android_kernel_xiaomi_sm8350/fs/hostfs/hostfs_kern.c
Badari Pulavarty 543ade1fc9 [PATCH] Streamline generic_file_* interfaces and filemap cleanups
This patch cleans up generic_file_*_read/write() interfaces.  Christoph
Hellwig gave me the idea for this clean ups.

In a nutshell, all filesystems should set .aio_read/.aio_write methods and use
do_sync_read/ do_sync_write() as their .read/.write methods.  This allows us
to cleanup all variants of generic_file_* routines.

Final available interfaces:

generic_file_aio_read() - read handler
generic_file_aio_write() - write handler
generic_file_aio_write_nolock() - no lock write handler

__generic_file_aio_write_nolock() - internal worker routine

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:28 -07:00

1032 lines
22 KiB
C

/*
* Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*
* Ported the filesystem routines to 2.5.
* 2003-02-10 Petr Baudis <pasky@ucw.cz>
*/
#include <linux/stddef.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/blkdev.h>
#include <linux/list.h>
#include <linux/statfs.h>
#include <linux/kdev_t.h>
#include <asm/uaccess.h>
#include "hostfs.h"
#include "kern_util.h"
#include "kern.h"
#include "user_util.h"
#include "init.h"
struct hostfs_inode_info {
char *host_filename;
int fd;
int mode;
struct inode vfs_inode;
};
static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
{
return(list_entry(inode, struct hostfs_inode_info, vfs_inode));
}
#define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_dentry->d_inode)
int hostfs_d_delete(struct dentry *dentry)
{
return(1);
}
struct dentry_operations hostfs_dentry_ops = {
.d_delete = hostfs_d_delete,
};
/* Changed in hostfs_args before the kernel starts running */
static char *root_ino = "/";
static int append = 0;
#define HOSTFS_SUPER_MAGIC 0x00c0ffee
static struct inode_operations hostfs_iops;
static struct inode_operations hostfs_dir_iops;
static const struct address_space_operations hostfs_link_aops;
#ifndef MODULE
static int __init hostfs_args(char *options, int *add)
{
char *ptr;
ptr = strchr(options, ',');
if(ptr != NULL)
*ptr++ = '\0';
if(*options != '\0')
root_ino = options;
options = ptr;
while(options){
ptr = strchr(options, ',');
if(ptr != NULL)
*ptr++ = '\0';
if(*options != '\0'){
if(!strcmp(options, "append"))
append = 1;
else printf("hostfs_args - unsupported option - %s\n",
options);
}
options = ptr;
}
return(0);
}
__uml_setup("hostfs=", hostfs_args,
"hostfs=<root dir>,<flags>,...\n"
" This is used to set hostfs parameters. The root directory argument\n"
" is used to confine all hostfs mounts to within the specified directory\n"
" tree on the host. If this isn't specified, then a user inside UML can\n"
" mount anything on the host that's accessible to the user that's running\n"
" it.\n"
" The only flag currently supported is 'append', which specifies that all\n"
" files opened by hostfs will be opened in append mode.\n\n"
);
#endif
static char *dentry_name(struct dentry *dentry, int extra)
{
struct dentry *parent;
char *root, *name;
int len;
len = 0;
parent = dentry;
while(parent->d_parent != parent){
len += parent->d_name.len + 1;
parent = parent->d_parent;
}
root = HOSTFS_I(parent->d_inode)->host_filename;
len += strlen(root);
name = kmalloc(len + extra + 1, GFP_KERNEL);
if(name == NULL) return(NULL);
name[len] = '\0';
parent = dentry;
while(parent->d_parent != parent){
len -= parent->d_name.len + 1;
name[len] = '/';
strncpy(&name[len + 1], parent->d_name.name,
parent->d_name.len);
parent = parent->d_parent;
}
