On Fri, Mar 21, 2008 at 02:44:39AM -1000, Jeff Roberson wrote: > On Fri, 21 Mar 2008, Konstantin Belousov wrote: > > >kib 2008-03-21 12:33:00 UTC > > > > FreeBSD src repository > > > > Modified files: > > sys/ufs/ffs ffs_vnops.c > > Log: > > Reduce the acquisition of the vnode interlock in the ffs_read() and > > ffs_extread() when setting the IN_ACCESS flag by checking whether the > > IN_ACCESS is already set. The possible race there is admissible. > > I don't believe there is a race because we should always hold an exclusive > vnode lock and the vnode interlock when clearing. The exclusive node lock We may hold only the shared vnode lock and the interlock when clearing, in the ufs_itimes().
> would prevent ffs_read() from executing entirely, so we don't have to > worry about races with clearing the bit. Races to set the bit are handled > by the vnode interlock. Yes, the race I meant is the clearing of the IN_ACCESS while performing unlocked read for check. It may be considered as a race, may be not. > > I should also mention that while this may seem innocuous enough this > figured heavily in LOCK_PROFILING for a real workload. > > Thanks, > Jeff > > > > > Tested by: pho > > Submitted by: jeff > > > > Revision Changes Path > > 1.180 +4 -2 src/sys/ufs/ffs/ffs_vnops.c > >
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