freebsd-dev/sbin/mount/mount.8
Pawel Jakub Dawidek 18713ab672 MFC r196456,r196457,r196458,r196662,r196702,r196703,r196919,r196927,r196928,
r196943,r196944,r196947,r196950,r196953,r196954,r196965,r196978,r196979,
r196980,r196982,r196985,r196992,r197131,r197133,r197150,r197151,r197152,
r197153,r197167,r197172,r197177,r197200,r197201:

r196456:
- Give minclsyspri and maxclsyspri real values (consulted with kmacy).
- Honour 'pri' argument for thread_create().

r196457:
Set priority of vdev_geom threads and zvol threads to PRIBIO.

r196458:
- Hide ZFS kernel threads under zfskern process.
- Use better (shorter) threads names:
	'zvol:worker zvol/tank/vol00' -> 'zvol tank/vol00'
	'vdev:worker da0' -> 'vdev da0'

r196662:
Add missing mountpoint vnode locking.
This fixes panic on assertion with DEBUG_VFS_LOCKS and vfs.usermount=1 when
regular user tries to mount dataset owned by him.

r196702:
Remove empty directory.

r196703:
Backport the 'dirtying dbuf' panic fix from newer ZFS version.

Reported by:	Thomas Backman <serenity@exscape.org>

r196919:
bzero() on-stack argument, so mutex_init() won't misinterpret that the
lock is already initialized if we have some garbage on the stack.

PR:	kern/135480
Reported by:	Emil Mikulic <emikulic@gmail.com>

r196927:
Changing provider size is not really supported by GEOM, but doing so when
provider is closed should be ok.
When administrator requests to change ZVOL size do it immediately if ZVOL
is closed or do it on last ZVOL close.

PR:	kern/136942
Requested by:	Bernard Buri <bsd@ask-us.at>

r196928:
Teach zdb(8) how to obtain GEOM provider size.

PR:	kern/133134
Reported by:	Philipp Wuensche <cryx-freebsd@h3q.com>

r196943:
- Avoid holding mutex around M_WAITOK allocations.
- Add locking for mnt_opt field.

r196944:
Don't recheck ownership on update mount. This will eliminate LOR between
vfs_busy() and mount mutex. We check ownership in vfs_domount() anyway.

Noticed by:	kib
Reviewed by:	kib

r196947:
Defer thread start until we set priority.

Reviewed by:	kib

r196950:
Fix detection of file system being shared. Now zfs unshare/destroy/rename
command will properly remove exported file systems.

r196953:
When snapshot mount point is busy (for example we are still in it)
we will fail to unmount it, but it won't be removed from the tree,
so in that case there is no need to reinsert it.

Reported by:	trasz

r196954:
If we have to use avl_find(), optimize a bit and use avl_insert() instead of
avl_add() (the latter is actually a wrapper around avl_find() + avl_insert()).
Fix similar case in the code that is currently commented out.

r196965:
Fix reference count leak for a case where snapshot's mount point is updated.

r196978:
Call ZFS_EXIT() after locking the vnode.

r196979:
On FreeBSD we don't have to look for snapshot's mount point,
because fhtovp method is already called with proper mount point.

r196980:
When we automatically mount snapshot we want to return vnode of the mount point
from the lookup and not covered vnode. This is one of the fixes for using .zfs/
over NFS.

r196982:
We don't export individual snapshots, so mnt_export field in snapshot's
mount point is NULL. That's why when we try to access snapshots over NFS
use mnt_export field from the parent file system.

r196985:
Only log successful commands! Without this fix we log even unsuccessful
commands executed by unprivileged users. Action is not really taken, but it is
logged to pool history, which might be confusing.

Reported by:	Denis Ahrens <denis@h3q.com>

r196992:
Implement __assert() for Solaris-specific code. Until now Solaris code was
using Solaris prototype for __assert(), but FreeBSD's implementation.
Both take different arguments, so we were either core-dumping in assert()
or printing garbage.

Reported by:	avg

r197131:
Tighten up the check for race in zfs_zget() - ZTOV(zp) can not only contain
NULL, but also can point to dead vnode, take that into account.

