--- name: "statfs64" section: "2" platform: "linux" package: "man-pages" version: "6.19-1" release: "Arch Linux 2026-11-01" platforms: ["linux", "macos"] url: "https://new.carta.tech/statfs/2" --- # statfs64(2) get filesystem statistics Part of [statfs(2)](/statfs/2.md). ## NAME statfs, fstatfs - get filesystem statistics ## LIBRARY Standard C library (*libc*, *-lc*) ## SYNOPSIS ``` #include /* or */ ``` **int statfs(const char \****path***, struct statfs \****buf***);** **int fstatfs(int** *fd***, struct statfs \****buf***);** Unless you need the *f\_type* field, you should use the standard [**statvfs**(3)](/statvfs/3.md) interface instead. ## DESCRIPTION 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 inodes in filesystem */ fsfilcnt_t f_ffree; /* Free inodes 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 */ }; ``` The following filesystem types may appear in *f\_type*: ``` ADFS_SUPER_MAGIC 0xadf5 AFFS_SUPER_MAGIC 0xadff AFS_SUPER_MAGIC 0x5346414f ANON_INODE_FS_MAGIC 0x09041934 /* Anonymous inode FS (for pseudofiles that have no name; e.g., epoll, signalfd, bpf) */ 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 /* Cgroup pseudo FS */ CGROUP2_SUPER_MAGIC 0x63677270 /* Cgroup v2 pseudo FS */ CIFS_MAGIC_NUMBER 0xff534d42 CODA_SUPER_MAGIC 0x73757245 COH_SUPER_MAGIC 0x012ff7b7 CRAMFS_MAGIC 0x28cd3d45 DEBUGFS_MAGIC 0x64626720 DEVFS_SUPER_MAGIC 0x1373 /* Linux 2.6.17 and earlier */ DEVPTS_SUPER_MAGIC 0x1cd1 ECRYPTFS_SUPER_MAGIC 0xf15f EFIVARFS_MAGIC 0xde5e81e4 EFS_SUPER_MAGIC 0x00414a53 EXT_SUPER_MAGIC 0x137d /* Linux 2.0 and earlier */ 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 /* Unused */ 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 /* original minix FS */ MINIX_SUPER_MAGIC2 0x138f /* 30 char minix FS */ MINIX2_SUPER_MAGIC 0x2468 /* minix V2 FS */ MINIX2_SUPER_MAGIC2 0x2478 /* minix V2 FS, 30 char names */ MINIX3_SUPER_MAGIC 0x4d5a /* minix V3 FS, 60 char names */ MQUEUE_MAGIC 0x19800202 /* POSIX message queue FS */ 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 /* /proc FS */ 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 SMB2_MAGIC_NUMBER 0xfe534d42 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 /* Linux 2.0 and earlier */ ``` Most of these MAGIC constants are defined in */usr/include/linux/magic.h*, and some are hardcoded in kernel sources. The *f\_flags* field 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)](/fcntl/2.md)). - **ST\_NOATIME** Do not update access times; see [**mount**(2)](/mount/2.md). - **ST\_NODEV** Disallow access to device special files on this filesystem. - **ST\_NODIRATIME** Do not update directory access times; see [**mount**(2)](/mount/2.md). - **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)](/exec/3.md) 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)](/mount/2.md). - **ST\_SYNCHRONOUS** Writes are synched to the filesystem immediately (see the description of **O\_SYNC** in [**open**(2)](/open/2.md)). - **ST\_NOSYMFOLLOW** (since Linux 5.10) Symbolic links are not followed when resolving paths; see [**mount**(2)](/mount/2.md). 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 to indicate the error. ## ERRORS - **EACCES** (**statfs**()) Search permission is denied for a component of the path prefix of *path*. (See also [**path\_resolution**(7)](/path_resolution/7.md).) - **EBADF** (**fstatfs**()) *fd* is not a valid open file descriptor. - **EFAULT** *buf* or *path* points to an invalid address. - **EINTR** The call was interrupted by a signal; see [**signal**(7)](/signal/7.md). - **EIO** An I/O error occurred while reading from the filesystem. - **ELOOP** (**statfs**()) Too many symbolic links were encountered in translating *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. ## VERSIONS ### The f\_fsid field Solaris, Irix, and POSIX have a system call [**statvfs**(2)](/statvfs/2.md) that returns a *struct statvfs* (defined in *\*) containing an *unsigned long* *f\_fsid*. Linux, SunOS, HP-UX, 4.4BSD have a system call **statfs**() that returns a *struct statfs* (defined in *\*) 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 *\*. 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)](/sysfs/2.md) system call. ## STANDARDS Linux. ## HISTORY 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 transparently deal with the kernel differences. LSB has deprecated the library calls **statfs**() and **fstatfs**() and tells us to use [**statvfs**(3)](/statvfs/3.md) and [**fstatvfs**(3)](/fstatvfs/3.md) instead. ## 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. Some systems have only *\*, other systems also have *\*, where the former includes the latter. So it seems including the former is the best choice. ## 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)](/pipe/2.md). ## SEE ALSO [**stat**(2)](/stat/2.md), [**statvfs**(3)](/statvfs/3.md), [**path\_resolution**(7)](/path_resolution/7.md)