statx(2) - Linux manual page (original) (raw)
statx(2) System Calls Manual statx(2)
NAME top
statx - get file status (extended)LIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#define _GNU_SOURCE** /* See feature_test_macros(7) */
**#include <fcntl.h>** /* Definition of **AT_*** constants */
**#include <sys/stat.h>**
**int statx(int** _dirfd_**, const char *_Nullable restrict** _path_**,**
**int** _flags_**, unsigned int** _mask_**,**
**struct statx *restrict** _statxbuf_**);**DESCRIPTION top
This function returns information about a file, storing it in the
buffer pointed to by _statxbuf_. The returned buffer is a structure
of the following type:
struct statx {
__u32 stx_mask; /* Mask of bits indicating
filled fields */
__u32 stx_blksize; /* Block size for filesystem I/O */
__u64 stx_attributes; /* Extra file attribute indicators */
__u32 stx_nlink; /* Number of hard links */
__u32 stx_uid; /* User ID of owner */
__u32 stx_gid; /* Group ID of owner */
__u16 stx_mode; /* File type and mode */
__u64 stx_ino; /* Inode number */
__u64 stx_size; /* Total size in bytes */
__u64 stx_blocks; /* Number of 512B blocks allocated */
__u64 stx_attributes_mask;
/* Mask to show what's supported
in stx_attributes */
/* The following fields are file timestamps */
struct statx_timestamp stx_atime; /* Last access */
struct statx_timestamp stx_btime; /* Creation */
struct statx_timestamp stx_ctime; /* Last status change */
struct statx_timestamp stx_mtime; /* Last modification */
/* If this file represents a device, then the next two
fields contain the ID of the device */
__u32 stx_rdev_major; /* Major ID */
__u32 stx_rdev_minor; /* Minor ID */
/* The next two fields contain the ID of the device
containing the filesystem where the file resides */
__u32 stx_dev_major; /* Major ID */
__u32 stx_dev_minor; /* Minor ID */
__u64 stx_mnt_id; /* Mount ID */
/* Direct I/O alignment restrictions */
__u32 stx_dio_mem_align;
__u32 stx_dio_offset_align;
__u64 stx_subvol; /* Subvolume identifier */
/* Direct I/O atomic write limits */
__u32 stx_atomic_write_unit_min;
__u32 stx_atomic_write_unit_max;
__u32 stx_atomic_write_segments_max;
/* File offset alignment for direct I/O reads */
__u32 stx_dio_read_offset_align;
/* Direct I/O atomic write max opt limit */
__u32 stx_atomic_write_unit_max_opt;
};
The file timestamps are structures of the following type:
struct statx_timestamp {
__s64 tv_sec; /* Seconds since the Epoch (UNIX time) */
__u32 tv_nsec; /* Nanoseconds since tv_sec */
};
(Note that reserved space and padding is omitted.)Invoking statx(): To access a file's status, no permissions are required on the file itself, but in the case of statx() with a pathname, execute (search) permission is required on all of the directories in path that lead to the file.
**statx**() uses _path_, _dirfd_, and _flags_ to identify the target file in
one of the following ways:
An absolute pathname
If _path_ begins with a slash, then it is an absolute
pathname that identifies the target file. In this case,
_dirfd_ is ignored.
A relative pathname
If _path_ is a string that begins with a character other than
a slash and _dirfd_ is **AT_FDCWD**, then _path_ is a relative
pathname that is interpreted relative to the process's
current working directory.
A directory-relative pathname
If _path_ is a string that begins with a character other than
a slash and _dirfd_ is a file descriptor that refers to a
directory, then _path_ is a relative pathname that is
interpreted relative to the directory referred to by _dirfd_.
(See [openat(2)](../man2/openat.2.html) for an explanation of why this is useful.)
