diff options
Diffstat (limited to 'drivers/char/ftape/zftape/zftape-read.c')
| -rw-r--r-- | drivers/char/ftape/zftape/zftape-read.c | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/drivers/char/ftape/zftape/zftape-read.c b/drivers/char/ftape/zftape/zftape-read.c new file mode 100644 index 0000000..214bf03 --- /dev/null +++ b/drivers/char/ftape/zftape/zftape-read.c @@ -0,0 +1,377 @@ +/* + * Copyright (C) 1996, 1997 Claus-Justus Heine + + 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: /homes/cvs/ftape-stacked/ftape/zftape/zftape-read.c,v $ + * $Revision: 1.2 $ + * $Date: 1997/10/05 19:19:06 $ + * + * This file contains the high level reading code + * for the QIC-117 floppy-tape driver for Linux. + */ + +#include <linux/errno.h> +#include <linux/mm.h> + +#include <linux/zftape.h> + +#include <asm/uaccess.h> + +#include "../zftape/zftape-init.h" +#include "../zftape/zftape-eof.h" +#include "../zftape/zftape-ctl.h" +#include "../zftape/zftape-write.h" +#include "../zftape/zftape-read.h" +#include "../zftape/zftape-rw.h" +#include "../zftape/zftape-vtbl.h" + +/* Global vars. + */ +int zft_just_before_eof; + +/* Local vars. + */ +static int buf_len_rd; + +void zft_zap_read_buffers(void) +{ + buf_len_rd = 0; +} + +int zft_read_header_segments(void) +{ + TRACE_FUN(ft_t_flow); + + zft_header_read = 0; + TRACE_CATCH(zft_vmalloc_once(&zft_hseg_buf, FT_SEGMENT_SIZE),); + TRACE_CATCH(ftape_read_header_segment(zft_hseg_buf),); + TRACE(ft_t_info, "Segments written since first format: %d", + (int)GET4(zft_hseg_buf, FT_SEG_CNT)); + zft_qic113 = (ft_format_code != fmt_normal && + ft_format_code != fmt_1100ft && + ft_format_code != fmt_425ft); + TRACE(ft_t_info, "ft_first_data_segment: %d, ft_last_data_segment: %d", + ft_first_data_segment, ft_last_data_segment); + zft_capacity = zft_get_capacity(); + zft_old_ftape = zft_ftape_validate_label(&zft_hseg_buf[FT_LABEL]); + if (zft_old_ftape) { + TRACE(ft_t_info, +"Found old ftaped tape, emulating eof marks, entering read-only mode"); + zft_ftape_extract_file_marks(zft_hseg_buf); + TRACE_CATCH(zft_fake_volume_headers(zft_eof_map, + zft_nr_eof_marks),); + } else { + /* the specs say that the volume table must be + * initialized with zeroes during formatting, so it + * MUST be readable, i.e. contain vaid ECC + * information. + */ + TRACE_CATCH(ftape_read_segment(ft_first_data_segment, + zft_deblock_buf, + FT_RD_SINGLE),); + TRACE_CATCH(zft_extract_volume_headers(zft_deblock_buf),); + } + zft_header_read = 1; + zft_set_flags(zft_unit); + zft_reset_position(&zft_pos); + TRACE_EXIT 0; +} + +int zft_fetch_segment_fraction(const unsigned int segment, void *buffer, + const ft_read_mode_t read_mode, + const unsigned int start, + const unsigned int size) +{ + int seg_sz; + TRACE_FUN(ft_t_flow); + + if (segment == zft_deblock_segment) { + TRACE(ft_t_data_flow, + "re-using segment %d already in deblock buffer", + segment); + seg_sz = zft_get_seg_sz(segment); + if (start > seg_sz) { + TRACE_ABORT(-EINVAL, ft_t_bug, + "trying to read beyond end of segment:\n" + KERN_INFO "seg_sz : %d\n" + KERN_INFO "start : %d\n" + KERN_INFO "segment: %d", + seg_sz, start, segment); + } + if ((start + size) > seg_sz) { + TRACE_EXIT seg_sz - start; + } + TRACE_EXIT size; + } + seg_sz = ftape_read_segment_fraction(segment, buffer, read_mode, + start, size); + TRACE(ft_t_data_flow, "segment %d, result %d", segment, seg_sz); + if ((int)seg_sz >= 0 && start == 0 && size == FT_SEGMENT_SIZE) { + /* this