[PATCH 8/10] 9p: loopback transport

From: Latchesar Ionkov
Date: Fri Nov 02 2007 - 13:07:30 EST

9P loopback transport that can be used between 9P in-kernel servers and v9fs
on the same machine.

Signed-off-by: Latchesar Ionkov <lucho@xxxxxxxxxx>

---
net/9p/Kconfig | 7 +
net/9p/Makefile | 4 +
net/9p/trans_loop.c | 371 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 382 insertions(+), 0 deletions(-)

diff --git a/net/9p/Kconfig b/net/9p/Kconfig
index 979c781..ae341f0 100644
--- a/net/9p/Kconfig
+++ b/net/9p/Kconfig
@@ -23,6 +23,13 @@ config NET_9P_FD
file descriptors. TCP/IP is the default transport for 9p,
so if you are going to use 9p, you'll likely want this.

+config NET_9P_LOOP
+ depends on NET_9P
+ default y if NET_9P
+ tristate "9P Loopback Transport (Experimental)"
+ help
+ Loopback transport.
+
config NET_9P_DEBUG
bool "Debug information"
depends on NET_9P
diff --git a/net/9p/Makefile b/net/9p/Makefile
index d143e4a..da05d35 100644
--- a/net/9p/Makefile
+++ b/net/9p/Makefile
@@ -1,5 +1,6 @@
obj-$(CONFIG_NET_9P) := 9pnet.o
obj-$(CONFIG_NET_9P_FD) += 9pnet_fd.o
+obj-$(CONFIG_NET_9P_LOOP) += 9pnet_loop.o
obj-$(CONFIG_NET_9P_SRV) += 9psrv.o

9pnet-objs := \
@@ -10,6 +11,9 @@ obj-$(CONFIG_NET_9P_SRV) += 9psrv.o
fcprint.o \
util.o \

