实验七(补充)sbull虚拟的磁盘驱动的编写.doc

sbull虚拟的磁盘驱动的编写 分类： EmbeddedARM/DSP. 驱动 2011-11-28 17:24 191人阅读 评论(0) 收藏 举报 原理指导：我们通过vmalloc在内存中开辟一部分空间，作为一个虚拟的磁盘，然后我们以块设备的方式来访问这片内存，例如这个sbull模型。sbull（SimpleBlockUtilityforLoadingLocalities），该驱动程序实现了一个使用系统内存的块设备，从本质上讲，属于一种RAM磁盘驱动程序。字符设备的IO操作则是直接不绕弯的，块设备的IO操作会配对和整合。驱动的任务是处理请求，对于这些请求的排队和整合的工作有IO调度算法处理。所以块设备的核心工作就是：请求处理函数或者是制造请求。Block_devices_operations结构体中没有读写一类的成员函数，而只是包含打开、释放和IO控制等函数。块设备的流程：(1)先把模块模型搭建好MODULE_LICENSE(DualBSD/GPL);staticstructblock_device_operationssbull_ops=.owner=THIS_MODULE,.open =sbull_open,.release =sbull_release,.media_changed=sbull_media_changed,.revalidate_disk=sbull_revalidate,.ioctl =sbull_ioctl,.getgeo =sbull_getgeo,;module_init(sbull_init);module_exit(sbull_exit);(2)定义一个我们用内存虚拟出来的块设备sbull_devstructsbull_devintsize;/*Devicesizeinsectors*/u8*data;/*Thedataarray*/shortusers;/*Howmanyusers*/shortmedia_change;/*Flagamediachange?*/spinlock_tlock;/*Formutualexclusion*/structrequest_queue*queue;/*Thedevicerequestqueue*/structgendisk*gd;/*Thegendiskstructure*/structtimer_listtimer;/*Forsimulatedmediachanges*/;这个设备结构体是我们工作的核心，也许你不知道需要哪些成员，不要紧，还是那句话，编写驱动的时候，需要设备表现出那些性质和功能，相应的添加上就OK了。(3)设备的初始化 sbull_init()一、sbull_major=register_blkdev(sbull_major,sbull);二、Staticstructsbull_dev*Devices=kmalloc(ndevices*sizeof(structsbull_dev),GFP_KERNEL);/在这里可以对Kmalloc的结果判断下，然后进一步处理.三、setup_device()跳到我们设备注册函数中去/初始化函数结束(4)开始注册我们的这个设备setup_device()/安装(注册)一个设备前，一定要保证它被初始化了这些成员都得出初始化好：一、intsize;/*Devicesizeinsectors*/u8*data;/*Thedataarray*/shortusers;/*Howmanyusers*/spinlock_tlock;/*Formutualexclusion*/structrequest_queue*queue;/*Thedevicerequestqueue*/structgendisk*gd;/*Thegendiskstructure*/二、add_disk(dev-gd);/这个重要的注册函数 /函数结束(5)扇区大小、data数组、user、锁lock的初始化：一、dev-size=nsectors*hardsect_size;dev-data=vmalloc(dev-size);spin_lock_init(&dev-lock);二、/dev-queue=blk_alloc_queue(GFP_KERNEL);/RM_NOQUEUE/dev-queue=blk_init_queue(sbull_full_request,&dev-lock);/RM_FULLdev-queue=blk_init_queue(sbull_request,&dev-lock);/RM_SIMPLE(6)告知内核硬件扇区尺寸、和timer模拟的初始化blk_queue_logical_block_size(dev-queue,hardsect_size);init_timer(&dev-timer);dev-timer.data=(unsignedlong)dev;dev-timer.function=sbull_invalidate;gendisk初始化一、初始化gendisk:dev-gd=alloc_disk(SBULL_MINORS);二、初始化gendisk的成员dev-gd-major=sbull_major;dev-gd-first_minor=which*SBULL_MINORS;dev-gd-fops=&sbull_ops;dev-gd-queue=dev-queue;dev-gd-private_data=dev;(7)设置gendisk容量为xxx_size个扇区大小set_capacity(dev-gd,nsectors*(hardsect_size/KERNEL_SECTOR_SIZE);(8)剩下的就是为devices_operation结构体里声明的那些接口进行实现：.open =sbull_open,.release =sbull_release,.media_changed=sbull_media_changed,.revalidate_disk =sbull_revalidate,.ioctl =sbull_ioctl,.getgeo =sbull_getgeo,一、sbull_open(structblock_device*bdev,fmode_tmode)二、sbull_release(structgendisk*bd_disk,fmode_tmode)三、sbull_media_changed(structgendisk*gd)四、sbull_revalidate(structgendisk*gd)五、sbull_invalidate(unsignedlongldev)六、sbull_ioctl(structblock_device*bdev,fmode_tmode,unsignedintcmd,unsignedlongarg)七、sbull_getgeo(structblock_device*bdev,structhd_geometry*geo)以下是代码：cpp view plaincopyprint?1. /*2. *Samplediskdriverfor2.6.35.3. */4. 