nfs: Add support for the v4.1 dacl attribute

The dacl attribute includes Automatic Inheritance flags not supported by
the acl attribute.  it is only supported in NFS version 4.1 and higher.
On systems where NFS version 4.0 is still the default, an additional
mount option is needed:

    mount -t nfs4 -o vers=4.1 [...]

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index fe7e230..ad3c441 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4634,7 +4634,7 @@
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct page *pages[DIV_ROUND_UP(NFS4ACL_SIZE_MAX, PAGE_SIZE)] = {};
 	struct nfs_getaclargs args = {
-		.fh = NFS_FH(inode),
+		.inode = inode,
 		.acl_pages = pages,
 		.acl_len = ARRAY_SIZE(pages) * PAGE_SIZE,
 	};
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 7796e6b..55b4493 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -1661,9 +1661,16 @@
 	encode_nfs4_stateid(xdr, &zero_stateid);
 
 	/* Encode attribute bitmap. */
-	p = reserve_space(xdr, 2*4);
-	*p++ = cpu_to_be32(1);
-	*p = cpu_to_be32(FATTR4_WORD0_ACL);
+	if (arg->server->attr_bitmask[1] & FATTR4_WORD1_DACL) {
+		p = reserve_space(xdr, 3*4);
+		*p++ = cpu_to_be32(2);
+		*p++ = 0;
+		*p = cpu_to_be32(FATTR4_WORD1_DACL);
+	} else {
+		p = reserve_space(xdr, 2*4);
+		*p++ = cpu_to_be32(1);
+		*p = cpu_to_be32(FATTR4_WORD0_ACL);
+	}
 
 	attrlen_offset = xdr->buf->len;
 	xdr_reserve_space(xdr, 4);  /* to be backfilled later */
@@ -2498,9 +2505,12 @@
 
 	encode_compound_hdr(xdr, req, &hdr);
 	encode_sequence(xdr, &args->seq_args, &hdr);
-	encode_putfh(xdr, args->fh, &hdr);
+	encode_putfh(xdr, NFS_FH(args->inode), &hdr);
 	replen = hdr.replen + op_decode_hdr_maxsz + 1;
-	encode_getattr_two(xdr, FATTR4_WORD0_ACL, FATTR4_WORD1_MODE, &hdr);
+	if (NFS_SERVER(args->inode)->attr_bitmask[1] & FATTR4_WORD1_DACL)
+		encode_getattr_two(xdr, 0, FATTR4_WORD1_MODE | FATTR4_WORD1_DACL, &hdr);
+	else
+		encode_getattr_two(xdr, FATTR4_WORD0_ACL, FATTR4_WORD1_MODE, &hdr);
 
 	xdr_inline_pages(&req->rq_rcv_buf, replen << 2,
 		args->acl_pages, 0, args->acl_len);
@@ -5428,12 +5438,25 @@
 
 	if (unlikely(bitmap[0] & (FATTR4_WORD0_ACL - 1U)))
 		return -EIO;
-	if (likely(bitmap[0] & FATTR4_WORD0_ACL)) {
+
+	if (bitmap[0] & FATTR4_WORD0_ACL) {
+		struct richace *ace;
+
+		if (bitmap[1] & FATTR4_WORD1_DACL)
+			return -EIO;
+
 		acl = decode_acl_entries(xdr, res->server);
 		if (IS_ERR(acl))
 			return PTR_ERR(acl);
+
+		status = -EIO;
+		richacl_for_each_entry(ace, acl) {
+			if (ace->e_flags & RICHACE_INHERITED_ACE)
+				goto out;
+		}
+
 		bitmap[0] &= ~FATTR4_WORD0_ACL;
-	} else
+	} else if (!(bitmap[1] & FATTR4_WORD1_DACL))
 		return -EOPNOTSUPP;
 
 	status = -EIO;
@@ -5443,6 +5466,23 @@
 	status = decode_attr_mode(xdr, bitmap, &res->mode);
 	if (status < 0)
 		goto out;
+
+	if (bitmap[1] & FATTR4_WORD1_DACL) {
+		unsigned int flags;
+		__be32 *p;
+
+		p = xdr_inline_decode(xdr, 4);
+		if (unlikely(!p))
+			return -EIO;
+		flags = be32_to_cpup(p);
+
+		acl = decode_acl_entries(xdr, res->server);
+		if (IS_ERR(acl))
+			return PTR_ERR(acl);
+
+		acl->a_flags = flags;
+		bitmap[1] &= ~FATTR4_WORD1_DACL;
+	}
 	status = 0;
 
 out:
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 23a8dbc..061356b 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -717,7 +717,7 @@
 
 struct nfs_getaclargs {
 	struct nfs4_sequence_args 	seq_args;
-	struct nfs_fh *			fh;
+	struct inode *			inode;
 	size_t				acl_len;
 	struct page **			acl_pages;
 };