On Wed, 2021-03-31 at 16:34 -0400, Olga Kornievskaia wrote:
> On Wed, Mar 31, 2021 at 3:42 PM Trond Myklebust
> <trondmy@xxxxxxxxxxxxxxx> wrote:
> >
> > On Wed, 2021-03-31 at 15:30 -0400, Olga Kornievskaia wrote:
> > > From: Olga Kornievskaia <kolga@xxxxxxxxxx>
> > >
> > > Currently the client ignores the value of the sr_eof of the SEEK
> > > operation. According to the spec, if the server didn't find the
> > > requested extent and reached the end of the file, the server
> > > would return sr_eof=true. In case the request for DATA and no
> > > data was found (ie in the middle of the hole), then the lseek
> > > expects that ENXIO would be returned.
> > >
> > > Fixes: 1c6dcbe5ceff8 ("NFS: Implement SEEK")
> > > Signed-off-by: Olga Kornievskaia <kolga@xxxxxxxxxx>
> > > ---
> > > fs/nfs/nfs42proc.c | 5 ++++-
> > > 1 file changed, 4 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/nfs/nfs42proc.c b/fs/nfs/nfs42proc.c
> > > index 094024b0aca1..d359e712c11d 100644
> > > --- a/fs/nfs/nfs42proc.c
> > > +++ b/fs/nfs/nfs42proc.c
> > > @@ -659,7 +659,10 @@ static loff_t _nfs42_proc_llseek(struct file
> > > *filep,
> > > if (status)
> > > return status;
> > >
> > > - return vfs_setpos(filep, res.sr_offset, inode->i_sb-
> > > > s_maxbytes);
> > > + if (whence == SEEK_DATA && res.sr_eof)
> > > + return -NFS4ERR_NXIO;
> > > + else
> > > + return vfs_setpos(filep, res.sr_offset, inode-
> > > >i_sb-
> > > > s_maxbytes);
> > > }
> > >
> > > loff_t nfs42_proc_llseek(struct file *filep, loff_t offset, int
> > > whence)
> >
> > Don't we also need to deal with SEEK_HOLE with the offset being
> > greater
> > than the end-of-file in the same way?
>
> We do not because if there is no hole extent after the requested
> offset, then there is an implied hole which is at the end of the file.
> So if sr_eof is true we still need to pay attention to the returned
> offset (ie it should be end of the file) and it's not an error
> condition.
I'm asking because according to the manpage for lseek():
ENXIO whence is SEEK_DATA or SEEK_HOLE, and offset is beyond the end
of the file, or whence is SEEK_DATA and offset is within a hole
at the end of the file.
i.e. the manpage implies that we should also be returning an error for
SEEK_HOLE if the supplied offset is beyond eof. Are you saying that we
currently do so?
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
