From 423cf6dc04eb79d441bfda2b127bc4b57134b41d Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 7 Apr 2008 15:59:23 +0200 Subject: [PATCH] udf: Cleanup anchor block detection. UDF anchor block detection is complicated by several things - there are several places where the anchor point can be, some of them relative to the last recorded block which some devices report wrongly. Moreover some devices on some media seem to have 7 spare blocks sectors for every 32 blocks (at least as far as I understand the old code) so we have to count also with that possibility. This patch splits anchor block detection into several functions so that it is clearer what we actually try to do. We fix several bugs of the type "for such and such media, we fail to check block blah" as a result of the cleanup. Signed-off-by: Jan Kara --- fs/udf/super.c | 239 ++++++++++++++++++++---------------------------- fs/udf/udf_sb.h | 2 +- 2 files changed, 99 insertions(+), 142 deletions(-) diff --git a/fs/udf/super.c b/fs/udf/super.c index 7ec828566d..fe0dafebde 100644 --- a/fs/udf/super.c +++ b/fs/udf/super.c @@ -678,149 +678,120 @@ static int udf_vrs(struct super_block *sb, int silent) } /* - * udf_find_anchor - * - * PURPOSE - * Find an anchor volume descriptor. - * - * PRE-CONDITIONS - * sb Pointer to _locked_ superblock. - * lastblock Last block on media. - * - * POST-CONDITIONS - * 1 if not found, 0 if ok - * - * HISTORY - * July 1, 1997 - Andrew E. Mileski - * Written, tested, and released. + * Check whether there is an anchor block in the given block */ -static void udf_find_anchor(struct super_block *sb) +static int udf_check_anchor_block(struct super_block *sb, sector_t block, + bool varconv) { - int lastblock; struct buffer_head *bh = NULL; + tag *t; uint16_t ident; uint32_t location; + + if (varconv) + bh = sb_bread(sb, udf_fixed_to_variable(block)); + else + bh = sb_bread(sb, block); + + if (!bh) + return 0; + + t = (tag *)bh->b_data; + ident = le16_to_cpu(t->tagIdent); + location = le32_to_cpu(t->tagLocation); + brelse(bh); + if (ident != TAG_IDENT_AVDP) + return 0; + return location == block; +} + +/* Search for an anchor volume descriptor pointer */ +static sector_t udf_scan_anchors(struct super_block *sb, bool varconv, + sector_t lastblock) +{ + sector_t last[4]; int i; - struct udf_sb_info *sbi; + struct udf_sb_info *sbi = UDF_SB(sb); - sbi = UDF_SB(sb); - lastblock = sbi->s_last_block; + last[0] = lastblock; + last[1] = last[0] - 2; + last[2] = last[0] - 150; + last[3] = last[0] - 152; - if (lastblock) { - int varlastblock = udf_variable_to_fixed(lastblock); - int last[] = { lastblock, lastblock - 2, - lastblock - 150, lastblock - 152, - varlastblock, varlastblock - 2, - varlastblock - 150, varlastblock - 152 }; - - lastblock = 0; - - /* Search for an anchor volume descriptor pointer */ - - /* according to spec, anchor is in either: - * block 256 - * lastblock-256 - * lastblock - * however, if the disc isn't closed, it could be 512 */ - - for (i = 0; !lastblock && i < ARRAY_SIZE(last); i++) { - ident = location = 0; - if (last[i] >= 0) { - bh = sb_bread(sb, last[i]); - if (bh) { - tag *t = (tag *)bh->b_data; - ident = le16_to_cpu(t->tagIdent); - location = le32_to_cpu(t->tagLocation); - brelse(bh); - } - } + /* according to spec, anchor is in either: + * block 256 + * lastblock-256 + * lastblock + * however, if the disc isn't closed, it could be 512 */ - if (ident == TAG_IDENT_AVDP) { - if (location == last[i] - sbi->s_session) { - lastblock = last[i] - sbi->s_session; - sbi->s_anchor[0] = lastblock; - sbi->s_anchor[1] = lastblock - 256; - } else if (location == - udf_variable_to_fixed(last[i]) - - sbi->s_session) { - UDF_SET_FLAG(sb, UDF_FLAG_VARCONV); - lastblock = - udf_variable_to_fixed(last[i]) - - sbi->s_session; - sbi->s_anchor[0] = lastblock; - sbi->s_anchor[1] = lastblock - 256 - - sbi->s_session; - } else { - udf_debug("Anchor found at block %d, " - "location mismatch %d.