mm: move filemap_range_needs_writeback() into header

No functional changes in this patch, just in preparation for efficiently
calling this light function from the block O_DIRECT handling.

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 3 insertions, 29 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index daa0e23a6ee6..655c9eec06b3 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -646,8 +646,8 @@ static bool mapping_needs_writeback(struct address_space *mapping)
 	return mapping->nrpages;
 }
 
-static bool filemap_range_has_writeback(struct address_space *mapping,
-					loff_t start_byte, loff_t end_byte)
+bool filemap_range_has_writeback(struct address_space *mapping,
+				 loff_t start_byte, loff_t end_byte)
 {
 	XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
 	pgoff_t max = end_byte >> PAGE_SHIFT;
@@ -667,34 +667,8 @@ static bool filemap_range_has_writeback(struct address_space *mapping,
 	}
 	rcu_read_unlock();
 	return page != NULL;
-
-}
-
-/**
- * filemap_range_needs_writeback - check if range potentially needs writeback
- * @mapping:           address space within which to check
- * @start_byte:        offset in bytes where the range starts
- * @end_byte:          offset in bytes where the range ends (inclusive)
- *
- * Find at least one page in the range supplied, usually used to check if
- * direct writing in this range will trigger a writeback. Used by O_DIRECT
- * read/write with IOCB_NOWAIT, to see if the caller needs to do
- * filemap_write_and_wait_range() before proceeding.
- *
- * Return: %true if the caller should do filemap_write_and_wait_range() before
- * doing O_DIRECT to a page in this range, %false otherwise.
- */
-bool filemap_range_needs_writeback(struct address_space *mapping,
-				   loff_t start_byte, loff_t end_byte)
-{
-	if (!mapping_needs_writeback(mapping))
-		return false;
-	if (!mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
-	    !mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK))
-		return false;
-	return filemap_range_has_writeback(mapping, start_byte, end_byte);
 }
-EXPORT_SYMBOL_GPL(filemap_range_needs_writeback);
+EXPORT_SYMBOL_GPL(filemap_range_has_writeback);
 
 /**
  * filemap_write_and_wait_range - write out & wait on a file range