[CRIU] Re: [PATCH 3/3] fifo: Add checkpoint restore for fifos

Andrew Vagin avagin at parallels.com
Wed Jun 27 04:12:01 EDT 2012


Don't forget to add proper test cases to the white list in zdtm.sh

On Tue, Jun 26, 2012 at 06:49:57PM +0400, Cyrill Gorcunov wrote:
> 
> Checpoint and restore of fifo is similar to
> pipes c/r except the pipe end-points are named
> file.
> 
> Because the fifo has a name we use regular files
> facility for fifo path c/r.
> 
> Still there is a trick used to "open" fifo:
> the opening procedure migh sleep if a fifo's peer
> is not yet opened, so before doing a real open
> we yield a fake open procedure (with O_RDWR flag)
> which prevents us from sleeping even if peer
> is not yet ready.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> ---
>  Makefile            |    1 +
>  cr-dump.c           |    9 ++-
>  cr-restore.c        |    4 +
>  cr-show.c           |   40 +++++++---
>  crtools.c           |    2 +
>  fifo.c              |  212 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  files-reg.c         |    8 --
>  include/crtools.h   |    4 +
>  include/fifo.h      |   10 +++
>  include/files-reg.h |   10 +++
>  include/image.h     |    8 ++
>  11 files changed, 288 insertions(+), 20 deletions(-)
>  create mode 100644 fifo.c
>  create mode 100644 include/fifo.h
> 

> diff --git a/Makefile b/Makefile
> index 3853028..2e8df3f 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -46,6 +46,7 @@ OBJS		+= sk-queue.o
>  OBJS		+= files.o
>  OBJS		+= files-reg.o
>  OBJS		+= pipes.o
> +OBJS		+= fifo.o
>  OBJS		+= file-ids.o
>  OBJS		+= namespaces.o
>  OBJS		+= uts_ns.o
> diff --git a/cr-dump.c b/cr-dump.c
> index 0d8833e..4f66c51 100644
> --- a/cr-dump.c
> +++ b/cr-dump.c
> @@ -37,6 +37,7 @@
>  #include "files.h"
>  #include "files-reg.h"
>  #include "pipes.h"
> +#include "fifo.h"
>  #include "shmem.h"
>  #include "sk-inet.h"
>  #include "eventfd.h"
> @@ -312,8 +313,12 @@ static int dump_one_file(pid_t pid, int fd, int lfd, char fd_flags,
>  	if (S_ISREG(p.stat.st_mode) || S_ISDIR(p.stat.st_mode))
>  		return dump_reg_file(&p, lfd, cr_fdset);
>  
> -	if (S_ISFIFO(p.stat.st_mode) && (statfs.f_type == PIPEFS_MAGIC))
> -		return dump_pipe(&p, lfd, cr_fdset);
> +	if (S_ISFIFO(p.stat.st_mode)) {
> +		if (statfs.f_type == PIPEFS_MAGIC)
> +			return dump_pipe(&p, lfd, cr_fdset);
> +		else
> +			return dump_fifo(&p, lfd, cr_fdset);
> +	}
>  
>  	return dump_unsupp_fd(&p);
>  }
> diff --git a/cr-restore.c b/cr-restore.c
> index 79dadac..0459820 100644
> --- a/cr-restore.c
> +++ b/cr-restore.c
> @@ -36,6 +36,7 @@
>  #include "files.h"
>  #include "files-reg.h"
>  #include "pipes.h"
> +#include "fifo.h"
>  #include "sk-inet.h"
>  #include "eventfd.h"
>  #include "eventpoll.h"
> @@ -301,6 +302,9 @@ static int prepare_shared(void)
>  	if (collect_pipes())
>  		return -1;
>  
> +	if (collect_fifo())
> +		return -1;
> +
>  	if (collect_inet_sockets())
>  		return -1;
>  
> diff --git a/cr-show.c b/cr-show.c
> index 2b59cfe..c663fd2 100644
> --- a/cr-show.c
> +++ b/cr-show.c
