Re: [Crash-utility] [PATCH v3 1/2] Support for "dev -d|-D" options by parsing bitmap in blk-mq layer

Hi Lianbo, Thank you for the update, much better structure :) Let's go into detail...

> Currently, crash doesn't support to display disk I/O statistics > for blk-mq devices. For more details, please refer to the following > commit: <98b417fc6346> ("Handle blk_mq_ctx member changes for kernels > 5.16-rc1 and later"). > > Lets parse the bitmap in blk-mq layer to achieve it. > > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > --- > defs.h | 11 +++ > dev.c | 261 ++++++++++++++++++++++++++++++++++++++++++++++-------- > symbols.c | 22 +++++ > 3 files changed, 255 insertions(+), 39 deletions(-) > > diff --git a/defs.h b/defs.h > index c8444b4e54eb..2681586a33dc 100644 > --- a/defs.h > +++ b/defs.h > @@ -2170,6 +2170,16 @@ struct offset_table { /* stash of commonly-used offsets */ > long sbq_wait_state_wait; > long sbitmap_alloc_hint; > long sbitmap_round_robin; > + long request_cmd_flags; > + long request_q; > + long request_state; > + long request_queue_queue_hw_ctx; > + long request_queue_nr_hw_queues; > + long blk_mq_hw_ctx_tags; > + long blk_mq_tags_bitmap_tags; > + long blk_mq_tags_breserved_tags; > + long blk_mq_tags_nr_reserved_tags; > + long blk_mq_tags_rqs; > }; > > struct size_table { /* stash of commonly-used sizes */ > @@ -2339,6 +2349,7 @@ struct size_table { /* stash of commonly-used sizes */ > long sbitmap; > long sbitmap_queue; > long sbq_wait_state; > + long blk_mq_tags; > }; > > struct array_table { > diff --git a/dev.c b/dev.c > index a493e51ac95c..c0240f7b889b 100644 > --- a/dev.c > +++ b/dev.c > @@ -4238,19 +4238,193 @@ get_one_mctx_diskio(unsigned long mctx, struct diskio *io) > io->write = (dispatch[1] - comp[1]); > } > > +typedef bool (busy_tag_iter_fn)(ulong rq, void *data); > + > +struct bt_iter_data { I think that some names are confusing and not synced with the kernel. How about renaming to "mq_inflight"? > + ulong q; > + struct diskio *dio; > +}; > + > +struct bt_tags_iter_data { And please rename this to "bt_iter_data". > + ulong tags; > + uint flags; rename to "reserved".

+ uint nr_reserved_tags; > + busy_tag_iter_fn *fn; > + void *data; > +}; > + > +/* > + * See the include/linux/blk_types.h and include/linux/blk-mq.h > + */ > +#define MQ_RQ_IN_FLIGHT 1 > +#define REQ_OP_BITS 8 > +#define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1) > + > +static uint op_is_write(uint op) > +{ > + return (op & REQ_OP_MASK) & 1; > +} > + > +static bool mq_check_inflight(ulong rq, void *data) > +{ > + uint cmd_flags = 0, state = 0; > + ulong addr = 0, queue = 0; > + struct bt_iter_data *iter = data; > + > + if (!IS_KVADDR(rq)) > + return TRUE; Why return TRUE? Does this mean that rq can be invalid with bit on?

+ > + addr = rq + OFFSET(request_q); > + if (!readmem(addr, KVADDR, &queue, sizeof(ulong), "request.q", RETURN_ON_ERROR)) > + return FALSE; > + > + addr = rq + OFFSET(request_cmd_flags); > + if (!readmem(addr, KVADDR, &cmd_flags, sizeof(uint), "request.cmd_flags", RETURN_ON_ERROR)) > + return FALSE; > + > + addr = rq + OFFSET(request_state); > + if (!readmem(addr, KVADDR, &state, sizeof(uint), "request.state", RETURN_ON_ERROR)) > + return FALSE; Rethinking these, RETURN_ON_ERROR leads to stop counting (i.e. wrong results) with error messages. I think it would be better to use FAULT_ON_ERROR unless we can ignore or handle an error correctly. What do you think? (And for the RETURN_ON_ERRORs below, same as above.) At first, I had the same opinion as yours. But eventually, called the

