| Message ID | 20210211143807.GA115624@redhat (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] block: recalculate segment count for multi-segment discards correctly | expand |
On Thu, Feb 11, 2021 at 10:48 PM David Jeffery <djeffery@redhat.com> wrote: > > 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> > > --- > V2 explicitly returns 1 instead of falling through in the no-multi case and > handles REQ_OP_SECURE_ERASE like REQ_OP_DISCARD. > > block/blk-merge.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/block/blk-merge.c b/block/blk-merge.c > index 808768f6b174..756473295f19 100644 > --- a/block/blk-merge.c > +++ b/block/blk-merge.c > @@ -383,6 +383,14 @@ unsigned int blk_recalc_rq_segments(struct request *rq) > switch (bio_op(rq->bio)) { > case REQ_OP_DISCARD: > case REQ_OP_SECURE_ERASE: > + if (queue_max_discard_segments(rq->q) > 1) { > + struct bio *bio = rq->bio; > + > + 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: > Hello Jens, Any chance to merge this patch which fixes one regression caused by commit 1e739730c5b9?
On 2/11/21 7:38 AM, David Jeffery wrote: > 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. Applied, thanks.
diff --git a/block/blk-merge.c b/block/blk-merge.c index 808768f6b174..756473295f19 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -383,6 +383,14 @@ unsigned int blk_recalc_rq_segments(struct request *rq) switch (bio_op(rq->bio)) { case REQ_OP_DISCARD: case REQ_OP_SECURE_ERASE: + if (queue_max_discard_segments(rq->q) > 1) { + struct bio *bio = rq->bio; + + 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:
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> --- V2 explicitly returns 1 instead of falling through in the no-multi case and handles REQ_OP_SECURE_ERASE like REQ_OP_DISCARD. block/blk-merge.c | 8 ++++++++ 1 file changed, 8 insertions(+)