Re: [PATCH 3/4] xfs_io: make ls/chattr work with special files

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Aug 08, 2025 at 09:30:18PM +0200, Andrey Albershteyn wrote:
> From: Andrey Albershteyn <aalbersh@redhat.com>
> 
> With new file_getattr/file_setattr syscalls we can now list/change file
> attributes on special files instead for ignoring them.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> ---
>  io/attr.c | 130 ++++++++++++++++++++++++++++++++++++--------------------------
>  1 file changed, 75 insertions(+), 55 deletions(-)
> 
> diff --git a/io/attr.c b/io/attr.c
> index fd82a2e73801..1cce602074f4 100644
> --- a/io/attr.c
> +++ b/io/attr.c
> @@ -8,6 +8,7 @@
>  #include "input.h"
>  #include "init.h"
>  #include "io.h"
> +#include "libfrog/file_attr.h"
>  
>  static cmdinfo_t chattr_cmd;
>  static cmdinfo_t lsattr_cmd;
> @@ -156,36 +157,35 @@ lsattr_callback(
>  	int			status,
>  	struct FTW		*data)
>  {
> -	struct fsxattr		fsx;
> -	int			fd;
> +	struct file_attr	fa;
> +	int			error;
>  
>  	if (recurse_dir && !S_ISDIR(stat->st_mode))
>  		return 0;
>  
> -	if ((fd = open(path, O_RDONLY)) == -1) {
> -		fprintf(stderr, _("%s: cannot open %s: %s\n"),
> -			progname, path, strerror(errno));
> -		exitcode = 1;
> -	} else if ((xfsctl(path, fd, FS_IOC_FSGETXATTR, &fsx)) < 0) {
> +	error = file_getattr(AT_FDCWD, path, stat, &fa, AT_SYMLINK_NOFOLLOW);
> +	if (error) {
>  		fprintf(stderr, _("%s: cannot get flags on %s: %s\n"),
>  			progname, path, strerror(errno));
>  		exitcode = 1;
> -	} else
> -		printxattr(fsx.fsx_xflags, 0, 1, path, 0, 1);
> +		return 0;
> +	}
> +
> +	printxattr(fa.fa_xflags, 0, 1, path, 0, 1);

Maybe it's time to rename this printxflags or something that's less
easily confused with extended attributes...

