Linux 6.11: enable queue flush through queue limits

In 6.11 struct queue_limits gains a 'features' field, where, among other
things, flush and write-cache are enabled. Detect it and use it.

Along the way, the blk_queue_set_write_cache() compat wrapper gets a
little cleanup. Since both flags are alway set together, its now a
single bool. Also the very very ancient version that sets q->flush_flags
directly couldn't actually turn it off, so I've fixed that. Not that we
use it, but still.

Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Sponsored-by: https://despairlabs.com/sponsor/
Closes #16400

1 files changed, 19 insertions, 12 deletions

diff --git a/include/os/linux/kernel/linux/blkdev_compat.h b/include/os/linux/kernel/linux/blkdev_compat.h
index b0f398354..0d07fd4b8 100644
--- a/include/os/linux/kernel/linux/blkdev_compat.h
+++ b/include/os/linux/kernel/linux/blkdev_compat.h
@@ -57,6 +57,11 @@ blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
 #endif
 
 /*
+ * 6.11 API
+ * Setting the flush flags directly is no longer possible; flush flags are set
+ * on the queue_limits structure and passed to blk_disk_alloc(). In this case
+ * we remove this function entirely.
+ *
  * 4.7 API,
  * The blk_queue_write_cache() interface has replaced blk_queue_flush()
  * interface.  However, the new interface is GPL-only thus we implement
@@ -68,31 +73,33 @@ blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
  * new one is GPL-only.   Thus if the GPL-only version is detected we
  * implement our own trivial helper.
  */
+#if !defined(HAVE_BLK_ALLOC_DISK_2ARG) || \
+	!defined(HAVE_BLKDEV_QUEUE_LIMITS_FEATURES)
 static inline void
-blk_queue_set_write_cache(struct request_queue *q, bool wc, bool fua)
+blk_queue_set_write_cache(struct request_queue *q, bool on)
 {
 #if defined(HAVE_BLK_QUEUE_WRITE_CACHE_GPL_ONLY)
-	if (wc)
+	if (on) {
 		blk_queue_flag_set(QUEUE_FLAG_WC, q);
-	else
-		blk_queue_flag_clear(QUEUE_FLAG_WC, q);
-	if (fua)
 		blk_queue_flag_set(QUEUE_FLAG_FUA, q);
-	else
+	} else {
+		blk_queue_flag_clear(QUEUE_FLAG_WC, q);
 		blk_queue_flag_clear(QUEUE_FLAG_FUA, q);
+	}
 #elif defined(HAVE_BLK_QUEUE_WRITE_CACHE)
-	blk_queue_write_cache(q, wc, fua);
+	blk_queue_write_cache(q, on, on);
 #elif defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
-	if (wc)
-		q->flush_flags |= REQ_FLUSH;
-	if (fua)
-		q->flush_flags |= REQ_FUA;
+	if (on)
+		q->flush_flags |= REQ_FLUSH | REQ_FUA;
+	else
+		q->flush_flags &= ~(REQ_FLUSH | REQ_FUA);
 #elif defined(HAVE_BLK_QUEUE_FLUSH)
-	blk_queue_flush(q, (wc ? REQ_FLUSH : 0) | (fua ? REQ_FUA : 0));
+	blk_queue_flush(q, on ? (REQ_FLUSH | REQ_FUA) : 0);
 #else
 #error "Unsupported kernel"
 #endif
 }
+#endif /* !HAVE_BLK_ALLOC_DISK_2ARG || !HAVE_BLKDEV_QUEUE_LIMITS_FEATURES */
 
 static inline void
 blk_queue_set_read_ahead(struct request_queue *q, unsigned long ra_pages)