During per-net pipes creation and destruction we have to make sure, that pipefs
sb exists for the whole creation/destruction cycle. This is done by using
special mutex which controls pipefs sb reference on network namespace context.
Helper consists of two parts: first of them (rpc_get_dentry_net) searches for
dentry with specified name and returns with mutex taken on success. When pipe
creation or destructions is completed, caller should release this mutex by
rpc_put_dentry_net call.
Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
---
include/linux/sunrpc/rpc_pipe_fs.h | 3 +++
net/sunrpc/netns.h | 1 +
net/sunrpc/rpc_pipe.c | 36 ++++++++++++++++++++++++++++++++++++
net/sunrpc/sunrpc_syms.c | 1 +
4 files changed, 41 insertions(+), 0 deletions(-)
diff --git a/include/linux/sunrpc/rpc_pipe_fs.h b/include/linux/sunrpc/rpc_pipe_fs.h
index 4585985..f32490c 100644
--- a/include/linux/sunrpc/rpc_pipe_fs.h
+++ b/include/linux/sunrpc/rpc_pipe_fs.h
@@ -53,6 +53,9 @@ enum {
extern struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
const unsigned char *dir_name);
+extern void rpc_pipefs_init_net(struct net *net);
+extern struct super_block *rpc_get_sb_net(const struct net *net);
+extern void rpc_put_sb_net(const struct net *net);
extern ssize_t rpc_pipe_generic_upcall(struct file *, struct rpc_pipe_msg *,
char __user *, size_t);
diff --git a/net/sunrpc/netns.h b/net/sunrpc/netns.h
index b384252..11d2f48 100644
--- a/net/sunrpc/netns.h
+++ b/net/sunrpc/netns.h
@@ -11,6 +11,7 @@ struct sunrpc_net {
struct cache_detail *ip_map_cache;
struct super_block *pipefs_sb;
+ struct mutex pipefs_sb_lock;
};
extern int sunrpc_net_id;
diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c
index 831e81d..e40ec55 100644
--- a/net/sunrpc/rpc_pipe.c
+++ b/net/sunrpc/rpc_pipe.c
@@ -1024,6 +1024,40 @@ struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
}
EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);
+void rpc_pipefs_init_net(struct net *net)
+{
+ struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+ mutex_init(&sn->pipefs_sb_lock);
+}
+
+/*
+ * This call will be used for per network namespace operations calls.
+ * Note: Function will be returned with pipefs_sb_lock taken if superblock was
+ * found. This lock have to be released by rpc_put_sb_net() when all operations
+ * will be completed.
+ */
+struct super_block *rpc_get_sb_net(const struct net *net)
+{
+ struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+ mutex_lock(&sn->pipefs_sb_lock);
+ if (sn->pipefs_sb)
+ return sn->pipefs_sb;
+ mutex_unlock(&sn->pipefs_sb_lock);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(rpc_get_sb_net);
+
+void rpc_put_sb_net(const struct net *net)
+{
+ struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+
+ BUG_ON(sn->pipefs_sb == NULL);
+ mutex_unlock(&sn->pipefs_sb_lock);
+}
+EXPORT_SYMBOL_GPL(rpc_put_sb_net);
+
static int
rpc_fill_super(struct super_block *sb, void *data, int silent)
{
@@ -1078,7 +1112,9 @@ void rpc_kill_sb(struct super_block *sb)
struct net *net = sb->s_fs_info;
struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
+ mutex_lock(&sn->pipefs_sb_lock);
sn->pipefs_sb = NULL;
+ mutex_unlock(&sn->pipefs_sb_lock);
put_net(net);
blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
RPC_PIPEFS_UMOUNT,
diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
index 8ec9778..7086d11 100644
--- a/net/sunrpc/sunrpc_syms.c
+++ b/net/sunrpc/sunrpc_syms.c
@@ -38,6 +38,7 @@ static __net_init int sunrpc_init_net(struct net *net)
if (err)
goto err_ipmap;
+ rpc_pipefs_init_net(net);
return 0;
err_ipmap:
--
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