From f0e437bcf46d2537df214e4026fac1382c023f79 Mon Sep 17 00:00:00 2001 From: Mark Wooding Date: Fri, 18 Feb 2022 19:00:48 +0000 Subject: [PATCH 1/1] dvd-sector-copy.c: Rewrite the bad-sector recovery machinery. It's now much more aggressive about skipping good sectors squished between bad ones. --- dvd-sector-copy.c | 206 ++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 194 insertions(+), 12 deletions(-) diff --git a/dvd-sector-copy.c b/dvd-sector-copy.c index d663c0b..908bbbc 100644 --- a/dvd-sector-copy.c +++ b/dvd-sector-copy.c @@ -489,25 +489,189 @@ static void recovered(secaddr bad_lo, secaddr bad_hi) status = 1; } +struct recoverybuf { + unsigned char *buf; + secaddr sz, pos, start, end; +}; + +static void rearrange_sectors(struct recoverybuf *r, + secaddr dest, secaddr src, secaddr len) +{ + assert(dest + len <= r->sz); + assert(src + len <= r->sz); + memmove(r->buf + dest*SECTORSZ, r->buf + src*SECTORSZ, len*SECTORSZ); +} + +#ifdef DEBUG +__attribute__((format(printf, 2, 3))) +static void show_recovery_buffer_map(const struct recoverybuf *r, + const char *what, ...) +{ + va_list ap; + + va_start(ap, what); + clear_progress(); + printf(";; recovery buffer ("); + vprintf(what, ap); + printf("): " + "(%"PRIuSEC") ..%"PRIuSEC".. " + "[%"PRIuSEC" ..%"PRIuSEC".. %"PRIuSEC"] " + "..%"PRIuSEC".. (%"PRIuSEC")\n", + r->pos, r->start, + r->pos + r->start, r->end - r->start, r->pos + r->end, + r->sz - r->end, r->pos + r->sz); + va_end(ap); + assert(r->start <= r->end); + assert(r->end <= r->sz); +} +#endif + +static ssize_t recovery_read_sectors(struct recoverybuf *r, + secaddr pos, secaddr off, secaddr want) +{ + ssize_t n; + + assert(off + want <= r->sz); + n = read_sectors(pos, r->buf + off*SECTORSZ, want); + return (n); +} + +static ssize_t recovery_read(struct recoverybuf *r, + secaddr pos, secaddr want) +{ + secaddr diff, pp, nn; + ssize_t n; + +#ifdef DEBUG + clear_progress(); + show_recovery_buffer_map(r, "begin(%"PRIuSEC", %"PRIuSEC")", pos, want); +#endif + + if (pos < r->pos) { + diff = r->pos - pos; + if (r->start + diff >= r->sz) { + r->pos = pos; r->start = r->end = 0; +#ifdef DEBUG + show_recovery_buffer_map(r, "cleared; shift up by %"PRIuSEC"", diff); +#endif + } else { + if (r->end + diff > r->sz) r->end = r->sz - diff; + rearrange_sectors(r, r->start + diff, r->start, r->end - r->start); + r->start += diff; r->end += diff; +#ifdef DEBUG + show_recovery_buffer_map(r, "shifted up by %"PRIuSEC"", diff); +#endif + } + } else if (pos > r->pos + r->end) { + r->pos = pos; r->start = r->end = 0; +#ifdef DEBUG + show_recovery_buffer_map(r, "cleared; beyond previous region"); +#endif + } else if (pos + want > r->pos + r->sz) { + diff = (pos + want) - (r->pos + r->sz); + if (r->end <= diff) { + r->pos = pos; r->start = r->end = 0; +#ifdef DEBUG + show_recovery_buffer_map(r, "cleared; shift down by %"PRIuSEC"", diff); +#endif + } else { + if (r->start < diff) r->start = diff; + rearrange_sectors(r, r->start - diff, r->start, r->end - r->start); + r->start -= diff; r->end -= diff; +#ifdef DEBUG + show_recovery_buffer_map(r, "shifted down by %"PRIuSEC"", diff); +#endif + } + } + + if (pos < r->pos + r->start) { + pp = pos - r->pos; nn = r->start - pp; +#ifdef DEBUG + printf(";; read low (%"PRIuSEC"@%"PRIuSEC", %"PRIuSEC")", pos, pp, nn); + fflush(stdout); +#endif + n = recovery_read_sectors(r, pos, pp, nn); +#ifdef