2 * drivers/s390/char/tape_block.c
3 * block device frontend for tape device driver
5 * S390 and zSeries version
6 * Copyright (C) 2001,2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 * Author(s): Carsten Otte <cotte@de.ibm.com>
8 * Tuan Ngo-Anh <ngoanh@de.ibm.com>
9 * Martin Schwidefsky <schwidefsky@de.ibm.com>
10 * Stefan Bader <shbader@de.ibm.com>
13 #define KMSG_COMPONENT "tape"
14 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
17 #include <linux/module.h>
18 #include <linux/blkdev.h>
19 #include <linux/smp_lock.h>
20 #include <linux/interrupt.h>
21 #include <linux/buffer_head.h>
22 #include <linux/kernel.h>
24 #include <asm/debug.h>
26 #define TAPE_DBF_AREA tape_core_dbf
30 #define TAPEBLOCK_MAX_SEC 100
31 #define TAPEBLOCK_MIN_REQUEUE 3
34 * 2003/11/25 Stefan Bader <shbader@de.ibm.com>
36 * In 2.5/2.6 the block device request function is very likely to be called
37 * with disabled interrupts (e.g. generic_unplug_device). So the driver can't
38 * just call any function that tries to allocate CCW requests from that con-
39 * text since it might sleep. There are two choices to work around this:
40 * a) do not allocate with kmalloc but use its own memory pool
41 * b) take requests from the queue outside that context, knowing that
42 * allocation might sleep
46 * file operation structure for tape block frontend
48 static int tapeblock_open(struct block_device
*, fmode_t
);
49 static int tapeblock_release(struct gendisk
*, fmode_t
);
50 static int tapeblock_medium_changed(struct gendisk
*);
51 static int tapeblock_revalidate_disk(struct gendisk
*);
53 static const struct block_device_operations tapeblock_fops
= {
55 .open
= tapeblock_open
,
56 .release
= tapeblock_release
,
57 .media_changed
= tapeblock_medium_changed
,
58 .revalidate_disk
= tapeblock_revalidate_disk
,
61 static int tapeblock_major
= 0;
64 tapeblock_trigger_requeue(struct tape_device
*device
)
66 /* Protect against rescheduling. */
67 if (atomic_cmpxchg(&device
->blk_data
.requeue_scheduled
, 0, 1) != 0)
69 schedule_work(&device
->blk_data
.requeue_task
);
73 * Post finished request.
76 __tapeblock_end_request(struct tape_request
*ccw_req
, void *data
)
78 struct tape_device
*device
;
81 DBF_LH(6, "__tapeblock_end_request()\n");
83 device
= ccw_req
->device
;
84 req
= (struct request
*) data
;
85 blk_end_request_all(req
, (ccw_req
->rc
== 0) ? 0 : -EIO
);
87 /* Update position. */
88 device
->blk_data
.block_position
=
89 (blk_rq_pos(req
) + blk_rq_sectors(req
)) >> TAPEBLOCK_HSEC_S2B
;
91 /* We lost the position information due to an error. */
92 device
->blk_data
.block_position
= -1;
93 device
->discipline
->free_bread(ccw_req
);
94 if (!list_empty(&device
->req_queue
) ||
95 blk_peek_request(device
->blk_data
.request_queue
))
96 tapeblock_trigger_requeue(device
);
100 * Feed the tape device CCW queue with requests supplied in a list.
