MFC r271788 (by will):

Enable ZFS debug flags to be modified via vfs.zfs.debug_flags.

This is primarily only of interest to ZFS developers, but it makes it
easier to get additional debugging.

MFSpectraBSD:   517074 on 2011/12/15 (by will), 662343 on 2013/03/20 (by gibbs)

1 files changed, 27 insertions, 0 deletions

diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
index e18ffd2..924f012 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_misc.c
@@ -263,6 +263,33 @@ TUNABLE_INT("vfs.zfs.recover", &zfs_recover);
 SYSCTL_INT(_vfs_zfs, OID_AUTO, recover, CTLFLAG_RWTUN, &zfs_recover, 0,
     "Try to recover from otherwise-fatal errors.");
 
+static int
+sysctl_vfs_zfs_debug_flags(SYSCTL_HANDLER_ARGS)
+{
+	int err, val;
+
+	val = zfs_flags;
+	err = sysctl_handle_int(oidp, &val, 0, req);
+	if (err != 0 || req->newptr == NULL)
+		return (err);
+
+	/*
+	 * ZFS_DEBUG_MODIFY must be enabled prior to boot so all
+	 * arc buffers in the system have the necessary additional
+	 * checksum data.  However, it is safe to disable at any
+	 * time.
+	 */
+	if (!(zfs_flags & ZFS_DEBUG_MODIFY))
+		val &= ~ZFS_DEBUG_MODIFY;
+	zfs_flags = val;
+
+	return (0);
+}
+TUNABLE_INT("vfs.zfs.debug_flags", &zfs_flags);
+SYSCTL_PROC(_vfs_zfs, OID_AUTO, debug_flags,
+    CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, sizeof(int),
+    sysctl_vfs_zfs_debug_flags, "IU", "Debug flags for ZFS testing.");
+
 /*
  * If destroy encounters an EIO while reading metadata (e.g. indirect
  * blocks), space referenced by the missing metadata can not be freed.