Merge tag 'block-6.19-20251211' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux

Pull block fixes from Jens Axboe:

 - Always initialize DMA state, fixing a potentially nasty issue on the
   block side

 - btrfs zoned write fix with cached zone reports

 - Fix corruption issues in bcache with chained bio's, and further make
   it clear that the chained IO handler is simply a marker, it's not
   code meant to be executed

 - Kill old code dealing with synchronous IO polling in the block layer,
   that has been dead for a long time. Only async polling is supported
   these days

 - Fix a lockdep issue in tag_set management, moving it to RCU

 - Fix an issue with ublks bio_vec iteration

 - Don't unconditionally enforce blocking issue of ublk control
   commands, allow some of them with non-blocking issue as they
   do not block

* tag 'block-6.19-20251211' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
  blk-mq-dma: always initialize dma state
  blk-mq: delete task running check in blk_hctx_poll()
  block: fix cached zone reports on devices with native zone append
  block: Use RCU in blk_mq_[un]quiesce_tagset() instead of set->tag_list_lock
  ublk: don't mutate struct bio_vec in iteration
  block: prohibit calls to bio_chain_endio
  bcache: fix improper use of bi_end_io
  ublk: allow non-blocking ctrl cmds in IO_URING_F_NONBLOCK issue

1 files changed, 5 insertions, 1 deletions

diff --git a/block/bio.c b/block/bio.c
index fa5ff36b443f..e726c0e280a8 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -321,9 +321,13 @@ static struct bio *__bio_chain_endio(struct bio *bio)
 	return parent;
 }
 
+/*
+ * This function should only be used as a flag and must never be called.
+ * If execution reaches here, it indicates a serious programming error.
+ */
 static void bio_chain_endio(struct bio *bio)
 {
-	bio_endio(__bio_chain_endio(bio));
+	BUG();
 }
 
 /**