buffer: set BIO_COMPLETE_IN_TASK for dropbehind writeback

Set BIO_COMPLETE_IN_TASK in __bh_submit() for write bios when the folio
has dropbehind set, so that buffer_head writeback completions get
deferred to task context where folio_end_dropbehind() can safely
invalidate folios.

Read completions are not deferred since dropbehind invalidation for
reads is handled synchronously by the reader.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260730-blk-dontcache-v7-4-3e8e6850068d@columbia.edu
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tal Zussman 2026-07-30 02:57:54 -04:00 • committed by Jens Axboe
commit a2c924c240