From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1E57B4EA37F; Tue, 9 Jun 2026 19:13:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781032386; cv=none; b=iD01UGiYjlGamaIIQFVV93EE9tS4WR/008Gk2QDEgAEFaXu5eIfWR1dFy5tvHWVUk18nqePQkpO0K9AMSLLVcw50+XXX55sYujHFSKiEtO1y4eWpUuTCfnJv58LvdXd5HSo3/oYIyAv7ZgccU6C59KZy4IQ8eTfare+Byc6mOnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781032386; c=relaxed/simple; bh=OyYo3h9FH7tddSUSU2yGqcG1rcOMZa8+hV0gLvVXT30=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=djSVfR2YmnToY8L5g2oFUucOu/aT/ToAO9PNv9fpOjB5EdhhiBqfBZlg8PAeOAYX9DflXaXfioRCUEU4r5BcQZ1e2RIvK8YYhHEec+PeM1TXjFNNQ7bt4jIDArMzrLFwerAqffjNpSWKtbfs5yG0HJlWwt4OfdoyROo+dWlqsJk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TFpYDTDB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TFpYDTDB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA1051F00898; Tue, 9 Jun 2026 19:12:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781032384; bh=JnD8AYBlSFJHV8ifo4XwIzlj5eOON9Q0z1EH0iWmsCE=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=TFpYDTDBuIAzpa+0TjHG5dMSItuqqqLZhFGeQ34qoDBgGbY2MoHw2glhTaoX81oCm 9z0VXjifWppnmUn0b/0WnuVlIJ/msxO6TdXR2BXu0PffY8j17xDH0BLMyNEONtfaa5 0b0MveTNIZzwhgPjhPSz024RZcIvQd7gj+d/h3U7rX+T2oT+TRUe6R9PPvaDucAlo3 dhgUYoDWmMPr6lEelcLBQi9AtCdCLExLm7X/WjKemb0TbVpLy6lOWzE9nDibDxjxrJ rKsjZGaDcoo4HrDKmvyXeaniKekTP9LHlqPsMQ7A5+RAgenOJURmR0Y/El9KRA68M3 nSA6T58L5V6UA== From: Andreas Hindborg Date: Tue, 09 Jun 2026 21:08:25 +0200 Subject: [PATCH v2 46/83] block: rnull: add shared tags Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260609-rnull-v6-19-rc5-send-v2-46-82c7404542e2@kernel.org> References: <20260609-rnull-v6-19-rc5-send-v2-0-82c7404542e2@kernel.org> In-Reply-To: <20260609-rnull-v6-19-rc5-send-v2-0-82c7404542e2@kernel.org> To: "Liam R. Howlett" , Alice Ryhl , Anna-Maria Behnsen , Benno Lossin , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Boqun Feng , Danilo Krummrich , FUJITA Tomonori , Frederic Weisbecker , Gary Guo , Jens Axboe , John Stultz , Lorenzo Stoakes , Lyude Paul , Miguel Ojeda , Stephen Boyd , Thomas Gleixner , Trevor Gross , "Liam R. Howlett" , Boqun Feng , Lorenzo Stoakes Cc: Andreas Hindborg , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rust-for-linux@vger.kernel.org X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=13841; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=OyYo3h9FH7tddSUSU2yGqcG1rcOMZa8+hV0gLvVXT30=; b=owEBbQKS/ZANAwAKAfpQKQiqxb3QAcsmYgBqKGTeznS9taKg4dSs5gVp6USJA2+jTJFwZidH4 aBNBag7rUaJAjMEAAEKAB0WIQRXitnI2WZ2JirAaob6UCkIqsW90AUCaihk3gAKCRD6UCkIqsW9 0HtxEACstjqG92HymGqbWHGNy9sEvKNUzNlbVl7NQKWv5rxeAIN2/U3xOvzo9HHjRbXBbQrz3Hq /ygvkPv1e/v6mOOFMSHLLL3rwlfgGXZ1JSZykGsCYNc+ggl6+cGbuOetVXEt4E0LHzqNLBi1/IY 4E3qoazdTGvD7Ms4eycgZ/Q9WpPM1SzmnGZz6iucfO0/zumZhVEWty6ofpwVDXWA2pMjJNFymCx lVC7/sgmJfQzvMMLAskuJwCBQ57FncfWBQKlyUT8TWJdmtQCVjyNFRH0D/pafBn7M0nYTwi217H z45FxqGkhzSe0AOZJgfmWf4yE3DgJ95LqlxaG3pXKulcf7m2L9LehCoEfOKVVF0Wvb55/pAiPu1 ofTBQ2sJKjf8pNdm8/R3UVcO44WJDbll32vo6/h4tIpH/P4STXAW/SnZPN23Q2T4M945He/g21E d1hK4m6b4ljc6hjIh92kokd0Xn2nVnajcqZpNhCxSG98at29luZcwruLAag6M2KtV+1uimnIKP2 mAiMahiFIBKe+4ZW9KIKuScsxOkaQ6nwg6XckyaCxi16iIC6CJ7HQ7Ix5xu/ndi9o/2pcp5kc4+ JS4G2uI7K7ZdKlm2BQq93oxC4S2WvjB28W1v9h8A0C+6Mlafa8QUaVhUF4EOvUXAWSg2+xy7v/7 GS9TiRF96HEb1pg== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 