btrfs: zero the buffer before marking it dirty in btrfs_redirty_list_add

commit c83b56d1dd87cf67492bb770c26d6f87aee70ed6 upstream.

btrfs_redirty_list_add zeroes the buffer data and sets the
EXTENT_BUFFER_NO_CHECK to make sure writeback is fine with a bogus
header.  But it does that after already marking the buffer dirty, which
means that writeback could already be looking at the buffer.

Switch the order of operations around so that the buffer is only marked
dirty when we're ready to write it.

Fixes: d3575156f662 ("btrfs: zoned: redirty released extent buffers")
CC: stable@vger.kernel.org # 5.15+
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 5fb57f04b5996373f60416e3a99949f568b37755..1feb68ae2a8ecab4d4dedbf3d02feb8fa74656c7 100644 (file)
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1605,11 +1605,11 @@ void btrfs_redirty_list_add(struct btrfs_transaction *trans,
            !list_empty(&eb->release_list))
                return;
 
+       memzero_extent_buffer(eb, 0, eb->len);
+       set_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags);
        set_extent_buffer_dirty(eb);
        set_extent_bits_nowait(&trans->dirty_pages, eb->start,
                               eb->start + eb->len - 1, EXTENT_DIRTY);
-       memzero_extent_buffer(eb, 0, eb->len);
-       set_bit(EXTENT_BUFFER_NO_CHECK, &eb->bflags);
 
        spin_lock(&trans->releasing_ebs_lock);
        list_add_tail(&eb->release_list, &trans->releasing_ebs);