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* fix a dax/block device attribute registration regression
@ 2021-09-22 18:33 Christoph Hellwig
  2021-09-22 18:33 ` [PATCH 1/3] nvdimm/pmem: fix creating the dax group Christoph Hellwig
                   ` (3 more replies)
  0 siblings, 4 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-22 18:33 UTC (permalink / raw)
  To: Dan Williams, Jens Axboe
  Cc: Vishal Verma, Dave Jiang, Ira Weiny, linux-block, nvdimm

Hi Dan and Jens,

this series fixed a regression in how the dax/write_cache attribute of the
pmem devices was registere.  It does so by both fixing the API abuse in the
driver and (temporarily) the behavior change in the block layer that made
this API abuse not work anymore.

Diffstat:
 block/genhd.c         |    3 +-
 drivers/dax/super.c   |   64 --------------------------------------------------
 drivers/nvdimm/pmem.c |   48 ++++++++++++++++++++++++++++++++++---
 include/linux/dax.h   |    2 -
 4 files changed, 46 insertions(+), 71 deletions(-)

^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH 1/3] nvdimm/pmem: fix creating the dax group
  2021-09-22 18:33 fix a dax/block device attribute registration regression Christoph Hellwig
@ 2021-09-22 18:33 ` Christoph Hellwig
  2021-09-22 18:33 ` [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem Christoph Hellwig
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-22 18:33 UTC (permalink / raw)
  To: Dan Williams, Jens Axboe
  Cc: Vishal Verma, Dave Jiang, Ira Weiny, linux-block, nvdimm

The recent block layer refactoring broke the way how the pmem driver
abused device_add_disk.  Fix this by properly passing the attribute groups
to device_add_disk.

Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/nvdimm/pmem.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 72de88ff0d30d..ef4950f808326 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -380,7 +380,6 @@ static int pmem_attach_disk(struct device *dev,
 	struct nd_pfn_sb *pfn_sb;
 	struct pmem_device *pmem;
 	struct request_queue *q;
-	struct device *gendev;
 	struct gendisk *disk;
 	void *addr;
 	int rc;
@@ -489,10 +488,8 @@ static int pmem_attach_disk(struct device *dev,
 	}
 	dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
 	pmem->dax_dev = dax_dev;
-	gendev = disk_to_dev(disk);
-	gendev->groups = pmem_attribute_groups;
 
-	device_add_disk(dev, disk, NULL);
+	device_add_disk(dev, disk, pmem_attribute_groups);
 	if (devm_add_action_or_reset(dev, pmem_release_disk, pmem))
 		return -ENOMEM;
 
-- 
2.30.2


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem
  2021-09-22 18:33 fix a dax/block device attribute registration regression Christoph Hellwig
  2021-09-22 18:33 ` [PATCH 1/3] nvdimm/pmem: fix creating the dax group Christoph Hellwig
@ 2021-09-22 18:33 ` Christoph Hellwig
  2021-09-22 21:40   ` Ira Weiny
  2021-09-22 18:33 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
  2021-09-27 18:19 ` fix a dax/block device attribute registration regression Dan Williams
  3 siblings, 1 reply; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-22 18:33 UTC (permalink / raw)
  To: Dan Williams, Jens Axboe
  Cc: Vishal Verma, Dave Jiang, Ira Weiny, linux-block, nvdimm

dax_attribute_group is only used by the pmem driver, and can avoid the
completely pointless lookup by the disk name if moved there.  This
leaves just a single caller of dax_get_by_host, so move dax_get_by_host
into the same ifdef block as that caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/dax/super.c   | 100 ++++++++----------------------------------
 drivers/nvdimm/pmem.c |  43 ++++++++++++++++++
 include/linux/dax.h   |   2 -
 3 files changed, 61 insertions(+), 84 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index fc89e91beea7c..b882cf8106ea3 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -63,6 +63,24 @@ static int dax_host_hash(const char *host)
 	return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE;
 }
 
