/*===========================================================================*
 *				rw_scattered				     *
 *===========================================================================*/
static void rw_scattered(
  dev_t dev,			/* major-minor device number */
  struct buf **bufq,		/* pointer to array of buffers */
  unsigned int bufqsize,	/* number of buffers */
  int rw_flag			/* READING or WRITING */
)
{
/* Read or write scattered data from a device. */

  register struct buf *bp;
  register iovec_t *iop;
  static iovec_t iovec[NR_IOREQS];
  off_t pos;
  unsigned int i, iov_per_block;
#if !defined(NDEBUG)
  unsigned int start_in_use = bufs_in_use, start_bufqsize = bufqsize;
#endif /* !defined(NDEBUG) */

  if(bufqsize == 0) return;

#if !defined(NDEBUG)
  /* for READING, check all buffers on the list are obtained and held
   * (count > 0)
   */
  if (rw_flag == READING) {
	assert(bufqsize <= LMFS_MAX_PREFETCH);

	for(i = 0; i < bufqsize; i++) {
		assert(bufq[i] != NULL);
		assert(bufq[i]->lmfs_count > 0);
  	}

  	/* therefore they are all 'in use' and must be at least this many */
	assert(start_in_use >= start_bufqsize);
  }

  assert(dev != NO_DEV);
  assert(fs_block_size > 0);
  assert(howmany(fs_block_size, PAGE_SIZE) <= NR_IOREQS);
#endif /* !defined(NDEBUG) */

  /* For WRITING, (Shell) sort buffers on lmfs_blocknr.
   * For READING, the buffers are already sorted.
   */
  if (rw_flag == WRITING)
	sort_blocks(bufq, bufqsize);

  /* Set up I/O vector and do I/O.  The result of bdev I/O is OK if everything
   * went fine, otherwise the error code for the first failed transfer.
   */
  while (bufqsize > 0) {
	unsigned int p, nblocks = 0, niovecs = 0;
	int r;
	for (iop = iovec; nblocks < bufqsize; nblocks++) {
		vir_bytes vdata, blockrem;
		bp = bufq[nblocks];
		if (bp->lmfs_blocknr != bufq[0]->lmfs_blocknr + nblocks)
			break;
		blockrem = bp->lmfs_bytes;
		iov_per_block = howmany(blockrem, PAGE_SIZE);
		if (niovecs > NR_IOREQS - iov_per_block) break;
		vdata = (vir_bytes) bp->data;
		for(p = 0; p < iov_per_block; p++) {
			vir_bytes chunk =
			    blockrem < PAGE_SIZE ? blockrem : PAGE_SIZE;
			iop->iov_addr = vdata;
			iop->iov_size = chunk;
			vdata += PAGE_SIZE;
			blockrem -= chunk;
			iop++;
			niovecs++;
		}
		assert(p == iov_per_block);
		assert(blockrem == 0);
	}

	assert(nblocks > 0);
	assert(niovecs > 0 && niovecs <= NR_IOREQS);

	pos = (off_t)bufq[0]->lmfs_blocknr * fs_block_size;
	if (rw_flag == READING)
		r = bdev_gather(dev, pos, iovec, niovecs, BDEV_NOFLAGS);
	else
		r = bdev_scatter(dev, pos, iovec, niovecs, BDEV_NOFLAGS);

	/* Harvest the results.  The driver may have returned an error, or it
	 * may have done less than what we asked for.
	 */
	if (r < 0) {
		printf("fs cache: I/O error %d on device %d/%d, "
		    "block %"PRIu64"\n",
		    r, major(dev), minor(dev), bufq[0]->lmfs_blocknr);
	}
	for (i = 0; i < nblocks; i++) {
		bp = bufq[i];
		if (r < (ssize_t)bp->lmfs_bytes) {
			/* Transfer failed. */
			if (i == 0) {
				bp->lmfs_dev = NO_DEV;	/* Invalidate block */
			}
			break;
		}
		if (rw_flag == READING) {
			lmfs_put_block(bp);
		} else {
			MARKCLEAN(bp);
		}
		r -= bp->lmfs_bytes;
	}

	bufq += i;
	bufqsize -= i;

	if (rw_flag == READING) {
		/* Don't bother reading more than the device is willing to
		 * give at this time.  Don't forget to release those extras.
		 */
		while (bufqsize > 0) {
			bp = *bufq++;
			bp->lmfs_dev = NO_DEV;	/* invalidate block */
			lmfs_put_block(bp);
			bufqsize--;
		}
	}
	if (rw_flag == WRITING && i == 0) {
		/* We're not making progress, this means we might keep
		 * looping. Buffers remain dirty if un-written. Buffers are
		 * lost if invalidate()d or LRU-removed while dirty. This
		 * is better than keeping unwritable blocks around forever..
		 */
		break;
	}
  }

