[PATCH 63/79] block: rnull: add an option to change the number of hardware queues

[Andreas Hindborg]

Add a feature to rnull that allows changing the number of simulated
hardware queues during device operation.

Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxx>
---
 drivers/block/rnull/configfs.rs | 143 +++++++++++++++++++++++++---------------
 drivers/block/rnull/rnull.rs    |  39 +++++++----
 2 files changed, 116 insertions(+), 66 deletions(-)

diff --git a/drivers/block/rnull/configfs.rs b/drivers/block/rnull/configfs.rs
index 816c057f130fc..424722f01ab8d 100644
--- a/drivers/block/rnull/configfs.rs
+++ b/drivers/block/rnull/configfs.rs
@@ -138,7 +138,13 @@ fn make_group(
                     completion_time: time::Delta::ZERO,
                     name: name.try_into()?,
                     memory_backed: false,
-                    submit_queues: 1,
+                    queue_config: Arc::pin_init(
+                        new_mutex!(QueueConfig {
+                            submit_queues: 1,
+                            poll_queues: 0
+                        }),
+                        GFP_KERNEL
+                    )?,
                     home_node: bindings::NUMA_NO_NODE,
                     discard: false,
                     no_sched: false,
@@ -158,7 +164,6 @@ fn make_group(
                     zone_max_open: 0,
                     zone_max_active: 0,
                     zone_append_max_sectors: u32::MAX,
-                    poll_queues: 0,
                     fua: true,
                 }),
             }),
@@ -215,7 +220,7 @@ struct DeviceConfigInner {
     completion_time: time::Delta,
     disk: Option<Arc<GenDisk<NullBlkDevice>>>,
     memory_backed: bool,
-    submit_queues: u32,
+    queue_config: Arc<Mutex<QueueConfig>>,
     home_node: i32,
     discard: bool,
     no_sched: bool,
@@ -235,7 +240,6 @@ struct DeviceConfigInner {
     zone_max_open: u32,
     zone_max_active: u32,
     zone_append_max_sectors: u32,
-    poll_queues: u32,
     fua: bool,
 }
 
@@ -268,7 +272,7 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
                 irq_mode: guard.irq_mode,
                 completion_time: guard.completion_time,
                 memory_backed: guard.memory_backed,
-                submit_queues: guard.submit_queues,
+                queue_config: guard.queue_config.clone(),
                 home_node: guard.home_node,
                 discard: guard.discard,
                 no_sched: guard.no_sched,
@@ -287,7 +291,6 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
                 zone_max_open: guard.zone_max_open,
                 zone_max_active: guard.zone_max_active,
                 zone_append_max_sectors: guard.zone_append_max_sectors,
-                poll_queues: guard.poll_queues,
                 forced_unit_access: guard.fua,
             })?);
             guard.powered = true;
@@ -300,9 +303,17 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
     }
 }
 
-configfs_simple_field!(DeviceConfig, 1,
-                       block_size, u32,
-                       check GenDiskBuilder::<NullBlkDevice>::validate_block_size
+pub(crate) struct QueueConfig {
+    pub(crate) submit_queues: u32,
+    pub(crate) poll_queues: u32,
+}
+
+configfs_simple_field!(
+    DeviceConfig,
+    1,
+    block_size,
+    u32,
+    check GenDiskBuilder::<NullBlkDevice>::validate_block_size
 );
 configfs_simple_bool_field!(DeviceConfig, 2, rotational);
 configfs_simple_field!(DeviceConfig, 3, capacity_mib, u64);
@@ -349,51 +360,57 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
     }
 }
 
-#[vtable]
-impl configfs::AttributeOperations<7> for DeviceConfig {
-    type Data = DeviceConfig;
-
-    fn show(this: &DeviceConfig, page: &mut [u8; PAGE_SIZE]) -> Result<usize> {
-        let mut writer = kernel::str::Formatter::new(page);
-        writer.write_fmt(fmt!("{}\n", this.data.lock().submit_queues))?;
-        Ok(writer.bytes_written())
-    }
+configfs_attribute! {
+    DeviceConfig,
+    7,
+    show: |this, page| show_field(this.data.lock().queue_config.lock().submit_queues, page),
+    store: |this,page| {
+        let config_guard = this.data.lock();
+        let mut queue_config = config_guard.queue_config.lock();
 
-    fn store(this: &DeviceConfig, page: &[u8]) -> Result {
-        if this.data.lock().powered {
-            return Err(EBUSY);
+        let text = core::str::from_utf8(page)?.trim();
+        let value = text.parse().map_err(|_| EINVAL)?;
+        if value > kernel::num_possible_cpus() {
+            return Err(kernel::error::code::EINVAL)
         }
 
