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From: Bernd Schubert <bs@q-leap.de>
To: Randy Dunlap <randy.dunlap@oracle.com>
Cc: linux-kernel@vger.kernel.org,
	"J. Bruce Fields" <bfields@fieldses.org>,
	brian@clusterfs.com,
	Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>,
	bs@q-leap.de
Subject: Re: patch: improve generic_file_buffered_write() (2nd try 2/2)
Date: Wed, 5 Sep 2007 19:49:28 +0200	[thread overview]
Message-ID: <200709051949.28585.bs@q-leap.de> (raw)
In-Reply-To: <200709051941.56145.bs@q-leap.de>

I guess when aio was introduced this was probably forgotten. For small chunks 
or synchronous i/o the likehood is correct, but for big data chunks and aio 
the likehood is false.

Signed-off-by: Bernd Schubert <bs@q-leap.de>
Signed-off-by: Goswin von Brederlow <goswin@vonbrederlow.de>

Index: linux-2.6.20.3/mm/filemap.c
===================================================================
--- linux-2.6.20.3.orig/mm/filemap.c	2007-09-05 18:51:59.000000000 +0200
+++ linux-2.6.20.3/mm/filemap.c	2007-09-05 18:53:12.000000000 +0200
@@ -2100,7 +2100,7 @@
 	/*
 	 * handle partial DIO write.  Adjust cur_iov if needed.
 	 */
-	if (likely(nr_segs == 1))
+	if (nr_segs == 1)
 		buf = iov->iov_base + written;
 	else {
 		filemap_set_next_iovec(&cur_iov, &iov_base, written);
@@ -2167,7 +2167,7 @@
 					vmtruncate(inode, isize);
 			}
 		}
-		if (likely(nr_segs == 1))
+		if (nr_segs == 1)
 			copied = filemap_copy_from_user(page, offset,
 							buf, bytes);
 		else
@@ -2213,7 +2213,7 @@
 				count -= copied;
 				pos += copied;
 				buf += copied;
-				if (unlikely(nr_segs > 1)) {
+				if (nr_segs > 1) {
 					filemap_set_next_iovec(&cur_iov,
 							&iov_base, copied);
 					if (count)

  reply	other threads:[~2007-09-05 17:49 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-05 13:45 patch: improve generic_file_buffered_write() Bernd Schubert
2007-09-05 15:35 ` Randy Dunlap
2007-09-05 17:41   ` patch: improve generic_file_buffered_write() (2nd try 1/2) Bernd Schubert
2007-09-05 17:49     ` Bernd Schubert [this message]
2007-09-08  4:15     ` Nick Piggin
2007-09-07 20:01       ` Goswin von Brederlow
2007-09-08  6:28         ` Nick Piggin
2007-09-07 21:12           ` Goswin von Brederlow
2007-09-08  7:25             ` Nick Piggin
2007-09-08  7:31               ` Nick Piggin
2007-09-08  9:43                 ` Goswin von Brederlow
2007-09-07 20:12                   ` Nick Piggin
2007-09-07 21:00       ` Goswin von Brederlow
2007-09-08  7:14         ` Nick Piggin

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