On Mon, 6 May 2013 23:11:20 +0200, David Sterba wrote:
> Superblock is always 4k, but metadata blocks may be larger. We have to
> use the appropriate block size when doing checksums, otherwise they're
> wrong.
>
> Signed-off-by: David Sterba <dsterba@xxxxxxx>
> ---
> btrfs-image.c | 27 +++++++++++++++++++++++----
> 1 file changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/btrfs-image.c b/btrfs-image.c
> index 188291c..dca7a28 100644
> --- a/btrfs-image.c
> +++ b/btrfs-image.c
> @@ -469,6 +469,16 @@ static int read_data_extent(struct metadump_struct *md,
> return 0;
> }
>
> +static int is_sb_offset(u64 offset) {
> + switch (offset) {
> + case 65536:
> + case 67108864:
> + case 274877906944:
Using btrfs_sb_offset() and an if statement would produce the same code
and would be more readable.
Additionally, the last huge number will cause a warning on 32-bit
systems, I assume.
> + return 1;
> + }
> + return 0;
> +}
> +
> static int flush_pending(struct metadump_struct *md, int done)
> {
> struct async_work *async = NULL;
> @@ -506,7 +516,16 @@ static int flush_pending(struct metadump_struct *md, int done)
> }
>
> while (!md->data && size > 0) {
> - eb = read_tree_block(md->root, start, blocksize, 0);
> + /*
> + * We must differentiate between superblock and
> + * metadata on filesystems with blocksize > 4k,
> + * otherwise the checksum fails for superblock
> + */
> + int bs = blocksize;
> +
> + if (is_sb_offset(start))
> + bs = BTRFS_SUPER_INFO_SIZE;
> + eb = read_tree_block(md->root, start, bs, 0);
> if (!eb) {
> free(async->buffer);
> free(async);
> @@ -516,9 +535,9 @@ static int flush_pending(struct metadump_struct *md, int done)
> }
> copy_buffer(async->buffer + offset, eb);
> free_extent_buffer(eb);
> - start += blocksize;
> - offset += blocksize;
> - size -= blocksize;
> + start += bs;
> + offset += bs;
> + size -= bs;
> }
>
> md->pending_start = (u64)-1;
>
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