On Fri, May 25, 2018 at 11:45:48AM +0800, Ming Lei wrote: > fs/btrfs/check-integrity.c | 6 +- > fs/btrfs/compression.c | 8 +- > fs/btrfs/disk-io.c | 3 +- > fs/btrfs/extent_io.c | 14 ++- > fs/btrfs/file-item.c | 4 +- > fs/btrfs/inode.c | 12 ++- > fs/btrfs/raid56.c | 5 +- For the btrfs bits, Acked-by: David Sterba <dsterba@xxxxxxxx> but that's from the bio API user perspective only, I'll leave the design and implementation questions to others. I've let the patchset through fstests, no problems. One thing that caught my eye was use of the 'struct bvec_iter_all' in random functions. As this structure is a compound of 2 others and is 40 bytes in size, I was curious how this increased stack consumption. Measured with -fstack-usage before and after patch 22/33 "btrfs: conver to bio_for_each_page_all2" -disk-io.c:btree_csum_one_bio 48 static +disk-io.c:btree_csum_one_bio 80 static -extent_io.c:end_bio_extent_buffer_writepage 56 static +extent_io.c:end_bio_extent_buffer_writepage 80 static -extent_io.c:end_bio_extent_readpage 176 dynamic,bounded +extent_io.c:end_bio_extent_readpage 240 dynamic,bounded -extent_io.c:end_bio_extent_writepage 56 static +extent_io.c:end_bio_extent_writepage 120 static -inode.c:btrfs_retry_endio 96 dynamic,bounded +inode.c:btrfs_retry_endio 144 dynamic,bounded -inode.c:btrfs_retry_endio_nocsum 72 dynamic,bounded +inode.c:btrfs_retry_endio_nocsum 104 dynamic,bounded -raid56.c:set_bio_pages_uptodate 8 static +raid56.c:set_bio_pages_uptodate 40 static It's not that bad, but still quite a lot just to iterate a list of bios. I think it's worth mentioning as it affects several other filesystems and should be possibly optimized in the future.
