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cifs: Add a tracepoint to track credits involved in R/W requests

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Add a tracepoint to track the credit changes and server in_flight value
involved in the lifetime of a R/W request, logging it against the
request/subreq debugging ID.  This requires the debugging IDs to be
recorded in the cifs_credits struct.

The tracepoint can be enabled with:

	echo 1 >/sys/kernel/debug/tracing/events/cifs/smb3_rw_credits/enable

Also add a three-state flag to struct cifs_credits to note if we're
interested in determining when the in_flight contribution ends and, if so,
to track whether we've decremented the contribution yet.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
David Howells 2024-05-23 10:01:08 +01:00 committed by Steve French
parent 61ea6b3a31
commit 519be98971
7 changed files with 173 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
fs/smb/client/cifsglob.h
View File

@ -290,7 +290,7 @@ struct smb_version_operations {
int (*check_receive)(struct mid_q_entry *, struct TCP_Server_Info *,
bool);
void (*add_credits)(struct TCP_Server_Info *server,
const struct cifs_credits *credits,
struct cifs_credits *credits,
const int optype);
void (*set_credits)(struct TCP_Server_Info *, const int);
int * (*get_credits_field)(struct TCP_Server_Info *, const int);
@ -550,8 +550,8 @@ struct smb_version_operations {
size_t *, struct cifs_credits *);
/* adjust previously taken mtu credits to request size */
int (*adjust_credits)(struct TCP_Server_Info *server,
struct cifs_credits *credits,
const unsigned int payload_size);
struct cifs_io_subrequest *subreq,
unsigned int /*enum smb3_rw_credits_trace*/ trace);
/* check if we need to issue closedir */
bool (*dir_needs_close)(struct cifsFileInfo *);
long (*fallocate)(struct file *, struct cifs_tcon *, int, loff_t,
@ -848,6 +848,9 @@ static inline void cifs_server_unlock(struct TCP_Server_Info *server)
struct cifs_credits {
unsigned int value;
unsigned int instance;
unsigned int in_flight_check;
unsigned int rreq_debug_id;
unsigned int rreq_debug_index;
};
static inline unsigned int
@ -873,7 +876,7 @@ has_credits(struct TCP_Server_Info *server, int *credits, int num_credits)
}
static inline void
add_credits(struct TCP_Server_Info *server, const struct cifs_credits *credits,
add_credits(struct TCP_Server_Info *server, struct cifs_credits *credits,
const int optype)
{
server->ops->add_credits(server, credits, optype);
@ -897,11 +900,11 @@ set_credits(struct TCP_Server_Info *server, const int val)
}
static inline int
adjust_credits(struct TCP_Server_Info *server, struct cifs_credits *credits,
const unsigned int payload_size)
adjust_credits(struct TCP_Server_Info *server, struct cifs_io_subrequest *subreq,
unsigned int /* enum smb3_rw_credits_trace */ trace)
{
return server->ops->adjust_credits ?
server->ops->adjust_credits(server, credits, payload_size) : 0;
server->ops->adjust_credits(server, subreq, trace) : 0;
}
static inline __le64

32
fs/smb/client/file.c
View File

@ -80,6 +80,16 @@ retry:
return netfs_prepare_write_failed(subreq);
}
wdata->credits.rreq_debug_id = subreq->rreq->debug_id;
wdata->credits.rreq_debug_index = subreq->debug_index;
wdata->credits.in_flight_check = 1;
trace_smb3_rw_credits(wdata->rreq->debug_id,
wdata->subreq.debug_index,
wdata->credits.value,
server->credits, server->in_flight,
wdata->credits.value,
cifs_trace_rw_credits_write_prepare);
#ifdef CONFIG_CIFS_SMB_DIRECT
if (server->smbd_conn)
subreq->max_nr_segs = server->smbd_conn->max_frmr_depth;
@ -101,7 +111,7 @@ static void cifs_issue_write(struct netfs_io_subrequest *subreq)
goto fail;
}
rc = adjust_credits(wdata->server, &wdata->credits, wdata->subreq.len);
rc = adjust_credits(wdata->server, wdata, cifs_trace_rw_credits_issue_write_adjust);
if (rc)
goto fail;
@ -158,7 +168,18 @@ static bool cifs_clamp_length(struct netfs_io_subrequest *subreq)
return false;
}
rdata->credits.in_flight_check = 1;
rdata->credits.rreq_debug_id = rreq->debug_id;
rdata->credits.rreq_debug_index = subreq->debug_index;
trace_smb3_rw_credits(rdata->rreq->debug_id,
rdata->subreq.debug_index,
rdata->credits.value,
server->credits, server->in_flight, 0,
cifs_trace_rw_credits_read_submit);
subreq->len = min_t(size_t, subreq->len, rsize);
#ifdef CONFIG_CIFS_SMB_DIRECT
if (server->smbd_conn)
subreq->max_nr_segs = server->smbd_conn->max_frmr_depth;
@ -289,6 +310,15 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq)
#endif
}
if (rdata->credits.value != 0)
trace_smb3_rw_credits(rdata->rreq->debug_id,
rdata->subreq.debug_index,
rdata->credits.value,
rdata->server ? rdata->server->credits : 0,
rdata->server ? rdata->server->in_flight : 0,
-rdata->credits.value,
cifs_trace_rw_credits_free_subreq);
add_credits_and_wake_if(rdata->server, &rdata->credits, 0);
if (rdata->have_xid)
free_xid(rdata->xid);

