From: Andreas Hindborg <a.hindborg@kernel.org>
To: "Boqun Feng" <boqun.feng@gmail.com>,
"Jens Axboe" <axboe@kernel.dk>, "Miguel Ojeda" <ojeda@kernel.org>,
"Gary Guo" <gary@garyguo.net>,
"Björn Roy Baron" <bjorn3_gh@protonmail.com>,
"Benno Lossin" <lossin@kernel.org>,
"Alice Ryhl" <aliceryhl@google.com>,
"Trevor Gross" <tmgross@umich.edu>,
"Danilo Krummrich" <dakr@kernel.org>,
"FUJITA Tomonori" <fujita.tomonori@gmail.com>,
"Frederic Weisbecker" <frederic@kernel.org>,
"Lyude Paul" <lyude@redhat.com>,
"Thomas Gleixner" <tglx@kernel.org>,
"Anna-Maria Behnsen" <anna-maria@linutronix.de>,
"John Stultz" <jstultz@google.com>,
"Stephen Boyd" <sboyd@kernel.org>,
"Lorenzo Stoakes" <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: linux-block@vger.kernel.org, rust-for-linux@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andreas Hindborg <a.hindborg@kernel.org>
Subject: [PATCH 20/79] block: rnull: add discard support
Date: Mon, 16 Feb 2026 00:35:07 +0100 [thread overview]
Message-ID: <20260216-rnull-v6-19-rc5-send-v1-20-de9a7af4b469@kernel.org> (raw)
In-Reply-To: <20260216-rnull-v6-19-rc5-send-v1-0-de9a7af4b469@kernel.org>
Add support for discard operations to the rnull block driver:
- Add discard module parameter and configfs attribute.
- Set max_hw_discard_sectors when discard is enabled.
- Add sector occupancy tracking.
- Add discard handling that frees sectors and removes empty pages.
- Discard operations require memory backing to function.
The discard feature uses a bitmap to track which sectors in each page are
occupied, allowing cleanup of pages when they are empty.
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
---
drivers/block/rnull/configfs.rs | 15 ++++++
drivers/block/rnull/rnull.rs | 115 +++++++++++++++++++++++++++++++++++-----
2 files changed, 116 insertions(+), 14 deletions(-)
diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs
index fe00617d2b679..4ec9be440105d 100644
--- a/drivers/block/rnull/configfs.rs
+++ b/drivers/block/rnull/configfs.rs
@@ -94,6 +94,7 @@ fn make_group(
submit_queues: 7,
use_per_node_hctx: 8,
home_node: 9,
+ discard: 10,
],
};
@@ -114,6 +115,7 @@ fn make_group(
memory_backed: false,
submit_queues: 1,
home_node: bindings::NUMA_NO_NODE,
+ discard: false,
}),
}),
core::iter::empty(),
@@ -171,6 +173,7 @@ struct DeviceConfigInner {
memory_backed: bool,
submit_queues: u32,
home_node: i32,
+ discard: bool,
}
#[vtable]
@@ -204,6 +207,7 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
memory_backed: guard.memory_backed,
submit_queues: guard.submit_queues,
home_node: guard.home_node,
+ discard: guard.discard,
})?);
guard.powered = true;
} else if guard.powered && !power_op {
@@ -321,3 +325,14 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
}
}
);
+
+configfs_attribute!(DeviceConfig, 10,
+ show: |this, page| show_field(this.data.lock().discard, page),
+ store: |this, page| store_with_power_check(this, page, |this, page| {
+ if !this.data.lock().memory_backed {
+ return Err(EINVAL);
+ }
+ this.data.lock().discard = kstrtobool_bytes(page)?;
+ Ok(())
+ })
+);
diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs
index fb3ce272d5bec..d1fb5fbc0c0be 100644
--- a/drivers/block/rnull/rnull.rs
+++ b/drivers/block/rnull/rnull.rs
@@ -19,14 +19,19 @@
Operations,
TagSet, //
},
+ SECTOR_MASK, SECTOR_SHIFT,
},
error::{
code,
Result, //
},
+ ffi,
new_mutex,
new_xarray,
- page::SafePage,
