446 lines
11 KiB
C
446 lines
11 KiB
C
/*
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* drivers/s390/char/tape_block.c
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* block device frontend for tape device driver
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*
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* S390 and zSeries version
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* Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Carsten Otte <cotte@de.ibm.com>
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* Tuan Ngo-Anh <ngoanh@de.ibm.com>
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* Martin Schwidefsky <schwidefsky@de.ibm.com>
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* Stefan Bader <shbader@de.ibm.com>
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*/
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#define KMSG_COMPONENT "tape"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/blkdev.h>
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#include <linux/smp_lock.h>
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#include <linux/interrupt.h>
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#include <linux/buffer_head.h>
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#include <linux/kernel.h>
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#include <asm/debug.h>
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#define TAPE_DBF_AREA tape_core_dbf
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#include "tape.h"
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#define TAPEBLOCK_MAX_SEC 100
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#define TAPEBLOCK_MIN_REQUEUE 3
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/*
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* 2003/11/25 Stefan Bader <shbader@de.ibm.com>
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*
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* In 2.5/2.6 the block device request function is very likely to be called
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* with disabled interrupts (e.g. generic_unplug_device). So the driver can't
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* just call any function that tries to allocate CCW requests from that con-
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* text since it might sleep. There are two choices to work around this:
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* a) do not allocate with kmalloc but use its own memory pool
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* b) take requests from the queue outside that context, knowing that
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* allocation might sleep
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*/
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/*
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* file operation structure for tape block frontend
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*/
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static int tapeblock_open(struct block_device *, fmode_t);
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static int tapeblock_release(struct gendisk *, fmode_t);
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static int tapeblock_medium_changed(struct gendisk *);
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static int tapeblock_revalidate_disk(struct gendisk *);
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static const struct block_device_operations tapeblock_fops = {
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.owner = THIS_MODULE,
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.open = tapeblock_open,
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.release = tapeblock_release,
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.media_changed = tapeblock_medium_changed,
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.revalidate_disk = tapeblock_revalidate_disk,
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};
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static int tapeblock_major = 0;
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static void
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tapeblock_trigger_requeue(struct tape_device *device)
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{
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/* Protect against rescheduling. */
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if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
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return;
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schedule_work(&device->blk_data.requeue_task);
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}
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/*
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* Post finished request.
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*/
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static void
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__tapeblock_end_request(struct tape_request *ccw_req, void *data)
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{
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struct tape_device *device;
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struct request *req;
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DBF_LH(6, "__tapeblock_end_request()\n");
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device = ccw_req->device;
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req = (struct request *) data;
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blk_end_request_all(req, (ccw_req->rc == 0) ? 0 : -EIO);
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if (ccw_req->rc == 0)
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/* Update position. */
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device->blk_data.block_position =
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(blk_rq_pos(req) + blk_rq_sectors(req)) >> TAPEBLOCK_HSEC_S2B;
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else
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/* We lost the position information due to an error. */
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device->blk_data.block_position = -1;
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device->discipline->free_bread(ccw_req);
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if (!list_empty(&device->req_queue) ||
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blk_peek_request(device->blk_data.request_queue))
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tapeblock_trigger_requeue(device);
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}
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/*
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* Feed the tape device CCW queue with requests supplied in a list.
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*/
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static int
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tapeblock_start_request(struct tape_device *device, struct request *req)
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{
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struct tape_request * ccw_req;
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int rc;
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DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
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ccw_req = device->discipline->bread(device, req);
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if (IS_ERR(ccw_req)) {
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DBF_EVENT(1, "TBLOCK: bread failed\n");
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blk_end_request_all(req, -EIO);
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return PTR_ERR(ccw_req);
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}
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ccw_req->callback = __tapeblock_end_request;
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ccw_req->callback_data = (void *) req;
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ccw_req->retries = TAPEBLOCK_RETRIES;
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rc = tape_do_io_async(device, ccw_req);
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if (rc) {
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/*
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* Start/enqueueing failed. No retries in
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* this case.
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*/
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blk_end_request_all(req, -EIO);
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device->discipline->free_bread(ccw_req);
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}
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return rc;
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}
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/*
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* Move requests from the block device request queue to the tape device ccw
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* queue.
