--- /dev/null
+/*
+ drbd_req.h
+
+ This file is part of DRBD by Philipp Reisner and Lars Ellenberg.
+
+ Copyright (C) 2006-2008, LINBIT Information Technologies GmbH.
+ Copyright (C) 2006-2008, Lars Ellenberg <lars.ellenberg@linbit.com>.
+ Copyright (C) 2006-2008, Philipp Reisner <philipp.reisner@linbit.com>.
+
+ DRBD is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ DRBD is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with drbd; see the file COPYING. If not, write to
+ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _DRBD_REQ_H
+#define _DRBD_REQ_H
+
+#include <linux/module.h>
+
+#include <linux/slab.h>
+#include <linux/drbd.h>
+#include "drbd_int.h"
+
+/* The request callbacks will be called in irq context by the IDE drivers,
+ and in Softirqs/Tasklets/BH context by the SCSI drivers,
+ and by the receiver and worker in kernel-thread context.
+ Try to get the locking right :) */
+
+/*
+ * Objects of type struct drbd_request do only exist on a R_PRIMARY node, and are
+ * associated with IO requests originating from the block layer above us.
+ *
+ * There are quite a few things that may happen to a drbd request
+ * during its lifetime.
+ *
+ * It will be created.
+ * It will be marked with the intention to be
+ * submitted to local disk and/or
+ * send via the network.
+ *
+ * It has to be placed on the transfer log and other housekeeping lists,
+ * In case we have a network connection.
+ *
+ * It may be identified as a concurrent (write) request
+ * and be handled accordingly.
+ *
+ * It may me handed over to the local disk subsystem.
+ * It may be completed by the local disk subsystem,
+ * either successfully or with io-error.
+ * In case it is a READ request, and it failed locally,
+ * it may be retried remotely.
+ *
+ * It may be queued for sending.
+ * It may be handed over to the network stack,
+ * which may fail.
+ * It may be acknowledged by the "peer" according to the wire_protocol in use.
+ * this may be a negative ack.
+ * It may receive a faked ack when the network connection is lost and the
+ * transfer log is cleaned up.
+ * Sending may be canceled due to network connection loss.
+ * When it finally has outlived its time,
+ * corresponding dirty bits in the resync-bitmap may be cleared or set,
+ * it will be destroyed,
+ * and completion will be signalled to the originator,
+ * with or without "success".
+ */
+
+enum drbd_req_event {
+ CREATED,
+ TO_BE_SENT,
+ TO_BE_SUBMITTED,
+
+ /* XXX yes, now I am inconsistent...
+ * these are not "events" but "actions"
+ * oh, well... */
+ QUEUE_FOR_NET_WRITE,
+ QUEUE_FOR_NET_READ,
+ QUEUE_FOR_SEND_OOS,
+
+ /* An empty flush is queued as P_BARRIER,
+ * which will cause it to complete "successfully",
+ * even if the local disk flush failed.
+ *
+ * Just like "real" requests, empty flushes (blkdev_issue_flush()) will
+ * only see an error if neither local nor remote data is reachable. */
+ QUEUE_AS_DRBD_BARRIER,
+
+ SEND_CANCELED,
+ SEND_FAILED,
+ HANDED_OVER_TO_NETWORK,
+ OOS_HANDED_TO_NETWORK,
+ CONNECTION_LOST_WHILE_PENDING,
+ READ_RETRY_REMOTE_CANCELED,
+ RECV_ACKED_BY_PEER,
+ WRITE_ACKED_BY_PEER,
+ WRITE_ACKED_BY_PEER_AND_SIS, /* and set_in_sync */
+ CONFLICT_RESOLVED,
+ POSTPONE_WRITE,
+ NEG_ACKED,
+ BARRIER_ACKED, /* in protocol A and B */
+ DATA_RECEIVED, /* (remote read) */
+
+ COMPLETED_OK,
+ READ_COMPLETED_WITH_ERROR,
+ READ_AHEAD_COMPLETED_WITH_ERROR,
+ WRITE_COMPLETED_WITH_ERROR,
+ DISCARD_COMPLETED_NOTSUPP,
+ DISCARD_COMPLETED_WITH_ERROR,
+
+ ABORT_DISK_IO,
+ RESEND,
+ FAIL_FROZEN_DISK_IO,
+ RESTART_FROZEN_DISK_IO,
+ NOTHING,
+};
+
+/* encoding of request states for now. we don't actually need that many bits.
+ * we don't need to do atomic bit operations either, since most of the time we
+ * need to look at the connection state and/or manipulate some lists at the
+ * same time, so we should hold the request lock anyways.
