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 <jack@suse.cz>
diff --git a/fs/udf/super.c b/fs/udf/super.c
index 7ec8285..fe0dafe 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -678,149 +678,120 @@
}
/*
- * udf_find_anchor
+ * Check whether there is an anchor block in the given block
+ */
+static int udf_check_anchor_block(struct super_block *sb, sector_t block,
+ bool varconv)
+{
+ 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 = UDF_SB(sb);
+
+ last[0] = lastblock;
+ last[1] = last[0] - 2;
+ last[2] = last[0] - 150;
+ last[3] = last[0] - 152;
+
+ /* 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; i < ARRAY_SIZE(last); i++) {
+ if (last[i] < 0)
+ continue;
+
+ 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 (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 (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;
+}
+
+/*
+ * Find an anchor volume descriptor. The function expects sbi->s_lastblock to
+ * be the last block on the media.
*
- * PURPOSE
- * Find an anchor volume descriptor.
+ * Return 1 if not found, 0 if ok
*
- * PRE-CONDITIONS
- * sb Pointer to _locked_ superblock.
- * lastblock Last block on media.
- *
- * POST-CONDITIONS
- * <return> 1 if not found, 0 if ok
- *
- * HISTORY
- * July 1, 1997 - Andrew E. Mileski
- * Written, tested, and released.
*/
static void udf_find_anchor(struct super_block *sb)
{
- int lastblock;
+ sector_t lastblock;
struct buffer_head *bh = NULL;
uint16_t ident;
- uint32_t location;
int i;
- struct udf_sb_info *sbi;
+ struct udf_sb_info *sbi = UDF_SB(sb);
- sbi = UDF_SB(sb);
- lastblock = sbi->s_last_block;
+ 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) {
- 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);
- }
- }
-
- 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);
- }
- }
-
- 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 (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;
- }
- }
- }
- }
+ UDF_SET_FLAG(sb, UDF_FLAG_VARCONV);
+ goto check_anchor;
}
- 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);
+ /* 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);
- if (ident == TAG_IDENT_AVDP && location == 256)
- 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 @@
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 @@
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 @@
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 */