zero deleted blocks

[Poul-Henning Kamp]

In message <20120813084120.GA2352 at deviant.kiev.zoral.com.ua>, Konstantin Belous
ov writes:

>I think TRIM support in UFS can be extended to zero-out the deleted
>blocks, with relatively small amount of work. Basically, in
>ufs/ffs/ffs_alloc.c:ffs_blkfree(), a BIO_WRITE of zero buffer shall be
>issued instead of BIO_DELETE.

It would be a better idea to give geom_disk a per-disk option to
convert BIO_DELETE to writes of zeros.

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