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Ocfs2/move_extents: helper to calculate the defraging length in one run.

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The helper is to calculate the defrag length in one run according to a threshold,
it will proceed doing defragmentation until the threshold was meet, and skip a
LARGE extent if any.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
This commit is contained in:
Tristan Ye 2011-03-18 14:35:40 +08:00
parent e08477176d
commit ee16cc037e
1 changed files with 30 additions and 0 deletions
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30
fs/ocfs2/move_extents.c
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@ -797,3 +797,33 @@ static int ocfs2_move_extent(struct ocfs2_move_extents_context *context,
return ret;
}
/*
* Helper to calculate the defraging length in one run according to threshold.
*/
static void ocfs2_calc_extent_defrag_len(u32 *alloc_size, u32 *len_defraged,
u32 threshold, int *skip)
{
if ((*alloc_size + *len_defraged) < threshold) {
/*
* proceed defragmentation until we meet the thresh
*/
*len_defraged += *alloc_size;
} else if (*len_defraged == 0) {
/*
* XXX: skip a large extent.
*/
*skip = 1;
} else {
/*
* split this extent to coalesce with former pieces as
* to reach the threshold.
*
* we're done here with one cycle of defragmentation
* in a size of 'thresh', resetting 'len_defraged'
* forces a new defragmentation.
*/
*alloc_size = threshold - *len_defraged;
*len_defraged = 0;
}
}