NFSv4: Save the owner/group name string when doing open

...so that we can do the uid/gid mapping outside the asynchronous RPC
context.
This fixes a bug in the current NFSv4 atomic open code where the client
isn't able to determine what the true uid/gid fields of the file are,
(because the asynchronous nature of the OPEN call denies it the ability
to do an upcall) and so fills them with default values, marking the
inode as needing revalidation.
Unfortunately, in some cases, the VFS will do some additional sanity
checks on the file, and may override the server's decision to allow
the open because it sees the wrong owner/group fields.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 47d1c6f..2c05f19 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -38,6 +38,89 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/nfs_idmap.h>
+#include <linux/nfs_fs.h>
+
+/**
+ * nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
+ * @fattr: fully initialised struct nfs_fattr
+ * @owner_name: owner name string cache
+ * @group_name: group name string cache
+ */
+void nfs_fattr_init_names(struct nfs_fattr *fattr,
+		struct nfs4_string *owner_name,
+		struct nfs4_string *group_name)
+{
+	fattr->owner_name = owner_name;
+	fattr->group_name = group_name;
+}
+
+static void nfs_fattr_free_owner_name(struct nfs_fattr *fattr)
+{
+	fattr->valid &= ~NFS_ATTR_FATTR_OWNER_NAME;
+	kfree(fattr->owner_name->data);
+}
+
+static void nfs_fattr_free_group_name(struct nfs_fattr *fattr)
+{
+	fattr->valid &= ~NFS_ATTR_FATTR_GROUP_NAME;
+	kfree(fattr->group_name->data);
+}
+
+static bool nfs_fattr_map_owner_name(struct nfs_server *server, struct nfs_fattr *fattr)
+{
+	struct nfs4_string *owner = fattr->owner_name;
+	__u32 uid;
+
+	if (!(fattr->valid & NFS_ATTR_FATTR_OWNER_NAME))
+		return false;
+	if (nfs_map_name_to_uid(server, owner->data, owner->len, &uid) == 0) {
+		fattr->uid = uid;
+		fattr->valid |= NFS_ATTR_FATTR_OWNER;
+	}
+	return true;
+}
+
+static bool nfs_fattr_map_group_name(struct nfs_server *server, struct nfs_fattr *fattr)
+{
+	struct nfs4_string *group = fattr->group_name;
+	__u32 gid;
+
+	if (!(fattr->valid & NFS_ATTR_FATTR_GROUP_NAME))
+		return false;
+	if (nfs_map_group_to_gid(server, group->data, group->len, &gid) == 0) {
+		fattr->gid = gid;
+		fattr->valid |= NFS_ATTR_FATTR_GROUP;
+	}
+	return true;
+}
+
+/**
+ * nfs_fattr_free_names - free up the NFSv4 owner and group strings
+ * @fattr: a fully initialised nfs_fattr structure
+ */
+void nfs_fattr_free_names(struct nfs_fattr *fattr)
+{
+	if (fattr->valid & NFS_ATTR_FATTR_OWNER_NAME)
+		nfs_fattr_free_owner_name(fattr);
+	if (fattr->valid & NFS_ATTR_FATTR_GROUP_NAME)
+		nfs_fattr_free_group_name(fattr);
+}
+
+/**
+ * nfs_fattr_map_and_free_names - map owner/group strings into uid/gid and free
+ * @server: pointer to the filesystem nfs_server structure
+ * @fattr: a fully initialised nfs_fattr structure
+ *
+ * This helper maps the cached NFSv4 owner/group strings in fattr into
+ * their numeric uid/gid equivalents, and then frees the cached strings.
+ */
+void nfs_fattr_map_and_free_names(struct nfs_server *server, struct nfs_fattr *fattr)
+{
+	if (nfs_fattr_map_owner_name(server, fattr))
+		nfs_fattr_free_owner_name(fattr);
+	if (nfs_fattr_map_group_name(server, fattr))
+		nfs_fattr_free_group_name(fattr);
+}
 
 static int nfs_map_string_to_numeric(const char *name, size_t namelen, __u32 *res)
 {
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 50a15fa..f59cab1 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1019,6 +1019,8 @@
 	fattr->valid = 0;
 	fattr->time_start = jiffies;
 	fattr->gencount = nfs_inc_attr_generation_counter();
+	fattr->owner_name = NULL;
+	fattr->group_name = NULL;
 }
 
 struct nfs_fattr *nfs_alloc_fattr(void)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 3b10801..df3d306 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -52,6 +52,7 @@
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/module.h>
+#include <linux/nfs_idmap.h>
 #include <linux/sunrpc/bc_xprt.h>
 #include <linux/xattr.h>
 #include <linux/utsname.h>
@@ -760,6 +761,8 @@
 	struct nfs_openres o_res;
 	struct nfs_open_confirmargs c_arg;
 	struct nfs_open_confirmres c_res;
+	struct nfs4_string owner_name;
+	struct nfs4_string group_name;
 	struct nfs_fattr f_attr;
 	struct nfs_fattr dir_attr;
 	struct dentry *dir;
@@ -783,6 +786,7 @@
 	p->o_res.server = p->o_arg.server;
 	nfs_fattr_init(&p->f_attr);
 	nfs_fattr_init(&p->dir_attr);
+	nfs_fattr_init_names(&p->f_attr, &p->owner_name, &p->group_name);
 }
 
 static struct nfs4_opendata *nfs4_opendata_alloc(struct dentry *dentry,
@@ -814,6 +818,7 @@
 	p->o_arg.name = &dentry->d_name;
 	p->o_arg.server = server;
 	p->o_arg.bitmask = server->attr_bitmask;
+	p->o_arg.dir_bitmask = server->cache_consistency_bitmask;
 	p->o_arg.claim = NFS4_OPEN_CLAIM_NULL;
 	if (flags & O_CREAT) {
 		u32 *s;
@@ -850,6 +855,7 @@
 	dput(p->dir);
 	dput(p->dentry);
 	nfs_sb_deactive(sb);
+	nfs_fattr_free_names(&p->f_attr);
 	kfree(p);
 }
 
@@ -1574,6 +1580,8 @@
 	if (status != 0 || !data->rpc_done)
 		return status;
 
+	nfs_fattr_map_and_free_names(NFS_SERVER(dir), &data->f_attr);
+
 	nfs_refresh_inode(dir, o_res->dir_attr);
 
 	if (o_res->rflags & NFS4_OPEN_RESULT_CONFIRM) {
@@ -1606,6 +1614,8 @@
 		return status;
 	}
 
+	nfs_fattr_map_and_free_names(server, &data->f_attr);
+
 	if (o_arg->open_flags & O_CREAT) {
 		update_changeattr(dir, &o_res->cinfo);
 		nfs_post_op_update_inode(dir, o_res->dir_attr);
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index dcaf693..95e92e4 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2298,7 +2298,7 @@
 	encode_getfh(xdr, &hdr);
 	encode_getfattr(xdr, args->bitmask, &hdr);
 	encode_restorefh(xdr, &hdr);
-	encode_getfattr(xdr, args->bitmask, &hdr);
+	encode_getfattr(xdr, args->dir_bitmask, &hdr);
 	encode_nops(&hdr);
 }
 
@@ -3792,7 +3792,8 @@
 }
 
 static int decode_attr_owner(struct xdr_stream *xdr, uint32_t *bitmap,
-		const struct nfs_server *server, uint32_t *uid, int may_sleep)
+		const struct nfs_server *server, uint32_t *uid,
+		struct nfs4_string *owner_name)
 {
 	uint32_t len;
 	__be32 *p;
@@ -3809,8 +3810,12 @@
 		p = xdr_inline_decode(xdr, len);
 		if (unlikely(!p))
 			goto out_overflow;
-		if (!may_sleep) {
-			/* do nothing */
+		if (owner_name != NULL) {
+			owner_name->data = kmemdup(p, len, GFP_NOWAIT);
+			if (owner_name->data != NULL) {
+				owner_name->len = len;
+				ret = NFS_ATTR_FATTR_OWNER_NAME;
+			}
 		} else if (len < XDR_MAX_NETOBJ) {
 			if (nfs_map_name_to_uid(server, (char *)p, len, uid) == 0)
 				ret = NFS_ATTR_FATTR_OWNER;
@@ -3830,7 +3835,8 @@
 }
 
