Re: kern/42205: kernel panic at activated userquota

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

The following reply was made to PR kern/42205; it has been noted by GNATS.

From: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
To: 6bone%6bone.informatik.uni-leipzig.de@localhost
Cc: gnats-bugs%NetBSD.org@localhost, kern-bug-people%NetBSD.org@localhost, 
gnats-admin%NetBSD.org@localhost,
        netbsd-bugs%NetBSD.org@localhost
Subject: Re: kern/42205: kernel panic  at activated userquota
Date: Mon, 26 Oct 2009 12:32:22 +0100

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 On Mon, Oct 26, 2009 at 06:49:31AM +0100, 
6bone%6bone.informatik.uni-leipzig.de@localhost wrote:
 > The patch works fine and solves the problem.
 
 Thanks. But, I think this was not the right way to fix the problem.
 Can you try the attached one instead ? It should fix your problem, and some
 others (including one that I fixed the wrong way some time ago, this is
 the code in #if 0/#endif in the patch).
 
 I'm running with this patch on several systems now and it seems to work fine.
 
 -- 
 Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
      NetBSD: 26 ans d'experience feront toujours la difference
 --
 
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 Index: sys/ufs/ufs/ufs_ihash.c
 ===================================================================
 RCS file: /cvsroot/src/sys/ufs/ufs/ufs_ihash.c,v
 retrieving revision 1.26.10.1
 diff -u -p -u -r1.26.10.1 ufs_ihash.c
 --- sys/ufs/ufs/ufs_ihash.c    28 Sep 2009 01:43:02 -0000      1.26.10.1
 +++ sys/ufs/ufs/ufs_ihash.c    24 Oct 2009 13:33:23 -0000
 @@ -152,6 +152,7 @@ ufs_ihashget(dev_t dev, ino_t inum, int 
                                mutex_exit(&ufs_ihash_lock);
                                if (vget(vp, flags | LK_INTERLOCK))
                                        goto loop;
 +#if 0
                                if (VTOI(vp) != ip ||
                                    ip->i_number != inum || ip->i_dev != dev) {
                                        /* lost race against vclean() */
 @@ -161,6 +162,7 @@ ufs_ihashget(dev_t dev, ino_t inum, int 
                                        vp = NULL;
                                        goto loop;
                                }
 +#endif
                        }
                        return (vp);
                }
 Index: sys/kern/vfs_subr.c
 ===================================================================
 RCS file: /cvsroot/src/sys/kern/vfs_subr.c,v
 retrieving revision 1.357.4.5
 diff -u -p -u -r1.357.4.5 vfs_subr.c
 --- sys/kern/vfs_subr.c        21 Jul 2009 00:31:58 -0000      1.357.4.5
 +++ sys/kern/vfs_subr.c        24 Oct 2009 13:33:23 -0000
 @@ -370,6 +370,17 @@ try_nextlist:
        vp->v_freelisthd = NULL;
        mutex_exit(&vnode_free_list_lock);
  
 +      if (vp->v_usecount != 0) {
 +              /*
 +               * was referenced again before we got the interlock
 +               * Don't return to freelist - the holder of the last
 +               * reference will destroy it.
 +               */
 +              vrelel(vp, 0); /* releases vp->v_interlock */
 +              mutex_enter(&vnode_free_list_lock);
 +              goto retry;
 +      }
 +
        /*
         * The vnode is still associated with a file system, so we must
         * clean it out before reusing it.  We need to add a reference
 @@ -1288,6 +1299,22 @@ vget(vnode_t *vp, int flags)
                vrelel(vp, 0);
                return ENOENT;
        }
 +
 +      if ((vp->v_iflag & VI_INACTNOW) != 0) {
 +              /*
 +               * if it's being desactived, wait for it to complete.
 +               * Make sure to not return a clean vnode.
 +               */
 +               if ((flags & LK_NOWAIT) != 0) {
 +                      vrelel(vp, 0);
 +                      return EBUSY;
 +              }
 +              vwait(vp, VI_INACTNOW);
 +              if ((vp->v_iflag & VI_CLEAN) != 0) {
 +                      vrelel(vp, 0);
 +                      return ENOENT;
 +              }
 +      }
        if (flags & LK_TYPE_MASK) {
                error = vn_lock(vp, flags | LK_INTERLOCK);
                if (error != 0) {
 @@ -1427,6 +1454,7 @@ vrelel(vnode_t *vp, int flags)
                        if (++vrele_pending > (desiredvnodes >> 8))
                                cv_signal(&vrele_cv); 
                        mutex_exit(&vrele_lock);
 +                      cv_broadcast(&vp->v_cv);
                        mutex_exit(&vp->v_interlock);
                        return;
                }
 @@ -1451,6 +1479,7 @@ vrelel(vnode_t *vp, int flags)
                VOP_INACTIVE(vp, &recycle);
                mutex_enter(&vp->v_interlock);
                vp->v_iflag &= ~VI_INACTNOW;
 +              cv_broadcast(&vp->v_cv);
                if (!recycle) {
                        if (vtryrele(vp)) {
                                mutex_exit(&vp->v_interlock);
 
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