On 16/06/2022 03:47, Damien Le Moal wrote:
so going backward several years... That internal tag for ATA does not
need to be reserved since this command is always used when the drive is
idle and no other NCQ commands are on-going.
So do you mean that ATA_TAG_INTERNAL qc is used for other commands
apart from internal commands?
No. It is used only for internal commands. What I meant to say is that
currently, internal commands are issued only on device scan, device
revalidate and error handling. All of these phases are done with the
device under EH with the issuing path stopped and all commands
completed,
If I want to allocate a request for an ATA internal command then could I
use 1x from the regular tags? I didn't think that this was possible as I
thought that all tags may be outstanding when EH kicks in. I need to
double check it.
Even if it were true, not using a reserved tag for ATA internal command
makes things more tricky as this command requires special handling for
scsi blk_mq_ops and there is no easy way to identify the command as
reserved (to know special handling is required).
so no regular commands can be issued. Only internal ones, non
NCQ, using the ATA_TAG_INTERNAL. So strictly speaking, we should not
need to reserve that internal tag at all.
Thanks,
John
