knfsd: Fixed problem with NFS exporting directories which are mounted on.

Recent changes in NFSd cause a directory which is mounted-on
to not appear properly when the filesystem containing it is exported.

*exp_get* now returns -ENOENT rather than NULL and when
commit 5d3dbbeaf56d0365ac6b5c0a0da0bd31cc4781e1
removed the NULL checks, it didn't add a check for -ENOENT.

Signed-off-by: Neil Brown <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/nfsd/vfs.c

···
 
 	exp2 = rqst_exp_get_by_name(rqstp, mnt, mounts);
 	if (IS_ERR(exp2)) {
-		err = PTR_ERR(exp2);
+		if (PTR_ERR(exp2) != -ENOENT)
+			err = PTR_ERR(exp2);
 		dput(mounts);
 		mntput(mnt);
 		goto out;