+#ifdef CONFIG_BLOCK
+#include <linux/blkdev.h>
+
+int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
+		pgoff_t *pgoff)
+{
+	sector_t start_sect = bdev ? get_start_sect(bdev) : 0;
+	phys_addr_t phys_off = (start_sect + sector) * 512;
+
+	if (pgoff)
+		*pgoff = PHYS_PFN(phys_off);
+	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
+		return -EINVAL;
+	return 0;
+}
+EXPORT_SYMBOL(bdev_dax_pgoff);
+
+#if IS_ENABLED(CONFIG_FS_DAX)
 /**
  * dax_get_by_host() - temporary lookup mechanism for filesystem-dax
  * @host: alternate name for the device registered by a dax driver
@@ -94,24 +112,6 @@ static struct dax_device *dax_get_by_host(const char *host)
 	return found;
 }
 
-#ifdef CONFIG_BLOCK
-#include <linux/blkdev.h>
-
-int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
-		pgoff_t *pgoff)
-{
-	sector_t start_sect = bdev ? get_start_sect(bdev) : 0;
-	phys_addr_t phys_off = (start_sect + sector) * 512;
-
-	if (pgoff)
-		*pgoff = PHYS_PFN(phys_off);
-	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
-		return -EINVAL;
-	return 0;
-}
-EXPORT_SYMBOL(bdev_dax_pgoff);
-
-#if IS_ENABLED(CONFIG_FS_DAX)
 struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 {
 	if (!blk_queue_dax(bdev->bd_disk->queue))
@@ -231,70 +231,6 @@ enum dax_device_flags {
 	DAXDEV_SYNC,
 };
 
-static ssize_t write_cache_show(struct device *dev,
-		struct device_attribute *attr, char *buf)
-{
-	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
-	ssize_t rc;
-
-	WARN_ON_ONCE(!dax_dev);
-	if (!dax_dev)
-		return -ENXIO;
-
-	rc = sprintf(buf, "%d\n", !!dax_write_cache_enabled(dax_dev));
-	put_dax(dax_dev);
-	return rc;
-}
-
-static ssize_t write_cache_store(struct device *dev,
-		struct device_attribute *attr, const char *buf, size_t len)
-{
-	bool write_cache;
-	int rc = strtobool(buf, &write_cache);
-	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
-
-	WARN_ON_ONCE(!dax_dev);
-	if (!dax_dev)
-		return -ENXIO;
-
-	if (rc)
-		len = rc;
-	else
-		dax_write_cache(dax_dev, write_cache);
-
-	put_dax(dax_dev);
-	return len;
-}
-static DEVICE_ATTR_RW(write_cache);
-
-static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
-{
-	struct device *dev = container_of(kobj, typeof(*dev), kobj);
-	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
-
-	WARN_ON_ONCE(!dax_dev);
-	if (!dax_dev)
-		return 0;
-
-#ifndef CONFIG_ARCH_HAS_PMEM_API
-	if (a == &dev_attr_write_cache.attr)
-		return 0;
-#endif
-	return a->mode;
-}
-
-static struct attribute *dax_attributes[] = {
-	&dev_attr_write_cache.attr,
-	NULL,
-};
-
-struct attribute_group dax_attribute_group = {
-	.name = "dax",
-	.attrs = dax_attributes,
-	.is_visible = dax_visible,
-};
-EXPORT_SYMBOL_GPL(dax_attribute_group);
-
 /**
  * dax_direct_access() - translate a device pgoff to an absolute pfn
  * @dax_dev: a dax_device instance representing the logical memory range
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index ef4950f808326..bbeb3f46db157 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -328,6 +328,49 @@ static const struct dax_operations pmem_dax_ops = {
 	.zero_page_range = pmem_dax_zero_page_range,
 };
 
