[src/trunk]: src/sys/kern If the vnode to vrelel() is already reclaimed there...

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c6de4ea88c38
branches:  trunk
changeset: 361603:c6de4ea88c38
user:      hannken <hannken%NetBSD.org@localhost>
date:      Thu Feb 17 14:38:06 2022 +0000

description:
If the vnode to vrelel() is already reclaimed there is no need
to lock or defer it.  Jump straight to decrement usecount and requeue.

diffstat:

 sys/kern/vfs_vnode.c |  139 ++++++++++++++++++++++++++------------------------
 1 files changed, 73 insertions(+), 66 deletions(-)

diffs (189 lines):

diff -r b669d0ebdd9c -r c6de4ea88c38 sys/kern/vfs_vnode.c
--- a/sys/kern/vfs_vnode.c      Thu Feb 17 14:33:25 2022 +0000
+++ b/sys/kern/vfs_vnode.c      Thu Feb 17 14:38:06 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_vnode.c,v 1.130 2022/02/12 15:51:29 thorpej Exp $  */
+/*     $NetBSD: vfs_vnode.c,v 1.131 2022/02/17 14:38:06 hannken Exp $  */
 
 /*-
  * Copyright (c) 1997-2011, 2019, 2020 The NetBSD Foundation, Inc.
@@ -148,7 +148,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.130 2022/02/12 15:51:29 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_vnode.c,v 1.131 2022/02/17 14:38:06 hannken Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_pax.h"
@@ -811,6 +811,20 @@
 #endif
 
        /*
+        * If already clean there is no need to lock, defer or
+        * deactivate this node.
+        */
+       if (VSTATE_GET(vp) == VS_RECLAIMED) {
+               if (lktype != LK_NONE) {
+                       mutex_exit(vp->v_interlock);
+                       lktype = LK_NONE;
+                       VOP_UNLOCK(vp);
+                       mutex_enter(vp->v_interlock);
+               }
+               goto out;
+       }
+
+       /*
         * First try to get the vnode locked for VOP_INACTIVE().
         * Defer vnode release to vdrain_thread if caller requests
         * it explicitly, is the pagedaemon or the lock failed.
@@ -820,8 +834,7 @@
                defer = true;
        } else if (lktype == LK_SHARED) {
                /* Excellent chance of getting, if the last ref. */
-               error = vn_lock(vp, LK_UPGRADE | LK_RETRY |
-                   LK_NOWAIT);
+               error = vn_lock(vp, LK_UPGRADE | LK_RETRY | LK_NOWAIT);
                if (error != 0) {
                        defer = true;
                } else {
@@ -829,8 +842,7 @@
                }
        } else if (lktype == LK_NONE) {
                /* Excellent chance of getting, if the last ref. */
-               error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY |
-                   LK_NOWAIT);
+               error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY | LK_NOWAIT);
                if (error != 0) {
                        defer = true;
                } else {
@@ -853,74 +865,69 @@
        KASSERT(lktype == LK_EXCLUSIVE);
 
        /*
-        * If not clean, deactivate the vnode, but preserve
-        * our reference across the call to VOP_INACTIVE().
+        * Deactivate the vnode, but preserve our reference across
+        * the call to VOP_INACTIVE().
+        *
+        * If VOP_INACTIVE() indicates that the file has been
+        * deleted, then recycle the vnode.
+        *
+        * Note that VOP_INACTIVE() will not drop the vnode lock.
         */
-       if (VSTATE_GET(vp) == VS_RECLAIMED) {
-               VOP_UNLOCK(vp);
-       } else {
-               /*
-                * If VOP_INACTIVE() indicates that the file has been
-                * deleted, then recycle the vnode.
-                *
-                * Note that VOP_INACTIVE() will not drop the vnode lock.
-                */
-               mutex_exit(vp->v_interlock);
-               recycle = false;
-               VOP_INACTIVE(vp, &recycle);
-               rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
-               mutex_enter(vp->v_interlock);
+       mutex_exit(vp->v_interlock);
+       recycle = false;
+       VOP_INACTIVE(vp, &recycle);
+       rw_enter(vp->v_uobj.vmobjlock, RW_WRITER);
+       mutex_enter(vp->v_interlock);
 
