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)
143 char *name, *resolved, *end;
151 n = hostfs_do_readlink(link, name, PATH_MAX);
154 else if (n == PATH_MAX) {
162 end = strrchr(link, '/');
167 len = strlen(link) + strlen(name) + 1;
169 resolved = kmalloc(len, GFP_KERNEL);
170 if (resolved == NULL) {
175 sprintf(resolved, "%s%s", link, name);
185 static struct inode *hostfs_iget(struct super_block *sb)
187 struct inode *inode = new_inode(sb);
189 return ERR_PTR(-ENOMEM);
193 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
196 * do_statfs uses struct statfs64 internally, but the linux kernel
197 * struct statfs still has 32-bit versions for most of these fields,
198 * so we convert them here
207 err = do_statfs(dentry->d_sb->s_fs_info,
208 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
209 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
213 sf->f_blocks = f_blocks;
214 sf->f_bfree = f_bfree;
215 sf->f_bavail = f_bavail;
216 sf->f_files = f_files;
217 sf->f_ffree = f_ffree;
218 sf->f_type = HOSTFS_SUPER_MAGIC;
222 static struct inode *hostfs_alloc_inode(struct super_block *sb)
224 struct hostfs_inode_info *hi;
226 hi = kmalloc(sizeof(*hi), GFP_KERNEL);
231 inode_init_once(&hi->vfs_inode);
232 mutex_init(&hi->open_mutex);
233 return &hi->vfs_inode;
236 static void hostfs_evict_inode(struct inode *inode)
238 truncate_inode_pages_final(&inode->i_data);
240 if (HOSTFS_I(inode)->fd != -1) {
241 close_file(&HOSTFS_I(inode)->fd);
242 HOSTFS_I(inode)->fd = -1;
246 static void hostfs_i_callback(struct rcu_head *head)
248 struct inode *inode = container_of(head, struct inode, i_rcu);
249 kfree(HOSTFS_I(inode));
252 static void hostfs_destroy_inode(struct inode *inode)
254 call_rcu(&inode->i_rcu, hostfs_i_callback);
257 static int hostfs_show_options(struct seq_file *seq, struct dentry *root)
259 const char *root_path = root->d_sb->s_fs_info;
260 size_t offset = strlen(root_ino) + 1;
262 if (strlen(root_path) > offset)
263 seq_printf(seq, ",%s", root_path + offset);
266 seq_puts(seq, ",append");
271 static const struct super_operations hostfs_sbops = {
272 .alloc_inode = hostfs_alloc_inode,
273 .destroy_inode = hostfs_destroy_inode,
274 .evict_inode = hostfs_evict_inode,
275 .statfs = hostfs_statfs,
276 .show_options = hostfs_show_options,
279 static int hostfs_readdir(struct file *file, struct dir_context *ctx)
283 unsigned long long next, ino;
287 name = dentry_name(file->f_path.dentry);
290 dir = open_dir(name, &error);
295 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) {
296 if (!dir_emit(ctx, name, len, ino, type))
304 static int hostfs_open(struct inode *ino, struct file *file)
309 int r = 0, w = 0, fd;
311 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
312 if ((mode & HOSTFS_I(ino)->mode) == mode)
315 mode |= HOSTFS_I(ino)->mode;
320 if (mode & FMODE_READ)
322 if (mode & FMODE_WRITE)
325 name = dentry_name(file->f_path.dentry);
329 fd = open_file(name, r, w, append);
334 mutex_lock(&HOSTFS_I(ino)->open_mutex);
335 /* somebody else had handled it first? */
336 if ((mode & HOSTFS_I(ino)->mode) == mode) {
337 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
