1.\" -*- nroff -*- 2.\" 3.\" Copyright (c) 1996 Doug Rabson 4.\" 5.\" All rights reserved. 6.\" 7.\" This program is free software. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 19.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28.\" 29.\" $FreeBSD$ 30.\" 31.Dd March 22, 2019 32.Dt VOP_FSYNC 9 33.Os 34.Sh NAME 35.Nm VOP_FDATASYNC , 36.Nm VOP_FSYNC 37.Nd flush file system buffers for a file 38.Sh SYNOPSIS 39.In sys/param.h 40.In sys/vnode.h 41.Ft int 42.Fn VOP_FDATASYNC "struct vnode *vp" "struct thread *td" 43.Ft int 44.Fn VOP_FSYNC "struct vnode *vp" "int waitfor" "struct thread *td" 45.Sh DESCRIPTION 46.Fn VOP_FSYNC 47ensures that a file can be recovered to its current state following a crash. 48That typically requires flushing the file's dirty buffers, its inode, and 49possibly other filesystem metadata to persistent media. 50.Fn VOP_FSYNC 51is used to implement the 52.Xr sync 2 53and 54.Xr fsync 2 55system calls. 56.Pp 57Its arguments are: 58.Bl -tag -width waitfor 59.It Fa vp 60The vnode of the file. 61.It Fa waitfor 62Whether the function should wait for I/O to complete. 63Possible values are: 64.Bl -tag -width MNT_NOWAIT 65.It Dv MNT_WAIT 66Synchronously wait for I/O to complete. 67.It Dv MNT_NOWAIT 68Start all I/O, but do not wait for it. 69.It Dv MNT_LAZY 70Push data not written by file system syncer. 71.El 72.It Fa td 73The calling thread. 74.El 75.Pp 76.Fn VOP_FDATASYNC 77is similar, but it does not require that all of the file's metadata be flushed. 78It only requires that the file's data be recoverable after a crash. 79That implies that the data itself must be flushed to disk, as well as some 80metadata such as the file's size but not necessarily its attributes. 81.Fn VOP_FDATASYNC 82should always wait for I/O to complete, as if called with 83.Dv MNT_WAIT . 84.Fn VOP_FDATASYNC 85is used to implement 86.Xr fdatasync 2 . 87.Sh LOCKS 88The vnode should be exclusively locked on entry, and stays locked on return. 89.Sh RETURN VALUES 90Zero is returned if the call is successful, otherwise an appropriate 91error code is returned. 92.Sh ERRORS 93.Bl -tag -width Er 94.It Bq Er ENOSPC 95The file system is full. 96.It Bq Er EDQUOT 97Quota exceeded. 98.El 99.Sh SEE ALSO 100.Xr vnode 9 101.Sh AUTHORS 102This manual page was written by 103.An Doug Rabson . 104