1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
|
.TH XLOSETUP 8 "September 2020" "util-linux" "System Administration"
.SH NAME
xlosetup \- set up and control xloop devices
.SH SYNOPSIS
.ad l
Get info:
.sp
.in +5
.B xlosetup
[\fIxloopdev\fP]
.sp
.B xlosetup \-l
.RB [ \-a ]
.sp
.B xlosetup \-j
.I file
.RB [ \-o
.IR offset ]
.sp
.in -5
Detach a xloop device:
.sp
.in +5
.B "xlosetup \-d"
.IR xloopdev ...
.sp
.in -5
Detach all associated xloop devices:
.sp
.in +5
.B "xlosetup \-D"
.sp
.in -5
Set up a xloop device:
.sp
.in +5
.B xlosetup
.RB [ \-o
.IR offset ]
.RB [ \-\-sizelimit
.IR size ]
.RB [ \-\-sector\-size
.IR size ]
.in +8
.RB [ \-Pr ]
.RB [ \-\-show ] " \-f" | \fIxloopdev\fP
.I file
.sp
.in -13
Resize a xloop device:
.sp
.in +5
.B "xlosetup \-c"
.I xloopdev
.in -5
.ad b
.SH DESCRIPTION
.B xlosetup
is used to associate xloop devices with regular files or block devices,
to detach xloop devices, and to query the status of a xloop device. If only the
\fIxloopdev\fP argument is given, the status of the corresponding xloop
device is shown. If no option is given, all xloop devices are shown.
.sp
Note that the old output format (i.e., \fBxlosetup \-a\fR) with comma-delimited
strings is deprecated in favour of the \fB\-\-list\fR output format.
.sp
It's possible to create more independent xloop devices for the same backing
file.
.B This setup may be dangerous, can cause data loss, corruption and overwrites.
Use \fB\-\-nooverlap\fR with \fB\-\-find\fR during setup to avoid this problem.
.SH OPTIONS
The \fIsize\fR and \fIoffset\fR
arguments may be followed by the multiplicative suffixes KiB (=1024),
MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is
optional, e.g., "K" has the same meaning as "KiB") or the suffixes
KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB.
.TP
.BR \-a , " \-\-all"
Show the status of all xloop devices. Note that not all information is accessible
for non-root users. See also \fB\-\-list\fR. The old output format (as printed
without \fB\-\-list)\fR is deprecated.
.TP
.BR \-d , " \-\-detach " \fIxloopdev\fR...
Detach the file or device associated with the specified xloop device(s). Note
that since Linux v3.7 kernel uses "lazy device destruction". The detach
operation does not return EBUSY error anymore if device is actively used by
system, but it is marked by autoclear flag and destroyed later.
.TP
.BR \-D , " \-\-detach\-all"
Detach all associated xloop devices.
.TP
.BR \-f , " \-\-find " "\fR[\fIfile\fR]"
Find the first unused xloop device. If a \fIfile\fR argument is present, use
the found device as xloop device. Otherwise, just print its name.
.IP "\fB\-\-show\fP"
Display the name of the assigned xloop device if the \fB\-f\fP option and a
\fIfile\fP argument are present.
.TP
.BR \-L , " \-\-nooverlap"
Check for conflicts between xloop devices to avoid situation when the same
backing file is shared between more xloop devices. If the file is already used
by another device then re-use the device rather than a new one. The option
makes sense only with \fB\-\-find\fP.
.TP
.BR \-j , " \-\-associated " \fIfile\fR " \fR[\fB\-o \fIoffset\fR]"
Show the status of all xloop devices associated with the given \fIfile\fR.
.TP
.BR \-o , " \-\-offset " \fIoffset
The data start is moved \fIoffset\fP bytes into the specified file or device. The \fIoffset\fP
may be followed by the multiplicative suffixes; see above.
.IP "\fB\-\-sizelimit \fIsize\fP"
The data end is set to no more than \fIsize\fP bytes after the data start. The \fIsize\fP
may be followed by the multiplicative suffixes; see above.
