cifs: add a warning when the in-flight count goes negative

[ Upstream commit e4645cc2f1e2d6f268bb8dcfac40997c52432aed ]

We've seen the in-flight count go into negative with some
internal stress testing in Microsoft.

Adding a WARN when this happens, in hope of understanding
why this happens when it happens.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Bharath SM <bharathsm@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index dec306a3b0f4144c8a51a2d01404c525bc9e272b..3287795c648e51ab2f702563f4b0b4ed0e104f53 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -78,6 +78,7 @@ smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add,
                *val = 65000; /* Don't get near 64K credits, avoid srv bugs */
                printk_once(KERN_WARNING "server overflowed SMB3 credits\n");
        }
+       WARN_ON_ONCE(server->in_flight == 0);
        server->in_flight--;
        if (server->in_flight == 0 && (optype & CIFS_OP_MASK) != CIFS_NEG_OP)
                rc = change_conf(server);