[PATCH 10/12] mm/filemap: add filemap_fdatawrite_range_kick() helper

[Jens Axboe <axboe@kernel.dk>]

Works like filemap_fdatawrite_range(), except it's a non-integrity data
writeback and hence only starts writeback on the specified range. Will
help facilitate generically starting uncached writeback from
generic_write_sync(), as header dependencies preclude doing this inline
from fs.h.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 include/linux/fs.h |  2 ++
 mm/filemap.c       | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6a838b5479a6..653b5efa3d3f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2878,6 +2878,8 @@ extern int __must_check file_fdatawait_range(struct file *file, loff_t lstart,
 extern int __must_check file_check_and_advance_wb_err(struct file *file);
 extern int __must_check file_write_and_wait_range(struct file *file,
 						loff_t start, loff_t end);
+int filemap_fdatawrite_range_kick(struct address_space *mapping, loff_t start,
+		loff_t end);
 
 static inline int file_write_and_wait(struct file *file)
 {
diff --git a/mm/filemap.c b/mm/filemap.c
index aa0b3af6533d..9842258ba343 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -449,6 +449,24 @@ int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
 }
 EXPORT_SYMBOL(filemap_fdatawrite_range);
 
+/**
+ * filemap_fdatawrite_range_kick - start writeback on a range
+ * @mapping:	target address_space
+ * @start:	index to start writeback on
+ * @end:	last (non-inclusive) index for writeback
+ *
+ * This is a non-integrity writeback helper, to start writing back folios
+ * for the indicated range.
+ *
+ * Return: %0 on success, negative error code otherwise.
+ */
+int filemap_fdatawrite_range_kick(struct address_space *mapping, loff_t start,
+				  loff_t end)
+{
+	return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_NONE);
+}
+EXPORT_SYMBOL_GPL(filemap_fdatawrite_range_kick);
+
 /**
  * filemap_flush - mostly a non-blocking flush
  * @mapping:	target address_space
-- 
2.45.2