Re: configurable block error injection v5

[Haris Iqbal <haris.iqbal@linux.dev>]

On 6/11/26 16:06, Christoph Hellwig wrote:
> Hi all,
> 
> this series adds a new configurable block error injection facility.
> We already have a few to inject block errors, but unfortunately most
> of them are either not very useful or hard to use, or both:
> 
>   - The fail_make_request failure injection point can't distinguish
>     different commands, different ranges in the file and can only injection
>     plain I/O errors.
>   - the should_fail_bio 'dynamic' failure injection has all the same issues
>     as fail_make_request
>   - dm-error can only fail all command in the table using BLK_STS_IOERR
>     and requires setting up a new block device
>   - dm-flakey and dm-dust allow all kinds of configurability, but still
>     don't have good error selection, no good support for non-read/write
>     commands and are limited to the dm table alignment requirements,
>     which for zoned devices enforces setting them up for an entire zone.
>     They also once again require setting up a stacked block device,
>     which is really annoying in harnesses like xfstests
> 
> This series adds a new debugfs-based block layer error injection
> that allows to configure what operations and ranges the injection
> applied to, and what status to return.  It also allows to configure a
> failure ratio similar to the xfs errortag injection.
> 
> Changes since v4:
>   - don't unlock in removeall to avoid a race between removeall and setup
>   - document why we can't match 0-sized bios
> 
> Changes since v3:
>   - use a static branch to guard the new condition
>   - split out a new header so that jump_label.h doesn't get pulled into
>     blk.h
>   - more checking for impossible conditions in blk_status_to_tag
>   - more spelling fixes
> 
> Changes since v2:
>   - improve the documentation a bit
>   - fix a spelling mistake in a comment
> 
> Changes since v1:
>   - drop the should_fail_bio removal and cleanup depending on it, as it's
>     used by eBPF programs and thus a hidden UABI.
>   - as a result split the code out to it's own Kconfig symbol
>   - various error handling fixed pointed out by Keith
>   - documentation spelling fixes pointed out by Randy
> 
> Diffstat:
>   Documentation/block/error-injection.rst |   59 +++++
>   Documentation/block/index.rst           |    1
>   block/Kconfig                           |    8
>   block/Makefile                          |    1
>   block/blk-core.c                        |   87 ++++++--
>   block/blk-sysfs.c                       |    5
>   block/blk.h                             |    3
>   block/error-injection.c                 |  315 ++++++++++++++++++++++++++++++++
>   block/error-injection.h                 |   21 ++
>   block/genhd.c                           |    4
>   include/linux/blkdev.h                  |    6
>   11 files changed, 490 insertions(+), 20 deletions(-)

Thank you for this series. It is a nice addition.


Reviewed-by: Md Haris Iqbal <haris.iqbal@linux.dev>
(for the whole series)

>