Commit 0246f3e5 authored by David Howells's avatar David Howells
Browse files

netfs: Add a tracepoint to log failures that would be otherwise unseen 



Add a tracepoint to log internal failures (such as cache errors) that we
don't otherwise want to pass back to the netfs.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Tested-by: default avatarJeff Layton <jlayton@kernel.org>
Tested-by: default avatarDave Wysochanski <dwysocha@redhat.com>
Tested-By: default avatarMarc Dionne <marc.dionne@auristor.com>
cc: Matthew Wilcox <willy@infradead.org>
cc: linux-mm@kvack.org
cc: linux-cachefs@redhat.com
cc: linux-afs@lists.infradead.org
cc: linux-nfs@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: ceph-devel@vger.kernel.org
cc: v9fs-developer@lists.sourceforge.net
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/161781048813.463527.1557000804674707986.stgit@warthog.procyon.org.uk/
Link: https://lore.kernel.org/r/161789082749.6155.15498680577213140870.stgit@warthog.procyon.org.uk/ # v6
parent 726218fd

fs/netfs/read_helper.c

+12 −2
Original line number Diff line number Diff line
@@ -271,6 +271,8 @@ static void netfs_rreq_copy_terminated(void *priv, ssize_t transferred_or_error, 


	if (IS_ERR_VALUE(transferred_or_error)) {

		netfs_stat(&netfs_n_rh_write_failed);

		trace_netfs_failure(rreq, subreq, transferred_or_error,

				    netfs_fail_copy_to_cache);

	} else {

		netfs_stat(&netfs_n_rh_write_done);

	}
@@ -323,6 +325,7 @@ static void netfs_rreq_do_write_to_cache(struct netfs_read_request *rreq) 
		ret = cres->ops->prepare_write(cres, &subreq->start, &subreq->len,

					       rreq->i_size);

		if (ret < 0) {

			trace_netfs_failure(rreq, subreq, ret, netfs_fail_prepare_write);

			trace_netfs_sreq(subreq, netfs_sreq_trace_write_skip);

			continue;

		}
@@ -627,6 +630,8 @@ void netfs_subreq_terminated(struct netfs_read_subrequest *subreq, 


	if (IS_ERR_VALUE(transferred_or_error)) {

		subreq->error = transferred_or_error;

		trace_netfs_failure(rreq, subreq, transferred_or_error,

				    netfs_fail_read);

		goto failed;

	}
@@ -996,8 +1001,10 @@ int netfs_readpage(struct file *file, 
	} while (test_bit(NETFS_RREQ_IN_PROGRESS, &rreq->flags));



	ret = rreq->error;

	if (ret == 0 && rreq->submitted < rreq->len)

	if (ret == 0 && rreq->submitted < rreq->len) {

		trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_readpage);

		ret = -EIO;

	}

out:

	netfs_put_read_request(rreq, false);

	return ret;
@@ -1069,6 +1076,7 @@ int netfs_write_begin(struct file *file, struct address_space *mapping, 
		/* Allow the netfs (eg. ceph) to flush conflicts. */

		ret = ops->check_write_begin(file, pos, len, page, _fsdata);

		if (ret < 0) {

			trace_netfs_failure(NULL, NULL, ret, netfs_fail_check_write_begin);

			if (ret == -EAGAIN)

				goto retry;

			goto error;
@@ -1145,8 +1153,10 @@ int netfs_write_begin(struct file *file, struct address_space *mapping, 
	}



	ret = rreq->error;

	if (ret == 0 && rreq->submitted < rreq->len)

	if (ret == 0 && rreq->submitted < rreq->len) {

		trace_netfs_failure(rreq, NULL, ret, netfs_fail_short_write_begin);

		ret = -EIO;

	}

	netfs_put_read_request(rreq, false);

	if (ret < 0)

		goto error;

include/trace/events/netfs.h

+58 −0
Original line number Diff line number Diff line
@@ -47,6 +47,15 @@ enum netfs_sreq_trace { 
	netfs_sreq_trace_write_term,

};



enum netfs_failure {

	netfs_fail_check_write_begin,

	netfs_fail_copy_to_cache,

	netfs_fail_read,

	netfs_fail_short_readpage,

	netfs_fail_short_write_begin,

	netfs_fail_prepare_write,

};



#endif



#define netfs_read_traces					\
@@ -81,6 +90,14 @@ enum netfs_sreq_trace { 
	EM(netfs_sreq_trace_write_skip,		"SKIP ")	\

	E_(netfs_sreq_trace_write_term,		"WTERM")



#define netfs_failures							\

	EM(netfs_fail_check_write_begin,	"check-write-begin")	\

	EM(netfs_fail_copy_to_cache,		"copy-to-cache")	\

	EM(netfs_fail_read,			"read")			\

	EM(netfs_fail_short_readpage,		"short-readpage")	\

	EM(netfs_fail_short_write_begin,	"short-write-begin")	\

	E_(netfs_fail_prepare_write,		"prep-write")





/*

 * Export enum symbols via userspace.
@@ -94,6 +111,7 @@ netfs_read_traces; 
netfs_rreq_traces;

netfs_sreq_sources;

netfs_sreq_traces;

netfs_failures;



/*

 * Now redefine the EM() and E_() macros to map the enums to the strings that
@@ -197,6 +215,46 @@ TRACE_EVENT(netfs_sreq, 
		      __entry->error)

	    );



TRACE_EVENT(netfs_failure,

	    TP_PROTO(struct netfs_read_request *rreq,

		     struct netfs_read_subrequest *sreq,

		     int error, enum netfs_failure what),



	    TP_ARGS(rreq, sreq, error, what),



	    TP_STRUCT__entry(

		    __field(unsigned int,		rreq		)

		    __field(unsigned short,		index		)

		    __field(short,			error		)

		    __field(unsigned short,		flags		)

		    __field(enum netfs_read_source,	source		)

		    __field(enum netfs_failure,		what		)

		    __field(size_t,			len		)

		    __field(size_t,			transferred	)

		    __field(loff_t,			start		)

			     ),



	    TP_fast_assign(

		    __entry->rreq	= rreq->debug_id;

		    __entry->index	= sreq ? sreq->debug_index : 0;

		    __entry->error	= error;

		    __entry->flags	= sreq ? sreq->flags : 0;

		    __entry->source	= sreq ? sreq->source : NETFS_INVALID_READ;

		    __entry->what	= what;

		    __entry->len	= sreq ? sreq->len : 0;

		    __entry->transferred = sreq ? sreq->transferred : 0;

		    __entry->start	= sreq ? sreq->start : 0;

			   ),



	    TP_printk("R=%08x[%u] %s f=%02x s=%llx %zx/%zx %s e=%d",

		      __entry->rreq, __entry->index,

		      __print_symbolic(__entry->source, netfs_sreq_sources),

		      __entry->flags,

		      __entry->start, __entry->transferred, __entry->len,

		      __print_symbolic(__entry->what, netfs_failures),

		      __entry->error)

	    );



#endif /* _TRACE_NETFS_H */



/* This part must be outside protection */