+static ssize_t write_cache_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct pmem_device *pmem = dev_to_disk(dev)->private_data;
+
+	return sprintf(buf, "%d\n", !!dax_write_cache_enabled(pmem->dax_dev));
+}
+
+static ssize_t write_cache_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct pmem_device *pmem = dev_to_disk(dev)->private_data;
+	bool write_cache;
+	int rc;
+
+	rc = strtobool(buf, &write_cache);
+	if (rc)
+		return rc;
+	dax_write_cache(pmem->dax_dev, write_cache);
+	return len;
+}
+static DEVICE_ATTR_RW(write_cache);
+
+static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+#ifndef CONFIG_ARCH_HAS_PMEM_API
+	if (a == &dev_attr_write_cache.attr)
+		return 0;
+#endif
+	return a->mode;
+}
+
+static struct attribute *dax_attributes[] = {
+	&dev_attr_write_cache.attr,
+	NULL,
+};
+
+static const struct attribute_group dax_attribute_group = {
+	.name		= "dax",
+	.attrs		= dax_attributes,
+	.is_visible	= dax_visible,
+};
+
 static const struct attribute_group *pmem_attribute_groups[] = {
 	&dax_attribute_group,
 	NULL,
diff --git a/include/linux/dax.h b/include/linux/dax.h
index 2619d94c308d4..8623caa673889 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -38,8 +38,6 @@ struct dax_operations {
 	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
 };
 
-extern struct attribute_group dax_attribute_group;
-
 #if IS_ENABLED(CONFIG_DAX)
 struct dax_device *alloc_dax(void *private, const char *host,
 		const struct dax_operations *ops, unsigned long flags);
-- 
2.30.2


^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-22 18:33 fix a dax/block device attribute registration regression Christoph Hellwig
  2021-09-22 18:33 ` [PATCH 1/3] nvdimm/pmem: fix creating the dax group Christoph Hellwig
  2021-09-22 18:33 ` [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem Christoph Hellwig
@ 2021-09-22 18:33 ` Christoph Hellwig
  2021-09-27 18:19 ` fix a dax/block device attribute registration regression Dan Williams
  3 siblings, 0 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-22 18:33 UTC (permalink / raw)
  To: Dan Williams, Jens Axboe
  Cc: Vishal Verma, Dave Jiang, Ira Weiny, linux-block, nvdimm

The proper API is to pass the groups to device_add_disk, but the code
used to also allow groups being set before calling *add_disk.  Warn
about that but keep the group pointer intact for now so that it can
be removed again after a grace period.

Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
---
 block/genhd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 7b6e5e1cf9564..409cf608cc5bd 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -439,7 +439,8 @@ int device_add_disk(struct device *parent, struct gendisk *disk,
 	dev_set_uevent_suppress(ddev, 1);
 
 	ddev->parent = parent;
-	ddev->groups = groups;
+	if (!WARN_ON_ONCE(ddev->groups))
+		ddev->groups = groups;
 	dev_set_name(ddev, "%s", disk->disk_name);
 	if (!(disk->flags & GENHD_FL_HIDDEN))
 		ddev->devt = MKDEV(disk->major, disk->first_minor);
-- 
2.30.2


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem
  2021-09-22 18:33 ` [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem Christoph Hellwig
@ 2021-09-22 21:40   ` Ira Weiny
  0 siblings, 0 replies; 11+ messages in thread
From: Ira Weiny @ 2021-09-22 21:40 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Dan Williams, Jens Axboe, Vishal Verma, Dave Jiang, linux-block, nvdimm

