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Subject: [PATCH 2/5] netfs: Call trace_netfs_read() after
 ->begin_cache_operation()
From:   David Howells <dhowells@redhat.com>
To:     jlayton@kernel.org
Cc:     dwysocha@redhat.com, linux-cachefs@redhat.com,
        v9fs-developer@lists.sourceforge.net,
        linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org,
        ceph-devel@vger.kernel.org, linux-nfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Wed, 07 Apr 2021 16:47:31 +0100
Message-ID: <161781045123.463527.14533348855710902201.stgit@warthog.procyon.org.uk>
In-Reply-To: <161781041339.463527.18139104281901492882.stgit@warthog.procyon.org.uk>
References: <161781041339.463527.18139104281901492882.stgit@warthog.procyon.org.uk>
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Reorder the netfs library API functions slightly to log the netfs_read
tracepoint after calling out to the network filesystem to begin a caching
operation.  This sets rreq->cookie_debug_id so that it can be logged in
tracepoints.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/netfs/read_helper.c |   23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/fs/netfs/read_helper.c b/fs/netfs/read_helper.c
index 0066db21aa11..8040b76da1b6 100644
--- a/fs/netfs/read_helper.c
+++ b/fs/netfs/read_helper.c
@@ -890,15 +890,16 @@ void netfs_readahead(struct readahead_control *ractl,
 	rreq->start	= readahead_pos(ractl);
 	rreq->len	= readahead_length(ractl);
 
-	netfs_stat(&netfs_n_rh_readahead);
-	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
-			 netfs_read_trace_readahead);
-
 	if (ops->begin_cache_operation) {
 		ret = ops->begin_cache_operation(rreq);
 		if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
 			goto cleanup_free;
 	}
+
+	netfs_stat(&netfs_n_rh_readahead);
+	trace_netfs_read(rreq, readahead_pos(ractl), readahead_length(ractl),
+			 netfs_read_trace_readahead);
+
 	netfs_rreq_expand(rreq, ractl);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -968,9 +969,6 @@ int netfs_readpage(struct file *file,
 	rreq->start	= page_index(page) * PAGE_SIZE;
 	rreq->len	= thp_size(page);
 
-	netfs_stat(&netfs_n_rh_readpage);
-	trace_netfs_read(rreq, rreq->start, rreq->len, netfs_read_trace_readpage);
-
 	if (ops->begin_cache_operation) {
 		ret = ops->begin_cache_operation(rreq);
 		if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) {
@@ -979,6 +977,9 @@ 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_read_request(rreq);
 
 	atomic_set(&rreq->nr_rd_ops, 1);
@@ -1111,15 +1112,15 @@ int netfs_write_begin(struct file *file, struct address_space *mapping,
 	__set_bit(NETFS_RREQ_NO_UNLOCK_PAGE, &rreq->flags);
 	netfs_priv = NULL;
 
-	netfs_stat(&netfs_n_rh_write_begin);
-	trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
-
 	if (ops->begin_cache_operation) {
 		ret = ops->begin_cache_operation(rreq);
 		if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS)
-			goto error;
+			goto error_put;
 	}
 
+	netfs_stat(&netfs_n_rh_write_begin);
+	trace_netfs_read(rreq, pos, len, netfs_read_trace_write_begin);
+
 	/* Expand the request to meet caching requirements and download
 	 * preferences.
 	 */