kernel/linux.git/drivers/md/raid5-cache.c, branch v6.18.21

lib/crc32: standardize on crc32c() name for Castagnoli CRC32

2025-02-09T04:06:30+00:00

For historical reasons, the Castagnoli CRC32 is available under 3 names: crc32c(), crc32c_le(), and __crc32c_le(). Most callers use crc32c(). The more verbose versions are not really warranted; there is no "_be" version that the "_le" version needs to be differentiated from, and the leading underscores are pointless. Therefore, let's standardize on just crc32c(). Remove the other two names, and update callers accordingly. Specifically, the new crc32c() comes from what was previously __crc32c_le(), so compared to the old crc32c() it now takes a size_t length rather than unsigned int, and it's now in linux/crc32.h instead of just linux/crc32c.h (which includes linux/crc32.h). Later patches will also rename __crc32c_le_combine(), crc32c_le_base(), and crc32c_le_arch(). Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250208024911.14936-5-ebiggers@kernel.org Signed-off-by: Eric Biggers

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

2025-01-13T16:56:11+00:00

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

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

2025-01-13T16:56:10+00:00

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

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

2025-01-13T16:56:10+00:00

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

md: Replace deprecated kmap_atomic() with kmap_local_page()

2025-01-13T15:36:29+00:00

kmap_atomic() is deprecated and should be replaced with kmap_local_page() [1][2]. kmap_local_page() is faster in kernels with HIGHMEM enabled, can take page faults, and allows preemption. According to [2], this is safe as long as the code between kmap_atomic() and kunmap_atomic() does not implicitly depend on disabling page faults or preemption. It appears to me that none of the call sites in this patch depend on disabling page faults or preemption; they are all mapping a page to simply extract some information from it or print some debug info. [1] https://lwn.net/Articles/836144/ [2] https://docs.kernel.org/mm/highmem.html#temporary-virtual-mappings Signed-off-by: David Reaver Link: https://lore.kernel.org/r/20250108192131.46843-1-me@davidreaver.com Signed-off-by: Song Liu

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