341 if ((mode | HOSTFS_I(ino)->mode) != mode) {
342 mode |= HOSTFS_I(ino)->mode;
343 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
347 if (HOSTFS_I(ino)->fd == -1) {
348 HOSTFS_I(ino)->fd = fd;
350 err = replace_file(fd, HOSTFS_I(ino)->fd);
353 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
357 HOSTFS_I(ino)->mode = mode;
358 mutex_unlock(&HOSTFS_I(ino)->open_mutex);
363 static int hostfs_file_release(struct inode *inode, struct file *file)
365 filemap_write_and_wait(inode->i_mapping);
370 static int hostfs_fsync(struct file *file, loff_t start, loff_t end,
373 struct inode *inode = file->f_mapping->host;
376 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
380 mutex_lock(&inode->i_mutex);
381 ret = fsync_file(HOSTFS_I(inode)->fd, datasync);
382 mutex_unlock(&inode->i_mutex);
387 static const struct file_operations hostfs_file_fops = {
388 .llseek = generic_file_llseek,
389 .read = new_sync_read,
390 .splice_read = generic_file_splice_read,
391 .read_iter = generic_file_read_iter,
392 .write_iter = generic_file_write_iter,
393 .write = new_sync_write,
394 .mmap = generic_file_mmap,
396 .release = hostfs_file_release,
397 .fsync = hostfs_fsync,
400 static const struct file_operations hostfs_dir_fops = {
401 .llseek = generic_file_llseek,
402 .iterate = hostfs_readdir,
403 .read = generic_read_dir,
405 .fsync = hostfs_fsync,
408 static int hostfs_writepage(struct page *page, struct writeback_control *wbc)
410 struct address_space *mapping = page->mapping;
411 struct inode *inode = mapping->host;
413 unsigned long long base;
414 int count = PAGE_CACHE_SIZE;
415 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
418 if (page->index >= end_index)
419 count = inode->i_size & (PAGE_CACHE_SIZE-1);
422 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
424 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
426 ClearPageUptodate(page);
430 if (base > inode->i_size)
431 inode->i_size = base;
434 ClearPageError(page);
444 static int hostfs_readpage(struct file *file, struct page *page)
450 start = (long long) page->index << PAGE_CACHE_SHIFT;
452 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
454 if (bytes_read < 0) {
459 memset(buffer + bytes_read, 0, PAGE_CACHE_SIZE - bytes_read);
461 flush_dcache_page(page);
462 SetPageUptodate(page);
463 if (PageError(page)) ClearPageError(page);
471 static int hostfs_write_begin(struct file *file, struct address_space *mapping,
472 loff_t pos, unsigned len, unsigned flags,
473 struct page **pagep, void **fsdata)
475 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
477 *pagep = grab_cache_page_write_begin(mapping, index, flags);
483 static int hostfs_write_end(struct file *file, struct address_space *mapping,
484 loff_t pos, unsigned len, unsigned copied,
485 struct page *page, void *fsdata)
487 struct inode *inode = mapping->host;
489 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
493 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
496 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
497 SetPageUptodate(page);
500 * If err > 0, write_file has added err to pos, so we are comparing
501 * i_size against the last byte written.
