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share/man/man9/VOP_INACTIVE.9
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| .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||||
| .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||||
| .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||||
| .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | ||||
| .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||||
| .\" | .\" | ||||
| .\" $FreeBSD$ | .\" $FreeBSD$ | ||||
| .\" | .\" | ||||
| .Dd July 27, 2014 | .Dd March 15, 2019 | ||||
| .Dt VOP_INACTIVE 9 | .Dt VOP_INACTIVE 9 | ||||
| .Os | .Os | ||||
| .Sh NAME | .Sh NAME | ||||
| .Nm VOP_INACTIVE , | .Nm VOP_INACTIVE , | ||||
| .Nm VOP_RECLAIM | .Nm VOP_RECLAIM | ||||
| .Nd reclaim file system resources for a vnode | .Nd reclaim file system resources for a vnode | ||||
| .Sh SYNOPSIS | .Sh SYNOPSIS | ||||
| .In sys/param.h | .In sys/param.h | ||||
| .In sys/vnode.h | .In sys/vnode.h | ||||
| .Ft int | .Ft int | ||||
| .Fn VOP_INACTIVE "struct vnode *vp" "struct thread *td" | .Fn VOP_INACTIVE "struct vnode *vp" "struct thread *td" | ||||
| .Ft int | .Ft int | ||||
| .Fn VOP_RECLAIM "struct vnode *vp" "struct thread *td" | .Fn VOP_RECLAIM "struct vnode *vp" "struct thread *td" | ||||
| .Sh DESCRIPTION | .Sh DESCRIPTION | ||||
| The arguments are: | The arguments are: | ||||
| .Bl -tag -width 2n | .Bl -tag -width 2n | ||||
| .It Fa vp | .It Fa vp | ||||
| The vnode being reclaimed. | The vnode being reclaimed. | ||||
| .El | .El | ||||
| .Pp | .Pp | ||||
| .Fn VOP_INACTIVE | .Fn VOP_INACTIVE | ||||
| is called when the kernel is no longer using the vnode. | is usually called when the kernel is no longer using the vnode. | ||||
cem: This seems a little less clear than before; it could be interpreted as "may be called sometimes… | |||||
| This may be | This may be | ||||
| because the reference count reaches zero or it may be that the | because the reference count reaches zero or it may be that the | ||||
| file system is being forcibly unmounted while there are open files. | file system is being forcibly unmounted while there are open files. | ||||
| It can be used to reclaim space for | It can be used to reclaim space on the last close of an | ||||
| .Sq open but deleted | .Sq open but deleted | ||||
| files. | file. | ||||
| However, there is no guarantee that it will be called at all, for example if | |||||
| the last reference was dropped while the vnode could not be locked exclusively. | |||||
Not Done Inline ActionsI do not know what unclean unmounts are. It is not guaranteed to be called because e.g. it might be called while only owning a shared vnode lock, and non-sleeping upgrade failed due to other shared lockers. kib: I do not know what unclean unmounts are. It is not guaranteed to be called because e.g. it… | |||||
Not Done Inline Actions@kib, which path would a VOP_INACTIVE() caller only hold a shared lock? cem: @kib, which path would a VOP_INACTIVE() caller only hold a shared lock? | |||||
Not Done Inline ActionsOh, vput/vunref may have a failed lock upgrade. But they still set VI_OWEINACT, so eventually the last other holder should invoke VOP_INACTIVE (or vgonel will). cem: Oh, vput/vunref may have a failed lock upgrade. But they still set VI_OWEINACT, so eventually… | |||||
Not Done Inline ActionsThe vnode could be vref-ed while VI_OWEINACT is set, and then if the lock mode is shared, it is still not inactivated. So no, there is no guarantee that vop_inactive necessary called before reclaim. kib: The vnode could be vref-ed while VI_OWEINACT is set, and then if the lock mode is shared, it is… | |||||
Not Done Inline Actions
I don't follow. If it is vrefed, it gains a non-zero usecount and is marked VI_ACTIVE. In vgonel(), it will still be vinactive -> VOP_INACTIVE()ed before RECLAIM. cem: > The vnode could be vref-ed while VI_OWEINACT is set, and then if the lock mode is shared, it… | |||||
Not Done Inline ActionsVOP_INACTIVE() gerald is to be called on each v_usecount 1->0 transition. This is not guaranteed at least due to the shared locking. The fact that we might be calling VOP_INACTIVE on next round of 1->0 transition or right before VOP_RECLAIM() call in vgonel() still does not satisfy the promise of calling VOP_INACTIVE on previous v_usecount zeroing. kib: VOP_INACTIVE() gerald is to be called on each v_usecount 1->0 transition. This is not… | |||||
Done Inline ActionsHm, can you clarify this sentence? It's called as part of vgonel() even during forced umount. So what is an unclean unmount in this context? cem: Hm, can you clarify this sentence? It's called as part of vgonel() even during forced umount. | |||||
Done Inline ActionsI meant things like power loss, crash, etc. The filesystem musn't rely exclusively on VOP_INACTIVE to reclaim space in such cases. asomers: I meant things like power loss, crash, etc. The filesystem musn't rely exclusively on… | |||||
Not Done Inline ActionsWe generally only document API guarantees with the understanding that they only apply if power is consistent and the system does not crash. If we added boilerplate about power loss/crash to every API it would bloat the manuals excessively and make it more difficult to read relevant information. I don't think there's any particular reason these APIs are different in that respect. cem: We generally only document API guarantees with the understanding that they only apply if power… | |||||
kibUnsubmitted Not Done Inline Actions'while the vnode lock could not be upgraded to exclusive without sleeping'. kib: 'while the vnode lock could not be upgraded to exclusive without sleeping'. | |||||
| .Pp | .Pp | ||||
| .Fn VOP_RECLAIM | .Fn VOP_RECLAIM | ||||
| is called when a vnode is being reused for a different file system. | is called when a vnode is being reused for a different file system. | ||||
| Any file system specific resources associated with the vnode should be | Any file system specific resources associated with the vnode should be | ||||
| freed. | freed. | ||||
| .Sh LOCKS | .Sh LOCKS | ||||
| For both | For both | ||||
| .Fn VOP_INACTIVE | .Fn VOP_INACTIVE | ||||
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This seems a little less clear than before; it could be interpreted as "may be called sometimes when the kernel is still using the vnode."
I might leave this sentence alone, but bring up your "no guarantee" sentence to follow directly after it.