[PATCH 10/33] iomap: add an iomap-based bmap implementation

[Christoph Hellwig <hch@xxxxxx>]

This adds a simple iomap-based implementation of the legacy ->bmap
interface.  Note that we can't easily add checks for rt or reflink
files, so these will have to remain in the callers.  This interface
just needs to die..

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/iomap.c            | 29 +++++++++++++++++++++++++++++
 include/linux/iomap.h |  3 +++
 2 files changed, 32 insertions(+)

diff --git a/fs/iomap.c b/fs/iomap.c
index af525cb47339..049e0c4aacac 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1201,3 +1201,32 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(iomap_dio_rw);
+
+static loff_t
+iomap_bmap_actor(struct inode *inode, loff_t pos, loff_t length,
+		void *data, struct iomap *iomap)
+{
+	sector_t *bno = data;
+
+	if (iomap->type == IOMAP_MAPPED)
+		*bno = (iomap->addr + pos - iomap->offset) >> inode->i_blkbits;
+	return 0;
+}
+
+/* legacy ->bmap interface.  0 is the error return (!) */
+sector_t
+iomap_bmap(struct address_space *mapping, sector_t bno,
+		const struct iomap_ops *ops)
+{
+	struct inode *inode = mapping->host;
+	loff_t pos = bno >> inode->i_blkbits;
+	unsigned blocksize = i_blocksize(inode);
+
+	if (filemap_write_and_wait(mapping))
+		return 0;
+
+	bno = 0;
+	iomap_apply(inode, pos, blocksize, 0, ops, &bno, iomap_bmap_actor);
+	return bno;
+}
+EXPORT_SYMBOL_GPL(iomap_bmap);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 19a07de28212..07f73224c38b 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -4,6 +4,7 @@
 
 #include <linux/types.h>
 
+struct address_space;
 struct fiemap_extent_info;
 struct inode;
 struct iov_iter;
@@ -95,6 +96,8 @@ loff_t iomap_seek_hole(struct inode *inode, loff_t offset,
 		const struct iomap_ops *ops);
 loff_t iomap_seek_data(struct inode *inode, loff_t offset,
 		const struct iomap_ops *ops);
+sector_t iomap_bmap(struct address_space *mapping, sector_t bno,
+		const struct iomap_ops *ops);
 
 /*
  * Flags for direct I/O ->end_io:
-- 
2.17.0