statvfs() System Call in Linux

NAME

statvfs, fstatvfs - get file system statistics

SYNOPSIS

#include <sys/statvfs.h>

int statvfs(const char *path, struct statvfs *buf);
int fstatvfs(int fd, struct statvfs *buf);

DESCRIPTION

The function statvfs() returns information about a mounted file system. 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;    /* file system block size */
    unsigned long  f_frsize;   /* fragment size */
    fsblkcnt_t     f_blocks;   /* size of fs in f_frsize units */
    fsblkcnt_t     f_bfree;    /* # free blocks */
    fsblkcnt_t     f_bavail;   /* # free blocks for non-root */
    fsfilcnt_t     f_files;    /* # inodes */
    fsfilcnt_t     f_ffree;    /* # free inodes */
    fsfilcnt_t     f_favail;   /* # free inodes for non-root */
    unsigned long  f_fsid;     /* file system 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 (of mount flags, see mount(8)). Bits defined by POSIX are

Tag	Description
ST_RDONLY
	Read-only file system.
ST_NOSUID
	Set-user-ID/set-group-ID bits are ignored by exec(2).

It is unspecified whether all members of the returned struct have meaningful 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 appropriately.

ERRORS

Tag	Description
EACCES	(statvfs()) Search permission is denied for a component of the path prefix of path. (See also path_resolution(2).)
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.
EIO	An I/O error occurred while reading from the file system.
ELOOP	(statvfs()) Too many symbolic links were encountered in translating 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 file system does not support this call.
ENOTDIR
	(statvfs()) A component of the path prefix of path is not a directory.
EOVERFLOW
	Some values were too large to be represented in the returned struct.

CONFORMING TO

Solaris, Irix, POSIX.1-2001

NOTES

The Linux kernel has system calls statfs() and fstatfs() to support this library call.

The current glibc implementation of

   pathconf(path, _PC_REC_XFER_ALIGN);
   pathconf(path, _PC_ALLOC_SIZE_MIN);
   pathconf(path, _PC_REC_MIN_XFER_SIZE);

uses the f_frsize, f_frsize, and f_bsize fields of the return value of statvfs(path,buf).