Re: [PATCH 5/6] FIX: mdadm hangs during reshape

[NeilBrown <neilb@suse.de>]

On Thu, 13 Jan 2011 15:50:42 +0100 Adam Kwolek <adam.kwolek@intel.com> wrote:

> During reshape when reshape is finished in md, progress_reshape() hangs
> on select(). Timeout is introduced to allow for reshape conditions check.
> 
> Signed-off-by: Adam Kwolek <adam.kwolek@intel.com>
> ---
> 
>  Grow.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/Grow.c b/Grow.c
> index f1a6218..763287b 100644
> --- a/Grow.c
> +++ b/Grow.c
> @@ -2459,6 +2459,7 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
>  		 * waiting forever on a dead array
>  		 */
>  		char action[20];
> +		struct timeval timeout;
>  		fd_set rfds;
>  		if (sysfs_get_str(info, NULL, "sync_action",
>  				  action, 20) <= 0 ||
> @@ -2466,7 +2467,9 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
>  			break;
>  		FD_ZERO(&rfds);
>  		FD_SET(fd, &rfds);
> -		select(fd+1, NULL, NULL, &rfds, NULL);
> +		timeout.tv_sec = 1;
> +		timeout.tv_usec = 0;
> +		select(fd+1, NULL, NULL, &rfds, &timeout);
>  		if (sysfs_fd_get_ll(fd, &completed) < 0) {
>  			close(fd);
>  			return -1;
> 
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Putting a timeout in here is definitely the wrong thing to do.

If you can reproduce the hang, please report the values of 
  completed, max_progress, wait_point

at that time, and the details of the array (level, devices, size, layout,
chunk size, etc).

NeilBrown