dm-log-writes: add a log_writes_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/20211129102203.2243509-11-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 3155875..cdb22e7 100644 (file)
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -947,17 +947,21 @@ static int log_dax(struct log_writes_c *lc, sector_t sector, size_t bytes,
        return 0;
 }
 
+static struct dax_device *log_writes_dax_pgoff(struct dm_target *ti,
+               pgoff_t *pgoff)
+{
+       struct log_writes_c *lc = ti->private;
+
+       *pgoff += (get_start_sect(lc->dev->bdev) >> PAGE_SECTORS_SHIFT);
+       return lc->dev->dax_dev;
+}
+
 static long log_writes_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
                                         long nr_pages, void **kaddr, pfn_t *pfn)
 {
-       struct log_writes_c *lc = ti->private;
-       sector_t sector = pgoff * PAGE_SECTORS;
-       int ret;
+       struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
-       ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages * PAGE_SIZE, &pgoff);
-       if (ret)
-               return ret;
-       return dax_direct_access(lc->dev->dax_dev, pgoff, nr_pages, kaddr, pfn);
+       return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
 }
 
 static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
@@ -966,11 +970,9 @@ static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
 {
        struct log_writes_c *lc = ti->private;
        sector_t sector = pgoff * PAGE_SECTORS;
+       struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
        int err;
 
-       if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-               return 0;
-
        /* Don't bother doing anything if logging has been disabled */
        if (!lc->logging_enabled)
                goto dax_copy;
@@ -981,34 +983,24 @@ static size_t log_writes_dax_copy_from_iter(struct dm_target *ti,
                return 0;
        }
 dax_copy:
-       return dax_copy_from_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
 static size_t log_writes_dax_copy_to_iter(struct dm_target *ti,
                                          pgoff_t pgoff, void *addr, size_t bytes,
                                          struct iov_iter *i)
 {
-       struct log_writes_c *lc = ti->private;
-       sector_t sector = pgoff * PAGE_SECTORS;
+       struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
-       if (bdev_dax_pgoff(lc->dev->bdev, sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
-               return 0;
-       return dax_copy_to_iter(lc->dev->dax_dev, pgoff, addr, bytes, i);
+       return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
 }
 
 static int log_writes_dax_zero_page_range(struct dm_target *ti, pgoff_t pgoff,
                                          size_t nr_pages)
 {
-       int ret;
-       struct log_writes_c *lc = ti->private;
-       sector_t sector = pgoff * PAGE_SECTORS;
+       struct dax_device *dax_dev = log_writes_dax_pgoff(ti, &pgoff);
 
-       ret = bdev_dax_pgoff(lc->dev->bdev, sector, nr_pages << PAGE_SHIFT,
-                            &pgoff);
-       if (ret)
-               return ret;
-       return dax_zero_page_range(lc->dev->dax_dev, pgoff,
-                                  nr_pages << PAGE_SHIFT);
+       return dax_zero_page_range(dax_dev, pgoff, nr_pages << PAGE_SHIFT);
 }
 
 #else