strncpy(name, root, strlen(root));
return(name);
}
static char *inode_name(struct inode *ino, int extra)
{
struct dentry *dentry;
dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
return(dentry_name(dentry, extra));
}
static int read_name(struct inode *ino, char *name)
{
/* The non-int inode fields are copied into ints by stat_file and
* then copied into the inode because passing the actual pointers
* in and having them treated as int * breaks on big-endian machines
*/
int err;
int i_mode, i_nlink, i_blksize;
unsigned long long i_size;
unsigned long long i_ino;
unsigned long long i_blocks;
err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
&ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
&ino->i_ctime, &i_blksize, &i_blocks);
if(err)
return(err);
ino->i_ino = i_ino;
ino->i_mode = i_mode;
ino->i_nlink = i_nlink;
ino->i_size = i_size;
ino->i_blocks = i_blocks;
return(0);
}
static char *follow_link(char *link)
{
int len, n;
char *name, *resolved, *end;
len = 64;
while(1){
n = -ENOMEM;
name = kmalloc(len, GFP_KERNEL);
if(name == NULL)
goto out;
n = do_readlink(link, name, len);
if(n < len)
break;
len *= 2;
kfree(name);
}
if(n < 0)
goto out_free;
if(*name == '/')
return(name);
end = strrchr(link, '/');
if(end == NULL)
return(name);
*(end + 1) = '\0';
len = strlen(link) + strlen(name) + 1;
resolved = kmalloc(len, GFP_KERNEL);
if(resolved == NULL){
n = -ENOMEM;
goto out_free;
}
sprintf(resolved, "%s%s", link, name);
kfree(name);
kfree(link);
return(resolved);
out_free:
kfree(name);
out:
return(ERR_PTR(n));
}
static int read_inode(struct inode *ino)
{
char *name;
int err = 0;
/* Unfortunately, we are called from iget() when we don't have a dentry
* allocated yet.
*/
if(list_empty(&ino->i_dentry))
goto out;
err = -ENOMEM;
name = inode_name(ino, 0);
if(name == NULL)
goto out;
if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){
name = follow_link(name);
if(IS_ERR(name)){
err = PTR_ERR(name);
goto out;
}
}
err = read_name(ino, name);
kfree(name);
out:
return(err);
}
int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
{
/* do_statfs uses struct statfs64 internally, but the linux kernel
* struct statfs still has 32-bit versions for most of these fields,
* so we convert them here
*/
int err;
long long f_blocks;
long long f_bfree;
long long f_bavail;
long long f_files;
long long f_ffree;
err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
&sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
&f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
&sf->f_namelen, sf->f_spare);
if(err) return(err);
sf->f_blocks = f_blocks;
sf->f_bfree = f_bfree;
sf->f_bavail = f_bavail;
sf->f_files = f_files;
sf->f_ffree = f_ffree;
sf->f_type = HOSTFS_SUPER_MAGIC;
return(0);
}
static struct inode *hostfs_alloc_inode(struct super_block *sb)
{
struct hostfs_inode_info *hi;
hi = kmalloc(sizeof(*hi), GFP_KERNEL);
if(hi == NULL)
return(NULL);
*hi = ((struct hostfs_inode_info) { .host_filename = NULL,
.fd = -1,
.mode = 0 });
inode_init_once(&hi->vfs_inode);
return(&hi->vfs_inode);
}
static void hostfs_delete_inode(struct inode *inode)
{
truncate_inode_pages(&inode->i_data, 0);
if(HOSTFS_I(inode)->fd != -1) {
close_file(&HOSTFS_I(inode)->fd);
HOSTFS_I(inode)->fd = -1;
}
clear_inode(inode);
}
static void hostfs_destroy_inode(struct inode *inode)
{
kfree(HOSTFS_I(inode)->host_filename);
/*XXX: This should not happen, probably. The check is here for
* additional safety.*/
if(HOSTFS_I(inode)->fd != -1) {
close_file(&HOSTFS_I(inode)->fd);
printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
