From ad072e9ee4420e3a4ee818c85c168f4bedee9335 Mon Sep 17 00:00:00 2001
From: Joern Engel <joern@logfs.org>
Date: Tue, 20 Apr 2010 21:44:10 +0200
Subject: [PATCH] --- yaml --- r: 190091 b: refs/heads/master c:
 b6349ac89eacb813f6963f7263da05bc3f483351 h: refs/heads/master i:   190089:
 564d75f1d74b1a293afb5d6bfd5237521f750fdd   190087:
 ba8e433c4d61b412cd01a7cc1157243927f393e8 v: v3

---
 [refs]                     |  2 +-
 trunk/fs/logfs/readwrite.c | 34 ++++++++++++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/[refs] b/[refs]
index ea52e39721b7..6d8693edb979 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: b8639077abf034824046ed09e779b74c4393031f
+refs/heads/master: b6349ac89eacb813f6963f7263da05bc3f483351
diff --git a/trunk/fs/logfs/readwrite.c b/trunk/fs/logfs/readwrite.c
index aca6c56a107a..7e3a1e5fd76d 100644
--- a/trunk/fs/logfs/readwrite.c
+++ b/trunk/fs/logfs/readwrite.c
@@ -1837,19 +1837,37 @@ static int __logfs_truncate(struct inode *inode, u64 size)
 	return logfs_truncate_direct(inode, size);
 }
 
-int logfs_truncate(struct inode *inode, u64 size)
+/*
+ * Truncate, by changing the segment file, can consume a fair amount
+ * of resources.  So back off from time to time and do some GC.
+ * 8 or 2048 blocks should be well within safety limits even if
+ * every single block resided in a different segment.
+ */
+#define TRUNCATE_STEP	(8 * 1024 * 1024)
+int logfs_truncate(struct inode *inode, u64 target)
 {
 	struct super_block *sb = inode->i_sb;
-	int err;
+	u64 size = i_size_read(inode);
+	int err = 0;
 
-	logfs_get_wblocks(sb, NULL, 1);
-	err = __logfs_truncate(inode, size);
-	if (!err)
-		err = __logfs_write_inode(inode, 0);
-	logfs_put_wblocks(sb, NULL, 1);
+	size = ALIGN(size, TRUNCATE_STEP);
+	while (size > target) {
+		if (size > TRUNCATE_STEP)
+			size -= TRUNCATE_STEP;
+		else
+			size = 0;
+		if (size < target)
+			size = target;
+
+		logfs_get_wblocks(sb, NULL, 1);
+		err = __logfs_truncate(inode, target);
+		if (!err)
+			err = __logfs_write_inode(inode, 0);
+		logfs_put_wblocks(sb, NULL, 1);
+	}
 
 	if (!err)
-		err = vmtruncate(inode, size);
+		err = vmtruncate(inode, target);
 
 	/* I don't trust error recovery yet. */
 	WARN_ON(err);