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bdev: infrastructure for flags

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Replace bd_partno with a 32bit field (__bd_flags).  The lower 8 bits
contain the partition number, the upper 24 are for flags.

Helpers: bdev_{test,set,clear}_flag(bdev, flag), with atomic_or()
and atomic_andnot() used to set/clear.

NOTE: this commit does not actually move any flags over there - they
are still bool fields.  As the result, it shifts the fields wrt
cacheline boundaries; that's going to be restored once the first
3 flags are dealt with.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2024-04-12 01:07:29 -04:00
parent b8c873edbf
commit 1116b9fa15
3 changed files with 19 additions and 3 deletions
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2
block/bdev.c
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@ -411,7 +411,7 @@ struct block_device *bdev_alloc(struct gendisk *disk, u8 partno)
mutex_init(&bdev->bd_fsfreeze_mutex);
spin_lock_init(&bdev->bd_size_lock);
mutex_init(&bdev->bd_holder_lock);
bdev->bd_partno = partno;
atomic_set(&bdev->__bd_flags, partno);
bdev->bd_inode = inode;
bdev->bd_queue = disk->queue;
if (partno)

3
include/linux/blk_types.h
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@ -45,8 +45,9 @@ struct block_device {
struct request_queue * bd_queue;
struct disk_stats __percpu *bd_stats;
unsigned long bd_stamp;
atomic_t __bd_flags; // partition number + flags
#define BD_PARTNO 255 // lower 8 bits; assign-once
bool bd_read_only; /* read-only policy */
u8 bd_partno;
bool bd_write_holder;
bool bd_has_submit_bio;
dev_t bd_dev;

17
include/linux/blkdev.h
View File

@ -722,7 +722,22 @@ void disk_uevent(struct gendisk *disk, enum kobject_action action);
static inline u8 bdev_partno(const struct block_device *bdev)
{
return bdev->bd_partno;
return atomic_read(&bdev->__bd_flags) & BD_PARTNO;
}
static inline bool bdev_test_flag(const struct block_device *bdev, unsigned flag)
{
return atomic_read(&bdev->__bd_flags) & flag;
}
static inline void bdev_set_flag(struct block_device *bdev, unsigned flag)
{
atomic_or(flag, &bdev->__bd_flags);
}
static inline void bdev_clear_flag(struct block_device *bdev, unsigned flag)
{
atomic_andnot(flag, &bdev->__bd_flags);
}
static inline int get_disk_ro(struct gendisk *disk)