fs/9p: add 9P2000.L renameat operation

renameat - change name of file or directory

size[4] Trenameat tag[2] olddirfid[4] oldname[s] newdirfid[4] newname[s]
size[4] Rrenameat tag[2]

older Trename have the below request format

size[4] Trename tag[2] fid[4] newdirfid[4] name[s]

The rename message is used to change the name of a file, possibly moving it
to a new directory. The rename opreation is actually a directory opertation
and should ideally have olddirfid, if not we cannot represent the fid on server
with anything other than name. We will have to derive the old directory name
from fid in the Trename request.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_inode.c

@@ -904,9 +904,12 @@ v9fs_vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 
 	down_write(&v9ses->rename_sem);
 	if (v9fs_proto_dotl(v9ses)) {
-		retval = p9_client_rename(oldfid, newdirfid,
-					(char *) new_dentry->d_name.name);
-		if (retval != -ENOSYS)
+		retval = p9_client_renameat(olddirfid, old_dentry->d_name.name,
+					    newdirfid, new_dentry->d_name.name);
+		if (retval == -EOPNOTSUPP)
+			retval = p9_client_rename(oldfid, newdirfid,
+						  new_dentry->d_name.name);
+		if (retval != -EOPNOTSUPP)
 			goto clunk_newdir;
 	}
 	if (old_dentry->d_parent != new_dentry->d_parent) {

include/net/9p/9p.h

@@ -181,6 +181,8 @@ enum p9_msg_t {
 	P9_RLINK,
 	P9_TMKDIR = 72,
 	P9_RMKDIR,
+	P9_TRENAMEAT = 74,
+	P9_RRENAMEAT,
 	P9_TVERSION = 100,
 	P9_RVERSION,
 	P9_TAUTH = 102,

include/net/9p/client.h

@@ -211,7 +211,10 @@ struct p9_dirent {
 };
 
 int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb);
-int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid, char *name);
+int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid,
+		     const char *name);
+int p9_client_renameat(struct p9_fid *olddirfid, const char *old_name,
+		       struct p9_fid *newdirfid, const char *new_name);
 struct p9_client *p9_client_create(const char *dev_name, char *options);
 void p9_client_destroy(struct p9_client *clnt);
 void p9_client_disconnect(struct p9_client *clnt);

net/9p/client.c

@@ -1666,7 +1666,8 @@ int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb)
 }
 EXPORT_SYMBOL(p9_client_statfs);
 
-int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid, char *name)
+int p9_client_rename(struct p9_fid *fid,
+		     struct p9_fid *newdirfid, const char *name)
 {
 	int err;
 	struct p9_req_t *req;
@@ -1693,6 +1694,36 @@ int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid, char *name)
 }
 EXPORT_SYMBOL(p9_client_rename);
 
+int p9_client_renameat(struct p9_fid *olddirfid, const char *old_name,
+		       struct p9_fid *newdirfid, const char *new_name)
+{
+	int err;
+	struct p9_req_t *req;
+	struct p9_client *clnt;
+
+	err = 0;
+	clnt = olddirfid->clnt;
+
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TRENAMEAT olddirfid %d old name %s"
+		   " newdirfid %d new name %s\n", olddirfid->fid, old_name,
+		   newdirfid->fid, new_name);
+
+	req = p9_client_rpc(clnt, P9_TRENAMEAT, "dsds", olddirfid->fid,
+			    old_name, newdirfid->fid, new_name);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto error;
+	}
+
+	P9_DPRINTK(P9_DEBUG_9P, "<<< RRENAMEAT newdirfid %d new name %s\n",
+		   newdirfid->fid, new_name);
+
+	p9_free_req(clnt, req);
+error:
+	return err;
+}
+EXPORT_SYMBOL(p9_client_renameat);
+
 /*
  * An xattrwalk without @attr_name gives the fid for the lisxattr namespace
  */