linux-ext4 - [PATCH 1/2] ext4: try to relieve ext4_mb_discard_group_preallocations() from hard work in simple way

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Date:	Thu, 25 Mar 2010 23:24:13 +0800
From:	jing zhang <zj.barak@...il.com>
To:	linux-ext4 <linux-ext4@...r.kernel.org>
Cc:	"Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger@....com>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>,
	"Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com>
Subject: [PATCH 1/2] ext4: try to relieve ext4_mb_discard_group_preallocations() 
	from hard work in simple way

From: Jing Zhang <zj.barak@...il.com>

Date: Wed Mar 25  23:15:06     2010

The function, ext4_mb_discard_group_preallocations(), works alone as
hard as possible without correct understanding its caller's good
thinking.

And now try to relieve it in simple way.

But the variable, free, may be replaced with freed.

Cc: Theodore Ts'o <tytso@....edu>
Cc: Andreas Dilger <adilger@....com>
Cc: Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Cc: "Aneesh Kumar K. V" <aneesh.kumar@...ux.vnet.ibm.com>
Signed-off-by: Jing Zhang <zj.barak@...il.com>

---

--- linux-2.6.32/fs/ext4/mballoc.c	2009-12-03 11:51:22.000000000 +0800
+++ ext4_mm_leak/mballoc-11-1.c	2010-03-25 23:06:00.000000000 +0800
@@ -3633,7 +3633,7 @@ repeat:
 		spin_lock(&pa->pa_lock);
 		if (atomic_read(&pa->pa_count)) {
 			spin_unlock(&pa->pa_lock);
-			busy = 1;
+			busy += 1;
 			continue;
 		}
 		if (pa->pa_deleted) {
@@ -3654,7 +3654,7 @@ repeat:
 	}

 	/* if we still need more blocks and some PAs were used, try again */
-	if (free < needed && busy) {
+	if (free < needed && needed <= free + busy) {
 		busy = 0;
 		ext4_unlock_group(sb, group);
 		/*
--
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