linux-kernel - [PATCH RFC] buffer_head: remove redundant test from wait_on

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Date:	Fri, 16 Apr 2010 11:58:19 +0100
From:	Richard Kennedy <richard@....demon.co.uk>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	Jens Axboe <jens.axboe@...cle.com>,
	lkml <linux-kernel@...r.kernel.org>,
	Nick Piggin <npiggin@...e.de>
Subject: [PATCH RFC]  buffer_head: remove redundant test from wait_on_buffer

The comment suggests that when b_count equals zero it is calling
__wait_no_buffer to trigger some debug, but as there is no debug in
__wait_on_buffer the whole thing is redundant.

AFAICT from the git log this has been the case for at least 5 years, so
it seems safe just to remove this.

Signed-off-by: Richard Kennedy <richard@....demon.co.uk>
---

This patch against 2.6.34-rc4
compiled & tested on x86_64

regards
Richard


diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 16ed028..4c62dd4 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -305,15 +305,10 @@ map_bh(struct buffer_head *bh, struct super_block *sb, sector_t block)
 	bh->b_size = sb->s_blocksize;
 }
 
-/*
- * Calling wait_on_buffer() for a zero-ref buffer is illegal, so we call into
- * __wait_on_buffer() just to trip a debug check.  Because debug code in inline
- * functions is bloaty.
- */
 static inline void wait_on_buffer(struct buffer_head *bh)
 {
 	might_sleep();
-	if (buffer_locked(bh) || atomic_read(&bh->b_count) == 0)
+	if (buffer_locked(bh))
 		__wait_on_buffer(bh);
 }
 


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