fstatvfs

STATVFS(3)                 Linux Programmer's Manual                STATVFS(3)

NAME
       statvfs, fstatvfs - get filesystem 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 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
       employed  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
              description 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 appropriately.

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.

       EIO    An I/O error occurred while reading from the filesystem.

       ELOOP  (statvfs()) Too many symbolic links were encountered  in  trans-
              lating 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
              directory.

       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 |
       +----------------------+---------------+---------+
CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

       Only the ST_NOSUID and ST_RDONLY flags of the f_flag field  are  speci-
       fied  in  POSIX.1.   To  obtain definitions of the remaining flags, one
       must define _GNU_SOURCE.

NOTES
       The Linux kernel has system calls statfs(2) and fstatfs(2)  to  support
       this library call.

       In  glibc  versions  before  2.13,  statvfs() populated the bits of the
       f_flag field by scanning the mount options shown in /proc/mounts.  How-
       ever,  starting with Linux 2.6.36, the underlying statfs(2) system call
       provides the necessary information via the  f_flags  field,  and  since
       glibc  version  2.13,  the statvfs() function will use information from
       that field rather than scanning /proc/mounts.

       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.

SEE ALSO
       statfs(2)

COLOPHON
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       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

Linux                             2015-08-08                        STATVFS(3)
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