[PATCH 09/19] netfs: Trace refcounting on the netfs_io_request struct
David Howells
dhowells at redhat.com
Wed Mar 2 06:06:16 PST 2022
Add refcount tracing for the netfs_io_request structure.
Signed-off-by: David Howells <dhowells at redhat.com>
cc: linux-cachefs at redhat.com
---
fs/netfs/internal.h | 11 +++++++++--
fs/netfs/objects.c | 24 +++++++++++++++++-------
fs/netfs/read_helper.c | 14 +++++++-------
include/linux/netfs.h | 2 +-
include/trace/events/netfs.h | 35 +++++++++++++++++++++++++++++++++++
5 files changed, 69 insertions(+), 17 deletions(-)
diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
index 1f2ad9c9d103..b3877e276a3a 100644
--- a/fs/netfs/internal.h
+++ b/fs/netfs/internal.h
@@ -22,13 +22,20 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
struct file *file,
loff_t start, size_t len,
enum netfs_io_origin origin);
-void netfs_get_request(struct netfs_io_request *rreq);
+void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what);
void netfs_clear_subrequests(struct netfs_io_request *rreq, bool was_async);
-void netfs_put_request(struct netfs_io_request *rreq, bool was_async);
+void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
+ enum netfs_rreq_ref_trace what);
struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq);
void netfs_put_subrequest(struct netfs_io_subrequest *subreq, bool was_async);
void netfs_get_subrequest(struct netfs_io_subrequest *subreq);
+static inline void netfs_see_request(struct netfs_io_request *rreq,
+ enum netfs_rreq_ref_trace what)
+{
+ trace_netfs_rreq_ref(rreq->debug_id, refcount_read(&rreq->ref), what);
+}
+
/*
* read_helper.c
*/
diff --git a/fs/netfs/objects.c b/fs/netfs/objects.c
index b212de11ebca..57d53f1f6741 100644
--- a/fs/netfs/objects.c
+++ b/fs/netfs/objects.c
@@ -33,7 +33,7 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
rreq->debug_id = atomic_inc_return(&debug_ids);
INIT_LIST_HEAD(&rreq->subrequests);
INIT_WORK(&rreq->work, netfs_rreq_work);
- refcount_set(&rreq->usage, 1);
+ refcount_set(&rreq->ref, 1);
__set_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags);
if (ctx->ops->init_request)
ctx->ops->init_request(rreq, file);
@@ -43,9 +43,12 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
return rreq;
}
-void netfs_get_request(struct netfs_io_request *rreq)
+void netfs_get_request(struct netfs_io_request *rreq, enum netfs_rreq_ref_trace what)
{
- refcount_inc(&rreq->usage);
+ int r;
+
+ __refcount_inc(&rreq->ref, &r);
+ trace_netfs_rreq_ref(rreq->debug_id, r + 1, what);
}
void netfs_clear_subrequests(struct netfs_io_request *rreq, bool was_async)
@@ -74,9 +77,16 @@ static void netfs_free_request(struct work_struct *work)
netfs_stat_d(&netfs_n_rh_rreq);
}
-void netfs_put_request(struct netfs_io_request *rreq, bool was_async)
+void netfs_put_request(struct netfs_io_request *rreq, bool was_async,
+ enum netfs_rreq_ref_trace what)
{
- if (refcount_dec_and_test(&rreq->usage)) {
+ unsigned int debug_id = rreq->debug_id;
+ bool dead;
+ int r;
+
+ dead = __refcount_dec_and_test(&rreq->ref, &r);
+ trace_netfs_rreq_ref(debug_id, r - 1, what);
+ if (dead) {
if (was_async) {
rreq->work.func = netfs_free_request;
if (!queue_work(system_unbound_wq, &rreq->work))
@@ -99,7 +109,7 @@ struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq
INIT_LIST_HEAD(&subreq->rreq_link);
refcount_set(&subreq->usage, 2);
subreq->rreq = rreq;
- netfs_get_request(rreq);
+ netfs_get_request(rreq, netfs_rreq_trace_get_subreq);
netfs_stat(&netfs_n_rh_sreq);
}
@@ -119,7 +129,7 @@ static void netfs_free_subrequest(struct netfs_io_subrequest *subreq,
trace_netfs_sreq(subreq, netfs_sreq_trace_free);
kfree(subreq);
netfs_stat_d(&netfs_n_rh_sreq);
- netfs_put_request(rreq, was_async);
+ netfs_put_request(rreq, was_async, netfs_rreq_trace_put_subreq);
}
void netfs_put_subrequest(struct netfs_io_subrequest *subreq, bool was_async)
diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 5e0fdf9c9772..535b2cbde4c8 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -108,7 +108,7 @@ static void netfs_rreq_completed(struct netfs_io_request *rreq, bool was_async)
{
trace_netfs_rreq(rreq, netfs_rreq_trace_done);