 static int decode_attr_group(struct xdr_stream *xdr, uint32_t *bitmap,
-		const struct nfs_server *server, uint32_t *gid, int may_sleep)
+		const struct nfs_server *server, uint32_t *gid,
+		struct nfs4_string *group_name)
 {
 	uint32_t len;
 	__be32 *p;
@@ -3847,8 +3853,12 @@
 		p = xdr_inline_decode(xdr, len);
 		if (unlikely(!p))
 			goto out_overflow;
-		if (!may_sleep) {
-			/* do nothing */
+		if (group_name != NULL) {
+			group_name->data = kmemdup(p, len, GFP_NOWAIT);
+			if (group_name->data != NULL) {
+				group_name->len = len;
+				ret = NFS_ATTR_FATTR_GROUP_NAME;
+			}
 		} else if (len < XDR_MAX_NETOBJ) {
 			if (nfs_map_group_to_gid(server, (char *)p, len, gid) == 0)
 				ret = NFS_ATTR_FATTR_GROUP;
@@ -4285,7 +4295,7 @@
 
 static int decode_getfattr_attrs(struct xdr_stream *xdr, uint32_t *bitmap,
 		struct nfs_fattr *fattr, struct nfs_fh *fh,
-		const struct nfs_server *server, int may_sleep)
+		const struct nfs_server *server)
 {
 	int status;
 	umode_t fmode = 0;
@@ -4352,12 +4362,12 @@
 		goto xdr_error;
 	fattr->valid |= status;
 
-	status = decode_attr_owner(xdr, bitmap, server, &fattr->uid, may_sleep);
+	status = decode_attr_owner(xdr, bitmap, server, &fattr->uid, fattr->owner_name);
 	if (status < 0)
 		goto xdr_error;
 	fattr->valid |= status;
 
-	status = decode_attr_group(xdr, bitmap, server, &fattr->gid, may_sleep);
+	status = decode_attr_group(xdr, bitmap, server, &fattr->gid, fattr->group_name);
 	if (status < 0)
 		goto xdr_error;
 	fattr->valid |= status;
@@ -4398,7 +4408,7 @@
 }
 
 static int decode_getfattr_generic(struct xdr_stream *xdr, struct nfs_fattr *fattr,
-		struct nfs_fh *fh, const struct nfs_server *server, int may_sleep)
+		struct nfs_fh *fh, const struct nfs_server *server)
 {
 	__be32 *savep;
 	uint32_t attrlen,
@@ -4417,7 +4427,7 @@
 	if (status < 0)
 		goto xdr_error;
 
-	status = decode_getfattr_attrs(xdr, bitmap, fattr, fh, server, may_sleep);
+	status = decode_getfattr_attrs(xdr, bitmap, fattr, fh, server);
 	if (status < 0)
 		goto xdr_error;
 
@@ -4428,9 +4438,9 @@
 }
 
 static int decode_getfattr(struct xdr_stream *xdr, struct nfs_fattr *fattr,
-		const struct nfs_server *server, int may_sleep)
+		const struct nfs_server *server)
 {
-	return decode_getfattr_generic(xdr, fattr, NULL, server, may_sleep);
+	return decode_getfattr_generic(xdr, fattr, NULL, server);
 }
 
