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smb: client: transport: avoid reconnects triggered by pending task work

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When io_uring is used in the same task as CIFS, there might be
unnecessary reconnects, causing issues in user-space applications
like QEMU with a log like:

> CIFS: VFS: \\10.10.100.81 Error -512 sending data on socket to server

Certain io_uring completions might be added to task_work with
notify_method being TWA_SIGNAL and thus TIF_NOTIFY_SIGNAL is set for
the task.

In __smb_send_rqst(), signals are masked before calling
smb_send_kvec(), but the masking does not apply to TIF_NOTIFY_SIGNAL.

If sk_stream_wait_memory() is reached via sock_sendmsg() while
TIF_NOTIFY_SIGNAL is set, signal_pending(current) will evaluate to
true there, and -EINTR will be propagated all the way from
sk_stream_wait_memory() to sock_sendmsg() in smb_send_kvec().
Afterwards, __smb_send_rqst() will see that not everything was written
and reconnect.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Fiona Ebner 2025-09-15 17:19:39 +02:00 committed by Steve French
parent 17ef15fa80
commit 00be6f26a2
1 changed files with 9 additions and 1 deletions
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10
fs/smb/client/transport.c
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@ -22,6 +22,7 @@
#include <linux/mempool.h>
#include <linux/sched/signal.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/task_work.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
@ -173,9 +174,16 @@ smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
* send a packet. In most cases if we fail to send
* after the retries we will kill the socket and
* reconnect which may clear the network problem.
*
* Even if regular signals are masked, EINTR might be
* propagated from sk_stream_wait_memory() to here when
* TIF_NOTIFY_SIGNAL is used for task work. For example,
* certain io_uring completions will use that. Treat
* having EINTR with pending task work the same as EAGAIN
* to avoid unnecessary reconnects.
*/
rc = sock_sendmsg(ssocket, smb_msg);
if (rc == -EAGAIN) {
if (rc == -EAGAIN || unlikely(rc == -EINTR && task_work_pending(current))) {
retries++;
if (retries >= 14 ||
(!server->noblocksnd && (retries > 2))) {