zfs rewrite ratelimit, and filter

[justinpryzby]

Is there any appetite for such a feature request ?

I'm thinking of zfs rewrite /zfs --bwlimit 50MB

One more idea -- what about filtering the rewritten blocks by vdev? Like zfs rewrite /zfs/foo --vdev=vdc, which means rewrite only blocks which are stored on vdc.

No idea if these make any sense with the implementation...

[amotin]

Rate limiting can be easily implemented just in user-space, if really needed. Should not be difficult.

Filtering of the blocks to rewrite I've planned from the beginning, and even reserved some space for future arguments. Though I am not sure what's the point to rewrite only specific vdev, at least unless you exclude it from new allocation?