[PATCH 03/10] smb: client: compress: disable compression on reconnects

Windows Server resets the connection if it gets a compressed request
that it couldn't decompress.

Some encoded payloads might decode differently on the server, or
vice-versa, due to different implementation details (not really a bug),
or an actual bug on either implementation.

To prevent an infinite retry on such failed sends, simply disable
compression for that server when a reconnect is about to happen.

Signed-off-by: Enzo Matsumiya <[email protected]>
---
 fs/smb/client/connect.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 85aec302c89e..324452bc0437 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -401,6 +401,20 @@ static int __cifs_reconnect(struct TCP_Server_Info *server,
 		try_to_freeze();
 		cifs_server_lock(server);
 
+		/*
+		 * Servers might disconnect us when they can't decompress a compressed request we
+		 * sent.
+		 * When this happens, as a failsafe measure, disable compression entirely to avoid
+		 * an endless retry.
+		 *
+		 * TODO: implement a more flexible alternative, e.g. identify and retry sending the
+		 * failed request uncompressed, without having to disable compression entirely.
+		 */
+		if (server->compression.enabled) {
+			cifs_server_dbg(VFS | ONCE, "disabling compression (failsafe)\n");
+			memset(&server->compression, 0, sizeof(server->compression));
+		}
+
 		if (!cifs_swn_set_server_dstaddr(server) &&
 		    !SERVER_IS_CHAN(server)) {
 			/* resolve the hostname again to make sure that IP address is up-to-date */
-- 
2.54.0