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authorRusty Russell <rusty@rustcorp.com.au>2010-09-13 19:55:26 +0930
committerRusty Russell <rusty@rustcorp.com.au>2010-09-13 19:55:26 +0930
commit9e0deff904877068d19b41e965732f145c2554b9 (patch)
tree243f4f93e0ba60d7998490f7b17a32f78c095c3a
parentfe958c009be224be91e9ed4cdafe5330735d0a38 (diff)
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tdb: make check more robust against recovery failures.
We can end up with dead areas when we die during transaction commit; tdb_check() fails on such a (valid) database. This is particularly noticable now we no longer truncate on recovery; if the recovery area was at the end of the file we used to remove it that way. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--lib/tdb/common/check.c41
1 files changed, 36 insertions, 5 deletions
diff --git a/lib/tdb/common/check.c b/lib/tdb/common/check.c
index 2c640434ee..3be8a0c48b 100644
--- a/lib/tdb/common/check.c
+++ b/lib/tdb/common/check.c
@@ -301,6 +301,21 @@ static bool tdb_check_free_record(struct tdb_context *tdb,
return true;
}
+/* Slow, but should be very rare. */
+static size_t dead_space(struct tdb_context *tdb, tdb_off_t off)
+{
+ size_t len;
+
+ for (len = 0; off + len < tdb->map_size; len++) {
+ char c;
+ if (tdb->methods->tdb_read(tdb, off, &c, 1, 0))
+ return 0;
+ if (c != 0 && c != 0x42)
+ break;
+ }
+ return len;
+}
+
int tdb_check(struct tdb_context *tdb,
int (*check)(TDB_DATA key, TDB_DATA data, void *private_data),
void *private_data)
@@ -310,6 +325,7 @@ int tdb_check(struct tdb_context *tdb,
tdb_off_t off, recovery_start;
struct tdb_record rec;
bool found_recovery = false;
+ tdb_len_t dead;
if (tdb_lockall_read(tdb) == -1)
return -1;
@@ -369,8 +385,23 @@ int tdb_check(struct tdb_context *tdb,
if (!tdb_check_free_record(tdb, off, &rec, hashes))
goto free;
break;
- case TDB_RECOVERY_MAGIC:
+ /* If we crash after ftruncate, we can get zeroes or fill. */
case TDB_RECOVERY_INVALID_MAGIC:
+ case 0x42424242:
+ if (recovery_start == off) {
+ found_recovery = true;
+ break;
+ }
+ dead = dead_space(tdb, off);
+ if (dead < sizeof(rec))
+ goto corrupt;
+
+ TDB_LOG((tdb, TDB_DEBUG_ERROR,
+ "Dead space at %d-%d (of %u)\n",
+ off, off + dead, tdb->map_size));
+ rec.rec_len = dead - sizeof(rec);
+ break;
+ case TDB_RECOVERY_MAGIC:
if (recovery_start != off) {
TDB_LOG((tdb, TDB_DEBUG_ERROR,
"Unexpected recovery record at offset %d\n",
@@ -379,7 +410,8 @@ int tdb_check(struct tdb_context *tdb,
}
found_recovery = true;
break;
- default:
+ default: ;
+ corrupt:
tdb->ecode = TDB_ERR_CORRUPT;
TDB_LOG((tdb, TDB_DEBUG_ERROR,
"Bad magic 0x%x at offset %d\n",
@@ -405,9 +437,8 @@ int tdb_check(struct tdb_context *tdb,
/* We must have found recovery area if there was one. */
if (recovery_start != 0 && !found_recovery) {
TDB_LOG((tdb, TDB_DEBUG_ERROR,
- "Expected %s recovery area, got %s\n",
- recovery_start ? "a" : "no",
- found_recovery ? "one" : "none"));
+ "Expected a recovery area at %u\n",
+ recovery_start));
goto free;
}