This is inline with the specification described in blkif.h:
* discard-granularity: should be set to the physical block size if
node is not present.
* discard-alignment, discard-secure: should be set to 0 if node not
present.
This was detected as QEMU would only create the discard-granularity
node but not discard-alignment, and thus the setup done in
blkfront_setup_discard would fail.
Fix blkfront_setup_discard to not fail on missing nodes, and also fix
blkif_set_queue_limits to set the discard granularity to the physical
block size if none is specified in xenbus.
Fixes: ed30bf317c ('xen-blkfront: Handle discard requests.')
Reported-by: Arthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-By: Arthur Borsboom <arthurborsboom@gmail.com>
Link: https://lore.kernel.org/r/20210119105727.95173-1-roger.pau@citrix.com
Signed-off-by: Juergen Gross <jgross@suse.com>
0549cd67b0