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Date: Mon, 17 Oct 2022 10:26:29 +0900
From: Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To: Chaitanya Kulkarni <kch@...dia.com>, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: axboe@...nel.dk, johannes.thumshirn@....com, bvanassche@....org,
ming.lei@...hat.com, shinichiro.kawasaki@....com,
vincent.fu@...sung.com, yukuai3@...wei.com
Subject: Re: [PATCH] null_blk: allow teardown on request timeout
On 10/16/22 14:20, Chaitanya Kulkarni wrote:
> In current timeout implementation null_blk just completes the request
> with error=BLK_STS_TIMEOUT without doing any cleanup, hence device
> cleanup code including handling inflight requests on timeout and
> teardown is never exercised.
>
> Add a module parameter rq_abort_limit to allow null_blk perform device
> cleanup when time out occurs. The non zero value of this parameter
> allows user to set the number of timeouts to occur before triggering
> cleanup/teardown work.
>
> Signed-off-by: Chaitanya Kulkarni <kch@...dia.com>
> ---
> * Test result enabling the rq_abort_limit from module parameter and
> issueing dd until null_blk device disappears from the pathname
> with connetion timeout error.
>
> linux-block (for-next) # !./test_
> ./test_null_blk_abort_on_timeout.sh
> commit 4fbcf978ae8f385aa1830ce40f210c7eec8d58fa (HEAD -> for-next)
> Author: Chaitanya Kulkarni <kch@...dia.com>
> Date: Tue Oct 11 23:22:43 2022 -0700
>
> null_blk: allow teardown on request timeout
>
> In current timeout implementation null_blk just completes the request
> with error=BLK_STS_TIMEOUT without doing any cleanup, hence device
> cleanup code including handling inflight requests on timeout and
> teardown is never exercised.
>
> Add a module parameter rq_abort_limit to allow null_blk perform device
> cleanup when time out occurs. The non zero value of this parameter
> allows user to set the number of timeouts to occur before triggering
> cleanup/teardown work.
>
> Signed-off-by: Chaitanya Kulkarni <kch@...dia.com>
> + umount /mnt/nullb0
> umount: /mnt/nullb0: not mounted.
> + rmdir 'config/nullb/nullb*'
> rmdir: failed to remove 'config/nullb/nullb*': No such file or directory
> + dmesg -c
> + modprobe -r null_blk
> + lsmod
> + grep null_blk
> ++ nproc
> + make -j 48 M=drivers/block modules
> CC [M] drivers/block/null_blk/main.o
> CC [M] drivers/block/null_blk/trace.o
> CC [M] drivers/block/null_blk/zoned.o
> LD [M] drivers/block/null_blk/null_blk.o
> MODPOST drivers/block/Module.symvers
> LD [M] drivers/block/null_blk/null_blk.ko
> + HOST=drivers/block/null_blk/
> ++ uname -r
> + HOST_DEST=/lib/modules/6.0.0blk+/kernel/drivers/block/null_blk/
> + cp drivers/block/null_blk//null_blk.ko /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//
> + ls -lrth /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//null_blk.ko
> -rw-r--r--. 1 root root 1.2M Oct 15 21:51 /lib/modules/6.0.0blk+/kernel/drivers/block/null_blk//null_blk.ko
> + sleep 1
> + dmesg -c
> ##################
> ##################
> nullb0 250:0 0 250G 0 disk
> dd: error writing '/dev/nullb0': Connection timed out
> 3+0 records in
> 2+0 records out
> 8192 bytes (8.2 kB, 8.0 KiB) copied, 6.13436 s, 1.3 kB/s
> ##################
> ##################
> nullb0 250:0 0 250G 0 disk
> [ 1598.393544] null_blk: rq 0000000015ff5165 timed out
> [ 1598.393555] blk_print_req_error: 74 callbacks suppressed
> [ 1598.393558] timeout error, dev nullb0, sector 8 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1598.395885] Buffer I/O error on dev nullb0, logical block 1, async page read
> [ 1598.397731] Dev nullb0: unable to read RDB block 8
> [ 1598.398990] nullb0: unable to read partition table
> [ 1598.399069] null_blk: disk nullb0 created
> [ 1598.399071] null_blk: module loaded
> [ 1604.537424] null_blk: rq 00000000b2a753f0 timed out
> [ 1604.537437] timeout error, dev nullb0, sector 16 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.13561 s, 0.0 kB/s
> ##################
> ##################
> nullb0 250:0 0 250G 0 disk
> [ 1610.681242] null_blk: rq 00000000a392790b timed out
> [ 1610.681253] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.13985 s, 0.0 kB/s
> ##################
> ##################
> nullb0 250:0 0 250G 0 disk
> [ 1616.825155] null_blk: rq 0000000091a70f01 timed out
> [ 1616.825168] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 1+0 records in
> 0+0 records out
> 0 bytes copied, 6.1325 s, 0.0 kB/s
> ##################
> ##################
> nullb0 250:0 0 250G 0 disk
> [ 1622.969017] null_blk: rq 00000000cdb610e7 timed out