}
kfree(HOSTFS_I(inode));
}
static void hostfs_read_inode(struct inode *inode)
{
read_inode(inode);
}
static struct super_operations hostfs_sbops = {
.alloc_inode = hostfs_alloc_inode,
.drop_inode = generic_delete_inode,
.delete_inode = hostfs_delete_inode,
.destroy_inode = hostfs_destroy_inode,
.read_inode = hostfs_read_inode,
.statfs = hostfs_statfs,
};
int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
{
void *dir;
char *name;
unsigned long long next, ino;
int error, len;
name = dentry_name(file->f_dentry, 0);
if(name == NULL) return(-ENOMEM);
dir = open_dir(name, &error);
kfree(name);
if(dir == NULL) return(-error);
next = file->f_pos;
while((name = read_dir(dir, &next, &ino, &len)) != NULL){
error = (*filldir)(ent, name, len, file->f_pos,
ino, DT_UNKNOWN);
if(error) break;
file->f_pos = next;
}
close_dir(dir);
return(0);
}
int hostfs_file_open(struct inode *ino, struct file *file)
{
char *name;
int mode = 0, r = 0, w = 0, fd;
mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
if((mode & HOSTFS_I(ino)->mode) == mode)
return(0);
/* The file may already have been opened, but with the wrong access,
* so this resets things and reopens the file with the new access.
*/
if(HOSTFS_I(ino)->fd != -1){
close_file(&HOSTFS_I(ino)->fd);
HOSTFS_I(ino)->fd = -1;
}
HOSTFS_I(ino)->mode |= mode;
if(HOSTFS_I(ino)->mode & FMODE_READ)
r = 1;
if(HOSTFS_I(ino)->mode & FMODE_WRITE)
w = 1;
if(w)
r = 1;
name = dentry_name(file->f_dentry, 0);
if(name == NULL)
return(-ENOMEM);
fd = open_file(name, r, w, append);
kfree(name);
if(fd < 0) return(fd);
FILE_HOSTFS_I(file)->fd = fd;
return(0);
}
int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
{
return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync);
}
static const struct file_operations hostfs_file_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.sendfile = generic_file_sendfile,
.aio_read = generic_file_aio_read,
.aio_write = generic_file_aio_write,
.write = do_sync_write,
.mmap = generic_file_mmap,
.open = hostfs_file_open,
.release = NULL,
.fsync = hostfs_fsync,
};
static const struct file_operations hostfs_dir_fops = {
.llseek = generic_file_llseek,
.readdir = hostfs_readdir,
.read = generic_read_dir,
};
int hostfs_writepage(struct page *page, struct writeback_control *wbc)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
char *buffer;
unsigned long long base;
int count = PAGE_CACHE_SIZE;
int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
int err;
if (page->index >= end_index)
count = inode->i_size & (PAGE_CACHE_SIZE-1);
buffer = kmap(page);
base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
if(err != count){
ClearPageUptodate(page);
goto out;
}
if (base > inode->i_size)
inode->i_size = base;
if (PageError(page))
ClearPageError(page);
err = 0;
out:
kunmap(page);
unlock_page(page);
return err;
}
int hostfs_readpage(struct file *file, struct page *page)
{
char *buffer;
long long start;
int err = 0;
start = (long long) page->index << PAGE_CACHE_SHIFT;
buffer = kmap(page);
err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
PAGE_CACHE_SIZE);
if(err < 0) goto out;
memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
flush_dcache_page(page);
SetPageUptodate(page);
if (PageError(page)) ClearPageError(page);
err = 0;
out:
kunmap(page);
unlock_page(page);
return(err);
}
int hostfs_prepare_write(struct file *file, struct page *page,
unsigned int from, unsigned int to)
{
char *buffer;
long long start, tmp;
int err;
start = (long long) page->index << PAGE_CACHE_SHIFT;