-               for (;;) {
-                       /*
-                        * If no longer the last reference, try to shed it. 
-                        * On success, drop the interlock last thereby
-                        * preventing the vnode being freed behind us.
-                        */
-                       if (vtryrele(vp)) {
-                               VOP_UNLOCK(vp);
-                               rw_exit(vp->v_uobj.vmobjlock);
-                               mutex_exit(vp->v_interlock);
-                               return;
+       for (;;) {
+               /*
+                * If no longer the last reference, try to shed it. 
+                * On success, drop the interlock last thereby
+                * preventing the vnode being freed behind us.
+                */
+               if (vtryrele(vp)) {
+                       VOP_UNLOCK(vp);
+                       rw_exit(vp->v_uobj.vmobjlock);
+                       mutex_exit(vp->v_interlock);
+                       return;
+               }
+               /*
+                * Block new references then check again to see if a
+                * new reference was acquired in the meantime.  If
+                * it was, restore the vnode state and try again.
+                */
+               if (recycle) {
+                       VSTATE_CHANGE(vp, VS_LOADED, VS_BLOCKED);
+                       if (vrefcnt(vp) != 1) {
+                               VSTATE_CHANGE(vp, VS_BLOCKED, VS_LOADED);
+                               continue;
                        }
-                       /*
-                        * Block new references then check again to see if a
-                        * new reference was acquired in the meantime.  If
-                        * it was, restore the vnode state and try again.
-                        */
-                       if (recycle) {
-                               VSTATE_CHANGE(vp, VS_LOADED, VS_BLOCKED);
-                               if (vrefcnt(vp) != 1) {
-                                       VSTATE_CHANGE(vp, VS_BLOCKED,
-                                           VS_LOADED);
-                                       continue;
-                               }
-                       }
-                       break;
+               }
+               break;
                }
 
-               /* Take care of space accounting. */
-               if ((vp->v_iflag & VI_EXECMAP) != 0) {
-                       cpu_count(CPU_COUNT_EXECPAGES, -vp->v_uobj.uo_npages);
-               }
-               vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP|VI_WRMAP);
-               vp->v_vflag &= ~VV_MAPPED;
-               rw_exit(vp->v_uobj.vmobjlock);
+       /* Take care of space accounting. */
+       if ((vp->v_iflag & VI_EXECMAP) != 0) {
+               cpu_count(CPU_COUNT_EXECPAGES, -vp->v_uobj.uo_npages);
+       }
+       vp->v_iflag &= ~(VI_TEXT|VI_EXECMAP|VI_WRMAP);
+       vp->v_vflag &= ~VV_MAPPED;
+       rw_exit(vp->v_uobj.vmobjlock);
 
-               /*
-                * Recycle the vnode if the file is now unused (unlinked),
-                * otherwise just free it.
-                */
-               if (recycle) {
-                       VSTATE_ASSERT(vp, VS_BLOCKED);
-                       /* vcache_reclaim drops the lock. */
-                       vcache_reclaim(vp);
-               } else {
-                       VOP_UNLOCK(vp);
-               }
-               KASSERT(vrefcnt(vp) > 0);
+       /*
+        * Recycle the vnode if the file is now unused (unlinked),
+        * otherwise just free it.
+        */
+       if (recycle) {
+               VSTATE_ASSERT(vp, VS_BLOCKED);
+               /* vcache_reclaim drops the lock. */
+               vcache_reclaim(vp);
+       } else {
+               VOP_UNLOCK(vp);
        }
+       KASSERT(vrefcnt(vp) > 0);
 
+out:
        if ((atomic_dec_uint_nv(&vp->v_usecount) & VUSECOUNT_MASK) != 0) {
                /* Gained another reference while being reclaimed. */
                mutex_exit(vp->v_interlock);