[Devel] Re: [PATCH] [RFC] Checkpoint/restart eventfd

[Oren Laadan]

Matt Helsley wrote:
> Save/restore eventfd files. These are anon_inodes just like epoll
> but instead of a set of files to poll they are a 64-bit counter
> and a flag value. Used for AIO.
> 
> Signed-off-by: Matt Helsley <matthltc at us.ibm.com>

Looks fine to me, except a nit below. Unless there are negative
comments I'll pull it in a couple of days (and fix the nits).

Oren.

> 
> NOTE: Marked [RFC] because it strangely does not pass my adapted LTP
> 	test cases unless it's running from a checkpointed image.
> 	Seems to be a mistake in the test case adaptation.
> ---
>  checkpoint/files.c             |    7 +++++
>  fs/eventfd.c                   |   51 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/checkpoint_hdr.h |    8 ++++++
>  include/linux/eventfd.h        |   10 ++++++++
>  4 files changed, 76 insertions(+), 0 deletions(-)
> 
> diff --git a/checkpoint/files.c b/checkpoint/files.c
> index f6de07e..43b95cc 100644
> --- a/checkpoint/files.c
> +++ b/checkpoint/files.c
> @@ -23,6 +23,7 @@
>  #include <linux/checkpoint.h>
>  #include <linux/checkpoint_hdr.h>
>  #include <net/sock.h>
> +#include <linux/eventfd.h>
>  
>  
>  /**************************************************************************
> @@ -607,6 +608,12 @@ static struct restore_file_ops restore_file_ops[] = {
>  		.file_type = CKPT_FILE_TTY,
>  		.restore = tty_file_restore,
>  	},
> +	/* eventfd */
> +	{
> +		.file_name = "EVENTFD",
> +		.file_type = CKPT_FILE_EVENTFD,
> +		.restore = eventfd_restore,
> +	},
>  };
>  
>  static struct file *do_restore_file(struct ckpt_ctx *ctx)
> diff --git a/fs/eventfd.c b/fs/eventfd.c
> index 31d12de..5d30cd5 100644
> --- a/fs/eventfd.c
> +++ b/fs/eventfd.c
> @@ -18,6 +18,8 @@
>  #include <linux/module.h>
>  #include <linux/kref.h>
>  #include <linux/eventfd.h>
> +#include <linux/checkpoint.h>
> +#include <linux/checkpoint_hdr.h>
>  
>  struct eventfd_ctx {
>  	struct kref kref;
> @@ -223,11 +225,34 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
>  	return res;
>  }
>  
> +static int eventfd_checkpoint(struct ckpt_ctx *ckpt_ctx, struct file *file)
> +{
> +	struct eventfd_ctx *ctx;

Nit: everywhere else we use @ctx for ckpt_ctx, so to avoid
confusion, I suggest:
	struct eventfd_ctx *efd_ctx;

> +	struct ckpt_hdr_file_eventfd *h;
> +	int ret = -ENOMEM;
> +
> +	h = ckpt_hdr_get_type(ckpt_ctx, sizeof(*h), CKPT_HDR_FILE);
> +	if (!h)
> +		return -ENOMEM;
> +	h->common.f_type = CKPT_FILE_EVENTFD;
> +	ret = checkpoint_file_common(ckpt_ctx, file, &h->common);
> +	if (ret < 0)
> +		goto out;
> +	ctx = file->private_data;
> +	h->count = ctx->count;
> +	h->flags = ctx->flags;
> +	ret = ckpt_write_obj(ckpt_ctx, &h->common.h);
> +out:
> +	ckpt_hdr_put(ckpt_ctx, h);
> +	return ret;
> +}

[...]

Oren.

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