freebsd-skq/lib/libc/sys/statfs.2
Konstantin Belousov 6992112349 Commit the 64-bit inode project.
Extend the ino_t, dev_t, nlink_t types to 64-bit ints.  Modify
struct dirent layout to add d_off, increase the size of d_fileno
to 64-bits, increase the size of d_namlen to 16-bits, and change
the required alignment.  Increase struct statfs f_mntfromname[] and
f_mntonname[] array length MNAMELEN to 1024.

ABI breakage is mitigated by providing compatibility using versioned
symbols, ingenious use of the existing padding in structures, and
by employing other tricks.  Unfortunately, not everything can be
fixed, especially outside the base system.  For instance, third-party
APIs which pass struct stat around are broken in backward and
forward incompatible ways.

Kinfo sysctl MIBs ABI is changed in backward-compatible way, but
there is no general mechanism to handle other sysctl MIBS which
return structures where the layout has changed. It was considered
that the breakage is either in the management interfaces, where we
usually allow ABI slip, or is not important.

Struct xvnode changed layout, no compat shims are provided.

For struct xtty, dev_t tty device member was reduced to uint32_t.
It was decided that keeping ABI compat in this case is more useful
than reporting 64-bit dev_t, for the sake of pstat.

Update note: strictly follow the instructions in UPDATING.  Build
and install the new kernel with COMPAT_FREEBSD11 option enabled,
then reboot, and only then install new world.

Credits: The 64-bit inode project, also known as ino64, started life
many years ago as a project by Gleb Kurtsou (gleb).  Kirk McKusick
(mckusick) then picked up and updated the patch, and acted as a
flag-waver.  Feedback, suggestions, and discussions were carried
by Ed Maste (emaste), John Baldwin (jhb), Jilles Tjoelker (jilles),
and Rick Macklem (rmacklem).  Kris Moore (kris) performed an initial
ports investigation followed by an exp-run by Antoine Brodin (antoine).
Essential and all-embracing testing was done by Peter Holm (pho).
The heavy lifting of coordinating all these efforts and bringing the
project to completion were done by Konstantin Belousov (kib).

Sponsored by:	The FreeBSD Foundation (emaste, kib)
Differential revision:	https://reviews.freebsd.org/D10439
2017-05-23 09:29:05 +00:00

