On 19/7/31 21:06, Xiaoguang Wang wrote:
> Mount with both dioread_nolock and nodelalloc will result in huge
> performance drop, which indeed is an known issue, so before we fix
> this issue, currently we disable this behaviour. Below test reproducer
> can reveal this performance drop.
>
> mount -o remount,dioread_nolock,delalloc /dev/vdb1
> rm -f testfile
> start_time=$(date +%s)
> dd if=/dev/zero of=testfile bs=4096 count=$((1024*256))
> sync
> end_time=$(date +%s)
> echo $((end_time - start_time))
>
> mount -o remount,dioread_nolock,nodelalloc /dev/vdb1
> rm -f testfile
> start_time=$(date +%s)
> dd if=/dev/zero of=testfile bs=4096 count=$((1024*256))
> sync
> end_time=$(date +%s)
> echo $((end_time - start_time))
>
> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
> ---
> fs/ext4/super.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 4079605d437a..1a2b2c0cd1b8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -2098,6 +2098,12 @@ static int parse_options(char *options, struct super_block *sb,
> int blocksize =
> BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
>
> + if (!test_opt(sb, DELALLOC)) {
> + ext4_msg(sb, KERN_ERR, "can't mount with "
> + "both dioread_nolock and nodelalloc");
> + return 0;
> + }
> +
I suggest move it down to keep blocksize check logic together.
Other than that, looks good to me.
Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
> if (blocksize < PAGE_SIZE) {
> ext4_msg(sb, KERN_ERR, "can't mount with "
> "dioread_nolock if block size != PAGE_SIZE");
>
