From ee16cc037e255801892481a2d0b7c1fff2adf1aa Mon Sep 17 00:00:00 2001 From: Tristan Ye Date: Fri, 18 Mar 2011 14:35:40 +0800 Subject: Ocfs2/move_extents: helper to calculate the defraging length in one run. 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 --- fs/ocfs2/move_extents.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'fs/ocfs2') diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c index ae15c998a82..1c822e08fea 100644 --- a/fs/ocfs2/move_extents.c +++ b/fs/ocfs2/move_extents.c @@ -797,3 +797,33 @@ out: 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; + } +} -- cgit v1.2.3-70-g09d2