[PATCH 2/4] btrfs: relocation: Check cancel request after each data page read

Qu Wenruo
2019-12-03T06:43:03Z

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 | }

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

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/relocation.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 9edd65b1bf82..533481a1f962 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -3355,6 +3355,10 @@ 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 (should_cancel_balance(fs_info)) {
+ ret = -ECANCELED;
+ goto out;
+ }
}
WARN_ON(nr != cluster->nr);
out:
--
2.24.0