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CIFS: Introduce credit-based flow control

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and send no more than credits value requests at once. For SMB/CIFS
it's trivial: increment this value by receiving any message and
decrement by sending one.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Pavel Shilovsky 2012-02-06 15:59:18 +04:00 committed by Steve French
parent fc40f9cf82
commit 2d86dbc970
6 changed files with 60 additions and 44 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
fs/cifs/cifsglob.h
View file

@ -250,8 +250,9 @@ struct TCP_Server_Info {
bool noblocksnd; /* use blocking sendmsg */
bool noautotune; /* do not autotune send buf sizes */
bool tcp_nodelay;
int credits; /* send no more requests at once */
unsigned int in_flight; /* number of requests on the wire to server */
spinlock_t req_lock; /* protect the value above */
spinlock_t req_lock; /* protect the two values above */
struct mutex srv_mutex;
struct task_struct *tsk;
char server_GUID[16];
@ -314,12 +315,14 @@ in_flight(struct TCP_Server_Info *server)
return num;
}
static inline void
dec_in_flight(struct TCP_Server_Info *server)
static inline bool
has_credits(struct TCP_Server_Info *server)
{
int num;
spin_lock(&server->req_lock);
server->in_flight--;
num = server->credits;
spin_unlock(&server->req_lock);
return num > 0;
}
/*

3
fs/cifs/cifsproto.h
View file

@ -88,6 +88,9 @@ extern int SendReceiveBlockingLock(const unsigned int xid,
struct smb_hdr *in_buf ,
struct smb_hdr *out_buf,
int *bytes_returned);
extern void cifs_add_credits(struct TCP_Server_Info *server,
const unsigned int add);
extern void cifs_set_credits(struct TCP_Server_Info *server, const int val);
extern int checkSMB(struct smb_hdr *smb, __u16 mid, unsigned int length);
extern bool is_valid_oplock_break(struct smb_hdr *smb,
struct TCP_Server_Info *);

13
fs/cifs/cifssmb.c
View file

@ -461,7 +461,7 @@ CIFSSMBNegotiate(unsigned int xid, struct cifs_ses *ses)
server->maxReq = min_t(unsigned int,
le16_to_cpu(rsp->MaxMpxCount),
cifs_max_pending);
server->oplocks = server->maxReq > 1 ? enable_oplocks : false;
cifs_set_credits(server, server->maxReq);
server->maxBuf = le16_to_cpu(rsp->MaxBufSize);
server->max_vcs = le16_to_cpu(rsp->MaxNumberVcs);
/* even though we do not use raw we might as well set this
@ -569,7 +569,7 @@ CIFSSMBNegotiate(unsigned int xid, struct cifs_ses *ses)
little endian */
server->maxReq = min_t(unsigned int, le16_to_cpu(pSMBr->MaxMpxCount),
cifs_max_pending);
server->oplocks = server->maxReq > 1 ? enable_oplocks : false;
cifs_set_credits(server, server->maxReq);
/* probably no need to store and check maxvcs */
server->maxBuf = le32_to_cpu(pSMBr->MaxBufferSize);
server->max_rw = le32_to_cpu(pSMBr->MaxRawSize);
@ -721,8 +721,7 @@ cifs_echo_callback(struct mid_q_entry *mid)
struct TCP_Server_Info *server = mid->callback_data;
DeleteMidQEntry(mid);
dec_in_flight(server);
wake_up(&server->request_q);
cifs_add_credits(server, 1);
}
int
@ -1674,8 +1673,7 @@ cifs_readv_callback(struct mid_q_entry *mid)
queue_work(system_nrt_wq, &rdata->work);
DeleteMidQEntry(mid);
dec_in_flight(server);
wake_up(&server->request_q);
cifs_add_credits(server, 1);
}
/* cifs_async_readv - send an async write, and set up mid to handle result */
@ -2115,8 +2113,7 @@ cifs_writev_callback(struct mid_q_entry *mid)
queue_work(system_nrt_wq, &wdata->work);
DeleteMidQEntry(mid);
dec_in_flight(tcon->ses->server);
wake_up(&tcon->ses->server->request_q);
cifs_add_credits(tcon->ses->server, 1);
}
/* cifs_async_writev - send an async write, and set up mid to handle result */

