• NeilBrown's avatar
    blk: make the bioset rescue_workqueue optional. · 47e0fb46
    NeilBrown authored
    This patch converts bioset_create() to not create a workqueue by
    default, so alloctions will never trigger punt_bios_to_rescuer().  It
    also introduces a new flag BIOSET_NEED_RESCUER which tells
    bioset_create() to preserve the old behavior.
    
    All callers of bioset_create() that are inside block device drivers,
    are given the BIOSET_NEED_RESCUER flag.
    
    biosets used by filesystems or other top-level users do not
    need rescuing as the bio can never be queued behind other
    bios.  This includes fs_bio_set, blkdev_dio_pool,
    btrfs_bioset, xfs_ioend_bioset, and one allocated by
    target_core_iblock.c.
    
    biosets used by md/raid do not need rescuing as
    their usage was recently audited and revised to never
    risk deadlock.
    
    It is hoped that most, if not all, of the remaining biosets
    can end up being the non-rescued version.
    Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
    Credit-to: Ming Lei <ming.lei@redhat.com> (minor fixes)
    Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
    Signed-off-by: default avatarNeilBrown <neilb@suse.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    47e0fb46
super.c 50.3 KB