5. /#include 6. #include 7. #include 8. #include 9. 10. #include 11. #include/*printk()*/ 12. #include/*kmalloc()*/ 13. #include/*everything.*/ 14. #include/*errorcodes*/ 15. #include 16. #include/*size_t*/ 17. #include/*O_ACCMODE*/ 18. #include/*HDIO_GETGEO*/ 19. #include 20. #include 21. #include 22. #include 23. #include/*invalidate_bdev*/ 24. #include 25. 26. MODULE_LICENSE(DualBSD/GPL);27. 28. staticintsbull_major=0;29. module_param(sbull_major,int,0);30. staticinthardsect_size=512;31. module_param(hardsect_size,int,0);32. staticintnsectors=25600;/*Howbigthedriveis*/33. module_param(nsectors,int,0);34. staticintndevices=1;35. module_param(ndevices,int,0);36. 37. /*38. *Thedifferentrequestmodeswecanuse.39. */40. enum41. RM_SIMPLE=0,/*Theextra-simplerequestfunction*/42. RM_FULL=1,/*Thefull-blownversion*/43. RM_NOQUEUE=2,/*Usemake_request*/44. ;45. /staticintrequest_mode=RM_FULL; 46. /staticintrequest_mode=RM_SIMPLE; 47. staticintrequest_mode=RM_NOQUEUE;48. module_param(request_mode,int,0);49. 50. /*51. *Minornumberandpartitionmanagement.52. */53. #defineSBULL_MINORS16 54. #defineMINOR_SHIFT4 55. #defineDEVNUM(kdevnum)(MINOR(kdev_t_to_nr(kdevnum)MINOR_SHIFT 56. 57. /*58. *Wecantweakourhardwaresectorsize,butthekerneltalkstous59. *intermsofsmallsectors,always.60. */61. #defineKERNEL_SECTOR_SIZE512 62. 63. /*64. *Afterthismuchidletime,thedriverwillsimulateamediachange.65. */66. #defineINVALIDATE_DELAY60*HZ 67. 68. /*69. *Theinternalrepresentationofourdevice.70. */71. structsbull_dev72. intsize;/*Devicesizeinsectors*/73. u8*data;/*Thedataarray*/74. shortusers;/*Howmanyusers*/75. shortmedia_change;/*Flagamediachange?*/76. spinlock_tlock;/*Formutualexclusion*/77. structrequest_queue*queue;/*Thedevicerequestqueue*/78. structgendisk*gd;/*Thegendiskstructure*/79. structtimer_listtimer;/*Forsimulatedmediachanges*/80. ;81. 82. staticstructsbull_dev*Devices=NULL;83. 84. /*85. *HandleanI/Orequest.86. */87. staticvoidsbull_transfer(structsbull_dev*dev,unsignedlongsector,88. unsignedlongnsect,char*buffer,intwrite)89. 90. unsignedlongoffset=sector*KERNEL_SECTOR_SIZE;91. unsignedlongnbytes=nsect*KERNEL_SECTOR_SIZE;92. /printk(in%soffset=%dnbytes=%dwrite=%dn,_FUNCTION_,offset,nbytes,write); 93. /buffer10=0; 94. /printk(buffer); 95. /printk(n); 96. if(offset+nbytes)dev-size)97. printk(KERN_NOTICEBeyond-endwrite(%ld%ld)n,offset,nbytes);98. return;99. 100. if(write)101. memcpy(dev-data+offset,buffer,nbytes);102. else103. memcpy(buffer,dev-data+offset,nbytes);104. 105. 106. /*Thesimpleformoftherequestfunction.*/107. 108. staticvoidsbull_request(structrequest_queue*q)109. 110. structrequest*req;111. 112. req=blk_fetch_request(q);113. while(req!=NULL)114. structsbull_dev*dev=req-rq_disk-private_data;115. if(!blk_fs_request(req)116. printk(KERN_NOTICESkipnon-fsrequestn);117. _blk_end_request_all(req,-EIO);118. continue;119. 