> @@ -61,6 +61,7 @@ static char *fdtype2s(u8 type)
>  		[FDINFO_REG] = "reg",
>  		[FDINFO_INETSK] = "isk",
>  		[FDINFO_PIPE] = "pipe",
> +		[FDINFO_FIFO] = "fifo",
>  		[FDINFO_UNIXSK] = "usk",
>  		[FDINFO_EVENTFD] = "efd",
>  		[FDINFO_EVENTPOLL] = "epl",
> @@ -174,24 +175,23 @@ void show_ghost_file(int fd, struct cr_options *o)
>  	pr_img_tail(CR_FD_GHOST_FILE);
>  }
>  
> -void show_pipes_data(int fd_pipes, struct cr_options *o)
> +void __show_pipes_data(int fd, struct cr_options *o)
>  {
>  	struct pipe_data_entry e;
> -	int ret;
> -
> -	pr_img_head(CR_FD_PIPES_DATA);
>  
>  	while (1) {
> -		ret = read_img_eof(fd_pipes, &e);
> -		if (ret <= 0)
> -			goto out;
> +		if (read_img_eof(fd, &e) <= 0)
> +			break;
>  		pr_msg("pipeid: 0x%8x bytes: 0x%8x off: 0x%8x\n",
>  		       e.pipe_id, e.bytes, e.off);
> -
> -		lseek(fd_pipes, e.off + e.bytes, SEEK_CUR);
> +		lseek(fd, e.off + e.bytes, SEEK_CUR);
>  	}
> +}
>  
> -out:
> +void show_pipes_data(int fd_pipes, struct cr_options *o)
> +{
> +	pr_img_head(CR_FD_PIPES_DATA);
> +	__show_pipes_data(fd_pipes, o);
>  	pr_img_tail(CR_FD_PIPES_DATA);
>  }
>  
> @@ -216,6 +216,26 @@ out:
>  	pr_img_tail(CR_FD_PIPES);
>  }
>  
> +void show_fifo_data(int fd, struct cr_options *o)
> +{
> +	pr_img_head(CR_FD_FIFO_DATA);
> +	__show_pipes_data(fd, o);
> +	pr_img_tail(CR_FD_FIFO_DATA);
> +}
> +
> +void show_fifo(int fd, struct cr_options *o)
> +{
> +	struct fifo_entry e;
> +
> +	pr_img_head(CR_FD_FIFO);
> +	while (1) {
> +		if (read_img_eof(fd, &e) <= 0)
> +			break;
> +		pr_msg("id: 0x%8x pipeid: 0x%8x\n", e.id, e.pipe_id);
> +	}
> +	pr_img_tail(CR_FD_FIFO);
> +}
> +
>  void show_fs(int fd_fs, struct cr_options *o)
>  {
>  	struct fs_entry fe;
> diff --git a/crtools.c b/crtools.c
> index d4d2305..c7c8c04 100644
> --- a/crtools.c
> +++ b/crtools.c
> @@ -60,6 +60,8 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
>  	FD_ENTRY(VMAS,		"vmas-%d",	 show_vmas),
>  	FD_ENTRY(PIPES,		"pipes",	 show_pipes),
>  	FD_ENTRY(PIPES_DATA,	"pipes-data",	 show_pipes_data),
> +	FD_ENTRY(FIFO,		"fifo",		 show_fifo),
> +	FD_ENTRY(FIFO_DATA,	"fifo-data",	 show_fifo_data),
>  	FD_ENTRY(PSTREE,	"pstree",	 show_pstree),
>  	FD_ENTRY(SIGACT,	"sigacts-%d",	 show_sigacts),
>  	FD_ENTRY(UNIXSK,	"unixsk",	 show_unixsk),
> diff --git a/fifo.c b/fifo.c
> new file mode 100644
> index 0000000..6916ca0
> --- /dev/null
> +++ b/fifo.c
> @@ -0,0 +1,212 @@
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <stdlib.h>
> +
> +#include "crtools.h"
> +#include "image.h"
> +#include "files.h"
> +#include "files-reg.h"
> +#include "pipes.h"
> +
> +#include "fifo.h"
> +
> +struct fifo_info {
> +	struct list_head	list;
> +	struct file_desc	d;
> +	struct fifo_entry	fe;
> +
> +	u32			bytes;
> +	off_t			off;
> +};
> +
> +static LIST_HEAD(fifo_head);
> +
> +static int dump_one_fifo(int lfd, u32 id, const struct fd_parms *p)
> +{
> +	int img = fdset_fd(glob_fdset, CR_FD_FIFO);
> +	struct fifo_entry e;
> +
> +	/*
> +	 * It's a trick here, we use regular files dumping
> +	 * code to save path to a fifo, then we reuse it
> +	 * on restore.
