dm-linear: add a linear_dax_pgoff helper

Add a helper to perform the entire remapping for DAX accesses.  This
helper open codes bdev_dax_pgoff given that the alignment checks have
already been done by the submitting file system and don't need to be
repeated.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/20211129102203.2243509-10-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 0a260c35aeeede053caa0a5b2295116953d57eda..90de42f6743ac2926778b532a832bbaedb375c09 100644 (file)
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -163,63 +163,44 @@ static int linear_iterate_devices(struct dm_target *ti,
 }
 
 #if IS_ENABLED(CONFIG_FS_DAX)
+static struct dax_device *linear_dax_pgoff(struct dm_target *ti, pgoff_t *pgoff)
+{
+       struct linear_c *lc = ti->private;
+       sector_t sector = linear_map_sector(ti, *pgoff << PAGE_SECTORS_SHIFT);
+
+       *pgoff = (get_start_sect(lc->dev->bdev) + sector) >> PAGE_SECTORS_SHIFT;
+       return lc->dev->dax_dev;
+}
+
 static long linear_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
                long nr_pages, void **kaddr, pfn_t *pfn)
 {
-       long ret;
-       struct linear_c *lc = ti->private;
-       struct block_device *bdev = lc->dev->bdev;
-       struct dax_device *dax_dev = lc->dev->dax_dev;
-       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-       dev_sector = linear_map_sector(ti, sector);
-       ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
-       if (ret)
-               return ret;
+       struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
+
        return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
 }
 
 static size_t linear_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i)
 {
-       struct linear_c *lc = ti->private;
-       struct block_device *bdev = lc->dev->bdev;
-       struct dax_device *dax_dev = lc->dev->dax_dev;
-       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+       struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
-       dev_sector = linear_map_sector(ti, sector);
-       if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-               return 0;
        return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
 static size_t linear_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i)
 {
-       struct linear_c *lc = ti->private;
-       struct block_device *bdev = lc->dev->bdev;
-       struct dax_device *dax_dev = lc->dev->dax_dev;
-       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
+       struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
 
-       dev_sector = linear_map_sector(ti, sector);
-       if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-               return 0;
        return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
 static int linear_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
                                      size_t nr_pages)
 {
-       int ret;
-       struct linear_c *lc = ti->private;
-       struct block_device *bdev = lc->dev->bdev;
-       struct dax_device *dax_dev = lc->dev->dax_dev;
-       sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
-
-       dev_sector = linear_map_sector(ti, sector);
-       ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages << PAGE_SHIFT, &pgoff);
-       if (ret)
-               return ret;
+       struct dax_device *dax_dev = linear_dax_pgoff(ti, &pgoff);
+
        return dax_zero_page_range(dax_dev, pgoff, nr_pages);
 }