SUNRPC: pipefs per-net operations helper introduced
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@parallels.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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@ -53,6 +53,9 @@ enum {
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extern struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
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const unsigned char *dir_name);
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extern void rpc_pipefs_init_net(struct net *net);
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extern struct super_block *rpc_get_sb_net(const struct net *net);
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extern void rpc_put_sb_net(const struct net *net);
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extern ssize_t rpc_pipe_generic_upcall(struct file *, struct rpc_pipe_msg *,
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char __user *, size_t);
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@ -11,6 +11,7 @@ struct sunrpc_net {
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struct cache_detail *ip_map_cache;
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struct super_block *pipefs_sb;
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struct mutex pipefs_sb_lock;
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};
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extern int sunrpc_net_id;
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@ -1023,6 +1023,40 @@ struct dentry *rpc_d_lookup_sb(const struct super_block *sb,
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}
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EXPORT_SYMBOL_GPL(rpc_d_lookup_sb);
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void rpc_pipefs_init_net(struct net *net)
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{
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struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
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mutex_init(&sn->pipefs_sb_lock);
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}
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/*
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* This call will be used for per network namespace operations calls.
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* Note: Function will be returned with pipefs_sb_lock taken if superblock was
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* found. This lock have to be released by rpc_put_sb_net() when all operations
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* will be completed.
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*/
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struct super_block *rpc_get_sb_net(const struct net *net)
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{
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struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
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mutex_lock(&sn->pipefs_sb_lock);
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if (sn->pipefs_sb)
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return sn->pipefs_sb;
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mutex_unlock(&sn->pipefs_sb_lock);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(rpc_get_sb_net);
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void rpc_put_sb_net(const struct net *net)
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{
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struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
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BUG_ON(sn->pipefs_sb == NULL);
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mutex_unlock(&sn->pipefs_sb_lock);
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}
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EXPORT_SYMBOL_GPL(rpc_put_sb_net);
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static int
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rpc_fill_super(struct super_block *sb, void *data, int silent)
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{
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@ -1077,7 +1111,9 @@ void rpc_kill_sb(struct super_block *sb)
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struct net *net = sb->s_fs_info;
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struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
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mutex_lock(&sn->pipefs_sb_lock);
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sn->pipefs_sb = NULL;
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mutex_unlock(&sn->pipefs_sb_lock);
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put_net(net);
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blocking_notifier_call_chain(&rpc_pipefs_notifier_list,
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RPC_PIPEFS_UMOUNT,
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@ -38,6 +38,7 @@ static __net_init int sunrpc_init_net(struct net *net)
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if (err)
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goto err_ipmap;
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rpc_pipefs_init_net(net);
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return 0;
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err_ipmap:
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