swh:1:snp:49cd9498d6cccc5e78252c27dcb645bcf7bf0c91
Tip revision: 60d4684068ff1eec78f55b5888d0bd2d4cca1520 authored by Linus Torvalds on 28 August 2006, 03:41:48 UTC
Linux v2.6.18-rc5
Linux v2.6.18-rc5
Tip revision: 60d4684
tape_block.c
/*
* drivers/s390/char/tape_block.c
* block device frontend for tape device driver
*
* S390 and zSeries version
* Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Carsten Otte <cotte@de.ibm.com>
* Tuan Ngo-Anh <ngoanh@de.ibm.com>
* Martin Schwidefsky <schwidefsky@de.ibm.com>
* Stefan Bader <shbader@de.ibm.com>
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/buffer_head.h>
#include <asm/debug.h>
#define TAPE_DBF_AREA tape_core_dbf
#include "tape.h"
#define PRINTK_HEADER "TAPE_BLOCK: "
#define TAPEBLOCK_MAX_SEC 100
#define TAPEBLOCK_MIN_REQUEUE 3
/*
* 2003/11/25 Stefan Bader <shbader@de.ibm.com>
*
* In 2.5/2.6 the block device request function is very likely to be called
* with disabled interrupts (e.g. generic_unplug_device). So the driver can't
* just call any function that tries to allocate CCW requests from that con-
* text since it might sleep. There are two choices to work around this:
* a) do not allocate with kmalloc but use its own memory pool
* b) take requests from the queue outside that context, knowing that
* allocation might sleep
*/
/*
* file operation structure for tape block frontend
*/
static int tapeblock_open(struct inode *, struct file *);
static int tapeblock_release(struct inode *, struct file *);
static int tapeblock_ioctl(struct inode *, struct file *, unsigned int,
unsigned long);
static int tapeblock_medium_changed(struct gendisk *);
static int tapeblock_revalidate_disk(struct gendisk *);
static struct block_device_operations tapeblock_fops = {
.owner = THIS_MODULE,
.open = tapeblock_open,
.release = tapeblock_release,
.ioctl = tapeblock_ioctl,
.media_changed = tapeblock_medium_changed,
.revalidate_disk = tapeblock_revalidate_disk,
};
static int tapeblock_major = 0;
static void
tapeblock_trigger_requeue(struct tape_device *device)
{
/* Protect against rescheduling. */
if (atomic_cmpxchg(&device->blk_data.requeue_scheduled, 0, 1) != 0)
return;
schedule_work(&device->blk_data.requeue_task);
}
/*
* Post finished request.
*/
static inline void
tapeblock_end_request(struct request *req, int uptodate)
{
if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
BUG();
end_that_request_last(req, uptodate);
}
static void
__tapeblock_end_request(struct tape_request *ccw_req, void *data)
{
struct tape_device *device;
struct request *req;
DBF_LH(6, "__tapeblock_end_request()\n");
device = ccw_req->device;
req = (struct request *) data;
tapeblock_end_request(req, ccw_req->rc == 0);
if (ccw_req->rc == 0)
/* Update position. */
device->blk_data.block_position =
(req->sector + req->nr_sectors) >> TAPEBLOCK_HSEC_S2B;
else
/* We lost the position information due to an error. */
device->blk_data.block_position = -1;
device->discipline->free_bread(ccw_req);
if (!list_empty(&device->req_queue) ||
elv_next_request(device->blk_data.request_queue))
tapeblock_trigger_requeue(device);
}
/*
* Feed the tape device CCW queue with requests supplied in a list.
*/
static inline int
tapeblock_start_request(struct tape_device *device, struct request *req)
{
struct tape_request * ccw_req;
int rc;
DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device, req);
ccw_req = device->discipline->bread(device, req);
if (IS_ERR(ccw_req)) {
DBF_EVENT(1, "TBLOCK: bread failed\n");
tapeblock_end_request(req, 0);
return PTR_ERR(ccw_req);
}
ccw_req->callback = __tapeblock_end_request;
ccw_req->callback_data = (void *) req;
ccw_req->retries = TAPEBLOCK_RETRIES;
rc = tape_do_io_async(device, ccw_req);
if (rc) {
/*
* Start/enqueueing failed. No retries in
* this case.
*/
tapeblock_end_request(req, 0);
device->discipline->free_bread(ccw_req);
}
return rc;
}
/*
* Move requests from the block device request queue to the tape device ccw
* queue.