PR:	kern/132068
Reported by:	Edward Fisk <7ogcg7g02@sneakemail.com>, kris
Fix based on patch from:	Jaakko Heinonen <jh@saunalahti.fi>

r197133:
- Protect reclaim with z_teardown_inactive_lock.
- Be prepared for dbuf to disappear in zfs_reclaim_complete() and check if
  z_dbuf field is NULL - this might happen in case of rollback or forced
  unmount between zfs_freebsd_reclaim() and zfs_reclaim_complete().
- On forced unmount wait for all znodes to be destroyed - destruction can be
  done asynchronously via zfs_reclaim_complete().

r197150:
There is a bug where mze_insert() can trigger an assert() of inserting
the same entry twice. This bug is not fixed yet, but leads to situation
where when try to access corrupted directory the kernel will panic.
Until the bug is properly fixed, try to recover from it and log that it
happened.

Reported by:	marck
OpenSolaris bug:	6709336

r197151:
Be sure not to overflow struct fid.

r197152:
Extend scope of the z_teardown_lock lock for consistency and "just in case".

r197153:
When zfs.ko is compiled with debug, make sure that znode and vnode point at
each other.

r197167:
Work-around READDIRPLUS problem with .zfs/ and .zfs/snapshot/ directories
by just returning EOPNOTSUPP. This will allow NFS server to fall back to
regular READDIR.
Note that converting inode number to snapshot's vnode is expensive operation.
Snapshots are stored in AVL tree, but based on their names, not inode numbers,
so to convert inode to snapshot vnode we have to interate over all snalshots.
This is not a problem in OpenSolaris, because in their READDIRPLUS
implementation they use VOP_LOOKUP() on d_name, instead of VFS_VGET() on
d_fileno as we do.

PR:	kern/125149
Reported by:	Weldon Godfrey <wgodfrey@ena.com>
Analysis by:	Jaakko Heinonen <jh@saunalahti.fi>

r197172:
Add missing \n.

Reported by:	marck

r197177:
Support both case: when snapshot is already mounted and when it is not yet
mounted.

r197200:
Modify mount(8) to skip MNT_IGNORE file systems by default, just like df(1)
does. This is not POLA violation, because there is no single file system in the
base that use MNT_IGNORE currently, although ZFS snapshots will be mounted with
MNT_IGNORE after next commit.

Reviewed by:	kib

r197201:
- Mount ZFS snapshots with MNT_IGNORE flag, so they are not visible in regular
  df(1) and mount(8) output. This is a bit smilar to OpenSolaris and follows
  ZFS route of not listing snapshots by default with 'zfs list' command.
- Add UPDATING entry to note that ZFS snapshots are no longer visible in
  mount(8) and df(1) output by default.

