blkmtd.c

内核linux2.4.20,可跟rtlinux3.2打补丁 组成实时linux系统,编译内核

  kfree(blocks);
#endif

  /* Tell people we have exitd */
  up(&thread_sem);
  return 0;
}


/* Add a range of pages into the outgoing write queue, making copies of them */
static int queue_page_write(mtd_raw_dev_data_t *rawdevice, struct page **pages,
			    int pagenr, int pagecnt, int iserase)
{
  struct page *outpage;
  struct page **new_pages = NULL;
  mtdblkdev_write_queue_t *item;
  int i;
  DECLARE_WAITQUEUE(wait, current);
  DEBUG(2, "blkmtd: queue_page_write: adding pagenr = %d pagecnt = %d\n", pagenr, pagecnt);

  if(!pagecnt)
    return 0;

  if(pages == NULL && !iserase)
    return -EINVAL;

  /* create a array for the list of pages */
  if(!iserase) {
    new_pages = kmalloc(pagecnt * sizeof(struct page *), GFP_KERNEL);
    if(new_pages == NULL)
      return -ENOMEM;

    /* make copies of the pages in the page cache */
    for(i = 0; i < pagecnt; i++) {
      outpage = alloc_pages(GFP_KERNEL, 0);
      if(!outpage) {
	while(i--) {
	  UnlockPage(new_pages[i]);
	  __free_pages(new_pages[i], 0);
	}
	kfree(new_pages);
	return -ENOMEM;
      }
      lock_page(outpage);
      memcpy(page_address(outpage), page_address(pages[i]), PAGE_SIZE);
      new_pages[i] = outpage;
    }
  }

  /* wait until there is some space in the write queue */
 test_lock:
  spin_lock(&mbd_writeq_lock);
  if(write_queue_cnt == write_queue_sz) {
    spin_unlock(&mbd_writeq_lock);
    DEBUG(3, "blkmtd: queue_page: Queue full\n");
    current->state = TASK_UNINTERRUPTIBLE;
    add_wait_queue(&mtbd_sync_wq, &wait);
    wake_up_interruptible(&thr_wq);
    schedule();
    current->state = TASK_RUNNING;
    remove_wait_queue(&mtbd_sync_wq, &wait);
    DEBUG(3, "blkmtd: queue_page_write: Queue has %d items in it\n", write_queue_cnt);
    goto test_lock;
  }

  DEBUG(3, "blkmtd: queue_page_write: qhead: %d qtail: %d qcnt: %d\n", 
	write_queue_head, write_queue_tail, write_queue_cnt);

  /* fix up the queue item */
  item = &write_queue[write_queue_head];
  item->pages = new_pages;
  item->pagenr = pagenr;
  item->pagecnt = pagecnt;
  item->rawdevice = rawdevice;
  item->iserase = iserase;

  write_queue_head++;
  write_queue_head %= write_queue_sz;
  write_queue_cnt++;
  DEBUG(3, "blkmtd: queue_page_write: qhead: %d qtail: %d qcnt: %d\n", 
	write_queue_head, write_queue_tail, write_queue_cnt);
  spin_unlock(&mbd_writeq_lock);
  DEBUG(2, "blkmtd: queue_page_write: finished\n");
  return 0;
}


/* erase a specified part of the device */
static int blkmtd_erase(struct mtd_info *mtd, struct erase_info *instr)
{
  mtd_raw_dev_data_t *rawdevice = mtd->priv;
  struct mtd_erase_region_info *einfo = mtd->eraseregions;
  int numregions = mtd->numeraseregions;
  size_t from;
  u_long len;
  int err = 0;

  /* check readonly */
  if(rawdevice->readonly) {
    printk("blkmtd: error: trying to erase readonly device %s\n", device);
    instr->state = MTD_ERASE_FAILED;
    goto erase_callback;
  }

  instr->state = MTD_ERASING;
  from = instr->addr;
  len = instr->len;

