> On Nov 18, 2024, at 4:01 PM, Darrick J. Wong <djwong@xxxxxxxxxx> wrote:
>
> On Mon, Nov 18, 2024 at 03:52:55PM -0800, Catherine Hoang wrote:
>> Add support for the new atomic_write_unit_min, atomic_write_unit_max, and
>> atomic_write_segments_max fields in statx for xfs_io. In order to support builds
>> against old kernel headers, define our own internal statx structs. If the
>> system's struct statx does not have the required atomic write fields, override
>> the struct definitions with the internal definitions in statx.h.
>>
>> Signed-off-by: Catherine Hoang <catherine.hoang@xxxxxxxxxx>
>> ---
>> configure.ac | 1 +
>> include/builddefs.in | 4 ++++
>> io/stat.c | 7 +++++++
>> io/statx.h | 23 ++++++++++++++++++++++-
>> m4/package_libcdev.m4 | 20 ++++++++++++++++++++
>> 5 files changed, 54 insertions(+), 1 deletion(-)
>>
>> diff --git a/configure.ac b/configure.ac
>> index 33b01399..0b1ef3c3 100644
>> --- a/configure.ac
>> +++ b/configure.ac
>> @@ -146,6 +146,7 @@ AC_HAVE_COPY_FILE_RANGE
>> AC_NEED_INTERNAL_FSXATTR
>> AC_NEED_INTERNAL_FSCRYPT_ADD_KEY_ARG
>> AC_NEED_INTERNAL_FSCRYPT_POLICY_V2
>> +AC_NEED_INTERNAL_STATX
>> AC_HAVE_GETFSMAP
>> AC_HAVE_MAP_SYNC
>> AC_HAVE_DEVMAPPER
>> diff --git a/include/builddefs.in b/include/builddefs.in
>> index 1647d2cd..cbc9ab0c 100644
>> --- a/include/builddefs.in
>> +++ b/include/builddefs.in
>> @@ -96,6 +96,7 @@ HAVE_COPY_FILE_RANGE = @have_copy_file_range@
>> 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@
>> +NEED_INTERNAL_STATX = @need_internal_statx@
>> HAVE_GETFSMAP = @have_getfsmap@
>> HAVE_MAP_SYNC = @have_map_sync@
>> HAVE_DEVMAPPER = @have_devmapper@
>> @@ -130,6 +131,9 @@ endif
>> ifeq ($(NEED_INTERNAL_FSCRYPT_POLICY_V2),yes)
>> PCFLAGS+= -DOVERRIDE_SYSTEM_FSCRYPT_POLICY_V2
>> endif
>> +ifeq ($(NEED_INTERNAL_STATX),yes)
>> +PCFLAGS+= -DOVERRIDE_SYSTEM_STATX
>> +endif
>> ifeq ($(HAVE_GETFSMAP),yes)
>> PCFLAGS+= -DHAVE_GETFSMAP
>> endif
>> diff --git a/io/stat.c b/io/stat.c
>> index 0f5618f6..7d1c1c93 100644
>> --- a/io/stat.c
>> +++ b/io/stat.c
>> @@ -6,6 +6,10 @@
>> * Portions of statx support written by David Howells (dhowells@xxxxxxxxxx)
>> */
>>
>> +#ifdef OVERRIDE_SYSTEM_STATX
>> +#define statx sys_statx
>> +#endif
>> +
>> #include "command.h"
>> #include "input.h"
>> #include "init.h"
>> @@ -347,6 +351,9 @@ dump_raw_statx(struct statx *stx)
>> printf("stat.rdev_minor = %u\n", stx->stx_rdev_minor);
>> printf("stat.dev_major = %u\n", stx->stx_dev_major);
>> printf("stat.dev_minor = %u\n", stx->stx_dev_minor);
>> + printf("stat.atomic_write_unit_min = %lld\n", (long long)stx->stx_atomic_write_unit_min);
>> + printf("stat.atomic_write_unit_max = %lld\n", (long long)stx->stx_atomic_write_unit_max);
>> + printf("stat.atomic_write_segments_max = %lld\n", (long long)stx->stx_atomic_write_segments_max);
>> return 0;
>> }
>>
>> diff --git a/io/statx.h b/io/statx.h
>> index c6625ac4..d151f732 100644
>> --- a/io/statx.h
>> +++ b/io/statx.h
>> @@ -61,6 +61,7 @@ struct statx_timestamp {
>> __s32 tv_nsec;
>> __s32 __reserved;
>> };
>> +#endif
>>
>> /*
>> * Structures for the extended file attribute retrieval system call
>> @@ -99,6 +100,8 @@ struct statx_timestamp {
>> * will have values installed for compatibility purposes so that stat() and
>> * co. can be emulated in userspace.