By file descriptor
If _path_ is an empty string (or NULL since Linux 6.11) and
the **AT_EMPTY_PATH** flag is specified in _flags_ (see below),
then the target file is the one referred to by the file
descriptor _dirfd_.
_flags_ can be used to influence a pathname-based lookup. A value
for _flags_ is constructed by ORing together zero or more of the
following constants:
**AT_EMPTY_PATH**
If _path_ is an empty string (or NULL since Linux 6.11),
operate on the file referred to by _dirfd_ (which may have
been obtained using the [open(2)](../man2/open.2.html) **O_PATH** flag). In this
case, _dirfd_ can refer to any type of file, not just a
directory.
If _dirfd_ is **AT_FDCWD**, the call operates on the current
working directory.
**AT_NO_AUTOMOUNT**
Don't automount the terminal ("basename") component of _path_
if it is a directory that is an automount point. This
allows the caller to gather attributes of an automount
point (rather than the location it would mount). This flag
has no effect if the mount point has already been mounted
over.
The **AT_NO_AUTOMOUNT** flag can be used in tools that scan
directories to prevent mass-automounting of a directory of
automount points.
All of [stat(2)](../man2/stat.2.html), [lstat(2)](../man2/lstat.2.html), and [fstatat(2)](../man2/fstatat.2.html) act as though
**AT_NO_AUTOMOUNT** was set.
**AT_SYMLINK_NOFOLLOW**
If _path_ is a symbolic link, do not dereference it: instead
return information about the link itself, like [lstat(2)](../man2/lstat.2.html).
_flags_ can also be used to control what sort of synchronization the
kernel will do when querying a file on a remote filesystem. This
is done by ORing in one of the following values:
**AT_STATX_SYNC_AS_STAT**
Do whatever [stat(2)](../man2/stat.2.html) does. This is the default and is very
much filesystem-specific.
**AT_STATX_FORCE_SYNC**
Force the attributes to be synchronized with the server.
This may require that a network filesystem perform a data
writeback to get the timestamps correct.
**AT_STATX_DONT_SYNC**
Don't synchronize anything, but rather just take whatever
the system has cached if possible. This may mean that the
information returned is approximate, but, on a network
filesystem, it may not involve a round trip to the server -
even if no lease is held.
The _mask_ argument to **statx**() is used to tell the kernel which
fields the caller is interested in. _mask_ is an ORed combination
of the following constants:
**STATX_TYPE** Want stx_mode & S_IFMT
**STATX_MODE** Want stx_mode & ~S_IFMT
**STATX_NLINK** Want stx_nlink
**STATX_UID** Want stx_uid
**STATX_GID** Want stx_gid
**STATX_ATIME** Want stx_atime
**STATX_MTIME** Want stx_mtime
**STATX_CTIME** Want stx_ctime
**STATX_INO** Want stx_ino
**STATX_SIZE** Want stx_size
**STATX_BLOCKS** Want stx_blocks
**STATX_BASIC_STATS** [All of the above]
**STATX_BTIME** Want stx_btime
**STATX_ALL** The same as STATX_BASIC_STATS | STATX_BTIME.
It is deprecated and should not be used.
**STATX_MNT_ID** Want stx_mnt_id (since Linux 5.8)
**STATX_DIOALIGN** Want stx_dio_mem_align and stx_dio_offset_align.
(since Linux 6.1; support varies by filesystem)
**STATX_MNT_ID_UNIQUE** Want unique stx_mnt_id (since Linux 6.8)
**STATX_SUBVOL** Want stx_subvol
(since Linux 6.10; support varies by filesystem)
**STATX_WRITE_ATOMIC** Want stx_atomic_write_unit_min,
stx_atomic_write_unit_max,
stx_atomic_write_segments_max,
and stx_atomic_write_unit_max_opt.
(since Linux 6.11; support varies by filesystem)
**STATX_DIO_READ_ALIGN** Want stx_dio_read_offset_align.
(since Linux 6.14; support varies by filesystem)
Note that, in general, the kernel does _not_ reject values in _mask_
other than the above. (For an exception, see **EINVAL** in errors.)
