Date: Thu, 28 May 2026 07:57:36 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: bae3d28fb6a7 - stable/15 - vn_lock_pair(): handle the case of vp1->v_vnlock == vp2->v_vnlock Message-ID: <6a17f570.2116c.67d93632@gitrepo.freebsd.org>
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The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=bae3d28fb6a72a5be337bf92c2294bbfdccbb13c commit bae3d28fb6a72a5be337bf92c2294bbfdccbb13c Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-05-16 23:19:50 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-05-28 07:57:14 +0000 vn_lock_pair(): handle the case of vp1->v_vnlock == vp2->v_vnlock (cherry picked from commit ace4a3e177c0da5efd9ceee0d9f46068562e3f5e) --- sys/kern/vfs_vnops.c | 32 +++++++++++++++++++++++++------- sys/sys/vnode.h | 2 +- 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c index 393353d8c038..1746d344aa64 100644 --- a/sys/kern/vfs_vnops.c +++ b/sys/kern/vfs_vnops.c @@ -4358,9 +4358,16 @@ vn_lock_pair_pause(const char *wmesg) * Only one of LK_SHARED and LK_EXCLUSIVE must be specified. * LK_NODDLKTREAT can be optionally passed. * - * If vp1 == vp2, only one, most exclusive, lock is obtained on it. + * If vp1->v_vnlock == vp2->v_vnlock, only one, most exclusive, lock + * is obtained on the vnode(s). The function accounts for the + * possibility of vp1 or vp2' v_vnlock changing while the + * corresponding vnode is unlocked. + * + * Return values: + * 0 - locked, two unlocks are required + * EDEADLK - locked, vnodes share the same lock, only one unlock is due. */ -void +int vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, struct vnode *vp2, bool vp2_locked, int lkflags2) { @@ -4374,9 +4381,10 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, MPASS((lkflags2 & ~(LK_SHARED | LK_EXCLUSIVE | LK_NODDLKTREAT)) == 0); if (vp1 == NULL && vp2 == NULL) - return; + return (0); - if (vp1 == vp2) { +recheck_same: + if (vp1 != NULL && vp2 != NULL && vp1->v_vnlock == vp2->v_vnlock) { MPASS(vp1_locked == vp2_locked); /* Select the most exclusive mode for lock. */ @@ -4389,20 +4397,26 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, /* No need to relock if any lock is exclusive. */ if ((vp1->v_vnlock->lock_object.lo_flags & LK_NOSHARE) != 0) - return; + return (EDEADLK); locked1 = VOP_ISLOCKED(vp1); if (((lkflags1 & LK_SHARED) != 0 && locked1 != LK_EXCLUSIVE) || ((lkflags1 & LK_EXCLUSIVE) != 0 && locked1 == LK_EXCLUSIVE)) - return; + return (EDEADLK); VOP_UNLOCK(vp1); } ASSERT_VOP_UNLOCKED(vp1, "vp1"); vn_lock(vp1, lkflags1 | LK_RETRY); - return; + if (vp1->v_vnlock == vp2->v_vnlock) + return (EDEADLK); + VOP_UNLOCK(vp1); + if (vp2_locked) { + VOP_UNLOCK(vp2); + vp2_locked = false; + } } if (vp1 != NULL) { @@ -4473,6 +4487,9 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, vn_lock(vp1, lkflags1 | LK_RETRY); vp1_locked = true; } + if (vp1 != NULL && vp2 != NULL && + vp1->v_vnlock == vp2->v_vnlock) + goto recheck_same; } if (vp1 != NULL) { if (lkflags1 == LK_EXCLUSIVE) @@ -4486,6 +4503,7 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, else ASSERT_VOP_LOCKED(vp2, "vp2 ret"); } + return (0); } int diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h index e48c4db95341..bb1d3faf567e 100644 --- a/sys/sys/vnode.h +++ b/sys/sys/vnode.h @@ -794,7 +794,7 @@ bool vn_isdisk_error(struct vnode *vp, int *errp); bool vn_isdisk(struct vnode *vp); int _vn_lock(struct vnode *vp, int flags, const char *file, int line); #define vn_lock(vp, flags) _vn_lock(vp, flags, __FILE__, __LINE__) -void vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, +int vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, struct vnode *vp2, bool vp2_locked, int lkflags2); int vn_open(struct nameidata *ndp, int *flagp, int cmode, struct file *fp); int vn_open_cred(struct nameidata *ndp, int *flagp, int cmode,home | help
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