From: relan <relan@users.noreply.github.com>
Date: Tue, 26 Feb 2013 18:58:36 +0000 (+0000)
Subject: Avoid extra erase on writes to the end of a file.
X-Git-Tag: android-x86-6.0-r1~108
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=36a79d4309268cf7f5b2871e6a6c6b0e1c78839f;p=android-x86%2Fexternal-exfat.git

Avoid extra erase on writes to the end of a file.
---

diff --git a/fuse/main.c b/fuse/main.c
index 53bafc1..cd02599 100644
--- a/fuse/main.c
+++ b/fuse/main.c
@@ -80,7 +80,7 @@ static int fuse_exfat_truncate(const char* path, off_t size)
 	if (rc != 0)
 		return rc;
 
-	rc = exfat_truncate(&ef, node, size);
+	rc = exfat_truncate(&ef, node, size, true);
 	exfat_put_node(&ef, node);
 	return rc;
 }
diff --git a/libexfat/cluster.c b/libexfat/cluster.c
index c462fc3..bd413bd 100644
--- a/libexfat/cluster.c
+++ b/libexfat/cluster.c
@@ -344,7 +344,8 @@ static int erase_range(struct exfat* ef, struct exfat_node* node,
 	return 0;
 }
 
-int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size)
+int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
+		bool erase)
 {
 	uint32_t c1 = bytes2clusters(ef, node->size);
 	uint32_t c2 = bytes2clusters(ef, size);
@@ -364,9 +365,12 @@ int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size)
 	if (rc != 0)
 		return rc;
 
-	rc = erase_range(ef, node, node->size, size);
-	if (rc != 0)
-		return rc;
+	if (erase)
+	{
+		rc = erase_range(ef, node, node->size, size);
+		if (rc != 0)
+			return rc;
+	}
 
 	exfat_update_mtime(node);
 	node->size = size;
diff --git a/libexfat/exfat.h b/libexfat/exfat.h
index e5fe625..8596efd 100644
--- a/libexfat/exfat.h
+++ b/libexfat/exfat.h
@@ -164,7 +164,8 @@ cluster_t exfat_next_cluster(const struct exfat* ef,
 cluster_t exfat_advance_cluster(const struct exfat* ef,
 		struct exfat_node* node, uint32_t count);
 void exfat_flush_cmap(struct exfat* ef);
-int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size);
+int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
+		bool erase);
 uint32_t exfat_count_free_clusters(const struct exfat* ef);
 int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b);
 
diff --git a/libexfat/io.c b/libexfat/io.c
index 4413aaa..fea3562 100644
--- a/libexfat/io.c
+++ b/libexfat/io.c
@@ -351,9 +351,12 @@ ssize_t exfat_generic_pwrite(struct exfat* ef, struct exfat_node* node,
 	const char* bufp = buffer;
 	off_t lsize, loffset, remainder;
 
-	if (offset + size > node->size)
-		if (exfat_truncate(ef, node, offset + size) != 0)
-			return -1;
+ 	if (offset > node->size)
+ 		if (exfat_truncate(ef, node, offset, true) != 0)
+ 			return -1;
+  	if (offset + size > node->size)
+ 		if (exfat_truncate(ef, node, offset + size, false) != 0)
+ 			return -1;
 	if (size == 0)
 		return 0;
 
diff --git a/libexfat/node.c b/libexfat/node.c
index 1f12b5f..2a855dd 100644
--- a/libexfat/node.c
+++ b/libexfat/node.c
@@ -56,7 +56,7 @@ void exfat_put_node(struct exfat* ef, struct exfat_node* node)
 		if (node->flags & EXFAT_ATTRIB_UNLINKED)
 		{
 			/* free all clusters and node structure itself */
-			exfat_truncate(ef, node, 0);
+			exfat_truncate(ef, node, 0, true);
 			free(node);
 		}
 		if (ef->cmap.dirty)
@@ -627,7 +627,7 @@ static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
 		new_size = CLUSTER_SIZE(*ef->sb);
 	if (new_size == dir->size)
 		return 0;
-	rc = exfat_truncate(ef, dir, new_size);
+	rc = exfat_truncate(ef, dir, new_size, true);
 	if (rc != 0)
 		return rc;
 	return 0;
@@ -673,7 +673,7 @@ static int grow_directory(struct exfat* ef, struct exfat_node* dir,
 {
 	return exfat_truncate(ef, dir,
 			DIV_ROUND_UP(asize + difference, CLUSTER_SIZE(*ef->sb))
-				* CLUSTER_SIZE(*ef->sb));
+				* CLUSTER_SIZE(*ef->sb), true);
 }
 
 static int find_slot(struct exfat* ef, struct exfat_node* dir,
@@ -826,7 +826,7 @@ int exfat_mkdir(struct exfat* ef, const char* path)
 	if (rc != 0)
 		return 0;
 	/* directories always have at least one cluster */
-	rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb));
+	rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
 	if (rc != 0)
 	{
 		delete(ef, node);