Instead, it simply informs the caller which values are supported
by this kernel and filesystem via the _statx.stxmask_ field.
Therefore, _do not_ simply set _mask_ to **UINT_MAX** (all bits set), as
one or more bits may, in the future, be used to specify an
extension to the buffer.The returned information The status information for the target file is returned in the statx structure pointed to by statxbuf. Included in this is stxmask which indicates what other information has been returned. stxmask has the same format as the mask argument and bits are set in it to indicate which fields have been filled in.
It should be noted that the kernel may return fields that weren't
requested and may fail to return fields that were requested,
depending on what the backing filesystem supports. (Fields that
are given values despite being unrequested can just be ignored.)
In either case, _stxmask_ will not be equal _mask_.
If a filesystem does not support a field or if it has an
unrepresentable value (for instance, a file with an exotic type),
then the mask bit corresponding to that field will be cleared in
_stxmask_ even if the user asked for it and a dummy value will be
filled in for compatibility purposes if one is available (e.g., a
dummy UID and GID may be specified to mount under some
circumstances).
A filesystem may also fill in fields that the caller didn't ask
for if it has values for them available and the information is
available at no extra cost. If this happens, the corresponding
bits will be set in _stxmask_.
_Note_: for performance and simplicity reasons, different fields in
the _statx_ structure may contain state information from different
moments during the execution of the system call. For example, if
_stxmode_ or _stxuid_ is changed by another process by calling
[chmod(2)](../man2/chmod.2.html) or [chown(2)](../man2/chown.2.html), **stat**() might return the old _stxmode_
together with the new _stxuid_, or the old _stxuid_ together with
the new _stxmode_.
Apart from _stxmask_ (which is described above), the fields in the
_statx_ structure are:
_stxblksize_
The "preferred" block size for efficient filesystem I/O.
(Writing to a file in smaller chunks may cause an
inefficient read-modify-rewrite.)
_stxattributes_
Further status information about the file (see below for
more information).
_stxnlink_
The number of hard links on a file.
_stxuid_
This field contains the user ID of the owner of the file.
_stxgid_
This field contains the ID of the group owner of the file.
_stxmode_
The file type and mode. See [inode(7)](../man7/inode.7.html) for details.
_stxino_
The inode number of the file.
_stxsize_
The size of the file (if it is a regular file or a symbolic
link) in bytes. The size of a symbolic link is the length
of the pathname it contains, without a terminating null
byte.
_stxblocks_
The number of blocks allocated to the file on the medium,
in 512-byte units. (This may be smaller than _stxsize_/512
when the file has holes.)
_stxattributesmask_
A mask indicating which bits in _stxattributes_ are
supported by the VFS and the filesystem.
_stxatime_
The file's last access timestamp.
_stxbtime_
The file's creation timestamp.
_stxctime_
The file's last status change timestamp.
_stxmtime_
The file's last modification timestamp.
_stxdevmajor_
_stxdevminor_
The device on which this file (inode) resides.
_stxrdevmajor_
_stxrdevminor_
The device that this file (inode) represents if the file is
of block or character device type.
_stxmntid_
If using STATX_MNT_ID, this is the mount ID of the mount
containing the file. This is the same number reported by
[name_to_handle_at(2)](../man2/name%5Fto%5Fhandle%5Fat.2.html) and corresponds to the number in the
first field in one of the records in _/proc/self/mountinfo_.
If using STATX_MNT_ID_UNIQUE, this is the unique mount ID
of the mount containing the file. This is the number
reported by [listmount(2)](../man2/listmount.2.html) and is the ID used to query the
mount with [statmount(2)](../man2/statmount.2.html). It is guaranteed to not be reused
while the system is running.
