path: root/drivers/block/drbd/drbd_req.c

/*
   drbd_req.c

   This file is part of DRBD by Philipp Reisner and Lars Ellenberg.

   Copyright (C) 2001-2008, LINBIT Information Technologies GmbH.
   Copyright (C) 1999-2008, Philipp Reisner <philipp.reisner@linbit.com>.
   Copyright (C) 2002-2008, Lars Ellenberg <lars.ellenberg@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.

 */

#include <linux/module.h>

#include <linux/slab.h>
#include <linux/drbd.h>
#include "drbd_int.h"
#include "drbd_req.h"


static bool drbd_may_do_local_read(struct drbd_device *device, sector_t sector, int size);

/* Update disk stats at start of I/O request */
static void _drbd_start_io_acct(struct drbd_device *device, struct drbd_request *req)
{
	generic_start_io_acct(bio_data_dir(req->master_bio), req->i.size >> 9,
			      &device->vdisk->part0);
}

/* Update disk stats when completing request upwards */
static void _drbd_end_io_acct(struct drbd_device *device, struct drbd_request *req)
{
	generic_end_io_acct(bio_data_dir(req->master_bio),
			    &device->vdisk->part0, req->start_jif);
}

static struct drbd_request *drbd_req_new(struct drbd_device *device,
					       struct bio *bio_src)
{
	struct drbd_request *req;

	req = mempool_alloc(drbd_request_mempool, GFP_NOIO);
	if (!req)
		return NULL;
	memset(req, 0, sizeof(*req));

	drbd_req_make_private_bio(req, bio_src);
	req->rq_state    = bio_data_dir(bio_src) == WRITE ? RQ_WRITE : 0;
	req->device   = device;
	req->master_bio  = bio_src;
	req->epoch       = 0;

	drbd_clear_interval(&req->i);
	req->i.sector     = bio_src->bi_iter.bi_sector;
	req->i.size      = bio_src->bi_iter.bi_size;
	req->i.local = true;
	req->i.waiting = false;

	INIT_LIST_HEAD(&req->tl_requests);
	INIT_LIST_HEAD(&req->w.list);
	INIT_LIST_HEAD(&req->req_pending_master_completion);
	INIT_LIST_HEAD(&req->req_pending_local);

	/* one reference to be put by __drbd_make_request */
	atomic_set(&req->completion_ref, 1);
	/* one kref as long as completion_ref > 0 */
	kref_init(&req->kref);
	return req;
}

static void drbd_remove_request_interval(struct rb_root *root,
					 struct drbd_request *req)
{
	struct drbd_device *device = req->device;
	struct drbd_interval *i = &req->i;

	drbd_remove_interval(root, i);

	/* Wake up any processes waiting for this request to complete.  */
	if (i->waiting)
		wake_up(&device->misc_wait);
}

void drbd_req_destroy(struct kref *kref)
{
	struct drbd_request *req = container_of(kref, struct drbd_request, kref);
	struct drbd_device *device = req->device;
	const unsigned s = req->rq_state;

	if ((req->master_bio && !(s & RQ_POSTPONED)) ||
		atomic_read(&req->completion_ref) ||
		(s & RQ_LOCAL_PENDING) ||
		((s & RQ_NET_MASK) && !(s & RQ_NET_DONE))) {
		drbd_err(device, "drbd_req_destroy: Logic BUG rq_state = 0x%x, completion_ref = %d\n",
				s, atomic_read(&req->completion_ref));
		return;
	}

	/* If called from mod_rq_state (expected normal case) or
	 * drbd_send_and_submit (the less likely normal path), this holds the
	 * req_lock, and req->tl_requests will typicaly be on ->transfer_log,
	 * though it may be still empty (never added to the transfer log).
	 *
	 * If called from do_retry(), we do NOT hold the req_lock, but we are
	 * still allowed to unconditionally list_del(&req->tl_requests),
	 * because it will be on a local on-stack list only. */
	list_del_init(&req->tl_requests);

	/* finally remove the request from the conflict detection
	 * respective block_id verification interval tree. */
	if (!drbd_interval_empty(&req->i)) {
		struct rb_root *root;

		if (s & RQ_WRITE)
			root = &device->write_requests;
		else
			root = &device->read_requests;
		drbd_remove_request_interval(root, req);
	} else if (s & (RQ_NET_MASK & ~RQ_NET_DONE) &a