lcnalloc.c

上一个上传的有问题,这个是好的。visopsys包括系统内核和GUI的全部SOURCE code ,还包括一些基本的docs文档。里面src子目录对应所有SOURCE code.对于想研究操作系统的朋

			/*
			 * Now do pass 2, scanning the first part of the zone
			 * we omitted in pass 1.
			 */
			pass = 2;
			zone_end = zone_start;
			switch (search_zone) {
			case 1: /* mft_zone */
				zone_start = vol->mft_zone_start;
				break;
			case 2: /* data1_zone */
				zone_start = vol->mft_zone_end;
				break;
			case 4: /* data2_zone */
				zone_start = 0;
				break;
			default:
				NTFS_BUG("switch (search_zone) 2");
			}
			/* Sanity check. */
			if (zone_end < zone_start)
				zone_end = zone_start;
			bmp_pos = zone_start;
			ntfs_log_trace("Continuing outer while loop, pass = 2, "
					"zone_start = 0x%llx, zone_end = "
					"0x%llx, bmp_pos = 0x%llx.\n",
					zone_start, zone_end, bmp_pos);
			continue;
		} /* pass == 2 */
done_zones_check:
		ntfs_log_trace("At done_zones_check, search_zone = %i, done_zones "
				"before = 0x%x, done_zones after = 0x%x.\n",
				search_zone, done_zones, done_zones | search_zone);
		done_zones |= search_zone;
		if (done_zones < 7) {
			ntfs_log_trace("Switching zone.\n");
			/* Now switch to the next zone we haven't done yet. */
			pass = 1;
			switch (search_zone) {
			case 1:
				ntfs_log_trace("Switching from mft zone to data1 "
						"zone.\n");
				/* Update mft zone position. */
				if (rlpos) {
					LCN tc;
					ntfs_log_trace("Before checks, vol->mft_zone_pos = 0x%llx.\n",
							(long long) vol->mft_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->mft_zone_end) {
						vol->mft_zone_pos =
								vol->mft_lcn;
						if (!vol->mft_zone_end)
							vol->mft_zone_pos = 0;
					} else if ((bmp_initial_pos >=
							vol->mft_zone_pos ||
							tc > vol->mft_zone_pos)
							&& tc >= vol->mft_lcn)
						vol->mft_zone_pos = tc;
					ntfs_log_trace("After checks, vol->mft_zone_pos = 0x%llx.\n",
							(long long) vol->mft_zone_pos);
				}
				/* Switch from mft zone to data1 zone. */
switch_to_data1_zone:		search_zone = 2;
				zone_start = bmp_initial_pos =
						vol->data1_zone_pos;
				zone_end = vol->nr_clusters;
				if (zone_start == vol->mft_zone_end)
					pass = 2;
				if (zone_start >= zone_end) {
					vol->data1_zone_pos = zone_start =
							vol->mft_zone_end;
					pass = 2;
				}
				break;
			case 2:
				ntfs_log_trace("Switching from data1 zone to data2 "
						"zone.\n");
				/* Update data1 zone position. */
				if (rlpos) {
					LCN tc;
					ntfs_log_trace("Before checks, vol->data1_zone_pos = 0x%llx.\n",
							(long long) vol->data1_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->nr_clusters)
						vol->data1_zone_pos =
							     vol->mft_zone_end;
					else if ((bmp_initial_pos >=
						    vol->data1_zone_pos ||
						    tc > vol->data1_zone_pos)
						    && tc >= vol->mft_zone_end)
						vol->data1_zone_pos = tc;