Add support for sharing tags between multiple rnull devices. When enabled via the `shared_tags` configfs attribute, all devices in the group share a single tag set, reducing memory usage. This feature requires creating a shared `TagSet` that can be referenced by multiple devices. Signed-off-by: Andreas Hindborg --- drivers/block/rnull/configfs.rs | 44 +++++++++---- drivers/block/rnull/rnull.rs | 136 +++++++++++++++++++++++++--------------- rust/kernel/block/mq/tag_set.rs | 18 ++++++ 3 files changed, 136 insertions(+), 62 deletions(-) diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs index 5e6bcf9d31d8..a84854e7c358 100644 --- a/drivers/block/rnull/configfs.rs +++ b/drivers/block/rnull/configfs.rs @@ -10,9 +10,12 @@ bindings, block::{ badblocks::BadBlocks, - mq::gen_disk::{ - GenDisk, - GenDiskBuilder, // + mq::{ + gen_disk::{ + GenDisk, + GenDiskBuilder, // + }, + TagSet, // }, // }, configfs::{ @@ -45,7 +48,9 @@ mod macros; -pub(crate) fn subsystem() -> impl PinInit, Error> { +pub(crate) fn subsystem( + shared_tag_set: Arc>, +) -> impl PinInit, Error> { let item_type = configfs_attrs! { container: configfs::Subsystem, data: Config, @@ -55,11 +60,17 @@ pub(crate) fn subsystem() -> impl PinInit, E ], }; - kernel::configfs::Subsystem::new(c"rnull", item_type, try_pin_init!(Config {})) + kernel::configfs::Subsystem::new( + c"rnull", + item_type, + try_pin_init!(Config { shared_tag_set }), + ) } #[pin_data] -pub(crate) struct Config {} +pub(crate) struct Config { + shared_tag_set: Arc>, +} #[vtable] impl AttributeOperations<0> for Config { @@ -69,7 +80,7 @@ impl AttributeOperations<0> for Config { let mut writer = kernel::str::Formatter::new(page); writer.write_str( "blocksize,size,rotational,irqmode,completion_nsec,memory_backed,\ - submit_queues,use_per_node_hctx,discard,blocking\n", + submit_queues,use_per_node_hctx,discard,blocking,shared_tags\n", )?; Ok(writer.bytes_written()) } @@ -106,6 +117,7 @@ fn make_group( cache_size_mib: 15, mbps: 16, blocking: 17, + shared_tags: 18, ], }; @@ -139,6 +151,8 @@ fn make_group( cache_size_mib: 0, mbps: 0, blocking: false, + shared_tags: false, + shared_tag_set: self.shared_tag_set.clone(), }), }), core::iter::empty(), @@ -215,6 +229,8 @@ struct DeviceConfigInner { disk_storage: Arc, mbps: u32, blocking: bool, + shared_tags: bool, + shared_tag_set: Arc>, } #[vtable] @@ -245,17 +261,20 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result { capacity_mib: guard.capacity_mib, irq_mode: guard.irq_mode, completion_time: guard.completion_time, - memory_backed: guard.memory_backed, - submit_queues: guard.submit_queues, - home_node: guard.home_node, discard: guard.discard, - no_sched: guard.no_sched, bad_blocks: guard.bad_blocks.clone(), bad_blocks_once: guard.bad_blocks_once, bad_blocks_partial_io: guard.bad_blocks_partial_io, storage: guard.disk_storage.clone(), bandwidth_limit: u64::from(guard.mbps) * 2u64.pow(20), - blocking: guard.blocking, + shared_tag_set: guard.shared_tags.then(|| guard.shared_tag_set.clone()), + tag_set: crate::TagSetOptions { + submit_queues: guard.submit_queues, + home_node: guard.home_node, + blocking: guard.blocking, + memory_backed: guard.memory_backed, + no_sched: guard.no_sched, + }, })?); guard.powered = true; } else if guard.powered && !power_op { @@ -427,3 +446,4 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result { configfs_simple_field!