Re: [PATCH 1/2] Btrfs: make clear_extent_bit() always return 0 on success

[Li Zefan <lizefan@huawei.com>]

(Note: I've changed my email address ;)

David Sterba wrote:

> On Mon, Mar 12, 2012 at 04:39:28PM +0800, Li Zefan wrote:
>> Currently it returns a set of bits that were cleared, but this return
>> value is not used at all.
>>
>> Moreover it doesn't seem to be useful, because we may clear the bits
>> of a few extent_states, but only the cleared bits of last one is
>> returned.
>>
>> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
>> ---
>>  fs/btrfs/extent_io.c |   19 +++++++------------
>>  1 files changed, 7 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
>> index a55fbe6..c968c95 100644
>> --- a/fs/btrfs/extent_io.c
>> +++ b/fs/btrfs/extent_io.c
>> @@ -394,18 +394,16 @@ static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
>>  
>>  /*
>>   * utility function to clear some bits in an extent state struct.
>> - * it will optionally wake up any one waiting on this state (wake == 1), or
>> - * forcibly remove the state from the tree (delete == 1).
>> + * it will optionally wake up any one waiting on this state (wake == 1)
>>   *
>>   * If no bits are set on the state struct after clearing things, the
>>   * struct is freed and removed from the tree
>>   */
>> -static int clear_state_bit(struct extent_io_tree *tree,
>> +static void clear_state_bit(struct extent_io_tree *tree,
>>  			    struct extent_state *state,
>>  			    int *bits, int wake)
>>  {
>>  	int bits_to_clear = *bits & ~EXTENT_CTLBITS;
>> -	int ret = state->state & bits_to_clear;
>>  
>>  	if ((bits_to_clear & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
>>  		u64 range = state->end - state->start + 1;
>> @@ -427,7 +425,6 @@ static int clear_state_bit(struct extent_io_tree *tree,
>>  	} else {
>>  		merge_state(tree, state);
>>  	}
>> -	return ret;
>>  }
>>  
>>  static struct extent_state *
> 
> The above part of the patch still applies and with only subject change
> to something like
> 
>   Btrfs: retrurn void from clear_state_bit
> 
> is a rc2 material. So, Li, if you're ok with this change I'm adding it
> (with the 2/2 patch) to my local queue of rc patches for Chris.
> 


Thanks for doing this!

--
Li Zefan

> 
> david
> 
> (the rest of the patch was done within the error handling series)
> 
>> @@ -449,8 +446,7 @@ alloc_extent_state_atomic(struct extent_state *prealloc)
>>   *
>>   * the range [start, end] is inclusive.
>>   *
>> - * This takes the tree lock, and returns < 0 on error, > 0 if any of the
>> - * bits were already set, or zero if none of the bits were already set.
>> + * This takes the tree lock, and returns < 0 on error.
>>   */
>>  int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
>>  		     int bits, int wake, int delete,
>> @@ -464,7 +460,6 @@ int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
>>  	struct rb_node *node;
>>  	u64 last_end;
>>  	int err;
>> -	int set = 0;
>>  	int clear = 0;
>>  
>>  	if (delete)
>> @@ -547,7 +542,7 @@ hit_next:
>>  		if (err)
>>  			goto out;
>>  		if (state->end <= end) {
>> -			set |= clear_state_bit(tree, state, &bits, wake);
>> +			clear_state_bit(tree, state, &bits, wake);
>>  			if (last_end == (u64)-1)
>>  				goto out;
>>  			start = last_end + 1;
>> @@ -568,13 +563,13 @@ hit_next:
>>  		if (wake)
>>  			wake_up(&state->wq);
>>  
>> -		set |= clear_state_bit(tree, prealloc, &bits, wake);
>> +		clear_state_bit(tree, prealloc, &bits, wake);
>>  
>>  		prealloc = NULL;
>>  		goto out;
>>  	}
>>  
>> -	set |= clear_state_bit(tree, state, &bits, wake);
>> +	clear_state_bit(tree, state, &bits, wake);
>>  next:
>>  	if (last_end == (u64)-1)
>>  		goto out;
>> @@ -591,7 +586,7 @@ out:
>>  	if (prealloc)
>>  		free_extent_state(prealloc);
>>  
>> -	return set;
>> +	return 0;
>>  
>>  search_again:
>>  	if (start > end)
>> -- 1.7.3.1