Xiao Ni <xni@xxxxxxxxxx> wrote:
> If /etc/hostname is empty and the hostname is decided by network(dhcp, e.g.), there is a
> risk that raid device will not be in active state after boot. It will be auto-read-only
> state. It depends on the boot sequence. If the storage starts before network. The system
> detects disks first, udev rules are triggered and raid device is assemble automatically.
> But the network hasn't started successfully. So mdadm can't get the right hostname. The
> raid device will be treated as a foreign raid.
> Add a note message if /etc/hostname is empty when creating a raid device.
> Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
> ---
> mdadm.c | 3 +++
> mdadm.h | 1 +
> util.c | 19 +++++++++++++++++++
> 3 files changed, 23 insertions(+)
> diff --git a/mdadm.c b/mdadm.c
> index 1b3467f..e551958 100644
> --- a/mdadm.c
> +++ b/mdadm.c
> @@ -1408,6 +1408,9 @@ int main(int argc, char *argv[])
> if (c.homehost == NULL && c.require_homehost)
> c.homehost = conf_get_homehost(&c.require_homehost);
> if (c.homehost == NULL || strcasecmp(c.homehost, "<system>") == 0) {
> + if (check_hostname())
> + pr_err("Note: The file /etc/hostname is empty. There is a risk the raid\n"
> + " can't be active after boot\n");
> if (gethostname(sys_hostname, sizeof(sys_hostname)) == 0) {
> sys_hostname[sizeof(sys_hostname)-1] = 0;
> c.homehost = sys_hostname;
> diff --git a/mdadm.h b/mdadm.h
> index 399478b..3ef1209 100644
> --- a/mdadm.h
> +++ b/mdadm.h
> @@ -1480,6 +1480,7 @@ extern int parse_cluster_confirm_arg(char *inp, char **devname, int *slot);
> extern int check_ext2(int fd, char *name);
> extern int check_reiser(int fd, char *name);
> extern int check_raid(int fd, char *name);
> +extern int check_hostname(void);
> extern int check_partitions(int fd, char *dname,
> unsigned long long freesize,
> unsigned long long size);
> diff --git a/util.c b/util.c
> index 579dd42..de5bad0 100644
> --- a/util.c
> +++ b/util.c
> @@ -694,6 +694,25 @@ int check_raid(int fd, char *name)
> return 1;
> }
>
> +/* It checks /etc/hostname has value or not */
> +int check_hostname()
> +{
> + int fd, ret = 0;
> + char buf[256];
> +
> + fd = open("/etc/hostname", O_RDONLY);
> + if (fd < 0) {
> + ret = 1;
> + goto out;
> + }
> +
> + if (read(fd, buf, sizeof(buf)) == 0)
> + ret = 1;
Why not use stat() here, since you don't use file content?
Also, any error from read() - mean file "not empty". This is right?
> +out:
> + close(fd);
> + return ret;
> +}
> +
> int fstat_is_blkdev(int fd, char *devname, dev_t *rdev)
> {
> struct stat stb;
