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 <xni@redhat.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20241106095124.74577-1-xni@redhat.com
Signed-off-by: Song Liu <song@kernel.org>

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 <yukuai3@huawei.com>
Tested-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Link: https://lore.kernel.org/r/20241031033114.3845582-8-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

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

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

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 <artur.paszkiewicz@intel.com>
Link: https://lore.kernel.org/r/20240827153536.6743-3-artur.paszkiewicz@intel.com
Signed-off-by: Song Liu <song@kernel.org>

Convert uses of wait_for_overlap wait queue with R5_Overlap bit to
wait_on_bit() / wake_up_bit().

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Link: https://lore.kernel.org/r/20240827153536.6743-2-artur.paszkiewicz@intel.com
Signed-off-by: Song Liu <song@kernel.org>

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 <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-36-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

And move the condition "if (mddev->bitmap)" into md_bitmap_resize() as
well, on the one hand make code cleaner, on the other hand try not to
access bitmap directly.

Since we are here, also change the parameter 'init' from int to bool.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-35-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

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 <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-33-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

Add a parameter 'bool sync' to distinguish them, and
md_bitmap_unplug_async() won't be exported anymore, hence
bitmap_operations only need one op to cover them.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-32-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>

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.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-30-yukuai1@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>