Re: [PATCH 3/3] staging: erofs: support IO read error injection

[Chao Yu]

On 2019/3/19 21:55, Gao Xiang wrote:
> Used to simulate disk IO read error for testing fatal
> error tolerance.
> 
> Here are the details,
> 1) use bio->bi_private to indicate super_block
>    for non-compressed bios since some (mainly meta)
>    pages can be of the corresponding bdev inode;
> 2) get super_block dynamically for compressed bios,
>    therefore it could not inject bios full of staging
>    pages, yet it doesn't affect the normal usage.
> 
> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> ---
>  drivers/staging/erofs/Documentation/filesystems/erofs.txt |  1 +
>  drivers/staging/erofs/data.c                              | 10 +++++++++-
>  drivers/staging/erofs/internal.h                          |  3 ++-
>  drivers/staging/erofs/super.c                             |  3 ++-
>  drivers/staging/erofs/unzip_vle.c                         | 10 ++++++++--
>  5 files changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/erofs/Documentation/filesystems/erofs.txt b/drivers/staging/erofs/Documentation/filesystems/erofs.txt
> index 961ec4da7705..74cf84ac48a3 100644
> --- a/drivers/staging/erofs/Documentation/filesystems/erofs.txt
> +++ b/drivers/staging/erofs/Documentation/filesystems/erofs.txt
> @@ -60,6 +60,7 @@ fault_injection=%d     Enable fault injection in all supported types with
>                         specified injection rate. Supported injection type:
>                         Type_Name                Type_Value
>                         FAULT_KMALLOC            0x000000001
> +                       FAULT_READ_IO            0x000000002
>  (no)user_xattr         Setup Extended User Attributes. Note: xattr is enabled
>                         by default if CONFIG_EROFS_FS_XATTR is selected.
>  (no)acl                Setup POSIX Access Control List. Note: acl is enabled
> diff --git a/drivers/staging/erofs/data.c b/drivers/staging/erofs/data.c
> index 526e0dbea5b5..16302ee54261 100644
> --- a/drivers/staging/erofs/data.c
> +++ b/drivers/staging/erofs/data.c
> @@ -17,11 +17,17 @@
>  
>  static inline void read_endio(struct bio *bio)
>  {
> +	struct super_block *const sb = bio->bi_private;
>  	int i;
>  	struct bio_vec *bvec;
> -	const blk_status_t err = bio->bi_status;
> +	blk_status_t err = bio->bi_status;
>  	struct bvec_iter_all iter_all;
>  
> +	if (time_to_inject(EROFS_SB(sb), FAULT_READ_IO)) {
> +		erofs_show_injection_info(FAULT_READ_IO);
> +		err = BLK_STS_IOERR;
> +	}
> +
>  	bio_for_each_segment_all(bvec, bio, i, iter_all) {
>  		struct page *page = bvec->bv_page;
>  
> @@ -69,6 +75,7 @@ struct page *__erofs_get_meta_page(struct super_block *sb,
>  			err = PTR_ERR(bio);
>  			goto err_out;
>  		}
> +		bio->bi_private = sb;

Will it be better to initialize bio's field in erofs_grab_bio()?

>  
>  		err = bio_add_page(bio, page, PAGE_SIZE, 0);
>  		if (unlikely(err != PAGE_SIZE)) {
> @@ -288,6 +295,7 @@ static inline struct bio *erofs_read_raw_page(struct bio *bio,
>  			bio = NULL;
>  			goto err_out;
>  		}
> +		bio->bi_private = inode->i_sb;

Ditto.

Thanks,

>  	}
>  
>  	err = bio_add_page(bio, page, PAGE_SIZE, 0);
> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> index ba1d86f3470e..5d7addd9cff0 100644
> --- a/drivers/staging/erofs/internal.h
> +++ b/drivers/staging/erofs/internal.h
> @@ -44,11 +44,12 @@
>  
>  enum {
>  	FAULT_KMALLOC,
> +	FAULT_READ_IO,
>  	FAULT_MAX,
>  };
>  
>  #ifdef CONFIG_EROFS_FAULT_INJECTION
> -extern char *erofs_fault_name[FAULT_MAX];
> +extern const char *erofs_fault_name[FAULT_MAX];
>  #define IS_FAULT_SET(fi, type) ((fi)->inject_type & (1 << (type)))
>  
>  struct erofs_fault_info {
> diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
> index 15c784fba879..ce025e6e4399 100644
> --- a/drivers/staging/erofs/super.c
> +++ b/drivers/staging/erofs/super.c
> @@ -141,8 +141,9 @@ static int superblock_read(struct super_block *sb)
>  }
>  
>  #ifdef CONFIG_EROFS_FAULT_INJECTION
> -char *erofs_fault_name[FAULT_MAX] = {
> +const char *erofs_fault_name[FAULT_MAX] = {
>  	[FAULT_KMALLOC]		= "kmalloc",
> +	[FAULT_READ_IO]		= "read IO error",
>  };
>  
>  static void __erofs_build_fault_attr(struct erofs_sb_info *sbi,
> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
> index d05fed4f8013..9fabdf596438 100644
> --- a/drivers/staging/erofs/unzip_vle.c
> +++ b/drivers/staging/erofs/unzip_vle.c
> @@ -843,8 +843,8 @@ static void z_erofs_vle_unzip_kickoff(void *ptr, int bios)
>  
>  static inline void z_erofs_vle_read_endio(struct bio *bio)
>  {
> -	const blk_status_t err = bio->bi_status;
>  	struct erofs_sb_info *sbi = NULL;
> +	blk_status_t err = bio->bi_status;
>  	unsigned int i;
>  	struct bio_vec *bvec;
>  	struct bvec_iter_all iter_all;
> @@ -856,9 +856,15 @@ static inline void z_erofs_vle_read_endio(struct bio *bio)
>  		DBG_BUGON(PageUptodate(page));
>  		DBG_BUGON(!page->mapping);
>  
> -		if (unlikely(!sbi && !z_erofs_is_stagingpage(page)))
> +		if (unlikely(!sbi && !z_erofs_is_stagingpage(page))) {
>  			sbi = EROFS_SB(page->mapping->host->i_sb);
>  
> +			if (time_to_inject(sbi, FAULT_READ_IO)) {
> +				erofs_show_injection_info(FAULT_READ_IO);
> +				err = BLK_STS_IOERR;
> +			}
> +		}
> +
>  		/* sbi should already be gotten if the page is managed */
>  		if (sbi)
>  			cachemngd = erofs_page_is_managed(sbi, page);
>