btrfs: scrub: support subpage tree block scrub

To support subpage tree block scrub, scrub_checksum_tree_block() only
needs to learn 2 new tricks:

- Follow sector size
  Now scrub_page only represents one sector, we need to follow it
  properly.

- Run checksum on all sectors
  Since scrub_page only represents one sector, we need to run checksum
  on all sectors, not only (nodesize >> PAGE_SIZE).

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index a1bf879..5ff6ee7 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -1811,12 +1811,22 @@ 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;
+       /*
+        * This is done in sectorsize steps even for metadata as there's a
+        * constraint for nodesize to be aligned to sectorsize. This will need
+        * to change so we don't misuse data and metadata units like that.
+        */
+       const u32 sectorsize = sctx->fs_info->sectorsize;
+       const int num_sectors = fs_info->nodesize >> fs_info->sectorsize_bits;
        int i;
        struct scrub_page *spage;
        char *kaddr;
 
        BUG_ON(sblock->page_count < 1);
+
+       /* Each member in pagev is just one block, not a full page */
+       ASSERT(sblock->page_count == num_sectors);
+
        spage = sblock->pagev[0];
        kaddr = page_address(spage->page);
        h = (struct btrfs_header *)kaddr;
@@ -1845,11 +1855,11 @@ static int scrub_checksum_tree_block(struct scrub_block *sblock)
        shash->tfm = fs_info->csum_shash;
        crypto_shash_init(shash);
        crypto_shash_update(shash, kaddr + BTRFS_CSUM_SIZE,
-                           PAGE_SIZE - BTRFS_CSUM_SIZE);
+                           sectorsize - BTRFS_CSUM_SIZE);
 
-       for (i = 1; i < num_pages; i++) {
+       for (i = 1; i < num_sectors; i++) {
                kaddr = page_address(sblock->pagev[i]->page);
-               crypto_shash_update(shash, kaddr, PAGE_SIZE);
+               crypto_shash_update(shash, kaddr, sectorsize);
        }
 
        crypto_shash_final(shash, calculated_csum);