[PATCH v3] erofs: support STATX_DIOALIGN

[Gao Xiang]

On 2024/7/18 16:32, Gao Xiang wrote:
> From: Hongbo Li via Linux-erofs <linux-erofs at lists.ozlabs.org>

Also I will fix the email address issue
(Hongbo Li <lihongbo22 at huawei.com>) when applying too.

> 
> Add support for STATX_DIOALIGN to erofs, so that direct I/O
> alignment restrictions are exposed to userspace in a generic
> way.
> 
> [Before]
> ```
> ./statx_test /mnt/erofs/testfile
> statx(/mnt/erofs/testfile) = 0
> dio mem align:0
> dio offset align:0
> ```
> 
> [After]
> ```
> ./statx_test /mnt/erofs/testfile
> statx(/mnt/erofs/testfile) = 0
> dio mem align:512
> dio offset align:512
> ```
> 
> Signed-off-by: Hongbo Li <lihongbo22 at huawei.com>
> Signed-off-by: Gao Xiang <hsiangkao at linux.alibaba.com>
> ---
> Hi Hongbo,
> 
> I tidy up the patch a bit according to the current codebase,
> I will apply this later for this cycle.
> 
> Also r-v-bs are always welcome...
> 
> Thanks,
> Gao Xiang
> 
>   fs/erofs/inode.c | 19 +++++++++++++++++--
>   1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index 5f6439a63af7..43c09aae2afc 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -334,14 +334,29 @@ int erofs_getattr(struct mnt_idmap *idmap, const struct path *path,
>   		  unsigned int query_flags)
>   {
>   	struct inode *const inode = d_inode(path->dentry);
> +	bool compressed =
> +		erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout);
>   
> -	if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout))
> +	if (compressed)
>   		stat->attributes |= STATX_ATTR_COMPRESSED;
> -
>   	stat->attributes |= STATX_ATTR_IMMUTABLE;
>   	stat->attributes_mask |= (STATX_ATTR_COMPRESSED |
>   				  STATX_ATTR_IMMUTABLE);
>   
> +	/*
> +	 * Return the DIO alignment restrictions if requested.
> +	 *
> +	 * In EROFS, STATX_DIOALIGN is not supported in ondemand mode and
> +	 * compressed files, so in these cases we report no DIO support.
> +	 */
> +	if ((request_mask & STATX_DIOALIGN) && S_ISREG(inode->i_mode)) {
> +		stat->result_mask |= STATX_DIOALIGN;
> +		if (!erofs_is_fscache_mode(inode->i_sb) && !compressed) {
> +			stat->dio_mem_align =
> +				bdev_logical_block_size(inode->i_sb->s_bdev);
> +			stat->dio_offset_align = stat->dio_mem_align;
> +		}
> +	}
>   	generic_fillattr(idmap, request_mask, inode, stat);
>   	return 0;
>   }