Reviewed by:	kib

Approved by:	re (bz)
2009-09-15 11:13:40 +00:00

560 lines
15 KiB
Groff

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.\" @(#)mount.8 8.8 (Berkeley) 6/16/94
.\" $FreeBSD$
.\"
.Dd March 11, 2008
.Dt MOUNT 8
.Os
.Sh NAME
.Nm mount
.Nd mount file systems
.Sh SYNOPSIS
.Nm
.Op Fl adflpruvw
.Op Fl F Ar fstab
.Op Fl o Ar options
.Op Fl t Cm ufs | Ar external_type
.Nm
.Op Fl dfpruvw
.Ar special | node
.Nm
.Op Fl dfpruvw
.Op Fl o Ar options
.Op Fl t Cm ufs | Ar external_type
.Ar special node
.Sh DESCRIPTION
The
.Nm
utility calls the
.Xr nmount 2
system call to prepare and graft a
.Ar special
device or the remote node (rhost:path) on to the file system tree at the point
.Ar node .
If either
.Ar special
or
.Ar node
are not provided, the appropriate information is taken from the
.Xr fstab 5
file.
.Pp
The system maintains a list of currently mounted file systems.
If no arguments are given to
.Nm ,
this list is printed.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl a
All the file systems described in
.Xr fstab 5
are mounted.
Exceptions are those marked as
.Dq Li noauto ,
those marked as
.Dq Li late
(unless the
.Fl l
option was specified),
those excluded by the
.Fl t
flag (see below), or if they are already mounted (except the
root file system which is always remounted to preserve
traditional single user mode behavior).
.It Fl d
Causes everything to be done except for the actual system call.
This option is useful in conjunction with the
.Fl v
flag to
determine what the
.Nm
command is trying to do.
.It Fl F Ar fstab
Specify the
.Pa fstab
file to use.
.It Fl f
Forces the revocation of write access when trying to downgrade
a file system mount status from read-write to read-only.
Also
forces the R/W mount of an unclean file system (dangerous; use with
caution).
.It Fl l
When used in conjunction with the
.Fl a
option, also mount those file systems which are marked as
.Dq Li late .
.It Fl o
Options are specified with a
.Fl o
flag followed by a comma separated string of options.
In case of conflicting options being specified, the rightmost option
takes effect.
The following options are available:
.Bl -tag -width indent
.It Cm acls
Enable Access Control Lists, or ACLS, which can be customized via the
.Xr setfacl 1
and
.Xr getfacl 1
commands.
.It Cm async
All
.Tn I/O
to the file system should be done asynchronously.
This is a
.Em dangerous
flag to set, since it does not guarantee that the file system structure
on the disk will remain consistent.
For this reason, the
.Cm async
flag should be used sparingly, and only when some data recovery
mechanism is present.
.It Cm current
When used with the
.Fl u
flag, this is the same as specifying the options currently in effect for
the mounted file system.
.It Cm force
The same as
.Fl f ;
forces the revocation of write access when trying to downgrade
a file system mount status from read-write to read-only.
Also
forces the R/W mount of an unclean file system (dangerous; use with caution).
.It Cm fstab
When used with the
.Fl u
flag, this is the same as specifying all the options listed in the
.Xr fstab 5
file for the file system.
.It Cm late
This file system should be skipped when
.Nm
is run with the
.Fl a
flag but without the
.Fl l
flag.
.It Cm mountprog Ns = Ns Aq Ar program
Force
.Nm
to use the specified program to mount the file system, instead of calling
.Xr nmount 2
directly. For example:
.Bd -literal
mount -t foofs -o mountprog=/mydir/fooprog /dev/acd0 /mnt
.Ed
.It Cm multilabel
Enable multi-label Mandatory Access Control, or MAC, on the specified file
system.
If the file system supports multilabel operation, individual labels will
be maintained for each object in the file system, rather than using a
single label for all objects.
An alternative to the
.Fl l
flag in
.Xr tunefs 8 .
See
.Xr mac 4
for more information, which cause the multilabel mount flag to be set
automatically at mount-time.
.It Cm noasync
Metadata I/O should be done synchronously, while data I/O should be done
asynchronously.
This is the default.
.It Cm noatime
Do not update the file access time when reading from a file.
This option
is useful on file systems where there are large numbers of files and
performance is more critical than updating the file access time (which is
rarely ever important).
This option is currently only supported on local file systems.
.It Cm noauto
This file system should be skipped when
.Nm
is run with the
.Fl a
flag.
.It Cm noclusterr
Disable read clustering.
.It Cm noclusterw
Disable write clustering.
.It Cm noexec
