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

problems with wipe_all on databases that may need crash recovery

diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c
index a25c3e7acadb6fdce377e8d4a406068d4fc4f010..767452c9b34b520a51bed6aace888b3f5b2dcd4f 100644 (file)
--- a/lib/tdb/common/tdb.c
+++ b/lib/tdb/common/tdb.c
@@ -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)
 {
@@ -735,43 +761,31 @@ 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;
-       } 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"));
+       /* 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;
                }
-       }
-
-       /* 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"));
+       } else {
+               /* 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;
                }
-               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;            
+               /* 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;
                }
        }