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 --- 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 621640195713..7a65124f70f9 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1701,6 +1701,7 @@ 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 f43747c062a7..6050851edcb8 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -2540,7 +2540,7 @@ 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 5c59c498f56a..5573e38b13f3 100644 --- a/fs/cifs/transport.c +++ b/fs/cifs/transport.c @@ -1073,8 +1073,11 @@ 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; @@ -1095,9 +1098,6 @@ 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 ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP) - goto out; - for (i = 0; i < num_rqst; i++) { rc = wait_for_response(ses->server, midQ[i]); if (rc != 0)