Patch "block: loop: fix filesystem corruption in case of aio/dio" has been added to the 4.5-stable tree

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 4.5-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-4.5 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ming Lei <[email protected]>
Date: Fri, 15 Apr 2016 18:51:28 +0800
Subject: block: loop: fix filesystem corruption in case of aio/dio

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.

---
 drivers/block/loop.c |    6 ++++++
 1 file changed, 6 insertions(+)

@@ -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;

Patches currently in stable-queue which might be from [email protected] are

queue-4.5/block-partition-initialize-percpuref-before-sending-out-kobj_add.patch queue-4.5/block-loop-fix-filesystem-corruption-in-case-of-aio-dio.patch