> [ 1622.969029] timeout error, dev nullb0, sector 0 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> dd: error writing '/dev/nullb0': Connection timed out
> 2+0 records in
> 1+0 records out
> 4096 bytes (4.1 kB, 4.0 KiB) copied, 6.14283 s, 0.7 kB/s
> ##################
> ##################
> [ 1629.112893] null_blk: rq 00000000555ecc5e timed out
> [ 1629.118817] blk_sync_queue 230
> [ 1629.118821] blk_sync_queue 232
> [ 1629.118823] blk_sync_queue 234
> [ 1629.118828] timeout error, dev nullb0, sector 8 op 0x1:(WRITE) flags 0x8800 phys_seg 1 prio class 2
> [ 1629.125044] blk_sync_queue 230
> [ 1629.125048] blk_sync_queue 232
> [ 1629.125049] blk_sync_queue 234
> ##################
> ##################
>
> * Test result enabling the rq_abort_limit from module parameter and
> issueing fio until null_blk device disappears from the pathname
> with connetion timeout error.
> nullb0 250:0 0 250G 0 disk
> RANDREAD: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=128
> fio-3.27
> Starting 1 process
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=214274048, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=32268288, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=107802624, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=193708032, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=202928128, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=281436160, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=33292288, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=250576896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=41902080, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=225521664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=303058944, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=405196800, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=309719040, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=111214592, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=254062592, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=128663552, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=76795904, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=355647488, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=5873664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=69328896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=216276992, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=16027648, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=328343552, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=385630208, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=137695232, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=146546688, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=157765632, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=290615296, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=230440960, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=130961408, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=88547328, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=157401088, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=296202240, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=35819520, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=212545536, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=261697536, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=66195456, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=254603264, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=169242624, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=258154496, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=69320704, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=335650816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=192950272, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=32813056, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=5804032, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=217219072, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=153227264, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=91131904, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=241209344, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=246509568, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=332935168, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=108859392, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=86061056, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=278966272, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=219004928, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=290512896, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=143306752, