[PATCH 8/9] btrfs: simplify eb checksum verification in btrfs_validate_metadata_buffer
From: David Sterba <dsterba@suse.com>
Date: 2021-05-25 17:11:20
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
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. Signed-off-by: David Sterba <dsterba@suse.com> --- 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 6dc137684899..868e358f6923 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 struct btrfs_header *header; 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 = page_address(eb->pages[0]) + + get_eb_offset_in_page(eb, offsetof(struct btrfs_leaf, header)); - 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;
--
2.29.2