From: Chris Mason <chris.mason@oracle.com>
Date: Tue, 10 Apr 2007 17:51:41 +0000 (-0400)
Subject: Btrfs: only cow in get_block when create==1
X-Git-Tag: firefly_0821_release~15789^2~11^2~55^2~56^2~30^2~606
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=79b2cb1fa6430501907cb1384abbddf074833e45;p=firefly-linux-kernel-4.4.55.git

Btrfs: only cow in get_block when create==1

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 91aa1b4c50af..a3183972f310 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1020,7 +1020,7 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
 
 	ret = btrfs_lookup_file_extent(trans, root, path,
 				       inode->i_ino,
-				       iblock << inode->i_blkbits, 1);
+				       iblock << inode->i_blkbits, create);
 	if (ret < 0) {
 		err = ret;
 		goto out;
@@ -1046,7 +1046,8 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
 	if (ret == 0) {
 		err = 0;
 		BUG_ON(btrfs_file_extent_disk_num_blocks(item) != 1);
-		if (btrfs_file_extent_generation(item) != trans->transid) {
+		if (create &&
+		    btrfs_file_extent_generation(item) != trans->transid) {
 			struct btrfs_key ins;
 			ret = btrfs_alloc_extent(trans, root, 1,
 						 blocknr, (u64)-1, &ins);