From: Ronnie Sahlberg lsahlber@redhat.com

Commit d69cb728e70c ("cifs: fix credits leak for SMB1 oplock breaks").

For SMB1 oplock breaks we would grab one credit while sending the PDU but we would never relese the credit back since we will never receive a response to this from the server. Eventuallt this would lead to a hang once all credits are leaked.

Fix this by defining a new flag CIFS_NO_SRV_RSP which indicates that there is no server response to this command and thus we need to add any credits back immediately after sending the PDU.

CC: Stable stable@vger.kernel.org #v5.0+ Signed-off-by: Ronnie Sahlberg lsahlber@redhat.com Reviewed-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Steve French stfrench@microsoft.com --- fs/cifs/cifsglob.h | 1 + fs/cifs/cifssmb.c | 2 +- fs/cifs/transport.c | 10 +++++----- 3 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 10ead04..8c295e3 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1657,6 +1657,7 @@ static inline bool is_retryable_error(int error)

#define CIFS_HAS_CREDITS 0x0400 /* already has credits */ #define CIFS_TRANSFORM_REQ 0x0800 /* transform request before sending */ +#define CIFS_NO_SRV_RSP 0x1000 /* there is no server response */

/* Security Flags: indicate type of session setup needed */ #define CIFSSEC_MAY_SIGN 0x00001 diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index 551924b..f91e714 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -2533,7 +2533,7 @@ CIFSSMBLock(const unsigned int xid, struct cifs_tcon *tcon,

if (lockType == LOCKING_ANDX_OPLOCK_RELEASE) { /* no response expected */ - flags = CIFS_ASYNC_OP | CIFS_OBREAK_OP; + flags = CIFS_NO_SRV_RSP | CIFS_ASYNC_OP | CIFS_OBREAK_OP; pSMB->Timeout = 0; } else if (waitFlag) { flags = CIFS_BLOCKING_OP; /* blocking operation, no timeout */ diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c index 9544eb9..95f3be9 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -906,8 +906,11 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,

mutex_unlock(&ses->server->srv_mutex);

- if (rc < 0) { - /* Sending failed for some reason - return credits back */ + /* + * If sending failed for some reason or it is an oplock break that we + * will not receive a response to - return credits back + */ + if (rc < 0 || (flags & CIFS_NO_SRV_RSP)) { for (i = 0; i < num_rqst; i++) add_credits(ses->server, credits[i], optype); goto out; @@ -928,9 +931,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses, smb311_update_preauth_hash(ses, rqst[0].rq_iov, rqst[0].rq_nvec);

- if (timeout == CIFS_ASYNC_OP) - goto out; - for (i = 0; i < num_rqst; i++) { rc = wait_for_response(ses->server, midQ[i]); if (rc != 0)