103 tapeblock_start_request(struct tape_device
*device
, struct request
*req
)
105 struct tape_request
* ccw_req
;
108 DBF_LH(6, "tapeblock_start_request(%p, %p)\n", device
, req
);
110 ccw_req
= device
->discipline
->bread(device
, req
);
111 if (IS_ERR(ccw_req
)) {
112 DBF_EVENT(1, "TBLOCK: bread failed\n");
113 blk_end_request_all(req
, -EIO
);
114 return PTR_ERR(ccw_req
);
116 ccw_req
->callback
= __tapeblock_end_request
;
117 ccw_req
->callback_data
= (void *) req
;
118 ccw_req
->retries
= TAPEBLOCK_RETRIES
;
120 rc
= tape_do_io_async(device
, ccw_req
);
123 * Start/enqueueing failed. No retries in
126 blk_end_request_all(req
, -EIO
);
127 device
->discipline
->free_bread(ccw_req
);
134 * Move requests from the block device request queue to the tape device ccw
138 tapeblock_requeue(struct work_struct
*work
) {
139 struct tape_blk_data
* blkdat
;
140 struct tape_device
* device
;
141 struct request_queue
* queue
;
143 struct request
* req
;
144 struct list_head
* l
;
147 blkdat
= container_of(work
, struct tape_blk_data
, requeue_task
);
148 device
= blkdat
->device
;
152 spin_lock_irq(get_ccwdev_lock(device
->cdev
));
153 queue
= device
->blk_data
.request_queue
;
155 /* Count number of requests on ccw queue. */
157 list_for_each(l
, &device
->req_queue
)
159 spin_unlock(get_ccwdev_lock(device
->cdev
));
161 spin_lock_irq(&device
->blk_data
.request_queue_lock
);
163 !blk_queue_plugged(queue
) &&
164 blk_peek_request(queue
) &&
165 nr_queued
< TAPEBLOCK_MIN_REQUEUE
167 req
= blk_fetch_request(queue
);
168 if (rq_data_dir(req
) == WRITE
) {
169 DBF_EVENT(1, "TBLOCK: Rejecting write request\n");
170 spin_unlock_irq(&device
->blk_data
.request_queue_lock
);
171 blk_end_request_all(req
, -EIO
);
172 spin_lock_irq(&device
->blk_data
.request_queue_lock
);
176 spin_unlock_irq(&device
->blk_data
.request_queue_lock
);
177 rc
= tapeblock_start_request(device
, req
);
178 spin_lock_irq(&device
->blk_data
.request_queue_lock
);
180 spin_unlock_irq(&device
->blk_data
.request_queue_lock
);
181 atomic_set(&device
->blk_data
.requeue_scheduled
, 0);
185 * Tape request queue function. Called from ll_rw_blk.c
188 tapeblock_request_fn(struct request_queue
*queue
)
190 struct tape_device
*device
;
192 device
= (struct tape_device
*) queue
->queuedata
;
193 DBF_LH(6, "tapeblock_request_fn(device=%p)\n", device
);
194 BUG_ON(device
== NULL
);
195 tapeblock_trigger_requeue(device
);
199 * This function is called for every new tapedevice
202 tapeblock_setup_device(struct tape_device
* device
)
204 struct tape_blk_data
* blkdat
;
205 struct gendisk
* disk
;
208 blkdat
= &device
->blk_data
;
209 blkdat
->device
= device
;
210 spin_lock_init(&blkdat
->request_queue_lock
);
211 atomic_set(&blkdat
->requeue_scheduled
, 0);
213 blkdat
->request_queue
= blk_init_queue(
214 tapeblock_request_fn
,
215 &blkdat
->request_queue_lock
217 if (!blkdat
->request_queue
)
220 rc
= elevator_change(blkdat
->request_queue
, "noop");
224 blk_queue_logical_block_size(blkdat
->request_queue
, TAPEBLOCK_HSEC_SIZE
);
225 blk_queue_max_hw_sectors(blkdat
->request_queue
, TAPEBLOCK_MAX_SEC
);
226 blk_queue_max_segments(blkdat
->request_queue
, -1L);
227 blk_queue_max_segment_size(blkdat
->request_queue
, -1L);
228 blk_queue_segment_boundary(blkdat
->request_queue
, -1L);
230 disk
= alloc_disk(1);
236 disk
->major
= tapeblock_major
;
237 disk
->first_minor
= device
->first_minor
;
238 disk
->fops
= &tapeblock_fops
;
239 disk
->private_data
= tape_get_device(device
);
240 disk
->queue
= blkdat
->request_queue
;
241 set_capacity(disk
, 0);
242 sprintf(disk
->disk_name
, "btibm%d",
243 device
->first_minor
/ TAPE_MINORS_PER_DEV
);
246 blkdat
->medium_changed
= 1;
247 blkdat
->request_queue
->queuedata
= tape_get_device(device
);
251 tape_get_device(device
);
252 INIT_WORK(&blkdat
->requeue_task
, tapeblock_requeue
);
257 blk_cleanup_queue(blkdat
->request_queue
);
258 blkdat
->request_queue
= NULL
;
264 tapeblock_cleanup_device(struct tape_device
*device
)
266 flush_scheduled_work();
267 tape_put_device(device
);
269 if (!device
->blk_data
.disk
) {
273 del_gendisk(device
->blk_data
.disk
);
274 device
->blk_data
.disk
->private_data
= NULL
;
275 tape_put_device(device
);
276 put_disk(device
->blk_data
.disk
);
278 device
->blk_data
.disk
= NULL
;
280 device
->blk_data
.request_queue
->queuedata
= NULL
;
281 tape_put_device(device
);
283 blk_cleanup_queue(device
->blk_data
.request_queue
);
284 device
->blk_data
.request_queue
= NULL
;
288 * Detect number of blocks of the tape.
