* [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-08 10:46 ` Vaibhav Jain
0 siblings, 0 replies; 10+ messages in thread
From: Vaibhav Jain @ 2021-04-08 10:46 UTC (permalink / raw)
To: linux-nvdimm
Cc: Vaibhav Jain, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
In case a platform doesn't provide explicit flush-hints but provides an
explicit flush callback, then nvdimm_has_flush() still returns '0'
indicating that writes do not require flushing. This happens on PPC64
with patch at [1] applied, where 'deep_flush' of a region was denied
even though an explicit flush function was provided.
Similar problem is also seen with virtio-pmem where the 'deep_flush'
sysfs attribute is not visible as in absence of any registered nvdimm,
'nd_region->ndr_mappings == 0'.
Fix this by updating nvdimm_has_flush() adding a condition to
nvdimm_has_flush() to test if a 'region->flush' callback is
assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
regions may need 'flush' without any explicit mappings as in case of
virtio-pmem.
References:
[1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
Cc: <stable@vger.kernel.org>
Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:
v3:
* Removed the test for ND_REGION_SYNC to handle case where a
synchronous region still wants to expose a deep-flush function.
[ Aneesh ]
* Updated patch title and description from previous patch
https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
v2:
* Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
* Updated patch description to address the virtio-pmem case.
* Removed test for 'nd_region->ndr_mappings' from beginning of
nvdimm_has_flush() to handle the virtio-pmem case.
---
drivers/nvdimm/region_devs.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index ef23119db574..c4b17bdd527f 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
{
int i;
- /* no nvdimm or pmem api == flushing capability unknown */
- if (nd_region->ndr_mappings == 0
- || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
+ /* no pmem api == flushing capability unknown */
+ if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
return -ENXIO;
+ /* Test if an explicit flush function is defined */
+ if (nd_region->flush)
+ return 1;
+
+ /* Test if any flush hints for the region are available */
for (i = 0; i < nd_region->ndr_mappings; i++) {
struct nd_mapping *nd_mapping = &nd_region->mapping[i];
struct nvdimm *nvdimm = nd_mapping->nvdimm;
@@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
}
/*
- * The platform defines dimm devices without hints, assume
- * platform persistence mechanism like ADR
+ * The platform defines dimm devices without hints nor explicit flush,
+ * assume platform persistence mechanism like ADR
*/
return 0;
}
--
2.30.2
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply related [flat|nested] 10+ messages in thread
* [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-08 10:46 ` Vaibhav Jain
0 siblings, 0 replies; 10+ messages in thread
From: Vaibhav Jain @ 2021-04-08 10:46 UTC (permalink / raw)
To: linux-nvdimm
Cc: Vaibhav Jain, Dan Williams, Aneesh Kumar K . V, Michael Ellerman,
Santosh Sivaraj, Ira Weiny, stable, Shivaprasad G Bhat
In case a platform doesn't provide explicit flush-hints but provides an
explicit flush callback, then nvdimm_has_flush() still returns '0'
indicating that writes do not require flushing. This happens on PPC64
with patch at [1] applied, where 'deep_flush' of a region was denied
even though an explicit flush function was provided.
Similar problem is also seen with virtio-pmem where the 'deep_flush'
sysfs attribute is not visible as in absence of any registered nvdimm,
'nd_region->ndr_mappings == 0'.
Fix this by updating nvdimm_has_flush() adding a condition to
nvdimm_has_flush() to test if a 'region->flush' callback is
assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
regions may need 'flush' without any explicit mappings as in case of
virtio-pmem.
References:
[1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
Cc: <stable@vger.kernel.org>
Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:
v3:
* Removed the test for ND_REGION_SYNC to handle case where a
synchronous region still wants to expose a deep-flush function.
[ Aneesh ]
* Updated patch title and description from previous patch
https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
v2:
* Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
* Updated patch description to address the virtio-pmem case.
* Removed test for 'nd_region->ndr_mappings' from beginning of
nvdimm_has_flush() to handle the virtio-pmem case.
