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 <keith.busch@intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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;