Linux compat 4.16: blk_queue_flag_{set,clear}

The HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY case was overlooked in
the original 10f88c5 commit because blk_queue_write_cache()
was available for the in-kernel builds.

Update the blk_queue_flag_{set,clear} wrappers to call the locked
versions to avoid confusion.  This is safe for all existing callers.

The blk_queue_set_write_cache() function has been updated to use
these wrappers.  This means setting/clearing both QUEUE_FLAG_WC
and QUEUE_FLAG_FUA is no longer atomic but this only done early
in zvol_alloc() prior to any requests so there is no issue.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Kash Pande <kash@tripleback.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes openzfs#7428
Closes openzfs#7431

include/linux/blkdev_compat.h

@@ -41,15 +41,15 @@ typedef unsigned __bitwise__ fmode_t;
 static inline void
 blk_queue_flag_set(unsigned int flag, struct request_queue *q)
 {
-	queue_flag_set_unlocked(flag, q);
+	queue_flag_set(flag, q);
 }
 #endif
 
 #ifndef HAVE_BLK_QUEUE_FLAG_CLEAR
 static inline void
 blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
 {
-	queue_flag_clear_unlocked(flag, q);
+	queue_flag_clear(flag, q);
 }
 #endif
 
@@ -72,16 +72,14 @@ static inline void
 blk_queue_set_write_cache(struct request_queue *q, bool wc, bool fua)
 {
 #if defined(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY)
-	spin_lock_irq(q->queue_lock);
 	if (wc)
-		queue_flag_set(QUEUE_FLAG_WC, q);
+		blk_queue_flag_set(QUEUE_FLAG_WC, q);
 	else
-		queue_flag_clear(QUEUE_FLAG_WC, q);
+		blk_queue_flag_clear(QUEUE_FLAG_WC, q);
 	if (fua)
-		queue_flag_set(QUEUE_FLAG_FUA, q);
+		blk_queue_flag_set(QUEUE_FLAG_FUA, q);
 	else
-		queue_flag_clear(QUEUE_FLAG_FUA, q);
-	spin_unlock_irq(q->queue_lock);
+		blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
 #elif defined(HAVE_BLK_QUEUE_WRITE_CACHE)
 	blk_queue_write_cache(q, wc, fua);
 #elif defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)