[RFC 02/23] pagemap: use mapping_min_order in fgf_set_order()

[Pankaj Raghav <kernel@pankajraghav.com>]

From: Pankaj Raghav <p.raghav@samsung.com>

fgf_set_order() encodes optimal order in fgp flags. Set it to at least
mapping_min_order from the page cache. Default to the old behaviour if
min_order is not set.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
 fs/iomap/buffered-io.c  | 2 +-
 include/linux/pagemap.h | 9 +++++----
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index ae8673ce08b1..d4613fd550c4 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -549,7 +549,7 @@ struct folio *iomap_get_folio(struct iomap_iter *iter, loff_t pos, size_t len)
 
 	if (iter->flags & IOMAP_NOWAIT)
 		fgp |= FGP_NOWAIT;
-	fgp |= fgf_set_order(len);
+	fgp |= fgf_set_order(iter->inode->i_mapping, len);
 
 	return __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT,
 			fgp, mapping_gfp_mask(iter->inode->i_mapping));
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index d2b5308cc59e..5d392366420a 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -620,6 +620,7 @@ typedef unsigned int __bitwise fgf_t;
 
 /**
  * fgf_set_order - Encode a length in the fgf_t flags.
+ * @mapping: address_space struct from the inode
  * @size: The suggested size of the folio to create.
  *
  * The caller of __filemap_get_folio() can use this to suggest a preferred
@@ -629,13 +630,13 @@ typedef unsigned int __bitwise fgf_t;
  * due to alignment constraints, memory pressure, or the presence of
  * other folios at nearby indices.
  */
-static inline fgf_t fgf_set_order(size_t size)
+static inline fgf_t fgf_set_order(struct address_space *mapping, size_t size)
 {
 	unsigned int shift = ilog2(size);
+	unsigned int min_order = mapping_min_folio_order(mapping);
+	int order = max(min_order, shift - PAGE_SHIFT);
 
-	if (shift <= PAGE_SHIFT)
-		return 0;
-	return (__force fgf_t)((shift - PAGE_SHIFT) << 26);
+	return (__force fgf_t)((order) << 26);
 }
 
 void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
-- 
2.40.1