linux-ext4 - Re: [PATCH 1/4] ext4: delalloc quota fixes

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Message-id: <87aaybn261.fsf@openvz.org>
Date:	Tue, 24 Nov 2009 22:38:46 +0300
From:	Dmitry Monakhov <dmonakhov@...nvz.org>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/4] ext4: delalloc quota fixes

Eric Sandeen <sandeen@...hat.com> writes:

> Dmitry Monakhov wrote:
>> This patch fix most visible problems with delalloc+quota issues
>> - ext4_get_reserved_space() must return bytes instead of blocks.
>> - Claim allocated meta blocks. Do it as we do for data blocks
>>   but delay it untill proper moment.
>> - Move space claiming to ext4_da_update_reserve_space()
>>   Only here we do know what we are dealing with data or metadata
>> 
>> The most useful test case for delalloc+quota is concurent tasks
>> with write+truncate vs chown for a same file.
>> 
>> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
>> ---
>>  fs/ext4/inode.c   |   12 ++++++++----
>>  fs/ext4/mballoc.c |    6 ------
>>  2 files changed, 8 insertions(+), 10 deletions(-)
>> 
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index ab22297..e642cdb 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -1057,7 +1057,7 @@ qsize_t ext4_get_reserved_space(struct inode *inode)
>>  		EXT4_I(inode)->i_reserved_meta_blocks;
>>  	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
>>  
>> -	return total;
>> +	return (total << inode->i_blkbits);
>>  }
>
> Ow, whoops, yes this looks like a bug!  (maybe should be in its own patch?)
Ok i'll resubmit patchset soon.
>
>>  /*
>>   * Calculate the number of metadata blocks need to reserve
>> @@ -1096,7 +1096,7 @@ static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
>>  static void ext4_da_update_reserve_space(struct inode *inode, int used)
>>  {
>>  	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
>> -	int total, mdb, mdb_free;
>> +	int total, mdb, mdb_free, mdb_claim = 0;
>>  
>>  	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
>>  	/* recalculate the number of metablocks still need to be reserved */
>> @@ -1109,7 +1109,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
>>  
>>  	if (mdb_free) {
>>  		/* Account for allocated meta_blocks */
>> -		mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
>> +		mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks;
>> +		BUG_ON(mdb_free < mdb_claim);
>
> Did you see this happening in testing?
>
No i didn't. I've add it just for sanity reason.
>> +		mdb_free -= mdb_claim;
>>  
>>  		/* update fs dirty blocks counter */
>>  		percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
>> @@ -1119,7 +1121,9 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
>>  
>>  	/* update per-inode reservations */
>>  	BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
>> -	EXT4_I(inode)->i_reserved_data_blocks -= used;
>> + 	EXT4_I(inode)->i_reserved_data_blocks -= used;
>
> looks like a little whitespace damage here
>
>> +	percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim);
>> +	vfs_dq_claim_block(inode, used + mdb_claim);
>>  	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
>>  
>>  	/*
>> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
>> index bba1282..d4c52db 100644
>> --- a/fs/ext4/mballoc.c
>> +++ b/fs/ext4/mballoc.c
>> @@ -2750,12 +2750,6 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
>>  	if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
>>  		/* release all the reserved blocks if non delalloc */
>>  		percpu_counter_sub(&sbi->s_dirtyblocks_counter, reserv_blks);
>> -	else {
>> -		percpu_counter_sub(&sbi->s_dirtyblocks_counter,
>> -						ac->ac_b_ex.fe_len);
>> -		/* convert reserved quota blocks to real quota blocks */
>> -		vfs_dq_claim_block(ac->ac_inode, ac->ac_b_ex.fe_len);
>> -	}
>
> Maybe Mingming can review this change better, I don't have all the quota paths
> in my head yet ...
>
> -Eric
>
>>  	if (sbi->s_log_groups_per_flex) {
>>  		ext4_group_t flex_group = ext4_flex_group(sbi,
--
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