linux-ext4 - Re: [PATCH 2/3] quota: add the option to not fail with EDQUOT in block allocation

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Date:	Mon, 12 Apr 2010 15:23:16 +0200
From:	Jan Kara <jack@...e.cz>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 2/3] quota: add the option to not fail with EDQUOT in
	block allocation

> To simplify metadata tracking for delalloc writes, ext4
> will simply claim metadata blocks at allocation time, without
> first speculatively reserving the worst case and then freeing
> what was not used.
> 
> To do this, we need a mechanism to track allocations in
> the quota subsystem, but potentially allow that allocation
> to actually go over quota.
> 
> This patch adds a DQUOT_SPACE_NOFAIL flag and function
> variants for this purpose.
> 
> Signed-off-by: Eric Sandeen <sandeen@...hat.com>
   Looks fine. Acked-by: Jan Kara <jack@...e.cz>

								Honza
> ---
> 
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index 8436d9b..c38b137 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -1490,6 +1490,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
>  	char warntype[MAXQUOTAS];
>  	int warn = flags & DQUOT_SPACE_WARN;
>  	int reserve = flags & DQUOT_SPACE_RESERVE;
> +	int nofail = flags & DQUOT_SPACE_NOFAIL;
>  
>  	/*
>  	 * First test before acquiring mutex - solves deadlocks when we
> @@ -1510,7 +1511,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
>  			continue;
>  		ret = check_bdq(inode->i_dquot[cnt], number, !warn,
>  				warntype+cnt);
> -		if (ret) {
> +		if (ret && !nofail) {
>  			spin_unlock(&dq_data_lock);
>  			goto out_flush_warn;
>  		}
> diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
> index daa106f..8f858ce 100644
> --- a/include/linux/quotaops.h
> +++ b/include/linux/quotaops.h
> @@ -16,6 +16,7 @@ static inline struct quota_info *sb_dqopt(struct super_block *sb)
>  
>  #define DQUOT_SPACE_WARN	0x1
>  #define DQUOT_SPACE_RESERVE	0x2
> +#define DQUOT_SPACE_NOFAIL	0x4
>  
>  #if defined(CONFIG_QUOTA)
>  
> @@ -262,6 +263,12 @@ static inline int dquot_alloc_space_nodirty(struct inode *inode, qsize_t nr)
>  	return __dquot_alloc_space(inode, nr, DQUOT_SPACE_WARN);
>  }
>  
> +static inline void dquot_alloc_space_nofail(struct inode *inode, qsize_t nr)
> +{
> +	__dquot_alloc_space(inode, nr, DQUOT_SPACE_WARN|DQUOT_SPACE_NOFAIL);
> +	mark_inode_dirty(inode);
> +}
> +
>  static inline int dquot_alloc_space(struct inode *inode, qsize_t nr)
>  {
>  	int ret;
> @@ -277,6 +284,11 @@ static inline int dquot_alloc_block_nodirty(struct inode *inode, qsize_t nr)
>  	return dquot_alloc_space_nodirty(inode, nr << inode->i_blkbits);
>  }
>  
> +static inline void dquot_alloc_block_nofail(struct inode *inode, qsize_t nr)
> +{
> +	dquot_alloc_space_nofail(inode, nr << inode->i_blkbits);
> +}
> +
>  static inline int dquot_alloc_block(struct inode *inode, qsize_t nr)
>  {
>  	return dquot_alloc_space(inode, nr << inode->i_blkbits);
> 
> --
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-- 
Jan Kara <jack@...e.cz>
SuSE CR Labs
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