From 0ef63f345c48afe5896c5cffcba57f0457d409b9 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Date: Mon, 31 May 2010 13:22:45 +0530
Subject: net/9p: Implement attrwalk 9p call

TXATTRWALK: Descend a ATTR namespace

 size[4] TXATTRWALK tag[2] fid[4] newfid[4] name[s]
 size[4] RXATTRWALK tag[2] size[8]

txattrwalk gets a fid pointing to xattr. This fid can later be
used to read the xattr value. If name is NULL the fid returned
can be used to get the list of extended attribute associated to
the file system object.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

diff --git a/include/net/9p/9p.h b/include/net/9p/9p.h
index cf580a4..6fabb5e 100644
--- a/include/net/9p/9p.h
+++ b/include/net/9p/9p.h
@@ -153,6 +153,8 @@ enum p9_msg_t {
 	P9_RGETATTR,
 	P9_TSETATTR = 26,
 	P9_RSETATTR,
+	P9_TXATTRWALK = 30,
+	P9_RXATTRWALK,
 	P9_TREADDIR = 40,
 	P9_RREADDIR,
 	P9_TLINK = 70,
diff --git a/include/net/9p/client.h b/include/net/9p/client.h
index d755c0e..60398b1 100644
--- a/include/net/9p/client.h
+++ b/include/net/9p/client.h
@@ -260,5 +260,6 @@ void p9stat_free(struct p9_wstat *);
 
 int p9_is_proto_dotu(struct p9_client *clnt);
 int p9_is_proto_dotl(struct p9_client *clnt);
+struct p9_fid *p9_client_xattrwalk(struct p9_fid *, const char *, u64 *);
 
 #endif /* NET_9P_CLIENT_H */
diff --git a/net/9p/client.c b/net/9p/client.c
index c458e04..ec80ee7 100644
--- a/net/9p/client.c
+++ b/net/9p/client.c
@@ -1622,6 +1622,56 @@ error:
 }
 EXPORT_SYMBOL(p9_client_rename);
 
+/*
+ * An xattrwalk without @attr_name gives the fid for the lisxattr namespace
+ */
+struct p9_fid *p9_client_xattrwalk(struct p9_fid *file_fid,
+				const char *attr_name, u64 *attr_size)
+{
+	int err;
+	struct p9_req_t *req;
+	struct p9_client *clnt;
+	struct p9_fid *attr_fid;
+
+	err = 0;
+	clnt = file_fid->clnt;
+	attr_fid = p9_fid_create(clnt);
+	if (IS_ERR(attr_fid)) {
+		err = PTR_ERR(attr_fid);
+		attr_fid = NULL;
+		goto error;
+	}
+	P9_DPRINTK(P9_DEBUG_9P,
+		">>> TXATTRWALK file_fid %d, attr_fid %d name %s\n",
+		file_fid->fid, attr_fid->fid, attr_name);
+
+	req = p9_client_rpc(clnt, P9_TXATTRWALK, "dds",
+			file_fid->fid, attr_fid->fid, attr_name);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto error;
+	}
+	err = p9pdu_readf(req->rc, clnt->proto_version, "q", attr_size);
+	if (err) {
+		p9pdu_dump(1, req->rc);
+		p9_free_req(clnt, req);
+		goto clunk_fid;
+	}
+	p9_free_req(clnt, req);
+	P9_DPRINTK(P9_DEBUG_9P, "<<<  RXATTRWALK fid %d size %llu\n",
+		attr_fid->fid, *attr_size);
+	return attr_fid;
+clunk_fid:
+	p9_client_clunk(attr_fid);
+	attr_fid = NULL;
+error:
+	if (attr_fid && (attr_fid != file_fid))
+		p9_fid_destroy(attr_fid);
+
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(p9_client_xattrwalk);
+
 int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset)
 {
 	int err, rsize, total;
-- 
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