+ */
+enum drbd_req_state_bits {
+ /* 3210
+ * 0000: no local possible
+ * 0001: to be submitted
+ * UNUSED, we could map: 011: submitted, completion still pending
+ * 0110: completed ok
+ * 0010: completed with error
+ * 1001: Aborted (before completion)
+ * 1x10: Aborted and completed -> free
+ */
+ __RQ_LOCAL_PENDING,
+ __RQ_LOCAL_COMPLETED,
+ __RQ_LOCAL_OK,
+ __RQ_LOCAL_ABORTED,
+
+ /* 87654
+ * 00000: no network possible
+ * 00001: to be send
+ * 00011: to be send, on worker queue
+ * 00101: sent, expecting recv_ack (B) or write_ack (C)
+ * 11101: sent,
+ * recv_ack (B) or implicit "ack" (A),
+ * still waiting for the barrier ack.
+ * master_bio may already be completed and invalidated.
+ * 11100: write acked (C),
+ * data received (for remote read, any protocol)
+ * or finally the barrier ack has arrived (B,A)...
+ * request can be freed
+ * 01100: neg-acked (write, protocol C)
+ * or neg-d-acked (read, any protocol)
+ * or killed from the transfer log
+ * during cleanup after connection loss
+ * request can be freed
+ * 01000: canceled or send failed...
+ * request can be freed
+ */
+
+ /* if "SENT" is not set, yet, this can still fail or be canceled.
+ * if "SENT" is set already, we still wait for an Ack packet.
+ * when cleared, the master_bio may be completed.
+ * in (B,A) the request object may still linger on the transaction log
+ * until the corresponding barrier ack comes in */
+ __RQ_NET_PENDING,
+
+ /* If it is QUEUED, and it is a WRITE, it is also registered in the
+ * transfer log. Currently we need this flag to avoid conflicts between
+ * worker canceling the request and tl_clear_barrier killing it from
+ * transfer log. We should restructure the code so this conflict does
+ * no longer occur. */
+ __RQ_NET_QUEUED,
+
+ /* well, actually only "handed over to the network stack".
+ *
+ * TODO can potentially be dropped because of the similar meaning
+ * of RQ_NET_SENT and ~RQ_NET_QUEUED.
+ * however it is not exactly the same. before we drop it
+ * we must ensure that we can tell a request with network part
+ * from a request without, regardless of what happens to it. */
+ __RQ_NET_SENT,
+
+ /* when set, the request may be freed (if RQ_NET_QUEUED is clear).
+ * basically this means the corresponding P_BARRIER_ACK was received */
+ __RQ_NET_DONE,
+
+ /* whether or not we know (C) or pretend (B,A) that the write
+ * was successfully written on the peer.
+ */
+ __RQ_NET_OK,
+
+ /* peer called drbd_set_in_sync() for this write */
+ __RQ_NET_SIS,
+
+ /* keep this last, its for the RQ_NET_MASK */
+ __RQ_NET_MAX,
+
+ /* Set when this is a write, clear for a read */
+ __RQ_WRITE,
+
+ /* Should call drbd_al_complete_io() for this request... */
+ __RQ_IN_ACT_LOG,
+
+ /* The peer has sent a retry ACK */
+ __RQ_POSTPONED,
+
+ /* would have been completed,
+ * but was not, because of drbd_suspended() */
+ __RQ_COMPLETION_SUSP,
+
+ /* We expect a receive ACK (wire proto B) */
+ __RQ_EXP_RECEIVE_ACK,
+
+ /* We expect a write ACK (wite proto C) */
+ __RQ_EXP_WRITE_ACK,
+
+ /* waiting for a barrier ack, did an extra kref_get */
+ __RQ_EXP_BARR_ACK,
+};
+
+#define RQ_LOCAL_PENDING (1UL << __RQ_LOCAL_PENDING)
+#define RQ_LOCAL_COMPLETED (1UL << __RQ_LOCAL_COMPLETED)
+#define RQ_LOCAL_OK (1UL << __RQ_LOCAL_OK)
+#define RQ_LOCAL_ABORTED (1UL << __RQ_LOCAL_ABORTED)
+
+#define RQ_LOCAL_MASK ((RQ_LOCAL_ABORTED << 1)-1)
+
+#define RQ_NET_PENDING (1UL << __RQ_NET_PENDING)
+#define RQ_NET_QUEUED (1UL << __RQ_NET_QUEUED)
+#define RQ_NET_SENT (1UL << __RQ_NET_SENT)
+#define RQ_NET_DONE (1UL << __RQ_NET_DONE)
+#define RQ_NET_OK (1UL << __RQ_NET_OK)
+#define RQ_NET_SIS (1UL << __RQ_NET_SIS)
