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>
21 struct hostfs_inode_info {
24 struct inode vfs_inode;
27 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
29 return list_entry(inode, struct hostfs_inode_info, vfs_inode);
32 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
34 static int hostfs_d_delete(struct dentry *dentry)
39 static const struct dentry_operations hostfs_dentry_ops = {
40 .d_delete = hostfs_d_delete,
43 /* Changed in hostfs_args before the kernel starts running */
44 static char *root_ino = "";
45 static int append = 0;
47 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
49 static const struct inode_operations hostfs_iops;
50 static const struct inode_operations hostfs_dir_iops;
51 static const struct address_space_operations hostfs_link_aops;
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, int extra)
94 struct dentry *parent;
100 while (parent->d_parent != parent) {
101 len += parent->d_name.len + 1;
102 parent = parent->d_parent;
105 root = parent->d_sb->s_fs_info;
107 name = kmalloc(len + extra + 1, GFP_KERNEL);
113 while (parent->d_parent != parent) {
114 len -= parent->d_name.len + 1;
116 strncpy(&name[len + 1], parent->d_name.name,
118 parent = parent->d_parent;
120 strncpy(name, root, strlen(root));
124 static char *inode_name(struct inode *ino, int extra)
126 struct dentry *dentry;
128 dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
129 return dentry_name(dentry, extra);
132 static int read_name(struct inode *ino, char *name)
135 * The non-int inode fields are copied into ints by stat_file and
136 * then copied into the inode because passing the actual pointers
137 * in and having them treated as int * breaks on big-endian machines
140 int i_mode, i_nlink, i_blksize;
141 unsigned long long i_size;
142 unsigned long long i_ino;
143 unsigned long long i_blocks;
145 err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
146 &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
147 &ino->i_ctime, &i_blksize, &i_blocks, -1);
152 ino->i_mode = i_mode;
153 ino->i_nlink = i_nlink;
154 ino->i_size = i_size;
155 ino->i_blocks = i_blocks;
159 static char *follow_link(char *link)
162 char *name, *resolved, *end;
167 name = kmalloc(len, GFP_KERNEL);
171 n = hostfs_do_readlink(link, name, len);
183 end = strrchr(link, '/');
188 len = strlen(link) + strlen(name) + 1;
190 resolved = kmalloc(len, GFP_KERNEL);
191 if (resolved == NULL) {
196 sprintf(resolved, "%s%s", link, name);
207 static int hostfs_read_inode(struct inode *ino)
213 * Unfortunately, we are called from iget() when we don't have a dentry
216 if (list_empty(&ino->i_dentry))
220 name = inode_name(ino, 0);
224 if (file_type(name, NULL, NULL) == OS_TYPE_SYMLINK) {
225 name = follow_link(name);
232 err = read_name(ino, name);
238 static struct inode *hostfs_iget(struct super_block *sb)
243 inode = new_inode(sb);
245 return ERR_PTR(-ENOMEM);
246 ret = hostfs_read_inode(inode);
254 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
257 * do_statfs uses struct statfs64 internally, but the linux kernel
258 * struct statfs still has 32-bit versions for most of these fields,
259 * so we convert them here
268 err = do_statfs(dentry->d_sb->s_fs_info,
269 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
270 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
271 &sf->f_namelen, sf->f_spare);
274 sf->f_blocks = f_blocks;
275 sf->f_bfree = f_bfree;
276 sf->f_bavail = f_bavail;
277 sf->f_files = f_files;
278 sf->f_ffree = f_ffree;
279 sf->f_type = HOSTFS_SUPER_MAGIC;
283 static struct inode *hostfs_alloc_inode(struct super_block *sb)
285 struct hostfs_inode_info *hi;
287 hi = kzalloc(sizeof(*hi), GFP_KERNEL);
291 inode_init_once(&hi->vfs_inode);
292 return &hi->vfs_inode;
295 static void hostfs_evict_inode(struct inode *inode)
297 truncate_inode_pages(&inode->i_data, 0);
298 end_writeback(inode);
299 if (HOSTFS_I(inode)->fd != -1) {
300 close_file(&HOSTFS_I(inode)->fd);
301 HOSTFS_I(inode)->fd = -1;
305 static void hostfs_destroy_inode(struct inode *inode)
307 kfree(HOSTFS_I(inode));
310 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
312 const char *root_path = vfs->mnt_sb->s_fs_info;
313 size_t offset = strlen(root_ino) + 1;
315 if (strlen(root_path) > offset)
316 seq_printf(seq, ",%s", root_path + offset);
321 static const struct super_operations hostfs_sbops = {
322 .alloc_inode = hostfs_alloc_inode,
323 .destroy_inode = hostfs_destroy_inode,
324 .evict_inode = hostfs_evict_inode,
325 .statfs = hostfs_statfs,
326 .show_options = hostfs_show_options,
329 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
333 unsigned long long next, ino;
336 name = dentry_name(file->f_path.dentry, 0);
339 dir = open_dir(name, &error);
344 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
345 error = (*filldir)(ent, name, len, file->f_pos,
354 int hostfs_file_open(struct inode *ino, struct file *file)
358 int r = 0, w = 0, fd;
360 mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
361 if ((mode & HOSTFS_I(ino)->mode) == mode)
365 * The file may already have been opened, but with the wrong access,
366 * so this resets things and reopens the file with the new access.
