f2fs: only redirty pinned folios in redirty_blocks

redirty_blocks() pins folios with read_cache_folio() and then walks the
same range again with filemap_lock_folio() to redirty them and drop the
references it took.

Commit 5951fee46bef ("f2fs: Use a folio in redirty_blocks()") changed
the second pass to a do/while loop. If read_cache_folio() fails before
anything is pinned, page_idx does not advance but the cleanup loop still
runs once.

If readahead has already populated the failed folio in page cache, that
extra iteration finds it and folio_put_refs(folio, 2) drops one
reference too many. Later drop_caches or reclaim can then report
"BUG: Bad page state".

Only redirty the range that was pinned successfully.

Fixes: 5951fee46bef ("f2fs: Use a folio in redirty_blocks()")
Cc: stable@kernel.org
Assisted-by: Codex:gpt-5.5
Signed-off-by: Wenjie Qi <qiwenjie@xiaomi.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

0 files changed, 0 insertions, 0 deletions