+9pnet_loop-objs := \
+ trans_loop.o \
+
9psrv-objs := \
srv.o \

diff --git a/net/9p/trans_loop.c b/net/9p/trans_loop.c
new file mode 100644
index 0000000..7e7793b
--- /dev/null
+++ b/net/9p/trans_loop.c
@@ -0,0 +1,371 @@
+/*
+ * linux/fs/9p/trans_fd.c
+ *
+ * Loopback transport. Used for testing.
+ *
+ * Copyright (C) 2007 by Latchesar Ionkov <lucho@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to:
+ * Free Software Foundation
+ * 51 Franklin Street, Fifth Floor
+ * Boston, MA 02111-1301 USA
+ *
+ */
+
+#include <linux/in.h>
+#include <linux/module.h>
+#include <linux/net.h>
+#include <linux/ipv6.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/un.h>
+#include <linux/uaccess.h>
+#include <linux/inet.h>
+#include <linux/idr.h>
+#include <linux/file.h>
+#include <linux/parser.h>
+#include <net/9p/9p.h>
+#include <net/9p/transport.h>
+
+struct p9_trans_loop {
+ spinlock_t lock;
+ char *name;
+ struct p9_trans *ctrans;
+ struct p9_trans *strans;
+ struct p9_trans_listener listener;
+ struct list_head trans_list;
+};
+
+struct p9_loop_opts {
+ char *name;
+};
+
+static struct p9_trans *p9lo_clt_create(const char *, char *);
+static void p9lo_clt_request(struct p9_trans *, struct p9_trans_req *);
+static int p9lo_clt_cancel(struct p9_trans *, struct p9_trans_req *);
+static void p9lo_clt_destroy(struct p9_trans *);
+static int p9lo_srv_create(struct p9_trans_loop *lt);
+static void p9lo_srv_destroy(struct p9_trans *);
+static int p9lo_srv_cancel(struct p9_trans *, struct p9_trans_req *);
+static void p9lo_srv_respond(struct p9_trans *, struct p9_trans_req *);
+static struct p9_trans_listener *p9lo_listener_create(char *);
+static void p9lo_trans_listener_destroy(struct p9_trans_listener *);
+
+static struct p9_trans_module p9lo_trans_mod = {
+ .name = "loop",
+ .maxsize = 65536,
+ .def = 0,
+ .create_client = p9lo_clt_create,
+ .create_listener = p9lo_listener_create,
+};
+
+enum {
+ Opt_name, Opt_err,
+};
+
+static match_table_t tokens = {
+ {Opt_name, "name=%s"},
+ {Opt_err, NULL},
+};
+
+static DEFINE_MUTEX(p9lo_lock);
+static LIST_HEAD(p9lo_trans_list);
+
+static void parse_opts(char *options, struct p9_loop_opts *opts)
+{
+ int token;
+ char *p;
+ substring_t args[MAX_OPT_ARGS];
+
+ opts->name = NULL;
+ if (!options)
+ return;
+
+ while ((p = strsep(&options, ",")) != NULL) {
+ if (*p == '\0')
+ continue;
+
+ token = match_token(p, tokens, args);
+ switch (token) {
+ case Opt_name:
+ opts->name = match_strdup(&args[0]);
+ break;
+ default:
+ continue;
+ }
+ }
+}
+
+static struct p9_trans_loop *p9lo_trans_find(char *name)
+{
+ struct p9_trans_loop *lo;
+
+ mutex_lock(&p9lo_lock);
+ list_for_each_entry(lo, &p9lo_trans_list, trans_list) {
+ if (!strcmp(name, lo->name)) {
+ mutex_unlock(&p9lo_lock);
+ return lo;
+ }
+ }
+ mutex_unlock(&p9lo_lock);
+ return ERR_PTR(-ENOENT);
+}
+
+static struct p9_trans_loop *p9lo_trans_create(char *name)
+{
+ struct p9_trans_loop *lo;
+
+ mutex_lock(&p9lo_lock);
+ list_for_each_entry(lo, &p9lo_trans_list, trans_list) {
+ if (!strcmp(name, lo->name)) {
+ mutex_unlock(&p9lo_lock);
+ return ERR_PTR(-EEXIST);
+ }
+ }
+
+ lo = kmalloc(sizeof(*lo) + strlen(name) + 1, GFP_KERNEL);
+ spin_lock_init(&lo->lock);
+ lo->name = (char *) lo + sizeof(*lo);
+ strcpy(lo->name, name);
+ lo->ctrans = NULL;
+ lo->strans = NULL;
+ lo->listener.err = 0;
+ lo->listener.aux = NULL;
+ lo->listener.taux = lo;
+ lo->listener.newtrans = NULL;
+ lo->listener.destroy = p9lo_trans_listener_destroy;
+ list_add_tail(&lo->trans_list, &p9lo_trans_list);
+ mutex_unlock(&p9lo_lock);
+
+ P9_DPRINTK(P9_DEBUG_TRANS, "trans %p\n", lo);
+ return lo;
+}
+
+static void p9lo_trans_destroy(struct p9_trans_loop *lo)
+{
+ if (lo->ctrans || lo->strans || !list_empty(&lo->trans_list))
+ return;
+
+ kfree(lo);
+}
+
+static struct p9_trans *p9lo_clt_create(const char *devname, char *options)
+{
+ int err;
+ struct p9_trans *ctrans;
+ struct p9_trans_loop *lt;
+ struct p9_loop_opts opts;
+
+ parse_opts(options, &opts);
+ if (!opts.name)
+ return ERR_PTR(-ENOENT);
+
+ lt = p9lo_trans_find(opts.name);
+ if (IS_ERR(lt))
+ return (struct p9_trans *) lt;
+
