xref: /freebsd/sbin/mdmfs/mdmfs.8 (revision 96190b4fef3b4a0cc3ca0606b0c4e3e69a5e6717)
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26.Dd October 31, 2019
27.Dt MDMFS 8
28.Os
29.Sh NAME
30.Nm mdmfs ,
31.Nm mount_mfs
32.Nd configure and mount an in-memory file system using the
33.Xr md 4
34driver or the
35.Xr tmpfs 4
36filesystem
37.Sh SYNOPSIS
38.Nm
39.Op Fl DLlMNnPStTUX
40.Op Fl a Ar maxcontig
41.Op Fl b Ar block-size
42.Op Fl c Ar blocks-per-cylinder-group
43.Op Fl d Ar max-extent-size
44.Op Fl E Ar path-mdconfig
45.Op Fl e Ar maxbpg
46.Op Fl F Ar file
47.Op Fl f Ar frag-size
48.Op Fl i Ar bytes
49.Op Fl k Ar skel
50.Op Fl m Ar percent-free
51.Op Fl O Ar optimization
52.Op Fl o Ar mount-options
53.Op Fl p Ar permissions
54.Op Fl s Ar size
55.Op Fl T Ar fstype
56.Op Fl v Ar version
57.Op Fl w Ar user : Ns Ar group
58.Ar md-device
59.Ar mount-point
60.Sh DESCRIPTION
61The
62.Nm
63utility is designed to be a work-alike and look-alike of the deprecated
64.Nm mount_mfs .
65The end result is essentially the same,
66but is accomplished in a completely different way.
67Based on
68.Ar md-device ,
69the
70.Nm
71utility either creates a
72.Xr tmpfs 4
73filesystem, or it configures an
74.Xr md 4
75disk using
76.Xr mdconfig 8 ,
77puts a UFS file system on it (unless
78.Fl P
79was specified) using
80.Xr newfs 8 ,
81and mounts it using
82.Xr mount 8 .
83It can handle
84.Xr geom_uzip 4
85compressed disk images, as long as the kernel supports this GEOM class.
86All the command line options are passed to the appropriate program
87at the appropriate stage in order to achieve the desired effect.
88.Pp
89When
90.Ar md-device
91is `auto',
92.Nm
93uses
94.Xr tmpfs 4
95if it is present in the kernel or can be loaded as a module,
96otherwise it falls back to using
97.Xr md 4
98auto-unit as if `md' had been specified.
99.Pp
100When
101.Ar md-device
102is `tmpfs',
103.Nm
104mounts a
105.Xr tmpfs 4
106filesystem, translating the
107.Fl s
108size option, if present, into a `-o size=' mount option.
109Any
110.Fl o
111options on the command line are passed through to the
112.Xr tmpfs 4
113mount.
114Options specific to
115.Xr mdconfig 8
116or
117.Xr newfs 8
118are ignored.
119.Pp
120When
121.Ar md-device
122does not result in
123.Xr tmpfs 4
124being used, then an
125.Xr md 4
126device is configured instead.
127By default,
128.Nm
129creates a swap-based
130.Pq Dv MD_SWAP
131disk with soft-updates enabled
132and mounts it on
133.Ar mount-point .
134It uses the
135.Xr md 4
136device specified by
137.Ar md-device .
138If
139.Ar md-device
140is
141.Ql md
142(no unit number),
143it will use
144.Xr md 4 Ns 's
145auto-unit feature to automatically select an unused device.
146Unless otherwise specified with one of the options below,
147it uses the default arguments to all the helper programs.
148.Pp
149The following options are available.
150Where possible,
151the option letter matches the one used by
152.Nm mount_mfs
153for the same thing.
154.Bl -tag -width indent
155.It Fl a Ar maxcontig
156Specify the maximum number of contiguous blocks that will be laid
157out before forcing a rotational delay
158(see the
159.Fl d
160option).
