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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE. .\" SUCH DAMAGE.
.\" .\"
.\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93 .\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93
.\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29 .\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29
.\" .\"
.\" $FreeBSD$ .\" $FreeBSD$
.\" .\"
.Dd November 6, 2020 .Dd August 27, 2021
.Dt MDCONFIG 8 .Dt MDCONFIG 8
.Os .Os
.Sh NAME .Sh NAME
.Nm mdconfig .Nm mdconfig
.Nd create and control memory disks .Nd create and control memory disks
.Sh SYNOPSIS .Sh SYNOPSIS
.Nm .Nm
.Fl a .Fl a
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This can be used with the This can be used with the
.Fl d .Fl d
flag to forcibly destroy an flag to forcibly destroy an
.Xr md 4 .Xr md 4
disk that is still in use. disk that is still in use.
.It Oo Cm no Oc Ns Cm readonly .It Oo Cm no Oc Ns Cm readonly
Enable/disable readonly mode. Enable/disable readonly mode.
.It Oo Cm no Oc Ns Cm verify .It Oo Cm no Oc Ns Cm verify
For For
markjUnsubmitted
Done
Inline Actions
.Cm vnode
- backed devices: Detect if hole-punching is supported by the underlying file
+ backed devices: detect whether hole-punching is supported by the underlying file
system.
markj:
.Cm vnode .Cm vnode
backed devices: enable/disable requesting verification of the backed devices: enable/disable requesting verification of the
markjUnsubmitted
Done
Inline Actions
system.
- If the file system supports hole-punching, for a
+ If the file system supports hole-punching, then to handle a
.Dv BIO_DELETE
markj:
file used for backing store. file used for backing store.
The type of verification depends on which security features are available. The type of verification depends on which security features are available.
markjUnsubmitted
Done
Inline Actions
.Dv BIO_DELETE
- request, a part of the request's operation range may be turned into a hole in
+ request, some or all of the request's operation range may be turned into a hole in
the file used for backing store.
markj:
One example of verification is testing file integrity with One example of verification is testing file integrity with
checksums or cryptographic signatures. checksums or cryptographic signatures.
.It Oo Cm no Oc Ns Cm autounmap
Detect if hole-punching is supported by the underlying file system.
markjUnsubmitted
Not Done
Inline Actions

I think it could be a bit more clear:

  • Start the description with "For .Cm vnode backed devices:" like other vnode-specific option descriptions.
  • What happens if the file system does support hole-punching?
  • What happens when autounmap is not specified and BIO_DELETE is received?
  • Probably reference fspacectl.2 or just briefly describe the meaning of "hole-punching".

"autounmap" also seems like a somewhat strange name to me. Is it named after something similar elsewhere?

markj: I think it could be a bit more clear: - Start the description with "For .Cm vnode backed…
khngAuthorUnsubmitted
Not Done
Inline Actions

Do you think "mayunmap" is a better name?

khng: Do you think "mayunmap" is a better name?
markjUnsubmitted
Not Done
Inline Actions

Is "unmap" the usual terminology? fspacectl.2 refers to space deallocation, and we have _PC_DEALLOC_PRESENT, so maybe "mustdealloc"?

markj: Is "unmap" the usual terminology? fspacectl.2 refers to space deallocation, and we have…
markjUnsubmitted
Done
Inline Actions
the file.
- If the file system of the vnode type memory disk does not support
+ If the file system does not support
hole-punching,
markj:
If the underlying file system of the vnode type memory disk does not support
hole-punching, BIO_DELETE requests are returned unsupported.
markjUnsubmitted
Done
Inline Actions
If the underlying file system of the vnode type memory disk does not support
- hole-punching, BIO_DELETE requests are returned unsupported.
+ hole-punching,
+ .Dv BIO_DELETE
+ requests are returned unsupported.
.El
.It Fl u Ar unit
markj:
.El .El
markjUnsubmitted
Done
Inline Actions
.Dv BIO_DELETE
- requests are returned unsupported.
+ requests to the device are not handled and will fail with
+ .Er EOPNOTSUPP .
.Pp
In case
markj:
.It Fl u Ar unit .It Fl u Ar unit
Request a specific unit number or device name for the Request a specific unit number or device name for the
markjUnsubmitted
Done
Inline Actions
requests are returned unsupported.
.Pp
- In case
+ When
.Cm mustdealloc
markj:
.Xr md 4 .Xr md 4
device instead of automatic allocation. device instead of automatic allocation.
If a device name is specified, it must start with If a device name is specified, it must start with
.Dq md .Dq md
followed by the unit number. followed by the unit number.
.El .El
markjUnsubmitted
Done
Inline Actions
.Dv BIO_DELETE
- request, if the file system supports hole-punching, a part of the request's
+ request, if the file system supports hole-punching, some or all of the request's
operation range may be turned into a hole in the file used for backing store.
markj:
.Pp .Pp
The last form, The last form,
.Nm .Nm
.Ar file , .Ar file ,
is provided for convenience as an abbreviation of is provided for convenience as an abbreviation of
.Nm .Nm
.Fl a .Fl a
.Fl t Cm vnode .Fl t Cm vnode
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