120. /printk(KERN_NOTICEReqdev%ddir%ldsec%ld,nr%df%lxn, 121. /dev-Devices,rq_data_dir(req), 122. /req-sector,req-current_nr_sectors, 123. /req-flags); 124. /printk(sectors=%dn,req-current_nr_sectors); 125. sbull_transfer(dev,blk_rq_pos(req),blk_rq_cur_sectors(req),126. req-buffer,rq_data_dir(req);127. if(!_blk_end_request_cur(req,0)128. req=NULL;129. 130. 131. 132. 133. 134. /*135. *TransferasingleBIO.136. */137. staticintsbull_xfer_bio(structsbull_dev*dev,structbio*bio)138. 139. inti;140. structbio_vec*bvec;141. sector_tsector=bio-bi_sector;142. 143. /*Doeachsegmentindependently.*/144. bio_for_each_segment(bvec,bio,i)145. char*buffer=_bio_kmap_atomic(bio,i,KM_USER0);146. sbull_transfer(dev,sector,bio_cur_bytes(bio)9,147. buffer,bio_data_dir(bio)=WRITE);148. sector+=bio_cur_bytes(bio)9;149. _bio_kunmap_atomic(bio,KM_USER0);150. 151. return0;/*Alwayssucceed*/152. 153. 154. /*155. *Transferafullrequest.156. */157. staticintsbull_xfer_request(structsbull_dev*dev,structrequest*req)158. 159. structbio*bio;160. intnsect=0;161. 162. _rq_for_each_bio(bio,req)163. sbull_xfer_bio(dev,bio);164. nsect+=bio-bi_size/KERNEL_SECTOR_SIZE;165. 166. returnnsect;167. 168. 169. 170. 171. /*172. *Smarterrequestfunctionthathandlesclustering.*/173. staticvoidsbull_full_request(structrequest_queue*q)174. 175. 176. structrequest*req;177. intnsect;178. structsbull_dev*dev;179. req=blk_fetch_request(q);180. dev=req-rq_disk-private_data;181. while(req!=NULL)182. if(!blk_fs_request(req)183. printk(KERN_NOTICESkipnon-fsrequestn);184. _blk_end_request_all(req,-EIO);185. continue;186. 187. /printk(KERN_NOTICEReqdev%ddir%ldsec%ld,nr%df%lxn, 188. /dev-Devices,rq_data_dir(req), 189. /req-sector,req-current_nr_sectors, 190. /req-flags); 191. /printk(sectors=%dn,req-current_nr_sectors); 192. nsect=sbull_xfer_request(dev,req);193. _blk_end_request(req,0,(nsectqueuedata;206. intstatus;207. 208. status=sbull_xfer_bio(dev,bio);209. /bio_endio(bio,bio-bi_size,status); 210. bio_endio(bio,status);211. return0;212. 213. 214. 215. /*216. *Openandclose.217. */218. 219. staticintsbull_open(structblock_device*bdev,fmode_tmode)220. 221. structsbull_dev*dev=bdev-bd_disk-private_data;222. /printk(fdfjdlksjfdlkjn); 223. del_timer_sync(&dev-timer);224. spin_lock(&dev-lock);225. if(!dev-users)226. check_disk_change(bdev);227. dev-users+;228. spin_unlock(&dev-lock);229. return0;230. 231. 232. staticintsbull_release(structgendisk*bd_disk,fmode_tmode)233. 234. structsbull_dev*dev=bd_disk-private_data;235. 236. spin_lock(&dev-lock);237. dev-users-;238. 239. if(!dev-users)240. dev-timer.expires=jiffies+INVALIDATE_DELAY;241. add_timer(&dev-timer);242. 243. spin_unlock(&dev-lock);244. 245. return0;246. 247. 248. /*249. *Lookfora(simulated)mediachange.250. */251. intsbull_media_changed(structgendisk*gd)252. 253. structsbull_dev*dev=gd-private_data;254. 255. returndev-media_change;256. 257. 258. /*259. *Revalidate.WEDONOTTAKETHELOCKHERE,forfearofdeadlocking260. *withopen.Thatneedstobereevaluated.261. */262. intsbull_revalidate(structgendisk*gd)263. 