2
fs/smb/client/smb1ops.c
View File

@ -108,7 +108,7 @@ cifs_find_mid(struct TCP_Server_Info *server, char *buffer)
static void
cifs_add_credits(struct TCP_Server_Info *server,
const struct cifs_credits *credits, const int optype)
struct cifs_credits *credits, const int optype)
{
spin_lock(&server->req_lock);
server->credits += credits->value;

42
fs/smb/client/smb2ops.c
View File

@ -66,7 +66,7 @@ change_conf(struct TCP_Server_Info *server)
static void
smb2_add_credits(struct TCP_Server_Info *server,
const struct cifs_credits *credits, const int optype)
struct cifs_credits *credits, const int optype)
{
int *val, rc = -1;
int scredits, in_flight;
@ -94,7 +94,21 @@ smb2_add_credits(struct TCP_Server_Info *server,
server->conn_id, server->hostname, *val,
add, server->in_flight);
}
WARN_ON_ONCE(server->in_flight == 0);
if (credits->in_flight_check > 1) {
pr_warn_once("rreq R=%08x[%x] Credits not in flight\n",
credits->rreq_debug_id, credits->rreq_debug_index);
} else {
credits->in_flight_check = 2;
}
if (WARN_ON_ONCE(server->in_flight == 0)) {
pr_warn_once("rreq R=%08x[%x] Zero in_flight\n",
credits->rreq_debug_id, credits->rreq_debug_index);
trace_smb3_rw_credits(credits->rreq_debug_id,
credits->rreq_debug_index,
credits->value,
server->credits, server->in_flight, 0,
cifs_trace_rw_credits_zero_in_flight);
}
server->in_flight--;
if (server->in_flight == 0 &&
((optype & CIFS_OP_MASK) != CIFS_NEG_OP) &&
@ -283,16 +297,23 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, size_t size,
static int
smb2_adjust_credits(struct TCP_Server_Info *server,
struct cifs_credits *credits,
const unsigned int payload_size)
struct cifs_io_subrequest *subreq,
unsigned int /*enum smb3_rw_credits_trace*/ trace)
{
int new_val = DIV_ROUND_UP(payload_size, SMB2_MAX_BUFFER_SIZE);
struct cifs_credits *credits = &subreq->credits;
int new_val = DIV_ROUND_UP(subreq->subreq.len, SMB2_MAX_BUFFER_SIZE);
int scredits, in_flight;
if (!credits->value || credits->value == new_val)
return 0;
if (credits->value < new_val) {
trace_smb3_rw_credits(subreq->rreq->debug_id,
subreq->subreq.debug_index,
credits->value,
server->credits, server->in_flight,
new_val - credits->value,
cifs_trace_rw_credits_no_adjust_up);
trace_smb3_too_many_credits(server->CurrentMid,
server->conn_id, server->hostname, 0, credits->value - new_val, 0);
cifs_server_dbg(VFS, "request has less credits (%d) than required (%d)",
@ -308,6 +329,12 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
in_flight = server->in_flight;
spin_unlock(&server->req_lock);
trace_smb3_rw_credits(subreq->rreq->debug_id,
subreq->subreq.debug_index,
credits->value,
server->credits, server->in_flight,
new_val - credits->value,
cifs_trace_rw_credits_old_session);
trace_smb3_reconnect_detected(server->CurrentMid,
server->conn_id, server->hostname, scredits,
credits->value - new_val, in_flight);
@ -316,6 +343,11 @@ smb2_adjust_credits(struct TCP_Server_Info *server,
return -EAGAIN;
}
trace_smb3_rw_credits(subreq->rreq->debug_id,
subreq->subreq.debug_index,
credits->value,
server->credits, server->in_flight,
new_val - credits->value, trace);
server->credits += credits->value - new_val;
scredits = server->credits;
in_flight = server->in_flight;

