I don't think we can do this for the cifs case - 49 blocking locks and
we would deadlock our system (a pending write could block forever) -
for smb2.2 it makes more sense. I don't think it actually causes a
problem to exceed 50 blocks locks - but if we want to count blocking
locks we will have to limit the maximum number of blocking locks to 2
or 3 less than maxmpx and not allow blocking locks if maxmpx is lower
than 3.
On Wed, Feb 22, 2012 at 1:32 AM, Pavel Shilovsky <piastry@xxxxxxxxxxx> wrote:
> to make sure we don't exceed the number of credits we have in this case.
>
> Signed-off-by: Pavel Shilovsky <piastry@xxxxxxxxxxx>
> ---
> fs/cifs/transport.c | 32 +++++++++++++++++++++-----------
> 1 files changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
> index 44ac0aa..fa93720 100644
> --- a/fs/cifs/transport.c
> +++ b/fs/cifs/transport.c
> @@ -279,15 +279,8 @@ wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
> spin_unlock(&server->req_lock);
> return -ENOENT;
> }
> -
> - /* can not count locking commands against total
> - as they are allowed to block on server */
> -
> - /* update # of requests on the wire to server */
> - if (long_op != CIFS_BLOCKING_OP) {
> - server->credits--;
> - server->in_flight++;
> - }
> + server->credits--;
> + server->in_flight++;
> spin_unlock(&server->req_lock);
> break;
> }
> @@ -816,7 +809,7 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> return -EIO;
> }
>
> - rc = wait_for_free_request(ses->server, CIFS_BLOCKING_OP);
> + rc = wait_for_free_request(ses->server, 0);
> if (rc)
> return rc;
>
> @@ -829,6 +822,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> rc = allocate_mid(ses, in_buf, &midQ);
> if (rc) {
> mutex_unlock(&ses->server->srv_mutex);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
>
> @@ -836,6 +831,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> if (rc) {
> delete_mid(midQ);
> mutex_unlock(&ses->server->srv_mutex);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
>
> @@ -848,6 +845,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
>
> if (rc < 0) {
> delete_mid(midQ);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
>
> @@ -869,6 +868,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> rc = send_nt_cancel(ses->server, in_buf, midQ);
> if (rc) {
> delete_mid(midQ);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
> } else {
> @@ -881,6 +882,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> already been removed. Don't exit in this case. */
> if (rc && rc != -ENOLCK) {
> delete_mid(midQ);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
> }
> @@ -893,6 +896,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> /* no longer considered to be "in-flight" */
> midQ->callback = DeleteMidQEntry;
> spin_unlock(&GlobalMid_Lock);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> }
> spin_unlock(&GlobalMid_Lock);
> @@ -903,8 +908,11 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> }
>
> rc = cifs_sync_mid_result(midQ, ses->server);
> - if (rc != 0)
> + if (rc != 0) {
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> return rc;
> + }
>
> /* rcvd frame is ok */
> if (out_buf == NULL || midQ->midState != MID_RESPONSE_RECEIVED) {
> @@ -918,6 +926,8 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
> rc = cifs_check_receive(midQ, ses->server, 0);
> out:
> delete_mid(midQ);
> + add_credits(ses->server, 1);
> + wake_up(&ses->server->request_q);
> if (rstart && rc == -EACCES)
> return -ERESTARTSYS;
> return rc;
> --
> 1.7.1
>
> --
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--
Thanks,
Steve
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