Date: Fri, 14 May 2021 21:04:01 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Mateusz Guzik <mjg@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: b5fb9ae6872c - main - vfs: lockless writecount adjustment in set/unset text Message-ID: <YJ67kVMW4jJV%2B3k8@kib.kiev.ua> In-Reply-To: <202105141423.14EENtDX058648@gitrepo.freebsd.org> References: <202105141423.14EENtDX058648@gitrepo.freebsd.org>
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On Fri, May 14, 2021 at 02:23:55PM +0000, Mateusz Guzik wrote: > The branch main has been updated by mjg: > > URL: https://cgit.FreeBSD.org/src/commit/?id=b5fb9ae6872c499f1a02bec41f48b163a73a2aaa > > commit b5fb9ae6872c499f1a02bec41f48b163a73a2aaa > Author: Mateusz Guzik <mjg@FreeBSD.org> > AuthorDate: 2021-05-07 14:04:27 +0000 > Commit: Mateusz Guzik <mjg@FreeBSD.org> > CommitDate: 2021-05-14 14:22:21 +0000 > > vfs: lockless writecount adjustment in set/unset text > > ... for cases where this is not the first/last exec. > --- > sys/kern/vfs_default.c | 32 ++++++++++++++++++++++++++++++-- > 1 file changed, 30 insertions(+), 2 deletions(-) > > diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c > index cf224981cbe7..3518bbeaa279 100644 > --- a/sys/kern/vfs_default.c > +++ b/sys/kern/vfs_default.c > @@ -1177,9 +1177,23 @@ vop_stdset_text(struct vop_set_text_args *ap) > { > struct vnode *vp; > struct mount *mp; > - int error; > + int error, n; > > vp = ap->a_vp; > + > + /* > + * Avoid the interlock if execs are already present. > + */ > + n = atomic_load_int(&vp->v_writecount); > + for (;;) { > + if (n > -1) { > + break; If you split the VOP for tmpfs/non-tmpfs implementations, then non-tmpfs can go with the atomics only.
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