dcssblk: add dax_operations support

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

Reported-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/s390/block/Kconfig b/drivers/s390/block/Kconfig
index 4a3b6232618323e390a36ee5896f5368932fb597..0acb8c2f947514f278f5b47194bdc79d4fcc4cc8 100644 (file)
--- a/drivers/s390/block/Kconfig
+++ b/drivers/s390/block/Kconfig
@@ -14,6 +14,7 @@ config BLK_DEV_XPRAM
 
 config DCSSBLK
        def_tristate m
+       select DAX
        prompt "DCSSBLK support"
        depends on S390 && BLOCK
        help

diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index 415d10a67b7a749366f6624d871e2c358d7fcea1..dc84cfd4e43829df783afe9e3c77d6f443aeb7ae 100644 (file)
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/pfn_t.h>
+#include <linux/dax.h>
 #include <asm/extmem.h>
 #include <asm/io.h>
 
@@ -30,8 +31,10 @@ static int dcssblk_open(struct block_device *bdev, fmode_t mode);
 static void dcssblk_release(struct gendisk *disk, fmode_t mode);
 static blk_qc_t dcssblk_make_request(struct request_queue *q,
                                                struct bio *bio);
-static long dcssblk_direct_access(struct block_device *bdev, sector_t secnum,
+static long dcssblk_blk_direct_access(struct block_device *bdev, sector_t secnum,
                         void **kaddr, pfn_t *pfn, long size);
+static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+               long nr_pages, void **kaddr, pfn_t *pfn);
 
 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
 
@@ -40,7 +43,11 @@ static const struct block_device_operations dcssblk_devops = {
        .owner          = THIS_MODULE,
        .open           = dcssblk_open,
        .release        = dcssblk_release,
-       .direct_access  = dcssblk_direct_access,
+       .direct_access  = dcssblk_blk_direct_access,
+};
+
+static const struct dax_operations dcssblk_dax_ops = {
+       .direct_access = dcssblk_dax_direct_access,
 };
 
 struct dcssblk_dev_info {
@@ -57,6 +64,7 @@ struct dcssblk_dev_info {
        struct request_queue *dcssblk_queue;
        int num_of_segments;
        struct list_head seg_list;
+       struct dax_device *dax_dev;
 };
 
 struct segment_info {
@@ -389,6 +397,8 @@ removeseg:
        }
        list_del(&dev_info->lh);
 
+       kill_dax(dev_info->dax_dev);
+       put_dax(dev_info->dax_dev);
        del_gendisk(dev_info->gd);
        blk_cleanup_queue(dev_info->dcssblk_queue);
        dev_info->gd->queue = NULL;
@@ -654,6 +664,13 @@ 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, dev_info->gd->disk_name,
+                       &dcssblk_dax_ops);
+       if (!dev_info->dax_dev) {
+               rc = -ENOMEM;
+               goto put_dev;
+       }
+
        get_device(&dev_info->dev);
        device_add_disk(&dev_info->dev, dev_info->gd);
 
@@ -752,6 +769,8 @@ dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const ch
        }
 
        list_del(&dev_info->lh);
+       kill_dax(dev_info->dax_dev);
+       put_dax(dev_info->dax_dev);
        del_gendisk(dev_info->gd);
        blk_cleanup_queue(dev_info->dcssblk_queue);
        dev_info->gd->queue = NULL;
@@ -883,21 +902,39 @@ fail:
 }
 
 static long
-dcssblk_direct_access (struct block_device *bdev, sector_t secnum,
+__dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
+               long nr_pages, void **kaddr, pfn_t *pfn)
+{
+       resource_size_t offset = pgoff * PAGE_SIZE;
+       unsigned long dev_sz;
+
+       dev_sz = dev_info->end - dev_info->start + 1;
+       *kaddr = (void *) dev_info->start + offset;
+       *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
+
+       return (dev_sz - offset) / PAGE_SIZE;
+}
+
+static long
+dcssblk_blk_direct_access(struct block_device *bdev, sector_t secnum,
                        void **kaddr, pfn_t *pfn, long size)
 {
        struct dcssblk_dev_info *dev_info;
-       unsigned long offset, dev_sz;
 
        dev_info = bdev->bd_disk->private_data;
        if (!dev_info)
                return -ENODEV;
-       dev_sz = dev_info->end - dev_info->start + 1;
-       offset = secnum * 512;
-       *kaddr = (void *) dev_info->start + offset;
-       *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset), PFN_DEV);
+       return __dcssblk_direct_access(dev_info, PHYS_PFN(secnum * 512),
+                       PHYS_PFN(size), kaddr, pfn) * PAGE_SIZE;
+}
+
+static long
+dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+               long nr_pages, void **kaddr, pfn_t *pfn)
+{
+       struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
 
-       return dev_sz - offset;
+       return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
 }
 
 static void