4.5-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ming Lei <[email protected]> commit a7297a6a3a3322b054592e8e988981d2f5f29cc4 upstream. Starting from commit e36f620428(block: split bios to max possible length), block core starts to split bio in the middle of bvec. Unfortunately loop dio/aio doesn't consider this situation, and always treat 'iter.iov_offset' as zero. Then filesystem corruption is observed. This patch figures out the offset of the base bvevc via 'bio->bi_iter.bi_bvec_done' and fixes the issue by passing the offset to iov iterator. Fixes: e36f6204288088f (block: split bios to max possible length) Cc: Keith Busch <[email protected]> Cc: Al Viro <[email protected]> Signed-off-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/block/loop.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -488,6 +488,12 @@ static int lo_rw_aio(struct loop_device bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, bio_segments(bio), blk_rq_bytes(cmd->rq)); + /* + * This bio may be started from the middle of the 'bvec' + * because of bio splitting, so offset from the bvec must + * be passed to iov iterator + */ + iter.iov_offset = bio->bi_iter.bi_bvec_done; cmd->iocb.ki_pos = pos; cmd->iocb.ki_filp = file;
