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/module.h>
12 #include <linux/pagemap.h>
13 #include <linux/statfs.h>
14 #include <linux/slab.h>
15 #include <linux/seq_file.h>
16 #include <linux/mount.h>
17 #include <linux/namei.h>
22 struct hostfs_inode_info {
25 struct inode vfs_inode;
28 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
30 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
33 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
35 static int hostfs_d_delete(const struct dentry *dentry)
40 static const struct dentry_operations hostfs_dentry_ops = {
41 .d_delete = hostfs_d_delete,
44 /* Changed in hostfs_args before the kernel starts running */
45 static char *root_ino = "";
46 static int append = 0;
48 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
50 static const struct inode_operations hostfs_iops;
51 static const struct inode_operations hostfs_dir_iops;
52 static const struct inode_operations hostfs_link_iops;
55 static int __init hostfs_args(char *options, int *add)
59 ptr = strchr(options, ',');
67 ptr = strchr(options, ',');
70 if (*options != '\0') {
71 if (!strcmp(options, "append"))
73 else printf("hostfs_args - unsupported option - %s\n",
81 __uml_setup("hostfs=", hostfs_args,
82 "hostfs=<root dir>,<flags>,...\n"
83 " This is used to set hostfs parameters. The root directory argument\n"
84 " is used to confine all hostfs mounts to within the specified directory\n"
85 " tree on the host. If this isn't specified, then a user inside UML can\n"
86 " mount anything on the host that's accessible to the user that's running\n"
88 " The only flag currently supported is 'append', which specifies that all\n"
89 " files opened by hostfs will be opened in append mode.\n\n"
93 static char *__dentry_name(struct dentry *dentry, char *name)
95 char *p = dentry_path_raw(dentry, name, PATH_MAX);
99 root = dentry->d_sb->s_fs_info;
105 strlcpy(name, root, PATH_MAX);
106 if (len > p - name) {
110 if (p > name + len) {
111 char *s = name + len;
112 while ((*s++ = *p++) != '\0')
118 static char *dentry_name(struct dentry *dentry)
120 char *name = __getname();
124 return __dentry_name(dentry, name); /* will unlock */
127 static char *inode_name(struct inode *ino)
129 struct dentry *dentry;
132 dentry = d_find_alias(ino);
136 name = dentry_name(dentry);
143 static char *follow_link(char *link)
146 char *name, *resolved, *end;
151 name = kmalloc(len, GFP_KERNEL);
155 n = hostfs_do_readlink(link, name, len);
167 end = strrchr(link, '/');
172 len = strlen(link) + strlen(name) + 1;
174 resolved = kmalloc(len, GFP_KERNEL);
175 if (resolved == NULL) {
180 sprintf(resolved, "%s%s", link, name);
191 static struct inode *hostfs_iget(struct super_block *sb)
193 struct inode *inode = new_inode(sb);
195 return ERR_PTR(-ENOMEM);
199 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
202 * do_statfs uses struct statfs64 internally, but the linux kernel
203 * struct statfs still has 32-bit versions for most of these fields,
204 * so we convert them here
213 err = do_statfs(dentry->d_sb->s_fs_info,
214 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
215 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
219 sf->f_blocks = f_blocks;
220 sf->f_bfree = f_bfree;
221 sf->f_bavail = f_bavail;
222 sf->f_files = f_files;
223 sf->f_ffree = f_ffree;
224 sf->f_type = HOSTFS_SUPER_MAGIC;
228 static struct inode *hostfs_alloc_inode(struct super_block *sb)
230 struct hostfs_inode_info *hi;
232 hi = kzalloc(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);
243 end_writeback(inode);
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 INIT_LIST_HEAD(&inode->i_dentry);
254 kfree(HOSTFS_I(inode));
257 static void hostfs_destroy_inode(struct inode *inode)
259 call_rcu(&inode->i_rcu, hostfs_i_callback);
262 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
264 const char *root_path = vfs->mnt_sb->s_fs_info;
265 size_t offset = strlen(root_ino) + 1;
267 if (strlen(root_path) > offset)
268 seq_printf(seq, ",%s", root_path + offset);
273 static const struct super_operations hostfs_sbops = {
274 .alloc_inode = hostfs_alloc_inode,
275 .destroy_inode = hostfs_destroy_inode,
276 .evict_inode = hostfs_evict_inode,
277 .statfs = hostfs_statfs,
278 .show_options = hostfs_show_options,
281 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
285 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)) != NULL) {
297 error = (*filldir)(ent, name, len, file->f_pos,
306 int hostfs_file_open(struct inode *ino, struct file *file)
308 static DEFINE_MUTEX(open_mutex);
312 int r = 0, w = 0, fd;
314 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
315 if ((mode & HOSTFS_I(ino)->mode) == mode)
318 mode |= HOSTFS_I(ino)->mode;
321 if (mode & FMODE_READ)
323 if (mode & FMODE_WRITE)
328 name = dentry_name(file->f_path.dentry);
332 fd = open_file(name, r, w, append);