+
+/* 0x1f8 */
+#define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK)
+
+#define RQ_WRITE (1UL << __RQ_WRITE)
+#define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG)
+#define RQ_POSTPONED (1UL << __RQ_POSTPONED)
+#define RQ_COMPLETION_SUSP (1UL << __RQ_COMPLETION_SUSP)
+#define RQ_EXP_RECEIVE_ACK (1UL << __RQ_EXP_RECEIVE_ACK)
+#define RQ_EXP_WRITE_ACK (1UL << __RQ_EXP_WRITE_ACK)
+#define RQ_EXP_BARR_ACK (1UL << __RQ_EXP_BARR_ACK)
+
+/* For waking up the frozen transfer log mod_req() has to return if the request
+ should be counted in the epoch object*/
+#define MR_WRITE 1
+#define MR_READ 2
+
+static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
+{
+ struct bio *bio;
+ bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */
+
+ req->private_bio = bio;
+
+ bio->bi_private = req;
+ bio->bi_end_io = drbd_request_endio;
+ bio->bi_next = NULL;
+}
+
+/* Short lived temporary struct on the stack.
+ * We could squirrel the error to be returned into
+ * bio->bi_iter.bi_size, or similar. But that would be too ugly. */
+struct bio_and_error {
+ struct bio *bio;
+ int error;
+};
+
+extern void start_new_tl_epoch(struct drbd_connection *connection);
+extern void drbd_req_destroy(struct kref *kref);
+extern void _req_may_be_done(struct drbd_request *req,
+ struct bio_and_error *m);
+extern int __req_mod(struct drbd_request *req, enum drbd_req_event what,
+ struct bio_and_error *m);
+extern void complete_master_bio(struct drbd_device *device,
+ struct bio_and_error *m);
+extern void request_timer_fn(unsigned long data);
+extern void tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
+extern void _tl_restart(struct drbd_connection *connection, enum drbd_req_event what);
+extern void tl_abort_disk_io(struct drbd_device *device);
+
+/* this is in drbd_main.c */
+extern void drbd_restart_request(struct drbd_request *req);
+
+/* use this if you don't want to deal with calling complete_master_bio()
+ * outside the spinlock, e.g. when walking some list on cleanup. */
+static inline int _req_mod(struct drbd_request *req, enum drbd_req_event what)
+{
+ struct drbd_device *device = req->device;
+ struct bio_and_error m;
+ int rv;
+
+ /* __req_mod possibly frees req, do not touch req after that! */
+ rv = __req_mod(req, what, &m);
+ if (m.bio)
+ complete_master_bio(device, &m);
+
+ return rv;
+}
+
+/* completion of master bio is outside of our spinlock.
+ * We still may or may not be inside some irqs disabled section
+ * of the lower level driver completion callback, so we need to
+ * spin_lock_irqsave here. */
+static inline int req_mod(struct drbd_request *req,
+ enum drbd_req_event what)
+{
+ unsigned long flags;
+ struct drbd_device *device = req->device;
+ struct bio_and_error m;
+ int rv;
+
+ spin_lock_irqsave(&device->resource->req_lock, flags);
+ rv = __req_mod(req, what, &m);
+ spin_unlock_irqrestore(&device->resource->req_lock, flags);
+
+ if (m.bio)
+ complete_master_bio(device, &m);
+
+ return rv;
+}
+
+static inline bool drbd_should_do_remote(union drbd_dev_state s)
+{
+ return s.pdsk == D_UP_TO_DATE ||
+ (s.pdsk >= D_INCONSISTENT &&
+ s.conn >= C_WF_BITMAP_T &&
+ s.conn < C_AHEAD);
+ /* Before proto 96 that was >= CONNECTED instead of >= C_WF_BITMAP_T.
+ That is equivalent since before 96 IO was frozen in the C_WF_BITMAP*
+ states. */
+}
+static inline bool drbd_should_send_out_of_sync(union drbd_dev_state s)
+{
+ return s.conn == C_AHEAD || s.conn == C_WF_BITMAP_S;
+ /* pdsk = D_INCONSISTENT as a consequence. Protocol 96 check not necessary
+ since we enter state C_AHEAD only if proto >= 96 */
+}
+
+#endif
Code Review / kvmfornfv.git / blobdiff