  /* check erase region has valid start and length */
  DEBUG(2, "blkmtd: erase: dev = `%s' from = 0x%x len = 0x%lx\n",
	bdevname(rawdevice->binding->bd_dev), from, len);
  while(numregions) {
    DEBUG(3, "blkmtd: checking erase region = 0x%08X size = 0x%X num = 0x%x\n",
	  einfo->offset, einfo->erasesize, einfo->numblocks);
    if(from >= einfo->offset && from < einfo->offset + (einfo->erasesize * einfo->numblocks)) {
      if(len == einfo->erasesize && ( (from - einfo->offset) % einfo->erasesize == 0))
	break;
    }
    numregions--;
    einfo++;
  }

  if(!numregions) {
    /* Not a valid erase block */
    printk("blkmtd: erase: invalid erase request 0x%lX @ 0x%08X\n", len, from);
    instr->state = MTD_ERASE_FAILED;
    err = -EIO;
  }
  
  if(instr->state != MTD_ERASE_FAILED) {
    /* start the erase */
    int pagenr, pagecnt;
    struct page *page, **pages;
    int i = 0;

    /* Handle the last page of the device not being whole */
    if(len < PAGE_SIZE)
      len = PAGE_SIZE;

    pagenr = from >> PAGE_SHIFT;
    pagecnt = len >> PAGE_SHIFT;
    DEBUG(3, "blkmtd: erase: pagenr = %d pagecnt = %d\n", pagenr, pagecnt);

    pages = kmalloc(pagecnt * sizeof(struct page *), GFP_KERNEL);
    if(pages == NULL) {
      err = -ENOMEM;
      instr->state = MTD_ERASE_FAILED;
      goto erase_out;
    }


    while(pagecnt) {
      /* get the page via the page cache */
      DEBUG(3, "blkmtd: erase: doing grab_cache_page() for page %d\n", pagenr);
      page = grab_cache_page(&rawdevice->as, pagenr);
      if(!page) {
	DEBUG(3, "blkmtd: erase: grab_cache_page() failed for page %d\n", pagenr);
	kfree(pages);
	err = -EIO;
	instr->state = MTD_ERASE_FAILED;
	goto erase_out;
      }
      memset(page_address(page), 0xff, PAGE_SIZE);
      pages[i] = page;
      pagecnt--;
      pagenr++;
      i++;
    }
    DEBUG(3, "blkmtd: erase: queuing page write\n");
    err = queue_page_write(rawdevice, NULL, from >> PAGE_SHIFT, len >> PAGE_SHIFT, 1);
    pagecnt = len >> PAGE_SHIFT;
    if(!err) {
      while(pagecnt--) {
	SetPageUptodate(pages[pagecnt]);
	UnlockPage(pages[pagecnt]);
	page_cache_release(pages[pagecnt]);
	flush_dcache_page(pages[pagecnt]);
      }
      kfree(pages);
      instr->state = MTD_ERASE_DONE;
    } else {
      while(pagecnt--) {
	SetPageError(pages[pagecnt]);
	page_cache_release(pages[pagecnt]);
      }
      kfree(pages);
      instr->state = MTD_ERASE_FAILED;
    }
  }
 erase_out:
  DEBUG(3, "blkmtd: erase: checking callback\n");
 erase_callback:
  if (instr->callback) {
    (*(instr->callback))(instr);
  }
  DEBUG(2, "blkmtd: erase: finished (err = %d)\n", err);
  return err;
}


/* read a range of the data via the page cache */
static int blkmtd_read(struct mtd_info *mtd, loff_t from, size_t len,
	     size_t *retlen, u_char *buf)
{
  mtd_raw_dev_data_t *rawdevice = mtd->priv;
  int err = 0;
  int offset;
  int pagenr, pages;

  *retlen = 0;

