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Ocfs2/move_extents: helper to validate and adjust moving goal.

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First best-effort attempt to validate and adjust the goal (physical address in
block), while it can't guarantee later operation can succeed all the time since
global_bitmap may change a bit over time.

Signed-off-by: Tristan Ye <tristan.ye@oracle.com>
This commit is contained in:
Tristan Ye 2011-03-18 14:35:36 +08:00
parent 1c06b91261
commit 99e4c75041
1 changed files with 61 additions and 0 deletions
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61
fs/ocfs2/move_extents.c
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@ -455,3 +455,64 @@ out:
*/
return ret;
}
/*
* XXX: helper to validate and adjust moving goal.
*/
static int ocfs2_validate_and_adjust_move_goal(struct inode *inode,
struct ocfs2_move_extents *range)
{
int ret, goal_bit = 0;
struct buffer_head *gd_bh = NULL;
struct ocfs2_group_desc *bg;
struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
int c_to_b = 1 << (osb->s_clustersize_bits -
inode->i_sb->s_blocksize_bits);
/*
* validate goal sits within global_bitmap, and return the victim
* group desc
*/
ret = ocfs2_find_victim_alloc_group(inode, range->me_goal,
GLOBAL_BITMAP_SYSTEM_INODE,
OCFS2_INVALID_SLOT,
&goal_bit, &gd_bh);
if (ret)
goto out;
bg = (struct ocfs2_group_desc *)gd_bh->b_data;
/*
* make goal become cluster aligned.
*/
if (range->me_goal % c_to_b)
range->me_goal = range->me_goal / c_to_b * c_to_b;
/*
* moving goal is not allowd to start with a group desc blok(#0 blk)
* let's compromise to the latter cluster.
*/
if (range->me_goal == le64_to_cpu(bg->bg_blkno))
range->me_goal += c_to_b;
/*
* movement is not gonna cross two groups.
*/
if ((le16_to_cpu(bg->bg_bits) - goal_bit) * osb->s_clustersize <
range->me_len) {
ret = -EINVAL;
goto out;
}
/*
* more exact validations/adjustments will be performed later during
* moving operation for each extent range.
*/
mlog(0, "extents get ready to be moved to #%llu block\n",
range->me_goal);
out:
brelse(gd_bh);
return ret;
}