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Date:   Mon, 29 Aug 2022 10:43:04 -0700
From:   Jaegeuk Kim <jaegeuk@kernel.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
        linux-f2fs-devel@lists.sourceforge.net, linux-xfs@vger.kernel.org,
        linux-api@vger.kernel.org, linux-fscrypt@vger.kernel.org,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCH v5 7/8] f2fs: support STATX_DIOALIGN
Message-ID: <Ywz6qH51lzdYy717@google.com>
References: <20220827065851.135710-1-ebiggers@kernel.org>
 <20220827065851.135710-8-ebiggers@kernel.org>
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On 08/26, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Add support for STATX_DIOALIGN to f2fs, so that direct I/O alignment
> restrictions are exposed to userspace in a generic way.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>

> ---
>  fs/f2fs/file.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 8e11311db21060..79177050732803 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -847,6 +847,24 @@ int f2fs_getattr(struct user_namespace *mnt_userns, const struct path *path,
>  		stat->btime.tv_nsec = fi->i_crtime.tv_nsec;
>  	}
>  
> +	/*
> +	 * Return the DIO alignment restrictions if requested.  We only return
> +	 * this information when requested, since on encrypted files it might
> +	 * take a fair bit of work to get if the file wasn't opened recently.
> +	 *
> +	 * f2fs sometimes supports DIO reads but not DIO writes.  STATX_DIOALIGN
> +	 * cannot represent that, so in that case we report no DIO support.
> +	 */
> +	if ((request_mask & STATX_DIOALIGN) && S_ISREG(inode->i_mode)) {
> +		unsigned int bsize = i_blocksize(inode);
> +
> +		stat->result_mask |= STATX_DIOALIGN;
> +		if (!f2fs_force_buffered_io(inode, WRITE)) {
> +			stat->dio_mem_align = bsize;
> +			stat->dio_offset_align = bsize;
> +		}
> +	}
> +
>  	flags = fi->i_flags;
>  	if (flags & F2FS_COMPR_FL)
>  		stat->attributes |= STATX_ATTR_COMPRESSED;
> -- 
> 2.37.2