From dfd29eed4ab5881a1af9f07c3573c0be5593dc1f Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 21 Sep 2020 22:07:14 +0200 Subject: [PATCH] btrfs: simplify eb checksum verification in btrfs_validate_metadata_buffer The verification copies the calculated checksum bytes to a temporary buffer but this is not necessary. We can map the eb header on the first page and use the checksum bytes directly. This saves at least one function call and boundary checks so it could lead to a minor performance improvement. Reviewed-by: Qu Wenruo Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b28b314ff7a91..34bcd986f738d 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -584,6 +584,7 @@ static int validate_extent_buffer(struct extent_buffer *eb) const u32 csum_size = fs_info->csum_size; u8 found_level; u8 result[BTRFS_CSUM_SIZE]; + const u8 *header_csum; int ret = 0; found_start = btrfs_header_bytenr(eb); @@ -608,15 +609,14 @@ static int validate_extent_buffer(struct extent_buffer *eb) } csum_tree_block(eb, result); + header_csum = page_address(eb->pages[0]) + + get_eb_offset_in_page(eb, offsetof(struct btrfs_header, csum)); - if (memcmp_extent_buffer(eb, result, 0, csum_size)) { - u8 val[BTRFS_CSUM_SIZE] = { 0 }; - - read_extent_buffer(eb, &val, 0, csum_size); + if (memcmp(result, header_csum, csum_size) != 0) { btrfs_warn_rl(fs_info, "checksum verify failed on %llu wanted " CSUM_FMT " found " CSUM_FMT " level %d", eb->start, - CSUM_FMT_VALUE(csum_size, val), + CSUM_FMT_VALUE(csum_size, header_csum), CSUM_FMT_VALUE(csum_size, result), btrfs_header_level(eb)); ret = -EUCLEAN; -- 2.30.2