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.\" @(#)statfs.2 8.5 (Berkeley) 5/24/95
.\" $FreeBSD$
.\"
.Dd February 13, 2017
.Dt STATFS 2
.Os
.Sh NAME
.Nm statfs
.Nd get file system statistics
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/param.h
.In sys/mount.h
.Ft int
.Fn statfs "const char *path" "struct statfs *buf"
.Ft int
.Fn fstatfs "int fd" "struct statfs *buf"
.Sh DESCRIPTION
The
.Fn statfs
system call
returns information about a mounted file system.
The
.Fa path
argument
is the path name of any file within the mounted file system.
The
.Fa buf
argument
is a pointer to a
.Vt statfs
structure defined as follows:
.Bd -literal
typedef struct fsid { int32_t val[2]; } fsid_t; /* file system id type */
/*
* filesystem statistics
*/
#define MFSNAMELEN 16 /* length of type name including null */
#define MNAMELEN 1024 /* size of on/from name bufs */
#define STATFS_VERSION 0x20140518 /* current version number */
struct statfs {
uint32_t f_version; /* structure version number */
uint32_t f_type; /* type of filesystem */
uint64_t f_flags; /* copy of mount exported flags */
uint64_t f_bsize; /* filesystem fragment size */
uint64_t f_iosize; /* optimal transfer block size */
uint64_t f_blocks; /* total data blocks in filesystem */
uint64_t f_bfree; /* free blocks in filesystem */
int64_t f_bavail; /* free blocks avail to non-superuser */
uint64_t f_files; /* total file nodes in filesystem */
int64_t f_ffree; /* free nodes avail to non-superuser */
uint64_t f_syncwrites; /* count of sync writes since mount */
uint64_t f_asyncwrites; /* count of async writes since mount */
uint64_t f_syncreads; /* count of sync reads since mount */
uint64_t f_asyncreads; /* count of async reads since mount */
uint64_t f_spare[10]; /* unused spare */
uint32_t f_namemax; /* maximum filename length */
uid_t f_owner; /* user that mounted the filesystem */
fsid_t f_fsid; /* filesystem id */
char f_charspare[80]; /* spare string space */
char f_fstypename[MFSNAMELEN]; /* filesystem type name */
char f_mntfromname[MNAMELEN]; /* mounted filesystem */
char f_mntonname[MNAMELEN]; /* directory on which mounted */
};
.Ed
.Pp
The flags that may be returned include:
.Bl -tag -width MNT_SYNCHRONOUS
.It Dv MNT_RDONLY
The file system is mounted read-only;
Even the super-user may not write on it.
.It Dv MNT_NOEXEC
Files may not be executed from the file system.
.It Dv MNT_NOSUID
Setuid and setgid bits on files are not honored when they are executed.
.It Dv MNT_SYNCHRONOUS
All I/O to the file system is done synchronously.
.It Dv MNT_ASYNC
No file system I/O is done synchronously.
.It Dv MNT_SOFTDEP
Soft updates being done (see
.Xr ffs 7 ) .
.It Dv MNT_GJOURNAL
Journaling with gjournal is enabled (see
.Xr gjournal 8 ) .
.It Dv MNT_SUIDDIR
Special handling of SUID bit on directories.
.It Dv MNT_UNION
Union with underlying file system.
.It Dv MNT_NOSYMFOLLOW
Symbolic links are not followed.
.It Dv MNT_NOCLUSTERR
Read clustering is disabled.
.It Dv MNT_NOCLUSTERW
Write clustering is disabled.
.\".It Dv MNT_JAILDEVFS
.\"XXX
.It Dv MNT_MULTILABEL
Mandatory Access Control (MAC) support for individual objects
(see
.Xr mac 4 ) .
.It Dv MNT_ACLS
Access Control List (ACL) support enabled.
.It Dv MNT_LOCAL
The file system resides locally.
.It Dv MNT_QUOTA
The file system has quotas enabled on it.
.It Dv MNT_ROOTFS
Identifies the root file system.
.It Dv MNT_EXRDONLY
The file system is exported read-only.
.It Dv MNT_NOATIME
Updating of file access times is disabled.
.It Dv MNT_USER
The file system has been mounted by a user.
.\".It Dv MNT_IGNORE
.\"XXX
.It Dv MNT_EXPORTED
The file system is exported for both reading and writing.
.It Dv MNT_DEFEXPORTED
The file system is exported for both reading and writing to any Internet host.
.It Dv MNT_EXPORTANON
The file system maps all remote accesses to the anonymous user.
.It Dv MNT_EXKERB
The file system is exported with Kerberos uid mapping.
.It Dv MNT_EXPUBLIC
The file system is exported publicly (WebNFS).
.El
.Pp
Fields that are undefined for a particular file system are set to -1.
The
.Fn fstatfs
system call
returns the same information about an open file referenced by descriptor
.Fa fd .
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
The
.Fn statfs
system call
fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er ENOTDIR
A component of the path prefix of
.Fa path
is not a directory.
.It Bq Er ENAMETOOLONG
The length of a component of
.Fa path
exceeds 255 characters,
or the length of
.Fa path
exceeds 1023 characters.
.It Bq Er ENOENT
The file referred to by
.Fa path
does not exist.
.It Bq Er EACCES
Search permission is denied for a component of the path prefix of
.Fa path .
.It Bq Er ELOOP
Too many symbolic links were encountered in translating
.Fa path .
.It Bq Er EFAULT
The
.Fa buf
or
.Fa path
argument
points to an invalid address.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Pp
The
.Fn fstatfs
system call
fails if one or more of the following are true:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa fd
argument
is not a valid open file descriptor.
.It Bq Er EFAULT
The
.Fa buf
argument
points to an invalid address.
.It Bq Er EIO
An
.Tn I/O
error occurred while reading from or writing to the file system.
.El
.Sh SEE ALSO
.Xr fhstatfs 2
.Sh HISTORY
The
.Fn statfs
system call first appeared in
.Bx 4.4 .