Add notifications when a scrub is paused or resumed.

[kithrup]

Notification when scrub is aborted taken from FreeBSD, the other two were modeled on that.

The change has been tested on FreeNAS.

[ahrens]

looks like there's a typo here (two "")

[kithrup]

Blast it. I thought I'd made that by patching. Hold on a bit while I fix it. grumble.

[ahrens]

You'll need to fix the compilation errors, which you can see by clicking "Details" next to the failed check:

../../common/fs/zfs/dsl_scan.c:366: error: passing argument 3 of 'spa_event_notify' from incompatible pointer type

../../common/fs/zfs/dsl_scan.c:366: error: too few arguments to function 'spa_event_notify'

../../common/fs/zfs/dsl_scan.c:421: error: passing argument 3 of 'spa_event_notify' from incompatible pointer type

../../common/fs/zfs/dsl_scan.c:421: error: too few arguments to function 'spa_event_notify'

../../common/fs/zfs/dsl_scan.c:1992: error: passing argument 3 of 'spa_event_notify' from incompatible pointer type

../../common/fs/zfs/dsl_scan.c:1992: error: too few arguments to function 'spa_event_notify'

[kithrup]

I've pushed it to my branch; does the PR automatically pick it up?

[ahrens]

@kithrup Yep. The new batch of automated build/tests are running now.

[kithrup]

I saw that just after I commented. yay automation testing!

[prakashsurya]

@ahrens looks like the compilation errors have been fixed; could you give this another look when you have time?