Mathieu Desnoyers wrote:
> In preparation for checking whether the architecture has data cache
> aliasing within alloc_dax(), modify the error handling of nvdimm/pmem
> pmem_attach_disk() to treat alloc_dax() -EOPNOTSUPP failure as non-fatal.
>
> For the transition, consider that alloc_dax() returning NULL is the
> same as returning -EOPNOTSUPP.
>
> Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Cc: Alasdair Kergon <agk@xxxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
> Cc: Mikulas Patocka <mpatocka@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
> Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxx>
> Cc: linux-arch@xxxxxxxxxxxxxxx
> Cc: linux-cxl@xxxxxxxxxxxxxxx
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-xfs@xxxxxxxxxxxxxxx
> Cc: dm-devel@xxxxxxxxxxxxxxx
> Cc: nvdimm@xxxxxxxxxxxxxxx
> ---
> drivers/nvdimm/pmem.c | 26 ++++++++++++++------------
> 1 file changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
> index 9fe358090720..f1d9f5c6dbac 100644
> --- a/drivers/nvdimm/pmem.c
> +++ b/drivers/nvdimm/pmem.c
> @@ -558,19 +558,21 @@ static int pmem_attach_disk(struct device *dev,
> disk->bb = &pmem->bb;
>
> dax_dev = alloc_dax(pmem, &pmem_dax_ops);
> - if (IS_ERR(dax_dev)) {
> - rc = PTR_ERR(dax_dev);
> - goto out;
> + if (IS_ERR_OR_NULL(dax_dev)) {
alloc_dax() should never return NULL. I.e. the lead in before this patch
should fix this misunderstanding:
diff --git a/include/linux/dax.h b/include/linux/dax.h
index b463502b16e1..df2d52b8a245 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -86,11 +86,7 @@ static inline void *dax_holder(struct dax_device *dax_dev)
static inline struct dax_device *alloc_dax(void *private,
const struct dax_operations *ops)
{
- /*
- * Callers should check IS_ENABLED(CONFIG_DAX) to know if this
- * NULL is an error or expected.
- */
- return NULL;
+ return ERR_PTR(-EOPNOTSUPP);
}
static inline void put_dax(struct dax_device *dax_dev)
{
> + rc = IS_ERR(dax_dev) ? PTR_ERR(dax_dev) : -EOPNOTSUPP;
Then this ternary can be replaced with just a check of which PTR_ERR()
value is being returned.