+ > + if (queue == iter->q && state == MQ_RQ_IN_FLIGHT) { > + if (op_is_write(cmd_flags)) > + iter->dio->write++; > + else > + iter->dio->read++; > + } > + > + return TRUE; > +} > + > +static bool bt_tags_iter(uint bitnr, void *data) > +{ > + ulong addr = 0, rqs_addr = 0, rq = 0; > + struct bt_tags_iter_data *tag_iter = data; > + ulong tag = tag_iter->tags; > + > + if (!tag_iter->flags) > + bitnr += tag_iter->nr_reserved_tags; > + > + /* rqs */ > + addr = tag + OFFSET(blk_mq_tags_rqs); > + if (!readmem(addr, KVADDR, &rqs_addr, sizeof(void *), "blk_mq_tags.rqs", RETURN_ON_ERROR)) > + return FALSE; > + > + addr = rqs_addr + bitnr * sizeof(ulong); /* rqs[bitnr] */ > + if (!readmem(addr, KVADDR, &rq, sizeof(ulong), "blk_mq_tags.rqs[]", RETURN_ON_ERROR)) > + return FALSE; > + > + return tag_iter->fn(rq, tag_iter->data); > +} > + > +static void bt_tags_for_each(ulong q, ulong tags, ulong sbq, uint flags, uint nr_resvd_tags, struct diskio *dio) Please rename this to bt_for_each.

+{ > + struct sbitmap_context sc = {0}; > + struct diskio tmp = {0}; This tmp can be removed? (The dio->{read,write} are incremented in mq_check_inflight(), so we don't need the local tmps for each function, I think) Let me double check.

+ struct bt_iter_data iter_data = { > + .q = q, > + .dio = &tmp, > + }; > + struct bt_tags_iter_data tags_iter_data = { > + .tags = tags, > + .flags = flags, > + .nr_reserved_tags = nr_resvd_tags, > + .fn = mq_check_inflight, > + .data = &iter_data, > + }; > + > + sbitmap_context_load(sbq + OFFSET(sbitmap_queue_sb), &sc); > + sbitmap_for_each_set(&sc, bt_tags_iter, &tags_iter_data); > + > + dio->read = tmp.read; > + dio->write = tmp.write; > +} > + > +static void queue_for_each_hw_ctx(ulong q, ulong *hctx, uint cnt, struct diskio *dio) > +{ > + uint i; > + struct diskio tmp = {0}; This also can be removed. > + > + if (!hctx || !dio) > + error(FATAL, "%s: Invalid parameter.\n", __func__); This can be used? Will remove it.

+ > + for (i = 0; i < cnt; i++) { > + ulong addr = 0, tags = 0; > + uint nr_reserved_tags = 0; > + > + if (!IS_KVADDR(hctx[i])) > + continue; Is this the remain of the v1 patch?

+ > + /* 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; > + > + 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 (nr_reserved_tags) { > + addr = tags + OFFSET(blk_mq_tags_breserved_tags); > + bt_tags_for_each(q, tags, addr, 1, nr_reserved_tags, &tmp); > + } > + addr = tags + OFFSET(blk_mq_tags_bitmap_tags); > + bt_tags_for_each(q, tags, addr, 0, nr_reserved_tags, &tmp); (the local tmp set by the nr_reserved_tags case is overwritten here.)

> + } > + > + dio->read = tmp.read; > + dio->write = tmp.write; > +} > + > +static void get_mq_diskio_from_hw_queues(ulong q, struct diskio *dio) > +{ > + uint cnt = 0; > + ulong addr = 0, hctx_addr = 0; > + ulong *hctx_array = NULL; > + struct diskio tmp = {0}; This also can be removed. Ditto.