					ntfs_log_trace("After checks, vol->data1_zone_pos = 0x%llx.\n",
							(long long) vol->data1_zone_pos);
				}
				/* Switch from data1 zone to data2 zone. */
				search_zone = 4;
				zone_start = bmp_initial_pos =
						vol->data2_zone_pos;
				zone_end = vol->mft_zone_start;
				if (!zone_start)
					pass = 2;
				if (zone_start >= zone_end) {
					vol->data2_zone_pos = zone_start =
							bmp_initial_pos = 0;
					pass = 2;
				}
				break;
			case 4:
				ntfs_log_debug("Switching from data2 zone to data1 "
						"zone.\n");
				/* Update data2 zone position. */
				if (rlpos) {
					LCN tc;
					ntfs_log_trace("Before checks, vol->data2_zone_pos = 0x%llx.\n",
							(long long) vol->data2_zone_pos);
					tc = rl[rlpos - 1].lcn +
							rl[rlpos - 1].length;
					if (tc >= vol->mft_zone_start)
						vol->data2_zone_pos = 0;
					else if (bmp_initial_pos >=
						      vol->data2_zone_pos ||
						      tc > vol->data2_zone_pos)
						vol->data2_zone_pos = tc;
					ntfs_log_trace("After checks, vol->data2_zone_pos = 0x%llx.\n",
							(long long) vol->data2_zone_pos);
				}
				/* Switch from data2 zone to data1 zone. */
				goto switch_to_data1_zone; /* See above. */
			default:
				NTFS_BUG("switch (search_zone) 3");
			}
			ntfs_log_trace("After zone switch, search_zone = %i, pass = "
					"%i, bmp_initial_pos = 0x%llx, "
					"zone_start = 0x%llx, zone_end = "
					"0x%llx.\n", search_zone, pass,
					(long long)bmp_initial_pos,
					(long long)zone_start,
					(long long)zone_end);
			bmp_pos = zone_start;
			if (zone_start == zone_end) {
				ntfs_log_trace("Empty zone, going to "
						"done_zones_check.\n");
				/* Empty zone. Don't bother searching it. */
				goto done_zones_check;
			}
			ntfs_log_trace("Continuing outer while loop.\n");
			continue;
		} /* done_zones == 7 */
		ntfs_log_trace("All zones are finished.\n");
		/*
		 * All zones are finished! If DATA_ZONE, shrink mft zone. If
		 * MFT_ZONE, we have really run out of space.
		 */
		mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
		ntfs_log_trace("vol->mft_zone_start = 0x%llx, vol->mft_zone_end = "
				"0x%llx, mft_zone_size = 0x%llx.\n",
				(long long)vol->mft_zone_start,
				(long long)vol->mft_zone_end,
				(long long)mft_zone_size);
		if (zone == MFT_ZONE || mft_zone_size <= 0) {
			ntfs_log_trace("No free clusters left, going to err_ret.\n");
			/* Really no more space left on device. */
			err = ENOSPC;
			goto err_ret;
		} /* zone == DATA_ZONE && mft_zone_size > 0 */
		ntfs_log_trace("Shrinking mft zone.\n");
		zone_end = vol->mft_zone_end;
		mft_zone_size >>= 1;
		if (mft_zone_size > 0)
			vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
		else /* mft zone and data2 zone no longer exist. */
			vol->data2_zone_pos = vol->mft_zone_start =
					vol->mft_zone_end = 0;
		if (vol->mft_zone_pos >= vol->mft_zone_end) {
			vol->mft_zone_pos = vol->mft_lcn;
			if (!vol->mft_zone_end)
