linux-stable.git/drivers/md/raid5.c, branch linux-6.13.y

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

2025-02-08T09:02:20+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/raid5: implement pers->bitmap_sector()

2025-02-08T09:02:19+00:00

commit 9c89f604476cf15c31fbbdb043cff7fbf1dbe0cb upstream.

Bitmap is used for the whole array for raid1/raid10, hence IO for the
array can be used directly for bitmap. However, bitmap is used for
underlying disks for raid5, hence IO for the array can't be used
directly for bitmap.

Implement pers->bitmap_sector() for raid5 to convert IO ranges from the
array to the underlying disks.

Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20250109015145.158868-5-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()

2025-02-08T09:02:19+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()

2025-02-08T09:02:19+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: Wait sync io to finish before changing group cnt

2024-11-07T23:34:52+00:00

One customer reports a bug: raid5 is hung when changing thread cnt
while resync is running. The stripes are all in conf->handle_list
and new threads can't handle them.

Commit b39f35ebe86d ("md: don't quiesce in mddev_suspend()") removes
pers->quiesce from mddev_suspend/resume. Before this patch, mddev_suspend
needs to wait for all ios including sync io to finish. Now it's used
to only wait normal io.

Fix this by calling raid5_quiesce from raid5_store_group_thread_cnt
directly to wait all sync requests to finish before changing the group
cnt.

Fixes: b39f35ebe86d ("md: don't quiesce in mddev_suspend()")
Cc: stable@vger.kernel.org
Signed-off-by: Xiao Ni 
Reviewed-by: Yu Kuai 
Link: https://lore.kernel.org/r/20241106095124.74577-1-xni@redhat.com
Signed-off-by: Song Liu

md/raid5: don't set Faulty rdev for blocked_rdev

2024-11-06T00:08:39+00:00

Faulty rdev should never be accessed anymore, hence there is no point to
wait for bad block to be acknowledged in this case while handling write
request.

Signed-off-by: Yu Kuai 
Tested-by: Mariusz Tkaczyk 
Link: https://lore.kernel.org/r/20241031033114.3845582-8-yukuai1@huaweicloud.com
Signed-off-by: Song Liu

md/raid5: rename wait_for_overlap to wait_for_reshape

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

The only remaining uses of wait_for_overlap are related to reshape so
rename it accordingly.

Signed-off-by: Artur Paszkiewicz 
Link: https://lore.kernel.org/r/20240827153536.6743-4-artur.paszkiewicz@intel.com
Signed-off-by: Song Liu

md/raid5: only add to wq if reshape is in progress

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

Now that actual overlaps are not handled on the wait_for_overlap wq
anymore, the remaining cases when we wait on this wq are limited to
reshape. If reshape is not in progress, don't add to the wq in
raid5_make_request() because add_wait_queue() / remove_wait_queue()
operations take a spinlock and cause noticeable contention when multiple
threads are submitting requests to the mddev.

Signed-off-by: Artur Paszkiewicz 
Link: https://lore.kernel.org/r/20240827153536.6743-3-artur.paszkiewicz@intel.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_resize() into bitmap_operations

2024-08-27T19:43:15+00:00

So that the implementation won't be exposed, and it'll be possible
to invent a new bitmap by replacing bitmap_operations.

Signed-off-by: Yu Kuai 
Link: https://lore.kernel.org/r/20240826074452.1490072-36-yukuai1@huaweicloud.com
Signed-off-by: Song Liu