linux-loongson/include/linux/stat.h
John Garry 5d894321c4 fs: add atomic write unit max opt to statx
XFS will be able to support large atomic writes (atomic write > 1x block)
in future. This will be achieved by using different operating methods,
depending on the size of the write.

Specifically a new method of operation based in FS atomic extent remapping
will be supported in addition to the current HW offload-based method.

The FS method will generally be appreciably slower performing than the
HW-offload method. However the FS method will be typically able to
contribute to achieving a larger atomic write unit max limit.

XFS will support a hybrid mode, where HW offload method will be used when
possible, i.e. HW offload is used when the length of the write is
supported, and for other times FS-based atomic writes will be used.

As such, there is an atomic write length at which the user may experience
appreciably slower performance.

Advertise this limit in a new statx field, stx_atomic_write_unit_max_opt.

When zero, it means that there is no such performance boundary.

Masks STATX{_ATTR}_WRITE_ATOMIC can be used to get this new field. This is
ok for older kernels which don't support this new field, as they would
report 0 in this field (from zeroing in cp_statx()) already. Furthermore
those older kernels don't support large atomic writes - apart from block
fops, but there would be consistent performance there for atomic writes
in range [unit min, unit max].

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Acked-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
2025-05-07 14:25:30 -07:00

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C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_STAT_H
#define _LINUX_STAT_H
#include <asm/stat.h>
#include <uapi/linux/stat.h>
#define S_IRWXUGO (S_IRWXU|S_IRWXG|S_IRWXO)
#define S_IALLUGO (S_ISUID|S_ISGID|S_ISVTX|S_IRWXUGO)
#define S_IRUGO (S_IRUSR|S_IRGRP|S_IROTH)
#define S_IWUGO (S_IWUSR|S_IWGRP|S_IWOTH)
#define S_IXUGO (S_IXUSR|S_IXGRP|S_IXOTH)
#define UTIME_NOW ((1l << 30) - 1l)
#define UTIME_OMIT ((1l << 30) - 2l)
#include <linux/types.h>
#include <linux/time.h>
#include <linux/uidgid.h>
struct kstat {
u32 result_mask; /* What fields the user got */
umode_t mode;
unsigned int nlink;
uint32_t blksize; /* Preferred I/O size */
u64 attributes;
u64 attributes_mask;
#define KSTAT_ATTR_FS_IOC_FLAGS \
(STATX_ATTR_COMPRESSED | \
STATX_ATTR_IMMUTABLE | \
STATX_ATTR_APPEND | \
STATX_ATTR_NODUMP | \
STATX_ATTR_ENCRYPTED | \
STATX_ATTR_VERITY \
)/* Attrs corresponding to FS_*_FL flags */
#define KSTAT_ATTR_VFS_FLAGS \
(STATX_ATTR_IMMUTABLE | \
STATX_ATTR_APPEND \
) /* Attrs corresponding to S_* flags that are enforced by the VFS */
u64 ino;
dev_t dev;
dev_t rdev;
kuid_t uid;
kgid_t gid;
loff_t size;
struct timespec64 atime;
struct timespec64 mtime;
struct timespec64 ctime;
struct timespec64 btime; /* File creation time */
u64 blocks;
u64 mnt_id;
u64 change_cookie;
u64 subvol;
u32 dio_mem_align;
u32 dio_offset_align;
u32 dio_read_offset_align;
u32 atomic_write_unit_min;
u32 atomic_write_unit_max;
u32 atomic_write_unit_max_opt;
u32 atomic_write_segments_max;
};
/* These definitions are internal to the kernel for now. Mainly used by nfsd. */
/* mask values */
#define STATX_CHANGE_COOKIE 0x40000000U /* Want/got stx_change_attr */
/* file attribute values */
#define STATX_ATTR_CHANGE_MONOTONIC 0x8000000000000000ULL /* version monotonically increases */
#endif