NFSv4: in readdir, use MOUNTED_ON_FILEID, rather than true fileid

 Some servers return an error if the READDIR call attempts to read the
 fileid of a mountpoint.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -1720,6 +1720,7 @@ static int _nfs4_proc_readdir(struct dentry *dentry, struct rpc_cred *cred,
 		.pages = &page,
 		.pgbase = 0,
 		.count = count,
+		.bitmask = NFS_SERVER(dentry->d_inode)->attr_bitmask,
 	};
 	struct nfs4_readdir_res res;
 	struct rpc_message msg = {

fs/nfs/nfs4xdr.c

@@ -1010,8 +1010,13 @@ static int encode_readdir(struct xdr_stream *xdr, const struct nfs4_readdir_arg
 	WRITE32(readdir->count >> 1);  /* We're not doing readdirplus */
 	WRITE32(readdir->count);
 	WRITE32(2);
+	if (readdir->bitmask[1] & FATTR4_WORD1_MOUNTED_ON_FILEID) {
+		WRITE32(0);
+		WRITE32(FATTR4_WORD1_MOUNTED_ON_FILEID);
+	} else {
 		WRITE32(FATTR4_WORD0_FILEID);
 		WRITE32(0);
+	}
 
 	/* set up reply kvec
 	 *    toplevel_status + taglen + rescount + OP_PUTFH + status
@@ -3857,7 +3862,7 @@ static int nfs4_xdr_dec_delegreturn(struct rpc_rqst *rqstp, uint32_t *p, void *d
 
 uint32_t *nfs4_decode_dirent(uint32_t *p, struct nfs_entry *entry, int plus)
 {
-	uint32_t bitmap[1] = {0};
+	uint32_t bitmap[2] = {0};
 	uint32_t len;
 
 	if (!*p++) {
@@ -3881,13 +3886,18 @@ uint32_t *nfs4_decode_dirent(uint32_t *p, struct nfs_entry *entry, int plus)
 	entry->ino = 1;
 
 	len = ntohl(*p++);		/* bitmap length */
-	if (len > 0) {
-		bitmap[0] = ntohl(*p);
+	if (len-- > 0) {
+		bitmap[0] = ntohl(*p++);
+		if (len-- > 0) {
+			bitmap[1] = ntohl(*p++);
 			p += len;
 		}
+	}
 	len = XDR_QUADLEN(ntohl(*p++));	/* attribute buffer length */
 	if (len > 0) {
-		if (bitmap[0] == FATTR4_WORD0_FILEID)
+		if (bitmap[0] == 0 && bitmap[1] == FATTR4_WORD1_MOUNTED_ON_FILEID)
+			xdr_decode_hyper(p, &entry->ino);
+		else if (bitmap[0] == FATTR4_WORD0_FILEID)
 			xdr_decode_hyper(p, &entry->ino);
 		p += len;
 	}

include/linux/nfs_xdr.h

@@ -563,6 +563,7 @@ struct nfs4_readdir_arg {
 	u32				count;
 	struct page **			pages;	/* zero-copy data */
 	unsigned int			pgbase;	/* zero-copy data */
+	const u32 *			bitmask;
 };
 
 struct nfs4_readdir_res {