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authorDavid Jeffery <djeffery@redhat.com>2021-02-11 09:38:07 -0500
committerJens Axboe <axboe@kernel.dk>2021-03-23 10:39:57 -0600
commita958937ff166fc60d1c3a721036f6ff41bfa2821 (patch)
tree51617a4631d07827220c1237ee9e99fc2602324e
parent5116784039f0421e9a619023cfba3e302c3d9adc (diff)
block: recalculate segment count for multi-segment discards correctly
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>
-rw-r--r--block/blk-merge.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c
index ffb4aa0ea68b..4d97fb6dd226 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -382,6 +382,14 @@ 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: