From e6b5859cccfa0fec02f3c5b1069481efc7186f47 Mon Sep 17 00:00:00 2001 From: Tristan Ye Date: Fri, 18 Mar 2011 14:35:37 +0800 Subject: [PATCH] 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 --- fs/ocfs2/move_extents.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) 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); +}