NFS: Make nfs_fhget() return appropriate error values

Currently it returns NULL, which usually gets interpreted as ENOMEM. In
fact it can mean a host of issues.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/dir.c

@@ -901,9 +901,9 @@ static struct dentry *nfs_lookup(struct inode *dir, struct dentry * dentry, stru
 		res = ERR_PTR(error);
 		goto out_unlock;
 	}
-	res = ERR_PTR(-EACCES);
 	inode = nfs_fhget(dentry->d_sb, &fhandle, &fattr);
-	if (!inode)
+	res = (struct dentry *)inode;
+	if (IS_ERR(res))
 		goto out_unlock;
 no_entry:
 	res = d_add_unique(dentry, inode);
@@ -1096,7 +1096,7 @@ static struct dentry *nfs_readdir_lookup(nfs_readdir_descriptor_t *desc)
 		return NULL;
 	dentry->d_op = NFS_PROTO(dir)->dentry_ops;
 	inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr);
-	if (!inode) {
+	if (IS_ERR(inode)) {
 		dput(dentry);
 		return NULL;
 	}
@@ -1134,9 +1134,9 @@ int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle,
 		if (error < 0)
 			goto out_err;
 	}
-	error = -ENOMEM;
 	inode = nfs_fhget(dentry->d_sb, fhandle, fattr);
-	if (inode == NULL)
+	error = PTR_ERR(inode);
+	if (IS_ERR(inode))
 		goto out_err;
 	d_instantiate(dentry, inode);
 	return 0;

fs/nfs/inode.c

@@ -241,7 +241,6 @@ static struct inode *
 nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh, struct nfs_fsinfo *fsinfo)
 {
 	struct nfs_server	*server = NFS_SB(sb);
-	struct inode *rooti;
 	int			error;
 
 	error = server->rpc_ops->getroot(server, rootfh, fsinfo);
@@ -250,10 +249,7 @@ nfs_get_root(struct super_block *sb, struct nfs_fh *rootfh, struct nfs_fsinfo *f
 		return ERR_PTR(error);
 	}
 
-	rooti = nfs_fhget(sb, rootfh, fsinfo->fattr);
-	if (!rooti)
-		return ERR_PTR(-ENOMEM);
-	return rooti;
+	return nfs_fhget(sb, rootfh, fsinfo->fattr);
 }
 
 /*
@@ -853,7 +849,7 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
 		.fh	= fh,
 		.fattr	= fattr
 	};
-	struct inode *inode = NULL;
+	struct inode *inode = ERR_PTR(-ENOENT);
 	unsigned long hash;
 
 	if ((fattr->valid & NFS_ATTR_FATTR) == 0)
@@ -866,8 +862,11 @@ nfs_fhget(struct super_block *sb, struct nfs_fh *fh, struct nfs_fattr *fattr)
 
 	hash = nfs_fattr_to_ino_t(fattr);
 
-	if (!(inode = iget5_locked(sb, hash, nfs_find_actor, nfs_init_locked, &desc)))
+	inode = iget5_locked(sb, hash, nfs_find_actor, nfs_init_locked, &desc);
+	if (inode == NULL) {
+		inode = ERR_PTR(-ENOMEM);
 		goto out_no_inode;
+	}
 
 	if (inode->i_state & I_NEW) {
 		struct nfs_inode *nfsi = NFS_I(inode);
@@ -936,7 +935,7 @@ out:
 	return inode;
 
 out_no_inode:
-	printk("nfs_fhget: iget failed\n");
+	dprintk("nfs_fhget: iget failed with error %ld\n", PTR_ERR(inode));
 	goto out;
 }
 

fs/nfs/nfs4proc.c

@@ -336,7 +336,7 @@ static struct nfs4_state *nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data
 	if (!(data->f_attr.valid & NFS_ATTR_FATTR))
 		goto out;
 	inode = nfs_fhget(data->dir->d_sb, &data->o_res.fh, &data->f_attr);
-	if (inode == NULL)
+	if (IS_ERR(inode))
 		goto out;
 	state = nfs4_get_open_state(inode, data->owner);
 	if (state == NULL)