[PATCH] iomap: turn iomap_want_unshare_iter into an inline function

[Christoph Hellwig <hch@lst.de>]

iomap_want_unshare_iter currently sits in fs/iomap/buffered-io.c, which
depends on CONFIG_BLOCK.  It is also in used in fs/dax.c whіch has no
such dependency.  Given that it is a trivial check turn it into an inline
in include/linux/iomap.h to fix the DAX && !BLOCK build.

Fixes: 6ef6a0e821d3 ("iomap: share iomap_unshare_iter predicate code with fsdax")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap/buffered-io.c | 17 -----------------
 include/linux/iomap.h  | 19 +++++++++++++++++++
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 604f786be4bc54..ef0b68bccbb612 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1270,23 +1270,6 @@ void iomap_write_delalloc_release(struct inode *inode, loff_t start_byte,
 }
 EXPORT_SYMBOL_GPL(iomap_write_delalloc_release);
 
-bool iomap_want_unshare_iter(const struct iomap_iter *iter)
-{
-	/*
-	 * Don't bother with blocks that are not shared to start with; or
-	 * mappings that cannot be shared, such as inline data, delalloc
-	 * reservations, holes or unwritten extents.
-	 *
-	 * Note that we use srcmap directly instead of iomap_iter_srcmap as
-	 * unsharing requires providing a separate source map, and the presence
-	 * of one is a good indicator that unsharing is needed, unlike
-	 * IOMAP_F_SHARED which can be set for any data that goes into the COW
-	 * fork for XFS.
-	 */
-	return (iter->iomap.flags & IOMAP_F_SHARED) &&
-		iter->srcmap.type == IOMAP_MAPPED;
-}
-
 static loff_t iomap_unshare_iter(struct iomap_iter *iter)
 {
 	struct iomap *iomap = &iter->iomap;
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index e04c060e8fe185..664c5f2f0aaa2d 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -270,6 +270,25 @@ static inline loff_t iomap_last_written_block(struct inode *inode, loff_t pos,
 	return round_up(pos + written, i_blocksize(inode));
 }
 
+/*
+ * Check if the range needs to be unshared for a FALLOC_FL_UNSHARE_RANGE
+ * operation.
+ *
+ * Don't bother with blocks that are not shared to start with; or mappings that
+ * cannot be shared, such as inline data, delalloc reservations, holes or
+ * unwritten extents.
+ *
+ * Note that we use srcmap directly instead of iomap_iter_srcmap as unsharing
+ * requires providing a separate source map, and the presence of one is a good
+ * indicator that unsharing is needed, unlike IOMAP_F_SHARED which can be set
+ * for any data that goes into the COW fork for XFS.
+ */
+static inline bool iomap_want_unshare_iter(const struct iomap_iter *iter)
+{
+	return (iter->iomap.flags & IOMAP_F_SHARED) &&
+		iter->srcmap.type == IOMAP_MAPPED;
+}
+
 ssize_t iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *from,
 		const struct iomap_ops *ops, void *private);
 int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops);
-- 
2.45.2