From: Yu Kuai <[email protected]> Add bio_alloc_atomic() for callers that need a GFP_ATOMIC bio from the default bio set but cannot safely pass a bdev during allocation. The helper returns an unattached bio, leaving callers to set bi_bdev and attach blkcg state explicitly before submission.
Use the helper for virtio-pmem flush child bios and OCFS2 heartbeat I/O. Both allocate bios from atomic paths and must avoid creating missing blkgs once blkg creation is protected by q->blkcg_mutex. virtio-pmem clones the parent bio's blkg association; OCFS2 binds heartbeat I/O to the root blkg. Signed-off-by: Yu Kuai <[email protected]> --- drivers/nvdimm/nd_virtio.c | 8 ++++---- fs/ocfs2/cluster/heartbeat.c | 15 ++++++++++++--- include/linux/bio.h | 6 ++++++ 3 files changed, 22 insertions(+), 7 deletions(-) diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c index 4176046627be..13d1ed1c466c 100644 --- a/drivers/nvdimm/nd_virtio.c +++ b/drivers/nvdimm/nd_virtio.c @@ -115,13 +115,13 @@ int async_pmem_flush(struct nd_region *nd_region, struct bio *bio) * parent bio. Otherwise directly call nd_region flush. */ if (bio && bio->bi_iter.bi_sector != -1) { - struct bio *child = bio_alloc(bio->bi_bdev, 0, - REQ_OP_WRITE | REQ_PREFLUSH, - GFP_ATOMIC); + struct bio *child = bio_alloc_atomic(0, + REQ_OP_WRITE | REQ_PREFLUSH); if (!child) return -ENOMEM; - bio_clone_blkg_association(child, bio); + child->bi_bdev = bio->bi_bdev; + bio_clone_blkg_association(child, bio); child->bi_iter.bi_sector = -1; bio_chain(child, bio); submit_bio(child); diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c index d12784aaaa4b..ec70f3b62837 100644 --- a/fs/ocfs2/cluster/heartbeat.c +++ b/fs/ocfs2/cluster/heartbeat.c @@ -10,6 +10,7 @@ #include <linux/module.h> #include <linux/fs.h> #include <linux/bio.h> +#include <linux/blk-cgroup.h> #include <linux/blkdev.h> #include <linux/delay.h> #include <linux/file.h> @@ -519,16 +520,24 @@ static struct bio *o2hb_setup_one_bio(struct o2hb_region *reg, struct bio *bio; struct page *page; - /* Testing has shown this allocation to take long enough under + /* + * Testing has shown this allocation to take long enough under * GFP_KERNEL that the local node can get fenced. It would be * nicest if we could pre-allocate these bios and avoid this - * all together. */ - bio = bio_alloc(reg_bdev(reg), 16, opf, GFP_ATOMIC); + * all together. + * + * Use the atomic bio allocation helper so bio_init() does not create a + * missing blkg. Heartbeat IO is cluster-liveness IO, so account it to + * the root blkcg instead. + */ + bio = bio_alloc_atomic(16, opf); if (!bio) { mlog(ML_ERROR, "Could not alloc slots BIO!\n"); bio = ERR_PTR(-ENOMEM); goto bail; } + bio->bi_bdev = reg_bdev(reg); + bio_associate_blkg_from_css(bio, blkcg_root_css); /* Must put everything in 512 byte sectors for the bio... */ bio->bi_iter.bi_sector = (reg->hr_start_block + cs) << (bits - 9); diff --git a/include/linux/bio.h b/include/linux/bio.h index 8f33f717b14f..f7d94d37893f 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -366,6 +366,12 @@ static inline struct bio *bio_alloc(struct block_device *bdev, return bio_alloc_bioset(bdev, nr_vecs, opf, gfp_mask, &fs_bio_set); } +static inline struct bio *bio_alloc_atomic(unsigned short nr_vecs, + blk_opf_t opf) +{ + return bio_alloc_bioset(NULL, nr_vecs, opf, GFP_ATOMIC, &fs_bio_set); +} + void submit_bio(struct bio *bio); extern void bio_endio(struct bio *); -- 2.51.0
