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 /* Changed in hostfs_args before the kernel starts running */
37 static char *root_ino = "";
38 static int append = 0;
40 static const struct inode_operations hostfs_iops;
41 static const struct inode_operations hostfs_dir_iops;
42 static const struct inode_operations hostfs_link_iops;
45 static int __init hostfs_args(char *options, int *add)
49 ptr = strchr(options, ',');
57 ptr = strchr(options, ',');
60 if (*options != '\0') {
61 if (!strcmp(options, "append"))
63 else printf("hostfs_args - unsupported option - %s\n",
71 __uml_setup("hostfs=", hostfs_args,
72 "hostfs=<root dir>,<flags>,...\n"
73 " This is used to set hostfs parameters. The root directory argument\n"
74 " is used to confine all hostfs mounts to within the specified directory\n"
75 " tree on the host. If this isn't specified, then a user inside UML can\n"
76 " mount anything on the host that's accessible to the user that's running\n"
78 " The only flag currently supported is 'append', which specifies that all\n"
79 " files opened by hostfs will be opened in append mode.\n\n"
83 static char *__dentry_name(struct dentry *dentry, char *name)
85 char *p = dentry_path_raw(dentry, name, PATH_MAX);
89 root = dentry->d_sb->s_fs_info;
95 strlcpy(name, root, PATH_MAX);
100 if (p > name + len) {
101 char *s = name + len;
102 while ((*s++ = *p++) != '\0')
108 static char *dentry_name(struct dentry *dentry)
110 char *name = __getname();
114 return __dentry_name(dentry, name);
117 static char *inode_name(struct inode *ino)
119 struct dentry *dentry;
122 dentry = d_find_alias(ino);
126 name = dentry_name(dentry);
133 static char *follow_link(char *link)
136 char *name, *resolved, *end;
141 name = kmalloc(len, GFP_KERNEL);
145 n = hostfs_do_readlink(link, name, len);
157 end = strrchr(link, '/');
162 len = strlen(link) + strlen(name) + 1;
164 resolved = kmalloc(len, GFP_KERNEL);
165 if (resolved == NULL) {
170 sprintf(resolved, "%s%s", link, name);
181 static struct inode *hostfs_iget(struct super_block *sb)
183 struct inode *inode = new_inode(sb);
185 return ERR_PTR(-ENOMEM);
189 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
192 * do_statfs uses struct statfs64 internally, but the linux kernel
193 * struct statfs still has 32-bit versions for most of these fields,
194 * so we convert them here
203 err = do_statfs(dentry->d_sb->s_fs_info,
204 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
205 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
209 sf->f_blocks = f_blocks;
210 sf->f_bfree = f_bfree;
211 sf->f_bavail = f_bavail;
212 sf->f_files = f_files;
213 sf->f_ffree = f_ffree;
214 sf->f_type = HOSTFS_SUPER_MAGIC;
218 static struct inode *hostfs_alloc_inode(struct super_block *sb)
220 struct hostfs_inode_info *hi;
222 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
227 inode_init_once(&hi->vfs_inode);
228 return &hi->vfs_inode;
231 static void hostfs_evict_inode(struct inode *inode)
233 truncate_inode_pages_final(&inode->i_data);
235 if (HOSTFS_I(inode)->fd != -1) {
236 close_file(&HOSTFS_I(inode)->fd);
237 HOSTFS_I(inode)->fd = -1;
241 static void hostfs_i_callback(struct rcu_head *head)
243 struct inode *inode = container_of(head, struct inode, i_rcu);
244 kfree(HOSTFS_I(inode));
247 static void hostfs_destroy_inode(struct inode *inode)
249 call_rcu(&inode->i_rcu, hostfs_i_callback);
252 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
254 const char *root_path = root->d_sb->s_fs_info;
255 size_t offset = strlen(root_ino) + 1;
257 if (strlen(root_path) > offset)
258 seq_printf(seq, ",%s", root_path + offset);
