[PATCH 7/9] smb/client: remember async ids from SMB2 pending responses

[ChenXiaoSong <chenxiaosong@chenxiaosong.com>]

From: ChenXiaoSong <chenxiaosong@kylinos.cn>

SMB2 servers may turn a request into an asynchronous command by replying
with STATUS_PENDING and SMB2_FLAGS_ASYNC_COMMAND. A later SMB2_CANCEL must
target the async id from that pending response rather than only the
original message id fields.

Store that async id in the mid entry when processing STATUS_PENDING so
the cancel path can build the correct header.

Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
---
 fs/smb/client/cifsglob.h |  2 ++
 fs/smb/client/smb2ops.c  | 12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 1250518997fb..ea1c5eb2356a 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1713,6 +1713,7 @@ struct mid_q_entry {
 	struct list_head qhead;	/* mids waiting on reply from this server */
 	refcount_t refcount;
 	__u64 mid;		/* multiplex id */
+	__u64 async_id;		/* async id if server returned STATUS_PENDING */
 	__u16 credits;		/* number of credits consumed by this mid */
 	__u16 credits_received;	/* number of credits from the response */
 	__u32 pid;		/* process id */
@@ -1742,6 +1743,7 @@ struct mid_q_entry {
 	bool multiRsp:1;	/* multiple trans2 responses for one request  */
 	bool multiEnd:1;	/* both received */
 	bool decrypted:1;	/* decrypted entry */
+	bool async_cmd:1;	/* server returned an async id for this request */
 };
 
 struct close_cancelled_open {
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 9c2455b5fb03..40f1ae0e9735 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -2684,11 +2684,23 @@ static bool
 smb2_is_status_pending(char *buf, struct TCP_Server_Info *server)
 {
 	struct smb2_hdr *shdr = (struct smb2_hdr *)buf;
+	struct mid_q_entry *mid;
 	int scredits, in_flight;
 
 	if (shdr->Status != STATUS_PENDING)
 		return false;
 
+	if (shdr->Flags & SMB2_FLAGS_ASYNC_COMMAND) {
+		mid = __smb2_find_mid(server, buf, false);
+		if (mid) {
+			spin_lock(&mid->mid_lock);
+			mid->async_cmd = true;
+			mid->async_id = le64_to_cpu(shdr->Id.AsyncId);
+			spin_unlock(&mid->mid_lock);
+			release_mid(server, mid);
+		}
+	}
+
 	if (shdr->CreditRequest) {
 		spin_lock(&server->req_lock);
 		server->credits += le16_to_cpu(shdr->CreditRequest);
-- 
2.54.0