dax: check for QUEUE_FLAG_DAX in bdev_dax_supported()

Add an explicit check for QUEUE_FLAG_DAX to __bdev_dax_supported().  This
is needed for DM configurations where the first element in the dm-linear or
dm-stripe target supports DAX, but other elements do not.  Without this
check __bdev_dax_supported() will pass for such devices, letting a
filesystem on that device mount with the DAX option.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Mike Snitzer <snitzer@redhat.com>
Fixes: commit 545ed20e6df6 ("dm: add infrastructure for DAX support")
Cc: stable@vger.kernel.org
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 903d9c4..45276ab 100644 (file)
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -86,6 +86,7 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 {
        struct dax_device *dax_dev;
        bool dax_enabled = false;
+       struct request_queue *q;
        pgoff_t pgoff;
        int err, id;
        void *kaddr;
@@ -99,6 +100,13 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
                return false;
        }
 
+       q = bdev_get_queue(bdev);
+       if (!q || !blk_queue_dax(q)) {
+               pr_debug("%s: error: request queue doesn't support dax\n",
+                               bdevname(bdev, buf));
+               return false;
+       }
+
        err = bdev_dax_pgoff(bdev, 0, PAGE_SIZE, &pgoff);
        if (err) {
                pr_debug("%s: error: unaligned partition for dax\n",