---
drivers/nvdimm/region_devs.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index ef23119db574..c4b17bdd527f 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
{
int i;
- /* no nvdimm or pmem api == flushing capability unknown */
- if (nd_region->ndr_mappings == 0
- || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
+ /* no pmem api == flushing capability unknown */
+ if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
return -ENXIO;
+ /* Test if an explicit flush function is defined */
+ if (nd_region->flush)
+ return 1;
+
+ /* Test if any flush hints for the region are available */
for (i = 0; i < nd_region->ndr_mappings; i++) {
struct nd_mapping *nd_mapping = &nd_region->mapping[i];
struct nvdimm *nvdimm = nd_mapping->nvdimm;
@@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
}
/*
- * The platform defines dimm devices without hints, assume
- * platform persistence mechanism like ADR
+ * The platform defines dimm devices without hints nor explicit flush,
+ * assume platform persistence mechanism like ADR
*/
return 0;
}
--
2.30.2
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
2021-04-08 10:46 ` Vaibhav Jain
@ 2021-04-12 6:52 ` Aneesh Kumar K.V
-1 siblings, 0 replies; 10+ messages in thread
From: Aneesh Kumar K.V @ 2021-04-12 6:52 UTC (permalink / raw)
To: Vaibhav Jain, linux-nvdimm, Dan Williams
Cc: Vaibhav Jain, Michael Ellerman, stable, Shivaprasad G Bhat
Vaibhav Jain <vaibhav@linux.ibm.com> writes:
> In case a platform doesn't provide explicit flush-hints but provides an
> explicit flush callback, then nvdimm_has_flush() still returns '0'
> indicating that writes do not require flushing. This happens on PPC64
> with patch at [1] applied, where 'deep_flush' of a region was denied
> even though an explicit flush function was provided.
>
> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> sysfs attribute is not visible as in absence of any registered nvdimm,
> 'nd_region->ndr_mappings == 0'.
>
> Fix this by updating nvdimm_has_flush() adding a condition to
> nvdimm_has_flush() to test if a 'region->flush' callback is
> assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
> regions may need 'flush' without any explicit mappings as in case of
> virtio-pmem.
>
> References:
> [1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
> https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Cc: <stable@vger.kernel.org>
> Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
> Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> ---
> Changelog:
>
> v3:
> * Removed the test for ND_REGION_SYNC to handle case where a
> synchronous region still wants to expose a deep-flush function.
> [ Aneesh ]
> * Updated patch title and description from previous patch
> https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
>
> v2:
> * Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
> * Updated patch description to address the virtio-pmem case.
> * Removed test for 'nd_region->ndr_mappings' from beginning of
> nvdimm_has_flush() to handle the virtio-pmem case.
> ---
> drivers/nvdimm/region_devs.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index ef23119db574..c4b17bdd527f 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> {
> int i;
>
> - /* no nvdimm or pmem api == flushing capability unknown */
> - if (nd_region->ndr_mappings == 0
> - || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> + /* no pmem api == flushing capability unknown */
> + if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> return -ENXIO;
>
> + /* Test if an explicit flush function is defined */
> + if (nd_region->flush)
> + return 1;
> +
> + /* Test if any flush hints for the region are available */
> for (i = 0; i < nd_region->ndr_mappings; i++) {
> struct nd_mapping *nd_mapping = &nd_region->mapping[i];
> struct nvdimm *nvdimm = nd_mapping->nvdimm;
> @@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> }
>
> /*
> - * The platform defines dimm devices without hints, assume
> - * platform persistence mechanism like ADR
> + * The platform defines dimm devices without hints nor explicit flush,
> + * assume platform persistence mechanism like ADR
> */
> return 0;
> }
> --
> 2.30.2
> _______________________________________________
> Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
> To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-12 6:52 ` Aneesh Kumar K.V
0 siblings, 0 replies; 10+ messages in thread
From: Aneesh Kumar K.V @ 2021-04-12 6:52 UTC (permalink / raw)
To: Vaibhav Jain, linux-nvdimm, Dan Williams
Cc: Vaibhav Jain, Michael Ellerman, stable, Shivaprasad G Bhat
Vaibhav Jain <vaibhav@linux.ibm.com> writes:
> In case a platform doesn't provide explicit flush-hints but provides an
> explicit flush callback, then nvdimm_has_flush() still returns '0'
> indicating that writes do not require flushing. This happens on PPC64
> with patch at [1] applied, where 'deep_flush' of a region was denied
> even though an explicit flush function was provided.