+ ctrans = kmalloc(sizeof(*ctrans), GFP_KERNEL);
+ if (!ctrans)
+ return ERR_PTR(-ENOMEM);
+
+ ctrans->err = 0;
+ ctrans->priv = lt;
+ ctrans->request = p9lo_clt_request;
+ ctrans->cancel = p9lo_clt_cancel;
+ ctrans->destroy = p9lo_clt_destroy;
+
+ spin_lock(&lt->lock);
+ if (lt->ctrans || lt->strans) {
+ spin_unlock(&lt->lock);
+ kfree(ctrans);
+ return ERR_PTR(-EEXIST);
+ }
+
+ lt->ctrans = ctrans;
+ spin_unlock(&lt->lock);
+
+ err = p9lo_srv_create(lt);
+ if (err) {
+ spin_lock(&lt->lock);
+ lt->ctrans = NULL;
+ spin_unlock(&lt->lock);
+ kfree(ctrans);
+ return ERR_PTR(err);
+ }
+
+ P9_DPRINTK(P9_DEBUG_TRANS, "trans %p ctrans %p\n", ctrans->priv,
+ ctrans);
+
+ return ctrans;
+}
+
+static void p9lo_clt_destroy(struct p9_trans *ctrans)
+{
+ struct p9_trans_loop *lt;
+
+ lt = ctrans->priv;
+ spin_lock(&lt->lock);
+ lt->ctrans = NULL;
+ if (lt->strans)
+ lt->strans->err = -EIO;
+ spin_unlock(&lt->lock);
+
+ if (lt->strans)
+ (*lt->strans->request)(lt->strans, NULL);
+
+ p9lo_trans_destroy(lt);
+}
+
+static void p9lo_clt_request(struct p9_trans *trans, struct p9_trans_req *creq)
+{
+ struct p9_trans_req *sreq;
+ struct p9_trans_loop *lt;
+
+ lt = trans->priv;
+ P9_DPRINTK(P9_DEBUG_TRANS, "trans %p ctrans %p\n", lt, trans);
+ sreq = kmalloc(sizeof(*sreq), GFP_KERNEL);
+ sreq->tag = creq->tag;
+ sreq->err = 0;
+ sreq->tc = creq->tc;
+ sreq->rc = creq->rc;
+ sreq->cb = p9lo_srv_respond;
+ sreq->cba = NULL;
+ sreq->aux = creq;
+ INIT_LIST_HEAD(&sreq->req_list);
+
+ spin_lock(&lt->lock);
+ if (!lt->strans) {
+ lt->strans->err = -EIO;
+ spin_unlock(&lt->lock);
+ return;
+ }
+ spin_unlock(&lt->lock);
+
+ (*lt->strans->request)(lt->strans, sreq);
+}
+
+static int p9lo_clt_cancel(struct p9_trans *trans, struct p9_trans_req *req)
+{
+ return 0;
+}
+
+static int p9lo_srv_create(struct p9_trans_loop *lt)
+{
+ struct p9_trans *strans;
+
+ strans = kmalloc(sizeof(*strans), GFP_KERNEL);
+ if (!strans)
+ return -ENOMEM;
+
+ strans->err = 0;
+ strans->priv = lt;
+ strans->request = NULL;
+ strans->cancel = p9lo_srv_cancel;
+ strans->destroy = p9lo_srv_destroy;
+
+ spin_lock(&lt->lock);
+ if (lt->strans) {
+ spin_unlock(&lt->lock);
+ kfree(strans);
+ return -EEXIST;
+ }
+
+ lt->strans = strans;
+ spin_unlock(&lt->lock);
+
+ P9_DPRINTK(P9_DEBUG_TRANS, "trans %p strans %p\n", strans->priv,
+ strans);
+
+ (*lt->listener.newtrans)(&lt->listener, strans);
+ return 0;
+}
+
+static void p9lo_srv_destroy(struct p9_trans *strans)
+{
+ struct p9_trans_loop *trans;
+
+ trans = strans->priv;
+ spin_lock(&trans->lock);
+ trans->strans = NULL;
+ if (trans->ctrans)
+ trans->ctrans->err = -EIO;
+ spin_unlock(&trans->lock);
+}
+
+static int p9lo_srv_cancel(struct p9_trans *trans, struct p9_trans_req *req)
+{
+ return 0;
+}
+
+static void p9lo_srv_respond(struct p9_trans *trans, struct p9_trans_req *sreq)
+{
+ struct p9_trans_loop *t;
+ struct p9_trans_req *creq;
+
+ t = trans->priv;
+ creq = sreq->aux;
+
+ if (sreq->rc != creq->rc) {
+ kfree(creq->rc);
+ creq->rc = sreq->rc;
+ }
+
+ kfree(sreq);
+ P9_DPRINTK(P9_DEBUG_TRANS, "id %d size %d\n", creq->rc->id, creq->rc->size);
+ (*creq->cb)(t->ctrans, creq);
+}
+
+static struct p9_trans_listener *p9lo_listener_create(char *options)
+{
+ struct p9_trans_loop *lt;
+ struct p9_loop_opts opts;
+
+ parse_opts(options, &opts);
+ if (!opts.name)
+ return ERR_PTR(-ENOENT);
+
+ lt = p9lo_trans_create(opts.name);
+ if (IS_ERR(lt))
+ return (struct p9_trans_listener *) lt;
+
+ return &lt->listener;
+}
+
+static void p9lo_trans_listener_destroy(struct p9_trans_listener *lis)
+{
+ struct p9_trans_loop *lt;
+
+ lt = lis->taux;
+ mutex_lock(&p9lo_lock);
+ list_del(&lt->trans_list);
+ mutex_unlock(&p9lo_lock);
+ p9lo_trans_destroy(lt);
+}
+
+static int __init p9lo_init(void)
+{
+ v9fs_register_trans(&p9lo_trans_mod);
+
+ return 1;
+}
+
+static void __exit p9lo_exit(void) {
+ printk(KERN_ERR "Removal of 9p transports not implemented\n");
+ BUG();
+}
+
+module_init(p9lo_init);
+module_exit(p9lo_exit);
+
+MODULE_AUTHOR("Latchesar Ionkov <lucho@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
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