cvs commit: src/sbin/atacontrol atacontrol.c

[Bruce M. Simpson]

Poul-Henning Kamp wrote:
> I have the attached patch in sos@ mailbox for approval, that adds
> BIO_DELETE support for the ata driver.
>
> I also want to implement a -E option to fsck(8) to erase all
> unallocated blocks.
>
> And finally the big item: msdosfs and ufs support to issue BIO_DELETE
> when files are deleted.  UFS is nasty because of soft-updates.
>   

Aha, I understand now. CFA and SATA vendors have gone off in two 
separate directions:
 * PATA and SATA drives, for a few years now, have tended to rewrite one 
cylinder at a time, which implies erasing the data on that cylinder.
 * NAND Flash devices should not have their sectors erased unless 
absolutely necessary, to implement wear levelling.

So it's necessary to tell the block layer, explicitly, beneath UFS, 
about the intention to delete the data contained within such blocks.

Thanks for doing this.
BMS