Date: Thu, 18 Feb 2021 02:16:56 +0100 From: Mateusz Guzik <mjguzik@gmail.com> To: Konstantin Belousov <kib@freebsd.org> Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org Subject: Re: git: fa3bd463cee5 - main - lockf: ensure atomicity of lockf for open(O_CREAT|O_EXCL|O_EXLOCK) Message-ID: <CAGudoHGZq-k4YCghzF3weBxx%2Bw95jSqGW_mjfF2_SkcYSQX6Bg@mail.gmail.com> In-Reply-To: <202102172323.11HNN1xo077930@gitrepo.freebsd.org> References: <202102172323.11HNN1xo077930@gitrepo.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On 2/18/21, Konstantin Belousov <kib@freebsd.org> wrote: > The branch main has been updated by kib: > > URL: > https://cgit.FreeBSD.org/src/commit/?id=fa3bd463cee5c3abeac29a83dc86eb3abfa97b06 > > commit fa3bd463cee5c3abeac29a83dc86eb3abfa97b06 > Author: Konstantin Belousov <kib@FreeBSD.org> > AuthorDate: 2021-01-29 23:48:55 +0000 > Commit: Konstantin Belousov <kib@FreeBSD.org> > CommitDate: 2021-02-17 23:22:05 +0000 > > lockf: ensure atomicity of lockf for open(O_CREAT|O_EXCL|O_EXLOCK) > > or EX_SHLOCK. Do it by setting a vnode iflag indicating that the > locking > exclusive open is in progress, and not allowing F_LOCK request to make > a progress until the first open finishes. > > Requested by: mckusick > Reviewed by: markj, mckusick > Tested by: pho > Sponsored by: The FreeBSD Foundation > MFC after: 1 week > Differential Revision: https://reviews.freebsd.org/D28697 > --- > sys/kern/vfs_default.c | 15 +++++++++++++++ > sys/kern/vfs_vnops.c | 23 ++++++++++++++++++++--- > sys/sys/fcntl.h | 1 + > sys/sys/vnode.h | 2 ++ > 4 files changed, 38 insertions(+), 3 deletions(-) > > diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c > index 382fbb2d9ace..3c428d7b7511 100644 > --- a/sys/kern/vfs_default.c > +++ b/sys/kern/vfs_default.c > @@ -423,10 +423,25 @@ int > vop_stdadvlock(struct vop_advlock_args *ap) > { > struct vnode *vp; > + struct mount *mp; > struct vattr vattr; > int error; > > vp = ap->a_vp; > + > + /* > + * Provide atomicity of open(O_CREAT | O_EXCL | O_EXLOCK) for > + * local filesystems. See vn_open_cred() for reciprocal part. > + */ > + mp = vp->v_mount; > + if (mp != NULL && (mp->mnt_flag & MNT_LOCAL) != 0 && > + ap->a_op == F_SETLK && (ap->a_flags & F_FIRSTOPEN) == 0) { This should check for FIRSTOPEN first, which will be least likely of the entire bunch. > + VI_LOCK(vp); > + while ((vp->v_iflag & VI_FOPENING) != 0) > + msleep(vp, VI_MTX(vp), PLOCK, "lockfo", 0); > + VI_UNLOCK(vp); > + } > + > if (ap->a_fl->l_whence == SEEK_END) { > /* > * The NFSv4 server must avoid doing a vn_lock() here, since it > diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c > index 71dd379558cb..781968f2db53 100644 > --- a/sys/kern/vfs_vnops.c > +++ b/sys/kern/vfs_vnops.c > @@ -228,8 +228,10 @@ vn_open_cred(struct nameidata *ndp, int *flagp, int > cmode, u_int vn_open_flags, > struct vattr vat; > struct vattr *vap = &vat; > int fmode, error; > + bool