On 2025-08-11 08:02:42, Darrick J. Wong wrote:
> 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?
Hmm, yeah, should work
>
> > +/*
> > + * 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?
xfrog_file_getattr?
>
> > + 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?
oh right, missed that. I can add this check.
Is it something common in general? I suppose booting into older
kernel when xfsprogs was compiled with the "current" one is one case
but it's expected that kernel can miss some features
>
> > +#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?
I was trying to just wrap the old code without changing the output,
I haven't thought too hard about design of this function. I will
apply your suggestion including EOPNOSUPP mentioned in other mail.
>
> > +}
> > +
> > +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__ ?
ops, right
>
> --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
> >
> >
>
--
- Andrey