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=176312320, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=346566656, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=183422976, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=383885312, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=199393280, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=160944128, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=142491648, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=217841664, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=178466816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=331423744, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=88883200, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=311562240, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=228642816, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=362893312, buflen=4096
> fio: io_u error on file /dev/nullb0: Connection timed out: read offset=323035136, buflen=4096
> fio: io_u error on file /dev/nullb0: Input/output error: read offset=385089536, buflen=4096
> fio: pid=7811, err=110/file:io_u.c:1841, func=io_u error, error=Connection timed out
>
> RANDREAD: (groupid=0, jobs=1): err=110 (file:io_u.c:1841, func=io_u error, error=Connection timed out): pid=7811: Sat Oct 15 21:52:09 2022
> read: IOPS=33, BW=64.6KiB/s (66.1kB/s)(420KiB/6503msec)
> slat (nsec): min=942, max=6485.4M, avg=29824299.02, stdev=439245367.62
> clat (usec): min=525, max=6501.3k, avg=3899782.52, stdev=3194606.52
> lat (usec): min=530, max=6501.3k, avg=3961597.01, stdev=3181404.42
> clat percentiles (usec):
> | 1.00th=[ 545], 5.00th=[ 553], 10.00th=[ 562],
> | 20.00th=[ 611], 30.00th=[ 15795], 40.00th=[ 15795],
> | 50.00th=[6476006], 60.00th=[6476006], 70.00th=[6476006],
> | 80.00th=[6476006], 90.00th=[6476006], 95.00th=[6476006],
> | 99.00th=[6476006], 99.50th=[6476006], 99.90th=[6476006],
> | 99.95th=[6476006], 99.99th=[6476006]
> bw ( KiB/s): min= 216, max= 216, per=100.00%, avg=216.00, stdev= 0.00, samples=1
> iops : min= 54, max= 54, avg=54.00, stdev= 0.00, samples=1
> lat (usec) : 750=12.39%
> lat (msec) : 20=6.88%, >=2000=28.90%
> cpu : usr=0.00%, sys=0.00%, ctx=4, majf=0, minf=150
> IO depths : 1=0.5%, 2=0.9%, 4=1.8%, 8=3.7%, 16=7.3%, 32=14.7%, >=64=71.1%
> submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
> complete : 0=0.0%, 4=98.9%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=1.1%
> issued rwts: total=218,0,0,0 short=40,0,0,0 dropped=0,0,0,0
> latency : target=0, window=0, percentile=100.00%, depth=128
>
> Run status group 0 (all jobs):
> READ: bw=64.6KiB/s (66.1kB/s), 64.6KiB/s-64.6KiB/s (66.1kB/s-66.1kB/s), io=420KiB (430kB), run=6503-6503msec
>
> Disk stats (read/write):
> nullb0: ios=90/0, merge=0/0, ticks=0/0, in_queue=0, util=98.55%
> ##################
> ##################
> [ 1635.256737] null_blk: rq 00000000834b8ba3 timed out
> [ 1635.256748] timeout error, dev nullb0, sector 0 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1635.258876] Buffer I/O error on dev nullb0, logical block 0, async page read
> [ 1641.400625] null_blk: rq 00000000ee97fbff timed out
> [ 1641.400636] timeout error, dev nullb0, sector 8 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1641.402919] Buffer I/O error on dev nullb0, logical block 1, async page read
> [ 1641.404755] Dev nullb0: unable to read RDB block 8
> [ 1641.406666] nullb0: unable to read partition table
> [ 1641.407559] null_blk: disk nullb0 created
> [ 1641.407562] null_blk: module loaded
> [ 1648.056420] null_blk: rq 00000000834b8ba3 timed out
> [ 1648.056432] timeout error, dev nullb0, sector 418504 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.058914] null_blk: rq 0000000064c974a9 timed out
> [ 1648.058918] timeout error, dev nullb0, sector 63024 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.061288] null_blk: rq 00000000ee97fbff timed out
> [ 1648.061291] timeout error, dev nullb0, sector 210552 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.063663] null_blk: rq 000000006c6fa717 timed out
> [ 1648.063667] timeout error, dev nullb0, sector 378336 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.066011] null_blk: rq 00000000fa856166 timed out
> [ 1648.066015] null_blk: rq 00000000de9bec9a timed out
> [ 1648.066016] timeout error, dev nullb0, sector 396344 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.068390] null_blk: rq 00000000f12b4b17 timed out
> [ 1648.068393] timeout error, dev nullb0, sector 549680 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.071389] null_blk: rq 00000000667726b2 timed out