+ page::{
+ SafePage, //
+ PAGE_SIZE,
+ },
pr_info,
prelude::*,
str::CString,
@@ -102,6 +107,11 @@
default: -1,
description: "Home node for the device. Default: -1 (no node)",
},
+ discard: u8 {
+ default: 0,
+ description:
+ "Support discard operations (requires memory-backed null_blk device). Default: false",
+ },
},
}
@@ -139,6 +149,7 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
memory_backed: *module_parameters::memory_backed.value() != 0,
submit_queues,
home_node: *module_parameters::home_node.value(),
+ discard: *module_parameters::discard.value() != 0,
})?;
disks.push(disk, GFP_KERNEL)?;
}
@@ -163,6 +174,7 @@ struct NullBlkOptions<'a> {
memory_backed: bool,
submit_queues: u32,
home_node: i32,
+ discard: bool,
}
struct NullBlkDevice;
@@ -178,6 +190,7 @@ fn new(options: NullBlkOptions<'_>) -> Result<GenDisk<Self>> {
memory_backed,
submit_queues,
home_node,
+ discard,
} = options;
let flags = if memory_backed {
@@ -201,22 +214,30 @@ fn new(options: NullBlkOptions<'_>) -> Result<GenDisk<Self>> {
irq_mode,
completion_time,
memory_backed,
+ block_size: block_size as usize,
}),
GFP_KERNEL,
)?;
- gen_disk::GenDiskBuilder::new()
+ let mut builder = gen_disk::GenDiskBuilder::new()
.capacity_sectors(capacity_mib << (20 - block::SECTOR_SHIFT))
.logical_block_size(block_size)?
.physical_block_size(block_size)?
- .rotational(rotational)
- .build(fmt!("{}", name.to_str()?), tagset, queue_data)
+ .rotational(rotational);
+
+ if memory_backed && discard {
+ builder = builder
+ // Max IO size is u32::MAX bytes
+ .max_hw_discard_sectors(ffi::c_uint::MAX >> block::SECTOR_SHIFT);
+ }
+
+ builder.build(fmt!("{}", name.to_str()?), tagset, queue_data)
}
#[inline(always)]
fn write(tree: &Tree, mut sector: usize, mut segment: Segment<'_>) -> Result {
while !segment.is_empty() {
- let page = SafePage::alloc_page(GFP_NOIO)?;
+ let page = NullBlockPage::new()?;
let mut tree = tree.lock();
let page_idx = sector >> block::PAGE_SECTORS_SHIFT;
@@ -228,8 +249,10 @@ fn write(tree: &Tree, mut sector: usize, mut segment: Segment<'_>) -> Result {
tree.get_mut(page_idx).unwrap()
};
+ page.set_occupied(sector);
let page_offset = (sector & block::SECTOR_MASK as usize) << block::SECTOR_SHIFT;
- sector += segment.copy_to_page(page, page_offset) >> block::SECTOR_SHIFT;
+ sector +=
+ segment.copy_to_page(page.page.get_pin_mut(), page_offset) >> block::SECTOR_SHIFT;
}
Ok(())
}
@@ -243,7 +266,7 @@ fn read(tree: &Tree, mut sector: usize, mut segment: Segment<'_>) -> Result {
if let Some(page) = tree.get(idx) {
let page_offset = (sector & block::SECTOR_MASK as usize) << block::SECTOR_SHIFT;
- sector += segment.copy_from_page(page, page_offset) >> block::SECTOR_SHIFT;
+ sector += segment.copy_from_page(&page.page, page_offset) >> block::SECTOR_SHIFT;
} else {
sector += segment.zero_page() >> block::SECTOR_SHIFT;
}
@@ -252,6 +275,32 @@ fn read(tree: &Tree, mut sector: usize, mut segment: Segment<'_>) -> Result {
Ok(())
}
+ fn discard(tree: &Tree, mut sector: usize, sectors: usize, block_size: usize) -> Result {
+ let mut remaining_bytes = sectors << SECTOR_SHIFT;
+ let mut tree = tree.lock();
+
+ while remaining_bytes > 0 {
+ let page_idx = sector >> block::PAGE_SECTORS_SHIFT;
+ let mut remove = false;
+ if let Some(page) = tree.get_mut(page_idx) {
+ page.set_free(sector);
+ if page.is_empty() {
+ remove = true;
+ }
+ }
+
+ if remove {
+ drop(tree.remove(page_idx))
