Date: Fri, 7 Apr 2023 22:59:39 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: bb24eaea4982 - main - vn_lock_pair(): allow to request shared locking Message-ID: <202304072259.337MxdLI060187@gitrepo.freebsd.org>
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The branch main has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=bb24eaea498268572aa140c35c02e02884cdf930 commit bb24eaea498268572aa140c35c02e02884cdf930 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2023-04-06 04:11:08 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2023-04-07 22:58:26 +0000 vn_lock_pair(): allow to request shared locking If either of vnodes is shared locked, lock must not be recursed. Requested by: rmacklem Reviewed by: markj, rmacklem Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D39444 --- sys/fs/unionfs/union_subr.c | 3 +- sys/kern/vfs_mount.c | 2 +- sys/kern/vfs_vnops.c | 86 +++++++++++++++++++++++++++++++-------------- sys/sys/vnode.h | 4 +-- sys/ufs/ffs/ffs_softdep.c | 10 +++--- sys/ufs/ufs/ufs_vnops.c | 2 +- 6 files changed, 71 insertions(+), 36 deletions(-) diff --git a/sys/fs/unionfs/union_subr.c b/sys/fs/unionfs/union_subr.c index 42437f1e3840..264d37634949 100644 --- a/sys/fs/unionfs/union_subr.c +++ b/sys/fs/unionfs/union_subr.c @@ -388,7 +388,8 @@ unionfs_nodeget(struct mount *mp, struct vnode *uppervp, KASSERT(dvp != NULL || (vp->v_vflag & VV_ROOT) != 0, ("%s: NULL dvp for non-root vp %p", __func__, vp)); - vn_lock_pair(lowervp, false, uppervp, false); + vn_lock_pair(lowervp, false, LK_EXCLUSIVE, uppervp, false, + LK_EXCLUSIVE); error = insmntque1(vp, mp); if (error != 0) { unionfs_nodeget_cleanup(vp, unp); diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index 6233d4c3741a..bf532df335bf 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -1273,7 +1273,7 @@ vfs_domount_first( * Use vn_lock_pair to avoid establishing an ordering between vnodes * from different filesystems. */ - vn_lock_pair(vp, false, newdp, false); + vn_lock_pair(vp, false, LK_EXCLUSIVE, newdp, false, LK_EXCLUSIVE); VI_LOCK(vp); vp->v_iflag &= ~VI_MOUNT; diff --git a/sys/kern/vfs_vnops.c b/sys/kern/vfs_vnops.c index 1d90f76f9cd6..05cc0cfda16e 100644 --- a/sys/kern/vfs_vnops.c +++ b/sys/kern/vfs_vnops.c @@ -3753,50 +3753,74 @@ vn_lock_pair_pause(const char *wmesg) /* * Lock pair of vnodes vp1, vp2, avoiding lock order reversal. - * vp1_locked indicates whether vp1 is exclusively locked; if not, vp1 - * must be unlocked. Same for vp2 and vp2_locked. One of the vnodes - * can be NULL. + * vp1_locked indicates whether vp1 is locked; if not, vp1 must be + * unlocked. Same for vp2 and vp2_locked. One of the vnodes can be + * NULL. * - * The function returns with both vnodes exclusively locked, and - * guarantees that it does not create lock order reversal with other - * threads during its execution. Both vnodes could be unlocked - * temporary (and reclaimed). + * The function returns with both vnodes exclusively or shared locked, + * according to corresponding lkflags, and guarantees that it does not + * create lock order reversal with other threads during its execution. + * Both vnodes could be unlocked temporary (and reclaimed). + * + * If requesting shared locking, locked vnode lock must not be recursed. */ void -vn_lock_pair(struct vnode *vp1, bool vp1_locked, struct vnode *vp2, - bool vp2_locked) +vn_lock_pair(struct vnode *vp1, bool vp1_locked, int lkflags1, + struct vnode *vp2, bool vp2_locked, int lkflags2) { int error; + MPASS(lkflags1 == LK_SHARED || lkflags1 == LK_EXCLUSIVE); + MPASS(lkflags2 == LK_SHARED || lkflags2 == LK_EXCLUSIVE); + if (vp1 == NULL && vp2 == NULL) return; + if (vp1 != NULL) { - if (vp1_locked) - ASSERT_VOP_ELOCKED(vp1, "vp1"); - else + if (lkflags1 == LK_SHARED && + (vp1->v_vnlock->lock_object.lo_flags & LK_NOSHARE) != 0) + lkflags1 = LK_EXCLUSIVE; + if (vp1_locked && VOP_ISLOCKED(vp1) != LK_EXCLUSIVE) { + ASSERT_VOP_LOCKED(vp1, "vp1"); + if (lkflags1 == LK_EXCLUSIVE) { + VOP_UNLOCK(vp1); + ASSERT_VOP_UNLOCKED(vp1, + "vp1 shared recursed"); + vp1_locked = false; + } + } else if (!vp1_locked) ASSERT_VOP_UNLOCKED(vp1, "vp1"); } else { vp1_locked = true; } + if (vp2 != NULL) { - if (vp2_locked) - ASSERT_VOP_ELOCKED(vp2, "vp2"); - else + if (lkflags2 == LK_SHARED && + (vp2->v_vnlock->lock_object.lo_flags & LK_NOSHARE) != 0) + lkflags2 = LK_EXCLUSIVE; + if (vp2_locked && VOP_ISLOCKED(vp2) != LK_EXCLUSIVE) { + ASSERT_VOP_LOCKED(vp2, "vp2"); + if (lkflags2 == LK_EXCLUSIVE) { + VOP_UNLOCK(vp2); + ASSERT_VOP_UNLOCKED(vp2, + "vp2 shared recursed"); + vp2_locked = false; + } + } else if (!vp2_locked) ASSERT_VOP_UNLOCKED(vp2, "vp2"); } else { vp2_locked = true; } + if (!vp1_locked && !vp2_locked) { - vn_lock(vp1, LK_EXCLUSIVE | LK_RETRY); + vn_lock(vp1, lkflags1 | LK_RETRY); vp1_locked = true; } - for (;;) { - if (vp1_locked && vp2_locked) - break; + while (!vp1_locked || !vp2_locked) { if (vp1_locked && vp2 != NULL) { if (vp1 != NULL) { - error = VOP_LOCK1(vp2, LK_EXCLUSIVE | LK_NOWAIT, + error = VOP_LOCK1(vp2, lkflags2 | LK_NOWAIT, __FILE__, __LINE__); if (error == 0) break; @@ -3804,12 +3828,12 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, struct vnode *vp2, vp1_locked = false; vn_lock_pair_pause("vlp1"); } - vn_lock(vp2, LK_EXCLUSIVE | LK_RETRY); + vn_lock(vp2, lkflags2 | LK_RETRY); vp2_locked = true; } if (vp2_locked && vp1 != NULL) { if (vp2 != NULL) { - error = VOP_LOCK1(vp1, LK_EXCLUSIVE | LK_NOWAIT, + error = VOP_LOCK1(vp1, lkflags1 | LK_NOWAIT, __FILE__, __LINE__); if (error == 0) break; @@ -3817,14 +3841,22 @@ vn_lock_pair(struct vnode *vp1, bool vp1_locked, struct vnode *vp2, vp2_locked = false; vn_lock_pair_pause("vlp2"); } - vn_lock(vp1, LK_EXCLUSIVE | LK_RETRY); + vn_lock(vp1, lkflags1 | LK_RETRY); vp1_locked = true; } } - if (vp1 != NULL) - ASSERT_VOP_ELOCKED(vp1, "vp1 ret"); - if (vp2 != NULL) - ASSERT_VOP_ELOCKED(vp2, "vp2 ret"); + if (vp1 != NULL) { + if (lkflags1 == LK_EXCLUSIVE) + ASSERT_VOP_ELOCKED(vp1, "vp1 ret"); + else + ASSERT_VOP_LOCKED(vp1, "vp1 ret"); + } + if (vp2 != NULL) { + if (lkflags2 == LK_EXCLUSIVE) + ASSERT_VOP_ELOCKED(vp2, "vp2 ret"); + else + ASSERT_VOP_LOCKED(vp2, "vp2 ret"); + } } int diff --git a/sys/sys/vnode.h b/sys/sys/vnode.h index 74514654713a..5e3f81de0236 100644 --- a/sys/sys/vnode.h +++ b/sys/sys/vnode.h @@ -757,8 +757,8 @@ 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, struct vnode *vp2, - bool vp2_locked); +void 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, u_int vn_open_flags, struct ucred *cred, struct file *fp); diff --git a/sys/ufs/ffs/ffs_softdep.c b/sys/ufs/ffs/ffs_softdep.c index 1e245d82f8b8..9f3644477038 100644 --- a/sys/ufs/ffs/ffs_softdep.c +++ b/sys/ufs/ffs/ffs_softdep.c @@ -3323,7 +3323,7 @@ softdep_prelink(struct vnode *dvp, if (vp != NULL) { VOP_UNLOCK(dvp); ffs_syncvnode(vp, MNT_NOWAIT, 0); - vn_lock_pair(dvp, false, vp, true); + vn_lock_pair(dvp, false, LK_EXCLUSIVE, vp, true, LK_EXCLUSIVE); if (dvp->v_data == NULL) goto out; } @@ -3335,7 +3335,8 @@ softdep_prelink(struct vnode *dvp, VOP_UNLOCK(dvp); vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); if (vp->v_data == NULL) { - vn_lock_pair(dvp, false, vp, true); + vn_lock_pair(dvp, false, LK_EXCLUSIVE, vp, true, + LK_EXCLUSIVE); goto out; } ACQUIRE_LOCK(ump); @@ -3345,7 +3346,8 @@ softdep_prelink(struct vnode *dvp, VOP_UNLOCK(vp); vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); if (dvp->v_data == NULL) { - vn_lock_pair(dvp, true, vp, false); + vn_lock_pair(dvp, true, LK_EXCLUSIVE, vp, false, + LK_EXCLUSIVE); goto out; } } @@ -3360,7 +3362,7 @@ softdep_prelink(struct vnode *dvp, journal_check_space(ump); FREE_LOCK(ump); - vn_lock_pair(dvp, false, vp, false); + vn_lock_pair(dvp, false, LK_EXCLUSIVE, vp, false, LK_EXCLUSIVE); out: ndp->ni_dvp_seqc = vn_seqc_read_any(dvp); if (vp != NULL) diff --git a/sys/ufs/ufs/ufs_vnops.c b/sys/ufs/ufs/ufs_vnops.c index 0a34eee310b4..1982e183ca04 100644 --- a/sys/ufs/ufs/ufs_vnops.c +++ b/sys/ufs/ufs/ufs_vnops.c @@ -235,7 +235,7 @@ ufs_sync_nlink(struct vnode *vp, struct vnode *vp1) if (vp1 != NULL) VOP_UNLOCK(vp1); error = ufs_sync_nlink1(mp); - vn_lock_pair(vp, false, vp1, false); + vn_lock_pair(vp, false, LK_EXCLUSIVE, vp1, false, LK_EXCLUSIVE); return (error); }
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