implicitly assumes that we are always called with + * buffer == zft_deblock_buf + */ + zft_deblock_segment = segment; + } else { + zft_deblock_segment = -1; + } + TRACE_EXIT seg_sz; +} + +/* + * out: + * + * int *read_cnt: the number of bytes we removed from the + * zft_deblock_buf (result) + * + * int *to_do : the remaining size of the read-request. Is changed. + * + * in: + * + * char *buff : buff is the address of the upper part of the user + * buffer, that hasn't been filled with data yet. + * int buf_pos_read: copy of buf_pos_rd + * int buf_len_read: copy of buf_len_rd + * char *zft_deblock_buf: ftape_zft_deblock_buf + * + * returns the amount of data actually copied to the user-buffer + * + * to_do MUST NOT SHRINK except to indicate an EOT. In this case to_do + * has to be set to 0. We cannot return -ENOSPC, because we return the + * amount of data actually * copied to the user-buffer + */ +static int zft_simple_read (int *read_cnt, + __u8 __user *dst_buf, + const int to_do, + const __u8 *src_buf, + const int seg_sz, + const zft_position *pos, + const zft_volinfo *volume) +{ + TRACE_FUN(ft_t_flow); + + if (seg_sz - pos->seg_byte_pos < to_do) { + *read_cnt = seg_sz - pos->seg_byte_pos; + } else { + *read_cnt = to_do; + } + if (copy_to_user(dst_buf, + src_buf + pos->seg_byte_pos, *read_cnt) != 0) { + TRACE_EXIT -EFAULT; + } + TRACE(ft_t_noise, "nr bytes just read: %d", *read_cnt); + TRACE_EXIT *read_cnt; +} + +/* req_len: gets clipped due to EOT of EOF. + * req_clipped: is a flag indicating whether req_len was clipped or not + * volume: contains information on current volume (blk_sz etc.) + */ +static int check_read_access(int *req_len, + const zft_volinfo **volume, + int *req_clipped, + const zft_position *pos) +{ + static __s64 remaining; + static int eod; + TRACE_FUN(ft_t_flow); + + if (zft_io_state != zft_reading) { + if (zft_offline) { /* offline includes no_tape */ + TRACE_ABORT(-ENXIO, ft_t_warn, + "tape is offline or no cartridge"); + } + if (!ft_formatted) { + TRACE_ABORT(-EACCES, + ft_t_warn, "tape is not formatted"); + } + /* now enter defined state, read header segment if not + * already done and flush write buffers + */ + TRACE_CATCH(zft_def_idle_state(),); + zft_io_state = zft_reading; + if (zft_tape_at_eod(pos)) { + eod = 1; + TRACE_EXIT 1; + } + eod = 0; + *volume = zft_find_volume(pos->seg_pos); + /* get the space left until EOF */ + remaining = zft_check_for_eof(*volume, pos); + buf_len_rd = 0; + TRACE(ft_t_noise, "remaining: " LL_X ", vol_no: %d", + LL(remaining), (*volume)->count); + } else if (zft_tape_at_eod(pos)) { + if (++eod > 2) { + TRACE_EXIT -EIO; /* st.c also returns -EIO */ + } else { + TRACE_EXIT 1; + } + } + if ((*req_len % (*volume)->blk_sz) != 0) { + /* this message is informational only. The user gets the + * proper return value + */ + TRACE_ABORT(-EINVAL, ft_t_info, + "req_len %d not a multiple of block size %d", + *req_len, (*volume)->blk_sz); + } + /* 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. + */ + remaining -= *req_len; + if (remaining <= 0) { + TRACE(ft_t_noise, + "clipped request from %d to %d.", + *req_len, (int)(*req_len + remaining)); + *req_len += remaining; + *req_clipped = 1; + } else { + *req_clipped = 0; + } + TRACE_EXIT 0; +} + +/* this_segs_size: the current segment's size. + * buff: the USER-SPACE buffer provided by the calling function. + * req_len: how much data should be read at most. + * volume: contains information on current