tree d7a34e5414a25f24f48d4b9bb4284ef2ebe16313
parent 581227d0d2b8735f899182f50b3a05089d02fa24
author Miao Xie <miaox@cn.fujitsu.com> 1368762823 +0000
committer Josef Bacik <jbacik@fusionio.com> 1371223791 -0400

Btrfs: make the state of the transaction more readable

We used 3 variants to track the state of the transaction, it was complex
and wasted the memory space. Besides that, it was hard to understand that
which types of the transaction handles should be blocked in each transaction
state, so the developers often made mistakes.

This patch improved the above problem. In this patch, we define 6 states
for the transaction,
  enum btrfs_trans_state {
	TRANS_STATE_RUNNING		= 0,
	TRANS_STATE_BLOCKED		= 1,
	TRANS_STATE_COMMIT_START	= 2,
	TRANS_STATE_COMMIT_DOING	= 3,
	TRANS_STATE_UNBLOCKED		= 4,
	TRANS_STATE_COMPLETED		= 5,
	TRANS_STATE_MAX			= 6,
  }
and just use 1 variant to track those state.

In order to make the blocked handle types for each state more clear,
we introduce a array:
  unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
	[TRANS_STATE_RUNNING]		= 0U,
	[TRANS_STATE_BLOCKED]		= (__TRANS_USERSPACE |
					   __TRANS_START),
	[TRANS_STATE_COMMIT_START]	= (__TRANS_USERSPACE |
					   __TRANS_START |
					   __TRANS_ATTACH),
	[TRANS_STATE_COMMIT_DOING]	= (__TRANS_USERSPACE |
					   __TRANS_START |
					   __TRANS_ATTACH |
					   __TRANS_JOIN),
	[TRANS_STATE_UNBLOCKED]		= (__TRANS_USERSPACE |
					   __TRANS_START |
					   __TRANS_ATTACH |
					   __TRANS_JOIN |
					   __TRANS_JOIN_NOLOCK),
	[TRANS_STATE_COMPLETED]		= (__TRANS_USERSPACE |
					   __TRANS_START |
					   __TRANS_ATTACH |
					   __TRANS_JOIN |
					   __TRANS_JOIN_NOLOCK),
  }
it is very intuitionistic.

Besides that, because we remove ->in_commit in transaction structure, so
the lock ->commit_lock which was used to protect it is unnecessary, remove
->commit_lock.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>