#if !defined(NDEBUG)
  if(rw_flag == READING) {
  	assert(start_in_use >= start_bufqsize);

	/* READING callers assume all bufs are released. */
	assert(start_in_use - start_bufqsize == bufs_in_use);
  }
#endif /* !defined(NDEBUG) */
}
示例#2
0
/*===========================================================================*
 *				lmfs_rw_scattered			     *
 *===========================================================================*/
void lmfs_rw_scattered(
  dev_t dev,			/* major-minor device number */
  struct buf **bufq,		/* pointer to array of buffers */
  int bufqsize,			/* number of buffers */
  int rw_flag			/* READING or WRITING */
)
{
/* Read or write scattered data from a device. */

  register struct buf *bp;
  int gap;
  register int i;
  register iovec_t *iop;
  static iovec_t iovec[NR_IOREQS];
  off_t pos;
  int iov_per_block;
  int start_in_use = bufs_in_use, start_bufqsize = bufqsize;

  assert(bufqsize >= 0);
  if(bufqsize == 0) return;

  /* for READING, check all buffers on the list are obtained and held
   * (count > 0)
   */
  if (rw_flag == READING) {
	for(i = 0; i < bufqsize; i++) {
		assert(bufq[i] != NULL);
		assert(bufq[i]->lmfs_count > 0);
  	}

  	/* therefore they are all 'in use' and must be at least this many */
	  assert(start_in_use >= start_bufqsize);
  }

  assert(dev != NO_DEV);
  assert(fs_block_size > 0);
  iov_per_block = roundup(fs_block_size, PAGE_SIZE) / PAGE_SIZE;
  assert(iov_per_block < NR_IOREQS);
  
  /* (Shell) sort buffers on lmfs_blocknr. */
  gap = 1;
  do
	gap = 3 * gap + 1;
  while (gap <= bufqsize);
  while (gap != 1) {
  	int j;
	gap /= 3;
	for (j = gap; j < bufqsize; j++) {
		for (i = j - gap;
		     i >= 0 && bufq[i]->lmfs_blocknr > bufq[i + gap]->lmfs_blocknr;
		     i -= gap) {
			bp = bufq[i];
			bufq[i] = bufq[i + gap];
			bufq[i + gap] = bp;
		}
	}
  }

  /* Set up I/O vector and do I/O.  The result of bdev I/O is OK if everything
   * went fine, otherwise the error code for the first failed transfer.
   */
  while (bufqsize > 0) {
  	int nblocks = 0, niovecs = 0;
	int r;
	for (iop = iovec; nblocks < bufqsize; nblocks++) {
		int p;
		vir_bytes vdata, blockrem;
		bp = bufq[nblocks];
		if (bp->lmfs_blocknr != (block_t) bufq[0]->lmfs_blocknr + nblocks)
			break;
		if(niovecs >= NR_IOREQS-iov_per_block) break;
		vdata = (vir_bytes) bp->data;
		blockrem = fs_block_size;
		for(p = 0; p < iov_per_block; p++) {
			vir_bytes chunk = blockrem < PAGE_SIZE ? blockrem : PAGE_SIZE;
			iop->iov_addr = vdata;
			iop->iov_size = chunk;
			vdata += PAGE_SIZE;
			blockrem -= chunk;
			iop++;
			niovecs++;
		}
		assert(p == iov_per_block);
		assert(blockrem == 0);
	}

	assert(nblocks > 0);
	assert(niovecs > 0);

	pos = (off_t)bufq[0]->lmfs_blocknr * fs_block_size;
	if (rw_flag == READING)
		r = bdev_gather(dev, pos, iovec, niovecs, BDEV_NOFLAGS);
	else
		r = bdev_scatter(dev, pos, iovec, niovecs, BDEV_NOFLAGS);

