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(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(dentry, name, PATH_MAX);
99 spin_unlock(&dcache_lock);
101 root = dentry->d_sb->s_fs_info;
107 strlcpy(name, root, PATH_MAX);
108 if (len > p - name) {
112 if (p > name + len) {
113 char *s = name + len;
114 while ((*s++ = *p++) != '\0')
120 static char *dentry_name(struct dentry *dentry)
122 char *name = __getname();
126 spin_lock(&dcache_lock);
127 return __dentry_name(dentry, name); /* will unlock */
130 static char *inode_name(struct inode *ino)
132 struct dentry *dentry;
133 char *name = __getname();
137 spin_lock(&dcache_lock);
138 if (list_empty(&ino->i_dentry)) {
139 spin_unlock(&dcache_lock);
143 dentry = list_first_entry(&ino->i_dentry, struct dentry, d_alias);
144 return __dentry_name(dentry, name); /* will unlock */
147 static char *follow_link(char *link)
150 char *name, *resolved, *end;
155 name = kmalloc(len, GFP_KERNEL);
159 n = hostfs_do_readlink(link, name, len);
171 end = strrchr(link, '/');
176 len = strlen(link) + strlen(name) + 1;
178 resolved = kmalloc(len, GFP_KERNEL);
179 if (resolved == NULL) {
184 sprintf(resolved, "%s%s", link, name);
195 static struct inode *hostfs_iget(struct super_block *sb)
197 struct inode *inode = new_inode(sb);
199 return ERR_PTR(-ENOMEM);
203 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
206 * do_statfs uses struct statfs64 internally, but the linux kernel
207 * struct statfs still has 32-bit versions for most of these fields,
208 * so we convert them here
217 err = do_statfs(dentry->d_sb->s_fs_info,
218 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
219 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
220 &sf->f_namelen, sf->f_spare);
223 sf->f_blocks = f_blocks;
224 sf->f_bfree = f_bfree;
225 sf->f_bavail = f_bavail;
226 sf->f_files = f_files;
227 sf->f_ffree = f_ffree;
228 sf->f_type = HOSTFS_SUPER_MAGIC;
232 static struct inode *hostfs_alloc_inode(struct super_block *sb)
234 struct hostfs_inode_info *hi;
236 hi = kzalloc(sizeof(*hi), GFP_KERNEL);
240 inode_init_once(&hi->vfs_inode);
241 return &hi->vfs_inode;
244 static void hostfs_evict_inode(struct inode *inode)
246 truncate_inode_pages(&inode->i_data, 0);
247 end_writeback(inode);
248 if (HOSTFS_I(inode)->fd != -1) {
249 close_file(&HOSTFS_I(inode)->fd);
250 HOSTFS_I(inode)->fd = -1;
254 static void hostfs_destroy_inode(struct inode *inode)
256 kfree(HOSTFS_I(inode));
259 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
261 const char *root_path = vfs->mnt_sb->s_fs_info;
262 size_t offset = strlen(root_ino) + 1;
264 if (strlen(root_path) > offset)
265 seq_printf(seq, ",%s", root_path + offset);
270 static const struct super_operations hostfs_sbops = {
271 .alloc_inode = hostfs_alloc_inode,
272 .destroy_inode = hostfs_destroy_inode,
273 .evict_inode = hostfs_evict_inode,
274 .statfs = hostfs_statfs,
275 .show_options = hostfs_show_options,
278 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
282 unsigned long long next, ino;
285 name = dentry_name(file->f_path.dentry);
288 dir = open_dir(name, &error);
293 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
