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0193e3966c
linux/drivers/md
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Wu Bo 0193e3966c dm verity: don't perform FEC for failed readahead IO 
We found an issue under Android OTA scenario that many BIOs have to do
FEC where the data under dm-verity is 100% complete and no corruption.

Android OTA has many dm-block layers, from upper to lower:
dm-verity
dm-snapshot
dm-origin & dm-cow
dm-linear
ufs

DM tables have to change 2 times during Android OTA merging process.
When doing table change, the dm-snapshot will be suspended for a while.
During this interval, many readahead IOs are submitted to dm_verity
from filesystem. Then the kverity works are busy doing FEC process
which cost too much time to finish dm-verity IO. This causes needless
delay which feels like system is hung.

After adding debugging it was found that each readahead IO needed
around 10s to finish when this situation occurred. This is due to IO
amplification:

dm-snapshot suspend
erofs_readahead     // 300+ io is submitted
	dm_submit_bio (dm_verity)
		dm_submit_bio (dm_snapshot)
		bio return EIO
		bio got nothing, it's empty
	verity_end_io
	verity_verify_io
	forloop range(0, io->n_blocks)    // each io->nblocks ~= 20
		verity_fec_decode
		fec_decode_rsb
		fec_read_bufs
		forloop range(0, v->fec->rsn) // v->fec->rsn = 253
			new_read
			submit_bio (dm_snapshot)
		end loop
	end loop
dm-snapshot resume

Readahead BIOs get nothing while dm-snapshot is suspended, so all of
them will cause verity's FEC.
Each readahead BIO needs to verify ~20 (io->nblocks) blocks.
Each block needs to do FEC, and every block needs to do 253
(v->fec->rsn) reads.
So during the suspend interval(~200ms), 300 readahead BIOs trigger
~1518000 (300*20*253) IOs to dm-snapshot.

As readahead IO is not required by userspace, and to fix this issue,
it is best to pass readahead errors to upper layer to handle it.

