At 04/07/2017 08:00 PM, David Sterba wrote:
On Mon, Mar 13, 2017 at 03:52:15PM +0800, Qu Wenruo wrote:@@ -3355,12 +3355,14 @@ static int cache_save_setup(struct btrfs_block_group_cache *block_group, struct btrfs_fs_info *fs_info = block_group->fs_info; struct btrfs_root *root = fs_info->tree_root; struct inode *inode = NULL; + struct extent_changeset data_reserved;Size of this structure is 40 bytes, and it's being added to many functions. This will be noticeable on the stack consumption. -extent-tree.c:btrfs_check_data_free_space 40 static -extent-tree.c:cache_save_setup 96 static +extent-tree.c:btrfs_check_data_free_space 48 static +extent-tree.c:cache_save_setup 136 static -file.c:__btrfs_buffered_write 192 static +file.c:__btrfs_buffered_write 232 static -file.c:btrfs_fallocate 208 static +file.c:btrfs_fallocate 248 static -inode-map.c:btrfs_save_ino_cache 112 static +inode-map.c:btrfs_save_ino_cache 152 static -inode.c:btrfs_direct_IO 128 static +inode.c:btrfs_direct_IO 176 static -inode.c:btrfs_writepage_fixup_worker 88 static +inode.c:btrfs_writepage_fixup_worker 128 static -inode.c:btrfs_truncate_block 136 static +inode.c:btrfs_truncate_block 176 static -inode.c:btrfs_page_mkwrite 112 static +inode.c:btrfs_page_mkwrite 152 static +ioctl.c:cluster_pages_for_defrag 200 static -ioctl.c:btrfs_defrag_file 312 static +ioctl.c:btrfs_defrag_file 232 static -qgroup.c:btrfs_qgroup_reserve_data 136 static +qgroup.c:btrfs_qgroup_reserve_data 128 static -relocation.c:prealloc_file_extent_cluster 152 static +relocation.c:prealloc_file_extent_cluster 192 static There are generic functions so this will affect non-qgroup workloads as well. So there need to be a dynamic allocation (which would add another point of failure), or reworked in another way.
Well, I'll try to rework this to allocate extent_changeset inside btrfs_qgroup_reserve_data(), so that callers only need extra 8 bytes stack space, and no need to introduce extra error handlers.
Thanks, Qu -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
