From owner-dev-commits-src-branches@freebsd.org Sat Apr 10 06:02:08 2021 Return-Path: Delivered-To: dev-commits-src-branches@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 6A94C5CFB24; Sat, 10 Apr 2021 06:02:08 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FHPXc0TYsz4RHx; Sat, 10 Apr 2021 06:02:07 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 8BFBE422D; Sat, 10 Apr 2021 06:02:07 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 13A627Yr015226; Sat, 10 Apr 2021 06:02:07 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 13A627Uh015225; Sat, 10 Apr 2021 06:02:07 GMT (envelope-from git) Date: Sat, 10 Apr 2021 06:02:07 GMT Message-Id: <202104100602.13A627Uh015225@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mateusz Guzik Subject: git: fb16013129a1 - stable/13 - vfs: add vfs_ref_from_vp MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: mjg X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: fb16013129a10a10be46197a82b814e479ed0905 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-branches@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commits to the stable branches of the FreeBSD src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 10 Apr 2021 06:02:08 -0000 The branch stable/13 has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=fb16013129a10a10be46197a82b814e479ed0905 commit fb16013129a10a10be46197a82b814e479ed0905 Author: Mateusz Guzik AuthorDate: 2021-02-15 22:08:40 +0000 Commit: Mateusz Guzik CommitDate: 2021-04-10 05:57:55 +0000 vfs: add vfs_ref_from_vp This generalizes what vop_stdgetwritemount used to be doing. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D28695 (cherry picked from commit a15f787adb4429b83fa911dcb60f69121aaee1ba) --- sys/kern/vfs_default.c | 25 +------------------------ sys/kern/vfs_mount.c | 38 ++++++++++++++++++++++++++++++++++++++ sys/sys/mount.h | 1 + 3 files changed, 40 insertions(+), 24 deletions(-) diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c index 3c428d7b7511..4b9b1b43f1ce 100644 --- a/sys/kern/vfs_default.c +++ b/sys/kern/vfs_default.c @@ -680,7 +680,6 @@ vop_stdgetwritemount(ap) } */ *ap; { struct mount *mp; - struct mount_pcpu *mpcpu; struct vnode *vp; /* @@ -693,29 +692,7 @@ vop_stdgetwritemount(ap) * with releasing it. */ vp = ap->a_vp; - mp = vp->v_mount; - if (mp == NULL) { - *(ap->a_mpp) = NULL; - return (0); - } - if (vfs_op_thread_enter(mp, mpcpu)) { - if (mp == vp->v_mount) { - vfs_mp_count_add_pcpu(mpcpu, ref, 1); - vfs_op_thread_exit(mp, mpcpu); - } else { - vfs_op_thread_exit(mp, mpcpu); - mp = NULL; - } - } else { - MNT_ILOCK(mp); - if (mp == vp->v_mount) { - MNT_REF(mp); - MNT_IUNLOCK(mp); - } else { - MNT_IUNLOCK(mp); - mp = NULL; - } - } + mp = vfs_ref_from_vp(vp); *(ap->a_mpp) = mp; return (0); } diff --git a/sys/kern/vfs_mount.c b/sys/kern/vfs_mount.c index 59000728efcc..7dc6b795eefd 100644 --- a/sys/kern/vfs_mount.c +++ b/sys/kern/vfs_mount.c @@ -449,6 +449,44 @@ sys_nmount(struct thread *td, struct nmount_args *uap) * Various utility functions */ +/* + * Get a reference on a mount point from a vnode. + * + * The vnode is allowed to be passed unlocked and race against dooming. Note in + * such case there are no guarantees the referenced mount point will still be + * associated with it after the function returns. + */ +struct mount * +vfs_ref_from_vp(struct vnode *vp) +{ + struct mount *mp; + struct mount_pcpu *mpcpu; + + mp = atomic_load_ptr(&vp->v_mount); + if (__predict_false(mp == NULL)) { + return (mp); + } + if (vfs_op_thread_enter(mp, mpcpu)) { + if (__predict_true(mp == vp->v_mount)) { + vfs_mp_count_add_pcpu(mpcpu, ref, 1); + vfs_op_thread_exit(mp, mpcpu); + } else { + vfs_op_thread_exit(mp, mpcpu); + mp = NULL; + } + } else { + MNT_ILOCK(mp); + if (mp == vp->v_mount) { + MNT_REF(mp); + MNT_IUNLOCK(mp); + } else { + MNT_IUNLOCK(mp); + mp = NULL; + } + } + return (mp); +} + void vfs_ref(struct mount *mp) { diff --git a/sys/sys/mount.h b/sys/sys/mount.h index 98d50161bed5..e6a74bf1fb60 100644 --- a/sys/sys/mount.h +++ b/sys/sys/mount.h @@ -997,6 +997,7 @@ void vfs_mount_error(struct mount *, const char *, ...); void vfs_mountroot(void); /* mount our root filesystem */ void vfs_mountedfrom(struct mount *, const char *from); void vfs_notify_upper(struct vnode *, int); +struct mount *vfs_ref_from_vp(struct vnode *); void vfs_ref(struct mount *); void vfs_rel(struct mount *); struct mount *vfs_mount_alloc(struct vnode *, struct vfsconf *, const char *,