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12#include <linux/module.h>
13#include <linux/moduleparam.h>
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/string.h>
17#include <linux/blkdev.h>
18#include <linux/bio.h>
19#include <linux/proc_fs.h>
20#include <linux/uaccess.h>
21#include <platform/simcall.h>
22
23#define SIMDISK_MAJOR 240
24#define SIMDISK_MINORS 1
25#define MAX_SIMDISK_COUNT 10
26
27struct simdisk {
28 const char *filename;
29 spinlock_t lock;
30 struct request_queue *queue;
31 struct gendisk *gd;
32 struct proc_dir_entry *procfile;
33 int users;
34 unsigned long size;
35 int fd;
36};
37
38
39static int simdisk_count = CONFIG_BLK_DEV_SIMDISK_COUNT;
40module_param(simdisk_count, int, S_IRUGO);
41MODULE_PARM_DESC(simdisk_count, "Number of simdisk units.");
42
43static int n_files;
44static const char *filename[MAX_SIMDISK_COUNT] = {
45#ifdef CONFIG_SIMDISK0_FILENAME
46 CONFIG_SIMDISK0_FILENAME,
47#ifdef CONFIG_SIMDISK1_FILENAME
48 CONFIG_SIMDISK1_FILENAME,
49#endif
50#endif
51};
52
53static int simdisk_param_set_filename(const char *val,
54 const struct kernel_param *kp)
55{
56 if (n_files < ARRAY_SIZE(filename))
57 filename[n_files++] = val;
58 else
59 return -EINVAL;
60 return 0;
61}
62
63static const struct kernel_param_ops simdisk_param_ops_filename = {
64 .set = simdisk_param_set_filename,
65};
66module_param_cb(filename, &simdisk_param_ops_filename, &n_files, 0);
67MODULE_PARM_DESC(filename, "Backing storage filename.");
68
69static int simdisk_major = SIMDISK_MAJOR;
70
71static void simdisk_transfer(struct simdisk *dev, unsigned long sector,
72 unsigned long nsect, char *buffer, int write)
73{
74 unsigned long offset = sector << SECTOR_SHIFT;
75 unsigned long nbytes = nsect << SECTOR_SHIFT;
76
77 if (offset > dev->size || dev->size - offset < nbytes) {
78 pr_notice("Beyond-end %s (%ld %ld)\n",
79 write ? "write" : "read", offset, nbytes);
80 return;
81 }
82
83 spin_lock(&dev->lock);
84 while (nbytes > 0) {
85 unsigned long io;
86
87 simc_lseek(dev->fd, offset, SEEK_SET);
88 READ_ONCE(*buffer);
89 if (write)
90 io = simc_write(dev->fd, buffer, nbytes);
91 else
92 io = simc_read(dev->fd, buffer, nbytes);
93 if (io == -1) {
94 pr_err("SIMDISK: IO error %d\n", errno);
95 break;
96 }
97 buffer += io;
98 offset += io;
99 nbytes -= io;
100 }
101 spin_unlock(&dev->lock);
102}
103
104static blk_qc_t simdisk_make_request(struct request_queue *q, struct bio *bio)
105{
106 struct simdisk *dev = q->queuedata;
107 struct bio_vec bvec;
108 struct bvec_iter iter;
109 sector_t sector = bio->bi_iter.bi_sector;
110
111 bio_for_each_segment(bvec, bio, iter) {
112 char *buffer = kmap_atomic(bvec.bv_page) + bvec.bv_offset;
113 unsigned len = bvec.bv_len >> SECTOR_SHIFT;
114
115 simdisk_transfer(dev, sector, len, buffer,
116 bio_data_dir(bio) == WRITE);
117 sector += len;
118 kunmap_atomic(buffer);
119 }
120
121 bio_endio(bio);
122 return BLK_QC_T_NONE;
123}
124
125static int simdisk_open(struct block_device *bdev, fmode_t mode)
126{
