netdev - [PATCH 5/7] net/9p: add trans_maxsize to struct p9

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Message-Id: <634f2aabd957966c7e576d769ad6bb96dbd4bfae.1631816768.git.linux_oss@crudebyte.com>
Date:   Thu, 16 Sep 2021 20:25:10 +0200
From:   Christian Schoenebeck <linux_oss@...debyte.com>
To:     v9fs-developer@...ts.sourceforge.net
Cc:     netdev@...r.kernel.org,
        Dominique Martinet <asmadeus@...ewreck.org>,
        Eric Van Hensbergen <ericvh@...il.com>,
        Latchesar Ionkov <lucho@...kov.net>,
        Greg Kurz <groug@...d.org>, Vivek Goyal <vgoyal@...hat.com>
Subject: [PATCH 5/7] net/9p: add trans_maxsize to struct p9_client

This new field 'trans_maxsize' optionally allows transport to
update it to reflect the actual maximum msize supported by
allocated transport channel.

Signed-off-by: Christian Schoenebeck <linux_oss@...debyte.com>
---
 include/net/9p/client.h |  2 ++
 net/9p/client.c         | 12 ++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index e1c308d8d288..e48c4cdf9be0 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -89,6 +89,7 @@ struct p9_req_t {
  * struct p9_client - per client instance state
  * @lock: protect @fids and @reqs
  * @msize: maximum data size negotiated by protocol
+ * @trans_maxsize: actual maximum msize supported by transport channel
  * @proto_version: 9P protocol version to use
  * @trans_mod: module API instantiated with this client
  * @status: connection state
@@ -103,6 +104,7 @@ struct p9_req_t {
 struct p9_client {
 	spinlock_t lock;
 	unsigned int msize;
+	unsigned int trans_maxsize;
 	unsigned char proto_version;
 	struct p9_trans_module *trans_mod;
 	enum p9_trans_status status;
diff --git a/net/9p/client.c b/net/9p/client.c
index fa2afeaf1394..6e699ede069e 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1037,6 +1037,14 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 		goto free_client;
 	}
 
+	/*
+	 * transport will get a chance to increase trans_maxsize (if
+	 * necessary) and it may update trans_maxsize in create() function
+	 * below accordingly to reflect the actual maximum size supported by
+	 * the allocated transport channel
+	 */
+	clnt->trans_maxsize = clnt->trans_mod->maxsize;
+
 	p9_debug(P9_DEBUG_MUX, "clnt %p trans %p msize %d protocol %d\n",
 		 clnt, clnt->trans_mod, clnt->msize, clnt->proto_version);
 
@@ -1044,8 +1052,8 @@ struct p9_client *p9_client_create(const char *dev_name, char *options)
 	if (err)
 		goto put_trans;
 
-	if (clnt->msize > clnt->trans_mod->maxsize) {
-		clnt->msize = clnt->trans_mod->maxsize;
+	if (clnt->msize > clnt->trans_maxsize) {
+		clnt->msize = clnt->trans_maxsize;
 		p9_debug(P9_DEBUG_ERROR,
 			 "Limiting 'msize' to %d as this is the maximum "
 			 "supported by transport %s\n",
-- 
2.20.1