On Fri, 16 Mar 2012 18:09:26 +0300 Pavel Shilovsky <[email protected]> wrote:
> 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. > The existing code essentially "hardcodes" a value of 50 instead of using maxReq. While I think that's wrong, if you change that behavior in the first patch, it's going to make tracking down any regressions from this very difficult. I think it might be better to have this series introduce no behavioral changes at all, and simply reorganize the code around a credit-based model. Once that's complete and working, then do a patch that makes the code respect maxReq. I know that that's more work, but we do need to be careful when we're tinkering with the low-level plumbing like this... > Signed-off-by: Pavel Shilovsky <[email protected]> > --- > fs/cifs/cifsglob.h | 11 +++++++---- > fs/cifs/cifsproto.h | 3 +++ > fs/cifs/cifssmb.c | 10 +++++----- > fs/cifs/connect.c | 14 ++++++-------- > fs/cifs/misc.c | 18 ++++++++++++++++++ > fs/cifs/transport.c | 36 ++++++++++++++++++++---------------- > 6 files changed, 59 insertions(+), 33 deletions(-) > > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h > index fb78bc9..d55de96 100644 > --- a/fs/cifs/cifsglob.h > +++ b/fs/cifs/cifsglob.h > @@ -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; > } > > /* > diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h > index 6f4e243..47a769e 100644 > --- a/fs/cifs/cifsproto.h > +++ b/fs/cifs/cifsproto.h > @@ -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 *); > diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c > index d7cbcfa..08c84a1 100644 > --- a/fs/cifs/cifssmb.c > +++ b/fs/cifs/cifssmb.c > @@ -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); > @@ -721,7 +721,7 @@ cifs_echo_callback(struct mid_q_entry *mid) > struct TCP_Server_Info *server = mid->callback_data; > > DeleteMidQEntry(mid); > - dec_in_flight(server); > + cifs_add_credits(server, 1); > wake_up(&server->request_q); ^^^^^^^^^ The above wake_up always follows the call to cifs_add_credits. Should you go ahead and move it inside of cifs_add_credits? > } > > @@ -1674,7 +1674,7 @@ cifs_readv_callback(struct mid_q_entry *mid) > > queue_work(system_nrt_wq, &rdata->work); > DeleteMidQEntry(mid); > - dec_in_flight(server); > + cifs_add_credits(server, 1); > wake_up(&server->request_q); > } > > @@ -2115,7 +2115,7 @@ cifs_writev_callback(struct mid_q_entry *mid) > > queue_work(system_nrt_wq, &wdata->work); > DeleteMidQEntry(mid); > - dec_in_flight(tcon->ses->server); > + cifs_add_credits(tcon->ses->server, 1); > wake_up(&tcon->ses->server->request_q); > } > > diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c > index a7627f2..f3a0c49 100644 > --- a/fs/cifs/connect.c > +++ b/fs/cifs/connect.c > @@ -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); > @@ -3756,9 +3752,11 @@ 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; > diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c > index 703ef5c..5dc936b 100644 > --- a/fs/cifs/misc.c > +++ b/fs/cifs/misc.c > @@ -690,3 +690,21 @@ 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); > +} > + > +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); > +} > diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c > index e2673aa..e8a4fd3 100644 > --- a/fs/cifs/transport.c > +++ b/fs/cifs/transport.c > @@ -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; > } > @@ -565,7 +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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -602,7 +606,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -613,7 +617,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -638,7 +642,7 @@ SendReceive2(const unsigned int xid, struct cifs_ses *ses, > midQ->resp_buf = NULL; > out: > delete_mid(midQ); > - dec_in_flight(ses->server); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > > return rc; > @@ -689,7 +693,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -722,7 +726,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -731,7 +735,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > return rc; > } > @@ -748,7 +752,7 @@ 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); > + cifs_add_credits(ses->server, 1); > wake_up(&ses->server->request_q); > > return rc; -- Jeff Layton <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-cifs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