-        let text = core::str::from_utf8(page)?.trim();
-        let value = text
-            .parse::<u32>()
-            .map_err(|_| kernel::error::code::EINVAL)?;
+        let old_submit_queues = queue_config.submit_queues;
+        queue_config.submit_queues = value;
+        let total_queue_count = queue_config.submit_queues + queue_config.poll_queues;
+
+        let disk = config_guard.disk.clone();
+
+        drop(queue_config);
+        drop(config_guard);
 
-        if value == 0 || value > kernel::num_possible_cpus() {
-            return Err(kernel::error::code::EINVAL);
+        if let Some(disk) = &disk {
+            if let Err(e) = disk.tag_set().update_hw_queue_count(total_queue_count) {
+                this.data.lock().queue_config.lock().submit_queues = old_submit_queues;
+                return Err(e);
+            }
         }
 
-        this.data.lock().submit_queues = value;
         Ok(())
-    }
+    },
 }
 
 configfs_attribute!(DeviceConfig, 8,
-    show: |this, page| show_field(
-        this.data.lock().submit_queues == kernel::num_online_nodes(), page
-    ),
-    store: |this, page| store_with_power_check(this, page, |this, page| {
-        let value = core::str::from_utf8(page)?
-            .trim()
-            .parse::<u8>()
-            .map_err(|_| kernel::error::code::EINVAL)?
-            != 0;
-
-        if value {
-            this.data.lock().submit_queues *= kernel::num_online_nodes();
-        }
-        Ok(())
-    })
+            show: |this, page| show_field(
+                this.data.lock().queue_config.lock().submit_queues == kernel::num_online_nodes(),
+                page
+            ),
+            store: |this, page| store_with_power_check(this, page, |this, page| {
+                let value = core::str::from_utf8(page)?
+                    .trim()
+                    .parse::<u8>()
+                    .map_err(|_| kernel::error::code::EINVAL)?
+                    != 0;
+
+                if value {
+        this.data.lock().queue_config.lock().submit_queues *= kernel::num_online_nodes();
+                }
+                Ok(())
+            })
 );
 
 configfs_simple_field!(
@@ -518,17 +535,37 @@ fn store(this: &DeviceConfig, page: &[u8]) -> Result {
 configfs_simple_field!(DeviceConfig, 24, zone_max_open, u32);
 configfs_simple_field!(DeviceConfig, 25, zone_max_active, u32);
 configfs_simple_field!(DeviceConfig, 26, zone_append_max_sectors, u32);
-configfs_simple_field!(
+configfs_attribute! {
     DeviceConfig,
     27,
-    poll_queues,
-    u32,
-    check | value | {
+    show: |this, page| show_field(this.data.lock().queue_config.lock().poll_queues, page),
+    store: |this,page| {
+        let config_guard = this.data.lock();
+        let mut queue_config = config_guard.queue_config.lock();
+
+        let text = core::str::from_utf8(page)?.trim();
+        let value = text.parse().map_err(|_| EINVAL)?;
         if value > kernel::num_possible_cpus() {
-            Err(kernel::error::code::EINVAL)
-        } else {
-            Ok(())
+            return Err(kernel::error::code::EINVAL)
         }
-    }
-);
+
+        let old_poll_queues = queue_config.poll_queues;
+        queue_config.poll_queues = value;
+        let total_queue_count = queue_config.submit_queues + queue_config.poll_queues;
+
+        let disk = config_guard.disk.clone();
+
+        drop(queue_config);
+        drop(config_guard);
+
+        if let Some(disk) = &disk {
+            if let Err(e) = disk.tag_set().update_hw_queue_count(total_queue_count) {
+                this.data.lock().queue_config.lock().poll_queues = old_poll_queues;
+                return Err(e);
+            }
+        }
+
+        Ok(())
+    },
+}
 configfs_simple_bool_field!(DeviceConfig, 28, fua);
diff --git a/drivers/block/rnull/rnull.rs b/drivers/block/rnull/rnull.rs
index 3b7edfe7efe44..429819bf042ba 100644
--- a/drivers/block/rnull/rnull.rs
+++ b/drivers/block/rnull/rnull.rs
@@ -10,7 +10,10 @@
 #[cfg(CONFIG_BLK_DEV_ZONED)]
 mod zoned;
 
-use configfs::IRQMode;
+use configfs::{
+    IRQMode,
+    QueueConfig, //
+};
 use disk_storage::{
     DiskStorage,
     NullBlockPage,
@@ -225,6 +228,8 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
                     *module_parameters::submit_queues.value()
                 };
 