On Wed, Sep 22, 2021 at 08:33:30PM +0200, Christoph Hellwig wrote:
> dax_attribute_group is only used by the pmem driver, and can avoid the
> completely pointless lookup by the disk name if moved there.  This
> leaves just a single caller of dax_get_by_host, so move dax_get_by_host
> into the same ifdef block as that caller.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> ---
>  drivers/dax/super.c   | 100 ++++++++----------------------------------
>  drivers/nvdimm/pmem.c |  43 ++++++++++++++++++
>  include/linux/dax.h   |   2 -
>  3 files changed, 61 insertions(+), 84 deletions(-)
> 
> diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> index fc89e91beea7c..b882cf8106ea3 100644
> --- a/drivers/dax/super.c
> +++ b/drivers/dax/super.c
> @@ -63,6 +63,24 @@ static int dax_host_hash(const char *host)
>  	return hashlen_hash(hashlen_string("DAX", host)) % DAX_HASH_SIZE;
>  }
>  
> +#ifdef CONFIG_BLOCK
> +#include <linux/blkdev.h>
> +
> +int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> +		pgoff_t *pgoff)
> +{
> +	sector_t start_sect = bdev ? get_start_sect(bdev) : 0;
> +	phys_addr_t phys_off = (start_sect + sector) * 512;
> +
> +	if (pgoff)
> +		*pgoff = PHYS_PFN(phys_off);
> +	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
> +		return -EINVAL;
> +	return 0;
> +}
> +EXPORT_SYMBOL(bdev_dax_pgoff);
> +
> +#if IS_ENABLED(CONFIG_FS_DAX)
>  /**
>   * dax_get_by_host() - temporary lookup mechanism for filesystem-dax
>   * @host: alternate name for the device registered by a dax driver
> @@ -94,24 +112,6 @@ static struct dax_device *dax_get_by_host(const char *host)
>  	return found;
>  }
>  
> -#ifdef CONFIG_BLOCK
> -#include <linux/blkdev.h>
> -
> -int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size,
> -		pgoff_t *pgoff)
> -{
> -	sector_t start_sect = bdev ? get_start_sect(bdev) : 0;
> -	phys_addr_t phys_off = (start_sect + sector) * 512;
> -
> -	if (pgoff)
> -		*pgoff = PHYS_PFN(phys_off);
> -	if (phys_off % PAGE_SIZE || size % PAGE_SIZE)
> -		return -EINVAL;
> -	return 0;
> -}
> -EXPORT_SYMBOL(bdev_dax_pgoff);
> -
> -#if IS_ENABLED(CONFIG_FS_DAX)
>  struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
>  {
>  	if (!blk_queue_dax(bdev->bd_disk->queue))
> @@ -231,70 +231,6 @@ enum dax_device_flags {
>  	DAXDEV_SYNC,
>  };
>  
> -static ssize_t write_cache_show(struct device *dev,
> -		struct device_attribute *attr, char *buf)
> -{
> -	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
> -	ssize_t rc;
> -
> -	WARN_ON_ONCE(!dax_dev);
> -	if (!dax_dev)
> -		return -ENXIO;
> -
> -	rc = sprintf(buf, "%d\n", !!dax_write_cache_enabled(dax_dev));
> -	put_dax(dax_dev);
> -	return rc;
> -}
> -
> -static ssize_t write_cache_store(struct device *dev,
> -		struct device_attribute *attr, const char *buf, size_t len)
> -{
> -	bool write_cache;
> -	int rc = strtobool(buf, &write_cache);
> -	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
> -
> -	WARN_ON_ONCE(!dax_dev);
> -	if (!dax_dev)
> -		return -ENXIO;
> -
> -	if (rc)
> -		len = rc;
> -	else
> -		dax_write_cache(dax_dev, write_cache);
> -
> -	put_dax(dax_dev);
> -	return len;
> -}
> -static DEVICE_ATTR_RW(write_cache);
> -
> -static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
> -{
> -	struct device *dev = container_of(kobj, typeof(*dev), kobj);
> -	struct dax_device *dax_dev = dax_get_by_host(dev_name(dev));
> -
> -	WARN_ON_ONCE(!dax_dev);
> -	if (!dax_dev)
> -		return 0;
> -
> -#ifndef CONFIG_ARCH_HAS_PMEM_API
> -	if (a == &dev_attr_write_cache.attr)
> -		return 0;
> -#endif
> -	return a->mode;
> -}
> -
> -static struct attribute *dax_attributes[] = {
> -	&dev_attr_write_cache.attr,
> -	NULL,
> -};
> -
> -struct attribute_group dax_attribute_group = {
> -	.name = "dax",
> -	.attrs = dax_attributes,
> -	.is_visible = dax_visible,
> -};
> -EXPORT_SYMBOL_GPL(dax_attribute_group);
> -
>  /**
>   * dax_direct_access() - translate a device pgoff to an absolute pfn
>   * @dax_dev: a dax_device instance representing the logical memory range
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index ef4950f808326..bbeb3f46db157 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -328,6 +328,49 @@ static const struct dax_operations pmem_dax_ops = {
>  	.zero_page_range = pmem_dax_zero_page_range,
>  };
>  
> +static ssize_t write_cache_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct pmem_device *pmem = dev_to_disk(dev)->private_data;
> +
> +	return sprintf(buf, "%d\n", !!dax_write_cache_enabled(pmem->dax_dev));
> +}
> +
> +static ssize_t write_cache_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct pmem_device *pmem = dev_to_disk(dev)->private_data;
> +	bool write_cache;
> +	int rc;
> +
> +	rc = strtobool(buf, &write_cache);
> +	if (rc)
> +		return rc;
> +	dax_write_cache(pmem->dax_dev, write_cache);
> +	return len;
> +}
> +static DEVICE_ATTR_RW(write_cache);
> +
> +static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
> +{
> +#ifndef CONFIG_ARCH_HAS_PMEM_API
> +	if (a == &dev_attr_write_cache.attr)
> +		return 0;
> +#endif
> +	return a->mode;
> +}
> +
> +static struct attribute *dax_attributes[] = {
> +	&dev_attr_write_cache.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group dax_attribute_group = {
> +	.name		= "dax",
> +	.attrs		= dax_attributes,
> +	.is_visible	= dax_visible,
> +};
> +
>  static const struct attribute_group *pmem_attribute_groups[] = {
>  	&dax_attribute_group,
>  	NULL,
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 2619d94c308d4..8623caa673889 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -38,8 +38,6 @@ struct dax_operations {
>  	int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
>  };
>  
> -extern struct attribute_group dax_attribute_group;
> -
>  #if IS_ENABLED(CONFIG_DAX)
>  struct dax_device *alloc_dax(void *private, const char *host,
>  		const struct dax_operations *ops, unsigned long flags);
> -- 
> 2.30.2
> 
> 

