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;
96 strlcpy(name, root, PATH_MAX);
101 if (p > name + len) {
102 char *s = name + len;
103 while ((*s++ = *p++) != '\0')
109 static char *dentry_name(struct dentry *dentry)
111 char *name = __getname();
115 return __dentry_name(dentry, name);
118 static char *inode_name(struct inode *ino)
120 struct dentry *dentry;
123 dentry = d_find_alias(ino);
127 name = dentry_name(dentry);
134 static char *follow_link(char *link)
137 char *name, *resolved, *end;
142 name = kmalloc(len, GFP_KERNEL);
146 n = hostfs_do_readlink(link, name, len);
158 end = strrchr(link, '/');
163 len = strlen(link) + strlen(name) + 1;
165 resolved = kmalloc(len, GFP_KERNEL);
166 if (resolved == NULL) {
171 sprintf(resolved, "%s%s", link, name);
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);
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_i_callback(struct rcu_head *head)
245 struct inode *inode = container_of(head, struct inode, i_rcu);
246 kfree(HOSTFS_I(inode));
249 static void hostfs_destroy_inode(struct inode *inode)
251 call_rcu(&inode->i_rcu, hostfs_i_callback);
254 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
256 const char *root_path = root->d_sb->s_fs_info;
257 size_t offset = strlen(root_ino) + 1;
259 if (strlen(root_path) > offset)
260 seq_printf(seq, ",%s", root_path + offset);
265 static const struct super_operations hostfs_sbops = {
266 .alloc_inode = hostfs_alloc_inode,
267 .destroy_inode = hostfs_destroy_inode,
268 .evict_inode = hostfs_evict_inode,
269 .statfs = hostfs_statfs,
270 .show_options = hostfs_show_options,
273 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
277 unsigned long long next, ino;
281 name = dentry_name(file->f_path.dentry);
284 dir = open_dir(name, &error);
289 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
290 if (!dir_emit(ctx, name, len, ino, type))
298 static int hostfs_open(struct inode *ino, struct file *file)
303 int r = 0, w = 0, fd;
305 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
306 if ((mode & HOSTFS_I(ino)->mode) == mode)
309 mode |= HOSTFS_I(ino)->mode;
312 if (mode & FMODE_READ)
314 if (mode & FMODE_WRITE)
319 name = dentry_name(file->f_path.dentry);
323 fd = open_file(name, r, w, append);
328 mutex_lock(&HOSTFS_I(ino)->open_mutex);
329 /* somebody else had handled it first? */
330 if ((mode & HOSTFS_I(ino)->mode) == mode) {
331 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
335 if ((mode | HOSTFS_I(ino)->mode) != mode) {
336 mode |= HOSTFS_I(ino)->mode;
337 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
341 if (HOSTFS_I(ino)->fd == -1) {
342 HOSTFS_I(ino)->fd = fd;
344 err = replace_file(fd, HOSTFS_I(ino)->fd);
347 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
351 HOSTFS_I(ino)->mode = mode;
352 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
357 static int hostfs_file_release(struct inode *inode, struct file *file)
359 filemap_write_and_wait(inode->i_mapping);
364 static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
367 struct inode *inode = file->f_mapping->host;
370 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
374 mutex_lock(&inode->i_mutex);
375 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
376 mutex_unlock(&inode->i_mutex);
381 static const struct file_operations hostfs_file_fops = {
382 .llseek = generic_file_llseek,
383 .read = new_sync_read,
384 .splice_read = generic_file_splice_read,
385 .read_iter = generic_file_read_iter,
386 .write_iter = generic_file_write_iter,
387 .write = new_sync_write,
388 .mmap = generic_file_mmap,
390 .release = hostfs_file_release,
391 .fsync = hostfs_fsync,
394 static const struct file_operations hostfs_dir_fops = {
395 .llseek = generic_file_llseek,
396 .iterate = hostfs_readdir,
397 .read = generic_read_dir,
399 .fsync = hostfs_fsync,
402 static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
404 struct address_space *mapping = page->mapping;
405 struct inode *inode = mapping->host;
407 unsigned long long base;
408 int count = PAGE_CACHE_SIZE;
409 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
412 if (page->index >= end_index)
413 count = inode->i_size & (PAGE_CACHE_SIZE-1);
416 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
418 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
420 ClearPageUptodate(page);
424 if (base > inode->i_size)
425 inode->i_size = base;
428 ClearPageError(page);
438 static int hostfs_readpage(struct file *file, struct page *page)
444 start = (long long) page->index << PAGE_CACHE_SHIFT;
446 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
448 if (bytes_read < 0) {
453 memset(buffer + bytes_read, 0, PAGE_CACHE_SIZE - bytes_read);
455 flush_dcache_page(page);
456 SetPageUptodate(page);
457 if (PageError(page)) ClearPageError(page);
465 static int hostfs_write_begin(struct file *file, struct address_space *mapping,
466 loff_t pos, unsigned len, unsigned flags,
467 struct page **pagep, void **fsdata)
469 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
471 *pagep = grab_cache_page_write_begin(mapping, index, flags);
477 static int hostfs_write_end(struct file *file, struct address_space *mapping,
478 loff_t pos, unsigned len, unsigned copied,
479 struct page *page, void *fsdata)
481 struct inode *inode = mapping->host;
483 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
487 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
490 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
491 SetPageUptodate(page);
494 * If err > 0, write_file has added err to pos, so we are comparing
495 * i_size against the last byte written.
