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.\" @(#)statfs.2 8.5 (Berkeley) 5/24/95
.\"
.Dd June 2, 2016
.Dt STATVFS 5
.Os
.Sh NAME
.Nm statvfs
.Nd file system statistics
.Sh SYNOPSIS
.In sys/types.h
.In sys/statvfs.h
.Sh DESCRIPTION
The
.In sys/statvfs.h
header defines the structures and functions that
return information about a mounted file system.
The
.Nm statvfs
structure is defined as follows:
.Bd -literal
typedef struct { int32_t val[2]; } fsid_t; /* file system id type */
#define VFS_NAMELEN 32 /* length of fs type name, including nul */
#define VFS_MNAMELEN 1024 /* length of buffer for returned name */
struct statvfs {
unsigned long f_flag; /* copy of mount exported flags */
unsigned long f_bsize; /* system block size */
unsigned long f_frsize; /* system fragment size */
unsigned long f_iosize; /* optimal file system block size */
/* The following are in units of f_frsize */
fsblkcnt_t f_blocks; /* number of blocks in file system */
fsblkcnt_t f_bfree; /* free blocks avail in file system */
fsblkcnt_t f_bavail; /* free blocks avail to non-root */
fsblkcnt_t f_bresvd; /* blocks reserved for root */
fsfilcnt_t f_files; /* total file nodes in file system */
fsfilcnt_t f_ffree; /* free file nodes in file system */
fsfilcnt_t f_favail; /* free file nodes avail to non-root */
fsfilcnt_t f_fresvd; /* file nodes reserved for root */
uint64_t f_syncreads; /* count of sync reads since mount */
uint64_t f_syncwrites; /* count of sync writes since mount */
uint64_t f_asyncreads; /* count of async reads since mount */
uint64_t f_asyncwrites; /* count of async writes since mount */
unsigned long f_fsid; /* POSIX compliant file system id */
fsid_t f_fsidx; /* NetBSD compatible file system id */
unsigned long f_namemax;/* maximum filename length */
uid_t f_owner; /* user that mounted the file system */
uint32_t f_spare[4]; /* spare space */
char f_fstypename[VFS_NAMELEN]; /* fs type name */
char f_mntonname[VFS_MNAMELEN]; /* directory on which mounted */
char f_mntfromname[VFS_MNAMELEN]; /* mounted file system */
};
.Ed
.Pp
The
.Fa f_flag
argument can have the following bits set:
.Bl -tag -width ST_SYNCHRONOUS
.It Dv ST_RDONLY
The filesystem is mounted read-only;
Even the super-user may not write on it.
.It Dv ST_NOEXEC
Files may not be executed from the filesystem.
.It Dv ST_NOSUID
Setuid and setgid bits on files are not honored when they are executed.
.It Dv ST_NODEV
Special files in the filesystem may not be opened.
.It Dv ST_UNION
Union with underlying filesystem instead of obscuring it.
.It Dv ST_SYNCHRONOUS
All I/O to the filesystem is done synchronously.
.It Dv ST_ASYNC
No filesystem I/O is done synchronously.
.It Dv ST_NOCOREDUMP
Don't write core dumps to this file system.
.It Dv ST_NOATIME
Never update access times.
.It Dv ST_SYMPERM
Recognize symbolic link permission.
.It Dv ST_NODEVMTIME
Never update modification times for device files.
.It Dv ST_LOG
Use logging (journalling).
.It Dv ST_LOCAL
The filesystem resides locally.
.It Dv ST_QUOTA
The filesystem has quotas enabled on it.
.It Dv ST_ROOTFS
Identifies the root filesystem.
.It Dv ST_EXRDONLY
The filesystem is exported read-only.
.It Dv ST_EXPORTED
The filesystem is exported for both reading and writing.
.It Dv ST_DEFEXPORTED
The filesystem is exported for both reading and writing to any Internet host.
.It Dv ST_EXPORTANON
The filesystem maps all remote accesses to the anonymous user.
.It Dv ST_EXKERB
The filesystem is exported with Kerberos uid mapping.
.It Dv ST_EXNORESPORT
Don't enforce reserved ports (NFS).
.It Dv ST_EXPUBLIC
Public export (WebNFS).
.El
.Pp
Fields that are undefined for a particular file system are set to \-1.
.Sh NOTES
.Bl -tag -width f_bavail
.It f_flag
The
.Fa f_flag
field is the same as the
.Fa f_flags
field in the
.Bx 4.3
.Ic statfs
system call.
.It f_fsid
Is defined to be
.Ft unsigned long
by the X/Open standard.
Unfortunately this is not enough space to store our
.Ft fsid_t ,
so we define an additional
.Fa f_fsidx
field.
.It f_bavail
Could historically be negative (in the
.Ic statfs
system call) when the used space has exceeded
the non-superuser free space.
In order to comply with the X/Open standard, we have to define
.Ft fsblkcnt_t
as an unsigned type, so in all cases where
.Fa f_bavail
would have been negative, we set it to 0.
In addition we provide
.Fa f_bresvd
which contains the amount of reserved blocks for the superuser, so
the old value of
.Fa f_bavail
can be easily computed as:
.Bd -literal
old_bavail = f_bfree - f_bresvd;
.Ed
.El
.Sh SEE ALSO
.Xr statvfs 2
.Sh HISTORY
The
.In sys/statvfs.h
header first appeared in
.Nx 3.0 .