buffer = kmap(page);
if(from != 0){
tmp = start;
err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer,
from);
if(err < 0) goto out;
}
if(to != PAGE_CACHE_SIZE){
start += to;
err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to,
PAGE_CACHE_SIZE - to);
if(err < 0) goto out;
}
err = 0;
out:
kunmap(page);
return(err);
}
int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
unsigned to)
{
struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
char *buffer;
long long start;
int err = 0;
start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from;
buffer = kmap(page);
err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
to - from);
if(err > 0) err = 0;
/* Actually, if !err, write_file has added to-from to start, so, despite
* the appearance, we are comparing i_size against the _last_ written
* location, as we should. */
if(!err && (start > inode->i_size))
inode->i_size = start;
kunmap(page);
return(err);
}
static const struct address_space_operations hostfs_aops = {
.writepage = hostfs_writepage,
.readpage = hostfs_readpage,
.set_page_dirty = __set_page_dirty_nobuffers,
.prepare_write = hostfs_prepare_write,
.commit_write = hostfs_commit_write
};
static int init_inode(struct inode *inode, struct dentry *dentry)
{
char *name;
int type, err = -ENOMEM;
int maj, min;
dev_t rdev = 0;
if(dentry){
name = dentry_name(dentry, 0);
if(name == NULL)
goto out;
type = file_type(name, &maj, &min);
/*Reencode maj and min with the kernel encoding.*/
rdev = MKDEV(maj, min);
kfree(name);
}
else type = OS_TYPE_DIR;
err = 0;
if(type == OS_TYPE_SYMLINK)
inode->i_op = &page_symlink_inode_operations;
else if(type == OS_TYPE_DIR)
inode->i_op = &hostfs_dir_iops;
else inode->i_op = &hostfs_iops;
if(type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
else inode->i_fop = &hostfs_file_fops;
if(type == OS_TYPE_SYMLINK)
inode->i_mapping->a_ops = &hostfs_link_aops;
else inode->i_mapping->a_ops = &hostfs_aops;
switch (type) {
case OS_TYPE_CHARDEV:
init_special_inode(inode, S_IFCHR, rdev);
break;
case OS_TYPE_BLOCKDEV:
init_special_inode(inode, S_IFBLK, rdev);
break;
case OS_TYPE_FIFO:
init_special_inode(inode, S_IFIFO, 0);
break;
case OS_TYPE_SOCK:
init_special_inode(inode, S_IFSOCK, 0);
break;
}
out:
return(err);
}
int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
struct nameidata *nd)
{
struct inode *inode;
char *name;
int error, fd;
error = -ENOMEM;
inode = iget(dir->i_sb, 0);
if(inode == NULL) goto out;
error = init_inode(inode, dentry);
if(error)
goto out_put;
error = -ENOMEM;
name = dentry_name(dentry, 0);
if(name == NULL)
goto out_put;
fd = file_create(name,
mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
if(fd < 0)
error = fd;
else error = read_name(inode, name);
kfree(name);
if(error)
goto out_put;
HOSTFS_I(inode)->fd = fd;
HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
d_instantiate(dentry, inode);
return(0);
out_put:
iput(inode);
out:
return(error);
}
struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
struct nameidata *nd)
{
struct inode *inode;
char *name;
int err;
err = -ENOMEM;
inode = iget(ino->i_sb, 0);
if(inode == NULL)
goto out;
err = init_inode(inode, dentry);
if(err)
goto out_put;
err = -ENOMEM;
name = dentry_name(dentry, 0);
if(name == NULL)
goto out_put;
err = read_name(inode, name);
kfree(name);
if(err == -ENOENT){
iput(inode);
inode = NULL;
}
else if(err)
goto out_put;
d_add(dentry, inode);
dentry->d_op = &hostfs_dentry_ops;
return(NULL);
out_put:
iput(inode);
out:
return(ERR_PTR(err));
}
