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: David Howells <dhowells@redhat.com>
Tested-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-By: Marc 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

1 files changed, 12 insertions, 2 deletions

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index cd3b61d5e192..1d3b50c5db6d 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -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 @@ retry:
 		/* 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 @@ retry:
 	}
 
 	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;