Change in vdsm[master]: block: add blkdiscard on zero image

Yaniv Kaul has posted comments on this change.

Change subject: block: add blkdiscard on zero image
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Patch Set 1:

(1 comment)

https://gerrit.ovirt.org/#/c/35631/1/vdsm/storage/blockSD.py
File vdsm/storage/blockSD.py:

Line 219:         size = multipath.getDeviceSize(lvm.lvDmDev(sdUUID, volUUID))
Line 220: 
Line 221:         try:
Line 222:             misc.ddWatchCopy("/dev/zero", path, aborting, size)
Line 223:             utillinux.blkdiscard(path)
>  We want to remove the data before we discard. Does discard ensure
> that the  
It certainly does.
It's not secure, in the sense that if there's a bug in the storage the date may
re-appear, but other than that - absolutely. For the bug in the storage we may wish to
introduce secure deletion, but this is a different item.
If we do unmap, we can and should rely on the data being deleted.

Also see https://rwmj.wordpress.com/tag/unmap/
Line 224:         except Exception as e:
Line 225:             log.exception('zeroing operation failed')
Line 226:             raise se.VolumesZeroingError(path)
Line 227: 


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Gerrit-MessageType: comment
Gerrit-Change-Id: I4e059c556c550440727b36b8af8e5dfc29ce2ccb
Gerrit-PatchSet: 1
Gerrit-Project: vdsm
Gerrit-Branch: master
Gerrit-Owner: Federico Simoncelli <fsimonce(a)redhat.com&gt;
Gerrit-Reviewer: Allon Mureinik <amureini(a)redhat.com&gt;
Gerrit-Reviewer: Jenkins CI
Gerrit-Reviewer: Nir Soffer <nsoffer(a)redhat.com&gt;
Gerrit-Reviewer: Tal Nisan <tnisan(a)redhat.com&gt;
Gerrit-Reviewer: Yaniv Kaul <ykaul(a)redhat.com&gt;
Gerrit-Reviewer: gerrit-hooks <automation(a)ovirt.org&gt;
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