>
> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> sysfs attribute is not visible as in absence of any registered nvdimm,
> 'nd_region->ndr_mappings == 0'.
>
> Fix this by updating nvdimm_has_flush() adding a condition to
> nvdimm_has_flush() to test if a 'region->flush' callback is
> assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
> regions may need 'flush' without any explicit mappings as in case of
> virtio-pmem.
>
> References:
> [1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
> https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Cc: <stable@vger.kernel.org>
> Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
> Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> ---
> Changelog:
>
> v3:
> * Removed the test for ND_REGION_SYNC to handle case where a
> synchronous region still wants to expose a deep-flush function.
> [ Aneesh ]
> * Updated patch title and description from previous patch
> https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
>
> v2:
> * Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
> * Updated patch description to address the virtio-pmem case.
> * Removed test for 'nd_region->ndr_mappings' from beginning of
> nvdimm_has_flush() to handle the virtio-pmem case.
> ---
> drivers/nvdimm/region_devs.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index ef23119db574..c4b17bdd527f 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> {
> int i;
>
> - /* no nvdimm or pmem api == flushing capability unknown */
> - if (nd_region->ndr_mappings == 0
> - || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> + /* no pmem api == flushing capability unknown */
> + if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> return -ENXIO;
>
> + /* Test if an explicit flush function is defined */
> + if (nd_region->flush)
> + return 1;
> +
> + /* Test if any flush hints for the region are available */
> for (i = 0; i < nd_region->ndr_mappings; i++) {
> struct nd_mapping *nd_mapping = &nd_region->mapping[i];
> struct nvdimm *nvdimm = nd_mapping->nvdimm;
> @@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> }
>
> /*
> - * The platform defines dimm devices without hints, assume
> - * platform persistence mechanism like ADR
> + * The platform defines dimm devices without hints nor explicit flush,
> + * assume platform persistence mechanism like ADR
> */
> return 0;
> }
> --
> 2.30.2
> _______________________________________________
> Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
> To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
2021-04-08 10:46 ` Vaibhav Jain
@ 2021-04-12 7:52 ` Pankaj Gupta
-1 siblings, 0 replies; 10+ messages in thread
From: Pankaj Gupta @ 2021-04-12 7:52 UTC (permalink / raw)
To: Vaibhav Jain
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
Hi Vaibhav,
> In case a platform doesn't provide explicit flush-hints but provides an
> explicit flush callback, then nvdimm_has_flush() still returns '0'
> indicating that writes do not require flushing. This happens on PPC64
> with patch at [1] applied, where 'deep_flush' of a region was denied
> even though an explicit flush function was provided.
>
> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> sysfs attribute is not visible as in absence of any registered nvdimm,
> 'nd_region->ndr_mappings == 0'.
In case of async flush callback, do we still need "deep_flush" ?
Thanks,
Pankaj
>
> Fix this by updating nvdimm_has_flush() adding a condition to
> nvdimm_has_flush() to test if a 'region->flush' callback is
> assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
> regions may need 'flush' without any explicit mappings as in case of
> virtio-pmem.
>
> References:
> [1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
> https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
>
> Cc: <stable@vger.kernel.org>
> Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
> Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> ---
> Changelog:
>
> v3:
> * Removed the test for ND_REGION_SYNC to handle case where a
> synchronous region still wants to expose a deep-flush function.
> [ Aneesh ]
> * Updated patch title and description from previous patch
> https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
>
> v2:
> * Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
> * Updated patch description to address the virtio-pmem case.
> * Removed test for 'nd_region->ndr_mappings' from beginning of
> nvdimm_has_flush() to handle the virtio-pmem case.
