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;
29 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
31 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
34 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file))
36 static int hostfs_d_delete(const struct dentry *dentry)
41 static const struct dentry_operations hostfs_dentry_ops = {
42 .d_delete = hostfs_d_delete,
45 /* Changed in hostfs_args before the kernel starts running */
46 static char *root_ino = "";
47 static int append = 0;
49 static const struct inode_operations hostfs_iops;
50 static const struct inode_operations hostfs_dir_iops;
51 static const struct inode_operations hostfs_link_iops;
54 static int __init hostfs_args(char *options, int *add)
58 ptr = strchr(options, ',');
66 ptr = strchr(options, ',');
69 if (*options != '\0') {
70 if (!strcmp(options, "append"))
72 else printf("hostfs_args - unsupported option - %s\n",
80 __uml_setup("hostfs=", hostfs_args,
81 "hostfs=<root dir>,<flags>,...\n"
82 " This is used to set hostfs parameters. The root directory argument\n"
83 " is used to confine all hostfs mounts to within the specified directory\n"
84 " tree on the host. If this isn't specified, then a user inside UML can\n"
85 " mount anything on the host that's accessible to the user that's running\n"
87 " The only flag currently supported is 'append', which specifies that all\n"
88 " files opened by hostfs will be opened in append mode.\n\n"
92 static char *__dentry_name(struct dentry *dentry, char *name)
94 char *p = dentry_path_raw(dentry, name, PATH_MAX);
98 root = dentry->d_sb->s_fs_info;
104 strlcpy(name, root, PATH_MAX);
105 if (len > p - name) {
109 if (p > name + len) {
110 char *s = name + len;
111 while ((*s++ = *p++) != '\0')
117 static char *dentry_name(struct dentry *dentry)
119 char *name = __getname();
123 return __dentry_name(dentry, name);
126 static char *inode_name(struct inode *ino)
128 struct dentry *dentry;
131 dentry = d_find_alias(ino);
135 name = dentry_name(dentry);
142 static char *follow_link(char *link)
145 char *name, *resolved, *end;
150 name = kmalloc(len, GFP_KERNEL);
154 n = hostfs_do_readlink(link, name, len);
166 end = strrchr(link, '/');
171 len = strlen(link) + strlen(name) + 1;
173 resolved = kmalloc(len, GFP_KERNEL);
174 if (resolved == NULL) {
179 sprintf(resolved, "%s%s", link, name);
190 static struct inode *hostfs_iget(struct super_block *sb)
192 struct inode *inode = new_inode(sb);
194 return ERR_PTR(-ENOMEM);
198 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
201 * do_statfs uses struct statfs64 internally, but the linux kernel
202 * struct statfs still has 32-bit versions for most of these fields,
203 * so we convert them here
212 err = do_statfs(dentry->d_sb->s_fs_info,
213 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
214 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
218 sf->f_blocks = f_blocks;
219 sf->f_bfree = f_bfree;
220 sf->f_bavail = f_bavail;
221 sf->f_files = f_files;
222 sf->f_ffree = f_ffree;
223 sf->f_type = HOSTFS_SUPER_MAGIC;
227 static struct inode *hostfs_alloc_inode(struct super_block *sb)
229 struct hostfs_inode_info *hi;
231 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
236 inode_init_once(&hi->vfs_inode);
237 return &hi->vfs_inode;
240 static void hostfs_evict_inode(struct inode *inode)
242 truncate_inode_pages(&inode->i_data, 0);
244 if (HOSTFS_I(inode)->fd != -1) {
245 close_file(&HOSTFS_I(inode)->fd);
246 HOSTFS_I(inode)->fd = -1;
250 static void hostfs_i_callback(struct rcu_head *head)
252 struct inode *inode = container_of(head, struct inode, i_rcu);
253 kfree(HOSTFS_I(inode));
256 static void hostfs_destroy_inode(struct inode *inode)
258 call_rcu(&inode->i_rcu, hostfs_i_callback);
261 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
263 const char *root_path = root->d_sb->s_fs_info;
264 size_t offset = strlen(root_ino) + 1;
266 if (strlen(root_path) > offset)
267 seq_printf(seq, ",%s", root_path + offset);
