On Thu, May 25, 2017 at 06:26:31PM -0600, Liu Bo wrote:
> Currently scrub only verify checksum of both metadata and data and
> couldn't detect an invalid extent_item.
This is a different kind of check that scrub was never designed to do.
Scrub just verifies the checksums, not the sructural integrity. This has
been referred to as an "on-line fsck". AFAIK xfs does not use 'scrub' in
the same sense as btrfs, so things are going to be confusing for the
users.
The on-line fsck is still desired, but I'd like to see a discussion how
exactly it should work, whether to extend scrub or add a new ioctl etc.
> This adds sanity check for extent item, now it can check if
> extent_inline_ref_type is valid.
>
> Signed-off-by: Liu Bo <bo.li....@oracle.com>
> ---
> fs/btrfs/scrub.c | 43 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> index b0251eb..e87b752 100644
> --- a/fs/btrfs/scrub.c
> +++ b/fs/btrfs/scrub.c
> @@ -3058,6 +3058,39 @@ static noinline_for_stack int
> scrub_raid56_parity(struct scrub_ctx *sctx,
> return ret < 0 ? ret : 0;
> }
>
> +static int check_extent_item(struct extent_buffer *l, int slot,
Please use 'eb' for the extent_buffer.
> + struct btrfs_extent_item *ei, int key_type)
key_type should be u8
> +{
> + unsigned long ptr;
> + unsigned long end;
> + struct btrfs_extent_inline_ref *iref;
> + u64 flags = btrfs_extent_flags(l, ei);
> + int is_data = !!(flags & BTRFS_EXTENT_FLAG_DATA);
> + int type;
> +
> + ptr = (unsigned long)(ei + 1);
> + if (!is_data &&
> + key_type != BTRFS_METADATA_ITEM_KEY)
> + ptr += sizeof(struct btrfs_tree_block_info);
> + end = (unsigned long)ei +
> + btrfs_item_size_nr(l, slot);
This will fit to one line
> +
> + while (1) {
> + if (ptr >= end) {
> + WARN_ON(ptr > end);
Please add some verbose error message or get rid of the WARN_ON
completely if possible.
> + break;
> + }
> +
> + iref = (struct btrfs_extent_inline_ref *)ptr;
> + type = btrfs_get_extent_inline_ref_type(l, iref, is_data);
> + if (type < 0)
> + return type;
> +
> + ptr += btrfs_extent_inline_ref_size(type);
> + }
> + return 0;
> +}
> +
> static noinline_for_stack int scrub_stripe(struct scrub_ctx *sctx,
> struct map_lookup *map,
> struct btrfs_device *scrub_dev,
> @@ -3318,6 +3351,16 @@ static noinline_for_stack int scrub_stripe(struct
> scrub_ctx *sctx,
> goto next;
> }
>
> + /* sanity check for extent inline ref type */
> + if (check_extent_item(l, slot, extent, key.type)) {
> + btrfs_err(fs_info,
> + "scrub: extent %llu(0x%llx) has an
> invalid extent inline ref type, ignored.",
Strings can be un-indented to the left.
> + key.objectid, key.objectid);
> + spin_lock(&sctx->stat_lock);
> + sctx->stat.uncorrectable_errors++;
Yeah, this is an example where the uncorrectable_error would gain a new
meaning. We'd need to extend the scrub error reporting so the various
metadata errors get reported properly and not mangled with the rest.
> + spin_unlock(&sctx->stat_lock);
> + goto next;
> + }
> again:
> extent_logical = key.objectid;
> extent_len = bytes;
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