[PATCH 4.19 057/131] loop: replace kill_bdev with invalidate_bdev

Sasha Levin
2020-06-29T20:08:05Z

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