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    Subject[PATCH 3.4 076/125] dm btree: fix bufio buffer leaks in dm_btree_del() error path
    Date
    From: Joe Thornber <ejt@redhat.com>

    3.4.113-rc1 review patch. If anyone has any objections, please let me know.

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


    commit ed8b45a3679eb49069b094c0711b30833f27c734 upstream.

    If dm_btree_del()'s call to push_frame() fails, e.g. due to
    btree_node_validator finding invalid metadata, the dm_btree_del() error
    path must unlock all frames (which have active dm-bufio buffers) that
    were pushed onto the del_stack.

    Otherwise, dm_bufio_client_destroy() will BUG_ON() because dm-bufio
    buffers have leaked, e.g.:
    device-mapper: bufio: leaked buffer 3, hold count 1, list 0

    Signed-off-by: Joe Thornber <ejt@redhat.com>
    Signed-off-by: Mike Snitzer <snitzer@redhat.com>
    Signed-off-by: Zefan Li <lizefan@huawei.com>
    ---
    drivers/md/persistent-data/dm-btree.c | 16 +++++++++++++++-
    1 file changed, 15 insertions(+), 1 deletion(-)

    diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
    index 77c615e..c948acf 100644
    --- a/drivers/md/persistent-data/dm-btree.c
    +++ b/drivers/md/persistent-data/dm-btree.c
    @@ -230,6 +230,16 @@ static void pop_frame(struct del_stack *s)
    dm_tm_unlock(s->tm, f->b);
    }

    +static void unlock_all_frames(struct del_stack *s)
    +{
    + struct frame *f;
    +
    + while (unprocessed_frames(s)) {
    + f = s->spine + s->top--;
    + dm_tm_unlock(s->tm, f->b);
    + }
    +}
    +
    int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
    {
    int r;
    @@ -285,9 +295,13 @@ int dm_btree_del(struct dm_btree_info *info, dm_block_t root)
    f->current_child = f->nr_children;
    }
    }
    -
    out:
    + if (r) {
    + /* cleanup all frames of del_stack */
    + unlock_all_frames(s);
    + }
    kfree(s);
    +
    return r;
    }
    EXPORT_SYMBOL_GPL(dm_btree_del);
    --
    1.9.1
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