STATFS(2)		   Linux Programmer's Manual		     STATFS(2)



NAME
       statfs, fstatfs - get filesystem statistics

SYNOPSIS
       #include <sys/vfs.h>    /* or <sys/statfs.h> */

       int statfs(const char *path, struct statfs *buf);
       int fstatfs(int fd, struct statfs *buf);

DESCRIPTION
       The  statfs()  system call returns information about a mounted filesys-
       tem.  path is the pathname of any file within the  mounted  filesystem.
       buf  is	a  pointer to a statfs structure defined approximately as fol-
       lows:

	   struct statfs {
	       __fsword_t f_type;    /* Type of filesystem (see below) */
	       __fsword_t f_bsize;   /* Optimal transfer block size */
	       fsblkcnt_t f_blocks;  /* Total data blocks in filesystem */
	       fsblkcnt_t f_bfree;   /* Free blocks in filesystem */
	       fsblkcnt_t f_bavail;  /* Free blocks available to
					unprivileged user */
	       fsfilcnt_t f_files;   /* Total file nodes in filesystem */
	       fsfilcnt_t f_ffree;   /* Free file nodes in filesystem */
	       fsid_t	  f_fsid;    /* Filesystem ID */
	       __fsword_t f_namelen; /* Maximum length of filenames */
	       __fsword_t f_frsize;  /* Fragment size (since Linux 2.6) */
	       __fsword_t f_flags;   /* Mount flags of filesystem
					(since Linux 2.6.36) */
	       __fsword_t f_spare[xxx];
			       /* Padding bytes reserved for future use */
	   };

	   Filesystem types:

	      ADFS_SUPER_MAGIC	    0xadf5
	      AFFS_SUPER_MAGIC	    0xadff
	      AFS_SUPER_MAGIC	    0x5346414f
	      ANON_INODE_FS_MAGIC   0x09041934
	      AUTOFS_SUPER_MAGIC    0x0187
	      BDEVFS_MAGIC	    0x62646576
	      BEFS_SUPER_MAGIC	    0x42465331
	      BFS_MAGIC		    0x1badface
	      BINFMTFS_MAGIC	    0x42494e4d
	      BPF_FS_MAGIC	    0xcafe4a11
	      BTRFS_SUPER_MAGIC	    0x9123683e
	      BTRFS_TEST_MAGIC	    0x73727279
	      CGROUP_SUPER_MAGIC    0x27e0eb
	      CGROUP2_SUPER_MAGIC   0x63677270
	      CIFS_MAGIC_NUMBER	    0xff534d42
	      CODA_SUPER_MAGIC	    0x73757245
	      COH_SUPER_MAGIC	    0x012ff7b7
	      CRAMFS_MAGIC	    0x28cd3d45
	      DEBUGFS_MAGIC	    0x64626720
	      DEVFS_SUPER_MAGIC	    0x1373
	      DEVPTS_SUPER_MAGIC    0x1cd1
	      ECRYPTFS_SUPER_MAGIC  0xf15f
	      EFIVARFS_MAGIC	    0xde5e81e4
	      EFS_SUPER_MAGIC	    0x00414a53
	      EXT_SUPER_MAGIC	    0x137d
	      EXT2_OLD_SUPER_MAGIC  0xef51
	      EXT2_SUPER_MAGIC	    0xef53
	      EXT3_SUPER_MAGIC	    0xef53
	      EXT4_SUPER_MAGIC	    0xef53
	      F2FS_SUPER_MAGIC	    0xf2f52010
	      FUSE_SUPER_MAGIC	    0x65735546
	      FUTEXFS_SUPER_MAGIC   0xbad1dea
	      HFS_SUPER_MAGIC	    0x4244
	      HOSTFS_SUPER_MAGIC    0x00c0ffee
	      HPFS_SUPER_MAGIC	    0xf995e849
	      HUGETLBFS_MAGIC	    0x958458f6
	      ISOFS_SUPER_MAGIC	    0x9660
	      JFFS2_SUPER_MAGIC	    0x72b6
	      JFS_SUPER_MAGIC	    0x3153464a
	      MINIX_SUPER_MAGIC	    0x137f /* orig. minix */
	      MINIX_SUPER_MAGIC2    0x138f /* 30 char minix */
	      MINIX2_SUPER_MAGIC    0x2468 /* minix V2 */
	      MINIX2_SUPER_MAGIC2   0x2478 /* minix V2, 30 char names */
	      MINIX3_SUPER_MAGIC    0x4d5a /* minix V3 fs, 60 char names */
	      MQUEUE_MAGIC	    0x19800202
	      MSDOS_SUPER_MAGIC	    0x4d44
	      MTD_INODE_FS_MAGIC    0x11307854
	      NCP_SUPER_MAGIC	    0x564c
	      NFS_SUPER_MAGIC	    0x6969
	      NILFS_SUPER_MAGIC	    0x3434
	      NSFS_MAGIC	    0x6e736673
	      NTFS_SB_MAGIC	    0x5346544e
	      OCFS2_SUPER_MAGIC	    0x7461636f
	      OPENPROM_SUPER_MAGIC  0x9fa1
	      OVERLAYFS_SUPER_MAGIC 0x794c7630
	      PIPEFS_MAGIC	    0x50495045
	      PROC_SUPER_MAGIC	    0x9fa0
	      PSTOREFS_MAGIC	    0x6165676c
	      QNX4_SUPER_MAGIC	    0x002f
	      QNX6_SUPER_MAGIC	    0x68191122
	      RAMFS_MAGIC	    0x858458f6
	      REISERFS_SUPER_MAGIC  0x52654973
	      ROMFS_MAGIC	    0x7275
	      SECURITYFS_MAGIC	    0x73636673
	      SELINUX_MAGIC	    0xf97cff8c
	      SMACK_MAGIC	    0x43415d53
	      SMB_SUPER_MAGIC	    0x517b
	      SOCKFS_MAGIC	    0x534f434b
	      SQUASHFS_MAGIC	    0x73717368
	      SYSFS_MAGIC	    0x62656572
	      SYSV2_SUPER_MAGIC	    0x012ff7b6
	      SYSV4_SUPER_MAGIC	    0x012ff7b5
	      TMPFS_MAGIC	    0x01021994
	      TRACEFS_MAGIC	    0x74726163
	      UDF_SUPER_MAGIC	    0x15013346
	      UFS_MAGIC		    0x00011954
	      USBDEVICE_SUPER_MAGIC 0x9fa2
	      V9FS_MAGIC	    0x01021997
	      VXFS_SUPER_MAGIC	    0xa501fcf5
	      XENFS_SUPER_MAGIC	    0xabba1974
	      XENIX_SUPER_MAGIC	    0x012ff7b4
	      XFS_SUPER_MAGIC	    0x58465342
	      _XIAFS_SUPER_MAGIC    0x012fd16d

