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.TH "ALLOC_NEW_RESERVATION" "9" "09 October 2005" "" ""

.SH NAME
alloc_new_reservation \- -allocate a new reservation window
.SH SYNOPSIS
"SYNOPSIS"
.sp
\fB
.sp
int alloc_new_reservation  (struct ext3_reserve_window_node * \fImy_rsv\fB, int \fIgoal\fB, struct super_block * \fIsb\fB, unsigned int \fIgroup\fB, struct buffer_head * \fIbitmap_bh\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fImy_rsv\fB\fR
-- undescribed --
.TP
\fB\fIgoal\fB\fR
The goal (group-relative).  It is where the search for a
free reservable space should start from.
if we have a goal(goal >0 ), then start from there,
no goal(goal = -1), we start from the first block
of the group.
.TP
\fB\fIsb\fB\fR
the super block
.TP
\fB\fIgroup\fB\fR
the group we are trying to allocate in
.TP
\fB\fIbitmap_bh\fB\fR
the block group block bitmap
.SH "DESCRIPTION"
.PP
.PP
To make a new reservation, we search part of the filesystem
reservation list (the list that inside the group). We try to
allocate a new reservation window near the allocation goal,
or the beginning of the group, if there is no goal.
.PP
We first find a reservable space after the goal, then from
there, we check the bitmap for the first free block after
it. If there is no free block until the end of group, then the
whole group is full, we failed. Otherwise, check if the free
block is inside the expected reservable space, if so, we
succeed.
If the first free block is outside the reservable space, then
start from the first free block, we search for next available
space, and go on.
.PP
on succeed, a new reservation will be found and inserted into the list
It contains at least one free block, and it does not overlap with other
reservation windows.
.SH "FAILED"
.PP
we failed to find a reservation window in this group