/*
* Connect a wrapfs inode dentry/inode with several lower ones. This is
* the classic stackable file system "vnode interposition" action.
*
* @dentry: wrapfs's dentry which interposes on lower one
* @sb: wrapfs's super_block
* @lower_path: the lower path (caller does path_get/put)
*/
int wrapfs_interpose(struct dentry *dentry, struct super_block *sb,
struct path *lower_path)
{
int err = 0;
struct inode *inode;
struct inode *lower_inode;
struct super_block *lower_sb;
lower_inode = lower_path->dentry->d_inode;
lower_sb = wrapfs_lower_super(sb);
/* check that the lower file system didn't cross a mount point */
if (lower_inode->i_sb != lower_sb) {
err = -EXDEV;
goto out;
}
/*
* We allocate our new inode below by calling wrapfs_iget,
* which will initialize some of the new inode's fields
*/
/* inherit lower inode number for wrapfs's inode */
inode = wrapfs_iget(sb, lower_inode);
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
d_add(dentry, inode);
out:
return err;
}
/* final actions when unmounting a file system */
static void wrapfs_put_super(struct super_block *sb)
{
struct wrapfs_sb_info *spd;
struct super_block *s;
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG;
#endif
spd = WRAPFS_SB(sb);
if (!spd)
return;
/* decrement lower super references */
s = wrapfs_lower_super(sb);
wrapfs_set_lower_super(sb, NULL);
atomic_dec(&s->s_active);
kfree(spd);
sb->s_fs_info = NULL;
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG_EXIT(0);
#endif
}
/*
* Used only in nfs, to kill any pending RPC tasks, so that subsequent
* code can actually succeed and won't leave tasks that need handling.
*/
static void wrapfs_umount_begin(struct super_block *sb)
{
struct super_block *lower_sb;
lower_sb = wrapfs_lower_super(sb);
if (lower_sb && lower_sb->s_op && lower_sb->s_op->umount_begin)
lower_sb->s_op->umount_begin(lower_sb);
}
/*
* Used only in nfs, to kill any pending RPC tasks, so that subsequent
* code can actually succeed and won't leave tasks that need handling.
*/
static void wrapfs_umount_begin(struct super_block *sb)
{
struct super_block *lower_sb;
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG;
#endif
lower_sb = wrapfs_lower_super(sb);
if (lower_sb && lower_sb->s_op && lower_sb->s_op->umount_begin)
lower_sb->s_op->umount_begin(lower_sb);
#ifdef EXTRA_CREDIT
if(dbg_bitmap & DBG_SB_OP)
UDBG_EXIT(0);
#endif
}
/* final actions when unmounting a file system */
static void wrapfs_put_super(struct super_block *sb)
{
struct wrapfs_sb_info *spd;
struct super_block *s;
spd = WRAPFS_SB(sb);
if (!spd)
return;
/* decrement lower super references */
s = wrapfs_lower_super(sb);
wrapfs_set_lower_super(sb, NULL);
atomic_dec(&s->s_active);
kfree(spd);
sb->s_fs_info = NULL;
}
/* Connect a wrapfs inode dentry/inode with several lower ones. This is
* the classic stackable file system "vnode interposition" action.
*
* @dentry: wrapfs's dentry which interposes on lower one
* @sb: wrapfs's super_block
* @lower_path: the lower path (caller does path_get/put)
*/
int wrapfs_interpose(struct dentry *dentry, struct super_block *sb,
struct path *lower_path)
{
int err = 0;
struct inode *inode;
struct inode *lower_inode;
struct super_block *lower_sb;
lower_inode = lower_path->dentry->d_inode;
lower_sb = wrapfs_lower_super(sb);
/* check that the lower file system didn't cross a mount point */
if (lower_inode->i_sb != lower_sb) {
err = -EXDEV;
goto out;
}
/*
* We allocate our new inode below by calling wrapfs_iget,
* which will initialize some of the new inode's fields
*/
/* inherit lower inode number for wrapfs's inode */
inode = wrapfs_new_iget(sb, iunique(sb, 1));
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
if (atomic_read(&inode->i_count) > 1)
goto out_add;
wrapfs_fill_inode(dentry, inode);
printk(KERN_INFO" U2fs_interpose success\n");
out_add:
d_add(dentry, inode);
out:
return err;
}