503 if (err > 0 && (pos > inode->i_size))
506 page_cache_release(page);
511 static const struct address_space_operations hostfs_aops = {
512 .writepage = hostfs_writepage,
513 .readpage = hostfs_readpage,
514 .set_page_dirty = __set_page_dirty_nobuffers,
515 .write_begin = hostfs_write_begin,
516 .write_end = hostfs_write_end,
519 static int read_name(struct inode *ino, char *name)
522 struct hostfs_stat st;
523 int err = stat_file(name, &st, -1);
527 /* Reencode maj and min with the kernel encoding.*/
528 rdev = MKDEV(st.maj, st.min);
530 switch (st.mode & S_IFMT) {
532 ino->i_op = &hostfs_link_iops;
535 ino->i_op = &hostfs_dir_iops;
536 ino->i_fop = &hostfs_dir_fops;
542 init_special_inode(ino, st.mode & S_IFMT, rdev);
543 ino->i_op = &hostfs_iops;
546 ino->i_op = &hostfs_iops;
547 ino->i_fop = &hostfs_file_fops;
548 ino->i_mapping->a_ops = &hostfs_aops;
555 ino->i_mode = st.mode;
556 set_nlink(ino, st.nlink);
557 i_uid_write(ino, st.uid);
558 i_gid_write(ino, st.gid);
559 ino->i_atime = st.atime;
560 ino->i_mtime = st.mtime;
561 ino->i_ctime = st.ctime;
562 ino->i_size = st.size;
563 ino->i_blocks = st.blocks;
567 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
574 inode = hostfs_iget(dir->i_sb);
576 error = PTR_ERR(inode);
581 name = dentry_name(dentry);
585 fd = file_create(name,
586 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
587 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
588 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
592 error = read_name(inode, name);
598 HOSTFS_I(inode)->fd = fd;
599 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
600 d_instantiate(dentry, inode);
609 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
616 inode = hostfs_iget(ino->i_sb);
618 err = PTR_ERR(inode);
623 name = dentry_name(dentry);
627 err = read_name(inode, name);
630 if (err == -ENOENT) {
637 d_add(dentry, inode);
646 static int hostfs_link(struct dentry *to, struct inode *ino,
649 char *from_name, *to_name;
652 if ((from_name = dentry_name(from)) == NULL)
654 to_name = dentry_name(to);
655 if (to_name == NULL) {
656 __putname(from_name);
659 err = link_file(to_name, from_name);
660 __putname(from_name);
665 static int hostfs_unlink(struct inode *ino, struct dentry *dentry)
673 if ((file = dentry_name(dentry)) == NULL)
676 err = unlink_file(file);
681 static int hostfs_symlink(struct inode *ino, struct dentry *dentry,
687 if ((file = dentry_name(dentry)) == NULL)
689 err = make_symlink(file, to);
694 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode)
699 if ((file = dentry_name(dentry)) == NULL)
701 err = do_mkdir(file, mode);
706 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
711 if ((file = dentry_name(dentry)) == NULL)
713 err = do_rmdir(file);
718 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
724 inode = hostfs_iget(dir->i_sb);
726 err = PTR_ERR(inode);
731 name = dentry_name(dentry);
735 init_special_inode(inode, mode, dev);
736 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
740 err = read_name(inode, name);
747 d_instantiate(dentry, inode);
758 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
759 struct inode *new_dir, struct dentry *new_dentry,
762 char *old_name, *new_name;
765 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
768 old_name = dentry_name(old_dentry);
769 if (old_name == NULL)
771 new_name = dentry_name(new_dentry);
772 if (new_name == NULL) {
777 err = rename_file(old_name, new_name);
779 err = rename2_file(old_name, new_name, flags);
786 static int hostfs_permission(struct inode *ino, int desired)
789 int r = 0, w = 0, x = 0, err;
791 if (desired & MAY_NOT_BLOCK)
794 if (desired & MAY_READ) r = 1;
795 if (desired & MAY_WRITE) w = 1;
796 if (desired & MAY_EXEC) x = 1;
797 name = inode_name(ino);
801 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
802 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
805 err = access_file(name, r, w, x);
808 err = generic_permission(ino, desired);
812 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
814 struct inode *inode = dentry->d_inode;