+ }
+
+ let processed = remaining_bytes.min(block_size);
+ sector += processed >> SECTOR_SHIFT;
+ remaining_bytes -= processed;
+ }
+
+ Ok(())
+ }
+
#[inline(never)]
fn transfer(
command: bindings::req_op,
@@ -268,7 +317,40 @@ fn transfer(
}
}
-type TreeNode = Owned<SafePage>;
+const _CHEKC_STATUS_WIDTH: () = build_assert!((PAGE_SIZE >> SECTOR_SHIFT) <= 64);
+
+struct NullBlockPage {
+ page: Owned<SafePage>,
+ status: u64,
+}
+
+impl NullBlockPage {
+ fn new() -> Result<KBox<Self>> {
+ Ok(KBox::new(
+ Self {
+ page: SafePage::alloc_page(GFP_NOIO | __GFP_ZERO)?,
+ status: 0,
+ },
+ GFP_NOIO,
+ )?)
+ }
+
+ fn set_occupied(&mut self, sector: usize) {
+ let idx = sector & SECTOR_MASK as usize;
+ self.status |= 1 << idx;
+ }
+
+ fn set_free(&mut self, sector: usize) {
+ let idx = sector & SECTOR_MASK as usize;
+ self.status &= !(1 << idx);
+ }
+
+ fn is_empty(&self) -> bool {
+ self.status == 0
+ }
+}
+
+type TreeNode = KBox<NullBlockPage>;
type Tree = XArray<TreeNode>;
#[pin_data]
@@ -278,6 +360,7 @@ struct QueueData {
irq_mode: IRQMode,
completion_time: Delta,
memory_backed: bool,
+ block_size: usize,
}
#[pin_data]
@@ -327,12 +410,16 @@ fn queue_rq(
let command = rq.command();
let mut sector = rq.sector();
- for bio in rq.bio_iter_mut() {
- let segment_iter = bio.segment_iter();
- for segment in segment_iter {
- let length = segment.len();
- Self::transfer(command, tree, sector, segment)?;
- sector += length as usize >> block::SECTOR_SHIFT;
+ if command == bindings::req_op_REQ_OP_DISCARD {
+ Self::discard(tree, sector, rq.sectors(), queue_data.block_size)?;
+ } else {
+ for bio in rq.bio_iter_mut() {
+ let segment_iter = bio.segment_iter();
+ for segment in segment_iter {
+ let length = segment.len();
+ Self::transfer(command, tree, sector, segment)?;
+ sector += length as usize >> block::SECTOR_SHIFT;
+ }
}
}
}
--
2.51.2
next prev parent reply other threads:[~2026-02-16 0:50 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-15 23:34 [PATCH 00/79] block: rnull: complete the rust null block driver Andreas Hindborg
2026-02-15 23:34 ` [PATCH 01/79] block: rnull: adopt new formatting guidelines Andreas Hindborg
2026-02-15 23:34 ` [PATCH 02/79] block: rnull: add module parameters Andreas Hindborg
2026-02-15 23:34 ` [PATCH 03/79] block: rnull: add macros to define configfs attributes Andreas Hindborg
2026-02-15 23:34 ` [PATCH 04/79] block: rust: fix generation of bindings to `BLK_STS_.*` Andreas Hindborg
2026-02-15 23:34 ` [PATCH 05/79] block: rust: change `queue_rq` request type to `Owned` Andreas Hindborg
2026-02-15 23:34 ` [PATCH 06/79] block: rust: add `Request` private data support Andreas Hindborg
2026-02-15 23:34 ` [PATCH 07/79] block: rust: allow `hrtimer::Timer` in `RequestData` Andreas Hindborg
2026-02-15 23:34 ` [PATCH 08/79] block: rnull: add timer completion mode Andreas Hindborg
2026-02-15 23:34 ` [PATCH 09/79] block: rust: introduce `kernel::block::bio` module Andreas Hindborg
2026-02-15 23:34 ` [PATCH 10/79] block: rust: add `command` getter to `Request` Andreas Hindborg
2026-02-15 23:34 ` [PATCH 11/79] block: rust: mq: use GFP_KERNEL from prelude Andreas Hindborg
2026-02-15 23:34 ` [PATCH 12/79] block: rust: add `TagSet` flags Andreas Hindborg
2026-02-15 23:35 ` [PATCH 13/79] block: rnull: add memory backing Andreas Hindborg
2026-02-15 23:35 ` [PATCH 14/79] block: rnull: add submit queue count config option Andreas Hindborg
