linux-kernel - Re: [PATCH v3 3/4] ext4: Support setting FMODE_CAN_ATOMIC

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Message-ID: <20241031214256.GE21832@frogsfrogsfrogs>
Date: Thu, 31 Oct 2024 14:42:56 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>
Cc: linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
	Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>,
	John Garry <john.g.garry@...cle.com>,
	Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
	Dave Chinner <david@...morbit.com>, linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] ext4: Support setting FMODE_CAN_ATOMIC_WRITE

On Wed, Oct 30, 2024 at 09:27:40PM +0530, Ritesh Harjani (IBM) wrote:
> FS needs to add the fmode capability in order to support atomic writes
> during file open (refer kiocb_set_rw_flags()). Set this capability on
> a regular file if ext4 can do atomic write.
> 
> Reviewed-by: John Garry <john.g.garry@...cle.com>
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
> ---
>  fs/ext4/file.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index a7b9b9751a3f..8116bd78910b 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -898,6 +898,9 @@ static int ext4_file_open(struct inode *inode, struct file *filp)
>  			return ret;
>  	}
>  
> +	if (S_ISREG(inode->i_mode) && ext4_can_atomic_write(inode->i_sb))

Modulo my comment earlier about ext4_can_atomic_write, this looks ok to
me.  With either variant, I say:
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> +		filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
> +
>  	filp->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
>  	return dquot_file_open(inode, filp);
>  }
> -- 
> 2.46.0
> 
>