Commit 6cd3d6fd authored by David Howells's avatar David Howells
Browse files

netfs: Trace refcounting on the netfs_io_subrequest struct 



Add refcount tracing for the netfs_io_subrequest structure.

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

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

Link: https://lore.kernel.org/r/164622998584.3564931.5052255990645723639.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/164678202603.1200972.14726007419792315578.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/164692901860.2099075.4845820886851239935.stgit@warthog.procyon.org.uk/ # v3
parent de74023b

fs/netfs/internal.h

+0 −2
Original line number Diff line number Diff line
@@ -25,8 +25,6 @@ void netfs_clear_subrequests(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)

fs/netfs/objects.c

+23 −9
Original line number Diff line number Diff line
@@ -53,7 +53,8 @@ void netfs_clear_subrequests(struct netfs_io_request *rreq, bool was_async) 
		subreq = list_first_entry(&rreq->subrequests,

					  struct netfs_io_subrequest, rreq_link);

		list_del(&subreq->rreq_link);

		netfs_put_subrequest(subreq, was_async);

		netfs_put_subrequest(subreq, was_async,

				     netfs_sreq_trace_put_clear);

	}

}
@@ -101,7 +102,7 @@ struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq 
	subreq = kzalloc(sizeof(struct netfs_io_subrequest), GFP_KERNEL);

	if (subreq) {

		INIT_LIST_HEAD(&subreq->rreq_link);

		refcount_set(&subreq->usage, 2);

		refcount_set(&subreq->ref, 2);

		subreq->rreq = rreq;

		netfs_get_request(rreq, netfs_rreq_trace_get_subreq);

		netfs_stat(&netfs_n_rh_sreq);
@@ -110,12 +111,17 @@ struct netfs_io_subrequest *netfs_alloc_subrequest(struct netfs_io_request *rreq 
	return subreq;

}



void netfs_get_subrequest(struct netfs_io_subrequest *subreq)

void netfs_get_subrequest(struct netfs_io_subrequest *subreq,

			  enum netfs_sreq_ref_trace what)

{

	refcount_inc(&subreq->usage);

	int r;



	__refcount_inc(&subreq->ref, &r);

	trace_netfs_sreq_ref(subreq->rreq->debug_id, subreq->debug_index, r + 1,

			     what);

}



static void __netfs_put_subrequest(struct netfs_io_subrequest *subreq,

static void netfs_free_subrequest(struct netfs_io_subrequest *subreq,

				  bool was_async)

{

	struct netfs_io_request *rreq = subreq->rreq;
@@ -126,8 +132,16 @@ static void __netfs_put_subrequest(struct netfs_io_subrequest *subreq, 
	netfs_put_request(rreq, was_async, netfs_rreq_trace_put_subreq);

}



void netfs_put_subrequest(struct netfs_io_subrequest *subreq, bool was_async)

void netfs_put_subrequest(struct netfs_io_subrequest *subreq, bool was_async,

			  enum netfs_sreq_ref_trace what)

{

	if (refcount_dec_and_test(&subreq->usage))

		__netfs_put_subrequest(subreq, was_async);

	unsigned int debug_index = subreq->debug_index;

	unsigned int debug_id = subreq->rreq->debug_id;

	bool dead;

	int r;



	dead = __refcount_dec_and_test(&subreq->ref, &r);

	trace_netfs_sreq_ref(debug_id, debug_index, r - 1, what);

	if (dead)

		netfs_free_subrequest(subreq, was_async);

}

fs/netfs/read_helper.c

+11 −9
Original line number Diff line number Diff line
@@ -167,7 +167,7 @@ static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error, 
	if (atomic_dec_and_test(&rreq->nr_copy_ops))

		netfs_rreq_unmark_after_write(rreq, was_async);



	netfs_put_subrequest(subreq, was_async);

	netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);

}



/*
@@ -191,7 +191,8 @@ static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq) 
	list_for_each_entry_safe(subreq, p, &rreq->subrequests, rreq_link) {

		if (!test_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags)) {

			list_del_init(&subreq->rreq_link);

			netfs_put_subrequest(subreq, false);

			netfs_put_subrequest(subreq, false,

					     netfs_sreq_trace_put_no_copy);

		}

	}
@@ -203,7 +204,8 @@ static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq) 
				break;

			subreq->len += next->len;

			list_del_init(&next->rreq_link);

			netfs_put_subrequest(next, false);

			netfs_put_subrequest(next, false,

					     netfs_sreq_trace_put_merged);

		}



		ret = cres->ops->prepare_write(cres, &subreq->start, &subreq->len,
@@ -219,7 +221,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_io_request *rreq) 


		atomic_inc(&rreq->nr_copy_ops);

		netfs_stat(&netfs_n_rh_write);

		netfs_get_subrequest(subreq);

		netfs_get_subrequest(subreq, netfs_sreq_trace_get_copy_to_cache);

		trace_netfs_sreq(subreq, netfs_sreq_trace_write);

		cres->ops->write(cres, subreq->start, &iter,

				 netfs_rreq_copy_terminated, subreq);
@@ -342,7 +344,7 @@ static void netfs_rreq_short_read(struct netfs_io_request *rreq, 
	netfs_stat(&netfs_n_rh_short_read);

	trace_netfs_sreq(subreq, netfs_sreq_trace_resubmit_short);



	netfs_get_subrequest(subreq);

	netfs_get_subrequest(subreq, netfs_sreq_trace_get_short_read);

	atomic_inc(&rreq->nr_outstanding);

	if (subreq->source == NETFS_READ_FROM_CACHE)

		netfs_read_from_cache(rreq, subreq, NETFS_READ_HOLE_CLEAR);
@@ -376,7 +378,7 @@ static bool netfs_rreq_perform_resubmissions(struct netfs_io_request *rreq) 
			subreq->error = 0;

			netfs_stat(&netfs_n_rh_download_instead);

			trace_netfs_sreq(subreq, netfs_sreq_trace_download_instead);

			netfs_get_subrequest(subreq);

			netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);

			atomic_inc(&rreq->nr_outstanding);

			netfs_read_from_server(rreq, subreq);