2026-02-15 23:35 ` [PATCH 15/79] block: rnull: add `use_per_node_hctx` " Andreas Hindborg
2026-02-15 23:35 ` [PATCH 16/79] block: rust: allow specifying home node when constructing `TagSet` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 17/79] block: rnull: allow specifying the home numa node Andreas Hindborg
2026-02-15 23:35 ` [PATCH 18/79] block: rust: add Request::sectors() method Andreas Hindborg
2026-02-15 23:35 ` [PATCH 19/79] block: rust: mq: add max_hw_discard_sectors support to GenDiskBuilder Andreas Hindborg
2026-02-15 23:35 ` Andreas Hindborg [this message]
2026-02-15 23:35 ` [PATCH 21/79] block: rust: add `NoDefaultScheduler` flag for `TagSet` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 22/79] block: rnull: add no_sched module parameter and configfs attribute Andreas Hindborg
2026-02-15 23:35 ` [PATCH 23/79] block: rust: change sector type from usize to u64 Andreas Hindborg
2026-02-15 23:35 ` [PATCH 24/79] block: rust: add `BadBlocks` for bad block tracking Andreas Hindborg
2026-02-15 23:35 ` [PATCH 25/79] block: rust: mq: add Request::end() method for custom status codes Andreas Hindborg
2026-02-15 23:35 ` [PATCH 26/79] block: rnull: add badblocks support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 27/79] block: rnull: add badblocks_once support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 28/79] block: rnull: add partial I/O support for bad blocks Andreas Hindborg
2026-02-15 23:35 ` [PATCH 29/79] block: rust: add `TagSet` private data support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 30/79] block: rust: add `hctx` " Andreas Hindborg
2026-02-15 23:35 ` [PATCH 31/79] block: rnull: add volatile cache emulation Andreas Hindborg
2026-02-15 23:35 ` [PATCH 32/79] block: rust: implement `Sync` for `GenDisk` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 33/79] block: rust: add a back reference feature to `GenDisk` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 34/79] block: rust: introduce an idle type state for `Request` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 35/79] block: rust: add a request queue abstraction Andreas Hindborg
2026-02-15 23:35 ` [PATCH 36/79] block: rust: add a method to get the request queue for a request Andreas Hindborg
2026-02-15 23:35 ` [PATCH 37/79] block: rust: introduce `kernel::block::error` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 38/79] block: rust: require `queue_rq` to return a `BlkResult` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 39/79] block: rust: add `GenDisk::queue_data` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 40/79] block: rnull: add bandwidth limiting Andreas Hindborg
2026-02-15 23:35 ` [PATCH 41/79] block: rnull: add blocking queue mode Andreas Hindborg
2026-02-15 23:35 ` [PATCH 42/79] block: rnull: add shared tags Andreas Hindborg
2026-02-15 23:35 ` [PATCH 43/79] block: rnull: add queue depth config option Andreas Hindborg
2026-02-15 23:35 ` [PATCH 44/79] block: rust: add an abstraction for `bindings::req_op` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 45/79] block: rust: add a method to set the target sector of a request Andreas Hindborg
2026-02-15 23:35 ` [PATCH 46/79] block: rust: move gendisk vtable construction to separate function Andreas Hindborg