14
fs/cifs/connect.c
View file

@ -642,14 +642,10 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
spin_unlock(&GlobalMid_Lock);
wake_up_all(&server->response_q);
/* Check if we have blocked requests that need to free. */
/* check if we have blocked requests that need to free */
spin_lock(&server->req_lock);
if (server->in_flight >= server->maxReq)
server->in_flight = server->maxReq - 1;
/*
* We do not want to set the max_pending too low or we could end up
* with the counter going negative.
*/
if (server->credits <= 0)
server->credits = 1;
spin_unlock(&server->req_lock);
/*
* Although there should not be any requests blocked on this queue it
@ -1906,7 +1902,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
tcp_ses->noautotune = volume_info->noautotune;
tcp_ses->tcp_nodelay = volume_info->sockopt_tcp_nodelay;
tcp_ses->in_flight = 0;
tcp_ses->maxReq = 1; /* enough to send negotiate request */
tcp_ses->credits = 1;
init_waitqueue_head(&tcp_ses->response_q);
init_waitqueue_head(&tcp_ses->request_q);
INIT_LIST_HEAD(&tcp_ses->pending_mid_q);
@ -3757,9 +3753,11 @@ int cifs_negotiate_protocol(unsigned int xid, struct cifs_ses *ses)
if (server->maxBuf != 0)
return 0;
cifs_set_credits(server, 1);
rc = CIFSSMBNegotiate(xid, ses);
if (rc == -EAGAIN) {
/* retry only once on 1st time connection */
cifs_set_credits(server, 1);
rc = CIFSSMBNegotiate(xid, ses);
if (rc == -EAGAIN)
rc = -EHOSTDOWN;

19
fs/cifs/misc.c
View file

@ -690,3 +690,22 @@ backup_cred(struct cifs_sb_info *cifs_sb)
return false;
}
void
cifs_add_credits(struct TCP_Server_Info *server, const unsigned int add)
{
spin_lock(&server->req_lock);
server->credits += add;
server->in_flight--;
spin_unlock(&server->req_lock);
wake_up(&server->request_q);
}
void
cifs_set_credits(struct TCP_Server_Info *server, const int val)
{
spin_lock(&server->req_lock);
server->credits = val;
server->oplocks = val > 1 ? enable_oplocks : false;
spin_unlock(&server->req_lock);
}

44
fs/cifs/transport.c
View file

@ -262,16 +262,16 @@ wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
if (long_op == CIFS_ASYNC_OP) {
/* oplock breaks must not be held up */
server->in_flight++;
server->credits--;
spin_unlock(&server->req_lock);
return 0;
}
while (1) {
if (server->in_flight >= server->maxReq) {
if (server->credits <= 0) {
spin_unlock(&server->req_lock);
cifs_num_waiters_inc(server);
wait_event(server->request_q,
in_flight(server) < server->maxReq);
wait_event(server->request_q, has_credits(server));
cifs_num_waiters_dec(server);
spin_lock(&server->req_lock);
} else {
@ -280,12 +280,16 @@ wait_for_free_request(struct TCP_Server_Info *server, const int long_op)
return -ENOENT;
}
/* can not count locking commands against total
as they are allowed to block on server */
/*
* Can not count locking commands against total
* as they are allowed to block on server.
*/
/* update # of requests on the wire to server */
if (long_op != CIFS_BLOCKING_OP)
if (long_op != CIFS_BLOCKING_OP) {
server->credits--;
server->in_flight++;
}
spin_unlock(&server->req_lock);
break;
}
@ -360,7 +364,7 @@ cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
mid = AllocMidQEntry(hdr, server);
if (mid == NULL) {
mutex_unlock(&server->srv_mutex);
dec_in_flight(server);
cifs_add_credits(server, 1);
wake_up(&server->request_q);
return -ENOMEM;
}
@ -393,7 +397,7 @@ cifs_call_async(struct TCP_Server_Info *server, struct kvec *iov,
return rc;
out_err:
delete_mid(mid);
dec_in_flight(server);
cifs_add_credits(server, 1);
wake_up(&server->request_q);
return rc;
}
@ -565,8 +569,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses,
mutex_unlock(&ses->server->srv_mutex);
cifs_small_buf_release(in_buf);
/* Update # of requests on wire to server */
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
rc = cifs_sign_smb2(iov, n_vec, ses->server, &midQ->sequence_number);
@ -602,8 +605,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses,
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
cifs_small_buf_release(in_buf);
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
spin_unlock(&GlobalMid_Lock);
@ -613,8 +615,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses,
rc = cifs_sync_mid_result(midQ, ses->server);
if (rc != 0) {
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
@ -638,8 +639,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses,
midQ->resp_buf = NULL;
out:
delete_mid(midQ);
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
@ -689,8 +689,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
if (rc) {
mutex_unlock(&ses->server->srv_mutex);
/* Update # of requests on wire to server */
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
@ -722,8 +721,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
/* no longer considered to be "in-flight" */
midQ->callback = DeleteMidQEntry;
spin_unlock(&GlobalMid_Lock);
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
spin_unlock(&GlobalMid_Lock);
@ -731,8 +729,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
rc = cifs_sync_mid_result(midQ, ses->server);
if (rc != 0) {
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}
@ -748,8 +745,7 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
rc = cifs_check_receive(midQ, ses->server, 0);
out:
delete_mid(midQ);
dec_in_flight(ses->server);
wake_up(&ses->server->request_q);
cifs_add_credits(ses->server, 1);
return rc;
}