368 if (HOSTFS_I(ino)->fd != -1) {
369 close_file(&HOSTFS_I(ino)->fd);
370 HOSTFS_I(ino)->fd = -1;
373 HOSTFS_I(ino)->mode |= mode;
374 if (HOSTFS_I(ino)->mode & FMODE_READ)
376 if (HOSTFS_I(ino)->mode & FMODE_WRITE)
381 name = dentry_name(file->f_path.dentry, 0);
385 fd = open_file(name, r, w, append);
389 FILE_HOSTFS_I(file)->fd = fd;
394 int hostfs_fsync(struct file *file, int datasync)
396 return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync);
399 static const struct file_operations hostfs_file_fops = {
400 .llseek = generic_file_llseek,
401 .read = do_sync_read,
402 .splice_read = generic_file_splice_read,
403 .aio_read = generic_file_aio_read,
404 .aio_write = generic_file_aio_write,
405 .write = do_sync_write,
406 .mmap = generic_file_mmap,
407 .open = hostfs_file_open,
409 .fsync = hostfs_fsync,
412 static const struct file_operations hostfs_dir_fops = {
413 .llseek = generic_file_llseek,
414 .readdir = hostfs_readdir,
415 .read = generic_read_dir,
418 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
420 struct address_space *mapping = page->mapping;
421 struct inode *inode = mapping->host;
423 unsigned long long base;
424 int count = PAGE_CACHE_SIZE;
425 int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
428 if (page->index >= end_index)
429 count = inode->i_size & (PAGE_CACHE_SIZE-1);
432 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
434 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
436 ClearPageUptodate(page);
440 if (base > inode->i_size)
441 inode->i_size = base;
444 ClearPageError(page);
454 int hostfs_readpage(struct file *file, struct page *page)
460 start = (long long) page->index << PAGE_CACHE_SHIFT;
462 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
467 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
469 flush_dcache_page(page);
470 SetPageUptodate(page);
471 if (PageError(page)) ClearPageError(page);
479 int hostfs_write_begin(struct file *file, struct address_space *mapping,
480 loff_t pos, unsigned len, unsigned flags,
481 struct page **pagep, void **fsdata)
483 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
485 *pagep = grab_cache_page_write_begin(mapping, index, flags);
491 int hostfs_write_end(struct file *file, struct address_space *mapping,
492 loff_t pos, unsigned len, unsigned copied,
493 struct page *page, void *fsdata)
495 struct inode *inode = mapping->host;
497 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
501 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
504 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
505 SetPageUptodate(page);
508 * If err > 0, write_file has added err to pos, so we are comparing
509 * i_size against the last byte written.