_stxdiomemalign_
The alignment (in bytes) required for user memory buffers
for direct I/O (**O_DIRECT**) on this file, or 0 if direct I/O
is not supported on this file.
**STATX_DIOALIGN** (_stxdiomemalign_ and _stxdiooffsetalign_)
is supported on block devices since Linux 6.1. The support
on regular files varies by filesystem; it is supported by
ext4, f2fs, and xfs since Linux 6.1.
_stxdiooffsetalign_
The alignment (in bytes) required for file offsets and I/O
segment lengths for direct I/O (**O_DIRECT**) on this file, or
0 if direct I/O is not supported on this file. This will
only be nonzero if _stxdiomemalign_ is nonzero, and vice
versa.
_stxdioreadoffsetalign_
The alignment (in bytes) required for file offsets and I/O
segment lengths for direct I/O reads (**O_DIRECT**) on this
file. If zero, the limit in _stxdiooffsetalign_ applies
for reads as well. If non-zero, this value must be smaller
than or equal to _stxdiooffsetalign_ which must be
provided by the file system if requested by the
application. The memory alignment in _stxdiomemalign_ is
not affected by this value.
**STATX_DIO_READ_ALIGN** (_stxdiooffsetalign_) is supported by
xfs on regular files since Linux 6.14.
_stxsubvol_
Subvolume number of the current file.
Subvolumes are fancy directories, i.e., they form a tree
structure that may be walked recursively. Support varies
by filesystem; it is supported by bcachefs and btrfs since
Linux 6.10.
_stxatomicwriteunitmin_
_stxatomicwriteunitmax_
The minimum and maximum sizes (in bytes) supported for
direct I/O (**O_DIRECT**) on the file to be written with torn-
write protection. These values are each guaranteed to be a
power-of-2.
**STATX_WRITE_ATOMIC** (_stxatomicwriteunitmin_,
_stxatomicwriteunitmax_, and
_stxatomicwritesegmentsmax_) is supported on block
devices since Linux 6.11. The support on regular files
varies by filesystem; it is supported by xfs and ext4 since
Linux 6.13.
_stxatomicwriteunitmaxopt_
The maximum size (in bytes) which is optimised for writes
issued with torn-write protection. If non-zero, this value
will not exceed the value in _stxatomicwriteunitmax_ and
will not be less than the value in
_stxatomicwriteunitmin_. A value of zero indicates that
_stxatomicwriteunitmax_ is the optimised limit. Slower
writes may be experienced when the size of the write
exceeds _stxatomicwriteunitmaxopt_ (when non-zero).
_stxatomicwritesegmentsmax_
The maximum number of elements in an array of vectors for a
write with torn-write protection enabled. See **RWF_ATOMIC**
flag for [pwritev2(2)](../man2/pwritev2.2.html).
For further information on the above fields, see [inode(7)](../man7/inode.7.html).File attributes The stxattributes field contains a set of ORed flags that indicate additional attributes of the file. Note that any attribute that is not indicated as supported by stxattributesmask has no usable value here. The bits in stxattributesmask correspond bit-by-bit to stxattributes.
The flags are as follows:
**STATX_ATTR_COMPRESSED**
The file is compressed by the filesystem and may take extra
resources to access.
**STATX_ATTR_IMMUTABLE**
The file cannot be modified: it cannot be deleted or
renamed, no hard links can be created to this file and no
data can be written to it. See [chattr(1)](../man1/chattr.1.html).
**STATX_ATTR_APPEND**
The file can only be opened in append mode for writing.
Random access writing is not permitted. See [chattr(1)](../man1/chattr.1.html).
**STATX_ATTR_NODUMP**
File is not a candidate for backup when a backup program
such as **dump**(8) is run. See [chattr(1)](../man1/chattr.1.html).
**STATX_ATTR_ENCRYPTED**
A key is required for the file to be encrypted by the
filesystem.
