On Tue, 4 Mar 2008, Stefan Richter wrote:
> Alan Stern wrote:
> > So I need a
> > way to know whether anything is mounted on a device below a SCSI host.
>
> Actually I have been thinking of something related for a while but
> didn't send a patch yet. Consider this:
>
> [include/scsi/scsi_host.h]
>
> struct scsi_host_template {
> ...
> + int (* slave_sdev_get)(struct scsi_device *);
> + void (* slave_sdev_put)(struct scsi_device *);
> ...
> }
>
> [drivers/scsi/scsi.c]
>
> int scsi_device_get(struct scsi_device *sdev)
> {
> + int err = 0;
> +
> if (sdev->sdev_state == SDEV_DEL)
> return -ENXIO;
> if (!get_device(&sdev->sdev_gendev))
> return -ENXIO;
> /* We can fail this if we're doing SCSI operations
> * from module exit (like cache flush) */
> try_module_get(sdev->host->hostt->module);
>
> - return 0;
> + if (sdev->host->hostt->slave_sdev_get)
> + err = sdev->host->hostt->slave_sdev_get(sdev);
> + if (err) {
> + ...some ifdef'd module_put stuff...;
> + put_device(&sdev->sdev_gendev);
> + }
> + return err;
> }
>
> and equivalent additions to scsi_device_put().
On second thought, I'm not so sure this would work the way I want.
scsi_device_get() ends up being called for all sorts of extra things
unrelated to device opens. For instance, scsi_probe_and_add_lun()
calls it whenever a new LUN is discovered.
Would it be acceptable to add a similar pair of callbacks to the host
template, invoked by the upper-level driver's open and release
routines?
Alan Stern
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
