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authorTristan Ye <tristan.ye@oracle.com>2011-03-18 14:35:40 +0800
committerTristan Ye <tristan.ye@oracle.com>2011-05-25 15:17:12 +0800
commitee16cc037e255801892481a2d0b7c1fff2adf1aa (patch)
tree00ec3109caf8becea9da524282bf66469361ed7c /fs/ocfs2/move_extents.c
parente08477176d5575493ba4c30041245c34f2737ad4 (diff)
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 <tristan.ye@oracle.com>
Diffstat (limited to 'fs/ocfs2/move_extents.c')
-rw-r--r--fs/ocfs2/move_extents.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index ae15c998a82a..1c822e08fea0 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;
+ }
+}