161.It Fl b Ar block-size
162The block size of the file system, in bytes.
163.It Fl c Ar blocks-per-cylinder-group
164The number of blocks per cylinder group in the file system.
165.It Fl D
166If not using auto-unit,
167do not run
168.Xr mdconfig 8
169to try to detach the unit before attaching it.
170.It Fl d Ar max-extent-size
171The file system may choose to store large files using extents.
172This parameter specifies the largest extent size that may be
173used.
174It is presently limited to its default value which is 16
175times the file system blocksize.
176.It Fl E Ar path-mdconfig
177Use
178.Ar path-mdconfig
179as a location of the
180.Xr mdconfig 8
181utility.
182.It Fl e Ar maxbpg
183Indicate the maximum number of blocks any single file can allocate
184out of a cylinder group before it is forced to begin allocating
185blocks from another cylinder group.
186.It Fl F Ar file
187Create a vnode-backed
188.Pq Dv MD_VNODE
189memory disk backed by
190.Ar file .
191.It Fl f Ar frag-size
192The fragment size of the file system in bytes.
193.It Fl i Ar bytes
194Number of bytes per inode.
195.It Fl k Ar skel
196Copy the content of directory
197.Ar skel
198into
199.Ar mount-point .
200.It Fl l
201Enable multilabel MAC on the new file system.
202.It Fl L
203Show the output of the helper programs.
204By default,
205it is sent to
206.Pa /dev/null .
207.It Fl M
208Create a
209.Xr malloc 9
210backed disk
211.Pq Dv MD_MALLOC
212instead of a swap-backed disk.
213.It Fl m Ar percent-free
214The percentage of space reserved for the superuser.
215.It Fl N
216Do not actually run the helper programs.
217This is most useful in conjunction with
218.Fl X .
219.It Fl n
220Do not create a
221.Pa .snap
222directory on the new file system.
223.It Fl O Ar optimization
224Select the optimization preference;
225valid choices are
226.Cm space
227and
228.Cm time ,
229which will optimize for minimum space fragmentation and
230minimum time spent allocating blocks,
231respectively.
232.It Fl o Ar mount-options
233Specify the mount options with which to mount the file system.
234See
235.Xr mount 8
236for more information.
237.It Fl P
238Preserve the existing file system;
239do not run
240.Xr newfs 8 .
241This only makes sense if
242.Fl F
243is specified to create a vnode-backed disk.
244.It Fl p Ar permissions
245Set the file (directory) permissions of the mount point
246.Ar mount-point
247to
248.Ar permissions .
249The
250.Ar permissions
251argument can be in any of the mode formats recognized by
252.Xr chmod 1 .
253If symbolic permissions are specified,
254the operation characters
255.Dq +
256and
257.Dq -
258are interpreted relative to the initial permissions of
259.Dq a=rwx .
260.It Fl S
261Do not enable soft-updates on the file system.
262.It Fl s Ar size
263Specify the size of the disk to create.
264This only makes sense if
265.Fl F
266is
267.Em not
268specified.
269That is,
270this will work when the backing storage is some form of
271memory, as opposed to a fixed-size file.
272The size may include the usual SI suffixes (k, m, g, t, p).
273A number without a suffix is interpreted as a count of 512-byte sectors.
274.It Fl t
275Turn on the TRIM enable flag for
276.Xr newfs 8 .
277When used with a file system that issue BIO_DELETE bio requests,
278.Xr md 4
279returns deleted blocks to the system memory pool.
280.It Fl T Ar fstype
281Specify a file system type for a vnode-backed memory disk.
282Any file system supported by
283.Xr mount 8
284command can be specified.
285This option only makes sense when
286.Fl F
287and
288.Fl P
289are used.
290.It Fl U
291Enable soft-updates on the file system.
292This is the default, and is accepted only
293for compatibility.
294It is only really useful to negate the
295.Fl S
296flag, should such a need occur.