272 static const struct super_operations hostfs_sbops = {
273 .alloc_inode = hostfs_alloc_inode,
274 .destroy_inode = hostfs_destroy_inode,
275 .evict_inode = hostfs_evict_inode,
276 .statfs = hostfs_statfs,
277 .show_options = hostfs_show_options,
280 int hostfs_readdir(struct file *file, struct dir_context *ctx)
284 unsigned long long next, ino;
288 name = dentry_name(file->f_path.dentry);
291 dir = open_dir(name, &error);
296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
297 if (!dir_emit(ctx, name, len, ino, type))
305 int hostfs_file_open(struct inode *ino, struct file *file)
307 static DEFINE_MUTEX(open_mutex);
311 int r = 0, w = 0, fd;
313 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
314 if ((mode & HOSTFS_I(ino)->mode) == mode)
317 mode |= HOSTFS_I(ino)->mode;
320 if (mode & FMODE_READ)
322 if (mode & FMODE_WRITE)
327 name = dentry_name(file->f_path.dentry);
331 fd = open_file(name, r, w, append);
336 mutex_lock(&open_mutex);
337 /* somebody else had handled it first? */
338 if ((mode & HOSTFS_I(ino)->mode) == mode) {
339 mutex_unlock(&open_mutex);
342 if ((mode | HOSTFS_I(ino)->mode) != mode) {
343 mode |= HOSTFS_I(ino)->mode;
344 mutex_unlock(&open_mutex);
348 if (HOSTFS_I(ino)->fd == -1) {
349 HOSTFS_I(ino)->fd = fd;
351 err = replace_file(fd, HOSTFS_I(ino)->fd);
354 mutex_unlock(&open_mutex);
358 HOSTFS_I(ino)->mode = mode;
359 mutex_unlock(&open_mutex);
364 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
366 struct inode *inode = file->f_mapping->host;
369 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
373 mutex_lock(&inode->i_mutex);
374 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
375 mutex_unlock(&inode->i_mutex);
380 static const struct file_operations hostfs_file_fops = {
381 .llseek = generic_file_llseek,
382 .read = do_sync_read,
383 .splice_read = generic_file_splice_read,
384 .aio_read = generic_file_aio_read,
385 .aio_write = generic_file_aio_write,
386 .write = do_sync_write,
387 .mmap = generic_file_mmap,
388 .open = hostfs_file_open,
390 .fsync = hostfs_fsync,
393 static const struct file_operations hostfs_dir_fops = {
394 .llseek = generic_file_llseek,
395 .iterate = hostfs_readdir,
396 .read = generic_read_dir,
399 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
401 struct address_space *mapping = page->mapping;
402 struct inode *inode = mapping->host;
404 unsigned long long base;
405 int count = PAGE_CACHE_SIZE;
406 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
409 if (page->index >= end_index)
410 count = inode->i_size & (PAGE_CACHE_SIZE-1);
413 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
415 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
417 ClearPageUptodate(page);
421 if (base > inode->i_size)
422 inode->i_size = base;
425 ClearPageError(page);
435 int hostfs_readpage(struct file *file, struct page *page)
441 start = (long long) page->index << PAGE_CACHE_SHIFT;
443 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
448 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
450 flush_dcache_page(page);
451 SetPageUptodate(page);
452 if (PageError(page)) ClearPageError(page);
460 int hostfs_write_begin(struct file *file, struct address_space *mapping,
461 loff_t pos, unsigned len, unsigned flags,
462 struct page **pagep, void **fsdata)
464 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
466 *pagep = grab_cache_page_write_begin(mapping, index, flags);
472 int hostfs_write_end(struct file *file, struct address_space *mapping,
473 loff_t pos, unsigned len, unsigned copied,
474 struct page *page, void *fsdata)
476 struct inode *inode = mapping->host;
478 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
482 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
485 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
486 SetPageUptodate(page);
489 * If err > 0, write_file has added err to pos, so we are comparing
490 * i_size against the last byte written.