127 struct simdisk *dev = bdev->bd_disk->private_data;
128
129 spin_lock(&dev->lock);
130 if (!dev->users)
131 check_disk_change(bdev);
132 ++dev->users;
133 spin_unlock(&dev->lock);
134 return 0;
135}
136
137static void simdisk_release(struct gendisk *disk, fmode_t mode)
138{
139 struct simdisk *dev = disk->private_data;
140 spin_lock(&dev->lock);
141 --dev->users;
142 spin_unlock(&dev->lock);
143}
144
145static const struct block_device_operations simdisk_ops = {
146 .owner = THIS_MODULE,
147 .open = simdisk_open,
148 .release = simdisk_release,
149};
150
151static struct simdisk *sddev;
152static struct proc_dir_entry *simdisk_procdir;
153
154static int simdisk_attach(struct simdisk *dev, const char *filename)
155{
156 int err = 0;
157
158 filename = kstrdup(filename, GFP_KERNEL);
159 if (filename == NULL)
160 return -ENOMEM;
161
162 spin_lock(&dev->lock);
163
164 if (dev->fd != -1) {
165 err = -EBUSY;
166 goto out;
167 }
168 dev->fd = simc_open(filename, O_RDWR, 0);
169 if (dev->fd == -1) {
170 pr_err("SIMDISK: Can't open %s: %d\n", filename, errno);
171 err = -ENODEV;
172 goto out;
173 }
174 dev->size = simc_lseek(dev->fd, 0, SEEK_END);
175 set_capacity(dev->gd, dev->size >> SECTOR_SHIFT);
176 dev->filename = filename;
177 pr_info("SIMDISK: %s=%s\n", dev->gd->disk_name, dev->filename);
178out:
179 if (err)
180 kfree(filename);
181 spin_unlock(&dev->lock);
182
183 return err;
184}
185
186static int simdisk_detach(struct simdisk *dev)
187{
188 int err = 0;
189
190 spin_lock(&dev->lock);
191
192 if (dev->users != 0) {
193 err = -EBUSY;
194 } else if (dev->fd != -1) {
195 if (simc_close(dev->fd)) {
196 pr_err("SIMDISK: error closing %s: %d\n",
197 dev->filename, errno);
198 err = -EIO;
199 } else {
200 pr_info("SIMDISK: %s detached from %s\n",
201 dev->gd->disk_name, dev->filename);
202 dev->fd = -1;
203 kfree(dev->filename);
204 dev->filename = NULL;
205 }
206 }
207 spin_unlock(&dev->lock);
208 return err;
209}
210
211static ssize_t proc_read_simdisk(struct file *file, char __user *buf,
212 size_t size, loff_t *ppos)
213{
214 struct simdisk *dev = PDE_DATA(file_inode(file));
215 const char *s = dev->filename;
216 if (s) {
217 ssize_t n = simple_read_from_buffer(buf, size, ppos,
218 s, strlen(s));
219 if (n < 0)
220 return n;
221 buf += n;
222 size -= n;
223 }
224 return simple_read_from_buffer(buf, size, ppos, "\n", 1);
225}
226
227static ssize_t proc_write_simdisk(struct file *file, const char __user *buf,
228 size_t count, loff_t *ppos)
229{
230 char *tmp = memdup_user_nul(buf, count);
231 struct simdisk *dev = PDE_DATA(file_inode(file));
232 int err;
233
234 if (IS_ERR(tmp))
235 return PTR_ERR(tmp);
236
237 err = simdisk_detach(dev);
238 if (err != 0)
239 goto out_free;
240
241 if (count > 0 && tmp[count - 1] == '\n')
242 tmp[count - 1] = 0;
243
244 if (tmp[0])
245 err = simdisk_attach(dev, tmp);
246
247 if (err == 0)
248 err = count;
249out_free:
250 kfree(tmp);
251 return err;
252}
253
254static const struct proc_ops simdisk_proc_ops = {
255 .proc_read = proc_read_simdisk,
