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Diffstat (limited to 'drivers/block/drbd/drbd_req.h')
| -rw-r--r-- | drivers/block/drbd/drbd_req.h | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h new file mode 100644 index 000000000..94c654020 --- /dev/null +++ b/drivers/block/drbd/drbd_req.h @@ -0,0 +1,345 @@ +/* + 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, + __RQ_WSAME, + __RQ_UNMAP, + + /* Should call drbd_al_complete_io() for this request... */ + __RQ_IN_ACT_LOG, + + /* This was the most recent request during some blk_finish_plug() + * or its implicit from-schedule equivalent. + * We may use it as hint to send a P_UNPLUG_REMOTE */ + __RQ_UNPLUG, + + /* 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) + +#define RQ_NET_MASK (((1UL << __RQ_NET_MAX)-1) & ~RQ_LOCAL_MASK) + +#define RQ_WRITE (1UL << __RQ_WRITE) +#define RQ_WSAME (1UL << __RQ_WSAME) +#define RQ_UNMAP (1UL << __RQ_UNMAP) +#define RQ_IN_ACT_LOG (1UL << __RQ_IN_ACT_LOG) +#define RQ_UNPLUG (1UL << __RQ_UNPLUG) +#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_fast(bio_src, GFP_NOIO, &drbd_io_bio_set); + + 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(struct timer_list *t); +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; +} + +extern bool drbd_should_do_remote(union drbd_dev_state); + +#endif |