NetBSD/share/man/man5/statvfs.5

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.\"	@(#)statfs.2	8.5 (Berkeley) 5/24/95
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.Dd November 12, 2005
.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
.Aq Pa 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 */

	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_MAGICLINKS
Expand special strings
.Po
beginning with
.Dq @
.Pc
when traversing symbolic links.
See
.Xr symlink 7
for a list of supported strings.
.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_SOFTDEP
Use soft dependencies.
.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
.Xr statfs 2
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
.Xr statfs 2
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
.Aq Pa sys/statvfs.h
header first appeared in
.Nx 3.0 .