Do not allow execution of any binaries on the mounted file system.
This option is useful for a server that has file systems containing
binaries for architectures other than its own.
Note: This option was not designed as a security feature and no
guarantee is made that it will prevent malicious code execution; for
example, it is still possible to execute scripts which reside on a
.Cm noexec
mounted partition.
.It Cm nosuid
Do not allow set-user-identifier or set-group-identifier bits to take effect.
Note: this option is worthless if a public available suid or sgid
wrapper like
.Xr suidperl 1
is installed on your system.
It is set automatically when the user does not have super-user privileges.
.It Cm nosymfollow
Do not follow symlinks
on the mounted file system.
.It Cm ro
The same as
.Fl r ;
mount the file system read-only (even the super-user may not write it).
.It Cm snapshot
This option allows a snapshot of the specified file system to be taken.
The
.Fl u
flag is required with this option.
Note that snapshot files must be created in the file system that is being
snapshotted.
You may create up to 20 snapshots per file system.
Active snapshots are recorded in the superblock, so they persist across unmount
and remount operations and across system reboots.
When you are done with a snapshot, it can be removed with the
.Xr rm 1
command.
Snapshots may be removed in any order, however you may not get back all the
space contained in the snapshot as another snapshot may claim some of the blocks
that it is releasing.
Note that the schg flag is set on snapshots to ensure that not even the root
user can write to them.
The unlink command makes an exception for snapshot files in that it allows them
to be removed even though they have the schg flag set, so it is not necessary to
clear the schg flag before removing a snapshot file.
.Pp
Once you have taken a snapshot, there are three interesting things that you can
do with it:
.Pp
.Bl -enum -compact
.It
Run
.Xr fsck 8
on the snapshot file.
Assuming that the file system was clean when it was mounted, you should always
get a clean (and unchanging) result from running fsck on the snapshot.
This is essentially what the background fsck process does.
.Pp
.It
Run
.Xr dump 8
on the snapshot.
You will get a dump that is consistent with the file system as of the timestamp
of the snapshot.
.Pp
.It
Mount the snapshot as a frozen image of the file system.
To mount the snapshot
.Pa /var/snapshot/snap1 :
.Bd -literal
mdconfig -a -t vnode -f /var/snapshot/snap1 -u 4
mount -r /dev/md4 /mnt
.Ed
.Pp
You can now cruise around your frozen
.Pa /var
file system at
.Pa /mnt .
Everything will be in the same state that it was at the time the snapshot was
taken.
The one exception is that any earlier snapshots will appear as zero length
files.
When you are done with the mounted snapshot:
.Bd -literal
umount /mnt
mdconfig -d -u 4
.Ed
.Pp
Further details can be found in the file at
.Pa /usr/src/sys/ufs/ffs/README.snapshot .
.El
.It Cm suiddir
A directory on the mounted file system will respond to the SUID bit
being set, by setting the owner of any new files to be the same
as the owner of the directory.
New directories will inherit the bit from their parents.
Execute bits are removed from
the file, and it will not be given to root.
.Pp
This feature is designed for use on fileservers serving PC users via
ftp, SAMBA, or netatalk.
It provides security holes for shell users and as
such should not be used on shell machines, especially on home directories.
This option requires the SUIDDIR
option in the kernel to work.
Only UFS file systems support this option.
See
.Xr chmod 2
for more information.
.It Cm sync
All
.Tn I/O
to the file system should be done synchronously.
.It Cm update
The same as
.Fl u ;
indicate that the status of an already mounted file system should be changed.
.It Cm union
Causes the namespace at the mount point to appear as the union
of the mounted file system root and the existing directory.
Lookups will be done in the mounted file system first.
If those operations fail due to a non-existent file the underlying
directory is then accessed.
All creates are done in the mounted file system.
.El
.Pp
Any additional options specific to a file system type that is not
one of the internally known types (see the
.Fl t
option) may be passed as a comma separated list; these options are
distinguished by a leading
.Dq \&-
(dash).
Options that take a value are specified using the syntax -option=value.
For example, the
.Nm
command:
.Bd -literal -offset indent
mount -t cd9660 -o -e /dev/cd0 /cdrom
