> -----Original Message----- > From: Anthony PERARD [mailto:anthony.per...@citrix.com] > Sent: 21 March 2019 11:42 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: xen-devel@lists.xenproject.org; qemu-bl...@nongnu.org; > qemu-de...@nongnu.org; Stefano Stabellini > <sstabell...@kernel.org>; Kevin Wolf <kw...@redhat.com>; Max Reitz > <mre...@redhat.com> > Subject: Re: [PATCH] xen-block: only advertize discard to the frontend when > it is enabled... > > On Wed, Mar 20, 2019 at 02:28:25PM +0000, Paul Durrant wrote: > > ...and properly enable it when synthesizing a drive. > > > > The Xen toolstack sets 'discard-enable' to '1' in xenstore when it wants > > to enable discard on a specified image. The code in > > xen_block_driver_create() correctly parses this and uses it to set > > typo: It's xen_block_drive_create (s/driver/drive/), otherwise my IDE > can't find it :-(.
Sorry, my fingers are so used to typing 'driver' > > > 'discard' to 'unamp' for the file_layer, but fails to do the same for the > > Looks like s/unamp/unmap/ Yes. > > > driver_layer (which effectively disables it). Meanwhile the code in > > xen_block_realize() advertizes discard support to the frontend in the > > default case (because conf->discard_granularity defaults to -1), even when > > That doesn't match the code I'm reading, before the patch apply. > if (discard_granularity > 0) feature-discard=1 > Nothing seems to set discard_granularity, so it keeps it's default to > -1, so .... wait, discard_granularity is unsigned :-( > > The description is fine then. Indeed. > > > the underlying image may not handle it. > > > > This patch adds the missing option to the driver_layer in > > xen_block_driver_create() and checks whether BDRV_O_UNMAP is actually > > set on the block device before advertizing discard to the frontend. > > In the case that discard is supported it also makes sure that the > > granularity is set to the physical block size. > > > > Signed-off-by: Paul Durrant <paul.durr...@citrix.com> > > With the two typos fixed (which I can try to remember to do on commit): > Reviewed-by: Anthony PERARD <anthony.per...@citrix.com> Ok, thanks. Paul > > Thanks, > > -- > Anthony PERARD _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
