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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Zheng Bin <zhengbin13@huawei.com>, Christoph Hellwig <hch@lst.de>,
        Bart Van Assche <bvanassche@acm.org>,
        Jens Axboe <axboe@kernel.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH 4.19 057/131] loop: replace kill_bdev with invalidate_bdev
Date:   Mon, 29 Jun 2020 11:33:48 -0400
Message-Id: <20200629153502.2494656-58-sashal@kernel.org>
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From: Zheng Bin <zhengbin13@huawei.com>

commit f4bd34b139a3fa2808c4205f12714c65e1548c6c upstream.

When a filesystem is mounted on a loop device and on a loop ioctl
LOOP_SET_STATUS64, because of kill_bdev, buffer_head mappings are getting
destroyed.
kill_bdev
  truncate_inode_pages
    truncate_inode_pages_range
      do_invalidatepage
        block_invalidatepage
          discard_buffer  -->clear BH_Mapped flag

sb_bread
  __bread_gfp
  bh = __getblk_gfp
  -->discard_buffer clear BH_Mapped flag
  __bread_slow
    submit_bh
      submit_bh_wbc
        BUG_ON(!buffer_mapped(bh))  --> hit this BUG_ON

Fixes: 5db470e229e2 ("loop: drop caches if offset or block_size are changed")
Signed-off-by: Zheng Bin <zhengbin13@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/block/loop.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index c1341c86bcded..728681a20b7f4 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1238,7 +1238,7 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
 	if (lo->lo_offset != info->lo_offset ||
 	    lo->lo_sizelimit != info->lo_sizelimit) {
 		sync_blockdev(lo->lo_device);
-		kill_bdev(lo->lo_device);
+		invalidate_bdev(lo->lo_device);
 	}
 
 	/* I/O need to be drained during transfer transition */
@@ -1512,12 +1512,12 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
 
 	if (lo->lo_queue->limits.logical_block_size != arg) {
 		sync_blockdev(lo->lo_device);
-		kill_bdev(lo->lo_device);
+		invalidate_bdev(lo->lo_device);
 	}
 
 	blk_mq_freeze_queue(lo->lo_queue);
 
-	/* kill_bdev should have truncated all the pages */
+	/* invalidate_bdev should have truncated all the pages */
 	if (lo->lo_queue->limits.logical_block_size != arg &&
 			lo->lo_device->bd_inode->i_mapping->nrpages) {
 		err = -EAGAIN;
-- 
2.25.1