dax: Move mandatory ->zero_page_range() check in alloc_dax()
zero_page_range() dax operation is mandatory for dax devices. Right now
that check happens in dax_zero_page_range() function. Dan thinks that's
too late and its better to do the check earlier in alloc_dax().
I also modified alloc_dax() to return pointer with error code in it in
case of failure. Right now it returns NULL and caller assumes failure
happened due to -ENOMEM. But with this ->zero_page_range() check, I
need to return -EINVAL instead.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Link: https://lore.kernel.org/r/20200401161125.GB9398@redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/dax/bus.c b/drivers/dax/bus.c
index 46e4604..df238c8 100644
--- a/drivers/dax/bus.c
+++ b/drivers/dax/bus.c
@@ -421,8 +421,10 @@ struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
* device outside of mmap of the resulting character device.
*/
dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
- if (!dax_dev)
+ if (IS_ERR(dax_dev)) {
+ rc = PTR_ERR(dax_dev);
goto err;
+ }
/* a device_dax instance is dead while the driver is not attached */
kill_dax(dax_dev);
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e498daf..8e32345 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -349,9 +349,6 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
{
if (!dax_alive(dax_dev))
return -ENXIO;
-
- if (!dax_dev->ops->zero_page_range)
- return -EOPNOTSUPP;
/*
* There are no callers that want to zero more than one page as of now.
* Once users are there, this check can be removed after the
@@ -571,9 +568,16 @@ struct dax_device *alloc_dax(void *private, const char *__host,
dev_t devt;
int minor;
+ if (ops && !ops->zero_page_range) {
+ pr_debug("%s: error: device does not provide dax"
+ " operation zero_page_range()\n",
+ __host ? __host : "Unknown");
+ return ERR_PTR(-EINVAL);
+ }
+
host = kstrdup(__host, GFP_KERNEL);
if (__host && !host)
- return NULL;
+ return ERR_PTR(-ENOMEM);
minor = ida_simple_get(&dax_minor_ida, 0, MINORMASK+1, GFP_KERNEL);
if (minor < 0)
@@ -596,7 +600,7 @@ struct dax_device *alloc_dax(void *private, const char *__host,
ida_simple_remove(&dax_minor_ida, minor);
err_minor:
kfree(host);
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL_GPL(alloc_dax);