From: David Jeffery djeffery@redhat.com
mainline inclusion from mainline-5.12-rc5 commit a958937ff166fc60d1c3a721036f6ff41bfa2821 category: bugfix bugzilla: 51373 CVE: NA
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When a stacked block device inserts a request into another block device using blk_insert_cloned_request, the request's nr_phys_segments field gets recalculated by a call to blk_recalc_rq_segments in blk_cloned_rq_check_limits. But blk_recalc_rq_segments does not know how to handle multi-segment discards. For disk types which can handle multi-segment discards like nvme, this results in discard requests which claim a single segment when it should report several, triggering a warning in nvme and causing nvme to fail the discard from the invalid state.
WARNING: CPU: 5 PID: 191 at drivers/nvme/host/core.c:700 nvme_setup_discard+0x170/0x1e0 [nvme_core] ... nvme_setup_cmd+0x217/0x270 [nvme_core] nvme_loop_queue_rq+0x51/0x1b0 [nvme_loop] __blk_mq_try_issue_directly+0xe7/0x1b0 blk_mq_request_issue_directly+0x41/0x70 ? blk_account_io_start+0x40/0x50 dm_mq_queue_rq+0x200/0x3e0 blk_mq_dispatch_rq_list+0x10a/0x7d0 ? __sbitmap_queue_get+0x25/0x90 ? elv_rb_del+0x1f/0x30 ? deadline_remove_request+0x55/0xb0 ? dd_dispatch_request+0x181/0x210 __blk_mq_do_dispatch_sched+0x144/0x290 ? bio_attempt_discard_merge+0x134/0x1f0 __blk_mq_sched_dispatch_requests+0x129/0x180 blk_mq_sched_dispatch_requests+0x30/0x60 __blk_mq_run_hw_queue+0x47/0xe0 __blk_mq_delay_run_hw_queue+0x15b/0x170 blk_mq_sched_insert_requests+0x68/0xe0 blk_mq_flush_plug_list+0xf0/0x170 blk_finish_plug+0x36/0x50 xlog_cil_committed+0x19f/0x290 [xfs] xlog_cil_process_committed+0x57/0x80 [xfs] xlog_state_do_callback+0x1e0/0x2a0 [xfs] xlog_ioend_work+0x2f/0x80 [xfs] process_one_work+0x1b6/0x350 worker_thread+0x53/0x3e0 ? process_one_work+0x350/0x350 kthread+0x11b/0x140 ? __kthread_bind_mask+0x60/0x60 ret_from_fork+0x22/0x30
This patch fixes blk_recalc_rq_segments to be aware of devices which can have multi-segment discards. It calculates the correct discard segment count by counting the number of bio as each discard bio is considered its own segment.
Fixes: 1e739730c5b9 ("block: optionally merge discontiguous discard bios into a single request") Signed-off-by: David Jeffery djeffery@redhat.com Reviewed-by: Ming Lei ming.lei@redhat.com Reviewed-by: Laurence Oberman loberman@redhat.com Link: https://lore.kernel.org/r/20210211143807.GA115624@redhat Signed-off-by: Jens Axboe axboe@kernel.dk
Conflicts: block/blk-merge.c
Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Yufen Yu yuyufen@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- block/blk-merge.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c index d24a6c9398ed8..b19fc258d089f 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -235,7 +235,8 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, { struct bio_vec bv, bvprv = { NULL }; int cluster, prev = 0; - unsigned int seg_size, nr_phys_segs; + unsigned int nr_phys_segs = 0; + unsigned int seg_size; struct bio *fbio, *bbio; struct bvec_iter iter;
@@ -245,6 +246,12 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, switch (bio_op(bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: + if (queue_max_discard_segments(q) > 1) { + for_each_bio(bio) + nr_phys_segs++; + return nr_phys_segs; + } + return 1; case REQ_OP_WRITE_ZEROES: return 0; case REQ_OP_WRITE_SAME: @@ -254,7 +261,6 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q, fbio = bio; cluster = blk_queue_cluster(q); seg_size = 0; - nr_phys_segs = 0; for_each_bio(bio) { bio_for_each_segment(bv, bio, iter) { /*