**STATX_ATTR_VERITY** (since Linux 5.5)
The file has fs-verity enabled. It cannot be written to,
and all reads from it will be verified against a
cryptographic hash that covers the entire file (e.g., via a
Merkle tree).
**STATX_ATTR_WRITE_ATOMIC** (since Linux 6.11)
The file supports torn-write protection.
**STATX_ATTR_DAX** (since Linux 5.8)
The file is in the DAX (cpu direct access) state. DAX
state attempts to minimize software cache effects for both
I/O and memory mappings of this file. It requires a file
system which has been configured to support DAX.
DAX generally assumes all accesses are via CPU load / store
instructions which can minimize overhead for small
accesses, but may adversely affect CPU utilization for
large transfers.
File I/O is done directly to/from user-space buffers and
memory mapped I/O may be performed with direct memory
mappings that bypass the kernel page cache.
While the DAX property tends to result in data being
transferred synchronously, it does not give the same
guarantees as the **O_SYNC** flag (see [open(2)](../man2/open.2.html)), where data and
the necessary metadata are transferred together.
A DAX file may support being mapped with the **MAP_SYNC** flag,
which enables a program to use CPU cache flush instructions
to persist CPU store operations without an explicit
[fsync(2)](../man2/fsync.2.html). See [mmap(2)](../man2/mmap.2.html) for more information.
**STATX_ATTR_MOUNT_ROOT** (since Linux 5.8)
The file is the root of a mount.RETURN VALUE top
On success, zero is returned. On error, -1 is returned, and _[errno](../man3/errno.3.html)_
is set to indicate the error.ERRORS top
**EACCES** Search permission is denied for one of the directories in
the path prefix of _path_. (See also [path_resolution(7)](../man7/path%5Fresolution.7.html).)
**EBADF** _path_ is relative but _dirfd_ is neither **AT_FDCWD** nor a valid
file descriptor.
**EFAULT** _path_ or _statxbuf_ points to a location outside the process's
accessible address space or is NULL (except since Linux
6.11 if **AT_EMPTY_PATH** is specified in _flags_, _path_ is
allowed to be NULL).
**EINVAL** Invalid flag specified in _flags_.
**EINVAL** Reserved flag specified in _mask_. (Currently, there is one
such flag, designated by the constant **STATX__RESERVED**, with
the value 0x80000000U.)
**ELOOP** Too many symbolic links encountered while traversing the
pathname.
**ENAMETOOLONG**
_path_ is too long.
**ENOENT** A component of _path_ does not exist, or _path_ is an empty
string and **AT_EMPTY_PATH** was not specified in _flags_.
**ENOMEM** Out of memory (i.e., kernel memory).
**ENOTDIR**
A component of the path prefix of _path_ is not a directory
or _path_ is relative and _dirfd_ is a file descriptor
referring to a file other than a directory.STANDARDS top
Linux.HISTORY top
Linux 4.11, glibc 2.28.SEE ALSO top
[ls(1)](../man1/ls.1.html), [stat(1)](../man1/stat.1.html), [access(2)](../man2/access.2.html), [chmod(2)](../man2/chmod.2.html), [chown(2)](../man2/chown.2.html),
[name_to_handle_at(2)](../man2/name%5Fto%5Fhandle%5Fat.2.html), [readlink(2)](../man2/readlink.2.html), [stat(2)](../man2/stat.2.html), [utime(2)](../man2/utime.2.html), [proc(5)](../man5/proc.5.html),
[capabilities(7)](../man7/capabilities.7.html), [inode(7)](../man7/inode.7.html), [symlink(7)](../man7/symlink.7.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.16 2025-09-21 statx(2)
Pages that refer to this page:stat(1), io_submit(2), io_uring_enter2(2), io_uring_enter(2), listmount(2), open(2), open_by_handle_at(2), stat(2), statmount(2), syscalls(2), io_uring_prep_statx(3), tmpfiles.d(5), fanotify(7), inode(7)