253 lines
6.9 KiB
Groff
253 lines
6.9 KiB
Groff
.\" Copyright (c) 2001 Networks Associates Technology, Inc.
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.\" All rights reserved.
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.\"
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.\" This software was developed for the FreeBSD Project by Chris
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.\" Costello at Safeport Network Services and NAI Labs, the Security
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.\" Research Division of Network Associates, Inc. under DARPA/SPAWAR
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.\" contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
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.\" research program.
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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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.\" 3. The names of the authors may not be used to endorse or promote
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.\" products derived from this software without specific prior written
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.\" permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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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.\" $FreeBSD$
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.\"
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.Dd December 26, 2001
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.Dt FFS 7
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.Sh NAME
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.Nm ffs
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.Nd Berkeley fast filesystem
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.Sh SYNOPSIS
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In the kernel configuration file:
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.Cd "options ENABLE_VFS_IOOPT"
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.Cd "options FFS"
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.Cd "options QUOTA"
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.Cd "options SOFTUPDATES"
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.Cd "options SUIDDIR"
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.Cd "options UFS_ACL"
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.Cd "options UFS_DIRHASH"
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.Cd "options UFS_EXTATTR"
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.Cd "options UFS_EXTATTR_AUTOSTART"
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.Pp
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In
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.Xr fstab 5 :
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.Bd -literal -compact
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/dev/disk0a /mnt ufs rw 1 1
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.Ed
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.Sh DESCRIPTION
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The Berkeley fast filesystem
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provides facilities to store filesystem data onto a disk device.
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.Nm
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has been optimized over the years
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for speed and reliability
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and is the default
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.Fx
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filesystem.
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.Ss VFS I/O optimization
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.Bl -tag -width 2n
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.It Cd "options ENABLE_VFS_IOOPT"
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This option enables the I/O optimization through the VM system,
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using VM operations instead of copying operations when possible.
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This option adds a
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.Xr sysctl 8
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MIB,
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.Va vfs.ioopt .
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The following are values and effects for
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.Va vfs.ioopt :
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.Pp
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.Bl -tag -width ".Em Value" -offset indent -compact
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.It Em Value
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.Em Effect
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.It Li 0
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No optimization
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.It Li 1
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VM operations if a request fits
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.It Li 2
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Aggressive optimization (VM used as much as possible)
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.El
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.El
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.Ss Quotas
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.Bl -tag -width 2n
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.It Cd "options QUOTA"
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This option allows system administrators
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to set limits on disk usage
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on a per-user basis.
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Quotas can be used only on filesystems
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mounted with the
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.Cm quota
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option;
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see
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.Xr quota 1
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and
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.Xr edquota 8 .
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.El
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.Ss Soft Updates
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.Bl -tag -width 2n
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.It Cd "options SOFTUPDATES"
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The soft updates feature tracks writes to the disk
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and enforces metadata update dependencies
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(e.g., updating free block maps)
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to ensure that the filesystem remains consistent.
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.Pp
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To enable soft updates on an
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.Em unmounted
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filesystem, use the following command:
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.Pp
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.D1 Nm tunefs Fl n Cm enable Ar fs
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.Pp
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.Ar fs
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can be either a mount point listed in
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.Xr fstab 5
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(e.g.,
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.Pa /usr ) ,
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or a disk device
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(e.g.,
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.Pa /dev/da0a ) .
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.El
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.Ss File Ownership Inheritance
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.Bl -tag -width 2n
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.It Cd "options SUIDDIR"
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For use in file sharing environments
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on networks including
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.Tn "Microsoft Windows"
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and
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.Tn "Apple Macintosh"
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computers,
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this option allows files on filesystems
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mounted with the
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.Cm suiddir
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option
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to inherit the ownership of its directory,
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i.e.,
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.Dq "if it's my directory, it must be my file."
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.El
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.Ss Access Control Lists
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.Bl -tag -width 2n
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.It Cd "options UFS_ACL"
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Access control lists allow the association of
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fine-grained discretionary access control information
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with files and directories.
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This option requires the presence of the
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.Dv UFS_EXTATTR
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option, and it is recommended that
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.Dv UFS_EXTATTR_AUTOSTART
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is included as well,
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so that ACLs are enabled atomically upon mounting the filesystem.
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.El
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.Pp
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In order to enable support for ACLs,
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two extended attributes must be available in the
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.Dv EXTATTR_NAMESPACE_SYSTEM
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namespace:
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.Pa posix1e.acl_access ,
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which holds the access ACL,
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and
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.Pa posix1e.acl_default ,
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which holds the default ACL for directories.
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If you are using filesystem extended attributes,
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the following commands may be used to
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allocate space for and create the necessary EA backing files
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for ACLs in the root of each filesystem.
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In these examples, the root filesystem is used;
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see
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.Sx "Extended Attributes"
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for more details.
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.Bd -literal -offset indent
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mkdir -p /.attribute/system
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cd /.attribute/system
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extattrctl initattr -p / 388 posix1e.acl_access
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extattrctl initattr -p / 388 posix1e.acl_default
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.Ed
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.Pp
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On the next mount of the root filesystem,
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the attributes will be automatically started
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(if
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.Dv UFS_EXTATTR_AUTOSTART
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is included in the kernel configuration),
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and ACLs will be enabled.
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.Ss Directory Hashing
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.Bl -tag -width 2n
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.It Cd "options UFS_DIRHASH"
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Implements a hash-based lookup scheme for directories
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in order to speed up accesses to very large directories.
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.El
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.Ss Extended Attributes
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.Bl -tag -width 2n
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.It Cd "options UFS_EXTATTR"
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Extended attributes allow the association of
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additional arbitrary metadata with files and directories,
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which can be assigned and retrieved from userland
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as well as from within the kernel; see
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.Xr extattrctl 8 .
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.It Cd "options UFS_EXTATTR_AUTOSTART"
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If this option is defined,
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.Nm
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will search for a
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.Pa .attribute
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subdirectory of the filesystem root during the mount operation.
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If found, extended attribute support will be
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automatically started for that filesystem.
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.El
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.Pp
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The following
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.Xr sysctl 8
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MIBs are defined for use with
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.Nm :
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.Bl -hang -width ".Va vfs.ffs.doreallocblk"
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.It Va vfs.ffs.doasyncfree
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Asynchronously write out modified i-node and indirect blocks
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upon reallocating filesystem blocks to be contiguous.
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(Default: 1.)
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.It Va vfs.ffs.doreallocblks
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Enable support for the rearrangement of blocks
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to be contiguous.
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(Default: 1.)
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.El
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.Sh SEE ALSO
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.Xr quota 1 ,
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.Xr acl 3 ,
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.Xr extattr 3 ,
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.Xr edquota 8 ,
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.Xr extattrctl 8 ,
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.Xr sysctl 8
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.Rs
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.%A M. McKusick
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.%A W. Joy
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.%A S. Lefler
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.%A R. Fabry
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.%D August 1984
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.%T "A Fast File System for UNIX"
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.%J "ACM Transactions on Computer Systems"
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.%N 2
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.%V 3
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.%P 181-197
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.Re
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.Rs
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.%A M. McKusick
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.%D June 2000
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.%T "Soft Updates: A Technique for Eliminating Most Synchronous Writes in the Fast Filesystem"
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.%J "Proceedings of the Freenix Track at the 1999 Usenix Annual Technical Conference"
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.%P 71-84
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.Re
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