> +	 */
> +	if (dump_one_reg_file(lfd, id, p))
> +		return -1;
> +
> +	pr_info("Dumping fifo %d with id %#x pipe_id %#x\n",
> +		lfd, id, (u32)p->stat.st_ino);
> +
> +	e.id		= id;
> +	e.pipe_id	= p->stat.st_ino;
> +
> +	if (write_img(img, &e) < 0)
> +		return -1;
> +
> +	return dump_one_pipe_data(CR_FD_FIFO_DATA, lfd, id, p);
> +}
> +
> +static const struct fdtype_ops fifo_ops = {
> +	.type		= FDINFO_FIFO,
> +	.make_gen_id	= make_gen_id,
> +	.dump		= dump_one_fifo,
> +};
> +
> +int dump_fifo(struct fd_parms *p, int lfd, const struct cr_fdset *set)
> +{
> +	return do_dump_gen_file(p, lfd, &fifo_ops, set);
> +}
> +
> +static int open_fifo_fd(struct file_desc *d)
> +{
> +	struct fifo_info *info = container_of(d, struct fifo_info, d);
> +	int new_fifo, fake_fifo = -1;
> +
> +	struct reg_file_info *rfi;
> +	struct file_desc *rd;
> +
> +	pr_info("\t\tCreating fifo pipe_id=%#x id=%#x\n",
> +		info->fe.pipe_id, info->fe.id);
> +
> +	rd = find_file_desc_raw(FDINFO_REG, info->fe.id);
> +	if (!rd) {
> +		pr_perror("Can't find regfile for fifo %#x\n", info->fe.id);
> +		return -1;
> +	}
> +
> +	rfi = container_of(rd, struct reg_file_info, d);
> +	if (rfi->remap_path) {
> +		if (link(rfi->remap_path, rfi->path) < 0) {
> +			pr_perror("Can't link %s -> %s\n",
> +				  rfi->remap_path, rfi->path);
> +			return -1;
> +		}
> +	} else {
> +		if (!rfi->path) {
> +			pr_err("Nil path found on regfile %#x for fifo %#x\n",
> +			       rfi->rfe.id, info->fe.id);
> +			return -1;
> +		}
> +	}
> +
> +	/*
> +	 * The fifos (except read-write fifos) do wait until
> +	 * another pipe-end get connected, so to be able to
> +	 * proceed the restoration procedure we open a fake
> +	 * fifo here.
> +	 */
> +	fake_fifo = open(rfi->path, O_RDWR);
> +	if (fake_fifo < 0) {
> +		pr_perror("Can't open fake fifo %#08x [%s]",
> +			  info->fe.id, rfi->path);
> +		return -1;
> +	}
> +
> +	new_fifo = open(rfi->path, rfi->rfe.flags);
> +	if (new_fifo < 0) {
> +		pr_perror("Can't open fifo %#08x [%s]",
> +			  info->fe.id, rfi->path);
> +		goto err_close_fake;
> +	}
> +
> +	if (restore_pipe_data(CR_FD_FIFO_DATA, fake_fifo, info->fe.id,
> +			      info->bytes, info->off))
> +		goto err_unlink;
> +
> +	if (rfi->remap_path)
> +		unlink(rfi->path);
> +
> +	if (restore_fown(new_fifo, &rfi->rfe.fown) < 0) {
> +		pr_perror("Can't restore owner on fifo %#08x",
> +			  info->fe.id);
> +		goto err_close_new;
> +	}
> +
> +err_close_fake:
> +	close_safe(&fake_fifo);
> +	return new_fifo;
> +
> +err_close_new:
> +	close_safe(&new_fifo);
> +	goto err_close_fake;
> +
> +err_unlink:
> +	if (rfi->remap_path)
> +		unlink(rfi->path);
> +	goto err_close_new;
> +}
> +
> +static struct file_desc_ops fifo_desc_ops = {
> +	.type		= FDINFO_FIFO,
> +	.open		= open_fifo_fd,
> +};
> +
> +static int handle_fifo_data(void)
> +{
> +	int img, ret;
> +
> +	img = open_image_ro(CR_FD_FIFO_DATA);
> +	if (img < 0)
> +		return -1;
> +
> +	while (1) {
> +		struct pipe_data_entry pde;
> +		struct fifo_info *info;
> +
> +		ret = read_img_eof(img, &pde);
> +		if (ret <= 0)
> +			break;
> +
> +		list_for_each_entry(info, &fifo_head, list) {
> +			if (info->fe.pipe_id != pde.pipe_id)
> +				continue;
> +
> +			info->off	= lseek(img, 0, SEEK_CUR) + pde.off;
> +			info->bytes	= pde.bytes;
> +
> +			lseek(img, pde.bytes + pde.off, SEEK_CUR);
> +			break;
> +		}
> +	}
> +
> +	close(img);
> +	return ret;
> +}
> +
> +int collect_fifo(void)
> +{
> +	struct fifo_info *info = NULL;
> +	int img, ret = -1;
> +
> +	img = open_image_ro(CR_FD_FIFO);
> +	if (img < 0)
> +		return -1;
> +
> +	while (1) {
> +		info = xmalloc(sizeof(*info));
> +		if (!info) {