263 static const struct super_operations hostfs_sbops = {
264 .alloc_inode = hostfs_alloc_inode,
265 .destroy_inode = hostfs_destroy_inode,
266 .evict_inode = hostfs_evict_inode,
267 .statfs = hostfs_statfs,
268 .show_options = hostfs_show_options,
271 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
275 unsigned long long next, ino;
279 name = dentry_name(file->f_path.dentry);
282 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_file_open(struct inode *ino, struct file *file)
298 static DEFINE_MUTEX(open_mutex);
302 int r = 0, w = 0, fd;
304 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
305 if ((mode & HOSTFS_I(ino)->mode) == mode)
308 mode |= HOSTFS_I(ino)->mode;
311 if (mode & FMODE_READ)
313 if (mode & FMODE_WRITE)
318 name = dentry_name(file->f_path.dentry);
322 fd = open_file(name, r, w, append);
327 mutex_lock(&open_mutex);
328 /* somebody else had handled it first? */
329 if ((mode & HOSTFS_I(ino)->mode) == mode) {
330 mutex_unlock(&open_mutex);
333 if ((mode | HOSTFS_I(ino)->mode) != mode) {
334 mode |= HOSTFS_I(ino)->mode;
335 mutex_unlock(&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(&open_mutex);
349 HOSTFS_I(ino)->mode = mode;
350 mutex_unlock(&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 = filemap_write_and_wait_range(inode->i_mapping, start, end);
372 mutex_lock(&inode->i_mutex);
373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
374 mutex_unlock(&inode->i_mutex);
379 static const struct file_operations hostfs_file_fops = {
380 .llseek = generic_file_llseek,
381 .read = new_sync_read,
382 .splice_read = generic_file_splice_read,
383 .read_iter = generic_file_read_iter,
384 .write_iter = generic_file_write_iter,
385 .write = new_sync_write,
386 .mmap = generic_file_mmap,
387 .open = hostfs_file_open,
388 .release = hostfs_file_release,
389 .fsync = hostfs_fsync,
392 static const struct file_operations hostfs_dir_fops = {
393 .llseek = generic_file_llseek,
394 .iterate = hostfs_readdir,
395 .read = generic_read_dir,
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 unsigned long long base;
404 int count = PAGE_CACHE_SIZE;
405 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
408 if (page->index >= end_index)
409 count = inode->i_size & (PAGE_CACHE_SIZE-1);
412 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
414 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
416 ClearPageUptodate(page);
420 if (base > inode->i_size)
421 inode->i_size = base;
424 ClearPageError(page);
434 static int hostfs_readpage(struct file *file, struct page *page)
440 start = (long long) page->index << PAGE_CACHE_SHIFT;
442 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
447 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
449 flush_dcache_page(page);
450 SetPageUptodate(page);
451 if (PageError(page)) ClearPageError(page);
459 static int hostfs_write_begin(struct file *file, struct address_space *mapping,
460 loff_t pos, unsigned len, unsigned flags,
461 struct page **pagep, void **fsdata)
463 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
465 *pagep = grab_cache_page_write_begin(mapping, index, flags);
471 static int hostfs_write_end(struct file *file, struct address_space *mapping,
472 loff_t pos, unsigned len, unsigned copied,
473 struct page *page, void *fsdata)
475 struct inode *inode = mapping->host;
477 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
481 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
484 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
485 SetPageUptodate(page);
488 * If err > 0, write_file has added err to pos, so we are comparing
489 * i_size against the last byte written.
