block: assign caller-specific lockdep class to disk->open_mutex

block/blk-mq.c

@@ -4459,7 +4459,7 @@ EXPORT_SYMBOL(blk_mq_destroy_queue);
 
 struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
 		struct queue_limits *lim, void *queuedata,
-		struct lock_class_key *lkclass)
+		struct gendisk_lkclass *lkclass)
 {
 	struct request_queue *q;
 	struct gendisk *disk;
@@ -4480,7 +4480,7 @@ struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
 EXPORT_SYMBOL(__blk_mq_alloc_disk);
 
 struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
-		struct lock_class_key *lkclass)
+		struct gendisk_lkclass *lkclass)
 {
 	struct gendisk *disk;
 

block/blk.h

@@ -642,7 +642,7 @@ void drop_partition(struct block_device *part);
 void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors);
 
 struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
-		struct lock_class_key *lkclass);
+		struct gendisk_lkclass *lkclass);
 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id);
 
 int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode);

block/genhd.c

@@ -1444,7 +1444,7 @@ dev_t part_devt(struct gendisk *disk, u8 partno)
 }
 
 struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
-		struct lock_class_key *lkclass)
+		struct gendisk_lkclass *lkclass)
 {
 	struct gendisk *disk;
 
@@ -1467,7 +1467,7 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
 		goto out_free_bdi;
 
 	disk->node_id = node_id;
-	mutex_init(&disk->open_mutex);
+	mutex_init_with_key(&disk->open_mutex, &lkclass->open_mutex_lkclass);
 	xa_init(&disk->part_tbl);
 	if (xa_insert(&disk->part_tbl, 0, disk->part0, GFP_KERNEL))
 		goto out_destroy_part_tbl;
@@ -1482,7 +1482,7 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
 	device_initialize(disk_to_dev(disk));
 	inc_diskseq(disk);
 	q->disk = disk;
-	lockdep_init_map(&disk->lockdep_map, "(bio completion)", lkclass, 0);
+	lockdep_init_map(&disk->lockdep_map, "(bio completion)", &lkclass->bio_lkclass, 0);
 #ifdef CONFIG_BLOCK_HOLDER_DEPRECATED
 	INIT_LIST_HEAD(&disk->slave_bdevs);
 #endif
@@ -1510,7 +1510,7 @@ struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id,
 }
 
 struct gendisk *__blk_alloc_disk(struct queue_limits *lim, int node,
-		struct lock_class_key *lkclass)
+		struct gendisk_lkclass *lkclass)
 {
 	struct queue_limits default_lim = { };
 	struct request_queue *q;

drivers/block/rnull/rnull.rs

@@ -61,7 +61,7 @@ impl NullBlkDevice {
             .logical_block_size(block_size)?
             .physical_block_size(block_size)?
             .rotational(rotational)
-            .build(fmt!("{}", name.to_str()?), tagset, queue_data)
+            .build(fmt!("{}", name.to_str()?), tagset, queue_data, kernel::my_gendisk_lkclass!())
     }
 }
 

drivers/scsi/sd.c

@@ -112,7 +112,7 @@ static DEFINE_MUTEX(sd_mutex_lock);
 static mempool_t *sd_page_pool;
 static mempool_t *sd_large_page_pool;
 static atomic_t sd_large_page_pool_users = ATOMIC_INIT(0);
-static struct lock_class_key sd_bio_compl_lkclass;
+static struct gendisk_lkclass sd_bio_compl_lkclass;
 
 static const char *sd_cache_types[] = {
 	"write through", "none", "write back",

drivers/scsi/sr.c

@@ -106,7 +106,7 @@ static struct scsi_driver sr_template = {
 static unsigned long sr_index_bits[SR_DISKS / BITS_PER_LONG];
 static DEFINE_SPINLOCK(sr_index_lock);
 
-static struct lock_class_key sr_bio_compl_lkclass;
+static struct gendisk_lkclass sr_bio_compl_lkclass;
 
 static int sr_open(struct cdrom_device_info *, int);
 static void sr_release(struct cdrom_device_info *);

include/linux/blk-mq.h

@@ -726,15 +726,15 @@ enum {
 
 struct gendisk *__blk_mq_alloc_disk(struct blk_mq_tag_set *set,
 		struct queue_limits *lim, void *queuedata,
-		struct lock_class_key *lkclass);
+		struct gendisk_lkclass *lkclass);
 #define blk_mq_alloc_disk(set, lim, queuedata)				\
 ({									\
-	static struct lock_class_key __key;				\
+	static struct gendisk_lkclass __key;				\
 									\
 	__blk_mq_alloc_disk(set, lim, queuedata, &__key);		\
 })
 struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
-		struct lock_class_key *lkclass);
+		struct gendisk_lkclass *lkclass);
 struct request_queue *blk_mq_alloc_queue(struct blk_mq_tag_set *set,
 		struct queue_limits *lim, void *queuedata);
 int blk_mq_init_allocated_queue(struct blk_mq_tag_set *set,

include/linux/blkdev.h

@@ -49,6 +49,11 @@ extern const struct device_type disk_type;
 extern const struct device_type part_type;
 extern const struct class block_class;
 