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*/
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static void
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tapeblock_requeue(struct work_struct *work) {
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struct tape_blk_data * blkdat;
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struct tape_device * device;
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struct request_queue * queue;
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int nr_queued;
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struct request * req;
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struct list_head * l;
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int rc;
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blkdat = container_of(work, struct tape_blk_data, requeue_task);
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device = blkdat->device;
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if (!device)
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return;
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spin_lock_irq(get_ccwdev_lock(device->cdev));
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queue = device->blk_data.request_queue;
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/* Count number of requests on ccw queue. */
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nr_queued = 0;
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list_for_each(l, &device->req_queue)
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nr_queued++;
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spin_unlock(get_ccwdev_lock(device->cdev));
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spin_lock_irq(&device->blk_data.request_queue_lock);
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while (
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!blk_queue_plugged(queue) &&
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blk_peek_request(queue) &&
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nr_queued < TAPEBLOCK_MIN_REQUEUE
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) {
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req = blk_fetch_request(queue);
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if (rq_data_dir(req) == WRITE) {
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DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
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spin_unlock_irq(&device->blk_data.request_queue_lock);
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blk_end_request_all(req, -EIO);
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spin_lock_irq(&device->blk_data.request_queue_lock);
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continue;
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}
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nr_queued++;
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spin_unlock_irq(&device->blk_data.request_queue_lock);
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rc = tapeblock_start_request(device, req);
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spin_lock_irq(&device->blk_data.request_queue_lock);
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}
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spin_unlock_irq(&device->blk_data.request_queue_lock);
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atomic_set(&device->blk_data.requeue_scheduled, 0);
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}
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/*
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* Tape request queue function. Called from ll_rw_blk.c
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*/
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static void
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tapeblock_request_fn(struct request_queue *queue)
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{
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struct tape_device *device;
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device = (struct tape_device *) queue->queuedata;
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DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
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BUG_ON(device == NULL);
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tapeblock_trigger_requeue(device);
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}
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/*
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* This function is called for every new tapedevice
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*/
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int
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tapeblock_setup_device(struct tape_device * device)
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{
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struct tape_blk_data * blkdat;
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struct gendisk * disk;
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int rc;
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blkdat = &device->blk_data;
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blkdat->device = device;
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spin_lock_init(&blkdat->request_queue_lock);
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atomic_set(&blkdat->requeue_scheduled, 0);
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blkdat->request_queue = blk_init_queue(
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tapeblock_request_fn,
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&blkdat->request_queue_lock
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);
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if (!blkdat->request_queue)
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return -ENOMEM;
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elevator_exit(blkdat->request_queue->elevator);
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rc = elevator_init(blkdat->request_queue, "noop");
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if (rc)
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goto cleanup_queue;
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blk_queue_logical_block_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
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blk_queue_max_hw_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
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blk_queue_max_segments(blkdat->request_queue, -1L);
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blk_queue_max_segment_size(blkdat->request_queue, -1L);
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blk_queue_segment_boundary(blkdat->request_queue, -1L);
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disk = alloc_disk(1);
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if (!disk) {
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rc = -ENOMEM;
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goto cleanup_queue;
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}
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disk->major = tapeblock_major;
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disk->first_minor = device->first_minor;
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disk->fops = &tapeblock_fops;
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disk->private_data = tape_get_device(device);
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disk->queue = blkdat->request_queue;
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set_capacity(disk, 0);
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sprintf(disk->disk_name, "btibm%d",
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device->first_minor / TAPE_MINORS_PER_DEV);
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blkdat->disk = disk;
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blkdat->medium_changed = 1;
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blkdat->request_queue->queuedata = tape_get_device(device);
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add_disk(disk);
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tape_get_device(device);
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INIT_WORK(&blkdat->requeue_task, tapeblock_requeue);
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return 0;
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cleanup_queue:
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blk_cleanup_queue(blkdat->request_queue);
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blkdat->request_queue = NULL;
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return rc;
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}
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void
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tapeblock_cleanup_device(struct tape_device *device)
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{
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flush_scheduled_work();
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tape_put_device(device);
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if (!device->blk_data.disk) {
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goto cleanup_queue;
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}
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del_gendisk(device->blk_data.disk);
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device->blk_data.disk->private_data = NULL;
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tape_put_device(device);
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put_disk(device->blk_data.disk);
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device->blk_data.disk = NULL;
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cleanup_queue:
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device->blk_data.request_queue->queuedata = NULL;
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tape_put_device(device);
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blk_cleanup_queue(device->blk_data.request_queue);
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device->blk_data.request_queue = NULL;
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}
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/*
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* Detect number of blocks of the tape.