491 if (err > 0 && (pos > inode->i_size))
494 page_cache_release(page);
499 static const struct address_space_operations hostfs_aops = {
500 .writepage = hostfs_writepage,
501 .readpage = hostfs_readpage,
502 .set_page_dirty = __set_page_dirty_nobuffers,
503 .write_begin = hostfs_write_begin,
504 .write_end = hostfs_write_end,
507 static int read_name(struct inode *ino, char *name)
510 struct hostfs_stat st;
511 int err = stat_file(name, &st, -1);
515 /* Reencode maj and min with the kernel encoding.*/
516 rdev = MKDEV(st.maj, st.min);
518 switch (st.mode & S_IFMT) {
520 ino->i_op = &hostfs_link_iops;
523 ino->i_op = &hostfs_dir_iops;
524 ino->i_fop = &hostfs_dir_fops;
530 init_special_inode(ino, st.mode & S_IFMT, rdev);
531 ino->i_op = &hostfs_iops;
535 ino->i_op = &hostfs_iops;
536 ino->i_fop = &hostfs_file_fops;
537 ino->i_mapping->a_ops = &hostfs_aops;
541 ino->i_mode = st.mode;
542 set_nlink(ino, st.nlink);
543 i_uid_write(ino, st.uid);
544 i_gid_write(ino, st.gid);
545 ino->i_atime = st.atime;
546 ino->i_mtime = st.mtime;
547 ino->i_ctime = st.ctime;
548 ino->i_size = st.size;
549 ino->i_blocks = st.blocks;
553 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
560 inode = hostfs_iget(dir->i_sb);
562 error = PTR_ERR(inode);
567 name = dentry_name(dentry);
571 fd = file_create(name,
572 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
573 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
574 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
578 error = read_name(inode, name);
584 HOSTFS_I(inode)->fd = fd;
585 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
586 d_instantiate(dentry, inode);
595 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
602 inode = hostfs_iget(ino->i_sb);
604 err = PTR_ERR(inode);
609 name = dentry_name(dentry);
613 err = read_name(inode, name);
616 if (err == -ENOENT) {
623 d_add(dentry, inode);
632 static int hostfs_link(struct dentry *to, struct inode *ino,
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 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
659 if ((file = dentry_name(dentry)) == NULL)
662 err = unlink_file(file);
667 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
673 if ((file = dentry_name(dentry)) == NULL)
675 err = make_symlink(file, to);
680 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
685 if ((file = dentry_name(dentry)) == NULL)
687 err = do_mkdir(file, mode);
692 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
697 if ((file = dentry_name(dentry)) == NULL)
699 err = do_rmdir(file);
704 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
710 inode = hostfs_iget(dir->i_sb);
712 err = PTR_ERR(inode);
717 name = dentry_name(dentry);
721 init_special_inode(inode, mode, dev);
722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
726 err = read_name(inode, name);
733 d_instantiate(dentry, inode);
744 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
745 struct inode *new_dir, struct dentry *new_dentry,
748 char *old_name, *new_name;
751 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
754 old_name = dentry_name(old_dentry);
755 if (old_name == NULL)
757 new_name = dentry_name(new_dentry);
758 if (new_name == NULL) {
763 err = rename_file(old_name, new_name);
765 err = rename2_file(old_name, new_name, flags);
772 static int hostfs_permission(struct inode *ino, int desired)
775 int r = 0, w = 0, x = 0, err;
777 if (desired & MAY_NOT_BLOCK)
780 if (desired & MAY_READ) r = 1;
781 if (desired & MAY_WRITE) w = 1;
782 if (desired & MAY_EXEC) x = 1;
783 name = inode_name(ino);
787 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
788 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
791 err = access_file(name, r, w, x);
794 err = generic_permission(ino, desired);
798 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
800 struct inode *inode = dentry->d_inode;
801 struct hostfs_iattr attrs;
805 int fd = HOSTFS_I(inode)->fd;
807 err = inode_change_ok(inode, attr);
