[Devel] [PATCH rh7 2/3] ext4: rework fallocate(FALLOC_FL_CONVERT_AND_EXTEND)

[Dmitry Monakhov]

Maxim Patlasov <mpatlasov at virtuozzo.com> writes:

> Since Oct 9 2014 (commit 671ddaaab74a8495a549fccae49eb4305c11e5d2), ploop has
> not used FALLOC_FL_KEEP_SIZE. This means that the part of
> fallocate(FALLOC_FL_CONVERT_AND_EXTEND) extending i_size is redundant now.
> Hence, we can use existing (and well tested) ext4_convert_unwritten_extents()
> instead of our home-made (buggy) algorithm.
Ack-by: dmonakhov at openvz.org
>
> https://jira.sw.ru/browse/PSBM-22381
>
> Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
> ---
>  fs/ext4/extents.c |  111 -----------------------------------------------------
>  1 file changed, 1 insertion(+), 110 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 34afee9..cf248ce 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4666,115 +4666,6 @@ retry:
>  	ext4_std_error(inode->i_sb, err);
>  }
>  
> -static int ext4_convert_and_extend_locked(struct inode *inode, loff_t offset,
> -					  loff_t len)
> -{
> -	struct ext4_ext_path *path = NULL;
> -	loff_t new_size = offset + len;
> -	ext4_lblk_t iblock = offset >> inode->i_blkbits;
> -	ext4_lblk_t new_iblock = new_size >> inode->i_blkbits;
> -	unsigned int max_blocks = new_iblock - iblock;
> -	handle_t *handle;
> -	unsigned int credits;
> -	int err = 0;
> -	int ret = 0;
> -
> -	if ((loff_t)iblock << inode->i_blkbits != offset ||
> -	    (loff_t)new_iblock << inode->i_blkbits != new_size)
> -		return -EINVAL;
> -
> -	while (max_blocks > 0) {
> -		struct ext4_extent *ex;
> -		ext4_lblk_t ee_block;
> -		ext4_fsblk_t ee_start;
> -		unsigned short ee_len;
> -		int depth;
> -
> -		/*
> -		 * credits to insert 1 extents into extent tree
> -		 */
> -		credits = ext4_chunk_trans_blocks(inode, max_blocks);
> -		handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, credits);
> -		if (IS_ERR(handle))
> -		       return PTR_ERR(handle);
> -
> -		down_write((&EXT4_I(inode)->i_data_sem));
> -
> -		/* find extent for this block */
> -		path = ext4_ext_find_extent(inode, iblock, NULL, 0);
> -		if (IS_ERR(path)) {
> -			err = PTR_ERR(path);
> -			goto done;
> -		}
> -
> -		depth = ext_depth(inode);
> -		ex = path[depth].p_ext;
> -		BUG_ON(ex == NULL && depth != 0);
> -
> -		if (ex == NULL) {
> -			err = -ENOENT;
> -			goto done;
> -		}
> -
> -		ee_block = le32_to_cpu(ex->ee_block);
> -		ee_start = ext4_ext_pblock(ex);
> -		ee_len = ext4_ext_get_actual_len(ex);
> -		if (!in_range(iblock, ee_block, ee_len)) {
> -			err = -ERANGE;
> -			goto done;
> -		}
> -
> -		if (ext4_ext_is_unwritten(ex)) {
> -			struct ext4_map_blocks map = {0};
> -
> -			map.m_lblk = iblock;
> -			map.m_len = max_blocks;
> -			err = ext4_convert_unwritten_extents_endio(handle, inode,
> -								   &map,
> -								   path);
> -			if (err < 0)
> -				goto done;
> -
> -			ext4_update_inode_fsync_trans(handle, inode, 1);
> -			err = check_eofblocks_fl(handle, inode, iblock, path,
> -						 max_blocks);
> -			if (err)
> -				goto done;
> -		}
> -
> -
> -		up_write((&EXT4_I(inode)->i_data_sem));
> -
> -		iblock += ee_len;
> -		max_blocks -= (ee_len < max_blocks) ? ee_len : max_blocks;
> -
> -		if (!max_blocks && new_size > i_size_read(inode)) {
> -			i_size_write(inode, new_size);
> -			ext4_update_i_disksize(inode, new_size);
> -		}
> -
> -		ret = ext4_mark_inode_dirty(handle, inode);
> -done:
> -		if (err)
> -			up_write((&EXT4_I(inode)->i_data_sem));
> -		else
> -			err = ret;
> -
> -		if (path) {
> -			ext4_ext_drop_refs(path);
> -			kfree(path);
> -		}
> -
> -		ret = ext4_journal_stop(handle);
> -		if (!err && ret)
> -			err = ret;
> -		if (err)
> -			return err;
> -	}
> -
> -	return 0;
> -}
> -
>  static int ext4_convert_and_extend(struct inode *inode, loff_t offset,
>  				   loff_t len)
>  {
> @@ -4784,7 +4675,7 @@ static int ext4_convert_and_extend(struct inode *inode, loff_t offset,
>  		return -EACCES;
>  
>  	mutex_lock(&inode->i_mutex);
> -	err = ext4_convert_and_extend_locked(inode, offset, len);
> +	err = ext4_convert_unwritten_extents(NULL, inode, offset, len);
>  	mutex_unlock(&inode->i_mutex);
>  
>  	return err;
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