statvfs(3) Library Functions Manual statvfs(3)
NAME
statvfs, fstatvfs - get filesystem statistics
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <sys/statvfs.h>
int statvfs(const char *restrict path, struct statvfs *restrict buf);
int fstatvfs(int fd, struct statvfs *buf);
DESCRIPTION
The function statvfs() returns information about a mounted filesystem.
path is the pathname of any file within the mounted filesystem. buf is
a pointer to a statvfs structure defined approximately as follows:
struct statvfs {
unsigned long f_bsize; /* Filesystem block size */
unsigned long f_frsize; /* Fragment size */
fsblkcnt_t f_blocks; /* Size of fs in f_frsize units */
fsblkcnt_t f_bfree; /* Number of free blocks */
fsblkcnt_t f_bavail; /* Number of free blocks for
unprivileged users */
fsfilcnt_t f_files; /* Number of inodes */
fsfilcnt_t f_ffree; /* Number of free inodes */
fsfilcnt_t f_favail; /* Number of free inodes for
unprivileged users */
unsigned long f_fsid; /* Filesystem ID */
unsigned long f_flag; /* Mount flags */
unsigned long f_namemax; /* Maximum filename length */
};
Here the types fsblkcnt_t and fsfilcnt_t are defined in <sys/types.h>.
Both used to be unsigned long.
The field f_flag is a bit mask indicating various options that were em-
ployed when mounting this filesystem. It contains zero or more of the
following flags:
ST_MANDLOCK
Mandatory locking is permitted on the filesystem (see fcntl(2)).
ST_NOATIME
Do not update access times; see mount(2).
ST_NODEV
Disallow access to device special files on this filesystem.
ST_NODIRATIME
Do not update directory access times; see mount(2).
ST_NOEXEC
Execution of programs is disallowed on this filesystem.
ST_NOSUID
The set-user-ID and set-group-ID bits are ignored by exec(3) for
executable files on this filesystem
ST_RDONLY
This filesystem is mounted read-only.
ST_RELATIME
Update atime relative to mtime/ctime; see mount(2).
ST_SYNCHRONOUS
Writes are synched to the filesystem immediately (see the de-
scription of O_SYNC in open(2)).
It is unspecified whether all members of the returned struct have mean-
ingful values on all filesystems.
fstatvfs() returns the same information about an open file referenced by
descriptor fd.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is
set to indicate the error.
ERRORS
EACCES (statvfs()) Search permission is denied for a component of the
path prefix of path. (See also path_resolution(7).)
EBADF (fstatvfs()) fd is not a valid open file descriptor.
EFAULT Buf or path points to an invalid address.
EINTR This call was interrupted by a signal; see signal(7).
EIO An I/O error occurred while reading from the filesystem.
ELOOP (statvfs()) Too many symbolic links were encountered in translat-
ing path.
ENAMETOOLONG
(statvfs()) path is too long.
ENOENT (statvfs()) The file referred to by path does not exist.
ENOMEM Insufficient kernel memory was available.
ENOSYS The filesystem does not support this call.
ENOTDIR
(statvfs()) A component of the path prefix of path is not a di-
rectory.
EOVERFLOW
Some values were too large to be represented in the returned
struct.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│ statvfs(), fstatvfs() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
VERSIONS
Only the ST_NOSUID and ST_RDONLY flags of the f_flag field are specified
in POSIX.1. To obtain definitions of the remaining flags, one must de-
fine _GNU_SOURCE.
NOTES
The Linux kernel has system calls statfs(2) and fstatfs(2) to support
this library call.
The glibc implementations of
pathconf(path, _PC_REC_XFER_ALIGN);
pathconf(path, _PC_ALLOC_SIZE_MIN);
pathconf(path, _PC_REC_MIN_XFER_SIZE);
respectively use the f_frsize, f_frsize, and f_bsize fields returned by
a call to statvfs() with the argument path.
Under Linux, f_favail is always the same as f_ffree, and there's no way
for a filesystem to report otherwise. This is not an issue, since no
filesystems with an inode root reservation exist.
STANDARDS
POSIX.1-2008.
HISTORY
POSIX.1-2001.
Before glibc 2.13, statvfs() populated the bits of the f_flag field by
scanning the mount options shown in /proc/mounts. However, starting
with Linux 2.6.36, the underlying statfs(2) system call provides the
necessary information via the f_flags field, and since glibc 2.13, the
statvfs() function will use information from that field rather than
scanning /proc/mounts.
SEE ALSO
statfs(2)
Linux man-pages 6.9.1 2024-05-02 statvfs(3)
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