[PATCH 2/2] btrfs: drop premature generation setting in btrfs_init_new_buffer()

[Sun YangKai <sunk67188@gmail.com>]

btrfs_init_new_buffer() sets the header generation only to satisfy
btrfs_clear_buffer_dirty()'s transaction check, then immediately
cleared by memzero_extent_buffer(). This is introduced in
commit cbddcc4fa3443("btrfs: set generation before calling btrfs_clean_tree_block in btrfs_init_new_buffer").

However, after commit c4e54a6571168("btrfs: replace clearing extent buffer dirty bit with btrfs_clean_block")
we can pass NULL instead of the transaction handle to
btrfs_clear_buffer_dirty() so that the generation of the buffer is not
checked. So we can remove the generation assignment that was done only
for that check.

No functional change, just removes a redundant write.

Signed-off-by: Sun YangKai <sunk67188@gmail.com>
---
 fs/btrfs/extent-tree.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index dc4ca98c3780..b22b0aaa99e4 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5082,9 +5082,6 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 	    !test_bit(BTRFS_ROOT_RESET_LOCKDEP_CLASS, &root->state))
 		lockdep_owner = BTRFS_FS_TREE_OBJECTID;
 
-	/* btrfs_clear_buffer_dirty() accesses generation field. */
-	btrfs_set_header_generation(buf, trans->transid);
-
 	/*
 	 * This needs to stay, because we could allocate a freed block from an
 	 * old tree into a new tree, so we need to make sure this new block is
@@ -5093,7 +5090,8 @@ btrfs_init_new_buffer(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 	btrfs_set_buffer_lockdep_class(lockdep_owner, buf, level);
 
 	btrfs_tree_lock_nested(buf, nest);
-	btrfs_clear_buffer_dirty(trans, buf);
+	/* We don't care buf's generation here. */
+	btrfs_clear_buffer_dirty(NULL, buf);
 	clear_bit(EXTENT_BUFFER_STALE, &buf->bflags);
 	clear_bit(EXTENT_BUFFER_ZONED_ZEROOUT, &buf->bflags);
 
-- 
2.51.2