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authorRusty Russell <rusty@rustcorp.com.au>2007-07-19 04:49:29 -0400
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-19 13:04:53 -0400
commitb754416bfe9adac6468e45fba244d77f52048aeb (patch)
tree0d57784c3864fafa811ab87e0d968eabb0502e37 /drivers/block/lguest_blk.c
parentd503e2fa5aecef99675c5a81b61321a5407bf61f (diff)
lguest: the block driver
Lguest block driver A simple block driver for lguest. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Andi Kleen <ak@suse.de> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/lguest_blk.c')
-rw-r--r--drivers/block/lguest_blk.c275
1 files changed, 275 insertions, 0 deletions
diff --git a/drivers/block/lguest_blk.c b/drivers/block/lguest_blk.c
new file mode 100644
index 000000000000..1634c2dd25ec
--- /dev/null
+++ b/drivers/block/lguest_blk.c
@@ -0,0 +1,275 @@
1/* A simple block driver for lguest.
2 *
3 * Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19//#define DEBUG
20#include <linux/init.h>
21#include <linux/types.h>
22#include <linux/blkdev.h>
23#include <linux/interrupt.h>
24#include <linux/lguest_bus.h>
25
26static char next_block_index = 'a';
27
28struct blockdev
29{
30 spinlock_t lock;
31
32 /* The disk structure for the kernel. */
33 struct gendisk *disk;
34
35 /* The major number for this disk. */
36 int major;
37 int irq;
38
39 unsigned long phys_addr;
40 /* The mapped block page. */
41 struct lguest_block_page *lb_page;
42
43 /* We only have a single request outstanding at a time. */
44 struct lguest_dma dma;
45 struct request *req;
46};
47
48/* Jens gave me this nice helper to end all chunks of a request. */
49static void end_entire_request(struct request *req, int uptodate)
50{
51 if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
52 BUG();
53 add_disk_randomness(req->rq_disk);
54 blkdev_dequeue_request(req);
55 end_that_request_last(req, uptodate);
56}
57
58static irqreturn_t lgb_irq(int irq, void *_bd)
59{
60 struct blockdev *bd = _bd;
61 unsigned long flags;
62
63 if (!bd->req) {
64 pr_debug("No work!\n");
65 return IRQ_NONE;
66 }
67
68 if (!bd->lb_page->result) {
69 pr_debug("No result!\n");
70 return IRQ_NONE;
71 }
72
73 spin_lock_irqsave(&bd->lock, flags);
74 end_entire_request(bd->req, bd->lb_page->result == 1);
75 bd->req = NULL;
76 bd->dma.used_len = 0;
77 blk_start_queue(bd->disk->queue);
78 spin_unlock_irqrestore(&bd->lock, flags);
79 return IRQ_HANDLED;
80}
81
82static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
83{
84 unsigned int i = 0, idx, len = 0;
85 struct bio *bio;
86
87 rq_for_each_bio(bio, req) {
88 struct bio_vec *bvec;
89 bio_for_each_segment(bvec, bio, idx) {
90 BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
91 BUG_ON(!bvec->bv_len);
92 dma->addr[i] = page_to_phys(bvec->bv_page)
93 + bvec->bv_offset;
94 dma->len[i] = bvec->bv_len;
95 len += bvec->bv_len;
96 i++;
97 }
98 }
99 if (i < LGUEST_MAX_DMA_SECTIONS)
100 dma->len[i] = 0;
101 return len;
102}
103
104static void empty_dma(struct lguest_dma *dma)
105{
106 dma->len[0] = 0;
107}
108
109static void setup_req(struct blockdev *bd,
110 int type, struct request *req, struct lguest_dma *dma)
111{
112 bd->lb_page->type = type;
113 bd->lb_page->sector = req->sector;
114 bd->lb_page->result = 0;
115 bd->req = req;
116 bd->lb_page->bytes = req_to_dma(req, dma);
117}
118
119static void do_write(struct blockdev *bd, struct request *req)
120{
121 struct lguest_dma send;
122
123 pr_debug("lgb: WRITE sector %li\n", (long)req->sector);
124 setup_req(bd, 1, req, &send);
125
126 lguest_send_dma(bd->phys_addr, &send);
127}
128
129static void do_read(struct blockdev *bd, struct request *req)
