iomap: correct the range of a partial dirty clear

The block range calculation in ifs_clear_range_dirty() is incorrect when
partially clearing a range in a folio. We cannot clear the dirty bit of
the first block or the last block if the start or end offset is not
blocksize-aligned. This has not yet caused any issues since we always
clear a whole folio in iomap_writeback_folio().

Fix this by rounding up the first block to blocksize alignment, and
calculate the last block by rounding down (using truncation). Correct
the nr_blks calculation accordingly.

Fixes: 4ce02c679722 ("iomap: Add per-block dirty state tracking to improve performance")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20260714082325.325163-2-yi.zhang@huaweicloud.com
Reviewed-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions