static int do_umount(kdev_t dev,int unmount_root)
{
struct super_block * sb;
int retval;
if (dev==ROOT_DEV && !unmount_root) {
/*
* Special case for "unmounting" root. We just try to remount
* it readonly, and sync() the device.
*/
if (!(sb=get_super(dev)))
return -ENOENT;
if (!(sb->s_flags & MS_RDONLY)) {
/*
* Make sure all quotas are turned off on this device we need to mount
* it readonly so no more writes by the quotasystem.
* If later on the remount fails too bad there are no quotas running
* anymore. Turn them on again by hand.
*/
quota_off(dev, -1);
fsync_dev(dev);
retval = do_remount_sb(sb, MS_RDONLY, 0);
if (retval)
return retval;
}
return 0;
}
if (!(sb=get_super(dev)) || !(sb->s_covered))
return -ENOENT;
if (!sb->s_covered->i_mount)
printk("VFS: umount(%s): mounted inode has i_mount=NULL\n",
kdevname(dev));
/*
* Before checking if the filesystem is still busy make sure the kernel
* doesn't hold any quotafiles open on that device. If the umount fails
* too bad there are no quotas running anymore. Turn them on again by hand.
*/
quota_off(dev, -1);
if (!fs_may_umount(dev, sb->s_mounted))
return -EBUSY;
sb->s_covered->i_mount = NULL;
iput(sb->s_covered);
sb->s_covered = NULL;
iput(sb->s_mounted);
sb->s_mounted = NULL;
if (sb->s_op && sb->s_op->write_super && sb->s_dirt)
sb->s_op->write_super(sb);
put_super(dev);
remove_vfsmnt(dev);
return 0;
}
static int do_umount(kdev_t dev)
{
register struct super_block *sb;
register struct super_operations *sop;
int retval = -ENOENT;
if ((sb = get_super(dev))) {
if (dev == ROOT_DEV) {
/* Special case for "unmounting" root. We just try to remount
* it readonly, and sync() the device.
*/
retval = 0;
if (!(sb->s_flags & MS_RDONLY)) {
fsync_dev(dev);
retval = do_remount_sb(sb, MS_RDONLY, 0);
}
}
else if (sb->s_covered) {
if (!sb->s_covered->i_mount)
panic("umount: i_mount=NULL\n");
if (!fs_may_umount(dev, sb->s_mounted))
retval = -EBUSY;
else {
retval = 0;
sb->s_covered->i_mount = NULL;
iput(sb->s_covered);
sb->s_covered = NULL;
iput(sb->s_mounted);
sb->s_mounted = NULL;
sop = sb->s_op;
if (sop && sop->write_super && sb->s_dirt)
sop->write_super(sb);
put_super(dev);
}
}
}
return retval;
}