	/* Harvest the results.  The driver may have returned an error, or it
	 * may have done less than what we asked for.
	 */
	if (r < 0) {
		printf("fs cache: I/O error %d on device %d/%d, block %u\n",
			r, major(dev), minor(dev), bufq[0]->lmfs_blocknr);
	}
	for (i = 0; i < nblocks; i++) {
		bp = bufq[i];
		if (r < (ssize_t) fs_block_size) {
			/* Transfer failed. */
			if (i == 0) {
				bp->lmfs_dev = NO_DEV;	/* Invalidate block */
			}
			break;
		}
		if (rw_flag == READING) {
			bp->lmfs_dev = dev;	/* validate block */
			lmfs_put_block(bp, PARTIAL_DATA_BLOCK);
		} else {
			MARKCLEAN(bp);
		}
		r -= fs_block_size;
	}

	bufq += i;
	bufqsize -= i;

	if (rw_flag == READING) {
		/* Don't bother reading more than the device is willing to
		 * give at this time.  Don't forget to release those extras.
		 */
		while (bufqsize > 0) {
			lmfs_put_block(*bufq++, PARTIAL_DATA_BLOCK);
			bufqsize--;
		}
	}
	if (rw_flag == WRITING && i == 0) {
		/* We're not making progress, this means we might keep
		 * looping. Buffers remain dirty if un-written. Buffers are
		 * lost if invalidate()d or LRU-removed while dirty. This
		 * is better than keeping unwritable blocks around forever..
		 */
		break;
	}
  }

  if(rw_flag == READING) {
  	assert(start_in_use >= start_bufqsize);

	/* READING callers assume all bufs are released. */
	assert(start_in_use - start_bufqsize == bufs_in_use);
  }
}
示例#3
0
文件: cache.c 项目: 0xenvision/minix
/*===========================================================================*
 *				rw_scattered				     *
 *===========================================================================*/
void rw_scattered(
  dev_t dev,			/* major-minor device number */
  struct buf **bufq,		/* pointer to array of buffers */
  int bufqsize,		/* number of buffers */
  int rw_flag 			/* READING or WRITING */
)
{
/* Read or write scattered data from a device. */

  register struct buf *bp;
  int gap;
  register int i;
  register iovec_t *iop;
  static iovec_t *iovec = NULL;
  u64_t pos;
  int j, r;

  STATICINIT(iovec, NR_IOREQS);
  assert(bufq != NULL);

  /* (Shell) sort buffers on b_blocknr. */
  gap = 1;
  do
	gap = 3 * gap + 1;
  while (gap <= bufqsize);
  while (gap != 1) {
	gap /= 3;
	for (j = gap; j < bufqsize; j++) {
		for (i = j - gap;
		     i >= 0 && bufq[i]->b_blocknr > bufq[i + gap]->b_blocknr;
		     i -= gap) {
			bp = bufq[i];
			bufq[i] = bufq[i + gap];
			bufq[i + gap] = bp;
		}
	}
  }

  /* Set up I/O vector and do I/O.  The result of dev_io is OK if everything
   * went fine, otherwise the error code for the first failed transfer.
   */
  while (bufqsize > 0) {
	for (j = 0, iop = iovec; j < NR_IOREQS && j < bufqsize; j++, iop++) {
		bp = bufq[j];
		if (bp->b_blocknr != (block_t) bufq[0]->b_blocknr + j) break;
		iop->iov_addr = (vir_bytes) bp->b_data;
		iop->iov_size = (vir_bytes) fs_block_size;
	}
	pos = mul64u(bufq[0]->b_blocknr, fs_block_size);
	if (rw_flag == READING)
		r = bdev_gather(dev, pos, iovec, j, BDEV_NOFLAGS);
	else
		r = bdev_scatter(dev, pos, iovec, j, BDEV_NOFLAGS);

	/* Harvest the results.  The driver may have returned an error, or it
	 * may have done less than what we asked for.
	 */
	if (r < 0) {
		printf("ext2: I/O error %d on device %d/%d, block %u\n",
			r, major(dev), minor(dev), bufq[0]->b_blocknr);
	}
	for (i = 0; i < j; i++) {
		bp = bufq[i];
		if (r < (ssize_t) fs_block_size) {
			/* Transfer failed. */
			if (i == 0) {
				bp->b_dev = NO_DEV;	/* invalidate block */
				vm_forgetblocks();
			}
			break;
		}
		if (rw_flag == READING) {
			bp->b_dev = dev;	/* validate block */
			put_block(bp, PARTIAL_DATA_BLOCK);
		} else {
			bp->b_dirt = CLEAN;
		}
		r -= fs_block_size;
	}
	bufq += i;
	bufqsize -= i;
	if (rw_flag == READING) {
		/* Don't bother reading more than the device is willing to
		 * give at this time.  Don't forget to release those extras.
		 */
		while (bufqsize > 0) {
			put_block(*bufq++, PARTIAL_DATA_BLOCK);
			bufqsize--;
		}
	}
	if (rw_flag == WRITING && i == 0) {
		/* We're not making progress, this means we might keep
		 * looping. Buffers remain dirty if un-written. Buffers are
		 * lost if invalidate()d or LRU-removed while dirty. This
		 * is better than keeping unwritable blocks around forever..
		 */
		break;
	}
  }
}