dax: add dax_iomap_sector() helper function

To be able to correctly calculate the sector from a file position and a
struct iomap there is a complex little bit of logic that currently happens
in both dax_iomap_actor() and dax_iomap_fault().  This will need to be
repeated yet again in the DAX PMD fault handler when it is added, so break
it out into a helper function.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/dax.c b/fs/dax.c
index fdbd7a1ec6cf621f28bd4a601bdcac0dd4a4a7c2..77379546433ed458c62d694b2f0e625b1013e333 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1030,6 +1030,11 @@ int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
 EXPORT_SYMBOL_GPL(dax_truncate_page);
 
 #ifdef CONFIG_FS_IOMAP
+static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
+{
+       return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
+}
+
 static loff_t
 dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
                struct iomap *iomap)
@@ -1055,8 +1060,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
                struct blk_dax_ctl dax = { 0 };
                ssize_t map_len;
 
-               dax.sector = iomap->blkno +
-                       (((pos & PAGE_MASK) - iomap->offset) >> 9);
+               dax.sector = dax_iomap_sector(iomap, pos);
                dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
                map_len = dax_map_atomic(iomap->bdev, &dax);
                if (map_len < 0) {
@@ -1193,7 +1197,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
                goto unlock_entry;
        }
 
-       sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9);
+       sector = dax_iomap_sector(&iomap, pos);
 
        if (vmf->cow_page) {
                switch (iomap.type) {