492 if (err > 0 && (pos > inode->i_size))
495 page_cache_release(page);
500 static const struct address_space_operations hostfs_aops = {
501 .writepage = hostfs_writepage,
502 .readpage = hostfs_readpage,
503 .set_page_dirty = __set_page_dirty_nobuffers,
504 .write_begin = hostfs_write_begin,
505 .write_end = hostfs_write_end,
508 static int read_name(struct inode *ino, char *name)
511 struct hostfs_stat st;
512 int err = stat_file(name, &st, -1);
516 /* Reencode maj and min with the kernel encoding.*/
517 rdev = MKDEV(st.maj, st.min);
519 switch (st.mode & S_IFMT) {
521 ino->i_op = &hostfs_link_iops;
524 ino->i_op = &hostfs_dir_iops;
525 ino->i_fop = &hostfs_dir_fops;
531 init_special_inode(ino, st.mode & S_IFMT, rdev);
532 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;
542 ino->i_mode = st.mode;
543 set_nlink(ino, st.nlink);
544 i_uid_write(ino, st.uid);
545 i_gid_write(ino, st.gid);
546 ino->i_atime = st.atime;
547 ino->i_mtime = st.mtime;
548 ino->i_ctime = st.ctime;
549 ino->i_size = st.size;
550 ino->i_blocks = st.blocks;
554 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
561 inode = hostfs_iget(dir->i_sb);
563 error = PTR_ERR(inode);
568 name = dentry_name(dentry);
572 fd = file_create(name,
573 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
574 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
575 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
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 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
603 inode = hostfs_iget(ino->i_sb);
605 err = PTR_ERR(inode);
610 name = dentry_name(dentry);
614 err = read_name(inode, name);
617 if (err == -ENOENT) {
624 d_add(dentry, inode);
633 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
635 char *from_name, *to_name;
638 if ((from_name = dentry_name(from)) == NULL)
640 to_name = dentry_name(to);
641 if (to_name == NULL) {
642 __putname(from_name);
645 err = link_file(to_name, from_name);
646 __putname(from_name);
651 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
659 if ((file = dentry_name(dentry)) == NULL)
662 err = unlink_file(file);
667 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
672 if ((file = dentry_name(dentry)) == NULL)
674 err = make_symlink(file, to);
679 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
684 if ((file = dentry_name(dentry)) == NULL)
686 err = do_mkdir(file, mode);
691 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
696 if ((file = dentry_name(dentry)) == NULL)
698 err = do_rmdir(file);
703 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
709 inode = hostfs_iget(dir->i_sb);
711 err = PTR_ERR(inode);
716 name = dentry_name(dentry);
720 init_special_inode(inode, mode, dev);
721 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
725 err = read_name(inode, name);
732 d_instantiate(dentry, inode);
743 int hostfs_rename(struct inode *from_ino, struct dentry *from,
744 struct inode *to_ino, struct dentry *to)
746 char *from_name, *to_name;
749 if ((from_name = dentry_name(from)) == NULL)
751 if ((to_name = dentry_name(to)) == NULL) {
752 __putname(from_name);
755 err = rename_file(from_name, to_name);
756 __putname(from_name);
761 int hostfs_permission(struct inode *ino, int desired)
764 int r = 0, w = 0, x = 0, err;
766 if (desired & MAY_NOT_BLOCK)
769 if (desired & MAY_READ) r = 1;
770 if (desired & MAY_WRITE) w = 1;
771 if (desired & MAY_EXEC) x = 1;
772 name = inode_name(ino);
776 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
777 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
780 err = access_file(name, r, w, x);
783 err = generic_permission(ino, desired);
787 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
789 struct inode *inode = dentry->d_inode;
790 struct hostfs_iattr attrs;
794 int fd = HOSTFS_I(inode)->fd;
796 err = inode_change_ok(inode, attr);
801 attr->ia_valid &= ~ATTR_SIZE;