static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
{
char *file;
int len;
file = inode_name(ino, dentry->d_name.len + 1);
if(file == NULL) return(NULL);
strcat(file, "/");
len = strlen(file);
strncat(file, dentry->d_name.name, dentry->d_name.len);
file[len + dentry->d_name.len] = '\0';
return(file);
}
int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
{
char *from_name, *to_name;
int err;
if((from_name = inode_dentry_name(ino, from)) == NULL)
return(-ENOMEM);
to_name = dentry_name(to, 0);
if(to_name == NULL){
kfree(from_name);
return(-ENOMEM);
}
err = link_file(to_name, from_name);
kfree(from_name);
kfree(to_name);
return(err);
}
int hostfs_unlink(struct inode *ino, struct dentry *dentry)
{
char *file;
int err;
if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
if(append)
return(-EPERM);
err = unlink_file(file);
kfree(file);
return(err);
}
int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
{
char *file;
int err;
if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
err = make_symlink(file, to);
kfree(file);
return(err);
}
int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
{
char *file;
int err;
if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
err = do_mkdir(file, mode);
kfree(file);
return(err);
}
int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
{
char *file;
int err;
if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
err = do_rmdir(file);
kfree(file);
return(err);
}
int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
struct inode *inode;
char *name;
int err = -ENOMEM;
inode = iget(dir->i_sb, 0);
if(inode == NULL)
goto out;
err = init_inode(inode, dentry);
if(err)
goto out_put;
err = -ENOMEM;
name = dentry_name(dentry, 0);
if(name == NULL)
goto out_put;
init_special_inode(inode, mode, dev);
err = do_mknod(name, mode, dev);
if(err)
goto out_free;
err = read_name(inode, name);
kfree(name);
if(err)
goto out_put;
d_instantiate(dentry, inode);
return(0);
out_free:
kfree(name);
out_put:
iput(inode);
out:
return(err);
}
int hostfs_rename(struct inode *from_ino, struct dentry *from,
struct inode *to_ino, struct dentry *to)
{
char *from_name, *to_name;
int err;
if((from_name = inode_dentry_name(from_ino, from)) == NULL)
return(-ENOMEM);
if((to_name = inode_dentry_name(to_ino, to)) == NULL){
kfree(from_name);
return(-ENOMEM);
}
err = rename_file(from_name, to_name);
kfree(from_name);
kfree(to_name);
return(err);
}
int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
{
char *name;
int r = 0, w = 0, x = 0, err;
if (desired & MAY_READ) r = 1;
if (desired & MAY_WRITE) w = 1;
if (desired & MAY_EXEC) x = 1;
name = inode_name(ino, 0);
if (name == NULL) return(-ENOMEM);
if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
err = 0;
else
err = access_file(name, r, w, x);
kfree(name);
if(!err)
err = generic_permission(ino, desired, NULL);
return err;
}
int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct hostfs_iattr attrs;
char *name;
int err;
err = inode_change_ok(dentry->d_inode, attr);
if (err)
return err;
if(append)
attr->ia_valid &= ~ATTR_SIZE;
attrs.ia_valid = 0;
if(attr->ia_valid & ATTR_MODE){
attrs.ia_valid |= HOSTFS_ATTR_MODE;
attrs.ia_mode = attr->ia_mode;
}
if(attr->ia_valid & ATTR_UID){
attrs.ia_valid |= HOSTFS_ATTR_UID;
attrs.ia_uid = attr->ia_uid;
}
if(attr->ia_valid & ATTR_GID){
attrs.ia_valid |= HOSTFS_ATTR_GID;
attrs.ia_gid = attr->ia_gid;
}
if(attr->ia_valid & ATTR_SIZE){
attrs.ia_valid |= HOSTFS_ATTR_SIZE;
attrs.ia_size = attr->ia_size;
}
if(attr->ia_valid & ATTR_ATIME){
attrs.ia_valid |= HOSTFS_ATTR_ATIME;