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: fix a dax/block device attribute registration regression
  2021-09-22 18:33 fix a dax/block device attribute registration regression Christoph Hellwig
                   ` (2 preceding siblings ...)
  2021-09-22 18:33 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
@ 2021-09-27 18:19 ` Dan Williams
  3 siblings, 0 replies; 11+ messages in thread
From: Dan Williams @ 2021-09-27 18:19 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Jens Axboe, Vishal Verma, Dave Jiang, Ira Weiny, linux-block,
	Linux NVDIMM

On Wed, Sep 22, 2021 at 11:34 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Hi Dan and Jens,
>
> this series fixed a regression in how the dax/write_cache attribute of the
> pmem devices was registere.  It does so by both fixing the API abuse in the
> driver and (temporarily) the behavior change in the block layer that made
> this API abuse not work anymore.

I took patch1 into for-5.15/libnvdimm, patch2 into for-5.16/libnvdimm,
and I'll leave patch3 for Jens.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-22 17:34 dax_supported() related cleanups v2 Christoph Hellwig
@ 2021-09-22 17:34 ` Christoph Hellwig
  0 siblings, 0 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-22 17:34 UTC (permalink / raw)
  To: Dan Williams, Vishal Verma, Dave Jiang
  Cc: Mike Snitzer, Matthew Wilcox, linux-xfs, nvdimm, linux-fsdevel,
	linux-ext4, Ira Weiny

The proper API is to pass the groups to device_add_disk, but the code
used to also allow groups being set before calling *add_disk.  Warn
about that but keep the group pointer intact for now so that it can
be removed again after a grace period.

Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
---
 block/genhd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 7b6e5e1cf9564..409cf608cc5bd 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -439,7 +439,8 @@ int device_add_disk(struct device *parent, struct gendisk *disk,
 	dev_set_uevent_suppress(ddev, 1);
 
 	ddev->parent = parent;
-	ddev->groups = groups;
+	if (!WARN_ON_ONCE(ddev->groups))
+		ddev->groups = groups;
 	dev_set_name(ddev, "%s", disk->disk_name);
 	if (!(disk->flags & GENHD_FL_HIDDEN))
 		ddev->devt = MKDEV(disk->major, disk->first_minor);
-- 
2.30.2


^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-20 23:50   ` Dan Williams
@ 2021-09-21  6:32     ` Christoph Hellwig
  0 siblings, 0 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-21  6:32 UTC (permalink / raw)
  To: Dan Williams
  Cc: Christoph Hellwig, Jens Axboe, Vishal Verma, Dave Jiang,
	Ira Weiny, linux-block, Linux NVDIMM

On Mon, Sep 20, 2021 at 04:50:03PM -0700, Dan Williams wrote:
> >
> >         ddev->parent = parent;
> > -       ddev->groups = groups;
> > +       if (!WARN_ON_ONCE(ddev->groups))
> > +               ddev->groups = groups;
> 
> That feels too compact to me, and dev_WARN_ONCE() might save someone a
> git blame to look up the reason for the warning:
> 
>     dev_WARN_ONCE(parent, ddev->groups, "unexpected pre-populated
> attribute group\n");
>     if (!ddev->groups)
>         ddev->groups = groups;
> 
> ...but not a deal breaker. Either way you can add:
> 

I'd rather keep it simple and optmize for the normal case..

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-20  7:27 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
  2021-09-20 22:52   ` Ira Weiny
@ 2021-09-20 23:50   ` Dan Williams
  2021-09-21  6:32     ` Christoph Hellwig
  1 sibling, 1 reply; 11+ messages in thread
From: Dan Williams @ 2021-09-20 23:50 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Jens Axboe, Vishal Verma, Dave Jiang, Ira Weiny, linux-block,
	Linux NVDIMM

On Mon, Sep 20, 2021 at 12:30 AM Christoph Hellwig <hch@lst.de> wrote:
>
> The proper API is to pass the groups to device_add_disk, but the code
> used to also allow groups being set before calling *add_disk.  Warn
> about that but keep the group pointer intact for now so that it can
> be removed again after a grace period.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")
> ---
>  block/genhd.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/block/genhd.c b/block/genhd.c
> index 7b6e5e1cf9564..409cf608cc5bd 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -439,7 +439,8 @@ int device_add_disk(struct device *parent, struct gendisk *disk,
>         dev_set_uevent_suppress(ddev, 1);
>
>         ddev->parent = parent;
> -       ddev->groups = groups;
> +       if (!WARN_ON_ONCE(ddev->groups))
> +               ddev->groups = groups;

That feels too compact to me, and dev_WARN_ONCE() might save someone a
git blame to look up the reason for the warning:

    dev_WARN_ONCE(parent, ddev->groups, "unexpected pre-populated
attribute group\n");
    if (!ddev->groups)
        ddev->groups = groups;

...but not a deal breaker. Either way you can add:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>

Jens, I'm ok for the final spin of this series to go through block.git
since the referenced commits in Fixes: went that route, just let me
know if you want me to take them.

