kernel/linux.git/drivers/md/raid5-cache.c, branch v6.12.80

md/md-bitmap: move bitmap_{start, end}write to md upper layer

2025-02-08T08:58:12+00:00

commit cd5fc653381811f1e0ba65f5d169918cab61476f upstream. There are two BUG reports that raid5 will hang at bitmap_startwrite([1],[2]), root cause is that bitmap start write and end write is unbalanced, it's not quite clear where, and while reviewing raid5 code, it's found that bitmap operations can be optimized. For example, for a 4 disks raid5, with chunksize=8k, if user issue a IO (0 + 48k) to the array: ┌────────────────────────────────────────────────────────────┐ │chunk 0 │ │ ┌────────────┬─────────────┬─────────────┬────────────┼ │ sh0 │A0: 0 + 4k │A1: 8k + 4k │A2: 16k + 4k │A3: P │ │ ┼────────────┼─────────────┼─────────────┼────────────┼ │ sh1 │B0: 4k + 4k │B1: 12k + 4k │B2: 20k + 4k │B3: P │ ┼──────┴────────────┴─────────────┴─────────────┴────────────┼ │chunk 1 │ │ ┌────────────┬─────────────┬─────────────┬────────────┤ │ sh2 │C0: 24k + 4k│C1: 32k + 4k │C2: P │C3: 40k + 4k│ │ ┼────────────┼─────────────┼─────────────┼────────────┼ │ sh3 │D0: 28k + 4k│D1: 36k + 4k │D2: P │D3: 44k + 4k│ └──────┴────────────┴─────────────┴─────────────┴────────────┘ Before this patch, 4 stripe head will be used, and each sh will attach bio for 3 disks, and each attached bio will trigger bitmap_startwrite() once, which means total 12 times. - 3 times (0 + 4k), for (A0, A1 and A2) - 3 times (4 + 4k), for (B0, B1 and B2) - 3 times (8 + 4k), for (C0, C1 and C3) - 3 times (12 + 4k), for (D0, D1 and D3) After this patch, md upper layer will calculate that IO range (0 + 48k) is corresponding to the bitmap (0 + 16k), and call bitmap_startwrite() just once. Noted that this patch will align bitmap ranges to the chunks, for example, if user issue a IO (0 + 4k) to array: - Before this patch, 1 time (0 + 4k), for A0; - After this patch, 1 time (0 + 8k) for chunk 0; Usually, one bitmap bit will represent more than one disk chunk, and this doesn't have any difference. And even if user really created a array that one chunk contain multiple bits, the overhead is that more data will be recovered after power failure. Also remove STRIPE_BITMAP_PENDING since it's not used anymore. [1] https://lore.kernel.org/all/CAJpMwyjmHQLvm6zg1cmQErttNNQPDAAXPKM3xgTjMhbfts986Q@mail.gmail.com/ [2] https://lore.kernel.org/all/ADF7D720-5764-4AF3-B68E-1845988737AA@flyingcircus.io/ Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20250109015145.158868-6-yukuai1@huaweicloud.com Signed-off-by: Song Liu Signed-off-by: Yu Kuai Signed-off-by: Greg Kroah-Hartman

md/md-bitmap: remove the last parameter for bimtap_ops->endwrite()

2025-02-08T08:58:11+00:00

commit 4f0e7d0e03b7b80af84759a9e7cfb0f81ac4adae upstream. For the case that IO failed for one rdev, the bit will be mark as NEEDED in following cases: 1) If badblocks is set and rdev is not faulty; 2) If rdev is faulty; Case 1) is useless because synchronize data to badblocks make no sense. Case 2) can be replaced with mddev->degraded. Also remove R1BIO_Degraded, R10BIO_Degraded and STRIPE_DEGRADED since case 2) no longer use them. Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20250109015145.158868-3-yukuai1@huaweicloud.com Signed-off-by: Song Liu Signed-off-by: Yu Kuai Signed-off-by: Greg Kroah-Hartman

md/md-bitmap: factor behind write counters out from bitmap_{start/end}write()

