link);
904 static const struct inode_operations hostfs_link_iops = {
905 .get_link = hostfs_get_link,
908 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
910 struct inode *root_inode;
911 char *host_root_path, *req_root = d;
914 sb->s_blocksize = 1024;
915 sb->s_blocksize_bits = 10;
916 sb->s_magic = HOSTFS_SUPER_MAGIC;
917 sb->s_op = &hostfs_sbops;
918 sb->s_d_op = &simple_dentry_operations;
919 sb->s_maxbytes = MAX_LFS_FILESIZE;
921 /* NULL is printed as '(null)' by printf(): avoid that. */
922 if (req_root == NULL)
926 sb->s_fs_info = host_root_path =
927 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root);
928 if (host_root_path == NULL)
931 root_inode = new_inode(sb);
935 err = read_name(root_inode, host_root_path);
939 if (S_ISLNK(root_inode->i_mode)) {
940 char *name = follow_link(host_root_path);
945 err = read_name(root_inode, name);
952 sb->s_root = d_make_root(root_inode);
953 if (sb->s_root == NULL)
964 static struct dentry *hostfs_read_sb(struct file_system_type *type,
965 int flags, const char *dev_name,
968 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
971 static void hostfs_kill_sb(struct super_block *s)
977 static struct file_system_type hostfs_type = {
978 .owner = THIS_MODULE,
980 .mount = hostfs_read_sb,
981 .kill_sb = hostfs_kill_sb,
984 MODULE_ALIAS_FS("hostfs");
986 static int __init init_hostfs(void)
988 return register_filesystem(&hostfs_type);
991 static void __exit exit_hostfs(void)
993 unregister_filesystem(&hostfs_type);
996 module_init(init_hostfs)
997 module_exit(exit_hostfs)
998 MODULE_LICENSE("GPL");