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SubjectRe: [PATCH v2 2/2] erofs: decompress in endio if possible
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On 2021/3/5 16:08, Huang Jianan 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 <huangjianan@oppo.com>
> Signed-off-by: Guo Weichao <guoweichao@oppo.com>
> ---
> fs/erofs/internal.h | 3 +++
> fs/erofs/super.c | 4 ++++
> fs/erofs/zdata.c | 13 +++++++++++--
> 3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
> index 67a7ec945686..b817cb85d67b 100644
> --- a/fs/erofs/internal.h
> +++ b/fs/erofs/internal.h
> @@ -70,6 +70,9 @@ struct erofs_sb_info {
>
> /* pseudo inode to manage cached pages */
> struct inode *managed_cache;
> +
> + /* decide whether to decompress synchronously */
> + bool readahead_sync_decompress;
> #endif /* CONFIG_EROFS_FS_ZIP */
> u32 blocks;
> u32 meta_blkaddr;
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index d5a6b9b888a5..77819efe9b15 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -175,6 +175,10 @@ static int erofs_read_superblock(struct super_block *sb)
> sbi->root_nid = le16_to_cpu(dsb->root_nid);
> sbi->inos = le64_to_cpu(dsb->inos);
>
> +#ifdef CONFIG_EROFS_FS_ZIP
> + sbi->readahead_sync_decompress = false;
> +#endif
> +
> sbi->build_time = le64_to_cpu(dsb->build_time);
> sbi->build_time_nsec = le32_to_cpu(dsb->build_time_nsec);
>
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 6cb356c4217b..49ffc817dd9e 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -706,6 +706,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
> goto out;
> }
>
> +static void z_erofs_decompressqueue_work(struct work_struct *work);
> static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
> bool sync, int bios)
> {
> @@ -720,8 +721,14 @@ 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->readahead_sync_decompress = true;
> + } else {
> + z_erofs_decompressqueue_work(&io->u.work);
> + }
> + }
> }
>
> static bool z_erofs_page_is_invalidated(struct page *page)
> @@ -1333,6 +1340,8 @@ static void z_erofs_readahead(struct readahead_control *rac)
> struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
>
> unsigned int nr_pages = readahead_count(rac);
> + bool sync = (sbi->readahead_sync_decompress &&
> + nr_pages <= sbi->ctx.max_sync_decompress_pages);
> bool sync = (nr_pages <= sbi->ctx.max_sync_decompress_pages);
sorry for my mistake here, i will send v3 to fix this.
> struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
> struct page *page, *head = NULL;

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