294 error = (*filldir)(ent, name, len, file->f_pos,
303 int hostfs_file_open(struct inode *ino, struct file *file)
305 static DEFINE_MUTEX(open_mutex);
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;
318 if (mode & FMODE_READ)
320 if (mode & FMODE_WRITE)
325 name = dentry_name(file->f_path.dentry);
329 fd = open_file(name, r, w, append);
334 mutex_lock(&open_mutex);
335 /* somebody else had handled it first? */
336 if ((mode & HOSTFS_I(ino)->mode) == mode) {
337 mutex_unlock(&open_mutex);
340 if ((mode | HOSTFS_I(ino)->mode) != mode) {
341 mode |= HOSTFS_I(ino)->mode;
342 mutex_unlock(&open_mutex);
346 if (HOSTFS_I(ino)->fd == -1) {
347 HOSTFS_I(ino)->fd = fd;
349 err = replace_file(fd, HOSTFS_I(ino)->fd);
352 mutex_unlock(&open_mutex);
356 HOSTFS_I(ino)->mode = mode;
357 mutex_unlock(&open_mutex);
362 int hostfs_fsync(struct file *file, int datasync)
364 return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync);
367 static const struct file_operations hostfs_file_fops = {
368 .llseek = generic_file_llseek,
369 .read = do_sync_read,
370 .splice_read = generic_file_splice_read,
371 .aio_read = generic_file_aio_read,
372 .aio_write = generic_file_aio_write,
373 .write = do_sync_write,
374 .mmap = generic_file_mmap,
375 .open = hostfs_file_open,
377 .fsync = hostfs_fsync,
380 static const struct file_operations hostfs_dir_fops = {
381 .llseek = generic_file_llseek,
382 .readdir = hostfs_readdir,
383 .read = generic_read_dir,
386 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
388 struct address_space *mapping = page->mapping;
389 struct inode *inode = mapping->host;
391 unsigned long long base;
392 int count = PAGE_CACHE_SIZE;
393 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
396 if (page->index >= end_index)
397 count = inode->i_size & (PAGE_CACHE_SIZE-1);
400 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
402 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
404 ClearPageUptodate(page);
408 if (base > inode->i_size)
409 inode->i_size = base;
412 ClearPageError(page);
422 int hostfs_readpage(struct file *file, struct page *page)
428 start = (long long) page->index << PAGE_CACHE_SHIFT;
430 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
435 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
437 flush_dcache_page(page);
438 SetPageUptodate(page);
439 if (PageError(page)) ClearPageError(page);
447 int hostfs_write_begin(struct file *file, struct address_space *mapping,
448 loff_t pos, unsigned len, unsigned flags,
449 struct page **pagep, void **fsdata)
451 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
453 *pagep = grab_cache_page_write_begin(mapping, index, flags);
459 int hostfs_write_end(struct file *file, struct address_space *mapping,
460 loff_t pos, unsigned len, unsigned copied,
461 struct page *page, void *fsdata)
463 struct inode *inode = mapping->host;
465 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
469 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
472 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
473 SetPageUptodate(page);
476 * If err > 0, write_file has added err to pos, so we are comparing
477 * i_size against the last byte written.
