linux-kernel - [PATCH 1/2] cifs: Fix cifs_write_back_from_locked

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Date:   Mon, 27 Feb 2023 13:04:53 +0000
From:   David Howells <dhowells@...hat.com>
To:     Steve French <smfrench@...il.com>
Cc:     David Howells <dhowells@...hat.com>,
        Shyam Prasad N <nspmangalore@...il.com>,
        Rohith Surabattula <rohiths.msft@...il.com>,
        Tom Talpey <tom@...pey.com>,
        Stefan Metzmacher <metze@...ba.org>,
        Jeff Layton <jlayton@...nel.org>, linux-cifs@...r.kernel.org,
        linux-kernel@...r.kernel.org, Steve French <sfrench@...ba.org>
Subject: [PATCH 1/2] cifs: Fix cifs_write_back_from_locked_folio()

cifs_write_back_from_locked_folio() should return the number of bytes read,
but returns the result of ->async_writev(), which will be 0 on success.  As
it happens, this doesn't prevent cifs_writepages_region() from working as
it will then examine and ignore the pages that are no longer dirty rather
than just skipping over them.

Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list")
Signed-off-by: David Howells <dhowells@...hat.com>
cc: Steve French <sfrench@...ba.org>
cc: Shyam Prasad N <nspmangalore@...il.com>
cc: Rohith Surabattula <rohiths.msft@...il.com>
cc: Tom Talpey <tom@...pey.com>
cc: Jeff Layton <jlayton@...nel.org>
cc: linux-cifs@...r.kernel.org
---
 fs/cifs/file.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index ebfcaae8c437..f8cc68ce9d8a 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -2839,6 +2839,7 @@ static ssize_t cifs_write_back_from_locked_folio(struct address_space *mapping,
 	free_xid(xid);
 	if (rc == 0) {
 		wbc->nr_to_write = count;
+		rc = len;
 	} else if (is_retryable_error(rc)) {
 		cifs_pages_write_redirty(inode, start, len);
 	} else {