linux-ext4 - Re: [PATCH 01/11] ext4: Set flags on quota files directly

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Message-Id: <BDA95568-149C-4049-AFE0-0D7AB483CFB6@dilger.ca>
Date:   Wed, 12 Apr 2017 15:00:04 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        reiserfs-devel@...r.kernel.org,
        jfs-discussion@...ts.sourceforge.net
Subject: Re: [PATCH 01/11] ext4: Set flags on quota files directly

On Apr 12, 2017, at 1:26 AM, Jan Kara <jack@...e.cz> wrote:
> 
> Currently immutable and noatime flags on quota files are set by quota
> code which requires us to copy inode->i_flags to our on disk version of
> quota flags in GETFLAGS ioctl and ext4_do_update_inode(). Move to
> setting / clearing these on-disk flags directly to save that copying.
> 
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---
> fs/ext4/super.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 56 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index a9448db1cf7e..480cbbebdc57 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -839,6 +839,28 @@ static void dump_orphan_list(struct super_block *sb, struct ext4_sb_info *sbi)
> 	}
> }
> 
> +#ifdef CONFIG_QUOTA
> +static int ext4_quota_off(struct super_block *sb, int type);
> +
> +static inline void ext4_quota_off_umount(struct super_block *sb)
> +{
> +	int type;
> +
> +	if (ext4_has_feature_quota(sb)) {
> +		dquot_disable(sb, -1,
> +			      DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
> +	} else {
> +		/* Use our quota_off function to clear inode flags etc. */
> +		for (type = 0; type < EXT4_MAXQUOTAS; type++)
> +			ext4_quota_off(sb, type);
> +	}
> +}
> +#else
> +static inline void ext4_quota_off_umount(struct super_block *sb)
> +{
> +}
> +#endif
> +
> static void ext4_put_super(struct super_block *sb)
> {
> 	struct ext4_sb_info *sbi = EXT4_SB(sb);
> @@ -847,7 +869,7 @@ static void ext4_put_super(struct super_block *sb)
> 	int i, err;
> 
> 	ext4_unregister_li_request(sb);
> -	dquot_disable(sb, -1, DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
> +	ext4_quota_off_umount(sb);
> 
> 	flush_workqueue(sbi->rsv_conversion_wq);
> 	destroy_workqueue(sbi->rsv_conversion_wq);
> @@ -1218,7 +1240,6 @@ static int ext4_mark_dquot_dirty(struct dquot *dquot);
> static int ext4_write_info(struct super_block *sb, int type);
> static int ext4_quota_on(struct super_block *sb, int type, int format_id,
> 			 const struct path *path);
> -static int ext4_quota_off(struct super_block *sb, int type);
> static int ext4_quota_on_mount(struct super_block *sb, int type);
> static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
> 			       size_t len, loff_t off);
> @@ -5344,11 +5365,28 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
> 		if (err)
> 			return err;
> 	}
> +
> 	lockdep_set_quota_inode(path->dentry->d_inode, I_DATA_SEM_QUOTA);
> 	err = dquot_quota_on(sb, type, format_id, path);
> -	if (err)
> +	if (err) {
> 		lockdep_set_quota_inode(path->dentry->d_inode,
> 					     I_DATA_SEM_NORMAL);
> +	} else {
> +		struct inode *inode = d_inode(path->dentry);
> +		handle_t *handle;
> +
> +		inode_lock(inode);
> +		handle = ext4_journal_start(inode, EXT4_HT_QUOTA, 1);
> +		if (IS_ERR(handle))
> +			goto unlock_inode;
> +		EXT4_I(inode)->i_flags |= EXT4_NOATIME_FL | EXT4_IMMUTABLE_FL;
> +		inode_set_flags(inode, S_NOATIME | S_IMMUTABLE,
> +				S_NOATIME | S_IMMUTABLE);
> +		ext4_mark_inode_dirty(handle, inode);
> +		ext4_journal_stop(handle);

Should this be conditional on these flags not already being set?  Otherwise
it dirties the filesystem on every mount even if it isn't needed.

> +	unlock_inode:
> +		inode_unlock(inode);
> +	}
> 	return err;
> }
> 
> @@ -5422,24 +5460,36 @@ static int ext4_quota_off(struct super_block *sb, int type)
> {
> 	struct inode *inode = sb_dqopt(sb)->files[type];
> 	handle_t *handle;
> +	int err;
> 
> 	/* Force all delayed allocation blocks to be allocated.
> 	 * Caller already holds s_umount sem */
> 	if (test_opt(sb, DELALLOC))
> 		sync_filesystem(sb);
> 
> -	if (!inode)
> +	if (!inode || !igrab(inode))
> 		goto out;
> 
> +	err = dquot_quota_off(sb, type);
> +	if (err)
> +		goto out_put;
> +
> +	inode_lock(inode);
> 	/* Update modification times of quota files when userspace can
> 	 * start looking at them */
> 	handle = ext4_journal_start(inode, EXT4_HT_QUOTA, 1);
> 	if (IS_ERR(handle))
> -		goto out;
> +		goto out_unlock;
> +	EXT4_I(inode)->i_flags &= ~(EXT4_NOATIME_FL | EXT4_IMMUTABLE_FL);
> +	inode_set_flags(inode, 0, S_NOATIME | S_IMMUTABLE);

It isn't obvious that we need to clear these flags at every unmount?  I
don't think there is a good reason to be modifying the quota files from
userspace, and e2fsck won't care about these flags anyway when fixing
the quota files.

> 	inode->i_mtime = inode->i_ctime = current_time(inode);
> 	ext4_mark_inode_dirty(handle, inode);
> 	ext4_journal_stop(handle);
> -
> +out_unlock:
> +	inode_unlock(inode);
> +out_put:
> +	iput(inode);
> +	return err;
> out:
> 	return dquot_quota_off(sb, type);
> }
> --
> 2.12.0
> 


Cheers, Andreas






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