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>

3 files changed, 32 insertions, 46 deletions

diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index c518421a9355..d4accdcb53a2 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -739,16 +739,18 @@ exp_find_key(svc_client *clp, int fsid_type, u32 *fsidv, struct cache_req *reqp)
         int err;
         
         if (!clp)
-                return NULL;
+                return ERR_PTR(-ENOENT);
 
         key.ek_client = clp;
         key.ek_fsidtype = fsid_type;
         memcpy(key.ek_fsid, fsidv, key_len(fsid_type));
 
         ek = svc_expkey_lookup(&key);
-        if (ek != NULL)
-                if ((err = cache_check(&svc_expkey_cache, &ek->h, reqp)))
-                        ek = ERR_PTR(err);
+        if (ek == NULL)
+                return ERR_PTR(-ENOMEM);
+        err = cache_check(&svc_expkey_cache, &ek->h, reqp);
+        if (err)
+                return ERR_PTR(err);
         return ek;
 }
 
@@ -809,30 +811,21 @@ exp_get_by_name(svc_client *clp, struct vfsmount *mnt, struct dentry *dentry,
                 struct cache_req *reqp)
 {
         struct svc_export *exp, key;
+        int err;
         
         if (!clp)
-                return NULL;
+                return ERR_PTR(-ENOENT);
 
         key.ex_client = clp;
         key.ex_mnt = mnt;
         key.ex_dentry = dentry;
 
         exp = svc_export_lookup(&key);
-        if (exp != NULL)  {
-                int err;
-
-                err = cache_check(&svc_export_cache, &exp->h, reqp);
-                switch (err) {
-                case 0: break;
-                case -EAGAIN:
-                case -ETIMEDOUT:
-                        exp = ERR_PTR(err);
-                        break;
-                default:
-                        exp = NULL;
-                }
-        }
-
+        if (exp == NULL)
+                return ERR_PTR(-ENOMEM);
+        err = cache_check(&svc_export_cache, &exp->h, reqp);
+        if (err)
+                return ERR_PTR(err);
         return exp;
 }
 
@@ -848,7 +841,7 @@ exp_parent(svc_client *clp, struct vfsmount *mnt, struct dentry *dentry,
         dget(dentry);
         exp = exp_get_by_name(clp, mnt, dentry, reqp);
 
-        while (exp == NULL && !IS_ROOT(dentry)) {
+        while (PTR_ERR(exp) == -ENOENT && !IS_ROOT(dentry)) {
                 struct dentry *parent;
 
                 parent = dget_parent(dentry);
@@ -901,7 +894,7 @@ static void exp_fsid_unhash(struct svc_export *exp)
                 return;
 
         ek = exp_get_fsid_key(exp->ex_client, exp->ex_fsid);
-        if (ek && !IS_ERR(ek)) {
+        if (!IS_ERR(ek)) {
                 ek->h.expiry_time = get_seconds()-1;
                 cache_put(&ek->h, &svc_expkey_cache);
         }
@@ -939,7 +932,7 @@ static void exp_unhash(struct svc_export *exp)
         struct inode *inode = exp->ex_dentry->d_inode;
 
         ek = exp_get_key(exp->ex_client, inode->i_sb->s_dev, inode->i_ino);
-        if (ek && !IS_ERR(ek)) {
+        if (!IS_ERR(ek)) {
                 ek->h.expiry_time = get_seconds()-1;
                 cache_put(&ek->h, &svc_expkey_cache);
         }
@@ -990,13 +983,12 @@ exp_export(struct nfsctl_export *nxp)
 
         /* must make sure there won't be an ex_fsid clash */
         if ((nxp->ex_flags & NFSEXP_FSID) &&
-            (fsid_key = exp_get_fsid_key(clp, nxp->ex_dev)) &&
-            !IS_ERR(fsid_key) &&
+            (!IS_ERR(fsid_key = exp_get_fsid_key(clp, nxp->ex_dev))) &&
             fsid_key->ek_mnt &&
             (fsid_key->ek_mnt != nd.mnt || fsid_key->ek_dentry != nd.dentry) )
                 goto finish;
 
-        if (exp) {
+        if (!IS_ERR(exp)) {
                 /* just a flags/id/fsid update */
 
                 exp_fsid_unhash(exp);
@@ -1105,7 +1097,7 @@ exp_unexport(struct nfsctl_export *nxp)
         err = -EINVAL;
         exp = exp_get_by_name(dom, nd.mnt, nd.dentry, NULL);
         path_release(&nd);
-        if (!exp)
+        if (IS_ERR(exp))
                 goto out_domain;
 
         exp_do_unexport(exp);
@@ -1150,10 +1142,6 @@ exp_rootfh(svc_client *clp, char *path, struct knfsd_fh *f, int maxsize)
                 err = PTR_ERR(exp);
                 goto out;
         }
-        if (!exp) {
-                dprintk("nfsd: exp_rootfh export not found.\n");
-                goto out;
-        }
 
         /*
          * fh must be initialized before calling fh_compose
@@ -1177,13 +1165,13 @@ exp_find(struct auth_domain *clp, int fsid_type, u32 *fsidv,
 {
         struct svc_export *exp;
         struct svc_expkey *ek = exp_find_key(clp, fsid_type, fsidv, reqp);
-        if (!ek || IS_ERR(ek))
+        if (IS_ERR(ek))
                 return ERR_PTR(PTR_ERR(ek));
 
         exp = exp_get_by_name(clp, ek->ek_mnt, ek->ek_dentry, reqp);
         cache_put(&ek->h, &svc_expkey_cache);
 
-        if (!exp || IS_ERR(exp))
+        if (IS_ERR(exp))
                 return ERR_PTR(PTR_ERR(exp));
         return exp;
 }
@@ -1205,10 +1193,10 @@ exp_pseudoroot(struct auth_domain *clp, struct svc_fh *fhp,
         mk_fsid(FSID_NUM, fsidv, 0, 0, 0, NULL);
 
         exp = exp_find(clp, FSID_NUM, fsidv, creq);
+        if (PTR_ERR(exp) == -ENOENT)
+                return nfserr_perm;
         if (IS_ERR(exp))
                 return nfserrno(PTR_ERR(exp));
-        if (exp == NULL)
-                return nfserr_perm;
         rv = fh_compose(fhp, exp, exp->ex_dentry, NULL);
         exp_put(exp);
         return rv;
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;
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 8d6b5c483ae1..0a18149ce963 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -192,15 +192,14 @@ nfsd_lookup(struct svc_rqst *rqstp, struct svc_fh *fhp, const char *name,
 
                         exp2 = exp_parent(exp->ex_client, mnt, dentry,
                                           &rqstp->rq_chandle);
-                        if (IS_ERR(exp2)) {
+                        if (PTR_ERR(exp2) == -ENOENT) {
+                                dput(dentry);
+                                dentry = dget(dparent);
+                        } else if (IS_ERR(exp2)) {
                                 host_err = PTR_ERR(exp2);
                                 dput(dentry);
                                 mntput(mnt);
                                 goto out_nfserr;
-                        }
-                        if (!exp2) {
-                                dput(dentry);
-                                dentry = dget(dparent);
                         } else {
                                 exp_put(exp);
                                 exp = exp2;