479 if (err > 0 && (pos > inode->i_size))
482 page_cache_release(page);
487 static const struct address_space_operations hostfs_aops = {
488 .writepage = hostfs_writepage,
489 .readpage = hostfs_readpage,
490 .set_page_dirty = __set_page_dirty_nobuffers,
491 .write_begin = hostfs_write_begin,
492 .write_end = hostfs_write_end,
495 static int read_name(struct inode *ino, char *name)
498 struct hostfs_stat st;
499 int err = stat_file(name, &st, -1);
503 /* Reencode maj and min with the kernel encoding.*/
504 rdev = MKDEV(st.maj, st.min);
506 switch (st.mode & S_IFMT) {
508 ino->i_op = &hostfs_link_iops;
511 ino->i_op = &hostfs_dir_iops;
512 ino->i_fop = &hostfs_dir_fops;
518 init_special_inode(ino, st.mode & S_IFMT, rdev);
519 ino->i_op = &hostfs_iops;
523 ino->i_op = &hostfs_iops;
524 ino->i_fop = &hostfs_file_fops;
525 ino->i_mapping->a_ops = &hostfs_aops;
529 ino->i_mode = st.mode;
530 ino->i_nlink = st.nlink;
533 ino->i_atime = st.atime;
534 ino->i_mtime = st.mtime;
535 ino->i_ctime = st.ctime;
536 ino->i_size = st.size;
537 ino->i_blocks = st.blocks;
541 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
542 struct nameidata *nd)
548 inode = hostfs_iget(dir->i_sb);
550 error = PTR_ERR(inode);
555 name = dentry_name(dentry);
559 fd = file_create(name,
560 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
561 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
562 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
566 error = read_name(inode, name);
572 HOSTFS_I(inode)->fd = fd;
573 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
574 d_instantiate(dentry, inode);
583 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
584 struct nameidata *nd)
590 inode = hostfs_iget(ino->i_sb);
592 err = PTR_ERR(inode);
597 name = dentry_name(dentry);
601 err = read_name(inode, name);
604 if (err == -ENOENT) {
611 d_add(dentry, inode);
612 dentry->d_op = &hostfs_dentry_ops;
621 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
623 char *from_name, *to_name;
626 if ((from_name = dentry_name(from)) == NULL)
628 to_name = dentry_name(to);
629 if (to_name == NULL) {
630 __putname(from_name);
633 err = link_file(to_name, from_name);
634 __putname(from_name);
639 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
647 if ((file = dentry_name(dentry)) == NULL)
650 err = unlink_file(file);
655 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
660 if ((file = dentry_name(dentry)) == NULL)
662 err = make_symlink(file, to);
667 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
672 if ((file = dentry_name(dentry)) == NULL)
674 err = do_mkdir(file, mode);
679 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
684 if ((file = dentry_name(dentry)) == NULL)
686 err = do_rmdir(file);
691 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
697 inode = hostfs_iget(dir->i_sb);
699 err = PTR_ERR(inode);
704 name = dentry_name(dentry);
708 init_special_inode(inode, mode, dev);
709 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
713 err = read_name(inode, name);
720 d_instantiate(dentry, inode);
731 int hostfs_rename(struct inode *from_ino, struct dentry *from,
732 struct inode *to_ino, struct dentry *to)
734 char *from_name, *to_name;
737 if ((from_name = dentry_name(from)) == NULL)
739 if ((to_name = dentry_name(to)) == NULL) {
740 __putname(from_name);
743 err = rename_file(from_name, to_name);
744 __putname(from_name);
749 int hostfs_permission(struct inode *ino, int desired)
752 int r = 0, w = 0, x = 0, err;
754 if (desired & MAY_READ) r = 1;
755 if (desired & MAY_WRITE) w = 1;
756 if (desired & MAY_EXEC) x = 1;
757 name = inode_name(ino);
761 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
762 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
765 err = access_file(name, r, w, x);
768 err = generic_permission(ino, desired, NULL);
772 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
774 struct inode *inode = dentry->d_inode;
775 struct hostfs_iattr attrs;
779 int fd = HOSTFS_I(inode)->fd;
781 err = inode_change_ok(inode, attr);
