xfs: use ->readlink to implement the readlink_by_handle ioctl

Also drop the now unused readlink_copy export.

[dchinner: use d_inode(dentry) rather than dentry->d_inode]

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/namei.c

@@ -4515,7 +4515,6 @@ int readlink_copy(char __user *buffer, int buflen, const char *link)
 out:
 	return len;
 }
-EXPORT_SYMBOL(readlink_copy);
 
 /*
  * A helper for ->readlink().  This should be used *ONLY* for symlinks that

fs/xfs/xfs_ioctl.c

@@ -277,7 +277,6 @@ xfs_readlink_by_handle(
 {
 	struct dentry		*dentry;
 	__u32			olen;
-	void			*link;
 	int			error;
 
 	if (!capable(CAP_SYS_ADMIN))
@@ -288,7 +287,7 @@ xfs_readlink_by_handle(
 		return PTR_ERR(dentry);
 
 	/* Restrict this handle operation to symlinks only. */
-	if (!d_is_symlink(dentry)) {
+	if (!d_inode(dentry)->i_op->readlink) {
 		error = -EINVAL;
 		goto out_dput;
 	}
@@ -298,21 +297,8 @@ xfs_readlink_by_handle(
 		goto out_dput;
 	}
 
-	link = kmalloc(MAXPATHLEN+1, GFP_KERNEL);
-	if (!link) {
-		error = -ENOMEM;
-		goto out_dput;
-	}
-
-	error = xfs_readlink(XFS_I(d_inode(dentry)), link);
-	if (error)
-		goto out_kfree;
-	error = readlink_copy(hreq->ohandle, olen, link);
-	if (error)
-		goto out_kfree;
+	error = d_inode(dentry)->i_op->readlink(dentry, hreq->ohandle, olen);
 
- out_kfree:
-	kfree(link);
  out_dput:
 	dput(dentry);
 	return error;