btrfs: scrub: simplify tree block checksum calculation

Use a simpler iteration over tree block pages, same what csum_tree_block
does: first page always exists, loop over the rest.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 19a64c7..663bb2c 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1814,15 +1814,10 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
        SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
        u8 calculated_csum[BTRFS_CSUM_SIZE];
        u8 on_disk_csum[BTRFS_CSUM_SIZE];
+       const int num_pages = sctx->fs_info->nodesize >> PAGE_SHIFT;
+       int i;
        struct page *page;
        char *kaddr;
-       u64 mapped_size;
-       void *p;
-       u64 len;
-       int index;
-
-       shash->tfm = fs_info->csum_shash;
-       crypto_shash_init(shash);
 
        BUG_ON(sblock->page_count < 1);
        page = sblock->pagev[0]->page;
@@ -1850,24 +1845,14 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
                   BTRFS_UUID_SIZE))
                sblock->header_error = 1;
 
-       len = sctx->fs_info->nodesize - BTRFS_CSUM_SIZE;
-       mapped_size = PAGE_SIZE - BTRFS_CSUM_SIZE;
-       p = kaddr + BTRFS_CSUM_SIZE;
-       index = 0;
-       for (;;) {
-               u64 l = min_t(u64, len, mapped_size);
+       shash->tfm = fs_info->csum_shash;
+       crypto_shash_init(shash);
+       crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE,
+                           PAGE_SIZE - BTRFS_CSUM_SIZE);
 
-               crypto_shash_update(shash, p, l);
-               len -= l;
-               if (len == 0)
-                       break;
-               index++;
-               BUG_ON(index >= sblock->page_count);
-               BUG_ON(!sblock->pagev[index]->page);
-               page = sblock->pagev[index]->page;
-               kaddr = page_address(page);
-               mapped_size = PAGE_SIZE;
-               p = kaddr;
+       for (i = 1; i < num_pages; i++) {
+               kaddr = page_address(sblock->pagev[i]->page);
+               crypto_shash_update(shash, kaddr, PAGE_SIZE);
        }
 
        crypto_shash_final(shash, calculated_csum);