Thread (41 messages) 41 messages, 4 authors, 2016-10-12
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[PATCH v5 12/17] dax: add dax_iomap_sector() helper function

From: Ross Zwisler <hidden>
Date: 2016-10-07 21:08:59
Also in: linux-fsdevel, linux-mm, linux-xfs, lkml, nvdimm
Subsystem: filesystem direct access (dax), filesystems (vfs and infrastructure), the rest · Maintainers: Dan Williams, Alexander Viro, Christian Brauner, Linus Torvalds

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-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 fs/dax.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 982ccbb..7689ab0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1023,6 +1023,11 @@ 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 inline 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)
@@ -1048,8 +1053,7 @@ 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) {
@@ -1186,7 +1190,7 @@ 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) {
-- 
2.7.4
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