On Fri, Aug 08, 2025 at 09:30:16PM +0200, Andrey Albershteyn wrote:
> Add wrappers for new file_getattr/file_setattr inode syscalls which will
> be used by xfs_quota and xfs_io.
>
> Signed-off-by: Andrey Albershteyn <aalbersh@xxxxxxxxxx>
> ---
> configure.ac | 1 +
> include/builddefs.in | 5 +++
> include/linux.h | 20 ++++++++++
> libfrog/Makefile | 2 +
> libfrog/file_attr.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++
> libfrog/file_attr.h | 35 +++++++++++++++++
> m4/package_libcdev.m4 | 19 +++++++++
> 7 files changed, 187 insertions(+)
>
> diff --git a/configure.ac b/configure.ac
> index 9a3309bcdfd1..40a44c571e7b 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -156,6 +156,7 @@ AC_PACKAGE_NEED_RCU_INIT
> AC_HAVE_PWRITEV2
> AC_HAVE_COPY_FILE_RANGE
> AC_HAVE_CACHESTAT
> +AC_HAVE_FILE_ATTR
> AC_NEED_INTERNAL_FSXATTR
> AC_NEED_INTERNAL_FSCRYPT_ADD_KEY_ARG
> AC_NEED_INTERNAL_FSCRYPT_POLICY_V2
> diff --git a/include/builddefs.in b/include/builddefs.in
> index 04b4e0880a84..d727b55b854f 100644
> --- a/include/builddefs.in
> +++ b/include/builddefs.in
> @@ -97,6 +97,7 @@ HAVE_ZIPPED_MANPAGES = @have_zipped_manpages@
> HAVE_PWRITEV2 = @have_pwritev2@
> HAVE_COPY_FILE_RANGE = @have_copy_file_range@
> HAVE_CACHESTAT = @have_cachestat@
> +HAVE_FILE_ATTR = @have_file_attr@
> NEED_INTERNAL_FSXATTR = @need_internal_fsxattr@
> NEED_INTERNAL_FSCRYPT_ADD_KEY_ARG = @need_internal_fscrypt_add_key_arg@
> NEED_INTERNAL_FSCRYPT_POLICY_V2 = @need_internal_fscrypt_policy_v2@
> @@ -169,6 +170,10 @@ ifeq ($(ENABLE_GETTEXT),yes)
> GCFLAGS += -DENABLE_GETTEXT
> endif
>
> +ifeq ($(HAVE_FILE_ATTR),yes)
> +LCFLAGS += -DHAVE_FILE_ATTR
> +endif
> +
> # Override these if C++ needs other options
> SANITIZER_CXXFLAGS = $(SANITIZER_CFLAGS)
> GCXXFLAGS = $(GCFLAGS)
> diff --git a/include/linux.h b/include/linux.h
> index 6e83e073aa2e..018cc78960e3 100644
> --- a/include/linux.h
> +++ b/include/linux.h
> @@ -16,6 +16,7 @@
> #include <sys/param.h>
> #include <sys/sysmacros.h>
> #include <sys/stat.h>
> +#include <sys/syscall.h>
> #include <inttypes.h>
> #include <malloc.h>
> #include <getopt.h>
> @@ -202,6 +203,25 @@ struct fsxattr {
> };
> #endif
>
> +/*
> + * Use __NR_file_getattr instead of build system HAVE_FILE_ATTR as this header
> + * could be included in other places where HAVE_FILE_ATTR is not defined (e.g.
> + * xfstests's conftest.c in ./configure)
> + */
> +#ifndef __NR_file_getattr
Seeing as uapi fs.h now has:
#define FILE_ATTR_SIZE_VER0 24
#define FILE_ATTR_SIZE_LATEST FILE_ATTR_SIZE_VER0
I wonder if you'd be better off gating on one of those defines rather
than the presence of the syscall number?
> +/*
> + * We need to define file_attr if it's missing to know how to convert it to
> + * fsxattr
> + */
> +struct file_attr {
> + __u32 fa_xflags;
> + __u32 fa_extsize;
> + __u32 fa_nextents;
> + __u32 fa_projid;
> + __u32 fa_cowextsize;
> +};
> +#endif
> +
> #ifndef FS_IOC_FSGETXATTR
> /*
> * Flags for the fsx_xflags field
> diff --git a/libfrog/Makefile b/libfrog/Makefile
> index b64ca4597f4e..7d49fd0fe6cc 100644
> --- a/libfrog/Makefile
> +++ b/libfrog/Makefile
> @@ -24,6 +24,7 @@ fsproperties.c \
> fsprops.c \
> getparents.c \
> histogram.c \
> +file_attr.c \
> list_sort.c \
> linux.c \
> logging.c \
> @@ -55,6 +56,7 @@ fsprops.h \
> getparents.h \
> handle_priv.h \
> histogram.h \
> +file_attr.h \
> logging.h \
> paths.h \
> projects.h \
> diff --git a/libfrog/file_attr.c b/libfrog/file_attr.c
> new file mode 100644
> index 000000000000..8592d775f554
> --- /dev/null
> +++ b/libfrog/file_attr.c
> @@ -0,0 +1,105 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024 Red Hat, Inc.
> + * All Rights Reserved.
