patch-2.1.66 linux/drivers/char/ftape/ftape-read.c

• Lines: 678
• Date: Wed Dec 31 16:00:00 1969
• Orig file: v2.1.65/linux/drivers/char/ftape/ftape-read.c
• Orig date: Tue Oct 29 15:40:36 1996

diff -u --recursive --new-file v2.1.65/linux/drivers/char/ftape/ftape-read.c linux/drivers/char/ftape/ftape-read.c
@@ -1,677 +0,0 @@
-/*
- *      Copyright (C) 1993-1995 Bas Laarhoven.
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; see the file COPYING.  If not, write to
- the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
-
- $Source: /home/bas/distr/ftape-2.03b/RCS/ftape-read.c,v $
- $Author: bas $
- *
- $Revision: 1.30 $
- $Date: 1995/05/27 08:54:21 $
- $State: Beta $
- *
- *      This file contains the reading code
- *      for the QIC-117 floppy-tape driver for Linux.
- */
-
-#include <linux/string.h>
-#include <linux/errno.h>
-#include <linux/mm.h>
-#include <linux/ftape.h>
-#include <asm/uaccess.h>
-
-#include "tracing.h"
-#include "ftape-read.h"
-#include "qic117.h"
-#include "ftape-io.h"
-#include "ftape-ctl.h"
-#include "ftape-rw.h"
-#include "ftape-write.h"
-#include "ftape-eof.h"
-#include "ecc.h"
-#include "ftape-bsm.h"
-
-/*      Global vars.
- */
-
-/*      Local vars.
- */
-int buf_pos_rd = 0;
-int buf_len_rd = 0;
-
-void ftape_zap_read_buffers(void)
-{
-	int i;
-
-	for (i = 0; i < NR_BUFFERS; ++i) {
-		/*
-		 * changed to "fit" with dynamic allocation of tape_buffer. --khp
-		 */
-		buffer[i].address = tape_buffer[i];
-		buffer[i].status = waiting;
-		buffer[i].bytes = 0;
-		buffer[i].skip = 0;
-		buffer[i].retry = 0;
-	}
-	buf_len_rd = 0;
-	buf_pos_rd = 0;
-	eof_mark = 0;
-	ftape_state = idle;
-}
-
-static unsigned long convert_sector_map(buffer_struct * buff)
-{
-	TRACE_FUN(8, "convert_sector_map");
-	int i = 0;
-	unsigned long bad_map = get_bad_sector_entry(buff->segment_id);
-	unsigned long src_map = buff->soft_error_map | buff->hard_error_map;
-	unsigned long dst_map = 0;
-
-	if (bad_map || src_map) {
-		TRACEx1(5, "bad_map = 0x%08lx", bad_map);
-		TRACEx1(5, "src_map = 0x%08lx", src_map);
-	}
-	while (bad_map) {
-		while ((bad_map & 1) == 0) {
-			if (src_map & 1) {
-				dst_map |= (1 << i);
-			}
-			src_map >>= 1;
-			bad_map >>= 1;
-			++i;
-		}
-		/* (bad_map & 1) == 1 */
-		src_map >>= 1;
-		bad_map >>= 1;
-	}
-	if (src_map) {
-		dst_map |= (src_map << i);
-	}
-	if (dst_map) {
-		TRACEx1(5, "dst_map = 0x%08lx", dst_map);
-	}
-	TRACE_EXIT;
-	return dst_map;
-}
-
-int correct_and_copy(unsigned int tail, byte * destination)
-{
-	TRACE_FUN(8, "correct_and_copy");
-	struct memory_segment mseg;
-	int result;
-	BAD_SECTOR read_bad;
-
-	mseg.read_bad = convert_sector_map(&buffer[tail]);
-	mseg.marked_bad = 0;	/* not used... */
-	mseg.blocks = buffer[tail].bytes / SECTOR_SIZE;
-	mseg.data = buffer[tail].address;
-	/*    If there are no data sectors we can skip this segment.
