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Re: kern/38460: fstrans_start code in genfs_do_putpages is racy



The following reply was made to PR kern/38460; it has been noted by GNATS.

From: Juergen Hannken-Illjes <hannken%eis.cs.tu-bs.de@localhost>
To: YAMAMOTO Takashi <yamt%mwd.biglobe.ne.jp@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/38460: fstrans_start code in genfs_do_putpages is racy
Date: Sat, 19 Apr 2008 13:37:16 +0200

 On Sat, Apr 19, 2008 at 07:38:38PM +0900, YAMAMOTO Takashi wrote:
 > > On Sat, Apr 19, 2008 at 08:05:00AM +0000, yamt%mwd.biglobe.ne.jp@localhost 
 > > wrote:
 > > > >Synopsis:       fstrans_start code in genfs_do_putpages is racy
 > > 
 > > This diff should fix it. Ok?
 > 
 > doesn't it break the existing "goto retry"?
 
 Yes.  This one should work. Ok?
 
 -- 
 Juergen Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig 
(Germany)
 
 Index: genfs_io.c
 ===================================================================
 RCS file: /cvsroot/src/sys/miscfs/genfs/genfs_io.c,v
 retrieving revision 1.5
 diff -p -u -2 -r1.5 genfs_io.c
 --- genfs_io.c 18 Jan 2008 11:01:23 -0000      1.5
 +++ genfs_io.c 19 Apr 2008 11:09:28 -0000
 @@ -779,7 +779,8 @@ genfs_do_putpages(struct vnode *vp, off_
            vp, uobj->uo_npages, startoff, endoff - startoff);
  
 +      has_trans = false;
 +
  retry:
        modified = false;
 -      has_trans = false;
        flags = origflags;
        KASSERT((vp->v_iflag & VI_ONWORKLST) != 0 ||
 @@ -791,4 +792,6 @@ retry:
                                vn_syncer_remove_from_worklist(vp);
                }
 +              if (has_trans)
 +                      fstrans_done(vp->v_mount);
                mutex_exit(slock);
                return (0);
 @@ -799,5 +802,5 @@ retry:
         */
  
 -      if ((flags & PGO_CLEANIT) != 0) {
 +      if (!has_trans && (flags & PGO_CLEANIT) != 0) {
                mutex_exit(slock);
                if (pagedaemon) {
 @@ -809,4 +812,5 @@ retry:
                has_trans = true;
                mutex_enter(slock);
 +              goto retry;
        }
  
 @@ -1169,7 +1173,4 @@ skip_scan:
        mutex_exit(slock);
  
 -      if (has_trans)
 -              fstrans_done(vp->v_mount);
 -
        if ((flags & PGO_RECLAIM) != 0 && onworklst) {
                /*
 @@ -1182,4 +1183,7 @@ skip_scan:
        }
  
 +      if (has_trans)
 +              fstrans_done(vp->v_mount);
 +
        return (error);
  }
 


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