Re: [RFC v2 1/1] shiftfs: uid/gid shifting bind mount

From: Vivek Goyal
Date: Thu Mar 02 2017 - 12:50:38 EST


On Mon, Feb 20, 2017 at 04:47:05PM -0800, James Bottomley wrote:

[..]
> +static int shiftfs_readlink(struct dentry *dentry, char __user *data,
> + int flags)
> +{
> + struct dentry *real = dentry->d_fsdata;
> + const struct inode_operations *iop = real->d_inode->i_op;
> +
> + if (iop->readlink)
> + return iop->readlink(real, data, flags);
> +
> + return -EINVAL;
> +}
> +

Hi James,

I was testing shiftfs on top of xfs and noticed readlink() is failing as
xfs does not define readlink.

Following patch fixes it for me.

Vivek

---
fs/shiftfs.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

Index: rhvgoyal-linux/fs/shiftfs.c
===================================================================
--- rhvgoyal-linux.orig/fs/shiftfs.c 2017-02-28 11:07:04.360579594 -0500
+++ rhvgoyal-linux/fs/shiftfs.c 2017-03-02 11:59:17.484345405 -0500
@@ -179,12 +179,8 @@ static int shiftfs_readlink(struct dentr
int flags)
{
struct dentry *real = dentry->d_fsdata;
- const struct inode_operations *iop = real->d_inode->i_op;

- if (iop->readlink)
- return iop->readlink(real, data, flags);
-
- return -EINVAL;
+ return vfs_readlink(real, data, flags);
}

static const char *shiftfs_get_link(struct dentry *dentry, struct inode *inode,