kernel/drivers/md/raid1-10.c, branch linux-6.9.y

md/raid1-10: factor out a new helper raid1_should_read_first()

2024-03-01T06:49:46Z

If resync is in progress, read_balance() should find the first usable disk, otherwise, data could be inconsistent after resync is done. raid1 and raid10 implement the same checking, hence factor out the checking to make code cleaner. Noted that raid1 is using 'mddev->recovery_cp', which is updated after all resync IO is done, while raid10 is using 'conf->next_resync', which is inaccurate because raid10 update it before submitting resync IO. Fortunately, raid10 read IO can't concurrent with resync IO, hence there is no problem. And this patch also switch raid10 to use 'mddev->recovery_cp'. Co-developed-by: Paul Luse Signed-off-by: Paul Luse Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20240229095714.926789-7-yukuai1@huaweicloud.com

md/raid1-10: add a helper raid1_check_read_range()

2024-03-01T06:49:46Z

The checking and handler of bad blocks appear many timers during read_balance() in raid1 and raid10. This helper will be used in later patches to simplify read_balance() a lot. Co-developed-by: Paul Luse Signed-off-by: Paul Luse Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20240229095714.926789-6-yukuai1@huaweicloud.com

md: factor out a helper exceed_read_errors() to check read_errors

2023-12-15T23:22:15Z

Move check_decay_read_errors() to raid1-10.c and factor out a helper exceed_read_errors() to check if read_errors exceeds the limit, so that raid1 can also use it. There are no functional changes. Signed-off-by: Li Nan Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231215023852.3478228-2-linan666@huaweicloud.com

md/raid1-10: fix casting from randomized structure in raid1_submit_write()

2023-06-23T16:33:16Z

Following build error triggered while build with clang version 17.0.0 with W=1(this can't be reporduced with gcc 13.1.0): drivers/md/raid1-10.c:117:25: error: casting from randomized structure pointer type 'struct block_device *' to 'struct md_rdev *' 117 | struct md_rdev *rdev = (struct md_rdev *)bio->bi_bdev; | ^ Fix this by casting 'bio->bi_bdev' to 'void *', as it used to be. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202306142042.fmjfmTF8-lkp@intel.com/ Fixes: 8295efbe68c0 ("md/raid1-10: factor out a helper to submit normal write") Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230616012136.3047071-1-yukuai1@huaweicloud.com

md/raid1-10: limit the number of plugged bio

2023-06-13T22:25:44Z

bio can be added to plug infinitely, and following writeback test can trigger huge amount of plugged bio: Test script: modprobe brd rd_nr=4 rd_size=10485760 mdadm -CR /dev/md0 -l10 -n4 /dev/ram[0123] --assume-clean --bitmap=internal echo 0 > /proc/sys/vm/dirty_background_ratio fio -filename=/dev/md0 -ioengine=libaio -rw=write -bs=4k -numjobs=1 -iodepth=128 -name=test Test result: Monitor /sys/block/md0/inflight will found that inflight keep increasing until fio finish writing, after running for about 2 minutes: [root@fedora ~]# cat /sys/block/md0/inflight 0 4474191 Fix the problem by limiting the number of plugged bio based on the number of copies for original bio. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529131106.2123367-8-yukuai1@huaweicloud.com

md/raid1-10: don't handle pluged bio by daemon thread

2023-06-13T22:25:44Z

current->bio_list will be set under submit_bio() context, in this case bitmap io will be added to the list and wait for current io submission to finish, while current io submission must wait for bitmap io to be done. commit 874807a83139 ("md/raid1{,0}: fix deadlock in bitmap_unplug.") fix the deadlock by handling plugged bio by daemon thread. On the one hand, the deadlock won't exist after commit a214b949d8e3 ("blk-mq: only flush requests from the plug in blk_mq_submit_bio"). On the other hand, current solution makes it impossible to flush plugged bio in raid1/10_make_request(), because this will cause that all the writes will goto daemon thread. In order to limit the number of plugged bio, commit 874807a83139 ("md/raid1{,0}: fix deadlock in bitmap_unplug.") is reverted, and the deadlock is fixed by handling bitmap io asynchronously. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529131106.2123367-7-yukuai1@huaweicloud.com

md/raid1-10: submit write io directly if bitmap is not enabled

2023-06-13T22:25:44Z

Commit 6cce3b23f6f8 ("[PATCH] md: write intent bitmap support for raid10") add bitmap support, and it changed that write io is submitted through daemon thread because bitmap need to be updated before write io. And later, plug is used to fix performance regression because all the write io will go to demon thread, which means io can't be issued concurrently. However, if bitmap is not enabled, the write io should not go to daemon thread in the first place, and plug is not needed as well. Fixes: 6cce3b23f6f8 ("[PATCH] md: write intent bitmap support for raid10") Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529131106.2123367-5-yukuai1@huaweicloud.com

md/raid1-10: factor out a helper to submit normal write

2023-06-13T22:25:43Z

There are multiple places to do the same thing, factor out a helper to prevent redundant code, and the helper will be used in following patch as well. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529131106.2123367-4-yukuai1@huaweicloud.com

md/raid1-10: factor out a helper to add bio to plug

2023-06-13T22:25:43Z

The code in raid1 and raid10 is identical, prepare to limit the number of plugged bios. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20230529131106.2123367-3-yukuai1@huaweicloud.com

md: raid1: check if adding pages to resync bio fails

2023-06-01T15:13:31Z

Check if adding pages to resync bio fails and if bail out. As the comment above suggests this cannot happen, WARN if it actually happens. Technically __bio_add_pages() would be sufficient here, but asserting the pages actually get added to the bio is preferred. This way we can mark bio_add_pages as __must_check. Reviewed-by: Damien Le Moal Acked-by: Song Liu Signed-off-by: Johannes Thumshirn Link: https://lore.kernel.org/r/33aea4c271220dc9bcab58c4b7bec478c1511142.1685532726.git.johannes.thumshirn@wdc.com Signed-off-by: Jens Axboe