Re: [PATCH v2 2/6] ext4: submit mapped buffers when io_end_vec allocation fails

[sashiko-bot@kernel.org]

> When the filesystem block size is smaller than the folio size, a folio
> can contain discontiguous unwritten ranges. mpage_process_folio() records
> a mapped range for conversion before allocating an io_end_vec for the
> next range.
> 
> If that allocation fails, mpage_map_and_submit_buffers() returns before
> submitting the folio. Its caller skips partial-folio submission, leaving
> the recorded range in io_end. Completion can then convert the range to
> written without writing its data, allowing reads to return stale disk
> contents.
> 
> Pass progress into buffer processing and set it as buffer mappings are
> updated. Route errors after such progress through the existing
> partial-folio submission path, so the mapped buffers are submitted before
> io_end completion. Buffers still requiring mapping remain dirty for retry.
> 
> Fixes: 4d06bfb97ecb ("ext4: Add error handling for io_end_vec struct allocation")
> Cc: stable@vger.kernel.org
> Signed-off-by: Julian Sun <sunjunchao@bytedance.com>

Sashiko has reviewed this patch and found no issues.

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