       Most    of     these	MAGIC	  constants	are	defined	    in
       /usr/include/linux/magic.h, and some are hardcoded in kernel sources.

       The  f_flags is a bit mask indicating mount options for the filesystem.
       It contains zero or more of the following bits:

       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)).

       Nobody knows what f_fsid is supposed to contain (but see below).

       Fields that are undefined for a particular filesystem are set to 0.

       fstatfs() 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 (statfs()) Search permission is denied for a  component  of  the
	      path prefix of path.  (See also path_resolution(7).)

       EBADF  (fstatfs()) 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  (statfs()) Too many symbolic links were encountered in translat-
	      ing path.

       ENAMETOOLONG
	      (statfs()) path is too long.

       ENOENT (statfs()) The file referred to by path does not exist.

       ENOMEM Insufficient kernel memory was available.

       ENOSYS The filesystem does not support this call.

       ENOTDIR
	      (statfs()) 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
       Linux-specific.	The Linux statfs() was inspired by the 4.4BSD one (but
       they do not use the same structure).

NOTES
       The  __fsword_t	type  used  for various fields in the statfs structure
       definition is a glibc internal type, not intended for public use.  This
       leaves  the  programmer	in a bit of a conundrum when trying to copy or
       compare	these  fields  to  local  variables  in	 a   program.	 Using
       unsigned int for such variables suffices on most systems.

       The  original  Linux  statfs()  and  fstatfs()  system  calls  were not
       designed with extremely large file sizes in mind.  Subsequently,	 Linux
       2.6 added new statfs64() and fstatfs64() system calls that employ a new
       structure, statfs64.  The new structure contains the same fields as the
       original	 statfs	 structure,  but  the  sizes  of  various  fields  are
       increased, to accommodate large file sizes.   The  glibc	 statfs()  and
       fstatfs()  wrapper functions transparently deal with the kernel differ-
       ences.

       Some  systems  have  only  <sys/vfs.h>,	 other	 systems   also	  have
       <sys/statfs.h>,	where  the  former  includes  the latter.  So it seems
       including the former is the best choice.

       LSB has deprecated the library calls statfs() and fstatfs()  and	 tells
       us to use statvfs(2) and fstatvfs(2) instead.

   The f_fsid field
       Solaris,	 Irix  and  POSIX have a system call statvfs(2) that returns a
       struct statvfs (defined in <sys/statvfs.h>) containing an unsigned long
       f_fsid.	 Linux,	 SunOS, HP-UX, 4.4BSD have a system call statfs() that
       returns a struct statfs (defined in <sys/vfs.h>)	 containing  a	fsid_t
       f_fsid,	where  fsid_t  is defined as struct { int val[2]; }.  The same
       holds for FreeBSD, except that it uses the include file <sys/mount.h>.

       The general idea is that f_fsid contains some random  stuff  such  that
       the  pair (f_fsid,ino) uniquely determines a file.  Some operating sys-
       tems use (a variation on) the device number, or the device number  com-
       bined  with  the	 filesystem  type.  Several operating systems restrict
       giving out the f_fsid field to the superuser  only  (and	 zero  it  for
       unprivileged  users),  because  this field is used in the filehandle of
       the filesystem when NFS-exported, and giving it out is a security  con-
       cern.

       Under  some operating systems, the fsid can be used as the second argu-
       ment to the sysfs(2) system call.

BUGS
       From Linux 2.6.38 up to and including Linux 3.1, fstatfs() failed  with
       the error ENOSYS for file descriptors created by pipe(2).

SEE ALSO
       stat(2), statvfs(3), path_resolution(7)

COLOPHON
       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2017-03-13			     STATFS(2)