Simplistig locking for --incremental.

[thirdparty/mdadm.git] / mdopen.c

diff --git a/mdopen.c b/mdopen.c
index ec34e916f8e9fdd996c88616e582f18f4aa55c2e..7f6a2ea431d81e07d6228218e9cce5c1c21489cb 100644 (file)
--- a/mdopen.c
+++ b/mdopen.c
@@ -302,6 +302,7 @@ int open_mddev_devnum(char *devname, int devnum, char *name, char *chosen_name)
         */
        int major_num, minor_num;
        struct stat stb;
+       int i;
 
        if (devname)
                strcpy(chosen_name, devname);
@@ -353,5 +354,17 @@ int open_mddev_devnum(char *devname, int devnum, char *name, char *chosen_name)
                }
                /* FIXME chown/chmod ?? */
        }
-       return open(chosen_name, O_RDWR);
+
+       /* Simple locking to avoid --incr being called for the same
+        * array multiple times in parallel.
+        */
+       for (i = 0; i < 25 ; i++) {
+               int fd;
+
+               fd = open(chosen_name, O_RDWR|O_EXCL);
+               if (fd >= 0 || errno != EBUSY)
+                       return fd;
+               usleep(200000);
+       }
+       return -1;
 }