-	 */
-	if (mseg.blocks <= 3) {
-		TRACE(4, "empty segment");
-		TRACE_EXIT;
-		return 0;
-	}
-	read_bad = mseg.read_bad;
-	history.crc_errors += count_ones(read_bad);
-	result = ecc_correct_data(&mseg);
-	if (read_bad != 0 || mseg.corrected != 0) {
-		TRACElx(4, "crc error map:", read_bad);
-		TRACElx(4, "corrected map:", mseg.corrected);
-		history.corrected += count_ones(mseg.corrected);
-	}
-	if (result == ECC_CORRECTED || result == ECC_OK) {
-		if (result == ECC_CORRECTED) {
-			TRACEi(3, "ecc corrected segment:", buffer[tail].segment_id);
-		}
-		memcpy(destination, mseg.data, (mseg.blocks - 3) * SECTOR_SIZE);
-		if ((read_bad ^ mseg.corrected) & mseg.corrected) {
-			/* sectors corrected without crc errors set */
-			history.crc_failures++;
-		}
-		TRACE_EXIT;
-		return (mseg.blocks - 3) * SECTOR_SIZE;
-	} else {
-		TRACEi(1, "ecc failure on segment", buffer[tail].segment_id);
-		history.ecc_failures++;
-		TRACE_EXIT;
-		return -EAGAIN;	/* should retry */
-	}
-	TRACE_EXIT;
-	return 0;
-}
-
-/*      Read given segment into buffer at address.
- */
-int read_segment(unsigned segment_id, byte * address, int *eof_mark,
-		 int read_ahead)
-{
-	TRACE_FUN(5, "read_segment");
-	int read_done = 0;
-	int result = 0;
-	int bytes_read = 0;
-	int retry = 0;
-
-	TRACEi(5, "segment_id =", segment_id);
-	if (ftape_state != reading) {
-		if (ftape_state == writing) {
-			ftape_flush_buffers();	/* flush write buffer */
-			TRACE(5, "calling ftape_abort_operation");
-			result = ftape_abort_operation();
-			if (result < 0) {
-				TRACE(1, "ftape_abort_operation failed");
-				TRACE_EXIT;
-				return -EIO;
-			}
-		} else {
-			/* clear remaining read buffers */
-			ftape_zap_read_buffers();
-		}
-		ftape_state = reading;
-	}
-	if (segment_id >= segments_per_track * tracks_per_tape) {
-		TRACE(5, "reading past end of tape");
-		TRACE_EXIT;
-		return -ENOSPC;
-	}
-	for (;;) {
-		/*    Search all full buffers for the first matching the wanted segment.
-		 *    Clear other buffers on the fly.
-		 */
-		while (!read_done && buffer[tail].status == done) {
-			if (buffer[tail].segment_id == segment_id) {
-				unsigned eof_sector;
-				unsigned sector_count = 0;
-				unsigned long bsm = get_bad_sector_entry(segment_id);
-				int i;
-
-				/*        If out buffer is already full, return its contents.
-				 */
-				if (buffer[tail].deleted) {
-					TRACEi(5, "found segment in cache :", segment_id);
-					TRACE_EXIT;
-					/*  Return a value that read_header_segment understands.
-					 *  As this should only occur when searching for the header
-					 *  segments it shouldn't be misinterpreted elsewhere.
-					 */
-					return 0;
-				}
-				TRACEi(5, "found segment in cache :", segment_id);
-				eof_sector = check_for_eof(segment_id);
-				if (eof_sector > 0) {
-					TRACEi(5, "end of file mark in sector:", eof_sector);
-					for (i = 1; i < eof_sector; ++i) {
-						if ((bsm & 1) == 0) {
-							++sector_count;
-						}
-						bsm >>= 1;
-					}
-					*eof_mark = 1;
-				}
-				if (eof_sector != 1) {	/* not found or gt 1 */
-					result = correct_and_copy(tail, address);
-					TRACEi(5, "segment contains (bytes) :", result);
-					if (result < 0) {
-						if (result != -EAGAIN) {
-							TRACE_EXIT;
-							return result;
-						}
-						/* keep read_done == 0, will trigger ftape_abort_operation
-						 * because reading wrong segment.
