svn commit: r318933 - in vendor-sys/illumos/dist/uts/common: fs fs/zfs sys
Andriy Gapon
avg at FreeBSD.org
Fri May 26 11:39:36 UTC 2017
Author: avg
Date: Fri May 26 11:39:34 2017
New Revision: 318933
URL: https://svnweb.freebsd.org/changeset/base/318933
Log:
8064 need a static DTrace probe in VN_HOLD
illumos/illumos-gate at ade42b557a6e29c3d17a61b1535d99af10e379be
https://github.com/illumos/illumos-gate/commit/ade42b557a6e29c3d17a61b1535d99af10e379be
https://www.illumos.org/issues/8064
It's currently nearly impossible to trace what process places a hold on
a vnode, as the only ways holds are place is via the `VN_HOLD()` and
`VN_HOLD_CALLER()` macros, which inline the bumping of `v_count`. Adding
static DTrace probes to these macros would enable tracing of where
specific vnode references come from.
For completeness and symmetry, a similar static probe should be added to
`vn_rele()` and `vn_rele_dnlc()`.
Reviewed by: Pavel Zakharov <pavel.zakharov at delphix.com>
Reviewed by: Prakash Surya <prakash.surya at delphix.com>
Reviewed by: Prashanth Sreenivasa <pks at delphix.com>
Reviewed by: Matthew Ahrens <mahrens at delphix.com>
Approved by: Robert Mustacchi <rm at joyent.com>
Author: Sebastien Roy <seb at delphix.com>
Modified:
vendor-sys/illumos/dist/uts/common/fs/gfs.c
vendor-sys/illumos/dist/uts/common/fs/vnode.c
vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c
vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c
vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_znode.c
vendor-sys/illumos/dist/uts/common/sys/vnode.h
Modified: vendor-sys/illumos/dist/uts/common/fs/gfs.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/gfs.c Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/fs/gfs.c Fri May 26 11:39:34 2017 (r318933)
@@ -23,8 +23,9 @@
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
-
-#pragma ident "%Z%%M% %I% %E% SMI"
+/*
+ * Copyright (c) 2017 by Delphix. All rights reserved.
+ */
#include <sys/types.h>
#include <sys/cmn_err.h>
@@ -671,7 +672,7 @@ found:
}
vn_free(vp);
} else {
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
data = NULL;
mutex_exit(&vp->v_lock);
if (vp->v_flag & V_XATTRDIR) {
Modified: vendor-sys/illumos/dist/uts/common/fs/vnode.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/vnode.c Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/fs/vnode.c Fri May 26 11:39:34 2017 (r318933)
@@ -22,6 +22,8 @@
/*
* Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
+ * Copyright 2016 Nexenta Systems, Inc. All rights reserved.
+ * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
*/
/* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
@@ -836,7 +838,7 @@ vn_rele(vnode_t *vp)
VOP_INACTIVE(vp, CRED(), NULL);
return;
}
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
mutex_exit(&vp->v_lock);
}
@@ -857,15 +859,15 @@ vn_rele_dnlc(vnode_t *vp)
VOP_INACTIVE(vp, CRED(), NULL);
return;
}
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
}
mutex_exit(&vp->v_lock);
}
/*
* Like vn_rele() except that it clears v_stream under v_lock.
- * This is used by sockfs when it dismantels the association between
- * the sockfs node and the vnode in the underlaying file system.
+ * This is used by sockfs when it dismantles the association between
+ * the sockfs node and the vnode in the underlying file system.
* v_lock has to be held to prevent a thread coming through the lookupname
* path from accessing a stream head that is going away.
*/
@@ -880,7 +882,7 @@ vn_rele_stream(vnode_t *vp)
VOP_INACTIVE(vp, CRED(), NULL);
return;
}
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
mutex_exit(&vp->v_lock);
}
@@ -911,7 +913,7 @@ vn_rele_async(vnode_t *vp, taskq_t *task
vp, TQ_SLEEP) != NULL);
return;
}
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
mutex_exit(&vp->v_lock);
}
Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_ctldir.c Fri May 26 11:39:34 2017 (r318933)
@@ -20,7 +20,7 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
* Copyright 2015, OmniTI Computer Consulting, Inc. All rights reserved.
*/
@@ -1210,7 +1210,7 @@ zfsctl_snapshot_inactive(vnode_t *vp, cr
mutex_enter(&vp->v_lock);
if (vp->v_count > 1) {
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
mutex_exit(&vp->v_lock);
mutex_exit(&sdp->sd_lock);
VN_RELE(dvp);
Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c Fri May 26 11:39:34 2017 (r318933)
@@ -21,7 +21,7 @@
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
* Copyright (c) 2014 Integros [integros.com]
* Copyright 2015 Joyent, Inc.
