From a6889caf6ec6ec32f19a02a9118410f39fc84fe2 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Mon, 12 Oct 2020 11:55:26 +0100 Subject: [PATCH] btrfs: do not start readahead for csum tree when scrubbing non-data block groups When scrubbing a stripe of a block group we always start readahead for the checksums btree and wait for it to complete, however when the blockgroup is not a data block group (or a mixed block group) it is a waste of time to do it, since there are no checksums for metadata extents in that btree. So skip that when the block group does not have the data flag set, saving some time doing memory allocations, queueing a job in the readahead work queue, waiting for it to complete and potentially avoiding some IO as well (when csum tree extents are not in memory already). Reviewed-by: Johannes Thumshirn Reviewed-by: Josef Bacik Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/scrub.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index e71e7586e9eb..04351b55dd14 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3084,17 +3084,21 @@ static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx, key_end.offset = (u64)-1; reada1 = btrfs_reada_add(root, &key, &key_end); - key.objectid = BTRFS_EXTENT_CSUM_OBJECTID; - key.type = BTRFS_EXTENT_CSUM_KEY; - key.offset = logical; - key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID; - key_end.type = BTRFS_EXTENT_CSUM_KEY; - key_end.offset = logic_end; - reada2 = btrfs_reada_add(csum_root, &key, &key_end); + if (cache->flags & BTRFS_BLOCK_GROUP_DATA) { + key.objectid = BTRFS_EXTENT_CSUM_OBJECTID; + key.type = BTRFS_EXTENT_CSUM_KEY; + key.offset = logical; + key_end.objectid = BTRFS_EXTENT_CSUM_OBJECTID; + key_end.type = BTRFS_EXTENT_CSUM_KEY; + key_end.offset = logic_end; + reada2 = btrfs_reada_add(csum_root, &key, &key_end); + } else { + reada2 = NULL; + } if (!IS_ERR(reada1)) btrfs_reada_wait(reada1); - if (!IS_ERR(reada2)) + if (!IS_ERR_OR_NULL(reada2)) btrfs_reada_wait(reada2);