				vol->mft_zone_pos = 0;
		}
		bmp_pos = zone_start = bmp_initial_pos =
				vol->data1_zone_pos = vol->mft_zone_end;
		search_zone = 2;
		pass = 2;
		done_zones &= ~2;
		ntfs_log_trace("After shrinking mft zone, mft_zone_size = 0x%llx, "
				"vol->mft_zone_start = 0x%llx, "
				"vol->mft_zone_end = 0x%llx, vol->mft_zone_pos "
				"= 0x%llx, search_zone = 2, pass = 2, "
				"dones_zones = 0x%x, zone_start = 0x%llx, "
				"zone_end = 0x%llx, vol->data1_zone_pos = "
				"0x%llx, continuing outer while loop.\n",
				(long long)mft_zone_size,
				(long long)vol->mft_zone_start,
				(long long)vol->mft_zone_end,
				(long long)vol->mft_zone_pos,
				done_zones,
				(long long)zone_start,
				(long long)zone_end,
				(long long)vol->data1_zone_pos);
	}
	ntfs_log_debug("After outer while loop.\n");
done_ret:
	ntfs_log_debug("At done_ret.\n");
	/* Add runlist terminator element. */
	rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
	rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
	rl[rlpos].length = 0;
	if (need_writeback) {
		s64 bw;
		ntfs_log_trace("Writing back.\n");
		need_writeback = 0;
		bw = ntfs_attr_pwrite(vol->lcnbmp_na, last_read_pos, br, buf);
		if (bw != br) {
			if (bw < 0)
				err = errno;
			else
				err = EIO;
			ntfs_log_trace("Bitmap writeback failed in done code path "
					"with error code %i.\n", err);
			goto err_ret;
		}
	}
done_err_ret:
	ntfs_log_debug("At done_err_ret (follows done_ret).\n");
	free(buf);
	/* Done! */
	if (!err)
		return rl;
	ntfs_log_trace("Failed to allocate clusters. Returning with error code "
			"%i.\n", err);
	errno = err;
	return NULL;
wb_err_ret:
	ntfs_log_trace("At wb_err_ret.\n");
	if (need_writeback) {
		s64 bw;
		ntfs_log_trace("Writing back.\n");
		need_writeback = 0;
		bw = ntfs_attr_pwrite(vol->lcnbmp_na, last_read_pos, br, buf);
		if (bw != br) {
			if (bw < 0)
				err = errno;
			else
				err = EIO;
			ntfs_log_trace("Bitmap writeback failed in error code path "
					"with error code %i.\n", err);
		}
	}
err_ret:
	ntfs_log_trace("At err_ret.\n");
	if (rl) {
		if (err == ENOSPC) {
			ntfs_log_trace("err = ENOSPC, first free lcn = 0x%llx, could "
					"allocate up to = 0x%llx clusters.\n",
					(long long)rl[0].lcn,
					(long long)count - clusters);
		}
		/* Add runlist terminator element. */
		rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
		rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
		rl[rlpos].length = 0;
		/* Deallocate all allocated clusters. */
		ntfs_log_trace("Deallocating allocated clusters.\n");
		ntfs_cluster_free_from_rl(vol, rl);
		/* Free the runlist. */
		free(rl);
		rl = NULL;
	} else {
		if (err == ENOSPC) {
			ntfs_log_trace("No space left at all, err = ENOSPC, first "
					"free lcn = 0x%llx.\n",
					(long long)vol->data1_zone_pos);
		}
	}
	ntfs_log_trace("rl = NULL, going to done_err_ret.\n");
	goto done_err_ret;
}