\n", - last[i], location); - } - } else if (ident == TAG_IDENT_FE || - ident == TAG_IDENT_EFE) { - lastblock = last[i]; - sbi->s_anchor[3] = 512; - } else { - ident = location = 0; - if (last[i] >= 256) { - bh = sb_bread(sb, last[i] - 256); - if (bh) { - tag *t = (tag *)bh->b_data; - ident = le16_to_cpu( - t->tagIdent); - location = le32_to_cpu( - t->tagLocation); - brelse(bh); - } - } + for (i = 0; i < ARRAY_SIZE(last); i++) { + if (last[i] < 0) + continue; - if (ident == TAG_IDENT_AVDP && - location == last[i] - 256 - - sbi->s_session) { - lastblock = last[i]; - sbi->s_anchor[1] = last[i] - 256; - } else { - ident = location = 0; - if (last[i] >= 312 + sbi->s_session) { - bh = sb_bread(sb, - last[i] - 312 - - sbi->s_session); - if (bh) { - tag *t = (tag *) - bh->b_data; - ident = le16_to_cpu( - t->tagIdent); - location = le32_to_cpu( - t->tagLocation); - brelse(bh); - } - } + if (udf_check_anchor_block(sb, last[i], varconv)) { + sbi->s_anchor[0] = last[i]; + sbi->s_anchor[1] = last[i] - 256; + return last[i]; + } - if (ident == TAG_IDENT_AVDP && - location == udf_variable_to_fixed(last[i]) - 256) { - UDF_SET_FLAG(sb, - UDF_FLAG_VARCONV); - lastblock = udf_variable_to_fixed(last[i]); - sbi->s_anchor[1] = lastblock - 256; - } - } - } + if (last[i] < 256) + continue; + + if (udf_check_anchor_block(sb, last[i] - 256, varconv)) { + sbi->s_anchor[1] = last[i] - 256; + return last[i]; } } - if (!lastblock) { - /* We haven't found the lastblock. check 312 */ - bh = sb_bread(sb, 312 + sbi->s_session); - if (bh) { - tag *t = (tag *)bh->b_data; - ident = le16_to_cpu(t->tagIdent); - location = le32_to_cpu(t->tagLocation); - brelse(bh); + if (udf_check_anchor_block(sb, sbi->s_session + 256, varconv)) { + sbi->s_anchor[0] = sbi->s_session + 256; + return last[0]; + } + if (udf_check_anchor_block(sb, sbi->s_session + 512, varconv)) { + sbi->s_anchor[0] = sbi->s_session + 512; + return last[0]; + } + return 0; +} - if (ident == TAG_IDENT_AVDP && location == 256) - UDF_SET_FLAG(sb, UDF_FLAG_VARCONV); - } +/* + * Find an anchor volume descriptor. The function expects sbi->s_lastblock to + * be the last block on the media. + * + * Return 1 if not found, 0 if ok + * + */ +static void udf_find_anchor(struct super_block *sb) +{ + sector_t lastblock; + struct buffer_head *bh = NULL; + uint16_t ident; + int i; + struct udf_sb_info *sbi = UDF_SB(sb); + + lastblock = udf_scan_anchors(sb, 0, sbi->s_last_block); + if (lastblock) + goto check_anchor; + + /* No anchor found? Try VARCONV conversion of block numbers */ + /* Firstly, we try to not convert number of the last block */ + lastblock = udf_scan_anchors(sb, 1, + udf_variable_to_fixed(sbi->s_last_block)); + if (lastblock) { + UDF_SET_FLAG(sb, UDF_FLAG_VARCONV); + goto check_anchor; } + /* Secondly, we try with converted number of the last block */ + lastblock = udf_scan_anchors(sb, 1, sbi->s_last_block); + if (lastblock) + UDF_SET_FLAG(sb, UDF_FLAG_VARCONV); + +check_anchor: + /* + * Check located anchors and the anchor block supplied via + * mount options + */ for (i = 0; i < ARRAY_SIZE(sbi->s_anchor); i++) { if (!sbi->s_anchor[i]) continue; @@ -830,9 +801,7 @@ static void udf_find_anchor(struct super_block *sb) sbi->s_anchor[i] = 0; else { brelse(bh); - if ((ident != TAG_IDENT_AVDP) && - (i || (ident != TAG_IDENT_FE && - ident != TAG_IDENT_EFE))) + if (ident != TAG_IDENT_AVDP) sbi->s_anchor[i] = 0; } } @@ -1225,17 +1194,6 @@ static int udf_load_partdesc(struct super_block *sb, sector_t block) if (ret) goto out_bh; - if (!sbi->s_last_block) { - sbi->s_last_block = udf_get_last_block(sb); - udf_find_anchor(sb); - if (!sbi->s_last_block) { - udf_debug("Unable to determine Lastblock (For " - "Virtual Partition)\n"); - ret = 1; - goto out_bh; - } - } - ret = udf_load_vat(sb, i, type1_idx); out_bh: /* In case loading failed, we handle cleanup in udf_fill_super */ @@ -1778,7 +1736,6 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent) sbi->s_last_block = uopt.lastblock; sbi->s_anchor[0] = sbi->s_anchor[1] = 0; sbi->s_anchor[2] = uopt.anchor; - sbi->s_anchor[3] = 256; if (udf_check_valid(sb, uopt.novrs, silent)) { /* read volume recognition sequences */ diff --git a/fs/udf/udf_sb.h b/fs/udf/udf_sb.h index fb2a6e9f8d..8308a12e12 100644 --- a/fs/udf/udf_sb.h +++ b/fs/udf/udf_sb.h @@ -100,7 +100,7 @@ struct udf_sb_info { /* Sector headers */ __s32 s_session; - __u32 s_anchor[4]; + __u32 s_anchor[3]; __u32 s_last_block; struct buffer_head *s_lvid_bh; -- 2.39.5