From patchwork Wed Nov 13 11:49:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Richard W.M. 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Jones" To: qemu-block@nongnu.org Cc: qemu-devel@nongnu.org, kwolf@redhat.com, hreitz@redhat.com, jjelen@redhat.com, mpitt@redhat.com Subject: [PATCH ssh] ssh: Do not switch session to non-blocking mode Date: Wed, 13 Nov 2024 11:49:55 +0000 Message-ID: <20241113115000.2494785-1-rjones@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.133.124; envelope-from=rjones@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.119, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Jakub Jelen The libssh does not handle non-blocking mode in SFTP correctly. The driver code already changes the mode to blocking for the SFTP initialization, but for some reason changes to non-blocking mode. This used to work accidentally until libssh in 0.11 branch merged the patch to avoid infinite looping in case of network errors: https://gitlab.com/libssh/libssh-mirror/-/merge_requests/498 Since then, the ssh driver in qemu fails to read files over SFTP as the first SFTP messages exchanged after switching the session to non-blocking mode return SSH_AGAIN, but that message is lost int the SFTP internals and interpretted as SSH_ERROR, which is returned to the caller: https://gitlab.com/libssh/libssh-mirror/-/issues/280 This is indeed an issue in libssh that we should address in the long term, but it will require more work on the internals. For now, the SFTP is not supported in non-blocking mode. Fixes: https://gitlab.com/libssh/libssh-mirror/-/issues/280 Signed-off-by: Jakub Jelen Signed-off-by: Richard W.M. Jones --- block/ssh.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/block/ssh.c b/block/ssh.c index 9f8140bcb6..e1529cfda9 100644 --- a/block/ssh.c +++ b/block/ssh.c @@ -866,8 +866,6 @@ static int ssh_open(BlockDriverState *bs, QDict *options, int bdrv_flags, goto err; } - /* Go non-blocking. */ - ssh_set_blocking(s->session, 0); if (s->attrs->type == SSH_FILEXFER_TYPE_REGULAR) { bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;