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 statfs() system call
returns information about a mounted filesystem. path is the pathname of any
file within the mounted filesystem. buf is a pointer to a
statfs structure defined
approximately as follows:
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 BDEVFS_MAGIC 0x62646576 BEFS_SUPER_MAGIC 0x42465331 BFS_MAGIC 0x1badface BINFMTFS_MAGIC 0x42494e4d BTRFS_SUPER_MAGIC 0x9123683e CGROUP_SUPER_MAGIC 0x27e0eb 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 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 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 NCP_SUPER_MAGIC 0x564c NFS_SUPER_MAGIC 0x6969 NILFS_SUPER_MAGIC 0x3434 NTFS_SB_MAGIC 0x5346544e OCFS2_SUPER_MAGIC 0x7461636f OPENPROM_SUPER_MAGIC 0x9fa1 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 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 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 file system. It
contains zero or more of the following bits:
ST_MANDLOCKMandatory locking is permitted on the filesystem (see fcntl(2)).
ST_NOATIMEDo not update access times; see mount(2).
ST_NODEVDisallow access to device special files on this filesystem.
ST_NODIRATIMEDo not update directory access times; see mount(2).
ST_NOEXECExecution of programs is disallowed on this filesystem.
ST_NOSUIDThe set-user-ID and set-group-ID bits are ignored by exec(3) for executable files on this filesystem
ST_RDONLYThis filesystem is mounted read-only.
ST_RELATIMEUpdate atime relative to mtime/ctime; see mount(2).
ST_SYNCHRONOUSWrites 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.
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
(statfs()) Search
permission is denied for a component of the path prefix
of path. (See
also path_resolution(7).)
(fstatfs()) fd is not a valid open
file descriptor.
buf or
path points to
an invalid address.
This call was interrupted by a signal; see signal(7).
An I/O error occurred while reading from the filesystem.
(statfs()) Too many
symbolic links were encountered in translating
path.
(statfs()) path is too long.
(statfs()) The file
referred to by path does not exist.
Insufficient kernel memory was available.
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 __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 differences.
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.
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 number, or the device number combined 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 concern.
Under some operating systems, the fsid can be used as the
second argument to the sysfs(2) system call.
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).
This page is part of release 4.07 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/.
|
Copyright (C) 2003 Andries Brouwer (aebcwi.nl) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END Modified 2003-08-17 by Walter Harms Modified 2004-06-23 by Michael Kerrisk <mtk.manpagesgmail.com> |