From 90b16fc7877e05adac291ba4f4bce6d88a74bb0a Mon Sep 17 00:00:00 2001 From: Marios Makassikis Date: Mon, 9 Dec 2024 11:51:00 +0900 Subject: [PATCH] ksmbd: fix broken transfers when exceeding max simultaneous operations Since commit 0a77d947f599 ("ksmbd: check outstanding simultaneous SMB operations"), ksmbd enforces a maximum number of simultaneous operations for a connection. The problem is that reaching the limit causes ksmbd to close the socket, and the client has no indication that it should have slowed down. This behaviour can be reproduced by setting "smb2 max credits = 128" (or lower), and transferring a large file (25GB). smbclient fails as below: $ smbclient //192.168.1.254/testshare -U user%pass smb: \> put file.bin cli_push returned NT_STATUS_USER_SESSION_DELETED putting file file.bin as \file.bin smb2cli_req_compound_submit: Insufficient credits. 0 available, 1 needed NT_STATUS_INTERNAL_ERROR closing remote file \file.bin smb: \> smb2cli_req_compound_submit: Insufficient credits. 0 available, 1 needed Windows clients fail with 0x8007003b (with smaller files even). Fix this by delaying reading from the socket until there's room to allocate a request. This effectively applies backpressure on the client, so the transfer completes, albeit at a slower rate. Fixes: 0a77d947f599 ("ksmbd: check outstanding simultaneous SMB operations") Signed-off-by: Marios Makassikis Signed-off-by: Namjae Jeon --- connection.c | 13 +++++++++++-- connection.h | 1 - server.c | 7 +------ server.h | 1 + transport_ipc.c | 5 ++++- 5 files changed, 17 insertions(+), 10 deletions(-) diff --git a/connection.c b/connection.c index 88b6a085..4404fc76 100644 --- a/connection.c +++ b/connection.c @@ -77,7 +77,6 @@ struct ksmbd_conn *ksmbd_conn_alloc(void) atomic_set(&conn->req_running, 0); atomic_set(&conn->r_count, 0); atomic_set(&conn->refcnt, 1); - atomic_set(&conn->mux_smb_requests, 0); conn->total_credits = 1; conn->outstanding_credits = 0; @@ -151,6 +150,8 @@ void ksmbd_conn_try_dequeue_request(struct ksmbd_work *work) struct ksmbd_conn *conn = work->conn; atomic_dec(&conn->req_running); + if (waitqueue_active(&conn->req_running_q)) + wake_up(&conn->req_running_q); if (list_empty(&work->request_entry) && list_empty(&work->async_request_entry)) @@ -361,7 +362,7 @@ int ksmbd_conn_handler_loop(void *p) { struct ksmbd_conn *conn = (struct ksmbd_conn *)p; struct ksmbd_transport *t = conn->transport; - unsigned int pdu_size, max_allowed_pdu_size; + unsigned int pdu_size, max_allowed_pdu_size, max_req; char hdr_buf[4] = {0,}; int size; @@ -371,6 +372,7 @@ int ksmbd_conn_handler_loop(void *p) if (t->ops->prepare && t->ops->prepare(t)) goto out; + max_req = server_conf.max_inflight_req; conn->last_active = jiffies; set_freezable(); while (ksmbd_conn_alive(conn)) { @@ -380,6 +382,13 @@ int ksmbd_conn_handler_loop(void *p) kvfree(conn->request_buf); conn->request_buf = NULL; +recheck: + if (atomic_read(&conn->req_running) + 1 > max_req) { + wait_event_interruptible(conn->req_running_q, + atomic_read(&conn->req_running) < max_req); + goto recheck; + } + size = t->ops->read(t, hdr_buf, sizeof(hdr_buf), -1); if (size != sizeof(hdr_buf)) break; diff --git a/connection.h b/connection.h index 8ddd5a3c..b379ae4f 100644 --- a/connection.h +++ b/connection.h @@ -107,7 +107,6 @@ struct ksmbd_conn { __le16 signing_algorithm; bool binding; atomic_t refcnt; - atomic_t mux_smb_requests; }; struct ksmbd_conn_ops { diff --git a/server.c b/server.c index 6bcb61de..f2c8d179 100644 --- a/server.c +++ b/server.c @@ -270,7 +270,6 @@ static void handle_ksmbd_work(struct work_struct *wk) ksmbd_conn_try_dequeue_request(work); ksmbd_free_work_struct(work); - atomic_dec(&conn->mux_smb_requests); /* * Checking waitqueue to dropping pending requests on * disconnection. waitqueue_active is safe because it @@ -300,11 +299,6 @@ static int queue_ksmbd_work(struct ksmbd_conn *conn) if (err) return 0; - if (atomic_inc_return(&conn->mux_smb_requests) >= conn->vals->max_credits) { - atomic_dec_return(&conn->mux_smb_requests); - return -ENOSPC; - } - work = ksmbd_alloc_work_struct(); if (!work) { pr_err("allocation for work failed\n"); @@ -367,6 +361,7 @@ static int server_conf_init(void) server_conf.auth_mechs |= KSMBD_AUTH_KRB5 | KSMBD_AUTH_MSKRB5; #endif + server_conf.max_inflight_req = SMB2_MAX_CREDITS; return 0; } diff --git a/server.h b/server.h index 4fc52933..94187628 100644 --- a/server.h +++ b/server.h @@ -42,6 +42,7 @@ struct ksmbd_server_config { struct smb_sid domain_sid; unsigned int auth_mechs; unsigned int max_connections; + unsigned int max_inflight_req; char *conf[SERVER_CONF_WORK_GROUP + 1]; struct task_struct *dh_task; diff --git a/transport_ipc.c b/transport_ipc.c index 33e4ffb6..1ceb65ce 100644 --- a/transport_ipc.c +++ b/transport_ipc.c @@ -321,8 +321,11 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req) init_smb2_max_write_size(req->smb2_max_write); if (req->smb2_max_trans) init_smb2_max_trans_size(req->smb2_max_trans); - if (req->smb2_max_credits) + if (req->smb2_max_credits) { init_smb2_max_credits(req->smb2_max_credits); + server_conf.max_inflight_req = + req->smb2_max_credits; + } if (req->smbd_max_io_size) init_smbd_max_io_size(req->smbd_max_io_size);