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Commit 97ea4998 authored by Pavel Shilovsky's avatar Pavel Shilovsky Committed by Steve French
Browse files

CIFS: Check for reconnects before sending compound requests 



The reconnect might have happended after we obtained credits
and before we acquired srv_mutex. Check for that under the mutex
and retry a sync operation if the reconnect is detected.

Signed-off-by: default avatarPavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 3349c3a7

fs/cifs/transport.c

+36 −2
Original line number Diff line number Diff line
@@ -843,6 +843,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, 
		{ .value = 0, .instance = 0 }

	};

	unsigned int instance;

	unsigned int first_instance = 0;

	char *buf;



	timeout = flags & CIFS_TIMEOUT_MASK;
@@ -870,6 +871,25 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, 
	for (i = 0; i < num_rqst; i++) {

		rc = wait_for_free_request(ses->server, timeout, optype,

					   &instance);



		if (rc == 0) {

			credits[i].value = 1;

			credits[i].instance = instance;

			/*

			 * All parts of the compound chain must get credits from

			 * the same session, otherwise we may end up using more

			 * credits than the server granted. If there were

			 * reconnects in between, return -EAGAIN and let callers

			 * handle it.

			 */

			if (i == 0)

				first_instance = instance;

			else if (first_instance != instance) {

				i++;

				rc = -EAGAIN;

			}

		}



		if (rc) {

			/*

			 * We haven't sent an SMB packet to the server yet but
@@ -884,8 +904,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, 
				add_credits(ses->server, &credits[j], optype);

			return rc;

		}

		credits[i].value = 1;

		credits[i].instance = instance;

	}



	/*
@@ -896,6 +914,22 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, 


	mutex_lock(&ses->server->srv_mutex);



	/*

	 * All the parts of the compound chain belong obtained credits from the

	 * same session (see the appropriate checks above). In the same time

	 * there might be reconnects after those checks but before we acquired

	 * the srv_mutex. We can not use credits obtained from the previous

	 * session to send this request. Check if there were reconnects after

	 * we obtained credits and return -EAGAIN in such cases to let callers

	 * handle it.

	 */

	if (first_instance != ses->server->reconnect_instance) {

		mutex_unlock(&ses->server->srv_mutex);

		for (j = 0; j < num_rqst; j++)

			add_credits(ses->server, &credits[j], optype);

		return -EAGAIN;

	}



	for (i = 0; i < num_rqst; i++) {

		midQ[i] = ses->server->ops->setup_request(ses, &rqst[i]);

		if (IS_ERR(midQ[i])) {