first_open; > > restart: > + first_open = false; > fmode = *flagp; > if ((fmode & (O_CREAT | O_EXCL | O_DIRECTORY)) == (O_CREAT | > O_EXCL | O_DIRECTORY)) > @@ -275,8 +277,16 @@ restart: > #endif > error = VOP_CREATE(ndp->ni_dvp, &ndp->ni_vp, > &ndp->ni_cnd, vap); > - VOP_VPUT_PAIR(ndp->ni_dvp, error == 0 ? &ndp->ni_vp : > - NULL, false); > + vp = ndp->ni_vp; > + if (error == 0 && (fmode & O_EXCL) != 0 && > + (fmode & (O_EXLOCK | O_SHLOCK)) != 0) { > + VI_LOCK(vp); > + vp->v_iflag |= VI_FOPENING; > + VI_UNLOCK(vp); > + first_open = true; > + } error tends to be 0, so this can inspect fmode first > + VOP_VPUT_PAIR(ndp->ni_dvp, error == 0 ? &vp : NULL, > + false); > vn_finished_write(mp); > if (error) { > NDFREE(ndp, NDF_ONLY_PNBUF); > @@ -287,7 +297,6 @@ restart: > return (error); > } > fmode &= ~O_TRUNC; > - vp = ndp->ni_vp; > } else { > if (ndp->ni_dvp == ndp->ni_vp) > vrele(ndp->ni_dvp); > @@ -317,6 +326,12 @@ restart: > vp = ndp->ni_vp; > } > error = vn_open_vnode(vp, fmode, cred, td, fp); > + if (first_open) { > + VI_LOCK(vp); > + vp->v_iflag &= ~VI_FOPENING; > + wakeup(vp); > + VI_UNLOCK(vp); > + } > if (error) > goto bad; > *flagp = fmode; > @@ -352,6 +367,8 @@ vn_open_vnode_advlock(struct vnode *vp, int fmode, > struct file *fp) > type = F_FLOCK; > if ((fmode & FNONBLOCK) == 0) > type |= F_WAIT; > + if ((fmode & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) > + type |= F_FIRSTOPEN; > error = VOP_ADVLOCK(vp, (caddr_t)fp, F_SETLK, &lf, type); > if (error == 0) > fp->f_flag |= FHASLOCK; > diff --git a/sys/sys/fcntl.h b/sys/sys/fcntl.h > index 3c29c04e46db..70e68246be13 100644 > --- a/sys/sys/fcntl.h > +++ b/sys/sys/fcntl.h > @@ -287,6 +287,7 @@ typedef __pid_t pid_t; > #define F_POSIX 0x040 /* Use POSIX semantics for lock */ > #define F_REMOTE 0x080 /* Lock owner is remote NFS client */ > #define F_NOINTR 0x100 /* Ignore signals when waiting */ > +#define F_FIRSTOPEN 0x200 /* First right to advlock file */ > #endif > > /* > diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h > index 639a16881e09..9d68f9e236f6 100644 > --- a/sys/sys/vnode.h > +++ b/sys/sys/vnode.h > @@ -254,6 +254,8 @@ struct xvnode { > #define VI_DOINGINACT 0x0004 /* VOP_INACTIVE is in progress */ > #define VI_OWEINACT 0x0008 /* Need to call inactive */ > #define VI_DEFINACT 0x0010 /* deferred inactive */ > +#define VI_FOPENING 0x0020 /* In open, with opening process having the > + first right to advlock file */ The flag was not added to vn_printf > > #define VV_ROOT 0x0001 /* root of its filesystem */ > #define VV_ISTTY 0x0002 /* vnode represents a tty */ > _______________________________________________ > dev-commits-src-all@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all > To unsubscribe, send any mail to > "dev-commits-src-all-unsubscribe@freebsd.org" > -- Mateusz Guzik <mjguzik gmail.com>
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAGudoHGZq-k4YCghzF3weBxx%2Bw95jSqGW_mjfF2_SkcYSQX6Bg>