[Ocfs2-devel] [PATCH 06/14] Ocfs2/move_extents: move a range of extent.

[Tristan Ye]

Mark Fasheh wrote:
> On Fri, Jan 21, 2011 at 06:20:23PM +0800, Tristan Ye wrote:
>> The moving range of __ocfs2_move_extent() was within one extent always, it
>> consists following parts:
>>
>> 1. Duplicates the clusters in pages to new_blkoffset, where extent to be moved.
>>
>> 2. Split the original extent with new extent, coalecse the nearby extents if possible.
>>
>> 3. Append old clusters to truncate log, or decrease_refcount if the extent was refcounted.
>>
>> Signed-off-by: Tristan Ye <tristan.ye at oracle.com>
>> ---
>>  fs/ocfs2/move_extents.c |  104 +++++++++++++++++++++++++++++++++++++++++++++++
>>  1 files changed, 104 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
>> index 9b30636..e28bd7d 100644
>> --- a/fs/ocfs2/move_extents.c
>> +++ b/fs/ocfs2/move_extents.c
>> @@ -56,6 +56,110 @@ struct ocfs2_move_extents_context {
>>  	struct ocfs2_cached_dealloc_ctxt dealloc;
>>  };
>>  
>> +static int __ocfs2_move_extent(handle_t *handle,
>> +			       struct ocfs2_move_extents_context *context,
>> +			       u32 cpos, u32 len, u32 p_cpos, u32 new_p_cpos,
>> +			       int ext_flags)
>> +{
>> +	int ret = 0, index;
>> +	struct inode *inode = context->inode;
>> +	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
>> +	struct ocfs2_extent_rec *rec, replace_rec;
>> +	struct ocfs2_path *path = NULL;
>> +	struct ocfs2_extent_list *el;
>> +	u64 ino = ocfs2_metadata_cache_owner(context->et.et_ci);
>> +	u64 old_blkno = ocfs2_clusters_to_blocks(inode->i_sb, p_cpos);
>> +
>> +	ret = ocfs2_duplicate_clusters_by_page(handle, context->file, cpos,
>> +					       p_cpos, new_p_cpos, len);
>> +	if (ret) {
>> +		mlog_errno(ret);
>> +		goto out;
>> +	}
>> +
>> +	memset(&replace_rec, 0, sizeof(replace_rec));
>> +	replace_rec.e_cpos = cpu_to_le32(cpos);
>> +	replace_rec.e_leaf_clusters = cpu_to_le16(len);
>> +	replace_rec.e_blkno = cpu_to_le64(ocfs2_clusters_to_blocks(inode->i_sb,
>> +								   new_p_cpos));
>> +
>> +	path = ocfs2_new_path_from_et(&context->et);
>> +	if (!path) {
>> +		ret = -ENOMEM;
>> +		mlog_errno(ret);
>> +		goto out;
>> +	}
>> +
>> +	ret = ocfs2_find_path(INODE_CACHE(inode), path, cpos);
>> +	if (ret) {
>> +		mlog_errno(ret);
>> +		goto out;
>> +	}
>> +
>> +	el = path_leaf_el(path);
>> +
>> +	index = ocfs2_search_extent_list(el, cpos);
>> +	if (index == -1 || index >= le16_to_cpu(el->l_next_free_rec)) {
>> +		ocfs2_error(inode->i_sb,
>> +			    "Inode %llu has an extent at cpos %u which can no "
>> +			    "longer be found.\n",
>> +			    (unsigned long long)ino, cpos);
>> +		ret = -EROFS;
>> +		goto out;
>> +	}
>> +
>> +	rec = &el->l_recs[index];
>> +
>> +	BUG_ON(ext_flags != rec->e_flags);
>> +	/*
>> +	 * after moving/defraging to new location, the extent is not going
>> +	 * to be refcounted anymore.
>> +	 */
>> +	if (ext_flags & OCFS2_EXT_REFCOUNTED)
>> +		replace_rec.e_flags = ext_flags & ~OCFS2_EXT_REFCOUNTED;
>> +	else
>> +		replace_rec.e_flags = ext_flags;
>
> You can remove the if statement here and just leave it as:
>
> 	replace_rec.e_flags = ext_flags & ~OCFS2_EXT_REFCOUNTED;

Definitely, I loved this optimization;-)

>
> which will do the same thing.
> 	--Mark
>
> --
> Mark Fasheh