2026-02-15 23:35 ` [PATCH 47/79] block: rust: add zoned block device support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 48/79] block: rnull: add zoned storage support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 49/79] block: rust: add `map_queues` support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 50/79] block: rust: add an abstraction for `struct blk_mq_queue_map` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 51/79] block: rust: add polled completion support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 52/79] block: rust: add accessors to `TagSet` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 53/79] block: rnull: add polled completion support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 54/79] block: rnull: add REQ_OP_FLUSH support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 55/79] block: rust: add request flags abstraction Andreas Hindborg
2026-02-15 23:35 ` [PATCH 56/79] block: rust: add abstraction for block queue feature flags Andreas Hindborg
2026-02-15 23:35 ` [PATCH 57/79] block: rust: allow setting write cache and FUA flags for `GenDisk` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 58/79] block: rust: add `Segment::copy_to_page_limit` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 59/79] block: rnull: add fua support Andreas Hindborg
2026-02-15 23:35 ` [PATCH 60/79] block: fix arg type in `blk_mq_update_nr_hw_queues` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 61/79] block: rust: add `GenDisk::tag_set` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 62/79] block: rust: add `TagSet::update_hw_queue_count` Andreas Hindborg
2026-02-16 23:59 ` Ken Kurematsu
2026-02-17 9:54 ` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 63/79] block: rnull: add an option to change the number of hardware queues Andreas Hindborg
2026-02-15 23:35 ` [PATCH 64/79] block: rust: add an abstraction for `struct rq_list` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 65/79] block: rust: add `queue_rqs` vtable hook Andreas Hindborg
2026-02-15 23:35 ` [PATCH 66/79] block: rnull: support queue_rqs Andreas Hindborg
2026-02-15 23:35 ` [PATCH 67/79] block: rust: remove the `is_poll` parameter from `queue_rq` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 68/79] block: rust: add a debug assert for refcounts Andreas Hindborg
2026-02-15 23:35 ` [PATCH 69/79] block: rust: add `TagSet::tag_to_rq` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 70/79] block: rust: add `Request::queue_index` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 71/79] block: rust: add `Request::requeue` Andreas Hindborg
2026-02-15 23:35 ` [PATCH 72/79] block: rust: add `request_timeout` hook Andreas Hindborg
2026-02-15 23:36 ` [PATCH 73/79] block: rnull: add fault injection support Andreas Hindborg
2026-02-15 23:36 ` [PATCH 74/79] block: rust: add max_sectors option to `GenDiskBuilder` Andreas Hindborg
2026-02-15 23:36 ` [PATCH 75/79] block: rnull: allow configuration of the maximum IO size Andreas Hindborg
2026-02-15 23:36 ` [PATCH 76/79] block: rust: add `virt_boundary_mask` option to `GenDiskBuilder` Andreas Hindborg
2026-02-15 23:36 ` [PATCH 77/79] block: rnull: add `virt_boundary` option Andreas Hindborg
2026-02-15 23:36 ` [PATCH 78/79] block: rnull: add `shared_tag_bitmap` config option Andreas Hindborg
2026-02-15 23:36 ` [PATCH 79/79] block: rnull: add zone offline and readonly configfs files Andreas Hindborg
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