Sure, thanks!
On Thu, Jul 24, 2025 at 3:36 PM lijiang <liji...@redhat.com> wrote:
>
> On Thu, Jul 24, 2025 at 9:18 AM Tao Liu <l...@redhat.com> wrote:
>>
>> Hi lianbo,
>>
>> Kindly ping for this patch...
>>
> Sorry about it. I will take a look next week.
>
> Thanks
> Lianbo
>
>>
>> Thanks,
>> Tao Liu
>>
>> On Fri, Jun 27, 2025 at 11:33 PM Tao Liu <l...@redhat.com> wrote:
>> >
>> > When blk_mq shared tags enabled for devices like scsi, the IO status is
>> > incorrect, e.g:
>> >
>> > crash> dev -d
>> > MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC
>> > SYNC
>> > 8 ffff90528df86000 sda ffff9052a3d61800 144 144 >> > 0
>> > 8 ffff905280718c00 sdb ffff9052a3d63c00 48 48 >> > 0
>> >
>> > crash> epython rqlist
>> > ffff90528e94a5c0 sda is unknown, deadline: 89.992 (90)
>> > rq_alloc: 0.196
>> > ffff90528e92f700 sda is unknown, deadline: 89.998 (90)
>> > rq_alloc: 0.202
>> > ffff90528e95ccc0 sda is unknown, deadline: 89.999 (90)
>> > rq_alloc: 0.203
>> > ffff90528e968bc0 sdb is unknown, deadline: 89.997 (90)
>> > rq_alloc: 0.201
>> >
>> > The root cause is: for shared tags case, only the shared tags are put
>> > into count. Without this patch, tags of all the hw_ctx are counted,
>> > which is incorrect.
>> >
>> > After apply the patch:
>> >
>> > crash> dev -d
>> > MAJOR GENDISK NAME REQUEST_QUEUE TOTAL READ
>> > WRITE
>> > 8 ffff90528df86000 sda ffff9052a3d61800 3 3 >> > 0
>> > 8 ffff905280718c00 sdb ffff9052a3d63c00 1 1 >> > 0
>> >
>> > This patch makes the following modification:
>> > 1) blk_mq shared tag support.
>> > 2) Function renaming: queue_for_each_hw_ctx -> blk_mq_queue_tag_busy_iter,
>> > because the latter is more close to the corresponding kernel function.
>> > 3) Extract a new queue_for_each_hw_ctx() function to be called for both
>> > shared-tags case and the hw_ctx case.
>> >
>> > Note:
>> > The patch is safe for earlier kernels which have no blk_mq shared tags
>> > implemented, because the blk_mq_is_shared_tags() check will exit safely.
>> >
>> > Signed-off-by: Tao Liu <l...@redhat.com>
>> > ---
>> >
>> > Please discard the previous patch "Filter repeated rq for cmd dev -d/-D",
>> > because filtering is an incorrect fix.
>> >
>> > ---
>> > defs.h | 3 ++
>> > dev.c | 96 ++++++++++++++++++++++++++++++++++++++-----------------
>> > symbols.c | 6 ++++
>> > 3 files changed, 76 insertions(+), 29 deletions(-)
>> >
>> > diff --git a/defs.h b/defs.h
>> > index bbd6d4b..4fecb83 100644
>> > --- a/defs.h
>> > +++ b/defs.h
>> > @@ -2271,6 +2271,9 @@ struct offset_table { /* stash of
>> > commonly-used offsets */
>> > long task_struct_thread_context_x28;
>> > long neigh_table_hash_heads;
>> > long neighbour_hash;
>> > + long request_queue_tag_set;
>> > + long blk_mq_tag_set_flags;
>> > + long blk_mq_tag_set_shared_tags;
>> > };
>> >
>> > struct size_table { /* stash of commonly-used sizes */
>> > diff --git a/dev.c b/dev.c
>> > index 9d38aef..0a4d5c9 100644