* Copyright 2017 Nexenta Systems, Inc.
@@ -1819,7 +1819,7 @@ top:
ASSERT0(error);
}
mutex_enter(&vp->v_lock);
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
ASSERT0(vp->v_count);
mutex_exit(&vp->v_lock);
mutex_exit(&zp->z_lock);
@@ -4411,7 +4411,7 @@ zfs_inactive(vnode_t *vp, cred_t *cr, ca
mutex_enter(&zp->z_lock);
mutex_enter(&vp->v_lock);
ASSERT(vp->v_count == 1);
- vp->v_count = 0;
+ VN_RELE_LOCKED(vp);
mutex_exit(&vp->v_lock);
mutex_exit(&zp->z_lock);
rw_exit(&zfsvfs->z_teardown_inactive_lock);
Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_znode.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_znode.c Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_znode.c Fri May 26 11:39:34 2017 (r318933)
@@ -20,7 +20,7 @@
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
* Copyright (c) 2014 Integros [integros.com]
*/
@@ -1293,7 +1293,7 @@ zfs_zinactive(znode_t *zp)
mutex_enter(&zp->z_lock);
mutex_enter(&vp->v_lock);
- vp->v_count--;
+ VN_RELE_LOCKED(vp);
if (vp->v_count > 0 || vn_has_cached_data(vp)) {
/*
* If the hold count is greater than zero, somebody has
Modified: vendor-sys/illumos/dist/uts/common/sys/vnode.h
==============================================================================
--- vendor-sys/illumos/dist/uts/common/sys/vnode.h Fri May 26 11:37:11 2017 (r318932)
+++ vendor-sys/illumos/dist/uts/common/sys/vnode.h Fri May 26 11:39:34 2017 (r318933)
@@ -22,6 +22,7 @@
/*
* Copyright (c) 1988, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
*/
/* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */
@@ -53,6 +54,7 @@
#include <sys/list.h>
#ifdef _KERNEL
#include <sys/buf.h>
+#include <sys/sdt.h>
#endif /* _KERNEL */
#ifdef __cplusplus
@@ -1342,10 +1344,32 @@ int vn_vmpss_usepageio(vnode_t *);
*/
extern uint_t pvn_vmodsort_supported;
-#define VN_HOLD(vp) { \
- mutex_enter(&(vp)->v_lock); \
- (vp)->v_count++; \
- mutex_exit(&(vp)->v_lock); \
+/*
+ * All changes to v_count should be done through VN_HOLD() or VN_RELE(), or
+ * one of their variants. This makes it possible to ensure proper locking,
+ * and to guarantee that all modifications are accompanied by a firing of
+ * the vn-hold or vn-rele SDT DTrace probe.
+ *
+ * Example DTrace command for tracing vnode references using these probes:
+ *
+ * dtrace -q -n 'sdt:::vn-hold,sdt:::vn-rele
+ * {
+ * this->vp = (vnode_t *)arg0;
+ * printf("%s %s(%p[%s]) %d\n", execname, probename, this->vp,
+ * this->vp->v_path == NULL ? "NULL" : stringof(this->vp->v_path),
+ * this->vp->v_count)
+ * }'
+ */
+#define VN_HOLD_LOCKED(vp) { \
+ ASSERT(mutex_owned(&(vp)->v_lock)); \
+ (vp)->v_count++; \
+ DTRACE_PROBE1(vn__hold, vnode_t *, vp); \
+}
+
+#define VN_HOLD(vp) { \
+ mutex_enter(&(vp)->v_lock); \
+ VN_HOLD_LOCKED(vp); \
+ mutex_exit(&(vp)->v_lock); \
}
#define VN_RELE(vp) { \
@@ -1356,6 +1380,13 @@ extern uint_t pvn_vmodsort_supported;
vn_rele_async(vp, taskq); \
}
+#define VN_RELE_LOCKED(vp) { \
+ ASSERT(mutex_owned(&(vp)->v_lock)); \
+ ASSERT((vp)->v_count >= 1); \
+ (vp)->v_count--; \
+ DTRACE_PROBE1(vn__rele, vnode_t *, vp); \
+}
+
#define VN_SET_VFS_TYPE_DEV(vp, vfsp, type, dev) { \
(vp)->v_vfsp = (vfsp); \
(vp)->v_type = (type); \
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