[PATCH v4 04/10] fuse: support large folios for writethrough writes

[Joanne Koong <joannelkoong@xxxxxxxxx>]

Add support for folios larger than one page size for writethrough
writes.

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

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 71b243b32f0a..aeed80bbf01c 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1214,6 +1214,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 				     struct iov_iter *ii, loff_t pos,
 				     unsigned int max_pages)
 {
+	size_t max_folio_size = mapping_max_folio_size(mapping);
 	struct fuse_args_pages *ap = &ia->ap;
 	struct fuse_conn *fc = get_fuse_conn(mapping->host);
 	unsigned offset = pos & (PAGE_SIZE - 1);
@@ -1225,17 +1226,17 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 	num = min(num, max_pages << PAGE_SHIFT);
 
 	ap->args.in_pages = true;
-	ap->descs[0].offset = offset;
 
 	while (num) {
 		size_t tmp;
 		struct folio *folio;
 		pgoff_t index = pos >> PAGE_SHIFT;
-		unsigned int bytes = min(PAGE_SIZE - offset, num);
+		unsigned int bytes;
+		unsigned int folio_offset;
 
  again:
 		err = -EFAULT;
-		if (fault_in_iov_iter_readable(ii, bytes))
+		if (fault_in_iov_iter_readable(ii, max_folio_size) == max_folio_size)
 			break;
 
 		folio = __filemap_get_folio(mapping, index, FGP_WRITEBEGIN,
@@ -1248,7 +1249,10 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 		if (mapping_writably_mapped(mapping))
 			flush_dcache_folio(folio);
 
-		tmp = copy_folio_from_iter_atomic(folio, offset, bytes, ii);
+		folio_offset = ((index - folio->index) << PAGE_SHIFT) + offset;
+		bytes = min(folio_size(folio) - folio_offset, num);
+
+		tmp = copy_folio_from_iter_atomic(folio, folio_offset, bytes, ii);
 		flush_dcache_folio(folio);
 
 		if (!tmp) {
@@ -1259,6 +1263,7 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 
 		err = 0;
 		ap->folios[ap->num_folios] = folio;
+		ap->descs[ap->num_folios].offset = folio_offset;
 		ap->descs[ap->num_folios].length = tmp;
 		ap->num_folios++;
 
@@ -1266,11 +1271,11 @@ static ssize_t fuse_fill_write_pages(struct fuse_io_args *ia,
 		pos += tmp;
 		num -= tmp;
 		offset += tmp;
-		if (offset == PAGE_SIZE)
+		if (offset == folio_size(folio))
 			offset = 0;
 
-		/* If we copied full page, mark it uptodate */
-		if (tmp == PAGE_SIZE)
+		/* If we copied full folio, mark it uptodate */
+		if (tmp == folio_size(folio))
 			folio_mark_uptodate(folio);
 
 		if (folio_test_uptodate(folio)) {
-- 
2.43.5