Date: Wed, 3 May 2023 12:55:08 +0300 From: Dmitry Chagin <dchagin@freebsd.org> To: Mateusz Guzik <mjguzik@gmail.com> Cc: Mark Johnston <markj@freebsd.org>, Konstantin Belousov <kib@freebsd.org>, src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: a1d71cebc05c - main - fstatat(2): restore AT_EMPTY_PATH handling Message-ID: <ZFIvfM_v9TsQQsBs@heemeyer.club> In-Reply-To: <CAGudoHGX6wNZTVEs3hSrgkOVgdmsLUPDrEKVtzDzytWgUN5Yew@mail.gmail.com> References: <202305021512.342FCpbN056202@gitrepo.freebsd.org> <ZFFBke7JKtnwyj23@heemeyer.club> <ZFFexSTAU6hh8jI-@nuc> <ZFFj-Rks8P0L0zxu@heemeyer.club> <CAGudoHF_YvTYwMg5b5WNHgZqGA3B5bP0QJx9SuV3G4p_JpqGTw@mail.gmail.com> <CAGudoHGX6wNZTVEs3hSrgkOVgdmsLUPDrEKVtzDzytWgUN5Yew@mail.gmail.com>
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On Tue, May 02, 2023 at 11:08:23PM +0200, Mateusz Guzik wrote:
> On 5/2/23, Mateusz Guzik <mjguzik@gmail.com> wrote:
> > right, this should do it
> >
> > diff --git a/sys/kern/vfs_cache.c b/sys/kern/vfs_cache.c
> > index e4977392349f..b583eed5e249 100644
> > --- a/sys/kern/vfs_cache.c
> > +++ b/sys/kern/vfs_cache.c
> > @@ -4435,6 +4435,7 @@ cache_fplookup_dirfd(struct cache_fpl *fpl,
> > struct vnode **vpp)
> > if ((*vpp)->v_type != VDIR) {
> > if (!((cnp->cn_flags & EMPTYPATH) != 0 &&
> > cnp->cn_pnbuf[0] == '\0')) {
> > cache_fpl_smr_exit(fpl);
> > + ndp->ni_resflags |= NIRES_EMPTYPATH;
> > return (cache_fpl_handled_error(fpl, ENOTDIR));
> > }
> > }
> >
>
> on another look it already works fine as is, I miseed the ! in the condition ;)
ugh, thanks, looks like it's time for me to sleep it off ))
>
> #include <sys/stat.h>
> #include <fcntl.h>
>
> int
> main(void)
> {
> struct stat sb;
> int fd;
>
> fd = open("/etc/fstab", O_RDONLY);
>
> fstatat(fd, "", &sb, AT_EMPTY_PATH);
> }
>
> openat(AT_FDCWD,"/etc/fstab",O_RDONLY,00) = 3 (0x3)
> fstatat(3,"",{ mode=-rw-r--r-- ,inode=370100,size=145,blksize=4096
> },AT_EMPTY_PATH) = 0 (0x0)
>
> dtrace -n 'vfs:fplookup:: /execname == "a.out"/ { @[stack(), arg1,
> arg2] = count(); }'
> [snip]
> kernel`kern_statat+0xec
> kernel`sys_fstatat+0x27
> kernel`amd64_syscall+0x109
> kernel`0xffffffff809726bb
> 4980 3 1
>
> as in handled in cache_fplookup_emptypath
>
> >
> > On 5/2/23, Dmitry Chagin <dchagin@freebsd.org> wrote:
> >> On Tue, May 02, 2023 at 03:04:37PM -0400, Mark Johnston wrote:
> >>> On Tue, May 02, 2023 at 08:00:01PM +0300, Dmitry Chagin wrote:
> >>> > On Tue, May 02, 2023 at 03:12:51PM +0000, Konstantin Belousov wrote:
> >>> > > The branch main has been updated by kib:
> >>> > >
> >>> > > URL:
> >>> > > https://cgit.FreeBSD.org/src/commit/?id=a1d71cebc05ccfeedf95f2db3e94b17270167888
> >>> > >
> >>> > > commit a1d71cebc05ccfeedf95f2db3e94b17270167888
> >>> > > Author: Konstantin Belousov <kib@FreeBSD.org>
> >>> > > AuthorDate: 2023-05-02 15:11:39 +0000
> >>> > > Commit: Konstantin Belousov <kib@FreeBSD.org>
> >>> > > CommitDate: 2023-05-02 15:11:39 +0000
> >>> > >
> >>> > > fstatat(2): restore AT_EMPTY_PATH handling
> >>> > >
> >>> > > Fixes: cb858340dcbf214cc4c4d78dbb741620d7b3a252
> >>> > > Reported by: markj
> >>> > > Sponsored by: The FreeBSD Foundation
> >>> > > ---
> >>> > > sys/kern/vfs_syscalls.c | 6 +++++-
> >>> > > 1 file changed, 5 insertions(+), 1 deletion(-)
> >>> > >
> >>> > > diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
> >>> > > index 5c0a291e3b0b..d68af4ea4d51 100644
> >>> > > --- a/sys/kern/vfs_syscalls.c
> >>> > > +++ b/sys/kern/vfs_syscalls.c
> >>> > > @@ -2438,8 +2438,12 @@ kern_statat(struct thread *td, int flag, int
> >>> > > fd, const char *path,
> >>> > > AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH) | LOCKSHARED | LOCKLEAF |
> >>> > > AUDITVNODE1, pathseg, path, fd, &cap_fstat_rights);
> >>> > >
> >>> > > - if ((error = namei(&nd)) != 0)
> >>> > > + if ((error = namei(&nd)) != 0) {
> >>> > > + if (error == ENOTDIR &&
> >>> > > + (nd.ni_resflags & NIRES_EMPTYPATH) != 0)
> >>> > > + error = kern_fstat(td, fd, sbp);
> >>> > > return (error);
> >>> > > + }
> >>> >
> >>> > cache_fplookup_dirfd() doesnt set the NIRES_EMPTYPATH flag
> >>>
> >>> It doesn't, but for an AT_EMPTY_PATH lookup it aborts the lookup and
> >>> returns ENOTDIR to namei(), which sets NIRES_EMPTYPATH before passing
> >>> the error up.
> >>>
> >>
> >> it call cache_fpl_handled_error() which is set status to
> >> CACHE_FPL_STATUS_HADLED, namei() simply return error in that path
> >>
> >>
> >>> > > error = VOP_STAT(nd.ni_vp, sbp, td->td_ucred, NOCRED);
> >>> > > NDFREE_PNBUF(&nd);
> >>> > > vput(nd.ni_vp);
> >>> >
> >>
> >
> >
> > --
> > Mateusz Guzik <mjguzik gmail.com>
> >
>
>
> --
> Mateusz Guzik <mjguzik gmail.com>
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