815 struct hostfs_iattr attrs;
819 int fd = HOSTFS_I(inode)->fd;
821 err = inode_change_ok(inode, attr);
826 attr->ia_valid &= ~ATTR_SIZE;
829 if (attr->ia_valid & ATTR_MODE) {
830 attrs.ia_valid |= HOSTFS_ATTR_MODE;
831 attrs.ia_mode = attr->ia_mode;
833 if (attr->ia_valid & ATTR_UID) {
834 attrs.ia_valid |= HOSTFS_ATTR_UID;
835 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid);
837 if (attr->ia_valid & ATTR_GID) {
838 attrs.ia_valid |= HOSTFS_ATTR_GID;
839 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid);
841 if (attr->ia_valid & ATTR_SIZE) {
842 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
843 attrs.ia_size = attr->ia_size;
845 if (attr->ia_valid & ATTR_ATIME) {
846 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
847 attrs.ia_atime = attr->ia_atime;
849 if (attr->ia_valid & ATTR_MTIME) {
850 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
851 attrs.ia_mtime = attr->ia_mtime;
853 if (attr->ia_valid & ATTR_CTIME) {
854 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
855 attrs.ia_ctime = attr->ia_ctime;
857 if (attr->ia_valid & ATTR_ATIME_SET) {
858 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
860 if (attr->ia_valid & ATTR_MTIME_SET) {
861 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
863 name = dentry_name(dentry);
866 err = set_attr(name, &attrs, fd);
871 if ((attr->ia_valid & ATTR_SIZE) &&
872 attr->ia_size != i_size_read(inode))
873 truncate_setsize(inode, attr->ia_size);
875 setattr_copy(inode, attr);
876 mark_inode_dirty(inode);
880 static const struct inode_operations hostfs_iops = {
881 .permission = hostfs_permission,
882 .setattr = hostfs_setattr,
885 static const struct inode_operations hostfs_dir_iops = {
886 .create = hostfs_create,
887 .lookup = hostfs_lookup,
889 .unlink = hostfs_unlink,
890 .symlink = hostfs_symlink,
891 .mkdir = hostfs_mkdir,
892 .rmdir = hostfs_rmdir,
893 .mknod = hostfs_mknod,
894 .rename2 = hostfs_rename2,
895 .permission = hostfs_permission,
896 .setattr = hostfs_setattr,
899 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
901 char *link = __getname();
903 char *path = dentry_name(dentry);
906 err = hostfs_do_readlink(path, link, PATH_MAX);
916 link = ERR_PTR(-ENOMEM);
919 nd_set_link(nd, link);
923 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
925 char *s = nd_get_link(nd);
930 static const struct inode_operations hostfs_link_iops = {
931 .readlink = generic_readlink,
932 .follow_link = hostfs_follow_link,
933 .put_link = hostfs_put_link,
936 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
938 struct inode *root_inode;
939 char *host_root_path, *req_root = d;
942 sb->s_blocksize = 1024;
943 sb->s_blocksize_bits = 10;
944 sb->s_magic = HOSTFS_SUPER_MAGIC;
945 sb->s_op = &hostfs_sbops;
946 sb->s_d_op = &simple_dentry_operations;
947 sb->s_maxbytes = MAX_LFS_FILESIZE;
949 /* NULL is printed as <NULL> by sprintf: avoid that. */
950 if (req_root == NULL)
954 sb->s_fs_info = host_root_path =
955 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
956 if (host_root_path == NULL)
959 sprintf(host_root_path, "%s/%s", root_ino, req_root);
961 root_inode = new_inode(sb);
965 err = read_name(root_inode, host_root_path);
969 if (S_ISLNK(root_inode->i_mode)) {
970 char *name = follow_link(host_root_path);
974 err = read_name(root_inode, name);
981 sb->s_root = d_make_root(root_inode);
982 if (sb->s_root == NULL)
993 static struct dentry *hostfs_read_sb(struct file_system_type *type,
994 int flags, const char *dev_name,
997 return mount_nodev(type, flags, data, hostfs_fill_sb_common);
1000 static void hostfs_kill_sb(struct super_block *s)
1003 kfree(s->s_fs_info);
1006 static struct file_system_type hostfs_type = {
1007 .owner = THIS_MODULE,
1009 .mount = hostfs_read_sb,
1010 .kill_sb = hostfs_kill_sb,
1013 MODULE_ALIAS_FS("hostfs");
1015 static int __init init_hostfs(void)
1017 return register_filesystem(&hostfs_type);
1020 static void __exit exit_hostfs(void)
1022 unregister_filesystem(&hostfs_type);
1025 module_init(init_hostfs)
1026 module_exit(exit_hostfs)
1027 MODULE_LICENSE("GPL");