+ > + addr = q + OFFSET(request_queue_nr_hw_queues); > + readmem(addr, KVADDR, &cnt, sizeof(uint), > + "request_queue.nr_hw_queues", FAULT_ON_ERROR); > + > + addr = q + OFFSET(request_queue_queue_hw_ctx); > + readmem(addr, KVADDR, &hctx_addr, sizeof(void *), > + "request_queue.queue_hw_ctx", FAULT_ON_ERROR); > + > + hctx_array = (ulong *)GETBUF(sizeof(void *) * cnt); > + if (!hctx_array) > + error(FATAL, "fail to get memory for the hctx_array\n"); > + > + if (!readmem(hctx_addr, KVADDR, hctx_array, sizeof(void *) * cnt, > + "request_queue.queue_hw_ctx[]", RETURN_ON_ERROR)) { > + FREEBUF(hctx_array); > + return; > + } > + > + queue_for_each_hw_ctx(q, hctx_array, cnt, &tmp); > + dio->read = tmp.read; > + dio->write = tmp.write; > + > + FREEBUF(hctx_array); > +} > + > static void > get_mq_diskio(unsigned long q, unsigned long *mq_count) > { > int cpu; > unsigned long queue_ctx; > unsigned long mctx_addr; > - struct diskio tmp; > + struct diskio tmp = {0}; > > if (INVALID_MEMBER(blk_mq_ctx_rq_dispatched) || > - INVALID_MEMBER(blk_mq_ctx_rq_completed)) > + INVALID_MEMBER(blk_mq_ctx_rq_completed)) { > + get_mq_diskio_from_hw_queues(q, &tmp); > + mq_count[0] = tmp.read; > + mq_count[1] = tmp.write; > return; > - > - memset(&tmp, 0x00, sizeof(struct diskio)); > + } > > readmem(q + OFFSET(request_queue_queue_ctx), KVADDR, &queue_ctx, > sizeof(ulong), "request_queue.queue_ctx", > @@ -4479,41 +4653,24 @@ display_one_diskio(struct iter *i, unsigned long gendisk, ulong flags) > && (io.read + io.write == 0)) > return; > > - if (use_mq_interface(queue_addr) && > - (INVALID_MEMBER(blk_mq_ctx_rq_dispatched) || > - INVALID_MEMBER(blk_mq_ctx_rq_completed))) > - fprintf(fp, "%s%s%s %s%s%s%s %s%s%s", > - mkstring(buf0, 5, RJUST|INT_DEC, (char *)(unsigned long)major), > - space(MINSPACE), > - mkstring(buf1, VADDR_PRLEN, LJUST|LONG_HEX, (char *)gendisk), > - space(MINSPACE), > - mkstring(buf2, 10, LJUST, disk_name), > - space(MINSPACE), > - mkstring(buf3, VADDR_PRLEN <= 11 ? 11 : VADDR_PRLEN, > - LJUST|LONG_HEX, (char *)queue_addr), > - space(MINSPACE), > - mkstring(buf4, 17, RJUST, "(not supported)"), > - space(MINSPACE)); > - > - else > - fprintf(fp, "%s%s%s %s%s%s%s %s%5d%s%s%s%s%s", > - mkstring(buf0, 5, RJUST|INT_DEC, (char *)(unsigned long)major), > - space(MINSPACE), > - mkstring(buf1, VADDR_PRLEN, LJUST|LONG_HEX, (char *)gendisk), > - space(MINSPACE), > - mkstring(buf2, 10, LJUST, disk_name), > - space(MINSPACE), > - mkstring(buf3, VADDR_PRLEN <= 11 ? 