diff options
| author | Mateusz Guzik <mjg@FreeBSD.org> | 2021-02-15 22:08:40 +0000 |
|---|---|---|
| committer | Mateusz Guzik <mjg@FreeBSD.org> | 2021-04-10 05:57:55 +0000 |
| commit | fb16013129a10a10be46197a82b814e479ed0905 (patch) | |
| tree | 71b40aaeddf16ae0bb6b1031251c273a56513b97 | |
| parent | 4cb1b49b3c985e97933a6194646bab47ece82400 (diff) | |
| download | src-fb16013129a10a10be46197a82b814e479ed0905.tar.gz src-fb16013129a10a10be46197a82b814e479ed0905.zip | |
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)
| -rw-r--r-- | sys/kern/vfs_default.c | 25 | ||||
| -rw-r--r-- | sys/kern/vfs_mount.c | 38 | ||||
| -rw-r--r-- | 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 *, |