linux-kernel - Re: [PATCH v2] ext4: fix quota charging for shared xattr blocks

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Message-ID: <20170524090658.GD10604@quack2.suse.cz>
Date:   Wed, 24 May 2017 11:06:58 +0200
From:   Jan Kara <jack@...e.cz>
To:     Tahsin Erdogan <tahsin@...gle.com>
Cc:     Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ext4: fix quota charging for shared xattr blocks

On Tue 23-05-17 16:03:51, Tahsin Erdogan wrote:
> ext4_xattr_block_set() calls dquot_alloc_block() to charge for an xattr
> block when new references are made. However if dquot_initialize() hasn't
> been called on an inode, request for charging is effectively ignored
> because ext4_inode_info->i_dquot is not initialized yet.
> 
> Add dquot_initialize() to call paths that lead to ext4_xattr_block_set().
> 
> Signed-off-by: Tahsin Erdogan <tahsin@...gle.com>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
> v2:
>  - moved dquot_initialize() to outside the main transaction
>  - added dquot_initialize_needed() function that is used by
>    ext4_xattr_release_block() to warn about call paths that don't
>    call dquot_initialize()
> 
>  fs/ext4/acl.c            |  4 ++++
>  fs/ext4/super.c          |  3 +++
>  fs/ext4/xattr.c          |  8 ++++++++
>  fs/quota/dquot.c         | 16 ++++++++++++++++
>  include/linux/quotaops.h |  6 ++++++
>  5 files changed, 37 insertions(+)
> 
> diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
> index fd389935ecd1..3ec0e46de95f 100644
> --- a/fs/ext4/acl.c
> +++ b/fs/ext4/acl.c
> @@ -4,6 +4,7 @@
>   * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@...e.de>
>   */
>  
> +#include <linux/quotaops.h>
>  #include "ext4_jbd2.h"
>  #include "ext4.h"
>  #include "xattr.h"
> @@ -232,6 +233,9 @@ ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
>  	handle_t *handle;
>  	int error, retries = 0;
>  
> +	error = dquot_initialize(inode);
> +	if (error)
> +		return error;
>  retry:
>  	handle = ext4_journal_start(inode, EXT4_HT_XATTR,
>  				    ext4_jbd2_credits_xattr(inode));
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 0b177da9ea82..e2e0eb7ac9a0 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1179,6 +1179,9 @@ static int ext4_set_context(struct inode *inode, const void *ctx, size_t len,
>  		return res;
>  	}
>  
> +	res = dquot_initialize(inode);
> +	if (res)
> +		return res;
>  retry:
>  	handle = ext4_journal_start(inode, EXT4_HT_MISC,
>  			ext4_jbd2_credits_xattr(inode));
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 8fb7ce14e6eb..5d3c2536641c 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -888,6 +888,8 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  			else {
>  				u32 ref;
>  
> +				WARN_ON_ONCE(dquot_initialize_needed(inode));
> +
>  				/* The old block is released after updating
>  				   the inode. */
>  				error = dquot_alloc_block(inode,
> @@ -954,6 +956,8 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
>  			/* We need to allocate a new block */
>  			ext4_fsblk_t goal, block;
>  
> +			WARN_ON_ONCE(dquot_initialize_needed(inode));
> +
>  			goal = ext4_group_first_block_no(sb,
>  						EXT4_I(inode)->i_block_group);
>  
> @@ -1166,6 +1170,7 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
>  		return -EINVAL;
>  	if (strlen(name) > 255)
>  		return -ERANGE;
> +
>  	ext4_write_lock_xattr(inode, &no_expand);
>  
>  	error = ext4_reserve_inode_write(handle, inode, &is.iloc);
> @@ -1267,6 +1272,9 @@ ext4_xattr_set(struct inode *inode, int name_index, const char *name,
>  	int error, retries = 0;
>  	int credits = ext4_jbd2_credits_xattr(inode);
>  
> +	error = dquot_initialize(inode);
> +	if (error)
> +		return error;
>  retry:
>  	handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
>  	if (IS_ERR(handle)) {
> diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
> index ebf80c7739e1..48813aeaab80 100644
> --- a/fs/quota/dquot.c
> +++ b/fs/quota/dquot.c
> @@ -1512,6 +1512,22 @@ int dquot_initialize(struct inode *inode)
>  }
>  EXPORT_SYMBOL(dquot_initialize);
>  
> +bool dquot_initialize_needed(struct inode *inode)
> +{
> +	struct dquot **dquots;
> +	int i;
> +
> +	if (!dquot_active(inode))
> +		return false;
> +
> +	dquots = i_dquot(inode);
> +	for (i = 0; i < MAXQUOTAS; i++)
> +		if (!dquots[i] && sb_has_quota_active(inode->i_sb, i))
> +			return true;
> +	return false;
> +}
> +EXPORT_SYMBOL(dquot_initialize_needed);
> +
>  /*
>   * Release all quotas referenced by inode.
>   *
> diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
> index 9c6f768b7d32..dda22f45fc1b 100644
> --- a/include/linux/quotaops.h
> +++ b/include/linux/quotaops.h
> @@ -44,6 +44,7 @@ void inode_sub_rsv_space(struct inode *inode, qsize_t number);
>  void inode_reclaim_rsv_space(struct inode *inode, qsize_t number);
>  
>  int dquot_initialize(struct inode *inode);
> +bool dquot_initialize_needed(struct inode *inode);
>  void dquot_drop(struct inode *inode);
>  struct dquot *dqget(struct super_block *sb, struct kqid qid);
>  static inline struct dquot *dqgrab(struct dquot *dquot)
> @@ -207,6 +208,11 @@ static inline int dquot_initialize(struct inode *inode)
>  	return 0;
>  }
>  
> +static inline bool dquot_initialize_needed(struct inode *inode)
> +{
> +	return false;
> +}
> +
>  static inline void dquot_drop(struct inode *inode)
>  {
>  }
> -- 
> 2.13.0.219.gdb65acc882-goog
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR