cifs: cache FILE_ALL_INFO for the shared root handle

When we open the shared root handle also ask for FILE_ALL_INFORMATION since
we can do this at zero cost as part of a compound.
Cache this information as long as the lease is held and return and serve any
future requests from cache.

This allows us to serve "stat /<mountpoint>" directly from cache and avoid
a network roundtrip.  Since clients often want to do this quite a lot
this improve performance slightly.

As an example: xfstest generic/533 performs 43 stat operations on the root
of the share while it is run. Which are eliminated with this patch.
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/cifsglob.h

@@ -962,11 +962,14 @@ cap_unix(struct cifs_ses *ses)
 
 struct cached_fid {
 	bool is_valid:1;	/* Do we have a useable root fid */
+	bool file_all_info_is_valid:1;
+
 	struct kref refcount;
 	struct cifs_fid *fid;
 	struct mutex fid_mutex;
 	struct cifs_tcon *tcon;
 	struct work_struct lease_break;
+	struct smb2_file_all_info file_all_info;
 };
 
 /*

fs/cifs/smb2inode.c

@@ -309,12 +309,17 @@ smb2_query_path_info(const unsigned int xid, struct cifs_tcon *tcon,
 		rc = open_shroot(xid, tcon, &fid);
 		if (rc)
 			goto out;
+
+		if (tcon->crfid.file_all_info_is_valid) {
+			move_smb2_info_to_cifs(data,
+					       &tcon->crfid.file_all_info);
+		} else {
 			rc = SMB2_query_info(xid, tcon, fid.persistent_fid,
 					     fid.volatile_fid, smb2_data);
-		close_shroot(&tcon->crfid);
-		if (rc)
-			goto out;
+			if (!rc)
 				move_smb2_info_to_cifs(data, smb2_data);
+		}
+		close_shroot(&tcon->crfid);
 		goto out;
 	}
 

fs/cifs/smb2ops.c

@@ -619,6 +619,7 @@ smb2_close_cached_fid(struct kref *ref)
 		SMB2_close(0, cfid->tcon, cfid->fid->persistent_fid,
 			   cfid->fid->volatile_fid);
 		cfid->is_valid = false;
+		cfid->file_all_info_is_valid = false;
 	}
 }
 
@@ -643,9 +644,18 @@ smb2_cached_lease_break(struct work_struct *work)
  */
 int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
 {
-	struct cifs_open_parms oparams;
-	int rc;
-	__le16 srch_path = 0; /* Null - since an open of top of share */
+	struct cifs_ses *ses = tcon->ses;
+	struct TCP_Server_Info *server = ses->server;
+	struct cifs_open_parms oparms;
+	struct smb2_create_rsp *o_rsp = NULL;
+	struct smb2_query_info_rsp *qi_rsp = NULL;
+	int resp_buftype[2];
+	struct smb_rqst rqst[2];
+	struct kvec rsp_iov[2];
+	struct kvec open_iov[SMB2_CREATE_IOV_SIZE];
+	struct kvec qi_iov[1];
+	int rc, flags = 0;
+	__le16 utf16_path = 0; /* Null - since an open of top of share */
 	u8 oplock = SMB2_OPLOCK_LEVEL_II;
 
 	mutex_lock(&tcon->crfid.fid_mutex);
@@ -657,22 +667,89 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
 		return 0;
 	}
 
