346 lines
11 KiB
C
346 lines
11 KiB
C
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/*
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drbd_req.h
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This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
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Copyright (C) 2006-2008, LINBIT Information Technologies GmbH.
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Copyright (C) 2006-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
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Copyright (C) 2006-2008, Philipp Reisner <philipp.reisner@linbit.com>.
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DRBD is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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DRBD is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with drbd; see the file COPYING. If not, write to
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the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef _DRBD_REQ_H
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#define _DRBD_REQ_H
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/drbd.h>
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#include "drbd_int.h"
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/* The request callbacks will be called in irq context by the IDE drivers,
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and in Softirqs/Tasklets/BH context by the SCSI drivers,
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and by the receiver and worker in kernel-thread context.
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Try to get the locking right :) */
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/*
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* Objects of type struct drbd_request do only exist on a R_PRIMARY node, and are
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* associated with IO requests originating from the block layer above us.
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*
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* There are quite a few things that may happen to a drbd request
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* during its lifetime.
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*
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* It will be created.
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* It will be marked with the intention to be
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* submitted to local disk and/or
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* send via the network.
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*
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* It has to be placed on the transfer log and other housekeeping lists,
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* In case we have a network connection.
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*
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* It may be identified as a concurrent (write) request
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* and be handled accordingly.
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*
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* It may me handed over to the local disk subsystem.
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* It may be completed by the local disk subsystem,
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* either successfully or with io-error.
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* In case it is a READ request, and it failed locally,
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* it may be retried remotely.
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*
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* It may be queued for sending.
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* It may be handed over to the network stack,
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* which may fail.
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* It may be acknowledged by the "peer" according to the wire_protocol in use.
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* this may be a negative ack.
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* It may receive a faked ack when the network connection is lost and the
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* transfer log is cleaned up.
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* Sending may be canceled due to network connection loss.
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* When it finally has outlived its time,
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* corresponding dirty bits in the resync-bitmap may be cleared or set,
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* it will be destroyed,
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* and completion will be signalled to the originator,
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* with or without "success".
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*/
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enum drbd_req_event {
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CREATED,
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TO_BE_SENT,
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TO_BE_SUBMITTED,
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/* XXX yes, now I am inconsistent...
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* these are not "events" but "actions"
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* oh, well... */
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QUEUE_FOR_NET_WRITE,
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QUEUE_FOR_NET_READ,
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QUEUE_FOR_SEND_OOS,
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/* An empty flush is queued as P_BARRIER,
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* which will cause it to complete "successfully",
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* even if the local disk flush failed.
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*
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* Just like "real" requests, empty flushes (blkdev_issue_flush()) will
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* only see an error if neither local nor remote data is reachable. */
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QUEUE_AS_DRBD_BARRIER,
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SEND_CANCELED,
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SEND_FAILED,
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HANDED_OVER_TO_NETWORK,
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OOS_HANDED_TO_NETWORK,
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CONNECTION_LOST_WHILE_PENDING,
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READ_RETRY_REMOTE_CANCELED,
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RECV_ACKED_BY_PEER,
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WRITE_ACKED_BY_PEER,
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WRITE_ACKED_BY_PEER_AND_SIS, /* and set_in_sync */
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CONFLICT_RESOLVED,
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POSTPONE_WRITE,
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NEG_ACKED,
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BARRIER_ACKED, /* in protocol A and B */
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DATA_RECEIVED, /* (remote read) */
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COMPLETED_OK,
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READ_COMPLETED_WITH_ERROR,
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READ_AHEAD_COMPLETED_WITH_ERROR,
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WRITE_COMPLETED_WITH_ERROR,
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DISCARD_COMPLETED_NOTSUPP,
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DISCARD_COMPLETED_WITH_ERROR,
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ABORT_DISK_IO,
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RESEND,
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FAIL_FROZEN_DISK_IO,
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RESTART_FROZEN_DISK_IO,
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NOTHING,
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};
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/* encoding of request states for now. we don't actually need that many bits.
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* we don't need to do atomic bit operations either, since most of the time we
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* need to look at the connection state and/or manipulate some lists at the
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* same time, so we should hold the request lock anyways.
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*/
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enum drbd_req_state_bits {
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/* 3210
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* 0000: no local possible
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* 0001: to be submitted
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* UNUSED, we could map: 011: submitted, completion still pending
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* 0110: completed ok
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* 0010: completed with error
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* 1001: Aborted (before completion)
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* 1x10: Aborted and completed -> free
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*/
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__RQ_LOCAL_PENDING,
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__RQ_LOCAL_COMPLETED,
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__RQ_LOCAL_OK,
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__RQ_LOCAL_ABORTED,
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/* 87654
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* 00000: no network possible
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* 00001: to be send
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* 00011: to be send, on worker queue
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* 00101: sent, expecting recv_ack (B) or write_ack (C)
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* 11101: sent,
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* recv_ack (B) or implicit "ack" (A),
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* still waiting for the barrier ack.
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* master_bio may already be completed and invalidated.
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* 11100: write acked (C),
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* data received (for remote read, any protocol)
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* or finally the barrier ack has arrived (B,A)...
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* request can be freed
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* 01100: neg-acked (write, protocol C)
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* or neg-d-acked (read, any protocol)
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* or killed from the transfer log
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* during cleanup after connection loss
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* request can be freed
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* 01000: canceled or send failed...
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* request can be freed
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*/
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/* if "SENT" is not set, yet, this can still fail or be canceled.
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* if "SENT" is set already, we still wait for an Ack packet.
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* when cleared, the master_bio may be completed.
