On Fri, Mar 05, 2021 at 05:58:40PM +0800, Huang Jianan via Linux-erofs wrote:
> z_erofs_decompressqueue_endio may not be executed in the atomic
> context, for example, when dm-verity is turned on. In this scenario,
> data can be decompressed directly to get rid of additional kworker
> scheduling overhead. Also, it makes no sense to apply synchronous
> decompression for such case.
>
> Signed-off-by: Huang Jianan <[email protected]>
> Signed-off-by: Guo Weichao <[email protected]>
> ---
> fs/erofs/internal.h | 2 ++
> fs/erofs/super.c | 1 +
> fs/erofs/zdata.c | 16 +++++++++++++---
> 3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 67a7ec945686..e325da7be237 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -53,6 +53,8 @@ struct erofs_fs_context {
>
> /* threshold for decompression synchronously */
> unsigned int max_sync_decompress_pages;
> + /* decide whether to decompress synchronously */
> + bool readahead_sync_decompress;
I updated this as below:
/* current strategy of how to use managed cache */
unsigned char cache_strategy;
+ /* strategy of sync decompression (false - auto, true - force on) */
+ bool readahead_sync_decompress;
/* threshold for decompression synchronously */
unsigned int max_sync_decompress_pages;
> #endif
> unsigned int mount_opt;
> };
...
> @@ -720,8 +723,14 @@ static void z_erofs_decompress_kickoff(struct
> z_erofs_decompressqueue *io,
> return;
> }
>
> - if (!atomic_add_return(bios, &io->pending_bios))
> - queue_work(z_erofs_workqueue, &io->u.work);
> + if (!atomic_add_return(bios, &io->pending_bios)) {
> + if (in_atomic() || irqs_disabled()) {
> + queue_work(z_erofs_workqueue, &io->u.work);
> + sbi->ctx.readahead_sync_decompress = true;
> + } else {
> + z_erofs_decompressqueue_work(&io->u.work);
> + }
> + }
Also updated this as below to return as early as possible:
- if (!atomic_add_return(bios, &io->pending_bios))
+ if (atomic_add_return(bios, &io->pending_bios))
+ return;
+ /* Use workqueue and sync decompression for atomic contexts only */
+ if (in_atomic() || irqs_disabled()) {
queue_work(z_erofs_workqueue, &io->u.work);
+ sbi->ctx.readahead_sync_decompress = true;
+ return;
+ }
+ z_erofs_decompressqueue_work(&io->u.work);
}
Otherwise, it looks good to me. I've applied to dev-test
for preliminary testing.
Reviewed-by: Gao Xiang <[email protected]>
Thanks,
Gao Xiang
