There is a bug where mze_insert() can trigger an assert() of inserting

the same entry twice. This bug is not fixed yet, but leads to situation
where when try to access corrupted directory the kernel will panic.
Until the bug is properly fixed, try to recover from it and log that it
happened.

Reported by:	marck
OpenSolaris bug:	6709336
MFC after:	3 days

1 files changed, 16 insertions, 5 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c
index 75b43a6..cf99222 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zap_micro.c
@@ -181,10 +181,11 @@ mze_compare(const void *arg1, const void *arg2)
 	return (0);
 }
 
-static void
+static int
 mze_insert(zap_t *zap, int chunkid, uint64_t hash, mzap_ent_phys_t *mzep)
 {
 	mzap_ent_t *mze;
+	avl_index_t idx;
 
 	ASSERT(zap->zap_ismicro);
 	ASSERT(RW_WRITE_HELD(&zap->zap_rwlock));
@@ -194,7 +195,12 @@ mze_insert(zap_t *zap, int chunkid, uint64_t hash, mzap_ent_phys_t *mzep)
 	mze->mze_chunkid = chunkid;
 	mze->mze_hash = hash;
 	mze->mze_phys = *mzep;
-	avl_add(&zap->zap_m.zap_avl, mze);
+	if (avl_find(&zap->zap_m.zap_avl, mze, &idx) != NULL) {
+		kmem_free(mze, sizeof (mzap_ent_t));
+		return (EEXIST);
+	}
+	avl_insert(&zap->zap_m.zap_avl, mze, idx);
+	return (0);
 }
 
 static mzap_ent_t *
@@ -329,10 +335,15 @@ mzap_open(objset_t *os, uint64_t obj, dmu_buf_t *db)
 			if (mze->mze_name[0]) {
 				zap_name_t *zn;
 
-				zap->zap_m.zap_num_entries++;
 				zn = zap_name_alloc(zap, mze->mze_name,
 				    MT_EXACT);
-				mze_insert(zap, i, zn->zn_hash, mze);
+				if (mze_insert(zap, i, zn->zn_hash, mze) == 0)
+					zap->zap_m.zap_num_entries++;
+				else {
+					printf("ZFS WARNING: Duplicated ZAP "
+					    "entry detected (%s).",
+					    mze->mze_name);
+				}
 				zap_name_free(zn);
 			}
 		}
@@ -771,7 +782,7 @@ again:
 			if (zap->zap_m.zap_alloc_next ==
 			    zap->zap_m.zap_num_chunks)
 				zap->zap_m.zap_alloc_next = 0;
-			mze_insert(zap, i, zn->zn_hash, mze);
+			VERIFY(0 == mze_insert(zap, i, zn->zn_hash, mze));
 			return;
 		}
 	}