+                let poll_queues = *module_parameters::poll_queues.value();
+
                 let block_size = *module_parameters::bs.value();
                 let disk = NullBlkDevice::new(NullBlkOptions {
                     name: &name,
@@ -234,7 +239,13 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
                     irq_mode: (*module_parameters::irqmode.value()).try_into()?,
                     completion_time: Delta::from_nanos(completion_time),
                     memory_backed: *module_parameters::memory_backed.value() != 0,
-                    submit_queues,
+                    queue_config: Arc::pin_init(
+                        new_mutex!(QueueConfig {
+                            submit_queues,
+                            poll_queues
+                        }),
+                        GFP_KERNEL,
+                    )?,
                     home_node: *module_parameters::home_node.value(),
                     discard: *module_parameters::discard.value() != 0,
                     no_sched: *module_parameters::no_sched.value() != 0,
@@ -253,7 +264,6 @@ fn init(_module: &'static ThisModule) -> impl PinInit<Self, Error> {
                     zone_max_open: *module_parameters::zone_max_open.value(),
                     zone_max_active: *module_parameters::zone_max_active.value(),
                     zone_append_max_sectors: *module_parameters::zone_append_max_sectors.value(),
-                    poll_queues: *module_parameters::poll_queues.value(),
                     forced_unit_access: *module_parameters::fua.value() != 0,
                 })?;
                 disks.push(disk, GFP_KERNEL)?;
@@ -277,7 +287,7 @@ struct NullBlkOptions<'a> {
     irq_mode: IRQMode,
     completion_time: Delta,
     memory_backed: bool,
-    submit_queues: u32,
+    queue_config: Arc<Mutex<QueueConfig>>,
     home_node: i32,
     discard: bool,
     no_sched: bool,
@@ -302,7 +312,6 @@ struct NullBlkOptions<'a> {
     zone_max_active: u32,
     #[cfg_attr(not(CONFIG_BLK_DEV_ZONED), expect(unused_variables))]
     zone_append_max_sectors: u32,
-    poll_queues: u32,
     forced_unit_access: bool,
 }
 
@@ -342,7 +351,7 @@ fn new(options: NullBlkOptions<'_>) -> Result<Arc<GenDisk<Self>>> {
             irq_mode,
             completion_time,
             memory_backed,
-            submit_queues,
+            queue_config,
             home_node,
             discard,
             no_sched,
@@ -361,7 +370,6 @@ fn new(options: NullBlkOptions<'_>) -> Result<Arc<GenDisk<Self>>> {
             zone_max_open,
             zone_max_active,
             zone_append_max_sectors,
-            poll_queues,
             forced_unit_access,
         } = options;
 
@@ -379,6 +387,11 @@ fn new(options: NullBlkOptions<'_>) -> Result<Arc<GenDisk<Self>>> {
             return Err(code::EINVAL);
         }
 
+        let queue_config_guard = queue_config.lock();
+        let submit_queues = queue_config_guard.submit_queues;
+        let poll_queues = queue_config_guard.poll_queues;
+        drop(queue_config_guard);
+
         let tagset_ctor = || -> Result<Arc<_>> {
             Arc::pin_init(
                 TagSet::new(
@@ -386,8 +399,7 @@ fn new(options: NullBlkOptions<'_>) -> Result<Arc<GenDisk<Self>>> {
                     KBox::new(
                         NullBlkTagsetData {
                             queue_depth: hw_queue_depth,
-                            submit_queue_count: submit_queues,
-                            poll_queue_count: poll_queues,
+                            queue_config,
                         },
                         GFP_KERNEL,
                     )?,
@@ -773,8 +785,7 @@ impl HasHrTimer<Self> for Pdu {
 
 struct NullBlkTagsetData {
     queue_depth: u32,
-    submit_queue_count: u32,
-    poll_queue_count: u32,
+    queue_config: Arc<Mutex<QueueConfig>>,
 }
 
 #[vtable]
@@ -919,8 +930,10 @@ fn report_zones(
     }
 
     fn map_queues(tag_set: Pin<&mut TagSet<Self>>) {
-        let mut submit_queue_count = tag_set.data().submit_queue_count;
-        let mut poll_queue_count = tag_set.data().poll_queue_count;
+        let queue_config = tag_set.data().queue_config.lock();
+        let mut submit_queue_count = queue_config.submit_queues;
+        let mut poll_queue_count = queue_config.poll_queues;
+        drop(queue_config);
 
         if tag_set.hw_queue_count() != submit_queue_count + poll_queue_count {
             pr_warn!(

-- 
2.51.2