Re: [PATCH v2] f2fs: fix to round down start offset of fallocate for pin file

[Chao Yu <chao@kernel.org>]

On 6/22/26 13:28, Sunmin Jeong wrote:
> Currently, the length of fallocate for pin file is section-aligned to
> keep allocated sections from being selected as victims of GC. However,
> for the case that the start offset of fallocate is not aligned in
> section, the allocated sections can't be fully utilized. It's because a
> new section is allocated by f2fs_allocate_pinning_section() after using
> blks_per_sec blocks regardless of the start offset. As a result, several
> unexpected dirty segments may be created, including blocks assigned to
> the pinned file.
> 
> To address this issue, let's round down the start offset of fallocate
> to the length of section.
> 
> The reproducing scenario is as below
> 
> chunk=$(((2<<20)+4096)) # 2MB + 4KB
> touch test
> f2fs_io pinfile set test
> f2fs_io fallocate 0 0 $chunk test
> f2fs_io fallocate 0 $chunk $chunk test
> f2fs_io fallocate 0 $((chunk*2)) $chunk test
> f2fs_io fiemap 0 $((chunk*3)) test
> 
> Fiemap: offset = 0 len = 12288
>     logical addr.    physical addr.   length           flags
> 0   0000000000000000 000000068c600000 0000000000400000 00001088
> 1   0000000000400000 000000003d400000 0000000000001000 00001088
> 2   0000000000401000 00000003eb200000 0000000000200000 00001088
> 3   0000000000601000 00000005e4200000 0000000000001000 00001088
> 4   0000000000602000 0000000605400000 0000000000200000 00001089
> 
> Cc: stable@vger.kernel.org
> Fixes: f5a53edcf01e ("f2fs: support aligned pinned file")
> Reviewed-by: Yunji Kang <yunji0.kang@samsung.com>
> Reviewed-by: Yeongjin Gil <youngjin.gil@samsung.com>
> Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
> Signed-off-by: Sunmin Jeong <s_min.jeong@samsung.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,