HAMMER mirroring - Multiple adjustments to support better incremental ops

* Read side - Ignore records created after the end point, reducing
  network bandwidth for incremental operations.

* Read side - Generate PASS for records created prior to tid_beg, instead
  of pushing the whole record, reducting network bandwidth for incremental
  operations.

* Write side - Ensure that deletions are end-exclusive.

* Write side - Do not delete records created >= end point, supporting
  incremental operations.

diff --git a/sys/vfs/hammer/hammer_mirror.c b/sys/vfs/hammer/hammer_mirror.c
index 3c4b966..78f8027 100644 (file)
--- a/sys/vfs/hammer/hammer_mirror.c
+++ b/sys/vfs/hammer/hammer_mirror.c
@@ -194,6 +194,17 @@ retry:
                mirror->key_cur = elm->base;
 
                /*
+                * If the record was created after our end point we just
+                * ignore it.
+                */
+               if (elm->base.create_tid > mirror->tid_end) {
+                       error = 0;
+                       bytes = 0;
+                       eatdisk = 1;
+                       goto didwrite;
+               }
+
+               /*
                 * Determine if we should generate a PASS or a REC.  PASS
                 * records are records without any data payload.  Such
                 * records will be generated if the target is already expected
@@ -206,8 +217,7 @@ retry:
                 * master are no-history, or if the slave is so far behind
                 * the master has already been pruned.
                 */
-               if (elm->base.create_tid < mirror->tid_beg ||
-                   elm->base.create_tid > mirror->tid_end) {
+               if (elm->base.create_tid < mirror->tid_beg) {
                        bytes = sizeof(mrec.rec);
                        if (mirror->count + HAMMER_HEAD_DOALIGN(bytes) >
                            mirror->size) {
@@ -487,7 +497,7 @@ hammer_ioc_mirror_write(hammer_transaction_t trans, hammer_inode_t ip,
  * Handle skip records.
  *
  * We must iterate from the last resolved record position at mirror->key_cur
- * to skip_beg and delete any records encountered.
+ * to skip_beg non-inclusive and delete any records encountered.
  *
  * mirror->key_cur must be carefully set when we succeed in processing
  * this mrec.
@@ -510,9 +520,11 @@ hammer_ioc_mirror_write_skip(hammer_cursor_t cursor,
 
        /*
         * Iterate from current position to skip_beg, deleting any records
-        * we encounter.
+        * we encounter.  The record at skip_beg is not included (it is
+        * skipped).
         */
        cursor->key_end = mrec->skip_beg;
+       cursor->flags &= ~HAMMER_CURSOR_END_INCLUSIVE;
        cursor->flags |= HAMMER_CURSOR_BACKEND;
        error = hammer_mirror_delete_to(cursor, mirror);
 
@@ -655,7 +667,6 @@ hammer_ioc_mirror_write_pass(hammer_cursor_t cursor,
        cursor->key_end = mrec->leaf.base;
        cursor->flags &= ~HAMMER_CURSOR_END_INCLUSIVE;
        cursor->flags |= HAMMER_CURSOR_BACKEND;
-
        error = hammer_mirror_delete_to(cursor, mirror);
 
        /*
@@ -696,6 +707,9 @@ hammer_ioc_mirror_write_pass(hammer_cursor_t cursor,
  * The deletion should be picked up on the next sequence since in order
  * to have been deleted on the master a transaction must have occured with
  * a TID greater then the create_tid of the record.
+ *
+ * To support incremental re-mirroring, just for robustness, we do not
+ * touch any records created beyond (or equal to) mirror->tid_end.
  */
 static
 int
@@ -710,8 +724,13 @@ hammer_mirror_delete_to(hammer_cursor_t cursor,
                elm = &cursor->node->ondisk->elms[cursor->index].leaf;
                KKASSERT(elm->base.btype == HAMMER_BTREE_TYPE_RECORD);
                cursor->flags |= HAMMER_CURSOR_ATEDISK;
+
+               /*
+                * Note: Must still delete records with create_tid < tid_beg,
+                *       as record may have been pruned-away on source.
+                */
                if (elm->base.delete_tid == 0 &&
-                   elm->base.create_tid != mirror->tid_end) {
+                   elm->base.create_tid < mirror->tid_end) {
                        error = hammer_delete_at_cursor(cursor,
                                                        HAMMER_DELETE_ADJUST,
                                                        mirror->tid_end,