Re: [PATCH v3 1/1] tools/hotplug: Scan xenstore once when attaching shared images files

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-10-05 at 17:41 +0100, Ian Jackson wrote:
> Mike Latimer writes ("[PATCH v3 1/1] tools/hotplug: Scan xenstore once
> when attaching shared images files"):
> > During the attachment of a loopback mounted image file, the mode of all
> > curent instances of this device already attached to other domains must
> > be
> > checked. This requires finding all loopback devices pointing to the
> > inode
> > of the shared image file, and then comparing the major and minor number
> > of
> > these devices to the major and minor number of every vbd device found
> > in the
> > xenstore database.
> > 
> > Prior to this patch, the entire xenstore database is walked for every
> > instance
> > of every loopback device pointing to the same shared image file. This
> > process
> > causes the block attachment process to becomes exponentially slower
> > with every
> > additional attachment of a shared image.
> > 
> > Rather than scanning all of xenstore for every instance of a shared
> > loopback
> > device, this patch creates a list of the major and minor numbers from
> > all
> > matching loopback devices. After generating this list, Xenstore is
> > walked
> > once, and major and minor numbers from every vbd are checked against
> > the list.
> > If a match is found, the mode of that vbd is checked for compatibility
> > with
> > the mode of the device being attached.
> 
> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Applied.

Mike, FWIW for singleton patches it is normally ok to dispense with the 0/1
mail and to just send the patch by itself. If there is commentary which
doesn't belong in the commit message you can put it below a "---" marker
(and "git am" will strip it). If there is lots commentary then sending a
0/1 is fine if you want, of course.

Ian.