linux-ext4 - PATCH 1/2] ext4: stop looping in ext4_num_dirty_pages when max

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Message-ID: <4C7D0AAA.2080808@redhat.com>
Date:	Tue, 31 Aug 2010 08:59:06 -0500
From:	Eric Sandeen <sandeen@...hat.com>
To:	ext4 development <linux-ext4@...r.kernel.org>
Subject: PATCH 1/2] ext4: stop looping in ext4_num_dirty_pages when max_pages
 reached

Today we simply break out of the inner loop when we have accumulated
max_pages; this keeps scanning forwad and doing pagevec_lookup_tag()
in the while (!done) loop, this does potentially a lot of work
with no net effect.

When we have accumulated max_pages, just clean up and return.

Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4b8debe..93497f6 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1207,8 +1207,10 @@ static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
 				break;
 			idx++;
 			num++;
-			if (num >= max_pages)
-				break;
+			if (num >= max_pages) {
+				pagevec_release(&pvec);
+				return num;
+			}
 		}
 		pagevec_release(&pvec);
 	}


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