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From: Jan Kara <jack@suse.cz>
To: ira.weiny@intel.com
Cc: linux-ext4@vger.kernel.org,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
	Eric Biggers <ebiggers@kernel.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>, Jeff Moyer <jmoyer@redhat.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH V4 7/8] fs/ext4: Introduce DAX inode flag
Date: Fri, 22 May 2020 13:48:48 +0200
Message-ID: <20200522114848.GC14199@quack2.suse.cz> (raw)
In-Reply-To: <20200521191313.261929-8-ira.weiny@intel.com>

On Thu 21-05-20 12:13:12, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> Add a flag to preserve FS_XFLAG_DAX in the ext4 inode.
> 
> Set the flag to be user visible and changeable.  Set the flag to be
> inherited.  Allow applications to change the flag at any time with the
> exception of if VERITY or ENCRYPT is set.
> 
> Disallow setting VERITY or ENCRYPT if DAX is set.
> 
> Finally, on regular files, flag the inode to not be cached to facilitate
> changing S_DAX on the next creation of the inode.
> 
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>

...

> @@ -303,6 +318,16 @@ static int ext4_ioctl_setflags(struct inode *inode,
>  	unsigned int jflag;
>  	struct super_block *sb = inode->i_sb;
>  
> +	if (ext4_test_inode_flag(inode, EXT4_INODE_DAX)) {
> +		if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY) ||
> +		    ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT) ||
> +		    ext4_test_inode_state(inode,
> +					  EXT4_STATE_VERITY_IN_PROGRESS)) {
> +			err = -EOPNOTSUPP;
> +			goto flags_out;
> +		}
> +	}

The way this check is implemented wouldn't IMO do what we need... It
doesn't check the flags that are being set but just the current inode
state. I think it should rather be:

	if ((flags ^ oldflags) & EXT4_INODE_DAX_FL) {
		...
	}

And perhaps move this to a place in ext4_ioctl_setflags() where we check
other similar conflicts.

And then we should check conflicts with the journal flag as well, as I
mentioned in reply to the first patch. There it is more complicated by the
fact that we should disallow setting of both EXT4_INODE_DAX_FL and
EXT4_JOURNAL_DATA_FL at the same time so the checks will be somewhat more
complicated.

								Honza

> +
>  	/* Is it quota file? Do not allow user to mess with it */
>  	if (ext4_is_quota_file(inode))
>  		goto flags_out;
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-21 19:13 [PATCH V4 0/8] Enable ext4 support for per-file/directory DAX operations ira.weiny
2020-05-21 19:13 ` [PATCH V4 1/8] fs/ext4: Narrow scope of DAX check in setflags ira.weiny
2020-05-22  7:58   ` Jan Kara
2020-05-21 19:13 ` [PATCH V4 2/8] fs/ext4: Disallow verity if inode is DAX ira.weiny
2020-05-21 19:13 ` [PATCH V4 3/8] fs/ext4: Change EXT4_MOUNT_DAX to EXT4_MOUNT_DAX_ALWAYS ira.weiny
2020-05-21 19:13 ` [PATCH V4 4/8] fs/ext4: Update ext4_should_use_dax() ira.weiny
2020-05-22 10:41   ` Jan Kara
2020-05-21 19:13 ` [PATCH V4 5/8] fs/ext4: Only change S_DAX on inode load ira.weiny
2020-05-21 19:13 ` [PATCH V4 6/8] fs/ext4: Make DAX mount option a tri-state ira.weiny
2020-05-21 19:13 ` [PATCH V4 7/8] fs/ext4: Introduce DAX inode flag ira.weiny
2020-05-22 11:48   ` Jan Kara [this message]
2020-05-25  4:39     ` Ira Weiny
2020-05-25  7:28       ` Jan Kara
2020-05-23  5:13   ` Andreas Dilger
2020-05-21 19:13 ` [PATCH V4 8/8] Documentation/dax: Update DAX enablement for ext4 ira.weiny

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