256 .proc_write = proc_write_simdisk,
257 .proc_lseek = default_llseek,
258};
259
260static int __init simdisk_setup(struct simdisk *dev, int which,
261 struct proc_dir_entry *procdir)
262{
263 char tmp[2] = { '0' + which, 0 };
264
265 dev->fd = -1;
266 dev->filename = NULL;
267 spin_lock_init(&dev->lock);
268 dev->users = 0;
269
270 dev->queue = blk_alloc_queue(GFP_KERNEL);
271 if (dev->queue == NULL) {
272 pr_err("blk_alloc_queue failed\n");
273 goto out_alloc_queue;
274 }
275
276 blk_queue_make_request(dev->queue, simdisk_make_request);
277 dev->queue->queuedata = dev;
278
279 dev->gd = alloc_disk(SIMDISK_MINORS);
280 if (dev->gd == NULL) {
281 pr_err("alloc_disk failed\n");
282 goto out_alloc_disk;
283 }
284 dev->gd->major = simdisk_major;
285 dev->gd->first_minor = which;
286 dev->gd->fops = &simdisk_ops;
287 dev->gd->queue = dev->queue;
288 dev->gd->private_data = dev;
289 snprintf(dev->gd->disk_name, 32, "simdisk%d", which);
290 set_capacity(dev->gd, 0);
291 add_disk(dev->gd);
292
293 dev->procfile = proc_create_data(tmp, 0644, procdir, &simdisk_proc_ops, dev);
294 return 0;
295
296out_alloc_disk:
297 blk_cleanup_queue(dev->queue);
298 dev->queue = NULL;
299out_alloc_queue:
300 return -ENOMEM;
301}
302
303static int __init simdisk_init(void)
304{
305 int i;
306
307 if (register_blkdev(simdisk_major, "simdisk") < 0) {
308 pr_err("SIMDISK: register_blkdev: %d\n", simdisk_major);
309 return -EIO;
310 }
311 pr_info("SIMDISK: major: %d\n", simdisk_major);
312
313 if (n_files > simdisk_count)
314 simdisk_count = n_files;
315 if (simdisk_count > MAX_SIMDISK_COUNT)
316 simdisk_count = MAX_SIMDISK_COUNT;
317
318 sddev = kmalloc_array(simdisk_count, sizeof(*sddev), GFP_KERNEL);
319 if (sddev == NULL)
320 goto out_unregister;
321
322 simdisk_procdir = proc_mkdir("simdisk", 0);
323 if (simdisk_procdir == NULL)
324 goto out_free_unregister;
325
326 for (i = 0; i < simdisk_count; ++i) {
327 if (simdisk_setup(sddev + i, i, simdisk_procdir) == 0) {
328 if (filename[i] != NULL && filename[i][0] != 0 &&
329 (n_files == 0 || i < n_files))
330 simdisk_attach(sddev + i, filename[i]);
331 }
332 }
333
334 return 0;
335
336out_free_unregister:
337 kfree(sddev);
338out_unregister:
339 unregister_blkdev(simdisk_major, "simdisk");
340 return -ENOMEM;
341}
342module_init(simdisk_init);
343
344static void simdisk_teardown(struct simdisk *dev, int which,
345 struct proc_dir_entry *procdir)
346{
347 char tmp[2] = { '0' + which, 0 };
348
349 simdisk_detach(dev);
350 if (dev->gd)
351 del_gendisk(dev->gd);
352 if (dev->queue)
353 blk_cleanup_queue(dev->queue);
354 remove_proc_entry(tmp, procdir);
355}
356
357static void __exit simdisk_exit(void)
358{
359 int i;
360
361 for (i = 0; i < simdisk_count; ++i)
362 simdisk_teardown(sddev + i, i, simdisk_procdir);
363 remove_proc_entry("simdisk", 0);
364 kfree(sddev);
365 unregister_blkdev(simdisk_major, "simdisk");
366}
367module_exit(simdisk_exit);
368
369MODULE_ALIAS_BLOCKDEV_MAJOR(SIMDISK_MAJOR);
370
371MODULE_LICENSE("GPL");
372
