On Thu, Apr 25, 2024 at 8:51 PM Rick Macklem <rick.mack...@gmail.com> wrote: > > On Thu, Apr 25, 2024 at 8:09 PM Konstantin Belousov <k...@freebsd.org> wrote: > > > > On Thu, Apr 25, 2024 at 07:49:23PM -0700, Rick Macklem wrote: > > > Hi, > > > > > > This week I have been doing active testing as a part of an IETF > > > bakeathon for NFSv4. During the week I had a NFSv4 client > > > crash. On the surface, it is straightforward, in that it called > > > ncl_doio_directwrite() and the field called b_caller1 was NULL. > > > > > > Now, here's the weird part... > > > ncl_doio_directwrite() should never be called because B_DIRECT > > > should never be set. (The only place B_DIRECT gets set in the code > > > is never currently executed.) > > Do you mean the place in nfs_directio_write()? And the fact that > > IO_SYNC is always set. > Yes. > > > > > > > > > I have a patch that clears out the "never to be executed" code and > > > this seems to avoid the patch, since with the patch, > > > ncl_doio_directwrite() > > > no longer exists. > > > > > > What I cannot figure out is how B_DIRECT got set? > > > I can note that UFS was under heavy load when the client crashed, > > > but I cannot see how a UFS "struct buf" would become a NFS "struct buf" > > > without b_flags being set to 0. > > > > There are also vfs_bio_brelse()/vfs_bio_setflags() functions which can > > set B_DIRECT. On the other hand, they are not used by nfs client. > Yes, again. > > > > > What was the overall state of the buffer with the B_DIRECT flag? Which > > vnode it was assigned to? > Unfortunately I was in a hurry and didn't get more info. > And, since I have never seen this crash before, I doubt I'll be able > to reproduce it. Oh, and I will put the cleanup patch on phabricator. I didn't see the crash again during a few days of testing with the patch. This makes sense, since it gets rid of ncl_doio_directwrite().
> > Thanks, rick