attrs.ia_atime = attr->ia_atime;
}
if(attr->ia_valid & ATTR_MTIME){
attrs.ia_valid |= HOSTFS_ATTR_MTIME;
attrs.ia_mtime = attr->ia_mtime;
}
if(attr->ia_valid & ATTR_CTIME){
attrs.ia_valid |= HOSTFS_ATTR_CTIME;
attrs.ia_ctime = attr->ia_ctime;
}
if(attr->ia_valid & ATTR_ATIME_SET){
attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
}
if(attr->ia_valid & ATTR_MTIME_SET){
attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
}
name = dentry_name(dentry, 0);
if(name == NULL) return(-ENOMEM);
err = set_attr(name, &attrs);
kfree(name);
if(err)
return(err);
return(inode_setattr(dentry->d_inode, attr));
}
int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat)
{
generic_fillattr(dentry->d_inode, stat);
return(0);
}
static struct inode_operations hostfs_iops = {
.create = hostfs_create,
.link = hostfs_link,
.unlink = hostfs_unlink,
.symlink = hostfs_symlink,
.mkdir = hostfs_mkdir,
.rmdir = hostfs_rmdir,
.mknod = hostfs_mknod,
.rename = hostfs_rename,
.permission = hostfs_permission,
.setattr = hostfs_setattr,
.getattr = hostfs_getattr,
};
static struct inode_operations hostfs_dir_iops = {
.create = hostfs_create,
.lookup = hostfs_lookup,
.link = hostfs_link,
.unlink = hostfs_unlink,
.symlink = hostfs_symlink,
.mkdir = hostfs_mkdir,
.rmdir = hostfs_rmdir,
.mknod = hostfs_mknod,
.rename = hostfs_rename,
.permission = hostfs_permission,
.setattr = hostfs_setattr,
.getattr = hostfs_getattr,
};
int hostfs_link_readpage(struct file *file, struct page *page)
{
char *buffer, *name;
int err;
buffer = kmap(page);
name = inode_name(page->mapping->host, 0);
if(name == NULL) return(-ENOMEM);
err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
kfree(name);
if(err == PAGE_CACHE_SIZE)
err = -E2BIG;
else if(err > 0){
flush_dcache_page(page);
SetPageUptodate(page);
if (PageError(page)) ClearPageError(page);
err = 0;
}
kunmap(page);
unlock_page(page);
return(err);
}
static const struct address_space_operations hostfs_link_aops = {
.readpage = hostfs_link_readpage,
};
static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
{
struct inode *root_inode;
char *name, *data = d;
int err;
sb->s_blocksize = 1024;
sb->s_blocksize_bits = 10;
sb->s_magic = HOSTFS_SUPER_MAGIC;
sb->s_op = &hostfs_sbops;
if((data == NULL) || (*data == '\0'))
data = root_ino;
err = -ENOMEM;
name = kmalloc(strlen(data) + 1, GFP_KERNEL);
if(name == NULL)
goto out;
strcpy(name, data);
root_inode = iget(sb, 0);
if(root_inode == NULL)
goto out_free;
err = init_inode(root_inode, NULL);
if(err)
goto out_put;
HOSTFS_I(root_inode)->host_filename = name;
err = -ENOMEM;
sb->s_root = d_alloc_root(root_inode);
if(sb->s_root == NULL)
goto out_put;
err = read_inode(root_inode);
if(err){
/* No iput in this case because the dput does that for us */
dput(sb->s_root);
sb->s_root = NULL;
goto out_free;
}
return(0);
out_put:
iput(root_inode);
out_free:
kfree(name);
out:
return(err);
}
static int hostfs_read_sb(struct file_system_type *type,
int flags, const char *dev_name,
void *data, struct vfsmount *mnt)
{
return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
}
static struct file_system_type hostfs_type = {
.owner = THIS_MODULE,
.name = "hostfs",
.get_sb = hostfs_read_sb,
.kill_sb = kill_anon_super,
.fs_flags = 0,
};
static int __init init_hostfs(void)
{
return(register_filesystem(&hostfs_type));
}
static void __exit exit_hostfs(void)
{
unregister_filesystem(&hostfs_type);
}
module_init(init_hostfs)
module_exit(exit_hostfs)
MODULE_LICENSE("GPL");
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/