Re: [PATCH v5 4/8] dcssblk: Handle alloc_dax() -EOPNOTSUPP failure

[Heiko Carstens]

On Mon, Feb 12, 2024 at 11:30:57AM -0500, Mathieu Desnoyers wrote:
> In preparation for checking whether the architecture has data cache
> aliasing within alloc_dax(), modify the error handling of dcssblk
> dcssblk_add_store() to handle alloc_dax() -EOPNOTSUPP failures.
> 
> Considering that s390 is not a data cache aliasing architecture,
> and considering that DCSSBLK selects DAX, a return value of -EOPNOTSUPP
> from alloc_dax() should make dcssblk_add_store() fail.
> 
> Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing 
> caches")
> Signed-off-by: Mathieu Desnoyers 
> Reviewed-by: Dan Williams 
...
> ---
>  drivers/s390/block/dcssblk.c | 11 ++-
>  1 file changed, 6 insertions(+), 5 deletions(-)

Acked-by: Heiko Carstens 

[PATCH v5 4/8] dcssblk: Handle alloc_dax() -EOPNOTSUPP failure

[Mathieu Desnoyers]

In preparation for checking whether the architecture has data cache
aliasing within alloc_dax(), modify the error handling of dcssblk
dcssblk_add_store() to handle alloc_dax() -EOPNOTSUPP failures.

Considering that s390 is not a data cache aliasing architecture,
and considering that DCSSBLK selects DAX, a return value of -EOPNOTSUPP
from alloc_dax() should make dcssblk_add_store() fail.

Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing 
caches")
Signed-off-by: Mathieu Desnoyers 
Reviewed-by: Dan Williams 
Cc: Alasdair Kergon 
Cc: Mike Snitzer 
Cc: Mikulas Patocka 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Dan Williams 
Cc: Vishal Verma 
Cc: Dave Jiang 
Cc: Matthew Wilcox 
Cc: Arnd Bergmann 
Cc: Russell King 
Cc: linux-a...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux-fsde...@vger.kernel.org
Cc: linux...@kvack.org
Cc: linux-...@vger.kernel.org
Cc: dm-devel@lists.linux.dev
Cc: nvd...@lists.linux.dev
Cc: linux-s...@vger.kernel.org
---
 drivers/s390/block/dcssblk.c | 11 ++-
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 4b7ecd4fd431..f363c1d51d9a 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -549,6 +549,7 @@ dcssblk_add_store(struct device *dev, struct 
device_attribute *attr, const char
int rc, i, j, num_of_segments;
struct dcssblk_dev_info *dev_info;
struct segment_info *seg_info, *temp;
+   struct dax_device *dax_dev;
char *local_buf;
unsigned long seg_byte_size;
 
@@ -677,13 +678,13 @@ dcssblk_add_store(struct device *dev, struct 
device_attribute *attr, const char
if (rc)
goto put_dev;
 
-   dev_info->dax_dev = alloc_dax(dev_info, _dax_ops);
-   if (IS_ERR(dev_info->dax_dev)) {
-   rc = PTR_ERR(dev_info->dax_dev);
-   dev_info->dax_dev = NULL;
+   dax_dev = alloc_dax(dev_info, _dax_ops);
+   if (IS_ERR(dax_dev)) {
+   rc = PTR_ERR(dax_dev);
goto put_dev;
}
-   set_dax_synchronous(dev_info->dax_dev);
+   set_dax_synchronous(dax_dev);
+   dev_info->dax_dev = dax_dev;
rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
if (rc)
goto out_dax;
-- 
2.39.2