netfs_clear_subrequests(rreq, was_async);
- netfs_put_request(rreq, was_async);
+ netfs_put_request(rreq, was_async, netfs_rreq_trace_put_complete);
}
/*
@@ -794,7 +794,7 @@ void netfs_readahead(struct readahead_control *ractl)
return;
cleanup_free:
- netfs_put_request(rreq, false);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
return;
}
EXPORT_SYMBOL(netfs_readahead);
@@ -840,7 +840,7 @@ int netfs_readpage(struct file *file, struct page *subpage)
netfs_stat(&netfs_n_rh_readpage);
trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
- netfs_get_request(rreq);
+ netfs_get_request(rreq, netfs_rreq_trace_get_hold);
atomic_set(&rreq->nr_outstanding, 1);
do {
@@ -865,7 +865,7 @@ int netfs_readpage(struct file *file, struct page *subpage)
ret = -EIO;
}
out:
- netfs_put_request(rreq, false);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
return ret;
nomem:
folio_unlock(folio);
@@ -1024,13 +1024,13 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
*/
ractl._nr_pages = folio_nr_pages(folio);
netfs_rreq_expand(rreq, &ractl);
- netfs_get_request(rreq);
/* We hold the folio locks, so we can drop the references */
folio_get(folio);
while (readahead_folio(&ractl))
;
+ netfs_get_request(rreq, netfs_rreq_trace_get_hold);
atomic_set(&rreq->nr_outstanding, 1);
do {
if (!netfs_rreq_submit_slice(rreq, &debug_index))
@@ -1056,7 +1056,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_write_begin);
ret = -EIO;
}
- netfs_put_request(rreq, false);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
if (ret < 0)
goto error;
@@ -1070,7 +1070,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
return 0;
error_put:
- netfs_put_request(rreq, false);
+ netfs_put_request(rreq, false, netfs_rreq_trace_put_failed);
error:
folio_unlock(folio);
folio_put(folio);
diff --git a/include/linux/netfs.h b/include/linux/netfs.h
index 8c33777c439e..e5c049a25746 100644
--- a/include/linux/netfs.h
+++ b/include/linux/netfs.h
@@ -185,7 +185,7 @@ struct netfs_io_request {
loff_t i_size; /* Size of the file */
loff_t start; /* Start position */
pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
- refcount_t usage;
+ refcount_t ref;
unsigned long flags;
#define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
#define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 8330ae8fbc0a..8c700e2bcd5c 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -60,6 +60,15 @@
EM(netfs_fail_short_write_begin, "short-write-begin") \
E_(netfs_fail_prepare_write, "prep-write")
+#define netfs_rreq_ref_traces \
+ EM(netfs_rreq_trace_get_hold, "GET HOLD ") \
+ EM(netfs_rreq_trace_get_subreq, "GET SUBREQ ") \
+ EM(netfs_rreq_trace_put_complete, "PUT COMPLT ") \
+ EM(netfs_rreq_trace_put_failed, "PUT FAILED ") \
+ EM(netfs_rreq_trace_put_hold, "PUT HOLD ") \
+ EM(netfs_rreq_trace_put_subreq, "PUT SUBREQ ") \
+ E_(netfs_rreq_trace_new, "NEW ")
+
#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
@@ -72,6 +81,7 @@ enum netfs_read_trace { netfs_read_traces } __mode(byte);
enum netfs_rreq_trace { netfs_rreq_traces } __mode(byte);
enum netfs_sreq_trace { netfs_sreq_traces } __mode(byte);
enum netfs_failure { netfs_failures } __mode(byte);
+enum netfs_rreq_ref_trace { netfs_rreq_ref_traces } __mode(byte);
#endif
@@ -89,6 +99,7 @@ netfs_rreq_traces;
netfs_sreq_sources;
netfs_sreq_traces;
netfs_failures;
+netfs_rreq_ref_traces;
/*
* Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -238,6 +249,30 @@ TRACE_EVENT(netfs_failure,
__entry->error)
);
+TRACE_EVENT(netfs_rreq_ref,
+ TP_PROTO(unsigned int rreq_debug_id, int ref,
+ enum netfs_rreq_ref_trace what),
+
+ TP_ARGS(rreq_debug_id, ref, what),
+
+ TP_STRUCT__entry(
+ __field(unsigned int, rreq )
+ __field(int, ref )
+ __field(enum netfs_rreq_ref_trace, what )
+ ),
+
+ TP_fast_assign(
+ __entry->rreq = rreq_debug_id;
+ __entry->ref = ref;
+ __entry->what = what;
+ ),
+
+ TP_printk("W=%08x %s r=%u",
+ __entry->rreq,
+ __print_symbolic(__entry->what, netfs_rreq_ref_traces),
+ __entry->ref)
+ );
+
#endif /* _TRACE_NETFS_H */
/* This part must be outside protection */
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