CVS commit: src/sys/dev/dkwedge

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Fri Apr 21 18:30:52 UTC 2023

Modified Files:
        src/sys/dev/dkwedge: dk.c

Log Message:
dk(4): Use disk_begindetach and rely on vdevgone to close instances.

The first step is to decide whether we can detach (if forced, yes; if
not forced, only if not already open), and prevent new opens if so.
There's no need to start closing open instances at this point --
we're just making a decision to detach, and preventing new opens by
transitioning state that dkopen will respect[*].

The second step is to force all open instances to close.  This is
done by vdevgone.  By the time vdevgone returns, there can be no open
instances, so if there _were_ any, closing them via vdevgone will
have passed through dklastclose.

After that point, there can be no opens and no I/O operations, so
dk_openmask must already be zero and the bufq must be empty.

Thus, there's no need to have an explicit call to dklastclose (via
dkwedge_cleanup_parent) before or after making the decision to
detach.

[*] Currently access to this state is racy: nothing serializes
    dkwedge_detach's state transition with dkopen's test.  TBD in a
    separate commit shortly.


To generate a diff of this commit:
cvs rdiff -u -r1.142 -r1.143 src/sys/dev/dkwedge/dk.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.