337 mutex_lock(&open_mutex);
338 /* somebody else had handled it first? */
339 if ((mode & HOSTFS_I(ino)->mode) == mode) {
340 mutex_unlock(&open_mutex);
343 if ((mode | HOSTFS_I(ino)->mode) != mode) {
344 mode |= HOSTFS_I(ino)->mode;
345 mutex_unlock(&open_mutex);
349 if (HOSTFS_I(ino)->fd == -1) {
350 HOSTFS_I(ino)->fd = fd;
352 err = replace_file(fd, HOSTFS_I(ino)->fd);
355 mutex_unlock(&open_mutex);
359 HOSTFS_I(ino)->mode = mode;
360 mutex_unlock(&open_mutex);
365 int hostfs_fsync(struct file *file, int datasync)
367 return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync);
370 static const struct file_operations hostfs_file_fops = {
371 .llseek = generic_file_llseek,
372 .read = do_sync_read,
373 .splice_read = generic_file_splice_read,
374 .aio_read = generic_file_aio_read,
375 .aio_write = generic_file_aio_write,
376 .write = do_sync_write,
377 .mmap = generic_file_mmap,
378 .open = hostfs_file_open,
380 .fsync = hostfs_fsync,
383 static const struct file_operations hostfs_dir_fops = {
384 .llseek = generic_file_llseek,
385 .readdir = hostfs_readdir,
386 .read = generic_read_dir,
389 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
391 struct address_space *mapping = page->mapping;
392 struct inode *inode = mapping->host;
394 unsigned long long base;
395 int count = PAGE_CACHE_SIZE;
396 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
399 if (page->index >= end_index)
400 count = inode->i_size & (PAGE_CACHE_SIZE-1);
403 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
405 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
407 ClearPageUptodate(page);
411 if (base > inode->i_size)
412 inode->i_size = base;
415 ClearPageError(page);
425 int hostfs_readpage(struct file *file, struct page *page)
431 start = (long long) page->index << PAGE_CACHE_SHIFT;
433 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
438 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
440 flush_dcache_page(page);
441 SetPageUptodate(page);
442 if (PageError(page)) ClearPageError(page);
450 int hostfs_write_begin(struct file *file, struct address_space *mapping,
451 loff_t pos, unsigned len, unsigned flags,
452 struct page **pagep, void **fsdata)
454 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
456 *pagep = grab_cache_page_write_begin(mapping, index, flags);
462 int hostfs_write_end(struct file *file, struct address_space *mapping,
463 loff_t pos, unsigned len, unsigned copied,
464 struct page *page, void *fsdata)
466 struct inode *inode = mapping->host;
468 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
472 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
475 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
476 SetPageUptodate(page);
479 * If err > 0, write_file has added err to pos, so we are comparing
480 * i_size against the last byte written.
482 if (err > 0 && (pos > inode->i_size))
485 page_cache_release(page);
490 static const struct address_space_operations hostfs_aops = {
491 .writepage = hostfs_writepage,
492 .readpage = hostfs_readpage,
493 .set_page_dirty = __set_page_dirty_nobuffers,
494 .write_begin = hostfs_write_begin,
495 .write_end = hostfs_write_end,
498 static int read_name(struct inode *ino, char *name)
501 struct hostfs_stat st;
502 int err = stat_file(name, &st, -1);
506 /* Reencode maj and min with the kernel encoding.*/
507 rdev = MKDEV(st.maj, st.min);
509 switch (st.mode & S_IFMT) {
511 ino->i_op = &hostfs_link_iops;
514 ino->i_op = &hostfs_dir_iops;
515 ino->i_fop = &hostfs_dir_fops;
521 init_special_inode(ino, st.mode & S_IFMT, rdev);
522 ino->i_op = &hostfs_iops;
526 ino->i_op = &hostfs_iops;
527 ino->i_fop = &hostfs_file_fops;
528 ino->i_mapping->a_ops = &hostfs_aops;
532 ino->i_mode = st.mode;
533 ino->i_nlink = st.nlink;
536 ino->i_atime = st.atime;
537 ino->i_mtime = st.mtime;
538 ino->i_ctime = st.ctime;
539 ino->i_size = st.size;
540 ino->i_blocks = st.blocks;
544 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
545 struct nameidata *nd)
551 inode = hostfs_iget(dir->i_sb);
553 error = PTR_ERR(inode);
558 name = dentry_name(dentry);
562 fd = file_create(name,
563 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
564 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
565 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
569 error = read_name(inode, name);
575 HOSTFS_I(inode)->fd = fd;
576 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
577 d_instantiate(dentry, inode);
586 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
587 struct nameidata *nd)
593 inode = hostfs_iget(ino->i_sb);
595 err = PTR_ERR(inode);
600 name = dentry_name(dentry);
604 err = read_name(inode, name);
607 if (err == -ENOENT) {
614 d_add(dentry, inode);
615 dentry->d_op = &hostfs_dentry_ops;
624 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
626 char *from_name, *to_name;
629 if ((from_name = dentry_name(from)) == NULL)
