/* 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" #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 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_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