786 attr->ia_valid &= ~ATTR_SIZE;
789 if (attr->ia_valid & ATTR_MODE) {
790 attrs.ia_valid |= HOSTFS_ATTR_MODE;
791 attrs.ia_mode = attr->ia_mode;
793 if (attr->ia_valid & ATTR_UID) {
794 attrs.ia_valid |= HOSTFS_ATTR_UID;
795 attrs.ia_uid = attr->ia_uid;
797 if (attr->ia_valid & ATTR_GID) {
798 attrs.ia_valid |= HOSTFS_ATTR_GID;
799 attrs.ia_gid = attr->ia_gid;
801 if (attr->ia_valid & ATTR_SIZE) {
802 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
803 attrs.ia_size = attr->ia_size;
805 if (attr->ia_valid & ATTR_ATIME) {
806 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
807 attrs.ia_atime = attr->ia_atime;
809 if (attr->ia_valid & ATTR_MTIME) {
810 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
811 attrs.ia_mtime = attr->ia_mtime;
813 if (attr->ia_valid & ATTR_CTIME) {
814 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
815 attrs.ia_ctime = attr->ia_ctime;
817 if (attr->ia_valid & ATTR_ATIME_SET) {
818 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
820 if (attr->ia_valid & ATTR_MTIME_SET) {
821 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
823 name = dentry_name(dentry);
826 err = set_attr(name, &attrs, fd);
831 if ((attr->ia_valid & ATTR_SIZE) &&
832 attr->ia_size != i_size_read(inode)) {
835 error = vmtruncate(inode, attr->ia_size);
840 setattr_copy(inode, attr);
841 mark_inode_dirty(inode);
845 static const struct inode_operations hostfs_iops = {
846 .create = hostfs_create,
848 .unlink = hostfs_unlink,
849 .symlink = hostfs_symlink,
850 .mkdir = hostfs_mkdir,
851 .rmdir = hostfs_rmdir,
852 .mknod = hostfs_mknod,
853 .rename = hostfs_rename,
854 .permission = hostfs_permission,
855 .setattr = hostfs_setattr,
858 static const struct inode_operations hostfs_dir_iops = {
859 .create = hostfs_create,
860 .lookup = hostfs_lookup,
862 .unlink = hostfs_unlink,
863 .symlink = hostfs_symlink,
864 .mkdir = hostfs_mkdir,
865 .rmdir = hostfs_rmdir,
866 .mknod = hostfs_mknod,
867 .rename = hostfs_rename,
868 .permission = hostfs_permission,
869 .setattr = hostfs_setattr,
872 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd)
874 char *link = __getname();
876 char *path = dentry_name(dentry);
879 err = hostfs_do_readlink(path, link, PATH_MAX);
889 link = ERR_PTR(-ENOMEM);
892 nd_set_link(nd, link);
896 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
898 char *s = nd_get_link(nd);
903 static const struct inode_operations hostfs_link_iops = {
904 .readlink = generic_readlink,
905 .follow_link = hostfs_follow_link,
906 .put_link = hostfs_put_link,
909 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
911 struct inode *root_inode;
912 char *host_root_path, *req_root = d;
915 sb->s_blocksize = 1024;
916 sb->s_blocksize_bits = 10;
917 sb->s_magic = HOSTFS_SUPER_MAGIC;
918 sb->s_op = &hostfs_sbops;
919 sb->s_maxbytes = MAX_LFS_FILESIZE;
921 /* NULL is printed as <NULL> by sprintf: avoid that. */
922 if (req_root == NULL)
926 sb->s_fs_info = host_root_path =
927 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
928 if (host_root_path == NULL)
931 sprintf(host_root_path, "%s/%s", root_ino, req_root);
933 root_inode = new_inode(sb);
937 err = read_name(root_inode, host_root_path);
941 if (S_ISLNK(root_inode->i_mode)) {
942 char *name = follow_link(host_root_path);
946 err = read_name(root_inode, name);
953 sb->s_root = d_alloc_root(root_inode);
954 if (sb->s_root == NULL)
965 static int hostfs_read_sb(struct file_system_type *type,
966 int flags, const char *dev_name,
967 void *data, struct vfsmount *mnt)
969 return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
972 static void hostfs_kill_sb(struct super_block *s)
978 static struct file_system_type hostfs_type = {
979 .owner = THIS_MODULE,
981 .get_sb = hostfs_read_sb,
982 .kill_sb = hostfs_kill_sb,
986 static int __init init_hostfs(void)
988 return register_filesystem(&hostfs_type);
991 static void __exit exit_hostfs(void)
993 unregister_filesystem(&hostfs_type);
996 module_init(init_hostfs)
997 module_exit(exit_hostfs)
998 MODULE_LICENSE("GPL");