volume (blk_sz etc.) + */ +static int empty_deblock_buf(__u8 __user *usr_buf, const int req_len, + const __u8 *src_buf, const int seg_sz, + zft_position *pos, + const zft_volinfo *volume) +{ + int cnt; + int result = 0; + TRACE_FUN(ft_t_flow); + + TRACE(ft_t_data_flow, "this_segs_size: %d", seg_sz); + if (zft_use_compression && volume->use_compression) { + TRACE_CATCH(zft_cmpr_lock(1 /* try to load */),); + TRACE_CATCH(result= (*zft_cmpr_ops->read)(&cnt, + usr_buf, req_len, + src_buf, seg_sz, + pos, volume),); + } else { + TRACE_CATCH(result= zft_simple_read (&cnt, + usr_buf, req_len, + src_buf, seg_sz, + pos, volume),); + } + pos->volume_pos += result; + pos->tape_pos += cnt; + pos->seg_byte_pos += cnt; + buf_len_rd -= cnt; /* remaining bytes in buffer */ + TRACE(ft_t_data_flow, "buf_len_rd: %d, cnt: %d", buf_len_rd, cnt); + if(pos->seg_byte_pos >= seg_sz) { + pos->seg_pos++; + pos->seg_byte_pos = 0; + } + TRACE(ft_t_data_flow, "bytes moved out of deblock-buffer: %d", cnt); + TRACE_EXIT result; +} + + +/* note: we store the segment id of the segment that is inside the + * deblock buffer. This spares a lot of ftape_read_segment()s when we + * use small block-sizes. The block-size may be 1kb (SECTOR_SIZE). In + * this case a MTFSR 28 maybe still inside the same segment. + */ +int _zft_read(char __user *buff, int req_len) +{ + int req_clipped; + int result = 0; + int bytes_read = 0; + static unsigned int seg_sz = 0; + static const zft_volinfo *volume = NULL; + TRACE_FUN(ft_t_flow); + + zft_resid = req_len; + result = check_read_access(&req_len, &volume, + &req_clipped, &zft_pos); + switch(result) { + case 0: + break; /* nothing special */ + case 1: + TRACE(ft_t_noise, "EOD reached"); + TRACE_EXIT 0; /* EOD */ + default: + TRACE_ABORT(result, ft_t_noise, + "check_read_access() failed with result %d", + result); + TRACE_EXIT result; + } + while (req_len > 0) { + /* Allow escape from this loop on signal ! + */ + FT_SIGNAL_EXIT(_DONT_BLOCK); + /* buf_len_rd == 0 means that we need to read a new + * segment. + */ + if (buf_len_rd == 0) { + while((result = zft_fetch_segment(zft_pos.seg_pos, + zft_deblock_buf, + FT_RD_AHEAD)) == 0) { + zft_pos.seg_pos ++; + zft_pos.seg_byte_pos = 0; + } + if (result < 0) { + zft_resid -= bytes_read; + TRACE_ABORT(result, ft_t_noise, + "zft_fetch_segment(): %d", + result); + } + seg_sz = result; + buf_len_rd = seg_sz - zft_pos.seg_byte_pos; + } + TRACE_CATCH(result = empty_deblock_buf(buff, + req_len, + zft_deblock_buf, + seg_sz, + &zft_pos, + volume), + zft_resid -= bytes_read); + TRACE(ft_t_data_flow, "bytes just read: %d", result); + bytes_read += result; /* what we got so far */ + buff += result; /* index in user-buffer */ + req_len -= result; /* what's left from req_len */ + } /* while (req_len > 0) */ + if (req_clipped) { + TRACE(ft_t_data_flow, + "maybe partial count because of eof mark"); + if (zft_just_before_eof && bytes_read == 0) { + /* req_len was > 0, but user didn't get + * anything the user has read in the eof-mark + */ + zft_move_past_eof(&zft_pos); + ftape_abort_operation(); + } else { + /* don't skip to the next file before the user + * tried to read a second time past EOF Just + * mark that we are at EOF and maybe decrement + * zft_seg_pos to stay in the same volume; + */ + zft_just_before_eof = 1; + zft_position_before_eof(&zft_pos, volume); + TRACE(ft_t_noise, "just before eof"); + } + } + zft_resid -= result; /* for MTSTATUS */ + TRACE_EXIT bytes_read; +} |