(DeviceConfig, 16, mbps, u32); configfs_simple_bool_field!(DeviceConfig, 17, blocking); +configfs_simple_bool_field!(DeviceConfig, 18, shared_tags); diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs index 181fce551a91..bcf6a85f1cbc 100644 --- a/drivers/block/rnull/rnull.rs +++ b/drivers/block/rnull/rnull.rs @@ -143,6 +143,10 @@ default: false, description: "Register as a blocking blk-mq driver device", }, + shared_tags: bool { + default: false, + description: "Share tag set between devices for blk-mq", + }, }, } @@ -158,19 +162,30 @@ impl kernel::InPlaceModule for NullBlkModule { fn init(_module: &'static ThisModule) -> impl PinInit { pr_info!("Rust null_blk loaded\n"); - let mut disks = KVec::new(); + pin_init::pin_init_scope(move || -> Result<_, Error> { + let submit_queues = if module_parameters::use_per_node_hctx.value() { + kernel::numa::num_online_nodes() + } else { + module_parameters::submit_queues.value() + }; + let home_node = module_parameters::home_node.value(); + let blocking = module_parameters::blocking.value(); + let memory_backed = module_parameters::memory_backed.value(); + let no_sched = module_parameters::no_sched.value(); + + let shared_tag_set = NullBlkDevice::build_tag_set(TagSetOptions { + submit_queues, + home_node, + blocking, + memory_backed, + no_sched, + })?; - let defer_init = move || -> Result<_, Error> { + let mut disks = KVec::new(); let completion_time: i64 = module_parameters::completion_nsec.value().try_into()?; for i in 0..module_parameters::nr_devices.value() { let name = CString::try_from_fmt(fmt!("rnullb{}", i))?; - let submit_queues = if module_parameters::use_per_node_hctx.value() { - kernel::numa::num_online_nodes() - } else { - module_parameters::submit_queues.value() - }; - let block_size = module_parameters::bs.value(); let disk = NullBlkDevice::new(NullBlkOptions { name: &name, @@ -179,27 +194,30 @@ fn init(_module: &'static ThisModule) -> impl PinInit { capacity_mib: module_parameters::gb.value() * 1024, irq_mode: module_parameters::irqmode.value().try_into()?, completion_time: Delta::from_nanos(completion_time), - memory_backed: module_parameters::memory_backed.value(), - submit_queues, - home_node: module_parameters::home_node.value(), discard: module_parameters::discard.value(), - no_sched: module_parameters::no_sched.value(), bad_blocks: Arc::pin_init(BadBlocks::new(false), GFP_KERNEL)?, bad_blocks_once: false, bad_blocks_partial_io: false, storage: Arc::pin_init(DiskStorage::new(0, block_size as usize), GFP_KERNEL)?, bandwidth_limit: u64::from(module_parameters::mbps.value()) * 2u64.pow(20), - blocking: module_parameters::blocking.value(), + shared_tag_set: module_parameters::shared_tags + .value() + .then(|| shared_tag_set.clone()), + tag_set: TagSetOptions { + submit_queues, + home_node, + blocking, + memory_backed, + no_sched, + }, })?; disks.push(disk, GFP_KERNEL)?; } - Ok(disks) - }; - - try_pin_init!(Self { - configfs_subsystem <- configfs::subsystem(), - param_disks <- new_mutex!(defer_init()?), + Ok(try_pin_init!(Self { + configfs_subsystem <- configfs::subsystem(shared_tag_set), + param_disks <- new_mutex!