2025-02-08T08:58:11+00:00

commit 08c50142a128dcb2d7060aa3b4c5db8837f7a46a upstream. behind_write is only used in raid1, prepare to refactor bitmap_{start/end}write(), there are no functional changes. Signed-off-by: Yu Kuai Reviewed-by: Xiao Ni Link: https://lore.kernel.org/r/20250109015145.158868-2-yukuai1@huaweicloud.com Signed-off-by: Song Liu Signed-off-by: Yu Kuai Signed-off-by: Greg Kroah-Hartman

md/raid5: use wait_on_bit() for R5_Overlap

2024-08-29T16:37:10+00:00

Convert uses of wait_for_overlap wait queue with R5_Overlap bit to wait_on_bit() / wake_up_bit(). Signed-off-by: Artur Paszkiewicz Link: https://lore.kernel.org/r/20240827153536.6743-2-artur.paszkiewicz@intel.com Signed-off-by: Song Liu

md/md-bitmap: merge md_bitmap_endwrite() into bitmap_operations

2024-08-27T17:14:17+00:00

So that the implementation won't be exposed, and it'll be possible to invent a new bitmap by replacing bitmap_operations. Also change the parameter from bitmap to mddev, to avoid access bitmap outside md-bitmap.c as much as possible. And change the type of 'success' and 'behind' from int to bool. Signed-off-by: Yu Kuai Link: https://lore.kernel.org/r/20240826074452.1490072-25-yukuai1@huaweicloud.com Signed-off-by: Song Liu

md/raid5: remove rcu protection to access rdev from conf

2023-11-27T23:49:05+00:00

Because it's safe to accees rdev from conf: - If any spinlock is held, because synchronize_rcu() from md_kick_rdev_from_array() will prevent 'rdev' to be freed until spinlock is released; - If 'reconfig_lock' is held, because rdev can't be added or removed from array; - If there is normal IO inflight, because mddev_suspend() will prevent rdev to be added or removed from array; - If there is sync IO inflight, because 'MD_RECOVERY_RUNNING' is checked in remove_and_add_spares(). And these will cover all the scenarios in raid456. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231125081604.3939938-5-yukuai1@huaweicloud.com

md: rename __mddev_suspend/resume() back to mddev_suspend/resume()

2023-10-11T01:49:51+00:00

Now that the old apis are removed, __mddev_suspend/resume() can be renamed to their original names. This is done by: sed -i "s/__mddev_suspend/mddev_suspend/g" *.[ch] sed -i "s/__mddev_resume/mddev_resume/g" *.[ch] Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231010151958.145896-20-yukuai1@huaweicloud.com

md/raid5-cache: use new apis to suspend array

2023-10-11T01:49:50+00:00

Convert to use new apis, the old apis will be removed eventually. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231010151958.145896-9-yukuai1@huaweicloud.com

md/raid5-cache: use READ_ONCE/WRITE_ONCE for 'conf->log'

2023-10-11T01:49:49+00:00

'conf->log' is set with 'reconfig_mutex' grabbed, however, readers are not procted, hence protect it with READ_ONCE/WRITE_ONCE to prevent reading abnormal values. Signed-off-by: Yu Kuai Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20231010151958.145896-3-yukuai1@huaweicloud.com

md/raid5-cache: fix null-ptr-deref for r5l_flush_stripe_to_raid()

2023-08-15T16:40:27+00:00

r5l_flush_stripe_to_raid() will check if the list 'flushing_ios' is empty, and then submit 'flush_bio', however, r5l_log_flush_endio() is clearing the list first and then clear the bio, which will cause null-ptr-deref: T1: submit flush io raid5d handle_active_stripes r5l_flush_stripe_to_raid // list is empty // add 'io_end_ios' to the list bio_init submit_bio // io1 T2: io1 is done r5l_log_flush_endio list_splice_tail_init // clear the list T3: submit new flush io ... r5l_flush_stripe_to_raid // list is empty // add 'io_end_ios' to the list bio_init bio_uninit // clear bio->bi_blkg submit_bio // null-ptr-deref Fix this problem by clearing bio before clearing the list in r5l_log_flush_endio(). Fixes: 0dd00cba99c3 ("raid5-cache: fully initialize flush_bio when needed") Reported-and-tested-by: Corey Hickey Closes: https://lore.kernel.org/all/cddd7213-3dfd-4ab7-a3ac-edd54d74a626@fatooh.org/ Signed-off-by: Yu Kuai Reviewed-by: Christoph Hellwig Signed-off-by: Song Liu