[PATCH 09/29] dm-linear: add a linear_dax_pgoff helper

Christoph Hellwig
2021-11-09T08:33:44Z

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>
---
drivers/md/dm-linear.c | 49 +++++++++++++-----------------------------
1 file changed, 15 insertions(+), 34 deletions(-)

diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 0a260c35aeeed..90de42f6743ac 100644
--- 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);
}

--
2.30.2