[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 <mathieu.desnoy...@efficios.com>
Reviewed-by: Dan Williams <dan.j.willi...@intel.com>
Cc: Alasdair Kergon <a...@redhat.com>
Cc: Mike Snitzer <snit...@kernel.org>
Cc: Mikulas Patocka <mpato...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Vishal Verma <vishal.l.ve...@intel.com>
Cc: Dave Jiang <dave.ji...@intel.com>
Cc: Matthew Wilcox <wi...@infradead.org>
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Russell King <li...@armlinux.org.uk>
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, &dcssblk_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, &dcssblk_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