264. structsbull_dev*dev=gd-private_data;265. 266. if(dev-media_change)267. dev-media_change=0;268. memset(dev-data,0,dev-size);269. 270. return0;271. 272. 273. /*274. *Theinvalidatefunctionrunsoutofthedevicetimer;itsets275. *aflagtosimulatetheremovalofthemedia.276. */277. voidsbull_invalidate(unsignedlongldev)278. 279. structsbull_dev*dev=(structsbull_dev*)ldev;280. 281. spin_lock(&dev-lock);282. if(dev-users|!dev-data)283. printk(KERN_WARNINGsbull:timersanitycheckfailedn);284. else285. dev-media_change=1;286. spin_unlock(&dev-lock);287. 288. 289. /*290. *Theioctl()implementation291. */292. 293. intsbull_ioctl(structblock_device*bdev,fmode_tmode,294. unsignedintcmd,unsignedlongarg)295. 296. return0;297. 298. 299. staticintsbull_getgeo(structblock_device*bdev,structhd_geometry*geo)300. 301. unsignedlongsize;302. structsbull_dev*pdev=bdev-bd_disk-private_data;303. 304. size=pdev-size;305. geo-cylinders=(size&0x3f)6;306. geo-heads=4;307. geo-sectors=16;308. geo-start=0;309. return0;310. 311. 312. 313. /*314. *Thedeviceoperationsstructure.315. */316. staticstructblock_device_operationssbull_ops=317. .owner=THIS_MODULE,318. .open=sbull_open,319. .release=sbull_release,320. .media_changed=sbull_media_changed,321. .revalidate_disk=sbull_revalidate,322. .ioctl=sbull_ioctl,323. .getgeo=sbull_getgeo,324. ;325. 326. 327. /*328. *Setupourinternaldevice.329. */330. staticvoidsetup_device(structsbull_dev*dev,intwhich)331. 332. /*333. *Getsomememory.334. */335. memset(dev,0,sizeof(structsbull_dev);336. dev-size=nsectors*hardsect_size;337. dev-data=vmalloc(dev-size);338. if(dev-data=NULL)339. printk(KERN_NOTICEvmallocfailure.n);340. return;341. 342. spin_lock_init(&dev-lock);343. 344. /*345. *Thetimerwhichinvalidatesthedevice.346. */347. init_timer(&dev-timer);348. dev-timer.data=(unsignedlong)dev;349. dev-timer.function=sbull_invalidate;350. 351. /*352. *TheI/Oqueue,dependingonwhetherweareusingourown353. *make_requestfunctionornot.354. */355. switch(request_mode)356. caseRM_NOQUEUE:357. dev-queue=blk_alloc_queue(GFP_KERNEL);358. if(dev-queue=NULL)359. gotoout_vfree;360. blk_queue_make_request(dev-queue,sbull_make_request);361. break;362. 363. caseRM_FULL:364. dev-queue=blk_init_queue(sbull_full_request,&dev-lock);365. if(dev-queue=NULL)366. gotoout_vfree;367. break;368. 369. default:370. printk(KERN_NOTICEBadrequestmode%d,usingsimplen,request_mode);371. /*fallinto.*/372. 373. caseRM_SIMPLE:374. dev-queue=blk_init_queue(sbull_request,&dev-lock);375. if(dev-queue=NULL)376. gotoout_vfree;377. break;378. 379. /blk_queue_hardsect_size(dev-queue,hardsect_size); 380. blk_queue_logical_block_size(dev-queue,hardsect_size);381. dev-queue-queuedata=dev;382. /*383. *Andthegendiskstructure.384. */385. dev-gd=alloc_disk(SBULL_MINORS);386. if(!dev-gd)387. printk(KERN_NOTICEalloc_diskfailuren);388. gotoout_vfree;389. 390. dev-gd-major=sbull_major;391. dev-gd-first_minor=which*SBULL_MINORS;392. dev-gd-fops=&sbull_ops;393. dev-gd-queue=dev-queue;394. dev-gd-private_d