Fix netfs_extract_iter_to_sg() for ITER_UBUF and ITER_IOVEC to set the size
of the page to the part of the page extracted, not the remaining amount of
data in the extracted page array at that point.

This doesn't yet affect anything as cifs, the only current user, only
passes in non-user-backed iterators.

Fixes: 018584697533 ("netfs: Add a function to extract an iterator into a scatterlist")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Steve French <sfrench@samba.org>
cc: Shyam Prasad N <redacted>
cc: Rohith Surabattula <redacted>
cc: linux-cachefs@redhat.com
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/iterator.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c
index e9a45dea748a..8a4c86687429 100644
--- a/fs/netfs/iterator.c
+++ b/fs/netfs/iterator.c

@@ -139,7 +139,7 @@ static ssize_t netfs_extract_user_to_sg(struct iov_iter *iter,
 			size_t seg = min_t(size_t, PAGE_SIZE - off, len);
 
 			*pages++ = NULL;
-			sg_set_page(sg, page, len, off);
+			sg_set_page(sg, page, seg, off);
 			sgtable->nents++;
 			sg++;
 			len -= seg;