130{
131 struct lguest_dma ping;
132
133 pr_debug("lgb: READ sector %li\n", (long)req->sector);
134 setup_req(bd, 0, req, &bd->dma);
135
136 empty_dma(&ping);
137 lguest_send_dma(bd->phys_addr, &ping);
138}
139
140static void do_lgb_request(request_queue_t *q)
141{
142 struct blockdev *bd;
143 struct request *req;
144
145again:
146 req = elv_next_request(q);
147 if (!req)
148 return;
149
150 bd = req->rq_disk->private_data;
151 /* Sometimes we get repeated requests after blk_stop_queue. */
152 if (bd->req)
153 return;
154
155 if (!blk_fs_request(req)) {
156 pr_debug("Got non-command 0x%08x\n", req->cmd_type);
157 req->errors++;
158 end_entire_request(req, 0);
159 goto again;
160 }
161
162 if (rq_data_dir(req) == WRITE)
163 do_write(bd, req);
164 else
165 do_read(bd, req);
166
167 /* Wait for interrupt to tell us it's done. */
168 blk_stop_queue(q);
169}
170
171static struct block_device_operations lguestblk_fops = {
172 .owner = THIS_MODULE,
173};
174
175static int lguestblk_probe(struct lguest_device *lgdev)
176{
177 struct blockdev *bd;
178 int err;
179 int irqflags = IRQF_SHARED;
180
181 bd = kmalloc(sizeof(*bd), GFP_KERNEL);
182 if (!bd)
183 return -ENOMEM;
184
185 spin_lock_init(&bd->lock);
186 bd->irq = lgdev_irq(lgdev);
187 bd->req = NULL;
188 bd->dma.used_len = 0;
189 bd->dma.len[0] = 0;
190 bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT);
191
192 bd->lb_page = lguest_map(bd->phys_addr, 1);
193 if (!bd->lb_page) {
194 err = -ENOMEM;
195 goto out_free_bd;
196 }
197
198 bd->major = register_blkdev(0, "lguestblk");
199 if (bd->major < 0) {
200 err = bd->major;
201 goto out_unmap;
202 }
203
204 bd->disk = alloc_disk(1);
205 if (!bd->disk) {
206 err = -ENOMEM;
207 goto out_unregister_blkdev;
208 }
209
210 bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock);
211 if (!bd->disk->queue) {
212 err = -ENOMEM;
213 goto out_put_disk;
214 }
215
216 /* We can only handle a certain number of sg entries */
217 blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS);
218 /* Buffers must not cross page boundaries */
219 blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1);
220
221 sprintf(bd->disk->disk_name, "lgb%c", next_block_index++);
222 if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
223 irqflags |= IRQF_SAMPLE_RANDOM;
224 err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd);
225 if (err)
226 goto out_cleanup_queue;
227
228 err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq);
229 if (err)
230 goto out_free_irq;
231
232 bd->disk->major = bd->major;
233 bd->disk->first_minor = 0;
234 bd->disk->private_data = bd;
235 bd->disk->fops = &lguestblk_fops;
236 /* This is initialized to the disk size by the other end. */
237 set_capacity(bd->disk, bd->lb_page->num_sectors);
238 add_disk(bd->disk);
239
240 printk(KERN_INFO "%s: device %i at major %d\n",
241 bd->disk->disk_name, lgdev->index, bd->major);
242
243 lgdev->private = bd;
244 return 0;
245
246out_free_irq:
247 free_irq(bd->irq, bd);
248out_cleanup_queue:
249 blk_cleanup_queue(bd->disk->queue);
250out_put_disk:
251 put_disk(bd->disk);
252out_unregister_blkdev:
253 unregister_blkdev(bd->major, "lguestblk");
254out_unmap:
255 lguest_unmap(bd->lb_page);
256out_free_bd:
257 kfree(bd);
258 return err;
259}
260
261static struct lguest_driver lguestblk_drv = {
262 .name = "lguestblk",
263 .owner = THIS_MODULE,
264 .device_type = LGUEST_DEVICE_T_BLOCK,
265 .probe = lguestblk_probe,
266};
267
268static __init int lguestblk_init(void)
269{
270 return register_lguest_driver(&lguestblk_drv);
271}
272module_init(lguestblk_init);
273
274MODULE_DESCRIPTION("Lguest block driver");
275MODULE_LICENSE("GPL");