> + */
> +
> +#include "file_attr.h"
> +#include <stdio.h>
> +#include <errno.h>
> +#include <string.h>
> +#include <sys/syscall.h>
> +#include <asm/types.h>
> +#include <fcntl.h>
> +
> +static void
> +file_attr_to_fsxattr(
> + const struct file_attr *fa,
> + struct fsxattr *fsxa)
> +{
> + memset(fsxa, 0, sizeof(struct fsxattr));
> +
> + fsxa->fsx_xflags = fa->fa_xflags;
> + fsxa->fsx_extsize = fa->fa_extsize;
> + fsxa->fsx_nextents = fa->fa_nextents;
> + fsxa->fsx_projid = fa->fa_projid;
> + fsxa->fsx_cowextsize = fa->fa_cowextsize;
> +
> +}
> +
> +static void
> +fsxattr_to_file_attr(
> + const struct fsxattr *fsxa,
> + struct file_attr *fa)
> +{
> + memset(fa, 0, sizeof(struct file_attr));
> +
> + fa->fa_xflags = fsxa->fsx_xflags;
> + fa->fa_extsize = fsxa->fsx_extsize;
> + fa->fa_nextents = fsxa->fsx_nextents;
> + fa->fa_projid = fsxa->fsx_projid;
> + fa->fa_cowextsize = fsxa->fsx_cowextsize;
> +}
> +
> +int
> +file_getattr(
> + const int dfd,
> + const char *path,
> + const struct stat *stat,
> + struct file_attr *fa,
> + const unsigned int at_flags)
> +{
Will this cause a naming conflict when libc wraps the new syscall?
> + int error;
> + int fd;
> + struct fsxattr fsxa;
> +
> +#ifdef HAVE_FILE_ATTR
> + return syscall(__NR_file_getattr, dfd, path, fa,
> + sizeof(struct file_attr), at_flags);
What happens if we build xfsprogs on new userspace but it then gets run
on an old kernel that doesn't support file_getattr(2)? Shouldn't we
fall back to the old ioctl on ENOSYS?
> +#else
> + if (SPECIAL_FILE(stat->st_mode))
> + return 0;
Why does it return 0 without filling out @fa? Shouldn't this be
EOPNOTSUPP or something?
> +#endif
> +
> + fd = open(path, O_RDONLY|O_NOCTTY);
> + if (fd == -1)
> + return errno;
> +
> + error = ioctl(fd, FS_IOC_FSGETXATTR, &fsxa);
> + close(fd);
> +
> + fsxattr_to_file_attr(&fsxa, fa);
Er... if the ioctl errors out, fsxa will still be uninitialized stack
garbage, which is (pointlessly) copied to the caller's fa structure.
> +
> + return error;
I'm confused about the return value of this function. If the syscall
or the ioctl fail we'll pass the -1 to the caller and let them access
errno, but if the open fails we return errno directly?
> +}
> +
> +int
> +file_setattr(
> + const int dfd,
> + const char *path,
> + const struct stat *stat,
> + struct file_attr *fa,
> + const unsigned int at_flags)
> +{
> + int error;
> + int fd;
> + struct fsxattr fsxa;
> +
> +#ifdef HAVE_FILE_ATTR
> + return syscall(__NR_file_setattr, dfd, path, fa,
> + sizeof(struct file_attr), at_flags);
> +#else
> + if (SPECIAL_FILE(stat->st_mode))
> + return 0;
> +#endif
> +
> + fd = open(path, O_RDONLY|O_NOCTTY);
> + if (fd == -1)
> + return errno;
Same comments that I had about file_getattr.
> +
> + file_attr_to_fsxattr(fa, &fsxa);
> + error = ioctl(fd, FS_IOC_FSSETXATTR, fa);
> + close(fd);
> +
> + return error;
> +}
> diff --git a/libfrog/file_attr.h b/libfrog/file_attr.h
> new file mode 100644
> index 000000000000..3e56e80a6f95
> --- /dev/null
> +++ b/libfrog/file_attr.h
> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024 Red Hat, Inc.
> + * All Rights Reserved.
> + */
> +#ifndef __LIBFROG_IXATTR_H__
> +#define __LIBFROG_IXATTR_H__
__LIBFROG_FILE_ATTR_H__ ?
--D
> +
> +#include "linux.h"
> +#include <sys/stat.h>
> +
> +#define SPECIAL_FILE(x) \
> + (S_ISCHR((x)) \
> + || S_ISBLK((x)) \
> + || S_ISFIFO((x)) \
> + || S_ISLNK((x)) \
> + || S_ISSOCK((x)))
> +
> +int
> +file_getattr(
> + const int dfd,
> + const char *path,
> + const struct stat *stat,
> + struct file_attr *fa,
> + const unsigned int at_flags);
> +
> +int
> +file_setattr(
> + const int dfd,
> + const char *path,
> + const struct stat *stat,
> + struct file_attr *fa,
> + const unsigned int at_flags);
> +
> +#endif /* __LIBFROG_IXATTR_H__ */
> diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> index 61353d0aa9d5..cb8ff1576d01 100644
> --- a/m4/package_libcdev.m4
> +++ b/m4/package_libcdev.m4
> @@ -274,3 +274,22 @@ AC_DEFUN([AC_PACKAGE_CHECK_LTO],
> AC_SUBST(lto_cflags)
> AC_SUBST(lto_ldflags)
> ])
> +
> +#
> +# Check if we have a file_getattr/file_setattr system call (Linux)
> +#
> +AC_DEFUN([AC_HAVE_FILE_ATTR],
> + [ AC_MSG_CHECKING([for file_getattr/file_setattr syscalls])
> + AC_LINK_IFELSE(
> + [ AC_LANG_PROGRAM([[
> +#define _GNU_SOURCE
> +#include <sys/syscall.h>
> +#include <unistd.h>
> + ]], [[
> +syscall(__NR_file_getattr, 0, 0, 0, 0, 0);
> + ]])
> + ], have_file_attr=yes
> + AC_MSG_RESULT(yes),
> + AC_MSG_RESULT(no))
> + AC_SUBST(have_file_attr)
> + ])
>
> --
> 2.49.0
>
>