.TP
.BR \-b , " \-\-sector-size " \fIsize
Set the logical sector size of the xloop device in bytes (since Linux 4.14). The
option may be used when create a new xloop device as well as stand-alone command
to modify sector size of the already existing xloop device.
.TP
.BR \-c , " \-\-set\-capacity " \fIxloopdev
Force the xloop driver to reread the size of the file associated with the
specified xloop device.
.TP
.BR \-P , " \-\-partscan"
Force the kernel to scan the partition table on a newly created xloop device. Note that the
partition table parsing depends on sector sizes. The default is sector size is 512 bytes,
otherwise you need to use the option \fB\-\-sector\-size\fR together with \fB\-\-partscan\fR.
.TP
.BR \-r , " \-\-read\-only"
Set up a read-only xloop device.
.TP
.BR \-\-direct\-io [ =on | off ]
Enable or disable direct I/O for the backing file. The optional argument
can be either \fBon\fR or \fBoff\fR. If the argument is omitted, it defaults
to \fBoff\fR.
.TP
.BR \-t , " \-\-type \fIformat\fR"
Set the file format type of the xloop device. If no file format type is specified,
the RAW file format is used by default. Valid file formats are: \fBRAW\fR,
\fBQCOW\fR, \fBVDI\fR, \fBVMDK\fR.
.TP
.BR \-v , " \-\-verbose"
Verbose mode.
.TP
.BR \-l , " \-\-list"
If a xloop device or the \fB\-a\fR option is specified, print the default columns
for either the specified xloop device or all xloop devices; the default is to
print info about all devices. See also \fB\-\-output\fP, \fB\-\-noheadings\fP,
\fB\-\-raw\fP, and \fB\-\-json\fP.
.TP
.BR \-O , " \-\-output " \fIcolumn\fR[,\fIcolumn\fR]...
Specify the columns that are to be printed for the \fB\-\-list\fP output.
Use \fB\-\-help\fR to get a list of all supported columns.
.TP
.B \-\-output\-all
Output all available columns.
.TP
.BR \-n , " \-\-noheadings"
Don't print headings for \fB\-\-list\fP output format.
.IP "\fB\-\-raw\fP"
Use the raw \fB\-\-list\fP output format.
.TP
.BR \-J , " \-\-json"
Use JSON format for \fB\-\-list\fP output.
.TP
.BR \-V , " \-\-version"
Display version information and exit.
.TP
.BR \-h , " \-\-help"
Display help text and exit.
.SH ENCRYPTION
.B Cryptoloop is no longer supported in favor of dm-crypt.
.B For more details see cryptsetup(8).
.SH EXIT STATUS
.B xlosetup
returns 0 on success, nonzero on failure. When
.B xlosetup
displays the status of a xloop device, it returns 1 if the device
is not configured and 2 if an error occurred which prevented
determining the status of the device.
.SH ENVIRONMENT
.IP XLOOPDEV_DEBUG=all
enables debug output.
.SH FILES
.TP
.I /dev/xloop[0..N]
xloop block devices
.TP
.I /dev/xloop-control
xloop control device
.SH EXAMPLE
The following commands can be used as an example of using the xloop device.
.nf
.IP
# dd if=/dev/zero of=~/file.img bs=1024k count=10
# xlosetup \-\-find \-\-show ~/file.img
/dev/xloop0
# mkfs \-t ext2 /dev/xloop0
# mount /dev/xloop0 /mnt
...
# umount /dev/xloop0
# xlosetup \-\-detach /dev/xloop0
.fi
.SH AUTHORS
Karel Zak <kzak@redhat.com>, based on the original version from
Theodore Ts'o <tytso@athena.mit.edu>
.SH AVAILABILITY
The xlosetup command is part of the util-linux package and is available from
https://www.kernel.org/pub/linux/utils/util-linux/.
|