^ permalink raw reply	[flat|nested] 11+ messages in thread

* Re: [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-20  7:27 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
@ 2021-09-20 22:52   ` Ira Weiny
  2021-09-20 23:50   ` Dan Williams
  1 sibling, 0 replies; 11+ messages in thread
From: Ira Weiny @ 2021-09-20 22:52 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: Dan Williams, Jens Axboe, Vishal Verma, Dave Jiang, linux-block, nvdimm

On Mon, Sep 20, 2021 at 09:27:26AM +0200, Christoph Hellwig wrote:
> The proper API is to pass the groups to device_add_disk, but the code
> used to also allow groups being set before calling *add_disk.  Warn
> about that but keep the group pointer intact for now so that it can
> be removed again after a grace period.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> ---
>  block/genhd.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/block/genhd.c b/block/genhd.c
> index 7b6e5e1cf9564..409cf608cc5bd 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -439,7 +439,8 @@ int device_add_disk(struct device *parent, struct gendisk *disk,
>  	dev_set_uevent_suppress(ddev, 1);
>  
>  	ddev->parent = parent;
> -	ddev->groups = groups;
> +	if (!WARN_ON_ONCE(ddev->groups))
> +		ddev->groups = groups;
>  	dev_set_name(ddev, "%s", disk->disk_name);
>  	if (!(disk->flags & GENHD_FL_HIDDEN))
>  		ddev->devt = MKDEV(disk->major, disk->first_minor);
> -- 
> 2.30.2
> 

^ permalink raw reply	[flat|nested] 11+ messages in thread

* [PATCH 3/3] block: warn if ->groups is set when calling add_disk
  2021-09-20  7:27 fix a dax/block device attribute registration regression Christoph Hellwig
@ 2021-09-20  7:27 ` Christoph Hellwig
  2021-09-20 22:52   ` Ira Weiny
  2021-09-20 23:50   ` Dan Williams
  0 siblings, 2 replies; 11+ messages in thread
From: Christoph Hellwig @ 2021-09-20  7:27 UTC (permalink / raw)
  To: Dan Williams, Jens Axboe
  Cc: Vishal Verma, Dave Jiang, Ira Weiny, linux-block, nvdimm

The proper API is to pass the groups to device_add_disk, but the code
used to also allow groups being set before calling *add_disk.  Warn
about that but keep the group pointer intact for now so that it can
be removed again after a grace period.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: 52b85909f85d ("block: fold register_disk into device_add_disk")
---
 block/genhd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/genhd.c b/block/genhd.c
index 7b6e5e1cf9564..409cf608cc5bd 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -439,7 +439,8 @@ int device_add_disk(struct device *parent, struct gendisk *disk,
 	dev_set_uevent_suppress(ddev, 1);
 
 	ddev->parent = parent;
-	ddev->groups = groups;
+	if (!WARN_ON_ONCE(ddev->groups))
+		ddev->groups = groups;
 	dev_set_name(ddev, "%s", disk->disk_name);
 	if (!(disk->flags & GENHD_FL_HIDDEN))
 		ddev->devt = MKDEV(disk->major, disk->first_minor);
-- 
2.30.2


^ permalink raw reply	[flat|nested] 11+ messages in thread

end of thread, other threads:[~2021-09-27 18:19 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-22 18:33 fix a dax/block device attribute registration regression Christoph Hellwig
2021-09-22 18:33 ` [PATCH 1/3] nvdimm/pmem: fix creating the dax group Christoph Hellwig
2021-09-22 18:33 ` [PATCH 2/3] nvdimm/pmem: move dax_attribute_group from dax to pmem Christoph Hellwig
2021-09-22 21:40   ` Ira Weiny
2021-09-22 18:33 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
2021-09-27 18:19 ` fix a dax/block device attribute registration regression Dan Williams
  -- strict thread matches above, loose matches on Subject: below --
2021-09-22 17:34 dax_supported() related cleanups v2 Christoph Hellwig
2021-09-22 17:34 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
2021-09-20  7:27 fix a dax/block device attribute registration regression Christoph Hellwig
2021-09-20  7:27 ` [PATCH 3/3] block: warn if ->groups is set when calling add_disk Christoph Hellwig
2021-09-20 22:52   ` Ira Weiny
2021-09-20 23:50   ` Dan Williams
2021-09-21  6:32     ` Christoph Hellwig

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