497 if (err > 0 && (pos > inode->i_size))
500 page_cache_release(page);
505 static const struct address_space_operations hostfs_aops = {
506 .writepage = hostfs_writepage,
507 .readpage = hostfs_readpage,
508 .set_page_dirty = __set_page_dirty_nobuffers,
509 .write_begin = hostfs_write_begin,
510 .write_end = hostfs_write_end,
513 static int read_name(struct inode *ino, char *name)
516 struct hostfs_stat st;
517 int err = stat_file(name, &st, -1);
521 /* Reencode maj and min with the kernel encoding.*/
522 rdev = MKDEV(st.maj, st.min);
524 switch (st.mode & S_IFMT) {
526 ino->i_op = &hostfs_link_iops;
529 ino->i_op = &hostfs_dir_iops;
530 ino->i_fop = &hostfs_dir_fops;
536 init_special_inode(ino, st.mode & S_IFMT, rdev);
537 ino->i_op = &hostfs_iops;
540 ino->i_op = &hostfs_iops;
541 ino->i_fop = &hostfs_file_fops;
542 ino->i_mapping->a_ops = &hostfs_aops;
549 ino->i_mode = st.mode;
550 set_nlink(ino, st.nlink);
551 i_uid_write(ino, st.uid);
552 i_gid_write(ino, st.gid);
553 ino->i_atime = st.atime;
554 ino->i_mtime = st.mtime;
555 ino->i_ctime = st.ctime;
556 ino->i_size = st.size;
557 ino->i_blocks = st.blocks;
561 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
568 inode = hostfs_iget(dir->i_sb);
570 error = PTR_ERR(inode);
575 name = dentry_name(dentry);
579 fd = file_create(name,
580 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
581 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
582 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
586 error = read_name(inode, name);
592 HOSTFS_I(inode)->fd = fd;
593 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
594 d_instantiate(dentry, inode);
603 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
610 inode = hostfs_iget(ino->i_sb);
612 err = PTR_ERR(inode);
617 name = dentry_name(dentry);
621 err = read_name(inode, name);
624 if (err == -ENOENT) {
631 d_add(dentry, inode);
640 static int hostfs_link(struct dentry *to, struct inode *ino,
643 char *from_name, *to_name;
646 if ((from_name = dentry_name(from)) == NULL)
648 to_name = dentry_name(to);
649 if (to_name == NULL) {
650 __putname(from_name);
653 err = link_file(to_name, from_name);
654 __putname(from_name);
659 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
667 if ((file = dentry_name(dentry)) == NULL)
670 err = unlink_file(file);
675 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
681 if ((file = dentry_name(dentry)) == NULL)
683 err = make_symlink(file, to);
688 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
693 if ((file = dentry_name(dentry)) == NULL)
695 err = do_mkdir(file, mode);
700 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
705 if ((file = dentry_name(dentry)) == NULL)
707 err = do_rmdir(file);
712 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
718 inode = hostfs_iget(dir->i_sb);
720 err = PTR_ERR(inode);
725 name = dentry_name(dentry);
729 init_special_inode(inode, mode, dev);
730 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
734 err = read_name(inode, name);
741 d_instantiate(dentry, inode);
752 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
753 struct inode *new_dir, struct dentry *new_dentry,
756 char *old_name, *new_name;
759 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
762 old_name = dentry_name(old_dentry);
763 if (old_name == NULL)
765 new_name = dentry_name(new_dentry);
766 if (new_name == NULL) {
771 err = rename_file(old_name, new_name);
773 err = rename2_file(old_name, new_name, flags);
780 static int hostfs_permission(struct inode *ino, int desired)
783 int r = 0, w = 0, x = 0, err;
785 if (desired & MAY_NOT_BLOCK)
788 if (desired & MAY_READ) r = 1;
789 if (desired & MAY_WRITE) w = 1;
790 if (desired & MAY_EXEC) x = 1;
791 name = inode_name(ino);
795 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
796 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
799 err = access_file(name, r, w, x);
802 err = generic_permission(ino, desired);
806 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
808 struct inode *inode = dentry->d_inode;
809 struct hostfs_iattr attrs;
813 int fd = HOSTFS_I(inode)->fd;
815 err = inode_change_ok(inode, attr);
820 attr->ia_valid &= ~ATTR_SIZE;
823 if (attr->ia_valid & ATTR_MODE) {
824 attrs.ia_valid |= HOSTFS_ATTR_MODE;
825 attrs.ia_mode = attr->ia_mode;
827 if (attr->ia_valid & ATTR_UID) {
828 attrs.ia_valid |= HOSTFS_ATTR_UID;
829 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
831 if (attr->ia_valid & ATTR_GID) {
832 attrs.ia_valid |= HOSTFS_ATTR_GID;
833 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
835 if (attr->ia_valid & ATTR_SIZE) {
836 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
837 attrs.ia_size = attr->ia_size;
839 if (attr->ia_valid & ATTR_ATIME) {
840 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
841 attrs.ia_atime = attr->ia_atime;
843 if (attr->ia_valid & ATTR_MTIME) {
844 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
845 attrs.ia_mtime = attr->ia_mtime;
847 if (attr->ia_valid & ATTR_CTIME) {
848 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
849 attrs.ia_ctime = attr->ia_ctime;
851 if (attr->ia_valid & ATTR_ATIME_SET) {
852 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
854 if (attr->ia_valid & ATTR_MTIME_SET) {
855 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
857 name = dentry_name(dentry);
860 err = set_attr(name, &attrs, fd);
865 if ((attr->ia_valid & ATTR_SIZE) &&
866 attr->ia_size != i_size_read(inode))
867 truncate_setsize(inode, attr->ia_size);
869 setattr_copy(inode, attr);
870 mark_inode_dirty(inode);
874 static const struct inode_operations hostfs_iops = {
875 .permission = hostfs_permission,
876 .setattr = hostfs_setattr,
879 static const struct inode_operations hostfs_dir_iops = {
880 .create = hostfs_create,
881 .lookup = hostfs_lookup,
883 .unlink = hostfs_unlink,
884 .symlink = hostfs_symlink,
885 .mkdir = hostfs_mkdir,
886 .rmdir = hostfs_rmdir,
887 .mknod = hostfs_mknod,
888 .rename2 = hostfs_rename2,
889 .permission = hostfs_permission,
890 .setattr = hostfs_setattr,
893 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
895 char *link = __getname();
897 char *path = dentry_name(dentry);
900 err = hostfs_do_readlink(path, link, PATH_MAX);
910 link = ERR_PTR(-ENOMEM);
913 nd_set_link(nd, link);
917 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
919 char *s = nd_get_link(nd);
924 static const struct inode_operations hostfs_link_iops = {
925 .readlink = generic_readlink,
926 .follow_link = hostfs_follow_link,
927 .put_link = hostfs_put_link,
930 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
932 struct inode *root_inode;
933 char *host_root_path, *req_root = d;
936 sb->s_blocksize = 1024;
937 sb->s_blocksize_bits = 10;
938 sb->s_magic = HOSTFS_SUPER_MAGIC;
939 sb->s_op = &hostfs_sbops;
940 sb->s_d_op = &simple_dentry_operations;
941 sb->s_maxbytes = MAX_LFS_FILESIZE;
943 /* NULL is printed as <NULL> by sprintf: avoid that. */
944 if (req_root == NULL)
948 sb->s_fs_info = host_root_path =
949 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
950 if (host_root_path == NULL)
953 sprintf(host_root_path, "%s/%s", root_ino, req_root);
955 root_inode = new_inode(sb);
959 err = read_name(root_inode, host_root_path);
963 if (S_ISLNK(root_inode->i_mode)) {
964 char *name = follow_link(host_root_path);
968 err = read_name(root_inode, name);
975 sb->s_root = d_make_root(root_inode);
976 if (sb->s_root == NULL)
987 static struct dentry *hostfs_read_sb(struct file_system_type *type,
988 int flags, const char *dev_name,
991 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
994 static void hostfs_kill_sb(struct super_block *s)
1000 static struct file_system_type hostfs_type = {
1001 .owner = THIS_MODULE,
1003 .mount = hostfs_read_sb,
1004 .kill_sb = hostfs_kill_sb,
1007 MODULE_ALIAS_FS("hostfs");
1009 static int __init init_hostfs(void)
1011 return register_filesystem(&hostfs_type);
1014 static void __exit exit_hostfs(void)
1016 unregister_filesystem(&hostfs_type);
1019 module_init(init_hostfs)
1020 module_exit(exit_hostfs)
1021 MODULE_LICENSE("GPL");