DEBUG + printf(" -> %ld\n", n); +#endif + if (n != nn) { + if (n > want) n = want; + goto end; + } + r->start = pp; +#ifdef DEBUG + show_recovery_buffer_map(r, "joined new region"); +#endif + } + + if (pos + want > r->pos + r->end) { + pp = r->end; nn = (pos + want) - (r->pos + r->end); +#ifdef DEBUG + printf(";; read high (%"PRIuSEC"@%"PRIuSEC", %"PRIuSEC")", + r->pos + pp, pp, nn); +fflush(stdout); +#endif + n = recovery_read_sectors(r, pos, pp, nn); +#ifdef DEBUG + printf(" -> %ld\n", n); +#endif + if (n > 0) { + r->end += n; +#ifdef DEBUG + show_recovery_buffer_map(r, "joined new region"); +#endif + } + } + + n = r->pos + r->end - pos; + if (!n && want) n = -1; + +end: +#ifdef DEBUG + show_recovery_buffer_map(r, "done; return %ld", n); +#endif + return (n); +} + +static secaddr run_length_wanted(secaddr pos, secaddr badlen, + secaddr sz, secaddr end) +{ + secaddr want; + + want = 3*badlen/2; + if (!want) want = 1; + if (want > end - pos) want = end - pos; + if (want > sz) want = sz; + return (want); +} + static ssize_t find_good_sector(secaddr *pos_inout, secaddr end, unsigned char *buf, secaddr sz) { int i; - secaddr pos = *pos_inout, bad_lo, bad_hi, good, step; + secaddr pos = *pos_inout, bad_lo, bad_hi, good, step, want; + struct recoverybuf r; ssize_t n; + r.buf = buf; r.sz = sz; r.pos = r.start = r.end = 0; report_bad_blocks_progress(pos, pos, errno); + + want = sz; if (want > end - pos) want = end - pos; for (i = 0; i < 4; i++) { - n = read_sectors(pos, buf, 1); + n = recovery_read(&r, pos, want); +#ifdef DEBUG + clear_progress(); + printf(";; [retry] try reading %"PRIuSEC" .. %"PRIuSEC" -> %ld\n", + pos, pos + want, n); +#endif if (n > 0) { clear_progress(); moan("sector %"PRIuSEC" read ok after retry", pos); - bad_lo = bad_hi = pos; return (n); } } - bad_lo = pos; step = 1; bad_hi = pos + 1; + bad_lo = pos; bad_hi = pos + 1; for (;;) { report_bad_blocks_progress(bad_lo, bad_hi, errno); if (bad_hi >= end) { @@ -515,23 +679,41 @@ static ssize_t find_good_sector(secaddr *pos_inout, secaddr end, moan("giving up on this extent"); recovered(bad_lo, end); *pos_inout = end; return (0); } - step *= 2; - if (step > end - bad_lo) step = end - bad_lo; + step = 2*(bad_hi - bad_lo); if (step > end - bad_lo) step = end - bad_lo; pos = bad_lo + step - 1; - n = read_sectors(pos, buf, 1); - if (n > 0) break; - bad_hi = pos + 1; + want = run_length_wanted(pos, step, sz, end); + n = recovery_read(&r, pos, want); +#ifdef DEBUG + clear_progress(); + printf(";; [bound] try reading %"PRIuSEC" .. %"PRIuSEC" -> %ld\n", + pos, pos + want, n); +#endif + if (n == want) break; + if (n < 0) n = 0; + bad_hi = pos + n + 1; } good = pos; while (good > bad_hi) { report_bad_blocks_progress(bad_lo, bad_hi, errno); pos = bad_hi + (good - bad_hi)/2; - n = read_sectors(pos, buf, 1); - if (n > 0) good = pos; - else bad_hi = pos + 1; + step = pos - bad_lo; + want = run_length_wanted(pos, step, sz, end); + n = recovery_read(&r, pos, want); +#ifdef DEBUG + clear_progress(); + printf(";; [limit] try reading %"PRIuSEC" .. %"PRIuSEC" -> %ld\n", + pos, pos + want, n); +#endif + if (n < 0) n = 0; + if (n == want) good = pos; + else bad_hi = pos + n + 1; } recovered(bad_lo, bad_hi); *pos_inout = good; + if (r.pos + r.start <= good && good <= r.pos + r.end) { + rearrange_sectors(&r, 0, good - r.pos, r.pos + r.end - good); + } else + n = 0; return (n); } -- 2.11.0