511 if (err > 0 && (pos > inode->i_size))
514 page_cache_release(page);
519 static const struct address_space_operations hostfs_aops = {
520 .writepage = hostfs_writepage,
521 .readpage = hostfs_readpage,
522 .set_page_dirty = __set_page_dirty_nobuffers,
523 .write_begin = hostfs_write_begin,
524 .write_end = hostfs_write_end,
527 static int init_inode(struct inode *inode, struct dentry *dentry)
530 int type, err = -ENOMEM;
535 name = dentry_name(dentry, 0);
538 type = file_type(name, &maj, &min);
539 /* Reencode maj and min with the kernel encoding.*/
540 rdev = MKDEV(maj, min);
543 else type = OS_TYPE_DIR;
546 if (type == OS_TYPE_SYMLINK)
547 inode->i_op = &page_symlink_inode_operations;
548 else if (type == OS_TYPE_DIR)
549 inode->i_op = &hostfs_dir_iops;
550 else inode->i_op = &hostfs_iops;
552 if (type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
553 else inode->i_fop = &hostfs_file_fops;
555 if (type == OS_TYPE_SYMLINK)
556 inode->i_mapping->a_ops = &hostfs_link_aops;
557 else inode->i_mapping->a_ops = &hostfs_aops;
560 case OS_TYPE_CHARDEV:
561 init_special_inode(inode, S_IFCHR, rdev);
563 case OS_TYPE_BLOCKDEV:
564 init_special_inode(inode, S_IFBLK, rdev);
567 init_special_inode(inode, S_IFIFO, 0);
570 init_special_inode(inode, S_IFSOCK, 0);
577 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
578 struct nameidata *nd)
584 inode = hostfs_iget(dir->i_sb);
586 error = PTR_ERR(inode);
590 error = init_inode(inode, dentry);
595 name = dentry_name(dentry, 0);
599 fd = file_create(name,
600 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
601 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
602 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
605 else error = read_name(inode, name);
611 HOSTFS_I(inode)->fd = fd;
612 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
613 d_instantiate(dentry, inode);
622 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
623 struct nameidata *nd)
629 inode = hostfs_iget(ino->i_sb);
631 err = PTR_ERR(inode);
635 err = init_inode(inode, dentry);
640 name = dentry_name(dentry, 0);
644 err = read_name(inode, name);
646 if (err == -ENOENT) {
653 d_add(dentry, inode);
654 dentry->d_op = &hostfs_dentry_ops;
663 static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
668 file = inode_name(ino, dentry->d_name.len + 1);
673 strncat(file, dentry->d_name.name, dentry->d_name.len);
674 file[len + dentry->d_name.len] = '\0';
678 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
680 char *from_name, *to_name;
683 if ((from_name = inode_dentry_name(ino, from)) == NULL)
685 to_name = dentry_name(to, 0);
686 if (to_name == NULL) {
690 err = link_file(to_name, from_name);
696 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
701 if ((file = inode_dentry_name(ino, dentry)) == NULL)
706 err = unlink_file(file);
711 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
716 if ((file = inode_dentry_name(ino, dentry)) == NULL)
718 err = make_symlink(file, to);
723 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
728 if ((file = inode_dentry_name(ino, dentry)) == NULL)
730 err = do_mkdir(file, mode);
735 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
740 if ((file = inode_dentry_name(ino, dentry)) == NULL)
742 err = do_rmdir(file);
747 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
753 inode = hostfs_iget(dir->i_sb);
755 err = PTR_ERR(inode);
759 err = init_inode(inode, dentry);
764 name = dentry_name(dentry, 0);
768 init_special_inode(inode, mode, dev);
769 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
773 err = read_name(inode, name);
778 d_instantiate(dentry, inode);
789 int hostfs_rename(struct inode *from_ino, struct dentry *from,
790 struct inode *to_ino, struct dentry *to)
792 char *from_name, *to_name;
795 if ((from_name = inode_dentry_name(from_ino, from)) == NULL)
797 if ((to_name = inode_dentry_name(to_ino, to)) == NULL) {
801 err = rename_file(from_name, to_name);
807 int hostfs_permission(struct inode *ino, int desired)
810 int r = 0, w = 0, x = 0, err;
812 if (desired & MAY_READ) r = 1;
813 if (desired & MAY_WRITE) w = 1;
814 if (desired & MAY_EXEC) x = 1;
815 name = inode_name(ino, 0);
819 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
820 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
823 err = access_file(name, r, w, x);