-						 */
-						TRACE(1, "ecc failed, retry");
-						++retry;
-					} else {
-						read_done = 1;
-					}
-				} else {
-					read_done = 1;
-				}
-				if (eof_sector > 0) {
-					bytes_read = sector_count * SECTOR_SIZE;
-					TRACEi(5, "partial read count:", bytes_read);
-				} else {
-					bytes_read = result;
-				}
-			} else {
-				TRACEi(5, "zapping segment in cache :", buffer[tail].segment_id);
-			}
-			buffer[tail].status = waiting;
-			next_buffer(&tail);
-		}
-		if (!read_done && buffer[tail].status == reading) {
-			if (buffer[tail].segment_id == segment_id) {
-				int result = wait_segment(reading);
-				if (result < 0) {
-					if (result == -EINTR) {
-						TRACE_EXIT;
-						return result;
-					}
-					TRACE(1, "wait_segment failed while reading");
-					ftape_abort_operation();
-				}
-			} else {
-				/*        We're reading the wrong segment, stop runner.
-				 */
-				ftape_abort_operation();
-			}
-		}
-		/*    if just passed the last segment on a track, wait for BOT or EOT mark.
-		 */
-		if (runner_status == logical_eot) {
-			int status;
-			result = ftape_ready_wait(timeout.seek, &status);
-			if (result < 0) {
-				TRACE(1, "ftape_ready_wait waiting for eot/bot failed");
-			}
-			if ((status & (QIC_STATUS_AT_BOT | QIC_STATUS_AT_EOT)) == 0) {
-				TRACE(1, "eot/bot not reached");
-			}
-			runner_status = end_of_tape;
-		}
-		/*    should runner stop ?
-		 */
-		if (runner_status == aborting || runner_status == buffer_overrun ||
-		    runner_status == end_of_tape) {
-			if (runner_status != end_of_tape &&
-			 !(runner_status == aborting && !tape_running)) {
-				ftape_dumb_stop();
-			}
-			if (runner_status == aborting) {
-				if (buffer[head].status == reading || buffer[head].status == error) {
-					if (buffer[head].status == error) {
-						history.defects += count_ones(buffer[head].hard_error_map);
-					}
-					buffer[head].status = waiting;
-				}
-			}
-			runner_status = idle;	/* aborted ? */
-		}
-		/*    If segment to read is empty, do not start runner for it,
-		 *    but wait for next read call.
-		 */
-		if (get_bad_sector_entry(segment_id) == EMPTY_SEGMENT) {
-			bytes_read = 0;		/* flag empty segment */
-			read_done = 1;
-		}
-		/*  Allow escape from this loop on signal !
-		 */
-		if (current->signal & _DONT_BLOCK) {
-			TRACE(2, "interrupted by non-blockable signal");
-			TRACE_EXIT;
-			return -EINTR;
-		}
-		/*    If we got a segment: quit, or else retry up to limit.
-		 */
-		if (read_done) {
-			break;
-		}
-		if (retry > RETRIES_ON_ECC_ERROR) {
-			history.defects++;
-			TRACE(1, "too many retries on ecc failure");
-			TRACE_EXIT;
-			return -ENODATA;
-		}
-		/*    Now at least one buffer is empty !
-		 *    Restart runner & tape if needed.
-		 */
-		TRACEx3(8, "head: %d, tail: %d, runner_status: %d",
-			head, tail, runner_status);
-		TRACEx2(8, "buffer[].status, [head]: %d, [tail]: %d",
-			buffer[head].status, buffer[tail].status);
-		if (buffer[tail].status == waiting) {
-			setup_new_segment(&buffer[head], segment_id, -1);
-			if (!read_ahead) {
-				buffer[head].next_segment = 0;	/* disable read-ahead */
-			}
-			calc_next_cluster(&buffer[head]);
-			if (runner_status == idle) {
-				result = ftape_start_tape(segment_id,
-					     buffer[head].sector_offset);
-				if (result < 0) {
-					TRACEx1(1, "Error: segment %d unreachable", segment_id);
-					TRACE_EXIT;
-					return result;
-				}
-				runner_status = running;
-			}
-			buffer[head].status = reading;
-			setup_fdc_and_dma(&buffer[head], FDC_READ);
-		}
-	}
-	if (read_done) {
-		TRACE_EXIT;
-		return bytes_read;
-	} else {
-		TRACE(1, "too many retries");
-		TRACE_EXIT;
-		return -EIO;
-	}
-}
-
-int read_header_segment(byte * address)
-{
-	TRACE_FUN(5, "read_header_segment");
-	int i;
-	int result;
-	int header_segment = -1;
-	unsigned int max_floppy_side;
-	unsigned int max_floppy_track;
-	unsigned int max_floppy_sector;
-	int first_failed = 0;
-	int status;
-	int new_tape_len;
-
-	result = ftape_report_drive_status(&status);
-	if (result < 0) {
-		TRACE(1, "error: error_status or report failure");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	TRACE(5, "reading...");
-	ftape_last_segment.id = 68;	/* will allow us to read the header ! */
-	/*  We're looking for the first header segment.
