ntdb: allow direct access for NTDB_INTERNAL dbs during expansion.

NTDB_INTERNAL databases need to malloc and copy to keep old versions
around if we expand, in a similar way to the manner in which keep old
mmaps around.

Of course, it only works for read-only accesses, since the two copies
are not synced.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/lib/ntdb/io.c b/lib/ntdb/io.c
index 6749d282d91247e9064db61338ff256cac08edfb..7645cddc373f2f8228e734f6fa82769a76e58ad2 100644 (file)
--- a/lib/ntdb/io.c
+++ b/lib/ntdb/io.c
@@ -36,11 +36,34 @@ static void free_old_mmaps(struct ntdb_context *ntdb)
 
        while ((i = ntdb->file->old_mmaps) != NULL) {
                ntdb->file->old_mmaps = i->next;
-               munmap(i->map_ptr, i->map_size);
+               if (ntdb->flags & NTDB_INTERNAL) {
+                       ntdb->free_fn(i->map_ptr, ntdb->alloc_data);
+               } else {
+                       munmap(i->map_ptr, i->map_size);
+               }
                ntdb->free_fn(i, ntdb->alloc_data);
        }
 }
 
+static enum NTDB_ERROR save_old_map(struct ntdb_context *ntdb)
+{
+       struct ntdb_old_mmap *old;
+
+       assert(ntdb->file->direct_count);
+
+       old = ntdb->alloc_fn(ntdb->file, sizeof(*old), ntdb->alloc_data);
+       if (!old) {
+               return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
+                                  "save_old_map alloc failed");
+       }
+       old->next = ntdb->file->old_mmaps;
+       old->map_ptr = ntdb->file->map_ptr;
+       old->map_size = ntdb->file->map_size;
+       ntdb->file->old_mmaps = old;
+
+       return NTDB_SUCCESS;
+}
+
 enum NTDB_ERROR ntdb_munmap(struct ntdb_context *ntdb)
 {
        if (ntdb->file->fd == -1) {
@@ -53,16 +76,7 @@ enum NTDB_ERROR ntdb_munmap(struct ntdb_context *ntdb)
 
        /* We can't unmap now if there are accessors. */
        if (ntdb->file->direct_count) {
-               struct ntdb_old_mmap *old
-                       = ntdb->alloc_fn(ntdb, sizeof(*old), ntdb->alloc_data);
-               if (!old) {
-                       return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
-                                          "ntdb_munmap alloc failed");
-               }
-               old->next = ntdb->file->old_mmaps;
-               old->map_ptr = ntdb->file->map_ptr;
-               old->map_size = ntdb->file->map_size;
-               ntdb->file->old_mmaps = old;
+               return save_old_map(ntdb);
        } else {
                munmap(ntdb->file->map_ptr, ntdb->file->map_size);
                ntdb->file->map_ptr = NULL;
@@ -434,9 +448,26 @@ static enum NTDB_ERROR ntdb_expand_file(struct ntdb_context *ntdb,
        }
 
        if (ntdb->flags & NTDB_INTERNAL) {
-               char *new = ntdb->expand_fn(ntdb->file->map_ptr,
-                                       ntdb->file->map_size + addition,
-                                       ntdb->alloc_data);
+               char *new;
+
+               /* Can't free it if we have direct accesses. */
+               if (ntdb->file->direct_count) {
+                       ecode = save_old_map(ntdb);
+                       if (ecode) {
+                               return ecode;
+                       }
+                       new = ntdb->alloc_fn(ntdb->file,
+                                            ntdb->file->map_size + addition,
+                                            ntdb->alloc_data);
+                       if (new) {
+                               memcpy(new, ntdb->file->map_ptr,
+                                      ntdb->file->map_size);
+                       }
+               } else {
+                       new = ntdb->expand_fn(ntdb->file->map_ptr,
+                                             ntdb->file->map_size + addition,
+                                             ntdb->alloc_data);
+               }
                if (!new) {
                        return ntdb_logerr(ntdb, NTDB_ERR_OOM, NTDB_LOG_ERROR,
                                          "No memory to expand database");