*/
static void
tapeblock_requeue(void *data) {
struct tape_device * device;
request_queue_t * queue;
int nr_queued;
struct request * req;
struct list_head * l;
int rc;
device = (struct tape_device *) data;
if (!device)
return;
spin_lock_irq(get_ccwdev_lock(device->cdev));
queue = device->blk_data.request_queue;
/* Count number of requests on ccw queue. */
nr_queued = 0;
list_for_each(l, &device->req_queue)
nr_queued++;
spin_unlock(get_ccwdev_lock(device->cdev));
spin_lock(&device->blk_data.request_queue_lock);
while (
!blk_queue_plugged(queue) &&
elv_next_request(queue) &&
nr_queued < TAPEBLOCK_MIN_REQUEUE
) {
req = elv_next_request(queue);
if (rq_data_dir(req) == WRITE) {
DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
blkdev_dequeue_request(req);
tapeblock_end_request(req, 0);
continue;
}
spin_unlock_irq(&device->blk_data.request_queue_lock);
rc = tapeblock_start_request(device, req);
spin_lock_irq(&device->blk_data.request_queue_lock);
blkdev_dequeue_request(req);
nr_queued++;
}
spin_unlock_irq(&device->blk_data.request_queue_lock);
atomic_set(&device->blk_data.requeue_scheduled, 0);
}
/*
* Tape request queue function. Called from ll_rw_blk.c
*/
static void
tapeblock_request_fn(request_queue_t *queue)
{
struct tape_device *device;
device = (struct tape_device *) queue->queuedata;
DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device);
BUG_ON(device == NULL);
tapeblock_trigger_requeue(device);
}
/*
* This function is called for every new tapedevice
*/
int
tapeblock_setup_device(struct tape_device * device)
{
struct tape_blk_data * blkdat;
struct gendisk * disk;
int rc;
blkdat = &device->blk_data;
spin_lock_init(&blkdat->request_queue_lock);
atomic_set(&blkdat->requeue_scheduled, 0);
blkdat->request_queue = blk_init_queue(
tapeblock_request_fn,
&blkdat->request_queue_lock
);
if (!blkdat->request_queue)
return -ENOMEM;
elevator_exit(blkdat->request_queue->elevator);
rc = elevator_init(blkdat->request_queue, "noop");
if (rc)
goto cleanup_queue;
blk_queue_hardsect_size(blkdat->request_queue, TAPEBLOCK_HSEC_SIZE);
blk_queue_max_sectors(blkdat->request_queue, TAPEBLOCK_MAX_SEC);
blk_queue_max_phys_segments(blkdat->request_queue, -1L);
blk_queue_max_hw_segments(blkdat->request_queue, -1L);
blk_queue_max_segment_size(blkdat->request_queue, -1L);
blk_queue_segment_boundary(blkdat->request_queue, -1L);
disk = alloc_disk(1);
if (!disk) {
rc = -ENOMEM;
goto cleanup_queue;
}
disk->major = tapeblock_major;
disk->first_minor = device->first_minor;
disk->fops = &tapeblock_fops;
disk->private_data = tape_get_device_reference(device);
disk->queue = blkdat->request_queue;
set_capacity(disk, 0);
sprintf(disk->disk_name, "btibm%d",
device->first_minor / TAPE_MINORS_PER_DEV);
blkdat->disk = disk;
blkdat->medium_changed = 1;
blkdat->request_queue->queuedata = tape_get_device_reference(device);
add_disk(disk);
INIT_WORK(&blkdat->requeue_task, tapeblock_requeue,
tape_get_device_reference(device));
return 0;
cleanup_queue:
blk_cleanup_queue(blkdat->request_queue);
blkdat->request_queue = NULL;
return rc;
}
void
tapeblock_cleanup_device(struct tape_device *device)
{
flush_scheduled_work();
device->blk_data.requeue_task.data = tape_put_device(device);
if (!device->blk_data.disk) {
PRINT_ERR("(%s): No gendisk to clean up!\n",
device->cdev->dev.bus_id);
goto cleanup_queue;
}
del_gendisk(device->blk_data.disk);
device->blk_data.disk->private_data =
tape_put_device(device->blk_data.disk->private_data);
put_disk(device->blk_data.disk);
device->blk_data.disk = NULL;
cleanup_queue:
device->blk_data.request_queue->queuedata = tape_put_device(device);
blk_cleanup_queue(device->blk_data.request_queue);
device->blk_data.request_queue = NULL;
}
/*
* Detect number of blocks of the tape.