-	 *  A header segment cannot contain bad sectors, therefor at the
-	 *  tape start, segments with bad sectors are (according to QIC-40/80)
-	 *  written with deleted data marks and must be skipped.
-	 */
-	used_header_segment = -1;
-	result = 0;
-	for (header_segment = 0;
-	     header_segment < ftape_last_segment.id && result == 0;
-	     ++header_segment) {
-		/*  Set no read-ahead, the isr will force read-ahead whenever
-		 *  it encounters deleted data !
-		 */
-		result = read_segment(header_segment, address, &status, 0);
-		if (result < 0 && !first_failed) {
-			TRACE(1, "header segment damaged, trying backup");
-			first_failed = 1;
-			result = 0;	/* force read of next (backup) segment */
-		}
-	}
-	if (result < 0 || header_segment >= ftape_last_segment.id) {
-		TRACE(1, "no readable header segment found");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	result = ftape_abort_operation();
-	if (result < 0) {
-		TRACE(1, "ftape_abort_operation failed");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	if (GET4(address, 0) != 0xaa55aa55) {
-		TRACE(1, "wrong signature in header segment");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	header_segment_1 = GET2(address, 6);
-	header_segment_2 = GET2(address, 8);
-	TRACEx2(2, "header segments are %d and %d",
-		header_segment_1, header_segment_2);
-	used_header_segment = (first_failed) ? header_segment_2 : header_segment_1;
-
-	/*    Verify tape parameters...
-	 *    QIC-40/80 spec:                 tape_parameters:
-	 *
-	 *    segments-per-track              segments_per_track
-	 *    tracks-per-cartridge            tracks_per_tape
-	 *    max-floppy-side                 (segments_per_track *
-	 *                                    tracks_per_tape - 1) /
-	 *                                    segments_per_head
-	 *    max-floppy-track                segments_per_head /
-	 *                                    segments_per_cylinder - 1
-	 *    max-floppy-sector               segments_per_cylinder *
-	 *                                    SECTORS_PER_SEGMENT
-	 */
-	format_code = (format_type) * (address + 4);
-	segments_per_track = GET2(address, 24);
-	tracks_per_tape = *(address + 26);
-	max_floppy_side = *(address + 27);
-	max_floppy_track = *(address + 28);
-	max_floppy_sector = *(address + 29);
-	TRACEx6(4, "(fmt/spt/tpc/fhm/ftm/fsm) = %d/%d/%d/%d/%d/%d",
-		format_code, segments_per_track, tracks_per_tape,
-		max_floppy_side, max_floppy_track, max_floppy_sector);
-	new_tape_len = tape_len;
-	switch (format_code) {
-	case fmt_425ft:
-		new_tape_len = 425;
-		break;
-	case fmt_normal:
-		if (tape_len == 0) {	/* otherwise 307 ft */
-			new_tape_len = 205;
-		}
-		break;
-	case fmt_1100ft:
-		new_tape_len = 1100;
-		break;
-	case fmt_wide:{
-			int segments_per_1000_inch = 1;		/* non-zero default for switch */
-			switch (qic_std) {
-			case QIC_TAPE_QIC40:
-				segments_per_1000_inch = 332;
-				break;
-			case QIC_TAPE_QIC80:
-				segments_per_1000_inch = 488;
-				break;
-			case QIC_TAPE_QIC3010:
-				segments_per_1000_inch = 730;
-				break;
-			case QIC_TAPE_QIC3020:
-				segments_per_1000_inch = 1430;
-				break;
-			}
-			new_tape_len = (1000 * segments_per_track +
-					(segments_per_1000_inch - 1)) / segments_per_1000_inch;
-			break;
-		}
-	default:
-		TRACE(1, "unknown tape format, please report !");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	if (new_tape_len != tape_len) {
-		tape_len = new_tape_len;
-		TRACEx1(1, "calculated tape length is %d ft", tape_len);
-		ftape_calc_timeouts();
-	}
-	if (segments_per_track == 0 && tracks_per_tape == 0 &&
-	    max_floppy_side == 0 && max_floppy_track == 0 &&
-	    max_floppy_sector == 0) {
-		/*  QIC-40 Rev E and earlier has no values in the header.
