knfsd: nfsd: make all exp_finding functions return -errno's on err

Currently exp_find(), exp_get_by_name(), and friends, return an export on
success, and on failure return:

	errors -EAGAIN (drop this request pending an upcall) or
		-ETIMEDOUT (an upcall has timed out), or
	return NULL, which can mean either that there was a memory allocation
		failure, or that an export was not found, or that a passed-in
		export lacks an auth_domain.

Many callers seem to assume that NULL means that an export was not found,
which may lead to bugs in the case of a memory allocation failure.

Modify these functions to distinguish between the two NULL cases by returning
either -ENOENT or -ENOMEM.  They now never return NULL.  We get to simplify
some code in the process.

We return -ENOENT in the case of a missing auth_domain.  This case should
probably be removed (or converted to a bug) after confirming that it can never
happen.

Signed-off-by: "J. Bruce Fields" <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 6 deletions

diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index ecf9c361b3f5..89f9041a7782 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -160,15 +160,14 @@ fh_verify(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, int access)
                                        &rqstp->rq_chandle);
                 }
 
-                if (IS_ERR(exp) && (PTR_ERR(exp) == -EAGAIN
-                                || PTR_ERR(exp) == -ETIMEDOUT)) {
-                        error = nfserrno(PTR_ERR(exp));
+                error = nfserr_stale;
+                if (PTR_ERR(exp) == -ENOENT)
                         goto out;
-                }
 
-                error = nfserr_stale; 
-                if (!exp || IS_ERR(exp))
+                if (IS_ERR(exp)) {
+                        error = nfserrno(PTR_ERR(exp));
                         goto out;
+                }
 
                 /* Check if the request originated from a secure port. */
                 error = nfserr_perm;