dm: treat alloc_dax() -EOPNOTSUPP failure as non-fatal

In preparation for checking whether the architecture has data cache
aliasing within alloc_dax(), modify the error handling of dm alloc_dev()
to treat alloc_dax() -EOPNOTSUPP failure as non-fatal.

Link: https://lkml.kernel.org/r/20240215144633.96437-5-mathieu.desnoyers@efficios.com
Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Michael Sclafani <dm-devel@lists.linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 8dcabf84d866e6d2ac863a98790b16b838475d23..10c73af93d00cc044d58834df822e7571479c341 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2054,6 +2054,7 @@ static void cleanup_mapped_device(struct mapped_device *md)
 static struct mapped_device *alloc_dev(int minor)
 {
        int r, numa_node_id = dm_get_numa_node();
+       struct dax_device *dax_dev;
        struct mapped_device *md;
        void *old_md;
 
@@ -2122,15 +2123,15 @@ static struct mapped_device *alloc_dev(int minor)
        md->disk->private_data = md;
        sprintf(md->disk->disk_name, "dm-%d", minor);
 
-       if (IS_ENABLED(CONFIG_FS_DAX)) {
-               md->dax_dev = alloc_dax(md, &dm_dax_ops);
-               if (IS_ERR(md->dax_dev)) {
-                       md->dax_dev = NULL;
+       dax_dev = alloc_dax(md, &dm_dax_ops);
+       if (IS_ERR(dax_dev)) {
+               if (PTR_ERR(dax_dev) != -EOPNOTSUPP)
                        goto bad;
-               }
-               set_dax_nocache(md->dax_dev);
-               set_dax_nomc(md->dax_dev);
-               if (dax_add_host(md->dax_dev, md->disk))
+       } else {
+               set_dax_nocache(dax_dev);
+               set_dax_nomc(dax_dev);
+               md->dax_dev = dax_dev;
+               if (dax_add_host(dax_dev, md->disk))
                        goto bad;
        }