>> > --- a/dev.c
>> > +++ b/dev.c
>> > @@ -4326,6 +4326,12 @@ struct bt_iter_data {
>> > #define MQ_RQ_IN_FLIGHT 1
>> > #define REQ_OP_BITS 8
>> > #define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1)
>> > +#define BLK_MQ_F_TAG_HCTX_SHARED (1 << 3)
>> > +
>> > +static bool blk_mq_is_shared_tags(unsigned int flags)
>> > +{
>> > + return flags & BLK_MQ_F_TAG_HCTX_SHARED;
>> > +}
>> >
>> > static uint op_is_write(uint op)
>> > {
>> > @@ -4403,43 +4409,72 @@ static void bt_for_each(ulong q, ulong tags, ulong
>> > sbq, uint reserved, uint nr_r
>> > sbitmap_for_each_set(&sc, bt_iter, &iter_data);
>> > }
>> >
>> > -static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct
>> > diskio *dio)
>> > +static bool queue_for_each_hw_ctx(ulong q, ulong blk_mq_tags_ptr,
>> > + bool bitmap_tags_is_ptr, struct diskio
>> > *dio)
>> > {
>> > - uint i;
>> > + uint i, nr_reserved_tags = 0;
>> > + ulong tags = 0, addr = 0;
>> > + bool ret = FALSE;
>> > +
>> > + if (!readmem(blk_mq_tags_ptr, KVADDR, &tags, sizeof(ulong),
>> > + "blk_mq_hw_ctx.tags", RETURN_ON_ERROR))
>> > + goto out;
>> > +
>> > + addr = tags + OFFSET(blk_mq_tags_nr_reserved_tags);
>> > + if (!readmem(addr, KVADDR, &nr_reserved_tags, sizeof(uint),
>> > + "blk_mq_tags_nr_reserved_tags", RETURN_ON_ERROR))
>> > + goto out;
>> > +
>> > + if (nr_reserved_tags) {
>> > + addr = tags + OFFSET(blk_mq_tags_breserved_tags);
>> > + if (bitmap_tags_is_ptr &&
>> > + !readmem(addr, KVADDR, &addr, sizeof(ulong),
>> > + "blk_mq_tags.bitmap_tags",
>> > RETURN_ON_ERROR))
>> > + goto out;
>> > + bt_for_each(q, tags, addr, 1, nr_reserved_tags, dio);
>> > + }
>> > + addr = tags + OFFSET(blk_mq_tags_bitmap_tags);
>> > + if (bitmap_tags_is_ptr &&
>> > + !readmem(addr, KVADDR, &addr, sizeof(ulong),
>> > + "blk_mq_tags.bitmap_tags", RETURN_ON_ERROR))
>> > + goto out;
>> > + bt_for_each(q, tags, addr, 0, nr_reserved_tags, dio);
>> > +
>> > + ret = TRUE;
>> > +out:
>> > + return ret;
>> > +}
>> > +
>> > +/*
>> > + * Replica of kernel block/blk-mq-tag.c:blk_mq_queue_tag_busy_iter()
>> > +*/
>> > +static void blk_mq_queue_tag_busy_iter(ulong q, ulong *hctx, uint cnt,
>> > + struct diskio *dio)
>> > +{
>> > + uint i, flags;
>> > int bitmap_tags_is_ptr = 0;
>> > + ulong addr = 0;
>> >
>> > if (MEMBER_TYPE("blk_mq_tags", "bitmap_tags") == TYPE_CODE_PTR)
>> > bitmap_tags_is_ptr = 1;
>> >
>> > - for (i = 0; i < cnt; i++) {
>> > - ulong addr = 0, tags = 0;
>> > - uint nr_reserved_tags = 0;
>> > + readmem(q + OFFSET(request_queue_tag_set), KVADDR, &addr,
>> > + sizeof(ulong), "request_queue.tag_set", RETURN_ON_ERROR);
>> >
>> > - /* Tags owned by the block driver */
>> > - addr = hctx[i] + OFFSET(blk_mq_hw_ctx_tags);
>> > - if (!readmem(addr, KVADDR, &tags, sizeof(ulong),
>> > - "blk_mq_hw_ctx.tags", RETURN_ON_ERROR))
>> > - break;
>> > + readmem(addr + OFFSET(blk_mq_tag_set_flags), KVADDR,
>> > + &flags, sizeof(uint), "blk_mq_tag_set.flags",