804 if (attr->ia_valid & ATTR_MODE) {
805 attrs.ia_valid |= HOSTFS_ATTR_MODE;
806 attrs.ia_mode = attr->ia_mode;
808 if (attr->ia_valid & ATTR_UID) {
809 attrs.ia_valid |= HOSTFS_ATTR_UID;
810 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
812 if (attr->ia_valid & ATTR_GID) {
813 attrs.ia_valid |= HOSTFS_ATTR_GID;
814 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
816 if (attr->ia_valid & ATTR_SIZE) {
817 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
818 attrs.ia_size = attr->ia_size;
820 if (attr->ia_valid & ATTR_ATIME) {
821 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
822 attrs.ia_atime = attr->ia_atime;
824 if (attr->ia_valid & ATTR_MTIME) {
825 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
826 attrs.ia_mtime = attr->ia_mtime;
828 if (attr->ia_valid & ATTR_CTIME) {
829 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
830 attrs.ia_ctime = attr->ia_ctime;
832 if (attr->ia_valid & ATTR_ATIME_SET) {
833 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
835 if (attr->ia_valid & ATTR_MTIME_SET) {
836 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
838 name = dentry_name(dentry);
841 err = set_attr(name, &attrs, fd);
846 if ((attr->ia_valid & ATTR_SIZE) &&
847 attr->ia_size != i_size_read(inode))
848 truncate_setsize(inode, attr->ia_size);
850 setattr_copy(inode, attr);
851 mark_inode_dirty(inode);
855 static const struct inode_operations hostfs_iops = {
856 .permission = hostfs_permission,
857 .setattr = hostfs_setattr,
860 static const struct inode_operations hostfs_dir_iops = {
861 .create = hostfs_create,
862 .lookup = hostfs_lookup,
864 .unlink = hostfs_unlink,
865 .symlink = hostfs_symlink,
866 .mkdir = hostfs_mkdir,
867 .rmdir = hostfs_rmdir,
868 .mknod = hostfs_mknod,
869 .rename = hostfs_rename,
870 .permission = hostfs_permission,
871 .setattr = hostfs_setattr,
874 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
876 char *link = __getname();
878 char *path = dentry_name(dentry);
881 err = hostfs_do_readlink(path, link, PATH_MAX);
891 link = ERR_PTR(-ENOMEM);
894 nd_set_link(nd, link);
898 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
900 char *s = nd_get_link(nd);
905 static const struct inode_operations hostfs_link_iops = {
906 .readlink = generic_readlink,
907 .follow_link = hostfs_follow_link,
908 .put_link = hostfs_put_link,
911 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
913 struct inode *root_inode;
914 char *host_root_path, *req_root = d;
917 sb->s_blocksize = 1024;
918 sb->s_blocksize_bits = 10;
919 sb->s_magic = HOSTFS_SUPER_MAGIC;
920 sb->s_op = &hostfs_sbops;
921 sb->s_d_op = &hostfs_dentry_ops;
922 sb->s_maxbytes = MAX_LFS_FILESIZE;
924 /* NULL is printed as <NULL> by sprintf: avoid that. */
925 if (req_root == NULL)
929 sb->s_fs_info = host_root_path =
930 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
931 if (host_root_path == NULL)
934 sprintf(host_root_path, "%s/%s", root_ino, req_root);
936 root_inode = new_inode(sb);
940 err = read_name(root_inode, host_root_path);
944 if (S_ISLNK(root_inode->i_mode)) {
945 char *name = follow_link(host_root_path);
949 err = read_name(root_inode, name);
956 sb->s_root = d_make_root(root_inode);
957 if (sb->s_root == NULL)
968 static struct dentry *hostfs_read_sb(struct file_system_type *type,
969 int flags, const char *dev_name,
972 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
975 static void hostfs_kill_sb(struct super_block *s)
981 static struct file_system_type hostfs_type = {
982 .owner = THIS_MODULE,
984 .mount = hostfs_read_sb,
985 .kill_sb = hostfs_kill_sb,
988 MODULE_ALIAS_FS("hostfs");
990 static int __init init_hostfs(void)
992 return register_filesystem(&hostfs_type);
995 static void __exit exit_hostfs(void)
997 unregister_filesystem(&hostfs_type);
1000 module_init(init_hostfs)
1001 module_exit(exit_hostfs)
1002 MODULE_LICENSE("GPL");