40
fs/smb/client/smb2pdu.c
View File

@ -4502,8 +4502,15 @@ smb2_readv_callback(struct mid_q_entry *mid)
struct TCP_Server_Info *server = rdata->server;
struct smb2_hdr *shdr =
(struct smb2_hdr *)rdata->iov[0].iov_base;
struct cifs_credits credits = { .value = 0, .instance = 0 };
struct cifs_credits credits = {
.value = 0,
.instance = 0,
.rreq_debug_id = rdata->rreq->debug_id,
.rreq_debug_index = rdata->subreq.debug_index,
};
struct smb_rqst rqst = { .rq_iov = &rdata->iov[1], .rq_nvec = 1 };
unsigned int rreq_debug_id = rdata->rreq->debug_id;
unsigned int subreq_debug_index = rdata->subreq.debug_index;
if (rdata->got_bytes) {
rqst.rq_iter = rdata->subreq.io_iter;
@ -4587,10 +4594,16 @@ smb2_readv_callback(struct mid_q_entry *mid)
if (rdata->subreq.start < rdata->subreq.rreq->i_size)
rdata->result = 0;
}
trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, rdata->credits.value,
server->credits, server->in_flight,
0, cifs_trace_rw_credits_read_response_clear);
rdata->credits.value = 0;
INIT_WORK(&rdata->subreq.work, smb2_readv_worker);
queue_work(cifsiod_wq, &rdata->subreq.work);
release_mid(mid);
trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, 0,
server->credits, server->in_flight,
credits.value, cifs_trace_rw_credits_read_response_add);
add_credits(server, &credits, 0);
}
@ -4647,7 +4660,7 @@ smb2_async_readv(struct cifs_io_subrequest *rdata)
min_t(int, server->max_credits -
server->credits, credit_request));
rc = adjust_credits(server, &rdata->credits, rdata->subreq.len);
rc = adjust_credits(server, rdata, cifs_trace_rw_credits_call_readv_adjust);
if (rc)
goto async_readv_out;
@ -4766,7 +4779,14 @@ smb2_writev_callback(struct mid_q_entry *mid)
struct cifs_tcon *tcon = tlink_tcon(wdata->req->cfile->tlink);
struct TCP_Server_Info *server = wdata->server;
struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf;
struct cifs_credits credits = { .value = 0, .instance = 0 };
struct cifs_credits credits = {
.value = 0,
.instance = 0,
.rreq_debug_id = wdata->rreq->debug_id,
.rreq_debug_index = wdata->subreq.debug_index,
};
unsigned int rreq_debug_id = wdata->rreq->debug_id;
unsigned int subreq_debug_index = wdata->subreq.debug_index;
ssize_t result = 0;
size_t written;
@ -4837,9 +4857,15 @@ smb2_writev_callback(struct mid_q_entry *mid)
tcon->tid, tcon->ses->Suid,
wdata->subreq.start, wdata->subreq.len);
trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, wdata->credits.value,
server->credits, server->in_flight,
0, cifs_trace_rw_credits_write_response_clear);
wdata->credits.value = 0;
cifs_write_subrequest_terminated(wdata, result ?: written, true);
release_mid(mid);
trace_smb3_rw_credits(rreq_debug_id, subreq_debug_index, 0,
server->credits, server->in_flight,
credits.value, cifs_trace_rw_credits_write_response_add);
add_credits(server, &credits, 0);
}
@ -4969,7 +4995,7 @@ smb2_async_writev(struct cifs_io_subrequest *wdata)
min_t(int, server->max_credits -
server->credits, credit_request));
rc = adjust_credits(server, &wdata->credits, io_parms->length);
rc = adjust_credits(server, wdata, cifs_trace_rw_credits_call_writev_adjust);
if (rc)
goto async_writev_out;
@ -4994,6 +5020,12 @@ async_writev_out:
cifs_small_buf_release(req);
out:
if (rc) {
trace_smb3_rw_credits(wdata->rreq->debug_id,
wdata->subreq.debug_index,
wdata->credits.value,
server->credits, server->in_flight,
-(int)wdata->credits.value,
cifs_trace_rw_credits_write_response_clear);
add_credits_and_wake_if(wdata->server, &wdata->credits, 0);
cifs_write_subrequest_terminated(wdata, rc, true);
}

