Re: [PATCH] xfs_io: add sync and syncfs commands

[Brian Foster <bfoster@redhat.com>]

On Fri, Oct 24, 2014 at 01:06:09PM -0500, Eric Sandeen wrote:
> There's no easy way to invoke syncfs from the commandline,
> as far as I know, so add it to xfs_io to be handy.
> 
> Add sync while we're at it, just for completeness.
> 
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
> 
> diff --git a/configure.ac b/configure.ac
> index ae17c68..bf0c205 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -111,6 +111,7 @@ AC_HAVE_FALLOCATE
>  AC_HAVE_FIEMAP
>  AC_HAVE_PREADV
>  AC_HAVE_SYNC_FILE_RANGE
> +AC_HAVE_SYNCFS
>  AC_HAVE_BLKID_TOPO($enable_blkid)
>  AC_HAVE_READDIR
>  
> diff --git a/include/builddefs.in b/include/builddefs.in
> index 944bcf6..b8bde5f 100644
> --- a/include/builddefs.in
> +++ b/include/builddefs.in
> @@ -103,6 +103,7 @@ HAVE_FALLOCATE = @have_fallocate@
>  HAVE_FIEMAP = @have_fiemap@
>  HAVE_PREADV = @have_preadv@
>  HAVE_SYNC_FILE_RANGE = @have_sync_file_range@
> +HAVE_SYNCFS = @have_syncfs@
>  HAVE_READDIR = @have_readdir@
>  
>  GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall 
> diff --git a/io/Makefile b/io/Makefile
> index c16af87..82593a6 100644
> --- a/io/Makefile
> +++ b/io/Makefile
> @@ -11,7 +11,7 @@ HFILES = init.h io.h
>  CFILES = init.c \
>  	attr.c bmap.c file.c freeze.c fsync.c getrusage.c imap.c link.c \
>  	mmap.c open.c parent.c pread.c prealloc.c pwrite.c seek.c shutdown.c \
> -	truncate.c
> +	sync.c truncate.c
>  
>  LLDLIBS = $(LIBXCMD) $(LIBHANDLE)
>  LTDEPENDENCIES = $(LIBXCMD) $(LIBHANDLE)
> @@ -64,6 +64,10 @@ CFILES += sync_file_range.c
>  LCFLAGS += -DHAVE_SYNC_FILE_RANGE
>  endif
>  
> +ifeq ($(HAVE_SYNCFS),yes)
> +LCFLAGS += -DHAVE_SYNCFS
> +endif
> +
>  ifeq ($(ENABLE_READLINE),yes)
>  LLDLIBS += $(LIBREADLINE) $(LIBTERMCAP)
>  endif
> diff --git a/io/init.c b/io/init.c
> index bfc35bf..1b07518 100644
> --- a/io/init.c
> +++ b/io/init.c
> @@ -80,8 +80,9 @@ init_commands(void)
>  	resblks_init();
>  	sendfile_init();
>  	shutdown_init();
> -	truncate_init();
> +	sync_init();
>  	sync_range_init();
> +	truncate_init();
>  }
>  
>  static int
> diff --git a/io/io.h b/io/io.h
> index 1b3bca1..db8b513 100644
> --- a/io/io.h
> +++ b/io/io.h
> @@ -109,6 +109,7 @@ extern void		pwrite_init(void);
>  extern void		quit_init(void);
>  extern void		seek_init(void);
>  extern void		shutdown_init(void);
> +extern void		sync_init(void);
>  extern void		truncate_init(void);
>  
>  #ifdef HAVE_FADVISE
> diff --git a/io/sync.c b/io/sync.c
> new file mode 100644
> index 0000000..a6c6215
> --- /dev/null
> +++ b/io/sync.c
> @@ -0,0 +1,70 @@
> +/*
> + * Copyright (c) 2014 Red Hat, Inc.
> + * All Rights Reserved.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it would be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write the Free Software Foundation,
> + * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> + */
> +
> +#include <xfs/xfs.h>
> +#include <xfs/command.h>
> +#include "init.h"
> +#include "io.h"
> +
> +static cmdinfo_t sync_cmd;
> +
> +static int
> +sync_f(
> +	int			argc,
> +	char			**argv)
> +{
> +	/* sync can't fail */
> +	sync();
> +	return 0;
> +}
> +
> +#ifdef HAVE_SYNCFS
> +static cmdinfo_t syncfs_cmd;
> +
> +static int
> +syncfs_f(
> +	int			argc,
> +	char			**argv)
> +{
> +	/* syncfs can't fail */
> +	syncfs(file->fd);
> +	return 0;
> +}
> +#endif
> +
> +void
> +sync_init(void)
> +{
> +	sync_cmd.name = "sync";
> +	sync_cmd.cfunc = sync_f;
> +	sync_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;

Not a big deal given that we have sync(1), but CMD_NOFILE_OK..?

The rest looks good to me.

Brian

> +	sync_cmd.oneline =
> +		_("calls sync(2) to flush all in-core filesystem state to disk");
> +
> +	add_command(&sync_cmd);
> +
> +#ifdef HAVE_SYNCFS
> +	syncfs_cmd.name = "syncfs";
> +	syncfs_cmd.cfunc = syncfs_f;
> +	syncfs_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
> +	syncfs_cmd.oneline =
> +		_("calls syncfs(2) to flush all in-core filesystem state to disk");
> +
> +	add_command(&syncfs_cmd);
> +#endif
> +}
> diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> index 8267ba0..51182e4 100644
> --- a/m4/package_libcdev.m4
> +++ b/m4/package_libcdev.m4
> @@ -171,6 +171,23 @@ AC_DEFUN([AC_HAVE_SYNC_FILE_RANGE],
>    ])
>  
>  #
> +# Check if we have a syncfs libc call (Linux)
> +#
> +AC_DEFUN([AC_HAVE_SYNCFS],
> +  [ AC_MSG_CHECKING([for syncfs])
> +    AC_TRY_LINK([
> +#define _GNU_SOURCE
> +#define _FILE_OFFSET_BITS 64
> +#include <unistd.h>
> +    ], [
> +         syncfs(0);
> +    ], have_syncfs=yes
> +       AC_MSG_RESULT(yes),
> +       AC_MSG_RESULT(no))
> +    AC_SUBST(have_syncfs)
> +  ])
> +
> +#
>  # Check if we have a readdir libc call
>  #
>  AC_DEFUN([AC_HAVE_READDIR],
> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> index e40fbf9..cf27b99 100644
> --- a/man/man8/xfs_io.8
> +++ b/man/man8/xfs_io.8
> @@ -362,6 +362,16 @@ start writeback of dirty data in the given range (SYNC_FILE_RANGE_WRITE).
>  .RE
>  .PD
>  .TP
> +.B sync
> +Calls
> +.BR sync (2)
> +to flush all filesystems' in-core data to disk.
> +.TP
> +.B syncfs
> +Calls
> +.BR syncfs (2)
> +to flush this filesystem's in-core data to disk.
> +.TP
>  .BI resvsp " offset length"
>  Allocates reserved, unwritten space for part of a file using the
>  XFS_IOC_RESVSP system call described in the
> 
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