.Ed
.Pp
causes
.Nm
to execute the equivalent of:
.Bd -literal -offset indent
/sbin/mount_cd9660 -e /dev/cd0 /cdrom
.Ed
.Pp
Additional options specific to file system types
which are not internally known
(see the description of the
.Fl t
option below)
may be described in the manual pages for the associated
.Pa /sbin/mount_ Ns Sy XXX
utilities.
.It Fl p
Print mount information in
.Xr fstab 5
format.
Implies also the
.Fl v
option.
.It Fl r
The file system is to be mounted read-only.
Mount the file system read-only (even the super-user may not write it).
The same as the
.Cm ro
argument to the
.Fl o
option.
.It Fl t Cm ufs | Ar external_type
The argument following the
.Fl t
is used to indicate the file system type.
The type
.Cm ufs
is the default.
The
.Fl t
option can be used
to indicate that the actions should only be taken on
file systems of the specified type.
More than one type may be specified in a comma separated list.
The list of file system types can be prefixed with
.Dq Li no
to specify the file system types for which action should
.Em not
be taken.
For example, the
.Nm
command:
.Bd -literal -offset indent
mount -a -t nonfs,nullfs
.Ed
.Pp
mounts all file systems except those of type
.Tn NFS
and
.Tn NULLFS .
.Pp
The default behavior of
.Nm
is to pass the
.Fl t
option directly to the
.Xr nmount 2
system call in the
.Li fstype
option.
.Pp
However, for the following file system types:
.Cm cd9660 ,
.Cm mfs ,
.Cm msdosfs ,
.Cm nfs ,
.Cm nfs4 ,
.Cm ntfs ,
.Cm nwfs ,
.Cm nullfs ,
.Cm portalfs ,
.Cm smbfs ,
.Cm udf ,
and
.Cm unionfs ,
.Nm
will not call
.Xr nmount 2
directly and will instead attempt to execute a program in
.Pa /sbin/mount_ Ns Sy XXX
where
.Sy XXX
is replaced by the file system type name.
For example, nfs file systems are mounted by the program
.Pa /sbin/mount_nfs .
.Pp
Most file systems will be dynamically loaded by the kernel
if not already present, and if the kernel module is available.
.It Fl u
The
.Fl u
flag indicates that the status of an already mounted file
system should be changed.
Any of the options discussed above (the
.Fl o
option)
may be changed;
also a file system can be changed from read-only to read-write
or vice versa.
An attempt to change from read-write to read-only will fail if any
files on the file system are currently open for writing unless the
.Fl f
flag is also specified.
The set of options is determined by applying the options specified
in the argument to
.Fl o
and finally applying the
.Fl r
or
.Fl w
option.
.It Fl v
Verbose mode.
If the
.Fl v
is used alone, show all file systems, including those that were mounted with the
.Dv MNT_IGNORE
flag and show additional information about each file system (including fsid
when run by root).
.It Fl w
The file system object is to be read and write.
.El
.Sh ENVIRONMENT
.Bl -tag -width ".Ev PATH_FSTAB"
.It Ev PATH_FSTAB
If the environment variable
.Ev PATH_FSTAB
is set, all operations are performed against the specified file.
.Ev PATH_FSTAB
will not be honored if the process environment or memory address space is
considered
.Dq tainted .
(See
.Xr issetugid 2
for more information.)
.El
.Sh FILES
.Bl -tag -width /etc/fstab -compact
.It Pa /etc/fstab
file system table
.El
.Sh DIAGNOSTICS
Various, most of them are self-explanatory.
.Pp
.Dl XXXXX file system is not available
.Pp
The kernel does not support the respective file system type.
Note that
support for a particular file system might be provided either on a static
(kernel compile-time), or dynamic basis (loaded as a kernel module by
.Xr kldload 8 ) .
.Sh SEE ALSO
.Xr getfacl 1 ,
.Xr setfacl 1 ,
.Xr nmount 2 ,
.Xr acl 3 ,
.Xr mac 4 ,
.Xr ext2fs 5 ,
.Xr fstab 5 ,
.Xr procfs 5 ,
.Xr kldload 8 ,
.Xr mount_cd9660 8 ,
.Xr mount_msdosfs 8 ,
.Xr mount_nfs 8 ,
.Xr mount_ntfs 8 ,
.Xr mount_nullfs 8 ,
.Xr mount_nwfs 8 ,
.Xr mount_portalfs 8 ,
.Xr mount_smbfs 8 ,
.Xr mount_udf 8 ,
.Xr mount_unionfs 8 ,
.Xr umount 8
.Sh CAVEATS
After a successful
.Nm ,
the permissions on the original mount point determine if
.Pa ..\&
is accessible from the mounted file system.
The minimum permissions for
the mount point for traversal across the mount point in both
directions to be possible for all users is 0111 (execute for all).
.Pp
Use of the
.Nm
is preferred over the use of the file system specific
.Pa mount_ Ns Sy XXX
commands.
In particular,
.Xr mountd 8
gets a
.Dv SIGHUP
signal (that causes an update of the export list)
only when the file system is mounted via
.Nm .
.Sh HISTORY
A
.Nm
utility appeared in
.At v1 .
.Sh BUGS
It is possible for a corrupted file system to cause a crash.