-	oparams.tcon = tcon;
-	oparams.create_options = 0;
-	oparams.desired_access = FILE_READ_ATTRIBUTES;
-	oparams.disposition = FILE_OPEN;
-	oparams.fid = pfid;
-	oparams.reconnect = false;
+	if (smb3_encryption_required(tcon))
+		flags |= CIFS_TRANSFORM_REQ;
+
+	memset(rqst, 0, sizeof(rqst));
+	resp_buftype[0] = resp_buftype[1] = CIFS_NO_BUFFER;
+	memset(rsp_iov, 0, sizeof(rsp_iov));
+
+	/* Open */
+	memset(&open_iov, 0, sizeof(open_iov));
+	rqst[0].rq_iov = open_iov;
+	rqst[0].rq_nvec = SMB2_CREATE_IOV_SIZE;
+
+	oparms.tcon = tcon;
+	oparms.create_options = 0;
+	oparms.desired_access = FILE_READ_ATTRIBUTES;
+	oparms.disposition = FILE_OPEN;
+	oparms.fid = pfid;
+	oparms.reconnect = false;
+
+	rc = SMB2_open_init(tcon, &rqst[0], &oplock, &oparms, &utf16_path);
+	if (rc)
+		goto oshr_exit;
+	smb2_set_next_command(tcon, &rqst[0]);
+
+	memset(&qi_iov, 0, sizeof(qi_iov));
+	rqst[1].rq_iov = qi_iov;
+	rqst[1].rq_nvec = 1;
+
+	rc = SMB2_query_info_init(tcon, &rqst[1], COMPOUND_FID,
+				  COMPOUND_FID, FILE_ALL_INFORMATION,
+				  SMB2_O_INFO_FILE, 0,
+				  sizeof(struct smb2_file_all_info) +
+				  PATH_MAX * 2, 0, NULL);
+	if (rc)
+		goto oshr_exit;
+
+	smb2_set_related(&rqst[1]);
+
+	rc = compound_send_recv(xid, ses, flags, 2, rqst,
+				resp_buftype, rsp_iov);
+	if (rc)
+		goto oshr_exit;
+
+	o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
+	oparms.fid->persistent_fid = o_rsp->PersistentFileId;
+	oparms.fid->volatile_fid = o_rsp->VolatileFileId;
+#ifdef CONFIG_CIFS_DEBUG2
+	oparms.fid->mid = le64_to_cpu(o_rsp->sync_hdr.MessageId);
+#endif /* CIFS_DEBUG2 */
+
+	if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE)
+		oplock = smb2_parse_lease_state(server, o_rsp,
+						&oparms.fid->epoch,
+						oparms.fid->lease_key);
+	else
+		goto oshr_exit;
+
 
-	rc = SMB2_open(xid, &oparams, &srch_path, &oplock, NULL, NULL, NULL);
-	if (rc == 0) {
 	memcpy(tcon->crfid.fid, pfid, sizeof(struct cifs_fid));
 	tcon->crfid.tcon = tcon;
 	tcon->crfid.is_valid = true;
 	kref_init(&tcon->crfid.refcount);
 	kref_get(&tcon->crfid.refcount);
-	}
+
+
+	qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
+	if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))
+		goto oshr_exit;
+	rc = smb2_validate_and_copy_iov(
+				le16_to_cpu(qi_rsp->OutputBufferOffset),
+				sizeof(struct smb2_file_all_info),
+				&rsp_iov[1], sizeof(struct smb2_file_all_info),
+				(char *)&tcon->crfid.file_all_info);
+	if (rc)
+		goto oshr_exit;
+	tcon->crfid.file_all_info_is_valid = 1;
+
+ oshr_exit:
 	mutex_unlock(&tcon->crfid.fid_mutex);
+	SMB2_open_free(&rqst[0]);
+	SMB2_query_info_free(&rqst[1]);
+	free_rsp_buf(resp_buftype[0], rsp_iov[0].iov_base);
+	free_rsp_buf(resp_buftype[1], rsp_iov[1].iov_base);
 	return rc;
 }
 

fs/cifs/smb2pdu.c

@@ -1797,8 +1797,9 @@ create_reconnect_durable_buf(struct cifs_fid *fid)
 	return buf;
 }
 
-static __u8
-parse_lease_state(struct TCP_Server_Info *server, struct smb2_create_rsp *rsp,
+__u8
+smb2_parse_lease_state(struct TCP_Server_Info *server,
+		       struct smb2_create_rsp *rsp,
 		       unsigned int *epoch, char *lease_key)
 {
 	char *data_offset;
@@ -2456,7 +2457,8 @@ SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
 	}
 
 	if (rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE)
-		*oplock = parse_lease_state(server, rsp, &oparms->fid->epoch,
+		*oplock = smb2_parse_lease_state(server, rsp,
+						 &oparms->fid->epoch,
 						 oparms->fid->lease_key);
 	else
 		*oplock = rsp->OplockLevel;

fs/cifs/smb2proto.h

@@ -223,6 +223,9 @@ extern int smb3_validate_negotiate(const unsigned int, struct cifs_tcon *);
 
 extern enum securityEnum smb2_select_sectype(struct TCP_Server_Info *,
 					enum securityEnum);
+extern __u8 smb2_parse_lease_state(struct TCP_Server_Info *server,
+				   struct smb2_create_rsp *rsp,
+				   unsigned int *epoch, char *lease_key);
 extern int smb3_encryption_required(const struct cifs_tcon *tcon);
 extern int smb2_validate_iov(unsigned int offset, unsigned int buffer_length,
 			     struct kvec *iov, unsigned int min_buf_size);