Thw whole point of csum_tree_block is to iterate over all extent buffer
pages and pass it to checksumming functions. The bytes where checksum is
stored must be skipped, thus map_private_extent_buffer. This complicates
further offset calculations.
As the first page will be always present, checksum the relevant bytes
unconditionally and then do a simple iteration over the remaining pages.
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
---
fs/btrfs/disk-io.c | 32 ++++++++------------------------
1 file changed, 8 insertions(+), 24 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 3952e4a2f3d7..5f74eb69f2fe 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -259,38 +259,22 @@ struct extent_map *btree_get_extent(struct btrfs_inode *inode,
static int csum_tree_block(struct extent_buffer *buf, u8 *result)
{
struct btrfs_fs_info *fs_info = buf->fs_info;
+ const int num_pages = fs_info->nodesize >> PAGE_SHIFT;
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
- unsigned long len;
- unsigned long cur_len;
- unsigned long offset = BTRFS_CSUM_SIZE;
char *kaddr;
- unsigned long map_start;
- unsigned long map_len;
- int err;
+ int i;
shash->tfm = fs_info->csum_shash;
crypto_shash_init(shash);
+ kaddr = page_address(buf->pages[0]);
+ crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE,
+ PAGE_SIZE - BTRFS_CSUM_SIZE);
- len = buf->len - offset;
-
- while (len > 0) {
- /*
- * Note: we don't need to check for the err == 1 case here, as
- * with the given combination of 'start = BTRFS_CSUM_SIZE (32)'
- * and 'min_len = 32' and the currently implemented mapping
- * algorithm we cannot cross a page boundary.
- */
- err = map_private_extent_buffer(buf, offset, 32,
- &kaddr, &map_start, &map_len);
- if (WARN_ON(err))
- return err;
- cur_len = min(len, map_len - (offset - map_start));
- crypto_shash_update(shash, kaddr + offset - map_start, cur_len);
- len -= cur_len;
- offset += cur_len;
+ for (i = 1; i < num_pages; i++) {
+ kaddr = page_address(buf->pages[i]);
+ crypto_shash_update(shash, kaddr, PAGE_SIZE);
}
memset(result, 0, BTRFS_CSUM_SIZE);
-
crypto_shash_final(shash, result);
return 0;
--
2.25.0
