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Linux 2.6 - man page for fstatfs (linux section 2)

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

       statfs, fstatfs - get filesystem statistics

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

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

       The  function  statfs() returns information about a mounted filesystem.	path is the path-
       name of any file within the mounted filesystem.	buf is a pointer to  a	statfs	structure
       defined approximately as follows:

	   #if __WORDSIZE == 32 	 /* System word size */
	   # define __SWORD_TYPE	   int
	   #else /* __WORDSIZE == 64 */
	   # define __SWORD_TYPE	 long int

	   struct statfs {
	       __SWORD_TYPE f_type;    /* type of filesystem (see below) */
	       __SWORD_TYPE f_bsize;   /* optimal transfer block size */
	       fsblkcnt_t   f_blocks;  /* total data blocks in filesystem */
	       fsblkcnt_t   f_bfree;   /* free blocks in fs */
	       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 fs */
	       fsid_t	    f_fsid;    /* filesystem id */
	       __SWORD_TYPE f_namelen; /* maximum length of filenames */
	       __SWORD_TYPE f_frsize;  /* fragment size (since Linux 2.6) */
	       __SWORD_TYPE f_spare[5];

	   Filesystem types:

	      ADFS_SUPER_MAGIC	    0xadf5
	      BEFS_SUPER_MAGIC	    0x42465331
	      BFS_MAGIC 	    0x1BADFACE
	      CIFS_MAGIC_NUMBER     0xFF534D42
	      CODA_SUPER_MAGIC	    0x73757245
	      COH_SUPER_MAGIC	    0x012FF7B7
	      CRAMFS_MAGIC	    0x28cd3d45
	      DEVFS_SUPER_MAGIC     0x1373
	      EFS_SUPER_MAGIC	    0x00414A53
	      EXT_SUPER_MAGIC	    0x137D
	      EXT2_SUPER_MAGIC	    0xEF53
	      EXT3_SUPER_MAGIC	    0xEF53
	      EXT4_SUPER_MAGIC	    0xEF53
	      HFS_SUPER_MAGIC	    0x4244
	      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 */
	      MSDOS_SUPER_MAGIC     0x4d44
	      NCP_SUPER_MAGIC	    0x564c
	      NFS_SUPER_MAGIC	    0x6969
	      NTFS_SB_MAGIC	    0x5346544e
	      PROC_SUPER_MAGIC	    0x9fa0
	      QNX4_SUPER_MAGIC	    0x002f
	      REISERFS_SUPER_MAGIC  0x52654973
	      ROMFS_MAGIC	    0x7275
	      SMB_SUPER_MAGIC	    0x517B
	      SYSV2_SUPER_MAGIC     0x012FF7B6
	      SYSV4_SUPER_MAGIC     0x012FF7B5
	      TMPFS_MAGIC	    0x01021994
	      UDF_SUPER_MAGIC	    0x15013346
	      UFS_MAGIC 	    0x00011954
	      VXFS_SUPER_MAGIC	    0xa501FCF5
	      XENIX_SUPER_MAGIC     0x012FF7B4
	      XFS_SUPER_MAGIC	    0x58465342
	      _XIAFS_SUPER_MAGIC    0x012FD16D

       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.

       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.

       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.

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

       ELOOP  (statfs()) Too many symbolic links were encountered in translating path.

	      (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.

	      (statfs()) A component of the path prefix of path is not a directory.

	      Some values were too large to be represented in the returned struct.

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

       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  trans-
       parently deal with the kernel differences.

       Some systems only have <sys/vfs.h>, other systems also have <sys/statfs.h>, where the for-
       mer 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 systems use (a variation on) the  device  num-
       ber, or the device number combined with the filesystem type.  Several OSes 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 concern.

       Under some operating systems the fsid can be used as second argument to the sysfs(2)  sys-
       tem call.

       stat(2), statvfs(2), path_resolution(7)

       This  page  is  part of release 3.55 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at

Linux					    2010-11-21					STATFS(2)

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