Re: [PATCH v13 0/3] md/md-bitmap: restore bitmap grow through sysfs

["Yu Kuai" <yukuai@fnnas.com>]

Hi,

Please just ignore the v13, it's local version by ai that I forgot to remove.

在 2026/4/25 10:46, Yu Kuai 写道:
> mdadm --grow adds an internal bitmap by writing bitmap/location for an
> array that currently has no bitmap. That requires the bitmap directory
> and location attribute to exist before the classic bitmap backend is
> created.
>
> This series separates bitmap backend lifetime from bitmap sysfs lifetime,
> splits the sysfs layout into common and backend-specific groups, and adds
> a small "none" bitmap backend. The none backend keeps bitmap/location
> available while no real bitmap is active, and the location store path can
> then switch between the none backend and the classic bitmap backend
> without tearing down the common bitmap sysfs directory.
>
> Patch 1 factors bitmap creation and destruction into helpers that do not
> touch sysfs registration.
>
> Patch 2 splits the classic bitmap sysfs files into a common group and an
> internal-bitmap group, and converts bitmap backend operations to use a
> sysfs group array.
>
> Patch 3 adds the none backend and uses it to restore mdadm --grow bitmap
> addition through bitmap/location.
>
> Changes since v12:
> - Keep the factoring patch focused on no-sysfs bitmap lifetime helpers.
> - Make bitmap operation lookup depend only on the current bitmap id
>    matching the installed backend.
> - Trim the none backend to only the operations required by the active
>    call paths.
> - Rework bitmap/location error handling with explicit cleanup labels.
> - Restore the none backend after bitmap removal and creation/load
>    failures so bitmap/location stays available.
>
> Validation:
>    - create a RAID1 array with --bitmap=none
>    - verify /sys/block/md0/md/bitmap/location exists and reports "none"
>    - mdadm --grow /dev/md0 --bitmap=internal
>    - verify location switches to "+8", mdadm reports "Intent Bitmap:
>      Internal", and /proc/mdstat reports a bitmap
>    - mdadm --grow /dev/md0 --bitmap=none
>    - verify location switches back to "none" and only the common location
>      attribute remains under md/bitmap
>    - repeat the internal/none switch once more
> - Checked the QEMU serial log for panic, Oops, BUG, WARNING, Call Trace,
>    RCU stall, and hung-task patterns; none were found.
>
> Yu Kuai (3):
>    md: factor bitmap creation away from sysfs handling
>    md/md-bitmap: split bitmap sysfs groups
>    md/md-bitmap: add a none backend for bitmap grow
>
>   drivers/md/md-bitmap.c   | 131 +++++++++++++++++++++++++++++++++++----
>   drivers/md/md-bitmap.h   |   2 +-
>   drivers/md/md-llbitmap.c |   7 ++-
>   drivers/md/md.c          | 125 ++++++++++++++++++++++++++-----------
>   drivers/md/md.h          |   3 +
>   5 files changed, 218 insertions(+), 50 deletions(-)
>
> base-commit: c85d314b135ff569c1031f2ef8e40368bcfe72ac

-- 
Thansk,
Kuai