6.4-stable review patch. If anyone has any objections, please let me know.
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From: Gao Xiang hsiangkao@linux.alibaba.com
commit e4c1cf523d820730a86cae2c6d55924833b6f7ac upstream.
This was accidentally fixed up in commit e4c1cf523d82 but we can't take the full change due to other dependancy issues, so here is just the actual bugfix that is needed.
[Background]
keltargw reported an issue [1] that with mmaped I/Os, sometimes the tail of the last page (after file ends) is not filled with zeroes.
The root cause is that such tail page could be wrongly selected for inplace I/Os so the zeroed part will then be filled with compressed data instead of zeroes.
A simple fix is to avoid doing inplace I/Os for such tail parts, actually that was already fixed upstream in commit e4c1cf523d82 ("erofs: tidy up z_erofs_do_read_page()") by accident.
[1] https://lore.kernel.org/r/3ad8b469-25db-a297-21f9-75db2d6ad224@linux.alibaba...
Reported-by: keltargw keltar.gw@gmail.com Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support") Signed-off-by: Gao Xiang hsiangkao@linux.alibaba.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/erofs/zdata.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -993,6 +993,8 @@ hitted: cur = end - min_t(erofs_off_t, offset + end - map->m_la, end); if (!(map->m_flags & EROFS_MAP_MAPPED)) { zero_user_segment(page, cur, end); + ++spiltted; + tight = false; goto next_part; } if (map->m_flags & EROFS_MAP_FRAGMENT) {