> +			ret = -1;
> +			break;
> +		}
> +
> +		ret = read_img_eof(img, &info->fe);
> +		if (ret <= 0)
> +			break;
> +
> +		pr_info("Collected fifo entry ID %#x PIPE ID %#x\n",
> +			info->fe.id, info->fe.pipe_id);
> +
> +		file_desc_add(&info->d, info->fe.id, &fifo_desc_ops);
> +		list_add(&info->list, &fifo_head);
> +	}
> +
> +	if (!ret)
> +		ret = handle_fifo_data();
> +
> +	xfree(info);
> +	close(img);
> +
> +	return ret;
> +}
> diff --git a/files-reg.c b/files-reg.c
> index 9ed4db1..48268ad 100644
> --- a/files-reg.c
> +++ b/files-reg.c
> @@ -14,14 +14,6 @@
>  
>  #include "files-reg.h"
>  
> -struct reg_file_info {
> -	struct file_desc	d;
> -
> -	struct reg_file_entry	rfe;
> -	char			*remap_path;
> -	char			*path;
> -};
> -
>  struct ghost_file {
>  	struct list_head	list;
>  	u32			id;
> diff --git a/include/crtools.h b/include/crtools.h
> index 4a7875d..7c8ce3b 100644
> --- a/include/crtools.h
> +++ b/include/crtools.h
> @@ -54,6 +54,8 @@ enum {
>  	CR_FD_UNIXSK,
>  	CR_FD_PIPES,
>  	CR_FD_PIPES_DATA,
> +	CR_FD_FIFO,
> +	CR_FD_FIFO_DATA,
>  	CR_FD_REMAP_FPATH,
>  	CR_FD_EVENTFD,
>  	CR_FD_EVENTPOLL,
> @@ -104,6 +106,8 @@ void show_mm(int fd_mm, struct cr_options *o);
>  void show_vmas(int fd_vma, struct cr_options *o);
>  void show_pipes(int fd_pipes, struct cr_options *o);
>  void show_pipes_data(int fd_pipes, struct cr_options *o);
> +void show_fifo(int fd, struct cr_options *o);
> +void show_fifo_data(int fd_pipes, struct cr_options *o);
>  void show_pstree(int fd_pstree, struct cr_options *o);
>  void show_sigacts(int fd_sigacts, struct cr_options *o);
>  void show_itimers(int fd, struct cr_options *o);
> diff --git a/include/fifo.h b/include/fifo.h
> new file mode 100644
> index 0000000..031e7cf
> --- /dev/null
> +++ b/include/fifo.h
> @@ -0,0 +1,10 @@
> +#ifndef FIFO_H__
> +#define FIFO_H__
> +
> +struct fd_parms;
> +struct cr_fdset;
> +
> +extern int dump_fifo(struct fd_parms *p, int lfd, const struct cr_fdset *set);
> +extern int collect_fifo(void);
> +
> +#endif /* FIFO_H__ */
> diff --git a/include/files-reg.h b/include/files-reg.h
> index 1dc5ff5..977d260 100644
> --- a/include/files-reg.h
> +++ b/include/files-reg.h
> @@ -2,10 +2,20 @@
>  #define FILES_REG_H__
>  
>  #include "types.h"
> +#include "files.h"
> +#include "image.h"
>  
>  struct cr_fdset;
>  struct fd_parms;
>  
> +struct reg_file_info {
> +	struct file_desc	d;
> +
> +	struct reg_file_entry	rfe;
> +	char			*remap_path;
> +	char			*path;
> +};
> +
>  extern int open_reg_by_id(u32 id);
>  extern void clear_ghost_files(void);
>  extern int collect_reg_files(void);
> diff --git a/include/image.h b/include/image.h
> index 1e8dbd0..6b404a0 100644
> --- a/include/image.h
> +++ b/include/image.h
> @@ -17,6 +17,8 @@
>  #define VMAS_MAGIC		0x54123737 /* Tula */
>  #define PIPES_MAGIC		0x56513555 /* Tver */
>  #define PIPES_DATA_MAGIC	0x56453709 /* Dubna */
> +#define FIFO_MAGIC		0x58364939 /* Kirov */
> +#define FIFO_DATA_MAGIC		0x59333054 /* Tosno */
>  #define SIGACT_MAGIC		0x55344201 /* Murom */
>  #define UNIXSK_MAGIC		0x54373943 /* Ryazan */
>  #define INETSK_MAGIC		0x56443851 /* Pereslavl */
> @@ -45,6 +47,7 @@ enum fd_types {
>  	FDINFO_UND,
>  	FDINFO_REG,
>  	FDINFO_PIPE,
> +	FDINFO_FIFO,
>  	FDINFO_INETSK,
>  	FDINFO_UNIXSK,
>  	FDINFO_EVENTFD,
> @@ -162,6 +165,11 @@ struct pipe_data_entry {
>  	u8	data[0];
>  } __packed;
>  
> +struct fifo_entry {
> +	u32	id;
> +	u32	pipe_id;
> +} __packed;
> +
>  /*
>   * splice() connect cache pages to pipe buffer, so
>   * some part of pages may be loosed if data are not



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