 /*
@@ -5711,8 +5721,7 @@
 	status = decode_open_downgrade(xdr, res);
 	if (status != 0)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -5738,8 +5747,7 @@
 	status = decode_access(xdr, res);
 	if (status != 0)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -5768,8 +5776,7 @@
 	status = decode_getfh(xdr, res->fh);
 	if (status)
 		goto out;
-	status = decode_getfattr(xdr, res->fattr, res->server
-			,!RPC_IS_ASYNC(rqstp->rq_task));
+	status = decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -5795,8 +5802,7 @@
 		goto out;
 	status = decode_getfh(xdr, res->fh);
 	if (status == 0)
-		status = decode_getfattr(xdr, res->fattr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task));
+		status = decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -5822,8 +5828,7 @@
 	status = decode_remove(xdr, &res->cinfo);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->dir_attr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->dir_attr, res->server);
 out:
 	return status;
 }
@@ -5856,14 +5861,12 @@
 	if (status)
 		goto out;
 	/* Current FH is target directory */
-	if (decode_getfattr(xdr, res->new_fattr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task)) != 0)
+	if (decode_getfattr(xdr, res->new_fattr, res->server))
 		goto out;
 	status = decode_restorefh(xdr);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->old_fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->old_fattr, res->server);
 out:
 	return status;
 }
@@ -5899,14 +5902,12 @@
 	 * Note order: OP_LINK leaves the directory as the current
 	 *             filehandle.
 	 */
-	if (decode_getfattr(xdr, res->dir_attr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task)) != 0)
+	if (decode_getfattr(xdr, res->dir_attr, res->server))
 		goto out;
 	status = decode_restorefh(xdr);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -5938,14 +5939,12 @@
 	status = decode_getfh(xdr, res->fh);
 	if (status)
 		goto out;
-	if (decode_getfattr(xdr, res->fattr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task)) != 0)
+	if (decode_getfattr(xdr, res->fattr, res->server))
 		goto out;
 	status = decode_restorefh(xdr);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->dir_fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->dir_fattr, res->server);
 out:
 	return status;
 }
@@ -5977,8 +5976,7 @@
 	status = decode_putfh(xdr);
 	if (status)
 		goto out;
-	status = decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	status = decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6076,8 +6074,7 @@
 	 * 	an ESTALE error. Shouldn't be a problem,
 	 * 	though, since fattr->valid will remain unset.
 	 */
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6108,13 +6105,11 @@
 		goto out;
 	if (decode_getfh(xdr, &res->fh) != 0)
 		goto out;
-	if (decode_getfattr(xdr, res->f_attr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task)) != 0)
+	if (decode_getfattr(xdr, res->f_attr, res->server) != 0)
 		goto out;
 	if (decode_restorefh(xdr) != 0)
 		goto out;
-	decode_getfattr(xdr, res->dir_attr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->dir_attr, res->server);
 out:
 	return status;
 }
@@ -6162,8 +6157,7 @@
 	status = decode_open(xdr, res);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->f_attr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->f_attr, res->server);
 out:
 	return status;
 }
@@ -6190,8 +6184,7 @@
 	status = decode_setattr(xdr);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6371,8 +6364,7 @@
 	if (status)
 		goto out;
 	if (res->fattr)
-		decode_getfattr(xdr, res->fattr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task));
+		decode_getfattr(xdr, res->fattr, res->server);
 	if (!status)
 		status = res->count;
 out:
@@ -6401,8 +6393,7 @@
 	if (status)
 		goto out;
 	if (res->fattr)
-		decode_getfattr(xdr, res->fattr, res->server,
-				!RPC_IS_ASYNC(rqstp->rq_task));
+		decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6561,8 +6552,7 @@
 	status = decode_delegreturn(xdr);
 	if (status != 0)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6591,8 +6581,7 @@
 		goto out;
 	xdr_enter_page(xdr, PAGE_SIZE);
 	status = decode_getfattr(xdr, &res->fs_locations->fattr,
-				 res->fs_locations->server,
-				 !RPC_IS_ASYNC(req->rq_task));
+				 res->fs_locations->server);
 out:
 	return status;
 }
@@ -6841,8 +6830,7 @@
 	status = decode_layoutcommit(xdr, rqstp, res);
 	if (status)
 		goto out;
-	decode_getfattr(xdr, res->fattr, res->server,
-			!RPC_IS_ASYNC(rqstp->rq_task));
+	decode_getfattr(xdr, res->fattr, res->server);
 out:
 	return status;
 }
@@ -6973,7 +6961,7 @@
 		goto out_overflow;
 
