[focal:linux-azure][(additional) PATCH 1/1] cifs: do not fail __smb_send_rqst if non-fatal signals are pending

[Marcelo Henrique Cerri]

From: Ronnie Sahlberg <lsahlber at redhat.com>

BugLink: https://bugs.launchpad.net/bugs/1911438

RHBZ 1848178

The original intent of returning an error in this function
in the patch:
  "CIFS: Mask off signals when sending SMB packets"
was to avoid interrupting packet send in the middle of
sending the data (and thus breaking an SMB connection),
but we also don't want to fail the request for non-fatal
signals even before we have had a chance to try to
send it (the reported problem could be reproduced e.g.
by exiting a child process when the parent process was in
the midst of calling futimens to update a file's timestamps).

In addition, since the signal may remain pending when we enter the
sending loop, we may end up not sending the whole packet before
TCP buffers become full. In this case the code returns -EINTR
but what we need here is to return -ERESTARTSYS instead to
allow system calls to be restarted.

Fixes: b30c74c73c78 ("CIFS: Mask off signals when sending SMB packets")
Cc: stable at vger.kernel.org # v5.1+
Signed-off-by: Ronnie Sahlberg <lsahlber at redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov at microsoft.com>
Signed-off-by: Steve French <stfrench at microsoft.com>
(cherry picked from commit 214a5ea081e77346e4963dd6d20c5539ff8b6ae6)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
---
 fs/cifs/transport.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 6d6de183915b..4ffbf8f96581 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -339,7 +339,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 	if (ssocket == NULL)
 		return -EAGAIN;
 
-	if (signal_pending(current)) {
+	if (fatal_signal_pending(current)) {
 		cifs_dbg(FYI, "signal pending before send request\n");
 		return -ERESTARTSYS;
 	}
@@ -431,7 +431,7 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 
 	if (signal_pending(current) && (total_len != send_length)) {
 		cifs_dbg(FYI, "signal is pending after attempt to send\n");
-		rc = -EINTR;
+		rc = -ERESTARTSYS;
 	}
 
 	/* uncork it */
-- 
2.25.1