On Thu, 2019-06-13 at 18:47 +0300, Amir Goldstein wrote: > On Thu, Jun 13, 2019 at 5:32 PM J . Bruce Fields <bfields@xxxxxxxxxxxx> wrote: > > On Thu, Jun 13, 2019 at 04:13:15PM +0200, Miklos Szeredi wrote: > > > On Wed, Jun 12, 2019 at 8:31 PM J . Bruce Fields <bfields@xxxxxxxxxxxx> wrote: > > > > How do opens for execute work? I guess they create a struct file with > > > > FMODE_EXEC and FMODE_RDONLY set and they decrement i_writecount. Do > > > > they also increment i_readcount? Reading do_open_execat and alloc_file, > > > > looks like it does, so, good, they should conflict with write leases, > > > > which sounds right. > > > > > > Right, but then why this: > > > > > > > > + /* Eliminate deny writes from actual writers count */ > > > > > + if (wcount < 0) > > > > > + wcount = 0; > > > > > > It's basically a no-op, as you say. And it doesn't make any sense > > > logically, since denying writes *should* deny write leases as well... > > > > Yes. I feel like the negative writecount case is a little nonobvious, > > so maybe replace that by a comment, something like this?: > > > > --b. > > > > diff --git a/fs/locks.c b/fs/locks.c > > index 2056595751e8..379829b913c1 100644 > > --- a/fs/locks.c > > +++ b/fs/locks.c > > @@ -1772,11 +1772,12 @@ check_conflicting_open(struct file *filp, const long arg, int flags) > > if (arg == F_RDLCK && wcount > 0) > > return -EAGAIN; > > > > - /* Eliminate deny writes from actual writers count */ > > - if (wcount < 0) > > - wcount = 0; > > - > > - /* Make sure that only read/write count is from lease requestor */ > > + /* > > + * Make sure that only read/write count is from lease requestor. > > + * Note that this will result in denying write leases when wcount > > + * is negative, which is what we want. (We shouldn't grant > > + * write leases on files open for execution.) > > + */ > > if (filp->f_mode & FMODE_WRITE) > > self_wcount = 1; > > else if (filp->f_mode & FMODE_READ) > > I'm fine with targeting 5.3 and I'm fine with all suggested changes > and adding some of my own. At this point we no longer need wcount > variable and code becomes more readable without it. > See attached patch (also tested). > > Thanks, > Amir. Thanks Amir. In that case, I'll go ahead and pick this up for v5.3, and will get it into linux-next soon. Thanks, -- Jeff Layton <jlayton@xxxxxxxxxx>