Cc: stable@vger.kernel.org
Fixes: a739ff3f54 ("dm verity: add support for forward error correction")
Signed-off-by: Wu Bo <bo.wu@vivo.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
2023-11-29 12:55:31 -05:00
..
bcache bcache: avoid NULL checking to c->root in run_cache_set() 2023-11-20 09:17:51 -07:00
persistent-data dm thin metadata: Fix ABBA deadlock by resetting dm_bufio_client 2023-06-16 18:24:13 -04:00
dm-audit.c dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-audit.h dm: introduce audit event module for device mapper 2021-10-27 16:53:47 -04:00
dm-bio-prison-v1.c dm: Annotate struct dm_bio_prison with __counted_by 2023-10-02 09:48:53 -07:00
dm-bio-prison-v1.h dm bio prison v1: add dm_cell_key_has_valid_range 2023-03-30 15:57:51 -04:00
dm-bio-prison-v2.c dm: address space issues relative to switch/while/for/... 2023-02-14 14:23:06 -05:00
dm-bio-prison-v2.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-bio-record.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-bufio.c dm-bufio: fix no-sleep mode 2023-11-17 14:41:14 -05:00
dm-builtin.c dm: adjust EXPORT_SYMBOL() to follow functions immediately 2023-02-14 14:23:07 -05:00
dm-cache-background-tracker.c dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-cache-background-tracker.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-cache-block-types.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-cache-metadata.c Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
dm-cache-metadata.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-cache-policy-internal.h dm: add missing empty lines 2023-02-14 14:23:06 -05:00
dm-cache-policy-smq.c dm cache policy smq: ensure IO doesn't prevent cleaner policy progress 2023-07-25 11:55:50 -04:00
dm-cache-policy.c dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-cache-policy.h dm: address indent/space issues 2023-02-14 14:23:06 -05:00
dm-cache-target.c block: replace fmode_t with a block-specific type for block open flags 2023-06-12 08:04:05 -06:00
dm-clone-metadata.c
dm-clone-metadata.h
dm-clone-target.c block: replace fmode_t with a block-specific type for block open flags 2023-06-12 08:04:05 -06:00
dm-core.h dm: fix a race condition in retrieve_deps 2023-09-14 11:18:29 -04:00
dm-crypt.c dm-crypt: start allocating with MAX_ORDER 2023-11-17 14:41:15 -05:00
dm-delay.c dm-delay: avoid duplicate logic 2023-11-17 14:41:14 -05:00
dm-dust.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-ebs-target.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-era-target.c block: replace fmode_t with a block-specific type for block open flags 2023-06-12 08:04:05 -06:00
dm-exception-store.c dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-exception-store.h dm: avoid spaces before function arguments or in favour of tabs 2023-02-14 14:23:06 -05:00
dm-flakey.c dm flakey: introduce random_read_corrupt and random_write_corrupt options 2023-06-16 18:24:13 -04:00
dm-ima.c dm: avoid inline filenames 2023-02-14 14:23:07 -05:00
dm-ima.h dm: avoid inline filenames 2023-02-14 14:23:07 -05:00
dm-init.c dm: open code dm_get_dev_t in dm_init_init 2023-06-05 10:57:40 -06:00
dm-integrity.c dm integrity: use crypto_shash_digest() in sb_mac() 2023-10-31 11:06:21 -04:00
dm-io-rewind.c dm: avoid void function return statements 2023-02-14 14:23:07 -05:00
dm-io-tracker.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-io.c dm: remove unnecessary (void*) conversions 2023-04-11 12:01:01 -04:00
dm-ioctl.c dm ioctl: replace deprecated strncpy with strscpy_pad 2023-10-23 13:02:37 -04:00
dm-kcopyd.c dm: remove unnecessary (void*) conversions 2023-04-11 12:01:01 -04:00
dm-linear.c dm: shortcut the calls to linear_map and stripe_map 2023-10-06 19:09:25 -04:00
dm-log-userspace-base.c dm log userspace: replace deprecated strncpy with strscpy 2023-10-23 13:02:48 -04:00
dm-log-userspace-transfer.c dm: avoid split of quoted strings where possible 2023-02-14 14:23:07 -05:00
dm-log-userspace-transfer.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-log-writes.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-log.c dm: remove unnecessary (void*) conversions 2023-04-11 12:01:01 -04:00
dm-mpath.c dm: push error reporting down to dm_register_target() 2023-04-11 12:01:01 -04:00
dm-mpath.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-path-selector.c dm: adjust EXPORT_SYMBOL() to follow functions immediately 2023-02-14 14:23:07 -05:00
dm-path-selector.h dm: avoid spaces before function arguments or in favour of tabs 2023-02-14 14:23:06 -05:00
dm-ps-historical-service-time.c dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-ps-io-affinity.c dm: address space issues relative to switch/while/for/... 2023-02-14 14:23:06 -05:00
dm-ps-queue-length.c dm: avoid spaces before function arguments or in favour of tabs 2023-02-14 14:23:06 -05:00
dm-ps-round-robin.c dm: correct block comments format. 2023-02-14 14:23:06 -05:00
dm-ps-service-time.c dm: avoid spaces before function arguments or in favour of tabs 2023-02-14 14:23:06 -05:00
dm-raid1.c dm: remove unnecessary (void*) conversions 2023-04-11 12:01:01 -04:00
dm-raid.c for-6.7/block-2023-10-30 2023-11-01 12:30:07 -10:00