  DEBUG(2, "blkmtd: read: dev = `%s' from = %ld len = %d buf = %p\n",
	bdevname(rawdevice->binding->bd_dev), (long int)from, len, buf);

  pagenr = from >> PAGE_SHIFT;
  offset = from - (pagenr << PAGE_SHIFT);
  
  pages = (offset+len+PAGE_SIZE-1) >> PAGE_SHIFT;
  DEBUG(3, "blkmtd: read: pagenr = %d offset = %d, pages = %d\n", pagenr, offset, pages);

  /* just loop through each page, getting it via readpage() - slow but easy */
  while(pages) {
    struct page *page;
    int cpylen;
    DEBUG(3, "blkmtd: read: looking for page: %d\n", pagenr);
    page = read_cache_page(&rawdevice->as, pagenr, (filler_t *)blkmtd_readpage, rawdevice);
    if(IS_ERR(page)) {
      return PTR_ERR(page);
    }
    wait_on_page(page);
    if(!Page_Uptodate(page)) {
      /* error reading page */
      printk("blkmtd: read: page not uptodate\n");
      page_cache_release(page);
      return -EIO;
    }

    cpylen = (PAGE_SIZE > len) ? len : PAGE_SIZE;
    if(offset+cpylen > PAGE_SIZE)
      cpylen = PAGE_SIZE-offset;
    
    memcpy(buf + *retlen, page_address(page) + offset, cpylen);
    offset = 0;
    len -= cpylen;
    *retlen += cpylen;
    pagenr++;
    pages--;
    page_cache_release(page);
  }
  
  DEBUG(2, "blkmtd: end read: retlen = %d, err = %d\n", *retlen, err);
  return err;
}

    
/* write a range of the data via the page cache.
 *
 * Basic operation. break the write into three parts. 
 *
 * 1. From a page unaligned start up until the next page boundary
 * 2. Page sized, page aligned blocks
 * 3. From end of last aligned block to end of range
 *
 * 1,3 are read via the page cache and readpage() since these are partial
 * pages, 2 we just grab pages from the page cache, not caring if they are
 * already in memory or not since they will be completly overwritten.
 *
 */
 
static int blkmtd_write(struct mtd_info *mtd, loff_t to, size_t len,
	      size_t *retlen, const u_char *buf)
{
  mtd_raw_dev_data_t *rawdevice = mtd->priv;
  int err = 0;
  int offset;
  int pagenr;
  size_t len1 = 0, len2 = 0, len3 = 0;
  struct page **pages;
  int pagecnt = 0;

  *retlen = 0;
  DEBUG(2, "blkmtd: write: dev = `%s' to = %ld len = %d buf = %p\n",
	bdevname(rawdevice->binding->bd_dev), (long int)to, len, buf);

  /* handle readonly and out of range numbers */

  if(rawdevice->readonly) {
    printk("blkmtd: error: trying to write to a readonly device %s\n", device);
    return -EROFS;
  }

  if(to >= rawdevice->totalsize) {
    return -ENOSPC;
  }

  if(to + len > rawdevice->totalsize) {
    len = (rawdevice->totalsize - to);
  }


  pagenr = to >> PAGE_SHIFT;
  offset = to - (pagenr << PAGE_SHIFT);

  /* see if we have to do a partial write at the start */
  if(offset) {
    if((offset + len) > PAGE_SIZE) {
      len1 = PAGE_SIZE - offset;
      len -= len1;
    } else {
      len1 = len;
      len = 0;
    }
  }

  /* calculate the length of the other two regions */
  len3 = len & ~PAGE_MASK;
  len -= len3;
  len2 = len;


  if(len1)
    pagecnt++;
  if(len2)
    pagecnt += len2 >> PAGE_SHIFT;
  if(len3)
    pagecnt++;

  DEBUG(3, "blkmtd: write: len1 = %d len2 = %d len3 = %d pagecnt = %d\n", len1, len2, len3, pagecnt);
  