289 * FIXME: can we extent this to detect the blocks size as well ?
292 tapeblock_revalidate_disk(struct gendisk
*disk
)
294 struct tape_device
* device
;
295 unsigned int nr_of_blks
;
298 device
= (struct tape_device
*) disk
->private_data
;
301 if (!device
->blk_data
.medium_changed
)
304 rc
= tape_mtop(device
, MTFSFM
, 1);
308 rc
= tape_mtop(device
, MTTELL
, 1);
312 pr_info("%s: Determining the size of the recorded area...\n",
313 dev_name(&device
->cdev
->dev
));
314 DBF_LH(3, "Image file ends at %d\n", rc
);
317 /* This will fail for the first file. Catch the error by checking the
319 tape_mtop(device
, MTBSF
, 1);
321 rc
= tape_mtop(device
, MTTELL
, 1);
328 DBF_LH(3, "Image file starts at %d\n", rc
);
332 pr_info("%s: The size of the recorded area is %i blocks\n",
333 dev_name(&device
->cdev
->dev
), nr_of_blks
);
334 set_capacity(device
->blk_data
.disk
,
335 nr_of_blks
*(TAPEBLOCK_HSEC_SIZE
/512));
337 device
->blk_data
.block_position
= 0;
338 device
->blk_data
.medium_changed
= 0;
343 tapeblock_medium_changed(struct gendisk
*disk
)
345 struct tape_device
*device
;
347 device
= (struct tape_device
*) disk
->private_data
;
348 DBF_LH(6, "tapeblock_medium_changed(%p) = %d\n",
349 device
, device
->blk_data
.medium_changed
);
351 return device
->blk_data
.medium_changed
;
355 * Block frontend tape device open function.
358 tapeblock_open(struct block_device
*bdev
, fmode_t mode
)
360 struct gendisk
* disk
= bdev
->bd_disk
;
361 struct tape_device
* device
;
365 device
= tape_get_device(disk
->private_data
);
367 if (device
->required_tapemarks
) {
368 DBF_EVENT(2, "TBLOCK: missing tapemarks\n");
369 pr_warning("%s: Opening the tape failed because of missing "
370 "end-of-file marks\n", dev_name(&device
->cdev
->dev
));
375 rc
= tape_open(device
);
379 rc
= tapeblock_revalidate_disk(disk
);
384 * Note: The reference to <device> is hold until the release function
387 tape_state_set(device
, TS_BLKUSE
);
392 tape_release(device
);
394 tape_put_device(device
);
400 * Block frontend tape device release function.
402 * Note: One reference to the tape device was made by the open function. So
403 * we just get the pointer here and release the reference.
406 tapeblock_release(struct gendisk
*disk
, fmode_t mode
)
408 struct tape_device
*device
= disk
->private_data
;
411 tape_state_set(device
, TS_IN_USE
);
412 tape_release(device
);
413 tape_put_device(device
);
420 * Initialize block device frontend.
427 /* Register the tape major number to the kernel */
428 rc
= register_blkdev(tapeblock_major
, "tBLK");
432 if (tapeblock_major
== 0)
433 tapeblock_major
= rc
;
438 * Deregister major for block device frontend
443 unregister_blkdev(tapeblock_major
, "tBLK");