/**
 * ntfs_cluster_free_from_rl - free clusters from runlist
 * @vol:	mounted ntfs volume on which to free the clusters
 * @rl:		runlist from which deallocate clusters
 *
 * On success return 0 and on error return -1 with errno set to the error code.
 */
int ntfs_cluster_free_from_rl(ntfs_volume *vol, runlist *rl)
{
	ntfs_log_trace("Entering.\n");

	for (; rl->length; rl++) {

		ntfs_log_trace("Dealloc lcn 0x%llx, len 0x%llx.\n",
			       (long long)rl->lcn, (long long)rl->length);

		if (rl->lcn >= 0 && ntfs_bitmap_clear_run(vol->lcnbmp_na,
				rl->lcn, rl->length)) {
			int eo = errno;
			ntfs_log_trace("Eeek! Deallocation of clusters failed.\n");
			errno = eo;
			return -1;
		}
	}
	return 0;
}

/**
 * ntfs_cluster_free - free clusters on an ntfs volume
 * @vol:	mounted ntfs volume on which to free the clusters
 * @na:		attribute whose runlist describes the clusters to free
 * @start_vcn:	vcn in @rl at which to start freeing clusters
 * @count:	number of clusters to free or -1 for all clusters
 *
 * Free @count clusters starting at the cluster @start_vcn in the runlist
 * described by the attribute @na from the mounted ntfs volume @vol.
 *
 * If @count is -1, all clusters from @start_vcn to the end of the runlist
 * are deallocated.
 *
 * On success return the number of deallocated clusters (not counting sparse
 * clusters) and on error return -1 with errno set to the error code.
 */
int ntfs_cluster_free(ntfs_volume *vol, ntfs_attr *na, VCN start_vcn, s64 count)
{
	runlist *rl;
	s64 nr_freed, delta, to_free;

	if (!vol || !vol->lcnbmp_na || !na || start_vcn < 0 ||
			(count < 0 && count != -1)) {
		ntfs_log_trace("Invalid arguments!\n");
		errno = EINVAL;
		return -1;
	}
	ntfs_log_trace("Entering for inode 0x%llx, attr 0x%x, count 0x%llx, "
		       "vcn 0x%llx.\n", (unsigned long long)na->ni->mft_no,
		       na->type, (long long)count, (long long)start_vcn);

	rl = ntfs_attr_find_vcn(na, start_vcn);
	if (!rl) {
		if (errno == ENOENT)
			return 0;
		else
			return -1;
	}

	if (rl->lcn < 0 && rl->lcn != LCN_HOLE) {
		errno = EIO;
		return -1;
	}

	/* Find the starting cluster inside the run that needs freeing. */
	delta = start_vcn - rl->vcn;

	/* The number of clusters in this run that need freeing. */
	to_free = rl->length - delta;
	if (count >= 0 && to_free > count)
		to_free = count;

	if (rl->lcn != LCN_HOLE) {
		/* Do the actual freeing of the clusters in this run. */
		if (ntfs_bitmap_clear_run(vol->lcnbmp_na, rl->lcn + delta,
				to_free))
			return -1;
		/* We have freed @to_free real clusters. */
		nr_freed = to_free;
	} else {
		/* No real clusters were freed. */
		nr_freed = 0;
	}

	/* Go to the next run and adjust the number of clusters left to free. */
	++rl;
	if (count >= 0)
		count -= to_free;

	/*
	 * Loop over the remaining runs, using @count as a capping value, and
	 * free them.
	 */
	for (; rl->length && count != 0; ++rl) {
		// FIXME: Need to try ntfs_attr_map_runlist() for attribute
		//	  list support! (AIA)
		if (rl->lcn < 0 && rl->lcn != LCN_HOLE) {
			// FIXME: Eeek! We need rollback! (AIA)
			ntfs_log_trace("Eeek! invalid lcn (= %lli).  Should attempt "
					"to map runlist!  Leaving inconsistent "
					"metadata!\n", (long long)rl->lcn);
			errno = EIO;
			return -1;
		}

		/* The number of clusters in this run that need freeing. */
		to_free = rl->length;
		if (count >= 0 && to_free > count)
			to_free = count;

		if (rl->lcn != LCN_HOLE) {
			/* Do the actual freeing of the clusters in the run. */
			if (ntfs_bitmap_clear_run(vol->lcnbmp_na, rl->lcn,
					to_free)) {
				int eo = errno;

				// FIXME: Eeek! We need rollback! (AIA)
				ntfs_log_trace("Eeek!  bitmap clear run failed.  "
						"Leaving inconsistent metadata!\n");
				errno = eo;
				return -1;
			}
			/* We have freed @to_free real clusters. */
			nr_freed += to_free;
		}

		if (count >= 0)
			count -= to_free;
	}

	if (count != -1 && count != 0) {
		// FIXME: Eeek! BUG()
		ntfs_log_trace("Eeek!  count still not zero (= %lli).  Leaving "
				"inconsistent metadata!\n", (long long)count);
		errno = EIO;
		return -1;
	}

	/* Done. Return the number of actual clusters that were freed. */
	return nr_freed;
}