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Diffstat (limited to 'static/netbsd/man2/fsync.2')
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diff --git a/static/netbsd/man2/fsync.2 b/static/netbsd/man2/fsync.2 new file mode 100644 index 00000000..0c2dec4b --- /dev/null +++ b/static/netbsd/man2/fsync.2 @@ -0,0 +1,196 @@ +.\" $NetBSD: fsync.2,v 1.21 2021/02/17 22:55:20 wiz Exp $ +.\" +.\" Copyright (c) 1983, 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. +.\" +.\" @(#)fsync.2 8.1 (Berkeley) 6/4/93 +.\" +.Dd February 17, 2021 +.Dt FSYNC 2 +.Os +.Sh NAME +.Nm fsync , +.Nm fsync_range +.Nd "synchronize a file's in-core state with that on disk" +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In unistd.h +.Ft int +.Fn fsync "int fd" +.Ft int +.Fn fsync_range "int fd" "int how" "off_t start" "off_t length" +.Sh DESCRIPTION +.Fn fsync +causes all modified data and attributes of +.Fa fd +to be written to a permanent storage device. +This normally results in all in-core modified copies +of buffers for the associated file to be written to a disk. +.Pp +.Fn fsync_range +is similar, but provides control over the region of the file +to be synchronized, and the method of synchronization. +.Pp +These functions should be used by programs that require a file to be +in a known state, for example, in building a simple transaction +facility. +.Pp +Note that writing the data to a permanent storage device +does not necessarily write the data to permanent storage media +within that device; +for example, after writing data to a disk device, the data might +reside in a cache within the device, but not yet on +more permanent storage within the device. +Neither +.Fn fsync +nor the default behavior of +.Fn fsync_range +(without the +.Dv FDISKSYNC +flag) +will flush disk caches, +because they assume that storage devices are able to ensure that +completed writes are transferred to media some time between the +write and a power failure or system crash. +.Pp +.Fn fsync_range +causes all modified data starting at +.Fa start +for length +.Fa length +of +.Fa fd +to be written to a permanent storage device. +If the +.Fa length +parameter is zero, +.Fn fsync_range +will synchronize all of the file data. +.Pp +.Fn fsync_range +takes a +.Fa how +parameter which contains one or more of the following flags: +.Bl -tag -width FDATASYNC -offset indent +.It Dv FDATASYNC +Synchronize the file data and sufficient meta-data to retrieve the +data for the specified range. +This is equivalent to +.Xr fdatasync 2 +on the specified range. +.It Dv FFILESYNC +Synchronize all modified file data and meta-data for the specified range. +This is equivalent to +.Nm +on the specified range. +.It Dv FDISKSYNC +Request the destination device to ensure that the relevant data +and meta-data is flushed from any cache to permanent storage media. +In the present implementation, the entire cache on the affected device will +be flushed, and this may have a significant impact on performance. +.El +.Pp +The +.Dv FDATASYNC +and +.Dv FFILESYNC +flags are mutually exclusive. +Either of those flags may be combined with the +.Dv FDISKSYNC +flag. +.Pp +Note that +.Fn fsync_range +requires that the file +.Fa fd +must be open for writing, whereas +.Fn fsync +does not. +.Sh RETURN VALUES +A 0 value is returned on success. +A \-1 value indicates an error. +.Sh ERRORS +.Fn fsync +or +.Fn fsync_range +fail if: +.Bl -tag -width Er +.It Bq Er EBADF +.Fa fd +is not a valid descriptor. +.It Bq Er EINVAL +.Fa fd +refers to a socket, not to a file. +.It Bq Er EIO +An I/O error occurred while reading from or writing to the file system. +.El +.Pp +Additionally, +.Fn fsync_range +fails if: +.Bl -tag -width Er +.It Bq Er EBADF +.Fa fd +is not open for writing. +.It Bq Er EINVAL +.Fa start +is less than zero, or +.Fa start ++ +.Fa length +is less than +.Fa start +or triggers an integer overflow; or +.Fa how +contains an invalid value. +.El +.Sh NOTES +For optimal efficiency, the +.Fn fsync_range +call requires that the file system containing the file referenced by +.Fa fd +support partial synchronization of file data. +For file systems which do +not support partial synchronization, the entire file will be synchronized +and the call will be the equivalent of calling +.Fn fsync . +.Sh SEE ALSO +.Xr fdatasync 2 , +.Xr sync 2 , +.Xr sync 8 +.Sh HISTORY +The +.Fn fsync +function call appeared in +.Bx 4.2 . +.Pp +The +.Fn fsync_range +function call first appeared in +.Nx 2.0 +and is modeled after the function available in AIX. |