Merge branch 'for-linus' into for-next

1 files changed, 12 insertions, 1 deletions

diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index def8b8d30ccc..df518c429667 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -138,6 +138,17 @@ BUFFER_FNS(Defer_Completion, defer_completion)
 static __always_inline void set_buffer_uptodate(struct buffer_head *bh)
 {
 	/*
+	 * If somebody else already set this uptodate, they will
+	 * have done the memory barrier, and a reader will thus
+	 * see *some* valid buffer state.
+	 *
+	 * Any other serialization (with IO errors or whatever that
+	 * might clear the bit) has to come from other state (eg BH_Lock).
+	 */
+	if (test_bit(BH_Uptodate, &bh->b_state))
+		return;
+
+	/*
 	 * make it consistent with folio_mark_uptodate
 	 * pairs with smp_load_acquire in buffer_uptodate
 	 */
@@ -156,7 +167,7 @@ static __always_inline int buffer_uptodate(const struct buffer_head *bh)
 	 * make it consistent with folio_test_uptodate
 	 * pairs with smp_mb__before_atomic in set_buffer_uptodate
 	 */
-	return (smp_load_acquire(&bh->b_state) & (1UL << BH_Uptodate)) != 0;
+	return test_bit_acquire(BH_Uptodate, &bh->b_state);
 }
 
 #define bh_offset(bh)		((unsigned long)(bh)->b_data & ~PAGE_MASK)