Merge tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull bdev flags update from Al Viro:
 "Compactifying bdev flags.

  We can easily have up to 24 flags with sane atomicity, _without_
  pushing anything out of the first cacheline of struct block_device"

* tag 'pull-bd_flags-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  bdev: move ->bd_make_it_fail to ->__bd_flags
  bdev: move ->bd_ro_warned to ->__bd_flags
  bdev: move ->bd_has_subit_bio to ->__bd_flags
  bdev: move ->bd_write_holder into ->__bd_flags
  bdev: move ->bd_read_only to ->__bd_flags
  bdev: infrastructure for flags
  wrapper for access to ->bd_partno
  Use bdev_is_paritition() instead of open-coding it

3 files changed, 33 insertions, 12 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index d88c0a009483..781c4500491b 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -45,10 +45,15 @@ struct block_device {
 	struct request_queue *	bd_queue;
 	struct disk_stats __percpu *bd_stats;
 	unsigned long		bd_stamp;
-	bool			bd_read_only;	/* read-only policy */
-	u8			bd_partno;
-	bool			bd_write_holder;
-	bool			bd_has_submit_bio;
+	atomic_t		__bd_flags;	// partition number + flags
+#define BD_PARTNO		255	// lower 8 bits; assign-once
+#define BD_READ_ONLY		(1u<<8) // read-only policy
+#define BD_WRITE_HOLDER		(1u<<9)
+#define BD_HAS_SUBMIT_BIO	(1u<<10)
+#define BD_RO_WARNED		(1u<<11)
+#ifdef CONFIG_FAIL_MAKE_REQUEST
+#define BD_MAKE_IT_FAIL		(1u<<12)
+#endif
 	dev_t			bd_dev;
 	struct address_space	*bd_mapping;	/* page cache */
 
@@ -65,10 +70,6 @@ struct block_device {
 	struct mutex		bd_fsfreeze_mutex; /* serialize freeze/thaw */
 
 	struct partition_meta_info *bd_meta_info;
-#ifdef CONFIG_FAIL_MAKE_REQUEST
-	bool			bd_make_it_fail;
-#endif
-	bool			bd_ro_warned;
 	int			bd_writers;
 	/*
 	 * keep this out-of-line as it's both big and not needed in the fast
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c78f500c27b0..aefdda9f4ec7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -718,15 +718,35 @@ void invalidate_disk(struct gendisk *disk);
 void set_disk_ro(struct gendisk *disk, bool read_only);
 void disk_uevent(struct gendisk *disk, enum kobject_action action);
 
+static inline u8 bdev_partno(const struct block_device *bdev)
+{
+	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)
 {
-	return disk->part0->bd_read_only ||
+	return bdev_test_flag(disk->part0, BD_READ_ONLY) ||
 		test_bit(GD_READ_ONLY, &disk->state);
 }
 
 static inline int bdev_read_only(struct block_device *bdev)
 {
-	return bdev->bd_read_only || get_disk_ro(bdev->bd_disk);
+	return bdev_test_flag(bdev, BD_READ_ONLY) || get_disk_ro(bdev->bd_disk);
 }
 
 bool set_capacity_and_notify(struct gendisk *disk, sector_t size);
@@ -1086,7 +1106,7 @@ static inline int sb_issue_zeroout(struct super_block *sb, sector_t block,
 
 static inline bool bdev_is_partition(struct block_device *bdev)
 {
-	return bdev->bd_partno;
+	return bdev_partno(bdev) != 0;
 }
 
 enum blk_default_limits {
diff --git a/include/linux/part_stat.h b/include/linux/part_stat.h
index abeba356bc3f..ac8c44dd8237 100644
--- a/include/linux/part_stat.h
+++ b/include/linux/part_stat.h
@@ -59,7 +59,7 @@ static inline void part_stat_set_all(struct block_device *part, int value)
 
 #define part_stat_add(part, field, addnd)	do {			\
 	__part_stat_add((part), field, addnd);				\
-	if ((part)->bd_partno)						\
+	if (bdev_is_partition(part))					\
 		__part_stat_add(bdev_whole(part), field, addnd);	\
 } while (0)