| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 002/163] block: loop: fix filesystem corruption in case of aio/dio | Date | Mon, 2 May 2016 17:10:30 -0700 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei <ming.lei@canonical.com>
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>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 423f4ca7d712..80cf8add46ff 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -488,6 +488,12 @@ static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 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;
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