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* in (B,A) the request object may still linger on the transaction log
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* until the corresponding barrier ack comes in */
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__RQ_NET_PENDING,
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/* If it is QUEUED, and it is a WRITE, it is also registered in the
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* transfer log. Currently we need this flag to avoid conflicts between
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* worker canceling the request and tl_clear_barrier killing it from
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* transfer log. We should restructure the code so this conflict does
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* no longer occur. */
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__RQ_NET_QUEUED,
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/* well, actually only "handed over to the network stack".
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*
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* TODO can potentially be dropped because of the similar meaning
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* of RQ_NET_SENT and ~RQ_NET_QUEUED.
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* however it is not exactly the same. before we drop it
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* we must ensure that we can tell a request with network part
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* from a request without, regardless of what happens to it. */
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__RQ_NET_SENT,
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/* when set, the request may be freed (if RQ_NET_QUEUED is clear).
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* basically this means the corresponding P_BARRIER_ACK was received */
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__RQ_NET_DONE,
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/* whether or not we know (C) or pretend (B,A) that the write
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* was successfully written on the peer.
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*/
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__RQ_NET_OK,
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/* peer called drbd_set_in_sync() for this write */
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__RQ_NET_SIS,
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/* keep this last, its for the RQ_NET_MASK */
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__RQ_NET_MAX,
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/* Set when this is a write, clear for a read */
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__RQ_WRITE,
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__RQ_WSAME,
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__RQ_UNMAP,
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/* Should call drbd_al_complete_io() for this request... */
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__RQ_IN_ACT_LOG,
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/* This was the most recent request during some blk_finish_plug()
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* or its implicit from-schedule equivalent.
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* We may use it as hint to send a P_UNPLUG_REMOTE */
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__RQ_UNPLUG,
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/* The peer has sent a retry ACK */
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__RQ_POSTPONED,
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/* would have been completed,
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* but was not, because of drbd_suspended() */
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__RQ_COMPLETION_SUSP,
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/* We expect a receive ACK (wire proto B) */
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__RQ_EXP_RECEIVE_ACK,
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/* We expect a write ACK (wite proto C) */
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__RQ_EXP_WRITE_ACK,
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/* waiting for a barrier ack, did an extra kref_get */
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__RQ_EXP_BARR_ACK,
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};
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#define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING)
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#define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
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#define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK)
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#define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED)
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#define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1)
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#define RQ_NET_PENDING (1UL << __RQ_NET_PENDING)
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#define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED)
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#define RQ_NET_SENT (1UL << __RQ_NET_SENT)
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#define RQ_NET_DONE (1UL << __RQ_NET_DONE)
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#define RQ_NET_OK (1UL << __RQ_NET_OK)
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#define RQ_NET_SIS (1UL << __RQ_NET_SIS)
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#define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
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#define RQ_WRITE (1UL << __RQ_WRITE)
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#define RQ_WSAME (1UL << __RQ_WSAME)
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#define RQ_UNMAP (1UL << __RQ_UNMAP)
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#define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG)
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#define RQ_UNPLUG (1UL << __RQ_UNPLUG)
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#define RQ_POSTPONED (1UL << __RQ_POSTPONED)
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#define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP)
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#define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK)
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#define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK)
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#define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK)
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/* For waking up the frozen transfer log mod_req() has to return if the request
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should be counted in the epoch object*/
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#define MR_WRITE 1
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#define MR_READ 2
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static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
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{
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struct bio *bio;
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bio = bio_clone_fast(bio_src, GFP_NOIO, &drbd_io_bio_set);
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req->private_bio = bio;
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bio->bi_private = req;
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bio->bi_end_io = drbd_request_endio;
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bio->bi_next = NULL;
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}
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/* Short lived temporary struct on the stack.
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* We could squirrel the error to be returned into
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* bio->bi_iter.bi_size, or similar. But that would be too ugly. */
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struct bio_and_error {
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struct bio *bio;
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int error;
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};
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extern void start_new_tl_epoch(struct drbd_connection *connection);
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extern void drbd_req_destroy(struct kref *kref);
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extern void _req_may_be_done(struct drbd_request *req,
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struct bio_and_error *m);
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extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
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struct bio_and_error *m);
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extern void complete_master_bio(struct drbd_device *device,
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struct bio_and_error *m);
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extern void request_timer_fn(struct timer_list *t);
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extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
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extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
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extern void tl_abort_disk_io(struct drbd_device *device);
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/* this is in drbd_main.c */
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extern void drbd_restart_request(struct drbd_request *req);
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/* use this if you don't want to deal with calling complete_master_bio()
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* outside the spinlock, e.g. when walking some list on cleanup. */
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static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what)
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{
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struct drbd_device *device = req->device;
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struct bio_and_error m;
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int rv;
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/* __req_mod possibly frees req, do not touch req after that! */
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rv = __req_mod(req, what, &m);
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if (m.bio)
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complete_master_bio(device, &m);
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return rv;
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}
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/* completion of master bio is outside of our spinlock.
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* We still may or may not be inside some irqs disabled section
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* of the lower level driver completion callback, so we need to
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* spin_lock_irqsave here. */
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static inline int req_mod(struct drbd_request *req,
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enum drbd_req_event what)
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{
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unsigned long flags;
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struct drbd_device *device = req->device;
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struct bio_and_error m;
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int rv;
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spin_lock_irqsave(&device->resource->req_lock, flags);
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rv = __req_mod(req, what, &m);
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spin_unlock_irqrestore(&device->resource->req_lock, flags);
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if (m.bio)
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complete_master_bio(device, &m);
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return rv;
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}
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extern bool drbd_should_do_remote(union drbd_dev_state);
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#endif
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