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diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
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+/*
+ 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/autoconf.h>
+#include <linux/module.h>
+
+#include <linux/slab.h>
+#include <linux/drbd.h>
+#include "drbd_int.h"
+#include "drbd_wrappers.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 sucessfully 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_send,
+ to_be_submitted,
+
+ /* XXX yes, now I am inconsistent...
+ * these two are not "events" but "actions"
+ * oh, well... */
+ queue_for_net_write,
+ queue_for_net_read,
+
+ send_canceled,
+ send_failed,
+ handed_over_to_network,
+ connection_lost_while_pending,
+ recv_acked_by_peer,
+ write_acked_by_peer,
+ write_acked_by_peer_and_sis, /* and set_in_sync */
+ conflict_discarded_by_peer,
+ neg_acked,
+ barrier_acked, /* in protocol A and B */
+ data_received, /* (remote read) */
+
+ read_completed_with_error,
+ read_ahead_completed_with_error,
+ write_completed_with_error,
+ completed_ok,
+ nothing, /* for tracing only */
+};
+
+/* 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 {
+ /* 210
+ * 000: no local possible
+ * 001: to be submitted
+ * UNUSED, we could map: 011: submitted, completion still pending
+ * 110: completed ok
+ * 010: completed with error
+ */
+ __RQ_LOCAL_PENDING,
+ __RQ_LOCAL_COMPLETED,
+ __RQ_LOCAL_OK,
+
+ /* 76543
+ * 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,
+};
+
+#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_MASK ((RQ_LOCAL_OK << 1)-1) /* 0x07 */
+
+#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)
+
+/* epoch entries */
+static inline
+struct hlist_head *ee_hash_slot(struct drbd_conf *mdev, sector_t sector)
+{
+ BUG_ON(mdev->ee_hash_s == 0);
+ return mdev->ee_hash +
+ ((unsigned int)(sector>>HT_SHIFT) % mdev->ee_hash_s);
+}
+
+/* transfer log (drbd_request objects) */
+static inline
+struct hlist_head *tl_hash_slot(struct drbd_conf *mdev, sector_t sector)
+{
+ BUG_ON(mdev->tl_hash_s == 0);
+ return mdev->tl_hash +
+ ((unsigned int)(sector>>HT_SHIFT) % mdev->tl_hash_s);
+}
+
+/* application reads (drbd_request objects) */
+static struct hlist_head *ar_hash_slot(struct drbd_conf *mdev, sector_t sector)
+{
+ return mdev->app_reads_hash
+ + ((unsigned int)(sector) % APP_R_HSIZE);
+}
+
+/* when we receive the answer for a read request,
+ * verify that we actually know about it */
+static inline struct drbd_request *_ar_id_to_req(struct drbd_conf *mdev,
+ u64 id, sector_t sector)
+{
+ struct hlist_head *slot = ar_hash_slot(mdev, sector);
+ struct hlist_node *n;
+ struct drbd_request *req;
+
+ hlist_for_each_entry(req, n, slot, colision) {
+ if ((unsigned long)req == (unsigned long)id) {
+ D_ASSERT(req->sector == sector);
+ return req;
+ }
+ }
+ return NULL;
+}
+
+static inline struct drbd_request *drbd_req_new(struct drbd_conf *mdev,
+ struct bio *bio_src)
+{
+ struct bio *bio;
+ struct drbd_request *req =
+ mempool_alloc(drbd_request_mempool, GFP_NOIO);
+ if (likely(req)) {
+ bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */
+
+ req->rq_state = 0;
+ req->mdev = mdev;
+ req->master_bio = bio_src;
+ req->private_bio = bio;
+ req->epoch = 0;
+ req->sector = bio->bi_sector;
+ req->size = bio->bi_size;
+ req->start_time = jiffies;
+ INIT_HLIST_NODE(&req->colision);
+ INIT_LIST_HEAD(&req->tl_requests);
+ INIT_LIST_HEAD(&req->w.list);
+
+ bio->bi_private = req;
+ bio->bi_end_io = drbd_endio_pri;
+ bio->bi_next = NULL;
+ }
+ return req;
+}
+
+static inline void drbd_req_free(struct drbd_request *req)
+{
+ mempool_free(req, drbd_request_mempool);
+}
+
+static inline int overlaps(sector_t s1, int l1, sector_t s2, int l2)
+{
+ return !((s1 + (l1>>9) <= s2) || (s1 >= s2 + (l2>>9)));
+}
+
+/* Short lived temporary struct on the stack.
+ * We could squirrel the error to be returned into
+ * bio->bi_size, or similar. But that would be too ugly. */
+struct bio_and_error {
+ struct bio *bio;
+ int error;
+};
+
+extern void _req_may_be_done(struct drbd_request *req,
+ struct bio_and_error *m);
+extern void __req_mod(struct drbd_request *req, enum drbd_req_event what,
+ struct bio_and_error *m);
+extern void complete_master_bio(struct drbd_conf *mdev,
+ struct bio_and_error *m);
+
+/* 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 void _req_mod(struct drbd_request *req, enum drbd_req_event what)
+{
+ struct drbd_conf *mdev = req->mdev;
+ struct bio_and_error m;
+
+ /* __req_mod possibly frees req, do not touch req after that! */
+ __req_mod(req, what, &m);
+ if (m.bio)
+ complete_master_bio(mdev, &m);
+}
+
+/* completion of master bio is outside of spinlock.
+ * If you need it irqsave, do it your self! */
+static inline void req_mod(struct drbd_request *req,
+ enum drbd_req_event what)
+{
+ struct drbd_conf *mdev = req->mdev;
+ struct bio_and_error m;
+ spin_lock_irq(&mdev->req_lock);
+ __req_mod(req, what, &m);
+ spin_unlock_irq(&mdev->req_lock);
+
+ if (m.bio)
+ complete_master_bio(mdev, &m);
+}
+#endif
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