not overwriting file_lock structure after GET_LK

If we have preventing lock, cifs should overwrite file_lock structure
with info about preventing lock. If we haven't preventing lock, cifs
should leave it unchanged except for the lock type (change it to F_UNLCK).

Signed-off-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifssmb.c

@@ -1810,8 +1810,21 @@ CIFSSMBPosixLock(const int xid, struct cifsTconInfo *tcon,
 		}
 		parm_data = (struct cifs_posix_lock *)
 			((char *)&pSMBr->hdr.Protocol + data_offset);
-		if (parm_data->lock_type == cpu_to_le16(CIFS_UNLCK))
+		if (parm_data->lock_type == __constant_cpu_to_le16(CIFS_UNLCK))
 			pLockData->fl_type = F_UNLCK;
+		else {
+			if (parm_data->lock_type ==
+					__constant_cpu_to_le16(CIFS_RDLCK))
+				pLockData->fl_type = F_RDLCK;
+			else if (parm_data->lock_type ==
+					__constant_cpu_to_le16(CIFS_WRLCK))
+				pLockData->fl_type = F_WRLCK;
+
+			pLockData->fl_start = parm_data->start;
+			pLockData->fl_end = parm_data->start +
+						parm_data->length - 1;
+			pLockData->fl_pid = parm_data->pid;
+		}
 	}
 
 plk_err_exit:

fs/cifs/file.c

@@ -838,8 +838,32 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
 
 		} else {
 			/* if rc == ERR_SHARING_VIOLATION ? */
-			rc = 0;	/* do not change lock type to unlock
-				   since range in use */
+			rc = 0;
+
+			if (lockType & LOCKING_ANDX_SHARED_LOCK) {
+				pfLock->fl_type = F_WRLCK;
+			} else {
+				rc = CIFSSMBLock(xid, tcon, netfid, length,
+					pfLock->fl_start, 0, 1,
+					lockType | LOCKING_ANDX_SHARED_LOCK,
+					0 /* wait flag */);
+				if (rc == 0) {
+					rc = CIFSSMBLock(xid, tcon, netfid,
+						length, pfLock->fl_start, 1, 0,
+						lockType |
+						LOCKING_ANDX_SHARED_LOCK,
+						0 /* wait flag */);
+					pfLock->fl_type = F_RDLCK;
+					if (rc != 0)
+						cERROR(1, ("Error unlocking "
+						"previously locked range %d "
+						"during test of lock", rc));
+					rc = 0;
+				} else {
+					pfLock->fl_type = F_WRLCK;
+					rc = 0;
+				}
+			}
 		}
 
 		FreeXid(xid);