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107 lines
3.4 KiB
Groff
107 lines
3.4 KiB
Groff
.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 1996 Doug Rabson
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.\"
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.\" All rights reserved.
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.\"
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.\" Copyright (c) 2019 The FreeBSD Foundation
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.\"
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.\" Portions of this documentation were written by BFF Storage Systems under
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.\" sponsorship from the FreeBSD Foundation.
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.\"
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.\" This program is free software.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd March 22, 2019
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.Dt VOP_FSYNC 9
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.Os
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.Sh NAME
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.Nm VOP_FDATASYNC ,
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.Nm VOP_FSYNC
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.Nd flush file system buffers for a file
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.Sh SYNOPSIS
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.In sys/param.h
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.In sys/vnode.h
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.Ft int
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.Fn VOP_FDATASYNC "struct vnode *vp" "struct thread *td"
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.Ft int
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.Fn VOP_FSYNC "struct vnode *vp" "int waitfor" "struct thread *td"
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.Sh DESCRIPTION
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.Fn VOP_FSYNC
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ensures that a file can be recovered to its current state following a crash.
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That typically requires flushing the file's dirty buffers, its inode, and
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possibly other filesystem metadata to persistent media.
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.Fn VOP_FSYNC
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is used to implement the
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.Xr sync 2
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and
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.Xr fsync 2
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system calls.
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.Pp
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Its arguments are:
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.Bl -tag -width waitfor
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.It Fa vp
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The vnode of the file.
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.It Fa waitfor
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Whether the function should wait for I/O to complete.
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Possible values are:
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.Bl -tag -width MNT_NOWAIT
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.It Dv MNT_WAIT
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Synchronously wait for I/O to complete.
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.It Dv MNT_NOWAIT
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Start all I/O, but do not wait for it.
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.It Dv MNT_LAZY
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Push data not written by file system syncer.
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.El
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.It Fa td
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The calling thread.
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.El
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.Pp
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.Fn VOP_FDATASYNC
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is similar, but it does not require that all of the file's metadata be flushed.
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It only requires that the file's data be recoverable after a crash.
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That implies that the data itself must be flushed to disk, as well as some
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metadata such as the file's size but not necessarily its attributes.
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.Fn VOP_FDATASYNC
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should always wait for I/O to complete, as if called with
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.Dv MNT_WAIT .
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.Fn VOP_FDATASYNC
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is used to implement
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.Xr fdatasync 2 .
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.Sh LOCKS
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The vnode should be exclusively locked on entry, and stays locked on return.
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.Sh RETURN VALUES
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Zero is returned if the call is successful, otherwise an appropriate
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error code is returned.
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er ENOSPC
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The file system is full.
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.It Bq Er EDQUOT
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Quota exceeded.
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.El
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.Sh SEE ALSO
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.Xr vnode 9
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.Sh AUTHORS
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This manual page was written by
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.An Doug Rabson .
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