[CRIU] [PATCH 3/4] kdat: Add fetching files stat

[Andrey Vagin]

On Tue, May 30, 2017 at 09:13:32PM +0300, Cyrill Gorcunov wrote:
> Will need it to unlimit the files allocation
> for service fd reserving and later for parasite code run
> (which is implemented in vz7 instance and soon will be
> ported into vanilla).
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>  criu/include/kerndat.h |  4 +++
>  criu/kerndat.c         | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 73 insertions(+)
> 
> diff --git a/criu/include/kerndat.h b/criu/include/kerndat.h
> index da184c0542a2..2dcfd0eb75a6 100644
> --- a/criu/include/kerndat.h
> +++ b/criu/include/kerndat.h
> @@ -1,6 +1,7 @@
>  #ifndef __CR_KERNDAT_H__
>  #define __CR_KERNDAT_H__
>  
> +#include <stdbool.h>
>  #include "int.h"
>  
>  struct stat;
> @@ -14,6 +15,7 @@ extern int kerndat_init(void);
>  extern int kerndat_get_dirty_track(void);
>  extern int kerndat_fdinfo_has_lock(void);
>  extern int kerndat_loginuid(void);
> +extern int kerndat_files_stat(bool early);
>  
>  enum pagemap_func {
>  	PM_UNKNOWN,
> @@ -52,6 +54,8 @@ struct kerndat_s {
>  	bool has_nspid;
>  	bool has_ns_get_userns;
>  	bool has_ns_get_parent;
> +	unsigned int sysctl_nr_open;
> +	unsigned long files_stat_max_files;
>  };
>  
>  extern struct kerndat_s kdat;
> diff --git a/criu/kerndat.c b/criu/kerndat.c
> index 3204d4bc1d12..c37c2f1d30db 100644
> --- a/criu/kerndat.c
> +++ b/criu/kerndat.c
> @@ -149,6 +149,74 @@ static void kerndat_mmap_min_addr(void)
>  		 (unsigned long)kdat.mmap_min_addr);
>  }
>  
> +int kerndat_files_stat(bool early)
> +{
> +	static const uint32_t NR_OPEN_DEFAULT = 1024 * 1024;
> +	static const uint64_t MAX_FILES_DEFAULT = 8192;
> +	uint64_t max_files;
> +	uint32_t nr_open;
> +
> +	struct sysctl_req req[] = {
> +		{
> +			.name	= "fs/file-max",
> +			.arg	= &max_files,
> +			.type	= CTL_U64,
> +		},
> +		{
> +			.name	= "fs/nr_open",
> +			.arg	= &nr_open,
> +			.type	= CTL_U32,
> +		},
> +	};
> +
> +	if (!early) {
> +		if (sysctl_op(req, ARRAY_SIZE(req), CTL_READ, 0)) {
> +			pr_warn("Can't fetch file_stat, using kernel defaults\n");
> +			nr_open = NR_OPEN_DEFAULT;
> +			max_files = MAX_FILES_DEFAULT;
> +		}
> +	} else {
> +		char buf[64];
> +		int fd1, fd2;
> +		ssize_t ret;
> +
> +		fd1 = open("/proc/sys/fs/file-max", O_RDONLY);
> +		fd2 = open("/proc/sys/fs/nr_open", O_RDONLY);
> +
> +		nr_open = NR_OPEN_DEFAULT;
> +		max_files = MAX_FILES_DEFAULT;
> +
> +		if (fd1 < 0 || fd2 < 0) {
> +			pr_warn("Can't fetch file_stat, using kernel defaults\n");
> +		} else {
> +			ret = read(fd1, buf, sizeof(buf) - 1);
> +			if (ret > 0) {
> +				buf[ret] = '\0';
> +				max_files = atol(buf);
> +			}
> +			ret = read(fd2, buf, sizeof(buf));
> +			if (ret > 0) {
> +				buf[ret] = '\0';
> +				nr_open = atol(buf);
> +			}
> +		}
> +
> +		if (fd1 >= 0)
> +			close(fd1);
> +		if (fd2 >= 0)
> +			close(fd2);
> +	}
> +
> +	kdat.sysctl_nr_open = nr_open;
> +	kdat.files_stat_max_files = max_files;

Where do you use kdat.files_stat_max_files?
> +
> +	pr_debug("files stat: %s %lu, %s %u\n",
> +		 req[0].name, kdat.files_stat_max_files,
> +		 req[1].name, kdat.sysctl_nr_open);
> +
> +	return 0;
> +}
> +
>  static int kerndat_get_shmemdev(void)
>  {
>  	void *map;
> @@ -823,6 +891,7 @@ int kerndat_init(void)
>  
>  	kerndat_lsm();
>  	kerndat_mmap_min_addr();
> +	kerndat_files_stat(false);
>  
>  	if (!ret)
>  		kerndat_save_cache();
> -- 
> 2.7.4
>