mdmon: periodically retry to create the socket

If initial socket creation fails, EROFS, set a periodic alarm to wake up
the manager and retry.  Include a kernel patch that will wake us up if
the mount flags are changed.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/kernel-patch-2.6.27 b/kernel-patch-2.6.27
new file mode 100644 (file)
index 0000000..8d0785d
--- /dev/null
+++ b/kernel-patch-2.6.27
@@ -0,0 +1,36 @@
+touch_mnt_namespace when the mount flags change
+
+From: Dan Williams <dan.j.williams@intel.com>
+
+Daemons that need to be launched while the rootfs is read-only can now
+poll /proc/mounts to be notified when their O_RDWR requests may no
+longer end in EROFS.
+
+Cc: Kay Sievers <kay.sievers@vrfy.org>
+Cc: Neil Brown <neilb@suse.de>
+Signed-off-by: Dan Williams <dan.j.williams@intel.com>
+---
+
+ fs/namespace.c |    7 ++++++-
+ 1 files changed, 6 insertions(+), 1 deletions(-)
+
+
+diff --git a/fs/namespace.c b/fs/namespace.c
+index 6e283c9..1bd5ba2 100644
+--- a/fs/namespace.c
++++ b/fs/namespace.c
+@@ -1553,8 +1553,13 @@ static noinline int do_remount(struct nameidata *nd, int flags, int mnt_flags,
+       if (!err)
+               nd->path.mnt->mnt_flags = mnt_flags;
+       up_write(&sb->s_umount);
+-      if (!err)
++      if (!err) {
+               security_sb_post_remount(nd->path.mnt, flags, data);
++
++              spin_lock(&vfsmount_lock);
++              touch_mnt_namespace(nd->path.mnt->mnt_ns);
++              spin_unlock(&vfsmount_lock);
++      }
+       return err;
+ }
+ 

diff --git a/managemon.c b/managemon.c
index dc3ff7f2f0edd9abbc4fedb7fee827b645aad39a..730334cd6d278a2770caeebb6e52d0185f256b63 100644 (file)
--- a/managemon.c
+++ b/managemon.c
@@ -606,10 +606,13 @@ void do_manager(struct supertype *container)
 {
        struct mdstat_ent *mdstat;
        sigset_t set;
+       int proc_fd;
 
        sigprocmask(SIG_UNBLOCK, NULL, &set);
        sigdelset(&set, SIGUSR1);
        sigdelset(&set, SIGHUP);
+       sigdelset(&set, SIGALRM);
+       proc_fd = open("/proc/mounts", O_RDONLY);
 
        do {
 
@@ -627,12 +630,14 @@ void do_manager(struct supertype *container)
 
                        read_sock(container);
 
-                       if (socket_hup_requested) {
+                       if (container->sock < 0 || socket_hup_requested) {
                                close(container->sock);
                                container->sock = make_control_sock(container->devname);
                                make_pidfile(container->devname, 0);
                                socket_hup_requested = 0;
                        }
+                       if (container->sock < 0)
+                               alarm(30);
 
                        free_mdstat(mdstat);
                }
@@ -642,9 +647,12 @@ void do_manager(struct supertype *container)
 
                manager_ready = 1;
 
-               if (update_queue == NULL)
-                       mdstat_wait_fd(container->sock, &set);
-               else
+               if (update_queue == NULL) {
+                       if (container->sock < 0)
+                               mdstat_wait_fd(proc_fd, &set);
+                       else
+                               mdstat_wait_fd(container->sock, &set);
+               } else
                        /* If an update is happening, just wait for signal */
                        pselect(0, NULL, NULL, NULL, NULL, &set);
        } while(1);

diff --git a/mdmon.c b/mdmon.c
index 3f5edbba78574db6efb5e4ff6cb602106ac35983..28b01398f715ed55c7675f51594747f8c3c50fc0 100644 (file)
--- a/mdmon.c
+++ b/mdmon.c
@@ -282,8 +282,6 @@ int main(int argc, char *argv[])
        }
 
        container->sock = make_control_sock(container->devname);
-       if (container->sock < 0)
-               fprintf(stderr, "mdmon: Cannot create socket in /var/run/mdadm\n");
        container->arrays = NULL;
 
        mdi = sysfs_read(mdfd, container->devnum,
@@ -356,10 +354,12 @@ int main(int argc, char *argv[])
        sigemptyset(&set);
        sigaddset(&set, SIGUSR1);
        sigaddset(&set, SIGHUP);
+       sigaddset(&set, SIGALRM);
        sigprocmask(SIG_BLOCK, &set, NULL);
        act.sa_handler = wake_me;
        act.sa_flags = 0;
        sigaction(SIGUSR1, &act, NULL);
+       sigaction(SIGALRM, &act, NULL);
        act.sa_handler = hup;
        sigaction(SIGHUP, &act, NULL);
        act.sa_handler = SIG_IGN;