> [ 1648.071393] timeout error, dev nullb0, sector 65024 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.073740] null_blk: rq 0000000088f0f903 timed out
> [ 1648.073744] timeout error, dev nullb0, sector 489408 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.078759] null_blk: rq 00000000fd349776 timed out
> [ 1648.078762] timeout error, dev nullb0, sector 81840 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.081093] null_blk: rq 000000002eb20dc4 timed out
> [ 1648.081096] timeout error, dev nullb0, sector 440472 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 2
> [ 1648.083492] null_blk: rq 000000002db4026f timed out
> [ 1648.083496] null_blk: rq 00000000db8f8be3 timed out
> [ 1648.083499] null_blk: rq 00000000078a6daf timed out
> [ 1648.083502] null_blk: rq 000000002c1b7c68 timed out
> [ 1648.083505] null_blk: rq 00000000790d87a1 timed out
> [ 1648.083508] null_blk: rq 000000004f48b7de timed out
> [ 1648.083516] null_blk: rq 0000000074a5ff86 timed out
> [ 1648.083518] null_blk: rq 000000000daf10f8 timed out
> [ 1648.083521] null_blk: rq 00000000d54f527e timed out
> [ 1648.083523] null_blk: rq 0000000009dc7bb8 timed out
> [ 1648.083526] null_blk: rq 0000000017e81cd2 timed out
> [ 1648.083529] null_blk: rq 0000000088e83fa2 timed out
> [ 1648.083532] null_blk: rq 000000003c014afe timed out
> [ 1648.083534] null_blk: rq 00000000b7a99358 timed out
> [ 1648.083537] null_blk: rq 00000000d2d80485 timed out
> [ 1648.083539] null_blk: rq 000000008805db58 timed out
> [ 1648.083541] null_blk: rq 000000005c2e8f7a timed out
> [ 1648.083544] null_blk: rq 00000000a33a2f2d timed out
> [ 1648.083546] null_blk: rq 00000000d05bf454 timed out
> [ 1648.083549] null_blk: rq 0000000080cb849f timed out
> [ 1648.083552] null_blk: rq 000000009cbb48e0 timed out
> [ 1648.083555] null_blk: rq 000000009e426689 timed out
> [ 1648.083558] null_blk: rq 000000003705d117 timed out
> [ 1648.083561] null_blk: rq 0000000010bc80b4 timed out
> [ 1648.083563] null_blk: rq 000000004da816da timed out
> [ 1648.083566] null_blk: rq 0000000081ceaf3f timed out
> [ 1648.083568] null_blk: rq 00000000fb1e808e timed out
> [ 1648.083570] null_blk: rq 000000006baf39c2 timed out
> [ 1648.083573] null_blk: rq 00000000241e851f timed out
> [ 1648.083575] null_blk: rq 00000000a7b7ff27 timed out
> [ 1648.083577] null_blk: rq 0000000092e37377 timed out
> [ 1648.083580] null_blk: rq 00000000a2b070cd timed out
> [ 1648.083583] null_blk: rq 00000000a2c63d6f timed out
> [ 1648.083585] null_blk: rq 00000000b775711d timed out
> [ 1648.083588] null_blk: rq 000000000bfe50e6 timed out
> [ 1648.083590] null_blk: rq 000000005c0b7039 timed out
> [ 1648.083593] null_blk: rq 00000000af60d454 timed out
> [ 1648.083595] null_blk: rq 00000000d2a38d75 timed out
> [ 1648.083598] null_blk: rq 0000000000ae81a8 timed out
> [ 1648.083601] null_blk: rq 000000001974c62a timed out
> [ 1648.083603] null_blk: rq 000000002aaf80e6 timed out
> [ 1648.083605] null_blk: rq 00000000bcdf1c85 timed out
> [ 1648.083608] null_blk: rq 000000008b5d9eb6 timed out
> [ 1648.083610] null_blk: rq 0000000066fcf345 timed out
> [ 1648.083613] null_blk: rq 0000000067dc1221 timed out
> [ 1648.083615] null_blk: rq 0000000088e78508 timed out
> [ 1648.083618] null_blk: rq 000000009d1352eb timed out
> [ 1648.083620] null_blk: rq 00000000a7019839 timed out
> [ 1648.083622] null_blk: rq 00000000f5756a31 timed out
> [ 1648.083625] null_blk: rq 00000000841b16a6 timed out
> [ 1648.083627] null_blk: rq 0000000082fa3e11 timed out
> [ 1648.083630] null_blk: rq 00000000794e9904 timed out
> [ 1648.083632] null_blk: rq 00000000c3bcf5d1 timed out
> [ 1648.094395] blk_sync_queue 230
> [ 1648.094400] blk_sync_queue 232
> [ 1648.094402] blk_sync_queue 234
> [ 1648.096130] blk_sync_queue 230
> [ 1648.096133] blk_sync_queue 232
> [ 1648.096135] blk_sync_queue 234
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> sda 8:0 0 50G 0 disk
> ├─sda1 8:1 0 1G 0 part /boot
> └─sda2 8:2 0 49G 0 part /home
> sdb 8:16 0 100G 0 disk /mnt/data
> sr0 11:0 1 1024M 0 rom
> zram0 251:0 0 8G 0 disk [SWAP]
> ---
> drivers/block/null_blk/main.c | 90 +++++++++++++++++++++++++++++--
> drivers/block/null_blk/null_blk.h | 10 ++++
> 2 files changed, 97 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 1f154f92f4c2..52db6b99b448 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -77,6 +77,10 @@ enum {
> NULL_IRQ_TIMER = 2,
> };
>
> +static unsigned int g_rq_abort_limit = 5;
> +module_param_named(rq_abort_limit, g_rq_abort_limit, uint, 0644);
> +MODULE_PARM_DESC(rq_abort_limit, "request timeout teardown limit. Default:5");
Number of request timeout to trigger device teardown ?
