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authorKonstantin Belousov <kib@FreeBSD.org>2021-01-29 23:48:55 +0000
committerKonstantin Belousov <kib@FreeBSD.org>2021-02-17 23:22:05 +0000
commitfa3bd463cee5c3abeac29a83dc86eb3abfa97b06 (patch)
tree00effb7f68f6bd16e710dad29fb806ce2c2554e1 /sys
parent351d06eeb509a420f3470c96b4a265467c87e2c2 (diff)
downloadsrc-fa3bd463cee5c3abeac29a83dc86eb3abfa97b06.tar.gz
src-fa3bd463cee5c3abeac29a83dc86eb3abfa97b06.zip
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
Diffstat (limited to 'sys')
-rw-r--r--sys/kern/vfs_default.c15
-rw-r--r--sys/kern/vfs_vnops.c23
-rw-r--r--sys/sys/fcntl.h1
-rw-r--r--sys/sys/vnode.h2
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) {
+ 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;
+ }
+ 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 */
#define VV_ROOT 0x0001 /* root of its filesystem */
#define VV_ISTTY 0x0002 /* vnode represents a tty */