| Message ID | 20210118151528.81668-1-roger.pau@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xen-blkfront: don't make discard-alignment mandatory | expand |
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@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> > --- > 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. Juergen
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@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> > > --- > > 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. Thanks, Roger.
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@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> >>> --- >>> 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
On Tue, Jan 19, 2021 at 11:11:26AM +0100, Jürgen Groß wrote: > 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@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> > > > > --- > > > > 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. No, in fact I think I need to rework this a little further. Just having feature-discard = 1 should enable the discard functionality, by setting discard-granularity = physical block size and discard-alignment = 0. Roger.
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); - if (!err) { - info->discard_granularity = discard_granularity; - info->discard_alignment = discard_alignment; - } - info->feature_secdiscard = - !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", - 0); + + if (!discard_granularity) + return; + + info->feature_discard = 1; + info->discard_granularity = discard_granularity; + info->discard_alignment = discard_alignment; + info->feature_secdiscard = !!discard_secure; } static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
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@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> --- drivers/block/xen-blkfront.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)