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    Subject[PATCH 3.16 033/245] Btrfs: improve check_node to avoid reading corrupted nodes
    3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Liu Bo <bo.li.liu@oracle.com>

    commit 6b722c1747d533ac6d4df110dc8233db46918b65 upstream.

    We need to check items in a node to make sure that we're reading
    a valid one, otherwise we could get various crashes while processing
    delayed_refs.

    Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
    Reviewed-by: David Sterba <dsterba@suse.com>
    Signed-off-by: David Sterba <dsterba@suse.com>
    Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    fs/btrfs/disk-io.c | 32 ++++++++++++++++++++++++++++----
    1 file changed, 28 insertions(+), 4 deletions(-)

    --- a/fs/btrfs/disk-io.c
    +++ b/fs/btrfs/disk-io.c
    @@ -508,9 +508,10 @@ static int check_tree_block_fsid(struct
    }

    #define CORRUPT(reason, eb, root, slot) \
    - btrfs_crit(root->fs_info, "corrupt leaf, %s: block=%llu," \
    - "root=%llu, slot=%d", reason, \
    - btrfs_header_bytenr(eb), root->objectid, slot)
    + btrfs_crit(root->fs_info, "corrupt %s, %s: block=%llu," \
    + " root=%llu, slot=%d", \
    + btrfs_header_level(eb) == 0 ? "leaf" : "node",\
    + reason, btrfs_header_bytenr(eb), root->objectid, slot)

    static noinline int check_leaf(struct btrfs_root *root,
    struct extent_buffer *leaf)
    @@ -601,6 +602,10 @@ static noinline int check_leaf(struct bt
    static int check_node(struct btrfs_root *root, struct extent_buffer *node)
    {
    unsigned long nr = btrfs_header_nritems(node);
    + struct btrfs_key key, next_key;
    + int slot;
    + u64 bytenr;
    + int ret = 0;

    if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root)) {
    btrfs_crit(root->fs_info,
    @@ -608,7 +613,26 @@ static int check_node(struct btrfs_root
    node->start, root->objectid, nr);
    return -EIO;
    }
    - return 0;
    +
    + for (slot = 0; slot < nr - 1; slot++) {
    + bytenr = btrfs_node_blockptr(node, slot);
    + btrfs_node_key_to_cpu(node, &key, slot);
    + btrfs_node_key_to_cpu(node, &next_key, slot + 1);
    +
    + if (!bytenr) {
    + CORRUPT("invalid item slot", node, root, slot);
    + ret = -EIO;
    + goto out;
    + }
    +
    + if (btrfs_comp_cpu_keys(&key, &next_key) >= 0) {
    + CORRUPT("bad key order", node, root, slot);
    + ret = -EIO;
    + goto out;
    + }
    + }
    +out:
    + return ret;
    }

    static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
    \
     
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