Commit 7f913c7c authored Feb 17, 2020 by Qu Wenruo Committed by David Sterba Mar 23, 2020

btrfs: relocation: Check cancel request after each data page read



When relocating a data extents with large large data extents, we spend
most of our time in relocate_file_extent_cluster() at stage "moving data
extents":

 1)               |  btrfs_relocate_block_group [btrfs]() {
 1)               |    relocate_file_extent_cluster [btrfs]() {
 1) $ 6586769 us  |    }
 1) + 18.260 us   |    relocate_file_extent_cluster [btrfs]();
 1) + 15.770 us   |    relocate_file_extent_cluster [btrfs]();
 1) $ 8916340 us  |  }
 1)               |  btrfs_relocate_block_group [btrfs]() {
 1)               |    relocate_file_extent_cluster [btrfs]() {
 1) $ 11611586 us |    }
 1) + 16.930 us   |    relocate_file_extent_cluster [btrfs]();
 1) + 15.870 us   |    relocate_file_extent_cluster [btrfs]();
 1) $ 14986130 us |  }

To make data relocation cancelling quicker, add extra balance cancelling
check after each page read in relocate_file_extent_cluster().

Cleanup and error handling uses the same mechanism as if the whole
process finished

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

parent 726a3421

fs/btrfs/relocation.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -3445,6 +3445,10 @@ static int relocate_file_extent_cluster(struct inode *inode,
		btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
		balance_dirty_pages_ratelimited(inode->i_mapping);
		btrfs_throttle(fs_info);
		if (btrfs_should_cancel_balance(fs_info)) {
		ret = -ECANCELED;
		goto out;
		}
		}
		WARN_ON(nr != cluster->nr);
		out:
		@@ -4259,6 +4263,14 @@ restart:
		backref_cache_cleanup(&rc->backref_cache);
		btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);

		/*
		* Even in the case when the relocation is cancelled, we should all go
		* through prepare_to_merge() and merge_reloc_roots().
		*
		* For error (including cancelled balance), prepare_to_merge() will
		* mark all reloc trees orphan, then queue them for cleanup in
		* merge_reloc_roots()
		*/
		err = prepare_to_merge(rc, err);

		merge_reloc_roots(rc);

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