LOCKFS(8) Maintenance Commands and Procedures LOCKFS(8)

NAME

lockfs - change or report file system locks

SYNOPSIS

/usr/sbin/lockfs [-adefhnuw] [-c string] [file-system]...

DESCRIPTION

lockfs is used to change and report the status of file system locks.
lockfs reports the lock status and unlocks the file systems that were
improperly left locked.


Using lockfs to lock a file system is discouraged because this
requires extensive knowledge of SunOS internals to be used
effectively and correctly.


When invoked with no arguments, lockfs lists the UFS file systems
that are locked. If file-system is not specified, and -a is
specified, lockfs is run on all mounted, UFS type file systems.

OPTIONS

The options are mutually exclusive: wndheuf. If you do specify more
than one of these options on a lockfs command line, the utility does
not protest and invokes only the last option specified. In
particular, you cannot specify a flush (-f) and a lock (for example,
-w) on the same command line. However, all locking operations
implicitly perform a flush, so the -f is superfluous when specifying
a lock.


You must be super-user to use any of the following options, with the
exception of -a, -f and -v.


The following options are supported.

-a

Apply command to all mounted, UFS type file systems. file-system
is ignored when -a is specified.


-c string

Accept a string that is passed as the comment field. The -c only
takes affect when the lock is being set using the -d, -h, -n, -u,
or -w options.


-d

Delete-lock (dlock) the specified file-system. dlock suspends
access that could remove directory entries.


-e

Error-lock (elock) the specified file-system. elock blocks all
local access to the locked file system and returns EWOULDBLOCK on
all remote access. File systems are elocked by UFS on detection
of internal inconsistency. They may only be unlocked after
successful repair by fsck, which is usually done automatically
(see mount_ufs(8)). elocked file systems can be unmounted.


-f

Force a synchronous flush of all data that is dirty at the time
fsflush is run to its backing store for the named file system (or
for all file systems.)

It is a more reliable method than using sync(8) because it does
not return until all possible data has been pushed. In the case
of UFS filesystems with logging enabled, the log is also rolled
before returning. Additional data can be modified by the time
fsflush exits, so using one of the locking options is more likely
to be of general use.


-h

Hard-lock (hlock) the specified file-system. hlock returns an
error on every access to the locked file system, and cannot be
unlocked. hlocked file systems can be unmounted.


-n

Name-lock (nlock) the specified file-system. nlock suspends
accesses that could change or remove existing directories
entries.


-u

Unlock (ulock) the specified file-system. ulock awakens suspended
accesses.


-v

Enable verbose output.


-w

Write-lock (wlock) the specified file-system. wlock suspends
writes that would modify the file system. Access times are not
kept while a file system is write-locked.

OPERANDS

The following operands are supported.

file-system

A list of path names separated by whitespace. Note that file-
system can be a directory rather than the specific name of a file
system, such as / or /usr. For example, if you specify
/export/home as an argument to a lockfs command and /export/home
is mounted on the root (/) file system, the lockfs command will
take effect on the root file system.

USAGE

See largefile(7) for the description of the behavior of lockfs when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES

Example 1: Using lockfs -a

In the following examples, filesystem is the pathname of the mounted-
on directory (mount point). Locktype is one of "write," "name,"
"delete," "hard," or "unlock". When enclosed in parenthesis, the lock
is being set. Comment is a string set by the process that last issued
a lock command.


The following example shows the lockfs output when only the -a option
is specified.


example# /usr/sbin/lockfs -a


Filesystem Locktype Comment
/ unlock
/var unlock


example#

Example 2: Using lockfs -w

The following example shows the lockfs output when the -w option is
used to write lock the /var file system and the comment string is set
using the -c option. The -a option is then specified on a separate
command line.


example# /usr/sbin/lockfs -w -c "lockfs: write lock example" /var
example# /usr/sbin/lockfs -a


Filesystem Locktype Comment
/ unlock
/var write lockfs: write lock example


example#

Example 3: Using lockfs -u

The following example shows the lockfs output when the -u option is
used to unlock the /var file system and the comment string is set
using the -c option.


example# /usr/sbin/lockfs -uc "lockfs: unlock example" /var
example# /usr/sbin/lockfs /var


Filesystem Locktype Comment
/var unlock lockfs: unlock example


example#

SEE ALSO

kill(1), mount_ufs(8), sync(8), attributes(7), largefile(7),
ufs(4FS),

DIAGNOSTICS

file system: Not owner

You must be root to use this command.


file system :Deadlock condition detected/avoided

A file is enabled for accounting or swapping, on file system.


file system: Device busy

Another process is setting the lock on file system.


January 2, 2008 LOCKFS(8)