> ---
> drivers/nvdimm/region_devs.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index ef23119db574..c4b17bdd527f 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> {
> int i;
>
> - /* no nvdimm or pmem api == flushing capability unknown */
> - if (nd_region->ndr_mappings == 0
> - || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> + /* no pmem api == flushing capability unknown */
> + if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> return -ENXIO;
>
> + /* Test if an explicit flush function is defined */
> + if (nd_region->flush)
> + return 1;
> +
> + /* Test if any flush hints for the region are available */
> for (i = 0; i < nd_region->ndr_mappings; i++) {
> struct nd_mapping *nd_mapping = &nd_region->mapping[i];
> struct nvdimm *nvdimm = nd_mapping->nvdimm;
> @@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> }
>
> /*
> - * The platform defines dimm devices without hints, assume
> - * platform persistence mechanism like ADR
> + * The platform defines dimm devices without hints nor explicit flush,
> + * assume platform persistence mechanism like ADR
> */
> return 0;
> }
> --
> 2.30.2
> _______________________________________________
> Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
> To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-12 7:52 ` Pankaj Gupta
0 siblings, 0 replies; 10+ messages in thread
From: Pankaj Gupta @ 2021-04-12 7:52 UTC (permalink / raw)
To: Vaibhav Jain
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
Hi Vaibhav,
> In case a platform doesn't provide explicit flush-hints but provides an
> explicit flush callback, then nvdimm_has_flush() still returns '0'
> indicating that writes do not require flushing. This happens on PPC64
> with patch at [1] applied, where 'deep_flush' of a region was denied
> even though an explicit flush function was provided.
>
> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> sysfs attribute is not visible as in absence of any registered nvdimm,
> 'nd_region->ndr_mappings == 0'.
In case of async flush callback, do we still need "deep_flush" ?
Thanks,
Pankaj
>
> Fix this by updating nvdimm_has_flush() adding a condition to
> nvdimm_has_flush() to test if a 'region->flush' callback is
> assigned. Also remove explicit test for 'nd_region->ndr_mapping' since
> regions may need 'flush' without any explicit mappings as in case of
> virtio-pmem.
>
> References:
> [1] "powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall"
> https://lore.kernel.org/linux-nvdimm/161703936121.36.7260632399582101498.stgit@e1fbed493c87
>
> Cc: <stable@vger.kernel.org>
> Fixes: c5d4355d10d4 ("libnvdimm: nd_region flush callback support")
> Reported-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> ---
> Changelog:
>
> v3:
> * Removed the test for ND_REGION_SYNC to handle case where a
> synchronous region still wants to expose a deep-flush function.
> [ Aneesh ]
> * Updated patch title and description from previous patch
> https://lore.kernel.org/linux-nvdimm/5e64778d-bf48-9f10-7d3d-5e530e5db590@linux.ibm.com
>
> v2:
> * Added the fixes tag and addressed the patch to stable tree [ Aneesh ]
> * Updated patch description to address the virtio-pmem case.
> * Removed test for 'nd_region->ndr_mappings' from beginning of
> nvdimm_has_flush() to handle the virtio-pmem case.
> ---
> drivers/nvdimm/region_devs.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
> index ef23119db574..c4b17bdd527f 100644
> --- a/drivers/nvdimm/region_devs.c
> +++ b/drivers/nvdimm/region_devs.c
> @@ -1234,11 +1234,15 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> {
> int i;
>
> - /* no nvdimm or pmem api == flushing capability unknown */
> - if (nd_region->ndr_mappings == 0
> - || !IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> + /* no pmem api == flushing capability unknown */
> + if (!IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API))
> return -ENXIO;
>
> + /* Test if an explicit flush function is defined */
> + if (nd_region->flush)
> + return 1;
> +
> + /* Test if any flush hints for the region are available */
> for (i = 0; i < nd_region->ndr_mappings; i++) {
> struct nd_mapping *nd_mapping = &nd_region->mapping[i];
> struct nvdimm *nvdimm = nd_mapping->nvdimm;
> @@ -1249,8 +1253,8 @@ int nvdimm_has_flush(struct nd_region *nd_region)
> }
>
> /*
> - * The platform defines dimm devices without hints, assume
> - * platform persistence mechanism like ADR
> + * The platform defines dimm devices without hints nor explicit flush,
> + * assume platform persistence mechanism like ADR
> */
> return 0;
> }
> --
> 2.30.2
> _______________________________________________
> Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
> To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
2021-04-12 7:52 ` Pankaj Gupta
@ 2021-04-13 14:53 ` Vaibhav Jain
-1 siblings, 0 replies; 10+ messages in thread
From: Vaibhav Jain @ 2021-04-13 14:53 UTC (permalink / raw)
To: Pankaj Gupta
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
Thanks Pankaj for looking into this patch,
Pankaj Gupta <pankaj.gupta.linux@gmail.com> writes:
> Hi Vaibhav,
>
>> In case a platform doesn't provide explicit flush-hints but provides an
>> explicit flush callback, then nvdimm_has_flush() still returns '0'
>> indicating that writes do not require flushing. This happens on PPC64
>> with patch at [1] applied, where 'deep_flush' of a region was denied
>> even though an explicit flush function was provided.
