This is a note to let you know that I've just added the patch titled
block: loop: fix filesystem corruption in case of aio/dio
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
block-loop-fix-filesystem-corruption-in-case-of-aio-dio.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a7297a6a3a3322b054592e8e988981d2f5f29cc4 Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Date: Fri, 15 Apr 2016 18:51:28 +0800
Subject: block: loop: fix filesystem corruption in case of aio/dio
From: Ming Lei <ming.lei@xxxxxxxxxxxxx>
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@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
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;
Patches currently in stable-queue which might be from ming.lei@xxxxxxxxxxxxx are
queue-4.4/block-partition-initialize-percpuref-before-sending-out-kobj_add.patch
queue-4.4/block-loop-fix-filesystem-corruption-in-case-of-aio-dio.patch
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