Illumos #3112, #3113, #3114

3112 ztest does not honor ZFS_DEBUG
3113 ztest should use watchpoints to protect frozen arc bufs
3114 some leaked nvlists in zfsdev_ioctl

Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: Matt Amdur <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Approved by: Eric Schrock <[email protected]>

References:
  https://www.illumos.org/issues/3112
  https://www.illumos.org/issues/3113
  https://www.illumos.org/issues/3114
  illumos/illumos-gate@cd1c8b85eb30b568e9816221430c479ace7a559d

The /proc/self/cmd watchpoint interface is specific to Solaris.
Therefore, the #3113 implementation was reworked to use the more
portable mprotect(2) system call.  When the pages are watched they
are marked read-only for protection.  Any write to the protected
address range immediately trigger a SIGSEGV.  The pages are marked
writable again when they are unwatched.

Ported-by: Brian Behlendorf <[email protected]>
Issue #1489

1 files changed, 17 insertions, 0 deletions

diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 7bdfbf738..91e7fdf35 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -1630,6 +1630,23 @@ spa_init(int mode)
 
 	spa_mode_global = mode;
 
+#ifndef _KERNEL
+	if (spa_mode_global != FREAD && dprintf_find_string("watch")) {
+		struct sigaction sa;
+
+		sa.sa_flags = SA_SIGINFO;
+		sigemptyset(&sa.sa_mask);
+		sa.sa_sigaction = arc_buf_sigsegv;
+
+		if (sigaction(SIGSEGV, &sa, NULL) == -1) {
+			perror("could not enable watchpoints: "
+			    "sigaction(SIGSEGV, ...) = ");
+		} else {
+			arc_watch = B_TRUE;
+		}
+	}
+#endif
+
 	fm_init();
 	refcount_init();
 	unique_init();