11 : VADDR_PRLEN, > - LJUST|LONG_HEX, (char *)queue_addr), > - space(MINSPACE), > - io.read + io.write, > - space(MINSPACE), > - mkstring(buf4, 5, RJUST|INT_DEC, > - (char *)(unsigned long)io.read), > - space(MINSPACE), > - mkstring(buf5, 5, RJUST|INT_DEC, > - (char *)(unsigned long)io.write), > - space(MINSPACE)); > + fprintf(fp, "%s%s%s %s%s%s%s %s%5d%s%s%s%s%s", > + mkstring(buf0, 5, RJUST|INT_DEC, (char *)(unsigned long)major), > + space(MINSPACE), > + mkstring(buf1, VADDR_PRLEN, LJUST|LONG_HEX, (char *)gendisk), > + space(MINSPACE), > + mkstring(buf2, 10, LJUST, disk_name), > + space(MINSPACE), > + mkstring(buf3, VADDR_PRLEN <= 11 ? 11 : VADDR_PRLEN, > + LJUST|LONG_HEX, (char *)queue_addr), > + space(MINSPACE), > + io.read + io.write, > + space(MINSPACE), > + mkstring(buf4, 5, RJUST|INT_DEC, > + (char *)(unsigned long)io.read), > + space(MINSPACE), > + mkstring(buf5, 5, RJUST|INT_DEC, > + (char *)(unsigned long)io.write), > + space(MINSPACE)); > > if (VALID_MEMBER(request_queue_in_flight)) { > if (!use_mq_interface(queue_addr)) { > @@ -4597,6 +4754,9 @@ void diskio_init(void) > MEMBER_OFFSET_INIT(kobject_entry, "kobject", "entry"); > MEMBER_OFFSET_INIT(kset_list, "kset", "list"); > MEMBER_OFFSET_INIT(request_list_count, "request_list", "count"); > + MEMBER_OFFSET_INIT(request_cmd_flags, "request", "cmd_flags"); > + MEMBER_OFFSET_INIT(request_q, "request", "q"); > + MEMBER_OFFSET_INIT(request_state, "request", "state"); > MEMBER_OFFSET_INIT(request_queue_in_flight, "request_queue", > "in_flight"); > if (MEMBER_EXISTS("request_queue", "rq")) > @@ -4608,10 +4768,33 @@ void diskio_init(void) > "mq_ops"); > ANON_MEMBER_OFFSET_INIT(request_queue_queue_ctx, > "request_queue", "queue_ctx"); > + MEMBER_OFFSET_INIT(request_queue_queue_hw_ctx, > + "request_queue", "queue_hw_ctx"); > + MEMBER_OFFSET_INIT(request_queue_nr_hw_queues, > + "request_queue", "nr_hw_queues"); > MEMBER_OFFSET_INIT(blk_mq_ctx_rq_dispatched, "blk_mq_ctx", > "rq_dispatched"); > MEMBER_OFFSET_INIT(blk_mq_ctx_rq_completed, "blk_mq_ctx", > "rq_completed"); > + MEMBER_OFFSET_INIT(blk_mq_hw_ctx_tags, "blk_mq_hw_ctx", "tags"); > + MEMBER_OFFSET_INIT(blk_mq_tags_bitmap_tags, "blk_mq_tags", > + "bitmap_tags"); > + MEMBER_OFFSET_INIT(blk_mq_tags_breserved_tags, "blk_mq_tags", > + "breserved_tags"); > + MEMBER_OFFSET_INIT(blk_mq_tags_nr_reserved_tags, "blk_mq_tags", > + "nr_reserved_tags"); > + MEMBER_OFFSET_INIT(blk_mq_tags_rqs, "blk_mq_tags", "rqs"); > + STRUCT_SIZE_INIT(blk_mq_tags, "blk_mq_tags"); > + STRUCT_SIZE_INIT(sbitmap, "sbitmap"); > + STRUCT_SIZE_INIT(sbitmap_word, "sbitmap_word"); > + MEMBER_OFFSET_INIT(sbitmap_word_word, "sbitmap_word", "word"); > + MEMBER_OFFSET_INIT(sbitmap_word