Forgot to Cc stable for the Fixes tag. Doing it now.

On Tue, Jan 19, 2021 at 11:57:27AM +0100, Roger Pau Monne wrote:

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

---

Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Juergen Gross jgross@suse.com Cc: Stefano Stabellini sstabellini@kernel.org Cc: Konrad Rzeszutek Wilk konrad.wilk@oracle.com Cc: "Roger Pau Monné" roger.pau@citrix.com Cc: Jens Axboe axboe@kernel.dk Cc: xen-devel@lists.xenproject.org Cc: linux-block@vger.kernel.org Cc: Arthur Borsboom arthurborsboom@gmail.com

---

Changes since v2:

• Allow all discard-* nodes to be optional.

---

drivers/block/xen-blkfront.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 5265975b3fba..e1c6798889f4 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -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);

-- 2.29.2