[PATCH 07/12] fuse: support large folios for stores

[Joanne Koong <joannelkoong@xxxxxxxxx>]

Add support for folios larger than one page size for stores.
Also change variable naming from "this_num" to "nr_bytes".

Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
 fs/fuse/dev.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 5be666af3ebe..df9138f33c47 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1658,18 +1658,23 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
 	num = outarg.size;
 	while (num) {
 		struct folio *folio;
-		unsigned int this_num;
+		unsigned int folio_offset;
+		unsigned int nr_bytes;
+		unsigned int nr_pages;
 
 		folio = filemap_grab_folio(mapping, index);
 		err = PTR_ERR(folio);
 		if (IS_ERR(folio))
 			goto out_iput;
 
-		this_num = min_t(unsigned, num, folio_size(folio) - offset);
-		err = fuse_copy_folio(cs, &folio, offset, this_num, 0);
+		folio_offset = ((index - folio->index) << PAGE_SHIFT) + offset;
+		nr_bytes = min_t(unsigned, num, folio_size(folio) - folio_offset);
+		nr_pages = (offset + nr_bytes + PAGE_SIZE - 1) >> PAGE_SHIFT;
+
+		err = fuse_copy_folio(cs, &folio, folio_offset, nr_bytes, 0);
 		if (!folio_test_uptodate(folio) && !err && offset == 0 &&
-		    (this_num == folio_size(folio) || file_size == end)) {
-			folio_zero_segment(folio, this_num, folio_size(folio));
+		    (nr_bytes == folio_size(folio) || file_size == end)) {
+			folio_zero_segment(folio, nr_bytes, folio_size(folio));
 			folio_mark_uptodate(folio);
 		}
 		folio_unlock(folio);
@@ -1678,9 +1683,9 @@ static int fuse_notify_store(struct fuse_conn *fc, unsigned int size,
 		if (err)
 			goto out_iput;
 
-		num -= this_num;
+		num -= nr_bytes;
 		offset = 0;
-		index++;
+		index += nr_pages;
 	}
 
 	err = 0;
-- 
2.43.5