>  
> -	if (fd != -1)
> -		close(fd);
>  	return 0;
>  }
>  
>  static int
>  lsattr_f(
> -	int		argc,
> -	char		**argv)
> +	int			argc,
> +	char			**argv)
>  {
> -	struct fsxattr	fsx;
> -	char		*name = file->name;
> -	int		c, aflag = 0, vflag = 0;
> +	struct file_attr	fa;
> +	char			*name = file->name;
> +	int			c, aflag = 0, vflag = 0;
> +	struct stat		st;
> +	int			error;
>  
>  	recurse_all = recurse_dir = 0;
>  	while ((c = getopt(argc, argv, "DRav")) != EOF) {
> @@ -211,17 +211,27 @@ lsattr_f(
>  	if (recurse_all || recurse_dir) {
>  		nftw(name, lsattr_callback,
>  			100, FTW_PHYS | FTW_MOUNT | FTW_DEPTH);
> -	} else if ((xfsctl(name, file->fd, FS_IOC_FSGETXATTR, &fsx)) < 0) {
> +		return 0;
> +	}
> +
> +	error = stat(name, &st);
> +	if (error)
> +		return error;
> +
> +	error = file_getattr(AT_FDCWD, name, &st, &fa, AT_SYMLINK_NOFOLLOW);
> +	if (error) {
>  		fprintf(stderr, _("%s: cannot get flags on %s: %s\n"),
>  			progname, name, strerror(errno));
>  		exitcode = 1;
> -	} else {
> -		printxattr(fsx.fsx_xflags, vflag, !aflag, name, vflag, !aflag);
> -		if (aflag) {
> -			fputs("/", stdout);
> -			printxattr(-1, 0, 1, name, 0, 1);
> -		}
> +		return 0;
>  	}
> +
> +	printxattr(fa.fa_xflags, vflag, !aflag, name, vflag, !aflag);
> +	if (aflag) {
> +		fputs("/", stdout);
> +		printxattr(-1, 0, 1, name, 0, 1);
> +	}
> +
>  	return 0;
>  }
>  
> @@ -232,44 +242,43 @@ chattr_callback(
>  	int			status,
>  	struct FTW		*data)
>  {
> -	struct fsxattr		attr;
> -	int			fd;
> +	struct file_attr	attr;
> +	int			error;
>  
>  	if (recurse_dir && !S_ISDIR(stat->st_mode))
>  		return 0;
>  
> -	if ((fd = open(path, O_RDONLY)) == -1) {
> -		fprintf(stderr, _("%s: cannot open %s: %s\n"),
> -			progname, path, strerror(errno));
> -		exitcode = 1;
> -	} else if (xfsctl(path, fd, FS_IOC_FSGETXATTR, &attr) < 0) {
> +	error = file_getattr(AT_FDCWD, path, stat, &attr, AT_SYMLINK_NOFOLLOW);
> +	if (error) {
>  		fprintf(stderr, _("%s: cannot get flags on %s: %s\n"),
>  			progname, path, strerror(errno));
>  		exitcode = 1;
> -	} else {
> -		attr.fsx_xflags |= orflags;
> -		attr.fsx_xflags &= ~andflags;
> -		if (xfsctl(path, fd, FS_IOC_FSSETXATTR, &attr) < 0) {
> -			fprintf(stderr, _("%s: cannot set flags on %s: %s\n"),
> -				progname, path, strerror(errno));
> -			exitcode = 1;
> -		}
> +		return 0;
> +	}
> +
> +	attr.fa_xflags |= orflags;
> +	attr.fa_xflags &= ~andflags;
> +	error = file_setattr(AT_FDCWD, path, stat, &attr, AT_SYMLINK_NOFOLLOW);
> +	if (error) {
> +		fprintf(stderr, _("%s: cannot set flags on %s: %s\n"),
> +			progname, path, strerror(errno));
> +		exitcode = 1;
>  	}
>  
> -	if (fd != -1)
> -		close(fd);
>  	return 0;
>  }
>  
>  static int
>  chattr_f(
> -	int		argc,
> -	char		**argv)
> +	int			argc,
> +	char			**argv)
>  {
> -	struct fsxattr	attr;
> -	struct xflags	*p;
> -	unsigned int	i = 0;
> -	char		*c, *name = file->name;
> +	struct file_attr	attr;
> +	struct xflags		*p;
> +	unsigned int		i = 0;
> +	char			*c, *name = file->name;
> +	struct stat		st;
> +	int			error;
>  
>  	orflags = andflags = 0;
>  	recurse_all = recurse_dir = 0;
> @@ -326,19 +335,30 @@ chattr_f(
>  	if (recurse_all || recurse_dir) {
>  		nftw(name, chattr_callback,
>  			100, FTW_PHYS | FTW_MOUNT | FTW_DEPTH);
> -	} else if (xfsctl(name, file->fd, FS_IOC_FSGETXATTR, &attr) < 0) {
> +		return 0;
> +	}
> +
> +	error = stat(name, &st);
> +	if (error)
> +		return error;
> +
> +	error = file_getattr(AT_FDCWD, name, &st, &attr, AT_SYMLINK_NOFOLLOW);
> +	if (error) {
>  		fprintf(stderr, _("%s: cannot get flags on %s: %s\n"),
>  			progname, name, strerror(errno));
>  		exitcode = 1;
> -	} else {
> -		attr.fsx_xflags |= orflags;
> -		attr.fsx_xflags &= ~andflags;
> -		if (xfsctl(name, file->fd, FS_IOC_FSSETXATTR, &attr) < 0) {
> -			fprintf(stderr, _("%s: cannot set flags on %s: %s\n"),
> -				progname, name, strerror(errno));
> -			exitcode = 1;
> -		}
> +		return 0;
>  	}
> +
> +	attr.fa_xflags |= orflags;
> +	attr.fa_xflags &= ~andflags;
> +	error = file_setattr(AT_FDCWD, name, &st, &attr, AT_SYMLINK_NOFOLLOW);

For my own curiosity, if you wanted to do the get/set sequence on a file
that's already open, is that just:

	file_getattr(fd, "", &attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);
	...
	file_setattr(fd, "", &attr, AT_EMPTY_PATH | AT_SYMLINK_NOFOLLOW);

--D

> +	if (error) {
> +		fprintf(stderr, _("%s: cannot set flags on %s: %s\n"),
> +			progname, name, strerror(errno));
> +		exitcode = 1;
> +	}
> +
>  	return 0;
>  }
>  
> 
> -- 
> 2.49.0
> 
>