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xen-blkfront: allow discard-* nodes to be optional

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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: ed30bf317c5ce ('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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Roger Pau Monne 2021-01-19 11:57:27 +01:00 committed by Greg Kroah-Hartman
parent a164789b86
commit 7d6e01e275
1 changed files with 7 additions and 13 deletions
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20
drivers/block/xen-blkfront.c
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@ -945,7 +945,8 @@ 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);
@ -2179,19 +2180,12 @@ 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);