-		 */
-		segments_per_track = 68;
-		tracks_per_tape = 20;
-		max_floppy_side = 1;
-		max_floppy_track = 169;
-		max_floppy_sector = 128;
-	}
-	/*  This test will compensate for the wrong parameter on tapes
-	 *  formatted by Conner software.
-	 */
-	if (segments_per_track == 150 &&
-	    tracks_per_tape == 28 &&
-	    max_floppy_side == 7 &&
-	    max_floppy_track == 149 &&
-	    max_floppy_sector == 128) {
-		TRACE(-1, "the famous CONNER bug: max_floppy_side off by one !");
-		max_floppy_side = 6;
-	}
-	/*  This test will compensate for the wrong parameter on tapes
-	 *  formatted by Colorado Windows software.
-	 */
-	if (segments_per_track == 150 &&
-	    tracks_per_tape == 28 &&
-	    max_floppy_side == 6 &&
-	    max_floppy_track == 150 &&
-	    max_floppy_sector == 128) {
-		TRACE(-1, "the famous Colorado bug: max_floppy_track off by one !");
-		max_floppy_track = 149;
-	}
-	segments_per_head = ((max_floppy_sector / SECTORS_PER_SEGMENT) *
-			     (max_floppy_track + 1));
-	/*
-	 *    Verify drive_configuration with tape parameters
-	 */
-	if (segments_per_head == 0 || segments_per_cylinder == 0 ||
-	  ((segments_per_track * tracks_per_tape - 1) / segments_per_head
-	   != max_floppy_side) ||
-	    (segments_per_head / segments_per_cylinder - 1 != max_floppy_track) ||
-	(segments_per_cylinder * SECTORS_PER_SEGMENT != max_floppy_sector)
-#ifdef TESTING
-	    || (format_code == 4 && (max_floppy_track != 254 || max_floppy_sector != 128))
-#endif
-	    ) {
-		TRACE(1, "Tape parameters inconsistency, please report");
-		TRACE_EXIT;
-		return -EIO;
-	}
-	first_data_segment = GET2(address, 10);		/* first data segment */
-	TRACEi(4, "first data segment:", first_data_segment);
-	extract_bad_sector_map(address);
-	/*  Find the highest segment id that allows still one full
-	 *  deblock_buffer to be written to tape.
-	 */
-	ftape_last_segment.size = 0;
-	for (i = segments_per_track * tracks_per_tape - 1; i >= 0; --i) {
-		int space = SECTORS_PER_SEGMENT - 3 - count_ones(get_bad_sector_entry(i));
-		if (space > 0) {
-			ftape_last_segment.size += space;	/* sectors free */
-			ftape_last_segment.free = (ftape_last_segment.size -
-				   sizeof(deblock_buffer) / SECTOR_SIZE);
-			if (ftape_last_segment.free >= 0) {
-				ftape_last_segment.id = i;
-				TRACEx2(4, "`last' segment is %d, %d Kb",
-					ftape_last_segment.id, ftape_last_segment.size);
-				break;
-			}
-		}
-	}
-	/* Copy the failed sector log into our local buffer.
