9p: Implement TGETLOCK

Synopsis

    size[4] TGetlock tag[2] fid[4] getlock[n]
    size[4] RGetlock tag[2] getlock[n]

Description

TGetlock is used to test for the existence of byte range posix locks on a file
identified by given fid. The reply contains getlock structure. If the lock could
be placed it returns F_UNLCK in type field of getlock structure.  Otherwise it
returns the details of the conflicting locks in the getlock structure

    getlock structure:
      type[1] - Type of lock: F_RDLCK, F_WRLCK
      start[8] - Starting offset for lock
      length[8] - Number of bytes to check for the lock
             If length is 0, check for lock in all bytes starting at the location
            'start' through to the end of file
      pid[4] - PID of the process that wants to take lock/owns the task
               in case of reply
      client[4] - Client id of the system that owns the process which
                  has the conflicting lock

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
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>

fs/9p/vfs_file.c

@@ -211,6 +211,51 @@ out:
 	return res;
 }
 
+static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
+{
+	struct p9_getlock glock;
+	struct p9_fid *fid;
+	int res = 0;
+
+	fid = filp->private_data;
+	BUG_ON(fid == NULL);
+
+	posix_test_lock(filp, fl);
+	/*
+	 * if we have a conflicting lock locally, no need to validate
+	 * with server
+	 */
+	if (fl->fl_type != F_UNLCK)
+		return res;
+
+	/* convert posix lock to p9 tgetlock args */
+	memset(&glock, 0, sizeof(glock));
+	glock.type = fl->fl_type;
+	glock.start = fl->fl_start;
+	if (fl->fl_end == OFFSET_MAX)
+		glock.length = 0;
+	else
+		glock.length = fl->fl_end - fl->fl_start + 1;
+	glock.proc_id = fl->fl_pid;
+	glock.client_id = utsname()->nodename;
+
+	res = p9_client_getlock_dotl(fid, &glock);
+	if (res < 0)
+		return res;
+	if (glock.type != F_UNLCK) {
+		fl->fl_type = glock.type;
+		fl->fl_start = glock.start;
+		if (glock.length == 0)
+			fl->fl_end = OFFSET_MAX;
+		else
+			fl->fl_end = glock.start + glock.length - 1;
+		fl->fl_pid = glock.proc_id;
+	} else
+		fl->fl_type = F_UNLCK;
+
+	return res;
+}
+
 /**
  * v9fs_file_lock_dotl - lock a file (or directory)
  * @filp: file to be locked
@@ -238,6 +283,8 @@ static int v9fs_file_lock_dotl(struct file *filp, int cmd, struct file_lock *fl)
 
 	if (IS_SETLK(cmd) || IS_SETLKW(cmd))
 		ret = v9fs_file_do_lock(filp, cmd, fl);
+	else if (IS_GETLK(cmd))
+		ret = v9fs_file_getlock(filp, fl);
 	else
 		ret = -EINVAL;
 out_err:

include/net/9p/9p.h

@@ -167,6 +167,8 @@ enum p9_msg_t {
 	P9_RFSYNC,
 	P9_TLOCK = 52,
 	P9_RLOCK,
+	P9_TGETLOCK = 54,
+	P9_RGETLOCK,
 	P9_TLINK = 70,
 	P9_RLINK,
 	P9_TMKDIR = 72,
@@ -492,6 +494,22 @@ struct p9_flock {
 	char *client_id;
 };
 
+/* struct p9_getlock: getlock structure
+ * @type - type of lock
+ * @start - starting offset of the lock
+ * @length - number of bytes
+ * @proc_id - process id which wants to take lock
+ * @client_id - client id
+ */
+
+struct p9_getlock {
+	u8 type;
+	u64 start;
+	u64 length;
+	u32 proc_id;
+	char *client_id;
+};
+
 /* Structures for Protocol Operations */
 struct p9_tstatfs {
 	u32 fid;

include/net/9p/client.h

@@ -250,6 +250,7 @@ int p9_client_mknod_dotl(struct p9_fid *oldfid, char *name, int mode,
 int p9_client_mkdir_dotl(struct p9_fid *fid, char *name, int mode,
 				gid_t gid, struct p9_qid *);
 int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status);
+int p9_client_getlock_dotl(struct p9_fid *fid, struct p9_getlock *fl);
 struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
 void p9_client_cb(struct p9_client *c, struct p9_req_t *req);
 

net/9p/client.c

@@ -1836,3 +1836,37 @@ error:
 
 }
 EXPORT_SYMBOL(p9_client_lock_dotl);
+
+int p9_client_getlock_dotl(struct p9_fid *fid, struct p9_getlock *glock)
+{
+	int err;
+	struct p9_client *clnt;
+	struct p9_req_t *req;
+
+	err = 0;
+	clnt = fid->clnt;
+	P9_DPRINTK(P9_DEBUG_9P, ">>> TGETLOCK fid %d, type %i start %lld "
+		"length %lld proc_id %d client_id %s\n", fid->fid, glock->type,
+		glock->start, glock->length, glock->proc_id, glock->client_id);
+
+	req = p9_client_rpc(clnt, P9_TGETLOCK, "dbqqds", fid->fid,  glock->type,
+		glock->start, glock->length, glock->proc_id, glock->client_id);
+
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	err = p9pdu_readf(req->rc, clnt->proto_version, "bqqds", &glock->type,
+			&glock->start, &glock->length, &glock->proc_id,
+			&glock->client_id);
+	if (err) {
+		p9pdu_dump(1, req->rc);
+		goto error;
+	}
+	P9_DPRINTK(P9_DEBUG_9P, "<<< RGETLOCK type %i start %lld length %lld "
+		"proc_id %d client_id %s\n", glock->type, glock->start,
+		glock->length, glock->proc_id, glock->client_id);
+error:
+	p9_free_req(clnt, req);
+	return err;
+}
+EXPORT_SYMBOL(p9_client_getlock_dotl);