297.It Fl v Ar version
298Specify the UFS version number for use on the file system; it may be
299either
300.Dv 1
301or
302.Dv 2 .
303The default is derived from the default of the
304.Xr newfs 8
305command.
306.It Fl w Ar user : Ns Ar group
307Set the owner and group to
308.Ar user
309and
310.Ar group ,
311respectively.
312The arguments have the same semantics as with
313.Xr chown 8 ,
314but specifying just a
315.Ar user
316or just a
317.Ar group
318is not supported.
319.It Fl X
320Print what command will be run before running it, and
321other assorted debugging information.
322.El
323.Pp
324The
325.Fl F
326and
327.Fl s
328options are passed to
329.Xr mdconfig 8
330as
331.Fl f
332and
333.Fl s ,
334respectively.
335The
336.Fl a , b , c , d , e , f , i , m
337and
338.Fl n
339options are passed to
340.Xr newfs 8
341with the same letter.
342The
343.Fl O
344option is passed to
345.Xr newfs 8
346as
347.Fl o .
348The
349.Fl o
350option is passed to
351.Xr mount 8
352with the same letter.
353The
354.Fl T
355option is passed to
356.Xr mount 8
357as
358.Fl t .
359For information on semantics, refer to the documentation of the programs
360that the options are passed to.
361.Sh EXAMPLES
362Create and mount a 32 megabyte swap-backed file system on
363.Pa /tmp :
364.Pp
365.Dl "mdmfs -s 32m md /tmp"
366.Pp
367The same file system created as an entry in
368.Pa /etc/fstab :
369.Pp
370.Dl "md /tmp mfs rw,-s32m 2 0"
371.Pp
372Create and mount a 16 megabyte malloc-backed file system on
373.Pa /tmp
374using the
375.Pa /dev/md1
376device;
377furthermore,
378do not use soft-updates on it and mount it
379.Cm async :
380.Pp
381.Dl "mdmfs -M -S -o async -s 16m md1 /tmp"
382.Pp
383Create and mount a
384.Xr geom_uzip 4
385based compressed disk image:
386.Pp
387.Dl "mdmfs -P -F foo.uzip -oro md.uzip /tmp/"
388.Pp
389Mount the same image, specifying the
390.Pa /dev/md1
391device:
392.Pp
393.Dl "mdmfs -P -F foo.uzip -oro md1.uzip /tmp/"
394.Pp
395Configure a vnode-backed file system and mount its first partition,
396using automatic device numbering:
397.Pp
398.Dl "mdmfs -P -F foo.img mds1a /tmp/"
399.Pp
400Mount a vnode-backed cd9660 file system using automatic device numbering:
401.Pp
402.Dl "mdmfs -T cd9660 -P -F foo.iso md /tmp"
403.Sh COMPATIBILITY
404The
405.Nm
406utility, while designed to be compatible with
407.Nm mount_mfs ,
408can be useful by itself.
409Since
410.Nm mount_mfs
411had some silly defaults, a
412.Dq compatibility
413mode is provided for the case where bug-to-bug compatibility is desired.
414.Pp
415Compatibility is enabled by starting
416.Nm
417with the name
418.Li mount_mfs
419or
420.Li mfs
421(as returned by
422.Xr getprogname 3 ) .
423In this mode, the following behavior, as done by
424.Nm mount_mfs ,
425is duplicated:
426.Bl -bullet -offset indent
427.It
428The file mode of
429.Ar mount-point
430is set by default to
431.Li 01777
432as if
433.Fl p Ar 1777
434was given on the command line.
435.El
436.Sh SEE ALSO
437.Xr md 4 ,
438.Xr tmpfs 4 ,
439.Xr fstab 5 ,
440.Xr mdconfig 8 ,
441.Xr mount 8 ,
442.Xr newfs 8
443.Sh HISTORY
444The
445.Nm
446utility appeared in
447.Fx 5.0 .
448.Sh AUTHORS
449.An Dima Dorfman
450