>> > RETURN_ON_ERROR);
>> >
>> > - addr = tags + OFFSET(blk_mq_tags_nr_reserved_tags);
>> > - if (!readmem(addr, KVADDR, &nr_reserved_tags, sizeof(uint),
>> > - "blk_mq_tags_nr_reserved_tags",
>> > RETURN_ON_ERROR))
>> > - break;
>> > + if (blk_mq_is_shared_tags(flags)) {
>> > + addr = addr + OFFSET(blk_mq_tag_set_shared_tags);
>> > + queue_for_each_hw_ctx(q, addr, bitmap_tags_is_ptr, dio);
>> > + return;
>> > + }
>> >
>> > - if (nr_reserved_tags) {
>> > - addr = tags + OFFSET(blk_mq_tags_breserved_tags);
>> > - if (bitmap_tags_is_ptr &&
>> > - !readmem(addr, KVADDR, &addr, sizeof(ulong),
>> > - "blk_mq_tags.bitmap_tags",
>> > RETURN_ON_ERROR))
>> > - break;
>> > - bt_for_each(q, tags, addr, 1, nr_reserved_tags,
>> > dio);
>> > - }
>> > - addr = tags + OFFSET(blk_mq_tags_bitmap_tags);
>> > - if (bitmap_tags_is_ptr &&
>> > - !readmem(addr, KVADDR, &addr, sizeof(ulong),
>> > - "blk_mq_tags.bitmap_tags",
>> > RETURN_ON_ERROR))
>> > - break;
>> > - bt_for_each(q, tags, addr, 0, nr_reserved_tags, dio);
>> > + for (i = 0; i < cnt; i++) {
>> > + /* Tags owned by the block driver */
>> > + addr = hctx[i] + OFFSET(blk_mq_hw_ctx_tags);
>> > + if (queue_for_each_hw_ctx(q, addr, bitmap_tags_is_ptr,
>> > dio) == FALSE)
>> > + return;
>> > }
>> > }
>> >
>> > @@ -4489,7 +4524,7 @@ static void get_mq_diskio_from_hw_queues(ulong q,
>> > struct diskio *dio)
>> > return;
>> > }
>> >
>> > - queue_for_each_hw_ctx(q, hctx_array, cnt, dio);
>> > + blk_mq_queue_tag_busy_iter(q, hctx_array, cnt, dio);
>> >
>> > FREEBUF(hctx_array);
>> > }
>> > @@ -4914,6 +4949,9 @@ void diskio_init(void)
>> > MEMBER_SIZE_INIT(class_private_devices, "class_private",
>> > "class_devices");
>> > MEMBER_OFFSET_INIT(disk_stats_in_flight, "disk_stats",
>> > "in_flight");
>> > + MEMBER_OFFSET_INIT(request_queue_tag_set, "request_queue",
>> > "tag_set");
>> > + MEMBER_OFFSET_INIT(blk_mq_tag_set_flags, "blk_mq_tag_set",
>> > "flags");
>> > + MEMBER_OFFSET_INIT(blk_mq_tag_set_shared_tags, "blk_mq_tag_set",
>> > "shared_tags");
>> >
>> > dt->flags |= DISKIO_INIT;
>> > }
>> > diff --git a/symbols.c b/symbols.c
>> > index e30fafe..794519a 100644
>> > --- a/symbols.c
>> > +++ b/symbols.c
>> > @@ -11487,6 +11487,12 @@ dump_offset_table(char *spec, ulong makestruct)
>> > OFFSET(blk_mq_tags_nr_reserved_tags));
>> > fprintf(fp, " blk_mq_tags_rqs: %ld\n",
>> > OFFSET(blk_mq_tags_rqs));
>> > + fprintf(fp, " request_queue_tag_set: %ld\n",
>> > + OFFSET(request_queue_tag_set));
>> > + fprintf(fp, " blk_mq_tag_set_flags: %ld\n",
>> > + OFFSET(blk_mq_tag_set_flags));
>> > + fprintf(fp, " blk_mq_tag_set_shared_tags: %ld\n",
>> > + OFFSET(blk_mq_tag_set_shared_tags));
>> >
>> > fprintf(fp, " subsys_private_subsys: %ld\n",
>> > OFFSET(subsys_private_subsys));
>> > fprintf(fp, " subsys_private_klist_devices: %ld\n",
>> > --
>> > 2.47.0
>> >
>>
--
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