* FIXME: can we extent this to detect the blocks size as well ?
*/
static int
tapeblock_revalidate_disk(struct gendisk *disk)
{
struct tape_device * device;
unsigned int nr_of_blks;
int rc;
device = (struct tape_device *) disk->private_data;
BUG_ON(!device);
if (!device->blk_data.medium_changed)
return 0;
PRINT_INFO("Detecting media size...\n");
rc = tape_mtop(device, MTFSFM, 1);
if (rc)
return rc;
rc = tape_mtop(device, MTTELL, 1);
if (rc < 0)
return rc;
DBF_LH(3, "Image file ends at %d\n", rc);
nr_of_blks = rc;
/* This will fail for the first file. Catch the error by checking the
* position. */
tape_mtop(device, MTBSF, 1);
rc = tape_mtop(device, MTTELL, 1);
if (rc < 0)
return rc;
if (rc > nr_of_blks)
return -EINVAL;
DBF_LH(3, "Image file starts at %d\n", rc);
device->bof = rc;
nr_of_blks -= rc;
PRINT_INFO("Found %i blocks on media\n", nr_of_blks);
set_capacity(device->blk_data.disk,
nr_of_blks*(TAPEBLOCK_HSEC_SIZE/512));
device->blk_data.block_position = 0;
device->blk_data.medium_changed = 0;
return 0;
}
static int
tapeblock_medium_changed(struct gendisk *disk)
{
struct tape_device *device;
device = (struct tape_device *) disk->private_data;
DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
device, device->blk_data.medium_changed);
return device->blk_data.medium_changed;
}
/*
* Block frontend tape device open function.
*/
static int
tapeblock_open(struct inode *inode, struct file *filp)
{
struct gendisk * disk;
struct tape_device * device;
int rc;
disk = inode->i_bdev->bd_disk;
device = tape_get_device_reference(disk->private_data);
if (device->required_tapemarks) {
DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
PRINT_ERR("TBLOCK: Refusing to open tape with missing"
" end of file marks.\n");
rc = -EPERM;
goto put_device;
}
rc = tape_open(device);
if (rc)
goto put_device;
rc = tapeblock_revalidate_disk(disk);
if (rc)
goto release;
/*
* Note: The reference to <device> is hold until the release function
* is called.
*/
tape_state_set(device, TS_BLKUSE);
return 0;
release:
tape_release(device);
put_device:
tape_put_device(device);
return rc;
}
/*
* Block frontend tape device release function.
*
* Note: One reference to the tape device was made by the open function. So
* we just get the pointer here and release the reference.
*/
static int
tapeblock_release(struct inode *inode, struct file *filp)
{
struct gendisk *disk = inode->i_bdev->bd_disk;
struct tape_device *device = disk->private_data;
tape_state_set(device, TS_IN_USE);
tape_release(device);
tape_put_device(device);
return 0;
}
/*
* Support of some generic block device IOCTLs.
*/
static int
tapeblock_ioctl(
struct inode * inode,
struct file * file,
unsigned int command,
unsigned long arg
) {
int rc;
int minor;
struct gendisk *disk;
struct tape_device *device;
rc = 0;
disk = inode->i_bdev->bd_disk;
BUG_ON(!disk);
device = disk->private_data;
BUG_ON(!device);
minor = iminor(inode);
DBF_LH(6, "tapeblock_ioctl(0x%0x)\n", command);
DBF_LH(6, "device = %d:%d\n", tapeblock_major, minor);
switch (command) {
/* Refuse some IOCTL calls without complaining (mount). */
case 0x5310: /* CDROMMULTISESSION */
rc = -EINVAL;
break;
default:
PRINT_WARN("invalid ioctl 0x%x\n", command);
rc = -EINVAL;
}
return rc;
}
/*
* Initialize block device frontend.
*/
int
tapeblock_init(void)
{
int rc;
/* Register the tape major number to the kernel */
rc = register_blkdev(tapeblock_major, "tBLK");
if (rc < 0)
return rc;
if (tapeblock_major == 0)
tapeblock_major = rc;
PRINT_INFO("tape gets major %d for block device\n", tapeblock_major);
return 0;
}
/*
* Deregister major for block device frontend
*/
void
tapeblock_exit(void)
{
unregister_blkdev(tapeblock_major, "tBLK");
}