812 attr->ia_valid &= ~ATTR_SIZE;
815 if (attr->ia_valid & ATTR_MODE) {
816 attrs.ia_valid |= HOSTFS_ATTR_MODE;
817 attrs.ia_mode = attr->ia_mode;
819 if (attr->ia_valid & ATTR_UID) {
820 attrs.ia_valid |= HOSTFS_ATTR_UID;
821 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
823 if (attr->ia_valid & ATTR_GID) {
824 attrs.ia_valid |= HOSTFS_ATTR_GID;
825 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
827 if (attr->ia_valid & ATTR_SIZE) {
828 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
829 attrs.ia_size = attr->ia_size;
831 if (attr->ia_valid & ATTR_ATIME) {
832 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
833 attrs.ia_atime = attr->ia_atime;
835 if (attr->ia_valid & ATTR_MTIME) {
836 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
837 attrs.ia_mtime = attr->ia_mtime;
839 if (attr->ia_valid & ATTR_CTIME) {
840 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
841 attrs.ia_ctime = attr->ia_ctime;
843 if (attr->ia_valid & ATTR_ATIME_SET) {
844 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
846 if (attr->ia_valid & ATTR_MTIME_SET) {
847 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
849 name = dentry_name(dentry);
852 err = set_attr(name, &attrs, fd);
857 if ((attr->ia_valid & ATTR_SIZE) &&
858 attr->ia_size != i_size_read(inode))
859 truncate_setsize(inode, attr->ia_size);
861 setattr_copy(inode, attr);
862 mark_inode_dirty(inode);
866 static const struct inode_operations hostfs_iops = {
867 .permission = hostfs_permission,
868 .setattr = hostfs_setattr,
871 static const struct inode_operations hostfs_dir_iops = {
872 .create = hostfs_create,
873 .lookup = hostfs_lookup,
875 .unlink = hostfs_unlink,
876 .symlink = hostfs_symlink,
877 .mkdir = hostfs_mkdir,
878 .rmdir = hostfs_rmdir,
879 .mknod = hostfs_mknod,
880 .rename2 = hostfs_rename2,
881 .permission = hostfs_permission,
882 .setattr = hostfs_setattr,
885 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
887 char *link = __getname();
889 char *path = dentry_name(dentry);
892 err = hostfs_do_readlink(path, link, PATH_MAX);
902 link = ERR_PTR(-ENOMEM);
905 nd_set_link(nd, link);
909 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
911 char *s = nd_get_link(nd);
916 static const struct inode_operations hostfs_link_iops = {
917 .readlink = generic_readlink,
918 .follow_link = hostfs_follow_link,
919 .put_link = hostfs_put_link,
922 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
924 struct inode *root_inode;
925 char *host_root_path, *req_root = d;
928 sb->s_blocksize = 1024;
929 sb->s_blocksize_bits = 10;
930 sb->s_magic = HOSTFS_SUPER_MAGIC;
931 sb->s_op = &hostfs_sbops;
932 sb->s_d_op = &simple_dentry_operations;
933 sb->s_maxbytes = MAX_LFS_FILESIZE;
935 /* NULL is printed as <NULL> by sprintf: avoid that. */
936 if (req_root == NULL)
940 sb->s_fs_info = host_root_path =
941 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
942 if (host_root_path == NULL)
945 sprintf(host_root_path, "%s/%s", root_ino, req_root);
947 root_inode = new_inode(sb);
951 err = read_name(root_inode, host_root_path);
955 if (S_ISLNK(root_inode->i_mode)) {
956 char *name = follow_link(host_root_path);
960 err = read_name(root_inode, name);
967 sb->s_root = d_make_root(root_inode);
968 if (sb->s_root == NULL)
979 static struct dentry *hostfs_read_sb(struct file_system_type *type,
980 int flags, const char *dev_name,
983 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
986 static void hostfs_kill_sb(struct super_block *s)
992 static struct file_system_type hostfs_type = {
993 .owner = THIS_MODULE,
995 .mount = hostfs_read_sb,
996 .kill_sb = hostfs_kill_sb,
999 MODULE_ALIAS_FS("hostfs");
1001 static int __init init_hostfs(void)
1003 return register_filesystem(&hostfs_type);
1006 static void __exit exit_hostfs(void)
1008 unregister_filesystem(&hostfs_type);
1011 module_init(init_hostfs)
1012 module_exit(exit_hostfs)
1013 MODULE_LICENSE("GPL");