Change rootfs pinning mechnism

Chane pinning mechanism: Use $rootfs/lxc.hold instead of $rootfs.hold (in case $rootfs is a mountpoint itself), but delete the file immediately after creating it (but keep it open). This will keep the root filesystem busy but does not leave any unnecessary files lying around. Signed-off-by: Christian Seiler <christian@iwakd.de> Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

Change rootfs pinning mechnism
b7ed4bf0 · Christian Seiler · Serge Hallyn · 368bbc02 · b7ed4bf0
Commit b7ed4bf0 authored Sep 12, 2013 by Christian Seiler Committed by Serge Hallyn Sep 12, 2013
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conf.c src/lxc/conf.c +8 -4

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--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -671,9 +671,10 @@ static int mount_rootfs_block(const char *rootfs, const char *target)

 /*
 * pin_rootfs
- * if rootfs is a directory, then open ${rootfs}.hold for writing for the
- * duration of the container run, to prevent the container from marking the
- * underlying fs readonly on shutdown.
+ * if rootfs is a directory, then open ${rootfs}/lxc.hold for writing for
+ * the duration of the container run, to prevent the container from marking
+ * the underlying fs readonly on shutdown. unlink the file immediately so
+ * no name pollution is happens
 * return -1 on error.
 * return -2 if nothing needed to be pinned.
 * return an open fd (>=0) if we pinned it.
@@ -700,11 +701,14 @@ int pin_rootfs(const char *rootfs)
 	if (!S_ISDIR(s.st_mode))
 		return -2;

-	ret = snprintf(absrootfspin, MAXPATHLEN, "%s%s", absrootfs, ".hold");
+	ret = snprintf(absrootfspin, MAXPATHLEN, "%s/lxc.hold", absrootfs);
 	if (ret >= MAXPATHLEN)
 		return -1;

 	fd = open(absrootfspin, O_CREAT | O_RDWR, S_IWUSR|S_IRUSR);
+	if (fd < 0)
+		return fd;
+	(void)unlink(absrootfspin);
 	return fd;
 }