brd: add dax_operations support

Setup a dax_inode to have the same lifetime as the brd block device and
add a ->direct_access() method that is equivalent to
brd_direct_access(). Once fs/dax.c has been converted to use
dax_operations the old brd_direct_access() will be removed.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index f744de7..e66956f 100644 (file)
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -339,6 +339,7 @@ config BLK_DEV_SX8
 
 config BLK_DEV_RAM
        tristate "RAM block device support"
+       select DAX if BLK_DEV_RAM_DAX
        ---help---
          Saying Y here will allow you to use a portion of your RAM memory as
          a block device, so that you can make file systems on it, read and

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index 3adc32a..60f3193 100644 (file)
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #ifdef CONFIG_BLK_DEV_RAM_DAX
 #include <linux/pfn_t.h>
+#include <linux/dax.h>
 #endif
 
 #include <linux/uaccess.h>
@@ -41,6 +42,9 @@ struct brd_device {
 
        struct request_queue    *brd_queue;
        struct gendisk          *brd_disk;
+#ifdef CONFIG_BLK_DEV_RAM_DAX
+       struct dax_device       *dax_dev;
+#endif
        struct list_head        brd_list;
 
        /*
@@ -375,30 +379,53 @@ static int brd_rw_page(struct block_device *bdev, sector_t sector,
 }
 
 #ifdef CONFIG_BLK_DEV_RAM_DAX
-static long brd_direct_access(struct block_device *bdev, sector_t sector,
-                       void **kaddr, pfn_t *pfn, long size)
+static long __brd_direct_access(struct brd_device *brd, pgoff_t pgoff,
+               long nr_pages, void **kaddr, pfn_t *pfn)
 {
-       struct brd_device *brd = bdev->bd_disk->private_data;
        struct page *page;
 
        if (!brd)
                return -ENODEV;
-       page = brd_insert_page(brd, sector);
+       page = brd_insert_page(brd, PFN_PHYS(pgoff) / 512);
        if (!page)
                return -ENOSPC;
        *kaddr = page_address(page);
        *pfn = page_to_pfn_t(page);
 
-       return PAGE_SIZE;
+       return 1;
+}
+
+static long brd_blk_direct_access(struct block_device *bdev, sector_t sector,
+                       void **kaddr, pfn_t *pfn, long size)
+{
+       struct brd_device *brd = bdev->bd_disk->private_data;
+       long nr_pages = __brd_direct_access(brd, PHYS_PFN(sector * 512),
+                       PHYS_PFN(size), kaddr, pfn);
+
+       if (nr_pages < 0)
+               return nr_pages;
+       return nr_pages * PAGE_SIZE;
+}
+
+static long brd_dax_direct_access(struct dax_device *dax_dev,
+               pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
+{
+       struct brd_device *brd = dax_get_private(dax_dev);
+
+       return __brd_direct_access(brd, pgoff, nr_pages, kaddr, pfn);
 }
+
+static const struct dax_operations brd_dax_ops = {
+       .direct_access = brd_dax_direct_access,
+};
 #else
-#define brd_direct_access NULL
+#define brd_blk_direct_access NULL
 #endif
 
 static const struct block_device_operations brd_fops = {
        .owner =                THIS_MODULE,
        .rw_page =              brd_rw_page,
-       .direct_access =        brd_direct_access,
+       .direct_access =        brd_blk_direct_access,
 };
 
 /*
@@ -441,7 +468,9 @@ static struct brd_device *brd_alloc(int i)
 {
        struct brd_device *brd;
        struct gendisk *disk;
-
+#ifdef CONFIG_BLK_DEV_RAM_DAX
+       struct dax_device *dax_dev;
+#endif
        brd = kzalloc(sizeof(*brd), GFP_KERNEL);
        if (!brd)
                goto out;
@@ -469,9 +498,6 @@ static struct brd_device *brd_alloc(int i)
        blk_queue_max_discard_sectors(brd->brd_queue, UINT_MAX);
        brd->brd_queue->limits.discard_zeroes_data = 1;
        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, brd->brd_queue);
-#ifdef CONFIG_BLK_DEV_RAM_DAX
-       queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue);
-#endif
        disk = brd->brd_disk = alloc_disk(max_part);
        if (!disk)
                goto out_free_queue;
@@ -484,8 +510,21 @@ static struct brd_device *brd_alloc(int i)
        sprintf(disk->disk_name, "ram%d", i);
        set_capacity(disk, rd_size * 2);
 
+#ifdef CONFIG_BLK_DEV_RAM_DAX
+       queue_flag_set_unlocked(QUEUE_FLAG_DAX, brd->brd_queue);
+       dax_dev = alloc_dax(brd, disk->disk_name, &brd_dax_ops);
+       if (!dax_dev)
+               goto out_free_inode;
+#endif
+
+
        return brd;
 
+#ifdef CONFIG_BLK_DEV_RAM_DAX
+out_free_inode:
+       kill_dax(dax_dev);
+       put_dax(dax_dev);
+#endif
 out_free_queue:
        blk_cleanup_queue(brd->brd_queue);
 out_free_dev:
@@ -525,6 +564,10 @@ out:
 static void brd_del_one(struct brd_device *brd)
 {
        list_del(&brd->brd_list);
+#ifdef CONFIG_BLK_DEV_RAM_DAX
+       kill_dax(brd->dax_dev);
+       put_dax(brd->dax_dev);
+#endif
        del_gendisk(brd->brd_disk);
        brd_free(brd);
 }