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Code

carefully step around the recovery area when doing a tdb_wipe_all. This prevents

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problems with wipe_all on databases that may need crash recovery

(This used to be ctdb commit e7b1349bf8784c151c2651edd99b3f40ebcece1f)
This commit is contained in:
Andrew Tridgell 2008-02-08 14:10:54 +11:00
parent 1ff6e08f78
commit f6ebcd6a55
1 changed files with 47 additions and 33 deletions
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80
ctdb/lib/tdb/common/tdb.c
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@ -686,10 +686,36 @@ void tdb_enable_seqnum(struct tdb_context *tdb)
}
/*
add a region of the file to the freelist. Length is the size of the region in bytes,
which includes the free list header that needs to be added
*/
static int tdb_free_region(struct tdb_context *tdb, tdb_off_t offset, ssize_t length)
{
struct list_struct rec;
if (length <= sizeof(rec)) {
/* the region is not worth adding */
return 0;
}
if (length + offset > tdb->map_size) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: adding region beyond end of file\n"));
return -1;
}
memset(&rec,'\0',sizeof(rec));
rec.rec_len = length - sizeof(rec);
if (tdb_free(tdb, offset, &rec) == -1) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_free_region: failed to add free record\n"));
return -1;
}
return 0;
}
/*
wipe the entire database, deleting all records. This can be done
very fast by using a global lock. The entire data portion of the
file becomes a single entry in the freelist.
This code carefully steps around the recovery area, leaving it alone
*/
int tdb_wipe_all(struct tdb_context *tdb)
{
@ -735,44 +761,32 @@ int tdb_wipe_all(struct tdb_context *tdb)
goto failed;
}
if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &offset) == -1) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write recovery head\n"));
goto failed;
}
/* add all the rest of the file to the freelist */
data_len = (tdb->map_size - TDB_DATA_START(tdb->header.hash_size)) - sizeof(struct list_struct);
if (data_len < recovery_size+sizeof(tdb_off_t)) {
recovery_size = 0;
/* add all the rest of the file to the freelist, possibly leaving a gap
for the recovery area */
if (recovery_size == 0) {
/* the simple case - the whole file can be used as a freelist */
data_len = (tdb->map_size - TDB_DATA_START(tdb->header.hash_size));
if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.hash_size), data_len) != 0) {
goto failed;
}
} else {
data_len -= recovery_size;
}
if (data_len > 0) {
struct list_struct rec;
memset(&rec,'\0',sizeof(rec));
rec.rec_len = data_len;
if (tdb_free(tdb, TDB_DATA_START(tdb->header.hash_size), &rec) == -1) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to add free record\n"));
/* we need to add two freelist entries - one on either
side of the recovery area
Note that we cannot shift the recovery area during
this operation. Only the transaction.c code may
move the recovery area or we risk subtle data
corruption
*/
data_len = (recovery_head - TDB_DATA_START(tdb->header.hash_size));
if (tdb_free_region(tdb, TDB_DATA_START(tdb->header.hash_size), data_len) != 0) {
goto failed;
}
}
/* possibly add the recovery record */
if (recovery_size != 0) {
struct list_struct rec;
recovery_head = tdb->map_size - recovery_size;
ZERO_STRUCT(rec);
rec.rec_len = recovery_size - sizeof(rec);
if (tdb_rec_write(tdb, recovery_head, &rec) != 0) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to add recovery record\n"));
/* and the 2nd free list entry after the recovery area - if any */
data_len = tdb->map_size - (recovery_head+recovery_size);
if (tdb_free_region(tdb, recovery_head+recovery_size, data_len) != 0) {
goto failed;
}
if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_wipe_all: failed to write recovery head\n"));
goto failed;
}
}
if (tdb_unlockall(tdb) != 0) {