[CRIU] [PATCH v4 07/17] autofs: dump stage introduced

[Pavel Emelyanov]

On 01/07/2016 07:09 PM, Stanislav Kinsburskiy wrote:
> AutoFS mount point is managed by user space daemon, which receives requests
> from kernel via pipe, passed on mount operation.
> Kernel hold write end, while user space process - read end.
> Thus, for successfull AutoFS migration, this connection has to be restored.
> 
> The major trick for dump stage is that mount points are collected (parsed)
> from initial pid namespace, which leads to real pgrp value in AutoFS options
> instead of virtual one. This have to be fixed.
> 
> Note: we don't care about virtual pgrp in case of catatonic mounts
> 
> Signed-off-by: Stanislav Kinsburskiy <skinsbursky at virtuozzo.com>
> ---
>  autofs.c         |   24 ++++++++++++++++++++++++
>  include/autofs.h |    1 +
>  mount.c          |    1 +
>  3 files changed, 26 insertions(+)
> 
> diff --git a/autofs.c b/autofs.c
> index c2aafa6..1f7509f 100644
> --- a/autofs.c
> +++ b/autofs.c
> @@ -300,3 +300,27 @@ int autofs_parse(struct mount_info *pm, bool for_dump)
>  
>  	return 0;
>  }
> +
> +int autofs_dump(struct mount_info *pm)
> +{
> +	AutofsEntry *entry = pm->autofs;
> +	struct mount_info *mi;
> +
> +	if (entry->fd == AUTOFS_CATATONIC_FD)
> +		return 0;
> +
> +	/* We need to get virtual pgrp to restore mount */
> +	entry->pgrp = pid_to_virt(entry->pgrp);
> +	if (!entry->pgrp) {
> +		pr_err("failed to find pstree item with pid %d\n",
> +				entry->pgrp);
> +		pr_err("Non-catatonic mount without master?\n");
> +		return -1;
> +	}
> +
> +	/* Fix pgrp for all bind-mounts */
> +	list_for_each_entry(mi, &pm->mnt_bind, mnt_bind)
> +		mi->autofs->pgrp = entry->pgrp;

Do they all have mi->autofs? This pointer is set in dump_one_mountpoint()
and by the time you get here for the first pm, all the others still
have NULL there.

> +
> +	return 0;
> +}
> diff --git a/include/autofs.h b/include/autofs.h
> index ac7ae5e..e547f55 100644
> --- a/include/autofs.h
> +++ b/include/autofs.h
> @@ -9,5 +9,6 @@ bool is_autofs_pipe(unsigned long inode);
>  
>  struct mount_info;
>  int autofs_parse(struct mount_info *pm, bool for_dump);
> +int autofs_dump(struct mount_info *pm);
>  
>  #endif
> diff --git a/mount.c b/mount.c
> index 69c69e1..f79f991 100644
> --- a/mount.c
> +++ b/mount.c
> @@ -1699,6 +1699,7 @@ static struct fstype fstypes[32] = {
>  		.name = "autofs",
>  		.code = FSTYPE__AUTOFS,
>  		.parse = autofs_parse,
> +		.dump = autofs_dump,
>  		.restore = always_fail,
>  	},
>  };
> 
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