[9p] Introduce client side TFSYNC/RFSYNC for dotl.

SYNOPSIS
    size[4] Tfsync tag[2] fid[4]

    size[4] Rfsync tag[2]

DESCRIPTION

The Tfsync transaction transfers ("flushes") all modified in-core data of
file identified by fid to the disk device (or other  permanent  storage
device)  where that  file  resides.
Signed-off-by: NVenkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>
Signed-off-by: NEric Van Hensbergen <ericvh@gmail.com>

fs/9p/vfs_file.c

@@ -290,6 +290,20 @@ static int v9fs_file_fsync(struct file *filp, int datasync)
 	return retval;
 }
 
+static int v9fs_file_fsync_dotl(struct file *filp, int datasync)
+{
+	struct p9_fid *fid;
+	int retval;
+
+	P9_DPRINTK(P9_DEBUG_VFS, "v9fs_file_fsync_dotl: filp %p datasync %x\n",
+			filp, datasync);
+
+	fid = filp->private_data;
+
+	retval = p9_client_fsync(fid);
+	return retval;
+}
+
 static const struct file_operations v9fs_cached_file_operations = {
 	.llseek = generic_file_llseek,
 	.read = do_sync_read,
@@ -311,7 +325,7 @@ static const struct file_operations v9fs_cached_file_operations_dotl = {
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock,
 	.mmap = generic_file_readonly_mmap,
-	.fsync = v9fs_file_fsync,
+	.fsync = v9fs_file_fsync_dotl,
 };
 
 const struct file_operations v9fs_file_operations = {
@@ -333,5 +347,5 @@ const struct file_operations v9fs_file_operations_dotl = {
 	.release = v9fs_dir_release,
 	.lock = v9fs_file_lock,
 	.mmap = generic_file_readonly_mmap,
-	.fsync = v9fs_file_fsync,
+	.fsync = v9fs_file_fsync_dotl,
 };

include/net/9p/9p.h

@@ -163,6 +163,8 @@ enum p9_msg_t {
 	P9_RXATTRCREATE,
 	P9_TREADDIR = 40,
 	P9_RREADDIR,
+	P9_TFSYNC = 50,
+	P9_RFSYNC,
 	P9_TLINK = 70,
 	P9_RLINK,
 	P9_TMKDIR = 72,

include/net/9p/client.h

@@ -229,6 +229,7 @@ int p9_client_symlink(struct p9_fid *fid, char *name, char *symname, gid_t gid,
 int p9_client_create_dotl(struct p9_fid *ofid, char *name, u32 flags, u32 mode,
 		gid_t gid, struct p9_qid *qid);
 int p9_client_clunk(struct p9_fid *fid);
+int p9_client_fsync(struct p9_fid *fid);
 int p9_client_remove(struct p9_fid *fid);
 int p9_client_read(struct p9_fid *fid, char *data, char __user *udata,
 							u64 offset, u32 count);

net/9p/client.c

@@ -1162,6 +1162,31 @@ int p9_client_link(struct p9_fid *dfid, struct p9_fid *oldfid, char *newname)
 }
 EXPORT_SYMBOL(p9_client_link);
 
+int p9_client_fsync(struct p9_fid *fid)
+{
+	int err;
+	struct p9_client *clnt;
+	struct p9_req_t *req;
+
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TFSYNC fid %d\n", fid->fid);
+	err = 0;
+	clnt = fid->clnt;
+
+	req = p9_client_rpc(clnt, P9_TFSYNC, "d", fid->fid);
+	if (IS_ERR(req)) {
+		err = PTR_ERR(req);
+		goto error;
+	}
+
+	P9_DPRINTK(P9_DEBUG_9P, "<<< RFSYNC fid %d\n", fid->fid);
+
+	p9_free_req(clnt, req);
+
+error:
+	return err;
+}
+EXPORT_SYMBOL(p9_client_fsync);
+
 int p9_client_clunk(struct p9_fid *fid)
 {
 	int err;