btrfs: scrub: simplify superblock checksum calculation

BTRFS_SUPER_INFO_SIZE is 4096, and fits to a page on all supported
architectures, so we can calculate the checksum in one go.

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

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 7dc4a09..13ee43f 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1907,15 +1907,8 @@ static int scrub_checksum_super(struct scrub_block *sblock)
        u8 on_disk_csum[BTRFS_CSUM_SIZE];
        struct page *page;
        char *kaddr;
-       u64 mapped_size;
-       void *p;
        int fail_gen = 0;
        int fail_cor = 0;
-       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;
@@ -1932,27 +1925,11 @@ static int scrub_checksum_super(struct scrub_block *sblock)
        if (!scrub_check_fsid(s->fsid, sblock->pagev[0]))
                ++fail_cor;
 
-       len = BTRFS_SUPER_INFO_SIZE - 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);
-
-               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;
-       }
+       shash->tfm = fs_info->csum_shash;
+       crypto_shash_init(shash);
+       crypto_shash_digest(shash, kaddr + BTRFS_CSUM_SIZE,
+                       BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE, calculated_csum);
 
-       crypto_shash_final(shash, calculated_csum);
        if (memcmp(calculated_csum, on_disk_csum, sctx->csum_size))
                ++fail_cor;