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85 lines
3 KiB
Groff
85 lines
3 KiB
Groff
.\"-
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2019 The FreeBSD Foundation
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.\"
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.\" This documentation was written by BFF Storage Systems, LLC under
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.\" sponsorship from the FreeBSD Foundation.
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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 AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd June 19, 2019
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.Dt VOP_BMAP 9
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.Os
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.Sh NAME
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.Nm VOP_BMAP
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.Nd Logical to physical block number conversion
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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_BMAP "struct vnode *vp" "daddr_t bn" "struct bufobj **bop" "daddr_t *bnp" "int *runp" "int *runb"
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.Sh DESCRIPTION
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This vnode call is used to lookup the physical block number of the file system's
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underlying device where a given logical block of a file is stored.
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Its arguments are:
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.Bl -tag -width type
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.It Fa vp
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The vnode of the file.
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.It Fa bn
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Logical block number within the file identified by
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.Fa vp .
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.It Fa bop
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Return storage for the buffer object associated with the file system's
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underlying device.
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.It Fa bnp
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Return storage for the physical block number.
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.It Fa runp
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Return storage for the number of succeeding logical blocks that may be
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efficiently read at the same time as the requested block.
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This will usually be the number of logical blocks whose physical blocks are
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contiguously allocated.
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However a file system is free to define "efficient" as it sees fit.
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.It Fa runb
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Like
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.Fa runp
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but for preceding rather than succeeding blocks.
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.El
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.Pp
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Any of the return arguments may be
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.Dv NULL
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to indicate that the caller does not care about that information.
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.Sh LOCKS
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The vnode will be locked on entry and should remain locked on return.
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.Sh RETURN VALUES
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Zero is returned on success, otherwise an error code is returned.
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.Sh SEE ALSO
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.Xr vnode 9
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.Sh HISTORY
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A
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.Fn bmap
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function first appeared in
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.Bx 4.2 .
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.Sh AUTHORS
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This manual page was written by
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.An Alan Somers .
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