		} else if (test_bit(NETFS_SREQ_SHORT_IO, &subreq->flags)) {
@@ -538,7 +540,7 @@ void netfs_subreq_terminated(struct netfs_io_subrequest *subreq, 
	else if (u == 1)

		wake_up_var(&rreq->nr_outstanding);



	netfs_put_subrequest(subreq, was_async);

	netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);

	return;



incomplete:
@@ -683,7 +685,7 @@ static bool netfs_rreq_submit_slice(struct netfs_io_request *rreq, 


subreq_failed:

	rreq->error = subreq->error;

	netfs_put_subrequest(subreq, false);

	netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_failed);

	return false;

}
@@ -1030,13 +1032,13 @@ 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, netfs_rreq_trace_get_hold);



	/* 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))

include/linux/netfs.h

+7 −1
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include <linux/fs.h>

#include <linux/pagemap.h>



enum netfs_sreq_ref_trace;



/*

 * Overload PG_private_2 to give us PG_fscache - this is used to indicate that

 * a page is currently backed by a local disk cache
@@ -136,7 +138,7 @@ struct netfs_io_subrequest { 
	loff_t			start;		/* Where to start the I/O */

	size_t			len;		/* Size of the I/O */

	size_t			transferred;	/* Amount of data transferred */

	refcount_t		usage;

	refcount_t		ref;

	short			error;		/* 0 or error that occurred */

	unsigned short		debug_index;	/* Index in list (for debugging output) */

	enum netfs_io_source	source;		/* Where to read from/write to */
@@ -268,6 +270,10 @@ extern int netfs_write_begin(struct file *, struct address_space *, 
			     void *);



extern void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);

extern void netfs_get_subrequest(struct netfs_io_subrequest *subreq,

				 enum netfs_sreq_ref_trace what);

extern void netfs_put_subrequest(struct netfs_io_subrequest *subreq,

				 bool was_async, enum netfs_sreq_ref_trace what);

extern void netfs_stats_show(struct seq_file *);



#endif /* _LINUX_NETFS_H */

include/trace/events/netfs.h

+40 −0
Original line number Diff line number Diff line
@@ -64,6 +64,17 @@ 
	EM(netfs_rreq_trace_put_subreq,		"PUT SUBREQ ")	\

	E_(netfs_rreq_trace_new,		"NEW        ")



#define netfs_sreq_ref_traces					\

	EM(netfs_sreq_trace_get_copy_to_cache,	"GET COPY2C ")	\

	EM(netfs_sreq_trace_get_resubmit,	"GET RESUBMIT")	\

	EM(netfs_sreq_trace_get_short_read,	"GET SHORTRD")	\

	EM(netfs_sreq_trace_new,		"NEW        ")	\

	EM(netfs_sreq_trace_put_clear,		"PUT CLEAR  ")	\

	EM(netfs_sreq_trace_put_failed,		"PUT FAILED ")	\

	EM(netfs_sreq_trace_put_merged,		"PUT MERGED ")	\

	EM(netfs_sreq_trace_put_no_copy,	"PUT NO COPY")	\

	E_(netfs_sreq_trace_put_terminated,	"PUT TERM   ")



#ifndef __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY

#define __NETFS_DECLARE_TRACE_ENUMS_ONCE_ONLY
@@ -77,6 +88,7 @@ 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);

enum netfs_sreq_ref_trace { netfs_sreq_ref_traces } __mode(byte);



#endif
@@ -94,6 +106,7 @@ netfs_sreq_sources; 
netfs_sreq_traces;

netfs_failures;

netfs_rreq_ref_traces;

netfs_sreq_ref_traces;



/*

 * Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -264,6 +277,33 @@ TRACE_EVENT(netfs_rreq_ref, 
		      __entry->ref)

	    );



TRACE_EVENT(netfs_sreq_ref,

	    TP_PROTO(unsigned int rreq_debug_id, unsigned int subreq_debug_index,

		     int ref, enum netfs_sreq_ref_trace what),



	    TP_ARGS(rreq_debug_id, subreq_debug_index, ref, what),



	    TP_STRUCT__entry(

		    __field(unsigned int,		rreq		)

		    __field(unsigned int,		subreq		)

		    __field(int,			ref		)

		    __field(enum netfs_sreq_ref_trace,	what		)

			     ),



	    TP_fast_assign(

		    __entry->rreq	= rreq_debug_id;

		    __entry->subreq	= subreq_debug_index;

		    __entry->ref	= ref;

		    __entry->what	= what;

			   ),



	    TP_printk("R=%08x[%x] %s r=%u",

		      __entry->rreq,

		      __entry->subreq,

		      __print_symbolic(__entry->what, netfs_sreq_ref_traces),

		      __entry->ref)

	    );



#undef EM

#undef E_

#endif /* _TRACE_NETFS_H */