 	if (decode_getfattr_attrs(xdr, bitmap, entry->fattr, entry->fh,
-					entry->server, 1) < 0)
+					entry->server) < 0)
 		goto out_overflow;
 	if (entry->fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID)
 		entry->ino = entry->fattr->mounted_on_fileid;
diff --git a/include/linux/nfs_idmap.h b/include/linux/nfs_idmap.h
index ae7d6a3..308c188 100644
--- a/include/linux/nfs_idmap.h
+++ b/include/linux/nfs_idmap.h
@@ -66,6 +66,8 @@
 /* Forward declaration to make this header independent of others */
 struct nfs_client;
 struct nfs_server;
+struct nfs_fattr;
+struct nfs4_string;
 
 #ifdef CONFIG_NFS_USE_NEW_IDMAPPER
 
@@ -97,6 +99,12 @@
 
 #endif /* CONFIG_NFS_USE_NEW_IDMAPPER */
 
+void nfs_fattr_init_names(struct nfs_fattr *fattr,
+		struct nfs4_string *owner_name,
+		struct nfs4_string *group_name);
+void nfs_fattr_free_names(struct nfs_fattr *);
+void nfs_fattr_map_and_free_names(struct nfs_server *, struct nfs_fattr *);
+
 int nfs_map_name_to_uid(const struct nfs_server *, const char *, size_t, __u32 *);
 int nfs_map_group_to_gid(const struct nfs_server *, const char *, size_t, __u32 *);
 int nfs_map_uid_to_name(const struct nfs_server *, __u32, char *, size_t);
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 6c898af..a764cef 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -18,6 +18,11 @@
 /* Forward declaration for NFS v3 */
 struct nfs4_secinfo_flavors;
 
+struct nfs4_string {
+	unsigned int len;
+	char *data;
+};
+
 struct nfs_fsid {
 	uint64_t		major;
 	uint64_t		minor;
@@ -61,6 +66,8 @@
 	struct timespec		pre_ctime;	/* pre_op_attr.ctime	  */
 	unsigned long		time_start;
 	unsigned long		gencount;
+	struct nfs4_string	*owner_name;
+	struct nfs4_string	*group_name;
 };
 
 #define NFS_ATTR_FATTR_TYPE		(1U << 0)
@@ -85,6 +92,8 @@
 #define NFS_ATTR_FATTR_V4_REFERRAL	(1U << 19)	/* NFSv4 referral */
 #define NFS_ATTR_FATTR_MOUNTPOINT	(1U << 20)	/* Treat as mountpoint */
 #define NFS_ATTR_FATTR_MOUNTED_ON_FILEID		(1U << 21)
+#define NFS_ATTR_FATTR_OWNER_NAME	(1U << 22)
+#define NFS_ATTR_FATTR_GROUP_NAME	(1U << 23)
 
 #define NFS_ATTR_FATTR (NFS_ATTR_FATTR_TYPE \
 		| NFS_ATTR_FATTR_MODE \
@@ -324,6 +333,7 @@
 	const struct qstr *	name;
 	const struct nfs_server *server;	 /* Needed for ID mapping */
 	const u32 *		bitmask;
+	const u32 *		dir_bitmask;
 	__u32			claim;
 	struct nfs4_sequence_args	seq_args;
 };
@@ -342,6 +352,8 @@
 	__u32			do_recall;
 	__u64			maxsize;
 	__u32			attrset[NFS4_BITMAP_SIZE];
+	struct nfs4_string	*owner;
+	struct nfs4_string	*group_owner;
 	struct nfs4_sequence_res	seq_res;
 };
 
@@ -778,11 +790,6 @@
 	struct posix_acl *	acl_default;
 };
 
-struct nfs4_string {
-	unsigned int len;
-	char *data;
-};
-
 #ifdef CONFIG_NFS_V4
 
 typedef u64 clientid4;