[PATCH 05/10] btrfs: convert heuristic_collect_sample() to use folios

[Tal Zussman]

Convert the sampling loop to folios. This removes the last caller of
find_get_page() in btrfs and saves a call to compound_head() per sampled
page. Document that the lookup is not supposed to fail with an ASSERT().

Signed-off-by: Tal Zussman <tz2294@xxxxxxxxxxxx>
---
 fs/btrfs/compression.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 979b2ffbd8fc..fa8b92592321 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -1488,7 +1488,7 @@ static bool sample_repeated_patterns(struct heuristic_ws *ws)
 static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
 				     struct heuristic_ws *ws)
 {
-	struct page *page;
+	struct folio *folio;
 	pgoff_t index, index_end;
 	u32 i, curr_sample_pos;
 	u8 *in_data;
@@ -1514,8 +1514,10 @@ static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
 
 	curr_sample_pos = 0;
 	while (index < index_end) {
-		page = find_get_page(inode->i_mapping, index);
-		in_data = kmap_local_page(page);
+		folio = filemap_get_folio(inode->i_mapping, index);
+		ASSERT(!IS_ERR(folio));
+		in_data = kmap_local_folio(folio,
+				offset_in_folio(folio, (u64)index << PAGE_SHIFT));
 		/* Handle case where the start is not aligned to PAGE_SIZE */
 		i = start % PAGE_SIZE;
 		while (i < PAGE_SIZE - SAMPLING_READ_SIZE) {
@@ -1529,7 +1531,7 @@ static void heuristic_collect_sample(struct inode *inode, u64 start, u64 end,
 			curr_sample_pos += SAMPLING_READ_SIZE;
 		}
 		kunmap_local(in_data);
-		put_page(page);
+		folio_put(folio);
 
 		index++;
 	}

-- 
2.39.5