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* FIXME: can we extent this to detect the blocks size as well ?
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*/
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static int
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tapeblock_revalidate_disk(struct gendisk *disk)
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{
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struct tape_device * device;
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unsigned int nr_of_blks;
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int rc;
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device = (struct tape_device *) disk->private_data;
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BUG_ON(!device);
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if (!device->blk_data.medium_changed)
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return 0;
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rc = tape_mtop(device, MTFSFM, 1);
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if (rc)
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return rc;
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rc = tape_mtop(device, MTTELL, 1);
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if (rc < 0)
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return rc;
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pr_info("%s: Determining the size of the recorded area...\n",
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dev_name(&device->cdev->dev));
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DBF_LH(3, "Image file ends at %d\n", rc);
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nr_of_blks = rc;
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/* This will fail for the first file. Catch the error by checking the
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* position. */
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tape_mtop(device, MTBSF, 1);
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rc = tape_mtop(device, MTTELL, 1);
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if (rc < 0)
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return rc;
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if (rc > nr_of_blks)
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return -EINVAL;
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DBF_LH(3, "Image file starts at %d\n", rc);
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device->bof = rc;
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nr_of_blks -= rc;
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pr_info("%s: The size of the recorded area is %i blocks\n",
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dev_name(&device->cdev->dev), nr_of_blks);
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set_capacity(device->blk_data.disk,
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nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
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device->blk_data.block_position = 0;
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device->blk_data.medium_changed = 0;
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return 0;
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}
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static int
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tapeblock_medium_changed(struct gendisk *disk)
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{
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struct tape_device *device;
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device = (struct tape_device *) disk->private_data;
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DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
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device, device->blk_data.medium_changed);
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return device->blk_data.medium_changed;
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}
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/*
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* Block frontend tape device open function.
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*/
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static int
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tapeblock_open(struct block_device *bdev, fmode_t mode)
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{
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struct gendisk * disk = bdev->bd_disk;
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struct tape_device * device;
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int rc;
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lock_kernel();
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device = tape_get_device(disk->private_data);
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if (device->required_tapemarks) {
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DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
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pr_warning("%s: Opening the tape failed because of missing "
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"end-of-file marks\n", dev_name(&device->cdev->dev));
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rc = -EPERM;
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goto put_device;
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}
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rc = tape_open(device);
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if (rc)
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goto put_device;
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rc = tapeblock_revalidate_disk(disk);
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if (rc)
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goto release;
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/*
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* Note: The reference to <device> is hold until the release function
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* is called.
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*/
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tape_state_set(device, TS_BLKUSE);
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unlock_kernel();
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return 0;
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release:
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tape_release(device);
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put_device:
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tape_put_device(device);
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unlock_kernel();
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return rc;
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}
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/*
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* Block frontend tape device release function.
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*
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* Note: One reference to the tape device was made by the open function. So
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* we just get the pointer here and release the reference.
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*/
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static int
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tapeblock_release(struct gendisk *disk, fmode_t mode)
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{
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struct tape_device *device = disk->private_data;
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lock_kernel();
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tape_state_set(device, TS_IN_USE);
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tape_release(device);
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tape_put_device(device);
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unlock_kernel();
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return 0;
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}
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/*
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* Initialize block device frontend.
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*/
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int
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tapeblock_init(void)
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{
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int rc;
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/* Register the tape major number to the kernel */
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rc = register_blkdev(tapeblock_major, "tBLK");
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if (rc < 0)
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return rc;
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if (tapeblock_major == 0)
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tapeblock_major = rc;
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return 0;
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}
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/*
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* Deregister major for block device frontend
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*/
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void
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tapeblock_exit(void)
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{
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unregister_blkdev(tapeblock_major, "tBLK");
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}
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