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authorTristan Ye <tristan.ye@oracle.com>2011-03-18 14:35:37 +0800
committerTristan Ye <tristan.ye@oracle.com>2011-05-25 15:17:11 +0800
commite6b5859cccfa0fec02f3c5b1069481efc7186f47 (patch)
treebd0308fa3455645a5fc91e9bd50912441eb07dbf
parent99e4c750419e0bb24a1bbf094b1e6a5a4eedbc36 (diff)
Ocfs2/move_extents: helper to probe a proper region to move in an alloc group.
Before doing the movement of extents, we'd better probe the alloc group from 'goal_blk' for searching a contiguous region to fit the wanted movement, we even will have a best-effort try by compromising to a threshold around the given goal. Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
-rw-r--r--fs/ocfs2/move_extents.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index e928a88f2db1..ebaff625fc28 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -516,3 +516,42 @@ out:
return ret;
}
+
+static void ocfs2_probe_alloc_group(struct inode *inode, struct buffer_head *bh,
+ int *goal_bit, u32 move_len, u32 max_hop,
+ u32 *phys_cpos)
+{
+ int i, used, last_free_bits = 0, base_bit = *goal_bit;
+ struct ocfs2_group_desc *gd = (struct ocfs2_group_desc *)bh->b_data;
+ u32 base_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
+ le64_to_cpu(gd->bg_blkno));
+
+ for (i = base_bit; i < le16_to_cpu(gd->bg_bits); i++) {
+
+ used = ocfs2_test_bit(i, (unsigned long *)gd->bg_bitmap);
+ if (used) {
+ /*
+ * we even tried searching the free chunk by jumping
+ * a 'max_hop' distance, but still failed.
+ */
+ if ((i - base_bit) > max_hop) {
+ *phys_cpos = 0;
+ break;
+ }
+
+ if (last_free_bits)
+ last_free_bits = 0;
+
+ continue;
+ } else
+ last_free_bits++;
+
+ if (last_free_bits == move_len) {
+ *goal_bit = i;
+ *phys_cpos = base_cpos + i;
+ break;
+ }
+ }
+
+ mlog(0, "found phys_cpos: %u to fit the wanted moving.\n", *phys_cpos);
+}