55
fs/smb/client/trace.h
View File

@ -20,6 +20,22 @@
/*
* Specify enums for tracing information.
*/
#define smb3_rw_credits_traces \
EM(cifs_trace_rw_credits_call_readv_adjust, "rd-call-adj") \
EM(cifs_trace_rw_credits_call_writev_adjust, "wr-call-adj") \
EM(cifs_trace_rw_credits_free_subreq, "free-subreq") \
EM(cifs_trace_rw_credits_issue_read_adjust, "rd-issu-adj") \
EM(cifs_trace_rw_credits_issue_write_adjust, "wr-issu-adj") \
EM(cifs_trace_rw_credits_no_adjust_up, "no-adj-up ") \
EM(cifs_trace_rw_credits_old_session, "old-session") \
EM(cifs_trace_rw_credits_read_response_add, "rd-resp-add") \
EM(cifs_trace_rw_credits_read_response_clear, "rd-resp-clr") \
EM(cifs_trace_rw_credits_read_submit, "rd-submit ") \
EM(cifs_trace_rw_credits_write_prepare, "wr-prepare ") \
EM(cifs_trace_rw_credits_write_response_add, "wr-resp-add") \
EM(cifs_trace_rw_credits_write_response_clear, "wr-resp-clr") \
E_(cifs_trace_rw_credits_zero_in_flight, "ZERO-IN-FLT")
#define smb3_tcon_ref_traces \
EM(netfs_trace_tcon_ref_dec_dfs_refer, "DEC DfsRef") \
EM(netfs_trace_tcon_ref_free, "FRE ") \
@ -59,7 +75,8 @@
#define EM(a, b) a,
#define E_(a, b) a
enum smb3_tcon_ref_trace { smb3_tcon_ref_traces } __mode(byte);
enum smb3_rw_credits_trace { smb3_rw_credits_traces } __mode(byte);
enum smb3_tcon_ref_trace { smb3_tcon_ref_traces } __mode(byte);
#undef EM
#undef E_
@ -71,6 +88,7 @@ enum smb3_tcon_ref_trace { smb3_tcon_ref_traces } __mode(byte);
#define EM(a, b) TRACE_DEFINE_ENUM(a);
#define E_(a, b) TRACE_DEFINE_ENUM(a);
smb3_rw_credits_traces;
smb3_tcon_ref_traces;
#undef EM
@ -1316,6 +1334,41 @@ TRACE_EVENT(smb3_tcon_ref,
__entry->ref)
);
TRACE_EVENT(smb3_rw_credits,
TP_PROTO(unsigned int rreq_debug_id,
unsigned int subreq_debug_index,
unsigned int subreq_credits,
unsigned int server_credits,
int server_in_flight,
int credit_change,
enum smb3_rw_credits_trace trace),
TP_ARGS(rreq_debug_id, subreq_debug_index, subreq_credits,
server_credits, server_in_flight, credit_change, trace),
TP_STRUCT__entry(
__field(unsigned int, rreq_debug_id)
__field(unsigned int, subreq_debug_index)
__field(unsigned int, subreq_credits)
__field(unsigned int, server_credits)
__field(int, in_flight)
__field(int, credit_change)
__field(enum smb3_rw_credits_trace, trace)
),
TP_fast_assign(
__entry->rreq_debug_id = rreq_debug_id;
__entry->subreq_debug_index = subreq_debug_index;
__entry->subreq_credits = subreq_credits;
__entry->server_credits = server_credits;
__entry->in_flight = server_in_flight;
__entry->credit_change = credit_change;
__entry->trace = trace;
),
TP_printk("R=%08x[%x] %s cred=%u chg=%d pool=%u ifl=%d",
__entry->rreq_debug_id, __entry->subreq_debug_index,
__print_symbolic(__entry->trace, smb3_rw_credits_traces),
__entry->subreq_credits, __entry->credit_change,
__entry->server_credits, __entry->in_flight)
);
#undef EM
#undef E_

8
fs/smb/client/transport.c
View File

@ -988,10 +988,10 @@ static void
cifs_compound_callback(struct mid_q_entry *mid)
{
struct TCP_Server_Info *server = mid->server;
struct cifs_credits credits;
credits.value = server->ops->get_credits(mid);
credits.instance = server->reconnect_instance;
struct cifs_credits credits = {
.value = server->ops->get_credits(mid),
.instance = server->reconnect_instance,
};
add_credits(server, &credits, mid->optype);