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netfs: Trace refcounting on the netfs_io_request struct

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Add refcount tracing for the netfs_io_request structure.

Changes
=======
ver #3)
 - Switch 'W=' to 'R=' in the traceline to match other request debug IDs.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com

Link: https://lore.kernel.org/r/164622997668.3564931.14456171619219324968.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678200943.1200972.7241495532327787765.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692900920.2099075.11847712419940675791.stgit@warthog.procyon.org.uk/ # v3
This commit is contained in:
David Howells 2022-02-17 21:13:05 +00:00
parent 18b3ff9fe8
commit de74023bef
5 changed files with 69 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
fs/netfs/internal.h
View File

@ -20,13 +20,20 @@
struct netfs_io_request *netfs_alloc_request(const struct netfs_request_ops *ops,
void *netfs_priv,
struct file *file);
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
*/

24
fs/netfs/objects.c
View File

@ -27,7 +27,7 @@ struct netfs_io_request *netfs_alloc_request(
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 (ops->init_request)
ops->init_request(rreq, file);
@ -37,9 +37,12 @@ struct netfs_io_request *netfs_alloc_request(
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)
@ -68,9 +71,16 @@ 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))
@ -93,7 +103,7 @@ 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);
}
@ -113,7 +123,7 @@ static void __netfs_put_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)

14
fs/netfs/read_helper.c
View File

@ -109,7 +109,7 @@ 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);
}
/*
@ -799,7 +799,7 @@ 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;
cleanup:
if (netfs_priv)
@ -858,7 +858,7 @@ int netfs_readpage(struct file *file,
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 {
@ -883,7 +883,7 @@ int netfs_readpage(struct file *file,
ret = -EIO;
}
out:
netfs_put_request(rreq, false);
netfs_put_request(rreq, false, netfs_rreq_trace_put_hold);
return ret;
}
EXPORT_SYMBOL(netfs_readpage);
@ -1030,13 +1030,13 @@ retry:
*/
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))
@ -1062,7 +1062,7 @@ retry:
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;
@ -1078,7 +1078,7 @@ have_folio_no_wait:
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);

2
include/linux/netfs.h
View File

@ -168,7 +168,7 @@ 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 */

35
include/trace/events/netfs.h
View File

@ -55,6 +55,15 @@
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
@ -67,6 +76,7 @@ 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
@ -83,6 +93,7 @@ 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
@ -229,6 +240,30 @@ 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("R=%08x %s r=%u",
__entry->rreq,
__print_symbolic(__entry->what, netfs_rreq_ref_traces),
__entry->ref)
);
#undef EM
#undef E_
#endif /* _TRACE_NETFS_H */