  /* get space for list of pages */
  pages = kmalloc(pagecnt * sizeof(struct page *), GFP_KERNEL);
  if(pages == NULL) {
    return -ENOMEM;
  }
  pagecnt = 0;

  if(len1) {
    /* do partial start region */
    struct page *page;
    
    DEBUG(3, "blkmtd: write: doing partial start, page = %d len = %d offset = %d\n", pagenr, len1, offset);
    page = read_cache_page(&rawdevice->as, pagenr, (filler_t *)blkmtd_readpage, rawdevice);

    if(IS_ERR(page)) {
      kfree(pages);
      return PTR_ERR(page);
    }
    memcpy(page_address(page)+offset, buf, len1);
    pages[pagecnt++] = page;
    buf += len1;
    *retlen = len1;
    err = 0;
    pagenr++;
  }

  /* Now do the main loop to a page aligned, n page sized output */
  if(len2) {
    int pagesc = len2 >> PAGE_SHIFT;
    DEBUG(3, "blkmtd: write: whole pages start = %d, count = %d\n", pagenr, pagesc);
    while(pagesc) {
      struct page *page;

      /* see if page is in the page cache */
      DEBUG(3, "blkmtd: write: grabbing page %d from page cache\n", pagenr);
      page = grab_cache_page(&rawdevice->as, pagenr);
      DEBUG(3, "blkmtd: write: got page %d from page cache\n", pagenr);
      if(!page) {
	printk("blkmtd: write: cant grab cache page %d\n", pagenr);
	err = -EIO;
	goto write_err;
      }
      memcpy(page_address(page), buf, PAGE_SIZE);
      pages[pagecnt++] = page;
      UnlockPage(page);
      SetPageUptodate(page);
      pagenr++;
      pagesc--;
      buf += PAGE_SIZE;
      *retlen += PAGE_SIZE;
    }
  }


  if(len3) {
    /* do the third region */
    struct page *page;
    DEBUG(3, "blkmtd: write: doing partial end, page = %d len = %d\n", pagenr, len3);
    page = read_cache_page(&rawdevice->as, pagenr, (filler_t *)blkmtd_readpage, rawdevice);
    if(IS_ERR(page)) {
      err = PTR_ERR(page);
      goto write_err;
    }
    memcpy(page_address(page), buf, len3);
    DEBUG(3, "blkmtd: write: writing out partial end\n");
    pages[pagecnt++] = page;
    *retlen += len3;
    err = 0;
  }
  DEBUG(2, "blkmtd: write: end, retlen = %d, err = %d\n", *retlen, err);
  /* submit it to the write task */
  err = queue_page_write(rawdevice, pages, to >> PAGE_SHIFT, pagecnt, 0);
  if(!err) {
    while(pagecnt--) {
      SetPageUptodate(pages[pagecnt]);
      flush_dcache_page(pages[pagecnt]);
      page_cache_release(pages[pagecnt]);
    }
    kfree(pages);
    return 0;
  }

 write_err:
  while(--pagecnt) {
    SetPageError(pages[pagecnt]);
    page_cache_release(pages[pagecnt]);
  }
  kfree(pages);
  return err;
}


/* sync the device - wait until the write queue is empty */
static void blkmtd_sync(struct mtd_info *mtd)
{
  DECLARE_WAITQUEUE(wait, current);
  mtd_raw_dev_data_t *rawdevice = mtd->priv;
  if(rawdevice->readonly)
    return;

  DEBUG(2, "blkmtd: sync: called\n");

 stuff_inq:
  spin_lock(&mbd_writeq_lock);
  if(write_queue_cnt) {
    spin_unlock(&mbd_writeq_lock);
    current->state = TASK_UNINTERRUPTIBLE;
    add_wait_queue(&mtbd_sync_wq, &wait);
    DEBUG(3, "blkmtd: sync: waking up task\n");
    wake_up_interruptible(&thr_wq);
    schedule();