diff options
Diffstat (limited to 'drivers/block/drbd/drbd_req.h')
| -rw-r--r-- | drivers/block/drbd/drbd_req.h | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h new file mode 100644 index 000000000000..d37ab57f1209 --- /dev/null +++ b/drivers/block/drbd/drbd_req.h @@ -0,0 +1,327 @@ +/* + 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 |