>> */
>> +#if !defined STATX_TYPE || defined OVERRIDE_SYSTEM_STATX
>
> Is there any place where STATX_TYPE is not defined but
> OVERRIDE_SYSTEM_STATX will *also* not be defined?
I don’t think so. So I guess this could just be
#ifdef OVERRIDE_SYSTEM_STATX
Does that seem right?
>
> I think the m4 macro you added sets need_internal_statx=yes for old
> systems where there's no STATX_TYPE, because there won't be a struct
> statx, let alone atomic_write_* fields in it, right?
>
> --D
>
>> +#undef statx
>> struct statx {
>> /* 0x00 */
>> __u32 stx_mask; /* What results were written [uncond] */
>> @@ -126,10 +129,23 @@ struct statx {
>> __u32 stx_dev_major; /* ID of device containing file [uncond] */
>> __u32 stx_dev_minor;
>> /* 0x90 */
>> - __u64 __spare2[14]; /* Spare space for future expansion */
>> + __u64 stx_mnt_id;
>> + __u32 stx_dio_mem_align; /* Memory buffer alignment for direct I/O */
>> + __u32 stx_dio_offset_align; /* File offset alignment for direct I/O */
>> + /* 0xa0 */
>> + __u64 stx_subvol; /* Subvolume identifier */
>> + __u32 stx_atomic_write_unit_min; /* Min atomic write unit in bytes */
>> + __u32 stx_atomic_write_unit_max; /* Max atomic write unit in bytes */
>> + /* 0xb0 */
>> + __u32 stx_atomic_write_segments_max; /* Max atomic write segment count */
>> + __u32 __spare1[1];
>> + /* 0xb8 */
>> + __u64 __spare3[9]; /* Spare space for future expansion */
>> /* 0x100 */
>> };
>> +#endif
>>
>> +#ifndef STATX_TYPE
>> /*
>> * Flags to be stx_mask
>> *
>> @@ -174,4 +190,9 @@ struct statx {
>> #define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */
>>
>> #endif /* STATX_TYPE */
>> +
>> +#ifndef STATX_WRITE_ATOMIC
>> +#define STATX_WRITE_ATOMIC 0x00010000U /* Want/got atomic_write_* fields */
>> +#endif
>> +
>> #endif /* XFS_IO_STATX_H */
>> diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
>> index 6de8b33e..bc8a49a9 100644
>> --- a/m4/package_libcdev.m4
>> +++ b/m4/package_libcdev.m4
>> @@ -98,6 +98,26 @@ AC_DEFUN([AC_NEED_INTERNAL_FSCRYPT_POLICY_V2],
>> AC_SUBST(need_internal_fscrypt_policy_v2)
>> ])
>>
>> +#
>> +# Check if we need to override the system struct statx with
>> +# the internal definition. This /only/ happens if the system
>> +# actually defines struct statx /and/ the system definition
>> +# is missing certain fields.
>> +#
>> +AC_DEFUN([AC_NEED_INTERNAL_STATX],
>> + [ AC_CHECK_TYPE(struct statx,
>> + [
>> + AC_CHECK_MEMBER(struct statx.stx_atomic_write_unit_min,
>> + ,
>> + need_internal_statx=yes,
>> + [#include <linux/stat.h>]
>> + )
>> + ],,
>> + [#include <linux/stat.h>]
>> + )
>> + AC_SUBST(need_internal_statx)
>> + ])
>> +
>> #
>> # Check if we have a FS_IOC_GETFSMAP ioctl (Linux)
>> #
>> --
>> 2.34.1
>>
>>