631 to_name = dentry_name(to);
632 if (to_name == NULL) {
633 __putname(from_name);
636 err = link_file(to_name, from_name);
637 __putname(from_name);
642 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
650 if ((file = dentry_name(dentry)) == NULL)
653 err = unlink_file(file);
658 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
663 if ((file = dentry_name(dentry)) == NULL)
665 err = make_symlink(file, to);
670 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
675 if ((file = dentry_name(dentry)) == NULL)
677 err = do_mkdir(file, mode);
682 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
687 if ((file = dentry_name(dentry)) == NULL)
689 err = do_rmdir(file);
694 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
700 inode = hostfs_iget(dir->i_sb);
702 err = PTR_ERR(inode);
707 name = dentry_name(dentry);
711 init_special_inode(inode, mode, dev);
712 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
716 err = read_name(inode, name);
723 d_instantiate(dentry, inode);
734 int hostfs_rename(struct inode *from_ino, struct dentry *from,
735 struct inode *to_ino, struct dentry *to)
737 char *from_name, *to_name;
740 if ((from_name = dentry_name(from)) == NULL)
742 if ((to_name = dentry_name(to)) == NULL) {
743 __putname(from_name);
746 err = rename_file(from_name, to_name);
747 __putname(from_name);
752 int hostfs_permission(struct inode *ino, int desired)
755 int r = 0, w = 0, x = 0, err;
757 if (desired & MAY_READ) r = 1;
758 if (desired & MAY_WRITE) w = 1;
759 if (desired & MAY_EXEC) x = 1;
760 name = inode_name(ino);
764 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
765 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
768 err = access_file(name, r, w, x);
771 err = generic_permission(ino, desired, NULL);
775 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
777 struct inode *inode = dentry->d_inode;
778 struct hostfs_iattr attrs;
782 int fd = HOSTFS_I(inode)->fd;
784 err = inode_change_ok(inode, attr);
789 attr->ia_valid &= ~ATTR_SIZE;
792 if (attr->ia_valid & ATTR_MODE) {
793 attrs.ia_valid |= HOSTFS_ATTR_MODE;
794 attrs.ia_mode = attr->ia_mode;
796 if (attr->ia_valid & ATTR_UID) {
797 attrs.ia_valid |= HOSTFS_ATTR_UID;
798 attrs.ia_uid = attr->ia_uid;
800 if (attr->ia_valid & ATTR_GID) {
801 attrs.ia_valid |= HOSTFS_ATTR_GID;
802 attrs.ia_gid = attr->ia_gid;
804 if (attr->ia_valid & ATTR_SIZE) {
805 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
806 attrs.ia_size = attr->ia_size;
808 if (attr->ia_valid & ATTR_ATIME) {
809 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
810 attrs.ia_atime = attr->ia_atime;
812 if (attr->ia_valid & ATTR_MTIME) {
813 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
814 attrs.ia_mtime = attr->ia_mtime;
816 if (attr->ia_valid & ATTR_CTIME) {
817 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
818 attrs.ia_ctime = attr->ia_ctime;
820 if (attr->ia_valid & ATTR_ATIME_SET) {
821 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
823 if (attr->ia_valid & ATTR_MTIME_SET) {
824 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
826 name = dentry_name(dentry);
829 err = set_attr(name, &attrs, fd);
834 if ((attr->ia_valid & ATTR_SIZE) &&
835 attr->ia_size != i_size_read(inode)) {
838 error = vmtruncate(inode, attr->ia_size);
843 setattr_copy(inode, attr);
844 mark_inode_dirty(inode);
848 static const struct inode_operations hostfs_iops = {
849 .create = hostfs_create,
851 .unlink = hostfs_unlink,
852 .symlink = hostfs_symlink,
853 .mkdir = hostfs_mkdir,
854 .rmdir = hostfs_rmdir,
855 .mknod = hostfs_mknod,
856 .rename = hostfs_rename,
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_rename,
871 .permission = hostfs_permission,
872 .setattr = hostfs_setattr,
875 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
877 char *link = __getname();
879 char *path = dentry_name(dentry);
882 err = hostfs_do_readlink(path, link, PATH_MAX);
892 link = ERR_PTR(-ENOMEM);
895 nd_set_link(nd, link);
899 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
901 char *s = nd_get_link(nd);
906 static const struct inode_operations hostfs_link_iops = {
907 .readlink = generic_readlink,
908 .follow_link = hostfs_follow_link,
909 .put_link = hostfs_put_link,
912 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
914 struct inode *root_inode;
915 char *host_root_path, *req_root = d;
918 sb->s_blocksize = 1024;
919 sb->s_blocksize_bits = 10;
920 sb->s_magic = HOSTFS_SUPER_MAGIC;
921 sb->s_op = &hostfs_sbops;
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_alloc_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,
989 static int __init init_hostfs(void)
991 return register_filesystem(&hostfs_type);
994 static void __exit exit_hostfs(void)
996 unregister_filesystem(&hostfs_type);
999 module_init(init_hostfs)
1000 module_exit(exit_hostfs)
1001 MODULE_LICENSE("GPL");