iomap: use BIO_COMPLETE_IN_TASK for dropbehind writeback

Set BIO_COMPLETE_IN_TASK on iomap writeback bios when a dropbehind folio
is added. This ensures that bi_end_io runs in task context, where
folio_end_dropbehind() can safely invalidate folios.

With the bio layer now handling task-context deferral generically,
IOMAP_IOEND_DONTCACHE is no longer needed, as XFS no longer needs to
route DONTCACHE ioends through its completion workqueue. Remove the flag
and its NOMERGE entry.

Without the NOMERGE, regular I/Os that get merged with a dropbehind
folio will also have their completion deferred to task context.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Link: https://patch.msgid.link/20260730-blk-dontcache-v7-3-3e8e6850068d@columbia.edu
Signed-off-by: Jens Axboe <axboe@kernel.dk>

0 files changed, 0 insertions, 0 deletions