-	 */
-	if (!ftape_validate_label(&deblock_buffer[30])) {
-		TRACE(-1, "This tape has no `Linux raw format' label,\n"
-		      "***** Use `mt' to erase this tape if you want to use file marks !");
-	} else {
-		extract_file_marks(address);
-	}
-	ftape_reset_position();
-	TRACE_EXIT;
-	return 0;
-}
-
-int _ftape_read(char *buff, int req_len)
-{
-	TRACE_FUN(5, "_ftape_read");
-	int result = 0;
-	int cnt;
-	int to_do = req_len;
-	static int remaining;
-	int bytes_read = 0;
-
-	if (ftape_offline || !formatted || no_tape) {
-		TRACEx3(-1, "offline = %d, formatted = %d, no_tape = %d",
-			ftape_offline, formatted, no_tape);
-		result = -EIO;
-	} else {
-		history.used |= 1;
-		if (first_data_segment == -1) {
-			result = read_header_segment(deblock_buffer);
-		}
-	}
-	if (result < 0) {
-		TRACE_EXIT;
-		return result;
-	}
-	/*  As GNU tar doesn't accept partial read counts when the multiple
-	 *  volume flag is set, we make sure to return the requested amount
-	 *  of data. Except, of course, at the end of the tape or file mark.
-	 */
-	while (to_do > 0) {	/* don't return with a partial count ! */
-		/*  If we're reading the `last' segment(s) on tape, make sure we don't
-		 *  get more than 29 Kb from it (As it only contains this much).
-		 *  This works only for sequential access, so random access should
-		 *  stay away from this `last' segment.
-		 *  Note: ftape_seg_pos points to the next segment that will be
-		 *        read, so it's one too high here!
-		 */
-		if (!eof_mark && ftape_seg_pos - 1 >= ftape_last_segment.id) {
-			TRACEi(5, "remaining of last segment:", remaining);
-			if (to_do > remaining) {
-				to_do = remaining;	/* fake a smaller request */
-				TRACE(5, "clipped request to remaining");
-			}
-		}
-		while (!eof_mark && buf_len_rd == 0) {
-			/*  When starting to read the `last' segment, set remaining
-			 */
-			if (ftape_seg_pos == ftape_last_segment.id) {
-				remaining = sizeof(deblock_buffer);
-				TRACEi(5, "remaining set to:", remaining);
-			}
-			result = read_segment(ftape_seg_pos, deblock_buffer, &eof_mark, 1);
-			if (result < 0) {
-				if (result == -ENODATA) {
-					/*  Unable to recover tape data, return error and skip bad spot.
-					 */
-					++ftape_seg_pos;
-				}
-				TRACEx1(4, "read_segment result: %d", result);
-				TRACE_EXIT;
-				return result;
-			}
-			/*  Allow escape from this loop on signal !
-			 */
-			if (current->signal & _DONT_BLOCK) {
-				TRACE(2, "interrupted by non-blockable signal");
-				TRACE_EXIT;
-				return -EINTR;
-			}
-			buf_pos_rd = 0;
-			buf_len_rd = result;
-			++ftape_seg_pos;
-		}
-		/*  Take as much as we can use
-		 */
-		cnt = (buf_len_rd < to_do) ? buf_len_rd : to_do;
-		TRACEi(7, "nr bytes just read:", cnt);
-		if (cnt > 0) {
-			result = verify_area(VERIFY_WRITE, buff, cnt);
-			if (result) {
-				TRACEx1(1, "verify_area failed, exitcode = %d", result);
-				TRACE_EXIT;
-				return -EIO;
-			}
-			copy_to_user(buff, deblock_buffer + buf_pos_rd, cnt);
-			buff += cnt;
-			to_do -= cnt;	/* what's left from req_len */
-			remaining -= cnt;	/* what remains on this tape */
-			bytes_read += cnt;	/* what we got so far */
-			buf_pos_rd += cnt;	/* index in buffer */
-			buf_len_rd -= cnt;	/* remaining bytes in buffer */
-		}
-		if (eof_mark && buf_len_rd == 0) {	/* nothing left */
-			TRACE(5, "partial count because of eof mark");
-			if (bytes_read == 0) {
-				eof_mark = 0;	/* no need for mark next read */
-			}
-			break;
-		}
-	}
-	TRACE_EXIT;
-	return bytes_read;
-}