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Commit a4af5503 authored by Roger Pau Monne's avatar Roger Pau Monne Committed by Greg Kroah-Hartman
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xen-blkfront: allow discard-* nodes to be optional 



commit 0549cd67b01016b579047bce045b386202a8bcfc upstream.

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: ed30bf31 ('xen-blkfront: Handle discard requests.')
Reported-by: default avatarArthur Borsboom <arthurborsboom@gmail.com>
Signed-off-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
Reviewed-by: default avatarJuergen Gross <jgross@suse.com>
Tested-By: default avatarArthur Borsboom <arthurborsboom@gmail.com>
Link: https://lore.kernel.org/r/20210119105727.95173-1-roger.pau@citrix.com


Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6974d9cf

drivers/block/xen-blkfront.c

+7 −13
Original line number Diff line number Diff line
@@ -936,7 +936,8 @@ static void blkif_set_queue_limits(struct blkfront_info *info) 
	if (info->feature_discard) {

		blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);

		blk_queue_max_discard_sectors(rq, get_capacity(gd));

		rq->limits.discard_granularity = info->discard_granularity;

		rq->limits.discard_granularity = info->discard_granularity ?:

						 info->physical_sector_size;

		rq->limits.discard_alignment = info->discard_alignment;

		if (info->feature_secdiscard)

			blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
@@ -2169,19 +2170,12 @@ static void blkfront_closing(struct blkfront_info *info) 


static void blkfront_setup_discard(struct blkfront_info *info)

{

	int err;

	unsigned int discard_granularity;

	unsigned int discard_alignment;



	info->feature_discard = 1;

	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,

		"discard-granularity", "%u", &discard_granularity,

		"discard-alignment", "%u", &discard_alignment,

		NULL);

	if (!err) {

		info->discard_granularity = discard_granularity;

		info->discard_alignment = discard_alignment;

	}

	info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,

							 "discard-granularity",

							 0);

	info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,

						       "discard-alignment", 0);

	info->feature_secdiscard =

		!!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",

				       0);