>>
>> Similar problem is also seen with virtio-pmem where the 'deep_flush'
>> sysfs attribute is not visible as in absence of any registered nvdimm,
>> 'nd_region->ndr_mappings == 0'.
>
> In case of async flush callback, do we still need "deep_flush" ?
'deep_flush' in libnvdimm (specifically 'deep_flush_store()')
anyways resorts to calling 'async_flush' callback if its defined. Which
makes sense to me since in absence of eADR, 'echo 1 > deep_flush' would
ensure that writes to pmem are now durable even if there is a sudden
power loss before cpu caches are flushed.
On non-nfit architectures the 'async_flush' callback should provide such
a guarantee, which can be triggered by user-space writing to the
'deep_flush' sysfs attr.
In absence of 'deep_flush' sysfs attr not sure how else can user-space
forcibly trigger async_flush callback for dev-dax char devices.
<snip>
--
Cheers
~ Vaibhav
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-13 14:53 ` Vaibhav Jain
0 siblings, 0 replies; 10+ messages in thread
From: Vaibhav Jain @ 2021-04-13 14:53 UTC (permalink / raw)
To: Pankaj Gupta
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
Thanks Pankaj for looking into this patch,
Pankaj Gupta <pankaj.gupta.linux@gmail.com> writes:
> Hi Vaibhav,
>
>> In case a platform doesn't provide explicit flush-hints but provides an
>> explicit flush callback, then nvdimm_has_flush() still returns '0'
>> indicating that writes do not require flushing. This happens on PPC64
>> with patch at [1] applied, where 'deep_flush' of a region was denied
>> even though an explicit flush function was provided.
>>
>> Similar problem is also seen with virtio-pmem where the 'deep_flush'
>> sysfs attribute is not visible as in absence of any registered nvdimm,
>> 'nd_region->ndr_mappings == 0'.
>
> In case of async flush callback, do we still need "deep_flush" ?
'deep_flush' in libnvdimm (specifically 'deep_flush_store()')
anyways resorts to calling 'async_flush' callback if its defined. Which
makes sense to me since in absence of eADR, 'echo 1 > deep_flush' would
ensure that writes to pmem are now durable even if there is a sudden
power loss before cpu caches are flushed.
On non-nfit architectures the 'async_flush' callback should provide such
a guarantee, which can be triggered by user-space writing to the
'deep_flush' sysfs attr.
In absence of 'deep_flush' sysfs attr not sure how else can user-space
forcibly trigger async_flush callback for dev-dax char devices.
<snip>
--
Cheers
~ Vaibhav
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
2021-04-13 14:53 ` Vaibhav Jain
@ 2021-04-14 10:22 ` Pankaj Gupta
-1 siblings, 0 replies; 10+ messages in thread
From: Pankaj Gupta @ 2021-04-14 10:22 UTC (permalink / raw)
To: Vaibhav Jain
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
> >> In case a platform doesn't provide explicit flush-hints but provides an
> >> explicit flush callback, then nvdimm_has_flush() still returns '0'
> >> indicating that writes do not require flushing. This happens on PPC64
> >> with patch at [1] applied, where 'deep_flush' of a region was denied
> >> even though an explicit flush function was provided.
