On 19.01.21 11:06, Roger Pau Monné wrote:
On Tue, Jan 19, 2021 at 08:43:01AM +0100, Jürgen Groß wrote:On 18.01.21 16:15, Roger Pau Monne wrote:Don't require the discard-alignment xenstore node to be present in order to correctly setup the feature. This can happen with versions of QEMU that only write the discard-granularity but not the discard-alignment node. Assume discard-alignment is 0 if not present. While there also fix the logic to not enable the discard feature if discard-granularity is not present. Reported-by: Arthur Borsboom <arthurborsboom@xxxxxxxxx> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> --- Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: "Roger Pau Monné" <roger.pau@xxxxxxxxxx> Cc: Jens Axboe <axboe@xxxxxxxxx> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx Cc: linux-block@xxxxxxxxxxxxxxx Cc: Arthur Borsboom <arthurborsboom@xxxxxxxxx> --- drivers/block/xen-blkfront.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 5265975b3fba..5a93f7cc2939 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -2179,22 +2179,23 @@ 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; + unsigned int discard_granularity = 0; + unsigned int discard_alignment = 0; + unsigned int discard_secure = 0; - info->feature_discard = 1; - err = xenbus_gather(XBT_NIL, info->xbdev->otherend, + xenbus_gather(XBT_NIL, info->xbdev->otherend, "discard-granularity", "%u", &discard_granularity, "discard-alignment", "%u", &discard_alignment, + "discard-secure", "%u", &discard_secure, NULL);This would mean that "discard-secure" will be evaluated only if the other two items are set in Xenstore. From blkif.h I can't see this is required, and your patch is modifying today's behavior in this regard. You might want to have three xenbus_read_unsigned() calls instead.You are right, discard-secure should be fetched regardless of whether discard-alignment exists. I can fetch discard-granularity and discard-alignment using xenbus_gather and keep discard-secure using xenbus_read_unsigned. Let me send a new version.
I'm still not convinced this is correct. blkif.h doesn't mention that discard-alignment will be valid only with discard-granularity being present. Juergen
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