block: renumber and rename the cache disabled flag

Start with the first bit, and drop the plural-S from the name.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20240619154623.450048-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/blk-sysfs.c

@@ -429,7 +429,7 @@ static ssize_t queue_io_timeout_store(struct request_queue *q, const char *page,
 
 static ssize_t queue_wc_show(struct request_queue *q, char *page)
 {
-	if (q->limits.features & BLK_FLAGS_WRITE_CACHE_DISABLED)
+	if (q->limits.features & BLK_FLAG_WRITE_CACHE_DISABLED)
 		return sprintf(page, "write through\n");
 	return sprintf(page, "write back\n");
 }
@@ -452,9 +452,9 @@ static ssize_t queue_wc_store(struct request_queue *q, const char *page,
 
 	lim = queue_limits_start_update(q);
 	if (disable)
-		lim.flags |= BLK_FLAGS_WRITE_CACHE_DISABLED;
+		lim.flags |= BLK_FLAG_WRITE_CACHE_DISABLED;
 	else
-		lim.flags &= ~BLK_FLAGS_WRITE_CACHE_DISABLED;
+		lim.flags &= ~BLK_FLAG_WRITE_CACHE_DISABLED;
 	err = queue_limits_commit_update(q, &lim);
 	if (err)
 		return err;

include/linux/blkdev.h

@@ -339,8 +339,8 @@ enum {
 
 /* internal flags in queue_limits.flags */
 enum {
-	/* do not send FLUSH or FUA command despite advertised write cache */
-	BLK_FLAGS_WRITE_CACHE_DISABLED		= (1u << 31),
+	/* do not send FLUSH/FUA commands despite advertising a write cache */
+	BLK_FLAG_WRITE_CACHE_DISABLED		= (1u << 0),
 };
 
 struct queue_limits {
@@ -1339,7 +1339,7 @@ static inline bool bdev_stable_writes(struct block_device *bdev)
 static inline bool blk_queue_write_cache(struct request_queue *q)
 {
 	return (q->limits.features & BLK_FEAT_WRITE_CACHE) &&
-		!(q->limits.flags & BLK_FLAGS_WRITE_CACHE_DISABLED);
+		!(q->limits.flags & BLK_FLAG_WRITE_CACHE_DISABLED);
 }
 
 static inline bool bdev_write_cache(struct block_device *bdev)