> >>
> >> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> >> sysfs attribute is not visible as in absence of any registered nvdimm,
> >> 'nd_region->ndr_mappings == 0'.
> >
> > In case of async flush callback, do we still need "deep_flush" ?
>
> 'deep_flush' in libnvdimm (specifically 'deep_flush_store()')
> anyways resorts to calling 'async_flush' callback if its defined. Which
> makes sense to me since in absence of eADR, 'echo 1 > deep_flush' would
> ensure that writes to pmem are now durable even if there is a sudden
> power loss before cpu caches are flushed.
>
> On non-nfit architectures the 'async_flush' callback should provide such
> a guarantee, which can be triggered by user-space writing to the
> 'deep_flush' sysfs attr.
>
> In absence of 'deep_flush' sysfs attr not sure how else can user-space
> forcibly trigger async_flush callback for dev-dax char devices.
O.k. that means for filesystem DAX deep_flush is alternative to
fsync/msync call.
I still have to dig deeper to understand more about "QUEUE_FLAG_FUA" flag &
why I was seeing REQ_FUA with virtio-pmem when doing fsync if its not enabled
in function "blk_queue_write_cache". But this is for my understanding.
Overall patch looks good to me and it looks to solve (not tested
though) the warning for
virtio-pmem as well.
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
Thanks,
Pankaj
_______________________________________________
Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org
To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks
@ 2021-04-14 10:22 ` Pankaj Gupta
0 siblings, 0 replies; 10+ messages in thread
From: Pankaj Gupta @ 2021-04-14 10:22 UTC (permalink / raw)
To: Vaibhav Jain
Cc: linux-nvdimm, Aneesh Kumar K . V, Michael Ellerman, stable,
Shivaprasad G Bhat
> >> In case a platform doesn't provide explicit flush-hints but provides an
> >> explicit flush callback, then nvdimm_has_flush() still returns '0'
> >> indicating that writes do not require flushing. This happens on PPC64
> >> with patch at [1] applied, where 'deep_flush' of a region was denied
> >> even though an explicit flush function was provided.
> >>
> >> Similar problem is also seen with virtio-pmem where the 'deep_flush'
> >> sysfs attribute is not visible as in absence of any registered nvdimm,
> >> 'nd_region->ndr_mappings == 0'.
> >
> > In case of async flush callback, do we still need "deep_flush" ?
>
> 'deep_flush' in libnvdimm (specifically 'deep_flush_store()')
> anyways resorts to calling 'async_flush' callback if its defined. Which
> makes sense to me since in absence of eADR, 'echo 1 > deep_flush' would
> ensure that writes to pmem are now durable even if there is a sudden
> power loss before cpu caches are flushed.
>
> On non-nfit architectures the 'async_flush' callback should provide such
> a guarantee, which can be triggered by user-space writing to the
> 'deep_flush' sysfs attr.
>
> In absence of 'deep_flush' sysfs attr not sure how else can user-space
> forcibly trigger async_flush callback for dev-dax char devices.
O.k. that means for filesystem DAX deep_flush is alternative to
fsync/msync call.
I still have to dig deeper to understand more about "QUEUE_FLAG_FUA" flag &
why I was seeing REQ_FUA with virtio-pmem when doing fsync if its not enabled
in function "blk_queue_write_cache". But this is for my understanding.
Overall patch looks good to me and it looks to solve (not tested
though) the warning for
virtio-pmem as well.
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
Thanks,
Pankaj
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-04-14 10:23 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-08 10:46 [PATCH v3] libnvdimm/region: Update nvdimm_has_flush() to handle explicit 'flush' callbacks Vaibhav Jain
2021-04-08 10:46 ` Vaibhav Jain
2021-04-12 6:52 ` Aneesh Kumar K.V
2021-04-12 6:52 ` Aneesh Kumar K.V
2021-04-12 7:52 ` Pankaj Gupta
2021-04-12 7:52 ` Pankaj Gupta
2021-04-13 14:53 ` Vaibhav Jain
2021-04-13 14:53 ` Vaibhav Jain
2021-04-14 10:22 ` Pankaj Gupta
2021-04-14 10:22 ` Pankaj Gupta
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