_cleared, "sbitmap_word", "cleared"); > + MEMBER_OFFSET_INIT(sbitmap_depth, "sbitmap", "depth"); > + MEMBER_OFFSET_INIT(sbitmap_shift, "sbitmap", "shift"); > + MEMBER_OFFSET_INIT(sbitmap_map_nr, "sbitmap", "map_nr"); > + MEMBER_OFFSET_INIT(sbitmap_map, "sbitmap", "map"); > + MEMBER_OFFSET_INIT(sbitmap_queue_sb, "sbitmap_queue", "sb"); > + > } > MEMBER_OFFSET_INIT(subsys_private_klist_devices, "subsys_private", > "klist_devices"); > diff --git a/symbols.c b/symbols.c > index 5d12a021c769..c1f09556d710 100644 > --- a/symbols.c > +++ b/symbols.c > @@ -10385,6 +10385,12 @@ dump_offset_table(char *spec, ulong makestruct) > OFFSET(kset_list)); > fprintf(fp, " request_list_count: %ld\n", > OFFSET(request_list_count)); > + fprintf(fp, " request_cmd_flags: %ld\n", > + OFFSET(request_cmd_flags)); > + fprintf(fp, " request_q: %ld\n", > + OFFSET(request_q)); > + fprintf(fp, " request_state: %ld\n", > + OFFSET(request_state)); > fprintf(fp, " request_queue_in_flight: %ld\n", > OFFSET(request_queue_in_flight)); > fprintf(fp, " request_queue_rq: %ld\n", > @@ -10393,10 +10399,25 @@ dump_offset_table(char *spec, ulong makestruct) > OFFSET(request_queue_mq_ops)); > fprintf(fp, " request_queue_queue_ctx: %ld\n", > OFFSET(request_queue_queue_ctx)); > + fprintf(fp, " request_queue_queue_hw_ctx: %ld\n", > + OFFSET(request_queue_queue_hw_ctx)); > + fprintf(fp, " request_queue_nr_hw_queues: %ld\n", > + OFFSET(request_queue_nr_hw_queues)); > fprintf(fp, " blk_mq_ctx_rq_dispatched: %ld\n", > OFFSET(blk_mq_ctx_rq_dispatched)); > fprintf(fp, " blk_mq_ctx_rq_completed: %ld\n", > OFFSET(blk_mq_ctx_rq_completed)); > + fprintf(fp, " blk_mq_hw_ctx_tags: %ld\n", > + OFFSET(blk_mq_hw_ctx_tags)); > + fprintf(fp, " blk_mq_tags_bitmap_tags: %ld\n", > + OFFSET(blk_mq_tags_bitmap_tags)); > + fprintf(fp, " blk_mq_tags_breserved_tags: %ld\n", > + OFFSET(blk_mq_tags_breserved_tags)); > + fprintf(fp, " blk_mq_tags_nr_reserved_tags: %ld\n", > + OFFSET(blk_mq_tags_nr_reserved_tags)); > + fprintf(fp, " blk_mq_tags_rqs: %ld\n", > + OFFSET(blk_mq_tags_rqs)); Good, thanks for adjusting these indents. Thanks, Kazu > + > fprintf(fp, " subsys_private_klist_devices: %ld\n", > OFFSET(subsys_private_klist_devices)); > fprintf(fp, " subsystem_kset: %ld\n", > @@ -11003,6 +11024,7 @@ dump_offset_table(char *spec, ulong makestruct) > fprintf(fp, " sbitmap: %ld\n", SIZE(sbitmap)); > fprintf(fp, " sbitmap_queue: %ld\n", SIZE(sbitmap_queue)); > fprintf(fp, " sbq_wait_state: %ld\n", SIZE(sbq_wait_state)); > + fprintf(fp, " blk_mq_tags: %ld\n", SIZE(blk_mq_tags)); > > fprintf(fp, "\n array_table:\n"); > /*