dm-region-hash.c dm: correct block comments format. 2023-02-14 14:23:06 -05:00
dm-rq.c dm: avoid using symbolic permissions 2023-02-14 14:23:07 -05:00
dm-rq.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-snap-persistent.c dm: remove unnecessary (void*) conversions 2023-04-11 12:01:01 -04:00
dm-snap-transient.c dm: avoid split of quoted strings where possible 2023-02-14 14:23:07 -05:00
dm-snap.c block: replace fmode_t with a block-specific type for block open flags 2023-06-12 08:04:05 -06:00
dm-stats.c dm: Annotate struct dm_stat with __counted_by 2023-10-02 09:48:52 -07:00
dm-stats.h dm stats: check for and propagate alloc_percpu failure 2023-03-16 13:37:06 -04:00
dm-stripe.c - Update DM core to directly call the map function for both the linear 2023-11-01 12:55:54 -10:00
dm-switch.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-sysfs.c dm sysfs: make kobj_type structure constant 2023-02-14 14:23:08 -05:00
dm-table.c dm error: Add support for zoned block devices 2023-10-31 11:06:21 -04:00
dm-target.c dm error: Add support for zoned block devices 2023-10-31 11:06:21 -04:00
dm-thin-metadata.c - Update DM crypt to allocate compound pages if possible. 2023-06-30 12:16:00 -07:00
dm-thin-metadata.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-thin.c - Update DM crypt to allocate compound pages if possible. 2023-06-30 12:16:00 -07:00
dm-uevent.c dm: avoid spaces before function arguments or in favour of tabs 2023-02-14 14:23:06 -05:00
dm-uevent.h dm: fix undue/missing spaces 2023-02-14 14:23:06 -05:00
dm-unstripe.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-verity-fec.c dm-verity: don't use blocking calls from tasklets 2023-11-17 14:41:14 -05:00
dm-verity-fec.h dm: change "unsigned" to "unsigned int" 2023-02-14 14:23:06 -05:00
dm-verity-loadpin.c dm: verity-loadpin: Add NULL pointer check for 'bdev' parameter 2023-06-28 10:43:04 -07:00
dm-verity-target.c dm verity: don't perform FEC for failed readahead IO 2023-11-29 12:55:31 -05:00
dm-verity-verify-sig.c dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-verity-verify-sig.h dm: add missing SPDX-License-Indentifiers 2023-02-14 14:23:06 -05:00
dm-verity.h dm-verity: don't use blocking calls from tasklets 2023-11-17 14:41:14 -05:00
dm-writecache.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-zero.c dm: add helper macro for simple DM target module init and exit 2023-04-11 12:09:08 -04:00
dm-zone.c dm zone: Use the bitmap API to allocate bitmaps 2023-06-16 18:24:13 -04:00
dm-zoned-metadata.c dm zoned: dynamically allocate the dm-zoned-meta shrinker 2023-10-04 10:32:25 -07:00
dm-zoned-reclaim.c
dm-zoned-target.c dm zoned: free dmz->ddev array in dmz_put_zoned_devices 2023-09-20 13:48:06 -04:00
dm-zoned.h dm/dm-zoned: Use the enum req_op type 2022-07-14 12:14:31 -06:00
dm.c - Update DM core to directly call the map function for both the linear 2023-11-01 12:55:54 -10:00
dm.h dm: shortcut the calls to linear_map and stripe_map 2023-10-06 19:09:25 -04:00
Kconfig fs: add CONFIG_BUFFER_HEAD 2023-08-02 09:13:09 -06:00
Makefile hardening updates for v5.20-rc1 2022-08-02 14:38:59 -07:00
md-autodetect.c md: use new apis to suspend array before mddev_create/destroy_serial_pool 2023-10-10 18:49:50 -07:00
md-bitmap.c md: cleanup mddev_create/destroy_serial_pool() 2023-10-10 18:49:51 -07:00
md-bitmap.h md-bitmap: don't use ->index for pages backing the bitmap file 2023-07-27 00:13:29 -07:00
md-cluster.c md-cluster: check for timeout while a new disk adding 2023-10-12 09:16:19 -07:00
md-cluster.h
md-faulty.c md/md-faulty: enable io accounting 2023-07-27 00:13:30 -07:00
md-linear.c md/md-linear: cleanup linear_add() 2023-10-10 18:49:51 -07:00
md-linear.h md/md-linear: Annotate struct linear_conf with __counted_by 2023-09-22 11:23:01 -07:00
md-multipath.c md/md-multipath: enable io accounting 2023-07-27 00:13:29 -07:00
md-multipath.h
md.c md: fix bi_status reporting in md_end_clone_io 2023-11-19 20:51:25 -08:00
md.h for-6.7/block-2023-10-30 2023-11-01 12:30:07 -10:00
raid0.c md: raid0: account for split bio in iostat accounting 2023-08-17 21:11:31 -07:00
raid0.h md/raid0: add discard support for the 'original' layout 2023-06-30 15:43:50 -07:00
raid1-10.c md/raid1-10: fix casting from randomized structure in raid1_submit_write() 2023-06-23 09:33:16 -07:00
raid1.c md/raid1: don't split discard io for write behind 2023-10-09 16:32:02 -07:00
raid1.h md/raid1: switch to use md_account_bio() for io accounting 2023-07-27 00:13:29 -07:00
raid5-cache.c md: rename __mddev_suspend/resume() back to mddev_suspend/resume() 2023-10-10 18:49:51 -07:00
raid5-log.h md/raid5-ppl: Drop unused argument from ppl_handle_flush_request() 2022-08-02 17:14:31 -06:00
raid5-ppl.c md: raid5: use __bio_add_page to add single page to new bio 2023-05-31 09:50:02 -06:00
raid5.c Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
raid5.h md/raid5: dynamically allocate the md-raid5 shrinker 2023-10-04 10:32:25 -07:00
raid10.c md: initialize 'writes_pending' while allocating mddev 2023-09-22 10:28:26 -07:00
raid10.h md/raid10: switch to use md_account_bio() for io accounting 2023-07-27 00:13:29 -07:00