krb5 commit: Fix MPOOL_IGNOREPIN to ease btree debugging

[Tom Yu]

https://github.com/krb5/krb5/commit/e6b4a19a546e0a171a416261cb06dfcc8e607e7b
commit e6b4a19a546e0a171a416261cb06dfcc8e607e7b
Author: Tom Yu <tlyu at mit.edu>
Date:   Mon Aug 8 09:06:16 2016 -0400

    Fix MPOOL_IGNOREPIN to ease btree debugging
    
    Various libdb2 test programs use the MPOOL_IGNOREPIN flag to examine
    arbitrary mpool pages that may or may not be pinned.  This flag is
    apparently intended to allow fetching pages that are already pinned,
    and to avoid setting the MPOOL_PINNED flag.  When there was a cache
    hit, mpool_get was setting MPOOL_PINNED anyway, causing aborts when
    using debugging programs such as dbtest and bttest.
    
    Fix this inconsistency by not setting MPOOL_PINNED when returning a
    cached page when the caller requested MPOOL_IGNOREPIN.  In bttest, add
    MPOOL_IGNOREPIN to allow dumping of pages while they are pinned
    without disrupting their pinned status.
    
    ticket: 8478

 src/plugins/kdb/db2/libdb2/mpool/mpool.c           |    3 ++-
 src/plugins/kdb/db2/libdb2/test/btree.tests/main.c |    3 +--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/plugins/kdb/db2/libdb2/mpool/mpool.c b/src/plugins/kdb/db2/libdb2/mpool/mpool.c
index 8dcda69..79ad613 100644
--- a/src/plugins/kdb/db2/libdb2/mpool/mpool.c
+++ b/src/plugins/kdb/db2/libdb2/mpool/mpool.c
@@ -214,7 +214,8 @@ mpool_get(mp, pgno, flags)
 		TAILQ_INSERT_TAIL(&mp->lqh, bp, q);
 
 		/* Return a pinned page. */
-		bp->flags |= MPOOL_PINNED;
+		if (!(flags & MPOOL_IGNOREPIN))
+			bp->flags |= MPOOL_PINNED;
 		return (bp->page);
 	}
 
diff --git a/src/plugins/kdb/db2/libdb2/test/btree.tests/main.c b/src/plugins/kdb/db2/libdb2/test/btree.tests/main.c
index 78195d6..5b9890b 100644
--- a/src/plugins/kdb/db2/libdb2/test/btree.tests/main.c
+++ b/src/plugins/kdb/db2/libdb2/test/btree.tests/main.c
@@ -785,7 +785,7 @@ show(db, argv)
 
 	pg = atoi(argv[1]);
 	t = db->internal;
-	if ((h = mpool_get(t->bt_mp, pg, 0)) == NULL) {
+	if ((h = mpool_get(t->bt_mp, pg, MPOOL_IGNOREPIN)) == NULL) {
 		(void)printf("getpage of %ld failed\n", pg);
 		return;
 	}
@@ -793,7 +793,6 @@ show(db, argv)
 		__bt_dmpage(h);
 	else
 		__bt_dpage(db, h);
-	mpool_put(t->bt_mp, h, 0);
 }
 #endif