+struct gendisk_lkclass {
+	struct lock_class_key bio_lkclass;
+	struct lock_class_key open_mutex_lkclass;
+};
+
 /*
  * Maximum number of blkcg policies allowed to be registered concurrently.
  * Defined here to simplify include dependency.
@@ -980,7 +985,7 @@ int bdev_disk_changed(struct gendisk *disk, bool invalidate);
 
 void put_disk(struct gendisk *disk);
 struct gendisk *__blk_alloc_disk(struct queue_limits *lim, int node,
-		struct lock_class_key *lkclass);
+		struct gendisk_lkclass *lkclass);
 
 /**
  * blk_alloc_disk - allocate a gendisk structure
@@ -996,7 +1001,7 @@ struct gendisk *__blk_alloc_disk(struct queue_limits *lim, int node,
  */
 #define blk_alloc_disk(lim, node_id)					\
 ({									\
-	static struct lock_class_key __key;				\
+	static struct gendisk_lkclass __key;				\
 									\
 	__blk_alloc_disk(lim, node_id, &__key);				\
 })

rust/kernel/block/mq.rs

@@ -88,7 +88,7 @@
 //!     Arc::pin_init(TagSet::new(1, 256, 1), flags::GFP_KERNEL)?;
 //! let mut disk = gen_disk::GenDiskBuilder::new()
 //!     .capacity_sectors(4096)
-//!     .build(fmt!("myblk"), tagset, ())?;
+//!     .build(fmt!("myblk"), tagset, (), kernel::my_gendisk_lkclass!())?;
 //!
 //! # Ok::<(), kernel::error::Error>(())
 //! ```

rust/kernel/block/mq/gen_disk.rs

@@ -11,7 +11,6 @@ use crate::{
     error::{self, from_err_ptr, Result},
     fmt::{self, Write},
     prelude::*,
-    static_lock_class,
     str::NullTerminatedFormatter,
     sync::Arc,
     types::{ForeignOwnable, ScopeGuard},
@@ -38,6 +37,43 @@ impl Default for GenDiskBuilder {
     }
 }
 
+/// A wrapper type for safely passing "struct gendisk_lkclass" argument.
+///
+/// This type can only be instantiated via the [`my_gendisk_lkclass!`] macro.
+pub struct GenDiskLockClass(pub(crate) *mut bindings::gendisk_lkclass);
+
+impl GenDiskLockClass {
+    /// Retrieve the underlying raw pointer.
+    pub(crate) fn as_ptr(&self) -> *mut bindings::gendisk_lkclass {
+        self.0
+    }
+}
+
+#[doc(hidden)]
+pub mod __internal {
+    use super::*;
+
+    /// Internal constructor used ONLY by the `my_gendisk_lkclass!` macro.
+    ///
+    /// SAFETY: `ptr` must point to a valid static `gendisk_lkclass` instance.
+    pub const unsafe fn new_lock_class(ptr: *mut bindings::gendisk_lkclass) -> GenDiskLockClass {
+        GenDiskLockClass(ptr)
+    }
+}
+
+/// Helper macro to generate a unique caller-local static lock class struct
+#[macro_export]
+macro_rules! my_gendisk_lkclass {
+    () => {{
+        static mut LKCLASS: $crate::bindings::gendisk_lkclass = $crate::bindings::gendisk_lkclass {
+            bio_lkclass: const { unsafe { ::core::mem::zeroed() } },
+            open_mutex_lkclass: const { unsafe { ::core::mem::zeroed() } },
+        };
+
+        unsafe { $crate::block::mq::gen_disk::__internal::new_lock_class(&raw mut LKCLASS) }
+    }};
+}
+
 impl GenDiskBuilder {
     /// Create a new instance.
     pub fn new() -> Self {
@@ -100,6 +136,7 @@ impl GenDiskBuilder {
         name: fmt::Arguments<'_>,
         tagset: Arc<TagSet<T>>,
         queue_data: T::QueueData,
+        lkclass: GenDiskLockClass,
     ) -> Result<GenDisk<T>> {
         let data = queue_data.into_foreign();
         let recover_data = ScopeGuard::new(|| {
@@ -121,7 +158,7 @@ impl GenDiskBuilder {
                 tagset.raw_tag_set(),
                 &mut lim,
                 data,
-                static_lock_class!().as_ptr(),
+                lkclass.as_ptr(),
             )
         })?;