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Add a FUNCTIONS section.

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In addition, small improvements to wording and markup.
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jruoho 2010-04-12 21:28:55 +00:00
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share/man/man9/fstrans.9
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@ -1,4 +1,4 @@
.\" $NetBSD: fstrans.9,v 1.14 2009/06/24 22:39:40 zafer Exp $
.\" $NetBSD: fstrans.9,v 1.15 2010/04/12 21:28:55 jruoho Exp $
.\"
.\" Copyright (c) 2007 The NetBSD Foundation, Inc.
.\" All rights reserved.
@ -27,7 +27,7 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd December 2, 2007
.Dd April 13, 2010
.Dt FSTRANS 9
.Os
.Sh NAME
@ -77,68 +77,76 @@ in
.Dv "mnt_iflag" .
.Pp
File systems are always in one of these states:
.Pp
.Bl -tag -offset indent -width FSTRANS_SUSPENDING -compact
.It Dv FSTRANS_NORMAL
normal operations.
Normal operations.
.It Dv FSTRANS_SUSPENDING
preparing a suspension.
Preparing a suspension.
.It Dv FSTRANS_SUSPENDED
suspended.
Suspended.
.El
.Pp
This state is represented by
.Vt "enum fstrans_state" .
.Bl -tag -width compact
.It Fn fstrans_getstate "mp"
returns the current state of the file system
.Fa mp .
.Pp
.It Fn fstrans_setstate "mp" "new_state"
changes the state of the file system
.Fa mp
to
.Fa new_state .
.El
.Pp
All file system operations use a
.Em "fstrans lock" .
This lock is recursive.
A thread already owning a lock will always get another lock.
The lock has two variants:
.Bl -tag -offset indent -width FSTRANS_SHARED -compact
.Bl -tag -offset indent -width FSTRANS_SHARED
.It Dv FSTRANS_SHARED
this lock will be granted if the file system is in state
A lock that will be granted if the file system is in state
.Dv FSTRANS_NORMAL .
.It Dv FSTRANS_LAZY
this lock will be granted if the file system is in state
A lock that will be granted if the file system is in state
.Dv FSTRANS_NORMAL
or
.Dv FSTRANS_SUSPENDING .
It needs special care because operations using this variant will not block
while the file system prepares suspension.
.El
.Pp
The lock variant is represented by
.Vt "enum fstrans_lock_type" .
.Sh FUNCTIONS
The following functions comprise the
.Tn API
provided by
.Nm .
.Bl -tag -width compact
.It Fn fstrans_getstate "mp"
Returns the current state of the file system
.Fa mp .
.It Fn fstrans_setstate "mp" "new_state"
Changes the state of the file system
.Fa mp
to
.Fa new_state .
.It Fn fstrans_start "mp" "lock_type"
sets a lock of type
Sets a lock of type
.Fa lock_type
on the file system
.Fa mp .
.It Fn fstrans_start_nowait "mp" "lock_type"
will not wait for a state change of the file system when attempting to
Like
.Fn fstrans_start ,
but will not wait for a state change of the file system when attempting to
acquire the lock.
The thread may still sleep while attempting to acquire the lock.
.It Fn fstrans_done "mp"
releases a lock on the file system
Releases a lock on the file system
.Fa mp .
.It Fn fstrans_is_owner "mp"
returns
Returns
.Dv true
if this thread is currently suspending the file system
.Fa mp .
.It Fn fscow_establish "mp" "func" "cookie"
Establish a copy-on-write callback for the file system
.Fa mp .
The function
.Fa func
will be called for every buffer written through this file system.
.It Fn fscow_disestablish "mp" "func" "cookie"