That would a lot clearer in my opinion.
> +
> static bool g_virt_boundary = false;
> module_param_named(virt_boundary, g_virt_boundary, bool, 0444);
> MODULE_PARM_DESC(virt_boundary, "Require a virtual boundary for the device. Default: False");
> @@ -247,6 +251,7 @@ static void null_del_dev(struct nullb *nullb);
> static int null_add_dev(struct nullb_device *dev);
> static struct nullb *null_find_dev_by_name(const char *name);
> static void null_free_device_storage(struct nullb_device *dev, bool is_cache);
> +static void null_destroy_dev(struct nullb *nullb);
>
> static inline struct nullb_device *to_nullb_device(struct config_item *item)
> {
> @@ -578,6 +583,18 @@ config_item *nullb_group_make_item(struct config_group *group, const char *name)
> {
> struct nullb_device *dev;
>
> + if (g_rq_abort_limit) {
> + /*
> + * abort_on_timeout removes the null_blk and resources. When
...the null_blk device and its resources. When the null_blk device is
created using configfs, ...
The remaining of the sentence does not parse at all.
> + * null_blk is created using configfs entry by user we will also
> + * need to cleanup the those entries when abort_on_timeout is set
> + * from null_abort_work() and that we shold not do it, since
> + * manupulating user's entries from kernel can create confusion,
> + * so just don't allow it.
> + */
> + pr_err("don't use g_abort_on_timeout with configfs entries\n");
> + return ERR_PTR(-EINVAL);
> + }
> if (null_find_dev_by_name(name))
> return ERR_PTR(-EEXIST);
>
> @@ -614,7 +631,7 @@ static ssize_t memb_group_features_show(struct config_item *item, char *page)
> "poll_queues,power,queue_mode,shared_tag_bitmap,size,"
> "submit_queues,use_per_node_hctx,virt_boundary,zoned,"
> "zone_capacity,zone_max_active,zone_max_open,"
> - "zone_nr_conv,zone_size\n");
> + "zone_nr_conv,zone_size,abort_on_timeout,rq_abort_limit\n");
Where is abort_on_timeout defined ? Nowhere to be seen. Does this patch
even compile ? Also, assuming this is a boolean, why introduce it ?
Wouldn't using "rq_abort_limit > 0" be equivalent ?
> }
>
> CONFIGFS_ATTR_RO(memb_group_, features);
> @@ -1609,10 +1626,60 @@ static int null_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
> return nr;
> }
>
> +static bool null_cancel_request(struct request *rq, void *data)
> +{
> + struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
> +
> + /*
> + * Keep it simple and set the timeout error since we've been schedule
> + * from timeout handler afterall.
> + */
> + cmd->error = BLK_STS_TIMEOUT;
> + if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq))
> + blk_mq_complete_request(rq);
> + return true;
> +}
> +
> +static void null_abort_work(struct work_struct *w)
> +{
> + struct nullb *nullb = container_of(w, struct nullb, abort_work);
> +
> + mutex_lock(&lock);
> + if (!nullb || !nullb->dev)
> + goto unlock;
> +
> + /*
> + * To make sure that null_handle_cmd() callers are not in progress from
> + * null_queue_rq()/null_submit_bio() when we are stopping nullb, we
> + * quiece the block layer request queue and engage in teardown sequence.