(disks), + })) }) } } @@ -211,17 +229,14 @@ struct NullBlkOptions<'a> { capacity_mib: u64, irq_mode: IRQMode, completion_time: Delta, - memory_backed: bool, - submit_queues: u32, - home_node: i32, discard: bool, - no_sched: bool, bad_blocks: Arc, bad_blocks_once: bool, bad_blocks_partial_io: bool, storage: Arc, bandwidth_limit: u64, - blocking: bool, + shared_tag_set: Option>>, + tag_set: TagSetOptions, } #[pin_data] @@ -243,9 +258,50 @@ struct NullBlkDevice { disk: SetOnce>>>, } +struct TagSetOptions { + submit_queues: u32, + home_node: i32, + blocking: bool, + memory_backed: bool, + no_sched: bool, +} + impl NullBlkDevice { const BANDWIDTH_TIMER_INTERVAL: Delta = Delta::from_millis(20); + fn build_tag_set(options: TagSetOptions) -> Result>> { + let TagSetOptions { + submit_queues, + home_node, + blocking, + memory_backed, + no_sched, + } = options; + + if home_node > kernel::numa::num_online_nodes().try_into()? { + return Err(code::EINVAL); + } + + let numa_node = if home_node == -1 { + kernel::alloc::NumaNode::NO_NODE + } else { + kernel::alloc::NumaNode::new(home_node)? + }; + + let mut flags = mq::tag_set::Flags::default(); + if blocking || memory_backed { + flags |= mq::tag_set::Flag::Blocking; + } + if no_sched { + flags |= mq::tag_set::Flag::NoDefaultScheduler; + } + + Arc::pin_init( + TagSet::new(submit_queues, (), 256, 1, numa_node, flags), + GFP_KERNEL, + ) + } + fn new(options: NullBlkOptions<'_>) -> Result>> { let NullBlkOptions { name, @@ -254,37 +310,22 @@ fn new(options: NullBlkOptions<'_>) -> Result>> { capacity_mib, irq_mode, completion_time, - memory_backed, - submit_queues, - home_node, discard, - no_sched, bad_blocks, bad_blocks_once, bad_blocks_partial_io, storage, bandwidth_limit, - blocking, + shared_tag_set, + tag_set, } = options; - let mut flags = mq::tag_set::Flags::default(); + let memory_backed = tag_set.memory_backed; - if blocking || memory_backed { - flags |= mq::tag_set::Flag::Blocking; - } - - if no_sched { - flags |= mq::tag_set::Flag::NoDefaultScheduler; - } - - if home_node > kernel::numa::num_online_nodes().try_into()? { - return Err(code::EINVAL); - } - - let numa_node = if home_node == -1 { - kernel::alloc::NumaNode::NO_NODE + let tagset = if let Some(shared) = shared_tag_set { + shared } else { - kernel::alloc::NumaNode::new(home_node)? + Self::build_tag_set(tag_set)? }; let capacity_sectors = capacity_mib << (20 - block::SECTOR_SHIFT); @@ -294,11 +335,6 @@ fn new(options: NullBlkOptions<'_>) -> Result>> { return Err(code::EINVAL); } - let tagset = Arc::pin_init( - TagSet::new(submit_queues, (), 256, 1, numa_node, flags), - GFP_KERNEL, - )?; - let queue_data = Arc::try_pin_init( try_pin_init!(Self { storage, diff --git a/rust/kernel/block/mq/tag_set.rs b/rust/kernel/block/mq/tag_set.rs index bfb8f8af4ee1..5359e60fb5a5 100644 --- a/rust/kernel/block/mq/tag_set.rs +++ b/rust/kernel/block/mq/tag_set.rs @@ -124,3 +124,21 @@ fn drop(self: Pin<&mut Self>) { unsafe { T::TagSetData::from_foreign(tagset_data) }; } } + +// SAFETY: It is safe to share references to `TagSet` across thread boundaries as long as +// `TagSetData` is `Sync`. +unsafe impl Sync for TagSet +where + T: Operations, + T::TagSetData: Sync, +{ +} + +// SAFETY: It is safe to transfer ownership of `TagSet` across thread boundaries if the associated +// private data is `Send` (it will be dropped with the `TagSet`). +unsafe impl Send for TagSet +where + T: Operations, + T::TagSetData: Send, +{ +} -- 2.51.2