1 files changed, 57 insertions, 31 deletions

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index bbd57ca0634a..3a7b0a0bf469 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -73,22 +73,12 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
 EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
 #endif
 
-/**
- * __bdev_dax_supported() - Check if the device supports dax for filesystem
- * @bdev: block device to check
- * @blocksize: The block size of the device
- *
- * This is a library function for filesystems to check if the block device
- * can be mounted with dax option.
- *
- * Return: true if supported, false if unsupported
- */
-bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
+bool __generic_fsdax_supported(struct dax_device *dax_dev,
+                struct block_device *bdev, int blocksize, sector_t start,
+                sector_t sectors)
 {
-        struct dax_device *dax_dev;
         bool dax_enabled = false;
         pgoff_t pgoff, pgoff_end;
-        struct request_queue *q;
         char buf[BDEVNAME_SIZE];
         void *kaddr, *end_kaddr;
         pfn_t pfn, end_pfn;
@@ -102,21 +92,14 @@ 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);
+        err = bdev_dax_pgoff(bdev, start, PAGE_SIZE, &pgoff);
         if (err) {
                 pr_debug("%s: error: unaligned partition for dax\n",
                                 bdevname(bdev, buf));
                 return false;
         }
 
-        last_page = PFN_DOWN(i_size_read(bdev->bd_inode) - 1) * 8;
+        last_page = PFN_DOWN((start + sectors - 1) * 512) * PAGE_SIZE / 512;
         err = bdev_dax_pgoff(bdev, last_page, PAGE_SIZE, &pgoff_end);
         if (err) {
                 pr_debug("%s: error: unaligned partition for dax\n",
@@ -124,20 +107,11 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
                 return false;
         }
 
-        dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
-        if (!dax_dev) {
-                pr_debug("%s: error: device does not support dax\n",
-                                bdevname(bdev, buf));
-                return false;
-        }
-
         id = dax_read_lock();
         len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
         len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
         dax_read_unlock(id);
 
-        put_dax(dax_dev);
-
         if (len < 1 || len2 < 1) {
                 pr_debug("%s: error: dax access failed (%ld)\n",
                                 bdevname(bdev, buf), len < 1 ? len : len2);
@@ -178,6 +152,49 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
         }
         return true;
 }
+EXPORT_SYMBOL_GPL(__generic_fsdax_supported);
+
+/**
+ * __bdev_dax_supported() - Check if the device supports dax for filesystem
+ * @bdev: block device to check
+ * @blocksize: The block size of the device
+ *
+ * This is a library function for filesystems to check if the block device
+ * can be mounted with dax option.
+ *
+ * Return: true if supported, false if unsupported
+ */
+bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
+{
+        struct dax_device *dax_dev;
+        struct request_queue *q;
+        char buf[BDEVNAME_SIZE];
+        bool ret;
+        int id;
+
+        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;
+        }
+
+        dax_dev = dax_get_by_host(bdev->bd_disk->disk_name);
+        if (!dax_dev) {
+                pr_debug("%s: error: device does not support dax\n",
+                                bdevname(bdev, buf));
+                return false;
+        }
+
+        id = dax_read_lock();
+        ret = dax_supported(dax_dev, bdev, blocksize, 0,
+                        i_size_read(bdev->bd_inode) / 512);
+        dax_read_unlock(id);
+
+        put_dax(dax_dev);
+
+        return ret;
+}
 EXPORT_SYMBOL_GPL(__bdev_dax_supported);
 #endif
 
@@ -303,6 +320,15 @@ long dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, long nr_pages,
 }
 EXPORT_SYMBOL_GPL(dax_direct_access);
 
+bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
+                int blocksize, sector_t start, sector_t len)
+{
+        if (!dax_alive(dax_dev))
+                return false;
+
+        return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
+}
+
 size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
                 size_t bytes, struct iov_iter *i)
 {