> + */
> + blk_freeze_queue_start(nullb->q);
> + blk_mq_quiesce_queue(nullb->q);
> + /*
> + * We already ensured that submit_bio() will not add any plugging by
> + * quiescing so it is safe to sync queue now.
> + */
> + blk_sync_queue(nullb->q);
> + blk_mq_tagset_busy_iter(nullb->tag_set, null_cancel_request, nullb);
> + blk_mq_tagset_wait_completed_request(nullb->tag_set);
> + /*
> + * Unblock any pending dispatch I/Os before we destroy the device.
> + * From null_destroy_dev()->del_gendisk() will set GD_DEAD flag
> + * causing any new I/O from __bio_queue_enter() to fail with -ENODEV.
> + */
> + blk_mq_unquiesce_queue(nullb->q);
> +
> + null_destroy_dev(nullb);
> +unlock:
> + mutex_unlock(&lock);
> +}
> +
> static enum blk_eh_timer_return null_timeout_rq(struct request *rq)
> {
> struct blk_mq_hw_ctx *hctx = rq->mq_hctx;
> struct nullb_cmd *cmd = blk_mq_rq_to_pdu(rq);
> + struct nullb *nullb = cmd->nq->dev->nullb;
> + bool fake_timeout_no_abort = cmd->fake_timeout && !g_rq_abort_limit;
>
> pr_info("rq %p timed out\n", rq);
>
> @@ -1632,9 +1699,23 @@ static enum blk_eh_timer_return null_timeout_rq(struct request *rq)
> * Only fake timeouts need to execute blk_mq_complete_request() here.
> */
> cmd->error = BLK_STS_TIMEOUT;
> - if (cmd->fake_timeout || hctx->type == HCTX_TYPE_POLL)
> + if (fake_timeout_no_abort || hctx->type == HCTX_TYPE_POLL) {
> blk_mq_complete_request(rq);
> - return BLK_EH_DONE;
> + return BLK_EH_DONE;
> + }
> +
> + if (atomic_dec_return(&nullb->rq_abort_count) != 0) {
> + blk_mq_complete_request(rq);
> + return BLK_EH_DONE;
> + }
> +
> + if (!flush_work(&nullb->abort_work))
> + queue_work(system_highpri_wq, &nullb->abort_work);
> + /*
> + * null_abort_work() will take care of completing all the requests
> + * including timed out one.
> + */
> + return BLK_EH_RESET_TIMER;
> }
>
> static blk_status_t null_queue_rq(struct blk_mq_hw_ctx *hctx,
> @@ -2124,6 +2205,9 @@ static int null_add_dev(struct nullb_device *dev)
> if (rv)
> goto out_ida_free;
>
> + INIT_WORK(&nullb->abort_work, null_abort_work);
> + atomic_set(&nullb->rq_abort_count, g_rq_abort_limit);
> +
> mutex_lock(&lock);
> list_add_tail(&nullb->list, &nullb_list);
> mutex_unlock(&lock);
> diff --git a/drivers/block/null_blk/null_blk.h b/drivers/block/null_blk/null_blk.h
> index 94ff68052b1e..d7f5d3161908 100644
> --- a/drivers/block/null_blk/null_blk.h
> +++ b/drivers/block/null_blk/null_blk.h
> @@ -133,6 +133,16 @@ struct nullb {
>
> struct nullb_queue *queues;
> unsigned int nr_queues;
> + /*
> + * null_blk request timeout teardown limit when device is in the
> + * stable state, i.e. once this limit is reached issue
> + * null_abort_work() to teardown the device from block lyaer
> + * request timeout callback and cleanup resources such as
> + * memory and pathname.
s/issue/execute
s/lyaer/layer
But I think this can be simplified to something like:
/*
* Number of requests timeout failures allowed before trigerring
* a device teardown from the block layer request timeout callback.
*/
> + */
> + atomic_t rq_abort_count;
> + /* tear down work to be scheduled from block layer request handler */
This comment is not really useful.
> + struct work_struct abort_work;
> char disk_name[DISK_NAME_LEN];
> };
>
--
Damien Le Moal
Western Digital Research
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