e42b096439
EINTEGRITY was previously documented as a UFS-specific error for mount(2). This documents EINTEGRITY as a filesystem-independent error that may be reported by the backing store of a filesystem. While here, document EIO as a filesystem-independent error for both mount(2) and posix_fadvise(2). EIO was previously only documented for UFS for mount(2). Reviewed by: mckusick Suggested by: mckusick MFC after: 2 weeks Sponsored by: Chelsio Communications Differential Revision: https://reviews.freebsd.org/D24168
144 lines
4.3 KiB
Groff
144 lines
4.3 KiB
Groff
.\" Copyright (c) 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)madvise.2 8.1 (Berkeley) 6/9/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 30, 2020
|
|
.Dt POSIX_FADVISE 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm posix_fadvise
|
|
.Nd give advice about use of file data
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In fcntl.h
|
|
.Ft int
|
|
.Fn posix_fadvise "int fd" "off_t offset" "off_t len" "int advice"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn posix_fadvise
|
|
system call
|
|
allows a process to describe to the system its data access behavior for an
|
|
open file descriptor
|
|
.Fa fd .
|
|
The advice covers the data starting at offset
|
|
.Fa offset
|
|
and continuing for
|
|
.Fa len
|
|
bytes.
|
|
If
|
|
.Fa len
|
|
is zero,
|
|
all data from
|
|
.Fa offset
|
|
to the end of the file is covered.
|
|
.Pp
|
|
The behavior is specified by the
|
|
.Fa advice
|
|
parameter and may be one of:
|
|
.Bl -tag -width POSIX_FADV_SEQUENTIAL
|
|
.It Dv POSIX_FADV_NORMAL
|
|
Tells the system to revert to the default data access behavior.
|
|
.It Dv POSIX_FADV_RANDOM
|
|
Is a hint that file data will be accessed randomly,
|
|
and prefetching is likely not advantageous.
|
|
.It Dv POSIX_FADV_SEQUENTIAL
|
|
Tells the system that file data will be accessed sequentially.
|
|
This currently does nothing as the default behavior uses heuristics to
|
|
detect sequential behavior.
|
|
.It Dv POSIX_FADV_WILLNEED
|
|
Tells the system that the specified data will be accessed in the near future.
|
|
The system may initiate an asynchronous read of the data if it is not already
|
|
present in memory.
|
|
.It Dv POSIX_FADV_DONTNEED
|
|
Tells the system that the specified data will not be accessed in the near
|
|
future.
|
|
The system may decrease the in-memory priority of clean data within the
|
|
specified range and future access to this data may require a read operation.
|
|
.It Dv POSIX_FADV_NOREUSE
|
|
Tells the system that the specified data will only be accessed once and
|
|
then not reused.
|
|
The system may decrease the in-memory priority of data once it has been
|
|
read or written.
|
|
Future access to this data may require a read operation.
|
|
.El
|
|
.Sh RETURN VALUES
|
|
If successful,
|
|
.Fn posix_fadvise
|
|
returns zero.
|
|
It returns an error on failure, without setting
|
|
.Va errno .
|
|
.Sh ERRORS
|
|
Possible failure conditions:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa fd
|
|
argument is not a valid file descriptor.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa advice
|
|
argument is not valid.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa offset
|
|
or
|
|
.Fa len
|
|
arguments are negative,
|
|
or
|
|
.Fa offset
|
|
+
|
|
.Fa len
|
|
is greater than the maximum file size.
|
|
.It Bq Er ENODEV
|
|
The
|
|
.Fa fd
|
|
argument does not refer to a regular file.
|
|
.It Bq Er ESPIPE
|
|
The
|
|
.Fa fd
|
|
argument is associated with a pipe or FIFO.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while reading from or writing to a file system.
|
|
.It Bq Er EINTEGRITY
|
|
Corrupted data was detected while reading from the file system.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr madvise 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn posix_fadvise
|
|
interface conforms to
|
|
.St -p1003.1-2001 .
|
|
.Sh HISTORY
|
|
The
|
|
.Fn posix_fadvise
|
|
system call first appeared in
|
|
.Fx 9.1 .
|