826 err = generic_permission(ino, desired, NULL);
830 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
832 struct inode *inode = dentry->d_inode;
833 struct hostfs_iattr attrs;
837 int fd = HOSTFS_I(inode)->fd;
839 err = inode_change_ok(inode, attr);
844 attr->ia_valid &= ~ATTR_SIZE;
847 if (attr->ia_valid & ATTR_MODE) {
848 attrs.ia_valid |= HOSTFS_ATTR_MODE;
849 attrs.ia_mode = attr->ia_mode;
851 if (attr->ia_valid & ATTR_UID) {
852 attrs.ia_valid |= HOSTFS_ATTR_UID;
853 attrs.ia_uid = attr->ia_uid;
855 if (attr->ia_valid & ATTR_GID) {
856 attrs.ia_valid |= HOSTFS_ATTR_GID;
857 attrs.ia_gid = attr->ia_gid;
859 if (attr->ia_valid & ATTR_SIZE) {
860 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
861 attrs.ia_size = attr->ia_size;
863 if (attr->ia_valid & ATTR_ATIME) {
864 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
865 attrs.ia_atime = attr->ia_atime;
867 if (attr->ia_valid & ATTR_MTIME) {
868 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
869 attrs.ia_mtime = attr->ia_mtime;
871 if (attr->ia_valid & ATTR_CTIME) {
872 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
873 attrs.ia_ctime = attr->ia_ctime;
875 if (attr->ia_valid & ATTR_ATIME_SET) {
876 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
878 if (attr->ia_valid & ATTR_MTIME_SET) {
879 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
881 name = dentry_name(dentry, 0);
884 err = set_attr(name, &attrs, fd);
889 if ((attr->ia_valid & ATTR_SIZE) &&
890 attr->ia_size != i_size_read(inode)) {
893 error = vmtruncate(inode, attr->ia_size);
898 setattr_copy(inode, attr);
899 mark_inode_dirty(inode);
903 static const struct inode_operations hostfs_iops = {
904 .create = hostfs_create,
906 .unlink = hostfs_unlink,
907 .symlink = hostfs_symlink,
908 .mkdir = hostfs_mkdir,
909 .rmdir = hostfs_rmdir,
910 .mknod = hostfs_mknod,
911 .rename = hostfs_rename,
912 .permission = hostfs_permission,
913 .setattr = hostfs_setattr,
916 static const struct inode_operations hostfs_dir_iops = {
917 .create = hostfs_create,
918 .lookup = hostfs_lookup,
920 .unlink = hostfs_unlink,
921 .symlink = hostfs_symlink,
922 .mkdir = hostfs_mkdir,
923 .rmdir = hostfs_rmdir,
924 .mknod = hostfs_mknod,
925 .rename = hostfs_rename,
926 .permission = hostfs_permission,
927 .setattr = hostfs_setattr,
930 int hostfs_link_readpage(struct file *file, struct page *page)
936 name = inode_name(page->mapping->host, 0);
939 err = hostfs_do_readlink(name, buffer, PAGE_CACHE_SIZE);
941 if (err == PAGE_CACHE_SIZE)
944 flush_dcache_page(page);
945 SetPageUptodate(page);
946 if (PageError(page)) ClearPageError(page);
954 static const struct address_space_operations hostfs_link_aops = {
955 .readpage = hostfs_link_readpage,
958 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
960 struct inode *root_inode;
961 char *host_root_path, *req_root = d;
964 sb->s_blocksize = 1024;
965 sb->s_blocksize_bits = 10;
966 sb->s_magic = HOSTFS_SUPER_MAGIC;
967 sb->s_op = &hostfs_sbops;
968 sb->s_maxbytes = MAX_LFS_FILESIZE;
970 /* NULL is printed as <NULL> by sprintf: avoid that. */
971 if (req_root == NULL)
975 sb->s_fs_info = host_root_path =
976 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL);
977 if (host_root_path == NULL)
980 sprintf(host_root_path, "%s/%s", root_ino, req_root);
982 root_inode = hostfs_iget(sb);
983 if (IS_ERR(root_inode)) {
984 err = PTR_ERR(root_inode);
988 err = init_inode(root_inode, NULL);
993 sb->s_root = d_alloc_root(root_inode);
994 if (sb->s_root == NULL)
997 err = hostfs_read_inode(root_inode);
999 /* No iput in this case because the dput does that for us */
1013 static int hostfs_read_sb(struct file_system_type *type,
1014 int flags, const char *dev_name,
1015 void *data, struct vfsmount *mnt)
1017 return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
1020 static void hostfs_kill_sb(struct super_block *s)
1023 kfree(s->s_fs_info);
1026 static struct file_system_type hostfs_type = {
1027 .owner = THIS_MODULE,
1029 .get_sb = hostfs_read_sb,
1030 .kill_sb = hostfs_kill_sb,
1034 static int __init init_hostfs(void)
1036 return register_filesystem(&hostfs_type);
1039 static void __exit exit_hostfs(void)
1041 unregister_filesystem(&hostfs_type);
1044 module_init(init_hostfs)
1045 module_exit(exit_hostfs)
1046 MODULE_LICENSE("GPL");